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1

Updating Applied Diffusion Models  

Science Conference Proceedings (OSTI)

Most diffusion models currently used in air quality applications are substantially out of date with understanding of turbulence and diffusion in the planetary boundary layer. Under a Cooperative Agreement with the Environmental Protection Agency, ...

J. C. Weil

1985-11-01T23:59:59.000Z

2

Tidal Diffusivity: A Mechanism for Frontogenesis  

Science Conference Proceedings (OSTI)

It is hypothesized that tidal mixing may provide a “diffusivitymechanism for frontogenesis. It stems from the fact that tidal diffusivity varies in the opposite sense from the water depth, so the vertically integrated diffusivity may exhibit a ...

Hsien-Wang Ou; Chang-Ming Dong; Dake Chen

2003-04-01T23:59:59.000Z

3

In vivo facilitated diffusion model  

E-Print Network (OSTI)

Under dilute in vitro conditions transcription factors rapidly locate their target sequence on DNA by using the facilitated diffusion mechanism. However, whether this strategy of alternating between three-dimensional bulk diffusion and one-dimensional sliding along the DNA contour is still beneficial in the crowded interior of cells is highly disputed. Here we use a simple model for the bacterial genome inside the cell and present a semi-analytical model for the in vivo target search of transcription factors within the facilitated diffusion framework. Without having to resort to extensive simulations we determine the mean search time of a lac repressor in a living E. coli cell by including parameters deduced from experimental measurements. The results agree very well with experimental findings, and thus the facilitated diffusion picture emerges as a quantitative approach to gene regulation in living bacteria cells. Furthermore we see that the search time is not very sensitive to the parameters characterizing the DNA configuration and that the cell seems to operate very close to optimal conditions for target localization. Local searches as implied by the colocalization mechanism are only found to mildly accelerate the mean search time within our model.

Max Bauer; Ralf Metzler

2013-01-23T23:59:59.000Z

4

Quasichemical Models of Multicomponent Nonlinear Diffusion  

E-Print Network (OSTI)

Diffusion preserves the positivity of concentrations, therefore, multicomponent diffusion should be nonlinear if there exist non-diagonal terms. The vast variety of nonlinear multicomponent diffusion equations should be ordered and special tools are needed to provide the systematic construction of the nonlinear diffusion equations for multicomponent mixtures with significant interaction between components. We develop an approach to nonlinear multicomponent diffusion based on the idea of the reaction mechanism borrowed from chemical kinetics. Chemical kinetics gave rise to very seminal tools for the modeling of processes. This is the stoichiometric algebra supplemented by the simple kinetic law. The results of this invention are now applied in many areas of science, from particle physics to sociology. In our work we extend the area of applications onto nonlinear multicomponent diffusion. We demonstrate, how the mechanism based approach to multicomponent diffusion can be included into the general thermodynamic ...

Gorban, A N; Wahab, H A

2011-01-01T23:59:59.000Z

5

Modeling phosphorus diffusion in three dimensions  

Science Conference Proceedings (OSTI)

A three-dimensional process simulator in which both the standard nonlinear diffusion model and a five-species kinetic model are implemented to model phosphorus diffusion in silicon is described. The reaction-diffusion equations are discretized using ...

W. B. Richardson; G. F. Carey; B. J. Mulvaney

2006-11-01T23:59:59.000Z

6

Diffusion-based DNA target colocalization by thermodynamic mechanisms  

E-Print Network (OSTI)

In eukaryotic cell nuclei, a variety of DNA interactions with nuclear elements occur, which, in combination with intra- and inter- chromosomal cross-talks, shape a functional 3D architecture. In some cases they are organized by active, i.e. actin/myosin, motors. More often, however, they have been related to passive diffusion mechanisms. Yet, the crucial questions on how DNA loci recognize their target and are reliably shuttled to their destination by Brownian diffusion are still open. Here, we complement the current experimental scenario by considering a physics model, in which the interaction between distant loci is mediated by diffusing bridging molecules. We show that, in such a system, the mechanism underlying target recognition and colocalization is a thermodynamic switch-like process (a phase transition) that only occurs if the concentration and affinity of binding molecules is above a threshold, or else stable contacts are not possible. We also briefly discuss the kinetics of this "passive-shuttling" process, as produced by random diffusion of DNA loci and their binders, and derive predictions based on the effects of genomic modifications and deletions.

Antonio Scialdone; Mario Nicodemi

2011-05-04T23:59:59.000Z

7

MODEL OF DIFFUSERS / PERMEATORS FOR HYDROGEN PROCESSING  

DOE Green Energy (OSTI)

Palladium-silver (Pd-Ag) diffusers are mainstays of hydrogen processing. Diffusers separate hydrogen from inert species such as nitrogen, argon or helium. The tubing becomes permeable to hydrogen when heated to more than 250 C and a differential pressure is created across the membrane. The hydrogen diffuses better at higher temperatures. Experimental or experiential results have been the basis for determining or predicting a diffuser's performance. However, the process can be mathematically modeled, and comparison to experimental or other operating data can be utilized to improve the fit of the model. A reliable model-based diffuser system design is the goal which will have impacts on tritium and hydrogen processing. A computer model has been developed to solve the differential equations for diffusion given the operating boundary conditions. The model was compared to operating data for a low pressure diffuser system. The modeling approach and the results are presented in this paper.

Hang, T; William Jacobs, W

2007-08-27T23:59:59.000Z

8

Fractional diffusion modeling of ion channel gating  

E-Print Network (OSTI)

An anomalous diffusion model for ion channel gating is put forward. This modeling scheme is able to describe the non-exponential, power-law like gating behavior of residence time intervals in several types of ion channels. Our scheme presents a generalization of the discrete diffusion model by Millhauser, Salpeter and Oswald [Proc. Natl. Acad. Sci. USA 85, 1503 (1988)] to the case of a continuous, anomalously slow conformational diffusion. The corresponding generalization is derived from a continuous time random walk composed of nearest neighbor jumps which in the scaling limit results in a fractional diffusion equation. The studied model contains three parameters only: the mean residence time, a characteristic time of conformational diffusion, and the index of subdiffusion. A tractable analytical expression for the characteristic function of the residence time distribution (RTD) is obtained. In the limiting case of normal diffusion a prior result of Goychuk and Hanggi [Proc. Natl. Acad. Sci. USA 99, 3552 (20...

Goychuk, I; Goychuk, Igor; Hanggi, Peter

2004-01-01T23:59:59.000Z

9

New frontiers in diffusion modeling  

E-Print Network (OSTI)

Over the last fifty years, diffusion researchers have sought to explain why the rate of adoption of an innovation varies over time. Some innovations are adopted quickly as compared to others, which take decades for adoption. ...

Ranganath, Naveen Chandra

2012-01-01T23:59:59.000Z

10

Mechanisms of Stochastic Diffusion of Energetic Ions in Spherical Tori  

Science Conference Proceedings (OSTI)

Stochastic diffusion of the energetic ions in spherical tori is considered. The following issues are addressed: (I) Goldston-White-Boozer diffusion in a rippled field; (ii) cyclotron-resonance-induced diffusion caused by the ripple; (iii) effects of non-conservation of the magnetic moment in an axisymmetric field. It is found that the stochastic diffusion in spherical tori with a weak magnetic field has a number of peculiarities in comparison with conventional tokamaks; in particular, it is characterized by an increased role of mechanisms associated with non-conservation of the particle magnetic moment. It is concluded that in current experiments on National Spherical Torus eXperiment (NSTX) the stochastic diffusion does not have a considerable influence on the confinement of energetic ions.

Ya.I. Kolesnichenko; R.B. White; Yu.V. Yakovenko

2001-01-18T23:59:59.000Z

11

Wind and Diffusion Modeling for Complex Terrain  

Science Conference Proceedings (OSTI)

Atmospheric transport and dispersion over complex terrain were investigated. Meteorological and sulfur hexafluoride (SF6) concentration data were collected and used to evaluate the performance of a transport and diffusion model coupled with a ...

Robert M. Cox; John Sontowski; Richard N. Fry Jr.; Catherine M. Dougherty; Thomas J. Smith

1998-10-01T23:59:59.000Z

12

Diffusion Models for Transient Releases  

Science Conference Proceedings (OSTI)

Plume models were developed to predict the concentration due to a nonbuoyant release from a source whose strength decreases exponentially with time of a pollutant that reacts in the atmosphere at a first-order rate. Models were developed that ...

Thomas J. Overcamp

1990-12-01T23:59:59.000Z

13

Diffusion based degradation mechanisms in giant magnetoresistive spin valves  

Science Conference Proceedings (OSTI)

Spin valve systems based on the giant magnetoresistive effect as used, for example, in hard disks and automotive applications consist of several functional metallic thin film layers. We have identified by secondary ion mass spectrometry two main degradation mechanisms: one is related to oxygen diffusion through a protective cap layer and the other one is interdiffusion directly at the functional layers of the giant magnetoresistive stack. By choosing a suitable material as cap layer (TaN), the oxidation effect can be suppressed.

Hawraneck, Matthias [Department of Sense and Control, Infineon Technologies AG, 85579 Neubiberg (Germany); Institute for Materials Science, Technische Universitaet Darmstadt, 64287 Darmstadt (Germany); Zimmer, Juergen; Raberg, Wolfgang; Pruegl, Klemens; Schmitt, Stephan; Bever, Thomas [Department of Sense and Control, Infineon Technologies AG, 85579 Neubiberg (Germany); Flege, Stefan; Alff, Lambert [Institute for Materials Science, Technische Universitaet Darmstadt, 64287 Darmstadt (Germany)

2008-07-07T23:59:59.000Z

14

Modelling international wind energy diffusion: Are the patterns of induced diffusion `S'  

E-Print Network (OSTI)

Modelling international wind energy diffusion: Are the patterns of induced diffusion `S' shaped datasets, the paper explores the patterns of international wind energy diffusion in OECD countries. The model employed in the paper predicted that wind energy, as a complex and expensive innovation, would

Feigon, Brooke

15

Modeling Vertical and Horizontal Diffusivities with the Sigma Coordinate System  

Science Conference Proceedings (OSTI)

The use of diffusive terms in numerical ocean models is examined relative to different coordinate systems. The conventional model for horizontal diffusion is found to be incorrect when bottom topographical slopes are large. A new formulation is ...

George L. Mellor; Alan F. Blumberg

1985-08-01T23:59:59.000Z

16

Distributed Energy Resources Market Diffusion Model  

SciTech Connect

Distributed generation (DG) technologies, such as gas-fired reciprocating engines and microturbines, have been found to be economically beneficial in meeting commercial-sector electrical, heating, and cooling loads. Even though the electric-only efficiency of DG is lower than that offered by traditional central stations, combined heat and power (CHP) applications using recovered heat can make the overall system energy efficiency of distributed energy resources (DER) greater. From a policy perspective, however, it would be useful to have good estimates of penetration rates of DER under various economic and regulatory scenarios. In order to examine the extent to which DER systems may be adopted at a national level, we model the diffusion of DER in the US commercial building sector under different technical research and technology outreach scenarios. In this context, technology market diffusion is assumed to depend on the system's economic attractiveness and the developer's knowledge about the technology. The latter can be spread both by word-of-mouth and by public outreach programs. To account for regional differences in energy markets and climates, as well as the economic potential for different building types, optimal DER systems are found for several building types and regions. Technology diffusion is then predicted via two scenarios: a baseline scenario and a program scenario, in which more research improves DER performance and stronger technology outreach programs increase DER knowledge. The results depict a large and diverse market where both optimal installed capacity and profitability vary significantly across regions and building types. According to the technology diffusion model, the West region will take the lead in DER installations mainly due to high electricity prices, followed by a later adoption in the Northeast and Midwest regions. Since the DER market is in an early stage, both technology research and outreach programs have the potential to increase DER adoption, and thus, shift building energy consumption to a more efficient alternative.

Maribu, Karl Magnus; Firestone, Ryan; Marnay, Chris; Siddiqui,Afzal S.

2006-06-16T23:59:59.000Z

17

Distributed Energy Resources Market Diffusion Model  

SciTech Connect

Distributed generation (DG) technologies, such as gas-fired reciprocating engines and microturbines, have been found to be economically beneficial in meeting commercial-sector electrical, heating, and cooling loads. Even though the electric-only efficiency of DG is lower than that offered by traditional central stations, combined heat and power (CHP) applications using recovered heat can make the overall system energy efficiency of distributed energy resources (DER) greater. From a policy perspective, however, it would be useful to have good estimates of penetration rates of DER under various economic and regulatory scenarios. In order to examine the extent to which DER systems may be adopted at a national level, we model the diffusion of DER in the US commercial building sector under different technical research and technology outreach scenarios. In this context, technology market diffusion is assumed to depend on the system's economic attractiveness and the developer's knowledge about the technology. The latter can be spread both by word-of-mouth and by public outreach programs. To account for regional differences in energy markets and climates, as well as the economic potential for different building types, optimal DER systems are found for several building types and regions. Technology diffusion is then predicted via two scenarios: a baseline scenario and a program scenario, in which more research improves DER performance and stronger technology outreach programs increase DER knowledge. The results depict a large and diverse market where both optimal installed capacity and profitability vary significantly across regions and building types. According to the technology diffusion model, the West region will take the lead in DER installations mainly due to high electricity prices, followed by a later adoption in the Northeast and Midwest regions. Since the DER market is in an early stage, both technology research and outreach programs have the potential to increase DER adoption, and thus, shift building energy consumption to a more efficient alternative.

Maribu, Karl Magnus; Firestone, Ryan; Marnay, Chris; Siddiqui,Afzal S.

2006-06-16T23:59:59.000Z

18

Modeling of Spectralon diffusers for radiometric calibration in remote sensing  

E-Print Network (OSTI)

Modeling of Spectralon diffusers for radiometric calibration in remote sensing G. Bazalgette Courre Abstract. Onboard calibration of radiometric measurements in remote sensing is often achieved for publication May 28, 2003. 1 Introduction Light diffusers are used in remote sensing applications

Sprik, Rudolf

19

Stable Schemes for Nonlinear Vertical Diffusion in Atmospheric Circulation Models  

Science Conference Proceedings (OSTI)

The intensity of vertical mixing in atmospheric models generally depends on wind shear and static stability, making the diffusion process nonlinear. Traditional implicit numerical schemes, which treat the variables to be diffused implicitly but ...

Claude Girard; Yves Delage

1990-03-01T23:59:59.000Z

20

Quantization in Classical Mechanics and Diffusion Mechanism of Alpha Decay, Proton and Cluster Radioactivity, Spontaneous Fission  

SciTech Connect

Based on the Chetaev generalized theorem the Schroedinger equation as the stability condition of trajectories in classical dynamics in the presence of dissipative forces is derived. In the framework of this approach the alternative model for unified description of alpha decay, spontaneous fission, cluster and proton radioactivity and is developed. We show the possibility of the classical (without tunneling) description of radioactive decay of heavy nuclei, when the so called noise-induced transition or, in other words, the stochastic channel of radioactive decay conditioned by the Kramers diffusion mechanism is generated under certain conditions.Using the ENSDF nuclear data, we have found the parametrized solutions of the Kramers equation of the Langevin type by the Alexandrov dynamic auto-regularization method (REGN-Dubna program). These solutions describe with high-accuracy the dependences of half-life (the decay probability) of heavy radioactive nuclei on total kinetic energy of daughter decay products.Verification of the inverse problem solution in the framework of the universal Kramers description of alpha decay, spontaneous fission, cluster and proton radioactivity, which based on the newest experimental data for alpha-decay of even-even superheavy nuclei (Z = 114, 116, 118), shows good coincidence of the experimental and theoretical dependences of half-life on alpha-decay energy.

Rusov, V. D.; Vlasenko, D. S.; Deliyergiyev, M. A. [Department of Theoretical and Experimental Nuclear Physics, Odessa National Polytechnic University, Odessa (Ukraine); Mavrodiev, S. Cht. [Institute for Nuclear Research and Nuclear Energy, BAS, Sofia (Bulgaria)

2010-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "diffusion mechanisms 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

Quantization in Classical Mechanics and Diffusion Mechanism of Alpha Decay, Cluster Radioactivity, Spontaneous Fission  

SciTech Connect

Based on the Chetaev generalized theorem the Schredinger equation as the stability condition of trajectories in classical dynamics in the presence of dissipative forces is derived. In the framework of this approach the alternative model for unified description of alpha decay, spontaneous fission, cluster radioactivity and is developed. We show the possibility of the classical (without tunneling) description of radioactive decay of heavy nuclei, when the so called noise-induced transition or, in other words, the stochastic channel of radioactive decay conditioned by the Kramers diffusion mechanism is generated under certain conditions.Using the ENSDF nuclear data, we have found the parametrized solutions of the Kramers equation of the Langevin type by the Alexandrov dynamic auto-regularization method (REGN-Dubna program). These solutions describe with high-accuracy the dependences of half-life (the decay probability) of heavy radioactive nuclei on total kinetic energy of daughter decay products.Verification of the inverse problem solution in the framework of the universal Kramers description of alpha decay, spontaneous fission, cluster radioactivity, which based on the newest experimental data for alpha-decay of even-even superheavy nuclei (Z = 114, 116, 118), shows good coincidence of the experimental and theoretical dependences of half-life on alpha-decay energy.

Rusov, V. D.; Vlasenko, D. S.; Deliyergiyev, M. A. [Department of Theoretical and Experimental Nuclear Physics, Odessa National Polytechnic University, Odessa (Ukraine); Mavrodiev, S. Cht. [Institute for Nuclear Research and Nuclear Energy, BAS, Sofia (Bulgaria)

2010-05-04T23:59:59.000Z

22

LHC Beam Diffusion Effects: Models and Measurements  

Science Conference Proceedings (OSTI)

Radio Frequency (RF) accelerating system noise and non-idealities can have detrimental impact on the LHC performance through longitudinal motion and longitudinal emittance growth. A theoretical formalism has been developed to relate the beam and RF loop dynamics with the bunch length growth [1]. Measurements were conducted at LHC to validate the formalism, determine the performance limiting RF components, and provide the foundation for beam diffusion estimates for higher energies and intensities. A brief summary of these results is presented in this work. During a long store, the relation between the energy lost to synchrotron radiation and the noise injected to the beam by the RF accelerating voltage determines the growth of the bunch energy spread and longitudinal emittance. Since the proton synchrotron radiation in the LHC is very low, the beam diffusion is extremely sensitive to RF perturbations. The theoretical formalism presented in [1], suggests that the noise experienced by the beam depends on the cavity phase noise power spectrum, filtered by the beam transfer function, and aliased due to the periodic sampling of the accelerating voltage signal V{sub c}. Additionally, the dependence of the RF accelerating cavity noise spectrum on the Low Level RF (LLRF) configurations has been predicted using time-domain simulations and models [2]. In this work, initial measurements at the LHC supporting the above theoretical formalism and simulation predictions are presented.

Mastorides, T.; /SLAC; Rivetta, C.; /SLAC; Fox, J.D.; /SLAC; Van Winkle, D.; /SLAC; Baudrenghien, P.; /CERN; Butterworth, A.; /CERN; Molendijk, J.; /CERN

2010-09-14T23:59:59.000Z

23

Diffusion effects on a superconductive model  

E-Print Network (OSTI)

A superconductive model characterized by a third order parabolic operator L" is analysed. When the viscous terms, represented by higher - order deriva- tives, tend to zero, a hyperbolic operator L0 appears. Furthermore, if P" is the Dirichlet initial boundary - value problem for L", when L" turns into L0; P" turns into a problem P0 with the same initial - boundary conditions as P". The solution of the nonlinear problem related to the remainder term r is achieved, as long as the higher-order derivatives of the solution of P0 are bounded. More- over, some classes of explicit solutions related to P0 are determined, proving the existence of at least one motion whose derivatives are bounded. The estimate shows that the diffusion effects are bounded even when time tends to infinity.

M. de Angelis; G. Fiore

2012-11-06T23:59:59.000Z

24

Radon diffusion through multilayer earthen covers: models and simulations  

SciTech Connect

A capability to model and analyze the fundamental interactions that influence the diffusion of radon gas through uranium mill tailings and cover systems has been investigated. The purpose of this study is to develop the theoretical basis for modeling radon diffusion and to develop an understanding of the fundamental interactions that influence radon diffusion. This study develops the theoretical basis for modeling radon diffusion in one, two and three dimensions. The theory has been incorporated into three computer models that are used to analyze several tailings and cover configurations. This report contains a discussion of the theoretical basis for modeling radon diffusion, a discussion of the computer models used to analyze uranium mill tailings and multilayered cover systems, and presents the results that have been obtained.

Mayer, D.W.; Oster, C.A.; Nelson, R.W.; Gee, G.W.

1981-09-01T23:59:59.000Z

25

A combinatorial model of malware diffusion via Bluetooth connections  

E-Print Network (OSTI)

We outline here the mathematical expression of a diffusion model for cellphones malware transmitted through Bluetooth channels. In particular, we provide both the recursive and the explicit formula underlying the proposed model.

Merler, Stefano

2012-01-01T23:59:59.000Z

26

Numerical Early Warning Model Research of Landfill Gas Permeation and Diffusion Considering Flow-Temperature Coupling  

Science Conference Proceedings (OSTI)

Based on seepage mechanics in porous medium gas and heat transfer theory, numerical early warning model is established, which is on quantitative description of migration and release of landfill gas and penetration and diffusion of energy, and dynamic ... Keywords: component, landfill gas, flow-temperature coupling, gas pressure and temperature distribution, numerical early warning model

Xue Qiang; Feng Xia-ting; Ma Shi-jin; Zhou Xiao-jun

2009-10-01T23:59:59.000Z

27

H Diffusion for Impurity and Defect Passivation: A Physical Model for Solar Cell Processing; Preprint  

DOE Green Energy (OSTI)

We propose a physical model for diffusion of H in Si containing impurities and defects. The diffusion occurs via several parallel mechanisms, involving complex formation (trapping) and dissociation (detrapping) at impurities and defects, hopping in lattice interstitial sites, and charge-state conversion. The role of bulk and process-induced traps is considered to explain observations from plasma, ion implantation, and PECVD-nitridation processes.

Sopori, B. L.; Zhang, Y.; Reedy, R.

2002-05-01T23:59:59.000Z

28

Numerical Discretization of Rotated Diffusion Operators in Ocean Models  

Science Conference Proceedings (OSTI)

A method to improve the behavior of the numerical discretization of a rotated diffusion operator such as, for example, the isopycnal diffusion parameterization used in large-scale ocean models based on the so-called z-coordinate system is ...

J-M. Beckers; H. Burchard; E. Deleersnijder; P. P. Mathieu

2000-08-01T23:59:59.000Z

29

Addition of Diffusion Model to MELCOR and Comparison with Data  

Science Conference Proceedings (OSTI)

A chemical diffusion model was incorporated into the thermal-hydraulics package of the MELCOR Severe Accident code (Reference 1) for analyzing air ingress events for a very high temperature gas-cooled reactor.

Brad Merrill; Richard Moore; Chang Oh

2004-06-01T23:59:59.000Z

30

Analysis and calibration of social factors in a consumer acceptance and adoption model for diffusion of diesel vehicle in Europe  

E-Print Network (OSTI)

While large scale diffusion of alternative fuel vehicles (AFVs) is widely anticipated, the mechanisms that determine their success or failure are ill understood. Analysis of an AFV transition model developed at MIT has ...

Zhang, Qi, S.M. Massachusetts Institute of Technology

2008-01-01T23:59:59.000Z

31

Measure of Diffusion Model Error for Thermal Radiation Transport  

E-Print Network (OSTI)

The diffusion approximation to the equation of transfer (Boltzmann transport equation) is usually applied to media where scattering dominates the interactions. Diffusion approximation helps in significant savings in terms of code complexity and computational time. However, this approximation often has significant error. Error due to the inherent nature of a physics model is called model error. Information about the model error associated with the diffusion approximation is clearly desirable. An indirect measure of model error is a quantity that is related in some way to the error but not equal to the error. In general, indirect measures of error are expected to be less costly than direct measures. Perhaps the most well-known indirect measure of the diffusion model error is the variable-Eddington tensor. This tensor provides a great deal of information about the angular dependence of the angular intensity solution, but it is not always simple to interpret. We define a new indirect measure of the diffusion model error called the diffusion model error source (DME source). When this DME source is added to the diffusion equation, the transport solution for the angular-integrated intensity is obtained. In contrast to the variable-Eddington tensor, our DME source is a scalar that is conceptually easy to interpret. In addition to defining the DME source analytically, we show how to generate this source numerically relative to the Sn radiative transfer equations with linear-discontinuous spatial discretization. This numerical source is computationally tested and shown to reproduce the Sn solution for a number of problems. Our radiative transfer model solves a coupled, time dependent, multi-frequency, 1-D slab equation and material heat transfer equation. We then use diffusion approximation to solve the same problem. The difference due to this approximation can be modelled by a “diffusion source”. The diffusion source is defined as an amount of inhomogeneous source that, when added to a diffusion calculation, gives a solution for the angle-integrated intensity that is equal to the transport solution.

Kumar, Akansha

2013-05-01T23:59:59.000Z

32

Mechanical model for ductility loss  

Science Conference Proceedings (OSTI)

A mechanical model was constructed to probe into the mechanism of ductility loss. Fracture criterion based on critical localized deformation was undertaken. Two microstructure variables were considered in the model. Namely, the strength ratio of grain boundary affected area to the matrix, ..cap omega.., and the linear fraction, x, of grain boundary affected area. A parametrical study was carried out. The study shows that the ductility is very sensitive to those microstructure parameters. The functional dependence of ductility to temperature as well as strain-rate, suggested by the model, is demonstrated to be consistent with the observation.

Hu, W.L.

1980-02-11T23:59:59.000Z

33

Analysis of price diffusion in financial markets using PUCK model  

E-Print Network (OSTI)

Based on the new type of random walk process called the Potentials of Unbalanced Complex Kinetics (PUCK) model, we theoretically show that the price diffusion in large scales is amplified 2/(2 + b) times, where b is the coefficient of quadratic term of the potential. In short time scales the price diffusion depends on the size M of the super moving average. Both numerical simulations and real data analysis of Yen-Dollar rates are consistent with theoretical analysis.

Mizuno, T; Takayasu, M; Mizuno, Takayuki; Takayasu, Hideki; Takayasu, Misako

2006-01-01T23:59:59.000Z

34

Modeling the Mechanics of the Cytoskeleton  

E-Print Network (OSTI)

Mechanics . . . . . . . . . . . . . . . . . . . . . . .t contribute to the network’s mechanics have been removed.R.D. Kamm, Cytoskeletal Mechanics, models and measurements,

Bai, Mo

2012-01-01T23:59:59.000Z

35

Discrepancies in Shortwave Diffuse Measured and Modeled Irradiances in Antarctica  

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

Discrepancies in Shortwave Diffuse Measured and Discrepancies in Shortwave Diffuse Measured and Modeled Irradiances in Antarctica A. Payton, P. Ricchiazzi, and C. Gautier University of California Santa Barbara, California D. Lubin Scripps Scripps Institution of Oceanography La Jolla, California Introduction Measurements of clear-sky shortwave (SW) radiation at the surface show discrepancies between measurements and model simulations, but only for certain measurements across time and space. Most of the observations entail broadband measurements. A spectral and spatial analysis of the occurrence of this discrepancy may lend insight into the responsible processes. Langley calibrated multi-filter rotating shadowband radiometer (MFRSR) measurements collected at the Antarctic coastline reveal significant

36

GIS-BASED 1-D DIFFUSIVE WAVE OVERLAND FLOW MODEL  

Science Conference Proceedings (OSTI)

This paper presents a GIS-based 1-d distributed overland flow model and summarizes an application to simulate a flood event. The model estimates infiltration using the Green-Ampt approach and routes excess rainfall using the 1-d diffusive wave approximation. The model was designed to use readily available topographic, soils, and land use/land cover data and rainfall predictions from a meteorological model. An assessment of model performance was performed for a small catchment and a large watershed, both in urban environments. Simulated runoff hydrographs were compared to observations for a selected set of validation events. Results confirmed the model provides reasonable predictions in a short period of time.

KALYANAPU, ALFRED [Los Alamos National Laboratory; MCPHERSON, TIMOTHY N. [Los Alamos National Laboratory; BURIAN, STEVEN J. [NON LANL

2007-01-17T23:59:59.000Z

37

Quantum hologram of macroscopically entangled light via the mechanism of diffuse light storage  

E-Print Network (OSTI)

In the present paper we consider a quantum memory scheme for light diffusely propagating through a spatially disordered atomic gas. The diffuse trapping of the signal light pulse can be naturally integrated with the mechanism of stimulated Raman conversion into a long-lived spin coherence. Then the quantum state of the light can be mapped onto the disordered atomic spin subsystem and can be stored in it for a relatively long time. The proposed memory scheme can be applicable for storage of the macroscopic analog of the $\\Psi^{(-)}$ Bell state and the prepared entangled atomic state performs its quantum hologram, which suggests the possibility of further quantum information processing.

L. V. Gerasimov; I. M. Sokolov; D. V. Kupriyanov; M. D. Havey

2011-11-29T23:59:59.000Z

38

Optimal Consumption Problem in a Diffusion Short-Rate Model  

E-Print Network (OSTI)

We consider a problem of an optimal consumption strategy on the infinite time horizon when the short-rate is a diffusion process. General existence and uniqueness theorem is illustrated by the Vasicek and so-called invariant interval models. We show also that when the short-rate dynamics is given by a Brownian motion or a geometric Brownian motion, then the value function is infinite.

Synowiec, Daniel

2009-01-01T23:59:59.000Z

39

Agent-based multi-optional model of innovations diffusion  

E-Print Network (OSTI)

We propose a formalism that allows the study of the process of diffusion of several products competing in a common market. It is based on the generalization of the statistics Ising model (Potts model). For the implementation, agent based modeling is used, applied to a problem of three options; to adopt a product A, a product B, or non-adoption. A launching strategy is analyzed for one of the two products, which delays its launching with the objective of competing with improvements. The proportion reached by one and another product is calculated at market saturation. The simulations are produced varying the social network topology, the uncertainty in the decision, and the population's homogeneity.

Laciana, Carlos E

2013-01-01T23:59:59.000Z

40

Diffusion versus Nonlocal Models of Stratospheric Mixing, in Theory and Practice  

Science Conference Proceedings (OSTI)

In zonally averaged chemical transport models of the stratosphere, quasi-isentropic mixing is represented by diffusion in latitude. However, it is fairly certain that the real mixing is to some extent nonlocal, so that the diffusive ...

Adam H. Sobel

1999-08-01T23:59:59.000Z

Note: This page contains sample records for the topic "diffusion mechanisms 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

Superdiffusion in a Model for Diffusion in a Molecularly Crowded Environment  

E-Print Network (OSTI)

We present a model for diffusion in a molecularly crowded environment. The model consists of random barriers in percolation network. Random walks in the presence of slowly moving barriers show normal diffusion for long times, but anomalous diffusion at intermediate times. The effective exponents for square distance versus time usually are below one at these intermediate times, but can be also larger than one for high barrier concentrations. Thus we observe sub- as well as super-diffusion in a crowded environment.

Dietrich Stauffer; Christian Schulze; Dieter W. Heermann

2007-06-05T23:59:59.000Z

42

In situ bioremediation: A network model of diffusion and flow in granular porous media  

SciTech Connect

In situ bioremediation is a potentially expedient, permanent and cost- effective means of waste site decontamination. However, permeability reductions due to the transport and deposition of native fines or due to excessive microorganism populations may severely inhibit the injection of supplemental oxygen in the contamination zone. To help understand this phenomenon, we have developed a micro-mechanical network model of flow, diffusion and particle transport in granular porous materials. The model differs from most similar models in that the network is defined by particle positions in a numerically-generated particle array. The model is thus widely applicable to computing effective transport properties for both ordered and realistic random porous media. A laboratory-scale apparatus to measure permeability reductions has also been designed, built and tested.

Griffiths, S.K.; Nilson, R.H.; Bradshaw, R.W.

