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1

Modeling biogechemical reactive transport in a fracture zone  

SciTech Connect (OSTI)

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

2

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

3

Reactive Transport Modeling of Acid Gas Generation and Condensation  

SciTech Connect (OSTI)

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

4

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

5

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

6

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

SciTech Connect (OSTI)

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

7

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

SciTech Connect (OSTI)

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

8

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

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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

9

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

SciTech Connect (OSTI)

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

10

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

SciTech Connect (OSTI)

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

11

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

SciTech Connect (OSTI)

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

12

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

SciTech Connect (OSTI)

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

13

Review of existing reactive transport software  

SciTech Connect (OSTI)

Simulations of thermal and hydrological evolution following the potential emplacement of a subterranean nuclear waste repository at Yucca Mountain, NV provide data that suggest the inevitability of dependent, simultaneous chemical evolution in this system. These chemical changes will modify significantly both the magnitude and structure of local porosity and permeability; hence, they will have a dynamic feedback effect on the evolving thermal and hydrological regime. Yet, despite this intimate interdependence of transport and chemical processes, a rigorous quantitative analysis of the post- emplacement environment that incorporates this critical feedback mechanism has not been completed to date. As an initial step in this direction, the present document outlines the fundamental chemical and transport processes that must be accounted for in such an analysis, and reviews the inventory of existing software that encodes these processed in explicitly coupled form. A companion report describes the prioritization of specific capabilities that are needed for modeling post-emplacement reactive transport at Yucca Mountain.

Glassley, W., LLNL

1998-02-03T23:59:59.000Z

14

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

SciTech Connect (OSTI)

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

15

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

SciTech Connect (OSTI)

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

16

Groundwater Reactive Transport Models, 2012, 141-159 141 Fan Zhang, Gour-Tsyh (George) Yeh, Jack C. Parker and Xiaonan Shi (Eds)  

E-Print Network [OSTI]

performance computing, reactive transport, carbon sequestration, multiple realizations, multiphase flow transport at the Hanford 300 Area and CO2 sequestration in deep geologic formations. Keywords: High resources, such as CO2 sequestration in deep geologic formations, on the environment, and the efficacy

Mills, Richard

17

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

18

Using laboratory flow experiments and reactive chemical transport modeling for designing waterflooding of the Agua Fria Reservoir, Poza Rica-Altamira Field, Mexico  

SciTech Connect (OSTI)

Waterflooding for enhanced oil recovery requires that injected waters must be chemically compatible with connate reservoir waters, in order to avoid mineral dissolution-and-precipitation cycles that could seriously degrade formation permeability and injectivity. Formation plugging is a concern especially in reservoirs with a large content of carbonates, such as calcite and dolomite, as such minerals typically react rapidly with an aqueous phase, and have strongly temperature-dependent solubility. Clay swelling can also pose problems. During a preliminary waterflooding pilot project, the Poza Rica-Altamira oil field, bordering the Gulf coast in the eastern part of Mexico, experienced injectivity loss after five months of reinjection of formation waters into well AF-847 in 1999. Acidizing with HCl restored injectivity. We report on laboratory experiments and reactive chemistry modeling studies that were undertaken in preparation for long-term waterflooding at Agua Frma. Using analogous core plugs obtained from the same reservoir interval, laboratory coreflood experiments were conducted to examine sensitivity of mineral dissolution and precipitation effects to water composition. Native reservoir water, chemically altered waters, and distilled water were used, and temporal changes in core permeability, mineral abundances and aqueous concentrations of solutes were monitored. The experiments were simulated with the multi-phase, nonisothermal reactive transport code TOUGHREACT, and reasonable to good agreement was obtained for changes in solute concentrations. Clay swelling caused an additional impact on permeability behavior during coreflood experiments, whereas the modeled permeability depends exclusively on chemical processes. TOUGHREACT was then used for reservoir-scale simulation of injecting ambient-temperature water (30 C, 86 F) into a reservoir with initial temperature of 80 C (176 F). Untreated native reservoir water was found to cause serious porosity and permeability reduction due to calcite precipitation, which is promoted by the retrograde solubility of this mineral. Using treated water that performed well in the laboratory flow experiments was found to avoid excessive precipitation, and allowed injection to proceed.

Birkle, P.; Pruess, K.; Xu, T.; Figueroa, R.A. Hernandez; Lopez, M. Diaz; Lopez, E. Contreras

2008-10-01T23:59:59.000Z

19

System-Scale Model of Aquifer, Vadose Zone, and River Interactions for the Hanford 300 Area - Application to Uranium Reactive Transport  

SciTech Connect (OSTI)

This report represents a synthesis and integration of basic and applied research into a system-scale model of the Hanford 300 Area groundwater uranium plume, supported by the U.S. Department of Energys Richland Operations (DOE-RL) office. The report integrates research findings and data from DOE Office of Science (DOE-SC), Office of Environmental Management (DOE-EM), and DOE-RL projects, and from the site remediation and closure contractor, Washington Closure Hanford, LLC (WCH). The three-dimensional, system-scale model addresses water flow and reactive transport of uranium for the coupled vadose zone, unconfined aquifer, and Columbia River shoreline of the Hanford 300 Area. The system-scale model of the 300 Area was developed to be a decision-support tool to evaluate processes of the total system affecting the groundwater uranium plume. The model can also be used to address what if questions regarding different remediation endpoints, and to assist in design and evaluation of field remediation efforts. For example, the proposed cleanup plan for the Hanford 300 Area includes removal, treatment, and disposal of contaminated sediments from known waste sites, enhanced attenuation of uranium hot spots in the vadose and periodically rewetted zone, and continued monitoring of groundwater with institutional controls. Illustrative simulations of polyphosphate infiltration were performed to demonstrate the ability of the system-scale model to address these types of questions. The use of this model in conjunction with continued field monitoring is expected to provide a rigorous basis for developing operational strategies for field remediation and for defining defensible remediation endpoints.

Rockhold, Mark L.; Bacon, Diana H.; Freedman, Vicky L.; Parker, Kyle R.; Waichler, Scott R.; Williams, Mark D.

2013-10-01T23:59:59.000Z

20

Reactive transport modeling to study changes in water chemistry induced by CO2 injection at the Frio-I brine pilot  

SciTech Connect (OSTI)

To demonstrate the potential for geologic storage of CO{sub 2} in saline aquifers, the Frio-I Brine Pilot was conducted, during which 1600 tons of CO{sub 2} were injected into a high-permeability sandstone and the resulting subsurface plume of CO{sub 2} was monitored using a variety of hydrogeological, geophysical, and geochemical techniques. Fluid samples were obtained before CO{sub 2} injection for baseline geochemical characterization, during the CO{sub 2} injection to track its breakthrough at a nearby observation well, and after injection to investigate changes in fluid composition and potential leakage into an overlying zone. Following CO{sub 2} breakthrough at the observation well, brine samples showed sharp drops in pH, pronounced increases in HCO{sub 3}{sup -} and aqueous Fe, and significant shifts in the isotopic compositions of H{sub 2}O and dissolved inorganic carbon. Based on a calibrated 1-D radial flow model, reactive transport modeling was performed for the Frio-I Brine Pilot. A simple kinetic model of Fe release from the solid to aqueous phase was developed, which can reproduce the observed increases in aqueous Fe concentration. Brine samples collected after half a year had lower Fe concentrations due to carbonate precipitation, and this trend can be also captured by our modeling. The paper provides a method for estimating potential mobile Fe inventory, and its bounding concentration in the storage formation from limited observation data. Long-term simulations show that the CO{sub 2} plume gradually spreads outward due to capillary forces, and the gas saturation gradually decreases due to its dissolution and precipitation of carbonates. The gas phase is predicted to disappear after 500 years. Elevated aqueous CO{sub 2} concentrations remain for a longer time, but eventually decrease due to carbonate precipitation. For the Frio-I Brine Pilot, all injected CO{sub 2} could ultimately be sequestered as carbonate minerals.

Kharaka, Y.K; Doughty, C.; Freifeld, B.M.; Daley, T.M.; Xu, T.

2009-11-01T23:59:59.000Z

Note: This page contains sample records for the topic "reactive transport models" 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

Influence of calcite on uranium(VI) reactive transport in the groundwaterriver mixing zone  

SciTech Connect (OSTI)

Calcite is an important mineral that can affect uranyl reactive transport in subsurface sediments. This study investigated the distribution of calcite and its influence on uranyl adsorption and reactive transport in the groundwater-river mixing zone at US Hanford 300A, Washington State. Simulations using a 2D reactive transport model under field-relevant hydrogeochemical conditions revealed a complex distribution of calcite concentration as a result of dynamic groundwater-river interactions. The calcite concentration distribution in turn affected the spatial and temporal changes in aqueous carbonate, calcium, and pH, which subsequently influenced U(VI) mobility and discharge rates into the river. The results implied that calcite distribution and its concentration dynamics is an important consideration for field characterization, monitoring, and reactive transport prediction.

Ma, Rui; Liu, Chongxuan; Greskowiak, Janek; Prommer, Henning; Zachara, John M.; Zheng, Chunmiao

2014-01-23T23:59:59.000Z

22

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

23

STOMP-ECKEChem: An Engineering Perspective on Reactive Transport in Geologic Media  

SciTech Connect (OSTI)

ECKEChem (Equilibrium, Conservation, Kinetic Equation Chemistry) is a reactive transport module for the STOMP suite of multifluid subsurface flow and transport simulators that was developed from an engineering perspective. STOMP comprises a suite of operational modes that are distinguished by the solved coupled conservation equations with capabilities for a variety of subsurface applications (e.g., environmental remediation and stewardship, geologic sequestration of greenhouse gases, gas hydrate production, and oil shale production). The ECKEChem module was designed to provide integrated reactive transport capabilities across the suite of STOMP simulator operational modes. The initial application for the ECKEChem module was in the simulation of the mineralization reactions that occurred with the injection of supercritical carbon dioxide into deep Columbia River basalt formations, where it was implemented in the STOMP-CO2 simulator. The STOMP-ECKEChem solution approach to modeling reactive transport in multifluid geologic media is founded on an engineering perspective: (1) sequential non-iterative coupling between the flow and reactive transport is sufficient, (2) reactive transport can be modeled by operator splitting with local geochemistry and global transport, (3) geochemistry can be expressed as a system of coupled nonlinear equilibrium, conservation and kinetic equations, (4) a limited number of kinetic equation forms are used in geochemical practice. This chapter describes the conceptual approach to converting a geochemical reaction network into a series of equilibrium, conservation and kinetic equations, the implementation of ECKEChem in STOMP, the numerical solution approach, and a demonstration of the simulator on a complex application involving desorption of uranium from contaminated field-textured sediments.

White, Mark D.; Fang, Yilin

2012-04-04T23:59:59.000Z

24

UZ Colloid Transport Model  

SciTech Connect (OSTI)

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

25

RAFT: A simulator for ReActive Flow and Transport of groundwater contaminants  

SciTech Connect (OSTI)

This report documents the use of the simulator RAFT for the ReActive flow and Transport of groundwater contaminants. RAFT can be used as a predictive tool in the design and analysis of laboratory and field experiments or it can be used for the estimation of model/process parameters from experiments. RAFT simulates the reactive transport of groundwater contaminants in one, two-, or three-dimensions and it can model user specified source/link configurations and arbitrary injection strategies. A suite of solvers for transport, reactions and regression are employed so that a combination of numerical methods best suited for a problem can be chosen. User specified coupled equilibrium and kinetic reaction systems can be incorporated into RAFT. RAFT is integrated with a symbolic computational language MAPLE, to automate code generation for arbitrary reaction systems. RAFT is expected to be used as a simulator for engineering design for field experiments in groundwater remediation including bioremediation, reactive barriers and redox manipulation. As an integrated tool with both the predictive ability and the ability to analyze experimental data, RAFT can help in the development of remediation technologies, from laboratory to field.

Chilakapati, A.

1995-07-01T23:59:59.000Z

26

Modeling of coupled heat transfer and reactive transport processes in porous media: Application to seepage studies at Yucca Mountain, Nevad a  

E-Print Network [OSTI]

Fractured Rock of Yucca Mountain, Nevada: Heterogeneity andfractured rocks of Yucca Mountain have been extensivelyHydrothermal Flow at Yucca Mountain, Part I: Modeling and

Mukhopadhyay, S.; Sonnenthal, E.L.; Spycher, N.

2008-01-01T23:59:59.000Z

27

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

28

Chemically Reactive Working Fluids for the Capture and Transport...  

Broader source: Energy.gov (indexed) [DOE]

Optical Waveguide Coupler Transformers for High-Power Solar Enegy Collection and Transmission Chemically Reactive Working Fluids Low-Cost Light Weigh Thin Film Solar Concentrators...

29

Cellular-automaton model for reactive systems  

Science Journals Connector (OSTI)

A method for constructing a variety of probabilistic lattice-gas cellular automata for chemically reacting systems is described. The microscopic reactive dynamics give rise to a general fourth-order polynomial rate law for the average particle density. The reduction of the microdynamical equations to a discrete or continuous Boltzmann equation is presented. Connection between the linearized Boltzmann equations and a reaction-diffusion macroscopic equation is discussed. As an example of the general formalism a set of cellular automata rules that yield the Schlgl phenomenological model is constructed. Simulation results are presented.

David Dab; Anna Lawniczak; Jean-Pierre Boon; Raymond Kapral

1990-05-14T23:59:59.000Z

30

Final Report Coupled In Silico Microbial and Geochemical Reactive Transport Models: Extension to Multi-Organism Communities, Upscaling, and Experimental Validation  

SciTech Connect (OSTI)

The project was highly successful in improving the understanding of physiological and ecological factors controlling the growth and interaction of subsurface microorganisms and in developing better strategies for in silico modeling of the interactions of subsurface microorganisms with other species and their environment.

Lovley, Derek R.

2014-03-05T23:59:59.000Z

31

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

32

Release of aged contaminants from weathered sediments: Effects of sorbate speciation on scaling of reactive transport  

SciTech Connect (OSTI)

Hanford sediments impacted by hyperalkaline high level radioactive waste have undergone incongruent silicate mineral weathering concurrent with contaminant uptake. In this project, we studied the impact of background pore water (BPW) on strontium, cesium and iodine desorption and transport in Hanford sediments that were experimentally weathered by contact with simulated hyperalkaline tank waste leachate (STWL) solutions. Using those lab-weathered Hanford sediments (HS) and model precipitates formed during nucleation from homogeneous STWL solutions (HN), we (i) provided thorough characterization of reaction products over a matrix of field-relevant gradients in contaminant concentration, partial pressure of carbon dioxide, and reaction time; (ii) improved molecular-scale understanding of how sorbate speciation controls contaminant desorption from weathered sediments upon removal of caustic sources; and (iii) developed a mechanistic, predictive model of meso- to field-scale contaminant reactive transport under these conditions. In this final report, we provide detailed descriptions of our results from this three-year study, completed in 2012 following a one-year no cost extension.

Chorover, Jon; Perdrial, Nico; Mueller, Karl; Strepka, Caleb; Oƒ ƒ ‚ ¢ƒ ‚ ‚ € ƒ ‚ ‚ ™ Day, Peggy; Rivera, Nelson; Um, Wooyong; Chang, Hyun-Shik; Steefel, Carl; Thompson, Aaron

2012-11-05T23:59:59.000Z

33

Modeling Sorption and Exchange Processes in Column Experiments and Large Scale Field Studies  

Science Journals Connector (OSTI)

This paper demonstrates the possibilities of reactive transport modeling in predicting contaminant transport processes of laboratory and field scales. Basic approaches of reactive transport modeling are discu...

Olaf Nitzsche; Harry Vereecken

2002-04-01T23:59:59.000Z

34

From Teleo-Reactive specifications to architectural components: A model-driven approach  

Science Journals Connector (OSTI)

The Teleo-Reactive approach designed by N.J. Nilsson offers a high-level programming model that permits the development of reactive systems, such as robotic vehicles. Teleo-Reactive programs are written in a manner that allows engineers to define the ... Keywords: Component-based software development, Model-driven software development, Reactive systems, Robotics, Teleo-Reactive programs

Pedro SNchez; Diego Alonso; Jos Miguel Morales; Pedro Javier Navarro

2012-11-01T23:59:59.000Z

35

Fluid-Rock Interaction: A Reactive Transport Approach  

Science Journals Connector (OSTI)

...fluid-rock interaction systems as well-mixed reactors was challenged and it was shown how an...Q, Lichtner PC, Zhang D (2007) An improved lattice Boltzmann model for multicomponent...Eric H. editor CNRS-Universite Paul Sabatier, Laboratoire de Mecanisme de Transfert...

