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1

A reaction-based paradigm to model reactive chemical transport in groundwater with general kinetic and equilibrium reactions  

SciTech Connect

This paper presents a reaction-based water quality transport model in subsurface flow systems. Transport of chemical species with a variety of chemical and physical processes is mathematically described by M partial differential equations (PDEs). Decomposition via Gauss-Jordan column reduction of the reaction network transforms M species reactive transport equations into two sets of equations: a set of thermodynamic equilibrium equations representing NE equilibrium reactions and a set of reactive transport equations of M-NE kinetic-variables involving no equilibrium reactions (a kinetic-variable is a linear combination of species). The elimination of equilibrium reactions from reactive transport equations allows robust and efficient numerical integration. The model solves the PDEs of kinetic-variables rather than individual chemical species, which reduces the number of reactive transport equations and simplifies the reaction terms in the equations. A variety of numerical methods are investigated for solving the coupled transport and reaction equations. Simulation comparisons with exact solutions were performed to verify numerical accuracy and assess the effectiveness of various numerical strategies to deal with different application circumstances. Two validation examples involving simulations of uranium transport in soil columns are presented to evaluate the ability of the model to simulate reactive transport with complex reaction networks involving both kinetic and equilibrium reactions.

Zhang, Fan [ORNL; Yeh, Gour-Tsyh [University of Central Florida, Orlando; Parker, Jack C [ORNL; Brooks, Scott C [ORNL; Pace, Molly [ORNL; Kim, Young Jin [ORNL; Jardine, Philip M [ORNL; Watson, David B [ORNL

2007-01-01T23:59:59.000Z

2

Modeling subsurface contaminant reactions and transport at the watershed scale  

SciTech Connect

The objectives of this research are: (1) to numerically examine the multiscale effects of physical and chemical mass transfer processes on watershed scale, variably saturated subsurface contaminant transport, and (2) to conduct numerical simulations on watershed scale reactive solute transport and evaluate their implications to uncertainty characterization and cost benefit analysis. Concurrent physical and chemical nonequilibrium caused by inter aggregate gradients of pressure head and solute concentration and intra-aggregate geochemical and microbiological processes, respectively, may arise at various scales and flowpaths. To this date, experimental investigations of these complex processes at watershed scale remain a challenge and numerical studies are often needed for guidance of water resources management and decision making. This research integrates the knowledge bases developed during previous experimental and numerical investigations at a proposed waste disposal site at the Oak Ridge National Laboratory to study the concurrent effects of physical and chemical nonequilibrium. Comparison of numerical results with field data indicates that: (1) multiregion, preferential flow and solute transport exist under partially saturated condition and can be confirmed theoretically, and that (2) mass transfer between pore regions is an important process influencing contaminant movement in the subsurface. Simulations of watershed scale, multi species reactive solute transport suggest that dominance of geochemistry and hydrodynamics may occur simultaneously at different locales and influence the movement of one species relative to another. Execution times on the simulations of the reactive solute transport model also indicate that the model is ready to assist the selection of important parameters for site characterization.

Gwo, J.P.; Jardine, P.M.; D`Azevedo, E.F. [Oak Ridge National Lab., TN (United States); Wilson, G.V. [Desert Research Inst., Las Vegas, NV (United States). Water Resources Center

1997-12-01T23:59:59.000Z

3

Modeling of transport and reaction in an engineered barrier for radioactive waste confinement  

E-Print Network (OSTI)

Modeling of transport and reaction in an engineered barrier for radioactive waste confinement G bentonite; Radioactive waste; Modelling; KIRMAT code; Chemical transformations; Mass transport 0169;1. Introduction A particular radioactive waste disposal design proposes to store waste in deep geological layers

Montes-Hernandez, German

4

Transport Model Simulations of Projectile Fragmentation Reactions at 140 MeV/nucleon  

E-Print Network (OSTI)

The collisions in four different reaction systems using 40,48Ca and 58,64Ni isotope beams and a Be target have been simulated using the Heavy Ion Phase Space Exploration and the Antisymmetrized Molecular Dynamics models. The present study mainly focuses on the model predictions of excitation energy of the hot fragments and the cross sections of final fragments produced in these reactions. The calculated fragment cross sections are compared to the published projectile fragmentation cross sections measured with a mass separator. Experimental efficiency-correction assumptions and their effects in validation of event generator codes are discussed in the light of the reaction dynamics described by these two models. The effects of various factors influencing the calculated cross sections, such as the choice of the statistical decay code and its parameters have been explored. Present study suggests that the CPU requirements and the uncertainties of model parameters including the influence of sequential decay effects...

Mocko, M; Lacroix, D; Ono, A; Danielewicz, P; Lynch, W G; Charity, R J

2008-01-01T23:59:59.000Z

5

Coupling of kinetic Monte Carlo simulations of surface reactions to transport in a fluid for heterogeneous catalytic reactor modeling  

SciTech Connect

We have developed a method to couple kinetic Monte Carlo simulations of surface reactions at a molecular scale to transport equations at a macroscopic scale. This method is applicable to steady state reactors. We use a finite difference upwinding scheme and a gap-tooth scheme to efficiently use a limited amount of kinetic Monte Carlo simulations. In general the stochastic kinetic Monte Carlo results do not obey mass conservation so that unphysical accumulation of mass could occur in the reactor. We have developed a method to perform mass balance corrections that is based on a stoichiometry matrix and a least-squares problem that is reduced to a non-singular set of linear equations that is applicable to any surface catalyzed reaction. The implementation of these methods is validated by comparing numerical results of a reactor simulation with a unimolecular reaction to an analytical solution. Furthermore, the method is applied to two reaction mechanisms. The first is the ZGB model for CO oxidation in which inevitable poisoning of the catalyst limits the performance of the reactor. The second is a model for the oxidation of NO on a Pt(111) surface, which becomes active due to lateral interaction at high coverages of oxygen. This reaction model is based on ab initio density functional theory calculations from literature.

Schaefer, C.; Jansen, A. P. J. [Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

2013-02-07T23:59:59.000Z

6

Transport model simulations of projectile fragmentation reactions at 140 MeV/nucleon  

SciTech Connect

The collisions in four different reaction systems using {sup 40,48}Ca and {sup 58,64}Ni isotope beams and a Be target have been simulated using the heavy ion phase space exploration and the antisymmetrized molecular dynamics models. The present study mainly focuses on the model predictions for the excitation energies of the hot fragments and the cross sections of the final fragments produced in these reactions. The effects of various factors influencing the final fragment cross sections, such as the choice of the statistical decay code and its parameters, have been explored. The predicted fragment cross sections are compared to the projectile fragmentation cross sections measured with the A1900 mass separator. At E/A=140 MeV, reaction dynamics can significantly modify the detection efficiencies for the fragments and make them different from the efficiencies applied to the measured data reported in the previous work. The effects of efficiency corrections on the validation of event generator codes are discussed in the context of the two models.

Mocko, M. [Los Alamos National Laboratory, Post Office Box 1663, Los Alamos, New Mexico 87545 (United States); National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States); Tsang, M. B.; Danielewicz, P.; Lynch, W. G. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States); Lacroix, D. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States); Ganil, CEA, IN2P3-CNRS, Boite Postal 5027, F-14021 Caen Cedex (France); Ono, A. [Department of Physics, Tohoku University, Sendai 980-8578 (Japan); Charity, R. J. [Chemistry Department, Washington University, St. Louis, Missouri 63130 (United States)

2008-08-15T23:59:59.000Z

7

Transport Model Simulations of Projectile Fragmentation Reactions at 140 MeV/nucleon  

E-Print Network (OSTI)

The collisions in four different reaction systems using $^{40,48}$Ca and $^{58,64}$Ni isotope beams and a Be target have been simulated using the Heavy Ion Phase Space Exploration and the Antisymmetrized Molecular Dynamics models. The present study mainly focuses on the model predictions for the excitation energies of the hot fragments and the cross sections of the final fragments produced in these reactions. The effects of various factors influencing the final fragment cross sections, such as the choice of the statistical decay code and its parameters have been explored. The predicted fragment cross sections are compared to the projectile fragmentation cross sections measured with the A1900 mass separator. At $E/A=140$ MeV, reaction dynamics can significantly modify the detection efficiencies for the fragments and make them different from the efficiencies applied to the measured data reported in the previous work. The effects of efficiency corrections on the validation of event generator codes are discussed in the context of the two models.

M. Mocko; M. B. Tsang; D. Lacroix; A. Ono; P. Danielewicz; W. G. Lynch; R. J. Charity

2008-04-16T23:59:59.000Z

8

Integration of Nontraditional Isotopic Systems Into Reaction-Transport Models of EGS For Exploration, Evaluation of Water-Rock Interaction, and Impacts of Water Chemistry on Reservoir Sustainability  

Energy.gov (U.S. Department of Energy (DOE))

Integration of Nontraditional Isotopic Systems Into Reaction-Transport Models of EGS For Exploration, Evaluation of Water-Rock Interaction, and Impacts of Water Chemistry on Reservoir Sustainability presentation at the April 2013 peer review meeting held in Denver, Colorado.

9

Computational fluid dynamics model development on transport phenomena coupling with reactions in intermediate temperature solid oxide fuel cells  

Science Journals Connector (OSTI)

A 3D model is developed to describe an anode-supported planar solid oxide fuel cell (SOFC) by ANSYS/Fluent evaluating reactions including methane steam reforming (MSR)/water-gas shift (WGSR) reactions in thick anode layer and H2-O2/CO-O2 electrochemical reactions in anode active layer coupled with heat mass species momentum and ion/electron charges transport processes in SOFC. The predicted results indicate that electron/ion exchange appears in the very thin region in active layers (0.018?mm in anode and 0.01?mm in cathode) based on three phase boundary operating temperature and concentration of reactants (mainly H2). Active polarization happening in active layers dominates over concentration and ohmic losses. High gradient of current density exists near interface between electrode and solid conductor due to the block by gas channel. It is also found the reaction rates of MSR and WGSR along main flow direction and cell thickness direction decrease due to low concentration of fuel (CH4) caused by mass consumption. With increasing operating temperature from 978?K to 1088?K the current density and the reaction rate of MSR are increased by 10.8% and 5.4% respectively. While ion current density is 52.9% higher than in standard case and H2 is consumed by 5.1% more when ion conductivity is doubled. CO-O2 has been considered in charge transfer reaction in anode active layer and it is found that the current density and species distributions are not sensitive but WGSR reaction will be forced backwards to supply more CO for CO-O2 electrochemical reaction.

Chao Yang; Guogang Yang; Danting Yue; Jinliang Yuan; Bengt Sunden

2013-01-01T23:59:59.000Z

10

A coupled transport and solid mechanics formulation with improved reaction kinetics parameters for modeling oxidation and decomposition in a uranium hydride bed.  

SciTech Connect

Modeling of reacting flows in porous media has become particularly important with the increased interest in hydrogen solid-storage beds. An advanced type of storage bed has been proposed that utilizes oxidation of uranium hydride to heat and decompose the hydride, releasing the hydrogen. To reduce the cost and time required to develop these systems experimentally, a valid computational model is required that simulates the reaction of uranium hydride and oxygen gas in a hydrogen storage bed using multiphysics finite element modeling. This SAND report discusses the advancements made in FY12 (since our last SAND report SAND2011-6939) to the model developed as a part of an ASC-P&EM project to address the shortcomings of the previous model. The model considers chemical reactions, heat transport, and mass transport within a hydride bed. Previously, the time-varying permeability and porosity were considered uniform. This led to discrepancies between the simulated results and experimental measurements. In this work, the effects of non-uniform changes in permeability and porosity due to phase and thermal expansion are accounted for. These expansions result in mechanical stresses that lead to bed deformation. To describe this, a simplified solid mechanics model for the local variation of permeability and porosity as a function of the local bed deformation is developed. By using this solid mechanics model, the agreement between our reacting bed model and the experimental data is improved. Additionally, more accurate uranium hydride oxidation kinetics parameters are obtained by fitting the experimental results from a pure uranium hydride oxidation measurement to the ones obtained from the coupled transport-solid mechanics model. Finally, the coupled transport-solid mechanics model governing equations and boundary conditions are summarized and recommendations are made for further development of ARIA and other Sandia codes in order for them to sufficiently implement the model.

Salloum, Maher N.; Shugard, Andrew D.; Kanouff, Michael P.; Gharagozloo, Patricia E.

2013-03-01T23:59:59.000Z

11

UZ Colloid Transport Model  

SciTech Connect

The UZ Colloid Transport model development plan states that the objective of this Analysis/Model Report (AMR) is to document the development of a model for simulating unsaturated colloid transport. This objective includes the following: (1) use of a process level model to evaluate the potential mechanisms for colloid transport at Yucca Mountain; (2) Provide ranges of parameters for significant colloid transport processes to Performance Assessment (PA) for the unsaturated zone (UZ); (3) Provide a basis for development of an abstracted model for use in PA calculations.

M. McGraw

2000-04-13T23:59:59.000Z

12

Towards Quantum Transport for Nuclear Reactions  

E-Print Network (OSTI)

Nonequilibrium Green's functions represent a promising tool for describing central nuclear reactions. Even at the single-particle level, though, the Green's functions contain more information that computers may handle in the foreseeable future. In this study, we investigate whether all the information contained in the Green's functions is necessarily relevant when describing the time evolution of nuclear reactions. For this, we carry out mean-field calculations of slab collisions in one dimension.

Danielewicz, Pawel; Barker, Brent

2009-01-01T23:59:59.000Z

13

Towards Quantum Transport for Nuclear Reactions  

E-Print Network (OSTI)

Nonequilibrium Green's functions represent a promising tool for describing central nuclear reactions. Even at the single-particle level, though, the Green's functions contain more information that computers may handle in the foreseeable future. In this study, we investigate whether all the information contained in the Green's functions is necessarily relevant when describing the time evolution of nuclear reactions. For this, we carry out mean-field calculations of slab collisions in one dimension.

Pawel Danielewicz; Arnau Rios; Brent Barker

2009-06-26T23:59:59.000Z

14

Modelling transport fuel demand  

Science Journals Connector (OSTI)

Transport fuels account for an increasing share of oil ... interest to study the economics of the transport fuel market and thereby to evaluate the efficiency of the price mechanism as an instrument of policy in ...

Thomas Sterner; Carol A. Dahl

1992-01-01T23:59:59.000Z

15

Transportation Analysis, Modeling, and Simulation (TAMS) Application  

E-Print Network (OSTI)

Transportation Analysis, Modeling, and Simulation (TAMS) Application Center for Transportation Passenger Flows Supply Chain Efficiency Transportation: Energy Environment Safety Security Vehicle Technologies T he Center for Transportation Analysis (CTA) TAMS application is a web-based tool that supports

16

An integrated experimental and numerical study: Developing a reaction transport model that couples chemical reactions of mineral dissolution/precipitation with spatial and temporal flow variations in CO2/brine/rock systems  

Energy.gov (U.S. Department of Energy (DOE))

Project objectives: Generate and characterize mineral dissolution/precipitation reactions in supercritical CO2/brine/rock systems under pressure-temperature-chemistry conditions resembling CO2injection into EGS. Characterize three-dimensional spatial and temporal distributions of rock structures subject to mineral dissolution/precipitation processes by X-ray tomography, SEM imaging, and Microprobe analysis.

17

Model for the transport of airborne radioiodine  

SciTech Connect

Gaseous iodine deposits on surfaces exposed to the vapors. The industry has observed gaseous iodine transport behavior for years, and groups have proposed models describing the phenomena with limited success. The transport models attempt to describe the complicated chemical processes in terms of empirical rate constants. The current model, also empirical, treats deposition, conversion, and resuspension along a path of short segments where the assumption of instantaneous and homogeneous mixing is adequate, passing on the results as input to the next segment. The number of segments depends on line and flow parameters and can be as many as 100,000 for a long, large-diameter pipe with low flow. It includes a chemical bonding reaction rate to iodine deposited on the surface. The model has five compartments in each segment: concentrations of the three airborne iodine species, surface activity available for resuspension, and reacted surface iodine that is fixed on the surface. All iodine in the segment undergoes radioactive decay. The calculation divides the time period into small time division, typically 100, where the assumption of instantaneous equilibrium is applicable. The model initially developed by Science Applications International describes deposition, resuspension, and conversion of iodine in four differential equations that describe, respectively, airborne elemental, HOI and organic, and surface activities.

Cline, J.E.

1991-11-01T23:59:59.000Z

18

Solar Models and NACRE thermonuclear reaction rates  

E-Print Network (OSTI)

Using the most recent updated physics, calibrated solar models have been computed with the new thermonuclear reaction rates of NACRE, the recently available European compilation. Comparisons with models computed with the reaction rates of Caughlan & Fowler (\\cite{cf88}) and of Adelberger et al. (\\cite{a98}) are made for global structure, expected neutrinos fluxes, chemical composition and sound speed profiles, helioseismological properties of p-modes and g-modes.

P. Morel; B. Pichon; J. Provost; G. Berthomieu

1999-07-27T23:59:59.000Z

19

Controlling reactivity of nanoporous catalyst materials by tuning reaction product-pore interior interactions: Statistical mechanical modeling  

SciTech Connect

Statistical mechanical modeling is performed of a catalytic conversion reaction within a functionalized nanoporous material to assess the effect of varying the reaction product-pore interior interaction from attractive to repulsive. A strong enhancement in reactivity is observed not just due to the shift in reaction equilibrium towards completion but also due to enhanced transport within the pore resulting from reduced loading. The latter effect is strongest for highly restricted transport (single-file diffusion), and applies even for irreversible reactions. The analysis is performed utilizing a generalized hydrodynamic formulation of the reaction-diffusion equations which can reliably capture the complex interplay between reaction and restricted transport.

Wang, Jing [Ames Laboratory; Ackerman, David M. [Ames Laboratory; Lin, Victor S.-Y. [Ames Laboratory; Pruski, Marek [Ames Laboratory; Evans, James W. [Ames Laboratory

2013-04-02T23:59:59.000Z

20

Fluid flow and solute transport modeling with lattice Boltzmann models  

E-Print Network (OSTI)

Fluid flow and solute transport modeling with lattice Boltzmann models Ph.D. Proposal: Shadab Anwar with solute transport and fluid flow modeling in porous media using lattice Boltzmann model (LBM). LBM

Sukop, Mike

Note: This page contains sample records for the topic "reaction transport model" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Transportation Network Modeling in Passenger Transportation  

E-Print Network (OSTI)

- Modeled (infrastructure not taken into account) VDxxGasoline car Hybrid car GD M$/M gallon M gallon model of Passenger Network Model to emulate mode competition Infrastructure sharing by fleet 4. Data or induced ­ Arc (Routes) fixed · Infrastructure ­ Highway, railway, waterways, airports · Fleet ­ Trucks

Daniels, Thomas E.

22

NREL: Transportation Research - Data, Models, and Tools  

NLE Websites -- All DOE Office Websites (Extended Search)

fuel providers, and other transportation decision-makers reduce petroleum use. CoolSim HVAC Model Heating, ventilating, and air conditioning (HVAC) model that solves energy,...

23

Transport Modeling Working Group Meeting Reports  

Energy.gov (U.S. Department of Energy (DOE))

Reports from meetings of the Transport Modeling Working Group, which meets twice per year to exchange information, create synergies, share experimental and computational results, and collaboratively develop methodologies for and understanding of transport phenomena in polymer electrolyte fuel cell stacks.

24

SATURATED ZONE FLOW AND TRANSPORT MODEL ABSTRACTION  

SciTech Connect

The purpose of the saturated zone (SZ) flow and transport model abstraction task is to provide radionuclide-transport simulation results for use in the total system performance assessment (TSPA) for license application (LA) calculations. This task includes assessment of uncertainty in parameters that pertain to both groundwater flow and radionuclide transport in the models used for this purpose. This model report documents the following: (1) The SZ transport abstraction model, which consists of a set of radionuclide breakthrough curves at the accessible environment for use in the TSPA-LA simulations of radionuclide releases into the biosphere. These radionuclide breakthrough curves contain information on radionuclide-transport times through the SZ. (2) The SZ one-dimensional (I-D) transport model, which is incorporated in the TSPA-LA model to simulate the transport, decay, and ingrowth of radionuclide decay chains in the SZ. (3) The analysis of uncertainty in groundwater-flow and radionuclide-transport input parameters for the SZ transport abstraction model and the SZ 1-D transport model. (4) The analysis of the background concentration of alpha-emitting species in the groundwater of the SZ.

B.W. ARNOLD

2004-10-27T23:59:59.000Z

25

Photochemical and electron transport reactions of bacterial photosynthesis.  

Science Journals Connector (OSTI)

...secondary reaction. In experiments with R. rubrumn, it was found that the initial reaction was complete in less than 0.2 ,usec. Thus, in both bacteria, the oxidation of P890 is the primary event. In considering the compounds which might serve as the...

L P Vernon

1968-09-01T23:59:59.000Z

26

Modeling reaction time within a traffic simulation model  

E-Print Network (OSTI)

Human reaction time has a substantial effect on modeling of human behavior at a microscopic level. Drivers and pedestrian do not react to an event instantaneously; rather, they take time to perceive the event, process the ...

Basak, Kakali

27

5. Energy Production and Transport 5.1 Energy Release from Nuclear Reactions  

E-Print Network (OSTI)

5. Energy Production and Transport 5.1 Energy Release from Nuclear Reactions As mentioned when we looked at energy generation, it is now known that most of the energy radiated by stars must be released by nuclear reactions. In this section we will consider why it is that energy can be released by nuclear

Peletier, Reynier

28

Model Recovery Procedure for Response to a Radiological Transportation...  

Office of Environmental Management (EM)

Recovery Procedure for Response to a Radiological Transportation Incident Model Recovery Procedure for Response to a Radiological Transportation Incident This Transportation...

29

Fuel Cell Technologies Office: Transport Modeling Working Group  

NLE Websites -- All DOE Office Websites (Extended Search)

Transport Modeling Transport Modeling Working Group to someone by E-mail Share Fuel Cell Technologies Office: Transport Modeling Working Group on Facebook Tweet about Fuel Cell Technologies Office: Transport Modeling Working Group on Twitter Bookmark Fuel Cell Technologies Office: Transport Modeling Working Group on Google Bookmark Fuel Cell Technologies Office: Transport Modeling Working Group on Delicious Rank Fuel Cell Technologies Office: Transport Modeling Working Group on Digg Find More places to share Fuel Cell Technologies Office: Transport Modeling Working Group on AddThis.com... Key Activities Plans, Implementation, & Results Accomplishments Organization Chart & Contacts Quick Links Hydrogen Production Hydrogen Delivery Hydrogen Storage Fuel Cells Technology Validation

30

Two-dimensional model of a reaction-diffusion system as a typewriter  

Science Journals Connector (OSTI)

Pattern formation is a common phenomenon, which appears in biological systems, especially in cell differentiation processes. The proper level for understanding the creation of patterns seems to be a physicochemical description. The most fundamental models should be based on systems, in which only chemical reactions and diffusion transport occur (reaction-diffusion systems). In order to present a richness of patterns, we show here the asymptotic patterns in the form of capital letters obtained in two-dimensional reaction-diffusion systems with zero-flux boundary conditions. All capital letters are obtained in the same model, but initial conditions and sizes of the systems are different for each letter. The chemical model consists of elementary reactions and is realistic. It can be realized experimentally in continuous-flow unstirred reactor with an enzymatic reaction allosterically inhibited by an excess of its reactant and product.

Andrzej L. Kawczy?ski and Bart?omiej Legawiec

2001-10-09T23:59:59.000Z

31

Argonne's GREET Model - Driving Transportation Solutions  

NLE Websites -- All DOE Office Websites (Extended Search)

Driving Driving Transportation Solutions Model Argonne's GREET D r i v i n g Tr a n s p o r t a t i o n S o l u t i o n s ARGONNE'S GREET Argonne's GREET model is widely recognized as the "gold standard" for evaluating and comparing the energy and environmental impacts of transportation fuels and advanced vehicles. The Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) model is a one-of-a-kind analytical tool that simulates the energy use and emissions output of various vehicle and fuel combinations. Sponsored by the U.S. Department of Energy's (DOE) Office of Energy Efficiency and Renewable Energy, the free software program gives researchers the unique ability to analyze technologies over an entire life cycle - from well to wheels and from raw material mining to vehicle disposal.

32

Model Recovery Procedure for Response to a Radiological Transportation Incident  

Energy.gov (U.S. Department of Energy (DOE))

This Transportation Emergency Preparedness Program (TEPP) Model Recovery Procedure contains the recommended elements for developing and conducting recovery planning at transportation incident scene...

33

Block Preconditioning for a Coupled Model of Transport with Sorption in Porous Media  

E-Print Network (OSTI)

Block Preconditioning for a Coupled Model of Transport with Sorption in Porous Media List consider a simplified model with one species undergoing a sorption reaction, given by a known equilibrium and D is the diffusion­ dispersion tensor. The sorption isotherm in equation (1) will be taken

Boyer, Edmond

34

Abstracts of the symposium on unsaturated flow and transport modeling  

SciTech Connect

Abstract titles are: Recent developments in modeling variably saturated flow and transport; Unsaturated flow modeling as applied to field problems; Coupled heat and moisture transport in unsaturated soils; Influence of climatic parameters on movement of radionuclides in a multilayered saturated-unsaturated media; Modeling water and solute transport in soil containing roots; Simulation of consolidation in partially saturated soil materials; modeling of water and solute transport in unsaturated heterogeneous fields; Fluid dynamics and mass transfer in variably-saturated porous media; Solute transport through soils; One-dimensional analytical transport modeling; Convective transport of ideal tracers in unsaturated soils; Chemical transport in macropore-mesopore media under partially saturated conditions; Influence of the tension-saturated zone on contaminant migration in shallow water regimes; Influence of the spatial distribution of velocities in porous media on the form of solute transport; Stochastic vs deterministic models for solute movement in the field; and Stochastic analysis of flow and solute transport. (DMC)

Not Available

1982-03-01T23:59:59.000Z

35

Chemical Kinetic Modeling of Advanced Transportation Fuels  

SciTech Connect

Development of detailed chemical kinetic models for advanced petroleum-based and nonpetroleum based fuels is a difficult challenge because of the hundreds to thousands of different components in these fuels and because some of these fuels contain components that have not been considered in the past. It is important to develop detailed chemical kinetic models for these fuels since the models can be put into engine simulation codes used for optimizing engine design for maximum efficiency and minimal pollutant emissions. For example, these chemistry-enabled engine codes can be used to optimize combustion chamber shape and fuel injection timing. They also allow insight into how the composition of advanced petroleum-based and non-petroleum based fuels affect engine performance characteristics. Additionally, chemical kinetic models can be used separately to interpret important in-cylinder experimental data and gain insight into advanced engine combustion processes such as HCCI and lean burn engines. The objectives are: (1) Develop detailed chemical kinetic reaction models for components of advanced petroleum-based and non-petroleum based fuels. These fuels models include components from vegetable-oil-derived biodiesel, oil-sand derived fuel, alcohol fuels and other advanced bio-based and alternative fuels. (2) Develop detailed chemical kinetic reaction models for mixtures of non-petroleum and petroleum-based components to represent real fuels and lead to efficient reduced combustion models needed for engine modeling codes. (3) Characterize the role of fuel composition on efficiency and pollutant emissions from practical automotive engines.

PItz, W J; Westbrook, C K; Herbinet, O

2009-01-20T23:59:59.000Z

36

Model solutions of regularized relativistic transport equations  

Science Journals Connector (OSTI)

We present numerical solutions of recently proposed relativistic transport equations for fluctuating hadronic fields with simplified model Lagrangians containing a spin-1/2 nucleon and a light scalar or pseudoscalar meson. We introduce and implement a method for regularizing tadpoles and vector loops which is consistent with the previously proposed regularization of the scalar loops. The resulting solutions in vacuum are well behaved, exhibiting the expected differences between the scalar and pseudoscalar cases without apparent pathologies.

Joseph P. Milana and Philip J. Siemens

1991-05-01T23:59:59.000Z

37

Azimuthal Anisotropies as Stringent Test for Nuclear Transport Models  

E-Print Network (OSTI)

Azimuthal distributions of charged particles and intermediate mass fragments emitted in Au+Au collisions at 600AMeV have been measured using the FOPI facility at GSI-Darmstadt. Data show a strong increase of the in-plane azimuthal anisotropy ratio with the charge of the detected fragment. Intermediate mass fragments are found to exhibit a strong momentum-space alignment with respect of the reaction plane. The experimental results are presented as a function of the polar center-of-mass angle and over a broad range of impact parameters. They are compared to the predictions of the Isospin Quantum Molecular Dynamics model using three different parametrisations of the equation of state. We show that such highly accurate data provide stringent test for microscopic transport models and can potentially constrain separately the stiffness of the nuclear equation of state and the momentum dependence of the nuclear interaction.

P. Crochet; F. Rami; R. Dona; the FOPI Collaboration

1997-09-15T23:59:59.000Z

38

Investigation of Multiscale and Multiphase Flow, Transport and Reaction in Heavy Oil Recovery Processes  

SciTech Connect

This project is an investigation of various multi-phase and multiscale transport and reaction processes associated with heavy oil recovery. The thrust areas of the project include the following: Internal drives, vapor-liquid flows, combustion and reaction processes, fluid displacements and the effect of instabilities and heterogeneities and the flow of fluids with yield stress. These find respective applications in foamy oils, the evolution of dissolved gas, internal steam drives, the mechanics of concurrent and countercurrent vapor-liquid flows, associated with thermal methods and steam injection, such as SAGD, the in-situ combustion, the upscaling of displacements in heterogeneous media and the flow of foams, Bingham plastics and heavy oils in porous media and the development of wormholes during cold production.

Yortsos, Yanis C.

2001-08-07T23:59:59.000Z

39

Investigation of Multiscale and Multiphase Flow, Transport and Reaction in Heavy Oil Recovery Processes  

SciTech Connect

This report is an investigation of various multi-phase and multiscale transport and reaction processes associated with heavy oil recovery. The thrust areas of the project include the following: Internal drives, vapor-liquid flows, combustion and reaction processes, fluid displacements and the effect of instabilities and heterogeneities and the flow of fluids with yield stress. These find respective applications in foamy oils, the evolution of dissolved gas, internal steam drives, the mechanics of concurrent and countercurrent vapor-liquid flows, associated with thermal methods and steam injection, such as SAGD, the in-situ combustion, the upscaling of displacements in heterogeneous media and the flow of foams, Bingham plastics and heavy oils in porous media and the development of wormholes during cold production.

Yortsos, Y.C.

2001-05-29T23:59:59.000Z

40

Experimental and numerical modeling of convective proppant transport  

SciTech Connect

Slurry-transport and -settling experiments were conducted to improve current descriptions of proppant transport, and the results were used to formulate a new slurry-transport model incorporated into a fully 3D fracture simulator. The model was tested and verified vs. experimental observations of slurry transport in a 4 x 16-ft slot model. Results of the study indicate that proppant-slurry transport can be modeled accurately by accounting for the effects of single-particle settling, density-driven flow, particle-velocity profiles, and slurry rheology.

Barree, R.D. [Marathon Oil Co., Littleton, CO (United States); Conway, M.W. [Stim-Lab Inc., Duncan, OK (United States)

1995-03-01T23:59:59.000Z

Note: This page contains sample records for the topic "reaction transport model" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Strong plasma screening in thermonuclear reactions: Electron drop model  

Science Journals Connector (OSTI)

We analyze enhancement of thermonuclear fusion reactions due to strong plasma screening in dense matter using a simple electron drop model. In the model we assume fusion in a potential that is screened by an effective electron cloud around colliding nuclei (extended Salpeter ion-sphere model). We calculate the mean-field screened Coulomb potentials for atomic nuclei with equal and nonequal charges, appropriate astrophysical S factors, and enhancement factors of reaction rates. As a byproduct, we study the analytic behavior of the screening potential at small separations between the reactants. In this model, astrophysical S factors depend not only on nuclear physics but on plasma screening as well. The enhancement factors are in good agreement with calculations by other methods. This allows us to formulate a combined, pure analytic model of strong plasma screening in thermonuclear reactions. The results can be useful for simulating nuclear burning in white dwarfs and neutron stars.

P. A. Kravchuk and D. G. Yakovlev

2014-01-09T23:59:59.000Z

42

Strong plasma screening in thermonuclear reactions: Electron drop model  

E-Print Network (OSTI)

We analyze enhancement of thermonuclear fusion reactions due to strong plasma screening in dense matter using a simple electron drop model. The model assumes fusion in a potential that is screened by an effective electron cloud around colliding nuclei (extended Salpeter ion-sphere model). We calculate the mean field screened Coulomb potentials for atomic nuclei with equal and nonequal charges, appropriate astrophysical S factors, and enhancement factors of reaction rates. As a byproduct, we study analytic behavior of the screening potential at small separations between the reactants. In this model, astrophysical S factors depend not only on nuclear physics but on plasma screening as well. The enhancement factors are in good agreement with calculations by other methods. This allows us to formulate the combined, pure analytic model of strong plasma screening in thermonuclear reactions. The results can be useful for simulating nuclear burning in white dwarfs and neutron stars.

Kravchuk, P A

2014-01-01T23:59:59.000Z

43

Strong plasma screening in thermonuclear reactions: Electron drop model  

E-Print Network (OSTI)

We analyze enhancement of thermonuclear fusion reactions due to strong plasma screening in dense matter using a simple electron drop model. The model assumes fusion in a potential that is screened by an effective electron cloud around colliding nuclei (extended Salpeter ion-sphere model). We calculate the mean field screened Coulomb potentials for atomic nuclei with equal and nonequal charges, appropriate astrophysical S factors, and enhancement factors of reaction rates. As a byproduct, we study analytic behavior of the screening potential at small separations between the reactants. In this model, astrophysical S factors depend not only on nuclear physics but on plasma screening as well. The enhancement factors are in good agreement with calculations by other methods. This allows us to formulate the combined, pure analytic model of strong plasma screening in thermonuclear reactions. The results can be useful for simulating nuclear burning in white dwarfs and neutron stars.

P. A. Kravchuk; D. G. Yakovlev

2014-01-11T23:59:59.000Z

44

Light radioactive nuclei capture reactions with phenomenological potential models  

E-Print Network (OSTI)

Light radioactive nuclei play an important role in many astrophysical environments. Due to very low cross sections of some neutron and proton capture reactions by these radioactive nuclei at energies of astrophysical interest, direct laboratory measurements are very difficult. For radioactive nuclei such as 8Li and 8B, the direct measurement of neutron capture reactions is impossible. Indirect methods have been applied to overcome these difficulties. In this work we will report on the results and discussion of phenomenological potential models used to determine some proton and neutron capture reactions. As a test we show the results for the 16O(p,g)17F_gs(5/2+) and 16O(p,g)17F_ex(1/2+) capture reactions.We also computed the nucleosynthesis cross sections for the 7Li(n,g)8Li, 8Li(n,g)9Li and 8B(p,g)9C capture reactions.

V. Guimaraes; C. A. Bertulani

2009-12-01T23:59:59.000Z

45

Documentation of TRU biological transport model (BIOTRAN)  

SciTech Connect

Inclusive of Appendices, this document describes the purpose, rationale, construction, and operation of a biological transport model (BIOTRAN). This model is used to predict the flow of transuranic elements (TRU) through specified plant and animal environments using biomass as a vector. The appendices are: (A) Flows of moisture, biomass, and TRU; (B) Intermediate variables affecting flows; (C) Mnemonic equivalents (code) for variables; (D) Variable library (code); (E) BIOTRAN code (Fortran); (F) Plants simulated; (G) BIOTRAN code documentation; (H) Operating instructions for BIOTRAN code. The main text is presented with a specific format which uses a minimum of space, yet is adequate for tracking most relationships from their first appearance to their formulation in the code. Because relationships are treated individually in this manner, and rely heavily on Appendix material for understanding, it is advised that the reader familiarize himself with these materials before proceeding with the main text.

Gallegos, A.F.; Garcia, B.J.; Sutton, C.M.

1980-01-01T23:59:59.000Z

46

Mesoscopic modeling of liquid water transport in polymer electrolyte fuel cells  

SciTech Connect

A key performance limitation in polymer electrolyte fuel cells (PEFC), manifested in terms of mass transport loss, originates from liquid water transport and resulting flooding phenomena in the constituent components. Liquid water leads to the coverage of the electrochemically active sites in the catalyst layer (CL) rendering reduced catalytic activity and blockage of the available pore space in the porous CL and fibrous gas diffusion layer (GDL) resulting in hindered oxygen transport to the active reaction sites. The cathode CL and the GDL therefore playa major role in the mass transport loss and hence in the water management of a PEFC. In this article, we present the development of a mesoscopic modeling formalism coupled with realistic microstructural delineation to study the profound influence of the pore structure and surface wettability on liquid water transport and interfacial dynamics in the PEFC catalyst layer and gas diffusion layer.

Mukherjee, Partha P [Los Alamos National Laboratory; Wang, Chao Yang [PENNSTATE UNIV.

2008-01-01T23:59:59.000Z

47

Causal simulation models for facing third millennium air transport sustainability  

Science Journals Connector (OSTI)

Aeronautics and air transport is a vital sector of our society and economy. Air transport logistics is one of the key players to support efficient globalization; however, sustainable mobility is at stake, due to facts such as the interdependencies with ... Keywords: air transport logistics, causal models, emergent dynamics, mitigation mechanisms, perturbations

Miquel A Piera; Juan Jos Ramos; Romualdo Moreno; Mercedes Narciso

2014-02-01T23:59:59.000Z

48

Device Scale Model Development for Transport Reactor  

NLE Websites -- All DOE Office Websites (Extended Search)

Gary J. stiegel Gary J. stiegel Gasification Technology Manager National Energy Technology Laboratory 626 Cochrans Mill Road P.O. Box 10940 Pittsburgh, PA 15236 412-386-4499 gary.stiegel@netl.doe.gov Chris Guenther Computational Science Division National Energy Technology Laboratory 3610 Collins Ferry Road P. O. Box 880 Morgantown, WV 26507 304-285-4483 chris.guenther@netl.doe.gov 8/2006 Gasification Technologies Device Scale MoDel DevelopMent for tranSport reactor Background Coal gasification is an efficient and environmentally acceptable technology that can utilize the vast coal reserves in the United States to produce clean affordable power and reduce dependence on foreign oil. Coal and other carbon containing materials can be gasified to produce a synthesis gas. This syngas can be fed to a

49

Comb models for transport along spiny dendrites  

E-Print Network (OSTI)

This chapter is a contribution in the "Handbook of Applications of Chaos Theory" ed. by Prof. Christos H Skiadas. The chapter is organized as follows. First we study the statistical properties of combs and explain how to reduce the effect of teeth on the movement along the backbone as a waiting time distribution between consecutive jumps. Second, we justify an employment of a comb-like structure as a paradigm for further exploration of a spiny dendrite. In particular, we show how a comb-like structure can sustain the phenomenon of the anomalous diffusion, reaction-diffusion and L\\'evy walks. Finally, we illustrate how the same models can be also useful to deal with the mechanism of ta translocation wave / translocation waves of CaMKII and its propagation failure. We also present a brief introduction to the fractional integro-differentiation in appendix at the end of the chapter.

Mndez, V

2015-01-01T23:59:59.000Z

50

Singular Vector Analysis for Atmospheric Chemical Transport Models  

E-Print Network (OSTI)

are presented for a simulation of atmospheric pollution in East Asia in March 2001. The singular valuesSingular Vector Analysis for Atmospheric Chemical Transport Models Wenyuan Liao and Adrian Sandu for atmospheric chemical transport models. The distinguishing feature of these models is the presence of stiff

Sandu, Adrian

51

On EOQ Cost Models with Arbitrary Purchase and Transportation ...  

E-Print Network (OSTI)

cost functions for which this model is easy to solve and related to solving a ... For the remaining purchase-transportation cost functions, when this problem...

Birbil

2014-03-02T23:59:59.000Z

52

Modeling Oxygen Transport in Three-Dimensional Capillary Networks.  

E-Print Network (OSTI)

??The purpose of this thesis was to examine how the use of real 3-dimensional (3D) capillary network geometries affect models of oxygen transport to tissue. (more)

Fraser, Graham M

2012-01-01T23:59:59.000Z

53

Investigation of Multiscale and Multiphase Flow, Transport and Reaction in Heavy Oil Recovery Processes  

SciTech Connect

The emphasis of this work was on investigating the mechanisms and factors that control the recovery of heavy oil with the objective to improve recovery efficiencies. For this purpose the interaction of flow transport and reaction at various scales from the pore network to the field scales were studied. Particular mechanisms to be investigated included the onset of gas flow in foamy oil production and in in-situ steam drive, gravity drainage in steam processes, the development of sustained combustion fronts and the propagation of foams in porous media. Analytical, computational and experimental methods were utilized to advance the state of the art in heavy oil recovery. Successful completion of this research was expected to lead to improvements in the Recovery efficiency of various heavy oil processes.

Yorstos, Yanis C.

2002-03-11T23:59:59.000Z

54

Investigation of Multiscale and Multiphase Flow, Transport and Reaction in Heavy Oil Recovery Process  

SciTech Connect

The emphasis of this work was on investigating the mechanisms and factors that control the recovery of heavy oil, with the objective to improve recovery efficiencies. For this purpose, the interaction of flow, transport and reaction at various scales (from the pore-network to the field scales) were studied. Particular mechanisms investigated included the onset of gas flow in foamy oil production and in in-situ steam drive, gravity drainage in steam process, the development of sustained combustion fronts and the propagation of foams in porous media. Analytical, computational and experimental methods were utilized to advance the state of the art in heavy oil recovery. Successful completion of this research was expected to lead to improvements in the recovery efficiency of various heavy oil processes.

Yortsos, Yanis C.; Akkutlu, Yucel; Amilik, Pouya; Kechagia, Persefoni; Lu, Chuan; Shariati, Maryam; Tsimpanogiannis, Ioannis; Zhan, Lang

2000-01-19T23:59:59.000Z

55

Advanced modeling of reaction cross sections for light nuclei  

SciTech Connect

The shell model/R-matrix technique of calculating nuclear reaction cross sections for light projectiles incident on light nuclei is discussed, particularly in the application of the technique to thermonuclear reactions. Details are presented on the computational methods for the shell model which display how easily the calculations can be performed. Results of the shell model/R-matrix technique are discussed as are some of the problems encountered in picking an appropriate nucleon-nucleon interaction for the large model spaces which must be used for current problems. The status of our work on developing an effective nucleon-nucleon interaction for use in large-basis shell model calculations is presented. This new interaction is based on a combination of global constraints and microscopic nuclear data. 23 refs., 6 figs., 2 tabs.

Resler, D.A.

1991-01-01T23:59:59.000Z

56

Model calculations of the hydrogen/deuterium kinetic isotope effect in the atomic hydrogen + disilane reaction  

Science Journals Connector (OSTI)

Model calculations of the hydrogen/deuterium kinetic isotope effect in the atomic hydrogen + disilane reaction ...

I. Safarik; T. L. Pollock; O. P. Strausz

1974-01-01T23:59:59.000Z

57

HYDROGEOCHEM: A coupled model of HYDROlogic transport and GEOCHEMical equilibria in reactive multicomponent systems  

SciTech Connect

This report presents the development of a hydrogeochemical transport model for multicomponent systems. The model is designed for applications to proper hydrological setting, accommodation of complete suite of geochemical equilibrium processes, easy extension to deal with chemical kinetics, and least constraints of computer resources. The hydrological environment to which the model can be applied is the heterogeneous, anisotropic, saturated-unsaturated subsurface media under either transient or steady state flow conditions. The geochemical equilibrium processes included in the model are aqueous complexation, adsorption-desorption, ion exchange, precipitation-dissolution, redox, and acid-base reactions. To achieve the inclusion of the full complement of these geochemical processes, total analytical concentrations of all chemical components are chosen as the primary dependent variables in the hydrological transport equations. Attendant benefits of this choice are to make the extension of the model to deal with kinetics of adsorption-desorption, ion exchange, precipitation-dissolution, and redox relatively easy. To make the negative concentrations during the iteration between the hydrological transport and geochemical equilibrium least likely, an implicit form of transport equations are proposed. To alleviate severe constraints of computer resources in terms of central processing unit (CPU) time and CPU memory, various optional numerical schemes are incorporated in the model. The model consists of a hydrological transport module and geochemical equilibrium module. Both modules were thoroughly tested in code consistency and were found to yield plausible results. The model is verified with ten examples. 79 refs., 21 figs., 17 tabs.

Yeh, G.T.; Tripathi, V.S.

1990-11-01T23:59:59.000Z

58

Reaction mechanisms in transport theories: a test of the nuclear effective interaction  

E-Print Network (OSTI)

We review recent results concerning collective excitations in neutron-rich systems and reactions between charge asymmetric systems at Fermi energies. Solving numerically self-consistent transport equations for neutrons and protons with specific initial conditions, we explore the structure of the different dipole vibrations in the $^{132}Sn$ system and investigate their dependence on the symmetry energy. We evidence the existence of a distinctive collective mode, that can be associated with the Pygmy Dipole Resonance, with an energy well below the standard Giant Dipole Resonance and isoscalar-like character, i.e. very weakly dependent on the isovector part of the nuclear effective interaction. At variance, the corresponding strength is rather sensitive to the behavior of the symmetry energy below saturation, which rules the number of excess neutrons in the nuclear surface. In reactions between charge asymmetric systems at Fermi energies, we investigate the interplay between dissipation mechanisms and isospin effects. Observables sensitive to the isospin dependent part of nuclear interaction are discussed, providing information on the symmetry energy density dependence below saturation.

M. Colonna; V. Baran; M. Di Toro; B. Frecus; Y. X. Zhang

2012-09-07T23:59:59.000Z

59

Global Thermodynamic Atmospheric Modeling: Search for NewHeterogeneous Reactions  

SciTech Connect

This article demonstrates quantitatively how far reactions are from chemical equilibrium over the full space of a two-dimensional atmospheric model. This method could be used with data where an instrument-equipped aircraft measures numerous species simultaneously, An atmospheric reaction is displaced from equilibrium by solar radiation and relocation of species by atmospheric motions. One purpose of this study is to seek additional stratospheric or tropospheric gas-phase chemical reactions that might undergo heterogeneous catalysis. Hypothetical cases can be rapidly screened in terms of their thermodynamic potential to react under measured or modeled atmospheric conditions of temperature and local species concentrations. If a reaction is interesting, is slow in the gas phase, and has a high thermodynamic tendency to react, it is a good candidate for a laboratory study to seek a heterogeneous catalyst, if the reaction is thermodynamically unfavorable, there is no catalyst that can cause the reaction to occur. If a reaction is thermodynamically favored to occur but also endothermic, it will tend to be slow at stratospheric temperatures. We find, as expected, that four heterogeneous reactions important in causing the Antarctic ''ozone hole'' have high thermodynamic tendencies to occur under atmospheric conditions, but one of these is only weakly thermodynamically allowed in some regions of the atmosphere. The reaction of SO2 and HNO3 to form HONO has a high thermodynamic potential to occur, is a well-known laboratory reaction at ice temperature, and may occur in nitric acid-rich sulfate aerosols. Throughout the troposphere and stratosphere, we find that formaldehyde has an extremely high thermodynamic potential to reduce nitric acid. Formaldehyde is known to stick to and remain in sulfuric acid solution, where it adds water to form H2C(OH)(2). Near room-temperature H2C(OH)(2) reacts with nitric acid in a two-step mechanism to form two molecules of HONO, but the rate of this process under conditions of stratospheric sulfuric acid aerosols is unknown.

Fairbrother, D.H.; Sullivan, D.S.D.; Johnston, H.S.

1997-07-03T23:59:59.000Z

60

Weakly screened thermonuclear reactions in astrophysical plasmas: Improving Salpeter's model  

E-Print Network (OSTI)

This paper presents a detailed study of the electron degeneracy and nonlinear screening effects which play a crucial role in the validity of Salpeter's weak-screening model. The limitations of that model are investigated and an improved one is proposed which can take into account nonlinear screening effects. Its application to the solar pp reaction derives an accurate screening enhancement factor and provides a very reliable estimation of the associated neutrino flux uncertanties.

Theodore E. Liolios

2003-06-23T23:59:59.000Z

Note: This page contains sample records for the topic "reaction transport model" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

Particle Tracking Model and Abstraction of Transport Processes  

SciTech Connect

The purpose of this report is to document the abstraction model being used in total system performance assessment (TSPA) model calculations for radionuclide transport in the unsaturated zone (UZ). The UZ transport abstraction model uses the particle-tracking method that is incorporated into the finite element heat and mass model (FEHM) computer code (Zyvoloski et al. 1997 [DIRS 100615]) to simulate radionuclide transport in the UZ. This report outlines the assumptions, design, and testing of a model for calculating radionuclide transport in the UZ at Yucca Mountain. In addition, methods for determining and inputting transport parameters are outlined for use in the TSPA for license application (LA) analyses. Process-level transport model calculations are documented in another report for the UZ (BSC 2004 [DIRS 164500]). Three-dimensional, dual-permeability flow fields generated to characterize UZ flow (documented by BSC 2004 [DIRS 169861]; DTN: LB03023DSSCP9I.001 [DIRS 163044]) are converted to make them compatible with the FEHM code for use in this abstraction model. This report establishes the numerical method and demonstrates the use of the model that is intended to represent UZ transport in the TSPA-LA. Capability of the UZ barrier for retarding the transport is demonstrated in this report, and by the underlying process model (BSC 2004 [DIRS 164500]). The technical scope, content, and management of this report are described in the planning document ''Technical Work Plan for: Unsaturated Zone Transport Model Report Integration'' (BSC 2004 [DIRS 171282]). Deviations from the technical work plan (TWP) are noted within the text of this report, as appropriate. The latest version of this document is being prepared principally to correct parameter values found to be in error due to transcription errors, changes in source data that were not captured in the report, calculation errors, and errors in interpretation of source data.

B. Robinson

2004-10-21T23:59:59.000Z

62

Reduced Fast Ion Transport Model For The Tokamak Transport Code TRANSP  

SciTech Connect

Fast ion transport models presently implemented in the tokamak transport code TRANSP [R. J. Hawryluk, in Physics of Plasmas Close to Thermonuclear Conditions, CEC Brussels, 1 , 19 (1980)] are not capturing important aspects of the physics associated with resonant transport caused by instabilities such as Toroidal Alfv#19;en Eigenmodes (TAEs). This work describes the implementation of a fast ion transport model consistent with the basic mechanisms of resonant mode-particle interaction. The model is formulated in terms of a probability distribution function for the particle's steps in phase space, which is consistent with the MonteCarlo approach used in TRANSP. The proposed model is based on the analysis of fast ion response to TAE modes through the ORBIT code [R. B. White et al., Phys. Fluids 27 , 2455 (1984)], but it can be generalized to higher frequency modes (e.g. Compressional and Global Alfv#19;en Eigenmodes) and to other numerical codes or theories.