1997-04-01T23:59:59.000Z

43

Analysis of the structure and mechanisms of extinction of a counterflow methanol-air diffusion flame  

SciTech Connect

Numerical calculations were performed to determine the structure and to clarify the extinction mechanisms of diffusion flames stabilized between counterflowing streams of methanol and air. The calculations were performed at a value of the thermodynamic pressure equal to 1 atmosphere, with different values for the rate of strain and with two different chemical kinetic mechanisms, mechanism a and mechanism b. Mechanism a and mechanism b have the same set of elementary reactions, but the rate constants for these elementary reactions were obtained from two different references. If mechanism a is used, the authors conclude that at low rates of strain the concentration of CH/sub 2/OH and HCO are in steady state and, if partial equilibrium is assumed for certain reactions, there exist algebraic relations among the concentrations of the radicals OH, H, and O. As the rate of strain is increased, HCO is no longer in steady state and no solution was obtained for a strain rate greater than 521 s/sup -1/. However, if mechanism b is used, the concentration of HCO alone is in steady state, and there also exist algebraic relations among the concentrations of the radicals OH, H, and O. As the rate of strain is increased, no solution was obtained for a strain rate greater than 168 s/sup -1/, and the authors speculate that extinction of the flame is due to a large value of the activation energy for a reaction controlling the pyrolysis of CH/sub 2/OH to CH/sub 2/O.

Seshadri, K.; Trevino, C.; Smooke, M.D.

1989-05-01T23:59:59.000Z

44

An Evaluation of the Role of Eddy Diffusion in Stratospheric Interactive Two-Dimensional Models  

Science Conference Proceedings (OSTI)

The effect of eddy diffusion in an interactive two-dimensional model of the stratosphere is reexamined. The model consists of a primitive equation dynamics module, a simplified HOx ozone model and a full radiative transfer scheme. The diabatic/...

Hans R. Schneider; Malcolm K. W. Ko; Nien Dak Sze; Guang-Yu Shi; Wei-Chyung Wang

1989-07-01T23:59:59.000Z

45

Gas-Phase Diffusion in Porous Media: Comparison of Models Stephen W. Webb  

Office of Scientific and Technical Information (OSTI)

Gas-Phase Diffusion in Porous Media: Comparison of Models Gas-Phase Diffusion in Porous Media: Comparison of Models Stephen W. Webb Sandia National Laboratories Albuquerque, New Mexico 87 185 ABSTRACT Two models are commonly used to analyze gas- phase diffusion in porous media in the presence of advection, the Advective-Dispersive Model (ADM) and the Dusty-gas Model (DGM). The ADM, which is used in TOUGH2, is based on a simple linear addition of advection calculated by Darcy's law and ordinary diffusion using Fick's law with a porosity- tortuosity-gas saturation multiplier to account for the porous medium. Another approach for gas-phase transport in porous media is the Dusty-Gas Model. This model applies the kinetic theory of gases to the gaseous components and the porous media (or "dust") to combine transport due to diffusion and

46

Monte Carlo Modeling of Diffuse Scattering from Single Crystals: The Program ZMC  

SciTech Connect

Diffuse scattering probes the local ordering in a crystal, whereas Bragg peaks are descriptive of the average long-range ordering. The population of local configurations can be explored by modeling the three-dimensional distribution of diffuse scattering. Local configurations are not constrained by the average crystallographic symmetry, so one way of modeling diffuse scattering is by modeling a disordered (short-range-ordered) structure and then calculating its diffuse scattering. The structure must contain enough unit cells to give a statistically valid model of the populations of local configurations, and so requirements for a program to model this ordering are very different from programs that model average crystal structures (used to fit the Bragg diffraction). ZMC is a program that has been developed to model diffuse scattering, particularly from molecular crystals. The strategies used to tackle the problem and the way in which they are implemented will be discussed.

Goossens, D.J.; Heerdegen, A.P.; Chan, E.J.; Welberry, T.R. (ANU)

2012-04-30T23:59:59.000Z

47

The Schrodinger-Chetaev Equation in Bohmian Quantum Mechanics and Diffusion Mechanism for Alpha Decay, Cluster Radioactivity and Spontaneous Fission  

E-Print Network (OSTI)

In the framework of Bohmian quantum mechanics supplemented with the Chetaev theorem on stable trajectories in dynamics in the presence of dissipative forces we have shown the possibility of the classical (without tunneling) universal description of radioactive decay of heavy nuclei, in which under certain conditions so called noise-induced transition is generated or, in other words, the stochastic channel of alpha decay, cluster radioactivity and spontaneous fission conditioned by the Kramers diffusion mechanism. Based on the ENSDF database we have found the parametrized solutions of the Kramers equation of Langevin type by Alexandrov dynamic auto-regularization method (FORTRAN program REGN-Dubna). These solutions describe with high-accuracy the dependence of the half-life (decay probability) of heavy radioactive nuclei on total kinetic energy of daughter decay products. The verification of inverse problem solution in the framework of the universal Kramers description of the alpha decay, cluster radioactivity and spontaneous fission, which was based on the newest experimental data of alpha-decay of even-even super heavy nuclei (Z=114, 116, 118) have shown the good coincidence of the experimental and theoretical half-life depend upon of alpha-decay energy.

V. D. Rusov; S. Cht. Mavrodiev; M. A. Deliyergiyev

2008-10-16T23:59:59.000Z

48

Comparison of homogenized and enhanced diffusion solutions of model PWR problems  

SciTech Connect

Model problem comparisons in slab geometry are made between two forms of homogenized diffusion theory and enhanced diffusion theory. The pin-cell discontinuity factors for homogenized diffusion calculations are derived from homogenized variational nodal P1 response matrices and from standard finite differencing. Enhanced diffusion theory consists of applying quasi-reflected interface conditions to reduce variational nodal Pn response matrices to one degree of freedom per interface, without homogenization within the cell. As expected both homogenized diffusion methods preserve reaction rates exactly if the discontinuity factors are derived from the P 11 reference solutions. If no reference lattice solution is available, discontinuity factors may be approximated from single cells with reflected boundary conditions; the computational effort is then comparable to calculating the enhanced diffusion response matrices. In this situation enhanced diffusion theory gives the most accurate results and finite difference discontinuity factors the least accurate. (authors)

Lewis, E. E. [Dept. of Mechanical Engineering, Northwestern Univ., 2145 Sheridan Rd., Evanston, IL 60208 (United States); Smith, M. A. [Nuclear Engineering Div., Argonne National Laboratory, 9700 S. Cass Ave, Argonne, IL 60439 (United States)

2012-07-01T23:59:59.000Z

49

Comparison between Wavenumber Truncation and Horizontal Diffusion Methods in Spectral Models  

Science Conference Proceedings (OSTI)

Commonly used horizontal diffusion and wavenumber truncation dealiasing methods in spectral models are verified using the National Center for Atmospheric Research Community Climate Model version 3. For the same horizontal grid resolution, time ...

Peter C. Chu; Xiong-Shan Chen; Chenwu Fan

2001-01-01T23:59:59.000Z

50

A Global Model for the Diapycnal Diffusivity Induced by Internal Gravity Waves  

Science Conference Proceedings (OSTI)

An energetically consistent model for the diapycnal diffusivity induced by breaking of internal gravity waves is proposed and tested in local and global settings. The model [Internal Wave Dissipation, Energy and Mixing (IDEMIX)] is based on the ...

Dirk Olbers; Carsten Eden

2013-08-01T23:59:59.000Z

51

A Semianalytical Solution to a Diffusion–Deposition–Resuspension Model of Local Contamination  

Science Conference Proceedings (OSTI)

This note describes a semianalytical solution to a diffusion–deposition–resuspension model. Calculations of the fate of a point contaminant show that the model performs well in representing the individual effects of advection, deposition, and ...

Yahui Zhuang

1998-03-01T23:59:59.000Z

52

Diffusion Follows Structure ¾ A Network Model of the Software  

Science Conference Proceedings (OSTI)

By conducting simulations, we show that the structure of the personal networks significantly influences the diffusion processes in network effect markets like the software market. Varying connectivity (number of links to other participants), the heterogeneity ...

Falk v. Westarp; Oliver Wendt

2000-01-01T23:59:59.000Z

53

Horizontal Momentum Diffusion in GCMs Using the Dynamic Smagorinsky Model  

Science Conference Proceedings (OSTI)

A dynamic version of Smagorinsky’s diffusion scheme is presented that is applicable for large-eddy simulations (LES) of the atmospheric dynamics. The approach is motivated (i) by the incompatibility of conventional hyperdiffusion schemes with the ...

Urs Schaefer-Rolffs; Erich Becker

2013-03-01T23:59:59.000Z

54

A GIS tool for modelling annual diffuse infiltration on a plot scale  

Science Conference Proceedings (OSTI)

ArcB is a GIS tool for modelling annual diffuse infiltration (R"P) from precipitation (P) on a plot scale that uses ArcObjects as the programming language to incorporate equations and boundary conditions for the water-balance consistency. Because detailed ... Keywords: ArcObjects, Diffuse infiltration, GIS, SE Spain, Semiarid climate

Salvador EspañA, Francisco J. Alcalá, ÁNgela Vallejos, Antonio Pulido-Bosch

2013-04-01T23:59:59.000Z

55

Boron diffusion and activation in polysilicon multilayer films for P+ MOS structure: Characterization and modeling  

Science Conference Proceedings (OSTI)

This work deals with in situ boron diffusion and activation in multilayer films: polysilicon (Poly1)/amorphous silicon (Poly2). These films are deposited by LPCVD technique. However, several heat treatments were carried in order to determine the optimal ... Keywords: Activation, Diffusion, Model, Polysilicon, SIMS profile

R. Mahamdi; L. Saci; F. Mansour; P. Temple-Boyer; E. Scheid; L. Jalabert

2009-01-01T23:59:59.000Z

56

Diffusion Bonding Aluminium Alloys and Composites: New Approaches and Modelling  

E-Print Network (OSTI)

certain materials. Some oxide films either dissolve in the bulk of the metal or decompose at the bonding temperature (e.g. those of many steels, copper, titanium, tantalum and zirconium), and so metal-to-metal contact can be readily established... to the diffusion bonding of all materials. Diffusion bonding of most metals is conducted under a vacuum of 10-3-10-5 mbar or in an inert atmosphere (normally dry nitrogen, argon or helium) in order to reduce detrimental oxidation of the faying surfaces. Bonding...

Shirzadi Ghoshouni, Amir Abbas

1998-07-10T23:59:59.000Z

57

Erratum: ``Nitrogen diffusion mechanism in the R2Fe17 lattice'' [Appl. Phys. Lett. 67, 208 (1995)  

E-Print Network (OSTI)

Erratum: ``Nitrogen diffusion mechanism in the R2Fe17 lattice'' [Appl. Phys. Lett. 67, 208 (1995 Center for Precision Manufacturing and Institute of Materials Science, University of Connecticut, Storrs concentration distribution in the hollow can be obtained by solving Eq. 8 whose solution is1 cf r,t cf0R r­R0 cf

Yang, De-Ping

58

A diffusion theory model for optimization calculations of cold neutron sources  

DOE Green Energy (OSTI)

This summary describes a simple two-group diffusion model of an infinite slab, liquid deuterium (LD/sub 2/) cold source. The simplicity of the model permits us to obtain an analytical solution from which we can deduce the reason for the optimum thickness based solely on diffusion type phenomena. Also, a second more sophisticated model is described, and the results compared to a deterministic transport calculation. The good (particularly qualitative) agreement between the results suggests that diffusion theory methods can be used in parametric and optimization studies in order to avoid the generally more expensive transport calculations. 5 refs., 1 fig.

Azmy, Y.Y.

1987-01-01T23:59:59.000Z

59

www.cepe.ethz.ch A Real Options Evaluation Model for the Diffusion Prospects of New Renewable Power Generation Technologies  

E-Print Network (OSTI)

www.cepe.ethz.ch A real options evaluation model for the diffusion prospects of new renewable power generation technologies

Gürkan Kumbaroglu; Reinhard Madlener; Mustafa Demirel; Gürkan Kumbaroglu; Reinhard Madlener; Mustafa Demirel

2004-01-01T23:59:59.000Z

60

Diffusion Experiments with a Global Discontinuous Galerkin Shallow-Water Model  

Science Conference Proceedings (OSTI)

A second-order diffusion scheme is developed for the discontinuous Galerkin (DG) global shallow-water model. The shallow-water equations are discretized on the cubed sphere tiled with quadrilateral elements relying on a nonorthogonal curvilinear ...

Ramachandran D. Nair

2009-10-01T23:59:59.000Z

Note: This page contains sample records for the topic "diffusion mechanisms 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

Effective Eddy Diffusivities Inferred from a Point Release Tracer in an Eddy-Resolving Ocean Model  

Science Conference Proceedings (OSTI)

This study uses tracer experiments in a global eddy-resolving ocean model to examine two diagnostic methods for inferring effective eddy isopycnic diffusivity from point release tracers. The first method is based on the growth rate of the area ...

Mei-Man Lee; A. J. George Nurser; Andrew C. Coward; Beverly A. de Cuevas

2009-04-01T23:59:59.000Z

62

The diffusion of photovoltaics : background, modeling and initial reaction of the agricultural - irrigation sector  

E-Print Network (OSTI)

This paper deals with the background, development and calibration of a model of innovation-diffusion, designed to help allocate government field test and demonstration resources in support of a photovoltaic technology ...

Lilien, Gary Louis

1978-01-01T23:59:59.000Z

63

The Relation between Baroclinic Adjustment and Turbulent Diffusion in the Two-Layer Model  

Science Conference Proceedings (OSTI)

Baroclinic adjustment and turbulent diffusion are two popular paradigms used to describe the eddy–mean flow closure in the two-layer model, with very different implications for the criticality of the system. Baroclinic adjustment postulates the ...

Pablo Zurita-Gotor

2007-04-01T23:59:59.000Z

64

Heterogeneous Correlation Modeling Based on the Wavelet Diagonal Assumption and on the Diffusion Operator  

Science Conference Proceedings (OSTI)

This article discusses several models for background error correlation matrices using the wavelet diagonal assumption and the diffusion operator. The most general properties of filtering local correlation functions, with wavelet formulations, are ...

Olivier Pannekoucke

2009-09-01T23:59:59.000Z

65

Spatial modeling and simulation of diffusion in nuclei of living cells  

Science Conference Proceedings (OSTI)

The mobility of fluorescently labelled molecules in the interphase nucleus has been increasingly employed to investigate the spatial organization of the interchromosomal space. We suggest an improved two-dimensional anisotropic diffusion model to address ...

Dietmar Volz; Martin Eigel; Chaitanya Athale; Peter Bastian; Harald Hermann; Constantin Kappel; Roland Eils

2004-05-01T23:59:59.000Z

66

Review of the Attributes and Performance of 10 Rural Diffusion Models  

Science Conference Proceedings (OSTI)

An American Meteorological Society committee, working cooperatively with the U.S. Environmental Protection Agency (EPA), has sponsored a peer review and evaluation of 10 rural diffusion models that are now used in regulatory procedures or have ...

Maynard E. Smith

1984-06-01T23:59:59.000Z

67

Modeling and Parameterization of Near-Source Diffusion in Weak Winds  

Science Conference Proceedings (OSTI)

A critical assessment is made of several different approaches that can be used for modeling near-source diffusion in weak winds, including the calm condition. For the convective boundary layer, the statistical theory approach is used in ...

S. Pal Arya

1995-05-01T23:59:59.000Z

68

The Control of Polar Haloclines by Along-Isopycnal Diffusion in Climate Models  

Science Conference Proceedings (OSTI)

Increasing the value of along-isopycnal diffusivity in a coupled model is shown to lead to enhanced stability of North Atlantic Deep Water (NADW) formation with respect to freshwater (FW) perturbations. This is because the North Atlantic (NA) ...

Willem P. Sijp; Matthew H. England

2009-02-01T23:59:59.000Z

69

Statistical Mechanics Model for Protein Folding  

E-Print Network (OSTI)

We present a novel statistical mechanics formalism for the theoretical description of the process of protein folding$\\leftrightarrow$unfolding transition in water environment. The formalism is based on the construction of the partition function of a protein obeying two-stage-like folding kinetics. Using the statistical mechanics model of solvation of hydrophobic hydrocarbons we obtain the partition function of infinitely diluted solution of proteins in water environment. The calculated dependencies of the protein heat capacities upon temperature are compared with the corresponding results of experimental measurements for staphylococcal nuclease and metmyoglobin.

Yakubovich, A V; Greiner, W

2010-01-01T23:59:59.000Z

70

Internet Resource Pricing Models, Mechanisms, and Methods  

E-Print Network (OSTI)

With the fast development of video and voice network applications, CDN (Content Distribution Networks) and P2P (Peer-to-Peer) content distribution technologies have gradually matured. How to effectively use Internet resources thus has attracted more and more attentions. For the study of resource pricing, a whole pricing strategy containing pricing models, mechanisms and methods covers all the related topics. We first introduce three basic Internet resource pricing models through an Internet cost analysis. Then, with the evolution of service types, we introduce several corresponding mechanisms which can ensure pricing implementation and resource allocation. On network resource pricing methods, we discuss the utility optimization in economics, and emphasize two classes of pricing methods (including system optimization and entities' strategic optimizations). Finally, we conclude the paper and forecast the research direction on pricing strategy which is applicable to novel service situation in the near future.

He, Huan; Liu, Ying

2011-01-01T23:59:59.000Z

71

The Diffuse Galactic Gamma-Ray Emission Model for GLAST LAT  

E-Print Network (OSTI)

Diffuse emission from the Milky Way dominates the gamma-ray sky. About 80% of the high-energy luminosity of the Milky Way comes from processes in the interstellar medium. The Galactic diffuse emission traces interactions of energetic particles, primarily protons and electrons, with the interstellar gas and radiation field, thus delivering information about cosmic-ray spectra and interstellar mass in distant locations. Additionally, the Galactic diffuse emission is the celestial foreground for the study of gamma-ray point sources and the extragalactic diffuse gamma-ray emission. We will report on the latest developments in the modelling of the Galactic diffuse emission, which will be used for the Gamma Ray Large Area Space Telescope (GLAST) investigations.

Porter, T A; Grenier, I A; Moskalenko, I V; Strong, A W

2007-01-01T23:59:59.000Z

72

The Diffuse Galactic Gamma-Ray Emission Model for GLAST LAT  

Science Conference Proceedings (OSTI)

Diffuse emission from the Milky Way dominates the gamma-ray sky. About 80% of the high-energy luminosity of the Milky Way comes from processes in the interstellar medium. The Galactic diffuse emission traces interactions of energetic particles, primarily protons and electrons, with the interstellar gas and radiation field, thus delivering information about cosmic-ray spectra and interstellar mass in distant locations. Additionally, the Galactic diffuse emission is the celestial foreground for the study of gamma-ray point sources and the extragalactic diffuse gamma-ray emission. We will report on the latest developments in the modeling of the Galactic diffuse emission, which will be used for the Gamma Ray Large Area Space Telescope (GLAST) investigations.

Porter, T.A.; /UC, Santa Cruz; Digel, S.W.; /SLAC /KIPAC, Menlo Park; Grenier, I.A.; /Saclay; Moskalenko, I.V.; /Stanford U., HEPL /KIPAC, Menlo Park; Strong, A.W.; /Garching, Max Planck Inst., MPE

2007-06-13T23:59:59.000Z

73

Quantum-Mechanical Model of Spacetime  

E-Print Network (OSTI)

We consider a possibility to construct a quantum-mechanical model of spacetime, where Planck size quantum black holes act as the fundamental constituents of space and time. Spacetime is assumed to be a graph, where black holes lie on the vertices. Our model implies that area has a discrete spectrum with equal spacing. At macroscopic length scales our model reproduces Einstein's field equation with a vanishing cosmological constant as a sort of thermodynamical equation of state of spacetime and matter fields. In the low temperature limit, where most black holes are assumed to be in the ground state, our model implies the Unruh and the Hawking effects, whereas in the high temperature limit we find, among other things, that black hole entropy depends logarithmically on the event horizon area, instead of being proportional to the area.

Makela, J

2007-01-01T23:59:59.000Z

74

Quantum-Mechanical Model of Spacetime  

E-Print Network (OSTI)

We consider a possibility to construct a quantum-mechanical model of spacetime, where Planck size quantum black holes act as the fundamental constituents of space and time. Spacetime is assumed to be a graph, where black holes lie on the vertices. Our model implies that area has a discrete spectrum with equal spacing. At macroscopic length scales our model reproduces Einstein's field equation with a vanishing cosmological constant as a sort of thermodynamical equation of state of spacetime and matter fields. In the low temperature limit, where most black holes are assumed to be in the ground state, our model implies the Unruh and the Hawking effects, whereas in the high temperature limit we find, among other things, that black hole entropy depends logarithmically on the event horizon area, instead of being proportional to the area.

Jarmo Makela

2007-01-24T23:59:59.000Z

75

Local Versus Nonlocal Boundary-Layer Diffusion in a Global Climate Model  

Science Conference Proceedings (OSTI)

The results of a local and a nonlocal scheme for vertical diffusion in the atmospheric boundary layer are compared within the context of a global climate model. The global model is an updated version of the NCAR Community Climate Model (CCM2). ...

A. A. M. Holtslag; B. A. Boville

1993-10-01T23:59:59.000Z

76

Using a Quasipotential Transformation for Modeling Diffusion Media inPolymer-Electrolyte Fuel Cells  

SciTech Connect

In this paper, a quasipotential approach along with conformal mapping is used to model the diffusion media of a polymer-electrolyte fuel cell. This method provides a series solution that is grid independent and only requires integration along a single boundary to solve the problem. The approach accounts for nonisothermal phenomena, two-phase flow, correct placement of the electronic potential boundary condition, and multilayer media. The method is applied to a cathode diffusion medium to explore the interplay between water and thermal management and performance, the impact of the rib-to-channel ratio, and the existence of diffusion under the rib and flooding phenomena.

Weber, Adam Z.; Newman, John

2008-08-29T23:59:59.000Z

77

Modeling diffusion of electrical appliances in the residential sector  

E-Print Network (OSTI)

and usage patterns, and because data sources covering these parameters are more scarce, modeling of household lighting

McNeil, Michael A.

2010-01-01T23:59:59.000Z

78

Mechanical Models of Fault-Related Folding  

SciTech Connect

The subject of the proposed research is fault-related folding and ground deformation. The results are relevant to oil-producing structures throughout the world, to understanding of damage that has been observed along and near earthquake ruptures, and to earthquake-producing structures in California and other tectonically-active areas. The objectives of the proposed research were to provide both a unified, mechanical infrastructure for studies of fault-related foldings and to present the results in computer programs that have graphical users interfaces (GUIs) so that structural geologists and geophysicists can model a wide variety of fault-related folds (FaRFs).

Johnson, A. M.

2003-01-09T23:59:59.000Z

79

Mathematical modeling of fluorescence diffuse optical imaging of cell membrane potential changes  

E-Print Network (OSTI)

The aim of this paper is to provide a mathematical model for spatial distribution of membrane electrical potential changes by fluorescence diffuse optical tomography. We derive the resolving power of the imaging method in the presence of measurement noise. The proposed mathematical model can be used for cell membrane tracking with the resolution of the optical microscope.

Habib Ammari; Josselin Garnier; Laure Giovangigli

2013-07-08T23:59:59.000Z

80

Modeling and rendering of heterogeneous translucent materials using the diffusion equation  

Science Conference Proceedings (OSTI)

In this article, we propose techniques for modeling and rendering of heterogeneous translucent materials that enable acquisition from measured samples, interactive editing of material attributes, and real-time rendering. The materials are assumed to ... Keywords: Appearance modeling and rendering, diffusion approximation, subsurface scattering

Jiaping Wang; Shuang Zhao; Xin Tong; Stephen Lin; Zhouchen Lin; Yue Dong; Baining Guo; Heung-Yeung Shum

2008-03-01T23:59:59.000Z

Note: This page contains sample records for the topic "diffusion mechanisms 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

A Joint-Diffused Inpainting Model for Underexposure Image Preserving the Linear Geometric Structure  

Science Conference Proceedings (OSTI)

To restore the underexposure image, an illumination compensation inpainting model which employs the joint-diffused partial differential equations (PDEs) is proposed. Firstly, the novel model compensates the illumination effect in multi-scaled underexposure ... Keywords: illumination compensation, image inpainting, partial differential equation (PDE), quotient image (QI)

Jiying Wu; Qiuqi Ruan; Gaoyun An

2009-01-01T23:59:59.000Z

82

Modeling diffusion of electrical appliances in the residential sector  

E-Print Network (OSTI)

Regression Results for Appliances Refrigerator Coefficientdiffusion of electrical appliances in the residential sectorfor modeling residential appliance uptake as a function of

McNeil, Michael A.

2010-01-01T23:59:59.000Z

83

Modeling lithium diffusion in nickel composite graphite Venkat R. Subramanian, Ping Yu, Branko N. Popov, Ralph E. White*  

E-Print Network (OSTI)

Modeling lithium diffusion in nickel composite graphite Venkat R. Subramanian, Ping Yu, Branko N. Exchange current and diffusion coef®cient for the lithium-diffusion are predicted. # 2001 Elsevier Science computers, and camcorders. The distinguished feature of lithium-ion batteries is the use of intercalation

Popov, Branko N.

84

Human walking model predicts joint mechanics, electromyography and mechanical economy  

E-Print Network (OSTI)

In this paper, we present an under-actuated model of human walking, comprising only a soleus muscle and flexion/extension monoarticular hip muscles. The remaining muscle groups of the human leg are modeled using quasi-passive, ...

Endo, Ken

85

South America Diffuse SR Solar Model from INPE and LABSOLAR  

Open Energy Info (EERE)

for Space Research) and the ARCVIEW software were used to produce the dataset and SHAPE files.
The assessment of reliability levels of the BRASIL-SR model were performed...

86

South America Diffuse SR Solar Model from INPE and LABSOLAR ...  

Open Energy Info (EERE)

for Space Research) and the ARCVIEW software were used to produce the dataset and SHAPE files.The assessment of reliability levels of the BRASIL-SR model were performed...

87

Covariance Localization with the Diffusion-Based Correlation Models  

Science Conference Proceedings (OSTI)

Improving the performance of ensemble filters applied to models with many state variables requires regularization of the covariance estimates by localizing the impact of observations on state variables. A covariance localization technique based on ...

Max Yaremchuk; Dmitry Nechaev

2013-02-01T23:59:59.000Z

88

Stellar Models with Microscopic Diffusion and Rotational Mixing I: Application to the Sun  

E-Print Network (OSTI)

The Yale stellar evolution code has been modified to include the combined effects of diffusion and rotational mixing on $^1$H, $^4$He and the trace elements $^3$He, $^6$Li, $^7$Li, and $^9$Be. The interaction between rotational mixing and diffusion is studied by calculating a number of calibrated solar models. The rotational mixing inhibits the diffusion in the outer parts of the models, leading to a decrease in the envelope diffusion by 25 -- 50\\%. Conversely, diffusion leads to gradients in mean molecular weight which can inhibit the rotational mixing. The degree to which gradients in mean molecular weight inhibits the rotational mixing is somewhat uncertain. A comparison to the observed solar oblateness suggests that gradients in the mean molecular weight play a smaller role in inhibiting the rotational mixing previously believed. This is reinforced by the fact that the model with the standard value for the inhibiting effect of mean molecular weight on the rotational mixing depletes no Li on the main sequence. This is in clear contrast to the observations. A reduction in the inhibiting effect of mean molecular weight gradients by a factor of ten leads to noticeable main sequence Li depletion.

Brian Chaboyer; P. Demarque; M. H. Pinsonneault

1994-08-17T23:59:59.000Z

89

Assessment of reduced mechanisms using One Dimensional Stochastic Turbulence model  

E-Print Network (OSTI)

Thermochemical information Semi-empirical methods Chemical kinetics information Detail chemical kinetics mechanism Transport model Transport parameters Computational simulation

Chien, Li-Chun

2010-01-01T23:59:59.000Z

90

Testing and modeling of diffusion bonded prototype optical windows under ITER conditions  

SciTech Connect

Glass-metal joints are a part of ITER optical diagnostics windows. These joints must be leak tight for the safety (presence of tritium in ITER) and to preserve the vacuum. They must also withstand the ITER environment: temperatures up to 220 deg.C and fast neutron fluxes of {approx}3.10{sup 9} n/cm{sup 2}.s. At the moment, little information is available about glass-metal joints suitable for ITER. Therefore, we performed mechanical and thermal tests on some prototypes of an aluminium diffusion bonded optical window. Finite element modeling with Abaqus code was used to understand the experimental results. The prototypes were helium leaking probably due to very tiny cracks in the interaction layer between the steel and the aluminium. However, they were all able to withstand a thermal cycling test up to 200 deg. C; no damage could be seen after the tests by visual inspection. The prototypes successfully passed push-out test with a 500 N load. During the destructive push-out tests the prototypes broke at a 6-12 kN load between the aluminium layer and the steel or the glass, depending on the surface quality of the glass. The microanalysis of the joints has also been performed. The finite element modeling of the push-out tests is in a reasonable agreement with the experiments. According to the model, the highest thermal stress is created in the aluminium layer. Thus, the aluminium joint seems to be the weakest part of the prototypes. If this layer is improved, it will probably make the prototype helium leak tight and as such, a good ITER window candidate. (authors)

Jacobs, M. [Flemish Inst. for Technological Research, Mol (Belgium); Van Oost, G. [Dept. of Applied Physics, Ghent Univ., Ghent (Belgium); Degrieck, J.; De Baere, I. [Dept. of Materials Science and Engineering, Ghent Univ., Ghent (Belgium); Gusarov, A. [Belgian Nuclear Research Center, Mol (Belgium); Gubbels, F. [TNO, Eindhoven (Netherlands); Massaut, V. [Belgian Nuclear Research Center, Mol (Belgium)

2011-07-01T23:59:59.000Z

91

Direct Solution Of The Implicit Formulation Of Fourth Order Horizontal Diffusion For Gridpoint Models On The Sphere  

E-Print Network (OSTI)

High order horizontal diffusion of the form Kr 2m is widely used in spectral models as a means of preventing energy accumulation at the shortest resolved scales. In the spectral context, an implicit formulation of such diffusion is trivial to implement. The present note describes an efficient method of implementing implicit high order diffusion in global finite difference models. The method expresses the high order diffusion equation as a sequence of equations involving r 2 . The solution is obtained by combining fast Fourier transforms in longitude with a finite difference solver for the second order ordinary differential equation in latitude. The implicit diffusion routine is suitable for use in any finite difference global model that uses a regular latitude/longitude grid. The absence of a restriction on the timestep makes it particularly suitable for use in semi-Lagrangian models. The scale selectivity of the high order diffusion gives it an advantage over the uncent...

Yong Li; J. Ray; Yong Li G S. Moorthi; J. Ray Bates

1994-01-01T23:59:59.000Z

92

Modeling diffusion of electrical appliances in the residential sector  

SciTech Connect

This paper presents a methodology for modeling residential appliance uptake as a function of root macroeconomic drivers. The analysis concentrates on four major energy end uses in the residential sector: refrigerators, washing machines, televisions and air conditioners. The model employs linear regression analysis to parameterize appliance ownership in terms of household income, urbanization and electrification rates according to a standard binary choice (logistic) function. The underlying household appliance ownership data are gathered from a variety of sources including energy consumption and more general standard of living surveys. These data span a wide range of countries, including many developing countries for which appliance ownership is currently low, but likely to grow significantly over the next decades as a result of economic development. The result is a 'global' parameterization of appliance ownership rates as a function of widely available macroeconomic variables for the four appliances studied, which provides a reliable basis for interpolation where data are not available, and forecasting of ownership rates on a global scale. The main value of this method is to form the foundation of bottom-up energy demand forecasts, project energy-related greenhouse gas emissions, and allow for the construction of detailed emissions mitigation scenarios.

McNeil, Michael A.; Letschert, Virginie E.

2009-11-22T23:59:59.000Z

93

Random matrix theory for modeling uncertainties in computational mechanics  

E-Print Network (OSTI)

Random matrix theory for modeling uncertainties in computational mechanics C. Soize Laboratory of Engineering Mechanics, University of Marne-la-Vall´ee, 5 boulevard Descartes, 77454 Marne-la-Vallée, France, e in computational mechanics. If data uncertainties can be modeled by parametric probabilistic methods, for a given

Paris-Sud XI, Université de

94

Modeling and Experimental Validation of Multiscale Mechanical ...  