Carl I. Steefel; Kate Maher

36

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

37

Final Project Report: Release of aged contaminants from weathered sediments: Effects of sorbate speciation on scaling of reactive transport  

SciTech Connect (OSTI)

Hanford sediments impacted by hyperalkaline high level radioactive waste have undergone incongruent silicate mineral weathering concurrent with contaminant uptake. In this project, we studied the impact of background pore water (BPW) on strontium, cesium and iodine desorption and transport in Hanford sediments that were experimentally weathered by contact with simulated hyperalkaline tank waste leachate (STWL) solutions. Using those lab-weathered Hanford sediments (HS) and model precipitates formed during nucleation from homogeneous STWL solutions (HN), we (i) provided detailed characterization of reaction products over a matrix of field-relevant gradients in contaminant concentration, PCO2, and reaction time; (ii) improved molecular-scale understanding of how sorbate speciation controls contaminant desorption from weathered sediments upon removal of caustic sources; and (iii) developed a mechanistic, predictive model of meso- to field-scale contaminant reactive transport under these conditions.

Jon Chorover, University of Arizona; Peggy O'‚ € ‚ ™ Day, University of California, Merced; Karl Mueller, Penn State University; Wooyong Um, Pacific Northwest National Laboratory; Carl Steefel, Lawrence Berkeley National Laboratory

2012-10-01T23:59:59.000Z

38

Toward a new paradigm for reactive flow modeling.  

SciTech Connect (OSTI)

Traditional reactive flow modeling provides a computational representation of shock initiation of energetic materials. Most reactive flow models require ad hoc assumptions to obtain robust simulations, assumptions that result from partitioning energy and volume change between constituents in a reactive mixture. For example, most models assume pressure and/or temperature equilibrium for the mixture. Many mechanical insults to energetic materials violate these approximations. Careful analysis is required to ensure that the model assumptions and limitations are not exceeded. One limitation is that the shock to detonation transition is replicated only for strong planar shocks. Many models require different parameters to match data from thin pulse, ramp wave, or multidimensional loading, an approach that fails for complex loading. To accurately simulate reaction under non-planar shock impact scenarios a new formalism is required. The continuum mixture theory developed by Baer and Nunziato is used to eliminate ad hoc assumptions and limitations of current reactive flow models. This modeling paradigm represents the multiphase nature of reacting condensed/gas mixtures. Comparisons between simulations and data are presented.

Schmitt, Robert Gerard

2005-08-01T23:59:59.000Z

39

Modeling subsurface contaminant reactions and transport at the watershed scale  

SciTech Connect (OSTI)

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

40

High Performance Computations of Subsurface Reactive Transport Processes at the Pore Scale  

E-Print Network [OSTI]

such as carbon sequestration drive the geochemistry of porous media far from equilibrium in relatively short time in reservoir scale models. In the DOE Energy Frontier Research Center for Nanoscale Control of Geologic Carbon such as reactive surface area or reaction rates as they affect CO2 sequestration, with an objective of upscaling

Note: This page contains sample records for the topic "reactive transport models" 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

Reactive cluster model of metallic glasses  

SciTech Connect (OSTI)

Though discovered more than a half century ago metallic glasses remain a scientific enigma. Unlike crystalline metals, characterized by short, medium, and long-range order, in metallic glasses short and medium-range order persist, though long-range order is absent. This fact has prompted research to develop structural descriptions of metallic glasses. Among these are cluster-based models that attribute amorphous structure to the existence of clusters that are incommensurate with crystalline periodicity. Not addressed, however, are the chemical factors stabilizing these clusters and promoting their interconnections. We have found that glass formers are characterized by a rich cluster chemistry that above the glass transformation temperature promotes exchange as well as static and vibronic sharing of atoms between clusters. The vibronic mechanism induces correlated motions between neighboring clusters and we hypothesize that the distance over which these motions are correlated mediates metallic glass stability and influences critical cooling rates.

Jones, Travis E. [Molecular Theory Group, Colorado School of Mines, Golden, Colorado 80401 (United States) [Molecular Theory Group, Colorado School of Mines, Golden, Colorado 80401 (United States); School of Physics, The University of Sydney, Sydney, New South Wales 2006 (Australia); Miorelli, Jonathan; Eberhart, Mark E. [Molecular Theory Group, Colorado School of Mines, Golden, Colorado 80401 (United States)] [Molecular Theory Group, Colorado School of Mines, Golden, Colorado 80401 (United States)

2014-02-28T23:59:59.000Z

42

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

43

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

SciTech Connect (OSTI)

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

44

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.

45

NREL: Transportation Research - Data, Models, and Tools  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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,...

46

Transport Modeling Working Group Meeting Reports  

Broader source: Energy.gov [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.

47

SATURATED ZONE FLOW AND TRANSPORT MODEL ABSTRACTION  

SciTech Connect (OSTI)

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

48

Pore-scale simulation of coupled reactive transport and dissolution in fractures and porous media using the level set interface tracking method  

SciTech Connect (OSTI)

A level set simulation methodology developed for modeling coupled reactive transport and structure evolution has been applied to dissolution in fracture apertures and porous media. The coupled processes such as fluid flow, reactant transport and dissolution at the solid-liquid interfaces are handled simultaneously. The reaction-induced evolution of solid-liquid interfaces is captured using the level set method, with the advantage of representing the interface with sub-grid scale resolution. The coupled processes are simulated for several geometric models of fractures and porous media under various flow conditions and reaction rates. Quantitative relationships between permeability and porosity are obtained from some of the simulation results and compared with analytical constitutive relations (i.e., the conventional cubic law and the Carman-Kozeny law) based on simplified pore space geometries and reaction induced geometric evolutions. The drastic deviation of the simulation results from these analytical theories is explained by the development of large local concentration gradients of reactants within fracture apertures and individual pores observed in the simulation results and consequently the complex geometric evolution patterns of fracture apertures and pores due to mineral dissolution. The simulation results support the argument that traditional constitutive relations based on simplified geometries and conditions have limited applicability in predicting field scale reactive transport and that incorporation of micro-scale physics is necessary.

Hai Huang; Xiaoyi Li

2011-01-01T23:59:59.000Z

49

Determination of the transport mechanisms in mixed conduction of reactively sputtered ZnO thin films  

Science Journals Connector (OSTI)

Material grown at highly Zn-rich conditions in reactive sputtering of ZnO thin films resulted in mixed conduction, indicating that stable p-type ZnO can be produced. In n-type conductivity, neutral flaw scattering transport mechanism via centres seems to be dominant due to the existence of oxygen vacancies in high concentrations. An exponential decrease in electron mobility is observed upon cooling from room temperature to 210?K while the concentration of the inactive state increases. This is also a cause of p-type conduction in the low temperature range ( scattering. Quantitative evaluations of VO centres show that fractional distribution of , and charge states are, respectively, around 4%, 95% and 1% of the total [VO] at the room temperature conditions. The energy of phonons interacting with the centre is estimated to be 38.5?meV which is a local phonon mode relaxation, most probably resulting in negative-U behaviour of VO centres.

S Tzemen; Emre Gr; S Do?an

2008-01-01T23:59:59.000Z

50

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...

51

Modeling biogechemical reactive transport in a fracture zone  

E-Print Network [OSTI]

is a prototype, full-scale underground facility launched andof Stockholm. The underground facility consists of a 3,600 m

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

2005-01-01T23:59:59.000Z

52

High-Resolution Simulation of Pore-Scale Reactive Transport Processes Associated with Carbon Sequestration  

Science Journals Connector (OSTI)

New investigative tools combined with experiments and computational methods are being developed to build a next-generation understanding of molecular-to-pore-scale processes in fluid-rock systems and to demonstrate the ability to control critical aspects of flow and transport in porous rock media in particular as applied to geologic sequestration of CO. Of scientific interest is to establish the rules governing emergent behavior at the porous-continuum macroscale under far from equilibrium conditions by carefully understanding the behavior at the underlying pore microscale. To this end the authors present a direct numerical simulation modeling capability that can resolve flow and transport processes in geometric features obtained from the image data of realistic pore space at unprecedented scale and resolution. Here they focus on scaling a new algorithmic approach based on embedded boundary finite-volume methods and algebraic multigrid. They demonstrate the scalability of this new capability known as Chombo-Crunch to more than 100 000 processor cores and show results from pore-scale flow and transport in the realistic pore space obtained from image data.

2014-01-01T23:59:59.000Z

53

Cooperative Strategies and Reactive Search: A Hybrid Model Proposal  

Science Journals Connector (OSTI)

Cooperative strategies and reactive search are very promising techniques for solving hard optimization problems, since they reduce human intervention required to set up a method when the resolution of an unknown instance is needed. However, as far as ...

Antonio D. Masegosa; Franco Mascia; David Pelta; Mauro Brunato

2009-11-01T23:59:59.000Z

54

Fuel Cell Technologies Office: Transport Modeling Working Group  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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

55

Photochemical Modeling of Emissions Trading of Highly Reactive Volatile Organic Compounds in Houston, Texas. 1. Reactivity Based Trading and Potential for Ozone Hot Spot Formation  

Science Journals Connector (OSTI)

Photochemical Modeling of Emissions Trading of Highly Reactive Volatile Organic Compounds in Houston, Texas. ... (12)?Thompson, T. M.; Wang, L.; Web, A.; McDonald-Buller, E.; Allen, D. T. Photochemical Modeling of the Air Quality Impacts of an Emissions Trading Program for Highly Reactive Volatile Organic Compounds (HRVOCs) in Texas; Air and Waste Management Association Annual Meeting, New Orleans, June, 2006. ...

Linlin Wang; Tammy Thompson; Elena C. McDonald-Buller; Alba Webb; David T. Allen

2007-02-27T23:59:59.000Z

56

Modeling of Hydrogen Storage Materials: A Reactive Force Field for NaH  

E-Print Network [OSTI]

Modeling of Hydrogen Storage Materials: A Reactive Force Field for NaH Ojwang' J.G.O.*, Rutger van is the fall in potential energy surface during heating. Keywords: hydrogen storage, reactive force field governing hydrogen desorption in NaH. During the abstraction process of surface molecular hydrogen charge

Goddard III, William A.

57

Argonne's GREET Model - Driving Transportation Solutions  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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.

58

Model Recovery Procedure for Response to a Radiological Transportation Incident  

Broader source: Energy.gov [DOE]

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

59

Abstracts of the symposium on unsaturated flow and transport modeling  

SciTech Connect (OSTI)

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

60

Mechanical models of fracture reactivation and slip on bedding surfaces during folding of the asymmetric anticline at Sheep Mountain, Wyoming  

E-Print Network [OSTI]

Mechanical models of fracture reactivation and slip on bedding surfaces during folding June 2008 Accepted 5 June 2008 Available online 13 June 2008 Keywords: Fold Fracture reactivation Bed methods to investigate the reactivation of fractures (opening and shearing) and the development of bedding

Borja, Ronaldo I.

Note: This page contains sample records for the topic "reactive transport models" 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

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

62

Model for the transport of airborne radioiodine  

SciTech Connect (OSTI)

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

63

Nanoscale study of reactive transport in catalyst layer of proton exchange membrane fuel cells with precious and non-precious catalysts using lattice Boltzmann method  

E-Print Network [OSTI]

High-resolution porous structures of catalyst layer (CL) with multicomponent in proton exchange membrane fuel cells are reconstructed using a reconstruction method called quartet structure generation set. Characterization analyses of nanoscale structures are implemented including pore size distribution, specific area and phase connectivity. Pore-scale simulation methods based on the lattice Boltzmann method are developed and used to predict the macroscopic transport properties including effective diffusivity and proton conductivity. Nonuniform distributions of ionomer in CL generates more tortuous pathway for reactant transport and greatly reduces the effective diffusivity. Tortuosity of CL is much higher than conventional Bruggeman equation adopted. Knudsen diffusion plays a significant role in oxygen diffusion and significantly reduces the effective diffusivity. Reactive transport inside the CL is also investigated. Although the reactive surface area of non-precious metal catalyst (NPMC) CL is much higher t...

Chen, Li; Kang, Qinjun; Holby, Edward F; Tao, Wen-Quan

2014-01-01T23:59:59.000Z

64

Reactive scattering in the bending-corrected rotating linear model  

SciTech Connect (OSTI)

We review the theory and applications of the Bending-Corrected Rotating Linear Model (BCRLM) to problems in the quantum description of reactions between atoms and diatomic molecules. 110 refs.

Walker, R.B.; Hayes, E.F.

1985-01-01T23:59:59.000Z

65

Fluid flow and reactive transport around potential nuclear waste emplacement tunnels at Yucca Mountain, Nevada  

E-Print Network [OSTI]

Unsaturated Zone at Yucca Mountain, Nevada. U.S. Geologicalzone model at Yucca Mountain, Nevada. J. Contaminantinvesti- gations at Yucca Mountain - the potential

Spycher, N.F.; Sonnenthal, E.L.; Apps, J.A.

2002-01-01T23:59:59.000Z

66

An Operator Splitting Method for Nonlinear Reactive Transport Equations and Its  

E-Print Network [OSTI]

model ground- water contaminant biodegradation and many other interesting applications. The proposed contaminants in groundwater provides valuable guidelines for in-situ remediation strategies. Injection

Ewing, Richard E.

67

Modeling the reactive inorganic solute distributions in the groundwater flow systems of the Hanford Site using inverse analytical modeling techniques.  

E-Print Network [OSTI]

??Inverse analytical techniques were used to model solute distributions and determine transport parameters for two flow systems in the Yakima Basalt subgroup at the Hanford (more)

Adamski, Mark Robert

2012-01-01T23:59:59.000Z

68

Reactive self-heating model of aluminum spherical nanoparticles  

E-Print Network [OSTI]

Aluminum-oxygen reaction is important in many highly energetic, high pressure generating systems. Recent experiments with nanostructured thermites suggest that oxidation of aluminum nanoparticles occurs in a few microseconds. Such rapid reaction cannot be explained by a conventional diffusion-based mechanism. We present a rapid oxidation model of a spherical aluminum nanoparticle, using Cabrera-Mott moving boundary mechanism, and taking self-heating into account. In our model, electric potential solves the nonlinear Poisson equation. In contrast with the Coulomb potential, a "double-layer" type solution for the potential and self-heating leads to enhanced oxidation rates. At maximal reaction temperature of 2000 C, our model predicts overall oxidation time scale in microseconds range, in agreement with experimental evidence.

Karen S. Martirosyan; Maxim Zyskin

2012-12-17T23:59:59.000Z

69

Experimental and numerical modeling of convective proppant transport  

SciTech Connect (OSTI)

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

70

Documentation of TRU biological transport model (BIOTRAN)  

SciTech Connect (OSTI)

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

71

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

72

Chemically Reactive Working Fluids | Department of Energy  

Broader source: Energy.gov (indexed) [DOE]

Chemically Reactive Working Fluids for the Capture and Transport of Concentrated Solar Thermal Energy for Power Generation Chemically Reactive Working Fluids SunShot CSP...

73

Device Scale Model Development for Transport Reactor  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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

74

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

75

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

76

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

77

Reactive mercury in the troposphere: Model formation and results for Florida, the northeastern United States, and the Atlantic Ocean  

E-Print Network [OSTI]

. Divalent reactive gaseous mercury (RGM) in the atmo- sphere is water-soluble and is efficiently removed is the Community Multiscale Air Quality model (CMAQ) with modifications to include an integrated solution for gas and mercury. Divalent reactive gaseous mercury (RGM) is formed slowly through gas phase reactions and removed

Sillman, Sanford

78

Particle Tracking Model and Abstraction of Transport Processes  

SciTech Connect (OSTI)

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

79

Reduced Fast Ion Transport Model For The Tokamak Transport Code TRANSP  

SciTech Connect (OSTI)

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

80

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

Note: This page contains sample records for the topic "reactive transport models" 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

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

82

Fuel Cell Technologies Office: Transport Modeling Working Group  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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.

83

Modeling atmospheric deposition using a stochastic transport model  

SciTech Connect (OSTI)

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

84

Reactive Flow Modeling of Liquid Explosives via ALE3D/Cheetah Simulations  

SciTech Connect (OSTI)

We carried out reactive flow simulations of liquid explosives such as nitromethane using the hydrodynamic code ALE3D coupled with equations of state and reaction kinetics modeled by the thermochemical code Cheetah. The simulation set-up was chosen to mimic cylinder experiments. For pure unconfined nitromethane we find that the failure diameter and detonation velocity dependence on charge diameter are in agreement with available experimental results. Such simulations are likely to be useful for determining detonability and failure behavior for a wide range of experimental conditions and explosive compounds.