Podesta,, Mario; Gorelenkova, Marina; White, Roscoe

2014-02-28T23:59:59.000Z

63

ab initio Electronic Transport Model with Explicit Solution to the Linearized Boltzmann Transport Equation  

E-Print Network (OSTI)

Accurate models of carrier transport are essential for describing the electronic properties of semiconductor materials. To the best of our knowledge, the current models following the framework of the Boltzmann transport equation (BTE) either rely heavily on experimental data (i.e., semi-empirical), or utilize simplifying assumptions, such as the constant relaxation time approximation (BTE-cRTA). While these models offer valuable physical insights and accurate calculations of transport properties in some cases, they often lack sufficient accuracy -- particularly in capturing the correct trends with temperature and carrier concentration. We present here a general transport model for calculating low-field electrical drift mobility and Seebeck coefficient of n-type semiconductors, by explicitly considering all relevant physical phenomena (i.e. elastic and inelastic scattering mechanisms). We first rewrite expressions for the rates of elastic scattering mechanisms, in terms of ab initio properties, such as the ban...

Faghaninia, Alireza; Lo, Cynthia S

2015-01-01T23:59:59.000Z

64

Transportation energy demand: Model development and use  

Science Journals Connector (OSTI)

This paper describes work undertaken and sponsored by the Energy Commission to improve transportation energy demand forecasting and policy analysis for California. Two ... , the paper discusses some of the import...

Chris Kavalec

1998-06-01T23:59:59.000Z

65

Fuel Cell Technologies Office: Transport Modeling Working Group  

NLE Websites -- All DOE Office Websites (Extended Search)

Transport Modeling Working Group Transport Modeling Working Group The Transport Modeling Working Group meets twice per year to exchange information, create synergies, share experimental and computational results, and collaboratively develop methodologies for and understanding of transport phenomena in polymer electrolyte fuel cell stacks. Its members include principle investigators and supporting personnel from transport-related projects funded by the U.S. Department of Energy (DOE). Learn more about DOE research activities can be found in the Multi-Year Research, Development, and Demonstration Plan. Description Technical Targets Meetings Contacts Description Fuel cell operation relies on effective mass transport of species through individual components and across the interfaces between components. Among these species are hydrogen, oxygen, water, protons, and electrons. Transport behavior is a function of operating conditions and component properties such as microstructure and surface properties. Understanding and optimizing the controlling transport phenomena are critical to the efficient and cost-effective operation of polymer electrolyte fuel cells. A better understanding of mass transport in the fuel cell, especially of water, has the potential to lead to improved designs and more efficient systems.

66

Modeling atmospheric deposition using a stochastic transport model  

SciTech Connect

An advanced stochastic transport model has been modified to include the removal mechanisms of dry and wet deposition. Time-dependent wind and turbulence fields are generated with a prognostic mesoscale numerical model and are used to advect and disperse individually released particles that are each assigned a mass. These particles are subjected to mass reduction in two ways depending on their physical location. Particles near the surface experience a decrease in mass using the concept of a dry deposition velocity, while the mass of particles located within areas of precipitation are depleted using a scavenging coefficient. Two levels of complexity are incorporated into the particle model. The simple case assumes constant values of dry deposition velocity and scavenging coefficient, while the more complex case varies the values according to meteorology, surface conditions, release material, and precipitation intensity. Instantaneous and cumulative dry and wet deposition are determined from the mass loss due to these physical mechanisms. A useful means of validating the model results is with data available from a recent accidental release of Cesium-137 from a steel-processing furnace in Algeciras, Spain in May, 1998. This paper describes the deposition modeling technique, as well as a comparison of simulated concentration and deposition with measurements taken for the Algeciras release.

Buckley, R.L.

1999-12-17T23:59:59.000Z

67

Deep sub-threshold $?$ and $?$ production in nuclear collisions with the UrQMD transport model  

E-Print Network (OSTI)

We present results on deep sub threshold hyperon production in nuclear collisions, with the UrQMD transport model. Introducing anti-kaon+baryon and hyperon+hyperon strangeness exchange reactions we obtain a good description of experimental data on single strange hadron production in Ar+KCl reactions at $E_{lab}=1.76$ A GeV. We find that the hyperon strangeness exchange is the dominant process contributing to the $\\Xi^-$ yield, however remains short of explaining the $\\Xi^-/\\Lambda$ ratio measured with the HADES experiment. We also discuss possible reasons for the discrepancy with previous studies and the experimental results, finding that many details of the transport simulation may have significant effects on the final $\\Xi^-$ yield.

G. Graef; J. Steinheimer; Feng Li; Marcus Bleicher

2014-09-28T23:59:59.000Z

68

Reactions of Lignin Model Compounds in Ionic Liquids  

SciTech Connect

Lignin, a readily available form of biomass, awaits novel chemistry for converting it to valuable aromatic chemicals. Recent work has demonstrated that ionic liquids are excellent solvents for processing woody biomass and lignin. Seeking to exploit ionic liquids as media for depolymerization of lignin, we investigated reactions of lignin model compounds in these solvents. Using Brnsted acid catalysts in 1-ethyl-3-methylimidazolium triflate at moderate temperatures, we obtained up to 11.6% yield of the dealkylation product guaiacol from the model compound eugenol and cleaved phenethyl phenyl ether, a model for lignin ethers. Despite these successes, acid catalysis failed in dealkylation of the unsaturated model compound 4-ethylguaiacol and did not produce monomeric products from organosolv lignin, demonstrating that further work is required to understand the complex chemistry of lignin depolymerization.

Holladay, John E.; Binder, Joseph B.; Gray, Michel J.; White, James F.; Zhang, Z. Conrad

2009-09-15T23:59:59.000Z

69

Two modelling approaches using spreadsheets for the transportation assignment problem  

Science Journals Connector (OSTI)

This paper presents two modelling approaches for teaching the transportation assignment problem that have been very successful in teaching and learning. We have illustrated it using a numerical example and formulated two spreadsheets models using the popular spreadsheet package Microsoft Excel. In the first approach, we formulated an algebraic model, then transfered it to a spreadsheet. In the second approach, we formulated a spreadsheet model directly by using spreadsheet modelling techniques. We have demonstrated that students can understand and solve the transportation assignment problem more easily using these two approaches.

Xiang Ye; Xiao Zong

2006-01-01T23:59:59.000Z

70

Effective Transport Properties Accounting for Electrochemical Reactions of Proton-Exchange Membrane Fuel Cell Catalyst Layers  

SciTech Connect

There has been a rapidly growing interest in three-dimensional micro-structural reconstruction of fuel cell electrodes so as to derive more accurate descriptors of the pertinent geometric and effective transport properties. Due to the limited accessibility of experiments based reconstruction techniques, such as dual-beam focused ion beam-scanning electro microscopy or micro X-Ray computed tomography, within sample micro-structures of the catalyst layers in polymer electrolyte membrane fuel cells (PEMFCs), a particle based numerical model is used in this study to reconstruct sample microstructure of the catalyst layers in PEMFCs. Then the reconstructed sample structure is converted into the computational grid using body-fitted/cut-cell based unstructured meshing technique. Finally, finite volume methods (FVM) are applied to calculate effective properties on computational sample domains.

Pharoah, Jon; Choi, Hae-Won; Chueh, Chih-Che; Harvey, David

2011-07-01T23:59:59.000Z

71

Fokker-Planck/Transport model for neutral beam driven tokamaks  

SciTech Connect

The application of nonlinear Fokker-Planck models to the study of beam-driven plasmas is briefly reviewed. This evolution of models has led to a Fokker-Planck/Transport (FPT) model for neutral-beam-driven Tokamaks, which is described in detail. The FPT code has been applied to the PLT, PDX, and TFTR Tokamaks, and some representative results are presented.

Killeen, J.; Mirin, A.A.; McCoy, M.G.

1980-01-01T23:59:59.000Z

72

Boltzmann-Langevin transport model for heavy-ion collisions  

SciTech Connect

Heavy-ion collisions at intermediate energies exhibit catastrophic phenomena which requires descriptions based on stochastic transport models. First, the Boltzmann-Langevin model, which provides an example of such stochastic approaches, is briefly described. Then, a projection method for obtaining numerical solutions of the Boltzmann-Langevin equation is discussed. Finally, some applications of the model to heavy-ion collisions are presented.

Ayik, S. [Tennessee Technological Univ., Cookeville, TN (United States)]|[Joint Institute for Heavy-Ion Research, Oak Ridge, TN (United States)

1994-06-01T23:59:59.000Z

73

Modeling of Syngas Reactions and Hydrogen Generation Over Sulfides  

SciTech Connect

The objective of the research is to analyze pathways of reactions of hydrogen with oxides of carbon over sulfides, and to predict which characteristics of the sulfide catalyst (nature of metal, defect structure) give rise to the lowest barriers toward oxygenated hydrocarbon product. Reversal of these pathways entails the generation of hydrogen, which is also proposed for study. In this first year of study, adsorption reactions of H atoms and H{sub 2} molecules with MoS{sub 2}, both in molecular and solid form, have been modeled using high-level density functional theory. The geometries and strengths of the adsorption sites are described and the methods used in the study are described. An exposed MO{sup IV} species modeled as a bent MoS{sub 2} molecule is capable of homopolar dissociative chemisorption of H{sub 2} into a dihydride S{sub 2}MoH{sub 2}. Among the periodic edge structures of hexagonal MoS{sub 2}, the (1{bar 2}11) edge is most stable but still capable of dissociating H{sub 2}, while the basal plane (0001) is not. A challenging task of theoretically accounting for weak bonding of MoS{sub 2} sheets across the Van der Waals gap has been addressed, resulting in a weak attraction of 0.028 eV/MoS{sub 2} unit, compared to the experimental value of 0.013 eV/MoS{sub 2} unit.

Kamil Klier; Jeffery A. Spirko; Michael L. Neiman

2002-09-17T23:59:59.000Z

74

Mass transfer model for two-layer TBP oxidation reactions  

SciTech Connect

To prove that two-layer, TBP-nitric acid mixtures can be safely stored in the canyon evaporators, it must be demonstrated that a runaway reaction between TBP and nitric acid will not occur. Previous bench-scale experiments showed that, at typical evaporator temperatures, this reaction is endothermic and therefore cannot run away, due to the loss of heat from evaporation of water in the organic layer. However, the reaction would be exothermic and could run away if the small amount of water in the organic layer evaporates before the nitric acid in this layer is consumed by the reaction. Provided that there is enough water in the aqueous layer, this would occur if the organic layer is sufficiently thick so that the rate of loss of water by evaporation exceeds the rate of replenishment due to mixing with the aqueous layer. This report presents measurements of mass transfer rates for the mixing of water and butanol in two-layer, TBP-aqueous mixtures, where the top layer is primarily TBP and the bottom layer is comprised of water or aqueous salt solution. Mass transfer coefficients are derived for use in the modeling of two-layer TBP-nitric acid oxidation experiments. Three cases were investigated: (1) transfer of water into the TBP layer with sparging of both the aqueous and TBP layers, (2) transfer of water into the TBP layer with sparging of just the TBP layer, and (3) transfer of butanol into the aqueous layer with sparging of both layers. The TBP layer was comprised of 99% pure TBP (spiked with butanol for the butanol transfer experiments), and the aqueous layer was comprised of either water or an aluminum nitrate solution. The liquid layers were air sparged to simulate the mixing due to the evolution of gases generated by oxidation reactions. A plastic tube and a glass frit sparger were used to provide different size bubbles. Rates of mass transfer were measured using infrared spectrophotometers provided by SRTC/Analytical Development.

Laurinat, J.E.

1994-09-28T23:59:59.000Z

75

A three-dimensional model of microbial transport and biodegradation at the Schoolcraft, Michigan, site  

E-Print Network (OSTI)

-dimensional reactive transport modeling of carbon tetrachloride (CT) bioremediation at the Schoolcraft site in western

76

A case against Kd-based transport models: natural attenuation at a mill tailings site  

Science Journals Connector (OSTI)

This study compares numerical modeling results of contaminant transport using a multi-component coupled reactive mass transport model and a distribution coefficient (Kd)-based transport model. The study site is a contaminated groundwater ... Keywords: contaminant, coupled processes, geochemical modeling, transport

Chen Zhu

2003-04-01T23:59:59.000Z

77

An Equilibrium-Based Model of Gas Reaction and Detonation  

SciTech Connect

During gaseous diffusion plant operations, conditions leading to the formation of flammable gas mixtures may occasionally arise. Currently, these could consist of the evaporative coolant CFC-114 and fluorinating agents such as F2 and ClF3. Replacement of CFC-114 with a non-ozone-depleting substitute is planned. Consequently, in the future, the substitute coolant must also be considered as a potential fuel in flammable gas mixtures. Two questions of practical interest arise: (1) can a particular mixture sustain and propagate a flame if ignited, and (2) what is the maximum pressure that can be generated by the burning (and possibly exploding) gas mixture, should it ignite? Experimental data on these systems, particularly for the newer coolant candidates, are limited. To assist in answering these questions, a mathematical model was developed to serve as a tool for predicting the potential detonation pressures and for estimating the composition limits of flammability for these systems based on empirical correlations between gas mixture thermodynamics and flammability for known systems. The present model uses the thermodynamic equilibrium to determine the reaction endpoint of a reactive gas mixture and uses detonation theory to estimate an upper bound to the pressure that could be generated upon ignition. The model described and documented in this report is an extended version of related models developed in 1992 and 1999.

Trowbridge, L.D.

2000-04-01T23:59:59.000Z

78

The National Energy Modeling System: An Overview 2000 - Transportation  

Gasoline and Diesel Fuel Update (EIA)

transportation demand module (TRAN) forecasts the consumption of transportation sector fuels by transportation mode, including the use of renewables and alternative fuels, subject to delivered prices of energy fuels and macroeconomic variables, including disposable personal income, gross domestic product, level of imports and exports, industrial output, new car and light truck sales, and population. The structure of the module is shown in Figure 8. transportation demand module (TRAN) forecasts the consumption of transportation sector fuels by transportation mode, including the use of renewables and alternative fuels, subject to delivered prices of energy fuels and macroeconomic variables, including disposable personal income, gross domestic product, level of imports and exports, industrial output, new car and light truck sales, and population. The structure of the module is shown in Figure 8. Figure 8. Transportation Demand Module Structure NEMS projections of future fuel prices influence the fuel efficiency, vehicle-miles traveled, and alternative-fuel vehicle (AFV) market penetration for the current fleet of vehicles. Alternative-fuel shares are projected on the basis of a multinomial logit vehicle attribute model, subject to State and Federal government mandates.

79

Pattern formation in reaction diffusion systems: a Galerkin model  

Science Journals Connector (OSTI)

Reaction diffusion systems are extremely useful for studying pattern formation in biological systems. We carry out a Lorenz like few mode truncation of a reaction diffusion system and show that it not only giv...

A. Bhattacharyay; J.K. Bhattacharjee

2001-06-01T23:59:59.000Z

80

Modeling biogechemical reactive transport in a fracture zone  

SciTech Connect

A coupled model of groundwater flow, reactive solute transport and microbial processes for a fracture zone of the Aspo site at Sweden is presented. This is the model of the so-called Redox Zone Experiment aimed at evaluating the effects of tunnel construction on the geochemical conditions prevailing in a fracture granite. It is found that a model accounting for microbially-mediated geochemical processes is able to reproduce the unexpected measured increasing trends of dissolved sulfate and bicarbonate. The model is also useful for testing hypotheses regarding the role of microbial processes and evaluating the sensitivity of model results to changes in biochemical parameters.

Molinero, Jorge; Samper, Javier; Yang, Chan Bing, and Zhang, Guoxiang; Guoxiang, Zhang

2005-01-14T23:59:59.000Z

Note: This page contains sample records for the topic "reaction transport model" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Comprehensive model to determine the effects of temperature and species fluctuations on reaction rates in turbulent reaction flows  

SciTech Connect

The use of silane (SiH4) as an effective ignitor and flame stabilizing pilot fuel is well documented. A reliable chemical kinetic mechanism for prediction of its behavior at the conditions encountered in the combustor of a SCRAMJET engine was calculated. The effects of hydrogen addition on hydrocarbon ignition and flame stabilization as a means for reduction of lengthy ignition delays and reaction times were studied. The ranges of applicability of chemical kinetic models of hydrogen-air combustors were also investigated. The CHARNAL computer code was applied to the turbulent reaction rate modeling.

Magnotti, F.; Diskin, G.; Matulaitis, J.; Chinitz, W.

1984-01-01T23:59:59.000Z

82

Targeted Observations for Atmospheric Chemistry and Transport Models  

E-Print Network (OSTI)

for a simulation of atmospheric pollution in East Asia in March 2001 show that the optimal location of observations, targeted observations. 1 Introduction Our ability to anticipate and manage changes in atmospheric pollutantTargeted Observations for Atmospheric Chemistry and Transport Models Adrian Sandu Department

Sandu, Adrian

83

A Microscopic Traffic Simulation Model for Transportation Planning in Georgios Papageorgiou, Pantelis Damianou, Andreas Pitsilides  

E-Print Network (OSTI)

A Microscopic Traffic Simulation Model for Transportation Planning in Cyprus Georgios Papageorgiou. This paper presents the microscopic simulation model development of a major traffic network of Nicosia simulation model is developed and utilized for transportation planning. 1. Introduction The demand

Pitsillides, Andreas

84

Analytical model for flux saturation in sediment transport  

E-Print Network (OSTI)

The transport of sediment by a fluid along the surface is responsible for dune formation, dust entrainment and for a rich diversity of patterns on the bottom of oceans, rivers, and planetary surfaces. Most previous models of sediment transport have focused on the equilibrium (or saturated) particle flux. However, the morphodynamics of sediment landscapes emerging due to surface transport of sediment is controlled by situations out-of-equilibrium. In particular, it is controlled by the saturation length characterizing the distance it takes for the particle flux to reach a new equilibrium after a change in flow conditions. The saturation of mass density of particles entrained into transport and the relaxation of particle and fluid velocities constitute the main relevant relaxation mechanisms leading to saturation of the sediment flux. Here we present a theoretical model for sediment transport which, for the first time, accounts for both these relaxation mechanisms and for the different types of sediment entrainment prevailing under different environmental conditions. Our analytical treatment allows us to derive a closed expression for the saturation length of sediment flux, which is general and can thus be applied under different physical conditions.

T. Phtz; E. J. R. Parteli; J. F. Kok; H. J. Herrmann

2014-05-30T23:59:59.000Z

85

Airflow and Pollutant Transport Modeling In Indoor and Built Environment  

NLE Websites -- All DOE Office Websites (Extended Search)

Airflow and Pollutant Transport Modeling In Indoor and Built Environment Airflow and Pollutant Transport Modeling In Indoor and Built Environment Speaker(s): Teshome Edae Jiru Date: October 12, 2009 - 12:12pm Location: 90-3122 Computer simulation is based on mathematical models developed mostly from theoretical science and helps for studying and prediction of the behavior of engineered systems. The advantages of computer simulation are the ease of varying the desired parameters to investigate various possible design scenarios, explore new theories, and design new experiments to test these theories. It also provides detailed information and serves as a powerful alternative to experimental science and observation when phenomena are not observable or when measurements are impractical or too expensive. This seminar presents the different types of mechanistic modeling approaches

86

Water Transport in PEM Fuel Cells: Advanced Modeling, Material Selection, Testing, and Design Optimization  

NLE Websites -- All DOE Office Websites (Extended Search)

in PEM Fuel Cells: in PEM Fuel Cells: Advanced Modeling, Material Selection, Testing, and Design Optimization J. Vernon Cole and Ashok Gidwani CFDRC Prepared for: DOE Hydrogen Fuel Cell Kickoff Meeting February 13, 2007 This presentation does not contain any proprietary or confidential information. Background Water Management Issues Arise From: ƒ Generation of water by cathodic reaction ƒ Membrane humidification requirements ƒ Capillary pressure driven transport through porous MEA and GDL materials ƒ Scaling bipolar plate channel dimensions J.H. Nam and M. Kaviany, Int. J. Heat Mass Transfer, 46, pp. 4595-4611 (2003) Relevant Barriers and Targets ƒ Improved Gas Diffusion Layer, Flow Fields, Membrane Electrode Assemblies Needed to Improve Water Management: * Flooding blocks reactant transport

87

3D Field-Scale Reactive Transport Modeling of In Situ Immobilization of Uranium in Structured Porous Media via Biostimulation  

SciTech Connect

A several-month-long ethanol injection experiment is being conducted to study the impacts of porous media structure (i.e., heterogeneity existing at multiple scales) on the effectiveness of metal/radionuclide bioremediation in a highly heterogeneous unconfined aquifer near Oak Ridge, TN, USA. We have constructed a 3D field-scale groundwater flow and multicomponent reactive transport model to simulate the experimental observations. The model incorporates a suite of abiotic reactions and microbially-mediated redox reactions for multiple terminal electron accepting processes (TEAPs) including soluble oxygen, nitrate, U(VI) and sulfate and solid-phase electron acceptors. Different biomass populations are considered in the model. Growth of these populations is derived from the bioenergetics-based approach in which the partitioning of electron flow between energy generation and cell biomass production is dependent on the free energy of the corresponding TEAP. TEAP reaction rates were free energy constrained. The TEAP model and reaction system have been formulated and used to simulate laboratory batch experimental observations. We conducted the field-scale simulation starting with the reaction system and parameters obtained from the batch experiment and hydrologic parameters estimated from the results of pumping tests, water level monitoring and model interpretation of a tracer test conducted in August 2004. Reaction parameters were investigated to compare simulation results and field experiment observations.

Fang, Yilin; Scheibe, Timothy D.; Roden, Eirc E.; Kamolpornwijit, Wiwat; Brooks, Scott C.

2006-09-12T23:59:59.000Z

88

Validation of transport models using additive flux minimization technique  

SciTech Connect

A new additive flux minimization technique is proposed for carrying out the verification and validation (V and V) of anomalous transport models. In this approach, the plasma profiles are computed in time dependent predictive simulations in which an additional effective diffusivity is varied. The goal is to obtain an optimal match between the computed and experimental profile. This new technique has several advantages over traditional V and V methods for transport models in tokamaks and takes advantage of uncertainty quantification methods developed by the applied math community. As a demonstration of its efficiency, the technique is applied to the hypothesis that the paleoclassical density transport dominates in the plasma edge region in DIII-D tokamak discharges. A simplified version of the paleoclassical model that utilizes the Spitzer resistivity for the parallel neoclassical resistivity and neglects the trapped particle effects is tested in this paper. It is shown that a contribution to density transport, in addition to the paleoclassical density transport, is needed in order to describe the experimental profiles. It is found that more additional diffusivity is needed at the top of the H-mode pedestal, and almost no additional diffusivity is needed at the pedestal bottom. The implementation of this V and V technique uses the FACETS::Core transport solver and the DAKOTA toolkit for design optimization and uncertainty quantification. The FACETS::Core solver is used for advancing the plasma density profiles. The DAKOTA toolkit is used for the optimization of plasma profiles and the computation of the additional diffusivity that is required for the predicted density profile to match the experimental profile.

Pankin, A. Y.; Kruger, S. E. [Tech-X Corporation, 5621 Arapahoe Ave., Boulder, Colorado 80303 (United States)] [Tech-X Corporation, 5621 Arapahoe Ave., Boulder, Colorado 80303 (United States); Groebner, R. J. [General Atomics, San Diego, California 92121 (United States)] [General Atomics, San Diego, California 92121 (United States); Hakim, A. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451 (United States)] [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451 (United States); Kritz, A. H.; Rafiq, T. [Department of Physics, Lehigh University, Bethlehem, Pennsylvania 18015 (United States)] [Department of Physics, Lehigh University, Bethlehem, Pennsylvania 18015 (United States)

2013-10-15T23:59:59.000Z

89

Improved Geothermometry Through Multivariate Reaction Path Modeling and Evaluation of Geomicrobiological Influences on Geochemical Temperature Indicators  

Energy.gov (U.S. Department of Energy (DOE))

Improved Geothermometry Through Multivariate Reaction Path Modeling and Evaluation of Geomicrobiological Influences on Geochemical Temperature Indicators presentation at the April 2013 peer review meeting held in Denver, Colorado.

90

Basic Reaction Model of Automobile Exhaust Gas Treatment over Pt?Rh Catalyst  

Science Journals Connector (OSTI)

Basic Reaction Model of Automobile Exhaust Gas Treatment over Pt?Rh Catalyst ... The reactor is heated by a three-section electric furnace. ...

Motoaki Kawase; Hiroyasu Fujitsuka; Hitoshi Nakanishi; Tatsuya Yoshikawa; Kouichi Miura

2010-09-02T23:59:59.000Z

91

Model documentation report: Transportation sector model of the National Energy Modeling System  

SciTech Connect

This report documents the objectives, analytical approach and development of the National Energy Modeling System (NEMS) Transportation Model (TRAN). The report catalogues and describes the model assumptions, computational methodology, parameter estimation techniques, model source code, and forecast results generated by the model. This document serves three purposes. First, it is a reference document providing a detailed description of TRAN for model analysts, users, and the public. Second, this report meets the legal requirements of the Energy Information Administration (EIA) to provide adequate documentation in support of its statistical and forecast reports (Public Law 93-275, 57(b)(1)). Third, it permits continuity in model development by providing documentation from which energy analysts can undertake model enhancements, data updates, and parameter refinements.

Not Available

1994-03-01T23:59:59.000Z

92

Sediment and radionuclide transport in rivers: radionuclide transport modeling for Cattaraugus and Buttermilk Creeks, New York  

SciTech Connect

SERATRA, a transient, two-dimensional (laterally-averaged) computer model of sediment-contaminant transport in rivers, satisfactorily resolved the distribution of sediment and radionuclide concentrations in the Cattaraugus Creek stream system in New York. By modeling the physical processes of advection, diffusion, erosion, deposition, and bed armoring, SERATRA routed three sediment size fractions, including cohesive soils, to simulate three dynamic flow events. In conjunction with the sediment transport, SERATRA computed radionuclide levels in dissolved, suspended sediment, and bed sediment forms for four radionuclides (/sup 137/Cs, /sup 90/Sr, /sup 239/ /sup 240/Pu, and /sup 3/H). By accounting for time-dependent sediment-radionuclide interaction in the water column and bed, SERATA is a physically explicit model of radionuclide fate and migration. Sediment and radionuclide concentrations calculated by SERATA in the Cattaraugus Creek stream system are in reasonable agreement with measured values. SERATRA is in the field performance phase of an extensive testing program designed to establish the utility of the model as a site assessment tool. The model handles not only radionuclides but other contaminants such as pesticides, heavy metals and other toxic chemicals. Now that the model has been applied to four field sites, including the latest study of the Cattaraugus Creek stream system, it is recommended that a final model be validated through comparison of predicted results with field data from a carefully controlled tracer test at a field site. It is also recommended that a detailed laboratory flume be tested to study cohesive sediment transport, deposition, and erosion characteristics. The lack of current understanding of these characteristics is one of the weakest areas hindering the accurate assessment of the migration of radionuclides sorbed by fine sediments of silt and clay.

Onishi, Y.; Yabusaki, S.B.; Kincaid, C.T.; Skaggs, R.L.; Walters, W.H.

1982-12-01T23:59:59.000Z

93

Advancements in the ADAPT Photospheric Flux Transport Model  

E-Print Network (OSTI)

Maps of the solar photospheric magnetic flux are fundamental drivers for simulations of the corona and solar wind which makes photospheric simulations important predictors of solar events on Earth. However, observations of the solar photosphere are only made intermittently over small regions of the solar surface. The Air Force Data Assimilative Photospheric Flux Transport (ADAPT) model uses localized ensemble Kalman filtering techniques to adjust a set of photospheric simulations to agree with the available observations. At the same time this information is propagated to areas of the simulation that have not been observed. ADAPT implements a local ensemble transform Kalman filter (LETKF) to accomplish data assimilation, allowing the covariance structure of the flux transport model to influence assimilation of photosphere observations while eliminating spurious correlations between ensemble members arising from a limited ensemble size. We give a detailed account of the ADAPT model and the implementation of the LETKF. Advantages of the LETKF scheme over previously implemented assimilation methods are highlighted.

Kyle S. Hickmann; Humberto C. Godinez; Carl J. Henney; C. Nick Arge

2014-10-22T23:59:59.000Z

94

Transportation  

NLE Websites -- All DOE Office Websites (Extended Search)

Transportation Transportation Transportation of Depleted Uranium Materials in Support of the Depleted Uranium Hexafluoride Conversion Program Issues associated with transport of depleted UF6 cylinders and conversion products. Conversion Plan Transportation Requirements The DOE has prepared two Environmental Impact Statements (EISs) for the proposal to build and operate depleted uranium hexafluoride (UF6) conversion facilities at its Portsmouth and Paducah gaseous diffusion plant sites, pursuant to the National Environmental Policy Act (NEPA). The proposed action calls for transporting the cylinder at ETTP to Portsmouth for conversion. The transportation of depleted UF6 cylinders and of the depleted uranium conversion products following conversion was addressed in the EISs.

95

Analytical impurity transport model: Coupling between particle and charge state transports in tokamak plasmas  

SciTech Connect

Interpretation and understanding of a set of coupled continuity equations commonly used in impurity tokamak transport studies are found to be syncretic and inadequate, since they do not distinguish between the cross-field fluxes of impurity particles and of their charge states (cs). An analytical approach to impurity transport studies previously developed is generalized to the case of diffusive-convective cs dynamics and provides a set of dimensionless parameters to describe the impurity behavior more correctly than using empirical coefficients D and V, which, in turn, have to be interpreted in terms of their cs, rather than of particles. An analytical transport model (ATM) with underlying interpretation is proposed. It is based on the solutions of two separate transport problems for impurity cs and particles instead of a single one. It is shown that ATM consistently explains two groups of available empirical dependences regarding the scaling D{proportional_to}n{sub e}{sup -1} and the profiles of V/D, which are shown to be the density profile gradients, {nabla}n{sub Z}/n{sub Z} and suggests the neoclassical scale of the particle diffusion coefficient.

Shurygin, V. A. [Nuclear Fusion Institute, Russian Research Centre Kurchatov Institute, Kurchatov Sq. 1, Moscow, 123182 (Russian Federation)

2008-01-15T23:59:59.000Z

96

Modeling the Influence of GDL and flow-field plate parameters on the reaction distribution in the PEMFC cathode catalyst layer  

Science Journals Connector (OSTI)

In this paper, a two-dimensional cross-the-channel model was applied to investigate the influence of gas diffusion layer (GDL) property and flow-field geometry on the local reaction rate in the PEMFC cathode catalyst layer. The model predictions show that the rate of consumption of oxygen or current density under the land area may differ considerably from that under the channel. Simulation results indicate that for a fixed channel width, increasing the channel-to-land width ratio results in improved water transport and positively impacts the overall reaction rates at high overpotential. However, too high ratio may retard electron transport and thus lead to worse cathode performance. Numerical simulation results revealed that GDL electrical conductivity and thickness have a strong influence on how the chemical species and electrons are transported to the active catalyst sites. Depending on the electrical conductivity of GDL, the region of higher reaction rate may occur either under the land or under the channel. Consideration of orthotropic electrical conductivity of GDL affects the simulation results significantly highlighting the need to improve our understanding of GDL transport coefficients. Simulation of GDL compression effects showed that the total current density is not affected significantly but current density distribution is. The extent of reactant bypass through the GDL from one channel to the other depends on the GDL permeability and results in a significant enhancement in reaction rates.

Wei Sun; Brant A. Peppley; Kunal Karan

2005-01-01T23:59:59.000Z

97

On the Upscaling of Reaction-Transport Processes in Porous Media with Fast Kinetics  

SciTech Connect

This report is organized as follows: Provide a brief review of the upscaling constraints of the type (2) for a typical diffusion-reaction system. In this an analogy with two-phase flow in porous media was drawn. Then, using the methodology of QW a problem at the unit cell for the computation of the effective mass transfer coefficient, in processes where local thermodynamic equilibrium applies was derived. This problem is found to be different than in QW, as it depends on the gradients of the macroscale variable, and can be cast in terms of an eigenvalue problem. Two simple, examples, one involving advection-dissolution and another involving drying in a pore network, was presented to illustrate the coupling between scales and to show the quantitative effect in case this coupling was neglected. Finally, similar ideas and an illustrative example was applied to reaction-diffusion systems with fast kinetics, where an equilibrium state is approached.

Kechagi, P.; Tsimpanogiannis, I.; Yortsos, Y.C.; Lichtner, P.

2001-01-09T23:59:59.000Z

98

Transportation  

NLE Websites -- All DOE Office Websites (Extended Search)

Health Risks » Transportation Health Risks » Transportation DUF6 Health Risks line line Accidents Storage Conversion Manufacturing Disposal Transportation Transportation A discussion of health risks associated with transport of depleted UF6. Transport Regulations and Requirements In the future, it is likely that depleted uranium hexafluoride cylinders will be transported to a conversion facility. For example, it is currently anticipated that the cylinders at the ETTP Site in Oak Ridge, TN, will be transported to the Portsmouth Site, OH, for conversion. Uranium hexafluoride has been shipped safely in the United States for over 40 years by both truck and rail. Shipments of depleted UF6 would be made in accordance with all applicable transportation regulations. Shipment of depleted UF6 is regulated by the

99

MELTING OF GLASS BATCH: MODEL FOR MULTIPLE OVERLAPPING GAS-EVOLVING REACTIONS  

SciTech Connect

In this study, we present a model for the kinetics of multiple overlapping reactions. Mathematical representation of the kinetics of gas-evolving reactions is crucial for the modeling of the feed-to-glass conversion in a waste-glass melter. The model simulates multiple gas-evolving reactions that occur during heating of a high-alumina high-level waste melter feed. To obtain satisfactory kinetic parameters, we employed Kissinger's method combined with least-squares analysis. The power-law kinetics with variable reaction order sufficed for obtaining excellent agreement with measured thermogravimetric analysis data.

Pokorny, Richard; Pierce, David A.; Hrma, Pavel R.

2012-08-10T23:59:59.000Z

100

Microfluidic Technology Platforms for Synthesizing, Labeling and Measuring the Kinetics of Transport and Biochemical Reactions for Developing Molecular Imaging Probes  

SciTech Connect

Radiotracer techniques are used in environmental sciences, geology, biology and medicine. Radiotracers with Positron Emission Tomography (PET) provided biological examinations of ~3 million patients 2008. Despite the success of positron labeled tracers in many sciences, there is limited access in an affordable and convenient manner to develop and use new tracers. Integrated microfluidic chips are a new technology well matched to the concentrations of tracers. Our goal is to develop microfluidic chips and new synthesis approaches to enable wide dissemination of diverse types of tracers at low cost, and to produce new generations of radiochemists for which there are many unfilled jobs. The program objectives are to: 1. Develop an integrated microfluidic platform technology for synthesizing and 18F-labeling diverse arrays of different classes of molecules. 2. Incorporate microfluidic chips into small PC controlled devices (Synthesizer) with a platform interfaced to PC for electronic and fluid input/out control. 3. Establish a de-centralized model with Synthesizers for discovering and producing molecular imaging probes, only requiring delivery of inexpensive [18F]fluoride ion from commercial PET radiopharmacies vs the centralized approach of cyclotron facilities synthesizing and shipping a few different types of 18F-probes. 4. Develop a position sensitive avalanche photo diode (PSAPD) camera for beta particles embedded in a microfluidic chip for imaging and measuring transport and biochemical reaction rates to valid new 18F-labeled probes in an array of cell cultures. These objectives are met within a research and educational program integrating radio-chemistry, synthetic chemistry, biochemistry, engineering and biology in the Crump Institute for Molecular Imaging. The Radiochemistry Training Program exposes PhD and post doctoral students to molecular imaging in vitro in cells and microorganisms in microfluidic chips and in vivo with PET, from new technologies for radiochemistry (macro to micro levels), biochemistry and biology to imaging principles, tracer kinetics, pharmacokinetics and biochemical assays. New generations of radiochemists will be immersed in the biochemistry and biology for which their labeled probes are being developed for assays of these processes. In this program engineers and radio-chemists integrate the principles of microfluidics and radiolabeling along with proper system design and chemistry rule sets to yield Synthesizers enabling biological and pharmaceutical scientists to develop diverse arrays of probes to pursue their interests. This progression would allow also radiochemists to focus on the further evolution of rapid, high yield synthetic reactions with new enabling technologies, rather than everyday production of radiotracers that should be done by technologists. The invention of integrated circuits in electronics established a platform technology that allowed an evolution of ideas and applications far beyond what could have been imagined at the beginning. Rather than provide a technology for the solution to a single problem, it is hoped that microfluidic radiochemistry will be an enabling platform technology for others to solve many problems. As part of this objective, another program goal is to commercialize the technologies that come from this work so that they can be provided to others who wish to use it.

Phelps, Michael E.

2009-09-01T23:59:59.000Z

Note: This page contains sample records for the topic "reaction transport model" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Lessons Learned from Alternative Transportation Fuels: Modeling Transition Dynamics  

Alternative Fuels and Advanced Vehicles Data Center (EERE)

Lessons Learned from Lessons Learned from Alternative Transportation Fuels: Modeling Transition Dynamics C. Welch Technical Report NREL/TP-540-39446 February 2006 Lessons Learned from Alternative Transportation Fuels: Modeling Transition Dynamics C. Welch Prepared under Task Nos. HS04.2000 and HS06.1002 Technical Report NREL/TP-540-39446 February 2006 National Renewable Energy Laboratory 1617 Cole Boulevard, Golden, Colorado 80401-3393 303-275-3000 * www.nrel.gov Operated for the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy by Midwest Research Institute * Battelle Contract No. DE-AC36-99-GO10337 NOTICE This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any

102

Computational Fluid Dynamic Simulations of a Pilot-Scale Transport Coal Gasifier: Evaluation of Reaction Kinetics  

Science Journals Connector (OSTI)

It was found that appropriate chemical kinetics for gasification reactions are key to the numerical prediction of syngas composition and the kinetics from Niksa Energy Associates PC Coal Lab yielded reasonable agreement to the experimental data. ... Air for the primary burner is present below the recycle feed, and additional air is fed into the mixing zone from various locations between coal and recycle inlets; this arrangement evenly distributes heat generated from the partial combustion of the circulating solids. ... Char burning rates become faster with coals of progressively lower rank, although the reactivity is somewhat less sensitive to coal quality at elevated pressure than at atm. pressure. ...

Tingwen Li; Kiran Chaudhari; Dirk VanEssendelft; Richard Turton; Philip Nicoletti; Mehrdad Shahnam; Chris Guenther

2013-11-18T23:59:59.000Z

103

Investigation of Multiscale and Multiphase Flow, Transport and Reaction in Heavy Oil Recovery Processes  

SciTech Connect

In this report, the thrust areas include the following: Internal drives, vapor-liquid flows, combustion and reaction processes, fluid displacements and the effect of instabilities and heterogeneities and the flow of fluids with yield stress. These find respective applications in foamy oils, the evolution of dissolved gas, internal steam drives, the mechanics of concurrent and countercurrent vapor-liquid flows, associated with thermal methods and steam injection, such as SAGD, the in-situ combustion, the upscaling of displacements in heterogeneous media and the flow of foams, Bingham plastics and heavy oils in porous media and the development of wormholes during cold production.

Yortsos, Yanis C.

2002-10-08T23:59:59.000Z

104

Optimizing Large Scale Chemical Transport Models for Multicore Platforms John C. Linford and Adrian Sandu  

E-Print Network (OSTI)

Optimizing Large Scale Chemical Transport Models for Multicore Platforms John C. Linford and Adrian: Chemical Transport Model, Domain Decom- position, Time Splitting, Multicore, Scalability, IBM Cell Broadband Engine, Intel Quad-Core Xeon. Abstract The performance of a typical chemical transport model

Sandu, Adrian

105

Reactive transport model for the ambient unsaturated hydrogeochemical system at Yucca mountain, Nevada  

Science Journals Connector (OSTI)

To assist a technical review of a potential application for a geologic repository, a reactive transport model is presented for the ambient hydrogeochemical system at Yucca Mountain (YM). The model simulates two-phase, nonisothermal, advective and diffusive ... Keywords: Yucca mountain, geochemistry, groundwater chemistry, groundwater flow and transport, hydrology, reactive transport model, unsaturated zone

Lauren Browning; William M. Murphy; Chandrika Manepally; Randall Fedors

2003-04-01T23:59:59.000Z

106

The importance of transport parameter cross correlations in natural systems radioactive transport models  

SciTech Connect

Transport parameter cross correlations are rarely considered in models used to predict radionuclide transport in natural systems. In this paper, it is shown that parameter cross correlations could have a significant impact on radionuclide transport predictions in saturated media. In fractured rock, the positive correlation between fracture apertures and groundwater residence times is shown to result in significantly less retardation due to matrix diffusion than is predicted without the correlation. The suppression of matrix diffusion is further amplified by a tendency toward larger apertures, smaller matrix diffusion coefficients, and less sorption capacity in rocks of lower matrix porosity. In a hypothetical example, strong cross correlations between these parameters result in a decrease in predicted radionuclide travel times of an order of magnitude or more relative to travel times calculated with uncorrelated parameters. In porous media, expected correlations between permeability, porosity, and sorption capacity also result in shorter predicted travel times than when the parameters are assumed to be uncorrelated. Individual parameter standard deviations can also have a significant influence on predicted radionuclide travel times, particularly when cross correlations are considered.

Reimus, Paul W [Los Alamos National Laboratory

2011-01-03T23:59:59.000Z

107

Cold-cap reactions in vitrification of nuclear waste glass: experiments and modeling  

SciTech Connect

Cold-cap reactions are multiple overlapping reactions that occur in the waste-glass melter during the vitrification process when the melter feed is being converted to molten glass. In this study, we used differential scanning calorimetry (DSC) to investigate cold-cap reactions in a high-alumina high-level waste melter feed. To separate the reaction heat from both sensible heat and experimental instability, we employed the run/rerun method, which enabled us to define the degree of conversion based on the reaction heat and to estimate the heat capacity of the reacting feed. Assuming that the reactions are nearly independent and can be approximated by the nth order kinetics, we obtained the kinetic parameters using the Kissinger method combined with least squares analysis. The resulting mathematical simulation of the cold-cap reactions provides a key element for the development of an advanced cold-cap model.

Chun, Jaehun [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Pierce, David A. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Pokorny, Richard [Inst. of Chemical Technology, Prague (Czech Republic); Hrma, Pavel R. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Pohang Univ. of Science and Techology (Korea, Republic of)

2013-05-10T23:59:59.000Z

108

A reaction-diffusion model of the human brain development  

Science Journals Connector (OSTI)

The anatomical variability of the human brain folds remains an unclear and challenging issue. Several hypotheses coexist for explaining the rapid development of cortical sulci and it is clear that understanding their variability would improve the comparison ... Keywords: brain development, folding, reaction-diffusion equations

Julien Lefvre; Jean-Franois Mangin

2010-04-01T23:59:59.000Z

109

Application of a new screening model to thermonuclear reactions of the rp process  

E-Print Network (OSTI)

A new screening model for astrophysical thermonuclear reactions was derived recently which improved Salpeter's weak-screening one. In the present work we prove that the new model can also give very reliable screening enhancement factors (SEFs) when applied to the rp process. According to the results of the new model, which agree well with Mitler's SEFs, the screened rp reaction rates can be, at most, twice as fast as the unscreened ones.

Theodore Liolios

2003-05-09T23:59:59.000Z

110

Multiphysics modeling of lithium ion battery capacity fading process with solid-electrolyte interphase growth by elementary reaction kinetics  

Science Journals Connector (OSTI)

Abstract A pseudo two-dimensional mathematical model is developed for a lithium ion battery, integrating the elementary reaction based solid-electrolyte interphase (SEI) growth model with multiple transport processes. The model is validated using the experimental data. Simulation results indicate that the operating temperature has great effect on the SEI layer generation and growth. Under different chargingdischarging rates, it is found that high chargingdischarging rate can intensify the battery capacity fading process. Different cooling conditions are then applied and show that enhanced surface convective cooling condition can effectively slow down the battery capacity fading. After that, the effect of electrolyte salt concentration and exchange current density are studied. It is found that raising the electrolyte salt concentration can improve the diffusion property of lithium ions, and stabilize the battery performance under lithium ion consumption induced resistance rising. It also suggests that improving exchange current density could greatly decrease the lithium ion battery capacity fading.

Yuanyuan Xie; Jianyang Li; Chris Yuan

2014-01-01T23:59:59.000Z

111

The Development and Application of Reactive Transport Modeling Techniques to Study Radionuclide Migration at Yucca Mountain, NV  

SciTech Connect

Yucca Mountain, Nevada has been chosen as a possible site for the first high level radioactive waste repository in the United States. As part of the site investigation studies, we need to make scientifically rigorous estimations of radionuclide migration in the event of a repository breach. Performance assessment models used to make these estimations are computationally intensive. We have developed two reactive transport modeling techniques to simulate radionuclide transport at Yucca Mountain: (1) the selective coupling approach applied to the convection-dispersion-reaction (CDR) model and (2) a reactive stream tube approach (RST). These models were designed to capture the important processes that influence radionuclide migration while being computationally efficient. The conventional method of modeling reactive transport models is to solve a coupled set of multi-dimensional partial differential equations for the relevant chemical components in the system. We have developed an iterative solution technique, denoted the selective coupling method, that represents a versatile alternative to traditional uncoupled iterative techniques and the filly coupled global implicit method. We show that selective coupling results in computational and memory savings relative to these approaches. We develop RST as an alternative to the CDR method for solving large two- or three-dimensional reactive transport simulations for cases in which one is interested in predicting the flux across a specific control plane. In the RST method, the multidimensional problem is reduced to a series of one-dimensional transport simulations along streamlines. The key assumption with RST is that mixing at the control plane approximates the transverse dispersion between streamlines. We compare the CDR and RST approaches for several scenarios that are relevant to the Yucca Mountain Project. For example, we apply the CDR and RST approaches to model an ongoing field experiment called the Unsaturated Zone Transport Test.

Viswanathan, Hari Selvi

1999-09-01T23:59:59.000Z

112

A minimum-reaction-flux solution to master-equation models of protein folding  

E-Print Network (OSTI)

A minimum-reaction-flux solution to master-equation models of protein folding Huan-Xiang Zhoua; published online 20 May 2008 Master equations are widely used for modeling protein folding. Here- ceptual and quantitative models for protein folding.1­15 In such models, the conformational space

Weston, Ken

113

Environmental Transport Input Parameters for the Biosphere Model  

SciTech Connect

This analysis report is one of the technical reports documenting the Environmental Radiation Model for Yucca Mountain, Nevada (ERMYN), a biosphere model supporting the total system performance assessment for the license application (TSPA-LA) for the geologic repository at Yucca Mountain. A graphical representation of the documentation hierarchy for the ERMYN is presented in Figure 1-1. This figure shows relationships among the reports developed for biosphere modeling and biosphere abstraction products for the TSPA-LA, as identified in the ''Technical Work Plan for Biosphere Modeling and Expert Support'' (BSC 2004 [DIRS 169573]) (TWP). This figure provides an understanding of how this report contributes to biosphere modeling in support of the license application (LA). This report is one of the five reports that develop input parameter values for the biosphere model. The ''Biosphere Model Report'' (BSC 2004 [DIRS 169460]) describes the conceptual model and the mathematical model. The input parameter reports, shown to the right of the Biosphere Model Report in Figure 1-1, contain detailed description of the model input parameters. The output of this report is used as direct input in the ''Nominal Performance Biosphere Dose Conversion Factor Analysis'' and in the ''Disruptive Event Biosphere Dose Conversion Factor Analysis'' that calculate the values of biosphere dose conversion factors (BDCFs) for the groundwater and volcanic ash exposure scenarios, respectively. The purpose of this analysis was to develop biosphere model parameter values related to radionuclide transport and accumulation in the environment. These parameters support calculations of radionuclide concentrations in the environmental media (e.g., soil, crops, animal products, and air) resulting from a given radionuclide concentration at the source of contamination (i.e., either in groundwater or in volcanic ash). The analysis was performed in accordance with the TWP (BSC 2004 [DIRS 169573]).

M. Wasiolek

2004-09-10T23:59:59.000Z

114

Modelling proton-induced reactions at low energies in the MARS15 code  

E-Print Network (OSTI)

An implementation of both the ALICE code and TENDL evaluated nuclear data library in order to describe nuclear reactions by low-energy projectiles in the Monte Carlo code MARS15 is presented. Comparisons between results of modelling and experimental data on reaction cross sections and secondary particle distributions are shown as well.

Rakhno, Igor L; Gudima, Konstantin K

2015-01-01T23:59:59.000Z

115

MODELLING OF CONCRETE STRUCTURES AFFECTED BY INTERNAL SWELLING REACTIONS: COUPLINGS BETWEEN  

E-Print Network (OSTI)

, France Abstract Alkali Aggregate Reaction (AAR) and Delayed Ettringite Formation (DEF) cause expansion Ettringite Formation, Modelling, Coupling 1. INTRODUCTION Alkali Aggregate Reaction (AAR) and Delayed Ettringite Formation (DEF) are both Internal Swelling Processes (ISP) that can affect concrete. In the first

Paris-Sud XI, Université de

116

Transportation System Risk Assessment (TSRA) bounding release model  

SciTech Connect

Transportation System Risk Assessments (TSRAs) document the compliance of proposed shipments of nuclear components with applicable federal regulations as well as the associated risks involved. If a relatively simple bounding analysis can show that the consequences resulting from a worst case scenario are acceptably low, a more time intensive and costly risk analysis can be avoided. Therefore, a bounding release FORTRAN model has been developed to determine the consequences of a worst case non-criticality transportation accident. The consequences of three conservative bounding accidents are determined by the model: (1) direct radiation exposure, (2) airborne release of radiological and/or hazardous solid material, and (3) release of radiological and/or hazardous solid material into a waterway and subsequent uptake by an individual through drinking water. Program output includes the direct radiation exposure (mrem), maximum downwind concentration (mg/m{sup 3}), radiation dose (mrem) received as a result of the postulated airborne release of radiological material, intake (mg) due to inhalation, radiation dose (mrem) received by an individual resulting from a release of radiological material into a waterway and uptake into drinking water, and uptake (mg) due to ingestion. This report documents the methodologies and correlations used in the numerical model to perform the bounding consequence calculations.