Science Conference Proceedings (OSTI)

Jul 31, 2012 ... Jonathan Zimmerman, Sandia National Laboratories. Scope, The mechanical behavior of a material has a strong and complex connection to its ...

95

LANL: Mechanical testing and modeling in MST  

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

MST For information on mechanical testing in MST Division contact: Mark Bourke, bourke@lanl.gov Materials Science and Technology Division Facility Focus Materials Science and...

96

A Semigeostrophic Eady-Wave Frontal Model Incorporating Momentum Diffusion. Part II: Kinetic Energy and Enstrophy Dissipation  

Science Conference Proceedings (OSTI)

Momentum diffusion has been introduced into a semigeostrophic Eady-wave frontal model by Blumen (Part I). This model is used to determine the kinetic energy and enstrophy dissipations within a frontal zone that extends from the ground to a ...

William Blumen

1990-12-01T23:59:59.000Z

97

Coupled Thermal-Hydrological-Mechanical-Chemical Model and Experiments...  

Open Energy Info (EERE)

of Applications for Research, Development and Analysis of Geothermal Technologies Project Type Topic 2 Integrated Chemical, Thermal, Mechanical and Hydrological Modeling...

98

Mechanical Characterization and Modeling of Next-Generation Solid ...  

Science Conference Proceedings (OSTI)

Symposium, Energy Conversion/Fuel Cells. Presentation Title, Mechanical Characterization and Modeling of Next-Generation Solid Oxide Fuel Cells and Stacks.

99

A Hydro-Thermo-Mechanical Numerical Model For Hdr Geothermal...  

Open Energy Info (EERE)

Hydro-Thermo-Mechanical Numerical Model For Hdr Geothermal Reservoir Evaluation Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: A...

100

Access Control: Policies, Models, and Mechanisms  

Science Conference Proceedings (OSTI)

Access control is the process of mediating every request to resources and data maintained by a system and determining whether the request should be granted or denied. The access control decision is enforced by a mechanism implementing regulations established ...

Pierangela Samarati; Sabrina De Capitani di Vimercati

2000-09-01T23:59:59.000Z

Note: This page contains sample records for the topic "diffusion mechanisms 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

An Empirical Model of UO2 Thermal Conductivity Based on Laser Flash Measurements of Thermal Diffusivity  

Science Conference Proceedings (OSTI)

Thermal conductivity of irradiated fuel materials, which can be derived from measured thermal diffusivity (TD), is a key consideration in thermal performance and design of a fuel rod. However, without interpretation, the measured TD data cannot be used directly to calculate fuel temperatures during irradiation. This report provides such interpretation and presents an empirical model for the degradation of UO2 thermal conductivity with burn-up.

1998-10-07T23:59:59.000Z

102

Prediction of Soot Formation in Laminar Opposed Diffusion Flame with Detailed and Reduced Reaction Mechanisms .  

E-Print Network (OSTI)

??The present work focuses on a computational study of a simplified soot model to predict soot production and destruction in methane/oxidizer (O2 and N2) and… (more)

Chang, Hojoon

2004-01-01T23:59:59.000Z

103

Modeling experimental results of diffusion of alkaline solutions through a compacted bentonite barrier  

SciTech Connect

The interaction between concrete/cement and swelling clay (bentonite) has been modeled in the context of engineered barrier systems for deep geological disposal of high-level radioactive waste. The geochemical transformations observed in laboratory diffusion experiments at 60 and 90 {sup o}C between bentonite and different high-pH solutions (K-Na-OH and Ca(OH){sub 2}-saturated) were reconciled with the reactive transport code CrunchFlow. For K-Na-OH solutions (pH = 13.5 at 25 {sup o}C) partial dissolution of montmorillonite and precipitation of Mg-silicates (talc-like), hydrotalcite and brucite at the interface are predicted at 60 {sup o}C, while at 90 {sup o}C the alteration is wider. Alkaline cations diffused beyond the mineralogical alteration zone by means of exchange with Mg{sup 2+} in the interlayer region of montmorillonite. Very slow reactivity and minor alteration of the clay are predicted in the Ca(OH){sub 2}-bentonite system. The model is a reasonable description of the experiments but also demonstrates the difficulties in modeling processes operating at a small scale under a diffusive regime.

Fernandez, Raul, E-mail: raul.fernandez@ietcc.csic.e [Instituto Eduardo Torroja de Ciencias de la Construccion (CSIC), C/Serrano Galvache, 4, 28033 Madrid (Spain); Institut fuer Geologie, Universitaet Bern, Baltzerstrasse 3, CH-3012 Bern (Switzerland); Cuevas, Jaime [Dpto. Geologia y Geoquimica, Facultad de Ciencias, Universidad Autonoma de Madrid, Campus Cantoblanco, 28049 Madrid (Spain); Maeder, Urs K. [Institut fuer Geologie, Universitaet Bern, Baltzerstrasse 3, CH-3012 Bern (Switzerland)

2010-08-15T23:59:59.000Z

104

Stellar Models with Microscopic Diffusion and Rotational Mixing II: Application to Open Clusters  

E-Print Network (OSTI)

Stellar models with masses ranging from 0.5 to $1.3~M_\\odot$ were constructed in order to compare to young cluster observations of Li and of rotation velocities. The amount of Li depletion in cool stars is sensitive to the amount of overshoot at the base of the surface convection zone, and the exact metallicity of the models. Even when this uncertainty is taken into account, the Li observations are a severe constraint for the models and rule out standard models, and pure diffusion models. Stellar models which include diffusion and rotational mixing in the radiative regions of stars are able to simultaneously match the Li abundances observed in the Pleiades, UMaG, Hyades, Praesepe, NGC 752 and M67. They also match the observed rotation periods in the Hyades. However, these models are unable to simultaneously explain the presence of the rapidly rotating late G and K stars in the Pleiades and the absence of rapidly rotating late F and early G stars.

Brian Chaboyer; P. Demarque; M. H. Pinsonneault

1994-08-17T23:59:59.000Z

105

A model for the directional distribution of the diffuse sky radiance with an application to a CPC collector  

SciTech Connect

The development of a new, semi-empirical model for the directional distribution of the diffuse radiance is reported. The proposed regression-type model, with the form of its base functions obtained from physical principles, is based on a combination of the purely physical reasoning approach and the purely empirical approach. Direct multiple-scattering calculations are circumvented through the use of the method of successive orders of scattering. The model is calibrated for the mean diffuse radiance estimated under all sky conditions reported in a large and comprehensive diffuse radiance data set. It is found that only a small increase in accuracy is gained by including higher orders of scattering, and this increase does not justify the complexity of the resulting model. Therefore, the single scattering approximation is recommended. The use of the model is illustrated in a typical application, in which the fraction of diffuse radiation intercepted by the receive of a compound parabolic concentrator is computed.

Siala, F.M.F. (Center for Solar Energy Studies, Tripoli (Libya)); Hooper, F.C. (Univ. of Toronto, Ontario (Canada))

1990-01-01T23:59:59.000Z

106

Integrated Chemical, Thermal, Mechanical and Hydrological Modeling...  

Open Energy Info (EERE)

489,476 1,602,500 Retrieved from "http:en.openei.orgwindex.php?titleIntegratedChemical,Thermal,MechanicalandHydrologicalModeling&oldid313283" Category:...

107

Modeling torque versus speed, shot noise, and rotational diffusion of the bacterial flagellar motor  

E-Print Network (OSTI)

We present a minimal physical model for the flagellar motor that enables bacteria to swim. Our model explains the experimentally measured torque-speed relationship of the proton-driven E. coli motor at various pH and temperature conditions. In particular, the dramatic drop of torque at high rotation speeds (the "knee") is shown to arise from saturation of the proton flux. Moreover, we show that shot noise in the proton current dominates the diffusion of motor rotation at low loads. This suggests a new way to probe the discreteness of the energy source, analogous to measurements of charge quantization in superconducting tunnel junctions.

Thierry Mora; Howard Yu; Ned S. Wingreen

2009-10-05T23:59:59.000Z

108

A GENERALIZED MODEL OF NONLINEAR DIFFUSIVE SHOCK ACCELERATION COUPLED TO AN EVOLVING SUPERNOVA REMNANT  

Science Conference Proceedings (OSTI)

To better model the efficient production of cosmic rays (CRs) in supernova remnants (SNRs) with the associated coupling between CR production and SNR dynamics, we have generalized an existing cr-hydro-NEI code to include the following processes: (1) an explicit calculation of the upstream precursor structure including the position-dependent flow speed, density, temperature, and magnetic field strength; (2) a momentum- and space-dependent CR diffusion coefficient; (3) an explicit calculation of magnetic field amplification; (4) calculation of the maximum CR momentum using the amplified magnetic field; (5) a finite Alfven speed for the particle scattering centers; and (6) the ability to accelerate a superthermal seed population of CRs, as well as the ambient thermal plasma. While a great deal of work has been done modeling SNRs, most work has concentrated on either the continuum emission from relativistic electrons or ions or the thermal emission from the shock heated plasma. Our generalized code combines these elements and describes the interplay between CR production and SNR evolution, including the nonlinear coupling of efficient diffusive shock acceleration, based mainly on the work of P. Blasi and coworkers, and a non-equilibrium ionization (NEI) calculation of thermal X-ray line emission. We believe that our generalized model will provide a consistent modeling platform for SNRs, including those interacting with molecular clouds, and improve the interpretation of current and future observations, including the high-quality spectra expected from Astro-H. SNR RX J1713.7-3946 is modeled as an example.

Lee, Shiu-Hang; Nagataki, Shigehiro [Yukawa Institute for Theoretical Physics, Kyoto University, Oiwake-cho Kitashirakawa, Sakyo-ku, Kyoto 606-8502 (Japan); Ellison, Donald C., E-mail: lee@yukawa.kyoto-u.ac.jp, E-mail: nagataki@yukawa.kyoto-u.ac.jp, E-mail: don_ellison@ncsu.edu [Physics Department, North Carolina State University, Box 8202, Raleigh, NC 27695 (United States)

2012-05-10T23:59:59.000Z

109

Measuring Diffusivity in Supercooled Liquid Nanoscale Films using Inert Gas Permeation: I. Kinetic Model and Scaling Methods  

DOE Green Energy (OSTI)

We describe in detail a diffusion model used to simulate inert gas transport through supercooled liquid overlayers. In recent work, the transport of the inert gas has been shown to be an effective probe of the diffusivity of supercooled liquid methanol in the experimentally challenging regime near the glass transition temperature. The model simulations accurately and quantitatively describe the inert gas permeation desorption spectra. The simulation results are used to validate universal scaling relationships between the diffusivity, overlayer thickness, and the temperature ramp rate for isothermal and temperature programmed desorption. From these scaling relationships we derive simple equations from which the diffusivity can be obtained using the peak desorption time or temperature for an isothermal or set of TPD experiments respectively without numerical simulation. The results presented here demonstrate that the permeation of gases through amorphous overlayers has the potential to be a powerful technique to obtain diffusivity data in deeply supercooled liquids.

Smith, R. Scott; Matthiesen, Jesper; Kay, Bruce D.

2010-11-07T23:59:59.000Z

110

Impact of Isopycnal Diffusion on Heat Fluxes and the Transient Response of a Two-Dimensional Ocean Model  

Science Conference Proceedings (OSTI)

A two-dimensional (latitude–depth) ocean–climate model is used to assess the impact of calculating diffusive heat and salinity fluxes along and across isopycnal surfaces rather than in a vertical–horizontal coordinate system. Differences between ...

L. D. Danny Harvey

1995-09-01T23:59:59.000Z

111

A Diagnosis of the Asymmetry in Top-Down and Bottom-Up Diffusion Using a Lagrangian Stochastic Model  

Science Conference Proceedings (OSTI)

A Lagrangian stochastic model of particle trajectories is used to investigate the asymmetry in vertical diffusion from area sources at the bottom and top of an inhomogeneous turbulent boundary layer. Such an asymmetry was discovered in the large-...

J. C. Weil

1990-02-01T23:59:59.000Z

112

Modeling heat conduction and radiation transport with the diffusion equation in  

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

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

113

Pyrolysis mechanisms of lignin model compounds  

DOE Green Energy (OSTI)

The flash vacuum pyrolysis of lignin model compounds was studied under conditions optimized for the production of liquid products to provide mechanistic insight into the reaction pathways that lead to product formation. The major reaction products can be explained by cleavage of the C-O either linkage by a free radial or concerted 1,2-elimination.

Britt, P.F.; Buchanan, A.C. III; Cooney, M.J.

1997-06-01T23:59:59.000Z

114

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

SciTech Connect

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

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

2011-05-15T23:59:59.000Z

115

A numerical method for solving convection-reaction-diffusion multivalued equations in fire spread modelling  

Science Conference Proceedings (OSTI)

A numerical method is developed for fire spread simulation modelling. The two-dimensional surface model presented takes into account moisture content, radiation, wind and slope effects, which are by far the most important mechanisms in fire spread. We ... Keywords: 02.60.Cb, 02.60.Lj, 02.70.Dh, Fire, Moisture, Pyrolysis, Radiation, Slope, Wind

L. Ferragut; M. I. Asensio; S. Monedero

2007-06-01T23:59:59.000Z

116

Ising-like agent-based technology diffusion model: adoption patterns vs. seeding strategies  

E-Print Network (OSTI)

The well-known Ising model used in statistical physics was adapted to a social dynamics context to simulate the adoption of a technological innovation. The model explicitly combines (a) an individual's perception of the advantages of an innovation and (b) social influence from members of the decision-maker's social network. The micro-level adoption dynamics are embedded into an agent-based model that allows exploration of macro-level patterns of technology diffusion throughout systems with different configurations (number and distributions of early adopters, social network topologies). In the present work we carry out many numerical simulations. We find that when the gap between the individual's perception of the options is high, the adoption speed increases if the dispersion of early adopters grows. Another test was based on changing the network topology by means of stochastic connections to a common opinion reference (hub), which resulted in an increment in the adoption speed. Finally, we performed a simula...

Laciana, Carlos E

2010-01-01T23:59:59.000Z

117

Sampling Conditioned Hypoelliptic Diffusions  

E-Print Network (OSTI)

A series of recent articles introduced a method to construct stochastic partial differential equations (SPDEs) which are invariant with respect to the distribution of a given conditioned diffusion. These works are restricted to the case of elliptic diffusions where the drift has a gradient structure, and the resulting SPDE is of second order parabolic type. The present article extends this methodology to allow the construction of SPDEs which are invariant with respect to the distribution of a class of hypoelliptic diffusion processes, subject to a bridge conditioning. This allows the treatment of more realistic physical models, for example one can use the resulting SPDE to study transitions between meta-stable states in mechanical systems with friction and noise. In this situation the restriction of the drift being a gradient can also be lifted.

Hairer, Martin; Voss, Jochen

2009-01-01T23:59:59.000Z

118

Model Development for Atomic Force Microscope Stage Mechanisms  

E-Print Network (OSTI)

Model Development for Atomic Force Microscope Stage Mechanisms Ralph C. Smith and Andrew G. Hatch of the Philippines Virginia Commonwealth University Diliman, Quezon City 1101 Richmond VA 23284 rcdelros titanate (PZT) devices employed in atomic force microscope stage mechanisms. We focus specifically on PZT

119

Albedo Feedback, the Meridional Structure of the Effective Heat Diffusivity, and Climatic Sensitivity: Results from Dynamic and Diffusive Models  

Science Conference Proceedings (OSTI)

The sensitivity of a two-level primitive equation atmospheric model to solar constant perturbations is examined in the presence of surface albedo feedback. The model is simplified to the point that a large number of numerical experiments can be ...

Isaac M. Held; David I. Linder; Max J. Suarez

1981-09-01T23:59:59.000Z

120

A mechanical model for Fourier's law of heat conduction  

E-Print Network (OSTI)

Nonequilibrium statistical mechanics close to equilibrium is a physically satisfactory theory centered on the linear response formula of Green-Kubo. This formula results from a formal first order perturbation calculation without rigorous justification. A rigorous derivation of Fourier's law for heat conduction from the laws of mechanics remains thus a major unsolved problem. In this note we present a deterministic mechanical model of a heat-conducting chain with nontrivial interactions, where kinetic energy fluctuations at the nodes of the chain are removed. In this model the derivation of Fourier's law can proceed rigorously.

David Ruelle

2011-02-27T23:59:59.000Z

Note: This page contains sample records for the topic "diffusion mechanisms 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

A Consistent Diffusion–Dissipation Parameterization in the ECHAM Climate Model  

Science Conference Proceedings (OSTI)

The diffusion–dissipation parameterizations usually adopted in GCMs are not physically consistent. Horizontal momentum diffusion, applied in the form of a hyperdiffusion, does not conserve angular momentum and the associated dissipative heating ...

Ulrike Burkhardt; Erich Becker

2006-04-01T23:59:59.000Z

122

A diffusion-kinetic model for pulverized-coal combustion and heat-and-mass transfer in a gas stream  

SciTech Connect

A diffusion-kinetic model for pulverized-coal combustion and heat-and-mass transfer in a gas stream is proposed, and the results of numerical simulation of the burnout dynamics of Kansk-Achinsk coals in the pulverized state at different treatment conditions and different model parameters are presented. The mathematical model describes the dynamics of thermochemical conversion of solid organic fuels with allowance for complex physicochemical phenomena of heat-and-mass exchange between coal particles and the gaseous environment.

E.A. Boiko; S.V. Pachkovskii [Polytechnic Institute, Federal University of Siberia, Krasnoyarsk (Russian Federation)

2008-12-15T23:59:59.000Z

123

Facilitated diffusion of proteins on chromatin  

E-Print Network (OSTI)

We present a theoretical model of facilitated diffusion of proteins in the cell nucleus. This model, which takes into account the successive binding/unbinding events of proteins to DNA, relies on a fractal description of the chromatin which has been recently evidenced experimentally. Facilitated diffusion is shown quantitatively to be favorable for a fast localization of a target locus by a transcription factor, and even to enable the minimization of the search time by tuning the affinity of the transcription factor with DNA. This study shows the robustness of the facilitated diffusion mechanism, invoked so far only for linear conformations of DNA.

O. Benichou; C. Chevalier; B. Meyer; R. Voituriez

2010-06-24T23:59:59.000Z

124

Coupled Thermal-Chemical-Mechanical Modeling of Validation Cookoff Experiments  

DOE Green Energy (OSTI)

The cookoff of energetic materials involves the combined effects of several physical and chemical processes. These processes include heat transfer, chemical decomposition, and mechanical response. The interaction and coupling between these processes influence both the time-to-event and the violence of reaction. The prediction of the behavior of explosives during cookoff, particularly with respect to reaction violence, is a challenging task. To this end, a joint DoD/DOE program has been initiated to develop models for cookoff, and to perform experiments to validate those models. In this paper, a series of cookoff analyses are presented and compared with data from a number of experiments for the aluminized, RDX-based, Navy explosive PBXN-109. The traditional thermal-chemical analysis is used to calculate time-to-event and characterize the heat transfer and boundary conditions. A reaction mechanism based on Tarver and McGuire's work on RDX{sup 2} was adjusted to match the spherical one-dimensional time-to-explosion data. The predicted time-to-event using this reaction mechanism compares favorably with the validation tests. Coupled thermal-chemical-mechanical analysis is used to calculate the mechanical response of the confinement and the energetic material state prior to ignition. The predicted state of the material includes the temperature, stress-field, porosity, and extent of reaction. There is little experimental data for comparison to these calculations. The hoop strain in the confining steel tube gives an estimation of the radial stress in the explosive. The inferred pressure from the measured hoop strain and calculated radial stress agree qualitatively. However, validation of the mechanical response model and the chemical reaction mechanism requires more data. A post-ignition burn dynamics model was applied to calculate the confinement dynamics. The burn dynamics calculations suffer from a lack of characterization of the confinement for the flaw-dominated failure mode experienced in the tests. High-pressure burning rates are needed for more detailed post-ignition studies. Sub-models for chemistry, mechanical response and burn dynamics need to be validated against data from less complex experiments. The sub-models can then be used in integrated analysis for comparison with experimental data taken during integrated tests.

ERIKSON,WILLIAM W.; SCHMITT,ROBERT G.; ATWOOD,A.I.; CURRAN,P.D.

2000-11-27T23:59:59.000Z

125

Notes 01. Modeling of mechanical (lumped parameter) elements  

E-Print Network (OSTI)

Fundamental elements in mechanical systems: inertias, stiffness and damping elements. Equivalent spring coefficients and associated potential energy. Equivalent mass or inertia coefficients and associated kinetic energy. Equations of motion of a rigid body in a plane. Equivalent damping coefficients and associated dissipation energy. Types of damping models (linear or viscous and nonlinear).

San Andres, Luis

2008-01-01T23:59:59.000Z

126

Performance modelling of the Orwell basic access mechanism  

Science Conference Proceedings (OSTI)

Orwell is a high speed slotted ring. Its protocol uses destination release of the slots. Because of this the carried load can be much larger than the transmission rate. A new analytical model of the Orwell basic access mechanism is presented in this ...

M. Zafirovic; I. G. Niemegeers

1987-08-01T23:59:59.000Z

127

Computational mechanical modeling of the behavior of carbon nanotubes  

Science Conference Proceedings (OSTI)

This paper presents a computational method for the mechanical simulation of carbon nanotubes, whose complexity is linear on the number of atoms. The regularity of a graphene lattice at its energy ground permits the definition of a tiling scheme that ... Keywords: carbon nanotubes, computational method, mathematical modeling, molecular dynamics, numerical simulation

Maria Morandi Cecchi; Alberto Giovanni Busetto

2007-08-01T23:59:59.000Z

128

Thesis A Numerical Model of Hydro-Thermo- Mechanical Coupling...  

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

1 31 53-T Thesis A Numerical Model of Hydro-Thermo- Mechanical Coupling in a Fractured Rock Mass ECEIVED Los Alamos N A T I O N A L L A B O R A T O R Y Los Alamos National...

129

Mechanical modeling of porous oxide fuel pellet A Test Problem  

Science Conference Proceedings (OSTI)

A poro-elasto-plastic material model has been developed to capture the response of oxide fuels inside the nuclear reactors under operating conditions. Behavior of the oxide fuel and variation in void volume fraction under mechanical loading as predicted by the developed model has been reported in this article. The significant effect of void volume fraction on the overall stress distribution of the fuel pellet has also been described. An important oxide fuel issue that can have significant impact on the fuel performance is the mechanical response of oxide fuel pellet and clad system. Specifically, modeling the thermo-mechanical response of the fuel pellet in terms of its thermal expansion, mechanical deformation, swelling due to void formation and evolution, and the eventual contact of the fuel with the clad is of significant interest in understanding the fuel-clad mechanical interaction (FCMI). These phenomena are nonlinear and coupled since reduction in the fuel-clad gap affects thermal conductivity of the gap, which in turn affects temperature distribution within the fuel and the material properties of the fuel. Consequently, in order to accurately capture fuel-clad gap closure, we need to account for fuel swelling due to generation, retention, and evolution of fission gas in addition to the usual thermal expansion and mechanical deformation. Both fuel chemistry and microstructure also have a significant effect on the nucleation and growth of fission gas bubbles. Fuel-clad gap closure leading to eventual contact of the fuel with the clad introduces significant stresses in the clad, which makes thermo-mechanical response of the clad even more relevant. The overall aim of this test problem is to incorporate the above features in order to accurately capture fuel-clad mechanical interaction. Because of the complex nature of the problem, a series of test problems with increasing multi-physics coupling features, modeling accuracy, and complexity are defined with the objective of accurate simulation of fuel-clad mechanical interaction subjected to a wide-range of thermomechanical stimuli.

Nukala, Phani K [ORNL; Barai, Pallab [ORNL; Simunovic, Srdjan [ORNL; Ott, Larry J [ORNL

2009-10-01T23:59:59.000Z

130

Trust and multi-agent systems: applying the "diffuse, default model" of trust to experiments involving artificial agents  

Science Conference Proceedings (OSTI)

We argue that the notion of trust, as it figures in an ethical context, can be illuminated by examining research in artificial intelligence on multi-agent systems in which commitment and trust are modeled. We begin with an analysis of a philosophical ... Keywords: Artificial agents, Default trust, Diffuse trust, Multi-agent systems, Trust

Jeff Buechner; Herman T. Tavani

2011-03-01T23:59:59.000Z

131

A Unified Model for Moist Convective Boundary Layers Based on a Stochastic Eddy-Diffusivity/Mass-Flux Parameterization  

Science Conference Proceedings (OSTI)

A single-column model (SCM) is developed for representing moist convective boundary layers. The key component of the SCM is the parameterization of subgrid-scale vertical mixing, which is based on a stochastic eddy-diffusivity/mass-flux (EDMF) ...

Kay Sušelj; João Teixeira; Daniel Chung

2013-07-01T23:59:59.000Z

132

Quasi-Steady Analysis of a PBL Model with an Eddy-Diffusivity Profile and Nonlocal Fluxes  

Science Conference Proceedings (OSTI)

Analytic solutions to a planetary boundary layer (PBL) model with an eddy-diffusivity profile (i.e., a K profile) and nonlocal fluxes are presented for the quasi-steady regime. The solutions demonstrate how different processes contribute to the ...

Bjorn Stevens

2000-03-01T23:59:59.000Z

133

Numerical identification of parameters for a strongly degenerate convection--diffusion problem modelling centrifugation of flocculated suspensions  

Science Conference Proceedings (OSTI)

This paper presents the identification of parameters in the flux and diffusion functions for a quasilinear strongly degenerate parabolic equation which models the centrifugation of flocculated suspensions. We consider both a rotating tube and a basket ... Keywords: Degenerate parabolic differential equation, Inverse problem, Numerical methods

S. Berres; R. Bürger; A. Coronel; M. Sepúlveda

2005-03-01T23:59:59.000Z

134

Electromagnetic Nature of Thermo-Mechanical Mass-Energy Transfer Due to Photon Diffusive Re-Emission and  

E-Print Network (OSTI)

mass-transfer trough material systems involved, from a mass-energy source to a sink system. Otherwise- contact" diffusive re-emission and propagation) and commensurate mass-transfer trough material systems conduction theory (parabolic difference equation), allowing infinite speed of thermal energy propagation (i

Kostic, Milivoje M.

135

Differences in the mechanics of information diffusion across topics: idioms, political hashtags, and complex contagion on twitter  

Science Conference Proceedings (OSTI)

There is a widespread intuitive sense that different kinds of information spread differently on-line, but it has been difficult to evaluate this question quantitatively since it requires a setting where many different kinds of information spread in a ... Keywords: information diffusion, social contagion, social media

Daniel M. Romero; Brendan Meeder; Jon Kleinberg

2011-03-01T23:59:59.000Z

136

Implementing and assessing computational modeling in introductory mechanics  

E-Print Network (OSTI)

Students taking introductory physics are rarely exposed to computational modeling. In a one-semester large lecture introductory calculus-based mechanics course at Georgia Tech, students learned to solve physics problems using the VPython programming environment. During the term 1357 students in this course solved a suite of fourteen computational modeling homework questions delivered using an online commercial course management system. Their proficiency with computational modeling was evaluated in a proctored environment using a novel central force problem. The majority of students (60.4%) successfully completed the evaluation. Analysis of erroneous student-submitted programs indicated that a small set of student errors explained why most programs failed. We discuss the design and implementation of the computational modeling homework and evaluation, the results from the evaluation and the implications for instruction in computational modeling in introductory STEM courses.

Caballero, Marcos D; Schatz, Michael F

2011-01-01T23:59:59.000Z

137

Mechanical properties and modeling of seal-forming lithologies  

Science Conference Proceedings (OSTI)

Specific goals and accomplishments of this research include: (1) The evaluation of models of salt diaper ascent that involve either power law, dislocation creep as determined experimentally by Horseman et al. (1993) or linear, fluid-assisted creep as reported by Spiers et al. (1988, 1990, 1992). We have compared models assuming these two, experimentally evaluated flow laws and examined the predictions they make regarding diaper incubation periods, ascent velocities, deviatoric stresses and strain rates. (2) The evaluation of the effects of differential loading on the initiation an of salt structures. (3) Examination of the role of basement faults on the initiation and morphologic evolution of salt structures. (4) Evaluation of the mechanical properties of shale as a function of pressure and determination of the nature of its brittle-ductile transition. (5) Evaluation of the mechanical anisotropies of shales with varying concentrations, distributions and preferred orientations of clay. (6) The determination of temperature and ratedependencies of strength for a shale constitutive model that can be used in numerical models that depend on viscous formulations. (7) Determination of the mechanisms of deformation for argillaceous rocks over awide range of conditions. (8) Evaluation of the effects of H[sub 2]O within clay interlayers, as adsorbed surface layers.

Kronenberg, A.K.; Russell, J.E.; Carter, N.L.; Mazariegos, R.; Ibanez, W.

1993-01-01T23:59:59.000Z

138

Relativistic diffusion  

E-Print Network (OSTI)

We discuss a relativistic diffusion in the proper time in an approach of Schay and Dudley. We derive (Langevin) stochastic differential equations in various coordinates.We show that in some coordinates the stochastic differential equations become linear. We obtain momentum probability distribution in an explicit form.We discuss a relativistic particle diffusing in an external electromagnetic field. We solve the Langevin equations in the case of parallel electric and magnetic fields. We derive a kinetic equation for the evolution of the probability distribution.We discuss drag terms leading to an equilibrium distribution.The relativistic analog of the Ornstein-Uhlenbeck process is not unique. We show that if the drag comes from a diffusion approximation to the master equation then its form is strongly restricted. The drag leading to the Tsallis equilibrium distribution satisfies this restriction whereas the one of the Juettner distribution does not. We show that any function of the relativistic energy can be the equilibrium distribution for a particle in a static electric field. A preliminary study of the time evolution with friction is presented. It is shown that the problem is equivalent to quantum mechanics of a particle moving on a hyperboloid with a potential determined by the drag. A relation to diffusions appearing in heavy ion collisions is briefly discussed.

Z. Haba

2008-09-08T23:59:59.000Z

139

Telegraph-type versus diffusion-type models of turbulent relative dispersion  

E-Print Network (OSTI)

Properties of two equations describing the evolution of the probability density function (PDF) of the relative dispersion in turbulent flow are compared by investigating their solutions: the Richardson diffusion equation with the drift term and the self-similar telegraph equation derived by Ogasawara and Toh [J. Phys. Soc. Jpn. 75, 083401 (2006)]. The solution of the self-similar telegraph equation vanishes at a finite point, which represents persistent separation of a particle pair, while that of the Richardson equation extends infinitely just after the initial time. Each equation has a similarity solution, which is found to be an asymptotic solution of the initial value problem. The time lag has a dominant effect on the relaxation process into the similarity solution. The approaching time to the similarity solution can be reduced by advancing the time of the similarity solution appropriately. Batchelor scaling, a scaling law relevant to initial separation, is observed only for the telegraph case. For both models, we estimate the Richardson constant, based on their similarity solutions.

Kentaro Kanatani; Takeshi Ogasawara; Sadayoshi Toh

2007-11-10T23:59:59.000Z

140

Effective Diffusion-Medium Thickness for Simplified Polymer-Electrolyte-Fuel-Cell Modeling  

SciTech Connect

In this manuscript, conformal mapping is applied to a rib/channel domain of a polymer-electrolyte-fuel-cell diffusion medium. The analysis leads to the calculation of an effective diffusion-medium thickness, which can subsequently be used in 1-D simulations to account for the average rib/channel 2-D geometric effect. Extensions of the analysis to anisotropic and multilayer diffusion media are also given. Both equations and figures show the impact on a given variable at the catalyst layer of having a combined conducting/nonconducting boundary across from it.

Weber, Adam; Weber, Adam Z.

2008-07-30T23:59:59.000Z

Note: This page contains sample records for the topic "diffusion mechanisms 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

An Improved Method for Computing Horizontal Diffusion in a Sigma-Coordinate Model and Its Application to Simulations over Mountainous Topography  

Science Conference Proceedings (OSTI)

A set of modifications is presented to reduce the unphysical impact of horizontal diffusion in numerical models with a terrain-following sigma-coordinate system. At model levels sufficiently far away from the ground, vertical interpolation is ...