Kuo, I W; Bastea, S; Fried, L E

2010-03-10T23:59:59.000Z

85

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

86

Fokker-Planck/Transport model for neutral beam driven tokamaks  

SciTech Connect (OSTI)

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

87

Boltzmann-Langevin transport model for heavy-ion collisions  

SciTech Connect (OSTI)

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

88

Chemical Kinetic Modeling of Advanced Transportation Fuels  

SciTech Connect (OSTI)

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

89

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.

90

TOUGHREACT Version 2.0: A simulator for subsurface reactive transport under non-isothermal multiphase flow conditions  

SciTech Connect (OSTI)

TOUGHREACT is a numerical simulation program for chemically reactive non-isothermal flows of multiphase fluids in porous and fractured media, and was developed by introducing reactive chemistry into the multiphase fluid and heat flow simulator TOUGH2 V2. The first version of TOUGHREACT was released to the public through the U.S. Department of Energy's Energy Science and Technology Software Center (ESTSC) in August 2004. It is among the most frequently requested of ESTSC's codes. The code has been widely used for studies in CO{sub 2} geological sequestration, nuclear waste isolation, geothermal energy development, environmental remediation, and increasingly for petroleum applications. Over the past several years, many new capabilities have been developed, which were incorporated into Version 2 of TOUGHREACT. Major additions and improvements in Version 2 are discussed here, and two application examples are presented: (1) long-term fate of injected CO{sub 2} in a storage reservoir and (2) biogeochemical cycling of metals in mining-impacted lake sediments.

Xu, T.; Spycher, N.; Sonnenthal, E.; Zhang, G.; Zheng, L.; Pruess, K.

2010-08-01T23:59:59.000Z

91

Dynamic modeling of the reactive twin-screw co-rotating extrusion process: experimental validation by using inlet  

E-Print Network [OSTI]

and modification.1 The co-rotating twin-screw extruder is of particular interest due to its modular geometry or removing chemical species.3,4 Furthermore, the co-rotating twin-screw extruder can handle high viscosityDynamic modeling of the reactive twin-screw co-rotating extrusion process: experimental validation

Paris-Sud XI, Université de

92

Modeling the sorption dynamics of NaH using a reactive force field J. G. O. Ojwang,1,a  

E-Print Network [OSTI]

Modeling the sorption dynamics of NaH using a reactive force field J. G. O. Ojwang,1,a Rutger van that the fall in potential energy is associated with either cluster fragmentation or de- sorption of molecular ReaxFFNaAlH4 to study the structural and dynamical details of hydrogen ab de sorption processes in Na

Goddard III, William A.

93

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

94

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

95

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

96

Airflow and Pollutant Transport Modeling In Indoor and Built Environment  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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

97

Validation of transport models using additive flux minimization technique  

SciTech Connect (OSTI)

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

98

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

99

Mitochondrial reactive oxygen species and cancer  

E-Print Network [OSTI]

Mitochondria produce reactive oxygen species (mROS) as a natural by-product of electron transport chain activity. While initial studies focused on the damaging effects of reactive oxygen species, a recent paradigm shift ...

Chandel, Navdeep S

100

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

SciTech Connect (OSTI)

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

Note: This page contains sample records for the topic "reactive transport models" 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

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

SciTech Connect (OSTI)

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

102

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

103

Transportation  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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.

104

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

SciTech Connect (OSTI)

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

105

Transportation  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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

106

Lessons Learned from Alternative Transportation Fuels: Modeling Transition Dynamics  

Alternative Fuels and Advanced Vehicles Data Center [Office of Energy Efficiency and Renewable Energy (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

107

Research Activities at U.S. Government Agencies in Subsurface Reactive Transport Modeling  

Science Journals Connector (OSTI)

...Therefore, it is critical to understand and...CO. A list of critical contaminants related...Parks Shallow Land Disposal Area Parks Township...Rifle, CO X X UMTRA Salt Lake City, UT X...field experiments are critical complements to the...Available at www.srs.gov/general...

Randall T. Cygan; Caroline T. Stevens; Robert W. Puls; Steven B. Yabusaki; Robert D. Wauchope; Christian J. McGrath; Gary P. Curtis; Malcolm D. Siegel; Linda A. Veblen; David R. Turner

108

Stochastic modeling of transport and degradation of reactive solutes in heterogeneous aquifers  

E-Print Network [OSTI]

and Rubin, 1996]. Hydraulic properties can be represented mathematically as stationary correlated space random functions (SRF). SRFs are usually characterized by their first two statistical moments: the mean and the variance [Gelhar...

Fadel, Ziad Joseph

2006-08-16T23:59:59.000Z

109

Uncertainty in the reactive transport model response to an alkaline perturbation in a clay formation  

E-Print Network [OSTI]

CSH_1.1 Gismondine Gyrolite Ettringite Katoite Stratlingite2) monosulfoaluminate ? ettringite. In clay, the major paths

Burnol, A.; Blanc, P.; Xu, T.; Spycher, N.; Gaucher, E.C.

2006-01-01T23:59:59.000Z

110

Reactive Transport Modeling of Natural Attenuation in Stormwater Bioretention Cells and Under Land Application of Wastewater  

E-Print Network [OSTI]

Natural attenuation is a cost effective method to treat wastewater applied into soil. The natural attenuation process includes diffusion, dispersion, microbial activity, oxidation, mineral precipitation, sorption, and ion exchange to mitigate...

Zhang, Jingqiu

2014-04-29T23:59:59.000Z

111

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

112

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

SciTech Connect (OSTI)

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

113

Environmental Transport Input Parameters for the Biosphere Model  

SciTech Connect (OSTI)

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

Transportation System Risk Assessment (TSRA) bounding release model  

SciTech Connect (OSTI)

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

115

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

116

Environmental Transport Input Parameters for the Biosphere Model  

SciTech Connect (OSTI)

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

117

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

118

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

119

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

SciTech Connect (OSTI)

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

120

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

Broader source: Energy.gov (indexed) [DOE]

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

Note: This page contains sample records for the topic "reactive transport models" 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.


121

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

122

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

123

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

124

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

125

Reactive Maintenance  

Broader source: Energy.gov [DOE]

Reactive maintenance follows a run-it-until-it-breaks strategy where no actions or efforts are taken to maintain equipment as intended by the manufacturer. Studies indicate this is still the predominant mode of maintenance for Federal facilities.

126

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.

127

Validation Analysis of the Shoal Groundwater Flow and Transport Model  

SciTech Connect (OSTI)

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

128

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

129

Modeling of coulpled deformation and permeability evolution during fault reactivation induced by deep underground injection of CO2  

SciTech Connect (OSTI)

The interaction between mechanical deformation and fluid flow in fault zones gives rise to a host of coupled hydromechanical processes fundamental to fault instability, induced seismicity, and associated fluid migration. In this paper, we discuss these coupled processes in general and describe three modeling approaches that have been considered to analyze fluid flow and stress coupling in fault-instability processes. First, fault hydromechanical models were tested to investigate fault behavior using different mechanical modeling approaches, including slip interface and finite-thickness elements with isotropic or anisotropic elasto-plastic constitutive models. The results of this investigation showed that fault hydromechanical behavior can be appropriately represented with the least complex alternative, using a finite-thickness element and isotropic plasticity. We utilized this pragmatic approach coupled with a strain-permeability model to study hydromechanical effects on fault instability during deep underground injection of CO{sub 2}. We demonstrated how such a modeling approach can be applied to determine the likelihood of fault reactivation and to estimate the associated loss of CO{sub 2} from the injection zone. It is shown that shear-enhanced permeability initiated where the fault intersects the injection zone plays an important role in propagating fault instability and permeability enhancement through the overlying caprock.

Cappa, F.; Rutqvist, J.

2010-06-01T23:59:59.000Z

130

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

Broader source: Energy.gov (indexed) [DOE]

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

131

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

132

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

SciTech Connect (OSTI)

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

133

Modeling of Diesel Exhaust Systems: A methodology to better simulate soot reactivity  

Broader source: Energy.gov [DOE]

Discussed development of a methodology for creating accurate soot models for soot samples from various origins with minimal characterization

134

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

135

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

136

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

137

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

138

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

139

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

140

Reactive Geochemical Transport Modeling of Concentrated Aqueous Solutions: Supplement to TOUGHREACT User's Guide for the Pitzer Ion-Interaction Model  

E-Print Network [OSTI]

Activity Coefficient of CaCl2 80 degree C Measured Osmotic80 degree C Measured Calculated Molality of CaCl2 Molalityof CaCl2 Figure 5-1. Comparison of the TOUGHREACT-

Zhang, Guoxiang; Spycher, Nicolas; Xu, Tianfu; Sonnenthal, Eric; Steefel, Carl

2006-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "reactive transport models" 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

Reactive Geochemical Transport Modeling of Concentrated Aqueous Solutions: Supplement to TOUGHREACT User's Guide for the Pitzer Ion-Interaction Model  

E-Print Network [OSTI]

gypsum, niter, soda niter, halite, sylvite, epsomite, Mg(NO7 1.0E-8 1.0E-9 Gypsum Halite CaCl2:2H2O Sylvite Calcite Na+

Zhang, Guoxiang; Spycher, Nicolas; Xu, Tianfu; Sonnenthal, Eric; Steefel, Carl

2006-01-01T23:59:59.000Z

142

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

143

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

SciTech Connect (OSTI)

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

144

Transportation  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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.

145

ReaxFF Reactive Force Field for Solid Oxide Fuel Cell Systems with Application to Oxygen Ion Transport in Yttria-Stabilized Zirconia  

E-Print Network [OSTI]

ReaxFF Reactive Force Field for Solid Oxide Fuel Cell Systems with Application to Oxygen Ion through yttria-stabilized zirconia (YSZ) solid oxide fuel cell (SOFC) membranes. All parameters for Reax temperature, leading to applications as oxygen sensors and as membranes for high temperature solid oxide fuel

Goddard III, William A.

146

Chemical characterization of ozone formation in the Houston-Galveston area: A chemical transport model study  

E-Print Network [OSTI]

: Constituent sources and sinks; 0345 Atmospheric Composition and Structure: Pollution--urban and regional (0305 of the atmosphere and hence the lifetime of reactive atmospheric pollutants and many re- duced chemical species. O3 model study Wenfang Lei1 and Renyi Zhang Department of Atmospheric Sciences, Texas A&M University

147

REACTIVE FLOW IN VUGGY CARBONATES: METHODS AND MODELS APPLIED TO MATRIX ACIDIZING OF CARBONATES  

E-Print Network [OSTI]

Carbonates invariably have small (micron) to large (centimeter) scale heterogeneities in flow properties that may cause the effects of injected acids to differ greatly from what is predicted by a model based on a homogenous formation. To the best...

Izgec, Omer

2010-07-14T23:59:59.000Z

148

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

149

Model Annex for Preparedness and Response to Radiological Transportation Incidents  

Broader source: Energy.gov [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...

150

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

151

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

SciTech Connect (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 {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

152

A turbulent transport network model in MULTIFLUX coupled with TOUGH2  

SciTech Connect (OSTI)

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

153

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

154

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

155

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

156

* 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

157

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

158

DYNAMIC MODELING AND CONTROL OF REACTIVE DISTILLATION FOR HYDROGENATION OF BENZENE  

E-Print Network [OSTI]

at other photolysis wave- lengths were also simulated. The OH transitions were labeled following Hund?s case (a). The P, Q, or R branches are for the cases of ?J or ?N )-1, 0, and 1, and the subscript 1 or 2 represents the different spin-orbit states ? 3/2... out in different processing units 1. Consequently, there has been a lot of interest in this type of process intensification in recent years. Emphasis has been on steady-state modeling and the foundations of RD column design. Still, comparably little...

Aluko, Obanifemi

2010-01-16T23:59:59.000Z

159

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

160

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

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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...

Note: This page contains sample records for the topic "reactive transport models" 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

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

162

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

163

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

164

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

165

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.

166

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

167

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

168

Photochemical Modeling of Emissions Trading of Highly Reactive Volatile Organic Compounds in Houston, Texas. 2. Incorporation of Chlorine Emissions  

Science Journals Connector (OSTI)

As part of the State Implementation Plan for attaining the National Ambient Air Quality Standard for ozone, the Texas Commission of Environmental Quality has created a Highly Reactive Volatile Organic Compounds (HRVOC) Emissions Cap and Trade Program for ...

Linlin Wang; Tammy Thompson; Elena C. McDonald-Buller; David T. Allen

2007-02-27T23:59:59.000Z

169

A SCOPING STUDY: Development of Probabilistic Risk Assessment Models for Reactivity Insertion Accidents During Shutdown In U.S. Commercial Light Water Reactors  

SciTech Connect (OSTI)

This report documents the scoping study of developing generic simplified fuel damage risk models for quantitative analysis from inadvertent reactivity insertion events during shutdown (SD) in light water pressurized and boiling water reactors. In the past, nuclear fuel reactivity accidents have been analyzed both mainly deterministically and probabilistically for at-power and SD operations of nuclear power plants (NPPs). Since then, many NPPs had power up-rates and longer refueling intervals, which resulted in fuel configurations that may potentially respond differently (in an undesirable way) to reactivity accidents. Also, as shown in a recent event, several inadvertent operator actions caused potential nuclear fuel reactivity insertion accident during SD operations. The set inadvertent operator actions are likely to be plant- and operation-state specific and could lead to accident sequences. This study is an outcome of the concern which arose after the inadvertent withdrawal of control rods at Dresden Unit 3 in 2008 due to operator actions in the plant inadvertently three control rods were withdrawn from the reactor without knowledge of the main control room operator. The purpose of this Standardized Plant Analysis Risk (SPAR) Model development project is to develop simplified SPAR Models that can be used by staff analysts to perform risk analyses of operating events and/or conditions occurring during SD operation. These types of accident scenarios are dominated by the operator actions, (e.g., misalignment of valves, failure to follow procedures and errors of commissions). Human error probabilities specific to this model were assessed using the methodology developed for SPAR model human error evaluations. The event trees, fault trees, basic event data and data sources for the model are provided in the report. The end state is defined as the reactor becomes critical. The scoping study includes a brief literature search/review of historical events, developments of a small set of comprehensive event trees and fault trees and recommendation for future work.

S. Khericha

2011-06-01T23:59:59.000Z

170

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

171

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"

172

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

173

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

SciTech Connect (OSTI)

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

174

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

SciTech Connect (OSTI)

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

175

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

176

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

177

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

178

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

179

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

180

Dependence of post-drop reactivity on data analysis model for rod drop experiment in a subcritical reactor with external source  

SciTech Connect (OSTI)

This paper presents an improved rod-drop reactivity and source strength measurement by the inverse kinetics method in subcritical reactor system. The inverse kinetics method extended to be applicable to subcritical system, which is referred to as least squares inverse kinetics method (LSIKM), can estimate both the reactivity and the external source strength by applying least square approximation. However, the application of the conventional fitting model of the LSIKM to fluctuating data leads to serious errors in the estimation. In this study, a specific fitting model proposed by Itagaki and Kitano is used for the LSIKM and the effectiveness for fluctuating data is demonstrated experimentally. Furthermore, the spatial dependence of the estimated results is investigated and the reduction method is proposed. (authors)

Taninaka, H. [Interdisciplinary Graduate School of Science and Technology, Kinki Univ., 3-4-1, Kowakae, Higashi-Osaka, 577-8502 (Japan); Hashimoto, K. [Atomic Energy Research Inst., Kinki Univ., 3-4-1, Kowakae, Higashi-Osaka, 577-8502 (Japan)

2006-07-01T23:59:59.000Z

Note: This page contains sample records for the topic "reactive transport models" 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

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

SciTech Connect (OSTI)

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

182

Mesoscopic modeling of liquid water transport in polymer electrolyte fuel cells  

SciTech Connect (OSTI)

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

183

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

184

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

SciTech Connect (OSTI)

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

185

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

SciTech Connect (OSTI)

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

186

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

SciTech Connect (OSTI)

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

187

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

Broader source: Energy.gov (indexed) [DOE]

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,

188

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

189

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 (OSTI)

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

190

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

191

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

192

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

193

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

194

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

SciTech Connect (OSTI)

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

195

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

196

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 (OSTI)

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

197

Mulitdimensional reactive transport modeling of CO2 minreal sequestration in basalts at the Helllisheidi geothermal field, Iceland  

E-Print Network [OSTI]

3 km SW of the Hellisheidi geothermal power plant, owned andbuilt next to Hellisheidi geothermal power plant. The pilotfrom Hellisheidi geothermal power plant. In simulations of

Aradottir, E.S.P.