Anderson, J.C.

1997-10-01T23:59:59.000Z

117

A model of sediment resuspension and transport dynamics in southern Lake Michigan  

E-Print Network (OSTI)

A model of sediment resuspension and transport dynamics in southern Lake Michigan Jing Lou-three-dimensional suspended sediment transport model was developed and generalized to include combined wave-current effects to study bottom sediment resuspension and transport in southern Lake Michigan. The results from a three

118

Environmental Transport Input Parameters for the Biosphere Model  

SciTech Connect

This analysis report is one of the technical reports documenting the Environmental Radiation Model for Yucca Mountain Nevada (ERMYN), a biosphere model supporting the total system performance assessment (TSPA) for the geologic repository at Yucca Mountain. A graphical representation of the documentation hierarchy for the ERMYN is presented in Figure 1-1. This figure shows relationships among the reports developed for biosphere modeling and biosphere abstraction products for the TSPA, as identified in the ''Technical Work Plan: for Biosphere Modeling and Expert Support'' (TWP) (BSC 2003 [163602]). Some documents in Figure 1-1 may be under development and not available when this report is issued. This figure provides an understanding of how this report contributes to biosphere modeling in support of the license application (LA), but access to the listed documents is not required to understand the contents of this report. This report is one of the reports that develops input parameter values for the biosphere model. The ''Biosphere Model Report'' (BSC 2003 [160699]) describes the conceptual model, the mathematical model, and the input parameters. The purpose of this analysis is to develop biosphere model parameter values related to radionuclide transport and accumulation in the environment. These parameters support calculations of radionuclide concentrations in the environmental media (e.g., soil, crops, animal products, and air) resulting from a given radionuclide concentration at the source of contamination (i.e., either in groundwater or volcanic ash). The analysis was performed in accordance with the TWP (BSC 2003 [163602]). This analysis develops values of parameters associated with many features, events, and processes (FEPs) applicable to the reference biosphere (DTN: M00303SEPFEPS2.000 [162452]), which are addressed in the biosphere model (BSC 2003 [160699]). The treatment of these FEPs is described in BSC (2003 [160699], Section 6.2). Parameter values developed in this report, and the related FEPs, are listed in Table 1-1. The relationship between the parameters and FEPs was based on a comparison of the parameter definition and the FEP descriptions as presented in BSC (2003 [160699], Section 6.2). The parameter values developed in this report support the biosphere model and are reflected in the TSPA through the biosphere dose conversion factors (BDCFs). Biosphere modeling focuses on radionuclides screened for the TSPA-LA (BSC 2002 [160059]). The same list of radionuclides is used in this analysis (Section 6.1.4). The analysis considers two human exposure scenarios (groundwater and volcanic ash) and climate change (Section 6.1.5). This analysis combines and revises two previous reports, ''Transfer Coefficient Analysis'' (CRWMS M&O 2000 [152435]) and ''Environmental Transport Parameter Analysis'' (CRWMS M&O 2001 [152434]), because the new ERMYN biosphere model requires a redefined set of input parameters. The scope of this analysis includes providing a technical basis for the selection of radionuclide- and element-specific biosphere parameters (except for Kd) that are important for calculating BDCFs based on the available radionuclide inventory abstraction data. The environmental transport parameter values were developed specifically for use in the biosphere model and may not be appropriate for other applications.

M. A. Wasiolek

2003-06-27T23:59:59.000Z

119

Lattice Boltzmann model for the bimolecular autocatalytic reactiondiffusion equation  

Science Journals Connector (OSTI)

Abstract A lattice Boltzmann model for the bimolecular autocatalytic reactiondiffusion equation is proposed. By using multi-scale technique and the ChapmanEnskog expansion on complex lattice Boltzmann equation, we obtain a series of complex partial differential equations, complex equilibrium distribution function and its complex moments. Then, the complex reactiondiffusion equation is recovered with higher-order accuracy of the truncation error. This equation can be used to describe the bimolecular autocatalytic reactiondiffusion systems, in which a rich variety of behaviors have been observed. Based on this model, the FitzhughNagumo model and the GrayScott model are simulated. The comparisons between the LBM results and the Alternative Direction Implicit results are given in detail. The numerical examples show that assumptions of source term can be used to raise the accuracy of the truncation error of the lattice Boltzmann scheme for the complex reactiondiffusion equation.

Jianying Zhang; Guangwu Yan

2014-01-01T23:59:59.000Z

120

Modified landfill gas generation rate model of first-order kinetics and two-stage reaction  

Science Journals Connector (OSTI)

This investigation was carried out to establish a new domestic landfill gas (LFG) generation rate model that takes...L 0), the reaction rate constant in the first stage (K 1), and ...

Jiajun Chen; Hao Wang

2009-09-01T23:59:59.000Z

Note: This page contains sample records for the topic "reaction transport model" from the National Library of EnergyBeta (NLEBeta).
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to obtain the most current and comprehensive results.


121

Cahn-Hilliard Reaction Model for Isotropic Li-ion Battery Particles  

E-Print Network (OSTI)

Using the recently developed Cahn-Hilliard reaction (CHR) theory, we present a simple mathematical model of the transition from solid-solution radial diffusion to two-phase shrinking-core dynamics during ion intercalation ...

Zeng, Yi

122

Porphyrinquinone compounds as synthetic models of the reaction centre  

Science Journals Connector (OSTI)

Data on the synthesis, steric structure, and photochemical properties of porphyrinquinone compounds as synthetic models of the reaction centre in photosynthesis are examined and described systematically. The bibliography includes 113 references.

V V Borovkov; Rima P Evstigneeva; L N Strekova; E I Filippovich

1989-01-01T23:59:59.000Z

123

An Intelligent System for Reaction Kinetic Modeling and Catalyst Design  

Science Journals Connector (OSTI)

The pruning rules restrict the type of reactants that can enter a reaction and the products that can be formed. ... a?First-order rate constants (kp, kod, kad, kb, ka, kcd) are in terms of mol/(g/h); second-order rate constants (kaa, kh, koa) in m3/(g/h); energy terms (?qod, ?qad, ?qcd) are in kJ/mol; and the entropy term, ?S has been normalized by the universal gas constant (J/(mol/K)). ... using a template of normal operation, whereas, symptomatic searches look for symptoms to direct the search to the fault location. ...

Santhoji Katare; James M. Caruthers; W. Nicholas Delgass; Venkat Venkatasubramanian

2004-02-11T23:59:59.000Z

124

Low energy ($p,?$) reactions in Ni and Cu nuclei using microscopic optical model  

E-Print Network (OSTI)

Radiative capture reactions for low energy protons have been theoretically studied for Ni and Cu isotopes using the microscopic optical model. The optical potential has been obtained in the folding model using different microscopic interactions with the nuclear densities from Relativistic Mean Field calculations. The calculated total cross sections as well as the cross sections for individually low lying levels have been compared with measurements involving stable nuclear targets. Rates for the rapid proton capture process have been evaluated for astrophysically important reactions.

G. Gangopadhyay

2010-08-05T23:59:59.000Z

125

Mixing Cell Model: A One-Dimensional Numerical Model for Assessment of Water Flow and Contaminant Transport in the Unsaturated Zone  

SciTech Connect

This report describes the Mixing Cell Model code, a one-dimensional model for water flow and solute transport in the unsaturated zone under steady-state or transient flow conditions. The model is based on the principles and assumptions underlying mixing cell model formulations. The unsaturated zone is discretized into a series of independent mixing cells. Each cell may have unique hydrologic, lithologic, and sorptive properties. Ordinary differential equations describe the material (water and solute) balance within each cell. Water flow equations are derived from the continuity equation assuming that unit-gradient conditions exist at all times in each cell. Pressure gradients are considered implicitly through model discretization. Unsaturated hydraulic conductivity and moisture contents are determined by the material-specific moisture characteristic curves. Solute transport processes include explicit treatment of advective processes, first-order chain decay, and linear sorption reactions. Dispersion is addressed through implicit and explicit dispersion. Implicit dispersion is an inherent feature of all mixing cell models and originates from the formulation of the problem in terms of mass balance around fully mixed volume elements. Expressions are provided that relate implicit dispersion to the physical dispersion of the system. Two FORTRAN codes were developed to solve the water flow and solute transport equations: (1) the Mixing-Cell Model for Flow (MCMF) solves transient water flow problems and (2) the Mixing Cell Model for Transport (MCMT) solves the solute transport problem. The transient water flow problem is typically solved first by estimating the water flux through each cell in the model domain as a function of time using the MCMF code. These data are stored in either ASCII or binary files that are later read by the solute transport code (MCMT). Code output includes solute pore water concentrations, water and solute inventories in each cell and at each specified output time, and water and solute fluxes through each cell and specified output time. Computer run times for coupled transient water flow and solute transport were typically several seconds on a 2 GHz Intel Pentium IV desktop computer. The model was benchmarked against analytical solutions and finite-element approximations to the partial differential equations (PDE) describing unsaturated flow and transport. Differences between the maximum solute flux estimated by the mixing-cell model and the PDE models were typically less than two percent.

A. S. Rood

2009-04-01T23:59:59.000Z

126

Mixing Cell Model: A One-Dimensional Numerical Model for Assessment of Water Flow and Contaminant Transport in the Unsaturated Zone  

SciTech Connect

This report describes the Mixing Cell Model code, a one-dimensional model for water flow and solute transport in the unsaturated zone under steady-state or transient flow conditions. The model is based on the principles and assumptions underlying mixing cell model formulations. The unsaturated zone is discretized into a series of independent mixing cells. Each cell may have unique hydrologic, lithologic, and sorptive properties. Ordinary differential equations describe the material (water and solute) balance within each cell. Water flow equations are derived from the continuity equation assuming that unit-gradient conditions exist at all times in each cell. Pressure gradients are considered implicitly through model discretization. Unsaturated hydraulic conductivity and moisture contents are determined by the material-specific moisture characteristic curves. Solute transport processes include explicit treatment of advective processes, first-order chain decay, and linear sorption reactions. Dispersion is addressed through implicit and explicit dispersion. Implicit dispersion is an inherent feature of all mixing cell models and originates from the formulation of the problem in terms of mass balance around fully mixed volume elements. Expressions are provided that relate implicit dispersion to the physical dispersion of the system. Two FORTRAN codes were developed to solve the water flow and solute transport equations: (1) the Mixing-Cell Model for Flow (MCMF) solves transient water flow problems and (2) the Mixing Cell Model for Transport (MCMT) solves the solute transport problem. The transient water flow problem is typically solved first by estimating the water flux through each cell in the model domain as a function of time using the MCMF code. These data are stored in either ASCII or binary files that are later read by the solute transport code (MCMT). Code output includes solute pore water concentrations, water and solute inventories in each cell and at each specified output time, and water and solute fluxes through each cell and specified output time. Computer run times for coupled transient water flow and solute transport were typically several seconds on a 2 GHz Intel Pentium IV desktop computer. The model was benchmarked against analytical solutions and finite-element approximations to the partial differential equations (PDE) describing unsaturated flow and transport. Differences between the maximum solute flux estimated by the mixing-cell model and the PDE models were typically less than two percent.

A. S. Rood

2010-10-01T23:59:59.000Z

127

Transportation  

Science Journals Connector (OSTI)

The romantic rides in Sandburgs eagle-car changed society. On the one hand, motor vehicle transportation is an integral thread of societys fabric. On the other hand, excess mobility fractures old neighborh...

David Hafemeister

2014-01-01T23:59:59.000Z

128

An ELLAM Approximation for Advective-Dispersive Transport with Nonlinear Sorption  

E-Print Network (OSTI)

1 An ELLAM Approximation for Advective-Dispersive Transport with Nonlinear Sorption Matthew W model equations governing solute transport and sorption reactions in porous media. Solute transport in the aqueous phase is modeled by standard advection and dif- fusion processes while sorption reactions

Russell, Thomas F.

129

Critical review: Radionuclide transport, sediment transport, and water quality mathematical modeling; and radionuclide adsorption/desorption mechanisms  

SciTech Connect

This report describes the results of a detailed literature review of radionuclide transport models applicable to rivers, estuaries, coastal waters, the Great Lakes, and impoundments. Some representatives sediment transport and water quality models were also reviewed to evaluate if they can be readily adapted to radionuclide transport modeling. The review showed that most available transport models were developed for dissolved radionuclide in rivers. These models include the mechanisms of advection, dispersion, and radionuclide decay. Since the models do not include sediment and radionuclide interactions, they are best suited for simulating short-term radionuclide migration where: (1) radionuclides have small distribution coefficients; (2) sediment concentrations in receiving water bodies are very low. Only 5 of the reviewed models include full sediment and radionuclide interactions: CHMSED developed by Fields; FETRA SERATRA, and TODAM developed by Onishi et al, and a model developed by Shull and Gloyna. The 5 models are applicable to cases where: (1) the distribution coefficient is large; (2) sediment concentrations are high; or (3) long-term migration and accumulation are under consideration. The report also discusses radionuclide absorption/desorption distribution ratios and addresses adsorption/desorption mechanisms and their controlling processes for 25 elements under surface water conditions. These elements are: Am, Sb, C, Ce, Cm, Co, Cr, Cs, Eu, I, Fe, Mn, Np, P, Pu, Pm, Ra, Ru, Sr, Tc, Th, {sup 3}H, U, Zn and Zr.

Onishi, Y.; Serne, R.J.; Arnold, E.M.; Cowan, C.E.; Thompson, F.L. [Pacific Northwest Lab., Richland, WA (United States)

1981-01-01T23:59:59.000Z

130

Modeling the coupling of reaction kinetics and hydrodynamics in a collapsing cavity  

SciTech Connect

We introduce a model of cavitation based on the multiphase Lattice Boltzmann method (LBM) that allows for coupling between the hydrodynamics of a collapsing cavity and supported solute chemical species. We demonstrate that this model can also be coupled to deterministic or stochastic chemical reactions. In a two-species model of chemical reactions (with a major and a minor specie), the major difference observed between the deterministic and stochastic reactions takes the form of random fluctuations in concentration of the minor species. We demonstrate that advection associated with the hydrodynamics of a collapsing cavity leads to highly inhomogeneous concentration of solutes. In turn these inhomogeneities in concentration may lead to significant increase in concentration-dependent reaction rates and can result in a local enhancement in the production of minor species.

Mishra, Sudib [University of Arizona; Deymier, Pierre [University of Arizona; Muralidharan, Krishna [University of Arizona; Frantziskonis, G. [University of Arizona; Pannala, Sreekanth [ORNL; Simunovic, Srdjan [ORNL

2010-01-01T23:59:59.000Z

131

Reactive Transport Modeling of Acid Gas Generation and Condensation  

SciTech Connect

Pulvirenti et al. (2004) recently conducted a laboratory evaporation/condensation experiment on a synthetic solution of primarily calcium chloride. This solution represents one potential type of evaporated pore water at Yucca Mountain, Nevada, a site proposed for geologic storage of high-level nuclear waste. These authors reported that boiling this solution to near dryness (a concentration factor >75,000 relative to actual pore waters) leads to the generation of acid condensate (pH 4.5) presumably due to volatilization of HCl (and minor HF and/or HNO{sub 3}). To investigate the various processes taking place, including boiling, gas transport, and condensation, their experiment was simulated by modifying an existing multicomponent and multiphase reactive transport code (TOUGHREACT). This code was extended with a Pitzer ion-interaction model to deal with high ionic strength. The model of the experiment was set-up to capture the observed increase in boiling temperature (143 C at {approx}1 bar) resulting from high concentrations of dissolved salts (up to 8 m CaCl{sub 2}). The computed HCI fugacity ({approx} 10{sup -4} bars) generated by boiling under these conditions is not sufficient to lower the pH of the condensate (cooled to 80 and 25 C) down to observed values unless the H{sub 2}O mass fraction in gas is reduced below {approx}10%. This is because the condensate becomes progressively diluted by H{sub 2}O gas condensation. However, when the system is modeled to remove water vapor, the computed pH of instantaneous condensates decreases to {approx}1.7, consistent with the experiment (Figure 1). The results also show that the HCl fugacity increases, and calcite, gypsum, sylvite, halite, MgCl{sub 2}4H{sub 2}O and CaCl{sub 2} precipitate sequentially with increasing concentration factors.

G. Zhahg; N. Spycher; E. Sonnenthal; C. Steefel

2005-01-25T23:59:59.000Z

132

Model Development and Analysis of the Fate and Transport of Water in a Salt  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Model Development and Analysis of the Fate and Transport of Water Model Development and Analysis of the Fate and Transport of Water in a Salt Based Repository Model Development and Analysis of the Fate and Transport of Water in a Salt Based Repository The study summarizes the initial work on numerical modeling, simulations, and experimental results related to nuclear waste storage in a salt repository. The study reflects the project's preliminary effort at simulating the fluid flow and heat transport processes, before treating the fully coupled thermal-mechanical-hydrologic-chemical (TMHC) coupled processes in the future. Model Development and Analysis of the Fate and Transport of Water in a Salt Based Repository More Documents & Publications Coupled Model for Heat and Water Transport in a High Level Waste Repository

133

Large-Scale Evacuation Network Model for Transporting Evacuees with Multiple Priorities  

E-Print Network (OSTI)

mathematical optimization model called Triage-Assignment-Transportation (TAT) model is suggested in order to decide on the tactical routing assignment of several classes of evacuation vehicles between staging areas and shelters in the nearby area. The model...

Na, Hyeong Suk

2014-05-01T23:59:59.000Z

134

Geophysical monitoring and reactive transport modeling of ureolytically-driven calcium carbonate precipitation  

SciTech Connect

Ureolytically-driven calcium carbonate precipitation is the basis for a promising in-situ remediation method for sequestration of divalent radionuclide and trace metal ions. It has also been proposed for use in geotechnical engineering for soil strengthening applications. Monitoring the occurrence, spatial distribution, and temporal evolution of calcium carbonate precipitation in the subsurface is critical for evaluating the performance of this technology and for developing the predictive models needed for engineering application. In this study, we conducted laboratory column experiments using natural sediment and groundwater to evaluate the utility of geophysical (complex resistivity and seismic) sensing methods, dynamic synchrotron x-ray computed tomography (micro-CT), and reactive transport modeling for tracking ureolytically-driven calcium carbonate precipitation processes under site relevant conditions. Reactive transport modeling with TOUGHREACT successfully simulated the changes of the major chemical components during urea hydrolysis. Even at the relatively low level of urea hydrolysis observed in the experiments, the simulations predicted an enhanced calcium carbonate precipitation rate that was 3-4 times greater than the baseline level. Reactive transport modeling results, geophysical monitoring data and micro-CT imaging correlated well with reaction processes validated by geochemical data. In particular, increases in ionic strength of the pore fluid during urea hydrolysis predicted by geochemical modeling were successfully captured by electrical conductivity measurements and confirmed by geochemical data. The low level of urea hydrolysis and calcium carbonate precipitation suggested by the model and geochemical data was corroborated by minor changes in seismic P-wave velocity measurements and micro-CT imaging; the latter provided direct evidence of sparsely distributed calcium carbonate precipitation. Ion exchange processes promoted through NH{sub 4}{sup +} production during urea hydrolysis were incorporated in the model and captured critical changes in the major metal species. The electrical phase increases were potentially due to ion exchange processes that modified charge structure at mineral/water interfaces. Our study revealed the potential of geophysical monitoring for geochemical changes during urea hydrolysis and the advantages of combining multiple approaches to understand complex biogeochemical processes in the subsurface.

Wu, Y.; Ajo-Franklin, J.B.; Spycher, N.; Hubbard, S.S.; Zhang, G.; Williams, K.H.; Taylor, J.; Fujita, Y.; Smith, R.

2011-07-15T23:59:59.000Z

135

Harmony Search Algorithm for Transport Energy Demand Modeling  

Science Journals Connector (OSTI)

The transport sector is one of the major consumers of energy production throughout the world. Thus, the estimation of medium and long-term energy consumption based on socio-economic and transport related indic...

Halim Ceylan; Huseyin Ceylan

2009-01-01T23:59:59.000Z

136

A Radionuclide Transport Model for the Unsaturated Zone at Yucca Mountain Bruce A. Robinson  

E-Print Network (OSTI)

A Radionuclide Transport Model for the Unsaturated Zone at Yucca Mountain Bruce A. Robinson Zhiming model calculations for radionuclide transport in the unsaturated zone at Yucca Mountain. The model developed by the Yucca Mountain Project based on calibrations to site data. The particle-tracking technique

Lu, Zhiming

137

To appear in the SIGGRAPH conference proceedings A Practical Model for Subsurface Light Transport  

E-Print Network (OSTI)

be simulated accurately but slowly by solving the full radiative transfer equation [1]. Only a few papersTo appear in the SIGGRAPH conference proceedings A Practical Model for Subsurface Light Transport introduces a simple model for subsurface light transport in translucent materials. The model enables

Stanford University

138

Modeling the Prospects for Hydrogen Powered Transportation Through 2100  

E-Print Network (OSTI)

Hydrogen fueled transportation has been proposed as a low carbon alternative to the current gasoline-powered

Sandoval, Reynaldo.

139

Mechanism of the Water Gas Shift Reaction on Pt: First Principles, Experiments, and Microkinetic Modeling  

SciTech Connect

The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. We present a microkinetic model as well as experimental data for the low-temperature water gas shift (WGS) reaction catalyzed by Pt at temperatures from 523 to 573 K and for various gas compositions at a pressure of 1 atm. Thermodynamic and kinetic parameters for the model are derived from periodic, self-consistent density functional theory (DFT-GGA) calculations on Pt(111). The destabilizing effect of high CO surface coverage on the binding energies of surface species is quantified through DFT calculations and accounted for in the microkinetic model. Deviations of specific fitted model parameters from DFT calculated parameters on Pt(111) point to the possible role of steps/defects in this reaction. Our model predicts reaction rates and reaction orders in good agreement with our experiments. The calculated and experimental apparent activation energies are 67.8 kJ/mol and 71.4 kJ/mol, respectively. The model shows that the most significant reaction channel proceeds via a carboxyl (COOH) intermediate. Formate (HCOO), which has been experimentally observed and thought to be the key WGS intermediate in the literature, is shown to act only as a spectator species.

Grabow, Lars C.; Gokhale, Amit A.; Evans, Steven T.; Dumesic, James A.; Mavrikakis, Manos

2008-03-27T23:59:59.000Z

140

Validation Analysis of the Shoal Groundwater Flow and Transport Model  

SciTech Connect

Environmental restoration at the Shoal underground nuclear test is following a process prescribed by a Federal Facility Agreement and Consent Order (FFACO) between the U.S. Department of Energy, the U.S. Department of Defense, and the State of Nevada. Characterization of the site included two stages of well drilling and testing in 1996 and 1999, and development and revision of numerical models of groundwater flow and radionuclide transport. Agreement on a contaminant boundary for the site and a corrective action plan was reached in 2006. Later that same year, three wells were installed for the purposes of model validation and site monitoring. The FFACO prescribes a five-year proof-of-concept period for demonstrating that the site groundwater model is capable of producing meaningful results with an acceptable level of uncertainty. The corrective action plan specifies a rigorous seven step validation process. The accepted groundwater model is evaluated using that process in light of the newly acquired data. The conceptual model of ground water flow for the Project Shoal Area considers groundwater flow through the fractured granite aquifer comprising the Sand Springs Range. Water enters the system by the infiltration of precipitation directly on the surface of the mountain range. Groundwater leaves the granite aquifer by flowing into alluvial deposits in the adjacent basins of Fourmile Flat and Fairview Valley. A groundwater divide is interpreted as coinciding with the western portion of the Sand Springs Range, west of the underground nuclear test, preventing flow from the test into Fourmile Flat. A very low conductivity shear zone east of the nuclear test roughly parallels the divide. The presence of these lateral boundaries, coupled with a regional discharge area to the northeast, is interpreted in the model as causing groundwater from the site to flow in a northeastward direction into Fairview Valley. Steady-state flow conditions are assumed given the absence of groundwater withdrawal activities in the area. The conceptual and numerical models were developed based upon regional hydrogeologic investigations conducted in the 1960s, site characterization investigations (including ten wells and various geophysical and geologic studies) at Shoal itself prior to and immediately after the test, and two site characterization campaigns in the 1990s for environmental restoration purposes (including eight wells and a year-long tracer test). The new wells are denoted MV-1, MV-2, and MV-3, and are located to the northnortheast of the nuclear test. The groundwater model was generally lacking data in the north-northeastern area; only HC-1 and the abandoned PM-2 wells existed in this area. The wells provide data on fracture orientation and frequency, water levels, hydraulic conductivity, and water chemistry for comparison with the groundwater model. A total of 12 real-number validation targets were available for the validation analysis, including five values of hydraulic head, three hydraulic conductivity measurements, three hydraulic gradient values, and one angle value for the lateral gradient in radians. In addition, the fracture dip and orientation data provide comparisons to the distributions used in the model and radiochemistry is available for comparison to model output. Goodness-of-fit analysis indicates that some of the model realizations correspond well with the newly acquired conductivity, head, and gradient data, while others do not. Other tests indicated that additional model realizations may be needed to test if the model input distributions need refinement to improve model performance. This approach (generating additional realizations) was not followed because it was realized that there was a temporal component to the data disconnect: the new head measurements are on the high side of the model distributions, but the heads at the original calibration locations themselves have also increased over time. This indicates that the steady-state assumption of the groundwater model is in error. To test the robustness of the model d

A. Hassan; J. Chapman

2008-11-01T23:59:59.000Z

Note: This page contains sample records for the topic "reaction transport model" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

A Reaction-Diffusion Model of Cancer Invasion  

Science Journals Connector (OSTI)

...A. G.J and Department of Physics IE. T. G.J. Temple University...behavior of the model but it does facilitate the derivation of...Lide, D. R., (ed.) CRC Handbook of Chemistry and Physics. Boca Raton, FL: CRC Press...

Robert A. Gatenby and Edward T. Gawlinski

1996-12-15T23:59:59.000Z

142

New city model to reduce demand for transportation  

Science Journals Connector (OSTI)

Managing demand for transportation can be a cost-effective alternative to increasing capacity. A demand management approach to transport services also has the potential to deliver better environmental outcomes, improved public health and stronger communities, and more prosperous and liveable cities The increased distance between places will have a direct impact on the demand of transportation. Public transport system (MRTS) is an answer to the growing traffic congestion. However, the question is; Is MRTS are the last resort? This paper will be an attempt to regularize the development scenario of the city and thus reducing the demand for transportation.

Sumant Sharma; Anoop Sharma; Ashwani Kumar

2011-01-01T23:59:59.000Z

143

Dynamic behavior of the monomermonomer surface reaction model with adsorbate interactions  

E-Print Network (OSTI)

Dynamic behavior of the monomer­monomer surface reaction model with adsorbate interactions model with an adsorbate interaction term is studied. An epidemic analysis of the poisoning times (tp between the concentration of molecules adsorbed on the surface and the rate of adsorp- tion

Voigt, Chris

144

Hydroxyl Ion Migration, Chemical Reactions, Water Transport and Other Effects As Optimizing Parameters In Cross-, Co- And Countercurrently Operated Membrane Cells For The Chlor/Alkali Electrolysis  

Science Journals Connector (OSTI)

A mathematical model describing a chloralkali-electrolysis in membrane cells including unusual flow pattern is presented. This paper discusses several influences like chemical reactions in the anolyte compartm...

K. H. Simmrock

1984-01-01T23:59:59.000Z

145

Direct Internal Reformation and Mass Transport in the Solid Oxide Fuel Cell Anode: A Pore-Scale Lattice Boltzmann Study with Detailed Reaction Kinetics  

SciTech Connect

The solid oxide fuel cell (SOFC) allows the conversion of chemical energy that is stored in a given fuel, including light hydrocarbons, to electrical power. Hydrocarbon fuels, such as methane, are logistically favourable and provide high energy densities. However, the use of these fuels often results in a decreased efficiency and life. An improved understanding of the reactive flow in the SOFC anode can help address these issues. In this study, the transport and heterogeneous internal reformation of a methane based fuel is addressed. The effect of the SOFC anode's complex structure on transport and reactions is shown to exhibit a complicated interplay between the local molar concentrations and the anode structure. Strong coupling between the phenomenological microstructures and local reformation reaction rates are recognised in this study, suggesting the extension to actual microstructures may provide new insights into the reformation processes.

Grew, Kyle N.; Joshi, Abhijit S.; Chiu, W. K. S.

2010-01-01T23:59:59.000Z

146

Chemical Accelerator Studies of Isotope Effects on Collision Dynamics of IonMolecule Reactions: Elaboration of a Model for Direct Reactions  

E-Print Network (OSTI)

there is a fairly wide distribution about the median values. Results confirm that this reaction is predominantly direct at all energies and provide no evidence for intermediate persistent complex formation. They are also consistent with a model for direct...

Hierl, Peter M.; Herman, Z.; Wolfgang, R.

1970-01-01T23:59:59.000Z

147

Lewis-Oppenheimer-Wouthuysen Model Applied to Neutrino Reactions  

Science Journals Connector (OSTI)

The cross sections for pion production by neutrinos and the charge-exchange scattering of neutrinos by nucleons are calculated. The weak-interaction Hamiltonian is taken as a product of nucleon and lepton currents. The Lewis-Oppenheimer-Wouthuysen model is used to compute the production matrix elements between nucleon-pion states given by the intermediate-coupling approximation. The results agree moderately well with the experiments using 2-BeV neutrinos.

Barbara Sakitt

1968-07-25T23:59:59.000Z

148

Model Development and Analysis of the Fate and Transport of Water in a Salt  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Development and Analysis of the Fate and Transport of Water Development and Analysis of the Fate and Transport of Water in a Salt Based Repository Model Development and Analysis of the Fate and Transport of Water in a Salt Based Repository The study summarizes the initial work on numerical modeling, simulations, and experimental results related to nuclear waste storage in a salt repository. The study reflects the project's preliminary effort at simulating the fluid flow and heat transport processes, before treating the fully coupled thermal-mechanical-hydrologic-chemical (TMHC) coupled processes in the future. Model Development and Analysis of the Fate and Transport of Water in a Salt Based Repository More Documents & Publications Coupled Model for Heat and Water Transport in a High Level Waste Repository in Salt

149

Long-Range Atmospheric Transport of Polycyclic Aromatic Hydrocarbons: A Global 3-D Model Analysis Including Evaluation of Arctic Sources  

E-Print Network (OSTI)

We use the global 3-D chemical transport model GEOS-Chem to simulate long-range atmospheric transport of polycyclic aromatic hydrocarbons (PAHs). To evaluate the models ability to simulate PAHs with different volatilities, ...

Friedman, Carey

150

Transportation Sector Model of the National Energy Modeling System. Volume 2 -- Appendices: Part 2  

SciTech Connect

The attachments contained within this appendix provide additional details about the model development and estimation process which do not easily lend themselves to incorporation in the main body of the model documentation report. The information provided in these attachments is not integral to the understanding of the model`s operation, but provides the reader with opportunity to gain a deeper understanding of some of the model`s underlying assumptions. There will be a slight degree of replication of materials found elsewhere in the documentation, made unavoidable by the dictates of internal consistency. Each attachment is associated with a specific component of the transportation model; the presentation follows the same sequence of modules employed in Volume 1. The following attachments are contained in Appendix F: Fuel Economy Model (FEM)--provides a discussion of the FEM vehicle demand and performance by size class models; Alternative Fuel Vehicle (AFV) Model--describes data input sources and extrapolation methodologies; Light-Duty Vehicle (LDV) Stock Model--discusses the fuel economy gap estimation methodology; Light Duty Vehicle Fleet Model--presents the data development for business, utility, and government fleet vehicles; Light Commercial Truck Model--describes the stratification methodology and data sources employed in estimating the stock and performance of LCT`s; Air Travel Demand Model--presents the derivation of the demographic index, used to modify estimates of personal travel demand; and Airborne Emissions Model--describes the derivation of emissions factors used to associate transportation measures to levels of airborne emissions of several pollutants.

NONE

1998-01-01T23:59:59.000Z

151

Using Reactive Transport Modeling to Evaluate the Source Term at Yucca Mountain  

SciTech Connect

The conventional approach of source-term evaluation for performance assessment of nuclear waste repositories uses speciation-solubility modeling tools and assumes pure phases of radioelements control their solubility. This assumption may not reflect reality, as most radioelements (except for U) may not form their own pure phases. As a result, solubility limits predicted using the conventional approach are several orders of magnitude higher then the concentrations of radioelements measured in spent fuel dissolution experiments. This paper presents the author's attempt of using a non-conventional approach to evaluate source term of radionuclide release for Yucca Mountain. Based on the general reactive-transport code AREST-CT, a model for spent fuel dissolution and secondary phase precipitation has been constructed. The model accounts for both equilibrium and kinetic reactions. Its predictions have been compared against laboratory experiments and natural analogues. It is found that without calibrations, the simulated results match laboratory and field observations very well in many aspects. More important is the fact that no contradictions between them have been found. This provides confidence in the predictive power of the model. Based on the concept of Np incorporated into uranyl minerals, the model not only predicts a lower Np source-term than that given by conventional Np solubility models, but also produces results which are consistent with laboratory measurements and observations. Moreover, two hypotheses, whether Np enters tertiary uranyl minerals or not, have been tested by comparing model predictions against laboratory observations, the results favor the former. It is concluded that this non-conventional approach of source term evaluation not only eliminates over-conservatism in conventional solubility approach to some extent, but also gives a realistic representation of the system of interest, which is a prerequisite for truly understanding the long-term behavior of the proposed repository. Therefore, it is a very promising alternative approach for source-term evaluation.

Y. Chen

2001-12-19T23:59:59.000Z

152

The National Energy Modeling System: An Overview 1998 - Transportation  

Gasoline and Diesel Fuel Update (EIA)

TRANSPORTATION DEMAND MODULE TRANSPORTATION DEMAND MODULE blueball.gif (205 bytes) Fuel Economy Submodule blueball.gif (205 bytes) Regional Sales Submodule blueball.gif (205 bytes) Alternative-Fuel Vehicle Submodule blueball.gif (205 bytes) Light-Duty Vehicle Stock Submodule blueball.gif (205 bytes) Vehicle-Miles Traveled (VMT) Submodule blueball.gif (205 bytes) Light-Duty Vehicle Commercial Fleet Submodule blueball.gif (205 bytes) Commercial Light Truck Submodule blueball.gif (205 bytes) Air Travel Demand Submodule blueball.gif (205 bytes) Aircraft Fleet Efficiency Submodule blueball.gif (205 bytes) Freight Transport Submodule blueball.gif (205 bytes) Miscellaneous Energy Use Submodule The transportation demand module (TRAN) forecasts the consumption of transportation sector fuels by transportation mode, including the use of

153

Coulomb reacceleration as a clock for nuclear reactions: A two-dimensional model  

Science Journals Connector (OSTI)

Reacceleration effects in the Coulomb breakup of nuclei are modeled with the two-dimensional time-dependent Schrdinger equation, extending a previous one-dimensional study. The present model better describes the individual contributions of longitudinal and transverse forces to the breakup and reacceleration. Reacceleration effects are found to preserve a strong memory of the pre-breakup phase of the reaction, as was concluded with the one-dimensional model.

C. A. Bertulani and G. F. Bertsch

1994-05-01T23:59:59.000Z

154

A unified model of electroporation and molecular transport  

E-Print Network (OSTI)

Biological membranes form transient, conductive pores in response to elevated transmembrane voltage, a phenomenon termed electroporation. These pores facilitate electrical and molecular transport across cell membranes that ...

Smith, Kyle Christopher

2011-01-01T23:59:59.000Z

155

Tropospheric Nitric Acid Columns from IASI Interpreted with a Chemical Transport Model Matthew Cooper1  

E-Print Network (OSTI)

1 Tropospheric Nitric Acid Columns from IASI Interpreted with a Chemical Transport Model Matthew from the IASI satellite instrument with a global chemical transport model (GEOS-Chem). GEOS the Infrared Atmospheric Sounding Interferometer (IASI) instrument on the MetOp satellite platform. IASI

Martin, Randall

156

A non-isothermal PEM fuel cell model including two water transport mechanisms in the  

E-Print Network (OSTI)

A non-isothermal PEM fuel cell model including two water transport mechanisms in the membrane K Freiburg Germany A dynamic two-phase flow model for proton exchange mem- brane (PEM) fuel cells and the species concentrations. In order to describe the charge transport in the fuel cell the Poisson equations

Münster, Westfälische Wilhelms-Universität

157

A Mixed Finite-Element Discretization of the Energy-Transport Model for Semiconductors  

E-Print Network (OSTI)

A Mixed Finite-Element Discretization of the Energy-Transport Model for Semiconductors Stefan Holst #12;tting mixed #12;nite-element method is used to discretize the stationary energy. Energy-transport models describe the ow of electrons through a semi- conductor device, in uenced by di

Pietra, Paola

158

Golden rule kinetics of transfer reactions in condensed phase: The microscopic model of electron transfer reactions in disordered solid matrices  

SciTech Connect

The algorithm for a theoretical calculation of transfer reaction rates for light quantum particles (i.e., the electron and H-atom transfers) in non-polar solid matrices is formulated and justified. The mechanism postulated involves a local mode (an either intra- or inter-molecular one) serving as a mediator which accomplishes the energy exchange between the reacting high-frequency quantum mode and the phonon modes belonging to the environment. This approach uses as a background the Fermi golden rule beyond the usually applied spin-boson approximation. The dynamical treatment rests on the one-dimensional version of the standard quantum relaxation equation for the reduced density matrix, which describes the frequency fluctuation spectrum for the local mode under consideration. The temperature dependence of a reaction rate is controlled by the dimensionless parameter ?{sub 0}=??{sub 0}/k{sub B}T where ?{sub 0} is the frequency of the local mode and T is the temperature. The realization of the computational scheme is different for the high/intermediate (?{sub 0} < 1 ? 3) and for low (?{sub 0}? 1) temperature ranges. For the first (quasi-classical) kinetic regime, the Redfield approximation to the solution of the relaxation equation proved to be sufficient and efficient in practical applications. The study of the essentially quantum-mechanical low-temperature kinetic regime in its asymptotic limit requires the implementation of the exact relaxation equation. The coherent mechanism providing a non-vanishing reaction rate has been revealed when T? 0. An accurate computational methodology for the cross-over kinetic regime needs a further elaboration. The original model of the hopping mechanism for electronic conduction in photosensitive organic materials is considered, based on the above techniques. The electron transfer (ET) in active centers of such systems proceeds via local intra- and intermolecular modes. The active modes, as a rule, operate beyond the kinetic regimes, which are usually postulated in the existing theories of the ET. Our alternative dynamic ET model for local modes immersed in the continuum harmonic medium is formulated for both classical and quantum regimes, and accounts explicitly for the mode/medium interaction. The kinetics of the energy exchange between the local ET subsystem and the surrounding environment essentially determine the total ET rate. The efficient computer code for rate computations is elaborated on. The computations are available for a wide range of system parameters, such as the temperature, external field, local mode frequency, and characteristics of mode/medium interaction. The relation of the present approach to the Marcus ET theory and to the quantum-statistical reaction rate theory [V. G. Levich and R. R. Dogonadze, Dokl. Akad. Nauk SSSR, Ser. Fiz. Khim. 124, 213 (1959); J. Ulstrup, Charge Transfer in Condensed Media (Springer, Berlin, 1979); M. Bixon and J. Jortner, Adv. Chem. Phys. 106, 35 (1999)] underlying it is discussed and illustrated by the results of computations for practically important target systems.

Basilevsky, M. V.; Mitina, E. A. [Photochemistry Center, Russian Academy of Sciences, 7a, Novatorov ul., Moscow (Russian Federation)] [Photochemistry Center, Russian Academy of Sciences, 7a, Novatorov ul., Moscow (Russian Federation); Odinokov, A. V. [Photochemistry Center, Russian Academy of Sciences, 7a, Novatorov ul., Moscow (Russian Federation) [Photochemistry Center, Russian Academy of Sciences, 7a, Novatorov ul., Moscow (Russian Federation); National Research Nuclear University MEPhI, 31, Kashirskoye shosse, Moscow (Russian Federation); Titov, S. V. [Karpov Institute of Physical Chemistry, 3-1/12, Building 6, Obuha pereulok, Moscow (Russian Federation)] [Karpov Institute of Physical Chemistry, 3-1/12, Building 6, Obuha pereulok, Moscow (Russian Federation)

2013-12-21T23:59:59.000Z

159

A Diagnostic Analysis of a Long-Term Regional Air Pollutant Transport Model  

Science Journals Connector (OSTI)

Predicted concentrations from the Regional Air Pollutant Transport (RAPT) model are compared with the corresponding observed values of sulfate, and the results used to define strengths and weaknesses in the model formulation.

Daniel J. McNaughton; Carl M. Berkowitz; Robert C. Williams

1981-07-01T23:59:59.000Z

160

MODELING FLOW AND TRANSPORT PATHWAYS TO THE POTENTIAL REPOSITORY HORIZON AT YUCCA MOUNTAIN  

SciTech Connect

The isotopic ratios of {sup 36}Cl/Cl are used in conjunction with geologic interpretation and numerical modeling to evaluate flow and transport pathways, processes, and model parameters in the unsaturated zone at Yucca Mountain. By synthesizing geochemical and geologic data, the numerical model results provide insight into the validity of alternative hydrologic parameter sets, flow and transport processes in and away from fault zones, and the applicability of {sup 36}Cl/Cl. ratios for evaluating alternative conceptual models.

A.V. WOLFSBERG, G.J.C. ROEMER, J.T. FABRYKA-MARTIN, B.A. ROBINSON

1998-03-04T23:59:59.000Z

Note: This page contains sample records for the topic "reaction transport model" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Transportation  

NLE Websites -- All DOE Office Websites (Extended Search)

Due to limited parking, all visitors are strongly encouraged to: Due to limited parking, all visitors are strongly encouraged to: 1) car-pool, 2) take the Lab's special conference shuttle service, or 3) take the regular off-site shuttle. If you choose to use the regular off-site shuttle bus, you will need an authorized bus pass, which can be obtained by contacting Eric Essman in advance. Transportation & Visitor Information Location and Directions to the Lab: Lawrence Berkeley National Laboratory is located in Berkeley, on the hillside directly above the campus of University of California at Berkeley. The address is One Cyclotron Road, Berkeley, California 94720. For comprehensive directions to the lab, please refer to: http://www.lbl.gov/Workplace/Transportation.html Maps and Parking Information: On Thursday and Friday, a limited number (15) of barricaded reserved parking spaces will be available for NON-LBNL Staff SNAP Collaboration Meeting participants in parking lot K1, in front of building 54 (cafeteria). On Saturday, plenty of parking spaces will be available everywhere, as it is a non-work day.

162

Kinetic Model for Parallel Reactions of CaSO4 with CO in Chemical-Looping Combustion  

Science Journals Connector (OSTI)

Kinetic Model for Parallel Reactions of CaSO4 with CO in Chemical-Looping Combustion ... Industrial & Engineering Chemistry Research2013 52 (11), 4059-4071 ...

Min Zheng; Laihong Shen; Xiaoqiong Feng; Jun Xiao

2011-03-23T23:59:59.000Z

163

Dynamical Coupled-Channels Model Analysis of ?-N Scattering and Electromagnetic Pion Production Reactions  

E-Print Network (OSTI)

The ability of the coupled-channels model (MSL) developed in recently in Ref. \\cite{msl} to account simultaneously for the $\\pi N$ scattering data and the $\\pi$ photoproduction reactions on the nucleon is presented. An accurate description of $\\pi N$ scattering has been obtained. A preliminary description of $\\pi$ photoproduction is also discussed.

B. Julia-Diaz

2007-12-01T23:59:59.000Z

164

Reaction-Diffusion Model for Combustion with Fuel Consumption: I. Dirichlet Boundary Conditions  

Science Journals Connector (OSTI)

......9JT, UK Department of Chemistry, University of Leeds...Reaction-Diffusion Model for Combustion with Fuel Consumption...SCOTT Department of Chemistry, University of Leeds...runaway in stockpiles of coal, wool, cellulose...smouldering or fully fledged combustion and their attendant......

G. ZHANG; J. H. MERKIN; S. K. SCOTT

1991-01-01T23:59:59.000Z

165

Analytical modeling of contaminant transport and horizontal well hydraulics  

E-Print Network (OSTI)

transport from one-, two-, and three-dimensional finite sources in a finite-thickness aquifer using Green's function method. A library of unpublished analytical solutions with different finite source geometry is provided. A graphically integrated software...

Park, Eungyu

2004-09-30T23:59:59.000Z

166

Model Annex for Preparedness and Response to Radiological Transportation Incidents  

Energy.gov (U.S. Department of Energy (DOE))

This part should contain a general statement of the intent of this Annex. To provide for the planning, preparedness and coordination of emergency service efforts to respond to a transportation...

167

Combined Modeling of Acceleration, Transport, and Hydrodynamic Response in Solar Flares. I. The Numerical Model  

Science Journals Connector (OSTI)

Acceleration and transport of high-energy particles and fluid dynamics of atmospheric plasma are interrelated aspects of solar flares, but for convenience and simplicity they were artificially separated in the past. We present here self-consistently combined Fokker-Planck modeling of particles and hydrodynamic simulation of flare plasma. Energetic electrons are modeled with the Stanford unified code of acceleration, transport, and radiation, while plasma is modeled with the Naval Research Laboratory flux tube code. We calculated the collisional heating rate directly from the particle transport code, which is more accurate than those in previous studies based on approximate analytical solutions. We repeated the simulation of Mariska et al. with an injection of power law, downward-beamed electrons using the new heating rate. For this case, a ~10% difference was found from their old result. We also used a more realistic spectrum of injected electrons provided by the stochastic acceleration model, which has a smooth transition from a quasi-thermal background at low energies to a nonthermal tail at high energies. The inclusion of low-energy electrons results in relatively more heating in the corona (versus chromosphere) and thus a larger downward heat conduction flux. The interplay of electron heating, conduction, and radiative loss leads to stronger chromospheric evaporation than obtained in previous studies, which had a deficit in low-energy electrons due to an arbitrarily assumed low-energy cutoff. The energy and spatial distributions of energetic electrons and bremsstrahlung photons bear signatures of the changing density distribution caused by chromospheric evaporation. In particular, the density jump at the evaporation front gives rise to enhanced emission, which, in principle, can be imaged by X-ray telescopes. This model can be applied to investigate a variety of high-energy processes in solar, space, and astrophysical plasmas.

Wei Liu; Vah Petrosian; John T. Mariska

2009-01-01T23:59:59.000Z

168

COMBINED MODELING OF ACCELERATION, TRANSPORT, AND HYDRODYNAMIC RESPONSE IN SOLAR FLARES. I. THE NUMERICAL MODEL  

SciTech Connect

Acceleration and transport of high-energy particles and fluid dynamics of atmospheric plasma are interrelated aspects of solar flares, but for convenience and simplicity they were artificially separated in the past. We present here self-consistently combined Fokker-Planck modeling of particles and hydrodynamic simulation of flare plasma. Energetic electrons are modeled with the Stanford unified code of acceleration, transport, and radiation, while plasma is modeled with the Naval Research Laboratory flux tube code. We calculated the collisional heating rate directly from the particle transport code, which is more accurate than those in previous studies based on approximate analytical solutions. We repeated the simulation of Mariska et al. with an injection of power law, downward-beamed electrons using the new heating rate. For this case, a {approx}10% difference was found from their old result. We also used a more realistic spectrum of injected electrons provided by the stochastic acceleration model, which has a smooth transition from a quasi-thermal background at low energies to a nonthermal tail at high energies. The inclusion of low-energy electrons results in relatively more heating in the corona (versus chromosphere) and thus a larger downward heat conduction flux. The interplay of electron heating, conduction, and radiative loss leads to stronger chromospheric evaporation than obtained in previous studies, which had a deficit in low-energy electrons due to an arbitrarily assumed low-energy cutoff. The energy and spatial distributions of energetic electrons and bremsstrahlung photons bear signatures of the changing density distribution caused by chromospheric evaporation. In particular, the density jump at the evaporation front gives rise to enhanced emission, which, in principle, can be imaged by X-ray telescopes. This model can be applied to investigate a variety of high-energy processes in solar, space, and astrophysical plasmas.

Liu Wei [Stanford-Lockheed Institute for Space Research, 466 Via Ortega, Cypress Hall, Stanford, CA 94305-4085 (United States); Petrosian, Vahe [Department of Physics, Stanford University, Stanford, CA 94305-4060 (United States); Mariska, John T. [Naval Research Laboratory, Code 7673, Washington, DC 20375-5000 (United States)

2009-09-10T23:59:59.000Z

169

A turbulent transport network model in MULTIFLUX coupled with TOUGH2  

SciTech Connect

A new numerical method is described for the fully iterated, conjugate solution of two discrete submodels, involving (a) a transport network model for heat, moisture, and airflows in a high-permeability, air-filled cavity; and (b) a variably saturated fractured porous medium. The transport network submodel is an integrated-parameter, computational fluid dynamics solver, describing the thermal-hydrologic transport processes in the flow channel system of the cavity with laminar or turbulent flow and convective heat and mass transport, using MULTIFLUX. The porous medium submodel, using TOUGH2, is a solver for the heat and mass transport in the fractured rock mass. The new model solution extends the application fields of TOUGH2 by integrating it with turbulent flow and transport in a discrete flow network system. We present demonstrational results for a nuclear waste repository application at Yucca Mountain with the most realistic model assumptions and input parameters including the geometrical layout of the nuclear spent fuel and waste with variable heat load for the individual containers. The MULTIFLUX and TOUGH2 model elements are fully iterated, applying a programmed reprocessing of the Numerical Transport Code Functionalization model-element in an automated Outside Balance Iteration loop. The natural, convective airflow field and the heat and mass transport in a representative emplacement drift during postclosure are explicitly solved in the new model. The results demonstrate that the direction and magnitude of the air circulation patterns and all transport modes are strongly affected by the heat and moisture transport processes in the surrounding rock, justifying the need for a coupled, fully iterated model solution such as the one presented in the paper.

Danko, G.; Bahrami, D.; Birkholzer, J.T.