Günther Zängl

2002-05-01T23:59:59.000Z

142

Simple Solar Spectral Model for Direct and Diffuse Irradiance on Horizontal and Tilted Planes at the Earth's Surface for Cloudless Atmospheres  

Science Conference Proceedings (OSTI)

In a previous work, we described a simple model for calculating direct normal and diffuse horizontal spectral solar irradiance for cloudless sky conditions. In this paper, we present a new simple model (SPCTRAL2) that incorporates improvements to ...

Richard E. Bird; Carol Riordan

1986-01-01T23:59:59.000Z

143

Stochastic Integration for the Heterogeneous Correlation Modeling Using a Diffusion Equation  

Science Conference Proceedings (OSTI)

In this note, a stochastic integration scheme is proposed as an alternative to a deterministic integration scheme, usually employed for the diffusion operator in data assimilation. The stochastic integration scheme is no more than a simple ...

Olivier Pannekoucke; Laurent Vezard

2010-08-01T23:59:59.000Z

144

Use of Eulerian initial conditions in a Lagrangian model of turbulent diffusion  

SciTech Connect

Simple analytic solutions were obtained for relative diffusion and meandering of puffs and plumes based upon the random-force theory of turbulent diffusion. These solutions assume that the initial velocities of the tracer particles are identical to the turbulent field velocities at the source location. The spatial and temporal correlation of these velocities are, therefore, determined by the Eulerian space-time autocorrelation function, and the appropriate ensemble averages can be calculated if this correlation function is known. These solutions exhibit many of the known features of relative diffusion and are in general agreement with similarity theory for the inertial subrange. The solutions are presented in dimensionless form and are applicable to turbulent diffusion on any scale. To apply these results to actual experiments, the magnitude of the Eulerian integral length scale L and the Eulerian and Lagrangian integral time scale t/sub E/ and t/sub L/ must be known. These can be determined only from experimental data.

Lee, J.T.; Stone, G.L.

1983-01-01T23:59:59.000Z

145

MODELLING OF BURNING AND EXTINCTION CHARACTERISTICS OF A POLYMER DIFFUSION FLAME AND COMPARISON WITH EXPERIMENT  

E-Print Network (OSTI)

and Seshadri, K. : Combustion and Flame, 26, 363, 1976. ActaD.P. and Prahl, J.M. : and Flame 33, 55, 1978. Burke, S.P.OF A POLYMER DIFFUSION FLAME AND COMPARISON WITH EXPERIMENT

Pitz, W.J.

2012-01-01T23:59:59.000Z

146

A Hydro-mechanical Model and Analytical Solutions for Geomechanical Modeling of Carbon Dioxide Geological Sequestration  

SciTech Connect

We present a hydro-mechanical model for geological sequestration of carbon dioxide. The model considers the poroelastic effects by taking into account the coupling between the geomechanical response and the fluid flow in greater detail. The simplified hydro-mechanical model includes the geomechanical part that relies on the linear elasticity, while the fluid flow is based on the Darcy’s law. Two parts were coupled using the standard linear poroelasticity. Analytical solutions for pressure field were obtained for a typical geological sequestration scenario. The model predicts the temporal and spatial variation of pressure field and effects of permeability and elastic modulus of formation on the fluid pressure distribution.

Xu, Zhijie; Fang, Yilin; Scheibe, Timothy D.; Bonneville, Alain HR

2012-05-15T23:59:59.000Z

147

Mechanical properties and modeling of seal-forming lithologies  

Science Conference Proceedings (OSTI)

The goal of this research is to evaluate the roles of deformation and the occurrence of weak sedimentary lithologies subjected to gravitational loads in shaping conventional and unconventional oil and gas reservoirs. Two sedimentary lithologies that influence the geometries, physical properties, and heterogeneities of oil and gas reservoirs are shale and rocksalt. Both form effect barriers to the flow and communication of petroleum and gas and, in many cases, form the seals to major reservoirs due to their low permeabilities. Both are actively deformed in depositional environments due to their low strengths relative to gravitational loads applied. Thus, the shapes of seal-forming units, and the nature of fractures and faults that may breach them depend upon either the mechanical properties of shale or those of salt, and the loading histories to which they have been subjected. Deformed shales may, in addition, serve as unconventional reservoirs of gas if open fractures within them provide sufficient porosity. The fracture and flow properties of shales are not well constrained, and the authors are currently investigating these properties experimentally. The rheology of rocksalt, on the other hand, is well known and they believe that the time is right to apply the experimentally constrained constitutive relations for rocksalt to deformations in the Earth. Efforts are continuing on modeling fracture anisotropy and the authors have examined simple, two-mica models to evaluate the mechanical interactions they proposed for gneiss and mica-poor schists. Brief summaries of the progress and results to date for (1) the mechanical properties of schist, (2) a two-mica model of fracture anisotropy, (3) deformation of shale, and (4) modeling of salt and shale tectonics of the northern Gulf of Mexico are given in the following sections. 35 refs., 33 figs., 1 tab.

Kronenberg, A.K.; Russell, J.E.; Carter, N.L.; Mazariegos, R.; Shea, W.T.

1991-03-01T23:59:59.000Z

148

Modelling and simulations of the chemo-mechanical behaviour of leached cement-based materials: Interactions between damage and leaching  

Science Conference Proceedings (OSTI)

The assessment of the durability of cement-based materials, which could be employed in underground structures for nuclear waste disposal, requires accounting for deterioration factors, such as chemical attacks and damage, and for the interactions between these phenomena. The objective of the present paper consists in investigating the long-term behaviour of cementitious materials by simulating their response to chemical and mechanical solicitations. In a companion paper (Stora et al., submitted to Cem. Concr. Res. 2008), the implementation of a multi-scale homogenization model into an integration platform has allowed for evaluating the evolution of the mineral composition, diffusive and elastic properties inside a concrete material subjected to leaching. To complete this previous work, an orthotropic micromechanical damage model is presently developed and incorporated in this numerical platform to estimate the mechanical and diffusive properties of damaged cement-based materials. Simulations of the chemo-mechanical behaviour of leached cementitious materials are performed with the tool thus obtained and compared with available experiments. The numerical results are insightful about the interactions between damage and chemical deteriorations.

Stora, E., E-mail: stora@univ-mlv.f [Atomic Energy Commission, CEA Saclay DEN/DANS/DPC/SCCME/Laboratoire d'Etude du Comportement des Betons et des Argiles, 91191 Gif sur Yvette (France); Universite Paris-Est, Laboratoire de Modelisation et Simulation Multiechelle, FRE3160 CNRS, 5 boulevard Descartes, 77454 Marne-la-Vallee Cedex 2 (France); Bary, B. [Atomic Energy Commission, CEA Saclay DEN/DANS/DPC/SCCME/Laboratoire d'Etude du Comportement des Betons et des Argiles, 91191 Gif sur Yvette (France); He, Q.-C. [Universite Paris-Est, Laboratoire de Modelisation et Simulation Multiechelle, FRE3160 CNRS, 5 boulevard Descartes, 77454 Marne-la-Vallee Cedex 2 (France); Deville, E.; Montarnal, P. [CEA Saclay DEN/DANS/DM2S/SFME/MTMS, 91191 Gif sur Yvette (France)

2010-08-15T23:59:59.000Z

149

A 3D Monte Carlo Photoionization Code for Modeling Diffuse Ionized Gas  

E-Print Network (OSTI)

We have developed a three dimensional Monte Carlo photoionization code tailored for the study of Galactic H II regions and the percolation of ionizing photons in diffuse ionized gas. We describe the code, our calculation of photoionization, heating & cooling, and the approximations we have employed for the low density H II regions we wish to study. Our code gives results in agreement with the Lexington H II region benchmarks. We show an example of a 2D shadowed region and point out the very significant effect that diffuse radiation produced by recombinations of helium has on the temperature within the shadow.

Wood, K; Ercolano, B

2004-01-01T23:59:59.000Z

150

Liquid nanofilms. A mechanical model for the disjoining pressure  

E-Print Network (OSTI)

Liquids in contact with solids are submitted to intermolecular forces making liquids heterogeneous and, in a mechanical model, the stress tensor is not any more spherical as in homogeneous bulks. The aim of this article is to show that a square-gradient functional taking into account the volume liquid free energy corrected with two surface liquid density functionals is a mean field approximation allowing to study structures of very thin liquid nanofilms near plane solid walls. The model determines analytically the concept of disjoining pressure for liquid films of thicknesses of a very few number of nanometers and yields a behavior in good agreement with the shapes of experimental curves carried out by Derjaguin and his successors.

Henri Gouin

2009-04-11T23:59:59.000Z

151

A Comparison Between Modeled and Measured Clear-Sky Radiative Shortwave Fluxes in Arctic Environments, with Special Emphasis on Diffuse Radiation  

SciTech Connect

The ability of the SBDART radiative transfer model to predict clear-sky diffuse and direct normal broadband shortwave irradiances is investigated. Model calculations of these quantities are compared with data from the Atmospheric Radiation Measurement (ARM) program’s Southern Great Plains (SGP) and North Slope of Alaska (NSA) sites. The model tends to consistently underestimate the direct normal irradiances at both sites by about 1%. In regards to clear-sky diffuse irradiance, the model overestimates this quantity at the SGP site in a manner similar to what has been observed in other studies (Halthore and Schwartz, 2000). The difference between the diffuse SBDART calculations and Halthore and Schwartz’s MODTRAN calculations is very small, thus demonstrating that SBDART performs similarly to MODTRAN. SBDART is then applied to the NSA site, and here it is found that the discrepancy between the model calculations and corrected diffuse measurements (corrected for daytime offsets, Dutton et al., 2001) is 0.4 W/m2 when averaged over the 12 cases considered here. Two cases of diffuse measurements from a shaded “black and white” pyranometer are also compared with the calculations and the discrepancy is again minimal. Thus, it appears as if the “diffuse discrepancy” that exists at the SGP site does not exist at the NSA sites. We cannot yet explain why the model predicts diffuse radiation well at one site but not at the other.

Barnard, James C.; Flynn, Donna M.

2002-10-08T23:59:59.000Z

152

Modeling the Q-cycle mechanism of transmembrane energy conversion  

E-Print Network (OSTI)

The Q-cycle mechanism plays an important role in the conversion of the redox energy into the energy of the proton electrochemical gradient across the biomembrane. The bifurcated electron transfer reaction, which is built into this mechanism, recycles one electron, thus, allowing to translocate two protons per one electron moving to the high-potential redox chain. We study a kinetic model of the Q-cycle mechanism in an artificial system which mimics the bf complex of plants and cyanobacteria in the regime of ferredoxin-dependent cyclic electron flow. Using methods of condensed matter physics, we derive a set of master equations and describe a time sequence of electron and proton transfer reactions in the complex. We find energetic conditions when the bifurcation of the electron pathways at the positive side of the membrane occurs naturally, without any additional gates. For reasonable parameter values, we show that this system is able to translocate more than 1.8 protons, on average, per one electron, with a thermodynamic efficiency of the order of 32% or higher.

Anatoly Yu. Smirnov; Franco Nori

2011-06-29T23:59:59.000Z

153

Modeling the Q-cycle mechanism of transmembrane energy conversion  

E-Print Network (OSTI)

The Q-cycle mechanism plays an important role in the conversion of the redox energy into the energy of the proton electrochemical gradient across the biomembrane. The bifurcated electron transfer reaction, which is built into this mechanism, recycles one electron, thus, allowing to translocate two protons per one electron moving to the high-potential redox chain. We study a kinetic model of the Q-cycle mechanism in an artificial system which mimics the bf complex of plants and cyanobacteria in the regime of ferredoxin-dependent cyclic electron flow. Using methods of condensed matter physics, we derive a set of master equations and describe a time sequence of electron and proton transfer reactions in the complex. We find energetic conditions when the bifurcation of the electron pathways at the positive side of the membrane occurs naturally, without any additional gates. For reasonable parameter values, we show that this system is able to translocate more than 1.8 protons, on average, per one electron, with a t...

Smirnov, Anatoly Yu

2011-01-01T23:59:59.000Z

154

Physica D 198 (2004) 281308 Diffuse interface modeling of two-phase flows based on averaging  

E-Print Network (OSTI)

, The University of Iowa, Iowa City, IA 52242, USA Received 23 April 2004; received in revised form 26 August 2004 and uses an ensemble averaging procedure on an atomic scale to obtain a diffuse interface version forces in the momentum equations for each phase. Based on a superposition of microscopic (atomic

Beckermann, Christoph

155

A description of heavy ion induced fission based on diffusion model  

Science Conference Proceedings (OSTI)

In this talk a review on our recent work on fission theory from point of view of diffusion process is presented. The transient phenomena of fission rate are revealed and studied carefully. By comparison of the fission rate calculated both at the saddle and seission points

Wu Xizhen; Feng Renfa; Bao Jingdong; Sun Zemin; Zhuo Yizhong

1992-01-01T23:59:59.000Z

156

Diffusive Transport by Breaking Waves  

Science Conference Proceedings (OSTI)

A simple conceptual model of the relationship between advective transport by breaking waves and diffusive transport is derived. line model postulates that the displacement of fluid parcels by a breaking wave is analogous to molecular diffusion (...

Kenneth P. Bowman

1995-07-01T23:59:59.000Z

157

A new model for mixing by double-diffusive convection (semi-convection): I. The conditions for layer formation  

E-Print Network (OSTI)

The process referred to as "semi-convection" in astrophysics and "double-diffusive convection in the diffusive regime" in Earth and planetary sciences, occurs in stellar and planetary interiors in regions which are stable according to the Ledoux criterion but unstable according to the Schwarzschild criterion. In this series of papers, we analyze the results of an extensive suite of 3D numerical simulations of the process, and ultimately propose a new 1D prescription for heat and compositional transport in this regime which can be used in stellar or planetary structure and evolution models. In a preliminary study of the phenomenon, Rosenblum et al. (2011) showed that, after saturation of the primary instability, a system can evolve in one of two possible ways: the induced turbulence either remains homogeneous, with very weak transport properties, or transitions into a thermo-compositional staircase where the transport rate is much larger (albeit still smaller than in standard convection). In this paper, we sho...

Mirouh, Giovanni M; Stellmach, Stephan; Traxler, Adrienne L; Wood, Toby S

2011-01-01T23:59:59.000Z

158

Estimating market penetration of new district heating and cooling systems using a combination of economic cost and diffusion models  

SciTech Connect

The economic-cost model and the diffusion model are among the many market-penetration forecasting approaches that are available. These approaches have been used separately in many applications. In this paper, the authors briefly review these two approaches and then describe a methodology for forecasting market penetration using both approaches sequentially. This methodology is illustrated with the example of market-penetration forecasting of new district heating and cooling (DHC) systems in the Argonne DHC Market Penetration Model, which was developed and used over the period 1979--1983. This paper discusses how this combination approach, which incorporates the strengths of the economic-cost and diffusion models, has been superior to any one approach for market forecasts of DHC systems. Also discussed are the required modifications for revising and updating the model in order to generate new market-penetration forecasts for DHC systems. These modifications are required as a result of changes in DHC engineering, economic, and market data from 1983 to 1990. 13 refs., 5 figs., 2 tabs.

Teotia, A.P.S.; Karvelas, D.E.

1991-05-10T23:59:59.000Z

159

Surveying Diffusion in Complex Geometries. An Essay  

E-Print Network (OSTI)

The surrounding world surprises us by the beauty and variety of complex shapes that emerge from nanometric to macroscopic scales. Natural or manufactured materials (sandstones, sedimentary rocks and cement), colloidal solutions (proteins and DNA), biological cells, tissues and organs (lungs, kidneys and placenta), they all present irregularly shaped "scenes" for a fundamental transport "performance", that is, diffusion. Here, the geometrical complexity, entangled with the stochastic character of diffusive motion, results in numerous fascinating and sometimes unexpected effects like diffusion screening or localization. These effects control many diffusion-mediated processes that play an important role in heterogeneous catalysis, biochemical mechanisms, electrochemistry, growth phenomena, oil recovery, or building industry. In spite of a long and rich history of academic and industrial research in this field, it is striking to see how little we know about diffusion in complex geometries, especially the one which occurs in three dimensions. We present our recent results on restricted diffusion. We look into the role of geometrical complexity at different levels, from boundary microroughness to hierarchical structure and connectivity of the whole diffusion-confining domain. We develop a new approach which consists in combining fast random walk algorithms with spectral tools. The main focus is on studying diffusion in model complex geometries (von Koch boundaries, Kitaoka acinus, etc.), as well as on developing and testing spectral methods. We aim at extending this knowledge and at applying the accomplished arsenal of theoretical and numerical tools to structures found in nature and industry.

Denis Grebenkov

2009-09-08T23:59:59.000Z

160

CFD MODELING ANALYSIS OF MECHANICAL DRAFT COOLING TOWER  

Science Conference Proceedings (OSTI)

Industrial processes use mechanical draft cooling towers (MDCT's) to dissipate waste heat by transferring heat from water to air via evaporative cooling, which causes air humidification. The Savannah River Site (SRS) has a MDCT consisting of four independent compartments called cells. Each cell has its own fan to help maximize heat transfer between ambient air and circulated water. The primary objective of the work is to conduct a parametric study for cooling tower performance under different fan speeds and ambient air conditions. The Savannah River National Laboratory (SRNL) developed a computational fluid dynamics (CFD) model to achieve the objective. The model uses three-dimensional steady-state momentum, continuity equations, air-vapor species balance equation, and two-equation turbulence as the basic governing equations. It was assumed that vapor phase is always transported by the continuous air phase with no slip velocity. In this case, water droplet component was considered as discrete phase for the interfacial heat and mass transfer via Lagrangian approach. Thus, the air-vapor mixture model with discrete water droplet phase is used for the analysis. A series of the modeling calculations was performed to investigate the impact of ambient and operating conditions on the thermal performance of the cooling tower when fans were operating and when they were turned off. The model was benchmarked against the literature data and the SRS test results for key parameters such as air temperature and humidity at the tower exit and water temperature for given ambient conditions. Detailed results will be presented here.

Lee, S; Alfred Garrett, A; James02 Bollinger, J; Larry Koffman, L

2008-03-03T23:59:59.000Z

Note: This page contains sample records for the topic "diffusion mechanisms 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

The Potential of MEMS for Advancing Experiments and Modeling in Cell Mechanics  

E-Print Network (OSTI)

The Potential of MEMS for Advancing Experiments and Modeling in Cell Mechanics O. Loh & A. Vaziri # Society for Experimental Mechanics 2007 Abstract Response to mechanical stimuli largely dictates cellular the hierarchical cell structure. As experimental and model-based investigations in cell mechanics advance

Vaziri, Ashkan

162

Sensitivity of Urban Airshed Model (UAM-IV) Calculated Air Pollutant Concentrations to the Vertical Diffusion Parameterization during Convective Meteorological Situations  

Science Conference Proceedings (OSTI)

It is shown that Urban Airshed Model (UAM-IV) calculated air pollutant concentrations during photochemical smog episodes in Atlanta, Georgia, depend strongly on the numerical parameterization of the daytime vertical diffusivity. Results found ...

Peter Nowacki; Perry J. Samson; Sanford Sillman

1996-10-01T23:59:59.000Z

163

Mathematical modelling of diffusion-reaction, and solution algorithm for complex reaction networks in porous catalyst pellets-steam reforming of natural gas  

Science Conference Proceedings (OSTI)

Three models of different degrees of rigor are developed for diffusion and reaction in porous catalyst pellets for the industrially important multicomponents' system with a multiple reversible reaction for the steam reforming of natural gas. The more ...

M. E. Abashar; S. S. Elnashaie

1993-10-01T23:59:59.000Z

164

STATISTICAL MECHANICS MODELING OF MESOSCALE DEFORMATION IN METALS  

SciTech Connect

The research under this project focused on a theoretical and computational modeling of dislocation dynamics of mesoscale deformation of metal single crystals. Specifically, the work aimed to implement a continuum statistical theory of dislocations to understand strain hardening and cell structure formation under monotonic loading. These aspects of crystal deformation are manifestations of the evolution of the underlying dislocation system under mechanical loading. The project had three research tasks: 1) Investigating the statistical characteristics of dislocation systems in deformed crystals. 2) Formulating kinetic equations of dislocations and coupling these kinetics equations and crystal mechanics. 3) Computational solution of coupled crystal mechanics and dislocation kinetics. Comparison of dislocation dynamics predictions with experimental results in the area of statistical properties of dislocations and their field was also a part of the proposed effort. In the first research task, the dislocation dynamics simulation method was used to investigate the spatial, orientation, velocity, and temporal statistics of dynamical dislocation systems, and on the use of the results from this investigation to complete the kinetic description of dislocations. The second task focused on completing the formulation of a kinetic theory of dislocations that respects the discrete nature of crystallographic slip and the physics of dislocation motion and dislocation interaction in the crystal. Part of this effort also targeted the theoretical basis for establishing the connection between discrete and continuum representation of dislocations and the analysis of discrete dislocation simulation results within the continuum framework. This part of the research enables the enrichment of the kinetic description with information representing the discrete dislocation systems behavior. The third task focused on the development of physics-inspired numerical methods of solution of the coupled dislocation kinetics and crystal mechanics framework. To a large extent, this task has also been successfully started. We have developed a custom finite-element approach with mesh points being a subset of the underlying crystal structure. When used to predict the evolution of the dislocation system, the planar motion of dislocations is naturally captured for all slip systems, thus minimizing numerical errors and providing simple ways to investigate cross slip and dislocation reactions. Preliminary results in this direction show that we are closer than ever in building a predictive framework for dislocation dynamics and mesoscale plasticity based on the first principles of dislocation dynamics. The rest of the report gives and overview of the research performed under this project and highlights the key results and open questions left for future investigations.

Anter El-Azab

2013-04-08T23:59:59.000Z

165

The Morphology of the Galactic Dark Matter Synchrotron Emission with Self-Consistent Cosmic Ray Diffusion Models  

E-Print Network (OSTI)

A generic prediction in the paradigm of weakly interacting dark matter is the production of relativistic particles from dark matter pair-annihilation in regions of high dark matter density. Ultra-relativistic electrons and positrons produced in the center of the Galaxy by dark matter annihilation should produce a diffuse synchrotron emission. While the spectral shape of the synchrotron dark matter haze depends on the particle model (and secondarily on the galactic magnetic fields), the morphology of the haze depends primarily on (1) the dark matter density distribution, (2) the galactic magnetic field morphology, and (3) the diffusion model for high-energy cosmic-ray leptons. Interestingly, an unidentified excess of microwave radiation with characteristics similar to those predicted by dark matter models has been claimed to exist near the galactic center region in the data reported by the WMAP satellite, and dubbed the "WMAP haze". In this study, we carry out a self-consistent treatment of the variables enumerated above, enforcing constraints from the available data on cosmic rays, radio surveys and diffuse gamma rays. We outline and make predictions for the general morphology and spectral features of a "dark matter haze" and we compare them to the WMAP haze data. We also characterize and study the spectrum and spatial distribution of the inverse Compton emission resulting from the same population of energetic electrons and positrons. We point out that the spectrum and morphology of the radio emission at different frequencies is a powerful diagnostics to test whether a galactic synchrotron haze indeed originates from dark matter annihilation.

Tim Linden; Stefano Profumo; Brandon Anderson

2010-04-22T23:59:59.000Z

166

MODELING THE DIFFUSION OF MICRO-CHP IN A RESIDENTIAL AREA  

E-Print Network (OSTI)

A thesis presented on the diffusion of micro-CHP in a residential area consisting of houses with multiple owners, currently using condensing boilers. The thesis shows that micro-CHP will not reach 50 % of the market in less than 20 years. Furthermore it analyses the impact of the heat demands, the gas electricity and feedback prices as well as the subsidies on the speed and time of adoption of micro-CHP. ii DECLARATION I declare that: this work has been prepared by myself, all literal or content based quotations are clearly pointed out,

Christian Chemaly; Technische Universität Hamburg; Christian Chemaly

2009-01-01T23:59:59.000Z

167

Determining the focal mechanisms of earthquakes by full waveform modeling  

E-Print Network (OSTI)

Determining the focal mechanism of an earthquake helps us to better characterize reservoirs, define faults, and understand the stress and strain regime. The objective of this thesis is to find the focal mechanism and depth ...

Busfar, Hussam A. (Hussam Abdullah)

2009-01-01T23:59:59.000Z

168

Measurements and modeling of moisture diffusion processes in transformer insulation using interdigital dielectrometry sensors  

E-Print Network (OSTI)

The presence of moisture in a transformer deteriorates the transformer insulation by decreasing its electrical, mechanical, and thermal strength. Therefore, it is important to monitor the moisture condition in both liquid ...

Du, Yanqing, 1971-

1999-01-01T23:59:59.000Z

169

Simplified clear sky model for direct and diffuse insolation on horizontal surfaces  

DOE Green Energy (OSTI)

A detailed comparison was made between five simple broadband models for clear sky global insolation. Compared models were those of Atwater and Ball, Davies and Hay, Watt, Hoyt, and Lacis and Hansen. A sixth simple model, called the Bird model, has been formulated by using parts of these five models and by comparison with the results from three rigorous radiative transfer codes. All of the simple models provide results that agree within < 10% with the three rigorous codes when the sun is in the zenith position. The Bird and Hoyt models agree within 3% with each other and with the results of the rigorous codes. However, the Bird model is easier to implement and has broader application than the Hoyt model.

Bird, R.E.; Hulstrom, R.L.

1981-02-01T23:59:59.000Z

170

Radiometric Modeling of Mechanical Draft Cooling Towers to Assist in the Extraction of their Absolute Temperature  

E-Print Network (OSTI)

Radiometric Modeling of Mechanical Draft Cooling Towers to Assist in the Extraction CENTER FOR IMAGING SCIENCE Title of Dissertation: Radiometric Modeling of Mechanical Draft Cooling Towers of Mechanical Draft Cooling Towers to Assist in the Extraction of their Absolute Temperature from Remote Thermal

Salvaggio, Carl

171

Including Surface Kinetic Effects in Simple Models of Ice Vapor Diffusion  

Science Conference Proceedings (OSTI)

A model for kinetically-limited vapor growth and aspect ratio evolution of atmospheric single ice crystals is presented. The method is based on the adaptive habit model of Chen and Lamb (1994), but is modified to include the deposition ...

Chengzhu Zhang; Jerry Y. Harrington

172

Modeling of Microstructure on the Hydrogen Diffusion in X70 Steel ...  

Science Conference Proceedings (OSTI)

Materials Genomics Past & Future: From CALPHAD to Flight · Microstructure Stability of Multi-Materials Systems with Adaptive Microstructures · Modeling of ...

173

Numerical Modeling of Hydraulic Fracture Propagation Using Thermo-hydro-mechanical Analysis with Brittle Damage Model by Finite Element Method  

E-Print Network (OSTI)

Better understanding and control of crack growth direction during hydraulic fracturing are essential for enhancing productivity of geothermal and petroleum reservoirs. Structural analysis of fracture propagation and impact on fluid flow is a challenging issue because of the complexity of rock properties and physical aspects of rock failure and fracture growth. Realistic interpretation of the complex interactions between rock deformation, fluid flow, heat transfer, and fracture propagation induced by fluid injection is important for fracture network design. In this work, numerical models are developed to simulate rock failure and hydraulic fracture propagation. The influences of rock deformation, fluid flow, and heat transfer on fracturing processes are studied using a coupled thermo-hydro-mechanical (THM) analysis. The models are used to simulate microscopic and macroscopic fracture behaviors of laboratory-scale uniaxial and triaxial experiments on rock using an elastic/brittle damage model considering a stochastic heterogeneity distribution. The constitutive modeling by the energy release rate-based damage evolution allows characterizing brittle rock failure and strength degradation. This approach is then used to simulate the sequential process of heterogeneous rock failures from the initiation of microcracks to the growth of macrocracks. The hydraulic fracturing path, especially for fractures emanating from inclined wellbores and closed natural fractures, often involves mixed mode fracture propagation. Especially, when the fracture is inclined in a 3D stress field, the propagation cannot be modeled using 2D fracture models. Hence, 2D/3D mixed-modes fracture growth from an initially embedded circular crack is studied using the damage mechanics approach implemented in a finite element method. As a practical problem, hydraulic fracturing stimulation often involves fluid pressure change caused by injected fracturing fluid, fluid leakoff, and fracture propagation with brittle rock behavior and stress heterogeneities. In this dissertation, hydraulic fracture propagation is simulated using a coupled fluid flow/diffusion and rock deformation analysis. Later THM analysis is also carried out. The hydraulic forces in extended fractures are solved using a lubrication equation. Using a new moving-boundary element partition methodology (EPM), fracture propagation through heterogeneous media is predicted simply and efficiently. The method allows coupling fluid flow and rock deformation, and fracture propagation using the lubrication equation to solve for the fluid pressure through newly propagating crack paths. Using the proposed model, the 2D/3D hydraulic fracturing simulations are performed to investigate the role of material and rock heterogeneity. Furthermore, in geothermal and petroleum reservoir design, engineers can take advantage of thermal fracturing that occurs when heat transfers between injected flow and the rock matrix to create reservoir permeability. These thermal stresses are calculated using coupled THM analysis and their influence on crack propagation during reservoir stimulation are investigated using damage mechanics and thermal loading algorithms for newly fractured surfaces.

Min, Kyoung

2013-08-01T23:59:59.000Z

174

Simple Models of Stratification  

Science Conference Proceedings (OSTI)

Simple analytical and numerical models of gratified circulation are discussed. The models are driven by buoyancy and mechanical forcing, and buoyancy diffusion is parameterized in term of diapycnal mass fluxes. The interior responds in typical ...

William K. Dewar

1991-12-01T23:59:59.000Z

175

Coupled 3D hydrodynamic models for submarine outfalls. Denvironmental hydraulic design and control of multiport diffusers.  

E-Print Network (OSTI)

??The book describes the hydraulic design and environmental impact prediction technologies for such installations. Focus are the hydrodynamics approached by computer models. First, a multiport… (more)

Bleninger, Tobias

2007-01-01T23:59:59.000Z

176

Establishing the Clear-Sky Diffuse Reference for BORCAL Using EPLAB Model 8-48 Pyranometers at the National Renewable Energ...  

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

Establishing the Clear-Sky Diffuse Reference for BORCAL Establishing the Clear-Sky Diffuse Reference for BORCAL Using EPLAB Model 8-48 Pyranometers at the National Renewable Energy Laboratory I. Reda, T. L. Stoffel, and D. Myers National Renewable Energy Laboratory Golden, Colorado Abstract Precision pyranometer calibrations are important to the quality of Atmospheric Radiation Measurement's (ARM's) shortwave solar irradiance measurements. Calibrations at the National Renewable Energy Laboratory (NREL) and Southern Great Plains (SGP) are under clear-sky conditions. G = I * COS(2) + D, is used to establish the reference global during the calibration. The references for the beam irradiance, I, and the solar zenith angle, 2, are internationally recognized. There is no recognized reference for the diffuse irradiance, D. Our research goal is to establish a consistent diffuse

177

Characterization and modeling of polysilicon MEMS chemical-mechanical polishing  

E-Print Network (OSTI)

Heavily used in the manufacture of integrated circuits, chemical-mechanical polishing (CMP) is becoming an enabling technology for microelectromechanical systems (MEMS). To reliably use CMP in the manufacturing process, ...

Tang, Brian D. (Brian David), 1980-

2004-01-01T23:59:59.000Z

178

Modeling of chemical mechanical polishing for shallow trench isolation  

E-Print Network (OSTI)

This thesis presents the nonlinear analysis, design, fabrication, and testing of an axial-gap magnetic induction micro machine, which is a two-phase planar motor in which the rotor is suspended above the stator via mechanical ...

Lee, Brian, 1975-

2002-01-01T23:59:59.000Z

179

Climatology of Sr-90 in Surface Air: A Simple Model using Diffusion and Scavenging  

Science Conference Proceedings (OSTI)

The evolution of Sr-90 distribution following an instantaneous stratospheric or tropospheric source in an annulus defined by latitude walls is investigated by means of a very simple model that uses 12 stratospheric and 12 tropospheric annular ...

D. O. Staley

1985-01-01T23:59:59.000Z

180

Brazil Diffuse Solar Radiation Model (40km) from INPE and LABSOLAR  

Open Energy Info (EERE)

by INPE - National Institute for Space Research) were used to produce the dataset and SHAPE files.
The assessment of reliability levels of the BRASIL-SR model were performed...