2013-01-01T23:59:59.000Z

198

MSWI bottom ash used as basement at two pilot-scale roads: comparison of leachate chemistry and reactive transport modeling  

E-Print Network [OSTI]

-wollastonite and, finally, calcite in equilibrium with atmospheric CO2. Al(OH)3, barite, ettringite

Paris-Sud XI, Université de

199

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

SciTech Connect (OSTI)

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

200

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

SciTech Connect (OSTI)

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

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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

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

SciTech Connect (OSTI)

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

202

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

SciTech Connect (OSTI)

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

203

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.

204

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

205

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.

206

TOUGHREACT User's Guide: A Simulation Program for Non-isothermal Multiphase Reactive Geochemical Transport in Variably Saturated Geologic Media, V1.2.1  

E-Print Network [OSTI]

mineralogic model of Yucca Mountain, Nevada, Rev 2.0 . , Losfrom tuffs at Yucca Mountain, Nevada, USA. Geochim.in zeolitized tuffs at Yucca Mountain, Nevada, USA. Geochim.

Xu, Tianfu

2008-01-01T23:59:59.000Z

207

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

SciTech Connect (OSTI)

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

208

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

SciTech Connect (OSTI)

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

209

A comparative study on the CANDU-6 reactivity device model based on Wolsong-2 physics measurement data  

SciTech Connect (OSTI)

A benchmark calculation of a 713 MWe Canada deuterium uranium (CANDU) reactor was performed based on the physics measurement data of Wolsong-2 nuclear power plant by using WIMS-AECL, DRAGON, and RFSP codes. The benchmark calculation included sensitivity analyses on the number of energy groups, cross-section library, and the weighting spectrum of the homogenized lattice parameters. The effective multiplication factor, critical boron concentration, reactivity device worth and the flux distribution were estimated and compared with those obtained by the measurement and standard CANDU reactor physics design tools. In general, the prediction errors by WIMS-AECL, DRAGON and RFSP codes were within the acceptance limit for all the sensitivity calculations. The sensitivity calculations also showed that the calculation accuracy was improved when two energy groups were used especially for the prediction of the reactivity worth of strong absorbers such as mechanical control absorbers and shutoff rods. However, the prediction error increased when calculating the reactivity worth of the adjuster banks with two energy groups. Therefore a further study is recommended to obtain consistent results for the benchmark calculation. (authors)

Park, C. J.; Choi, H. [Korea Atomic Energy Research Inst., Deokjin-dong 150, Yuseong-gu, Daejeon (Korea, Republic of)

2006-07-01T23:59:59.000Z

210

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

SciTech Connect (OSTI)

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

211

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

SciTech Connect (OSTI)

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

212

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

SciTech Connect (OSTI)

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

213

Quantification of NA processes for the CAH-contamination in Karlsruhe-Ost/Killisfeld with the help of a groundwater model  

Science Journals Connector (OSTI)

Reactive transport of chlorinated aliphatic hydrocarbons (CAH) was simulated with a process oriented multi-species-model for a model domain of 4km2. The objective of the calculations was the quantification of NA...

Dr.-Ing. W. Schfer; Dr. F. Wickert; Dr. A. Tiehm

2007-06-01T23:59:59.000Z

214

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

SciTech Connect (OSTI)

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

215

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

216

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

217

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

218

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.

219

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

220

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

Note: This page contains sample records for the topic "reactive transport models" 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

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

222

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

223

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

224

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

225

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

226

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

227

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

SciTech Connect (OSTI)

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

228

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

SciTech Connect (OSTI)

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

229

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

230

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

231

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

SciTech Connect (OSTI)

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

232

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

SciTech Connect (OSTI)

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

233

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

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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

234

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

235

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

236

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

SciTech Connect (OSTI)

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

237

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

238

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

SciTech Connect (OSTI)

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

239

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

SciTech Connect (OSTI)

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

240

Curvature-based criteria for model reduction in chemical kinetics via optimization of trajectories  

E-Print Network [OSTI]

that the computational effort for a full simulation of reactive flows, e.g. of fluid transport involving combustion processes, is computationally extremely expensive. For a simulation in reasonable time reduced models

Gorban, Alexander N.

Note: This page contains sample records for the topic "reactive transport models" from the National Library of EnergyBeta (NLEBeta).
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We encourage you to perform a real-time search of NLEBeta
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241

Development and Evaluation of a State-of-the-Science Reactive Plume  

E-Print Network [OSTI]

for plume rise, plume visibility, and stack opacity (5). Examples of other reactive plume models include

Zhang, Yang

242

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

SciTech Connect (OSTI)

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

243

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

244

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

SciTech Connect (OSTI)

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

245

Modeling the Effect of Sedimentation on Cesium Transport in Fourmile Branch  

SciTech Connect (OSTI)

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

246

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

247

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

248

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

249

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

SciTech Connect (OSTI)

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

250

Reactivating personal memory 1 RUNNING HEAD: Reactivating personal memory  

E-Print Network [OSTI]

Reactivating personal memory 1 RUNNING HEAD: Reactivating personal memory Modifying memory: Selectively enhancing and updating personal memories for a museum; Reactivating personal memory 2 Abstract Memory can be modified when reactivated

Schacter, Daniel

251

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.

252

A multi-model assessment of pollution transport to the Arctic  

SciTech Connect (OSTI)

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

253

Groundwater transport modeling of constituents originating from the Burial Grounds Complex  

SciTech Connect (OSTI)

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

254

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

SciTech Connect (OSTI)

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

255

Area-preserving maps models of gyroaveraged EB chaotic transport  

SciTech Connect (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 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

256

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

257

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

258

Stable Isotope Fractionations in Biogeochemical Reactive Transport  

E-Print Network [OSTI]

Standard Review Plan for the Review of DOE Plans for Achieving Regulatory Compliance at Sites with Contaminated Groundwater under Title I of the Uranium

Druhan, Jennifer Lea

2012-01-01T23:59:59.000Z

259

Stable Isotope Fractionations in Biogeochemical Reactive Transport  

E-Print Network [OSTI]

between these values. (B) measured TIC in effluentand the calculated TIC assuming all acetate consumed (asin A) is converted to TIC. Dissolved methane concentrations

Druhan, Jennifer Lea

2012-01-01T23:59:59.000Z

260

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

Note: This page contains sample records for the topic "reactive transport models" 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

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

SciTech Connect (OSTI)

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

262

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

SciTech Connect (OSTI)

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

263

MSIV leakage airborne iodine transport  

SciTech Connect (OSTI)

Gaseous iodine deposits on surfaces exposed to vapors. Basic chemical and physical principles predict this behavior, and several laboratory and in-plant measurements demonstrate the characteristic. An empirical model was developed that describes the deposition, resuspension, and transformation of airborne radioiodine molecular species as a stream containing these forms moves along its pathway. The model uses a data base of measured values of deposition and resuspension rates in its application and describes the conversion of the more reactive inorganic iodine species I[sub 2] to the less reactive organic species CH[sub 3]I as the iodine deposits and resuspends along the path. It also considers radioactive decay and chemical surface bonding during residence on surfaces. For the 8-day [sup 131]I, decay during the airborne portion of the transport is negligible. Verification of the model included measurement tests of long gaseous-activity sampling lines of different diameters, operated at different flow rates and stream temperatures. The model was applied to the streams at a boiling water reactor nuclear power plant to describe the transport through leaking main steam isolation valves (MSIVs), following a loss-of-coolant accident.

Cline, J.E. (Cline Associates Inc., Rockville, MD (United States))

1993-01-01T23:59:59.000Z

264

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

SciTech Connect (OSTI)

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

265

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

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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

266

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

267

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

268

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

269

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

SciTech Connect (OSTI)

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

270

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

SciTech Connect (OSTI)

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

271

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

SciTech Connect (OSTI)

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

272

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

273

Numerical simulation of detonation structures using a thermodynamically consistent and fully conservative reactive flow model for multi-component computations  

Science Journals Connector (OSTI)

...there have been many advances in detonation modelling...apparent in figure 7 c. Recent experimental investigation...support by the Natural Sciences and Engineering Research...mixtures. In 42nd AIAA Aerospace Science Meeting and Exhibit...

2009-01-01T23:59:59.000Z

274

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

275

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

276

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

277

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

278

Modeling heat conduction and radiation transport with the diffusion equation in  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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,

279

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

280

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

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281

Mesoscopic modeling of multi-physicochemical transport phenomena in porous media  

SciTech Connect (OSTI)

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

282

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

283

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

SciTech Connect (OSTI)

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

284

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

SciTech Connect (OSTI)

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

285

Thermochemical process for seasonal storage of solar energy: characterization and modeling of a high-density reactive bed  

E-Print Network [OSTI]

1 Thermochemical process for seasonal storage of solar energy: characterization and modeling to maximize the use of solar energy for house heating, it is interesting to valorize the solar energy excess efficiency, and a 20 per cent share of renewable). The use of renewable energies and in particular solar

Paris-Sud XI, Université de

286

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

SciTech Connect (OSTI)

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

287

Transport in Porous Media 37: 327346, 1999. c 1999 Kluwer Academic Publishers. Printed in the Netherlands.  

E-Print Network [OSTI]

in the Netherlands. 327 A Decomposition Method for Solving Coupled Multi-Species Reactive Transport Problems YUNWEI

Clement, Prabhakar

288

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

289

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

SciTech Connect (OSTI)

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

290

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

291

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

SciTech Connect (OSTI)

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

292

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

SciTech Connect (OSTI)

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

293

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

SciTech Connect (OSTI)

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

294

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

SciTech Connect (OSTI)

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

295

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

296

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

297

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

298

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

299

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

300

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

Note: This page contains sample records for the topic "reactive transport models" 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.


301

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

SciTech Connect (OSTI)

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

302

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

SciTech Connect (OSTI)

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

303

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

SciTech Connect (OSTI)

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

304

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

SciTech Connect (OSTI)

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

305

Reactive Power Compensator.  

DOE Patents [OSTI]

A system and method for determining and providing reactive power compensation for an inductive load. A reactive power compensator (50,50') monitors the voltage and current flowing through each of three distribution lines (52a, 52b, 52c), which are supplying three-phase power to one or more inductive loads. Using signals indicative of the current on each of these lines when the voltage waveform on the line crosses zero, the reactive power compensator determines a reactive power compensator capacitance that must be connected to the lines to maintain a desired VAR level, power factor, or line voltage. Alternatively, an operator can manually select a specific capacitance for connection to each line, or the capacitance can be selected based on a time schedule. The reactive power compensator produces control signals, which are coupled through optical fibers (102/106) to a switch driver (110, 110') to select specific compensation capacitors (112) for connections to each line. The switch driver develops triggering signals that are supplied to a plurality of series-connected solid state switches (350), which control charge current in one direction in respect to ground for each compensation capacitor. During each cycle, current flows from ground to charge the capacitors as the voltage on the line begins to go negative from its positive peak value. The triggering signals are applied to gate the solid state switches into a conducting state when the potential on the lines and on the capacitors reaches a negative peak value, thereby minimizing both the potential difference and across the charge current through the switches when they begin to conduct. Any harmonic distortion on the potential and current carried by the lines is filtered out from the current and potential signals used by the reactive power compensator so that it does not affect the determination of the required reactive compensation. 26 figs.

El-Sharkawi, M.A.; Venkata, S.S.; Chen, M.; Andexler, G.; Huang, T.

1992-07-28T23:59:59.000Z

306

Reactive power compensator  

DOE Patents [OSTI]

A system and method for determining and providing reactive power compensation for an inductive load. A reactive power compensator (50,50') monitors the voltage and current flowing through each of three distribution lines (52a, 52b, 52c), which are supplying three-phase power to one or more inductive loads. Using signals indicative of the current on each of these lines when the voltage waveform on the line crosses zero, the reactive power compensator determines a reactive power compensator capacitance that must be connected to the lines to maintain a desired VAR level, power factor, or line voltage. Alternatively, an operator can manually select a specific capacitance for connection to each line, or the capacitance can be selected based on a time schedule. The reactive power compensator produces control signals, which are coupled through optical fibers (102/106) to a switch driver (110, 110') to select specific compensation capacitors (112) for connections to each line. The switch driver develops triggering signals that are supplied to a plurality of series-connected solid state switches (350), which control charge current in one direction in respect to ground for each compensation capacitor. During each cycle, current flows from ground to charge the capacitors as the voltage on the line begins to go negative from its positive peak value. The triggering signals are applied to gate the solid state switches into a conducting state when the potential on the lines and on the capacitors reaches a negative peak value, thereby minimizing both the potential difference and across the charge current through the switches when they begin to conduct. Any harmonic distortion on the potential and current carried by the lines is filtered out from the current and potential signals used by the reactive power compensator so that it does not affect the determination of the required reactive compensation.

El-Sharkawi, Mohamed A. (Renton, WA); Venkata, Subrahmanyam S. (Woodinville, WA); Chen, Mingliang (Kirkland, WA); Andexler, George (Everett, WA); Huang, Tony (Seattle, WA)

1992-01-01T23:59:59.000Z

307

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 (OSTI)

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

308

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

SciTech Connect (OSTI)

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

309

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

SciTech Connect (OSTI)

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

310

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.

311

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

312

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

313

Oxyferryl Heme Reactivity  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Oxyferryl Heme Reactivity Using both Radiation and Photochemical Oxyferryl Heme Reactivity Using both Radiation and Photochemical Techniques A. M. English, T. Fox, G. Tsaprailis, C. W. Fenwick, J. F. Wishart, J. T. Hazzard, and G. Tollin Adv. Chem. Ser. 254, Ch. 6, pp. 81-98 Abstract: Flash photolysis and pulse radiolysis were used to generate reductants in situ to study the electron-transfer (ET) reactivity of the FeIV=O heme centers in myoglobin and cytochrome c peroxidase. Reduction of a5RuIII groups covalently bound to surface histidines allowed intramolecular RuII --> FeIV=O ET rates to be measured. Protonation of the oxene ligand was found to be largely rate determining in myoglobin, consistent with the lack of proton donors in its heme pocket. The large distance (21-23 Å) between surface histidines and the heme in wild-type

314

Reactivity of Acid Generators  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Reactivity of Acid Generators for Chemically Amplified Resists with Reactivity of Acid Generators for Chemically Amplified Resists with Low-Energy Electrons Atsuro Nakano, Takahiro Kozawa, Seiichi Tagawa, Tomasz Szreder, James F. Wishart, Toshiyuki Kai and Tsutomu Shimokawa Jpn. J. Appl. Phys., 45, L197-L200 (2006). [Find paper at the Japanese Journal of Applied Physics] Abstract: In chemically amplified resists for ionizing radiations such as electron beams and extreme ultraviolet (EUV), low-energy electrons play an important role in the pattern formation processes. The reactivity of acid generators with low-energy electrons was evaluated using solvated electrons in tetrahydrofuran, which were generated by a pulsed electron beam. The rate constants of acid generators with the solvated electrons ranged from 0.6 to 1.9 x 1011 M-1s-1

315

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

316

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

317

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

318

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

319

Reactive Power Compensating System.  

DOE Patents [OSTI]

The circuit was designed for the specific application of wind-driven induction generators. It has great potential for application in any situation where a varying reactive power load is present, such as with induction motors or generators, or for transmission network compensation.

Williams, Timothy J.; El-Sharkawi, Mohamed A.; Venkata, Subrahmanyam S.

1985-01-04T23:59:59.000Z

320

Reactive power compensating system  

DOE Patents [OSTI]

The reactive power of an induction machine is compensated by providing fixed capacitors on each phase line for the minimum compensation required, sensing the current on one line at the time its voltage crosses zero to determine the actual compensation required for each phase, and selecting switched capacitors on each line to provide the balance of the compensation required.

Williams, Timothy J. (Redondo Beach, CA); El-Sharkawi, Mohamed A. (Renton, WA); Venkata, Subrahmanyam S. (Seattle, WA)

1987-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "reactive transport models" 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.


321

Chemically Reactive Working Fluids  

Broader source: Energy.gov (indexed) [DOE]

Capture and Transport of Concentrated Solar Thermal Energy for Power Generation Argonne National Laboratory Award Number: CPS25657 | April 15, 2013 | Brotzman * Thermodynamic and...