2011-02-15T23:59:59.000Z

170

Acid-base chemical reaction model for nucleation rates in the polluted  

NLE Websites -- All DOE Office Websites (Extended Search)

Acid-base chemical reaction model for nucleation rates in the polluted Acid-base chemical reaction model for nucleation rates in the polluted atmospheric boundary layer Title Acid-base chemical reaction model for nucleation rates in the polluted atmospheric boundary layer Publication Type Conference Paper Year of Publication 2013 Authors Chen, Modi, Mari Titcombe, Jingkun Jiang, Coty Jen, Chongai Kuang, Marc L. Fischer, Fred L. Eisele, Ilja J. Siepmann, David R. Hanson, Jun Zhao, and Peter H. McMurry Conference Name Nucleation and Atmospheric Aerosols: 19th International Conference Publisher AIP Publishing LLC Conference Location Fort Collins, CO Abstract Measurements of aerosol number distributions down to one molecule have provided information that we've used to develop a new approach for modeling atmospheric nucleation rates. Measurements were carried out with the Cluster Chemical Ionization Mass Spectrometer (Cluster CIMS), the scanning mobility spectrometer using a diethylene glycol condensation particle counter as detector (DEG SMPS), and an ambient pressure proton transfer mass spectrometer for ammonia and amines (AmPMS). The model explains nucleation as a result of cluster evolution due to a sequence of acid-base reactions. We conclude that the smallest stable cluster contains four sulfuric acid molecules. The model leads to a simple analytic expression for nucleation rates that is reasonably consistent (i.e., ± 10x) with atmospheric observations. The model predicts that nucleation rates are equal to a prefactor, P<1, times the sulfuric acid vapor collision rate, (i.e., J=P⋅0.5⋅k11 ∗[H2SO4]2).

171

Coupling Chemical Transport Model Source Attributions with Positive Matrix Factorization: Application to Two IMPROVE Sites Impacted by Wildfires  

Science Journals Connector (OSTI)

Coupling Chemical Transport Model Source Attributions with Positive Matrix Factorization: Application to Two IMPROVE Sites Impacted by Wildfires ... Cooperative

Timothy M. Sturtz; Bret A. Schichtel; Timothy V. Larson

2014-09-02T23:59:59.000Z

172

A residence-time-based transport approach for the groundwater pathway in performance assessment models  

Science Journals Connector (OSTI)

This paper presents the theoretical development and numerical implementation of a new modeling approach for representing the groundwater pathway in risk assessment or performance assessment model of a contaminant transport system. The model developed ... Keywords: Groundwater pathway, Mixing model, Performance assessment, Residence time distribution

Bruce A. Robinson; Shaoping Chu

2013-03-01T23:59:59.000Z

173

Multicomponent reactive transport modeling at the Ratones uranium mine, Cceres (Spain)  

E-Print Network (OSTI)

Multicomponent reactive transport modeling at the Ratones uranium mine, Cáceres (Spain) Modelación management. The Ratones uranium mine was abandoned and flooded in 1974. Due to its reducing underground water, uranium, reactive transport, granite hydrochemistry, Ratones mine. Resumen La inundación de minas

Politècnica de Catalunya, Universitat

174

Parallelization of a relaxation scheme modelling the bedload transport of sediments in shallow  

E-Print Network (OSTI)

Parallelization of a relaxation scheme modelling the bedload transport of sediments in shallow the cohesive strength of the soil particles. Once detached, the sediments can be transported downstream as non-cohesive sediment before its deposition. BANG Project, INRIA-Paris-Rocquencourt & LAGA, Universiy Paris 13 Nord

Boyer, Edmond

175

* All figures are in color on the Coastal Sediments Proceedings DVD. NONUNIFORM SEDIMENT TRANSPORT MODELING AT  

E-Print Network (OSTI)

1783 * All figures are in color on the Coastal Sediments Proceedings DVD. NONUNIFORM SEDIMENT@ncche.olemiss.edu. Abstract: A depth-averaged two-dimensionalnonuniform sediment transport model is applied to the beaches. The sediment transport, bed change and sorting equations are solved simultaneously and implicitly at the same

US Army Corps of Engineers

176

ANALYSIS OF MODELS FOR QUANTUM TRANSPORT OF ELECTRONS IN GRAPHENE LAYERS  

E-Print Network (OSTI)

ANALYSIS OF MODELS FOR QUANTUM TRANSPORT OF ELECTRONS IN GRAPHENE LAYERS RAYMOND EL HAJJ transport of electrons in a graphene layer. We treat two situations. First, when the particles can move by a selfconsistent po- tential, which is the trace in the plane of the graphene of the 3D Poisson potential

Méhats, Florian

177

Standing Waves in a Two-Dimensional Reaction-Diffusion Model with the Short-Wave Instability  

E-Print Network (OSTI)

Standing Waves in a Two-Dimensional Reaction-Diffusion Model with the Short-Wave Instability Milos 25, 1998; In Final Form: October 19, 1998 Various patterns of standing waves are found beyond the onset of the short-wave instability in a model reaction- diffusion system. These include plain

Epstein, Irving R.

178

Modeling Studies on the Transport of Benzene and H2S in CO2-Water Systems  

E-Print Network (OSTI)

interest in subcritical (hot/liquid) water from 298 K to 473subcritical region. Modeling Studies on the Transport of Benzene and H 2 S in CO 2 -Water

Zheng, L.

2011-01-01T23:59:59.000Z

179

E-Print Network 3.0 - agent transport modeling Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

results for: agent transport modeling Page: << < 1 2 3 4 5 > >> 1 Lecture Notes in Computer Science 1 Internet Agents for Effective Collaboration Summary: we present WAPM, a Web...

180

Observations and modeling of wave-acceleration-induced sediment transport in the surfzone  

E-Print Network (OSTI)

Onshore sediment transport and sandbar migration are important to the morphological evolution of beaches, but are not understood well. Here, a new model that accounts for accelerations of wave-orbital velocities predicts ...

Hoefel, Fernanda Gemael, 1973-

2004-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "reaction transport model" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Comparisons of Transport and Dispersion Model Predictions of the URBAN 2000 Field Experiment  

Science Journals Connector (OSTI)

The tracer releases of the URBAN 2000 urban tracer and meteorological field experiment conducted in Salt Lake City, Utah, in October 2000 provided a wealth of data for comparison with the predictions of transport and dispersion models. ...

Steve Warner; Nathan Platt; James F. Heagy

2004-06-01T23:59:59.000Z

182

Oceanic transports of heat and salt from a global model and data  

E-Print Network (OSTI)

A state estimate produced by ECCO-GODAE from a global one-degree model and data spanning the years 1992-2005 is analyzed in terms of transports of volume, temperature, and freshwater. The estimate is assessed to be ...

Olson, Elise

2006-01-01T23:59:59.000Z

183

Improving parameterization of scalar transport through vegetation in a coupled ecosystem-atmosphere model  

E-Print Network (OSTI)

Several regional-scale ecosystem models currently parameterize subcanopy scalar transport using a rough-wall boundary eddy diffusivity formulation. This formulation predicts unreasonably high soil evaporation beneath tall, ...

Link, Percy Anne

2008-01-01T23:59:59.000Z

184

Technology detail in a multi-sector CGE model : transport under climate policy  

E-Print Network (OSTI)

A set of three analytical models is used to study the imbedding of specific transport technologies within a multi-sector, multi-region evaluation of constraints on greenhouse emissions. Key parameters of a computable general ...

Schafer, Andreas.

185

Mathematical Geology, Vol. 33, No. 1, 2001 Modeling Uranium Transport in Koongarra,  

E-Print Network (OSTI)

Mathematical Geology, Vol. 33, No. 1, 2001 Modeling Uranium Transport in Koongarra, Australia waste disposal safety assessment studies. The Koongarra uranium deposit in the Alligator Rivers region weathering over several million years, during which many climatological, hydrological, and geological changes

Hassanizadeh, S. Majid

186

Computers & Geosciences 29 (2003) 351359 A case against Kd-based transport models: natural attenuation  

E-Print Network (OSTI)

attenuation at a mill tailings site Chen Zhu* Department of Geology and Planetary Science, University)-based transport model. The study site is a contaminated groundwater aquifer underneath a uranium mill tailings

Polly, David

187

The Fluid Interface Reactions Structures and Transport (FIRST) EFRC (A "Life at the Frontiers of Energy Research" contest entry from the 2011 Energy Frontier Research Centers (EFRCs) Summit and Forum)  

ScienceCinema (OSTI)

'The Fluid Interface Reactions Structures and Transport (FIRST) EFRC' was submitted by FIRST to the 'Life at the Frontiers of Energy Research' video contest at the 2011 Science for Our Nation's Energy Future: Energy Frontier Research Centers (EFRCs) Summit and Forum. Twenty-six EFRCs created short videos to highlight their mission and their work. FIRST, an EFRC directed by David J. Wesolowski at the Oak Ridge National Laboratory is a partnership of scientists from nine institutions: Oak Ridge National Laboratory (lead), Argonne National Laboratory, Drexel University, Georgia State University, Northwestern University, Pennsylvania State University, Suffolk University, Vanderbilt University, and University of Virginia. The Office of Basic Energy Sciences in the U.S. Department of Energy's Office of Science established the 46 Energy Frontier Research Centers (EFRCs) in 2009. These collaboratively-organized centers conduct fundamental research focused on 'grand challenges' and use-inspired 'basic research needs' recently identified in major strategic planning efforts by the scientific community. The overall purpose is to accelerate scientific progress toward meeting the nation's critical energy challenges. The mission of Fluid Interface Reactions, Structures and Transport Center is 'to develop quantitative and predictive models of the unique nanoscale environment at fluid-solid interfaces that will enable transformational advances in electrical energy storage and heterogeneous catalysis for solar fuels.' Research topics are: catalysis (biomass, CO{sub 2}, water), electrocatalysis, photocatalysis, photoelectrocatalysis, solar fuels, solar electrodes, electrical energy storage, batteries, capacitors, battery electrodes, electrolytes, extreme environment, CO{sub 2} (convert), greenhouse gas, microelectromechanical systems (MEMS), interfacial characterization, matter by design, novel materials synthesis, and charge transport.

Wesolowski, David J. (Director, FIRST - Fluid Interface Reactions, Structures, and Transport Center); FIRST Staff

2011-11-02T23:59:59.000Z

188

Cathode porous transport irreversibility model for PEM fuel cell design  

Science Journals Connector (OSTI)

The influence is studied of slip-irreversibility at the interface between the gas diffusion layer, also referred to here as the porous transport layer, and the catalyst layer of a proton exchange membrane fuel cell (PEMFC). A two-dimensional cathode ... Keywords: catalyst layer, exergy, gas diffusion layer, slip flow irreversibility

E. O. B. Ogedengbe; M. A. Rosen

2009-02-01T23:59:59.000Z

189

Comparisons Between Different Forward Models For Light Transport In Tissues  

E-Print Network (OSTI)

The radiative transfer equation to describe the laser radiation transport in scattering, absorbing and emitting the radiative heat transfer equation, which can be applied to almost all the electromagnetic radiation. The diffusion approximation method is controlled by a differential equation, which is derived from radiative

Guo, Zhixiong "James"

190

Sodium Transport in a Mouse Model of Colonic Carcinogenesis  

Science Journals Connector (OSTI)

...transport changes in the colonie mucosa of car cinogen-treated CFi mice after 4 weeks...9 1.0Electric potential in mV. ' Conductance in mS...ratios in human cancer cells as revealed by energy dispersive X-ray microanalysis. J...

Richard J. Davies; Wibo F. Weidema; Geoffrey I. Sandle; Lawrence Palmer; Eleanor E. Deschner; and Jerome J. DeCosse

1987-09-01T23:59:59.000Z

191

Modeling requirements for full-scope reactor simulators of fission-product transport during severe accidents  

SciTech Connect

This paper describes in the needs and requirements to properly and efficiently model fission product transport on full scope reactor simulators. Current LWR simulators can be easily adapted to model severe accident phenomena and the transport of radionuclides. Once adapted these simulators can be used as a training tool during operator training exercises for training on severe accident guidelines, for training on containment venting procedures, or as training tool during site wide emergency training exercises.

Ellison, P.G.; Monson, P.R. (Westinghouse Savannah River Co., Aiken, SC (United States)); Mitchell, H.A. (Concord Associates, Inc., Knoxville, TN (United States))

1990-01-01T23:59:59.000Z

192

Modeling requirements for full-scope reactor simulators of fission-product transport during severe accidents  

SciTech Connect

This paper describes in the needs and requirements to properly and efficiently model fission product transport on full scope reactor simulators. Current LWR simulators can be easily adapted to model severe accident phenomena and the transport of radionuclides. Once adapted these simulators can be used as a training tool during operator training exercises for training on severe accident guidelines, for training on containment venting procedures, or as training tool during site wide emergency training exercises.

Ellison, P.G.; Monson, P.R. [Westinghouse Savannah River Co., Aiken, SC (United States); Mitchell, H.A. [Concord Associates, Inc., Knoxville, TN (United States)

1990-12-31T23:59:59.000Z

193

Stochastic Dynamic Demand Inventory Models with Explicit Transportation Costs and Decisions  

E-Print Network (OSTI)

is the policy where several small loads will be dispatched as a single, combined load. From an inventory-modeling perspec- tive, the integrated inventory-transportation problems add dispatch quantities as decision variables to the stochastic dynamic inventory...): The vendor makes the inventory replen- ishment decisions on how much to order from the outside supplier. 2. Pure Outbound Transportation Models (PO): The collection depot makes the delivery schedules of order dispatches to the buyer(s). 3. Integrated...

Zhang, Liqing

2011-07-01T23:59:59.000Z

194

Application of multidimensional analytical transport models to coal-tar derivatives  

E-Print Network (OSTI)

APPLICATION OF MULTIDIMENSIONAL ANALYTICAL TRANSPORT MODELS TO COAL-TAR DERIVATIVES A Thesis by YOUN SIM Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE May 1992 Major Subject: Geology APPLICATION OF MULTIDIMENSIONAL ANALYTICAL TRANSPORT MODELS TO COAL-TAR DERIVATIVES A Thesis by YOUN SIM Approved as to style and content by: Patrick A. Domenico (Chair of Committee) N man...

Sim, Youn

2012-06-07T23:59:59.000Z

195

Reaction of nitric oxide with heme proteins and model compounds of hemoglobin  

SciTech Connect

Rates for the reaction of nitric oxide with several ferric heme proteins and model compounds have been measured. The NO combination rates are markedly affected by the presence or absence of distal histidine. Elephant myoglobin in which the E7 distal histidine has been replaced by glutamine reacts with NO 500-1000 times faster than do the native hemoglobins or myoglobins. By contrast, there is not difference in the CO combination rate constants of sperm whale and elephant myoglobins. Studies on ferric model compounds for the R and T states of hemoglobin indicate that their NO combination rate constants are similar to those observed for the combination of CO with the corresponding ferro derivatives. The last observation suggests that the presence of an axial water molecule at the ligand binding site of ferric hemoglobin A prevents it from exhibiting significant cooperativity in its reactions with NO.

Sharma, V.S.; Traylor, T.G.; Gardiner, R.; Mizukami, H.

1987-06-30T23:59:59.000Z

196

Mass transfer model for two-layer TBP oxidation reactions: Revision 1  

SciTech Connect

To prove that two-layer, TBP-nitric acid mixtures can be safely stored in the Canyon evaporators, it must be demonstrated that a runaway reaction between TBP and nitric acid will not occur. Previous bench-scale experiments showed that, at typical evaporator temperatures, this reaction is endothermic and therefore cannot run away, due to the loss of heat from evaporation of water in the organic layer. However, the reaction would be exothermic and could run away if the small amount of water in the organic layer evaporates before the nitric acid in this layer is consumed by the reaction. Provided that there is enough water in the aqueous layer, this would occur if the organic layer is sufficiently thick so that the rate of loss of water by evaporation exceeds the rate of replenishment due to mixing with the aqueous layer. Bubbles containing reaction products enhance the rate of transfer of water from the aqueous layer to the organic layer. These bubbles are generated by the oxidation of TBP and its reaction products in the organic layer and by the oxidation of butanol in the aqueous layer. Butanol is formed by the hydrolysis of TBP in the organic layer. For aqueous-layer bubbling to occur, butanol must transfer into the aqueous layer. Consequently, the rate of oxidation and bubble generation in the aqueous layer strongly depends on the rate of transfer of butanol from the organic to the aqueous layer. This report presents measurements of mass transfer rates for the mixing of water and butanol in two-layer, TBP-aqueous mixtures, where the top layer is primarily TBP and the bottom layer is comprised of water or aqueous salt solution. Mass transfer coefficients are derived for use in the modeling of two-layer TBP-nitric acid oxidation experiments.

Laurinat, J.E.

1994-11-04T23:59:59.000Z

197

Modeling reaction quench times in the waste heat boiler of a Claus plant  

SciTech Connect

At the high temperatures found in the modified Claus reaction furnace, the thermal decomposition and oxidation of H[sub 2]S yields large quantities of desirable products, gaseous hydrogen (H[sub 2]) and sulfur (S[sub 2]). However, as the temperature of the gas stream is lowered in the waste heat boiler (WHB) located downstream of the furnace, the reverse reaction occurs leading to reassociation of H[sub 2] and S[sub 2] molecules. To examine the reaction quenching capabilities of the WHB, a rigorous computer model was developed incorporating recently published intrinsic kinetic data. A sensitivity study performed with the model demonstrated that WHBs have a wide range of operation with gas mass flux in the tubes from 4 to 24 kg/(m[sup 2] [center dot] s). Most important, the model showed that is was possible to operate WHBs such that quench times could be decreased to 40 ms, which is a reduction by 60% compared to a base case scenario. Furthermore, hydrogen production could be increased by over 20% simply by reconfiguring the WHB tubes.

Nasato, L.V.; Karan, K.; Mehrotra, A.K.; Behie, L.A. (Univ. of Calgary, Alberta (Canada). Dept. of Chemical and Petroleum Engineering)

1994-01-01T23:59:59.000Z

198

A MODEL FOR THE FLEET SIZING OF DEMAND RESPONSIVE TRANSPORTATION SERVICES WITH TIME WINDOWS  

E-Print Network (OSTI)

A MODEL FOR THE FLEET SIZING OF DEMAND RESPONSIVE TRANSPORTATION SERVICES WITH TIME WINDOWS Marco a demand responsive transit service with a predetermined quality for the user in terms of waiting time models; Continuous approximation models; Paratransit services; Demand responsive transit systems. #12;3 1

Dessouky, Maged

199

Journal of Transportation Engineering Modelling Automobile Driver's Toll-Lane Choice Behaviour at a Toll Plaza  

E-Print Network (OSTI)

Journal of Transportation Engineering Modelling Automobile Driver's Toll-Lane Choice Behaviour at a Toll Plaza --Manuscript Draft-- Manuscript Number: TEENG-1181R3 Full Title: Modelling Automobile Driver to develop a random utility based discrete multinomial choice model for the behaviour of automobile drivers

Kundu, Debasis

200

A fully resolved active musculo-mechanical model for esophageal transport  

E-Print Network (OSTI)

Esophageal transport is a physiological process that mechanically transports an ingested food bolus from the pharynx to the stomach via the esophagus, a multi-layered muscular tube. This process involves interactions between the bolus, the esophagus, and the neurally coordinated activation of the esophageal muscles. In this work, we use an immersed boundary (IB) approach to simulate peristaltic transport in the esophagus. The bolus is treated as a viscous fluid that is actively transported by the muscular esophagus, which is modeled as an actively contracting, fiber-reinforced tube. A simplified version of our model is verified by comparison to an analytic solution to the tube dilation problem. Three different complex models of the multi-layered esophagus, which differ in their activation patterns and the layouts of the mucosal layers, are then extensively tested. To our knowledge, these simulations are the first of their kind to incorporate the bolus, the multi-layered esophagus tube, and muscle activation i...

Kou, Wenjun; Griffith, Boyce E; Pandolfino, John E; Kahrilas, Peter J; Patankar, Neelesh A

2015-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "reaction transport model" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Oxygen Transport Ceramic Membranes Quarterly Report  

E-Print Network (OSTI)

/Reaction rates in Ion 21 Transport Membranes using Isotope Tracer and Transient Kinetic Techniques CONCLUSIONS 30Oxygen Transport Ceramic Membranes Quarterly Report January 2003 ­ March 2003 Principal Authors on the thermodynamic properties of the membrane materials are continued to develop a complete model for the membrane

Eagar, Thomas W.

202

Nucleus-nucleus cold fusion reactions analyzed with the l-dependent 'fusion by diffusion' model  

SciTech Connect

We present a modified version of the Fusion by Diffusion (FBD) model aimed at describing the synthesis of superheavy nuclei in cold fusion reactions, in which a low excited compound nucleus emits only one neutron. The modified FBD model accounts for the angular momentum dependence of three basic factors determining the evaporation residue cross section: the capture cross section {sigma}{sub cap}(l), the fusion probability P{sub fus}(l), and the survival probability P{sub surv}(l). The fusion hindrance factor, the inverse of P{sub fus}(l), is treated in terms of thermal fluctuations in the shape degrees of freedom and is expressed as a solution of the Smoluchowski diffusion equation. The l dependence of P{sub fus}(l) results from the l-dependent potential energy surface of the colliding system. A new parametrization of the distance of starting point of the diffusion process is introduced. An analysis of a complete set of 27 excitation functions for production of superheavy nuclei in cold fusion reactions, studied in experiments at GSI Darmstadt, RIKEN Tokyo, and LBNL Berkeley, is presented. The FBD model satisfactorily reproduces shapes and absolute cross sections of all the cold fusion excitation functions. It is shown that the peak position of the excitation function for a given 1n reaction is determined by the Q value of the reaction and the height of the fission barrier of the final nucleus. This fact could possibly be used in future experiments (with well-defined beam energy) for experimental determination of the fission barrier heights.

Cap, T.; Siwek-Wilczynska, K.; Wilczynski, J. [Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Hoza 69, PL-00-681 Warsaw (Poland); Andrzej Soltan Institute for Nuclear Studies, PL-05-400 Otwock-Swierk (Poland)

2011-05-15T23:59:59.000Z

203

Model simulation and experiments of flow and mass transport through a nano-material gas filter  

SciTech Connect

A computational model for evaluating the performance of nano-material packed-bed filters was developed. The porous effects of the momentum and mass transport within the filter bed were simulated. For the momentum transport, an extended Ergun-type model was employed and the energy loss (pressure drop) along the packed-bed was simulated and compared with measurement. For the mass transport, a bulk dsorption model was developed to study the adsorption process (breakthrough behavior). Various types of porous materials and gas flows were tested in the filter system where the mathematical models used in the porous substrate were implemented and validated by comparing with experimental data and analytical solutions under similar conditions. Good agreements were obtained between experiments and model predictions.

Yang, Xiaofan; Zheng, Zhongquan C.; Winecki, Slawomir; Eckels, Steve

2013-11-01T23:59:59.000Z

204

Modeling the cathode compartment of polymer electrolyte fuel cells: Dead and active reaction zones  

SciTech Connect

A two-dimensional model of the cathode compartment of a polymer electrolyte fuel cell has been developed. The existence of gas channels in the current collector is taken into account. The model is based on continuity equations for concentrations of the gases and Poisson's equations for potentials of membrane and carbon phase, coupled by Tafel relation for reaction kinetics. Stefan-Maxwell and Knudsen diffusion of gases are taken into account. The simulations were performed for high and low values of carbon phase conductivity. The results revealed (i) for a low value of carbon phase conductivity, a dead zone in the active layer in front of the gas channel is formed, where the reaction rate is small. The catalyst may be removed from this zone without significant loss in cell performance; (ii) For a high carbon phase conductivity value, such a zone is absent, but removal of the catalyst from the same part of the active layer forces the reaction to proceed more rapidly in the remaining parts, with only marginal losses in performance. This conclusion is valid for high diffusivity of oxygen. For low diffusivity, dead zones are formed in front of the current collector, so that catalyst can be removed from these zones. The results, thus, show the possibilities for a considerable reduction of the amount of catalyst.

Kulikovsky, A.A.; Divisek, J.; Kornyshev, A.A.

1999-11-01T23:59:59.000Z

205

Including radiative heat transfer and reaction quenching in modeling a Claus plant waste heat boiler  

SciTech Connect

Due to increasingly stringent sulfur emission regulations, improvements are necessary in the modified Claus process. A recently proposed model by Nasato et al. for the Claus plant waste heat boiler (WHB) is improved by including radiative heat transfer, which yields significant changes in the predicted heat flux and the temperature profile along the WHB tube, leading to a faster quenching of chemical reactions. For the WHB considered, radiation accounts for approximately 20% of the heat transferred by convection alone. More importantly, operating the WHB at a higher gas mass flux is shown to enhance reaction quenching, resulting in a doubling of the predicted hydrogen flow rate. This increase in hydrogen flow rate is sufficient to completely meet the hydrogen requirement of the H[sub 2]S recovery process considered, which would eliminate the need for a hydrogen plant.

Karan, K.; Mehrotra, A.K.; Behie, L.A. (Univ. of Calgary, Alberta (Canada). Dept. of Chemical and Petroleum Engineering)

1994-11-01T23:59:59.000Z

206

Idealized tracer transport models with time-varying transport: applications to ocean boundary currents  

Science Journals Connector (OSTI)

One-dimensional advectiondiffusion and advectiondiffusiondilution (or leaky-pipe) models have been widely used to interpret a variety of geophysical phenomena. For example, in the ocean these tools have been...

F. Terenzi; Timothy M. Hall

2010-04-01T23:59:59.000Z

207

Recent developments of the cascade-exciton model of nuclear reactions  

SciTech Connect

Recent developments of the Cascade-Exciton Model (CEM) of nuclear reactions are described. The improved cascade-exciton model as implemented in the code CEM97 differs from the CEM95 version by incorporating new approximations for the elementary cross sections used in the cascade, using more precise values for nuclear masses and pairing energies, using corrected systematics for the level-density parameters, and several other refinements. We have improved algorithms used in many subroutines, decreasing the computing time by up to a factor of 6 for heavy targets. We describe a number of further improvements and changes to CEM97, motivated by new data on isotope production measured at GSI. This leads us to CEM2k, a new version of the CEM code. CEM2k has a longer cascade stage, less preequilibrium emission, and evaporation from more highly excited compound nuclei compared to earlier versions. CEM2k also has other improvements and allows us to better model neutron, radionuclide, and gas production in ATW spallation targets. The increased accuracy and predictive power of the code CEM2k are shown by several examples. Further necessary work is outlined. KEYWORDS: Intranuclear cascade, preequilibrium, evaporation, and fission reactions, Monte Carlo simulations, cascade-exciton model, particle spectra, spallation and fission cross sections, GSI data

Mashnik, S. G. (Stepan G.); Sierk, A. J. (Arnold J.)

2001-01-01T23:59:59.000Z

208

Transport enhancement and suppression in turbulent magnetic reconnection: A self-consistent turbulence model  

SciTech Connect

Through the enhancement of transport, turbulence is expected to contribute to the fast reconnection. However, the effects of turbulence are not so straightforward. In addition to the enhancement of transport, turbulence under some environment shows effects that suppress the transport. In the presence of turbulent cross helicity, such dynamic balance between the transport enhancement and suppression occurs. As this result of dynamic balance, the region of effective enhanced magnetic diffusivity is confined to a narrow region, leading to the fast reconnection. In order to confirm this idea, a self-consistent turbulence model for the magnetic reconnection is proposed. With the aid of numerical simulations where turbulence effects are incorporated in a consistent manner through the turbulence model, the dynamic balance in the turbulence magnetic reconnection is confirmed.

Yokoi, N. [Institute of Industrial Science, University of Tokyo, Tokyo (Japan)] [Institute of Industrial Science, University of Tokyo, Tokyo (Japan); Higashimori, K.; Hoshino, M. [Department of Earth and Planetary Science, University of Tokyo, Tokyo (Japan)] [Department of Earth and Planetary Science, University of Tokyo, Tokyo (Japan)

2013-12-15T23:59:59.000Z

209

Flow and transport model of the Savannah River Site Old Burial Grounds using Data Fusion modeling (DFM)  

SciTech Connect

The Data Fusion Modeling (DFM) approach has been used to develop a groundwater flow and transport model of the Old Burial Grounds (OBG) at the US Department of Energy`s Savannah River Site (SRS). The resulting DFM model was compared to an existing model that was calibrated via the typical trial-and-error method. The OBG was chosen because a substantial amount of hydrogeologic information is available, a FACT (derivative of VAM3DCG) flow and transport model of the site exists, and the calibration and numerics were challenging with standard approaches. The DFM flow model developed here is similar to the flow model by Flach et al. This allows comparison of the two flow models and validates the utility of DFM. The contaminant of interest for this study is tritium, because it is a geochemically conservative tracer that has been monitored along the seepline near the F-Area effluent and Fourmile Branch for several years.

NONE

1995-11-01T23:59:59.000Z

210

Modeling electron transport in the presence of electric and magnetic fields.  

SciTech Connect

This report describes the theoretical background on modeling electron transport in the presence of electric and magnetic fields by incorporating the effects of the Lorentz force on electron motion into the Boltzmann transport equation. Electromagnetic fields alter the electron energy and trajectory continuously, and these effects can be characterized mathematically by differential operators in terms of electron energy and direction. Numerical solution techniques, based on the discrete-ordinates and finite-element methods, are developed and implemented in an existing radiation transport code, SCEPTRE.

Fan, Wesley C.; Drumm, Clifton Russell; Pautz, Shawn D.; Turner, C. David

2013-09-01T23:59:59.000Z

211

Coupled modeling of grounddwater flow solute transport, chemical reactions and microbial processes in the "SP" island  

E-Print Network (OSTI)

rock /SKB, 1995/. Underground facilities will have to beis a prototype, full-scale underground facility launched andof Stockholm. The underground facility consists of a 3,600 m

Samper, Javier; Molinero, Jorg; Changbing, Yang; Zhang, Guoxiang

2003-01-01T23:59:59.000Z

212

Development of a scalable model for predicting arsenic transport coupled with oxidation and adsorption reactions  

E-Print Network (OSTI)

Department of Civil Engineering, 238 Harbert Engineering Center, Auburn University, AL, 36849, United States al., 2004). The presence of arsenic in natural waters is controlled by adsorption, ion exchange

Clement, Prabhakar

213

Coupled modeling of grounddwater flow solute transport, chemical reactions and microbial processes in the "SP" island  

E-Print Network (OSTI)

in cements is the ettringite (a highly soluble calcium andBrucite Foshagite Calcite Ettringite Recharge water Na Ca Mg

Samper, Javier; Molinero, Jorg; Changbing, Yang; Zhang, Guoxiang

2003-01-01T23:59:59.000Z

214

Coupled Model for Heat and Water Transport in a High Level Waste Repository  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Coupled Model for Heat and Water Transport in a High Level Waste Coupled Model for Heat and Water Transport in a High Level Waste Repository in Salt Coupled Model for Heat and Water Transport in a High Level Waste Repository in Salt This report summarizes efforts to simulate coupled thermal-hydrological-chemical (THC) processes occurring within a generic hypothetical high-level waste (HLW) repository in bedded salt; chemical processes of the system allow precipitation and dissolution of salt with elevated temperatures that drive water and water vapor flow around hot waste packages. Characterizing salt backfill processes is an important objective of the exercise. An evidence-based algorithm for mineral dehydration is also applied in the modeling. The Finite Element Heat and Mass transfer code (FEHM) is used to simulate coupled thermal,

215

The investigation of fracture aperture effect on shale gas transport using discrete fracture model  

Science Journals Connector (OSTI)

Abstract Discrete fracture model (DFM) numerical simulation is used to investigate the shale gas transports in fractured porous media in this paper. A new seepage flow mathematic model, in which flow in fracture meets Cubic law and matrix meets non-Darcy law, is adopted and fracture aperture effect on the transport behavior is simulated by solving the nonlinear partial differential equations using finite element analysis (FEA). In this DFM, fluid flows into wellbore which is surrounded by impermeable rock matrix is merely through fractures that connect to it. The model is used to simulate a random generated fractures network to study the flow and transport characteristics in fractured porous media (FPM). Several cases with different fracture aperture in same natural fractured model are given. The preliminary simulation results show that both the natural and hydraulic fracture aperture have a significant impact on shale gas migration and production.

Lidong Mi; Hanqiao Jiang; Junjian Li; Tao Li; Ye Tian

2014-01-01T23:59:59.000Z

216

Phase II Contaminant Transport Parameters for the Groundwater Flow and Contaminant Transport Model of Corrective Action Unit 98: Frenchman Flat, Nye County, Nevada, Rev. No.: 0  

SciTech Connect

This report documents pertinent transport data and data analyses as part of the Phase II Corrective Action Investigation (CAI) for Frenchman Flat (FF) Corrective Action Unit (CAU) 98. The purpose of this data compilation and related analyses is to provide the primary reference to support parameterization of the Phase II FF CAU transport model.

DeNovio, Nicole M.; Bryant, Nathan; King, Chrissi B.; Bhark, Eric; Drellack, Sigmund L.; Pickens, John F.; Farnham, Irene; Brooks, Keely M.; Reimus, Paul; Aly, Alaa

2005-04-01T23:59:59.000Z

217

Constructing a Model Transport Equation for a Massless Bose Gas and its Analytic Solution  

E-Print Network (OSTI)

A model kinetic equation is constructed for the transport of a massless Bose gas. This equation is applied to solution of the boundary value problem for the transport of radiation in the half-space occupied by a dispersive medium that is in local thermal equilibrium with the radiation. It is shown that the difference in temperature between the dispersive medium and the incident radiation depends substantially on the character of the scattering properties of the particles of the medium.

A. V. Latyshev; A. A. Yushkanov

2010-12-14T23:59:59.000Z

218

Assimilation of satellite images into a sediment transport model of Lake Michigan  

E-Print Network (OSTI)

by combining the satellite data with the numerical model. In our application, we find that data assimilationAssimilation of satellite images into a sediment transport model of Lake Michigan Jonathan R consider two data assimilation methods, direct insertion and a kriging-based approach, and perform

Stroud, Jonathan

219

ABSORPTION-DELAY MODELS OF HEAT TRANSPORT R.E. SHOWALTER AND D.B. VISARRAGA  

E-Print Network (OSTI)

ABSORPTION-DELAY MODELS OF HEAT TRANSPORT R.E. SHOWALTER AND D.B. VISARRAGA Abstract. A temperature jump in the water traveling through a pipe is delayed by the absorption of heat into the pipe wall transfer, absorption, memory, kinetic models, approximation. 1 #12;2 R.E. SHOWALTER AND D.B. VISARRAGA 1

220

Grand challenge problems in environmental modeling and remediation: groundwater contaminant transport  

SciTech Connect

This report describes briefly the work of the Center for Subsurface Modeling (CSM) of the University of Texas at Austin (and Rice University prior to September 1995) on the Partnership in Computational Sciences Consortium (PICS) project entitled Grand Challenge Problems in Environmental Modeling and Remediation: Groundwater Contaminant Transport.

Todd Arbogast; Steve Bryant; Clint N. Dawson; Mary F. Wheeler

1998-08-31T23:59:59.000Z

Note: This page contains sample records for the topic "reaction transport model" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Ris-R-1201(EN) Radon Transport Modelling  

E-Print Network (OSTI)

in atmospheric pressure. It can also be used for flux calculations of radon from the soil surface or to model of soil gas and combined generation, radioactive decay, diffusion and advection of radon can be solved. Moisture is included in the model, and partitioning of radon between air, water and soil grains (adsorption

222

Contaminant Transport Parameters for the Groundwater Flow and Contaminant Transport Model of Corrective Action Units 101 and 102: Central and Western Pahute Mesa, Nye County, Nevada, Revision 0  

SciTech Connect

This report documents the analysis of the available transport parameter data conducted in support of the development of a Corrective Action Unit (CAU) groundwater flow model for Central and Western Pahute Mesa: CAUs 101 and 102.

Drici, Warda

2003-08-01T23:59:59.000Z

223

Modeling the coupled mechanics, transport, and growth processes in collagen tissues.  

SciTech Connect

The purpose of this project is to develop tools to model and simulate the processes of self-assembly and growth in biological systems from the molecular to the continuum length scales. The model biological system chosen for the study is the tendon fiber which is composed mainly of Type I collagen fibrils. The macroscopic processes of self-assembly and growth at the fiber scale arise from microscopic processes at the fibrillar and molecular length scales. At these nano-scopic length scales, we employed molecular modeling and simulation method to characterize the mechanical behavior and stability of the collagen triple helix and the collagen fibril. To obtain the physical parameters governing mass transport in the tendon fiber we performed direct numerical simulations of fluid flow and solute transport through an idealized fibrillar microstructure. At the continuum scale, we developed a mixture theory approach for modeling the coupled processes of mechanical deformation, transport, and species inter-conversion involved in growth. In the mixture theory approach, the microstructure of the tissue is represented by the species concentration and transport and material parameters, obtained from fibril and molecular scale calculations, while the mechanical deformation, transport, and growth processes are governed by balance laws and constitutive relations developed within a thermodynamically consistent framework.

Holdych, David J.; Nguyen, Thao D.; Klein, Patrick A.; in't Veld, Pieter J.; Stevens, Mark Jackson

2006-11-01T23:59:59.000Z

224

Conceptual model for transport processes in the Culebra Dolomite Member, Rustler Formation  

SciTech Connect

The Culebra Dolomite Member of the Rustler Formation represents a possible pathway for contaminants from the Waste Isolation Pilot Plant underground repository to the accessible environment. The geologic character of the Culebra is consistent with a double-porosity, multiple-rate model for transport in which the medium is conceptualized as consisting of advective porosity, where solutes are carried by the groundwater flow, and fracture-bounded zones of diffusive porosity, where solutes move through slow advection or diffusion. As the advective travel length or travel time increases, the nature of transport within a double-porosity medium changes. This behavior is important for chemical sorption, because the specific surface area per unit mass of the diffusive porosity is much greater than in the advective porosity. Culebra transport experiments conducted at two different length scales show behavior consistent with a multiple-rate, double-porosity conceptual model for Culebra transport. Tracer tests conducted on intact core samples from the Culebra show no evidence of significant diffusion, suggesting that at the core scale the Culebra can be modeled as a single-porosity medium where only the advective porosity participates in transport. Field tracer tests conducted in the Culebra show strong double-porosity behavior that is best explained using a multiple-rate model.

Holt, R.M. [Holt Hydrogeology, Placitas, NM (United States)] [Holt Hydrogeology, Placitas, NM (United States)

1997-08-01T23:59:59.000Z

225

Conceptual model for regional radionuclide transport from a salt dome repository: a technical memorandum  

SciTech Connect

Disposal of high-level radioactive wastes is a major environmental problem influencing further development of nuclear energy in this country. Salt domes in the Gulf Coast Basin are being investigated as repository sites. A major concern is geologic and hydrologic stability of candidate domes and potential transport of radionuclides by groundwater to the biosphere prior to their degradation to harmless levels of activity. This report conceptualizes a regional geohydrologic model for transport of radionuclides from a salt dome repository. The model considers transport pathways and the physical and chemical changes that would occur through time prior to the radionuclides reaching the biosphere. Necessary, but unknown inputs to the regional model involve entry and movement of fluids through the repository dome and across the dome-country rock interface and the effect on the dome and surrounding strata of heat generated by the radioactive wastes.

Kier, R.S.; Showalter, P.A.; Dettinger, M.D.

1980-05-30T23:59:59.000Z

226

PATHWAY: a simulation model of radionuclide-transport through agricultural food chains  

SciTech Connect

PATHWAY simulates the transport of radionuclides from fallout through an agricultural ecosystem. The agro-ecosystem is subdivided into several land management units, each of which is used either for grazing animals, for growing hay, or for growing food crops. The model simulates the transport of radionuclides by both discrete events and continuous, time-dependent processes. The discrete events include tillage of soil, harvest and storage of crops,and deposition of fallout. The continuous processes include the transport of radionuclides due to resuspension, weathering, rain splash, percolation, leaching, adsorption and desorption of radionuclides in the soil, root uptake, foliar absorption, growth and senescence of vegetation, and the ingestion assimilation, and excretion of radionuclides by animals. Preliminary validation studies indicate that the model dynamics and simulated values of radionuclide concentrations in several agricultural products agree well with measured values when the model is driven with site specific data on deposition from world-wide fallout.

Kirchner, T.B.; Whicker, F.W.; Otis, M.D.

1982-01-01T23:59:59.000Z

227

Heat Transport in Groundwater Systems--Finite Element Model  

E-Print Network (OSTI)

into groundwater aquifers for long term energy storage. Analytical solutions are available that predict water temperatures as hot water is injected into a groundwater aquifer, but little field and laboratory data are available to verify these models. The objectives...

Grubaugh, E. K.; Reddell, D. L.

228

Lattice-gas model for active vesicle transport by molecular motors with opposite polarities  

E-Print Network (OSTI)

We introduce a multi-species lattice gas model for motor protein driven collective cargo transport on cellular filaments. We use this model to describe and analyze the collective motion of interacting vesicle cargoes being carried by oppositely directed molecular motors, moving on a single biofilament. Building on a totally asymmetric exclusion process (TASEP) to characterize the motion of the interacting cargoes, we allow for mass exchange with the environment, input and output at filament boundaries and focus on the role of interconversion rates and how they affect the directionality of the net cargo transport. We quantify the effect of the various different competing processes in terms of non-equilibrium phase diagrams. The interplay of interconversion rates, which allow for flux reversal and evaporation/deposition processes introduce qualitatively new features in the phase diagrams. We observe regimes of three-phase coexistence, the possibility of phase re-entrance and a significant flexibility in how the different phase boundaries shift in response to changes in control parameters. The moving steady state solutions of this model allows for different possibilities for the spatial distribution of cargo vesicles, ranging from homogeneous distribution of vesicles to polarized distributions, characterized by inhomogeneities or {\\it shocks}. Current reversals due to internal regulation emerge naturally within the framework of this model. We believe this minimal model will clarify the understanding of many features of collective vesicle transport, apart from serving as the basis for building more exact quantitative models for vesicle transport relevant to various {\\it in-vivo} situations.

Sudipto Muhuri; Ignacio Pagonabarraga

2010-09-09T23:59:59.000Z

229

A Practical Model for Subsurface Light Transport Henrik Wann Jensen Stephen R. Marschner Marc Levoy Pat Hanrahan  

E-Print Network (OSTI)

by solving the full radiative transfer equation [1]. Only a few papers in graphics have taken this approachA Practical Model for Subsurface Light Transport Henrik Wann Jensen Stephen R. Marschner Marc Levoy transport in translucent materials. The model enables efficient simulation of effects that BRDF models

O'Brien, James F.

230

Extended sudden approximation modeling of high-energy nucleon-removal reactions  

Science Journals Connector (OSTI)

Calculations based on the sudden approximation have been performed to describe high-energy single-nucleon removal reactions. Within this approach, which takes as its starting point the formalism developed to describe the breakup of well-developed single-neutron halo systems, the nucleon-removal cross section and the full three-dimensional momentum distributions of the core fragments, including absorption, diffraction, Coulomb, and nuclear-Coulomb interference amplitudes, have been computed. The Coulomb, breakup has been treated to all orders for the dipole interaction. The results are compared here to experimental data for a range of light, neutron-rich psd-shell nuclei taken at beam energies of 4368MeV?nucleon. Good agreement is found for the inclusive cross sections and both the longitudinal and transverse momentum distributions. In the case of C17, comparison is also made with the results of calculations using the transfer-to-the-continuum model. The three-dimensional momentum distributions computed within the sudden approximation model exhibit longitudinal and transverse momentum components that are strongly coupled by the reaction for s-wave states, while no such effect is apparent for d waves. Incomplete detection of transverse momenta arising from limited experimental acceptances thus leads to a narrowing of the longitudinal distributions for nuclei with significant s-wave valence neutron configurations, as confirmed by the data. Asymmetries in the longitudinal momentum distributions attributed to diffractive dissociation are also explored.

F. Carstoiu; E. Sauvan; N. A. Orr; A. Bonaccorso

2004-11-04T23:59:59.000Z

231

Application of computer modeling techniques to the kinetics of the reaction of carbon with oxygen  

SciTech Connect

Computer modeling techniques are applied to the kinetics of the reaction of carbon with oxygen. The rates of disappearance of oxygen, of formation of CO, CO/sub 2/ and the surface complex, measured over the temperature range 748-1173 K and the pressure range 0.5-400 Pa may be described by a mechanism involving adsorption of oxygen, formation of the strongly-bound complex, desorption of the complex and reaction of the complex with a gas-phase molecule of oxygen. The latter is shown to be an important source of CO/sub 2/ at low temperatures and higher pressures of oxygen. An important feature of the mechanism is the existence of at least two distinct types of active sites for the binding of the complex on the carbon surface, each with a characteristic reactivity. Most of the results on which the model is based were obtained using thin films of pyrolytic carbon, but some results from the oxidation of graphon are also consistent with the mechanism.

Ahmed, S.; Back, M.H.; Roscoe, J.M.

1989-01-01T23:59:59.000Z

232

Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model  

SciTech Connect

This Analysis/Model Report (AMR) documents an updated analysis of water-level data performed to provide the saturated-zone, site-scale flow and transport model (CRWMS M&O 2000) with the configuration of the potentiometric surface, target water-level data, and hydraulic gradients for model calibration. The previous analysis was presented in ANL-NBS-HS-000034, Rev 00 ICN 01, Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model (USGS 2001). This analysis is designed to use updated water-level data as the basis for estimating water-level altitudes and the potentiometric surface in the SZ site-scale flow and transport model domain. The objectives of this revision are to develop computer files containing (1) water-level data within the model area (DTN: GS010908312332.002), (2) a table of known vertical head differences (DTN: GS0109083 12332.003), and (3) a potentiometric-surface map (DTN: GS010608312332.001) using an alternate concept from that presented in ANL-NBS-HS-000034, Rev 00 ICN 01 for the area north of Yucca Mountain. The updated water-level data include data obtained from the Nye County Early Warning Drilling Program (EWDP) and data from borehole USW WT-24. In addition to being utilized by the SZ site-scale flow and transport model, the water-level data and potentiometric-surface map contained within this report will be available to other government agencies and water users for ground-water management purposes. The potentiometric surface defines an upper boundary of the site-scale flow model, as well as provides information useful to estimation of the magnitude and direction of lateral ground-water flow within the flow system. Therefore, the analysis documented in this revision is important to SZ flow and transport calculations in support of total system performance assessment.

P. Tucci

2001-12-20T23:59:59.000Z

233

Realistic multisite lattice-gas modeling and KMC simulation of catalytic surface reactions: Kinetics and multiscale spatial behavior for CO-oxidation on metal (100) surfaces  

SciTech Connect

A realistic molecular-level description of catalytic reactions on single-crystal metal surfaces can be provided by stochastic multisite lattice-gas (msLG) models. This approach has general applicability, although in this report, we will focus on the example of CO-oxidation on the unreconstructed fcc metal (100) or M(100) surfaces of common catalyst metals M = Pd, Rh, Pt and Ir (i.e., avoiding regimes where Pt and Ir reconstruct). These models can capture the thermodynamics and kinetics of adsorbed layers for the individual reactants species, such as CO/M(100) and O/M(100), as well as the interaction and reaction between different reactant species in mixed adlayers, such as (CO + O)/M(100). The msLG models allow population of any of hollow, bridge, and top sites. This enables a more flexible and realistic description of adsorption and adlayer ordering, as well as of reaction configurations and configuration-dependent barriers. Adspecies adsorption and interaction energies, as well as barriers for various processes, constitute key model input. The choice of these energies is guided by experimental observations, as well as by extensive Density Functional Theory analysis. Model behavior is assessed via Kinetic Monte Carlo (KMC) simulation. We also address the simulation challenges and theoretical ramifications associated with very rapid diffusion and local equilibration of reactant adspecies such as CO. These msLG models are applied to describe adsorption, ordering, and temperature programmed desorption (TPD) for individual CO/M(100) and O/M(100) reactant adlayers. In addition, they are also applied to predict mixed (CO + O)/M(100) adlayer structure on the nanoscale, the complete bifurcation diagram for reactive steady-states under continuous flow conditions, temperature programmed reaction (TPR) spectra, and titration reactions for the CO-oxidation reaction. Extensive and reasonably successful comparison of model predictions is made with experimental data. Furthermore, we discuss the possible transition from traditional mean-field-type bistability and reaction kinetics for lower-pressure to multistability and enhanced fluctuation effects for moderate- or higher-pressure. Behavior in the latter regime reflects a stronger influence of adspecies interactions and also lower diffusivity in the higher-coverage mixed adlayer. We also analyze mesoscale spatiotemporal behavior including the propagation of reaction diffusion fronts between bistable reactive and inactive states, and associated nucleation-mediated transitions between these states. This behavior is controlled by complex surface mass transport processes, specifically chemical diffusion in mixed reactant adlayers for which we provide a precise theoretical formulation. The msLG models together with an appropriate treatment of chemical diffusivity enable equation-free heterogeneous coupled lattice-gas (HCLG) simulations of spatiotemporal behavior. In addition, msLG + HCLG modeling can describe coverage variations across polycrystalline catalysts surfaces, pressure variations across catalyst surfaces in microreactors, and could be incorporated into a multiphysics framework to describe mass and heat transfer limitations for high-pressure catalysis. (C) 2013 Elsevier Ltd. All rights reserved.

Liu, Dajiang [Ames Laboratory; Evans, James W. [Ames Laboratory

2013-12-01T23:59:59.000Z

234

Transported PDF Modeling of Nonpremixed Turbulent CO/H-2/N-2 Jet Flames  

SciTech Connect

Turbulent CO/H{sub 2}/N{sub 2} (syngas) flames are simulated using a transported composition probability density function (PDF) method. A consistent hybrid Lagrangian particle/Eulerian mesh algorithm is used to solve the modeled PDF transport equation. The model includes standard k? turbulence, gradient transport for scalars, and Euclidean minimum spanning tree (EMST) mixing. Sensitivities of model results to variations in the turbulence model, the treatment of radiation heat transfer, the choice of chemical mechanism, and the PDF mixing model are explored. A baseline model reproduces the measured mean and rms temperature, major species, and minor species profiles reasonably well, and captures the scaling that is observed in the experiments. Both our results and the literature suggest that further improvements can be realized with adjustments in the turbulence model, the radiation heat transfer model, and the chemical mechanism. Although radiation effects are relatively small in these flames, consideration of radiation is important for accurate NO prediction. Chemical mechanisms that have been developed specifically for fuels with high concentrations of CO and H{sub 2} perform better than a methane mechanism that was not designed for this purpose. It is important to account explicitly for turbulencechemistry interactions, although the details of the mixing model do not make a large difference in the results, within reasonable limits.