Note: This page contains sample records for the topic "diffusion mechanisms 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

Brazil Diffuse Solar Radiation Model (40km) from INPE and LABSOLAR...  

Open Energy Info (EERE)

by INPE - National Institute for Space Research) were used to produce the dataset and SHAPE files. The assessment of reliability levels of the BRASIL-SR model were performed...

182

The Computation of Diapycnal Diffusive and Advective Scalar Fluxes in Multilayer Isopycnic-Coordinate Ocean Models  

Science Conference Proceedings (OSTI)

This paper addresses the problem of how to numerically incorporate diapycnal mixing and advection processes into isopycnal ocean general circulation models. A general expression of diapycnal velocity is derived for the case in which density is a ...

Dingming Hu

1996-08-01T23:59:59.000Z

183

A New Diffusion Scheme for Numerical Models Based on Full Irreversibility  

Science Conference Proceedings (OSTI)

In this work, the forecast accuracy of a numerical weather prediction model is improved by emulating physical dissipation as suggested by the second law of thermodynamics, which controls the irreversible evolutionary direction of a many-body ...

C. Liu; Y. Liu; H. Xu

2009-04-01T23:59:59.000Z

184

Modeling the mechanical behavior of amorphous metals by shear transformation zone dynamics  

E-Print Network (OSTI)

A new mesoscale modeling technique for the thermo-mechanical behavior of amorphous metals is proposed. The modeling framework considers the shear transformation zone (STZ) as the fundamental unit of deformation, and ...

Homer, Eric Richards, 1980-

2010-01-01T23:59:59.000Z

185

An improved structural mechanics model for the FRAPCON nuclear fuel performance code  

E-Print Network (OSTI)

In order to provide improved predictions of Pellet Cladding Mechanical Interaction (PCMI) for the FRAPCON nuclear fuel performance code, a new model, the FRAPCON Radial-Axial Soft Pellet (FRASP) model, was developed. This ...

Mieloszyk, Alexander James

2012-01-01T23:59:59.000Z

186

Mechanism of Zonal Index Evolution in a Two-Layer Model  

Science Conference Proceedings (OSTI)

A mechanism that drives a zonal jet to meander in the meridional direction is investigated with a two-layer multiwave quasigeostrophic ?-plant channel model. This model isolates the zonal index characteristics of a purely eddy-driven jet. ...

Sukyoung Lee; Steven Feldstein

1996-08-01T23:59:59.000Z

187

Diffusion Coefficients  

Science Conference Proceedings (OSTI)

Mar 13, 2012 ... Challenges in Constructing Diffusion Mobility Databases for Industrial Alloys: ... Implementation of new initiatives such as the Materials Genome ...

188

A Drift-Diffusion-Reaction Model for Excitonic Photovoltaic Bilayers: Asymptotic Analysis and A 2-D HDG Finite-Element Scheme  

E-Print Network (OSTI)

We present and discuss a mathematical model for the operation of bilayer organic photovoltaic devices. Our model couples drift-diffusion-recombination equations for the charge carriers (specifically, electrons and holes) with a reaction-diffusion equation for the excitons/ polaron pairs and Poisson's equation for the self-consistent electrostatic potential. The material difference (i.e. the HOMO/LUMO gap) of the two organic substrates forming the bilayer device are included as a work-function potential. Firstly, we perform an asymptotic analysis of the scaled one-dimensional stationary state system i) with focus on the dynamics on the interface and ii) with the goal of simplifying the bulk dynamics away for the interface. Secondly, we present a twodimensional Hybrid Discontinuous Galerkin Finite Element numerical scheme which is very well suited to resolve i) the material changes ii) the resulting strong variation over the interface and iii) the necessary upwinding in the discretization of drift-diffusion equ...

Brinkman, Daniel; Markowich, Peter A; Wolfram, Marie-Therese

2012-01-01T23:59:59.000Z

189

The Neural Network Model using for Predictions Mechanical ...  

Science Conference Proceedings (OSTI)

Study of Composite Materials Application for Horizontal Axis Wind Turbine Blades ... Using the Computational Modelling to Improve Durability of Diesel Engine ...

190

Thermal-Mechanical Fatigue Life Model for Coated Superalloy ...  

Science Conference Proceedings (OSTI)

in an aggressive combustion gas environment. Coating ..... M.I. Wood and G.F. Harrison, "Modeling The Deformation Of Coated. Superalloys Under Thermal ...

191

Galactic Diffuse Emissions  

DOE Green Energy (OSTI)

Interactions of cosmic rays with interstellar nucleons and photons make the Milky Way a bright, diffuse source of high-energy {gamma}-rays. Observationally, the results from EGRET, COMPTEL, and OSSE have now been extended to higher energies by ground-based experiments, with detections of diffuse emission in the Galactic center reported by H.E.S.S. in the range above 100 GeV and of diffuse emission in Cygnus by MILAGRO in the TeV range. In the range above 100 keV, INTEGRAL SPI has found that diffuse emission remains after point sources are accounted for. I will summarize current knowledge of diffuse {gamma}-ray emission from the Milky Way and review some open issues related to the diffuse emission -- some old, like the distribution of cosmic-ray sources and the origin of the 'excess' of GeV emission observed by EGRET, and some recently recognized, like the amount and distribution of molecular hydrogen not traced by CO emission -- and anticipate some of the advances that will be possible with the Large Area Telescope on GLAST. We plan to develop an accurate physical model for the diffuse emission, which will be useful for detecting and accurately characterizing emission from Galactic point sources as well as any Galactic diffuse emission from exotic processes, and for studying the unresolved extragalactic emission.

Digel, Seth W.; /SLAC

2007-10-25T23:59:59.000Z

192

Assessment of reduced mechanisms using One Dimensional Stochastic Turbulence model  

E-Print Network (OSTI)

turbulence model for a syngas jet flame. Proceeding of FallKerstein 2002), a turbulent syngas (CO/H2/NO) jet flame wasand DNS results of the syngas jet flame was recently done

Chien, Li-Chun

2010-01-01T23:59:59.000Z

193

Analytic Models for the Mechanical Structure of the Solar Core  

E-Print Network (OSTI)

All stars exhibit universal central behavior in terms of new homology variables (u,w). In terms of these variables, we obtain simple analytic fits to numerical standard solar models for the core and radiative zones of the ZAMS and present Suns, with a few global parameters. With these analytic fits, different theoretical models of the solar core, neutrino fluxes, and helioseismic observations can be parametrized and compared.

Dallas C. Kennedy; Sidney A. Bludman

1998-12-09T23:59:59.000Z

194

Modeling Technology Innovation and Diffusion in Transition Economies: The Case of China  

SciTech Connect

Our research program has involved data collection and analysis, modeling building, and the presentation of results. The data collection and analysis work was done in collaboration with our colleagues at the National Bureau of Statistics (NBS) in China. Each summer, we hosted on average four researchers from NBS for 3 months to work with us on the data analysis component of the research. Each summer our NBS colleagues would bring an updated data set of firm-level economic, R&D, and energy data that allowed us to explore the impacts of technological change on firm-level energy consumption. This grant also funded a number of graduate and undergraduate students to work on different elements of the analysis.

Karen Fisher-Vanden

2005-10-20T23:59:59.000Z

195

A Hydro-Thermo-Mechanical Numerical Model For Hdr Geothermal Reservoir  

Open Energy Info (EERE)

Hydro-Thermo-Mechanical Numerical Model For Hdr Geothermal Reservoir Hydro-Thermo-Mechanical Numerical Model For Hdr Geothermal Reservoir Evaluation Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: A Hydro-Thermo-Mechanical Numerical Model For Hdr Geothermal Reservoir Evaluation Details Activities (0) Areas (0) Regions (0) Abstract: A two-dimensional numerical model of coupled fluid flow, heat transfer and rock mechanics in naturally fractured rock is developed. The model is applicable to assessments of hot dry rock (HDR) geothermal reservoir characterisation experiments, and to the study of hydraulic stimulations and the heat extraction potential of HDR reservoirs. Modelling assumptions are based on the characteristics of the experimental HDR reservoir in the Carnmenellis granite in Cornwall, S. W. England. In

196

A Mechanical Fluid-Dynamical Model For Ground Movements At Campi Flegrei  

Open Energy Info (EERE)

Mechanical Fluid-Dynamical Model For Ground Movements At Campi Flegrei Mechanical Fluid-Dynamical Model For Ground Movements At Campi Flegrei Caldera Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: A Mechanical Fluid-Dynamical Model For Ground Movements At Campi Flegrei Caldera Details Activities (0) Areas (0) Regions (0) Abstract: We present here a consistent model, which explains the mechanisms of unrest phenomena at Campi Flegrei (Italy), both at short-term (years) and at secular scales. The model consists basically of two effects: the first one is related to the elastic response of the shallow crust to increasing pressure within a shallow magma chamber; the second involves the fluid-dynamics of shallow aquifers in response to increasing pressure and/or temperature at depth. The most important roles in the proposed model

197

A generalized theory for non-classical transport with angular-dependent path-length distributions 2: Anisotropic diffusion in model pebble bed reactor cores  

E-Print Network (OSTI)

We describe an analysis of neutron transport in the interior of model pebble bed reactor (PBR) cores, considering both crystal and random pebble arrangements. Monte Carlo codes were developed for (i) generating random realizations of the model PBR core, and (ii) performing neutron transport inside the crystal and random heterogeneous cores; numerical results are presented for two different choices of material parameters. These numerical results are used to investigate the anisotropic behavior of neutrons in each case and to assess the accuracy of estimates for the diffusion coefficients obtained with the diffusion approximations of different models: the atomic mix model, the Behrens correction, the Lieberoth correction, the generalized linear Boltzmann equation (GLBE), and the new GLBE with angular-dependent path-length distributions. This new theory utilizes a non-classical form of the Boltzmann equation in which the locations of the scattering centers in the system are correlated and the distance-to-collisi...

Vasques, Richard

2013-01-01T23:59:59.000Z

198

Coal thermolysis modeling: The effects of restricted diffusion on thermal reaction pathways  

Science Conference Proceedings (OSTI)

The technique of model compound immobilization by covalent surface attachment is being employed to investigate the potential impact of restricted diffusional mobility on the thermal reactivity of coal. This restricted mobility may be imposed in coal as a consequence of its cross-linked, macromolecular structure. A detailed study of the thermolysis of surface-immobilized bibenzyl showed that the rate of unimolecular C-C homolysis is similar to that in fluid phases. Recent studies have foucused on the thermally induced, free radical chain decomposition reactions for surface-immobilized 1,3-diphenylpropane and 1,4-diphenylbutane. For 1,4-diphenylbutane both the reaction rate and product composition are strongly dependent on surface coverage and, hence, the proximity of 1.4-diphenylbutane molecules and hydrogen abstracting radicals on the surface. The rates and selectivities of these key bimolecular reaction steps on the surface might also be affected by the structure of neighboring molecules. In the current study, we are beginning to probe this feature by examining the influence of the structure of co-attached aromatic molecules such as biphenyl and diphenylmethane on the reaction rate and regioselectivity in the thermolysis of 1,4-diphenylbutane. 7 refs. , 1 fig., 2 tabs.

Buchanan, A.C. III; Britt, P.F.; Biggs, C.A.

1989-01-01T23:59:59.000Z

199

Mechanisms, Models, and Simulations of Metal-Coated Fiber Consolidation  

E-Print Network (OSTI)

of existing contacts as matrix plasticity and/or PLC. When the voids are small the coated fiber bundle shrinks-shaped voids with a shape factor similar to that observed in the experiments. Creep rates were microstructure fractions were introduced into the model using micromechanics-based creep constitutive relationships

Wadley, Haydn

200

Qunatum-Mechanical Model of Spacetime II: Thermodynamics of Spacetime  

E-Print Network (OSTI)

In this second part of our series of two papers, where spacetime is modelled by a graph, where Planck size quantum black holes lie on the vertices, we consider the thermodynamics of spacetime. We formulate an equation which tells in which way an accelerating, spacelike two-surface of spacetime interacts with the thermal radiation flowing through that surface. In the low temperature limit, where most quantum black holes constituting spacetime are assumed to lie in the ground state, our equation implies, among other things, the Hawking and the Unruh effects, as well as Einstein's field equation with a vanishing cosmological constant for general matter fields. We also consider the high temperature limit, where the microscopic black holes are assumed to lie in highly excited states. In this limit our model implies, among other things, that black hole entropy depends logarithmically on its area, instead of being proportional to the area.

Makela, J

2008-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "diffusion mechanisms 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.


201

Dose Modeling Evaluations and Technical Support Document For the Authorized Limits Request for the DOE-Owned Property Outside the Limited Area, Paducah Gaseous Diffusion Plant Paducah, Kentucky  

SciTech Connect

Environmental assessments and remediation activities are being conducted by the U.S. Department of Energy (DOE) at the Paducah Gaseous Diffusion Plant (PGDP), Paducah, Kentucky. The Oak Ridge Institute for Science and Education (ORISE), a DOE prime contractor, was contracted by the DOE Portsmouth/Paducah Project Office (DOE-PPPO) to conduct radiation dose modeling analyses and derive single radionuclide soil guidelines (soil guidelines) in support of the derivation of Authorized Limits (ALs) for 'DOE-Owned Property Outside the Limited Area' ('Property') at the PGDP. The ORISE evaluation specifically included the area identified by DOE restricted area postings (public use access restrictions) and areas licensed by DOE to the West Kentucky Wildlife Management Area (WKWMA). The licensed areas are available without restriction to the general public for a variety of (primarily) recreational uses. Relevant receptors impacting current and reasonably anticipated future use activities were evaluated. In support of soil guideline derivation, a Conceptual Site Model (CSM) was developed. The CSM listed radiation and contamination sources, release mechanisms, transport media, representative exposure pathways from residual radioactivity, and a total of three receptors (under present and future use scenarios). Plausible receptors included a Resident Farmer, Recreational User, and Wildlife Worker. single radionuclide soil guidelines (outputs specified by the software modeling code) were generated for three receptors and thirteen targeted radionuclides. These soil guidelines were based on satisfying the project dose constraints. For comparison, soil guidelines applicable to the basic radiation public dose limit of 100 mrem/yr were generated. Single radionuclide soil guidelines from the most limiting (restrictive) receptor based on a target dose constraint of 25 mrem/yr were then rounded and identified as the derived soil guidelines. An additional evaluation using the derived soil guidelines as inputs into the code was also performed to determine the maximum (peak) dose for all receptors. This report contains the technical basis in support of the DOE?s derivation of ALs for the 'Property.' A complete description of the methodology, including an assessment of the input parameters, model inputs, and results is provided in this report. This report also provides initial recommendations on applying the derived soil guidelines.

Boerner, A. J. [Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN (United States). Independent Environmental Assessment and Verification Program; Maldonado, D. G. [Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN (United States). Independent Environmental Assessment and Verification Program; Hansen, Tom [Ameriphysics, LLC (United States)

2012-09-01T23:59:59.000Z

202

On a scale invariant model of statistical mechanics and the kinetic theory of ideal gas  

Science Conference Proceedings (OSTI)

A scale invariant model of statistical mechanics is applied to derive invariant Maxwell-Boltzmann speed and Planck energy spectrum of equilibrium statistical fields including that of isotropic stationary turbulence. The latter is shown to lead to the ... Keywords: Riemann hypothesis, TOE, kinetic theory of ideal gas, statistical mechanics, thermodynamics

Siavash H. Sohrab

2011-04-01T23:59:59.000Z

203

On-line regression algorithms for learning mechanical models of robots: A survey  

Science Conference Proceedings (OSTI)

With the emergence of more challenging contexts for robotics, the mechanical design of robots is becoming more and more complex. Moreover, their missions often involve unforeseen physical interactions with the environment. To deal with these difficulties, ... Keywords: Adaptive and learning systems, Adaptive control, Mechanical models

Olivier Sigaud; Camille Salaün; Vincent Padois

2011-12-01T23:59:59.000Z

204

Distributed Hydrologic Modeling in Northwest Mexico Reveals the Links between Runoff Mechanisms and Evapotranspiration  

Science Conference Proceedings (OSTI)

A distributed hydrologic model is used to evaluate how runoff mechanisms—including infiltration excess (RI), saturation excess (RS), and groundwater exfiltration (RG)—influence the generation of streamflow and evapotranspiration (ET) in a ...

Agustín Robles-Morua; Enrique R. Vivoni; Alex S. Mayer

2012-06-01T23:59:59.000Z

205

Impact of an Updated Carbon Bond Mechanism on Predictions from the CMAQ Modeling System: Preliminary Assessment  

Science Conference Proceedings (OSTI)

An updated and expanded version of the Carbon Bond mechanism (CB05) has been incorporated into the Community Multiscale Air Quality (CMAQ) modeling system to more accurately simulate wintertime, pristine, and high-altitude situations. The CB05 ...

Golam Sarwar; Deborah Luecken; Greg Yarwood; Gary Z. Whitten; William P. L. Carter

2008-01-01T23:59:59.000Z

206

Investigating the Mechanisms of Diurnal Rainfall Variability Using a Regional Climate Model  

Science Conference Proceedings (OSTI)

This study investigates the ability of a regional climate model (RCM) to simulate the diurnal cycle of precipitation over southeast Australia, to provide a basis for understanding the mechanisms that drive diurnal variability. When compared with ...

Jason P. Evans; Seth Westra

2012-10-01T23:59:59.000Z

207

Thermodynamic modeling of transcription: sensitivity analysis differentiates biological mechanism from mathematical model-induced effects  

E-Print Network (OSTI)

as: Dresch et al. : Thermodynamic modeling of transcription:ARTICLE Open Access Thermodynamic modeling of transcription:on the analysis of thermodynamic models, which have been

Dresch, Jacqueline M; Liu, Xiaozhou; Arnosti, David N; Ay, Ahmet

2010-01-01T23:59:59.000Z

208

Diffuse Scattering  

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

Diffuse Scattering Diffuse Scattering * Anticipatory (trick) question: If you have an x-ray or neutron detector looking at a small sample volume, which will scatter more x- rays or neutrons into the detector 1 atom 100 atoms or 1000 atoms? X-ray or neutron beam Answer: Depends! Diffuse Scattering Gene E. Ice Materials Science and Technology Division Oak Ridge National Laboratory, USA National School on Neutron and X-ray Scattering ORNL/SNS June 2011 Presentation concentrates year graduate-level course into 1 hour * Skip mathematical complexities * Expose to range of applications * Develop intuition for length scales * Talk like x-ray/neutron scattering guru - Reciprocal space - Debye Temperature - Laue monotonic - Krivoglaz defects of 1st/2nd kinds! Great for cocktail parties or impressing attractive strangers-

209

Numerical study on convection diffusion for gasification agent in underground coal gasification. Part I: establishment of mathematical models and solving method  

SciTech Connect

The aim of this article is to discuss the distribution law of the gasification agent concentration in a deep-going way during underground coal gasification and the new method of solving the problem for the convection diffusion of the gas. In this paper, the basic features of convection diffusion for the gas produced in underground coal gasification are studied. On the basis of the model experiment, through the analysis of the distribution and patterns of variation for the fluid concentration field in the process of the combustion and gasification of the coal seams within the gasifier, the 3-D non-linear unstable mathematical models on the convection diffusion for oxygen are established. In order to curb such pseudo-physical effects as numerical oscillation and surfeit which frequently occurred in the solution of the complex mathematical models, the novel finite unit algorithm, the upstream weighted multi-cell balance method is advanced in this article, and its main derivation process is introduced.

Yang, L.H.; Ding, Y.M. [China University of Mining & Technology, Xuzhou (China). College of Resources and Geoscience

2009-07-01T23:59:59.000Z

210

What Are the Sources of Mechanical Damping in Matsuno–Gill-Type Models?  

Science Conference Proceedings (OSTI)

The Matsuno–Gill model has been widely used to study the tropical large-scale circulations and atmosphere–ocean interactions. However, a common critique of this model is that it requires a strong equivalent linear mechanical damping to get ...

Jia-Lin Lin; Brian E. Mapes; Weiqing Han

2008-01-01T23:59:59.000Z

211

Numerical modeling of electrochemical-mechanical interactions in lithium polymer batteries  

Science Conference Proceedings (OSTI)

This paper presents a multi-scale finite element approach for lithium batteries to study electrochemical-mechanical interaction phenomena at macro- and micro-scales. The battery model consists of a lithium foil anode, a separator, and a porous cathode ... Keywords: Finite element method, Homogenization, Multi-scale modeling, Porous electrode theory

Stephanie Golmon; Kurt Maute; Martin L. Dunn

2009-12-01T23:59:59.000Z

212

Development of a model to calculate mechanical specific energy for air hammer drilling systems  

E-Print Network (OSTI)

Drilling for hydrocarbons is an expensive operation; consequently operators try to save costs by reducing the number of days spent during this operation. Drilling efficiently with the highest attainable rate of penetration is one of the ways drilling time could be reduced. Real-time monitoring of Mechanical Specific Energy will enable drilling engineers to detect when the optimum drilling rate for a given set of drilling parameters is not being achieved. Numerous works have been done on air hammers and rock Mechanical Specific Energy. Previous research has shown that Mechanical Specific Energy, which is a ratio that quantifies the input energy and Rate of Penetration (ROP) of a drilling system, is directly proportional to the rock compressive strength being drilled. The Mechanical Specific Energy model utilizes drilling parameters such as ROP, Weight on bit (WOB), RPM, torque, flow-rate, bottom-hole pressure, and bottom-hole temperature to show how effectively energy being put into the drill string is being converted to ROP at the bit. This research effort proposes a new model to calculate the Mechanical Specific Energy for air hammer drilling systems. A thermodynamic model for the air hammer from which the piston impact velocity and kinetic energy is obtained is presented. To be able to estimate the effective energy delivered to the rock by the hammer, the stress wave propagation model is used and factored into the Mechanical Specific Energy model. The Mechanical Specific Energy values obtained from the application of this model provide a qualitative indicator of formation pressure changes and a means for drilling engineers to detect when optimum drilling rate is not being achieved. It can be deduced from the model that the impact energy of the hammer is greatly affected by the pressure drop across the hammer and since the hammer accounts for about sixty percent of the energy required for destroying the rock, the ROP can be varied by varying the pressure drop across the hammer.

Okuchaba, Boma Jeremiah

2008-05-01T23:59:59.000Z

213

How to Fit simply Soil Mechanics Behaviour with Incremental Modelling and to Describe Drained Cyclic Behaviours  

E-Print Network (OSTI)

It has been proposed recently a new incremental modelling to describe the mechanics of soil. It is based on two parameters called the pseudo Young modulus E=1/Co and the pseudo Poisson coefficient n, which both evolve during compression. Evolution of n is known since it shall fit the Rowe's law of dilatancy, but Co has to be evaluated from experiment. In this paper we proposed a way to evaluate the Co variation from other mechanical modelling. The way cyclic behaviour of drained sample can be modelled is also described.

P. Evesque

2005-07-04T23:59:59.000Z

214

Diffusion and Numerical Filters  

Science Conference Proceedings (OSTI)

Applications of low-pass filters or implicit diffusion are found to be extremely beneficial in a simple model problem that contains an oven-ordered advection scheme based on a symmetric stencil. In contrast, the effects are negative when either ...

William H. Raymond

1994-04-01T23:59:59.000Z

215

Diffusion bonding  

SciTech Connect

1. A method for joining beryllium to beryllium by diffusion bonding, comprising the steps of coating at least one surface portion of at least two beryllium pieces with nickel, positioning a coated surface portion in a contiguous relationship with an other surface portion, subjecting the contiguously disposed surface portions to an environment having an atmosphere at a pressure lower than ambient pressure, applying a force upon the beryllium pieces for causing the contiguous surface portions to abut against each other, heating the contiguous surface portions to a maximum temperature less than the melting temperature of the beryllium, substantially uniformly decreasing the applied force while increasing the temperature after attaining a temperature substantially above room temperature, and maintaining a portion of the applied force at a temperature corresponding to about maximum temperature for a duration sufficient to effect the diffusion bond between the contiguous surface portions.

Anderson, Robert C. (Oak Ridge, TN)

1976-06-22T23:59:59.000Z

216

On the Mechanical Response of Chopped Glass/Urethane Resin Composite: Data and Model  

SciTech Connect

This report presents data on the creep response of a polymeric composite that is a candidate material for automotive applications. The above data were used to establish the basis for the mechanical characterization of the material's response over a wide range of stresses and temperatures, as well as under cyclic loading and due to exposure to distilled water. A constitutive model based upon fundamental principles of irreversible thermodynamics and continuum mechanics was employed to encompass the above mentioned database and to predict the response under more complex inputs. These latter tests verified the validity of the model.

Elahi, M.; Weitsman, Y.J.

1999-11-01T23:59:59.000Z

217

Information Technology Diffusion with Influentials, Imitators, and Opponents  

Science Conference Proceedings (OSTI)

Information technology (IT) innovations follow a diverse set of diffusion patterns. Early diffusion models explaining technology diffusion patterns assumed that there is a single homogeneous segment of potential adopters. It was later shown that a two-segment ... Keywords: Diffusion Of Innovation, Information Technology Diffusion, Technology Opposition

Hasan Cavusoglu; Nan Hu; Yingjiu Li; Dan Ma

2010-10-01T23:59:59.000Z

218

Statistical Mechanics of Image Restoration by the Plane Rotator Model Yo^hei SAIKA and Hidetoshi NISHIMORI1  

E-Print Network (OSTI)

Statistical Mechanics of Image Restoration by the Plane Rotator Model Yo^hei SAIKA and Hidetoshi) On the basis of statistical mechanics formulation for problems of image restoration and error- correcting codes image is faster than that by the Ising model at low temperature. KEYWORDS: statistical mechanics, image

Nishimori, Hidetoshi

219

Assessment of RANS-based turbulent combustion models for prediction of gas turbine emissions: turbulence model and reaction mechanism effects  

DOE Green Energy (OSTI)

The goal of this study is to assess current, commonly applied turbulence and combustion models with respect to their performance in gas-turbine combustion (GTC). Reynolds Averaged Navier-Stokes (RANS)-based turbulence and chemistry models are two primary factors influencing the uncertainty in predicting turbulent combustion characteristics, especially for GTC. RANS-based methods are the design tools of choice in the gas turbine industry due to the high computational costs of LES (Large Eddy Simulation). In this study, lean premixed combustion of methane was simulated using two different reduced mechanisms (ARM9 and ARM19) along with the Eddy Dissipation Concept (EDC) turbulent chemistry interaction model to calculate the CO and NOx emissions. The effect of turbulence models was assessed by considering two different models. Both of the models tested performed well in the prediction of temperature and major species profiles. Predicted values of NO emission profiles showed an average difference of ±5 ppm compared to experimental values. Computed intermediate species profiles showed large qualitative and quantitative errors when compared with the experimental data. These discrepancies, especially the intermediate species hydrogen, indicate the challenges these reduced mechanisms and turbulence models can present when modeling pollutant emissions from gas turbine combustors.

Nanduri, J.R.; Celik, I.B.; Strakey, P.A.; Parsons, D.R.

2007-10-01T23:59:59.000Z

220

Simple solar spectral model for direct and diffuse irradiance on horizontal and tilted planes at the earth's surface for cloudless atmospheres  

DOE Green Energy (OSTI)

A new, simple model for calculating clear-sky direct and diffuse spectral irradiance on horizontal and tilted surfaces is presented. The model is based on previously reported simple algorithms and on comparisons with rigorous radiative transfer calculations and limited outdoor measurements. Equations for direct normal irradiance are outlined; and include: Raleigh scattering; aerosol scattering and absorption; water vapor absorption; and ozone and uniformly mixed gas absorption. Inputs to the model include solar zenith angle, collector tilt angle, atmospheric turbidity, amount of ozone and precipitable water vapor, surface pressure, and ground albedo. The model calculates terrestrial spectra from 0.3 to 4.0 ..mu..m with approximately 10 nm resolution. A major goal of this work is to provide researchers with the capability to calculate spectral irradiance for different atmospheric conditions and different collector geometries using microcomputers. A listing of the computer program is provided.

Bird, R.; Riordan, C.

1984-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "diffusion mechanisms 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 model for DNA helicase mechanism based on a flashing ratchet  

E-Print Network (OSTI)

Helicases are molecular motors that consume energy supplied by chemical reactions to unwind double-stranded nucleic acids (like DNA and RNA) and to translocate along one of the single-strands. Motivated by the recent claims, based on experimental observations on the helicase NS3 of hepatitis C virus (HCV), that monomeric helicases are governed by a Brownian ratchet mechanism, here we develope a quantitative model. Our Brownian ratchet model, which is a somewhat new reformulation of the Betterton-J\\"ulicher theory of helicases, is generic two-state model and is applicable to all helicases which follow the Brownian ratchet mechanism. We illustrate the predictive power of the model by calculating some experimentally testable motor properties of a few monomeric helicases. Speficically, we predict the speed of unwinding of the double-stranded DNA and fluctuations around the average drift of the helicase. Our predictions are in excellent quantitative agreement with the corresponding experimental data.

Garai, Ashok; Chowdhury, Debashish

2007-01-01T23:59:59.000Z

222

BEAM DIFFUSION MEASUREMENTS AT RHIC.  

Science Conference Proceedings (OSTI)

During a store, particles from the beam core continually diffuse outwards into the halo through a variety of mechanisms. Understanding the diffusion rate as a function of particle amplitude can help discover which processes are important to halo growth. A collimator can be used to measure the amplitude growth rate as a function of the particle amplitude. In this paper we present results of diffusion measurements performed at the Relativistic Heavy Ion Collider (RHIC) with fully stripped gold ions, deuterons, and protons. We compare these results with measurements from previous years, and simulations, and discuss any factors that relate to beam growth in RHIC.

FLILLER,R.P.,IIIDREES,A.GASSNER,D.MCINTYRE,G.PEGGS,S.TRBOJEVIC,D.

2003-05-12T23:59:59.000Z

223

Simulating flame lift-off characteristics of diesel and biodiesel fuels using detailed chemical-kinetic mechanisms and LES turbulence model.  

DOE Green Energy (OSTI)

Combustion in direct-injection diesel engines occurs in a lifted, turbulent diffusion flame mode. Numerous studies indicate that the combustion and emissions in such engines are strongly influenced by the lifted flame characteristics, which are in turn determined by fuel and air mixing in the upstream region of the lifted flame, and consequently by the liquid breakup and spray development processes. From a numerical standpoint, these spray combustion processes depend heavily on the choice of underlying spray, combustion, and turbulence models. The present numerical study investigates the influence of different chemical kinetic mechanisms for diesel and biodiesel fuels, as well as Reynolds-averaged Navier-Stokes (RANS) and large eddy simulation (LES) turbulence models on predicting flame lift-off lengths (LOLs) and ignition delays. Specifically, two chemical kinetic mechanisms for n-heptane (NHPT) and three for biodiesel surrogates are investigated. In addition, the RNG k-{epsilon} (RANS) model is compared to the Smagorinsky based LES turbulence model. Using adaptive grid resolution, minimum grid sizes of 250 {micro}m and 125 {micro}m were obtained for the RANS and LES cases respectively. Validations of these models were performed against experimental data from Sandia National Laboratories in a constant volume combustion chamber. Ignition delay and flame lift-off validations were performed at different ambient temperature conditions. The LES model predicts lower ignition delays and qualitatively better flame structures compared to the RNG k-{epsilon} model. The use of realistic chemistry and a ternary surrogate mixture, which consists of methyl decanoate, methyl 9-decenoate, and NHPT, results in better predicted LOLs and ignition delays. For diesel fuel though, only marginal improvements are observed by using larger size mechanisms. However, these improved predictions come at a significant increase in computational cost.

Som, S; Longman, D. E.; Luo, Z; Plomer, M; Lu, T; Senecal, P.K.; Pomraning, E (Energy Systems); (Univ. of Connecticut); (CONVERGENT Science)

2012-01-01T23:59:59.000Z

224

Analysis and Application of Sheppard’s Airflow Model to Predict Mechanical Orographic Lifting and the Occurrence of Mountain Clouds  

Science Conference Proceedings (OSTI)

Mechanically driven orographic lifting is important for air pollution dispersion and weather prediction, but the small dimensions of mountain peaks often prevent numerical weather models from producing detailed forecasts. Mechanical lifting in ...