322

Waste area Grouping 2 Phase I remedial investigation: Sediment and Cesium-137 transport modeling report  

SciTech Connect (OSTI)

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

323

Numerical modeling of deep groundwater flow and heat transport in the Williston Basin  

SciTech Connect (OSTI)

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

324

Preliminary model for heat transport within a tongue-and-reservoir liquid diode for passive solar heating  

SciTech Connect (OSTI)

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

325

A Learning-Based Approach to Reactive Security  

E-Print Network [OSTI]

Terms--Reactive security, risk management, attack graphs, online learning, adversarial learning, game vulnerability is plugged, CISOs typically perform a cost- benefit analysis to identify which risks to address of reactive strategies in an economic model of the CISO's security cost-benefit trade- offs. Unlike previously

Song, Dawn

326

Vadose Zone Transport Field Study: Summary Report  

SciTech Connect (OSTI)

From FY 2000 through FY 2003, a series of vadose zone transport field experiments were conducted as part of the U.S. Department of Energys Groundwater/Vadose Zone Integration Project Science and Technology Project, now known as the Remediation and Closure Science Project, and managed by the Pacific Northwest National Laboratory (PNNL). The series of experiments included two major field campaigns, one at a 299-E24-11 injection test site near PUREX and a second at a clastic dike site off Army Loop Road. The goals of these experiments were to improve our understanding of vadose zone transport processes; to develop data sets to validate and calibrate vadose zone flow and transport models; and to identify advanced monitoring techniques useful for evaluating flow-and-transport mechanisms and delineating contaminant plumes in the vadose zone at the Hanford Site. This report summarizes the key findings from the field studies and demonstrates how data collected from these studies are being used to improve conceptual models and develop numerical models of flow and transport in Hanfords vadose zone. Results of these tests have led to a better understanding of the vadose zone. Fine-scale geologic heterogeneities, including grain fabric and lamination, were observed to have a strong effect on the large-scale behavior of contaminant plumes, primarily through increased lateral spreading resulting from anisotropy. Conceptual models have been updated to include lateral spreading and numerical models of unsaturated flow and transport have revised accordingly. A new robust model based on the concept of a connectivity tensor was developed to describe saturation-dependent anisotropy in strongly heterogeneous soils and has been incorporated into PNNLs Subsurface Transport Over Multiple Phases (STOMP) simulator. Application to field-scale transport problems have led to a better understanding plume behavior at a number of sites where lateral spreading may have dominated waste migration (e.g. BC Cribs and Trenches). The improved models have been also coupled with inverse models and newly-developed parameter scaling techniques to allow estimation of field-scale and effective transport parameters for the vadose zone. The development and utility of pedotransfer functions for describing fine-scale hydrogeochemical heterogeneity and for incorporating this heterogeneity into reactive transport models was explored. An approach based on grain-size statistics appears feasible and has been used to describe heterogeneity in hydraulic properties and sorption properties, such as the cation exchange capacity and the specific surface area of Hanford sediments. This work has also led to the development of inverse modeling capabilities for time-dependent, subsurface, reactive transport with transient flow fields using an automated optimization algorithm. In addition, a number of geophysical techniques investigated for their potential to provide detailed information on the subtle changes in lithology and bedding surfaces; plume delineation, leak detection. High-resolution resistivity is now being used for detecting saline plumes at several waste sites at Hanford, including tank farms. Results from the field studies and associated analysis have appeared in more than 46 publications generated over the past 4 years. These publications include test plans and status reports, in addition to numerous technical notes and peer reviewed papers.

Ward, Andy L.; Conrad, Mark E.; Daily, William D.; Fink, James B.; Freedman, Vicky L.; Gee, Glendon W.; Hoversten, Gary M.; Keller, Jason M.; Majer, Ernest L.; Murray, Christopher J.; White, Mark D.; Yabusaki, Steven B.; Zhang, Z. F.

2006-07-31T23:59:59.000Z

327

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 (OSTI)

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

328

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

329

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.

330

Transportation Secure Data Center: Real-World Data for Planning, Modeling and Analysis (Fact Sheet)  

SciTech Connect (OSTI)

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

331

Transportation Secure Data Center: Real-World Data for Planning, Modeling, and Analysis (Fact Sheet)  

SciTech Connect (OSTI)

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

332

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

333

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

334

Reactive Air Aluminization  

SciTech Connect (OSTI)

Ferritic stainless steels and other alloys are of great interest to SOFC developers for applications such as interconnects, cell frames, and balance of plant components. While these alloys offer significant advantages (e.g., low material and manufacturing cost, high thermal conductivity, and high temperature oxidation resistance), there are challenges which can hinder their utilization in SOFC systems; these challenges include Cr volatility and reactivity with glass seals. To overcome these challenges, protective coatings and surface treatments for the alloys are under development. In particular, aluminization of alloy surfaces offers the potential for mitigating both evaporation of Cr from the alloy surface and reaction of alloy constituents with glass seals. Commercial aluminization processes are available to SOFC developers, but they tend to be costly due to their use of exotic raw materials and/or processing conditions. As an alternative, PNNL has developed Reactive Air Aluminization (RAA), which offers a low-cost, simpler alternative to conventional aluminization methods.

Choi, Jung-Pyung; Chou, Y. S.; Stevenson, Jeffry W.

2011-10-28T23:59:59.000Z

335

Using laboratory flow experiments and reactive chemical transport modeling for designing waterflooding of the Agua Fria Reservoir, Poza Rica-Altamira Field, Mexico  

E-Print Network [OSTI]

1. Williams, P. : Mexico, Oil and Gas Investor (July 2003)oil field, bordering the Gulf coast in the eastern part of Mexico,

Birkle, P.

2009-01-01T23:59:59.000Z

336

Modeling of coupled heat transfer and reactive transport processes in porous media: Application to seepage studies at Yucca Mountain, Nevad a  

E-Print Network [OSTI]

of gypsum (or anhydrite), halite, fluorite and other salts.such as anhydrite, gypsum, or halite) also precipitate as a

Mukhopadhyay, Sumit; Sonnenthal, Eric L.; Spycher, Nicolas

2008-01-01T23:59:59.000Z

337

Using laboratory flow experiments and reactive chemical transport modeling for designing waterflooding of the Agua Fria Reservoir, Poza Rica-Altamira Field, Mexico  

E-Print Network [OSTI]

11 to 48 m 3 /d]. Recently, PEMEX initiated an aggressiveand Petrleos Mexicanos (PEMEX, Subdireccin Region Norte),oilfield. Thanks to the PEMEX administration for the

Birkle, P.

2009-01-01T23:59:59.000Z

338

Phase II Transport Model of Corrective Action Unit 98: Frenchman Flat, Nevada Test Site, Nye County, Nevada, Revision 1  

SciTech Connect (OSTI)

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

339

X-ray microtomography characterization of porosity, permeability and reactive surface changes during dissolution  

E-Print Network [OSTI]

X-ray microtomography characterization of porosity, permeability and reactive surface changes from X-ray microtomography data obtained before and after a set of dissolution experiments of pure.V. All rights reserved. Keywords: Reactive transport Carbon storage Permeability X-ray microtomography 1

Luquot, Linda

340

Reactive Maintenance | Department of Energy  

Broader source: Energy.gov (indexed) [DOE]

Reactive Maintenance Reactive Maintenance Reactive Maintenance October 7, 2013 - 9:40am Addthis Reactive maintenance follows a run-it-until-it-breaks strategy where no actions or efforts are taken to maintain equipment as intended by the manufacturer. Studies indicate this is still the predominant mode of maintenance for Federal facilities. Advantages Reactive maintenance advantages are a double-edged sword. Federal agencies following a purely reactive maintenance strategy can expect little expenditures for manpower or system upkeep until something breaks. However, systems do break. With new equipment, Federal agencies can expect minimal incidents of failure. However, older equipment often experiences higher failure incidents and costlier repairs. Other advantages of reactive maintenance are:

Note: This page contains sample records for the topic "reactive transport models" 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

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

342

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

343

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

SciTech Connect (OSTI)

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

344

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

SciTech Connect (OSTI)

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

345

Grand challenge problems in environmental modeling and remediation: Groundwater contaminant transport. Final project report 1998  

SciTech Connect (OSTI)

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

346

Validation, Proof-of-Concept, and Postaudit of the Groundwater Flow and Transport Model of the Project Shoal Area  

SciTech Connect (OSTI)

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

347

Modeling most likely pathways for smuggling radioactive and special nuclear materials on a worldwide multi-modal transportation network  

SciTech Connect (OSTI)

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

348

Modeling most likely pathways for smuggling radioactive and special nuclear materials on a worldwide multimodal transportation network  

SciTech Connect (OSTI)

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

349

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

350

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  

Broader source: Energy.gov [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.

351

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 (OSTI)

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

352

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

353

Modeling the Hydrogeochemical Transport of Radionuclides through Engineered Barriers System in the Proposed LLW Disposal Site of Taiwan - 12082  

SciTech Connect (OSTI)

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

354

Modeling Groundwater Flow and Transport of Radionuclides at Amchitka Island's Underground Nuclear Tests: Milrow, Long Shot, and Cannikin  

SciTech Connect (OSTI)

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

355

Use of a comprehensive calibration ``gauntlet`` approach for improved contaminants transport modeling at the F and H Area Seepage Basins  

SciTech Connect (OSTI)

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

356

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

357

Modeling heat and mass transport phenomena at higher temperatures in solar distillation systems - The Chilton-Colburn analogy  

SciTech Connect (OSTI)

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

358

A model to assess the relative impact of policy in transportation energy expenditures  

SciTech Connect (OSTI)

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

359

Mathematical modeling of liquid/liquid hollow fiber membrane contactor accounting for interfacial transport phenomena: Extraction of lanthanides as a surrogate for actinides  

SciTech Connect (OSTI)

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

360

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

Note: This page contains sample records for the topic "reactive transport models" 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.
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361

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

362

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

363

Federal Energy Management Program: Reactive Maintenance  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Reactive Reactive Maintenance to someone by E-mail Share Federal Energy Management Program: Reactive Maintenance on Facebook Tweet about Federal Energy Management Program: Reactive Maintenance on Twitter Bookmark Federal Energy Management Program: Reactive Maintenance on Google Bookmark Federal Energy Management Program: Reactive Maintenance on Delicious Rank Federal Energy Management Program: Reactive Maintenance on Digg Find More places to share Federal Energy Management Program: Reactive Maintenance on AddThis.com... Sustainable Buildings & Campuses Operations & Maintenance Federal Requirements Program Management Commissioning Metering Computerized Maintenance Management Systems Maintenance Types Reactive Preventive Predictive Reliability-Centered Major Equipment Types

364

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

365

Fast-ignition transport studies: Realistic electron source, integrated particle-in-cell and hydrodynamic modeling, imposed magnetic fields  

SciTech Connect (OSTI)

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

366

A groundwater flow and transport model of long-term radionuclide migration in central Frenchman flat, Nevada test site  

SciTech Connect (OSTI)

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

367

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

368

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

369

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

370

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

371

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 (OSTI)

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

372

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

373

Lattice Boltzmann simulation of solute transport in heterogeneous porous media with conduits to estimate macroscopic continuous time random walk model parameters  

SciTech Connect (OSTI)

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

374

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 (OSTI)

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

375

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

376

Metal-based reactive nanomaterials  

Science Journals Connector (OSTI)

Recent developments in materials processing and characterization resulted in the discovery of a new type of reactive materials containing nanoscaled metal components. The well-known high oxidation energies of metallic fuels can now be released very rapidly because of the very high reactive interface areas in such metal-based reactive nanomaterials. Consequently, these materials are currently being examined for an entire range of applications in energetic formulations inappropriate for conventional, micron-sized metal fuels having relatively low reaction rates. New application areas, such as reactive structural materials, are also being explored. Research remains active in manufacturing and characterization of metal-based reactive nanomaterials including elemental metal nanopowders and various nanocomposite material systems. Because of the nanometer scale of the individual particles, or phase domains, and because of the very high enthalpy of reaction between components of the nanocomposite materials, the final phase compositions, morphology, and thermodynamic properties of the reactive nanocomposite materials may be different from those of their micron-scaled counterparts. Ignition mechanisms in such materials can be governed by heterogeneous reactions that are insignificant for materials with less developed reactive interface areas. New combustion regimes are being observed that are affected by very short ignition delays combined with very high metal combustion temperatures. Current progress in this rapidly growing research area is reviewed and some potential directions for the future research are discussed.

Edward L. Dreizin

2009-01-01T23:59:59.000Z

377

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

378

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

Broader source: Energy.gov (indexed) [DOE]

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...

379

Model Development and Analysis of the Fate and Transport of Water...  

Broader source: Energy.gov (indexed) [DOE]

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...

380

NA22 Model Cities Project - LL244T An Intelligent Transportation System-Based Radiation Alert and Detection System  

SciTech Connect (OSTI)

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

Note: This page contains sample records for the topic "reactive transport models" 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.


381

Electrocatalytic Reactivity for Oxygen Reduction of Palladium...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Reactivity for Oxygen Reduction of Palladium-Modified Carbon Nanotubes Synthesized in Supercritical Fluid. Electrocatalytic Reactivity for Oxygen Reduction of Palladium-Modified...

382

Formation, characterization and reactivity of adsorbed oxygen...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Formation, characterization and reactivity of adsorbed oxygen on BaOPt(111). Formation, characterization and reactivity of adsorbed oxygen on BaOPt(111). Abstract: The formation...

383

Feed gas contaminant removal in ion transport membrane systems  

SciTech Connect (OSTI)

An oxygen ion transport membrane process wherein a heated oxygen-containing gas having one or more contaminants is contacted with a reactive solid material to remove the one or more contaminants. The reactive solid material is provided as a deposit on a support. The one or more contaminant compounds in the heated oxygen-containing gas react with the reactive solid material. The contaminant-depleted oxygen-containing gas is contacted with a membrane, and oxygen is transported through the membrane to provide transported oxygen.

Underwood, Richard Paul (Allentown, PA); Makitka, III, Alexander (Hatfield, PA); Carolan, Michael Francis (Allentown, PA)

2012-04-03T23:59:59.000Z

384

Combined Estimation of Hydrogeologic Conceptual Model, Parameter, and Scenario Uncertainty with Application to Uranium Transport at the Hanford Site 300 Area  

SciTech Connect (OSTI)

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 associated prior scenario probabilities. A joint assessment of uncertainty results from combining model predictions computed under each scenario using as weight the posterior model and prior scenario probabilities. The uncertainty methodology was applied to modeling of groundwater flow and uranium transport at the Hanford Site 300 Area. Eight alternative models representing uncertainty in the hydrogeologic and geochemical properties as well as the temporal variability were considered. Two scenarios represent alternative future behavior of the Columbia River adjacent to the site were considered. The scenario alternatives were implemented in the models through the boundary conditions. Results demonstrate the feasibility of applying a comprehensive uncertainty assessment to large-scale, detailed groundwater flow and transport modeling and illustrate the benefits of the methodology I providing better estimates of predictive uncertiay8, quantitative results for use in assessing risk, and an improved understanding of the system behavior and the limitations of the models.

Meyer, Philip D.; Ye, Ming; Rockhold, Mark L.; Neuman, Shlomo P.; Cantrell, Kirk J.

2007-07-30T23:59:59.000Z

385

Feasibility of uid transport modelling for bu er and processing systems : Information Fluid Dynamics  

E-Print Network [OSTI]

that achieve robustness, accuracy and rapid simulations. Here we present a uid model for a general family modelling . . . . . . . . . . . . . . . . . . . . 12 3.2 Multi-species case for FIFO . . . . . . . . . . . . . . . . . . . . . . . . . 21 5 Numerical discretization for the FIFO equation 22 5.1 Building an explicit scheme

386

Conservation of reactive electromagnetic energy in reactive time  

E-Print Network [OSTI]

The complex Poynting theorem (CPT) is extended to a canonical time-scale domain $(t,s)$. Time-harmonic phasors are replaced by the positive-frequency parts of general fields, which extend analytically to complex time $t+is$, with $s>0$ interpreted as a time resolution scale. The real part of the extended CPT gives conservation in $t$ of a time-averaged field energy, and its imaginary part gives conservation in $s$ of a time-averaged reactive energy. In both cases, the averaging windows are determined by a Cauchy kernel of width $\\Delta t\\sim \\pm s$. This completes the time-harmonic CPT, whose imaginary part is generally supposed to be vaguely `related to' reactive energy without giving a conservation law, or even an expression, for the latter. The interpretation of $s$ as reactive time, tracking the leads and lags associated with stored capacitative and inductive energy, gives a simple explanation of the volt-ampere reactive (var) unit measuring reactive power: a var is simply one Joule per reactive second. T...