Zhao, xinyu; Haworth, D. C.; Huckaby, E. David

2012-01-01T23:59:59.000Z

235

Hydrologic Nuclide Transport Models in Cyder, A Geologic Disposal Software Library - 13328  

SciTech Connect

Component level and system level abstraction of detailed computational geologic repository models have resulted in four rapid computational models of hydrologic radionuclide transport at varying levels of detail. Those models are described, as is their implementation in Cyder, a software library of interchangeable radionuclide transport models appropriate for representing natural and engineered barrier components of generic geology repository concepts. A proof of principle demonstration was also conducted in which these models were used to represent the natural and engineered barrier components of a repository concept in a reducing, homogenous, generic geology. This base case demonstrates integration of the Cyder open source library with the Cyclus computational fuel cycle systems analysis platform to facilitate calculation of repository performance metrics with respect to fuel cycle choices. (authors)

Huff, Kathryn D. [Argonne National Laboratory, 9700 S. Cass Ave, Argonne, IL (United States)] [Argonne National Laboratory, 9700 S. Cass Ave, Argonne, IL (United States)

2013-07-01T23:59:59.000Z

236

Development and applications of two finite element groundwater flow and contaminant transport models: FEWA and FEMA  

SciTech Connect

This paper presents the construction, verification, and application of two groundwater flow and contaminant transport models: A Finite Element Model of Water Flow through Aquifers (FEWA) and A Finite Element Model of Material Transport through Aquifers (FEMA). The construction is based on the finite element approximation of partial differential equations of groundwater flow (FEWA) and of solute movement (FEMA). The particular features of FEWA and FEMA are their versatility and flexibility for dealing with nearly all vertically integrated two-dimensional problems. The models were verified against both analytical solutions and widely used US Geological Survey finite difference approximations. They were then applied for calibration and validation, using data obtained in experiments at the Engineering Test Facility at Oak Ridge National Laboratory. Results indicated that the models are valid for this specific site. To demonstrate the versatility anf flexibility of the models, they were applied to two hypothetical, but realistic, complex problems and three field sites across the United States. In these applications the models yielded good agreement with the field data for all three sites. Finally, the predictive capabilities of the models were demonstrated using data obtained at the Hialeah Preston site in Florida. This case illustrates the capability of FEWA and FEMA as predictive tools and their usefulness in the management of groundwater flow and contaminant transport. 25 refs.

Yeh, G.T.; Wong, K.V.; Craig, P.M.; Davis, E.C.

1985-01-01T23:59:59.000Z

237

Testing and benchmarking of a three-dimensional groundwater flow and solute transport model  

SciTech Connect

A three-dimensional finite-difference model was developed to simulate groundwater flow and solute transport. The model is intended for application to a variety of groundwater resource and solute migration evaluations, including several complex sites at the Savannah River Plant (SRP). Because the model, FTWORK, is relatively new, there is a need to provide confidence in the model results. Methodologies that test models include comparisons with analytical solutions, comparisons with empirical data, and checking that conservation properties hold. Another level of testing is the comparison of one code against another. This paper describes the testing and benchmarking procedure used to verify the validate FTWORK.

Sims, P.N.; Andersen, P.F.; Faust, C.R. [GeoTrans, Inc., Herndon, VA (United States); Stephenson, D.E. [E.I. DuPont de Nemours and Co., Aiken, SC (United States)

1988-12-31T23:59:59.000Z

238

Bifurcation theory of a one-dimensional transport model for the L-H transition  

SciTech Connect

Transitions between low and high-confinement (L-H transitions) in magnetically confined plasmas can appear as three qualitatively different types: sharp, smooth, and oscillatory. Bifurcation analysis unravels these possible transition types and how they are situated in parameter space. In this paper the bifurcation analysis is applied to a 1-dimensional model for the radial transport of energy and density near the edge of magnetically confined plasmas. This phenomenological L-H transition model describes the reduction of the turbulent transport by EB-flow shear self-consistently with the evolution of the radial electric field. Therewith, the exact parameter space, including the threshold values of the control parameters, of the possible L-H transitions in the model is determined. Furthermore, a generalised equal area rule is derived to describe the evolution of the transport barrier in space and time self-consistently. Applying this newly developed rule to the model analysed in this paper reveals a naturally occurring transition to an extra wide transport barrier that may correspond to the improved confinement known as the very-high-confinement mode.

Weymiens, W.; Blank, H. J. de; Hogeweij, G. M. D. [FOM Institute DIFFERDutch Institute for Fundamental Energy Research, Association EURATOM-FOM, Trilateral Euregio Cluster, PO Box 1207, Nieuwegein (Netherlands)] [FOM Institute DIFFERDutch Institute for Fundamental Energy Research, Association EURATOM-FOM, Trilateral Euregio Cluster, PO Box 1207, Nieuwegein (Netherlands)

2013-08-15T23:59:59.000Z

239

Modeling dust emissions and transport within Europe: The Ukraine March 2007 event  

E-Print Network (OSTI)

Modeling dust emissions and transport within Europe: The Ukraine March 2007 event Bertrand originating from Ukraine related to chernozemic-erodible lands. Using surface and satellite measurements in the Netherlands, Belgium, and the north of France were mostly due to the extremely rare Ukraine dust event

Menut, Laurent

240

NASA/CR2011-215960 Modeling High-Speed Civil Tiltrotor Transports in the  

E-Print Network (OSTI)

NASA/CR­2011-215960 Modeling High-Speed Civil Tiltrotor Transports in the Next Generation Airspace-NNA06BC41C #12;Since its founding, NASA has been dedicated to the advancement of aeronautics and space science. The NASA Scientific and Technical Information (STI) Program Office plays a key part in helping

Note: This page contains sample records for the topic "reaction transport model" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Using reactive transport modeling to evaluate the source term at Yucca mountain  

Science Journals Connector (OSTI)

The conventional approach of source-term evaluation for performance assessment of nuclear waste repositories uses the dissolution rate of waste form and the solubility of pure phases of radioactive elements to constrain radionuclide concentrations. This ... Keywords: neptunium, nuclear waste, radionuclide solubility, reactive-transport modeling, secondary phases, spent nuclear fuel, uranium

Yueting Chen

2003-04-01T23:59:59.000Z

242

MODELLING OF TRANSPORT PHENOMENA FOR THE HYPERSONIC STAGNATION POINT HEAT TRANSFER PROBLEM  

E-Print Network (OSTI)

MODELLING OF TRANSPORT PHENOMENA FOR THE HYPERSONIC STAGNATION POINT HEAT TRANSFER PROBLEM A to vibrational mode el refers to electronic mode Introduction One of the major problems encountered in hypersonic. The hypersonic flow about such surfaces is charac­ terized by a strong bow shock, which converts the major part

243

Optimized regional and interannual variability of lightning in a global chemical transport model constrained  

E-Print Network (OSTI)

to remove their diurnal sampling bias, we construct a monthly time series of lightning flash rates for 1998, D20307, doi:10.1029/2012JD017934. 1. Introduction [2] The extreme heat in a lightning flash channelOptimized regional and interannual variability of lightning in a global chemical transport model

Jacob, Daniel J.

244

Reduced Order Model Compensator Control of Species Transport in a CVD Reactor  

E-Print Network (OSTI)

Reduced Order Model Compensator Control of Species Transport in a CVD Reactor G.M. Kepler, H for computation of feedback controls and compensators in a high pressure chemical vapor deposition (HPCVD) reactor, through open­loop optimization [6, 21, 34]. However, because of process variability and the in­ creasing

245

MANHAZ position paper on: Modelling of Pollutant Transport in the Atmosphere  

E-Print Network (OSTI)

MANHAZ position paper on: Modelling of Pollutant Transport in the Atmosphere Torben Mikkelsen July, Denmark I Atmospheric dispersion: Basic The dispersion of pollutants is intimately related to the state 2003 Atmospheric Physics Division Wind Energy Department Risø National Laboratory Dk-4000 Roskilde

246

A mixed finite-element scheme of a semiconductor energy-transport model  

E-Print Network (OSTI)

A mixed finite-element scheme of a semiconductor energy-transport model using dual entropy variables Stephan Gadau, Ansgar J¨ungel, and Paola Pietra Abstract. One-dimensional stationary energy employing a mixed-hybrid finite- element method which has the advantage to fulfill current conser- vation

Hanke-Bourgeois, Martin

247

Multiphase transport model for relativistic heavy ion collisions  

E-Print Network (OSTI)

of these results to experimental data, mainly from heavy ion collisions at the BNL Relativistic Heavy Ion Collider, are then made in order to extract information on the properties of the hot dense matter formed in these collisions. DOI: 10.1103/PhysRevC.72... quark and a diquark with weights according to relations from the SU(6) quark model [71], and the diquark is then decomposed into two quarks. The quark and diquark masses are taken to be the same as in the PYTHIA program [59], e.g.,mu = 5.6,md = 9.9...

Lin, ZW; Ko, Che Ming; Li, Ba; Zhang, B.; Pal, S.

2005-01-01T23:59:59.000Z

248

Fluctuations in a kinetic transport model for quantum friction  

E-Print Network (OSTI)

We consider a linear Boltzmann equation that arises in a model for quantum friction. It describes a particle that is slowed down by the emission of bosons. We study the stochastic process generated by this Boltzmann equation and we show convergence of its spatial trajectory to a multiple of Brownian motion with exponential scaling. The asymptotic position of the particle is finite in mean, even though its absolute value is typically infinite. This is contrasted to an approximation that neglects the influence of fluctuations, where the mean asymptotic position is infinite.

Roland Bauerschmidt; Wojciech de Roeck; Jrg Frhlich

2014-03-23T23:59:59.000Z

249

Peristaltic Transport of a Rheological Fluid: Model for Movement of Food Bolus Through Esophagus  

E-Print Network (OSTI)

Fluid mechanical peristaltic transport through esophagus has been of concern in the paper. A mathematical model has been developed with an aim to study the peristaltic transport of a rheological fluid for arbitrary wave shapes and tube lengths. The Ostwald-de Waele power law of viscous fluid is considered here to depict the non-Newtonian behaviour of the fluid. The model is formulated and analyzed with the specific aim of exploring some important information concerning the movement of food bolus through the esophagus. The analysis has been carried out by using lubrication theory. The study is particularly suitable for cases where the Reynolds number is small. The esophagus is treated as a circular tube through which the transport of food bolus takes places by periodic contraction of the esophageal wall. Variation of different variables concerned with the transport phenomena such as pressure, flow velocity, particle trajectory and reflux are investigated for a single wave as well as for a train of periodic peristaltic waves. Locally variable pressure is seen to be highly sensitive to the flow index `n'. The study clearly shows that continuous fluid transport for Newtonian/rheological fluids by wave train propagation is much more effective than widely spaced single wave propagation in the case of peristaltic movement of food bolus in the esophagus.

J. C. Misra; S. Maiti

2011-12-28T23:59:59.000Z

250

Spatially-resolved modeling of electric double layers and surface chemistry for the hydrogen oxidation reaction in  

E-Print Network (OSTI)

-Pt Tafel reaction [A-1] ( ) + - 2H +Pt H-Pt +H +e Heyrovsky reaction [A-2] ( ) + - H-Pt Pt+H +e Volmer of the Tafel-Volmer, Heyrovsky-Volmer or Tafel-Heyrovsky pathways: ( ) ( ) ( )2 2HOR H V T H V Tj F F F the Tafel and Heyrovsky steps that we can develop a model using the second form of Eq. [A-14]. Inserting Eqs

Litster, Shawn

251

Computational modelling of transport phenomena in high energy materials processing application: large eddy simulation and parallelisation  

Science Journals Connector (OSTI)

A comprehensive three-dimensional numerical model is presented in order to address the coupled turbulent momentum, heat and species transport during molten metal-pool convection in association with continuous evolution of solid-liquid interface typically encountered in high energy materials processing applications. The turbulent aspect is handled by a large eddy simulation (LES) model and the phase changing phenomena is taken care of by a modified enthalpy-porosity technique. The proposed finite volume based LES model is subsequently parallelised for effective computational economy. To demonstrate the effectiveness of the present model, a systematic analysis is subsequently carried out to simulate a typical high power laser surface alloying process, where the effects of turbulent transport can actually be realised.

Dipankar Chatterjee

2011-01-01T23:59:59.000Z

252

Transport of Molecular Motor Dimers in Burnt-Bridge Models  

E-Print Network (OSTI)

Dynamics of molecular motor dimers, consisting of rigidly bound particles that move along two parallel lattices and interact with underlying molecular tracks, is investigated theoretically by analyzing discrete-state stochastic continuous-time burnt-bridge models. In these models the motion of molecular motors is viewed as a random walk along the lattices with periodically distributed weak links (bridges). When the particle crosses the weak link it can be destroyed with a probability $p$, driving the molecular motor motion in one direction. Dynamic properties and effective generated forces of dimer molecular motors are calculated exactly as a function of a concentration of bridges $c$ and burning probability $p$ and compared with properties of the monomer motors. It is found that the ratio of the velocities of the dimer and the monomer can never exceed 2, while the dispersions of the dimer and the monomer are not very different. The relative effective generated force of the dimer (as compared to the monomer) also cannot be larger than 2 for most sets of parameters. However, a very large force can be produced by the dimer in the special case of $c=1/2$ for non-zero shift between the lattices. Our calculations do not show the significant increase in the force generated by collagenase motor proteins in real biological systems as predicted by previous computational studies. The observed behavior of dimer molecular motors is discussed by considering in detail the particle dynamics near burnt bridges.

Alexander Yu. Morozov; Anatoly B. Kolomeisky

2007-09-21T23:59:59.000Z

253

GREET 1.0 -- Transportation fuel cycles model: Methodology and use  

SciTech Connect

This report documents the development and use of the Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) model. The model, developed in a spreadsheet format, estimates the full fuel-cycle emissions and energy use associated with various transportation fuels for light-duty vehicles. The model calculates fuel-cycle emissions of five criteria pollutants (volatile organic compounds, Co, NOx, SOx, and particulate matter measuring 10 microns or less) and three greenhouse gases (carbon dioxide, methane, and nitrous oxide). The model also calculates the total fuel-cycle energy consumption, fossil fuel consumption, and petroleum consumption using various transportation fuels. The GREET model includes 17 fuel cycles: petroleum to conventional gasoline, reformulated gasoline, clean diesel, liquefied petroleum gas, and electricity via residual oil; natural gas to compressed natural gas, liquefied petroleum gas, methanol, hydrogen, and electricity; coal to electricity; uranium to electricity; renewable energy (hydropower, solar energy, and wind) to electricity; corn, woody biomass, and herbaceous biomass to ethanol; and landfill gases to methanol. This report presents fuel-cycle energy use and emissions for a 2000 model-year car powered by each of the fuels that are produced from the primary energy sources considered in the study.

Wang, M.Q.

1996-06-01T23:59:59.000Z

254

Uncertainty Analysis Framework - Hanford Site-Wide Groundwater Flow and Transport Model  

SciTech Connect

Pacific Northwest National Laboratory (PNNL) embarked on a new initiative to strengthen the technical defensibility of the predictions being made with a site-wide groundwater flow and transport model at the U.S. Department of Energy Hanford Site in southeastern Washington State. In FY 2000, the focus of the initiative was on the characterization of major uncertainties in the current conceptual model that would affect model predictions. The long-term goals of the initiative are the development and implementation of an uncertainty estimation methodology in future assessments and analyses using the site-wide model. This report focuses on the development and implementation of an uncertainty analysis framework.

Cole, Charles R.; Bergeron, Marcel P.; Murray, Christopher J.; Thorne, Paul D.; Wurstner, Signe K.; Rogers, Phillip M.

2001-11-09T23:59:59.000Z

255

Numerical modeling of mixed sediment resuspension, transport, and deposition during the March 1998 episodic events in southern Lake  

E-Print Network (OSTI)

Numerical modeling of mixed sediment resuspension, transport, and deposition during the March 1998 2006; published 17 February 2007. [1] A two-dimensional sediment transport model capable of simulating sediment resuspension of mixed (cohesive plus noncohesive) sediment is developed and applied

256

A critical view on transport and entanglement in models of photosynthesis  

E-Print Network (OSTI)

Quantum effects in biological light-harvesting molecules, such as quantum coherence of excitonic states and entanglement have recently gained much attention. We observe a certain discrepancy between the original experimental work and several theoretical treatments of coherent excitation transport in light-harvesting molecules. Contrary to what is generally stated, we argue that entanglement in such molecules is generally not equivalent to the presence of coherence but mostly introduced by initial assumptions underlying the models, and that entanglement, as opposite to coherence, seems to play no role in the transport efficiency.

Tiersch, Markus; Briegel, Hans J

2011-01-01T23:59:59.000Z

257

Evaluation of C-14 as a natural tracer for injected fluids at theAidlin sector of The Geysers geothermal system through modeling ofmineral-water-gas Reactions  

SciTech Connect

A reactive-transport model for 14C was developed to test its applicability to the Aidlin geothermal system. Using TOUGHREACT, we developed a 1-D grid to evaluate the effects of water injection and subsequent water-rock-gas interaction on the compositions of the produced fluids. A dual-permeability model of the fracture-matrix system was used to describe reaction-transport processes in which the permeability of the fractures is many orders of magnitude higher than that of the rock matrix. The geochemical system included the principal minerals (K-feldspar, plagioclase, calcite, silica polymorphs) of the metagraywackes that comprise the geothermal reservoir rocks. Initial simulation results predict that the gas-phase CO2 in the reservoir will become more enriched in 14C as air-equilibrated injectate water (with a modern carbon signature) is incorporated into the system, and that these changes will precede accompanying decreases in reservoir temperature. The effects of injection on 14C in the rock matrix will be lessened somewhat because of the dissolution of matrix calcite with ''dead'' carbon.

Dobson, Patrick; Sonnenthal, Eric; Lewicki, Jennifer; Kennedy, Mack

2006-06-01T23:59:59.000Z

258

Transport Modeling of Membrane Extraction of Chlorinated Hydrocarbon from Water for Ion Mobility Spectrometry  

SciTech Connect

Membrane-extraction Ion Mobility Spectrometry (ME-IMS) is a feasible technique for the continuous monitoring of chlorinated hydrocarbons in water. This work studies theoretically the time-dependent characteristics of sampling and detection of trichloroethylene (TCE). The sampling is configured so that aqueous contaminants permeate through a hollow polydimethylsiloxane (PDMS) membrane and are carried away by a transport gas flowing through the membrane tube into IMS analyzer. The theoretical study is based on a two-dimensional transient fluid flow and mass transport model. The model describes the TCE mixing in the water, permeation through the membrane layer, and convective diffusion in the air flow inside membrane tube. The effect of various transport gas flow rates on temporal profiles of IMS signal intensity is investigated. The results show that fast time response and high transport yield can be achieved for ME-IMS by controlling the flow rate in the extraction membrane tube. These modeled time-response profiles are important for determining duty cycles of field-deployable sensors for monitoring chlorinated hydrocarbons in water.

Zhang, Wei [ORNL; Du, Yongzhai [ORNL; Feng, Zhili [ORNL; Xu, Jun [ORNL

2010-01-01T23:59:59.000Z

259

BLT-EC (Breach, Leach Transport, and Equilibrium Chemistry), a finite-element model for assessing the release of radionuclides from low-level waste disposal units: Background, theory, and model description  

SciTech Connect

Performance assessment models typically account for the processes of sorption and dissolution-precipitation by using an empirical distribution coefficient, commonly referred to as K{sub d} that combines the effects of all chemical reactions between solid and aqueous phases. In recent years, however, there has been an increasing awareness that performance assessments based solely on empirically based K{sub d} models may be incomplete, particularly for applications involving radionuclides having sorption and solubility properties that are sensitive to variations in the in-situ chemical environment. To accommodate variations in the in-situ chemical environment, and to assess its impact on radionuclide mobility, it is necessary to model radionuclide release, transport, and chemical processes in a coupled fashion. This modeling has been done and incorporated into the two-dimensional, finite-element, computer code BLT-EC (Breach, Leach, Transport, Equilibrium Chemistry). BLT-EC is capable of predicting container degradation, waste-form leaching, and advective-dispersive, multispecies, solute transport. BLT-EC accounts for retardation directly by modeling the chemical processes of complexation, sorption, dissolution-precipitation, ion-exchange, and oxidation-reduction reactions. In this report we: (1) present a detailed description of the various physical and chemical processes that control the release and migration of radionuclides from shallow land LLW disposal facilities; (2) formulate the mathematical models that represent these processes; (3) outline how these models are incorporated and implemented in BLT-EC; and (4) demonstrate the application of BLT-EC on a set of example problems.

MacKinnon, R.J.; Sullivan, T.M. [Brookhaven National Lab., Upton, NY (United States); Simonson, S.A. [Massachusetts Inst. of Technology, Cambridge, MA (United States); Suen, C.J. [California State Univ., Fresno, CA (United States)

1995-08-01T23:59:59.000Z

260

Pore-Scale Modeling of Two-Phase Transport in Polymer Electrolyte Fuel Cells - Progress and Perspective  

SciTech Connect

Recent years have witnessed an explosion of research and development efforts in the area of polymer electrolyte fuel cells (PEFC), perceived as the next generation clean energy source for automotive, portable and stationary applications. Despite significant progress, a pivotal performance/durability limitation in PEFCs centers on two-phase transport and mass transport loss originating from suboptimal liquid water transport and flooding phenomena. Liquid water blocks the porous pathways in the gas diffusion layer (GDL) and the catalyst layer (CL), thus hindering oxygen transport from the flow field to the electrochemically actives sites in the catalyst layer. Different approaches have been examined to model the underlying transport mechanisms in the PEFC with different levels of complexities. Due to the macroscopic nature, these two-phase models fail to resolve the underlying structural influence on the transport and performance. Mesoscopic modeling at the pore-scale offers great promise in elucidating the underlying structure-transport-performance interlinks in the PEFC porous components. In this article, a systematic review of the recent progress and prospects of pore-scale modeling in the context of two-phase transport in the PEFC is presented. Specifically, the efficacy of lattice Boltzmann (LB), pore morphology (PM) and pore network (PN) models coupled with realistic delineation of microstructures in fostering enhanced insight into the underlying liquid water transport in the PEFC GDL and CL is highlighted.

Mukherjee, Partha P [ORNL

2010-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "reaction transport model" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Carlsbad Area Office unveils full-scale model of new WIPP waste transportation cask  

NLE Websites -- All DOE Office Websites (Extended Search)

Carlsbad Area Office Unveils Full-Scale Model Carlsbad Area Office Unveils Full-Scale Model Of New WIPP Waste Transportation Cask CARLSBAD, N.M., February 23, 2000 - The U.S. Department of Energy's (DOE) Carlsbad Area Office today unveiled a full-scale model of its newest waste transportation cask, the RH-72B, during a ceremony at the local DOE offices. "This is another milestone for the Department of Energy," said Dr. Inés Triay, Manager of the Carlsbad Area Office, describing the importance of the new container for those attending the ceremony. "After we receive approval from the U.S. Nuclear Regulatory Commission (NRC), we plan to add the RH-72B to our fleet, which will help the Department meet its continuing mission to remove transuranic waste from the accessible environment and

262

Volume exclusion and elasticity driven directional transport: an alternative model for bacterium motility  

E-Print Network (OSTI)

On the basis of a model we capture the role of strong attractive interaction in suppressing the rotational degrees of freedom of the system and volume exclusion in keeping microscopic symmetry-breaking intact to result in super-diffusive transport of small systems in a thermal atmosphere over a large time scale. Our results, characterize such systems on the basis of having a super-diffusive intermediate regime in between a very small and large time scales of diffusive regimes. Although, the Brownian ratchet model fails to account for the origin of motility in actin polymerization propelled directional motion of bacterium like Listeria Monocytogene (LM) and similar bio-mimetic systems due to the presence of strong attractive forces, our model can account for the origin of directional transport in such systems on the basis of the same interactions.

A. Bhattacharyay

2009-05-14T23:59:59.000Z

263

Volume exclusion and elasticity driven directional transport: an alternative model for bacterium motility  

E-Print Network (OSTI)

On the basis of a model we capture the role of strong attractive interaction in suppressing the rotational degrees of freedom of the system and volume exclusion in keeping microscopic symmetry-breaking intact to result in super-diffusive transport of small systems in a thermal atmosphere over a large time scale. Our results, characterize such systems on the basis of having a super-diffusive intermediate regime in between a very small and large time scales of diffusive regimes. Although, the Brownian ratchet model fails to account for the origin of motility in actin polymerization propelled directional motion of bacterium like Listeria Monocytogene (LM) and similar bio-mimetic systems due to the presence of strong attractive forces, our model can account for the origin of directional transport in such systems on the basis of the same interactions.

Bhattacharyay, A

2009-01-01T23:59:59.000Z

264

Assimilation of satellite images into a sediment transport model of Lake Michigan.  

SciTech Connect

In this paper we develop and examine several schemes for combining daily images obtained from the Sea-viewing Wide Field Spectrometer (SeaWiFS) with a two-dimensional sediment transport model of Lake Michigan. We consider two data assimilation methods, direct insertion and a kriging-based approach, and perform a forecasting study focused on a 2-month period in spring 1998 when a large storm caused substantial amounts of sediment resuspension and horizontal sediment transport in the lake. By beginning with the simplest possible forecast method and sequentially adding complexity we are able to assess the improvements offered by combining the satellite data with the numerical model. In our application, we find that data assimilation schemes that include both the data and the lake dynamics improve forecast root mean square error by 40% over purely model-based approaches and by 20% over purely data-based approaches.

Stroud, J.; Lesht, B.; Beletsky, D.; Stein, M.; Univ. of Pennsylvania; NOAA; Univ. of Michigan; Univ. of Chicago

2009-01-01T23:59:59.000Z

265

Modeling the global freight transportation system: a multi-level modeling perspective  

Science Journals Connector (OSTI)

The interconnectedness of different actors in the global freight transportation industry has rendered such a system as a large complex system where different sub-systems are interrelated. On such a system, policy-related- exploratory analyses which have ...

Ronald Apriliyanto Halim; Lorant A. Tavasszy; Mamadou D. Seck

2012-12-01T23:59:59.000Z

266

MONTE CARLO SIMULATION MODEL OF ENERGETIC PROTON TRANSPORT THROUGH SELF-GENERATED ALFVEN WAVES  

SciTech Connect

A new Monte Carlo simulation model for the transport of energetic protons through self-generated Alfven waves is presented. The key point of the model is that, unlike the previous ones, it employs the full form (i.e., includes the dependence on the pitch-angle cosine) of the resonance condition governing the scattering of particles off Alfven waves-the process that approximates the wave-particle interactions in the framework of quasilinear theory. This allows us to model the wave-particle interactions in weak turbulence more adequately, in particular, to implement anisotropic particle scattering instead of isotropic scattering, which the previous Monte Carlo models were based on. The developed model is applied to study the transport of flare-accelerated protons in an open magnetic flux tube. Simulation results for the transport of monoenergetic protons through the spectrum of Alfven waves reveal that the anisotropic scattering leads to spatially more distributed wave growth than isotropic scattering. This result can have important implications for diffusive shock acceleration, e.g., affect the scattering mean free path of the accelerated particles in and the size of the foreshock region.

Afanasiev, A.; Vainio, R., E-mail: alexandr.afanasiev@helsinki.fi [Department of Physics, University of Helsinki (Finland)

2013-08-15T23:59:59.000Z

267

FINAL REPORT:Observation and Simulations of Transport of Molecules and Ions Across Model Membranes  

SciTech Connect

During the this new grant we developed a robust methodology for investigating a wide range of properties of phospho-lipid bilayers. The approach developed is unique because despite using periodic boundary conditions, we can simulate an entire experiment or process in detail. For example, we can follow the entire permeation process in a lipid-membrane. This includes transport from the bulk aqueous phase to the lipid surface; permeation into the lipid; transport inside the lipid; and transport out of the lipid to the bulk aqueous phase again. We studied the transport of small gases in both the lipid itself and in model protein channels. In addition, we have examined the transport of nanocrystals through the lipid membrane, with the main goal of understanding the mechanical behavior of lipids under stress including water and ion leakage and lipid flip flop. Finally we have also examined in detail the deformation of lipids when under the influence of external fields, both mechanical and electrostatic (currently in progress). The important observations and conclusions from our studies are described in the main text of the report

MURAD, SOHAIL [University of Illinois at Chicago] [University of Illinois at Chicago; JAMESON, CYNTHIA J [University of Illinois at Chicago] [University of Illinois at Chicago

2013-10-22T23:59:59.000Z

268

Monomer-dimer reaction model with asymmetric adsorption of monomer and dimer on the catalyst surface  

Science Journals Connector (OSTI)

The irreversible kinetics of the Ziff-Gulari-Barshad model in the presence of inhomogeneity on a catalyst surface is investigated by means of Monte Carlo simulation. We assume that only part of catalyst surface sites are active for surface catalytic reaction and randomly distributed on the catalyst surface. The adsorption of a O2 molecule is permitted if one site of a nearest-neighbor vacant pair is active. CO can adsorb on all vacant sites, but the adsorption probability is p(p<1) if the site is not active. In our modified model, the O-passivated phase disappears and the continuous phase transition between the O passivated and the reactive state is eliminated. We also find that the transition between the CO passivated and the reactive state is continuous if the concentration of the active sites is small, and it becomes discontinuous with increasing concentrations of active sites. Furthermore, it is shown that a hysteresis loop exists whether the CO-passivated transition is continuous or discontinuous. Our simulation results are in good agreement with many relevant experimental results and may provide an alternative explanation for the experimental observations.

Da-yin Hua and Yu-qiang Ma

2001-10-17T23:59:59.000Z

269

The Role of Dispersion in Radionuclide Transport - Data and Modeling Requirements: Revision No. 1  

SciTech Connect

This document is the collaborative effort of the members of an ad hoc subcommittee of the Underground Test Area Project Technical Working Group. This subcommittee was to answer questions and concerns raised by the Nevada Division of Environmental Protection to the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office, regarding Pahute Mesa Corrective Action Units (CAUs) 101 and 102. The document attempts to synthesize the combined comments made by each member of this subcommittee into insights made in the role of dispersion in radionuclide transport data and modeling. Dispersion is one of many processes that control the concentration of radionuclides in groundwater beneath the Nevada Test Site where CAUs 101 and 102 are located. In order to understand the role of dispersion in radionuclide transport, there is a critical need for CAU- or site-specific data related to transport parameters which is currently lacking, particularly in the case of Western a nd Central Pahute Mesa. The purpose of this technical basis document is to: (1) define dispersion and its role in contaminant transport, (2) present a synopsis of field-scale dispersion measurements, (3) provide a literature review of theories to explain field-scale dispersion, (4) suggest approaches to account for dispersion in CAU-scale radionuclide modeling, and (5) to determine if additional dispersion measurements should be made at this time.

Stoller-Navarro Joint Venture

2004-02-01T23:59:59.000Z

270

Peristaltic Transport of a Rheological Fluid: Model for Movement of Food Bolus Through Esophagus  

E-Print Network (OSTI)

Fluid mechanical peristaltic transport through esophagus has been of concern in the paper. A mathematical model has been developed with an aim to study the peristaltic transport of a rheological fluid for arbitrary wave shapes and tube lengths. The Ostwald-de Waele power law of viscous fluid is considered here to depict the non-Newtonian behaviour of the fluid. The model is formulated and analyzed with the specific aim of exploring some important information concerning the movement of food bolus through the esophagus. The analysis has been carried out by using lubrication theory. The study is particularly suitable for cases where the Reynolds number is small. The esophagus is treated as a circular tube through which the transport of food bolus takes places by periodic contraction of the esophageal wall. Variation of different variables concerned with the transport phenomena such as pressure, flow velocity, particle trajectory and reflux are investigated for a single wave as well as for a train of periodic per...

Misra, J C

2011-01-01T23:59:59.000Z

271

Conceptual model for regional radionuclide transport from a basalt repository site. Final draft, technical memorandum  

SciTech Connect

This technical memorandum was prepared to: (1) describe a typical basalt radionuclide repository site, (2) describe geologic and hydrologic processes associated with regional radionuclide transport in basalts, (3) define the parameters required to model regional radionuclide transport from a basalt repository site, and (4) develop a ''conceptual model'' of radionuclide transport from a basalt repository site. In a general hydrological sense, basalts may be described as layered sequences of aquifers and aquitards. The Columbia River Basalt, centered near the semi-arid Pasco Basin, is considered by many to be typical basalt repository host rock. Detailed description of the flow system including flow velocities with high-low hydraulic conductivity sequences are not possible with existing data. However, according to theory, waste-transport routes are ultimately towards the Columbia River and the lengths of flow paths from the repository to the biosphere may be relatively short. There are many physical, chemical, thermal, and nuclear processes with associated parameters that together determine the possible pattern of radionuclide migration in basalts and surrounding formations. Brief process descriptions and associated parameter lists are provided. Emphasis has been placed on the use of the distribution coefficient in simulating ion exchange. The use of the distribution coefficient approach is limited because it takes into account only relatively fast mass transfer processes. In general, knowledge of hydrogeochemical processes is primitive.

Walton, W.C.; Voorhees, M.L.; Prickett, T.A.

1980-05-23T23:59:59.000Z

272

Modeling the Effect of Sedimentation on Cesium Transport in Fourmile Branch  

SciTech Connect

The major mechanisms of radioactive material transport and fate in surface water are (1) sources, (2) dilution, advection and dispersion of radionuclides by flow and surface waves, (3) radionuclide decay, and (4) interaction between sediment and radionuclides. STREAM II, an aqueous transport module of the Savannah River Site emergency response WIND system, accounts for the source term, and the effects of dilution, advection and dispersion. Although the model has the capability to account for nuclear decay, due to the short time interval of interest for emergency response, the effect of nuclear decay is very small and so it is not employed. The interactions between the sediment and radionuclides are controlled by the flow conditions and physical and chemical characteristics of the radionuclides and the sediment constituents. The STREAM II version used in emergency response does not model the effects of sediment deposition/resuspension to minimize computing time. This study estimates the effects of sediment deposition/resuspension on radionuclide aqueous transport. For radionuclides that adsorb onto suspended sediment, the omission of deposition/resuspension effects overestimates the downstream radionuclide peak concentration and is therefore conservative. For the case of cesium transport in the Fourmile Branch, the calculated reduction in peak concentration as the cesium is transported downstream is greater with sediment deposition modeled than without. For example, including the effects of sediment deposition/resuspension in the STREAM II calculation results in a 72 percent reduction in the downstream (5075 meters downstream from H-Area) peak cesium concentration. It is important to note that the high partition coefficient appropriate for cesium enhances the importance of sediment deposition/resuspension; the reduction in the calculated peak concentration would be less for radioisotopes with lower partition coefficients.

Chen, K.F.

2001-02-22T23:59:59.000Z

273

Directed transport in equilibrium : analysis of the dimer model with inertial terms  

E-Print Network (OSTI)

We have previously shown an analysis of our dimer model in the over-damped regime to show directed transport in equilibrium. Here we analyze the full model with inertial terms present to establish the same result. First we derive the Fokker-Planck equation for the system following a Galilean transformation to show that a uniformly translating equilibrium distribution is possible. Then, we find out the velocity selection for the centre of mass motion using that distribution on our model. We suggest generalization of our calculations for soft collision potentials and indicate to interesting situation with possibility of oscillatory non-equilibrium state within equilibrium.

A. Bhattacharyay

2011-08-15T23:59:59.000Z

274

The modelling of biochemical-thermal coupling effect on gas generation and transport in MSW landfill  

Science Journals Connector (OSTI)

The landfill gas generation was investigated based on the theories of the thermodynamics, microbial dynamics and chemical dynamics. The coupling model was developed for describing the gas transport and heat release. And the relationship between the gas generation rate and the temperature was proposed. The parameters in the gas generation model were obtained by bioreactor test in order to evaluate the volume of gas production of the Erfeishan landfill in China. The simulation results shown that the operating life of the landfill will be overestimated if the model does not consider the thermal effect during degradation of the solid substrate.

Liu Lei; Liang Bing; Xue Qiang; Zhao Ying; Yang Chun

2011-01-01T23:59:59.000Z

275

Activity based travel demand models as a tool for evaluating sustainable transportation policies  

Science Journals Connector (OSTI)

India is in the course of an economic transition. The economic growth nurtured the life in the cities and cities have become a major livelihood destination for everyone. This migration of people contributed to the increased urbanization of Indian cities. The booming economy fostered the well-being and shaped the lifestyle of people in such a way that the dependency on private vehicle has become an unavoidable affair. Along with population growth, the increased vehicle ownership gave rise to overall spurt in travel demand. But the supply side lagged behind the demand adding to many of the transport related externalities such as accidents, congestion, pollution, inequity etc. The importance of sustainability is understood in the current urban transport scenario leading to the development and promotion of sustainable transport polices. The core agenda of these polices is to target the travel behavior of people and change the way they travel by creating a different travel environment. However, the impacts of many such policies are either unknown or complex. Hence, before adopting and implementing such policies, it is important for the decision makers to be aware of the impacts of them. The role of travel demand models comes here as they predict the future travel demand under different policy scenarios. This paper reviews the ability of travel demand models applied in India in analyzing the sustainable transport policies. The study found that the conventional model system in India, which is trip based four step aggregate methodology, is inadequate in analyzing the sustainable transport policies. A review of alternative approach, known as activity based travel demand modeling found that they are capable of handling such policies better than conventional models and are assistive to the decision makers in arriving at right mix of polices specific to the situations. Since there is no operational activity based travel demand model system developed in India, the study at the end envisaged a conceptual framework of an integrated activity based travel demand model based on the requirements identified from the review. This can potentially replace the existing travel demand models and can be used for planning applications once the modification & validation have been done according to the existing activity-travel behavior of individuals.

Manoj Malayath; Ashish Verma

2013-01-01T23:59:59.000Z

276

Comparative study of micromixing models in transported scalar PDF simulations of turbulent nonpremixed bluff body flames  

SciTech Connect

Numerical simulation results are presented for turbulent jet diffusion flames with various levels of turbulence-chemistry interaction, stabilized behind a bluff body (Sydney Flames HM1-3). Interaction between turbulence and combustion is modeled with the transported joint-scalar PDF approach. The mass density function transport equation is solved in a Lagrangian manner. A second-moment-closure turbulence model is applied to obtain accurate mean flow and turbulent mixing fields. The behavior of two micromixing models is discussed: the Euclidean minimum spanning tree model and the modified Curl coalescence dispersion model. The impact of the micromixing model choice on the results in physical space is small, although some influence becomes visible as the amount of local extinction increases. Scatter plots and profiles of conditional means and variances of thermochemical quantities, conditioned on the mixture fraction, are discussed both within and downstream of the recirculation region. A distinction is made between local extinction and incomplete combustion, based on the CO species mass fraction. The differences in qualitative behavior between the micromixing models are explained and quantitative comparison to experimental data is made. (author)

Merci, Bart [Department of Flow, Heat and Combustion Mechanics, Ghent University-UGent, Ghent (Belgium); Roekaerts, Dirk [Department of Multi-Scale Physics, Delft University of Technology, Delft (Netherlands); Naud, Bertrand [CIEMAT, Madrid (Spain); Pope, Stephen B. [Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY (United States)

2006-07-15T23:59:59.000Z

277

TransCom model simulations of CH? and related species: linking transport, surface flux and chemical loss with CH? variability in the troposphere and lower stratosphere  

E-Print Network (OSTI)

A chemistry-transport model (CTM) intercomparison experiment (TransCom-CH?) has been designed to investigate the roles of surface emissions, transport and chemical loss in simulating the global methane distribution. Model ...

Patra, P. K.

278

Nanolithographic Fabrication and Heterogeneous Reaction Studies of Two-Dimensional Platinum Model Catalyst Systems  

E-Print Network (OSTI)

and truly tune the catalyst to the reaction. References 1.Gavriilidis, A. Varma, Catalyst Design, Cambridge UniversityStructure of Metallic Catalysts, Academic Press, London,

Contreras, A.M.

2006-01-01T23:59:59.000Z

279

Comparison of palladium and platinum Water Gas Shift reaction kinetics using density functional theory models.  

E-Print Network (OSTI)

?? The Water Gas Shift (WGS) reaction can be either thermodynamically or kinetically limited, depending on process conditions. Improved catalysts are of particular interest at (more)

Clay, John P.

2014-01-01T23:59:59.000Z

280

Model for primary charge separation in reaction centers of photosynthetic bacteria  

Science Journals Connector (OSTI)

...Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139. | Journal Article...reaction/storage of solar energy) RICHARD FRIESNERf...Science and Engineering, Massachusetts Institute of Technology...

Richard Friesner; Reiner Wertheimer

1982-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "reaction transport model" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

A multi-model assessment of pollution transport to the Arctic  

SciTech Connect

We examine the response of Arctic gas and aerosol concentrations to perturbations in pollutant emissions from Europe, East and South Asia, and North America using results from a coordinated model intercomparison. These sensitivities to regional emissions (mixing ratio change per unit emission) vary widely across models and species. Intermodel differences are systematic, however, so that the relative importance of different regions is robust. North America contributes the most to Arctic ozone pollution. For aerosols and CO, European emissions dominate at the Arctic surface but East Asian emissions become progressively more important with altitude, and are dominant in the upper troposphere. Sensitivities show strong seasonality: surface sensitivities typically maximize during boreal winter for European and during spring for East Asian and North American emissions. Mid-tropospheric sensitivities, however, nearly always maximize during spring or summer for all regions. Deposition of black carbon (BC) onto Greenland is most sensitive to North American emissions. North America and Europe each contribute {approx}40% of total BC deposition to Greenland, with {approx}20% from East Asia. Elsewhere in the Arctic, both sensitivity and total BC deposition are dominated by European emissions. Model diversity for aerosols is especially large, resulting primarily from differences in aerosol physical and chemical processing (including removal). Comparison of modeled aerosol concentrations with observations indicates problems in the models, and perhaps, interpretation of the measurements. For gas phase pollutants such as CO and O{sub 3}, which are relatively well-simulated, the processes contributing most to uncertainties depend on the source region and altitude examined. Uncertainties in the Arctic surface CO response to emissions perturbations are dominated by emissions for East Asian sources, while uncertainties in transport, emissions, and oxidation are comparable for European and North American sources. At higher levels, model-to-model variations in transport and oxidation are most important. Differences in photochemistry appear to play the largest role in the intermodel variations in Arctic ozone sensitivity, though transport also contributes substantially in the mid-troposphere.

Shindell, D T; Chin, M; Dentener, F; Doherty, R M; Faluvegi, G; Fiore, A M; Hess, P; Koch, D M; MacKenzie, I A; Sanderson, M G; Schultz, M G; Schulz, M; Stevenson, D S; Teich, H; Textor, C; Wild, O; Bergmann, D J; Bey, I; Bian, H; Cuvelier, C; Duncan, B N; Folberth, G; Horowitz, L W; Jonson, J; Kaminski, J W; Marmer, E; Park, R; Pringle, K J; Schroeder, S; Szopa, S; Takemura, T; Zeng, G; Keating, T J; Zuber, A

2008-03-13T23:59:59.000Z

282

Groundwater transport modeling of constituents originating from the Burial Grounds Complex  

SciTech Connect

The Savannah River Site (SRS), operates a number of sites for the land disposal of various leachable radionuclide, organic, and inorganic wastes. Located within the General Separations Area (GSA) of SRS are the Low Level Radioactive Waste Disposal Facility (LLRWDF) and the Old Burial Ground (OBG). A portion of the LLRWDF has been designated as the Mixed Waste Management Facility (MWMF). The OBG began receiving waste in 1952 and was closed in 1974. Various wastes, including transuranic, intermediate and low level beta-gamma, and solvents, were received during this period of operation. In 1969, prior to the closing of the OBG, a portion of the MWMF/LLRWDF (the MWMF) began receiving waste. GeoTrans, Inc. was contracted by WSRC to conduct a numerical modeling study to assess groundwater flow and contaminant transport in the vicinity of the MWMF in support of an Alternate Concentration Limits demonstration for the Part B permit. The project was divided into two phases: development of a groundwater flow model of the hydrogeologic system underlying the MWMF which includes the entire GSA, and development of a solute transport model to assess migration of 19 designated constituents of concern (COCs) over a period 30 years into the future. The first phase was completed in May of 1992 and the results documented in GeoTrans (1992). That report serves as the companion volume to the present contaminant transport modeling report. The transport study is intended to develop predictions of concentration and mass flux of the 19 COCs at downgradient exposure points over the 30 year period of interest. These results are to be used in human health and ecological risk assessments which are also being performed in support of the Part B permit.

Andersen, P.F.; Shupe, M.G.; Spalding, C.P. [GeoTrans, Inc., Sterling, VA (US)

1992-10-30T23:59:59.000Z

283

Comparison of one-, two-, and three-dimensional models for mass transport of radionuclides  

SciTech Connect

This technical memorandum compares one-, two-, and three-dimensional models for studying regional mass transport of radionuclides in groundwater associated with deep repository disposal of high-level radioactive wastes. In addition, this report outlines the general conditions for which a one- or two-dimensional model could be used as an alternate to a three-dimensional model analysis. The investigation includes a review of analytical and numerical models in addition to consideration of such conditions as rock and fluid heterogeneity, anisotropy, boundary and initial conditions, and various geometric shapes of repository sources and sinks. Based upon current hydrologic practice, each review is taken separately and discussed to the extent that the researcher can match his problem conditions with the minimum number of model dimensions necessary for an accurate solution.

Prickett, T.A.; Voorhees, M.L.; Herzog, B.L.

1980-02-01T23:59:59.000Z

284

Determining the Effect of Concerted Elimination Reactions in the Pyrolysis of Lignin Using Model Compounds  

SciTech Connect

Lignin pyrolysis is a significant impediment in forming liquid fuel from biomass. Lignin pyrolyzes at a higher temperature than other biomass components (ie cellulose, hemicellulose) and tends to form radicals which lead to cross linking and ultimately char formation. A primary step in advances biomass-to-fuel technology will be to discover mechanisms that can disassemble lignin at lower temperatures and depolymerize lignin into more stable products. We have investigated the thermochemistry of the various inter-linkage units found in lignin ({beta}-O4, {alpha}-O4, {beta}-{beta}, {beta}-O5, etc) using electronic structure calculations at the M06-2x/6-311++G(d,p) on a series of dimer model compounds. In addition to the usually-assumed bond homolysis reactions, we have investigated a variety of concerted elimination pathways that will tend to produce closed-shell stable products. Such a bottom-up approach could aid in the targeted development of catalysts that produce more desirable products under less severe reactor conditions.

Robichaud, D.; Clark, J.; Nimlos, M.

2012-01-01T23:59:59.000Z

285

Area-preserving maps models of gyroaveraged EB chaotic transport  

SciTech Connect

Discrete maps have been extensively used to model 2-dimensional chaotic transport in plasmas and fluids. Here we focus on area-preserving maps describing finite Larmor radius (FLR) effects on E??B chaotic transport in magnetized plasmas with zonal flows perturbed by electrostatic drift waves. FLR effects are included by gyro-averaging the Hamiltonians of the maps which, depending on the zonal flow profile, can have monotonic or non-monotonic frequencies. In the limit of zero Larmor radius, the monotonic frequency map reduces to the standard Chirikov-Taylor map, and in the case of non-monotonic frequency, the map reduces to the standard nontwist map. We show that in both cases FLR leads to chaos suppression, changes in the stability of fixed points, and robustness of transport barriers. FLR effects are also responsible for changes in the phase space topology and zonal flow bifurcations. Dynamical systems methods based on the counting of recurrences times are used to quantify the dependence on the Larmor radius of the threshold for the destruction of transport barriers.

Fonseca, J. D. da, E-mail: jfonseca@if.usp.br; Caldas, I. L., E-mail: ibere@if.usp.br [Institute of Physics, University of So Paulo, So Paulo, SP 5315-970 (Brazil); Castillo-Negrete, D. del, E-mail: delcastillod@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8071 (United States)

2014-09-15T23:59:59.000Z

286

Area-preserving maps models of gyro-averaged ${\\bf E} \\times {\\bf B}$ chaotic transport  

E-Print Network (OSTI)

Discrete maps have been extensively used to model 2-dimensional chaotic transport in plasmas and fluids. Here we focus on area-preserving maps describing finite Larmor radius (FLR) effects on ${\\bf E} \\times {\\bf B}$ chaotic transport in magnetized plasmas with zonal flows perturbed by electrostatic drift waves. FLR effects are included by gyro-averaging the Hamiltonians of the maps which, depending on the zonal flow profile, can have monotonic or non-monotonic frequencies. In the limit of zero Larmor radius, the monotonic frequency map reduces to the standard Chirikov-Taylor map, and, in the case of non-monotonic frequency, the map reduces to the standard nontwist map. We show that in both cases FLR leads to chaos suppression, changes in the stability of fixed points, and robustness of transport barriers. FLR effects are also responsible for changes in the phase space topology and zonal flow bifurcations. Dynamical systems methods based on recurrence time statistics are used to quantify the dependence on the Larmor radius of the threshold for the destruction of transport barriers.

J. D. da Fonseca; D. del-Castillo-Negrete; I. L. Caldas

2014-09-10T23:59:59.000Z

287

A critical view on transport and entanglement in models of photosynthesis  

E-Print Network (OSTI)

We revisit critically the recent claims, inspired by quantum optics and quantum information, that there is entanglement in the biological pigment protein complexes, and that it is responsible for the high transport efficiency. While unexpectedly long coherence times were experimentally demonstrated, the existence of entanglement is, at the moment, a purely theoretical conjecture; it is this conjecture that we analyze. As demonstrated by a toy model, a similar transport phenomenology can be obtained without generating entanglement. Furthermore, we also argue that even if entanglement does exist, it is purely incidental and seems to plays no essential role for the transport efficiency. We emphasize that our paper is not a proof that entanglement does not exist in light-harvesting complexes - this would require a knowledge of the system and its parameters well beyond the state of the art. Rather, we present a counter-example to the recent claims of entanglement, showing that the arguments, as they stand at the moment, are not sufficiently justified and hence cannot be taken as proof for the existence of entanglement, let alone of its essential role, in the excitation transport.

Markus Tiersch; Sandu Popescu; Hans J. Briegel

2011-04-19T23:59:59.000Z

288

Final Report Coupling in silico microbial models with reactive transport models to predict the fate of contaminants in the subsurface.  

SciTech Connect

This project successfully accomplished its goal of coupling genome-scale metabolic models with hydrological and geochemical models to predict the activity of subsurface microorganisms during uranium bioremediation. Furthermore, it was demonstrated how this modeling approach can be used to develop new strategies to optimize bioremediation. The approach of coupling genome-scale metabolic models with reactive transport modeling is now well enough established that it has been adopted by other DOE investigators studying uranium bioremediation. Furthermore, the basic principles developed during our studies will be applicable to much broader investigations of microbial activities, not only for other types of bioremediation, but microbial metabolism in diversity of environments. This approach has the potential to make an important contribution to predicting the impact of environmental perturbations on the cycling of carbon and other biogeochemical cycles.

Lovley, Derek R.