Jan Kleissl; Richard E. Honrath; Diamantino V. Henriques

2006-10-01T23:59:59.000Z

225

Comparison of problem model change mechanisms issued from CSP and TRIZ  

E-Print Network (OSTI)

1 Comparison of problem model change mechanisms issued from CSP and TRIZ RRoollaanndd DDee GGuuiioo satisfaction problem (CSP), on the other hand. Keywords: over-constrained problems, dialectical methods issued from CSP and TRIZ 2 · a set of evaluation parameters, which represent the objective of the problem

Paris-Sud XI, Université de

226

Mechanics of complex bodies: commentary on the unified modelling of material substructures  

E-Print Network (OSTI)

Basic issues of the general model-building framework of the mechanics of complex bodies are discussed. Attention is focused on the representation of the material elements, the conditions for the existence of ground states in conservative setting and the interpretation of the nature of the various balance laws occurring.

Paolo Maria Mariano

2008-03-26T23:59:59.000Z

227

D-eigenvalues of diffusion kurtosis tensors  

Science Conference Proceedings (OSTI)

Diffusion kurtosis imaging (DKI) is a new model in medical engineering, where a diffusion kurtosis (DK) tensor is involved. A DK tensor is a fourth-order three-dimensional fully symmetric tensor. In this paper, we introduce D-eigenvalues for a DK tensor. ... Keywords: Computation, Diffusion kurtosis, Eigenvalues, Tensors

Liqun Qi; Yiju Wang; Ed X. Wu

2008-11-01T23:59:59.000Z

228

Numerical Classical and Quantum Mechanical simulations of Charge Density wave models  

E-Print Network (OSTI)

We first present how to do a computer simulation of Charge Density Waves using a driven harmonic oscillator model by a numerical scheme as initially formulated by Littlewood, and then afterwards use this to present how the dielectric model as presented by this proceedure leads to a blow up at the initialization of a threshold field ET. We find that this is highly unphysical and this initiated our inquiry as to alternative models. Afterwards, we then investigate hwo to present this transport problem of CDW quantum mechanically, threough a numerical simulation of the massive Schwinger model. We find that this single chaing quantum mechanical simulation uwed to formulate solutions to CDW transport in itself is insufficient for transport of solitons(anti-solitons) through a pinning gap model of CDW. We show that a model Hamiltonian with Peierls condensation energy used to couple adjacent chains (or transverse wave vectors) permits formation of solitons (anti- solitons) which can be used to transport CDW through a potential barrier. This addition of the Peierls condensation energy term is essential for any quantum model of Charge Density Waves to give tunneling behavior as seen via a numerical simulation.

A. W. Beckwith

2004-09-13T23:59:59.000Z

229

Physical and chemical comparison of soot in hydrocarbon and biodiesel fuel diffusion flames: A study of model and commercial fuels  

Science Conference Proceedings (OSTI)

Data are presented to compare soot formation in both surrogate and practical fatty acid methyl ester biodiesel and petroleum fuel diffusion flames. The approach here uses differential mobility analysis to follow the size distributions and electrical charge of soot particles as they evolve in the flame, and laser ablation particle mass spectrometry to elucidate their composition. Qualitatively, these soot properties exhibit a remarkably similar development along the flames. The size distributions begin as a single mode of precursor nanoparticles, evolve through a bimodal phase marking the onset of aggregate formation, and end in a self preserving mode of fractal-like particles. Both biodiesel and hydrocarbon fuels yield a common soot composition dominated by C{sub x}H{sub y}{sup +} ions, stabilomer PAHs, and fullerenes in the positive ion mass spectrum, and C{sub x}{sup -} and C{sub 2x}H{sup -} in the negative ion spectrum. These ion intensities initially grow with height in the diffusion flames, but then decline during later stages, consistent with soot carbonization. There are important quantitative differences between fuels. The surrogate biodiesel fuel methyl butanoate substantially reduces soot levels, but soot formation and evolution in this flame are delayed relative to both soy and petroleum fuels. In contrast, soots from soy and hexadecane flames exhibit nearly quantitative agreement in their size distribution and composition profiles with height, suggesting similar soot precursor chemistry. (author)

Matti Maricq, M. [Research and Advanced Engineering, Ford Motor Company, Dearborn, MI (United States)

2011-01-15T23:59:59.000Z

230

THE DETONATION MECHANISM OF THE PULSATIONALLY ASSISTED GRAVITATIONALLY CONFINED DETONATION MODEL OF Type Ia SUPERNOVAE  

Science Conference Proceedings (OSTI)

We describe the detonation mechanism composing the 'pulsationally assisted' gravitationally confined detonation (GCD) model of Type Ia supernovae. This model is analogous to the previous GCD model reported in Jordan et al.; however, the chosen initial conditions produce a substantively different detonation mechanism, resulting from a larger energy release during the deflagration phase. The resulting final kinetic energy and {sup 56}Ni yields conform better to observational values than is the case for the 'classical' GCD models. In the present class of models, the ignition of a deflagration phase leads to a rising, burning plume of ash. The ash breaks out of the surface of the white dwarf, flows laterally around the star, and converges on the collision region at the antipodal point from where it broke out. The amount of energy released during the deflagration phase is enough to cause the star to rapidly expand, so that when the ash reaches the antipodal point, the surface density is too low to initiate a detonation. Instead, as the ash flows into the collision region (while mixing with surface fuel), the star reaches its maximally expanded state and then contracts. The stellar contraction acts to increase the density of the star, including the density in the collision region. This both raises the temperature and density of the fuel-ash mixture in the collision region and ultimately leads to thermodynamic conditions that are necessary for the Zel'dovich gradient mechanism to produce a detonation. We demonstrate feasibility of this scenario with three three-dimensional (3D), full star simulations of this model using the FLASH code. We characterized the simulations by the energy released during the deflagration phase, which ranged from 38% to 78% of the white dwarf's binding energy. We show that the necessary conditions for detonation are achieved in all three of the models.

Jordan, G. C. IV; Graziani, C.; Weide, K.; Norris, J.; Hudson, R.; Lamb, D. Q. [Flash Center for Computational Science, University of Chicago, Chicago, IL 60637 (United States); Fisher, R. T. [Department of Physics, University of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA 02740 (United States); Townsley, D. M. [Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL 35487 (United States); Meakin, C. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Reid, L. B. [NTEC Environmental Technology, Subiaco WA 6008 (Australia)

2012-11-01T23:59:59.000Z

231

An improved oxygen diffusion model to explain the effect of low-temperature baking on high field losses in niobium superconducting cavities  

SciTech Connect

Radio-frequency (RF) superconducting cavities made of high purity niobium are widely used to accelerate charged particle beams in particle accelerators. The major limitation to achieve RF field values approaching the theoretical limit for niobium is represented by ''anomalous'' losses which degrade the quality factor of the cavities starting at peak surface magnetic fields of about 100 mT, in absence of field emission. These high field losses are often referred to as ''Q-drop''. It has been observed that the Q-drop is drastically reduced by baking the cavities at 120 C for about 48 h under ultrahigh vacuum. An improved oxygen diffusion model for the niobium-oxide system is proposed to explain the benefit of the low-temperature baking on the Q-drop in niobium superconducting rf cavities. The model shows that baking at 120 C for 48 h allows oxygen to diffuse away from the surface, and therefore increasing the lower critical field towards the value for pure niobium.

Gianluigi Ciovati

2005-09-15T23:59:59.000Z

232

Statistical-mechanical lattice models for protein-DNA binding in chromatin  

E-Print Network (OSTI)

Statistical-mechanical lattice models for protein-DNA binding are well established as a method to describe complex ligand binding equilibriums measured in vitro with purified DNA and protein components. Recently, a new field of applications has opened up for this approach since it has become possible to experimentally quantify genome-wide protein occupancies in relation to the DNA sequence. In particular, the organization of the eukaryotic genome by histone proteins into a nucleoprotein complex termed chromatin has been recognized as a key parameter that controls the access of transcription factors to the DNA sequence. New approaches have to be developed to derive statistical mechanical lattice descriptions of chromatin-associated protein-DNA interactions. Here, we present the theoretical framework for lattice models of histone-DNA interactions in chromatin and investigate the (competitive) DNA binding of other chromosomal proteins and transcription factors. The results have a number of applications for quant...

Teif, Vladimir B

2010-01-01T23:59:59.000Z

233

Radiometric Modeling of Mechanical Draft Cooling Towers to Assist in the Extraction of their Absolute Temperature from  

E-Print Network (OSTI)

Radiometric Modeling of Mechanical Draft Cooling Towers to Assist in the Extraction108, Aiken, SC, USA ABSTRACT Determining the internal temperature of a mechanical draft cooling tower is to estimate the temperature of the air exiting a mechanical draft cooling tower (MDCT) through the use

Salvaggio, Carl

234

Multi-level assembly model for top-down design of mechanical products  

Science Conference Proceedings (OSTI)

To enable next generation CAD tools to effectively support top-down design of products, a top-down assembly design process is refined from the traditional product design process to better exhibit the recursive-execution and structure-evolvement characteristics ... Keywords: Inheritance mechanism, Layout skeleton, Multi-level assembly model, Shape skeleton, Skeleton feature, Skeleton interface, Top-down assembly design, Top-down component design

Xiang Chen; Shuming Gao; Youdong Yang; Shuting Zhang

2012-10-01T23:59:59.000Z

235

Eddy diffusion  

E-Print Network (OSTI)

Perhaps you have heard that turbulence is the most difficult problem in fluid mechanics and, according to some, the greatest unsolved problem in physics. One indication of the difficulty is that it is impossible to give a satisfactory definition of a “turbulent flow”. But everyone agrees that one

unknown authors

2000-01-01T23:59:59.000Z

236

A numerical model of hydro-thermo-mechanical coupling in a fractured rock mass  

DOE Green Energy (OSTI)

Coupled hydro-thermo-mechanical codes with the ability to model fractured materials are used for predicting groundwater flow behavior in fractured aquifers containing thermal sources. The potential applications of such a code include the analysis of groundwater behavior within a geothermal reservoir. The capability of modeling hydro-thermo systems with a dual porosity, fracture flow model has been previously developed in the finite element code, FEHM. FEHM has been modified to include stress coupling with the dual porosity feature. FEHM has been further developed to implicitly couple the dependence of fracture hydraulic conductivity on effective stress within two dimensional, saturated aquifers containing fracture systems. The cubic law for flow between parallel plates was used to model fracture permeability. The Bartin-Bandis relationship was used to determine the fracture aperture within the cubic law. The code used a Newton Raphson iteration to implicitly solve for six unknowns at each node. Results from a model of heat flow from a reservoir to the moving fluid in a single fracture compared well with analytic results. Results of a model showing the increase in fracture flow due to a single fracture opening under fluid pressure compared well with analytic results. A hot dry rock, geothermal reservoir was modeled with realistic time steps indicating that the modified FEHM code does successfully model coupled flow problems with no convergence problems.

Bower, K.M.

1996-06-01T23:59:59.000Z

237

Model development and calibration for the coupled thermal, hydraulic and mechanical phenomena of the bentonite  

E-Print Network (OSTI)

FOR THE COUPLED THERMAL, HYDRAULIC AND MECHANICAL PHENOMENAby the interdependence of thermal, hydraulic and mechanical

Hernelind, J.

2009-01-01T23:59:59.000Z

238

Predictions of particle size and lattice diffusion pathway requirements for sodium-ion anodes using eta-Cu6Sn5 thin films as a model system  

SciTech Connect

Geometrically well-defined Cu6Sn5 thin films were used as model systems to estimate the diffusion depth and diffusion pathway requirements of Li and Na ions in alloy anodes. eta-Cu6Sn5 anodes have an initial reversible capacity towards Li of 545 mAh g-1 (Li3.96Sn or 19.8 Li/Cu6Sn5) and a very low initial irreversible capacity of 1.6 Li/Cu6Sn5. In contrast, the reaction with Na is limited with a reversible capacity of 160 mAh g-1 compared to the expected 516 mAh g-1. The potential profile is analogous to that of pure Sn with an average potential of 0.3 V. X-ray diffraction and 119Sn-M ssbauer measurements show that this limited capacity is likely resulting from the limited diffusion of Na into the anode particles not the formation of a low Na-content phase. This is substantiated by the analysis of the structure of eta-Cu6Sn5 which revealed zig-zag and tunnel diffusion pathways with spherical voids with a diameter very close to that of Na+. Moreover, our results also indicate that an alloy of eta-Cu6Sn5 should have optimized particle sizes of about 10 nm in diameter to increase the Na-capacity significantly. An alternative system consisting of a mixture of Cu6Sn5 and Sn of nominal composition Cu6Sn10 has been studied as possible Na-ion anode material possessing higher storage capacity than pure Cu6Sn5. Indeed this mixture of phase delivers a larger initial reversible storage capacity up to 400 mAh g-1. Finally, we have evidenced that the presence of Cu in Cu6Sn5 and in Cu6Sn10 suppresses the anomalous electrolyte decomposition normally measured for pure Sn at 1.2 V during discharge.

Baggetto, Loic [ORNL; Jumas, Dr. Jean-Claude [Institut Charles Gerhardt, University of Montpellier II, FRANCE; Gorka, Joanna [ORNL; Bridges, Craig A [ORNL; Veith, Gabriel M [ORNL

2013-01-01T23:59:59.000Z

239

Orientational relaxation in a dispersive dynamic medium : Generalization of the Kubo-Ivanov-Anderson jump diffusion model to include fractional environmental dynamics  

E-Print Network (OSTI)

Ivanov-Anderson (IA) model (and an earlier treatment by Kubo) envisages a decay of the orientational correlation by random but large amplitude molecular jumps, as opposed to infinitesimal small jumps assumed in Brownian diffusion. Recent computer simulation studies on water and supercooled liquids have shown that large amplitude motions may indeed be more of a rule than exception. Existing theoretical studies on jump diffusion mostly assume an exponential (Poissonian) waiting time distribution for jumps, thereby again leading to an exponential decay. Here we extend the existing formalism of Ivanov and Anderson to include an algebraic waiting time distribution between two jumps. As a result, the first and second rank orientational time correlation functions show the same long time power law, but their short time decay behavior is quite different. The predicted Cole-Cole plot of dielectric relaxation reproduces various features of non-Debye behaviour observed experimentally. We also developed a theory where both unrestricted small jumps and large angular jumps coexist simultaneously. The small jumps are shown to have a large effect on the long time decay, particularly in mitigating the effects of algebraic waiting time distribution, and in giving rise to an exponential-like decay, with a time constant, surprisingly, less than the time constant that arises from small amplitude decay alone.

K. Seki; B. Bagchi; M. Tachiya

2007-10-17T23:59:59.000Z

240

Parallel flow diffusion battery  

DOE Patents (OSTI)

A parallel flow diffusion battery for determining the mass distribution of an aerosol has a plurality of diffusion cells mounted in parallel to an aerosol stream, each diffusion cell including a stack of mesh wire screens of different density.

Yeh, Hsu-Chi (Albuquerque, NM); Cheng, Yung-Sung (Albuquerque, NM)

1984-08-07T23:59:59.000Z

Note: This page contains sample records for the topic "diffusion mechanisms 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.


241

Parallel flow diffusion battery  

DOE Patents (OSTI)

A parallel flow diffusion battery for determining the mass distribution of an aerosol has a plurality of diffusion cells mounted in parallel to an aerosol stream, each diffusion cell including a stack of mesh wire screens of different density.

Yeh, H.C.; Cheng, Y.S.

1984-01-01T23:59:59.000Z

242

Two-phase flow in a vertical pipe and the phenomenon of choking: Homogeneous diffusion model. Part I. Homogeneous flow models  

DOE Green Energy (OSTI)

The paper examines the topologic structure of all possible solutions which can exist in flows through adiabatic constant-area ducts for which the homogeneous diffusion model has been assumed. The conservation equations are one-dimensional with the single space variable z, but gravity effects are included. The conservation equations are coupled with three equations of state: a pure substance, a perfect gas with constant specific heats, and a homogeneous two-phase system in thermodynamic equilibrium. The preferred state variables are pressure P, enthalpy h, and mass flux G{sup 2}. The three conservation equations are first-order but nonlinear. They induce a family of solutions which are interpreted as curves in a four-dimensional phase space conceived as a union of three-dimensional spaces (h, G{sup 2};z) with G{sup 2} = const treated as a parameter. It is shown that all points in these spaces are regular, so that no singular solutions need to be considered. The existence and uniqueness theorem leads to the conclusion that through every point in phase space there passes one and only one solution-curve. The set of differential equations, treated as a system of algebraic equations at each point of the phase space, determines the components of a rate-of-change vector which are obtained explicitly by Cramer's rule. This vector is tangent to the solution curve. Each solution curve turns downward in z at some specific elevation z*, and this determines the condition for choking. Choking occurs always when the exit flow velocity at L=z* is equal to the local velocity of propagation of small plane disturbances of sufficiently large wavelength, that is when the flow rate G becomes equal to a specified, critical flow rate, G*. A criterion, analogous to the Mach number, which indicates the presence or absence of choking in a cross-section is the ratio K=G/G** of the mass-flow rate G to the local critical mass flow rate, G**, K=1 denoting choking. The critical parameters depend only on the thermodynamic properties of the fluid and are independent of the gravitational acceleration and shearing stress at the wall. The topological characteristics of the solutions allow us to study all flow patterns which can, and which cannot, occur in a pipe of given length L into which fluid is discharged through a rounded entrance from a stagnation reservoir and whose back-pressure is slowly lowered. The set of flow patterns is analogous to that which occurs with a perfect gas, except that the characteristic numerical values are different. They must be obtained by numerical integration and the influence of gravity must be allowed for. The preceding conclusions are valid for all assumptions concerning the shearing stress at the wall which make it dependent on the state parameters only, but not on their derivatives with respect to z. However, the study is limited to upward flows for which the shearing stress at the wall and the gravitational acceleration are codirectional.

Bilicki, Z.; Kestin, J.

1982-01-01T23:59:59.000Z

243

Determination of Electrochemical Performance and Thermo-Mechanical-Chemical Stability of SOFCs from Defect Modeling  

DOE Green Energy (OSTI)

This research was focused on two distinct but related issues. The first issue concerned using defect modeling to understand the relationship between point defect concentration and the electrochemical, thermo-chemical and mechano-chemical properties of typical solid oxide fuel cell (SOFC) materials. The second concerned developing relationships between the microstructural features of SOFC materials and their electrochemical performance. To understand the role point defects play in ceramics, a coherent analytical framework was used to develop expressions for the dependence of thermal expansion and elastic modulus on point defect concentration in ceramics. These models, collectively termed the continuum-level electrochemical model (CLEM), were validated through fits to experimental data from electrical conductivity, I-V characteristics, elastic modulus and thermo-chemical expansion experiments for (nominally pure) ceria, gadolinia-doped ceria (GDC) and yttria-stabilized zirconia (YSZ) with consistently good fits. The same values for the material constants were used in all of the fits, further validating our approach. As predicted by the continuum-level electrochemical model, the results reveal that the concentration of defects has a significant effect on the physical properties of ceramic materials and related devices. Specifically, for pure ceria and GDC, the elastic modulus decreased while the chemical expansion increased considerably in low partial pressures of oxygen. Conversely, the physical properties of YSZ remained insensitive to changes in oxygen partial pressure within the studied range. Again, the findings concurred exactly with the predictions of our analytical model. Indeed, further analysis of the results suggests that an increase in the point defect content weakens the attractive forces between atoms in fluorite-structured oxides. The reduction treatment effects on the flexural strength and the fracture toughness of pure ceria were also evaluated at room temperature. The results reveal that the flexural strength decreases significantly after heat treatment in very low oxygen partial pressure environments; however, in contrast, fracture toughness is increased by 30-40% when the oxygen partial pressure was decreased to 10{sup -20} to 10{sup -22} atm range. Fractographic studies show that microcracks developed at 800 oC upon hydrogen reduction are responsible for the decreased strength. To understand the role of microstructure on electrochemical performance, electrical impedance spectra from symmetric LSM/YSZ/LSM cells was de-convoluted to obtain the key electrochemical components of electrode performance, namely charge transfer resistance, surface diffusion of reactive species and bulk gas diffusion through the electrode pores. These properties were then related to microstructural features, such as triple-phase boundary length and tortuosity. From these experiments we found that the impedance due to oxygen adsorption obeys a power law with pore surface area, while the impedance due to charge transfer is found to obey a power-law with respect to triple phase boundary length. A model based on kinetic theory explaining the power-law relationships observed was then developed. Finally, during our EIS work on the symmetric LSM/YSZ/LSM cells a technique was developed to improve the quality of high-frequency impedance data and their subsequent de-convolution.

Eric Wachsman; Keith L. Duncan

2006-09-30T23:59:59.000Z

244

Thermo-Poroelastic Modeling of Reservoir Stimulation and Microseismicity Using Finite Element Method with Damage Mechanics  

E-Print Network (OSTI)

Stress and permeability variations around a wellbore and in the reservoir are of much interest in petroleum and geothermal reservoir development. Water injection causes significant changes in pore pressure, temperature, and stress in hot reservoirs, changing rock permeability. In this work, two- and three-dimensional finite element methods were developed to simulate coupled reservoirs with damage mechanics and stress-dependent permeability. The model considers the influence of fluid flow, temperature, and solute transport in rock deformation and models nonlinear behavior with continuum damage mechanics and stress-dependent permeability. Numerical modeling was applied to analyze wellbore stability in swelling shale with two- and three-dimensional damage/fracture propagation around a wellbore and injection-induced microseismic events. The finite element method (FEM) was used to solve the displacement, pore pressure, temperature, and solute concentration problems. Solute mass transport between drilling fluid and shale formation was considered to study salinity effects. Results show that shear and tensile failure can occur around a wellbore in certain drilling conditions where the mud pressure lies between the reservoir pore pressure and fracture gradient. The fully coupled thermo-poro-mechanical FEM simulation was used to model damage/fracture propagation and microseismic events caused by fluid injection. These studies considered wellbore geometry in small-scale modeling and point-source injection, assuming singularity fluid flux for large-scale simulation. Damage mechanics was applied to capture the effects of crack initiation, microvoid growth, and fracture propagation. The induced microseismic events were modeled in heterogeneous geological media, assuming the Weibull distribution functions for modulus and permeability. The results of this study indicate that fluid injection causes the effective stress to relax in the damage phase and to concentrate at the interface between the damage phase and the intact rock. Furthermore, induced-stress and far-field stress influence damage propagation. Cold water injection causes the tensile stress and affects the initial fracture and fracture propagation, but fracture initiation pressure and far-field stress are critical to create a damage/fracture plane, which is normal to the minimum far-field stress direction following well stimulation. Microseismic events propagate at both well scale and reservoir-scale simulation; the cloud shape of a microseismic event is affected by permeability anisotropy and far-field stress, and deviatoric horizontal far-field stress especially contributes to the localization of the microseismic cloud.

Lee, Sang Hoon

2011-12-01T23:59:59.000Z

245

Shortwave, Clear-sky Diffuse Irradiance in the 350 to 1050 nm Range: Comparison of Models with RSS Measurements at the Southern Great Plains ARM Site in September/October 2001  

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

Shortwave, Clear-Sky Diffuse Irradiance in the Shortwave, Clear-Sky Diffuse Irradiance in the 350 to 1050 nm Range: Comparison of Models with RSS Measurements at the Southern Great Plains ARM Site in September/October 2001 J. J. Michalsky, P. W. Kiedron, Q.-L. Min, and L. C. Harrison Atmospheric Sciences Research Center State University of New York Albany, New York J. J. Michalsky Surface Radiation Research Branch Air Resources Laboratory National Oceanic and Atmospheric Administration Boulder, Colorado Abstract A rotating shadowband spectroradiometer (RSS) operating in the spectral range between 350 to 1050 nm obtained measurements of direct and diffuse components of spectral irradiance during the first diffuse irradiance IOP in the autumn of 2001. Independent measurements of the primary inputs to spectral

246

2012 Diffusion Workshop Presentation  

Science Conference Proceedings (OSTI)

... Diffusion Studies in Mg-Al-Zn (N. Kulkarni, B. Warmack, J. Mundy, ORNL); Thermodynamics and Correlation Effects on Diffusion in Al-Ni Melts. ...

2012-12-05T23:59:59.000Z

247

Acceleration Mechanisms  

E-Print Network (OSTI)

Glossary I. Background and context of the subject II. Stochastic acceleration III. Resonant scattering IV. Diffusive shock acceleration V. DSA at multiple shocks VI. Applications of DSA VII. Acceleration by parallel electric fields VIII. Other acceleration mechanisms IX. Future directions X. Appendix: Quasilinear equations XI. Bibliography

Melrose, D B

2009-01-01T23:59:59.000Z

248

A new model for mixing by double-diffusive convection (semi-convection). II. The transport of heat and composition through layers  

E-Print Network (OSTI)

Regions of stellar and planetary interiors that are unstable according to the Schwarzschild criterion, but stable according to the Ledoux criterion, are subject to a form of oscillatory double-diffusive (ODD) convection often called "semi-convection". In this series of papers, we use an extensive suite of three-dimensional (3D) numerical simulations to quantify the transport of heat and composition by ODD convection, and ultimately propose a new 1D prescription that can be used in stellar and planetary structure and evolution models. The first paper in this series demonstrated that under certain conditions ODD convection spontaneously transitions from an initially homogeneously turbulent state into a staircase of convective layers, which results in a substantial increase in the transport of heat and composition. Here, we present simulations of ODD convection in this layered regime, we describe the dynamical behavior of the layers, and we derive empirical scaling laws for the transport through layered convecti...

Wood, Toby S; Stellmach, Stephan

2012-01-01T23:59:59.000Z

249

Contact Mechanics Modeling of Homogeneous and Layered Elastic-Plastic Media: Surface Roughness and Adhesion Effects  

E-Print Network (OSTI)

H. , 2003. Fracture mechanics analysis of thin coatingsK.L. , 1985. Contact Mechanics, Cambridge University Press,J. , Chaboche, J. L. , 1994. Mechanics of Solid Materials.

Song, Zhichao

2012-01-01T23:59:59.000Z

250

Physics and modeling of thermal flow and soil mechanics in unconsolidated porous media  

SciTech Connect

This paper describes a new formulation of nonlinear soil mechanics and multiphase thermal flow. The nonlinearites of the soil behavior and their interactions with fluid flow causing shear failure of the soil are the dominant features of the process. The numerical formulation of the coupled flow/stress solution model includes nonlinear compressibility and flow properties as functions of pressure, stress, and temperature; nonlinear, incremental, thermal poroelastic stress analysis; and shear or tensile failure and its effects on transport properties, porosity, and stress. An efficient sequential numerical scheme was developed. It is mass conservative and applicable to external coupling of existing simulators. The 1D examples show some startling new features of reservoir mechanics in unconsolidated media.

Settari, A. (Simtech Consulting Services Ltd. (US))

1992-02-01T23:59:59.000Z

251

Modeling of Plume Downwash and Enhanced Diffusion near Buildings: Comparison to Wind Tunnel Observations for in Arctic Industrial Site  

Science Conference Proceedings (OSTI)

The ability of a modified Industrial Source Complex model to simulate concentration distributions resulting from high wind speeds (neutral conditions) has been evaluated by comparison to data from a wind tunnel study of a Prudhoe Bay, AK oil-...

Alex Guenther; Brian Lamb; Ronald Petersen

1989-05-01T23:59:59.000Z

252

3D Modeling of Coupled Rock Deformation and Thermo-Poro-Mechanical Processes in Fractures  

E-Print Network (OSTI)

Problems involving coupled thermo-poro-chemo-mechanical processes are of great importance in geothermal and petroleum reservoir systems. In particular, economic power production from enhanced geothermal systems, effective water-flooding of petroleum reservoirs, and stimulation of gas shale reservoirs are significantly influenced by coupled processes. During such procedures, stress state in the reservoir is changed due to variation in pore fluid pressure and temperature. This can cause deformation and failure of weak planes of the formation with creation of new fractures, which impacts reservoir response. Incorporation of geomechanical factor into engineering analyses using fully coupled geomechanics-reservoir flow modeling exhibits computational challenges and numerical difficulties. In this study, we develop and apply efficient numerical models to solve 3D injection/extraction geomechanics problems formulated within the framework of thermo-poro-mechanical theory with reactive flow. The models rely on combining Displacement Discontinuity (DD) Boundary Element Method (BEM) and Finite Element Method (FEM) to solve the governing equations of thermo-poro-mechanical processes involving fracture/reservoir matrix. The integration of BEM and FEM is accomplished through direct and iterative procedures. In each case, the numerical algorithms are tested against a series of analytical solutions. 3D study of fluid injection and extraction into the geothermal reservoir illustrates that thermo-poro-mechanical processes change fracture aperture (fracture conductivity) significantly and influence the fluid flow. Simulations that consider joint stiffness heterogeneity show development of non-uniform flow paths within the crack. Undersaturated fluid injection causes large silica mass dissolution and increases fracture aperture while supersaturated fluid causes mineral precipitation and closes fracture aperture. Results show that for common reservoir and injection conditions, the impact of fully developed thermoelastic effect on fracture aperture tend to be greater compare to that of poroelastic effect. Poroelastic study of hydraulic fracturing demonstrates that large pore pressure increase especially during multiple hydraulic fracture creation causes effective tensile stress at the fracture surface and shear failure around the main fracture. Finally, a hybrid BEFEM model is developed to analyze stress redistribution in the overburden and within the reservoir during fluid injection and production. Numerical results show that fluid injection leads to reservoir dilation and induces vertical deformation, particularly near the injection well. However, fluid withdrawal causes reservoir to compact. The Mandel-Cryer effect is also successfully captured in numerical simulations, i.e., pore pressure increase/decrease is non-monotonic with a short time values that are above/below the background pore pressure.

Rawal, Chakra

2012-05-01T23:59:59.000Z

253

Subgrid-Scale Mixing in Climate Models: A Novel Look at Diffusion, Accuracy, Stability and Climate Sensitivity  

SciTech Connect

This project focuses on evaluating the role of subgrid-scale dissipation in the dynamical core of atmospheric models. All dynamical cores of atmospheric general circulation models (GCMs) employ some form of subgrid-scale dissipation, either explicitly specified or inherent in the chosen numerical schemes. The dissipation processes are needed to keep the simulation stable or to satisfy important physical properties, and the hope is that they capture and mimic in some poorly understood way the true processes at the unresolved subgrid scale. There is no physical basis that such dissipation can accomplish this. We originally posed a set of numerical test cases chosen or designed to isolate the role of the filters and fixers on both the dynamical variables (pressure, temperature, velocity, vorticity) and trace constituents. From these test case results, we synthesize the information to determine the impact of the subgrid-scale assumptions on weather and climate models.

Rood, Richard B; Jablonowski, Christiane

2012-10-31T23:59:59.000Z

254

Spherical diffusion of tritium from a point of release in a uniform unsaturated soil. A deterministic model for tritium migration in an arid disposal site  

SciTech Connect

Tritium (Tr), when released as tritiated water at a point in a uniform and relatively dry soil, redistributes in both the liquid and vapor phases. The flux density of Tr in the liquid will exceed that in the vapor phase provided the water content is greater than approximately 15% of the total soil porosity. Thus Tr redistribution must be modeled recognizing transfer ``in parallel`` in both phases. The authors use the diffusion equation cast in spherical coordinates to analyze this problem in order to provide a basis for design of field experiments, and to offer observations on the long term behavior of such systems. The solution of the diffusion equation permits calculation of the evolution of profiles of Tr concentration, within and external to the sphere of released solution, assuming the initial concentration within this sphere to be uniform. The authors also predict the rate of advance of the maximum of Tr as it advances, and attenuates, in the soil. Calculations for the case of 1 million Curies of Tr diluted in 1 liter of water and released at a depth of 20 meters, and 200 meters above the water table, are demonstrated. If the soil has an initial water volume fraction of 0.06 and total porosity of 0.3 they show, for example, that at 5 meters from the point of discharge, the Tr concentration increases to a maximum in 24 years and then slowly declines. That maximum is 1 Curie/liter. The concentration in the gas phase will be 5 orders-of-magnitude less than this. At 60 meters the maximum ever reached in the liquid phase is ca 10{sup {minus}21} Ci/liter; that maximum will be achieved after 408 years. The authors discuss the effects of variation in the volume fractions of water and air originally present in the soil on the effective diffusion coefficient of Tr in soil, consider the effects of a net flux of water in the system, and identify questions to be answered to achieve safe systematic disposal of tritium in the deep unsaturated zone of desert soil.