Kaiser, Gerald

2015-01-01T23:59:59.000Z

387

Recent Advances in Detailed Chemical Kinetic Models for Large Hydrocarbon and Biodiesel Transportation Fuels  

SciTech Connect (OSTI)

n-Hexadecane and 2,2,4,4,6,8,8-heptamethylnonane represent the primary reference fuels for diesel that are used to determine cetane number, a measure of the ignition property of diesel fuel. With the development of chemical kinetics models for these two primary reference fuels for diesel, a new capability is now available to model diesel fuel ignition. Also, we have developed chemical kinetic models for a whole series of large n-alkanes and a large iso-alkane to represent these chemical classes in fuel surrogates for conventional and future fuels. Methyl decanoate and methyl stearate are large methyl esters that are closely related to biodiesel fuels, and kinetic models for these molecules have also been developed. These chemical kinetic models are used to predict the effect of the fuel molecule size and structure on ignition characteristics under conditions found in internal combustion engines.

Westbrook, C K; Pitz, W J; Curran, H J; Herbinet, O; Mehl, M

2009-03-30T23:59:59.000Z

388

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

389

Multiphase Modeling of Flow, Transport, and Biodegradation in a Mesoscale Landfill Bioreactor  

E-Print Network [OSTI]

1179. Popov, V. ; Power, H. Landfill emission of gases intoC.M. T2LBM Version 1.0: Landfill bioreactor model forand recovery from landfills, Ann Arbor Science Publishers,

Oldenburg, Curtis M.; Borglin, Sharon E.; Hazen, Terry C.

2002-01-01T23:59:59.000Z

390

Fuel Temperature Coefficient of Reactivity  

SciTech Connect (OSTI)

A method for measuring the fuel temperature coefficient of reactivity in a heterogeneous nuclear reactor is presented. The method, which is used during normal operation, requires that calibrated control rods be oscillated in a special way at a high reactor power level. The value of the fuel temperature coefficient of reactivity is found from the measured flux responses to these oscillations. Application of the method in a Savannah River reactor charged with natural uranium is discussed.

Loewe, W.E.

2001-07-31T23:59:59.000Z

391

Evaluation of the Atmospheric Transport Model in the MACCS2 Code and its Impact on Decision Making at DOE Sites  

Broader source: Energy.gov (indexed) [DOE]

the Atmospheric the Atmospheric Transport Model in the MACCS2 Code and its Impact on Decision Making at Department of Energy Sites John E. Till and Arthur S. Rood June 5, 2012 RAC Historical Dose Reconstruction Projects Environmental Risk Assessment "Understanding and communicating the movement of radionuclides and chemicals released to the environment, resulting exposure to humans, and the subsequent dose or risk from exposure." Types of Dose/Risk  Medical  Occupational  Public Dose/Risk Can Be Estimated for  Real people  Hypothetical people Purpose of Assessments  Compliance  Decision making  Epidemiology  Emergency response Approaches to Estimating Risk  In certain situations, and depending upon the decisions to be made, if the results of relatively

392

Powder transport model for laser cladding by lateral powder feeding: I. Powder flow field with cylindrical distribution  

Science Journals Connector (OSTI)

Powder transport ratio is defined as the mass ratio of powder particles fed into the molten pool to all powders transported in the process of laser cladding by lateral powder feeding. According to the...

Xinyong Gong; Yongzhong Zhang; Mingkun Liu

2013-08-01T23:59:59.000Z

393

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

SciTech Connect (OSTI)

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

394

Single crystal flow reactor for studying reactivities on metal oxide model catalysts at atmospheric pressure to bridge the pressure gap to the adsorption properties determined under UHV conditions  

Science Journals Connector (OSTI)

A flow reactor for the investigation of heterogeneous catalytic reactions on single crystalline metal oxide model catalysts has been designed. It is located in a high pressure cell attached to an UHV analysis cha...

C. Kuhrs; M. Swoboda; W. Weiss

2001-01-01T23:59:59.000Z

395

Computational Nanophotonics: modeling optical interactions and transport in tailored nanosystem architectures  

SciTech Connect (OSTI)

This report describes research by George Schatz and Mark Ratner that was done over the period 10/03-5/09 at Northwestern University. This research project was part of a larger research project with the same title led by Stephen Gray at Argonne. A significant amount of our work involved collaborations with Gray, and there were many joint publications as summarized later. In addition, a lot of this work involved collaborations with experimental groups at Northwestern, Argonne, and elsewhere. The research was primarily concerned with developing theory and computational methods that can be used to describe the interaction of light with noble metal nanoparticles (especially silver) that are capable of plasmon excitation. Classical electrodynamics provides a powerful approach for performing these studies, so much of this research project involved the development of methods for solving Maxwells equations, including both linear and nonlinear effects, and examining a wide range of nanostructures, including particles, particle arrays, metal films, films with holes, and combinations of metal nanostructures with polymers and other dielectrics. In addition, our work broke new ground in the development of quantum mechanical methods to describe plasmonic effects based on the use of time dependent density functional theory, and we developed new theory concerned with the coupling of plasmons to electrical transport in molecular wire structures. Applications of our technology were aimed at the development of plasmonic devices as components of optoelectronic circuits, plasmons for spectroscopy applications, and plasmons for energy-related applications.

Schatz, George; Ratner, Mark

2014-02-27T23:59:59.000Z

396

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

SciTech Connect (OSTI)

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

397

Sanitary landfill local-scale flow and transport modeling in support of alternative concentrations limit demonstrations, Savannah River Site  

SciTech Connect (OSTI)

The Savannah River Site (SRS) is a Department of Energy (DOE) facility located near Aiken, South Carolina which is currently operated and managed by Westinghouse Savannah River Company (WSRC). The Sanitary Landfill (Sanitary Landfill) at the SRS is located approximately 2,000 feet Northwest of Upper Three Runs Creek (UTRC) on an approximately 70 acre site located south of Road C between the SRS B-Area and UTRC. The Sanitary Landfill has been receiving wastes since 1974 and operates as an unlined trench and fill operation. The original landfill site was 32 acres. This area reached its capacity around 1987 and a Northern Expansion of 16 acres and a Southern Expansion of 22 acres were added in 1987. The Northern Expansion has not been used for waste disposal to date and the Southern Expansion is expected to reach capacity in 1992 or 1993. The waste received at the Sanitary Landfill is predominantly paper, plastics, rubber, wood, metal, cardboard, rags saturated with degreasing solvents, pesticide bags, empty cans, and asbestos in bags. The landfill is not supposed to receive any radioactive wastes. However, tritium has been detected in the groundwater at the site. Gross alpha and gross beta are also evaluated at the landfill. The objectives of this modeling study are twofold: (1) to create a local scale Sanitary Landfill flow model to study hydraulic effects resulting from capping the Sanitary Landfill; and (2) to create a Sanitary Landfill local scale transport model to support ACL Demonstrations for a RCRA Part B Permit Renewal.

Kelly, V.A.; Beach, J.A.; Statham, W.H.; Pickens, J.F. [INTERA, Inc., Austin, TX (United States)

1993-02-19T23:59:59.000Z

398

COAL SLAGGING AND REACTIVITY TESTING  

SciTech Connect (OSTI)

Union Fenosa's La Robla I Power Station is a 270-MW Foster Wheeler arch-fired system. The unit is located at the mine that provides a portion of the semianthracitic coal. The remaining coals used are from South Africa, Russia, Australia, and China. The challenges at the La Robla I Station stem from the various fuels used, the characteristics of which differ from the design coal. The University of North Dakota Energy & Environmental Research Center (EERC) and the Lehigh University Energy Research Center (LUERC) undertook a program to assess problematic slagging and unburned carbon issues occurring at the plant. Full-scale combustion tests were performed under baseline conditions, with elevated oxygen level and with redistribution of air during a site visit at the plant. During these tests, operating information, observations and temperature measurements, and coal, slag deposit, and fly ash samples were obtained to assess slagging and unburned carbon. The slagging in almost all cases appeared due to elevated temperatures rather than fuel chemistry. The most severe slagging occurred when the temperature at the sampling port was in excess of 1500 C, with problematic slagging where first-observed temperatures exceeded 1350 C. The presence of anorthite crystals in the bulk of the deposits analyzed indicates that the temperatures were in excess of 1350 C, consistent with temperature measurements during the sampling period. Elevated temperatures and ''hot spots'' are probably the result of poor mill performance, and a poor distribution of the coal from the mills to the specific burners causes elevated temperatures in the regions where the slag samples were extracted. A contributing cause appeared to be poor combustion air mixing and heating, resulting in oxygen stratification and increased temperatures in certain areas. Air preheater plugging was observed and reduces the temperature of the air in the windbox, which leads to poor combustion conditions, resulting in unburned carbon as well as slagging. A second phase of the project involved advanced analysis of the baseline coal along with an Australian coal fired at the plant. These analysis results were used in equilibrium thermodynamic modeling along with a coal quality model developed by the EERC to assess slagging, fouling, and opacity for the coals. Bench-scale carbon conversion testing was performed in a drop-tube furnace to assess the reactivity of the coals. The Australian coal had a higher mineral content with significantly more clay minerals present than the baseline coal. The presence of these clay minerals, which tend to melt at relatively low temperatures, indicated a higher potential for problematic slagging than the baseline coal. However, the pyritic minerals, comprising over 25% of the baseline mineral content, may form sticky iron sulfides, leading to severe slagging in the burner region if local areas with reducing conditions exist. Modeling results indicated that neither would present significant fouling problems. The Australian coal was expected to show slagging behavior much more severe than the baseline coal except at very high furnace temperatures. However, the baseline coal was predicted to exhibit opacity problems, as well as have a higher potential for problematic calcium sulfate-based low-temperature fouling. The baseline coal had a somewhat higher reactivity than the Australian coal, which was consistent with both the lower average activation energy for the baseline coal and the greater carbon conversion at a given temperature and residence time. The activation energy of the baseline coal showed some effect of oxygen on the activation energy, with E{sub a} increasing at the lower oxygen concentration, but may be due to the scatter in the baseline coal kinetic values at the higher oxygen level tested.

Donald P. McCollor; Kurt E. Eylands; Jason D. Laumb

2003-10-01T23:59:59.000Z

399

An improved numerical scheme for a coupled system to model soil erosion and polydispersed sediments transport  

E-Print Network [OSTI]

An improved numerical scheme for a coupled system to model soil erosion and polydispersed sediments, the positivity of both water depth and sediment concentrations. Recently, a well-balanced MUSCL-Hancock scheme step is required to ensure the positivity of sediment concentrations. The main result of this paper

Boyer, Edmond

400

Geophysical constraints on contaminant transport modeling in a heterogeneous fluvial aquifer  

E-Print Network [OSTI]

of Geological Sciences, University of Alabama, Box 870338, Tuscaloosa, AL 35487, USA b Institute of Marine log­log relationship. Application of this relationship, using site-specific empirical constants supplemented with geophysical data at least as well as previous models of the site using purely hydrologic data

Zheng, Chunmiao

Note: This page contains sample records for the topic "reactive transport models" 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

Using TDR and Inverse Modeling to Characterize Solute Transport in a Layered Agricultural Volcanic Soil  

Science Journals Connector (OSTI)

...ranges from 7 to 9 depending on the composition and degree of crystallinity (van Olphen...Assessing temporal variations in soil water composition with time domain reflectometry. Soil...mathematical model for simulating water and agrochemicals in the soil and vadose environment...

A. Ritter; R. Muoz-Carpena; C. M. Regalado; M. Javaux; M. Vanclooster

402

Transport parameter determination and modeling of sodium and strontium plumes at the Idaho National Engineering Laboratory  

E-Print Network [OSTI]

. , 1974] . . 7. Generalized plume with centerline 8. Strontium-90 distribution, 1970 [after Robertson et aL, 1974]. . . . 20 . 22 9. The sodium plume transverse dispersivity-Rnite source size in y iteration diagram. 10. The calculat. ed sodium plume.... There is flow there which picks up the contaminant ions dispersing them through the complex network of fractures and interconnected pore space of the saturated porous medium, the aquifer. Being able to model this spread of contaminant in the subsurface...

Londergan, John Thomas

2012-06-07T23:59:59.000Z

403

Transportation Networks and Location A Geometric Approach  

E-Print Network [OSTI]

Transportation Networks and Location A Geometric Approach Belén Palop1,2 1Departamento de March 2009 Florida State University #12;Belén Palop, UVa, SUNY Outline Transportation Network Model;Transportation Network Model Belén Palop, UVa, SUNY Outline Transportation Network Model Network placement

Palop del Río, Belén

404

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

SciTech Connect (OSTI)

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

405

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

406

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

SciTech Connect (OSTI)

Water management in Proton Exchange Membrane, PEM, Fuel Cells is challenging because of the inherent conflicts between the requirements for efficient low and high power operation. Particularly at low powers, adequate water must be supplied to sufficiently humidify the membrane or protons will not move through it adequately and resistance losses will decrease the cell efficiency. At high power density operation, more water is produced at the cathode than is necessary for membrane hydration. This excess water must be removed effectively or it will accumulate in the Gas Diffusion Layers, GDLs, between the gas channels and catalysts, blocking diffusion paths for reactants to reach the catalysts and potentially flooding the electrode. As power density of the cells is increased, the challenges arising from water management are expected to become more difficult to overcome simply due to the increased rate of liquid water generation relative to fuel cell volume. Thus, effectively addressing water management based issues is a key challenge in successful application of PEMFC systems. In this project, CFDRC and our partners used a combination of experimental characterization, controlled experimental studies of important processes governing how water moves through the fuel cell materials, and detailed models and simulations to improve understanding of water management in operating hydrogen PEM fuel cells. The characterization studies provided key data that is used as inputs to all state-of-the-art models for commercially important GDL materials. Experimental studies and microscopic scale models of how water moves through the GDLs showed that the water follows preferential paths, not branching like a river, as it moves toward the surface of the material. Experimental studies and detailed models of water and airflow in fuel cells channels demonstrated that such models can be used as an effective design tool to reduce operating pressure drop in the channels and the associated costs and weight of blowers and pumps to force air and hydrogen gas through the fuel cell. Promising improvements to materials structure and surface treatments that can potentially aid in managing the distribution and removal of liquid water were developed; and improved steady-state and freeze-thaw performance was demonstrated for a fuel cell stack under the self-humidified operating conditions that are promising for stationary power generation with reduced operating costs.

J. Vernon Cole; Abhra Roy; Ashok Damle; Hari Dahr; Sanjiv Kumar; Kunal Jain; Ned Djilai

2012-10-02T23:59:59.000Z

407

Transportation Services  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Transportation Services Transporting nuclear materials within the United States and throughout the world is a complicated and sometimes highly controversial effort requiring...

408

Local Transportation  

E-Print Network [OSTI]

Local Transportation. Transportation from the Airport to Hotel. There are two types of taxi companies that operate at the airport: special and regular taxis (

409

Ground-water flow and transport modeling of the NRC-licensed waste disposal facility, West Valley, New York  

SciTech Connect (OSTI)

This report describes a simulation study of groundwater flow and radionuclide transport from disposal at the NRC licensed waste disposal facility in West Valley, New York. A transient, precipitation driven, flow model of the near-surface fractured till layer and underlying unweathered till was developed and calibrated against observed inflow data into a recently constructed interceptor trench for the period March--May 1990. The results suggest that lateral flow through the upper, fractured till layer may be more significant than indicated by previous, steady state flow modeling studies. A conclusive assessment of the actual magnitude of lateral flow through the fractured till could however not be made. A primary factor contributing to this uncertainty is the unknown contribution of vertical infiltration through the interceptor trench cap to the total trench inflow. The second part of the investigation involved simulation of the migration of Sr-90, Cs-137 and Pu-239 from the one of the fuel hull disposal pits. A first-order radionuclide leach rate with rate coefficient of 10{sup {minus}6}/day was assumed to describe radionuclide release into the disposal pit. The simulations indicated that for wastes buried below the fractured till zone, no significant migration would occur. However, under the assumed conditions, significant lateral migration could occur for radionuclides present in the upper, fractured till zone. 23 refs., 68 figs., 12 tabs.