2012-10-31T23:59:59.000Z

289

Introduction Transport in disordered graphene  

E-Print Network (OSTI)

Introduction Transport in disordered graphene Summary Ballistic transport in disordered graphene P, Gornyi, Mirlin Ballistic transport in disordered graphene #12;Introduction Transport in disordered graphene Summary Outline 1 Introduction Model Experimental motivation Transport in clean graphene 2

Fominov, Yakov

290

Finite element modelling of transport and drift effects in tokamak divertor and SOL  

SciTech Connect

A finite element code is used to simulate transport of a single-species plasma in the edge and divertor of a tokamak. The physical model is based on Braginskii`s fluid equations for the conservation of particles, parallel momentum, ion and electron energy. In modelling recycling, transport of neutral density and energy is treated in the diffusion approximation. The electrostatic potential is obtained from the generalized Ohm`s law. It is used to compute the electric field and the associated E x B drift. In a first approximation, transport is assumed to be ambipolar. The system of equations is discretized on an unstructured triangular mesh, thus permitting good spatial resolution near the X-point and an accurate description of divertor plates of arbitrary shape. Special care must be taken to prevent numerical corruption of the highly anisotropic thermal diffusion. Comparisons will be made between simulations and experimental results from TdeV. This will focus, in particular, on density and temperature profiles at the divertor plates, and on the plasma parallel velocity in the SOL. The asymmetry in the power deposited to the inner and outer divertors and the effect of magnetic field reversal will be considered. Comparisons with B2-Eirene simulation results will also be presented.

Simard, M.; Marchand, R. [INRS-Energie et Materiaux, Varennes, Quebec (Canada); Boucher, C.; Gunn, J.P. [Centre Canadien de Fusion Magnetique, Varennes, Quebec (Canada)] [and others

1996-12-31T23:59:59.000Z

291

A numerical model of non-equilibrium thermal plasmas. I. Transport properties  

SciTech Connect

A self-consistent and complete numerical model for investigating the fundamental processes in a non-equilibrium thermal plasma system consists of the governing equations and the corresponding physical properties of the plasmas. In this paper, a new kinetic theory of the transport properties of two-temperature (2-T) plasmas, based on the solution of the Boltzmann equation using a modified Chapman-Enskog method, is presented. This work is motivated by the large discrepancies between the theories for the calculation of the transport properties of 2-T plasmas proposed by different authors in previous publications. In the present paper, the coupling between electrons and heavy species is taken into account, but reasonable simplifications are adopted, based on the physical fact that m{sub e}/m{sub h} Much-Less-Than 1, where m{sub e} and m{sub h} are, respectively, the masses of electrons and heavy species. A new set of formulas for the transport coefficients of 2-T plasmas is obtained. The new theory has important physical and practical advantages over previous approaches. In particular, the diffusion coefficients are complete and satisfy the mass conversation law due to the consideration of the coupling between electrons and heavy species. Moreover, this essential requirement is satisfied without increasing the complexity of the transport coefficient formulas. Expressions for the 2-T combined diffusion coefficients are obtained. The expressions for the transport coefficients can be reduced to the corresponding well-established expressions for plasmas in local thermodynamic equilibrium for the case in which the electron and heavy-species temperatures are equal.

Zhang XiaoNing; Xia WeiDong [Department of Thermal Science and Energy Engineering, University of Science and Technology of China, Hefei, Anhui Province 230026 (China); Li HePing [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Murphy, Anthony B. [CSIRO Materials Science and Engineering, PO Box 218, Lindfield NSW 2070 (Australia)

2013-03-15T23:59:59.000Z

292

Modeling the Energy Use of a Connected and Automated Transportation System (Poster)  

SciTech Connect

Early research points to large potential impacts of connected and automated vehicles (CAVs) on transportation energy use - dramatic savings, increased use, or anything in between. Due to a lack of suitable data and integrated modeling tools to explore these complex future systems, analyses to date have relied on simple combinations of isolated effects. This poster proposes a framework for modeling the potential energy implications from increasing penetration of CAV technologies and for assessing technology and policy options to steer them toward favorable energy outcomes. Current CAV modeling challenges include estimating behavior change, understanding potential vehicle-to-vehicle interactions, and assessing traffic flow and vehicle use under different automation scenarios. To bridge these gaps and develop a picture of potential future automated systems, NREL is integrating existing modeling capabilities with additional tools and data inputs to create a more fully integrated CAV assessment toolkit.

Gonder, J.; Brown, A.

2014-07-01T23:59:59.000Z

293

A two-phase flow model of sediment transport: transition from bedload to suspended load  

E-Print Network (OSTI)

The transport of dense particles by a turbulent flow depends on two dimensionless numbers. Depending on the ratio of the shear velocity of the flow to the settling velocity of the particles (or the Rouse number), sediment transport takes place in a thin layer localized at the surface of the sediment bed (bedload) or over the whole water depth (suspended load). Moreover, depending on the sedimentation Reynolds number, the bedload layer is embedded in the viscous sublayer or is larger. We propose here a two-phase flow model able to describe both viscous and turbulent shear flows. Particle migration is described as resulting from normal stresses, but is limited by turbulent mixing and shear-induced diffusion of particles. Using this framework, we theoretically investigate the transition between bedload and suspended load.

Filippo Chiodi; Philippe Claudin; Bruno Andreotti

2014-09-02T23:59:59.000Z

294

SISGR - In situ characterization and modeling of formation reactions under extreme heating rates in nanostructured multilayer foils  

SciTech Connect

Materials subjected to extreme conditions, such as very rapid heating, behave differently than materials under more ordinary conditions. In this program we examined the effect of rapid heating on solid-state chemical reactions in metallic materials. One primary goal was to develop experimental techniques capable of observing these reactions, which can occur at heating rates in excess of one million degrees Celsius per second. One approach that we used is x-ray diffraction performed using microfocused x-ray beams and very fast x-ray detectors. A second approach is the use of a pulsed electron source for dynamic transmission electron microscopy. With these techniques we were able to observe how the heating rate affects the chemical reaction, from which we were able to discern general principles about how these reactions proceed. A second thrust of this program was to develop computational tools to help us understand and predict the reactions. From atomic-scale simulations were learned about the interdiffusion between different metals at high heating rates, and about how new crystalline phases form. A second class of computational models allow us to predict the shape of the reaction front that occurs in these materials, and to connect our understanding of interdiffusion from the atomistic simulations to measurements made in the laboratory. Both the experimental and computational techniques developed in this program are expected to be broadly applicable to a wider range of scientific problems than the intermetallic solid-state reactions studied here. For example, we have already begun using the x-ray techniques to study how materials respond to mechanical deformation at very high rates.

Hufnagel, Todd C.

2014-06-09T23:59:59.000Z

295

Representing the Effects of Long-Range Transport and Lateral Boundary Conditions in Regional Air Pollution Models  

Science Journals Connector (OSTI)

Both observational and modeling studies have demonstrated that pollutants near the Earths surface can be convectively lofted to higher altitudes where strong winds can efficiently transport them from one contine...

Rohit Mathur; Shawn Roselle; Jeffrey Young

2014-01-01T23:59:59.000Z

296

A computational model for coal transport and combustion. Final technical report  

SciTech Connect

In this project, a comprehensive theoretical, computational and experimental study directed toward providing a fundamental understanding of particulate flows as applied to coal transport is performed. Thermodynamically admissible constitutive expressions for the phasic stress tensors, heat and fluctuation energy flux vectors for turbulent multiphase flows were derived. The material parameters of the model were evaluated from the limiting conditions of rapid flows of dry spherical granular particles, and single-phase turbulent fluid flows. The case of simple shear flows of glass beads-water mixtures was studied. The model was extended to cover chemically active gas-solid flows. A thermodynamically consistent model for rapid flows of granular materials in a rotating frame of reference, along with a transport equation for the granular kinetic stress tensor was developed. The model parameters for the special case of spherical nearly elastic particles were evaluated. The results for the granular stresses and the normal stress differences were compared with the available simulation data and good agreement was observed. Effects of frictional loss of energy on rapid granular shear flows were studied. The previously developed kinetic based model was used and the mean velocity, the fluctuation kinetic energy and the solid volume fraction profiles were evaluated under a variety of conditions and different friction coefficients. A computational model for analyzing rapid granular in complex geometries was developed. The discrete element scheme was used and the granular flow down a chute was analyzed. The results were compared with the available experimental data, the model predictions, and the existing simulation results, and good agreements were observed. The model was used to analyze granular flows in a duct with an obstructing block. The effect of boundary condition was also included and the granular gravity flow was analyzed in details.

Ahmadi, G.

1995-03-01T23:59:59.000Z

297

Multi-fluid transport code modeling of time-dependent recycling in ELMy H-mode  

SciTech Connect

Simulations of a high-confinement-mode (H-mode) tokamak discharge with infrequent giant type-I ELMs are performed by the multi-fluid, multi-species, two-dimensional transport code UEDGE-MB, which incorporates the Macro-Blob approach for intermittent non-diffusive transport due to filamentary coherent structures observed during the Edge Localized Modes (ELMs) and simple time-dependent multi-parametric models for cross-field plasma transport coefficients and working gas inventory in material surfaces. Temporal evolutions of pedestal plasma profiles, divertor recycling, and wall inventory in a sequence of ELMs are studied and compared to the experimental time-dependent data. Short- and long-time-scale variations of the pedestal and divertor plasmas where the ELM is described as a sequence of macro-blobs are discussed. It is shown that the ELM recovery includes the phase of relatively dense and cold post-ELM divertor plasma evolving on a several ms scale, which is set by the transport properties of H-mode barrier. The global gas balance in the discharge is also analyzed. The calculated rates of working gas deposition during each ELM and wall outgassing between ELMs are compared to the ELM particle losses from the pedestal and neutral-beam-injection fueling rate, correspondingly. A sensitivity study of the pedestal and divertor plasmas to model assumptions for gas deposition and release on material surfaces is presented. The performed simulations show that the dynamics of pedestal particle inventory is dominated by the transient intense gas deposition into the wall during each ELM followed by continuous gas release between ELMs at roughly a constant rate.

Pigarov, A. Yu.; Krasheninnikov, S. I.; Hollmann, E. M. [University of California at San Diego, La Jolla, California 92093 (United States); Rognlien, T. D.; Lasnier, C. J. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Unterberg, E. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

2014-06-15T23:59:59.000Z

298

Multi-fluid transport code modeling of time-dependent recycling in ELMy H-mode  

SciTech Connect

Simulations of a high-confinement-mode (H-mode) tokamak discharge with infrequent giant type-I ELMs are performed by the multi-fluid, multi-species, two-dimensional transport code UEDGE-MB, which incorporates the Macro-Blob approach for intermittent non-diffusive transport due to filamentary coherent structures observed during the Edge Localized Modes (ELMs) and simple time-dependent multi-parametric models for cross-field plasma transport coefficients and working gas inventory in material surfaces. Temporal evolutions of pedestal plasma profiles, divertor recycling, and wall inventory in a sequence of ELMs are studied and compared to the experimental time-dependent data. Short- and long-time-scale variations of the pedestal and divertor plasmas where the ELM is described as a sequence of macro-blobs are discussed. It is shown that the ELM recovery includes the phase of relatively dense and cold post-ELM divertor plasma evolving on a several ms scale, which is set by the transport properties of H-mode barrier. The global gas balance in the discharge is also analyzed. The calculated rates of working gas deposition during each ELM and wall outgassing between ELMs are compared to the ELM particle losses from the pedestal and neutral-beam-injection fueling rate, correspondingly. A sensitivity study of the pedestal and divertor plasmas to model assumptions for gas deposition and release on material surfaces is presented. The performed simulations show that the dynamics of pedestal particle inventory is dominated by the transient intense gas deposition into the wall during each ELM followed by continuous gas release between ELMs at roughly a constant rate.

Pigarov, A. Yu. [University of California, San Diego; Krasheninnikov, S. I. [University of California, La Jolla; Rognlien, T. D. [Lawrence Livermore National Laboratory (LLNL); Hollmann, E. M. [University of California, San Diego; Lasnier, C. J. [Lawrence Livermore National Laboratory (LLNL); Unterberg, Ezekial A [ORNL

2014-01-01T23:59:59.000Z

299

Characterization and activity of ferric-sulfide-based catalyst in model reactions of direct coal liquefaction: Effect of preparation conditions  

SciTech Connect

The authors studied the activity of various ferric-sulfide-based catalysts in model hydrogenation and cracking reactions under conditions typical of direct coal liquefaction (DCL). The catalysts used were mixtures of FeS{sub 2} (pyrite, PY) and nonstoichiometric FeS{sub x} (pyrrhotite, PH) obtained by high-temperature disproportionation of ferric sulfide in a nitrogen atmosphere or a hydrogen atmosphere. The structural changes in the catalyst were also examined, both before and after the model reactions. The cracking functionality of the catalysts was studied by using cumene, and the hydrocracking functionality was studied by using diphenylmethane. Phenanthrene was used as a model compound for hydrogenation and hydrogen shuttling. Phenanthrene hydrogenation was studied in the presence of H{sub 2}(g), and hydrogen shuttling was studied when a hydrogen donor (tetralin) was present in the absence of H{sub 2}(g). All the model reactions were performed under conditions typical of DCL: 400 C and 1,000 psig for 30 min. The surface and bulk of the catalysts were characterized by Auger electron spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and atomic absorption spectroscopy. The performance of the catalysts was found to vary with the type of reaction, the initial ratio of FeS{sub x} to FeS{sub 2} (PH/PY) found in the catalyst, and the catalyst age. Catalysts freshly prepared in a nitrogen atmosphere were most active for model hydrogenation and hydrocracking runs. Catalysts freshly prepared in hydrogen were most active in shuttling. A simple model was developed to explain changes in the surface and bulk of the catalysts.

Chadha, A.; Stinespring, C.D.; Stiller, A.H.; Zondlo, J.W.; Dadyburjor, D.B. [West Virginia Univ., Morgantown, WV (United States). Dept. of Chemical Engineering] [West Virginia Univ., Morgantown, WV (United States). Dept. of Chemical Engineering

1997-02-01T23:59:59.000Z

300

Kinetics of intrachain reactions of supercoiled DNA: Theory and numerical modeling  

E-Print Network (OSTI)

. Klenin and Jo¨rg Langowskia) Division Biophysics of Macromolecules, German Cancer Research Center, Im analytical approach has yet been found. It is clear that the rate of a very slow reaction is deter- mined that the activity

Langowski, Jörg

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301

Model hydrodesulfurization reactions: saturated C/sub 4/S molecules on Mo(110)  

SciTech Connect

The reactions of tetrahydrothiophene and 1-butanethiol on Mo(110) have been investigated by using temperature-programmed reaction spectroscopy, isotopic exchange reactions, and Auger electron spectroscopy. At low exposures, tetrahydrothiophene decomposes below 400 K to gaseous dihydrogen and surface carbon and sulfur. Higher tetrahydrothiophene exposures also result in reaction limited formation of butane and butene at 350 and 380 K, respectively. Preadsorption of a saturation coverage of hydrogen or deuterium atoms decreases the temperature at which butane is formed by 50 K and increases the yield of butane by a factor of approximately 6 at reaction saturation. The butene formation peak is unaffected by the presence of excess surface hydrogen. Reversible desorption of molecularly bound tetrahydrothiophene from the Mo(110) surface is observed at 310 K. In the absence of preadsorbed hydrogen, approximately 25% of the tetrahydrothiophene that reacts forms hydrocarbons, as measured by Auger electron spectroscopy. An irreversibly bound hydrocarbon fragment is present on the surface which decomposes at 565 K to produce gaseous dihydrogen. The butane, butene, and dihydrogen incorporate surface deuterium. The proposed mechanism for this reaction is initial hydrogenation of one of the ..cap alpha..-carbon atoms with accompanying C-S bond scission.

Roberts, J.T.; Friend, C.M.

1986-11-12T23:59:59.000Z

302

High-energy nuclear quasielastic reactions: Decisive tests of nuclear-binding/pion models of the European Muon Collaboration effect  

Science Journals Connector (OSTI)

The light-cone nucleon momentum distributions obtained from nonrelativistic spectral functions or given by nuclear-binding/pion models are often used to analyze high-Q2 quasielastic and deep-inelastic (e,e) reactions. We demonstrate that in such models the presence of non-nucleonic components causes the scattering from forward and backward moving target protons to be significantly different. Other models do not have this property. The sensitivity of current (e,ep) and (p,pp) color transparency experiments is sufficient to observe these differences.

L. Frankfurt; G. A. Miller; M. Strikman

1992-01-06T23:59:59.000Z

303

High energy nuclear quasielastic reactions: Decisive tests of nuclear binding/pion models of the EMC effect  

SciTech Connect

The light-cone nucleon momentum distributions obtained from non- relativistic spectral functions or given by nuclear binding/pion models are often used to analyze high Q{sup 2} quasi-elastic and deep-inelastic (e,e{prime}) reactions. We demonstrate that in such models the presence of non-nucleonic components causes the scattering from forward and backward moving target protons to be significantly different. Other models do not have this property. The sensitivity of current (e,e{prime}p) and (p,pp) color transparency experiments is sufficient to observe these differences.

Frankfurt, L; Strikman, M [Washington Univ., Seattle, WA (United States). Inst. for Nuclear Theory AN SSSR, Leningrad (USSR). Inst. Yadernoj Fiziki; Miller, G A [Washington Univ., Seattle, WA (United States). Inst. for Nuclear Theory

1991-01-01T23:59:59.000Z

304

Theory of nuclear reactions  

SciTech Connect

The book presents a theory of nuclear reaction. An account is given of the nonrelativistic nuclear reaction theory. The R - matrix description of nuclear reactions is considered and the dispersion method is formulated. Mechanisms of nuclear reactions and their relationship are studied in detail. Attention is paid to nuclear reactions involving the compound nuclear formation and to direct nuclear processes. The optical model the diffraction approach and high - energy diffraction nuclear processes involving composite particles are discussed.

Sitenko, A.G.

1990-01-01T23:59:59.000Z

305

A PM3-SRP + Analytic Function Potential Energy Surface Model for O(3P) Reactions with Alkanes. Application to O(3P) + Ethane  

Science Journals Connector (OSTI)

A PM3-SRP + Analytic Function Potential Energy Surface Model for O(3P) Reactions with Alkanes. ... The results of high-level ab initio calculations for the O(3P) + C2H6 primary reactions, yielding OH + C2H5, C2H5O + H, and CH3O + CH3, 11 ensuing secondary and unimolecular dissociation reactions involving products of these primary reactions, and additional reactions were used to develop two PM3-SRP models for the PES. ... Even though these two PM3-SRP models are unable to quantitatively represent the many reactions that occur in high-energy collisions of O(3P) with alkanes, they are vast improvements over the PES of PM3 theory. ...

Tianying Yan; Charles Doubleday; William L. Hase

2004-07-16T23:59:59.000Z

306

Simplification of the tug-of-war model for cellular transport in cells  

E-Print Network (OSTI)

The transport of organelles and vesicles in living cells can be well described by a kinetic tug-of-war model advanced by M\\"uller, Klumpp and Lipowsky. In which, the cargo is attached by two motor species, kinesin and dynein, and the direction of motion is determined by the number of motors which bind to the track. In recent work [Phys. Rev. E 79, 061918 (2009)], this model was studied by mean field theory, and it was found that, usually the tug-of-war model has one, two, or three distinct stable stationary points. However, the results there are mostly obtained by numerical calculations, since it is hard to do detailed theoretical studies to a two-dimensional nonlinear system. In this paper, we will carry out further detailed analysis about this model, and try to find more properties theoretically. Firstly, the tug-of-war model is simplified to a one-dimensional equation. Then we claim that the stationary points of the tug-of-war model correspond to the roots of the simplified equation, and the stable stationary points correspond to the roots with positive derivative. Bifurcation occurs at the corresponding parameters, under which the simplified one-dimensional equation exists root with zero derivative. Using the simplified equation, not only more properties of the tug-of-war model can be obtained analytically, the related numerical calculations will become more accurate and more efficient. This simplification will be helpful to future studies of the tug-of-war model.

Yunxin Zhang

2010-07-07T23:59:59.000Z

307

Driving kinetically constrained models into non-equilibrium steady states: structural and slow transport properties  

E-Print Network (OSTI)

Complex fluids in shear flow and biased dynamics in crowded environments exhibit counterintuitive features which are difficult to address both at theoretical level and by molecular dynamic simulations. To understand some of these features we study a schematic model of highly viscous liquid, the 2D Kob-Andersen kinetically constrained model, driven into non-equilibrium steady states by a uniform non-Hamiltonian force. We present a detailed numerical analysis of the microscopic behavior of the model, including transversal and longitudinal spatial correlations and dynamic heterogeneities. In particular, we show that at high particle density the transition from positive to negative resistance regimes in the current vs field relation can be explained via the emergence of nontrivial structures that intermittently trap the particles and slow down the dynamics. We relate such spatial structures to the current vs field relation in the different transport regimes.

Francesco Turci; Estelle Pitard; Mauro Sellitto

2012-06-27T23:59:59.000Z

308

Shock of three-state model for intracellular transport of kinesin KIF1A  

E-Print Network (OSTI)

Recently, a three-state model is presented to describe the intracellular traffic of unconventional (single-headed) kinesin KIF1A [Phys. Rev. Lett. {\\bf 95}, 118101 (2005)], in which each motor can bind strongly or weakly to its microtubule track, and each binding site of the track might be empty or occupied by one motor. As the usual two-state model, i.e. the totally asymmetric simple exclusion process (TASEP) with motor detachment and attachment, in steady state of the system, this three-state model also exhibits shock (or domain wall separating the high-density and low density phases) and boundary layers. In this study, using mean-field analysis, the conditions of existence of shock and boundary layers are obtained theoretically. Combined with numerical calculations, the properties of shock are also studied. This study will be helpful to understand the biophysical properties of the collective transport of kinesin KIF1A.

Yunxin Zhang

2011-05-16T23:59:59.000Z

309

An optimal penalty method for a hyperbolic system modeling the edge plasma transport in a tokamak  

Science Journals Connector (OSTI)

Abstract The penalization method is used to take account of obstacles, such as the limiter, in a tokamak. Because of the magnetic confinement of the plasma in a tokamak, the transport occurs essentially in the direction parallel to the magnetic field lines. We study a 1D nonlinear hyperbolic system as a simplified model of the plasma transport in the area close to the wall. A penalization which cuts the flux term of the momentum is studied. We show numerically that this penalization creates a Dirac measure at the plasma-limiter interface which prevents us from defining the transport term in the usual distribution sense. Hence, a new penalty method is proposed for this hyperbolic system. For this penalty method, an asymptotic expansion and numerical tests give an optimal rate of convergence without spurious boundary layer. Another two-fields penalization has also been implemented and the numerical convergence analysis when the penalization parameter tends to 0 reveals the presence of a boundary layer.

Philippe Angot; Thomas Auphan; Olivier Gus

2014-01-01T23:59:59.000Z

310

Area-preserving maps models of gyro-averaged ${\\bf E} \\times {\\bf B}$ chaotic transport  

E-Print Network (OSTI)

Discrete maps have been extensively used to model 2-dimensional chaotic transport in plasmas and fluids. Here we focus on area-preserving maps describing finite Larmor radius (FLR) effects on ${\\bf E} \\times {\\bf B}$ chaotic transport in magnetized plasmas with zonal flows perturbed by electrostatic drift waves. FLR effects are included by gyro-averaging the Hamiltonians of the maps which, depending on the zonal flow profile, can have monotonic or non-monotonic frequencies. In the limit of zero Larmor radius, the monotonic frequency map reduces to the standard Chirikov-Taylor map, and, in the case of non-monotonic frequency, the map reduces to the standard nontwist map. We show that in both cases FLR leads to chaos suppression, changes in the stability of fixed points, and robustness of transport barriers. FLR effects are also responsible for changes in the phase space topology and zonal flow bifurcations. Dynamical systems methods based on recurrence time statistics are used to quantify the dependence on the...

da Fonseca, J D; Caldas, I L

2014-01-01T23:59:59.000Z

311

Modeling heat conduction and radiation transport with the diffusion equation in  

NLE Websites -- All DOE Office Websites (Extended Search)

heat conduction and radiation transport with the diffusion equation in NIF ALE-AMR heat conduction and radiation transport with the diffusion equation in NIF ALE-AMR This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2010 J. Phys.: Conf. Ser. 244 022075 (http://iopscience.iop.org/1742-6596/244/2/022075) Download details: IP Address: 50.136.219.251 The article was downloaded on 18/04/2013 at 01:36 Please note that terms and conditions apply. View the table of contents for this issue, or go to the journal homepage for more Home Search Collections Journals About Contact us My IOPscience Modeling Heat Conduction and Radiation Transport with the Diffusion Equation in NIF ALE-AMR A.C. Fisher 1 , D.S. Bailey 1 , T.B. Kaiser 1 , B.T.N. Gunney 1 , N.D. Masters 1 , A.E. Koniges 2 , D.C. Eder 1 , R.W. Anderson 1 1: Lawrence Livermore National Laboratory,

312

Initialization of hydrodynamics in relativistic heavy ion collisions with an energy-momentum transport model  

E-Print Network (OSTI)

A key ingredient of hydrodynamical modeling of relativistic heavy ion collisions is thermal initial conditions, an input that is the consequence of a pre-thermal dynamics which is not completely understood yet. In the paper we employ a recently developed energy-momentum transport model of the pre-thermal stage to study influence of the alternative initial states in nucleus-nucleus collisions on flow and energy density distributions of the matter at the starting time of hydrodynamics. In particular, the dependence of the results on isotropic and anisotropic initial states is analyzed. It is found that at the thermalization time the transverse flow is larger and the maximal energy density is higher for the longitudinally squeezed initial momentum distributions. The results are also sensitive to the relaxation time parameter, equation of state at the thermalization time, and transverse profile of initial energy density distribution: Gaussian approximation, Glauber Monte Carlo profiles, etc. Also, test results ensure that the numerical code based on the energy-momentum transport model is capable of providing both averaged and fluctuating initial conditions for the hydrodynamic simulations of relativistic nuclear collisions.

V. Yu. Naboka; S. V. Akkelin; Iu. A. Karpenko; Yu. M. Sinyukov

2015-01-14T23:59:59.000Z

313

Exotic quantum transport in double-stranded Kronig-Penney model  

E-Print Network (OSTI)

We introduce double-stranded Kronig-Penney model and analyze its transport properties. The asymmetric fluxes between two strands with suddenly alternating localization patterns are found as the energy is varied. The zero-size limit of the internal lines connecting two strands is examined using quantum graph vertices with four edges. We also consider a two-dimensional Kronig-Penney lattice with two types of alternating layers with $\\delta$ and $\\delta'$ connections, and show that the existence of energy bands in which the quantum flux can flow only in selected directions.

Taksu Cheon; Sergey S. Poghosyan

2014-10-31T23:59:59.000Z

314

Mesoscopic modeling of multi-physicochemical transport phenomena in porous media  

SciTech Connect

We present our recent progress on mesoscopic modeling of multi-physicochemical transport phenomena in porous media based on the lattice Boltzmann method. Simulation examples include injection of CO{sub 2} saturated brine into a limestone rock, two-phase behavior and flooding phenomena in polymer electrolyte fuel cells, and electroosmosis in homogeneously charged porous media. It is shown that the lattice Boltzmann method can account for multiple, coupled physicochemical processes in these systems and can shed some light on the underlying physics occuning at the fundamental scale. Therefore, it can be a potential powerful numerical tool to analyze multi-physicochemical processes in various energy, earth, and environmental systems.

Kang, Qinjin [Los Alamos National Laboratory; Wang, Moran [Los Alamos National Laboratory; Mukherjee, Partha P [Los Alamos National Laboratory; Lichtner, Peter C [Los Alamos National Laboratory

2009-01-01T23:59:59.000Z

315

Planning Model of Optimal Modal-Mix in Intercity Passenger Transportation  

Science Journals Connector (OSTI)

Environmentally sustainable transportation becomes an important issue as well for intercity passenger transportation, where modal shifting from energy consuming airline and bus service to energy efficient high sp...

Makoto Okumura; Huseyin Tirtom; Hiromichi Yamaguchi

2013-01-01T23:59:59.000Z

316

Mixed integer model for optimizing equipment scheduling and overburden transport in a surface coal mining operation  

SciTech Connect

The lack of available techniques prompted the development of a mixed integer model to optimize the scheduling of equipment and the distribution of overburden in a typical mountaintop removal operation. Using this format, a (0-1) integer model and transportation model were constructed to determine the optimal equipment schedule and optimal overburden distribution, respectively. To solve this mixed integer program, the model was partitioned into its binary and real-valued components. Each problem was successively solved and their values added to form estimates of the value of the mixed integer program. Optimal convergence was indicated when the difference between two successive estimates satisfied some pre-specific accuracy value. The performance of the mixed integer model was tested against actual field data to determine its practical applications. To provide the necessary input information, production data was obtained from a single seam, mountaintop removal operation located in the Appalachian coal field. As a means of analyzing the resultant equipment schedule, the total idle time was calculated for each machine type and each lift location. Also, the final overburden assignments were analyzed by determining the distribution of spoil material for various overburden removal productivities. Subsequent validation of the mixed integer model was conducted in two distinct areas. The first dealt with changes in algorithmic data and their effects on the optimality of the model. The second area concerned variations in problem structure, specifically those dealing with changes in problem size and other user-inputed values such as equipment productivities or required reclamation.

Goodman, G.V.R.

1987-01-01T23:59:59.000Z

317

3-D agricultural air quality modeling: Impacts of NH3/H2S gasphase reactions and bi-directional exchange of NH3  

Science Journals Connector (OSTI)

Abstract Accurately simulating the transport and fate of reduced nitrogen (NHx=ammonia (NH3)+ammonium (NH4+))- and sulfur-containing compounds emitted from agricultural activities represents a major challenge in agricultural air quality modeling. In this study, the Community Multiscale Air Quality (CMAQ) modeling system is further developed and improved by implementing 22 ammonia (NH3)/hydrogen sulfide (H2S) related gas-phase reactions and adjusting a few key parameters (e.g., emission potential) for bi-directional exchange of NH3 fluxes. Several simulations are conducted over the eastern U.S. domain at a 12-km horizontal resolution for January and July 2002 to examine the impacts of those improved treatments on air quality. The 5th generation mesoscale model (MM5) and CMAQ predict an overall satisfactory and consistent performance with previous modeling studies, especially for 2-m temperature, 2-m relative humidity, ozone (O3), and fine particulate matter (PM2.5). High model biases exist for precipitation in July and also dry/wet depositions. The updated model treatments contribute to O3, NHx, and PM2.5 by up to 0.4ppb, 1.0?gm?3, and 1.0?gm?3 in January, respectively, and reduce O3 by up to 0.8ppb and contribute to \\{NHx\\} and PM2.5 by up to 1.2 and 1.1?gm?3 in July, respectively. The spatial distributions of O3 in both months and sulfur dioxide (SO2) in January are mainly affected by inline dry deposition velocity calculation. The spatial distributions of SO2 and sulfate (SO42?) in July are affected by both inline dry deposition velocity and NH3/H2S reactions. The variation trends of NH3, NHx, ammonium nitrate (NH4NO3), PM2.5 and total nitrogen (TN) are predominated by bi-directional exchange of NH3 fluxes. Uncertainties of NH3 emission potentials and empirical constants used in the bi-directional exchange scheme may significantly affect the concentrations of \\{NHx\\} and PM2.5, indicating that a more accurate and explicit treatment for those parameters should be considered in the future work.

Kai Wang; Yang Zhang

2014-01-01T23:59:59.000Z

318

Urban airshed modeling of air quality impacts of alternative transportation fuel use in Los Angeles and Atlanta  

SciTech Connect

The main objective of NREL in supporting this study is to determine the relative air quality impact of the use of compressed natural gas (CNG) as an alternative transportation fuel when compared to low Reid vapor pressure (RVP) gasoline and reformulated gasoline (RFG). A table lists the criteria, air toxic, and greenhouse gas pollutants for which emissions were estimated for the alternative fuel scenarios. Air quality impacts were then estimated by performing photochemical modeling of the alternative fuel scenarios using the Urban Airshed Model Version 6.21 and the Carbon Bond Mechanism Version IV (CBM-IV) (Geary et al., 1988) Using this model, the authors examined the formation and transport of ozone under alternative fuel strategies for motor vehicle transportation sources for the year 2007. Photochemical modeling was performed for modeling domains in Los Angeles, California, and Atlanta, Georgia.

NONE

1997-12-01T23:59:59.000Z

319

Singlet oxygen generation according to flame-sheet and finite-rate chlorine/BHP reaction models. [Basic Hydrogen Peroxide  

SciTech Connect

In a flowing chemical oxygen--iodine laser, the photon energy is emitted by excited iodine atoms. These atoms are produced by energy transfer from O[sub 2]([sup 1][Delta]) after molecular iodine is dissociated upon mixing and reaction with the O[sub 2]([sup 1][Delta]). The generation of singlet delta oxygen, O[sub 2]([sup 1][Delta]), following gaseous chlorine diffusion into and reaction with liquid basic hydrogen peroxide (solution of KOH or NaOH in H[sub 2]O[sub 2] and H[sub 2]O) is investigated. Both flame-sheet and finite-rate reaction models for Cl[sub 2]/BHP are developed. A closed-form solution for the O[sub 2]([sup 1][Delta]) yield is obtained with the flame-sheet analysis, while a solution involving an integral equation is derived with the finite-rate analysis. The models are applied to a rotating disk type O[sub 2]([sup 1][Delta]) generator for illustration. The results do not differ greatly between the two models, and they show favorable agreement with reported experimental data.

Quan, V.; Copeland, D.A.; Blauer, J.A.; Rodriguez, S.E. (Rockwell International, Canoga Park, CA (United States). Rocketdyne Div.)

1994-05-01T23:59:59.000Z

320

Characterization and Reaction Studies of Silica Supported Platinum and Rhodium Model Catalysts  

E-Print Network (OSTI)

at which a chemical reaction approaches equilibrium and does not itself undergo a net chemical change.1 When a catalyst is in a different phase (e.g. solid) than a reactant mixture it is defined as a heterogeneous catalyst. Two types of heterogeneous... concerning the active-nature of the surface. For what reasons, on an atomic level, are surfaces capable of sustaining a reaction and others deactivate? What effect does particle size/structure have on activity and selectivity? Is this an electronic...

Lundwall, Matthew James

2012-02-14T23:59:59.000Z

Note: This page contains sample records for the topic "reaction transport model" from the National Library of EnergyBeta (NLEBeta).
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321

Development of a Hydrodynamic and Transport model of Bellingham Bay in Support of Nearshore Habitat Restoration  

SciTech Connect

In this study, a hydrodynamic model based on the unstructured-grid finite volume coastal ocean model (FVCOM) was developed for Bellingham Bay, Washington. The model simulates water surface elevation, velocity, temperature, and salinity in a three-dimensional domain that covers the entire Bellingham Bay and adjacent water bodies, including Lummi Bay, Samish Bay, Padilla Bay, and Rosario Strait. The model was developed using Pacific Northwest National Laboratorys high-resolution Puget Sound and Northwest Straits circulation and transport model. A sub-model grid for Bellingham Bay and adjacent coastal waters was extracted from the Puget Sound model and refined in Bellingham Bay using bathymetric light detection and ranging (LIDAR) and river channel cross-section data. The model uses tides, river inflows, and meteorological inputs to predict water surface elevations, currents, salinity, and temperature. A tidal open boundary condition was specified using standard National Oceanic and Atmospheric Administration (NOAA) predictions. Temperature and salinity open boundary conditions were specified based on observed data. Meteorological forcing (wind, solar radiation, and net surface heat flux) was obtained from NOAA real observations and National Center for Environmental Prediction North American Regional Analysis outputs. The model was run in parallel with 48 cores using a time step of 2.5 seconds. It took 18 hours of cpu time to complete 26 days of simulation. The model was calibrated with oceanographic field data for the period of 6/1/2009 to 6/26/2009. These data were collected specifically for the purpose of model development and calibration. They include time series of water-surface elevation, currents, temperature, and salinity as well as temperature and salinity profiles during instrument deployment and retrieval. Comparisons between model predictions and field observations show an overall reasonable agreement in both temporal and spatial scales. Comparisons of root mean square error values for surface elevation, velocity, temperature, and salinity time series are 0.11 m, 0.10 m/s, 1.28oC, and 1.91 ppt, respectively. The model was able to reproduce the salinity and temperature stratifications inside Bellingham Bay. Wetting and drying processes in tidal flats in Bellingham Bay, Samish Bay, and Padilla Bay were also successfully simulated. Both model results and observed data indicated that water surface elevations inside Bellingham Bay are highly correlated to tides. Circulation inside the bay is weak and complex and is affected by various forcing mechanisms, including tides, winds, freshwater inflows, and other local forcing factors. The Bellingham Bay model solution was successfully linked to the NOAA oil spill trajectory simulation model General NOAA Operational Modeling Environment (GNOME). Overall, the Bellingham Bay model has been calibrated reasonably well and can be used to provide detailed hydrodynamic information in the bay and adjacent water bodies. While there is room for further improvement with more available data, the calibrated hydrodynamic model provides useful hydrodynamic information in Bellingham Bay and can be used to support sediment transport and water quality modeling as well as assist in the design of nearshore restoration scenarios.

Wang, Taiping; Yang, Zhaoqing; Khangaonkar, Tarang

2010-04-22T23:59:59.000Z

322

A Complete Transport Validated Model on a Zeolite Membrane for Carbon Dioxide Permeance and Capture  

E-Print Network (OSTI)

The CO2 emissions from major industries cause serious global environment problems and their mitigation is urgently needed. The use of zeolite membranes is a very efficient way in order to capture CO2 from some flue gases. The dominant transport mechanism at low temperature andor high pressure is the diffusion through the membrane. This procedure can be divided in three steps: Adsorption of the molecules of the species in the surface of the membrane, then a driving force gives a path where the species follow inside the membrane and finally the species desorbed from the surface of the membrane. The current work is aimed at developing a simulation model for the CO2 transport through a zeolite membrane and estimate the diffusion phenomenon through a very thin membrane of 150 nm in a Wicke-Kallenbach cell. The cell is cylindrical in shape with diameter of 19 mm and consists of a retentate gas chamber, a permeate gas chamber which are separated by a cylindrical zeolite membrane. This apparatus have been modeled wit...

Gkanas, Evangelos I; Stubos, Athanasios K; Makridis, Sofoklis S

2013-01-01T23:59:59.000Z

323

The application of enzyme reaction, nonlinear diffusion models to the malting process  

Science Journals Connector (OSTI)

...to close down the reaction...sugar from starch. A schematic...beta-glucanases, which break up glutin...endosperm. The starch molecules...so-called alpha and beta amylases, the second...released starch to produce...second stage breaks down into the...

2010-01-01T23:59:59.000Z

324

Analysis of vadose zone tritium transport from an underground storage tank release using numerical modeling and geostatistics  

SciTech Connect

Numerical and geostatistical analyses show that the artificial smoothing effect of kriging removes high permeability flow paths from hydrogeologic data sets, reducing simulated contaminant transport rates in heterogeneous vadose zone systems. therefore, kriging alone is not recommended for estimating the spatial distribution of soil hydraulic properties for contaminant transport analysis at vadose zone sites. Vadose zone transport if modeled more effectively by combining kriging with stochastic simulation to better represent the high degree of spatial variability usually found in the hydraulic properties of field soils. However, kriging is a viable technique for estimating the initial mass distribution of contaminants in the subsurface.

Lee, K.H.

1997-09-01T23:59:59.000Z

325

Comprehensive inverse modeling for the study of carrier transport models in sub-50nm MOSFETs  

E-Print Network (OSTI)

Direct quantitative 2-D characterization of sub-50 nm MOSFETs continues to be elusive. This research develops a comprehensive indirect inverse modeling technique for extracting 2-D device topology using combined log(I)-V ...

Djomehri, Ihsan Jahed, 1976-

2002-01-01T23:59:59.000Z

326

Models for source term, flow, transport and dose assessment in NRC`s Iterative Performance Assessment, Phase 2  

SciTech Connect

The core consequence modules for the recently completed Phase 2 Iterative Performance Assessment (IPA) of the Yucca Mountain repository for high-level nuclear waste depend on models for releases from the engineered barrier system (source term), flow of liquid and gas, transport of radionuclides in the geosphere and assessment of dose to target populations. The source term model includes temperature and moisture phenomena in the near-field environment, general, pitting and crevice corrosion, contact of the waste form by water, dissolution and oxidation of the waste form, and transport of dissolved and gaseous radionuclides from the waste package by advection and diffusion. The liquid flow and transport models describe water flow through fractures and matrix in both the unsaturated and saturated zones. Models for flow of gas and transport of {sup 14}CO{sub 2} released from the engineered barrier system to the atmosphere take into account repository heat and the geothermal gradient. The dose assessment model calculates doses to a regional population and a farm family for an assumed reference biosphere in the vicinity of the repository. The Phase 2 IPA led to a number of suggestions for model improvement: (1) improve the ability of the models to include spatial and temporal variability in the parameters; (2) improve the coupling among processes, especially the effects of changing environments in the waste packages; (3) develop more mechanistic models, but abstracted for use in total system performance assessment; and (4) use more site specific parameters, especially for the dose assessments.

McCartin, T.; Codell, R.; Neel, R.; Ford, W.; Wescott, R.; Bradbury, J. [Nuclear Regulatory Commission, Washington, DC (United States); Sagar, B.; Walton, J. [Center for Nuclear Waste Regulatory Analyses, San Antonio, TX (United States)

1994-12-31T23:59:59.000Z

327

ACCELERATION OF LOW-ENERGY IONS AT PARALLEL SHOCKS WITH A FOCUSED TRANSPORT MODEL  

SciTech Connect

We present a test particle simulation on the injection and acceleration of low-energy suprathermal particles by parallel shocks with a focused transport model. The focused transport equation contains all necessary physics of shock acceleration, but avoids the limitation of diffusive shock acceleration (DSA) that requires a small pitch angle anisotropy. This simulation verifies that the particles with speeds of a fraction of to a few times the shock speed can indeed be directly injected and accelerated into the DSA regime by parallel shocks. At higher energies starting from a few times the shock speed, the energy spectrum of accelerated particles is a power law with the same spectral index as the solution of standard DSA theory, although the particles are highly anisotropic in the upstream region. The intensity, however, is different from that predicted by DSA theory, indicating a different level of injection efficiency. It is found that the shock strength, the injection speed, and the intensity of an electric cross-shock potential (CSP) jump can affect the injection efficiency of the low-energy particles. A stronger shock has a higher injection efficiency. In addition, if the speed of injected particles is above a few times the shock speed, the produced power-law spectrum is consistent with the prediction of standard DSA theory in both its intensity and spectrum index with an injection efficiency of 1. CSP can increase the injection efficiency through direct particle reflection back upstream, but it has little effect on the energetic particle acceleration once the speed of injected particles is beyond a few times the shock speed. This test particle simulation proves that the focused transport theory is an extension of DSA theory with the capability of predicting the efficiency of particle injection.

Zuo, Pingbing; Zhang, Ming; Rassoul, Hamid K. [Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL 32901 (United States)] [Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL 32901 (United States)

2013-04-10T23:59:59.000Z

328

Transportation Sector Model of the National Energy Modeling System. Volume 2 -- Appendices: Part 3  

SciTech Connect

This Appendix consists of two unpublished reports produced by Energy and Environmental Analysis, Inc., under contract to Oak Ridge National Laboratory. These two reports formed the basis for the subsequent development of the Fuel Economy Model described in Volume 1. They are included in order to document more completely the efforts undertaken to construct a comprehensive model of automobile fuel economy. The supplemental reports are as follows: Supplement 1--Documentation Attributes of Technologies to Improve Automotive Fuel Economy; Supplement 2--Analysis of the Fuel Economy Boundary for 2010 and Comparison to Prototypes.

NONE

1998-01-01T23:59:59.000Z

329

Carbon-nitrogen bond-forming reactions in supercritical and expanded-liquid carbon dioxide media : green synthetic chemistry with multiscale reaction and phase behavior modeling  

E-Print Network (OSTI)

The goal of this work was to develop a detailed understanding of carbon-nitrogen (C-N) bond-forming reactions of amines carried out in supercritical and expanded-liquid carbon dioxide (CO2) media. Key motivations behind ...

Ciccolini, Rocco P

2008-01-01T23:59:59.000Z

330

A classical approach in simple nuclear fusion reaction {sub 1}H{sup 2}+{sub 1}H{sup 3} using two-dimension granular molecular dynamics model  

SciTech Connect

Molecular dynamics in 2-D accompanied by granular model provides an opportunity to investigate binding between nuclei particles and its properties that arises during collision in a fusion reaction. A fully classical approach is used to observe the influence of initial angle of nucleus orientation to the product yielded by the reaction. As an example, a simplest fusion reaction between {sub 1}H{sup 2} and {sub 1}H{sup 3} is observed. Several products of the fusion reaction have been obtained, even the unreported ones, including temporary {sub 2}He{sup 4} nucleus.

Viridi, S.; Kurniadi, R.; Waris, A.; Perkasa, Y. S. [Nuclear Physics and Biophysics Research Division, Institut Teknologi Bandung, Bandung 40132 (Indonesia); Doctoral Program in Physics, Institut Teknologi Bandung, Bandung 40132 Physics Department, Universitas Islam Negeri Sunan Gunung Djati, Bandung 40614 (Indonesia)

2012-06-06T23:59:59.000Z

331

Tritium transport in the NuMI decay pipe region - modeling and comparison with experimental data  

SciTech Connect

The NuMI (Neutrinos at Main Injector) beam facility at Fermilab is designed to produce an intense beam of muon neutrinos to be sent to the MINOS underground experiment in Soudan, Minnesota. Neutrinos are created by the decay of heavier particles. In the case of NuMI, the decaying particles are created by interaction of high-energy protons in a target, creating mostly positive pions. These particles can also interact with their environment, resulting in production of a variety of short-lived radionuclides and tritium. In the NuMI beam, neutrinos are produced by 120 GeV protons from the Fermilab Main Injector accelerator which are injected into the NuMI beam line using single turn extraction. The beam line has been designed for 400 kW beam power, roughly a factor of 2 above the initial (2005-06) running conditions. Extracted protons are bent downwards at a 57mr angle towards the Soudan Laboratory. The meson production target is a 94 cm segmented graphite rod, cooled by water in stainless tubes on the top and bottom of the target. The target is followed by two magnetic horns which are pulsed to 200 kA in synchronization with the passage of the beam, producing focusing of the secondary hadron beam and its daughter neutrinos. Downstream of the second horn the meson beam is transported for 675 m in an evacuated 2 m diameter beam (''decay'') pipe. Subsequently, the residual mesons and protons are absorbed in a water cooled aluminum/steel absorber immediately downstream of the decay pipe. Some 200 m of rock further downstream ranges out all of the residual muons. During beam operations, after installation of the chiller condensate system in December 2005, the concentration of tritiated water in the MINOS sump flow of 177 gpm was around 12 pCi/ml, for a total of 0.010 pCi/day. A simple model of tritium transport and deposition via humidity has been constructed to aid in understanding how tritium reaches the sump water. The model deals with tritium transported as HTO, water in which one hydrogen atom has been replaced with tritium. Based on concepts supported by the modeling, a dehumidification system was installed during May 2006 that reduced the tritium level in the sump by a factor of two. This note is primarily concerned with tritium that was produced in the NuMI target pile, carried by air flow into the target hall and down the decay pipe passageway (where most of it was deposited). The air is exhausted through the existing air vent shaft EAV2 (Figure 1).

Hylen, J.; Plunkett, R.; /Fermilab

2007-03-01T23:59:59.000Z

332

How does the mass transport in disk galaxy models influence the character of orbits?  

E-Print Network (OSTI)

We explore the regular or chaotic nature of orbits of stars moving in the meridional (R,z) plane of an axially symmetric time-dependent disk galaxy model with a central, spherically symmetric nucleus. In particular, mass is linearly transported from the disk to the galactic nucleus, in order to mimic, in a way, the case of self-consistent interactions of an actual N-body simulation. We thus try to unveil the influence of this mass transportation on the different families of orbits of stars by monitoring how the percentage of chaotic orbits, as well as the percentages of orbits of the main regular resonant families, evolve as the galaxy develops a dense and massive nucleus in its core. The SALI method is applied to samples of orbits in order to distinguish safely between ordered and chaotic motion. In addition, a method based on the concept of spectral dynamics is used for identifying the various families of regular orbits and also for recognizing the secondary resonances that bifurcate from them. Our computat...

Zotos, Euaggelos E

2015-01-01T23:59:59.000Z

333

Transportation Demand  

Gasoline and Diesel Fuel Update (EIA)

page intentionally left blank page intentionally left blank 69 U.S. Energy Information Administration | Assumptions to the Annual Energy Outlook 2011 Transportation Demand Module The NEMS Transportation Demand Module estimates transportation energy consumption across the nine Census Divisions (see Figure 5) and over ten fuel types. Each fuel type is modeled according to fuel-specific technology attributes applicable by transportation mode. Total transportation energy consumption is the sum of energy use in eight transport modes: light-duty vehicles (cars and light trucks), commercial light trucks (8,501-10,000 lbs gross vehicle weight), freight trucks (>10,000 lbs gross vehicle weight), buses, freight and passenger aircraft, freight and passenger rail, freight shipping, and miscellaneous

334

Chombo-Crunch: Modeling Pore-Scale Reactive Transport in Carbon  

NLE Websites -- All DOE Office Websites (Extended Search)

Transient pH on calcite grains in capillary tube experiment. 1 billion grid points computed on 48K cores. 1 micron resolution. Transient pH on calcite grains in capillary tube experiment. 1 billion grid points computed on 48K cores. 1 micron resolution. Transient pH on calcite grains in capillary tube experiment. 1 billion grid points computed on 48K cores. 1 micron resolution. David Trebotich, Lawrence Berkeley National Laboratory Chombo-Crunch: Modeling Pore-Scale Reactive Transport in Carbon Sequestration PI Name: David Trebotich PI Email: treb@lbl.gov Institution: Lawrence Berkeley National Laboratory Allocation Program: INCITE Allocation Hours at ALCF: 80 Million Year: 2014 Research Domain: Earth Science Carbon sequestration, the process of capturing carbon dioxide (CO2) before it enters the atmosphere and transferring it into the earth, is a promising technique to help control greenhouse gas emissions. Researchers from the

335

Efficiency and Evolution of Water Transport Systems in Higher Plants: A Modelling Approach. II. Stelar Evolution  

Science Journals Connector (OSTI)

...July 1994 research-article Efficiency and Evolution of Water Transport Systems in Higher...protostele and siphonostele in water conduction was analysed numerically...identical with regard to water transport efficiency. The Royal Society is collaborating...