Smiles, D.E.; Gardner, W.R.; Schulz, R.K. [Univ. of California, Berkeley, CA (United States). Dept. of Environmental Science, Policy and Management

1993-10-01T23:59:59.000Z

255

DNA folding: structural and mechanical properties of the two-angle model for chromatin  

E-Print Network (OSTI)

We present a theoretical analysis of the structural and mechanical properties of the 30-nm chromatin fiber. Our study is based on the two-angle model introduced by Woodcock et al. (Woodcock, C. L., S. A. Grigoryev, R. A. Horowitz, and N. Whitaker. 1993. PNAS 90:9021-9025) that describes the chromatin fiber geometry in terms of the entry-exit angle of the nucleosomal DNA and the rotational setting of the neighboring nucleosomes with respect to each other. We explore analytically the different structures that arise from this building principle, and demonstrate that the geometry with the highest density is close to the one found in native chromatin fibers under physiological conditions. On the basis of this model we calculate mechanical properties of the fiber under stretching. We obtain expressions for the stress-strain characteristics which show good agreement with the results of recent stretching experiments (Cui, Y., and C. Bustamante. 2000. PNAS 97:127-132) and computer simulations (Katritch, V., C. Bustamante, and W. K. Olson. 2000. J. Mol. Biol. 295:29-40), and which provide simple physical insights into correlations between the structural and elastic properties of chromatin.

H. Schiessel; W. M. Gelbart; R. Bruinsma

2001-02-07T23:59:59.000Z

256

Bulk and surface controlled diffusion of fission gas atoms  

Science Conference Proceedings (OSTI)

Fission gas retention and release impact nuclear fuel performance by, e.g., causing fuel swelling leading to mechanical interaction with the clad, increasing the plenum pressure and reducing the gap thermal conductivity. All of these processes are important to understand in order to optimize operating conditions of nuclear reactors and to simulate accident scenarios. Most fission gases have low solubility in the fuel matrix, which is especially pronounced for large fission gas atoms such as Xe and Kr, and as a result there is a significant driving force for segregation of gas atoms to extended defects such as grain boundaries or dislocations and subsequently for nucleation of gas bubbles at these sinks. Several empirical or semi-empirical models have been developed for fission gas release in nuclear fuels, e.g. [1-6]. One of the most commonly used models in fuel performance codes was published by Massih and Forsberg [3,4,6]. This model is similar to the early Booth model [1] in that it applies an equivalent sphere to separate bulk UO{sub 2} from grain boundaries represented by the sphere circumference. Compared to the Booth model, it also captures trapping at grain boundaries, fission gas resolution and it describes release from the boundary by applying timedependent boundary conditions to the circumference. In this work we focus on the step where fission gas atoms diffuse from the grain interior to the grain boundaries. The original Massih-Forsberg model describes this process by applying an effective diffusivity divided into three temperature regimes. In this report we present results from density functional theory calculations (DFT) that are relevant for the high (D{sub 3}) and intermediate (D{sub 2}) temperature diffusivities of fission gases. The results are validated by making a quantitative comparison to Turnbull's [8-10] and Matzke's data [12]. For the intrinsic or high temperature regime we report activation energies for both Xe and Kr diffusion in UO{sub 2{+-}x}, which compare favorably to available experiments. This is an extension of previous work [13]. In particular, it applies improved chemistry models for the UO{sub 2{+-}x} nonstoichiometry and its impact on the fission gas activation energies. The derivation of these models follows the approach that used in our recent study of uranium vacancy diffusion in UO{sub 2} [14]. Also, based on the calculated DFT data we analyze vacancy enhanced diffusion mechanisms in the intermediate temperature regime. In addition to vacancy enhanced diffusion we investigate species transport on the (111) UO{sub 2} surface. This is motivated by the formation of small voids partially filled with fission gas atoms (bubbles) in UO{sub 2} under irradiation, for which surface diffusion could be the rate-limiting transport step. Diffusion of such bubbles constitutes an alternative mechanism for mass transport in these materials.

Andersson, Anders D. [Los Alamos National Laboratory

2012-08-09T23:59:59.000Z

257

Ions and Precipitation Charging in Warm and Cold Clouds as Simulated in One-Dimensional Time-Dependent Models  

Science Conference Proceedings (OSTI)

One-dimensional time-dependent models of warm and cold clouds were constructed to test the electrical and precipitation development in the presence of a variety of charge separation mechanisms. The, models simulate charging by ion diffusion, the ...

I. Tzur; Z. Levin

1981-11-01T23:59:59.000Z

258

Microfabricated diffusion source  

DOE Patents (OSTI)

A microfabricated diffusion source to provide for a controlled diffusion rate of a vapor comprises a porous reservoir formed in a substrate that can be filled with a liquid, a headspace cavity for evaporation of the vapor therein, a diffusion channel to provide a controlled diffusion of the vapor, and an outlet to release the vapor into a gas stream. The microfabricated diffusion source can provide a calibration standard for a microanalytical system. The microanalytical system with an integral diffusion source can be fabricated with microelectromechanical systems technologies.

Oborny, Michael C. (Albuquerque, NM); Frye-Mason, Gregory C. (Cedar Crest, NM); Manginell, Ronald P. (Albuquerque, NM)

2008-07-15T23:59:59.000Z

259

Progress Report for Diffusion Welding of the NGNP Process Application Heat Exchangers  

DOE Green Energy (OSTI)

The U.S. Department of Energy selected the high temperature gas-cooled reactor as the basis for the Next Generation Nuclear Plant (NGNP). The NGNP will demonstrate the use of nuclear power for electricity, hydrogen production, and process heat applications. The NGNP Project is currently investigating the use of metallic, diffusion welded, compact heat exchangers to transfer heat from the primary (reactor side) heat transport system to the secondary heat transport system. An intermediate heat exchanger will transfer this heat to downstream applications such as hydrogen production, process heat, and electricity generation. The channeled plates that make up the heat transfer surfaces of the intermediate heat exchanger will have to be assembled into an array by diffusion welding. This report describes the preliminary results of a scoping study that evaluated the diffusion welding process parameters and the resultant mechanical properties of diffusion welded joints using Alloy 800H. The long-term goal of the program is to progress towards demonstration of small heat exchanger unit cells fabricated with diffusion welds. Demonstration through mechanical testing of the unit cells will support American Society of Mechanical Engineers rules and standards development, reduce technical risk, and provide proof of concept for heat exchanger fabrication methods needed to deploy heat exchangers in several potential NGNP configurations.1 Researchers also evaluated the usefulness of modern thermodynamic and diffusion computational tools (Thermo-Calc and Dictra) in optimizing the parameters for diffusion welding of Alloy 800H. The modeling efforts suggested a temperature of 1150 C for 1 hour with an applied pressure of 5 MPa using 15 {micro}m nickel foil as joint filler to reduce chromium oxidation on the welded surfaces. Good agreement between modeled and experimentally determined concentration gradients was achieved

R.E. Mizia; D.E. Clark; M.V. Glazoff; T.E. Lister; T.L. Trowbridge

2011-12-01T23:59:59.000Z

260

Diffusive separation of noble gases and noble gas abundance patterns in sedimentary rocks  

SciTech Connect

The mechanisms responsible for noble gas concentrations, abundance patterns, and strong retentivity in sedimentary lithologies remain poorly explained. Diffusion-controlled fractionation of noble gases is modeled and examined as an explanation for the absolute and relative abundances of noble gases observed in sediments. Since the physical properties of the noble gases are strong functions of atomic mass, the individual diffusion coefficients, adsorption coefficients and atomic radii combine to impede heavy noble gas (Xe) diffusion relative to light noble gas (Ne) diffusion. Filling of lithic grains/half-spaces by diffusive processes thus produces Ne enrichments in the early and middle stages of the filling process with F(Ne) values similar to that observed in volcanic glasses. Emptying lithic grains/half-spaces produces a Xe-enriched residual in the late (but not final) stages of the process producing F(Xe) values similar to that observed in shales. 'Exotic but unexceptional' shales that exhibit both F(Ne) and F(Xe) enrichments can be produced by incomplete emptying followed by incomplete filling. This mechanism is consistent with literature reported noble gas abundance patterns but may still require a separate mechanism for strong retention. A system of labyrinths-with-constrictions and/or C-, Si-nanotubes when combined with simple adsorption can result in stronger diffusive separation and non-steady-state enrichments that persist for longer times. Enhanced adsorption to multiple C atoms inside C-nanotubes as well as dangling functional groups closing the ends of nanotubes can provide potential mechanisms for 'strong retention'. We need new methods of examining noble gases in rocks to determine the role and function of angstrom-scale structures in both the diffusive enrichment process and the 'strong retention' process for noble gas abundances in terrestrial rocks.

Torgersen, T.; Kennedy, B.M.; van Soest, M.C.

2004-06-14T23:59:59.000Z

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261

Coupled elastic-plastic thermomechanically assisted diffusion: Theory development, numerical implementation, and application  

Science Conference Proceedings (OSTI)

A fully coupled thermomechanical diffusion theory describing the thermal and mechanically assisted mass transport of dilute mobile constituents in an elastic solid is extended to include the effects of elastic-plastic deformation. Using the principles of modern continuum mechanics and classical plasticity theory, balance laws and constitutive equations are derived for a continuum composed of an immobile, but deformable, parent material and a dilute mobile constituent. The resulting equations are cast into a finite element formulation for incorporation into a finite element code. This code serves as a tool for modeling thermomechanically assisted phenomena in elastic-plastic solids. A number of simplified problems for which analytical solutions can be derived are used to benchmark the theory and finite element code. Potential uses of the numerical implementation of the theory are demonstrated using two problems. Specifically, tritium diffusion in a titanium alloy and hydrogen diffusion in a multiphase stainless steel are examined.

Weinacht, D.J.

1995-12-01T23:59:59.000Z

262

Oceanographic implications of Laboratory Experiments on Diffusive Interfaces  

Science Conference Proceedings (OSTI)

This paper contains a summary of the results from some laboratory and theoretical studies on the diffusive interface in double diffusive convection, paying particular attention to the recent work of Fernando. A simple model is developed which ...

Harindra J. S. Fernando

1989-11-01T23:59:59.000Z

263

THE MULTIGROUP DIFFUSION EQUATIONS OF REACTOR PHYSICS  

SciTech Connect

The partial differential equations of the multigroup diffusion model of reactor physics are shown to have solutions both in the time-independent and timedependent problems, and the usually assumed behavior of these solutions is shown to be mathematically valid. The method of spectral representation is developed for the multigroup diffusion operator. (auth)

Habetler, G.J.; Martino, M.A.

1958-07-28T23:59:59.000Z

264

Patents and the diffusion of technical information  

E-Print Network (OSTI)

Abstract: Does the disclosure requirement of the patent system encourage the diffusion of inventions? This paper builds a simple model where firms choose between patents and trade secrecy to protect inventions. Diffusion is not necessarily more likely with a patent system nor is the “market for technology ” necessarily greater.

James Bessen; Thanks To Ashish Arora; Robert Barr; Nancy Gallini; Wendy Gordon; Mark Lemley; Mike Meurer

2005-01-01T23:59:59.000Z

265

ENHANCING THE ATOMIC-LEVEL UNDERSTANDING OF CO2 MINERAL SEQUESTRATION MECHANISMS VIA ADVANCED COMPUTATIONAL MODELING  

SciTech Connect

Fossil fuels currently provide 85% of the world's energy needs, with the majority coming from coal, due to its low cost, wide availability, and high energy content. The extensive use of coal-fired power assumes that the resulting CO{sub 2} emissions can be vented to the atmosphere. However, exponentially increasing atmospheric CO{sub 2} levels have brought this assumption under critical review. Over the last decade, this discussion has evolved from whether exponentially increasing anthropogenic CO{sub 2} emissions will adversely affect the global environment, to the timing and magnitude of their impact. A variety of sequestration technologies are being explored to mitigate CO{sub 2} emissions. These technologies must be both environmentally benign and economically viable. Mineral carbonation is an attractive candidate technology as it disposes of CO{sub 2} as geologically stable, environmentally benign mineral carbonates, clearly satisfying the first criteria. The primary challenge for mineral carbonation is cost-competitive process development. CO{sub 2} mineral sequestration--the conversion of stationary-source CO{sub 2} emissions into mineral carbonates (e.g., magnesium and calcium carbonate, MgCO{sub 3} and CaCO{sub 3})--has recently emerged as one of the most promising sequestration options, providing permanent CO{sub 2} disposal, rather than storage. In this approach a magnesium-bearing feedstock mineral (typically serpentine or olivine; available in vast quantities globally) is specially processed and allowed to react with CO{sub 2} under controlled conditions. This produces a mineral carbonate which (1) is environmentally benign, (2) already exists in nature in quantities far exceeding those that could result from carbonating the world's known fossil fuel reserves, and (3) is stable on a geological time scale. Minimizing the process cost via optimization of the reaction rate and degree of completion is the remaining challenge. As members of the DOE/NETL managed National Mineral Sequestration Working Group we have already significantly improved our understanding of mineral carbonation. Group members at the Albany Research Center have recently shown that carbonation of olivine and serpentine, which naturally occurs over geological time (i.e., 100,000s of years), can be accelerated to near completion in hours. Further process refinement will require a synergetic science/engineering approach that emphasizes simultaneous investigation of both thermodynamic processes and the detailed microscopic, atomic-level mechanisms that govern carbonation kinetics. Our previously funded Phase I Innovative Concepts project demonstrated the value of advanced quantum-mechanical modeling as a complementary tool in bridging important gaps in our understanding of the atomic/molecular structure and reaction mechanisms that govern CO{sub 2} mineral sequestration reaction processes for the model Mg-rich lamellar hydroxide feedstock material Mg(OH){sub 2}. In the present simulation project, improved techniques and more efficient computational schemes have allowed us to expand and augment these capabilities and explore more complex Mg-rich, lamellar hydroxide-based feedstock materials, including the serpentine-based minerals. These feedstock materials are being actively investigated due to their wide availability, and low-cost CO{sub 2} mineral sequestration potential. Cutting-edge first principles quantum chemical, computational solid-state and materials simulation methodology studies proposed herein, have been strategically integrated with our new DOE supported (ASU-Argonne National Laboratory) project to investigate the mechanisms that govern mineral feedstock heat-treatment and aqueous/fluid-phase serpentine mineral carbonation in situ. This unified, synergetic theoretical and experimental approach will provide a deeper understanding of the key reaction mechanisms than either individual approach can alone. Ab initio techniques will also significantly advance our understanding of atomic-level processes at the solid/solution interface by e

A.V.G. Chizmeshya

2003-12-19T23:59:59.000Z

266

ENHANCING THE ATOMIC-LEVEL UNDERSTANDING OF CO2 MINERAL SEQUESTRATION MECHANISMS VIA ADVANCED COMPUTATIONAL MODELING  

SciTech Connect

Fossil fuels currently provide 85% of the world's energy needs, with the majority coming from coal, due to its low cost, wide availability, and high energy content. The extensive use of coalfired power assumes that the resulting CO{sub 2} emissions can be vented to the atmosphere. However, exponentially increasing atmospheric CO{sub 2} levels have brought this assumption under critical review. Over the last decade, this discussion has evolved from whether exponentially increasing anthropogenic CO{sub 2} emissions will adversely affect the global environment, to the timing and magnitude of their impact. A variety of sequestration technologies are being explored to mitigate CO{sub 2} emissions. These technologies must be both environmentally benign and economically viable. Mineral carbonation is an attractive candidate technology as it disposes of CO{sub 2} as geologically stable, environmentally benign mineral carbonates, clearly satisfying the first criteria. The primary challenge for mineral carbonation is cost-competitive process development. CO{sub 2} mineral sequestration--the conversion of stationary-source CO{sub 2} emissions into mineral carbonates (e.g., magnesium and calcium carbonate, MgCO{sub 3} and CaCO{sub 3})--has recently emerged as one of the most promising sequestration options, providing permanent CO{sub 2} disposal, rather than storage. In this approach a magnesium-bearing feedstock mineral (typically serpentine or olivine; available in vast quantities globally) is specially processed and allowed to react with CO{sub 2} under controlled conditions. This produces a mineral carbonate which (i) is environmentally benign, (ii) already exists in nature in quantities far exceeding those that could result from carbonating the world's known fossil fuel reserves, and (iii) is stable on a geological time scale. Minimizing the process cost via optimization of the reaction rate and degree of completion is the remaining challenge. As members of the DOE/NETL managed National Mineral Sequestration Working Group we have already significantly improved our understanding of mineral carbonation. Group members at the Albany Research Center have recently shown that carbonation of olivine and serpentine, which naturally occurs over geological time (i.e., 100,000s of years), can be accelerated to near completion in hours. Further process refinement will require a synergetic science/engineering approach that emphasizes simultaneous investigation of both thermodynamic processes and the detailed microscopic, atomic-level mechanisms that govern carbonation kinetics. Our previously funded Phase I Innovative Concepts project demonstrated the value of advanced quantum-mechanical modeling as a complementary tool in bridging important gaps in our understanding of the atomic/molecular structure and reaction mechanisms that govern CO{sub 2} mineral sequestration reaction processes for the model Mg-rich lamellar hydroxide feedstock material Mg(OH){sub 2}. In the present simulation project, improved techniques and more efficient computational schemes have allowed us to expand and augment these capabilities and explore more complex Mg-rich, lamellar hydroxide-based feedstock materials, including the serpentine-based minerals. These feedstock materials are being actively investigated due to their wide availability, and low-cost CO{sub 2} mineral sequestration potential. Cutting-edge first principles quantum chemical, computational solid-state and materials simulation methodology studies proposed herein, have been strategically integrated with our new DOE supported (ASU-Argonne National Laboratory) project to investigate the mechanisms that govern mineral feedstock heat-treatment and aqueous/fluid-phase serpentine mineral carbonation in situ. This unified, synergetic theoretical and experimental approach will provide a deeper understanding of the key reaction mechanisms than either individual approach can alone. Ab initio techniques will also significantly advance our understanding of atomic-level processes at the solid/solution interface by

A.V.G. Chizmeshya

2002-12-19T23:59:59.000Z

267

ENHANCING THE ATOMIC-LEVEL UNDERSTANDING OF CO2 MINERAL SEQUESTRATION MECHANISMS VIA ADVANCED COMPUTATIONAL MODELING  

SciTech Connect

Fossil fuels currently provide 85% of the world's energy needs, with the majority coming from coal, due to its low cost, wide availability, and high energy content. The extensive use of coal-fired power assumes that the resulting CO2 emissions can be vented to the atmosphere. However, exponentially increasing atmospheric CO2 levels have brought this assumption under critical review. Over the last decade, this discussion has evolved from whether exponentially increasing anthropogenic CO2 emissions will adversely affect the global environment, to the timing and magnitude of their impact. A variety of sequestration technologies are being explored to mitigate CO2 emissions. These technologies must be both environmentally benign and economically viable. Mineral carbonation is an attractive candidate technology as it disposes of CO2 as geologically stable, environmentally benign mineral carbonates, clearly satisfying the first criteria. The primary challenge for mineral carbonation is cost-competitive process development. CO2 mineral sequestration--the conversion of stationary-source CO2 emissions into mineral carbonates (e.g., magnesium and calcium carbonate, MgCO3 and CaCO3)--has recently emerged as one of the most promising sequestration options, providing permanent CO2 disposal, rather than storage. In this approach a magnesium-bearing feedstock mineral (typically serpentine or olivine; available in vast quantities globally) is specially processed and allowed to react with CO2 under controlled conditions. This produces a mineral carbonate which (1) is environmentally benign, (2) already exists in nature in quantities far exceeding those that could result from carbonating the world's known fossil fuel reserves, and (3) is stable on a geological time scale. Minimizing the process cost via optimization of the reaction rate and degree of completion is the remaining challenge. As members of the DOE/NETL managed National Mineral Sequestration Working Group we have already significantly improved our understanding of mineral carbonation. Group members at the Albany Research Center have recently shown that carbonation of olivine and serpentine, which naturally occurs over geological time (i.e., 100,000s of years), can be accelerated to near completion in hours. Further process refinement will require a synergetic science/engineering approach that emphasizes simultaneous investigation of both thermodynamic processes and the detailed microscopic, atomic-level mechanisms that govern carbonation kinetics. Our previously funded Phase I Innovative Concepts project demonstrated the value of advanced quantum-mechanical modeling as a complementary tool in bridging important gaps in our understanding of the atomic/molecular structure and reaction mechanisms that govern CO2 mineral sequestration reaction processes for the model Mg-rich lamellar hydroxide feedstock material Mg(OH)2. In the present simulation project, improved techniques and more efficient computational schemes have allowed us to expand and augment these capabilities and explore more complex Mg-rich, lamellar hydroxide-based feedstock materials, including the serpentine-based minerals. These feedstock materials are being actively investigated due to their wide availability, and low-cost CO2 mineral sequestration potential. Cutting-edge first principles quantum chemical, computational solid-state and materials simulation methodology studies proposed herein, have been strategically integrated with our new DOE supported (ASU-Argonne National Laboratory) project to investigate the mechanisms that govern mineral feedstock heat-treatment and aqueous/fluid-phase serpentine mineral carbonation in situ. This unified, synergetic theoretical and experimental approach has provided a deeper understanding of the key reaction mechanisms than either individual approach can alone. We used ab initio techniques to significantly advance our understanding of atomic-level processes at the solid/solution interface by elucidating the origin of vibrational, electronic, x-ray and electron energy loss sp

A.V.G. Chizmeshya; M.J. McKelvy; G.H. Wolf; R.W. Carpenter; D.A. Gormley; J.R. Diefenbacher; R. Marzke

2006-03-01T23:59:59.000Z

268

Modeling study of ventilation, IAQ and energy impacts of residential mechanical ventilation  

SciTech Connect

This paper reports on a simulation study of indoor air quality, ventilation and energy impacts of several mechanical ventilation approaches in a single-family residential building. The study focused on a fictitious two-story house in Spokane, Washington and employed the multizone airflow and contaminant dispersal model CONTAM. The model of the house included a number of factors related to airflow including exhaust fan and forced-air system operation, duct leakage and weather effects, as well as factors related to contaminant dispersal including adsorption/desorption of water vapor and volatile organic compounds, surface losses of particles and nitrogen dioxide, outdoor contaminant concentrations, and occupant activities. The contaminants studied include carbon monoxide, carbon dioxide, nitrogen dioxide, water vapor, fine and coarse particles, and volatile organic compounds. One-year simulations were performed for four different ventilation approaches: a base case of envelope infiltration only, passive inlet vents in combination with exhaust fan operation, an outdoor intake duct connected to the forced-air system return balanced by exhaust fan operation, and a continuously-operated exhaust fan. Results discussed include whole building air change rates, air distribution within the house, heating and cooling loads, contaminants concentrations, and occupant exposure to contaminants.

Persily, A.K.

1998-05-01T23:59:59.000Z

269

Improvement of Stent Retriever Design and Efficacy of Mechanical Thrombectomy in a Flow Model  

SciTech Connect

In vitro experiments were performed to evaluate the efficacy of mechanical intracranial thrombectomy comparing the newly developed Aperio stent retriever and standard devices for stroke treatment. The Aperio (A), with an increased working length of 4 cm and a special cell design for capturing and withholding clots, was compared to three benchmark devices: the Solitaire retrievable stent (B), the Merci X6 (C), and the Merci L5 retriever (D). In a vascular glass model with pulsatile flow, reminiscent of the M1 segment of the middle cerebral artery, we repeatedly induced occlusion by generating thrombi via a modified Chandler loop system. The numbers of recanalization attempts, peripheral embolizations, and recanalizations at the site of occlusion were recorded during 10 retrieval experiments with each device. Eleven devices were able to remove the blood clots from the occluded branch. In 34 of 40 experiments, restoration of flow was obtained in 1-3 attempts. The main differences between the study devices were observed in terms of clot withholding and fragmentation during retrieval. Although there was only one fragmentation recorded for device A, disengagement of the whole clot or peripheral embolization of fragments occurred more frequently (5-7 times) with devices B, C, and D. In a vascular model, the design of device A was best at capturing and withholding thrombi during retrieval. Further study will be necessary to see whether this holds true in clinical applications.

Wenger, Katharina, E-mail: kwenger@stud.uni-frankfurt.de [Institute of Neuroradiology, University of Frankfurt am Main (Germany)] [Institute of Neuroradiology, University of Frankfurt am Main (Germany); Nagl, Frank, E-mail: fnagl@acandis.com [Acandis GmbH and Co KG (Germany)] [Acandis GmbH and Co KG (Germany); Wagner, Marlies, E-mail: Marlies.Wagner@kgu.de; Berkefeld, Joachim, E-mail: berkefeld@em.uni-frankfurt.de [Institute of Neuroradiology, University of Frankfurt am Main (Germany)] [Institute of Neuroradiology, University of Frankfurt am Main (Germany)

2013-02-15T23:59:59.000Z

270

The abelian confinement mechanism revisited: new aspects of the Georgi-Glashow model  

E-Print Network (OSTI)

The confinement problem remains one of the most difficult problems in theoretical physics. An important step toward the solution of this problem is the Polyakov's work on abelian confinement. The Georgi-Glashow model is a natural testing ground for this mechanism which has been surprising us by its richness and wide applicability. In this work, we shed light on two new aspects of this model in 2+1 D. First, we develop a many-body description of the effective degrees of freedom. Namely, we consider a non-relativistic gas of W-bosons in the background of monopole-instanton plasma. Many-body treatment is a standard toolkit in condensed matter physics. However, we add a new twist by supplying the monopole-instantons as external background field. Using this construction, we calculate the exact form of the potential between two electric probes as a function of their separation. This potential is expressed in terms of the Meijer-G function which interpolates between logarithmic and linear behavior at small and large distances, respectively. Second, we develop a systematic approach to integrate out the effect of the W-bosons at finite temperature in the range 0gas. We repeat our analysis using the many-body description which yields the same result and provides a check on our formalism. At temperatures close to the deconfinement temperature, the gas becomes essentially two-dimensional recovering the partition function of the dual sine-Gordon model that was considered in a previous work.

Mohamed M. Anber

2013-07-31T23:59:59.000Z

271

Surveying Diffusion in Complex Geometries. An Essay  

E-Print Network (OSTI)

The surrounding world surprises us by the beauty and variety of complex shapes that emerge from nanometric to macroscopic scales. Natural or manufactured materials (sandstones, sedimentary rocks and cement), colloidal solutions (proteins and DNA), biological cells, tissues and organs (lungs, kidneys and placenta), they all present irregularly shaped "scenes" for a fundamental transport "performance", that is, diffusion. Here, the geometrical complexity, entangled with the stochastic character of diffusive motion, results in numerous fascinating and sometimes unexpected effects like diffusion screening or localization. These effects control many diffusion-mediated processes that play an important role in heterogeneous catalysis, biochemical mechanisms, electrochemistry, growth phenomena, oil recovery, or building industry. In spite of a long and rich history of academic and industrial research in this field, it is striking to see how little we know about diffusion in complex geometries, especially the one whic...

Grebenkov, Denis

2009-01-01T23:59:59.000Z

272

Commercial Building Partnerships Replication and Diffusion  

SciTech Connect

This study presents findings from survey and interview data investigating replication efforts of Commercial Building Partnership (CBP) partners that worked directly with the Pacific Northwest National Laboratory (PNNL). PNNL partnered directly with 12 organizations on new and retrofit construction projects, which represented approximately 28 percent of the entire U.S. Department of Energy (DOE) CBP program. Through a feedback survey mechanism, along with personal interviews, PNNL gathered quantitative and qualitative data relating to replication efforts by each organization. These data were analyzed to provide insight into two primary research areas: 1) CBP partners’ replication efforts of technologies and approaches used in the CBP project to the rest of the organization’s building portfolio (including replication verification), and, 2) the market potential for technology diffusion into the total U.S. commercial building stock, as a direct result of the CBP program. The first area of this research focused specifically on replication efforts underway or planned by each CBP program participant. Factors that impact replication include motivation, organizational structure and objectives firms have for implementation of energy efficient technologies. Comparing these factors between different CBP partners revealed patterns in motivation for constructing energy efficient buildings, along with better insight into market trends for green building practices. The second area of this research develops a diffusion of innovations model to analyze potential broad market impacts of the CBP program on the commercial building industry in the United States.

Antonopoulos, Chrissi A.; Dillon, Heather E.; Baechler, Michael C.

2013-09-16T23:59:59.000Z

273

Exploring the mechanisms critical to the operation of metal face seals through modeling and experiments  

E-Print Network (OSTI)

This thesis aims to explore operation mechanisms of a special type of mechanical face seals: the flexible metal-to-metal face seal (FMMFS). Unique features of the FMMFS include much more flexibility in the circumferential ...

Wang, Yong, Ph. D. Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics

2008-01-01T23:59:59.000Z

274

Diffusive Accumulation of Methane Bubbles in Seabed  

E-Print Network (OSTI)

We consider seabed bearing methane bubbles. In the absence of fractures the bubbles are immovably trapped in a porous matrix by surface tension forces; therefore the dominant mechanism of transfer of gas mass becomes the diffusion of gas molecules through the liquid. The adequate description of this process requires accounting "other-than-normal" (non-Fickian) diffusion effects, thermodiffusion and gravity action. We evaluate the diffusive flux of aqueous methane and predict the possibility of existence of bubble mass accumulation zones (which can appear independently from the presence/absence of hydrate stability zone) and effect of non-Fickian drift on the capacity of shallow and deep methane-hydrate deposits.

Goldobin, D S; Levesley, J; Lovell, M A; Rochelle, C A; Jackson, P; Haywood, A; Hunter, S; Rees, J

2010-01-01T23:59:59.000Z

275

Pollutant Transport and Diffusion in Katabatic Flows  

Science Conference Proceedings (OSTI)

The characteristics of pollutant transport and diffusion of a passive contaminant in a two-dimensional katabatic flow over a simple slope are examined using a primitive equation hydrodynamic model. It is shown that pollutants released above the ...

Carmen J. Nappo; K. Shankar Rao; Jerold A. Herwehe

1989-07-01T23:59:59.000Z

276

Characterizing unsaturated diffusion in porous tuff gravel  

SciTech Connect

Evaluation of solute diffusion in unsaturated porous gravel is very important for investigations of contaminant transport and remediation, risk assessment, and waste disposal (for example, the potential high-level nuclear waste repository at Yucca Mountain, Nevada). For a porous aggregate medium such as granular tuff, the total water content is comprised of surface water and interior water. The surface water component (water film around grains and pendular water between the grain contacts) could serve as a predominant diffusion pathway. To investigate the extent to which surface water films and contact points affect solute diffusion in unsaturated gravel, we examined the configuration of water using x-ray computed tomography in partially saturated gravel, and made quantitative measurements of diffusion at multiple water contents using two different techniques. In the first, diffusion coefficients of potassium chloride in 2-4 mm granular tuff at multiple water contents were calculated from electrical conductivity measurements using the Nernst-Einstein equation. In the second, we used laser ablation with inductively coupled plasma-mass spectrometry to perform micro-scale mapping, allowing the measurement of diffusion coefficients for a mixture of chemical tracers for tuff cubes and tetrahedrons having two contact geometries (cube-cube and cube-tetrahedron). The x-ray computed tomography images show limited contact between grains, and this could hinder the pathways for diffusive transport. Experimental results show the critical role of surface water in controlling transport pathways and hence the magnitude of diffusion. Even with a bulk volumetric water content of 1.5%, the measured solute diffusion coefficient is as low as 1.5 x 10{sup -14} m{sup 2}/s for tuff gravel. Currently used diffusion models relating diffusion coefficients to total volumetric water content inadequately describe unsaturated diffusion behavior in porous gravel at very low water contents.

Hu, Qinhong; Kneafsey, Timothy J.; Roberts, Jeffery J.; Tomutsa, Liviu; Wang, Joseph, S.Y.