Kool, J.B.; Wu, Y.S. (HydroGeoLogic, Inc., Herndon, VA (United States))

1991-10-01T23:59:59.000Z

410

Innovative mathematical modeling in environmental remediation  

Science Journals Connector (OSTI)

There are two different ways to model reactive transport: ad hoc and innovative reaction-based approaches. The former, such as the Kd simplification of adsorption, has been widely employed by practitioners, while the latter has been mainly used in scientific communities for elucidating mechanisms of biogeochemical transport processes. It is believed that innovative mechanistic-based models could serve as protocols for environmental remediation as well. This paper reviews the development of a mechanistically coupled fluid flow, thermal transport, hydrologic transport, and reactive biogeochemical model and example-applications to environmental remediation problems. Theoretical bases are sufficiently described. Four example problems previously carried out are used to demonstrate how numerical experimentation can be used to evaluate the feasibility of different remediation approaches. The first one involved the application of a 56-species uranium tailing problem to the Melton Branch Subwatershed at Oak Ridge National Laboratory (ORNL) using the parallel version of the model. Simulations were made to demonstrate the potential mobilization of uranium and other chelating agents in the proposed waste disposal site. The second problem simulated laboratory-scale system to investigate the role of natural attenuation in potential off-site migration of uranium from uranium mill tailings after restoration. It showed inadequacy of using a single Kd even for a homogeneous medium. The third example simulated laboratory experiments involving extremely high concentrations of uranium, technetium, aluminum, nitrate, and toxic metals (e.g., Ni, Cr, Co). The fourth example modeled microbially-mediated immobilization of uranium in an unconfined aquifer using acetate amendment in a field-scale experiment. The purposes of these modeling studies were to simulate various mechanisms of mobilization and immobilization of radioactive wastes and to illustrate how to apply reactive transport models for environmental remediation.

Gour-Tsyh Yeh; Jin-Ping Gwo; Malcolm D. Siegel; Ming-Hsu Li; Yilin Fang; Fan Zhang; Wensui Luo; Steve B. Yabusaki

2013-01-01T23:59:59.000Z

411

A grid refinement approach to flow and transport modeling of a proposed groundwater corrective action at the Savannah River Plant, Aiken, South Carolina  

SciTech Connect (OSTI)

The regional scale model, calibrated by an automatic least-squares procedure, resulted in a set of hydraulic parameter values consistent with other methods. The automatic procedure facilitated the calibration of the model in which ten hydraulic parameters were treated as unknowns. Ground water flow velocities were used to perform particle-tracking analyses. Local scale transport models were developed for the F and H Area seepage basins. The grid refinement technique in conjunction with the parameter estimation method was very effective in the analysis of regional and local flow and transport phenomena. The estimated hydraulic parameters, determined objectively by the automatic procedure, showed excellent agreement with results from other methods. The local scale transport modeling required significant mesh refinements to meet the objectives of the study. Thus, it was necessary to reduce the area of the model domain to maintain cost and computational efficiency. Regional flow phenomena were preserved in the reduced scale models by extracting hydraulic boundaries and parameters from the regional flow model.

Duffield, G.M.; Buss, D.R.; Stephenson, D.E.; Mercer, J.W.

1987-01-01T23:59:59.000Z

412

Transport anisotropy of the pnictides studied via Monte Carlo simulations of the Spin-Fermion model  

SciTech Connect (OSTI)

An undoped three-orbital spin-fermion model for the Fe-based superconductors is studied via Monte Carlo techniques in two-dimensional clusters. At low temperatures, the magnetic and one-particle spectral properties are in agreement with neutron and photoemission experiments. Our main results are the resistance versus temperature curves that display the same features observed in BaFe{sub 2}As{sub 2} detwinned single crystals (under uniaxial stress), including a low-temperature anisotropy between the two directions followed by a peak at the magnetic ordering temperature, that qualitatively appears related to short-range spin order and concomitant Fermi surface orbital order.

Liang, Shuhua [ORNL; Alvarez, Gonzalo [ORNL; Sen, Cengiz [ORNL; Moreo, Adriana [ORNL; Dagotto, Elbio R [ORNL

2012-01-01T23:59:59.000Z

413

Chamber transport  

SciTech Connect (OSTI)

Heavy ion beam transport through the containment chamber plays a crucial role in all heavy ion fusion (HIF) scenarios. Here, several parameters are used to characterize the operating space for HIF beams; transport modes are assessed in relation to evolving target/accelerator requirements; results of recent relevant experiments and simulations of HIF transport are summarized; and relevant instabilities are reviewed. All transport options still exist, including (1) vacuum ballistic transport, (2) neutralized ballistic transport, and (3) channel-like transport. Presently, the European HIF program favors vacuum ballistic transport, while the US HIF program favors neutralized ballistic transport with channel-like transport as an alternate approach. Further transport research is needed to clearly guide selection of the most attractive, integrated HIF system.

OLSON,CRAIG L.

2000-05-17T23:59:59.000Z

414

Reactive sticking coefficients of silane on silicon  

SciTech Connect (OSTI)

Reactive sticking coefficients (RSCs) were measured for silane and disilane on polycrystalline silicon for a wide range of temperature and flux (pressure) conditions. The data were obtained from deposition rate measurements using molecular beam scattering and a very low pressure cold wall reactor. The RSCs have non-Arrhenius temperature dependences and decreases with increasing flux at low (710/sup 0/) temperatures. A simple model involving dissociative adsorption of silane is consistent with these results. The results are compared with previous studies of the SiH/sub 4//Si(s) reaction.

Buss, R.J.; Ho, P.; Breiland, W.G.; Coltrin, M.E.

1988-09-15T23:59:59.000Z

415

IAEA sodium void reactivity benchmark calculations  

SciTech Connect (OSTI)

In this paper, the IAEA-1 992 ``Benchmark Calculation of Sodium Void Reactivity Effect in Fast Reactor Core`` problem is evaluated. The proposed design is a large axially heterogeneous oxide-fueled fast reactor as described in Section 2; the core utilizes a sodium plenum above the core to enhance leakage effects. The calculation methods used in this benchmark evaluation are described in Section 3. In Section 4, the calculated core performance results for the benchmark reactor model are presented; and in Section 5, the influence of steel and interstitial sodium heterogeneity effects is estimated.

Hill, R.N.; Finck, P.J.

1992-12-01T23:59:59.000Z

416

IAEA sodium void reactivity benchmark calculations  

SciTech Connect (OSTI)

In this paper, the IAEA-1 992 Benchmark Calculation of Sodium Void Reactivity Effect in Fast Reactor Core'' problem is evaluated. The proposed design is a large axially heterogeneous oxide-fueled fast reactor as described in Section 2; the core utilizes a sodium plenum above the core to enhance leakage effects. The calculation methods used in this benchmark evaluation are described in Section 3. In Section 4, the calculated core performance results for the benchmark reactor model are presented; and in Section 5, the influence of steel and interstitial sodium heterogeneity effects is estimated.

Hill, R.N.; Finck, P.J.

1992-01-01T23:59:59.000Z

417

SIMPLIFIED CHARGED PARTICLE BEAM TRANSPORT MODELING USING COMMONLY AVAILABLE COMMERCIAL SOFTWARE  

SciTech Connect (OSTI)

Particle beam modeling in accelerators has been the focus of considerable effort since the 1950s. Many generations of tools have resulted from this process, each leveraging both prior experience and increases in computer power. However, continuing innovation in accelerator technology results in systems that are not well described by existing tools, so the software development process is on-going. We discuss a novel response to this situation, which was encountered when Jefferson Lab began operation of its energy-recovering linacs. These machines were not readily described with legacy soft-ware; therefore a model was built using Microsoft Excel. This interactive simulation can query data from the accelerator, use it to compute machine parameters, analyze difference orbit data, and evaluate beam properties. It can also derive new accelerator tunings and rapidly evaluate the impact of changes in machine configuration. As it is spreadsheet-based, it can be easily user-modified in response to changing requirements. Examples for the JLab IR Upgrade FEL are presented.

D. Douglas; K. Beard; J. Eldred; P. Evtushenko; A. Jenkins; W. Moore; L. Osborne; D. Sexton; C. Tennant

2007-06-18T23:59:59.000Z

418

Analysis of the NAEG model of transuranic radionuclide transport and dose  

SciTech Connect (OSTI)

We analyze the model for estimating the dose from /sup 239/Pu developed for the Nevada Applied Ecology Group (NAEG) by using sensitivity analysis and uncertainty analysis. Sensitivity analysis results suggest that the air pathway is the critical pathway for the organs receiving the highest dose. Soil concentration and the factors controlling air concentration are the most important parameters. The only organ whose dose is sensitive to parameters in the ingestion pathway is the GI tract. The air pathway accounts for 100% of the dose to lung, upper respiratory tract, and thoracic lymph nodes; and 95% of its dose via ingestion. Leafy vegetable ingestion accounts for 70% of the dose from the ingestion pathway regardless of organ, peeled vegetables 20%; accidental soil ingestion 5%; ingestion of beef liver 4%; beef muscle 1%. Only a handful of model parameters control the dose for any one organ. The number of important parameters is usually less than 10. Uncertainty analysis indicates that choosing a uniform distribution for the input parameters produces a lognormal distribution of the dose. The ratio of the square root of the variance to the mean is three times greater for the doses than it is for the individual parameters. As found by the sensitivity analysis, the uncertainty analysis suggests that only a few parameters control the dose for each organ. All organs have similar distributions and variance to mean ratios except for the lymph modes. 16 references, 9 figures, 13 tables.

Kercher, J.R.; Anspaugh, L.R.

1984-11-01T23:59:59.000Z

419

Lipid-Based Nanodiscs as Models for Studying Mesoscale Coalescence A Transport Limited Case  

SciTech Connect (OSTI)

Lipid-based nanodiscs (bicelles) are able to form in mixtures of long- and short-chain lipids. Initially, they are of uniform size but grow upon dilution. Previously, nanodisc growth kinetics have been studied using time-resolved small angle neutron scattering (SANS), a technique which is not well suited for probing their change in size immediately after dilution. To address this, we have used dynamic light scattering (DLS), a technique which permits the collection of useful data in a short span of time after dilution of the system. The DLS data indicate that the negatively charged lipids in nanodiscs play a significant role in disc stability and growth. Specifically, the charged lipids are most likely drawn out from the nanodiscs into solution, thereby reducing interparticle repulsion and enabling the discs to grow. We describe a population balance model, which takes into account Coulombic interactions and adequately predicts the initial growth of nanodiscs with a single parameter i.e., surface potential. The results presented here strongly support the notion that the disc coalescence rate strongly depends on nanoparticle charge density. The present system containing low-polydispersity lipid nanodiscs serves as a good model for understanding how charged discoidal micelles coalesce.

Hu, Andrew [University of Connecticut, Storrs; Fan, Tai-Hsi [University of Connecticut, Storrs; Katsaras, John [ORNL; Xia, Yan [University of Connecticut, Storrs; Li, Ming [University of Connecticut, Storrs; Nieh, Mu-Ping [University of Connecticut, Storrs

2014-01-01T23:59:59.000Z

420

High-energy Particle Transport in Three-dimensional Hydrodynamic Models of Colliding-wind Binaries  

Science Journals Connector (OSTI)

Massive stars in binary systems (such as WR 140, WR 147, or ? Carinae) have long been regarded as potential sources of high-energy ?-rays. The emission is thought to arise in the region where the stellar winds collide and produce relativistic particles that subsequently might be able to emit ?-rays. Detailed numerical hydrodynamic simulations have already offered insight into the complex dynamics of the wind collision region (WCR), while independent analytical studies, albeit with simplified descriptions of the WCR, have shed light on the spectra of charged particles. In this paper, we describe a combination of these two approaches. We present a three-dimensional hydrodynamical model for colliding stellar winds and compute spectral energy distributions of relativistic particles for the resulting structure of the WCR. The hydrodynamic part of our model incorporates the line-driven acceleration of the winds, gravity, orbital motion, and the radiative cooling of the shocked plasma. In our treatment of charged particles, we consider diffusive shock acceleration in the WCR and the subsequent cooling via inverse Compton losses (including Klein-Nishina effects), bremsstrahlung, collisions, and other energy loss mechanisms.

K. Reitberger; R. Kissmann; A. Reimer; O. Reimer; G. Dubus

2014-01-01T23:59:59.000Z

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421

Bayesian data assimilation for stochastic multiscale models of transport in porous media.  

SciTech Connect (OSTI)

We investigate Bayesian techniques that can be used to reconstruct field variables from partial observations. In particular, we target fields that exhibit spatial structures with a large spectrum of lengthscales. Contemporary methods typically describe the field on a grid and estimate structures which can be resolved by it. In contrast, we address the reconstruction of grid-resolved structures as well as estimation of statistical summaries of subgrid structures, which are smaller than the grid resolution. We perform this in two different ways (a) via a physical (phenomenological), parameterized subgrid model that summarizes the impact of the unresolved scales at the coarse level and (b) via multiscale finite elements, where specially designed prolongation and restriction operators establish the interscale link between the same problem defined on a coarse and fine mesh. The estimation problem is posed as a Bayesian inverse problem. Dimensionality reduction is performed by projecting the field to be inferred on a suitable orthogonal basis set, viz. the Karhunen-Loeve expansion of a multiGaussian. We first demonstrate our techniques on the reconstruction of a binary medium consisting of a matrix with embedded inclusions, which are too small to be grid-resolved. The reconstruction is performed using an adaptive Markov chain Monte Carlo method. We find that the posterior distributions of the inferred parameters are approximately Gaussian. We exploit this finding to reconstruct a permeability field with long, but narrow embedded fractures (which are too fine to be grid-resolved) using scalable ensemble Kalman filters; this also allows us to address larger grids. Ensemble Kalman filtering is then used to estimate the values of hydraulic conductivity and specific yield in a model of the High Plains Aquifer in Kansas. Strong conditioning of the spatial structure of the parameters and the non-linear aspects of the water table aquifer create difficulty for the ensemble Kalman filter. We conclude with a demonstration of the use of multiscale stochastic finite elements to reconstruct permeability fields. This method, though computationally intensive, is general and can be used for multiscale inference in cases where a subgrid model cannot be constructed.

Marzouk, Youssef M. (Massachusetts Institute of Technology, Cambridge, MA); van Bloemen Waanders, Bart Gustaaf (Sandia National Laboratories, Albuquerque NM); Parno, Matthew (Massachusetts Institute of Technology, Cambridge, MA); Ray, Jaideep; Lefantzi, Sophia; Salazar, Luke (Sandia National Laboratories, Albuquerque NM); McKenna, Sean Andrew (Sandia National Laboratories, Albuquerque NM); Klise, Katherine A. (Sandia National Laboratories, Albuquerque NM)

2011-10-01T23:59:59.000Z

422

Task II: ECRH and transport modeling in tandem mirrors and divertor physics. Annual progress report on fusion plasma theory, January 1, 1983-December 31, 1983  

SciTech Connect (OSTI)

The research performed under Task II of this contract has focused on (1) the coupling of an ECRH ray tracing and absorption code to a tandem mirror transport code in order to self-consistently model the temporal and spatial evolution of the plasma, and (2) the further development of a semi-analytical kinetic model for plasma flow in divertors and pumped limiters. Work on these topics is briefly summarized in this progress report.

Emmert, G.A.

1983-08-01T23:59:59.000Z

423

Simulation and Comparison of Particle Injection in an Indoor Environment Using the Species Transport and Discrete Phase Models  

SciTech Connect (OSTI)

In simulating fluid/solid-particle multiphase -flows, various methods are available. One approach is the combined Euler-Lagrange method, which simulates the fluid phase flow in the Eulerian framework and the discrete phase (particle) motion in the Lagrangian framework simultaneously. The Lagrangian approach, where particle motion is determined by the current state of the fluid phase flow, is also called the discrete phase model (DPM), in the context of numerical flow simulation. In this method, the influence of the particle motions on the fluid flow can be included (two-way interactions) but are more commonly excluded (one-way interactions, when the discrete phase concentration is dilute. The other approach is to treat the particle number concentration as a continuous species, a necessarily passive quantity determined by the fluid flow, with no influences from the particles on the fluid flow (one-way interactions only), except to the extent the discrete phase continuum alters the overall fluid properties, such as density. In this paper, we compare these two methods with experimental data for an indoor environmental chamber. The effects of injection particle numbers and the related boundary conditions are investigated. In the Euler-Lagrange interaction or DPM model for incompressible flow, the Eulerian continuous phase is governed by the Reynolds-averaged N-S (RANS) equations. The motions of particles are governed by Newtons second law. The effects of particle motions are communicated to the continuous phase through a force term in the RANS equations. The second formulation is a pure Eulerian type, where only the particle-number concentration is addressed, rather than the motion of each individual particle. The fluid flow is governed by the same RANS equations without the particle force term. The particle-number concentration is simulated by a species transport equation. Comparisons among the models and with experimental and literature data are presented. Particularly, results with different numbers of released particles in the DPM will be investigated.