1994-01-01T23:59:59.000Z

336

Transport and seismoelectric properties of porous permeable rock : numerical modeling and laboratory measurements  

E-Print Network (OSTI)

The objective of this thesis is to better understand the transport and seismoelectric (SE) properties of porous permeable rock. Accurate information of rock transport properties, together with pore geometry, can aid us to ...

Zhan, Xin, Ph. D. Massachusetts Institute of Technology

2010-01-01T23:59:59.000Z

337

Mechanism model for shale gas transport considering diffusion, adsorption/desorption and Darcy flow  

Science Journals Connector (OSTI)

To improve the understanding of the transport mechanism in shale gas reservoirs and build a theoretical basic for ... on productivity evaluation and efficient exploitation, various gas transport mechanisms within...

Ming-qiang Wei ???; Yong-gang Duan ???

2013-07-01T23:59:59.000Z

338

Modeling regional transportation demand in China and the impacts of a national carbon constraint  

E-Print Network (OSTI)

Climate and energy policy in China will have important and uneven impacts on the countrys regionally heterogeneous transport system. In order to simulate these impacts, transport sector detail is added to a multi-sector, ...

Kishimoto, Paul

2015-01-30T23:59:59.000Z

339

Additional resonant contribution to the potential model for the 12C(alpha,gamma)16O reaction  

E-Print Network (OSTI)

The additional resonant contribution to the potential model is examined in $\\alpha$+$^{12}$C elastic scattering and the low-energy $^{12}$C($\\alpha$,$\\gamma$)$^{16}$O reaction. The excitation function of elastic scattering below $E_{c.m.}= 5$ MeV seems to be reproduced by the potential model satisfactorily, and it is not profoundly disturbed by the additional resonances. The weak coupling is good enough to describe the $^{16}$O structure in the vicinity of the $\\alpha$-particle threshold, especially below $E_{c.m.}= 8$ MeV, corresponding to the excitation energy $E_x \\approx 15$ MeV. The additional resonances give the complement of the astrophysical $S$-factors from the simple potential model. The $S$-factor of $^{12}$C($\\alpha$,$\\gamma$)$^{16}$O at $E_{c.m.}=300$ keV is dominated by the $E$2 transition, which is enhanced by the subthreshold 2$^+_1$ state at $E_x= 6.92$ MeV. The contribution from the subthreshold 1$^-_1$ state at $E_x= 7.12$ MeV is predicted to be small. The additional resonances do not give the large contribution to the thermonuclear reaction rates of $^{12}$C($\\alpha$,$\\gamma$)$^{16}$O at helium burning temperatures.

M. Katsuma

2014-04-15T23:59:59.000Z

340

Extended sum-rule model view of light and intermediate mass fragment emission in nuclear reactions at intermediate energies  

Science Journals Connector (OSTI)

The original sum-rule model worked out by Wilczy?ski et al. and successfully used for a global description of complete and incomplete fusion reactions has been extended by a term accounting for dissipative processes of the dinuclear system on its way to fusion. When applying to light- and heavy-ion collisions with various targets at energies in the transitional region, the new term proves to be rather essential for reproducing the element distributions of the fragments emitted from rather asymmetric systems.

I. M. Brncu?; H. Rebel; J. Wentz; V. Corcalciuc

1990-11-01T23:59:59.000Z

Note: This page contains sample records for the topic "reaction transport model" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Energy Dependence of Energy Partition in Products of Direct Reactions: Crossed?Beam Studies and a New Model  

E-Print Network (OSTI)

and R. E. Merrifield (unpublished). Energy Dependence of Energy Partition in Products of Direct Reactions: Crossed Beam Studies and aNew Model P. HIERL, Z. HERMAN,* J. KERSTETTER, AND R. WOLFGANG Department of Chemistry, Yale University, New Haven.... (If position of maximum intensity in c.m. system were plotted, a somewhat higher intercept Qo would result.) modes of the products, and on the dependence of this on initial kinetic energy. Results on the systems Ar++D~ArD++D, and Ar...

Hierl, Peter M.; Herman, Z.; Kerstetter, J.; Wolfgang, R.

1968-01-01T23:59:59.000Z

342

Hadron Cancer Therapy: Role of Nuclear Reactions  

DOE R&D Accomplishments (OSTI)

Recently it has become feasible to calculate energy deposition and particle transport in the body by proton and neutron radiotherapy beams, using Monte Carlo transport methods. A number of advances have made this possible, including dramatic increases in computer speeds, a better understanding of the microscopic nuclear reaction cross sections, and the development of methods to model the characteristics of the radiation emerging from the accelerator treatment unit. This paper describes the nuclear reaction mechanisms involved, and how the cross sections have been evaluated from theory and experiment, for use in computer simulations of radiation therapy. The simulations will allow the dose delivered to a tumor to be optimized, whilst minimizing the dos given to nearby organs at risk.

Chadwick, M. B.

2000-06-20T23:59:59.000Z

343

REACTIVE TRANSPORT MODELING USING A PARALLEL FULLY-COUPLED SIMULATOR BASED ON PRECONDITIONED JACOBIAN-FREE NEWTON-KRYLOV  

SciTech Connect

Systems of multicomponent reactive transport in porous media that are large, highly nonlinear, and tightly coupled due to complex nonlinear reactions and strong solution-media interactions are often described by a system of coupled nonlinear partial differential algebraic equations (PDAEs). A preconditioned Jacobian-Free Newton-Krylov (JFNK) solution approach is applied to solve the PDAEs in a fully coupled, fully implicit manner. The advantage of the JFNK method is that it avoids explicitly computing and storing the Jacobian matrix during Newton nonlinear iterations for computational efficiency considerations. This solution approach is also enhanced by physics-based blocking preconditioning and multigrid algorithm for efficient inversion of preconditioners. Based on the solution approach, we have developed a reactive transport simulator named RAT. Numerical results are presented to demonstrate the efficiency and massive scalability of the simulator for reactive transport problems involving strong solution-mineral interactions and fast kinetics. It has been applied to study the highly nonlinearly coupled reactive transport system of a promising in situ environmental remediation that involves urea hydrolysis and calcium carbonate precipitation.

Luanjing Guo; Chuan Lu; Hai Huang; Derek R. Gaston

2012-06-01T23:59:59.000Z

344

Numerical modeling of a thermohydrochemical (T-H-C) coupling and the implications to radionuclide transport.  

SciTech Connect

Thermohydrochemical (T-H-C) processes result from the placement of heat-generating radioactive materials in unsaturated, fractured geologic materials. The placement of materials in the proposed Yucca Mountain repository will result in complex environmental conditions. Simple models are developed liking the thermohydrological effects simulated with TOUGHZ to system chemistry, with an example presented for chloride. Perturbations to near-field chemistry could have a significant impact on the migration of actinides and fission products in geologic materials. Various conceptual models to represent fractures are utilized in TOUGHZ simulations of thermohydrological processes. The simulated moisture redistribution is then coupled to simple chemical models to demonstrate the potential magnitude of T-H-C processes. The concentration of chloride in solution (returning to the engineered barrier system) is demonstrated, in extreme cases, to exceed 100,000 mg/L. The implication is that the system (typically ambient chemical and hydrological conditions) in which radionuclide transport is typically simulated and measured may be significantly different from the perturbed system.

Esh, D. W.; Scheetz, B. E.

1999-09-21T23:59:59.000Z

345

Laboratory And Lysimeter Experimentation And Transport Modeling Of Neptunium And Strontium In Savannah River Site Sediments  

SciTech Connect

The Savannah River Site (SRS) conducts performance assessment (PA) calculations to determine the appropriate amount of low-level radiological waste that can be safely disposed on site. Parameters are included in these calculations that account for the interaction between the immobile solid phase and the mobile aqueous phase. These parameters are either the distribution coefficient (K{sub d} value) or the apparent solubility value (K{sub sp}). These parameters are readily found in the literature and are used throughout the DOE complex. One shortcoming of K{sub d} values is that they are only applicable to a given set of solid and aqueous phase conditions. Therefore, a given radionuclide may have several K{sub d} values as it moves between formations and comes into contact with different solids and different aqueous phases. It is expected that the K{sub d} construct will be appropriate to use for a majority of the PA and for a majority of the radionuclides. However, semi-mechanistic models would be more representative in isolated cases where the chemistry is especially transitory or the radionuclide chemistry is especially complex, bringing to bear multiple species of varying sorption tendencies to the sediment. Semi-mechanistic models explicitly accommodate the dependency of K{sub d} values, or other sorption parameters, on contaminant concentration, competing ion concentrations, pH-dependent surface charge on the adsorbent, and solute species distribution. Incorporating semi-mechanistic concepts into geochemical models is desirable to make the models more robust and technically defensible. Furthermore, these alternative models could be used to augment or validate a Kd?based DOE Order 435.1 Performance Assessment. The objectives of this study were to: 1) develop a quantitative thermodynamically-based model for neptunium sorption to SRS sediments, and 2) determine a sorption constant from an SRS 11-year lysimeter study. The modeling studies were conducted with existing data sets. The first data set used laboratory generated Np sorption data as a function of concentration (three orders of magnitude) and as a function of pH (four orders of magnitude of proton concentration). In this modeling exercise, a very simple solution was identified by assuming that all sorption occurred only to the iron oxides in the sediment and that all the added NpO{sub 4}{sup -} remained in the oxidized state and was not reduced to the Np(IV) state (as occurs rapidly with Pu(V)). With rather limited input data, very good agreement between experimental and modeling results was observed. This modeling approach would be easy to add to the PA with little additional data requirements. This model would be useful in a system where pH is expected to change greatly, such as directly beneath a grout or concrete structure. The second model discussed in the report was to derive strontium K{sub d} values from data collected in an 11-year-old field transport study. In this controlled lysimeter study, a sensitivity analysis was conducted of hydrological and chemical processes that influence contaminant transport, including diffusion coefficients, seepage velocity, and K{sub d} value. The best overall K{sub d} derived from the model fit to the data was 32 L kg{sup -1}, which was the same value that was previously measured in traditional laboratory batch sorption studies. This was an unexpected result given the differences in experimental conditions between the batch test and the lysimeter flow through test, in particular the differences between strontium adsorption and desorption processes occurring in the latter test and not in the former. There were some trends in the lysimeter strontium data that were not predicted by the K{sub d} model, which suggest that other geochemical processes are likely also controlling strontium transport. Strontium release and cation exchange are being evaluated. These results suggest that future modeling efforts (e.g., PAs) could be improved by employing a more robust semi-empirical modeling approach to transient or complex conditio

Kaplan, Daniel I.; Powell, B. A.; Miller, Todd J.

2012-09-24T23:59:59.000Z

346

An Improved Equilibrium-Kinetics Speciation Algorithm For Redox Reactions  

Open Energy Info (EERE)

Improved Equilibrium-Kinetics Speciation Algorithm For Redox Reactions Improved Equilibrium-Kinetics Speciation Algorithm For Redox Reactions In Variably Saturated Subsurface Flow Systems Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: An Improved Equilibrium-Kinetics Speciation Algorithm For Redox Reactions In Variably Saturated Subsurface Flow Systems Details Activities (0) Areas (0) Regions (0) Abstract: Reactive chemical transport occurs in a variety of geochemical environments, and over a broad range of space and time scales. Efficiency of the chemical speciation and water-rock-gas interaction calculations is important for modeling field-scale multidimensional reactive transport problems. An improved efficient model, REACT, for simulating water-rock-gas interaction under equilibrium and kinetic conditions, has been developed.

347

Influence of Transport Variables on Isospin Transport Ratios  

E-Print Network (OSTI)

The symmetry energy in the nuclear equation of state affects many aspects of nuclear astrophysics, nuclear structure, and nuclear reactions. Recent constraints from heavy ion collisions, including isospin diffusion observables, have started to put constraints on the symmetry energy below nuclear saturation density, but these constraints depend on the employed transport model and input physics other than the symmetry energy. To understand these dependencies, we study the influence of the symmetry energy, isoscaler mean field compressibility and momentum dependence, in-medium nucleon-nucleon cross sections, and light cluster production on isospin diffusion within the pBUU transport code. In addition to the symmetry energy, several uncertain issues strongly affect isospin diffusion, most notably the cross sections and cluster production. In addition, there is a difference in the calculated isospin transport ratios, depending upon whether they are computed using the isospin asymmetry of either the residue or of a...

Coupland, D D S; Tsang, M B; Danielewicz, P; Zhang, Yingxun

2011-01-01T23:59:59.000Z

348

A Numerical Study on Gaseous Reactions in Silane Pyrolysis  

Science Journals Connector (OSTI)

A simple gaseous reaction model involving 11 elementary reactions for 10 chemical species is proposed for silane and disilane pyrolyses at 550750 K; its appropriateness is examined by a calculation based on an one-dimensional nonsteady condition which includes gaseous reactions, diffusional transport and radical adsorptions. The calculated results show that the model can successfully explain the experimental behavior of a gas composition concerning the time lag of hydrogen molecule production as well as the temperature and pressure dependences of the saturated higher silane concentrations. The reaction model is applied to a SiH4H2N2 system; it predicts that dilution with hydrogen or the premixing of c.a. 4% of disilane is useful for obtaining a spatially uniform deposition rate in a flow-type CVD reactor.

Akimasa Yuuki; Yasuji Matsui; Kunihide Tachibana

1987-01-01T23:59:59.000Z

349

Full optimized reaction space model for quantum chemical reaction calculations. Definition, applications, and the IntraAtomic correlation correction extension. [H/sub 2/ exchange between ethane and ethylene; gas-phase ozonolysis  

SciTech Connect

The Full Optimized Reaction Space (FORS) model is used for the theoretical calculation of molecular potential energy surfaces involved in chemical reactions. The FORS model is applied to two polyatomic reactions: the dihydrogen exchange between ethane and etylene, and the formation and dissolution of dioxirane and dioxymethane. The former reaction is found to possess a high barrier, in spite of its symmetry allowed nature. The latter reaction involves significant configuration mixing as methylene and oxygen react to form, successively, dioxirane, dioxymethane, and hydrogen and carbon dioxide. Finally, FORS wavefunctions can be expressed in terms of a basis of antisymmetrized products of atomic state functions, using the predominantly atomic projected localized orbitals. The atoms in molecules analysis permits the incorporation of data from atomic spectra into the molecular Hamiltonian to achieve the IntraAtomic Correlation Correction (IACC). The IACC scheme is illustrated for a few small diatomics (H/sub 2/, NH, F/sub 2/), and is shown to yield more accurate results than the uncorrected FORS wavefunctions.

Schmidt, M.W.

1982-12-01T23:59:59.000Z

350

Phase I Contaminant Transport Parameters for the Groundwater Flow and Contaminant Transport Model of Corrective Action Unit 99: Rainier Mesa/Shoshone Mountain, Nevada Test Site, Nye County, Nevada, Revision 1  

SciTech Connect

This document presents a summary and framework of available transport data and other information directly relevant to the development of the Rainier Mesa/Shoshone Mountain (RMSM) Corrective Action Unit (CAU) 99 groundwater transport model. Where appropriate, data and information documented elsewhere are briefly summarized with reference to the complete documentation.

Nathan Bryant

2008-05-01T23:59:59.000Z

351

Recent Site-Wide Transport Modeling Related to the Carbon Tetrachloride Plume at the Hanford Site  

SciTech Connect

Carbon tetrachloride transport in the unconfined aquifer system at the Hanford Site has been the subject of follow-on studies since the Carbon Tetrachloride Innovative Treatment Remediation Demonstration (ITRD) Program was completed in FY 2002. These scoping analyses were undertaken to provide support for strategic planning and guidance for the more robust modeling needed to obtain a final record of decision (ROD) for the carbon tetrachloride plume in the 200 West Area. This report documents the technical approach and the results of these follow-on, site-wide scale-modeling efforts. The existing site-wide groundwater model was used in this effort. The work extended that performed as part of the ITRD modeling study in which a 200 West Area scale submodel was developed to examine arrival concentrations at an arbitrary boundary between the 200 E and 200 W areas. These scoping analyses extended the analysis to predict the arrival of the carbon tetrachloride plume at the Columbia River. The results of these analyses illustrate the importance of developing field-scale estimates of natural attenuation parameters, abiotic degradation rate and soil/water equilibrium sorption coefficient, for carbon tetrachloride. With these parameters set to zero, carbon tetrachloride concentrations will exceed the compliance limit of 5 ?g/L outside the 200 Area Plateau Waste Management Area, and the aquifer source loading and area of the aquifer affected will continue to grow until arrival rates of carbon tetrachloride equal source release rates, estimated at 33 kg/yr. Results of this scoping analysis show that the natural attenuation parameters are critical in predicting the future movement of carbon tetrachloride from the 200 West Area. Results also show the significant change in predictions between continual source release from the vadose zone and complete source removal.

Bergeron, Marcel P.; Cole, C R.

2005-11-01T23:59:59.000Z

352

Sustainable Reactions in Tunable Solvents  

Science Journals Connector (OSTI)

Sustainable Reactions in Tunable Solvents ... Molecular dynamics simulations are used to calculate several free energy profiles relevant to the recombination/dissociation and transport of individual ions and ion pairs across the water/chloroform interface. ...

Charles A. Eckert; Charles L. Liotta; David Bush; James S. Brown; Jason P. Hallett

2004-09-14T23:59:59.000Z

353

Computer Modeling of Transport of Oxidizing Species in Grain Boundaries during Zirconium Corrosion  

SciTech Connect

Zirconium (Zr) based alloys are widely used as the cladding materials in light-water reactors. The water-side corrosion of these alloys degrades their structural integrity and poses serious safety concerns. During the Zr corrosion process, a thin Zr oxide (ZrO2) layer forms on the alloy surface and serves as a barrier layer for further corrosion. The majority of the oxide has the monoclinic phase. At the transition region between the oxide and the metal, the oxide contains a thin layer of stabilized tetragonal phase. It is found that the texture of the tetragonal layer determines the protectiveness of the oxide for corrosion. The transport of oxidizing species, such as anion defects, cation defects, and electron through the tetragonal oxide layer could be the rate limiting step of the corrosion. The defect diffusion can be affected by the growing stresses and microstructures such as grain boundaries and dislocations. In this work molecular dynamics simulations are used to investigate the anion and cation diffusion in bulk and at grain boundaries in tetragonal ZrO2. The results show that defect diffusion at grain boundaries is complex and the behavior strongly depends on the grain boundary type. For most of the grain boundaries studied the defect diffusion are much slower than in the bulk, implying that grain boundaries may not be fast defect transport paths during corrosion. The connection between the modeling results and published experimental work will also be discussed. This work is funded by the Laboratory Directed Research and Development (LDRD) program at Idaho National Laboratory.

Xian-Ming Bai; Yongfeng Zhang; Michael R. Tonks

2014-06-01T23:59:59.000Z

354

PHYSICAL REVIEW B 88, 144305 (2013) Two-channel model for nonequilibrium thermal transport in pump-probe experiments  

E-Print Network (OSTI)

150 nm of the Al/Si0.99Ge0.01 interface. The extra thermal resistance in this region is a result. INTRODUCTION The magnitude of a material's thermal conductivity and spe- cific heat is determinedPHYSICAL REVIEW B 88, 144305 (2013) Two-channel model for nonequilibrium thermal transport in pump

Cahill, David G.

355

Solutions of burnt-bridge models for molecular motor transport Alexander Yu. Morozov, Ekaterina Pronina, and Anatoly B. Kolomeisky  

E-Print Network (OSTI)

Solutions of burnt-bridge models for molecular motor transport Alexander Yu. Morozov, Ekaterina consecutive binding sites called "bridges" , is investigated theoretically by analyzing discrete-state stochastic "burnt-bridge" mod- els. When an unbiased diffusing particle crosses the bridge, the link can

356

TWO-DIMENSIONAL REACTIVE TRANSPORT MODELING OF CO2 INJECTION IN A SALINE AQUIFER AT THE SLEIPNER SITE  

E-Print Network (OSTI)

. To ensure safety, a low permeable formation, called the cap rock, is required on the top of the storage zone in the brine, and geochemical reactions with the host rock are considered in the model. Two mineralogical assemblages are considered in the Utsira formation, a sand formation that is highly permeable and a shale

Boyer, Edmond

357

Comparison of unsaturated flow and solute transport through waste rock at two experimental scales using temporal moments and numerical modeling  

Science Journals Connector (OSTI)

Abstract This study analyzed and compared unsaturated flow response and tracer breakthrough curves from a 10-m high constructed pile experiment (CPE) in the field (Antamina, Peru) and two 0.8m high laboratory-based columns. Similar materials were used at both experimental scales, with the exception of a narrower grain size distribution range for the smaller column tests. Observed results indicate flow and solute transport regimes between experimental scales were comparable, dominated by flow and solute migration through granular matrix materials. These results are supported by: analogous breakthrough curves (normalized to cross-sectional area and flow path length) that suggest observation- or smaller- scale heterogeneities within the porous media have been homogenized or smoothed at the transport-scale, long breakthrough tails, and similar recovered tracer mass fractions (i.e., 0.72 0.80) at the end of the experiment. CPE breakthrough curves do indicate a portion of the fluid flow follows rapid flow paths (open void or film flow); however, this portion accounts for a minor (i.e., ~0.1%) component of the overall flow and transport regime. Flow-corrected temporal moment analysis was used to estimate flow and transport parameter values, however large temporal variations in flow indicate this method is better suited for conceptualizing transport regimes. In addition, a dual-porosity mobile-immobile (MIM), rate-limited mass-transfer approach was able to simulate tracer breakthrough and the dominant transport regimes from both scales. Dispersivity values used in model simulations reflect a scale-dependency, whereby column values were approximately 2x smaller than those values applied in CPE simulations. The mass-transfer coefficient, for solute transport between mobile and immobile regions, was considered as a model calibration factor. Column experiments are characterized by a larger mobile to immobile porosity ratio and a shorter experimental duration and flow path, which supports larger mass-transfer coefficient values (relative to the CPE). These results demonstrate that laboratory-based experiments may be able to mimic flow regimes observed in the field; however, the requirement of scale-dependent dispersivities and in particular mass-transfer coefficients indicates these tests may be more limited in understanding larger-scale solute transport between regions of different mobility. Nevertheless, the results of this study suggest that the reasonably simplistic modeling approaches utilized in this study may be applied at other field sites to estimate parameters and conceptualize dominant transport processes through highly heterogeneous, unsaturated material.

Sharon Blackmore; Leslie Smith; K. Ulrich Mayer; Roger D. Beckie

2014-01-01T23:59:59.000Z

358

A fundamental study of model fuel conversion reactions in sub and supercritical water  

E-Print Network (OSTI)

Model reactants under hydrothermal conditions were examined to improve our understanding of chemical transformations in this high temperature and pressure environment. Results have a direct impact on present and future ...

Lachance, Russell Philip

2005-01-01T23:59:59.000Z

359

Use of Rough Sets and Spectral Data for Building Predictive Models of Reaction Rate Constants  

Science Journals Connector (OSTI)

A model for predicting the log of the rate constants for alkaline hydrolysis of organic esters has been developed with the use of gas-phase mid-infrared library spectra and a...

Collette, Timothy W; Szladow, Adam J

1994-01-01T23:59:59.000Z

360

Direct Insertion of MODIS Radiances in a Global Aerosol Transport Model CLARK WEAVER,* ARLINDO DA SILVA, MIAN CHIN,# PAUL GINOUX,@ OLEG DUBOVIK,&,@@  

E-Print Network (OSTI)

is directly inserted into the Goddard Chemistry and Aerosol Radiation Transport model (GOCART), which aerosol radiative forcing in the thermody- namic equation of GCMs, 3) to account for the reduc- tionDirect Insertion of MODIS Radiances in a Global Aerosol Transport Model CLARK WEAVER,* ARLINDO DA

Chin, Mian

Note: This page contains sample records for the topic "reaction transport model" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Evaluation of Atmospheric Transport Models for Use in Phase II of the Historical Public Exposures Studies at the Rocky Flats Plant  

Science Journals Connector (OSTI)

Five atmospheric transport models were evaluated for use in Phase II of the Historical Public Exposures Studies at the Rocky Flats Plant. Models included a simple straight-line ... hexafluoride tracer measurement...

Arthur S. Rood; George G. Killough; John E. Till

1999-08-01T23:59:59.000Z

362

Uncertainties in modeling low-energy neutrino-induced reactions on iron-group nuclei  

Science Journals Connector (OSTI)

Charged-current neutrino-nucleus cross sections for 54,56Fe and 58,60Ni are calculated and compared using frameworks based on relativistic and Skyrme energy-density functionals and on the shell model. The current theoretical uncertainties in modeling neutrino-nucleus cross sections are assessed in relation to the predicted Gamow-Teller transition strength and available data, to multipole decomposition of the cross sections, and to cross sections averaged over the Michel flux and Fermi-Dirac distribution. By employing different microscopic approaches and models, the decay-at-rest (DAR) neutrino-56Fe cross section and its theoretical uncertainty are estimated to be ???th=(25857)10?42cm2, in very good agreement with the experimental value ???exp=(25610843)10?42cm2.

N. Paar; T. Suzuki; M. Honma; T. Marketin; D. Vretenar

2011-10-31T23:59:59.000Z

363

A model of the generation and transport of ozone in high-tension nozzle driven corona inside a novel diode  

SciTech Connect

The genesis and transport of ozone (O{sub 3}) are investigated in a novel plasma diode and described in this paper. The innovative cathode (K) of this axial symmetric diode which operated at the high voltage ({phi}{sub 0}), has a large number of sharpened nozzles located on different radial planes of its central tubular-mast and is encircled by the anode (A). The nozzles played the dual role of oxygen (O{sub 2}) injection as well as creation of high electric field (E) in the A-K gap, enabled the formation of a cold corona. Electrons in the corona under the influence of E moved towards anode, collided with O{sub 2} and created the O radicals. O in turn joined the free O{sub 2} and formed O{sub 3}. The evolution of O{sub 3} here is modeled in various O{sub 2} pressure (P), electron density (n{sub e}), and temperature (T) in terms of the major reaction modes involving e, O, O{sub 2}, and O{sub 3}. Typical steady state O{sub 3} density attained so in P {approx} bar, n{sub e}{approx} 10{sup 15} m{sup -3} and T{approx} 300 K is over 10{sup 25} m{sup -3} and that of O lower {approx}10{sup 20} m{sup -3}. Both the O and O{sub 3} densities increased with an enhanced n{sub e} of avalanche multiplications in corona. O{sub 3} increased also with a higher P but the temporal O reversed in trend midway and reduced with P towards the steady state. A sharp decline in diode resistance with smaller A-K gap induced finite discharge current and led to the undesired heating of corona. It is shown that the O{sub 3} density reduced with the temperature rise but O density reduced with the T rise up to 500 K and then rose modestly with the further T increase.

Vijayan, T.; Patil, Jagadish G. [Pillai's Institute of Information Technology, Engineering, Media Studies and Research (PIIT), Dr. K. M. Vasudevan Pillai's Campus, Sector 16, New Panvel, Navi Mumbai 410206 (India)

2012-12-15T23:59:59.000Z

364

Modeling of photolysis and hydroxyl radical reactions of 1,1,1-trichloroethane using multi-wavelength UV sources  

SciTech Connect

A process for the photolysis of hydrogen peroxide (UV/H{sub 2}O{sub 2}) is being used for the oxidation of organic chemicals in contaminated groundwater, surface water, and wastewaters. Models of the UV/H{sub 2}O{sub 2} process are available, although restricted to a single wavelength (usually 254 nm) UV source. In practice, lamps used in many environmental applications are high output multi-wavelength lamps, often medium pressure mercury vapor lamps. In this work, a model was developed for solving simultaneous multi-wavelength photolysis and radical reactions of the UV/H{sub 2}O{sub 2} system with a single substrate (1,1,1-trichloroethane) and its by-products. Micromath Scientist, a data handling software package, was used as a platform to build the computer model. The program integrates changing photolysis rates of the major light absorbing species as their relative concentrations change into a system for solving simultaneous ordinary differential equations (ODEs). Thus, the photolysis rates were dynamically linked to the mechanism solver. Experimental data are compared to model simulations, and cost comparisons for single and multi-wavelength treatments are computed.

Loraine, G.A.; Glaze, W.H. [Univ. of North Carolina, Chapel Hill, NC (United States)

1995-12-31T23:59:59.000Z

365

Semiclassical Distorted Wave Model Analysis of Backward Proton Emission from $(p,p^{\\prime}x)$ Reactions at Intermediate Energies  

E-Print Network (OSTI)

A semiclassical distorted wave (SCDW) model with Wigner transform of one-body density matrix is presented for multistep direct $(p,p^{\\prime}x)$ reactions to the continuum. The model uses Wigner distribution functions obtained in methods which include nucleon-nucleon correlations to a different extent, as well as Woods-Saxon (WS) single-particle wave function. The higher momentum components of target nucleons that play a crucial role in reproducing the high-energy part of the backward proton spectra are properly taken into account. This SCDW model is applied to analyses of multistep direct processes in $^{12}$C$(p,p^{\\prime}x)$, $^{40}$Ca$(p,p^{\\prime}x)$ and $^{90}$Zr$(p,p^{\\prime}x)$ in the incident energy range of 150--392 MeV. The double differential cross sections are calculated up to three-step processes. The calculated angular distributions are in good agreement with the experimental data, in particular at backward angles where the previous SCDW calculations with the WS single-particle wave function showed large underestimation. It is found that the result with the Wigner distribution function based on the coherent density fluctuation model provides overall better agreement with the experimental data over the whole emission energies.

M. K. Gaidarov; Y. Watanabe; K. Ogata; M. Kohno; M. Kawai; A. N. Antonov

2003-07-28T23:59:59.000Z

366

Orientational effects in the direct Cl? + \\{CH3Cl\\} SN2 reaction at elevated collision energies: hard-ovoid line-of-centers collision model  

Science Journals Connector (OSTI)

The hard-sphere line-of-centers collision model can be extended analytically to include the orientational dependence of both the energy barrier and the critical distance of approach. This hard-ovoid line-of-centers model is applied to the translational activation of the bimolecular nucleophilic substitution (SN2) reaction, Cl? + \\{CH3Cl\\} ? ClCH3 + Cl?, for which a direct reaction mechanism was found in recent classical trajectory calculations. The model is compared with recent experiments and the classical trajectory calculations.

Kent M Ervin

1999-01-01T23:59:59.000Z

367

Finite-size effects in kinetic phase transitions of a model reaction on a fractal surface: Scaling approach and Monte Carlo investigation  

Science Journals Connector (OSTI)

Finite-size effects in kinetic (irreversible) phase transitions, from reactive to poisoned states, occurring in model reactions are interpreted with the aid of a phenomenological scaling approach. The proposed arguments are tested by computer simulations of a model for the oxidation of carbon monoxide on a fractal surface. The critical exponents of the transitions displayed by the model and the exponents for the transient period of the reaction at criticality are evaluated. A crossover from a reactive steady state to a regime where the surface could be poisoned by each of the reactants is found and discussed.

Ezequiel V. Albano

1990-12-01T23:59:59.000Z

368

Reaction times for user behavior models in microblogging online social networks  

Science Journals Connector (OSTI)

Online Social Networks (OSNs) have, in recent years, emerged as a new way to communicate, diffuse information, coordinate people, establish relationships, among other possibilities. In this context, being able to understand and predict how users behave ... Keywords: microblogging, modeling, online social network, simulation

Samuel Martins Barbosa Neto; Maira Athanazio De Cerqueira Gatti; Paulo Rodrigo Cavalin; Claudio Santos Pinhanez; Cicero Nogueira Dos Santos; Ana Paula Appel

2013-10-01T23:59:59.000Z

369

Wave transport for a scalar model of the Love waves Guillaume Bal Leonid Ryzhik y  

E-Print Network (OSTI)

of the wavelength. The transport equation accounts for the multiple scattering of the Love waves analyzed using radiative transfer equations for more than thirty years [5, 6, 7, 8, 14]. A systematic and e?cient way to obtain transport equations is presented in [16, 18]. The mathematics involved in this process

Ryzhik, Lenya

370

Wave transport for a scalar model of the Love waves Guillaume Bal Leonid Ryzhik \\Lambda  

E-Print Network (OSTI)

of the wavelength. The transport equation accounts for the multiple scattering of the Love waves using radiative transfer equations for more than thirty years [5, 6, 7, 8, 14]. A systematic and efficient way to obtain transport equations is presented in [16, 18]. The mathematics involved

Bal, Guillaume

371

Cahn-Hilliard Reaction Model for Isotropic Li-ion Battery Particles Yi Zeng1, Martin Z. Bazant1,2  

E-Print Network (OSTI)

Cahn-Hilliard Reaction Model for Isotropic Li-ion Battery Particles Yi Zeng1, Martin Z. Bazant1,2 1 particle. This general approach extends previous Li-ion battery models, which either neglect phase theory for Li-ion batteries [13, 18] with Butler-Volmer kinetics and concentration depen- dent

Bazant, Martin Z.

372

Waste area Grouping 2 Phase I remedial investigation: Sediment and Cesium-137 transport modeling report  

SciTech Connect

This report is one of five reports issued in 1996 that provide follow-up information to the Phase I Remedial Investigation (RI) Report for Waste Area Grouping (WAG) 2 at Oak Ridge National Laboratory (ORNL). The five reports address areas of concern that may present immediate risk to public health at the Clinch River and ecological risk within WAG 2 at ORNL. A sixth report, on groundwater, in the series documenting WAG 2 RI Phase I results were part of project activities conducted in FY 1996. The five reports that complete activities conducted as part of Phase I of the Remedial Investigation (RI) for WAG 2 are as follows: (1) Waste Area Grouping 2, Phase I Task Data Report: Seep Data Assessment, (2) Waste Area Grouping 2, Phase I Task Data Report: Tributaries Data Assessment, (3) Waste Area Grouping 2, Phase I Task Data Report: Ecological Risk Assessment, (4) Waste Area Grouping 2, Phase I Task Data Report: Human Health Risk Assessment, (5) Waste Area Grouping 2, Phase I Task Data Report: Sediment and {sup 137}Cs Transport Modeling In December 1990, the Remedial Investigation Plan for Waste Area Grouping 2 at Oak Ridge National Laboratory was issued (ORNL 1990). The WAG 2 RI Plan was structured with a short-term component to be conducted while upgradient WAGs are investigated and remediated, and a long-term component that will complete the RI process for WAG 2 following remediation of upgradient WAGs. RI activities for the short-term component were initiated with the approval of the Environmental Protection Agency, Region IV (EPA), and the Tennessee Department of Environment and Conservation (TDEC). This report presents the results of an investigation of the risk associated with possible future releases of {sup 137}Cs due to an extreme flood. The results are based on field measurements made during storms and computer model simulations.

Clapp, R.B.; Bao, Y.S.; Moore, T.D.; Brenkert, A.L.; Purucker, S.T.; Reece, D.K.; Burgoa, B.B.

1996-06-01T23:59:59.000Z

373

Numerical modeling of deep groundwater flow and heat transport in the Williston Basin  

SciTech Connect

A numerical modeling approach has been used to evaluate quantitatively the effects of fluid flow on contemporary heat flow in an intracratonic basin. The authors have selected the Williston basin for this hydrodynamic study because of the opportunity it presents to assess the relation of deep groundwater flow to basin geothermics and the associated features of diagenesis and petroleum accumulation. The finite element method is used to solve the coupled equations of fluid flow and heat transport in two-dimensional sections of the basin. Both the fluid- and heat-flow regime are assumed to be at steady state, and the fluid flow is driven primarily by the water-table relief which is taken to be a subdued replica of land-surface topography. Buoyancy forces may also affect flow through fluid density gradients created by temperature and salinity effects. Three southwest-northwest oriented sections across the basin were modeled using available and estimated parameter data. The predicted flow patterns are most strongly affected by the topography, but the Devonian salt unit and Cretaceous shale unit exert some control. Cross-formational flow is especially important near the downdip, solution edge of the salt beds. Flow rates rarely exceed 0.5 m/year in the deep-central part of the basin, yet there does exist a marked effect on heat flow, albeit subdued by the blanket effect of the low-permeability Cretaceous shales. The regional effect of the topography-driven flow system is reflected in present-day salinity patterns and heat-flow data.

Garven, G.; Vigrass, L.

1985-01-01T23:59:59.000Z

374

Improving the {sup 33}S(p,{gamma}){sup 34}Cl Reaction Rate for Models of Classical Nova Explosions  

SciTech Connect

Reduced uncertainty in the thermonuclear rate of the {sup 33}S(p,{gamma}){sup 34}Cl reaction would help to improve our understanding of nucleosynthesis in classical nova explosions. At present, models are generally in concordance with observations that nuclei up to roughly the calcium region may be produced in these explosive phenomena; better knowledge of this rate would help with the quantitative interpretation of nova observations over the S-Ca mass region, and contribute towards the firm establishment of a nucleosynthetic endpoint. As well, models find that the ejecta of nova explosions on massive oxygen-neon white dwarfs may contain as much as 150 times the solar abundance of {sup 33}S. This characteristic isotopic signature of a nova explosion could possibly be observed through the analysis of microscopic grains formed in the environment surrounding a nova and later embedded within primitive meteorites. An improved {sup 33}S(p,{gamma}){sup 34}Cl rate (the principal destruction mechanism for {sup 33}S in novae) would help to ensure a robust model prediction for the amount of {sup 33}S that may be produced. Finally, constraining this rate could confirm or rule out the decay of an isomeric state of {sup 34}Cl(E{sub x} = 146 keV, t{sub 1/2} = 32 m) as a source for observable gamma-rays from novae. We have performed several complementary experiments dedicated to improving our knowledge of the {sup 33}S(p,{gamma}){sup 34}Cl rate, using both indirect methods (measurement of the {sup 34}S({sup 3}He,t){sup 34}Cl and {sup 33}S({sup 3}He,d){sup 34}Cl reactions with the Munich Q3D spectrograph) and direct methods (in normal kinematics at CENPA, University of Washington, and in inverse kinematics with the DRAGON recoil mass separator at TRIUMF). Our results will be used with nova models to facilitate comparisons of model predictions with present and future nova observables.

Parikh, A.; Faestermann, Th.; Kruecken, R.; Bildstein, V.; Bishop, S.; Eppinger, K.; Herlitzius, C.; Lepyoshkina, O.; Maierbeck, P.; Seiler, D.; Wimmer, K. [Physik Department E12, Technische Universitaet Muenchen, D-85748, Garching (Germany); Hertenberger, R.; Wirth, H.-F. [Fakultaet fuer Physik, Ludwig-Maximilians-Universitaet Muenchen, D-85748 Garching (Germany); Fallis, J.; Hager, U.; Hutcheon, D.; Ruiz, Ch.; Buchmann, L.; Ottewell, D. [TRIUMF, Vancouver, BC, V6T 2A3 (Canada); Freeman, B. [Center for Experimental Nuclear Physics and Astrophysics, University of Washington, Seattle, WA 98195 (United States)

2011-10-28T23:59:59.000Z

375

A comparative study of vibrational relaxation and chemical reaction models for the Martian entry vehicle  

E-Print Network (OSTI)

different chemistry sets and rates. The analyses have been carried out at an altitude of 50. 1 km and at speeds of 7. 387 km/sec and 8. 0 km/sec. The results indicate that the flow is in a highly nonequilibrium state. Due to the rapid dissociation of CO...: QUANTUM MECHANICAL PROPERTIES VITA 133 136 LIST OF TABLES Page 1. Temperature Models studied at 7. 387 km/sec, 53 2. Heat Transfer Rates at the Wall for Non-catalytic and Partially Catalytic Walls . 94 3. Thermodynamic Properties of the Species 4...

Koteshwar, Rajeev

1992-01-01T23:59:59.000Z

376

Preliminary model for heat transport within a tongue-and-reservoir liquid diode for passive solar heating  

SciTech Connect

A preliminary model is presented for heat transport within a tongue-and-reservoir liquid diode for passive solar heating. The diode consists of a rectangular vertical slot (tongue) extending from the bottom of a rectangular-shaped reservoir at the reservoir's front face. Water is used as the working fluid in the tongue and reservoir. Solar radiation is incident on the front face of the tongue, which also loses heat to the outside, while radiation and convection transport heat from the back of the reservoir to the building. Convection transports heat when the tongue is irradiated; however, when convection ceases and the temperature of the tongue cools below that of the reservoir (from exposure to the outside temperature), the reservoir stratifies, and the primary heat loss mechanism is conduction through the tongue and its fluid. The result is a passive solar component that may outperform most others. Flow in the tongue is treated as boundary layer flow; the integral forms of the governing equations are combined to form a single equation governing the local boundary layer thickness. The results are shown to depend upon the Grashof, Prandtl, and heat-loss Biot numbers. Results from this model agree well with those from our flow visualization experiments. A model is also proposed for diode heat transport processes during cool-down. In this model, and empirical coefficient accounts for the weak convective mixing that occurs in the reservoir during this phase. Preliminary results indicate the coefficient to be spatially dependent but independent of time and reservoir temperature. More experiments are planned to further validate both of the models described above.

Jones, G.F.

1984-01-01T23:59:59.000Z

377

Energy-transfer and charge-separation pathways in the reaction center of photosystem II revealed by coherent two-dimensional optical  

E-Print Network (OSTI)

of pigment-protein reaction-center RC complexes is the first energy conversion step in photosynthesisEnergy-transfer and charge-separation pathways in the reaction center of photosystem II revealed-band tight-binding model. The dissipative exciton and charge carrier motions are calculated using a transport

Mukamel, Shaul

378

Phase transitions in a reaction-diffusion model on a line with boundaries  

SciTech Connect

A one-dimensional model on a line of length L is investigated, which involves particle diffusion as well as single particle annihilation. There are also creation and annihilation at the boundaries. The static and dynamical behaviors of the system are studied. It is seen that the system could exhibit a dynamical phase transition. For small drift velocities, the relaxation time does not depend on the absorption rates at the boundaries. This is the fast phase. For large velocities, the smaller of the absorption rates at boundaries enter the relaxation rate and makes it longer. This is the slow phase. Finally, the effect of a random particle creation in the bulk is also investigated.

Khorrami, Mohammad, E-mail: mamwad@mailaps.org; Aghamohammadi, Amir, E-mail: mohamadi@alzahra.ac.ir [Department of Physics, Alzahra University, Tehran 19938-93973 (Iran, Islamic Republic of)] [Department of Physics, Alzahra University, Tehran 19938-93973 (Iran, Islamic Republic of)

2014-03-15T23:59:59.000Z

379

Phase I Contaminant Transport Parameters for the Groundwater Flow and Contaminant Transport Model of Corrective Action Unit 97: Yucca Flat/Climax Mine, Nevada Test Site, Nye County, Nevada, Revision 0  

SciTech Connect

This report documents transport data and data analyses for Yucca Flat/Climax Mine CAU 97. The purpose of the data compilation and related analyses is to provide the primary reference to support parameterization of the Yucca Flat/Climax Mine CAU transport model. Specific task objectives were as follows: Identify and compile currently available transport parameter data and supporting information that may be relevant to the Yucca Flat/Climax Mine CAU. Assess the level of quality of the data and associated documentation. Analyze the data to derive expected values and estimates of the associated uncertainty and variability. The scope of this document includes the compilation and assessment of data and information relevant to transport parameters for the Yucca Flat/Climax Mine CAU subsurface within the context of unclassified source-term contamination. Data types of interest include mineralogy, aqueous chemistry, matrix and effective porosity, dispersivity, matrix diffusion, matrix and fracture sorption, and colloid-facilitated transport parameters.

John McCord

2007-09-01T23:59:59.000Z

380

Pore-scale modeling of electrical and fluid transport in Berea sandstone  

E-Print Network (OSTI)

The purpose of this paper is to test how well numerical calculations can predict transport properties of porous permeable rock, given its 3D digital microtomography (?CT) image. For this study, a Berea 500 sandstone sample ...

Zhan, Xin

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381

A geostatistical modeling study of the effect of heterogeneity on radionuclide transport in the  

E-Print Network (OSTI)

in the unsaturated zone, Yucca Mountain Hari S. Viswanathan*, Bruce A. Robinson, Carl W. Gable, James W. Carey Earth to contaminant transport in the unsaturated zone of Yucca Mountain. However, zeolitically altered areas are lower

Gable, Carl W.

382

Transportation Secure Data Center: Real-World Data for Planning, Modeling and Analysis (Fact Sheet)  

SciTech Connect

The National Renewable Energy Laboratory (NREL) and the U.S. Department of Transportation (DOT) have launched the free, web-based Transportation Secure Data Center (TSDC). The TSDC (www.nrel.gov/tsdc) preserves respondent anonymity while making vital transportation data available to a broad group of users through secure, online access. The TSDC database gives, metropolitan planning organizations, universities, national laboratories, air quality management districts, disaster planning agencies and auto manufacturers free-of-charge web-based access to valuable transportation data. The TSDC's two levels of access make composite data available with simple online registration, and allow researchers to use detailed spatial data after completing a straight forward application process.

Not Available

2013-01-01T23:59:59.000Z

383

Transportation Secure Data Center: Real-World Data for Planning, Modeling, and Analysis (Fact Sheet)  

SciTech Connect

This fact sheet describes the Transportation Secure Data Center (TSDC) - an NREL-operated resource that provides secure access to detailed GPS travel data for valuable research purposes in a way that protects original participant privacy.

Not Available

2014-01-01T23:59:59.000Z

384

An Episodic Transit Time Model for Quantification of Preferential Solute Transport  

Science Journals Connector (OSTI)

...preferential leaching of agrochemicals. The approach needs to...Preferential transport of agrochemicals through soil macropores...showed that the mean isotopic composition of soil water throughflow...preferential leaching of agrochemicals. The evaluation of the...

Mats Larsbo

385

Computations and modeling of oil transport between piston lands and liner in internal combustion engines  

E-Print Network (OSTI)

The consumption of lubricating oil in internal combustion engines is a continuous interest for engine developers and remains to be one of the least understood areas. A better understanding on oil transport is critical to ...

Fang, Tianshi

2014-01-01T23:59:59.000Z

386

Subsurface Uranium Fate and Transport: Integrated Experiments and Modeling of Coupled Biogeochemical Mechanisms of Nanocrystalline Uraninite Oxidation by Fe(III)-(hydr)oxides - Project Final Report  

SciTech Connect

Subsurface bacteria including sulfate reducing bacteria (SRB) reduce soluble U(VI) to insoluble U(IV) with subsequent precipitation of UO2. We have shown that SRB reduce U(VI) to nanometer-sized UO2 particles (1-5 nm) which are both intra- and extracellular, with UO2 inside the cell likely physically shielded from subsequent oxidation processes. We evaluated the UO2 nanoparticles produced by Desulfovibrio desulfuricans G20 under growth and non-growth conditions in the presence of lactate or pyruvate and sulfate, thiosulfate, or fumarate, using ultrafiltration and HR-TEM. Results showed that a significant mass fraction of bioreduced U (35-60%) existed as a mobile phase when the initial concentration of U(VI) was 160 M. Further experiments with different initial U(VI) concentrations (25 - 900 ?M) in MTM with PIPES or bicarbonate buffers indicated that aggregation of uraninite depended on the initial concentrations of U(VI) and type of buffer. It is known that under some conditions SRB-mediated UO2 nanocrystals can be reoxidized (and thus remobilized) by Fe(III)-(hydr)oxides, common constituents of soils and sediments. To elucidate the mechanism of UO2 reoxidation by Fe(III) (hydr)oxides, we studied the impact of Fe and U chelating compounds (citrate, NTA, and EDTA) on reoxidation rates. Experiments were conducted in anaerobic batch systems in PIPES buffer. Results showed EDTA significantly accelerated UO2 reoxidation with an initial rate of 9.5?M day-1 for ferrihydrite. In all cases, bicarbonate increased the rate and extent of UO2 reoxidation with ferrihydrite. The highest rate of UO2 reoxidation occurred when the chelator promoted UO2 and Fe(III) (hydr)oxide dissolution as demonstrated with EDTA. When UO2 dissolution did not occur, UO2 reoxidation likely proceeded through an aqueous Fe(III) intermediate as observed for both NTA and citrate. To complement to these laboratory studies, we collected U-bearing samples from a surface seep at the Rifle field site and have measured elevated U concentrations in oxic iron-rich sediments. To translate experimental results into numerical analysis of U fate and transport, a reaction network was developed based on Sani et al. (2004) to simulate U(VI) bioreduction with concomitant UO2 reoxidation in the presence of hematite or ferrihydrite. The reduction phase considers SRB reduction (using lactate) with the reductive dissolution of Fe(III) solids, which is set to be microbially mediated as well as abiotically driven by sulfide. Model results show the oxidation of HS by Fe(III) directly competes with UO2 reoxidation as Fe(III) oxidizes HS preferentially over UO2. The majority of Fe reduction is predicted to be abiotic, with ferrihydrite becoming fully consumed by reaction with sulfide. Predicted total dissolved carbonate concentrations from the degradation of lactate are elevated (log(pCO2) ~ 1) and, in the hematite system, yield close to two orders-of-magnitude higher U(VI) concentrations than under initial carbonate concentrations of 3 mM. Modeling of U(VI) bioreduction with concomitant reoxidation of UO2 in the presence of ferrihydrite was also extended to a two-dimensional field-scale groundwater flow and biogeochemically reactive transport model for the South Oyster site in eastern Virginia. This model was developed to simulate the field-scale immobilization and subsequent reoxidation of U by a biologically mediated reaction network.

Peyton, Brent M. [Montana State University; Timothy, Ginn R. [University of California Davis; Sani, Rajesh K. [South Dakota School of Mines and Technology

2013-08-14T23:59:59.000Z

387

Phase II Transport Model of Corrective Action Unit 98: Frenchman Flat, Nevada Test Site, Nye County, Nevada, Revision 1  

SciTech Connect

This document, the Phase II Frenchman Flat transport report, presents the results of radionuclide transport simulations that incorporate groundwater radionuclide transport model statistical and structural uncertainty, and lead to forecasts of the contaminant boundary (CB) for a set of representative models from an ensemble of possible models. This work, as described in the Federal Facility Agreement and Consent Order (FFACO) Underground Test Area (UGTA) strategy (FFACO, 1996; amended 2010), forms an essential part of the technical basis for subsequent negotiation of the compliance boundary of the Frenchman Flat corrective action unit (CAU) by Nevada Division of Environmental Protection (NDEP) and National Nuclear Security Administration Nevada Site Office (NNSA/NSO). Underground nuclear testing via deep vertical shafts was conducted at the Nevada Test Site (NTS) from 1951 until 1992. The Frenchman Flat area, the subject of this report, was used for seven years, with 10 underground nuclear tests being conducted. The U.S. Department of Energy (DOE), NNSA/NSO initiated the UGTA Project to assess and evaluate the effects of underground nuclear tests on groundwater at the NTS and vicinity through the FFACO (1996, amended 2010). The processes that will be used to complete UGTA corrective actions are described in the Corrective Action Strategy in the FFACO Appendix VI, Revision No. 2 (February 20, 2008).