Zheng, Zhongquan C.; Wei, Zhenglun A.; Bennett, James S.; Yang, Xiaofan

2012-12-11T23:59:59.000Z

424

Drift-Scale Radionuclide Transport  

SciTech Connect (OSTI)

The purpose of this model report is to document the drift scale radionuclide transport model, taking into account the effects of emplacement drifts on flow and transport in the vicinity of the drift, which are not captured in the mountain-scale unsaturated zone (UZ) flow and transport models ''UZ Flow Models and Submodels'' (BSC 2004 [DIRS 169861]), ''Radionuclide Transport Models Under Ambient Conditions'' (BSC 2004 [DIRS 164500]), and ''Particle Tracking Model and Abstraction of Transport Process'' (BSC 2004 [DIRS 170041]). The drift scale radionuclide transport model is intended to be used as an alternative model for comparison with the engineered barrier system (EBS) radionuclide transport model ''EBS Radionuclide Transport Abstraction'' (BSC 2004 [DIRS 169868]). For that purpose, two alternative models have been developed for drift-scale radionuclide transport. One of the alternative models is a dual continuum flow and transport model called the drift shadow model. The effects of variations in the flow field and fracture-matrix interaction in the vicinity of a waste emplacement drift are investigated through sensitivity studies using the drift shadow model (Houseworth et al. 2003 [DIRS 164394]). In this model, the flow is significantly perturbed (reduced) beneath the waste emplacement drifts. However, comparisons of transport in this perturbed flow field with transport in an unperturbed flow field show similar results if the transport is initiated in the rock matrix. This has led to a second alternative model, called the fracture-matrix partitioning model, that focuses on the partitioning of radionuclide transport between the fractures and matrix upon exiting the waste emplacement drift. The fracture-matrix partitioning model computes the partitioning, between fractures and matrix, of diffusive radionuclide transport from the invert (for drifts without seepage) into the rock water. The invert is the structure constructed in a drift to provide the floor of the drift. The reason for introducing the fracture-matrix partitioning model is to broaden the conceptual model for flow beneath waste emplacement drifts in a way that does not rely on the specific flow behavior predicted by a dual continuum model and to ensure that radionuclide transport is not underestimated. The fracture-matrix partitioning model provides an alternative method of computing the partitioning of radionuclide releases from drifts without seepage into rock fractures and rock matrix. Drifts without seepage are much more likely to have a significant fraction of radionuclide releases into the rock matrix, and therefore warrant additional attention in terms of the partitioning model used for TSPA.

J. Houseworth

2004-09-22T23:59:59.000Z

425

Joint Energy and Reactive Power Market Considering Coupled Active and Reactive Reserve Market Ensuring System Security  

Science Journals Connector (OSTI)

Reactive power market is usually held as independent from energy and reserved active power markets; however, active and reactive power are ... synchronous generator capacity curve. Therefore, reactive power market

Hamed Ahmadi; Asghar Akbari Foroud

2014-06-01T23:59:59.000Z

426

Development and use of the GREET model to estimate fuel-cycle energy use and emissions of various transportation technologies and fuels  

SciTech Connect (OSTI)

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, carbon monoxide, nitrogen oxides, sulfur oxides, 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 (hydrogen, 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.

1996-03-01T23:59:59.000Z

427

Transport modeling in performance assessments for the Yucca Mountain disposal system for spent nuclear fuel and high-level radioactive waste  

Science Journals Connector (OSTI)

Abstract This paper summarizes modeling of radionuclide transport in the unsaturated and saturated zone conducted between 1984 and 2008 to evaluate feasibility, viability, and assess compliance of a repository for spent nuclear fuel and high-level radioactive waste at Yucca Mountain, Nevada. One dimensional (1-D) transport for a single porosity media without lateral dispersion was solved in both the saturated zone (SZ) and unsaturated zone (UZ) for the first assessment in 1984 but progressed to a dual-porosity formulation for the UZ in the second assessment in 1991. By the time of the viability assessment, a dual-permeability transport formulation was used in the UZ. With the planned switch to a dose performance measure, individual dose from a drinking water pathway was evaluated for the third assessment in 1993 and from numerous pathways for the viability assessment in 1998 and thereafter. Stream tubes for transport in the SZ were initially developed manually but progressed to particle tracking in 1991. For the viability assessment, particle tracking was used to solve the transport equations in the 3-D UZ and SZ flow fields. To facilitate calculations, the convolution method was also used in the SZ for the viability assessment. For the site recommendation in 2001 and licensing compliance analysis in 2008, the 3-D transport results of the SZ were combined with 1-D transport results, which evaluated decay of radionuclides, in order to evaluate compliance with groundwater protection requirements. Uncertainty in flow within the unsaturated and saturated zone was generally important to explaining the spread in the individual dose performance measure.

Rob P. Rechard; Bill W. Arnold; Bruce A. Robinson; James E. Houseworth

2014-01-01T23:59:59.000Z

428

Triclosan Reactivity in Chloraminated Waters  

Science Journals Connector (OSTI)

Triclosan Reactivity in Chloraminated Waters ... Triclosan, widely employed as an antimicrobial additive in many household personal care products, has recently been detected in wastewater treatment plant effluents and in source waters used for drinking water supplies. ... Chloramines used either as alternative disinfectants in drinking water treatment or formed during chlorination of nonnitrified wastewater effluents have the potential to react with triclosan. ...

Aimee E. Greyshock; Peter J. Vikesland

2006-03-16T23:59:59.000Z

429

Estimates of Radioxenon Released from Southern Hemisphere Medical isotope Production Facilities Using Measured Air Concentrations and Atmospheric Transport Modeling  

SciTech Connect (OSTI)

Abstract The International Monitoring System (IMS) of the Comprehensive-Nuclear-Test-Ban-Treaty monitors the atmosphere for radioactive xenon leaking from underground nuclear explosions. Emissions from medical isotope production represent a challenging background signal when determining whether measured radioxenon in the atmosphere is associated with a nuclear explosion prohibited by the treaty. The Australian Nuclear Science and Technology Organisation (ANSTO) operates a reactor and medical isotope production facility in Lucas Heights, Australia. This study uses two years of release data from the ANSTO medical isotope production facility and Xe-133 data from three IMS sampling locations to estimate the annual releases of Xe-133 from medical isotope production facilities in Argentina, South Africa, and Indonesia. Atmospheric dilution factors derived from a global atmospheric transport model were used in an optimization scheme to estimate annual release values by facility. The annual releases of about 6.81014 Bq from the ANSTO medical isotope production facility are in good agreement with the sampled concentrations at these three IMS sampling locations. Annual release estimates for the facility in South Africa vary from 1.21016 to 2.51016 Bq and estimates for the facility in Indonesia vary from 6.11013 to 3.61014 Bq. Although some releases from the facility in Argentina may reach these IMS sampling locations, the solution to the objective function is insensitive to the magnitude of those releases.

Eslinger, Paul W.; Friese, Judah I.; Lowrey, Justin D.; McIntyre, Justin I.; Miley, Harry S.; Schrom, Brian T.

2014-04-06T23:59:59.000Z

430

Transportation | Argonne National Laboratory  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Transportation Transportation From modeling and simulation programs to advanced electric powertrains, engines, biofuels, lubricants, and batteries, Argonne's transportation research is vital to the development of next-generation vehicles. Revolutionary advances in transportation are critical to reducing our nation's petroleum consumption and the environmental impact of our vehicles. Some of the most exciting new vehicle technologies are being ushered along by research conducted at Argonne National Laboratory. Our Transportation Technology R&D Center (TTRDC) brings together scientists and engineers from many disciplines across the laboratory to work with the U.S. Department of Energy (DOE), automakers and other industrial partners. Our goal is to put new transportation technologies on the road that improve

431

Definition: Reactive Power | Open Energy Information  

Open Energy Info (EERE)

Reactive Power Reactive Power Jump to: navigation, search Dictionary.png Reactive Power The portion of electricity that establishes and sustains the electric and magnetic fields of alternating-current equipment. Reactive power must be supplied to most types of magnetic equipment, such as motors and transformers. It also must supply the reactive losses on transmission facilities. Reactive power is provided by generators, synchronous condensers, or electrostatic equipment such as capacitors and directly influences electric system voltage. It is usually expressed in kilovars (kvar) or megavars (Mvar).[1] View on Wikipedia Wikipedia Definition In electric power transmission and distribution, volt-ampere reactive (var) is a unit used to measure reactive power in an AC electric

432

Reactive Power Support Services in Electricity Markets  

E-Print Network [OSTI]

Reactive Power Support Services in Electricity Markets Costing and Pricing of Ancillary Services Final Project Report Power Systems Engineering Research Center A National Science Foundation Industry Reactive Power Support Services in Electricity Markets Costing and Pricing of Ancillary Services Project

433

Development of Waste Acceptance Criteria at 221-U Building: Initial Flow and Transport Scoping Calculations  

SciTech Connect (OSTI)

This report documents numerical flow and transport simulations performed that establish initial waste acceptance criteria for the potential waste streams that may be safely sequestered in the 221-U Building and similar canyon structures. Specifically, simulations were executed to identify the maximum loading of contaminant mass (without respect to volume) that can be emplaced within the 221-U Building with no more than 1 pCi/m2 of contaminant migrating outside the structure within a 1,000 year time period. The initial scoping simulations were executed in one dimension to assess important processes, and then two dimensions to establish waste acceptance criteria. Two monolithic conditions were assessed: (1) a grouted canyon monolith; and (2) a canyon monolith filled with sand, both assuming no cracks or fissures were present to cause preferential transport. A three-staged approach was taken to account for different processes that may impact the amount of contaminant that can be safely sequestered in canyon structure. In the first stage, flow and transport simulations established waste acceptance criteria based on a linear (Kd) isotherm approach. In the second stage, impacts on thermal loading were examined and the differences in waste acceptance criteria quantified. In the third stage of modeling, precipitation/dissolution reactions were considered on the release and transport of the contaminants, and the subsequent impact on the maximum contaminant loading. The reactive transport modeling is considered a demonstration of the reactive transport capability, and shows the importance of its use for future performance predictions once site-specific data have been obtained.

Freedman, Vicky L.; Zhang, Z. F.; Keller, Jason M.; Chen, Yousu

2007-05-30T23:59:59.000Z

434

General Multiobjective Force Field Optimization Framework, with Application to Reactive Force Fields for Silicon Carbide  

E-Print Network [OSTI]

Fields for Silicon Carbide Andres Jaramillo-Botero,* Saber Naserifar, and William A. Goddard, III: (1) the ReaxFF reactive force field for modeling the adiabatic reactive dynamics of silicon carbide specific force field parameters for tripod metal templates, tripodMO(CO)3, using the root mean square

Goddard III, William A.

435

Passive Ozone Control Through Use of Reactive Indoor Wall and Ceiling Materials  

E-Print Network [OSTI]

Passive Ozone Control Through Use of Reactive Indoor Wall and Ceiling Materials Paper # 715 Donna A and unpainted drywall as passive ozone control surfaces in a room-sized laboratory chamber. Mean deposition-50%, resulted in increased reactivity for activated carbon. In our model for a typical house, about 35

Siegel, Jeffrey

436

Surface tension in a reactive binary mixture of incompressible fluids  

E-Print Network [OSTI]

Surface tension in a reactive binary mixture of incompressible fluids Henning Struchtrup Institute with a distributed form of surface tension. The model describes chemistry, diffusion, viscosity and heat transfer tension at the front. Keywords: Binary mixtures, Surface tension, Irreversible thermodynamics, Hele

Struchtrup, Henning

437

Characterization of groundwater flow and transport in the General Separations Areas, Savannah River Plant: Flow model refinement and particle-tracking analysis report  

SciTech Connect (OSTI)

The Department of Energy (DOE) is preparing the necessary NEPA documentation for an Environmental Impact Statement (EIS) to address the waste disposal activities for groundwater protection at the Savannah River Plant (SRP). For purposes of this EIA, the areas within the plant have been separated into 26 functional groups based primarily on hydrogeologic setting and types of disposed waste materials. The overall objective is to provide an appropriate quantitative assessment of the environmental impacts from past and future operations within each functional group. The analysis from each functional group will be integrated to assess the impacts of plant-wide operations. A flexible approach to quantifying the impacts using several methods of quantitative analysis is being employed. Numerical flow and transport modeling is one method being applied to several functional groups. The scope of work can be divided into four broad categories: (1) Data Review and Conceptual Model Development, (2) Groundwater Flow Model Construction and Refinement, (3) Solute Transport Model Construction, and (4) Remedial Alternative Simulations. The major topics covered in this report are: (1) summary of the hydrogeologic conditions of the area, (2) observed flow velocities at the study site, (3) a summary of results from the preliminary flow modeling effort, (4) flow model refinement and results, and (5) particle tracking analyses based on the refined flow model.

Duffield, G.M.; Buss, D.R.; Root, R.W. Jr.; Hughes, S.S.; Mercer, J.W. [GeoTrans, Inc., Sterling, VA (United States)

1986-03-01T23:59:59.000Z

438

Transport Model with Quasipions  

E-Print Network [OSTI]

, and the Welch Foundation under Grant No. A-1110 (C.M.K. and L.X.). We would like to acknowledge many fruitful discussions with W. Bauer, B.A. Li, P. D. Danielewicz, and U. Mosel concerning pion production. One of the authors (C.M.K.) also thanks M. Asakawa... for helpful discussions. [1] J. Cugnon, D. Kinet, and J. Vandermeullen, Nucl. Phys. A379, 553 (1982). [2] Y. Kitazoe, M. Gyulassy, P. Danielewicz, H. Toki, Y. Yamamura, and M. Sano, Phys. Lett. B 138, 341 (1984); Y. Kitazoe, M. Sano, H. Toki, and S...

Xiong, L.; Ko, Che Ming; Koch, V.

1993-01-01T23:59:59.000Z

439

Carrier-mediated transport of monocarboxylic acids in BeWo cell monolayers as a model of the human trophoblast  

E-Print Network [OSTI]

The monolayer-forming, human choriocarcinoma cell line, BeWo, was used to study the mechanisms of monocarboxylic acid transport across the human trophoblast. Benzoic acid, acetic acid, and lactic acid were used as markers ...

Utoguchi, Naoki; Magnusson, Malin; Audus, Kenneth L.

1999-01-01T23:59:59.000Z

440

Transport and Metabolism of Opioid Peptides across BeWo Cells, An In Vitro Model of the Placental Barrier  

E-Print Network [OSTI]

In keeping with the advance of biotechnology, cell culture becomes an important tool for investigating the transport and the metabolism phenomena. A cell line of human origin, the BeWo choriocarcinoma cell line, was used ...

Ampasavate, Chadarat; Chandorkar, Gurudatt A.; Velde, David Vande; Stobaugh, John F.; Audus, Kenneth L.

2002-01-01T23:59:59.000Z

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441

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

442

Reactive Ion Benjamin A. Small  

E-Print Network [OSTI]

(torr) plasma etching reactive ion etching ion milling m cm 100µm µm #12;5 Mechanics ~40 mTorrE380 kHz, 13.56 MHz ~30 sccm #12;6 Chemistry X X X X F- F- F-F- X F-F- F- F- F- R++ R++ R++ #12;7 Chemistry before opening · Silanes are explosive in the atmosphere #12;13 Bibliography Campbell, Stephen A

Garmestani, Hamid

443

Internal structure, hygroscopic and reactive properties of mixed sodium  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Internal structure, hygroscopic and Internal structure, hygroscopic and reactive properties of mixed sodium methanesulfonate-sodium chloride particles Internal structure, hygroscopic and reactive properties of mixed sodium methanesulfonate-sodium chloride particles Print Friday, 13 May 2011 00:00 Scientists recently combined experimental approaches and molecular dynamics modeling to gain new insights into the internal structure of sea salt particles and relate it to their fundamental chemical reactivity in the atmosphere. This research shows that surface enhancement or depletion of chemical components in marine particles can occur because of the difference in the chemical nature of the species. Because the atmospheric chemistry of the salt particles takes place at the gas-particle interface, understanding their complex surfaces provides new insights about their effect on the environment and climate change. Article Link.