Gregg Ruskuaff

2010-01-01T23:59:59.000Z

388

A mixed SOC-turbulence model for nonlocal transport and Levy-fractional Fokker-Planck equation  

E-Print Network (OSTI)

The phenomena of nonlocal transport in magnetically confined plasma are theoretically analyzed. A hybrid model is proposed, which brings together the notion of inverse energy cascade, typical of drift-wave- and two-dimensional fluid turbulence, and the ideas of avalanching behavior, associable with self-organized critical (SOC) behavior. Using statistical arguments, it is shown that an amplification mechanism is needed to introduce nonlocality into dynamics. We obtain a consistent derivation of nonlocal Fokker-Planck equation with space-fractional derivatives from a stochastic Markov process with the transition probabilities defined in reciprocal space. The hybrid model observes the Sparre Andersen universality and defines a new universality class of SOC.

Alexander V. Milovanov; Jens Juul Rasmussen

2014-03-24T23:59:59.000Z

389

Electron transport modeling and energy filtering for efficient thermoelectric Mg2Si1?xSnx solid solutions  

Science Journals Connector (OSTI)

We present a comprehensive electron transport model to analyze thermoelectric properties of both n- and p-type bulk Mg2Si1?xSnx (0?x?1) solid solutions. A temperature-dependent multiparabolic bands model is used to describe the band structures of the alloys, and the transport properties are calculated using the linearized Boltzmann transport equations under the relaxation time approximation. A variety of experimental data from literature are fitted very well by this model and analyzed for further material optimization. Our analysis shows that the compositions of x = 0.6 to 0.7 exhibit the highest thermoelectric figure of merit zT among n-type Mg2Si1?xSnx in the midtemperature range 600 to 900 K due to both the high power factors achieved by the convergence of the two conduction bands and low electronic thermal conductivities. For the p-type materials, we find that the bipolar electronic thermal conductivity is a major factor limiting the figure of merit. Low Sn content (x?p-type materials due mainly to their lower bipolar thermal conductivities with larger band gaps. Finally, we propose that hot carrier energy filtering can be very useful for these alloys as it can simultaneously reduce the electronic thermal conductivity and enhance the power factor. A zT greater than 3 is possible for n-type Mg2Si0.4Sn0.6 (x = 0.6) at 700 K, if electrons with energies lower than 0.4 eV are effectively prevented from participating in transport.

Je-Hyeong Bahk; Zhixi Bian; Ali Shakouri

2014-02-05T23:59:59.000Z

390

ZINC CHLORIDE-CATALYZED REACTIONS OF OXYGEN- AND SULFUR-CONTAINING COMPOUNDS WITH MODEL STRUCTURES IN COAL  

E-Print Network (OSTI)

by: thiophene (Aldrich), tetrahydrothiophene (MCB) , andresult in observable reaction products. TetrahydrothiopheneTetrahydrothiophene was found to be thermally stable at 325

Mobley, David Paul

2013-01-01T23:59:59.000Z

391

Numerical modeling of mixed sediment resuspension, transport, and deposition during the March 1998 episodic events in southern Lake Michigan  

SciTech Connect

A two-dimensional sediment transport model capable of simulating sediment resuspension of mixed (cohesive+noncohesive) sediment is developed and applied to quantitatively simulate the March 1998 resuspension events in southern Lake Michigan. Some characteristics of the model are the capability to incorporate several floc size classes, a physically-based settling velocity formula, bed armoring, and sediment availability limitation. Important resuspension parameters were estimated from field and laboratory measurement data. The model reproduced the resuspension plume (observed by the SeaWIFS satellite and field instruments) and recently measured sedimentation rate distribution (using radiotracer techniques) fairly well. Model results were verified with field measurements of suspended sediment concentration and settling flux (by ADCPs and sediment traps). Both wave conditions and sediment bed properties (critical shear stress, fine sediment fraction, and limited sediment availability or source) are the critical factors that determine the concentration distribution and width of the resuspension plume. The modeled sedimentation pattern shows preferential accumulation of sediment on the eastern side of the lake, which agrees with the observed sedimentation pattern despite a predominance of particle sources from the western shoreline. The main physical mechanisms determining the sedimentation pattern are 1) the two counter-rotating circulation gyres producing offshore mass transport along the southeastern coast during northerly wind and 2) the settling velocity of sediment flocs which controls the deposition location.

Lee, Cheegwan; Schwab, David J.; Beletsky, Dmitry; Stroud, Jonathan; Lesht, B. M.

2007-02-17T23:59:59.000Z

392

Numerical modeling of mixed sediment resuspension, transport, and deposition during the March 1998 episodic events in southern Lake Michigan.  

SciTech Connect

A two-dimensional sediment transport model capable of simulating sediment resuspension of mixed (cohesive plus noncohesive) sediment is developed and applied to quantitatively simulate the March 1998 resuspension events in southern Lake Michigan. Some characteristics of the model are the capability to incorporate several floc size classes, a physically based settling velocity formula, bed armoring, and sediment availability limitation. Important resuspension parameters were estimated from field and laboratory measurement data. The model reproduced the resuspension plume (observed by the SeaWIFS satellite and field instruments) and recently measured sedimentation rate distribution (using radiotracer techniques) fairly well. Model results were verified with field measurements of suspended sediment concentration and settling flux (by ADCPs and sediment traps). Both wave conditions and sediment bed properties (critical shear stress, fine sediment fraction, and limited sediment availability or source) are the critical factors that determine the concentration distribution and width of the resuspension plume. The modeled sedimentation pattern shows preferential accumulation of sediment on the eastern side of the lake, which agrees with the observed sedimentation pattern despite a predominance of particle sources from the western shoreline. The main physical mechanisms determining the sedimentation pattern are (1) the two counter-rotating circulation gyres producing offshore mass transport along the southeastern coast during northerly wind and (2) the settling velocity of sediment flocs which controls the deposition location.

Lee, C.; Schwab, D. J.; Beletsky, D.; Stroud, J.; Lesht, B.; PNNL; NOAA; Univ. of Michigan; Univ. of Pennsylvania

2007-02-17T23:59:59.000Z

393

Grand challenge problems in environmental modeling and remediation: Groundwater contaminant transport. Final project report 1998  

SciTech Connect

The over-reaching goal of the Groundwater Grand Challenge component of the Partnership in Computational Science (PICS) was to develop and establish the massively parallel approach for the description of groundwater flow and transport and to address the problem of uncertainties in the data and its interpretation. This necessitated the development of innovative algorithms and the implementation of massively parallel computational tools to provide a suite of simulators for groundwater flow and transport in heterogeneous media. This report summarizes the activities and deliverables of the Groundwater Grand Challenge project funded through the High Performance Computing grand challenge program of the Department of Energy from 1995 through 1997.

NONE

1998-04-01T23:59:59.000Z

394

An Integrated Experimental and Numerical Study: Developing a Reaction  

Open Energy Info (EERE)

Integrated Experimental and Numerical Study: Developing a Reaction Integrated Experimental and Numerical Study: Developing a Reaction Transport Model that Couples Chemical Reactions of Mineral Dissolution/Precipitation with Spatial and Temporal Flow Variations in CO2/Brine/Rock Systems Geothermal Project Jump to: navigation, search Last modified on July 22, 2011. Project Title An Integrated Experimental and Numerical Study: Developing a Reaction Transport Model that Couples Chemical Reactions of Mineral Dissolution/Precipitation with Spatial and Temporal Flow Variations in CO2/Brine/Rock Systems Project Type / Topic 1 Recovery Act: Enhanced Geothermal Systems Component Research and Development/Analysis Project Type / Topic 2 Supercritical Carbon Dioxide / Reservoir Rock Chemical Interactions Project Description This project will result in a numerical simulator (modified version of TOUGH2) that can adjust porosity and permeability fields according to experimentally observed chemical fluid-rock interactions (mineral dissolution/precipitation) under realistic conditions likely found when supercritical CO2 is injected into geothermal reservoirs for heat energy extraction. The simulator can thus help determine if CO2 injection into EGS brines will cause clogging of pore spaces or dissolution of host rocks with potentially detrimental consequences to heat extraction. As a result, this simulator will play a critical role when assessing long-term sustainability of geothermal energy utilization in enhanced and natural geothermal systems. The simulator can also be used to evaluate long-term CO2 sequestration potentials.

395

Validation, Proof-of-Concept, and Postaudit of the Groundwater Flow and Transport Model of the Project Shoal Area  

SciTech Connect

The groundwater flow and radionuclide transport model characterizing the Shoal underground nuclear test has been accepted by the State of Nevada Division of Environmental Protection. According to the Federal Facility Agreement and Consent Order (FFACO) between DOE and the State of Nevada, the next steps in the closure process for the site are then model validation (or postaudit), the proof-of-concept, and the long-term monitoring stage. This report addresses the development of the validation strategy for the Shoal model, needed for preparing the subsurface Corrective Action Decision Document-Corrective Action Plan and the development of the proof-of-concept tools needed during the five-year monitoring/validation period. The approach builds on a previous model, but is adapted and modified to the site-specific conditions and challenges of the Shoal site.

Ahmed Hassan

2004-09-01T23:59:59.000Z

396

Modeling most likely pathways for smuggling radioactive and special nuclear materials on a worldwide multi-modal transportation network  

SciTech Connect

Nuclear weapons proliferation is an existing and growing worldwide problem. To help with devising strategies and supporting decisions to interdict the transport of nuclear material, we developed the Pathway Analysis, Threat Response and Interdiction Options Tool (PATRIOT) that provides an analytical approach for evaluating the probability that an adversary smuggling radioactive or special nuclear material will be detected during transit. We incorporate a global, multi-modal transportation network, explicit representation of designed and serendipitous detection opportunities, and multiple threat devices, material types, and shielding levels. This paper presents the general structure of PATRIOT, all focuses on the theoretical framework used to model the reliabilities of all network components that are used to predict the most likely pathways to the target.

Saeger, Kevin J [Los Alamos National Laboratory; Cuellar, Leticia [Los Alamos National Laboratory

2010-10-28T23:59:59.000Z

397

Modeling most likely pathways for smuggling radioactive and special nuclear materials on a worldwide multimodal transportation network  

SciTech Connect

Nuclear weapons proliferation is an existing and growing worldwide problem. To help with devising strategies and supporting decisions to interdict the transport of nuclear material, we developed the Pathway Analysis, Threat Response and Interdiction Options Tool (PATRIOT) that provides an analytical approach for evaluating the probability that an adversary smuggling radioactive or special nuclear material will be detected during transit. We incorporate a global, multi-modal transportation network, explicit representation of designed and serendipitous detection opportunities, and multiple threat devices, material types, and shielding levels. This paper presents the general structure of PATRIOT, and focuses on the theoretical framework used to model the reliabilities of all network components that are used to predict the most likely pathways to the target.

Saeger, Kevin J [Los Alamos National Laboratory; Cuellar, Leticia [Los Alamos National Laboratory

2010-01-01T23:59:59.000Z

398

Where do fossil fuel carbon dioxide emissions from California go? An analysis based on radiocarbon observations and an atmospheric transport model  

E-Print Network (OSTI)

ET AL. : FOSSIL FUEL CO 2 TRANSPORT IN CALIFORNIA health,fossil fuel combustion, with consequent impacts to human health [health. [ 45 ] Model predictions indicated that some areas within California had higher near-surface fossil fuel

2008-01-01T23:59:59.000Z

399

Advanced Monte Carlo modeling of prompt fission neutrons for thermal and fast neutron-induced fission reactions on Pu239  

Science Journals Connector (OSTI)

Prompt fission neutrons following the thermal and 0.5 MeV neutron-induced fission reaction of Pu239 are calculated using a Monte Carlo approach to the evaporation of the excited fission fragments. Exclusive data such as the multiplicity distribution P(?), the average multiplicity as a function of fragment mass ??(A), and many others are inferred in addition to the most used average prompt fission neutron spectrum ?(Ein,Eout), as well as average neutron multiplicity ??. Experimental information on these more exclusive data help constrain the Monte Carlo model parameters. The calculated average total neutron multiplicity is ??c=2.871 in very close agreement with the evaluated value ??e=2.8725 present in the ENDF/B-VII.0 library. The neutron multiplicity distribution P(?) is in very good agreement with the evaluation by Holden and Zucker. The calculated average spectrum differs in shape from the ENDF/B-VII.0 spectrum, evaluated with the Madland-Nix model. In particular, we predict more neutrons in the low-energy tail of the spectrum (below about 300 keV) than the Madland-Nix calculations, casting some doubts on how much scission neutrons contribute to the shape of the low-energy tail of the spectrum. The spectrum high-energy tail is very sensitive to the total kinetic energy distribution of the fragments as well as to the total excitation energy sharing at scission. Present experimental uncertainties on measured spectra above 6 MeV are too large to distinguish between various theoretical hypotheses. Finally, comparisons of the Monte Carlo results with experimental data on ??(A) indicate that more neutrons are emitted from the light fragments than the heavy ones, in agreement with previous works.

P. Talou; B. Becker; T. Kawano; M. B. Chadwick; Y. Danon

2011-06-23T23:59:59.000Z

400

Naturally fractured reservoirs: Optimized E and P strategies using a reaction-transport-mechanical simulator in an integrated approach. Annual report, 1996--1997  

SciTech Connect

The methodology and results of this project are being tested using the Andector-Goldsmith Field in the Permian Basin, West Texas. The study area includes the Central Basin Platform and the Midland Basin. The Andector-Goldsmith Field lies at the juncture of these two zones in the greater West Texas Permian Basin. Although the modeling is being conducted in this area, the results have widespread applicability to other fractured carbonate and other reservoirs throughout the world.

Hoak, T.; Jenkins, R. [Science Applications International Corp., McLean, VA (United States); Ortoleva, P.; Ozkan, G.; Shebl, M.; Sibo, W.; Tuncay, K. [Laboratory for Computational Geodynamics (United States); Sundberg, K. [Phillips Petroleum Company (United States)

1998-07-01T23:59:59.000Z

Note: This page contains sample records for the topic "reaction transport model" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Mathematical modelling of drug transport in tumour multicell spheroids and monolayer cultures  

E-Print Network (OSTI)

an enhanced survival rate in multicell spheroids compared to monolayer cultures, consistent with experimental observations, and indicate that the key factor determining this is drug penetration. An analysis of the large penetration of effective quantities of drugs deep into the tumour, due to drug transport being mainly

402

Modeling Coupled Hydrologic and Chemical Processes: Long-Term Uranium Transport following Phosphorus Fertilization  

Science Journals Connector (OSTI)

...mainly 226Ra and 210Pb) and rare earth elements originating...Phosphoric acid and the byproduct phosphogypsum are produced using H2SO4...the following reaction: Phosphogypsum (a calcium sulfate dihydrate...2006. The application of phosphogypsum in agriculture and the radiological...

D. Jacques; J. im?nek; D. Mallants; M.Th. van Genuchten

403

Dynamic Monte-Carlo modeling of hydrogen isotope reactivediffusive transport in porous graphite  

E-Print Network (OSTI)

by voids which are typically a fraction of a microm- eter. The granules consist of graphitic micro-crystal- lites of size 10­100 nm separated by micro-voids which are typically 1 nm (Fig. 1) [1­4]. These sub chemical reactions to form hydrocarbons or recombine to form hydro- gen molecules which can then diffuse

Nordlund, Kai

404

Modeling the Hydrogeochemical Transport of Radionuclides through Engineered Barriers System in the Proposed LLW Disposal Site of Taiwan - 12082  

SciTech Connect

A proposed site for final disposal of low-level radioactive waste located in Daren Township of Taitung County along the southeastern coast has been on the selected list in Taiwan. The geology of the Daren site consists of argillite and meta-sedimentary rocks. A mined cavern design with a tunnel system of 500 m below the surface is proposed. Concrete is used as the main confinement material for the engineered barrier. To investigate the hydrogeochemical transport of radionuclides through engineered barriers system, HYDROGEOCHEM5.0 model was applied to simulate the complex chemical interactions among radionuclides, the cement minerals of the concrete, groundwater flow, and transport in the proposed site. The simulation results showed that the engineered barriers system with the side ditch efficiently drained the ground water and lowered the concentration of the concrete degradation induced species (e.g., hydrogen ion, sulfate, and chloride). The velocity of groundwater observed at side ditch gradually decreased with time due to the fouling of pore space by the mineral formation of ettringite and thaumasite. The short half-life of Co-60, Sr-90 and Cs-137 significantly reduced the concentrations, whereas the long half-life of I-129(1.57x10{sup 7} years) and Am-241(432 years) remain stable concentrations at the interface of waste canister and concrete barrier after 300 years. The mineral saturation index (SI) was much less than zero due to the low aqueous concentration of radionuclide, so that the precipitation formation of Co-60, Sr-90, I-129, Cs-137 and Am-241 related minerals were not found. The effect of adsorption/desorption (i.e., surface complexation model) could be a crucial geochemical mechanism for the modeling of liquid-solid phase behavior of radionuclide in geochemically dynamic environments. Moreover, the development of advanced numerical models that are coupled with hydrogeochemical transport and dose assessment of radionuclide is required in the future. (authors)

Lin, Wen-Sheng [Hydrotech Research Institute, National Taiwan University, Taipei, Taiwan (China); Liu, Chen-Wuing; Tsao, Jui-Hsuan [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei, Taiwan (China); Li, Ming-Hsu [Institute of Hydrological and Oceanic Sciences, National Central University, Jhongli, Taiwan (China)

2012-07-01T23:59:59.000Z

405

Modeling Groundwater Flow and Transport of Radionuclides at Amchitka Island's Underground Nuclear Tests: Milrow, Long Shot, and Cannikin  

SciTech Connect

Since 1963, all United States nuclear tests have been conducted underground. A consequence of this testing has been the deposition of large amounts of radioactive material in the subsurface, sometimes in direct contact with groundwater. The majority of this testing occurred on the Nevada Test Site (NTS), but a limited number of experiments were conducted in other locations. One of these locations, Amchitka Island, Alaska is the subject of this report. Three underground nuclear tests were conducted on Amchitka Island. Long Shot was an 80-kiloton-yield test conducted at a depth of 700 meters (m) on October 29, 1965 (DOE, 2000). Milrow had an announced yield of about 1,000 kilotons, and was detonated at a depth of 1,220 m on October 2, 1969. Cannikin had an announced yield less than 5,000 kilotons, and was conducted at a depth of 1,790 m on November 6, 1971. The purpose of this work is to provide a portion of the information needed to conduct a human-health risk assessment of the potential hazard posed by the three underground nuclear tests on Amchitka Island. Specifically, the focus of this work is the subsurface transport portion, including the release of radionuclides from the underground cavities and their movement through the groundwater system to the point where they seep out of the ocean floor and into the marine environment. This requires a conceptual model of groundwater flow on the island using geologic, hydrologic, and chemical information, a numerical model for groundwater flow, a conceptual model of contaminant release and transport properties from the nuclear test cavities, and a numerical model for contaminant transport. Needed for the risk assessment are estimates of the quantity of radionuclides (in terms of mass flux) from the underground tests on Amchitka that could discharge to the ocean, the time of possible discharge, and the location in terms of distance from shoreline. The radionuclide data presented here are all reported in terms of normalized masses to avoid presenting classified information. As only linear processes are modeled, the results can be readily scaled by the true classified masses for use in the risk assessment. The modeling timeframe for the risk assessment was set at 1,000 years, though some calculations are extended to 2,000 years. This first section of the report endeavors to orient the reader with the environment of Amchitka and the specifics of the underground nuclear tests. Of prime importance are the geologic and hydrologic conditions of the subsurface. A conceptual model for groundwater flow beneath the island is then developed and paired with an appropriate numerical modeling approach in section 2. The parameters needed for the model, supporting data for them, and data uncertainties are discussed at length. The calibration of the three flow models (one for each test) is then presented. At this point the conceptual radionuclide transport model is introduced and its numerical approach described in section 3. Again, the transport parameters and their supporting data and uncertainties are the focus. With all of the processes and parameters in place, the first major modeling phase can be discussed in section 4. In this phase, a parametric uncertainty analysis is performed to determine the sensitivity of the transport modeling results to the uncertainties present in the parameters. This analysis is motivated by the recognition of substantial uncertainty in the subsurface conditions on the island and the need to incorporate that uncertainty into the modeling. The conclusion of the first phase determines the parameters to hold as uncertain through the main flow and transport modeling. This second, main phase of modeling is presented in section 5, with the contaminant breakthrough behavior of each test site addressed. This is followed by a sensitivity analysis in section 6, regarding the importance of additional processes that could not be supported in the main modeling effort due to lack of data. Finally, the results for the individual sites are compared, the sensitivities discussed,

Ahmed Hassan; Karl Pohlmann; Jenny Chapman

2002-11-19T23:59:59.000Z

406

Use of a comprehensive calibration ``gauntlet`` approach for improved contaminants transport modeling at the F and H Area Seepage Basins  

SciTech Connect

Many types of facility and monitoring data have been collected to support operation, closure and envirorunental restoration of the F and H-Area Seepage Basins at the Savannah River Site. Based on the various types of data, we developed contaminant transpose models to allow projection of contaminant releases and comparison of restoration alternatives. The modeling was performed in the following three stages: postulation of a conceptual model of the flow and transport system; development of a simplified analytical model based on a transfer function; development of a numerical model. A key feature of the work was use of both traditional data sources and calibration targets such as heads, geological data and pump test results, and non-traditional data sources and calibration targets, such as plume arrival times and shapes, contaminant release rates, and surface water concentrations. Throughout the process, the intermediate and final results were compared to all of the various data types and the earlier modeling stages. The result was a calibration ``gauntlet`` with explicit criteria for refinement and acceptance of the final model. Failure to match at any step within the gauntlet necessitated appropriate reformulation or modification of the model and rechecking for acceptable matches.

Looney, B.B.; Haselow, J.S.; Pidcoe, W.W.; Lewis, C.M. [Westinghouse Savannah River Co., Aiken, SC (United States); Andersen, P.F.; Spalding, C.P. [GeoTrans, Inc., Sterling, VA (United States)

1993-12-01T23:59:59.000Z

407

Influence of Transport Variables on Isospin Transport Ratios  

E-Print Network (OSTI)

The symmetry energy in the nuclear equation of state affects many aspects of nuclear astrophysics, nuclear structure, and nuclear reactions. Recent constraints from heavy ion collisions, including isospin diffusion observables, have started to put constraints on the symmetry energy below nuclear saturation density, but these constraints depend on the employed transport model and input physics other than the symmetry energy. To understand these dependencies, we study the influence of the symmetry energy, isoscaler mean field compressibility and momentum dependence, in-medium nucleon-nucleon cross sections, and light cluster production on isospin diffusion within the pBUU transport code. In addition to the symmetry energy, several uncertain issues strongly affect isospin diffusion, most notably the cross sections and cluster production. In addition, there is a difference in the calculated isospin transport ratios, depending upon whether they are computed using the isospin asymmetry of either the residue or of all forward moving fragments. Measurements that compare the isospin transport ratios of these two quantities would help place constraints on the input physics, such as the density dependence of the symmetry energy.

D. D. S. Coupland; W. G. Lynch; M. B. Tsang; P. Danielewicz; Yingxun Zhang

2011-07-19T23:59:59.000Z

408

Efficiency and Evolution of Water Transport Systems in Higher Plants: A Modelling Approach. I. The Earliest Land Plants  

Science Journals Connector (OSTI)

...1994 research-article Efficiency and Evolution of Water Transport Systems in Higher...transport vascular taxa water water pressure GeoRef, Copyright...1098/rstb.1994.0093 Efficiency and evolution of water transport systems in higher...

1994-01-01T23:59:59.000Z

409

Modeling heat and mass transport phenomena at higher temperatures in solar distillation systems - The Chilton-Colburn analogy  

SciTech Connect

In the present investigation efforts have been devoted towards developing an analysis suitable for heat and mass transfer processes modeling in solar distillation systems, when they are operating at higher temperatures. For this purpose the use of Lewis relation is not new although its validity is based on the assumptions of identical boundary layer concentration and temperature distributions, as well as low mass flux conditions, which are not usually met in solar distillation systems operating at higher temperatures associated with considerable mass transfer rates. The present analysis, taking into consideration these conditions and the temperature dependence of all pertinent thermophysical properties of the saturated binary mixture of water vapor and dry air, leads to the development of an improved predictive accuracy model. This model, having undergone successful first order validation against earlier reported measurements from the literature, appears to offer more accurate predictions of the transport processes and mass flow rate yield of solar stills when operated at elevated temperatures. (author)

Tsilingiris, P.T. [Department of Energy Engineering, Heat Transfer Laboratory, Technological Education Institution of Athens, A. Spyridonos Street, GR 122 10 Egaleo, Athens (Greece)

2010-02-15T23:59:59.000Z

410

A model to assess the relative impact of policy in transportation energy expenditures  

SciTech Connect

The research reported in this paper uses the 1977 and 1983 Nationwide Personal Transportation Study surveys (NPTS's) to estimate the cross-section and time responses of minority and majority households in terms of variations in vehicles held by the household, VMT per household vehicle, 1983 dollar income of the household, education and age of the household head, transit availability to the household, workers and nonworkers per household, and urban vs rural location.

Santini, D.J.; Vyas, A.D.

1987-01-01T23:59:59.000Z

411

Mathematical modeling of liquid/liquid hollow fiber membrane contactor accounting for interfacial transport phenomena: Extraction of lanthanides as a surrogate for actinides  

SciTech Connect

This report is divided into two parts. The second part is divided into the following sections: experimental protocol; modeling the hollow fiber extractor using film theory; Graetz model of the hollow fiber membrane process; fundamental diffusive-kinetic model; and diffusive liquid membrane device-a rigorous model. The first part is divided into: membrane and membrane process-a concept; metal extraction; kinetics of metal extraction; modeling the membrane contactor; and interfacial phenomenon-boundary conditions-applied to membrane transport.

Rogers, J.D.

1994-08-04T23:59:59.000Z

412

Use of superposition and the extended pulse model to evaluate the contaminant transport parameters of variably source-loaded plumes  

E-Print Network (OSTI)

. Source Dimension Y 4. 5. 2. Dispersivities 4. 5. 3. Velocity 4. 5. 4. Discussion of the Match between Simulated and Observed Concentrations 4. 5. 5. Perched Effluent 4. 5. 6. Future Migration of the Tritium Plume 62 62 65 67 77 79 79 80 87.../v) / ] ) (7) erfc( [x-vt(1 t 4%ax/v) 1/2]/2 (axvt) / } (erf [ (y+Y/2)/2 (ayx) /2]-erf [ (y-Y/2)/2 (ayx) / ] ) (erf [ (z+Z/2)/2 (azx) / ]-erf [(z-Z/2)/2 (azx) / ] ) . This model can simulate one-, two-, or three-dimensional transport and dispersion of a...

Hankins, Donald Wayne

2012-06-07T23:59:59.000Z

413

Dynamic Incompressible Navier-Stokes Model of Catalytic Converter in 1-D Including Fundamental Oxidation Reaction Rate Expressions  

E-Print Network (OSTI)

, this work includes the history of the fundamental reactions of automotive catalysts including carbon monoxide (CO), hydrogen (H2) and nitric oxide (NO) oxidation on a widely used material formulation (platinum catalyst on alumina washcoat). A detailed report...

Loya, Sudarshan Kedarnath

2011-12-31T23:59:59.000Z

414

A Model of Two Reactions as Dose-Stochastic Radiological Effect Relationship and Estimation of Radiation Risks  

Science Journals Connector (OSTI)

A defense system consists of two forms of organism reaction, which determine innate n and adaptive a radiosensitivities. The significance of n is determined by host (inner) factors, and the significance of a....

M. M. Komochkov

1999-01-01T23:59:59.000Z

415

An efficient parallel-computing method for modeling nonisothermal multiphase flow and multicomponent transport in porous  

E-Print Network (OSTI)

numerical model simulating flow of moisture in the unsaturated zone of Yucca Mountain, Nevada; the second

Elmroth, Erik

416

MODELING THE FATE AND TRANSPORT OF ATRAZINE IN THE UPPER CHESAPEAKE BAY  

E-Print Network (OSTI)

for agrochemicals in the Upper Chesapeake Bay. Keywords: Chesapeake Bay, hydrodynamic model, atrazine, photolysis

Frei, Allan

417

Two-Dimensional Hydrodynamic Core-Collapse Supernova Simulations with Spectral Neutrino Transport II. Models for Different Progenitor Stars  

E-Print Network (OSTI)

1D and 2D supernova simulations for stars between 11 and 25 solar masses are presented, making use of the Prometheus/Vertex neutrino-hydrodynamics code, which employs a full spectral treatment of the neutrino transport. Multi-dimensional transport aspects are treated by the ``ray-by-ray plus'' approximation described in Paper I. Our set of models includes a 2D calculation for a 15 solar mass star whose iron core is assumed to rotate rigidly with an angular frequency of 0.5 rad/s before collapse. No important differences were found depending on whether random seed perturbations for triggering convection are included already during core collapse, or whether they are imposed on a 1D collapse model shortly after bounce. Convection below the neutrinosphere sets in about 40 ms p.b. at a density above 10**12 g/cm^3 in all 2D models, and encompasses a layer of growing mass as time goes on. It leads to a more extended proto-neutron star structure with accelerated lepton number and energy loss and significantly higher muon and tau neutrino luminosities, but reduced mean energies of the radiated neutrinos, at times later than ~100 ms p.b. In case of an 11.2 solar mass star we find that low (l = 1,2) convective modes cause a probably rather weak explosion by the convectively supported neutrino-heating mechanism after ~150 ms p.b. when the 2D simulation is performed with a full 180 degree grid, whereas the same simulation with 90 degree wedge fails to explode like all other models. This sensitivity demonstrates the proximity of our 2D models to the borderline between success and failure, and stresses the need of simulations in 3D, ultimately without the axis singularity of a polar grid. (abridged)

R. Buras; H. -Th. Janka; M. Rampp; K. Kifonidis

2005-12-07T23:59:59.000Z

418

Fast-ignition transport studies: Realistic electron source, integrated particle-in-cell and hydrodynamic modeling, imposed magnetic fields  

SciTech Connect

Transport modeling of idealized, cone-guided fast ignition targets indicates the severe challenge posed by fast-electron source divergence. The hybrid particle-in-cell (PIC) code Zuma is run in tandem with the radiation-hydrodynamics code Hydra to model fast-electron propagation, fuel heating, and thermonuclear burn. The fast electron source is based on a 3D explicit-PIC laser-plasma simulation with the PSC code. This shows a quasi two-temperature energy spectrum and a divergent angle spectrum (average velocity-space polar angle of 52 Degree-Sign ). Transport simulations with the PIC-based divergence do not ignite for >1 MJ of fast-electron energy, for a modest (70 {mu}m) standoff distance from fast-electron injection to the dense fuel. However, artificially collimating the source gives an ignition energy of 132 kJ. To mitigate the divergence, we consider imposed axial magnetic fields. Uniform fields {approx}50 MG are sufficient to recover the artificially collimated ignition energy. Experiments at the Omega laser facility have generated fields of this magnitude by imploding a capsule in seed fields of 50-100 kG. Such imploded fields will likely be more compressed in the transport region than in the laser absorption region. When fast electrons encounter increasing field strength, magnetic mirroring can reflect a substantial fraction of them and reduce coupling to the fuel. A hollow magnetic pipe, which peaks at a finite radius, is presented as one field configuration which circumvents mirroring.

Strozzi, D. J.; Tabak, M.; Larson, D. J.; Divol, L.; Kemp, A. J.; Bellei, C.; Marinak, M. M.; Key, M. H. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States)

2012-07-15T23:59:59.000Z

419

A groundwater flow and transport model of long-term radionuclide migration in central Frenchman flat, Nevada test site  

SciTech Connect

A set of groundwater flow and transport models were created for the Central Testing Area of Frenchman Flat at the former Nevada Test Site to investigate the long-term consequences of a radionuclide migration experiment that was done between 1975 and 1990. In this experiment, radionuclide migration was induced from a small nuclear test conducted below the water table by pumping a well 91 m away. After radionuclides arrived at the pumping well, the contaminated effluent was discharged to an unlined ditch leading to a playa where it was expected to evaporate. However, recent data from a well near the ditch and results from detailed models of the experiment by LLNL personnel have convincingly demonstrated that radionuclides from the ditch eventually reached the water table some 220 m below land surface. The models presented in this paper combine aspects of these detailed models with concepts of basin-scale flow to estimate the likely extent of contamination resulting from this experiment over the next 1,000 years. The models demonstrate that because regulatory limits for radionuclide concentrations are exceeded only by tritium and the half-life of tritium is relatively short (12.3 years), the maximum extent of contaminated groundwater has or will soon be reached, after which time the contaminated plume will begin to shrink because of radioactive decay. The models also show that past and future groundwater pumping from water supply wells within Frenchman Flat basin will have negligible effects on the extent of the plume.

Kwicklis, Edward Michael [Los Alamos National Laboratory; Becker, Naomi M [Los Alamos National Laboratory; Ruskauff, Gregory [NAVARRO-INTERA, LLC.; De Novio, Nicole [GOLDER AND ASSOC.; Wilborn, Bill [US DOE NNSA NSO

2010-11-10T23:59:59.000Z

420

Continuous-time random-walk model of transport in variably saturated heterogeneous porous media  

Science Journals Connector (OSTI)

We propose a unified physical framework for transport in variably saturated porous media. This approach allows fluid flow and solute migration to be treated as ensemble averages of fluid and solute particles, respectively. We consider the cases of homogeneous and heterogeneous porous materials. Within a fractal mobile-immobile continuous time random-walk framework, the heterogeneity will be characterized by algebraically decaying particle retention times. We derive the corresponding (nonlinear) continuum-limit partial differential equations and we compare their solutions to Monte Carlo simulation results. The proposed methodology is fairly general and can be used to track fluid and solutes particles trajectories for a variety of initial and boundary conditions.

Andrea Zoia; Marie-Christine Nel; Andrea Cortis

2010-03-04T23:59:59.000Z

Note: This page contains sample records for the topic "reaction transport model" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

A Conceptual Nitrate Transport Model and Its Application at Different Scales  

Science Journals Connector (OSTI)

Liu et al. [12...] reported the calibration of a diffuse nitrate model (the DNMT model) at White Cart Water Catchment against the observed water quality...K 0 (the hydraulic conductivity at grou...

Shuming Liu; Peter Tucker; Martin Mansell

2010-08-01T23:59:59.000Z

422

Modeling Unsaturated Flow and Transport Processes in Fractured Tuffs of Yucca Mountain  

E-Print Network (OSTI)

zone site-scale model, Yucca Mountain Site Characterizationsite-scale model, Yucca Mountain Project Milestone 3GLM105M,unsaturated zone, Yucca Mountain, Nevada. Water-Resources

Wu, Yu-Shu; Lu, Guoping; Zhang, Keni; Bodvarsson, G.S.

2003-01-01T23:59:59.000Z

423

EMEP Intercomparison Study of Numerical Models for Long-Range Atmospheric Transport of Mercury  

E-Print Network (OSTI)

............................... Denmark...NERI G. Petersen, R. Ebinghaus .................. Germany...GKSS J. Pacyna and Oxidants Model, GKSS Research Center, GermanyADOM MSC-E heavy metal regional model, EMEP MSC

424

Modeling Tidal Stream Energy Extraction and its Effects on Transport Processes in a Tidal Channel and Bay System Using a Three-dimensional Coastal Ocean Model  

SciTech Connect

This paper presents a numerical modeling study for simulating in-stream tidal energy extraction and assessing its effects on the hydrodynamics and transport processes in a tidal channel and bay system connecting to coastal ocean. A marine and hydrokinetic (MHK) module was implemented in a three-dimensional (3-D) coastal ocean model using the momentum sink approach. The MHK model was validated with the analytical solutions for tidal channels under one-dimensional (1-D) conditions. Model simulations were further carried out to compare the momentum sink approach with the quadratic bottom friction approach. The effects of 3-D simulations on the vertical velocity profile, maximum extractable energy, and volume flux reduction across the channel were investigated through a series of numerical experiments. 3-D model results indicate that the volume flux reduction at the maximum extractable power predicted by the 1-D analytical model or two-dimensional (2-D) depth-averaged numerical model may be overestimated. Maximum extractable energy strongly depends on the turbine hub height in the water column, and which reaches a maximum when turbine hub height is located at mid-water depth. Far-field effects of tidal turbines on the flushing time of the tidal bay were also investigated. Model results demonstrate that tidal energy extraction has a greater effect on the flushing time than volume flux reduction, which could negatively affect the biogeochemical processes in estuarine and coastal waters that support primary productivity and higher forms of marine life.

Yang, Zhaoqing; Wang, Taiping; Copping, Andrea E.

2013-02-28T23:59:59.000Z

425

Nuclear reactions  

Science Journals Connector (OSTI)

Much reference has been made in the last chapter to nuclear energy levels and their various properties (e.g ... ways of doing this the use of nuclear reactions, and studies of how excited nuclei...

R. J. Blin-Stoyle FRS

1991-01-01T23:59:59.000Z

426

Toward Novel Hybrid Biomass, Coal, and Natural Gas Processes for Satisfying Current Transportation Fuel Demands, 1: Process Alternatives, Gasification Modeling, Process Simulation, and Economic Analysis  

Science Journals Connector (OSTI)

Toward Novel Hybrid Biomass, Coal, and Natural Gas Processes for Satisfying Current Transportation Fuel Demands, 1: Process Alternatives, Gasification Modeling, Process Simulation, and Economic Analysis ... This paper, which is the first part of a series of papers, introduces a hybrid coal, biomass, and natural gas to liquids (CBGTL) process that can produce transportation fuels in ratios consistent with current U.S. transportation fuel demands. ... Steady-state process simulation results based on Aspen Plus are presented for the seven process alternatives with a detailed economic analysis performed using the Aspen Process Economic Analyzer and unit cost functions obtained from literature. ...

Richard C. Baliban; Josephine A. Elia; Christodoulos A. Floudas

2010-07-19T23:59:59.000Z

427

Lattice Boltzmann simulation of solute transport in heterogeneous porous media with conduits to estimate macroscopic continuous time random walk model parameters  

SciTech Connect

Lattice Boltzmann models simulate solute transport in porous media traversed by conduits. Resulting solute breakthrough curves are fitted with Continuous Time Random Walk models. Porous media are simulated by damping flow inertia and, when the damping is large enough, a Darcy's Law solution instead of the Navier-Stokes solution normally provided by the lattice Boltzmann model is obtained. Anisotropic dispersion is incorporated using a direction-dependent relaxation time. Our particular interest is to simulate transport processes outside the applicability of the standard Advection-Dispersion Equation (ADE) including eddy mixing in conduits. The ADE fails to adequately fit any of these breakthrough curves.

Anwar, S.; Cortis, A.; Sukop, M.

2008-10-20T23:59:59.000Z

428

Recent Approaches to Modeling Transport of Mercury in Surface Water and Groundwater - Case Study in Upper East Fork Poplar Creek, Oak Ridge, TN - 13349  

SciTech Connect

In this case study, groundwater/surface water modeling was used to determine efficacy of stabilization in place with hydrologic isolation for remediation of mercury contaminated areas in the Upper East Fork Poplar Creek (UEFPC) Watershed in Oak Ridge, TN. The modeling simulates the potential for mercury in soil to contaminate groundwater above industrial use risk standards and to contribute to surface water contamination. The modeling approach is unique in that it couples watershed hydrology with the total mercury transport and provides a tool for analysis of changes in mercury load related to daily precipitation, evaporation, and runoff from storms. The model also allows for simulation of colloidal transport of total mercury in surface water. Previous models for the watershed only simulated average yearly conditions and dissolved concentrations that are not sufficient for predicting mercury flux under variable flow conditions that control colloidal transport of mercury in the watershed. The transport of mercury from groundwater to surface water from mercury sources identified from information in the Oak Ridge Environmental Information System was simulated using a watershed scale model calibrated to match observed daily creek flow, total suspended solids and mercury fluxes. Mercury sources at the former Building 81-10 area, where mercury was previously retorted, were modeled using a telescopic refined mesh with boundary conditions extracted from the watershed model. Modeling on a watershed scale indicated that only source excavation for soils/sediment in the vicinity of UEFPC had any effect on mercury flux in surface water. The simulations showed that colloidal transport contributed 85 percent of the total mercury flux leaving the UEFPC watershed under high flow conditions. Simulation of dissolved mercury transport from liquid elemental mercury and adsorbed sources in soil at former Building 81-10 indicated that dissolved concentrations are orders of magnitude below a target industrial groundwater concentration beneath the source and would not influence concentrations in surface water at Station 17. This analysis addressed only shallow concentrations in soil and the shallow groundwater flow path in soil and unconsolidated sediments to UEFPC. Other mercury sources may occur in bedrock and transport though bedrock to UEFPC may contribute to the mercury flux at Station 17. Generally mercury in the source areas adjacent to the stream and in sediment that is eroding can contribute to the flux of mercury in surface water. Because colloidally adsorbed mercury can be transported in surface water, actions that trap colloids and or hydrologically isolate surface water runoff from source areas would reduce the flux of mercury in surface water. Mercury in soil is highly adsorbed and transport in the groundwater system is very limited under porous media conditions. (authors)

Bostick, Kent; Daniel, Anamary [Professional Project Services, Inc., Bethel Valley Road, Oak Ridge, TN, 37922 (United States)] [Professional Project Services, Inc., Bethel Valley Road, Oak Ridge, TN, 37922 (United States); Tachiev, Georgio [Florida International University, Applied Research Center 10555 W. Flagler St., EC 2100 Miami Florida 33174 (United States)] [Florida International University, Applied Research Center 10555 W. Flagler St., EC 2100 Miami Florida 33174 (United States); Malek-Mohammadi, Siamak [Bradley University, 413A Jobst Hall, Preoria, IL 61625 (United States)] [Bradley University, 413A Jobst Hall, Preoria, IL 61625 (United States)

2013-07-01T23:59:59.000Z

429

A Model of Transient Thermal Transport Phenomena Applied to the Carbonation and Calcination of a Sorbent Particle for Calcium Oxide Looping CO2 Capture  

E-Print Network (OSTI)

looping is selected as the model cycle because of its suitability for solar-driven carbon dioxide captureA Model of Transient Thermal Transport Phenomena Applied to the Carbonation and Calcination of a Sorbent Particle for Calcium Oxide Looping CO2 Capture Lindsey Yue and Wojciech Lipi´nski, The Australian

430

Reaction-Driven Ion Transport Membrane  

NLE Websites -- All DOE Office Websites (Extended Search)

Jenny B. Tennant Jenny B. Tennant Gasification Technology Manager National Energy Technology Laboratory 3610 Collins Ferry Road P.O. Box 880 Morgantown, WV 26507-0880 304-285-4830 jenny.tennant@netl.doe.gov Susan Maley Project Manager National Energy Technology Laboratory 3610 Collins Ferry Road P.O. Box 880 Morgantown, WV 26507-0880 304-285-1321 susan.maley@netl.doe.gov David Studer Principal Investigator Air Products and Chemicals Inc.

431

Fluid Interface Reactions, Structures and Transport  

NLE Websites -- All DOE Office Websites (Extended Search)

CS Division CS Division PS Directorate ORNL Sub Header Title CSE Division Home Project Overview Project Management Advisory Board Research Team Research Highlights Publications Calendar Contact Us Research Areas Neutron Sciences Energy Advanced Materials Supercomputing Catalysis A. J. Drexel Nanotechnology Institute ornl logo Vanderbilt University logo Argonne National Laboratory logo Drexel University logo University of Virginia logo NorthWestern University logo Suffolk University logo Penn State University logo Georgia State University logo First Wiki First Wiki Site logo FIRST Center The overarching goal of the FIRST Energy Frontier Research Center (EFRCs) is to address the fundamental gaps in our current understanding of interfacial systems of high importance to future energy technologies,

432

Fluid Interface Reactions, Structures and Transport  

NLE Websites -- All DOE Office Websites (Extended Search)

thrusts, educational outreach, oversight, operational support, and integration with DOE's core science and technology programs. The Director (David J.Wesolowski) is responsible for...

433

Hydrogen transport membranes for dehydrogenation reactions  

DOE Patents (OSTI)

A method of converting C.sub.2 and/or higher alkanes to olefins by contacting a feedstock containing C.sub.2 and/or higher alkanes with a first surface of a metal composite membrane of a sintered homogenous mixture of an Al oxide or stabilized or partially stabilized Zr oxide ceramic powder and a metal powder of one or more of Pd, Nb, V, Zr, Ta and/or alloys or mixtures thereof. The alkanes dehydrogenate to olefins by contact with the first surface with substantially only atomic hydrogen from the dehydrogenation of the alkanes passing through the metal composite membrane. Apparatus for effecting the conversion and separation is also disclosed.

Balachandran; Uthamalingam (Hinsdale, IL)

2008-02-12T23:59:59.000Z

434

Fluid Interface Reactions, Structures and Transport  

NLE Websites -- All DOE Office Websites (Extended Search)

fluid by local bond relaxation, charge redistribution, dissolution, precipitation, sorption and porosity developmentdestruction. Heretofore, interfaces have been described...

435

Transportation Demand This  

U.S. Energy Information Administration (EIA) Indexed Site

Transportation Demand Transportation Demand This page inTenTionally lefT blank 75 U.S. Energy Information Administration | Assumptions to the Annual Energy Outlook 2013 Transportation Demand Module The NEMS Transportation Demand Module estimates transportation energy consumption across the nine Census Divisions (see Figure 5) and over ten fuel types. Each fuel type is modeled according to fuel-specific and associated technology attributes applicable by transportation mode. Total transportation energy consumption is the sum of energy use in eight transport modes: light-duty vehicles (cars and light trucks), commercial light trucks (8,501-10,000 lbs gross vehicle weight), freight trucks (>10,000 lbs gross vehicle weight), buses, freight and passenger aircraft, freight

436

Coupled Model for Heat and Water Transport in a High Level Waste...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

algorithm for mineral dehydration is also applied in the modeling. The Finite Element Heat and Mass transfer code (FEHM) is used to simulate coupled thermal, hydrological, and...

437

Model Development and Analysis of the Fate and Transport of Water...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

work on numerical modeling, simulations, and experimental results related to nuclear waste storage in a salt repository. The study reflects the project's preliminary effort at...

438

NA22 Model Cities Project - LL244T An Intelligent Transportation System-Based Radiation Alert and Detection System  

SciTech Connect

The purpose of this project was twofold: first, provide an understanding of the technical foundation and planning required for deployment of Intelligent Transportation System (ITS)-based system architectures for the protection of New York City from a terrorist attack using a vehicle-deployed nuclear device; second, work with stakeholders to develop mutual understanding of the technologies and tactics required for threat detection/identification and establish guidelines for designing operational systems and procedures. During the course of this project we interviewed and coordinated analysis with people from the New Jersey State Attorney General's office, the New Jersey State Police, the Port Authority of New York/New Jersey, the Counterterrorism Division of the New York City Police Department, the New Jersey Transit Authority, the State of New Jersey Department of Transportation, TRANSCOM and a number of contractors involved with state and federal intelligent transportation development and implementation. The basic system architecture is shown in the figure below. In an actual system deployment, radiation sensors would be co-located with existing ITS elements and the data will be sent to the Traffic Operations Center. A key element of successful system operation is the integration of vehicle data, such as license plate, EZ pass ID, vehicle type/color and radiation signature. A threat data base can also be implemented and utilized in cases where there is a suspect vehicle identified from other intelligence sources or a mobile detector system. Another key aspect of an operational architecture is the procedures used to verify the threat and plan interdiction. This was a major focus of our work and discussed later in detail. In support of the operational analysis, we developed a detailed traffic simulation model that is described extensively in the body of the report.

Peglow, S

2004-02-24T23:59:59.000Z

439

Optical-Model Parameters for the C-12(li-7,li-7)c-12 Reaction at 63 and 78.7 Mev  

E-Print Network (OSTI)

of energies via simple changes in the depths of the potentials, NUCLEAR REACTIONS ~2 C('Li, 'Li) and ~2 C{'Li,'Li') E('Li)=68 and 78.7 MeV; measured o-{&); deduced optical model parameters; deduced deformation lengths for YLi* and C*. Natural targets, DWBA... the most forward angle elastic scattering cross sections with several OM parameter sets; the 1980The American Physica1 Society OPTICAL MODEL PARAMETERS FOR THE ~2 C(7Li, 7Li). . . normalization factor was treated as a free para- meter. The magnitude...

Zeller, A. F.; Lui, YW; Tribble, Robert E.; Tanner, D. M.

1980-01-01T23:59:59.000Z

440

vol. 160, no. 3 the american naturalist september 2002 A Model for Optimal Reaction Norms: The Case  

E-Print Network (OSTI)

of the Pregnant Garter Snake and Her Temperature-Sensitive Embryos Stevan J. Arnold1,* and Charles R. Peterson2, 1 that traits that are subject to temperature effects during development will evolve a flat or U-shaped reaction by maintaining 67 female garter snakes (Thamnophis elegans) at eight different constant temperatures (21 ­33 C

Arnold, Stevan J.

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441

Combined Estimation of Hydrogeologic Conceptual Model, Parameter, and Scenario Uncertainty with Application to Uranium Transport at the Hanford Site 300 Area  

SciTech Connect

This report to the Nuclear Regulatory Commission (NRC) describes the development and application of a methodology to systematically and quantitatively assess predictive uncertainty in groundwater flow and transport modeling that considers the combined impact of hydrogeologic uncertainties associated with the conceptual-mathematical basis of a model, model parameters, and the scenario to which the model is applied. The methodology is based on a n extension of a Maximum Likelihood implementation of Bayesian Model Averaging. Model uncertainty is represented by postulating a discrete set of alternative conceptual models for a site with associated prior model probabilities that reflect a belief about the relative plausibility of each model based on its apparent consistency with available knowledge and data. Posterior model probabilities are computed and parameter uncertainty is estimated by calibrating each model to observed system behavior; prior parameter estimates are optionally included. Scenario uncertainty is represented as a discrete set of alternative future conditions affecting boundary conditions, source/sink terms, or other aspects of the models, with associ