2003-11-12T23:59:59.000Z

277

A comparative model of two mechanisms from which a magnetic field arises in the heart  

Science Conference Proceedings (OSTI)

There are two different mechanisms from which a magnetic field can arise in the heart. The first mechanism has the source of the magnetic field as a current dipole oriented perpendicular to the action potential wave front with the “return” currents flowing in an adjacent volume conductor. The second mechanism is one with no adjacent volume conductor and has a magnetic field that arises due to the anisotropy of the tissue. We see that the two mechanisms produce magnetic fields of similar magnitudes and similar falloff rates as distance from the tissue increases

R. A. Murdick; B. J. Roth

2004-01-01T23:59:59.000Z

278

Coarsening of the Sn-Pb Solder Microstructure in Constitutive Model-Based Predictions of Solder Joint Thermal Mechanical Fatigue  

SciTech Connect

Thermal mechanical fatigue (TMF) is an important damage mechanism for solder joints exposed to cyclic temperature environments. Predicting the service reliability of solder joints exposed to such conditions requires two knowledge bases: first, the extent of fatigue damage incurred by the solder microstructure leading up to fatigue crack initiation, must be quantified in both time and space domains. Secondly, fatigue crack initiation and growth must be predicted since this metric determines, explicitly, the loss of solder joint functionality as it pertains to its mechanical fastening as well as electrical continuity roles. This paper will describe recent progress in a research effort to establish a microstructurally-based, constitutive model that predicts TMF deformation to 63Sn-37Pb solder in electronic solder joints up to the crack initiation step. The model is implemented using a finite element setting; therefore, the effects of both global and local thermal expansion mismatch conditions in the joint that would arise from temperature cycling.

Vianco, P.T.; Burchett, S.N.; Neilsen, M.K.; Rejent, J.A.; Frear, D.R.

1999-04-12T23:59:59.000Z

279

A statistical, physical-based, micro-mechanical model of hydrogen-induced intergranular fracture in steel  

E-Print Network (OSTI)

. Introduction It is well recognized that hydrogen represents an abundant, clean and mobile energy carrier. For the hydrogen economy to be fully realized though, efficient hydrogen storage and transportation, for exampleA statistical, physical-based, micro-mechanical model of hydrogen-induced intergranular fracture

Ritchie, Robert

280

Stochastic approach to diffusion inside the chaotic layer of a resonance  

E-Print Network (OSTI)

We model chaotic diffusion, in a symplectic 4D map by using the result of a theorem that was developed for stochastically perturbed integrable Hamiltonian systems. We explicitly consider a map defined by a free rotator (FR) coupled to a standard map (SM). We focus in the diffusion process in the action, $I$, of the FR, obtaining a semi--numerical method to compute the diffusion coefficient. We study two cases corresponding to a thick and a thin chaotic layer in the SM phase space and we discuss a related conjecture stated in the past. In the first case the numerically computed probability density function for the action $I$ is well interpolated by the solution of a Fokker-Planck (F-P) equation, whereas it presents a non--constant time delay respect to the concomitant F-P solution in the second case suggesting the presence of an anomalous diffusion time scale. The explicit calculation of a diffusion coefficient for a 4D symplectic map can be useful to understand the slow diffusion observed in Celestial Mechanics and Accelerator Physics.

Martín F. Mestre; Armando Bazzani; Pablo M. Cincotta; Claudia M. Giordano

2013-11-11T23:59:59.000Z

Note: This page contains sample records for the topic "diffusion mechanisms 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.


281

Thermodynamics and Diffusion  

Science Conference Proceedings (OSTI)

Feb 28, 2011 ... Hume-Rothery Symposium Thermodynamics and Diffusion Coupling ... be quite fundamental and often it cannot be distinguished from “basic” ...

282

Mulitcomponent Multiphase Diffusion  

Science Conference Proceedings (OSTI)

... 54 (2006) p 2431-2439. pdf file; "Hillert, Höglund, and Ågren, "Diffusion in interstitial compounds with thermal and stoichiometric defects," J. Appl. ...

2008-07-22T23:59:59.000Z

283

Particle Dispersion and Mixing of Conservative Properties in an Eddy-Resolving Model  

Science Conference Proceedings (OSTI)

We examine the diffusive behavior of the flow field in an eddy-resolving, primitive equation circulation model. Analysis of fluid particle trajectories illustrates the transport mechanisms, which are leading to uniform tracer and potential ...

Claus W. Böning; Michael D. Cox

1988-02-01T23:59:59.000Z

284

A general kinetic model: Kinetics and atomic-scale mechanisms of feldspar dissolution.  

E-Print Network (OSTI)

??This thesis presents a general kinetic model and its application to feldspar dissolution. In the framework of Monte Carlo methods, the model simulates the stochastic… (more)

Zhang, Li

2008-01-01T23:59:59.000Z

285

Atomistic and continuum modeling of mechanical properties of collagen: Elasticity, fracture, and self-assembly  

E-Print Network (OSTI)

efforts to refine the Standard Model and understanding of atomic properties. #12;Contents 1 Once Upon

Entekhabi, Dara

286

Studying paths of participation in viral diffusion process  

Science Conference Proceedings (OSTI)

Authors propose a conceptual model of participation in viral diffusion process composed of four stages: awareness, infection, engagement and action. To verify the model it has been applied and studied in the virtual social chat environment settings. ... Keywords: information diffusion, multistage analysis, online social networks, participation model

Jaros?aw Jankowski; Sylwia Ciuberek; Anita Zbieg; Rados?aw Michalski

2012-12-01T23:59:59.000Z

287

Physical understanding and modeling of chemical mechanical planarization in dielectric materials  

E-Print Network (OSTI)

Chemical mechanical planarization (CMP) has become the enabling planarization technique of choice for current and emerging silicon integrated circuit (IC) fabrication processes. This work studies CMP in dielectric materials ...

Xie, Xiaolin, Ph. D. Massachusetts Institute of Technology

2007-01-01T23:59:59.000Z

288

Subgrid-Scale Eddy Parameterization by Statistical Mechanics in a Barotropic Ocean Model  

Science Conference Proceedings (OSTI)

The feasibility of using a subgrid-scale eddy parameterization, based on statistical mechanics of potential vorticity, is investigated. A specific implementation is derived for the somewhat classic barotropic vorticity equation in the case of a ...

Evguéni Kazantsev; Joël Sommeria; Jacques Verron

1998-06-01T23:59:59.000Z

289

Physical and numerical modeling of the external fluid mechanics of OTEC pilot plants  

E-Print Network (OSTI)

This study examined the near field external fluid mechanics of symmetrical OTEC pilot plant designs (20-80 MWe) under realistic deep water conditions. The objective was to assess the environmental impact of different plant ...

Singarella, Paul N.

1982-01-01T23:59:59.000Z

290

Mechanisms of Decadal Arctic Climate Variability in the Community Climate System Model, Version 2 (CCSM2)  

Science Conference Proceedings (OSTI)

Several mechanisms have been proposed to explain natural climate variability in the Arctic. These include processes related to the influence of the North Atlantic Oscillation/Arctic Oscillation (NAO/AO), anticyclonic/cyclonic regimes, changes in ...

Hugues Goosse; Marika M. Holland

2005-09-01T23:59:59.000Z

291

Model-based dummy feature placement for oxide chemical-mechanical polishing manufacturability  

Science Conference Proceedings (OSTI)

Chemical-mechanical polishing (CMP) is an enabling technique used in deep-submicron VLSI manufacturing to achieve uniformity in long range oxide planarization [1]. Post-CMP oxide topography is highly related to local spatial pattern density in layout. ...

Ruiqi Tian; D. F. Wong; Robert Boone

2000-06-01T23:59:59.000Z

292

In vitro models of cartilage degradation following joint injury : mechanical overload, inflammatory cytokines and therapeutic approaches  

E-Print Network (OSTI)

Osteoarthritis (OA) is the most common form of joint disorder. Individuals who have sustained an acute traumatic joint injury are at greater risk for the development of OA. The mechanisms by which injury causes cartilage ...

Lu, Yihong C. S

2010-01-01T23:59:59.000Z

293

Fractal Location and Anomalous Diffusion Dynamics for Oil Wells from the KY Geological Survey  

E-Print Network (OSTI)

Utilizing data available from the Kentucky Geonet (KYGeonet.ky.gov) the fossil fuel mining locations created by the Kentucky Geological Survey geo-locating oil and gas wells are mapped using ESRI ArcGIS in Kentucky single plain 1602 ft projection. This data was then exported into a spreadsheet showing latitude and longitude for each point to be used for modeling at different scales to determine the fractal dimension of the set. Following the porosity and diffusivity studies of Tarafdar and Roy1 we extract fractal dimensions of the fossil fuel mining locations and search for evidence of scaling laws for the set of deposits. The Levy index is used to determine a match to a statistical mechanically motivated generalized probability function for the wells. This probability distribution corresponds to a solution of a dynamical anomalous diffusion equation of fractional order that describes the Levy paths which can be solved in the diffusion limit by the Fox H function ansatz.

Andrew, Keith; Andrew, Kevin A

2009-01-01T23:59:59.000Z

294

Experimental Verification of Thermo-Mechanical Models for XLPE Cable in Pipes and Ducts  

Science Conference Proceedings (OSTI)

In 2002 EPRI began investigations of the thermo-mechanical (T-M) behavior of transmission-class cable systems with extruded insulation in duct-manhole and pipe systems and began work on a design guide. The project consisted primarily of two efforts: experimental measurement of cable parameters and development of a mathematical simulation of the thermal and mechanical behavior of transmission-class cable with extruded cross-linked polyethylene (XLPE) insulation when installed in ducts and pipes. ...

2012-12-20T23:59:59.000Z

295

Higgs Mechanism in the Standard Model and a Possibility of its Direct Physical Realization  

E-Print Network (OSTI)

The aim of this work was to answer the question: Is the direct physical realization of the Higgs mechanism possible? It is shown that this mechanism cannot have a direct physical realization since the condition for this realization is not fulfilled. It means that if in the new collider at CERN a scalar particle is detected, it does not mean that it is a Higgs particle.

Kh. M. Beshtoev

2008-12-30T23:59:59.000Z

296

Eddy Advective and Diffusive Transports of Heat and Salt in the Southern Ocean  

Science Conference Proceedings (OSTI)

There are two distinct mechanisms by which eddies provide systematic transport of tracer on isopycnals: the advective transport, associated with the slumping of isopycnals, and the diffusive transport, associated with down-gradient diffusion. ...

Mei-Man Lee; A. J. George Nurser; A. C. Coward; B. A. de Cuevas

2007-05-01T23:59:59.000Z

297

Mechanical properties and modeling of seal-forming lithologies. Technical progress report No. 3, March 15, 1992--June 14, 1993  

SciTech Connect

Specific goals and accomplishments of this research include: (1) The evaluation of models of salt diaper ascent that involve either power law, dislocation creep as determined experimentally by Horseman et al. (1993) or linear, fluid-assisted creep as reported by Spiers et al. (1988, 1990, 1992). We have compared models assuming these two, experimentally evaluated flow laws and examined the predictions they make regarding diaper incubation periods, ascent velocities, deviatoric stresses and strain rates. (2) The evaluation of the effects of differential loading on the initiation an of salt structures. (3) Examination of the role of basement faults on the initiation and morphologic evolution of salt structures. (4) Evaluation of the mechanical properties of shale as a function of pressure and determination of the nature of its brittle-ductile transition. (5) Evaluation of the mechanical anisotropies of shales with varying concentrations, distributions and preferred orientations of clay. (6) The determination of temperature and ratedependencies of strength for a shale constitutive model that can be used in numerical models that depend on viscous formulations. (7) Determination of the mechanisms of deformation for argillaceous rocks over awide range of conditions. (8) Evaluation of the effects of H{sub 2}O within clay interlayers, as adsorbed surface layers.

Kronenberg, A.K.; Russell, J.E.; Carter, N.L.; Mazariegos, R.; Ibanez, W.

1993-06-01T23:59:59.000Z

298

Model studies of the structures, reactivities, and reaction mechanisms of metalloenzymes  

Science Conference Proceedings (OSTI)

Electronic structure theory, which in recent years has been actively and effectively applied to the modeling of chemical reactions involving transition-metal complexes, is now also being applied to the modeling of biological processes involving metalloenzymes. ...

K. Morokuma; D. G. Musaev; T. Vreven; H. Basch; M. Torrent; D. V. Khoroshun

2001-05-01T23:59:59.000Z

299

Mechanisms of Low Cloud–Climate Feedback in Idealized Single-Column Simulations with the Community Atmospheric Model, Version 3 (CAM3)  

Science Conference Proceedings (OSTI)

This study investigates the physical mechanism of low cloud feedback in the Community Atmospheric Model, version 3 (CAM3) through idealized single-column model (SCM) experiments over the subtropical eastern oceans. Negative cloud feedback is ...

Minghua Zhang; Christopher Bretherton

2008-09-01T23:59:59.000Z

300

Solar diffusion and public incentives  

Science Conference Proceedings (OSTI)

Institutional arrangements for the commercialization of solar technologies cover a variety of incentives. Although this book concentrates on one such incentive, a grant awarded to homeowners purchasing an approved solar hot water heater, the concluding discussion suggests alternative inducements. The empirical work is based on data collected in Connecticut, but attention is given to national- and state-level studies addressing various aspects of the solar-diffusion process. The authors begin by examining public acceptance and various social-science models for diffusion processes. They conclude that the importance of social and behavioral factors in accelerating the energy transition should not be underestimated. Eight appendices include survey and application forms, information releases, and information about the incentive program. 81 references, 4 figures, 33 tables.

Warkov, S.; Meyer, J.W.

1982-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "diffusion mechanisms 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

Determination of Basic Structure-Property Relations for Processing and Modeling in Advanced Nuclear Fuel: Microstructure Evolution and Mechanical Properties  

SciTech Connect

The project objective is to study structure-property relations in solid solutions of nitrides and oxides with surrogate elements to simulate the behavior of fuels of inert matrix fuels of interest to the Advanced Fuel Cycle Initiative (AFCI), with emphasis in zirconium-based materials. Work with actual fuels will be carried out in parallel in collaboration with Los Alamos National Laboratory (LANL). Three key aspects will be explored: microstructure characterization through measurement of global texture evolution and local crystallographic variations using Electron Backscattering Diffraction (EBSD); determination of mechanical properties, including fracture toughness, quasi-static compression strength, and hardness, as functions of load and temperature, and, finally, development of structure-property relations to describe mechanical behavior of the fuels based on experimental data. Materials tested will be characterized to identify the mechanisms of deformation and fracture and their relationship to microstructure and its evolution. New aspects of this research are the inclusion of crystallographic information into the evaluation of fuel performance and the incorporation of statistical variations of microstructural variables into simplified models of mechanical behavior of fuels that account explicitly for these variations. The work is expected to provide insight into processing conditions leading to better fuel performance and structural reliability during manufacturing and service, as well as providing a simplified testing model for future fuel production.

Kirk Wheeler; Manuel Parra; Pedro Peralta

2009-03-01T23:59:59.000Z

302

Modelling Quantum Mechanics by the Quantumlike Description of the Electric Signal Propagation in Transmission Lines  

E-Print Network (OSTI)

It is shown that the transmission line technology can be suitably used for simulating quantum mechanics. Using manageable and at the same time non-expensive technology, several quantum mechanical problems can be simulated for significant tutorial purposes. The electric signal envelope propagation through the line is governed by a Schrodinger-like equation for a complex function, representing the low-frequency component of the signal, In this preliminary analysis, we consider two classical examples, i.e. the Frank-Condon principle and the Ramsauer effect.

R. Fedele; M. A. Man'ko; V. I. Man'ko; V. G. Vaccaro

2002-07-30T23:59:59.000Z

303

Nonlinear Horizontal Diffusion for GCMs  

Science Conference Proceedings (OSTI)

The mixing-length-based parameterization of horizontal diffusion, which was originally proposed by Smagorinsky, is revisited. The complete tendencies of horizontal momentum diffusion, the associated frictional heating, and horizontal diffusion of ...

Erich Becker; Ulrike Burkhardt

2007-04-01T23:59:59.000Z

304

Quantum-Mechanical Model of Spacetime I: Microscopic Properties of Spacetime  

E-Print Network (OSTI)

This is the first part in a series of two papers, where we consider a specific microscopic model of spacetime. In our model Planck size quantum black holes are taken to be the fundamental building blocks of space and time. Spacetime is assumed to be a graph, where black holes lie on the vertices. In this first paper we construct our model in details, and show how classical spacetime emerges at the long distance limit from our model. We also consider the statistics of spacetime.

Makela, J

2008-01-01T23:59:59.000Z

305

A Simple Quantum-Mechanical Model of Spacetime I: Microscopic Properties of Spacetime  

E-Print Network (OSTI)

This is the first part in a series of two papers, where we consider a specific microscopic model of spacetime. In our model Planck size quantum black holes are taken to be the fundamental building blocks of space and time. Spacetime is assumed to be a graph, where black holes lie on the vertices. In this first paper we construct our model in details, and show how classical spacetime emerges at the long distance limit from our model. We also consider the statistics of spacetime.

J. Makela

2008-05-26T23:59:59.000Z

306

VISUALS: Diffusion couple animation - TMS  

Science Conference Proceedings (OSTI)

Sep 25, 2007 ... This Quicktime animation of a diffusion couple shows side-by-side views of two different atomic species - red and green - diffusing across a flat ...

307

Adaptive multigroup radiation diffusion  

E-Print Network (OSTI)

This thesis describes the development and implementation of an algorithm for dramatically increasing the accuracy and reliability of multigroup radiation diffusion simulations at low group counts. This is achieved by ...

Williams, Richard B., Sc. D. Massachusetts Institute of Technology

2005-01-01T23:59:59.000Z

308

A semi-analytical model for heat and mass transfer in geothermal reservoirs to estimate fracture surface-are-to-volume ratios and thermal breakthrough using thermally-decaying and diffusing tracers  

SciTech Connect

A semi-analytical model was developed to conduct rapid scoping calculations of responses of thermally degrading and diffusing tracers in multi-well tracer tests in enhanced geothermal systems (EGS). The model is based on an existing Laplace transform inversion model for solute transport in dual-porosity media. The heat- and mass-transfer calculations are decoupled and conducted sequentially, taking advantage of the fact that heat transfer between fractures and the rock matrix is much more rapid than mass transfer and therefore mass transfer will effectively occur in a locally isothermal system (although the system will be nonisothermal along fracture flow pathways, which is accounted for by discretizing the flow pathways into multiple segments that have different temperature histories). The model takes advantage of the analogies between heat and mass transfer, solving the same governing equations with k{sub m}/({rho}C{sub p}){sub w} being substituted for {phi}D{sub m} in the equation for fracture transport and k{sub m}/({rho}C{sub p}){sub m} being subsituted for D{sub m} in the equation for matrix transport; where k = thermal conductivity (cal/cm-s-K), {rho} = density (g/cm{sup 3}), C{sub p} = heat capacity (at constant pressure) (cal/g-K), {phi} = matrix porosity, and D = tracer diffusion coefficient (cm{sup 2}/s), with the subscripts w and m referring to water and matrix, respectively. A significant advantage of the model is that it executes in a fraction of second on a single-CPU personal computer, making it very amenable for parameter estimation algorithms that involve repeated runs to find global minima. The combined thermal-mass transport model was used to evaluate the ability to estimate when thermal breakthrough would occur in a multi-well EGS configuration using thermally degrading tracers. Calculations were conducted to evaluate the range of values of Arrhenius parameters, A and E{sub {alpha}} (pre-exponential factor, 1/s, and activation energy, cal/mol) required to obtain interpretable responses of thermally-degrading tracers that decay according to the rate constant k{sub d} = Ae{sup -E{sub {alpha}}/RT}, where k{sub d} = decay rate constant (1/s), R = ideal gas constant (1.987 cal/mol-K), and T = absolute temperature (K). It is shown that there are relatively narrow ranges of A and E{sub {alpha}} that will result in readily interpretable tracer responses for any given combination of ambient reservoir temperature and working fluid residence time in a reservoir. The combined model was also used to simulate the responses of conservative tracers with different diffusion coefficients as a way of estimating fracture surface-area-to-volume ratios (SA/V) in multi-well EGS systems. This method takes advantage of the fact that the differences in breakthrough curves of tracers with different matrix diffusion coefficients are a function of SA/V. The model accounts for differences in diffusion coefficients as a function of temperature so that tracer responses obtained at different times can be used to obtain consistent estimates of SA/V as the reservoir cools down. Some single-well applications of this approach are simulated with a numerical model to demonstrate the potential to evaluate the effectiveness of EGS stimulations before a second well is drilled.

Reimus, Paul W [Los Alamos National Laboratory

2010-12-08T23:59:59.000Z

309

Mathematical model of IRIS replication mechanism for the simulation of tactical networks  

Science Conference Proceedings (OSTI)

The Multilateral Interoperability Programme (MIP) was established to promote more successful and better harmonized operational functions for international peace-keeping forces. The C2IEDM/JC3IEDM (Command and Control Information Exchange Data Model) ... Keywords: C2IS, Simulations, Tactical radio network, Traffic modeling

Joe Mohorko; Matja Fras

2009-05-01T23:59:59.000Z

310

Diffusion bonding of commercially pure Ni using Cu interlayer  

Science Conference Proceedings (OSTI)

The concentration dependence of diffusivity in a multi-component diffusion system makes it complicated to predict the concentration profiles of diffusing species. This so called chemical diffusivity can be expressed as a function of thermodynamic and kinetic data. DICTRA software can calculate the concentration profiles using appropriate mobility and thermodynamic data. It can also optimize the diffusivity data using experimental diffusivity data. Then the optimized diffusivity data is stored as mobility data which is a linear function of temperature. In this work, diffusion bonding of commercially pure Ni using Cu interlayers is reported. The mobility parameters of Ni-Cu alloy binary systems were optimized using DICTRA/Thermocalc software from the available self-, tracer and chemical diffusion coefficients. The optimized mobility parameters were used to simulate concentration profiles of Ni-Cu diffusion joints using DICTRA/Thermocalc software. The calculated and experimental concentration profiles agreed well at 1100 Degree-Sign C. Agreement between the simulated and experimental profiles was less good at 1050 Degree-Sign C due to the grain boundary contribution to the overall diffusion. - Highlights: Black-Right-Pointing-Pointer The concentration profiles of Cu in Ni-Cu diffusion joints are modeled. Black-Right-Pointing-Pointer Interdiffusion coefficients in Ni-Cu system are optimized. Black-Right-Pointing-Pointer Optimized interdiffusion coefficients are expressed as mobility parameters. Black-Right-Pointing-Pointer Simulated profiles are comparable with experimental profiles.

Rahman, A.H.M.E., E-mail: a.rahman@my.und.edu; Cavalli, M.N.

2012-07-15T23:59:59.000Z

311

Technology Diffusion in Communication Networks  

E-Print Network (OSTI)

In the rich and growing literature on diffusion and cascade effects in social networks, it is assumed that a node's actions are influenced only by its immediate neighbors in the social network. However, there are other contexts in which this highly-local view of influence is not applicable. The diffusion of technologies in communication networks is one important example; here, a node's actions should also be influenced by remote nodes that it can communicate with using the new technology. We propose a new model of technology diffusion inspired by the networking literature on this topic. Given the communication network $G(V,E)$, we assume that node $u$ activates (i.e. deploys the new technology) when it is adjacent to a connected component of active nodes in $G$ of size exceeding node $u$'s threshold $\\theta(u)$. We focus on an algorithmic problem that is well understood in the context of social networks, but thus far has only heuristic solutions in the context of communication networks: determining the smalle...

Goldberg, Sharon

2012-01-01T23:59:59.000Z

312

Peer Effects in the Diffusion of Solar Photovoltaic Panels  

Science Conference Proceedings (OSTI)

Social interaction (peer) effects are recognized as a potentially important factor in the diffusion of new products. In the case of environmentally friendly goods or technologies, both marketers and policy makers are interested in the presence of causal ... Keywords: diffusion models, empirical IO methods, endogeneity, probability models, social contagion, word of mouth

Bryan Bollinger; Kenneth Gillingham

2012-11-01T23:59:59.000Z

313

Reaction-diffusion systems with constant diffusivities: conditional symmetries and form-preserving transformations  

E-Print Network (OSTI)

Q-conditional symmetries (nonclassical symmetries) for a general class of two-component reaction-diffusion systems with constant diffusivities are studied. Using the recently introduced notion of Q-conditional symmetries of the first type (R. Cherniha J. Phys. A: Math. Theor., 2010. vol. 43., 405207), an exhaustive list of reaction-diffusion systems admitting such symmetry is derived. The form-preserving transformations for this class of systems are constructed and it is shown that this list contains only non-equivalent systems. The obtained symmetries permit to reduce the reaction-diffusion systems under study to two-dimensional systems of ordinary differential equations and to find exact solutions. As a non-trivial example, multiparameter families of exact solutions are explicitly constructed for two nonlinear reaction-diffusion systems. A possible interpretation to a biologically motivated model is presented.

Roman Cherniha; Vasyl' Davydovych

2013-04-24T23:59:59.000Z

314

Disposal barriers that release contaminants only by molecular diffusion  

Science Conference Proceedings (OSTI)

Engineered barriers can slow the movement of pollutants out of land disposal facilities in several ways. If the advective velocity is low, release will be primarily by molecular diffusion. Attenuation processes also work to slow the transport of many contaminants. Barriers that cause pollutants to be released almost entirely by molecular diffusion represent the best barriers achievable. Use of thick barrier materials will maximize the breakthrough time of contaminants that diffuse through the barrier. Thin barriers with exceedingly low permeabilities will not necessarily outperform thicker, more permeable liners. In fact, if diffusion is the dominant mechanism of release, the thicker, more permeable barrier may actually outperform the thinner barrier with lower permeability.

Daniel, D.E.; Shackelford, C.D.

1988-01-01T23:59:59.000Z

315

FLAMMABLE GAS DIFFUSION THROUGH SINGLE SHELL TANK (SST) DOMES  

DOE Green Energy (OSTI)

This report quantified potential hydrogen diffusion through Hanford Site Single-Shell tank (SST) domes if the SSTs were hypothetically sealed airtight. Results showed that diffusion would keep headspace flammable gas concentrations below the lower flammability limit in the 241-AX and 241-SX SST. The purpose of this document is to quantify the amount of hydrogen that could diffuse through the domes of the SSTs if they were hypothetically sealed airtight. Diffusion is assumed to be the only mechanism available to reduce flammable gas concentrations. The scope of this report is limited to the 149 SSTs.

MEACHAM, J.E.

2003-11-10T23:59:59.000Z

316

A Mechanism and Simple Dynamical Model of the North Atlantic Oscillation and Annular Modes  

Science Conference Proceedings (OSTI)

A simple dynamical model is presented for the basic spatial and temporal structure of the large-scale modes of intraseasonal variability and associated variations in the zonal index. Such variability in the extratropical atmosphere is known to be ...

Geoffrey K. Vallis; Edwin P. Gerber; Paul J. Kushner; Benjamin A. Cash

2004-02-01T23:59:59.000Z

317

On Adding Thermodynamic Damping Mechanisms to Refine Two Classical Models of Katabatic Winds  

Science Conference Proceedings (OSTI)

The Prandtl and layer-averaged models of katabatic winds contain some nonphysical singularities in the analytical solutions, which give unbounded steady flow anomalies at zero slope angles or adiabatic lapse rates. This study presents some simple ...

Ruping Mo

2013-07-01T23:59:59.000Z

318

Mechanisms for Wave Packet Formation and Maintenance in a Quasigeostrophic Two-Layer Model  

Science Conference Proceedings (OSTI)

A quasigeostrophic, two-layer, ?-plane channel model is used to investigate the dynamics of baroclinic wave packets. A series of experiments are performed in which an unstable flow is maintained by lower-level Ekman friction and radiative ...

J. G. Esler; P. H. Haynes

1999-08-01T23:59:59.000Z

319

An agent-based model of the cognitive mechanisms underlying the origins of creative cultural evolution  

Science Conference Proceedings (OSTI)

Human culture is uniquely cumulative and open-ended. Using a computational model of cultural evolution in which neural network based agents evolve ideas for actions through invention and imitation, we tested the hypothesis that this is due to the capacity ... Keywords: EVOC, action, agent-based model, creativity, cultural diversity, cultural evolution, gesture, homo erectus, innovation, invention, mimetic, origin of culture, recursive recall, self-triggered recall and rehearsal loop

Liane Gabora; Maryam Saberi

2011-11-01T23:59:59.000Z

320

Quantum diffusion in the quasiperiodic kicked rotor  

E-Print Network (OSTI)

We study the mechanisms responsible for quantum diffusion in the quasiperiodic kicked rotor. We report experimental measurements of the diffusion constant on the atomic version of the system and develop a theoretical approach (based on the Floquet theorem) explaining the observations, especially the ``sub-Fourier'' character of the resonances observed in the vicinity of exact periodicity, i.e. the ability of the system to distinguish two neighboring driving frequencies in a time shorter than the inverse of the difference of the two frequencies.

Hans Lignier; Jean Claude Garreau; Pascal Szriftgiser; Dominique Delande

2004-12-02T23:59:59.000Z

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321

An Experimental Field Dataset with Buoyant, Neutral, and Dense Gas Atmospheric Releases and Model Comparisons in Low–Wind Speed (Diffusion) Conditions  

Science Conference Proceedings (OSTI)

A unique field dataset from a series of low–wind speed experiments, modeling efforts using three commonly used models to replicate these releases, and statistical analysis of how well these models were able to predict the plume concentrations is ...

Veronica E. Wannberg; Gustavious Williams; Patrick Sawyer; Richard Venedam

2010-09-01T23:59:59.000Z

322

An interacting-agent model of financial markets from the viewpoint of Nonextensive statistical mechanics  

E-Print Network (OSTI)

In this paper we present an interacting-agent model of financial markets. We describe a financial market through an Ising model to formulate the tendency of agents getting influenced by the other agents' investment attitude [8]. We formulate the agents' decision making on investment as the {\\it minimum energy principle for Tsallis entropy [11]}, and demonstrate that the equilibrium probability distribution function of the investment attitude of interacting-agents is the {\\it q-exponential distribution}. We also show that the power-law distribution of volatility of price fluctuations, which is often demonstrated in the empirical studies [17], can be explained naturally by our model that have their origin in the collective crowd behavior of many interacting-agents.

Kaizoji, T

2006-01-01T23:59:59.000Z

323

Enforcement Documents - Portsmouth Gaseous Diffusion Plant | Department of  

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

Portsmouth Gaseous Diffusion Plant Portsmouth Gaseous Diffusion Plant Enforcement Documents - Portsmouth Gaseous Diffusion Plant March 26, 2010 Enforcement Letter, Intennech, Inc. - March 26, 2010 Enforcement Letter issued to Intermech, Inc. related to Installation and Inspection of Anchor Bolts and Pipe Supports at the DUF6 Conversion Buildings at the Portsmouth and Paducah Gaseous Diffusion Plants March 26, 2010 Enforcement Letter, Geiger Brothers Mechanical Contractors, INC - March 26, 2010 Enforcement Letter issued to Geiger Brothers Mechanical Contractors, Inc. related to Installation and Inspection of Penetration Fire Seals at the DUF6 Conversion Building at the Portsmouth Gaseous Diffusion Plant March 26, 2010 Consent Order, Uranium Disposition Services, LLC - NCO-2010-01 Consent Order issued to Uranium Disposition Services, LLC related to

324

Determination of Matrix Diffusion Properties of Granite  

Science Conference Proceedings (OSTI)

Rock-core column experiments were introduced to estimate the diffusion and sorption properties of Kuru Grey granite used in block-scale experiments. The objective was to examine the processes causing retention in solute transport through rock fractures, especially matrix diffusion. The objective was also to estimate the importance of retention processes during transport in different scales and flow conditions. Rock-core columns were constructed from cores drilled into the fracture and were placed inside tubes to form flow channels in the 0.5 mm gap between the cores and the tube walls. Tracer experiments were performed using uranin, HTO, {sup 36}Cl, {sup 131}I, {sup 22}Na and {sup 85}Sr at flow rates of 1-50 {mu}L.min{sup -1}. Rock matrix was characterized using {sup 14}C-PMMA method, scanning electron microscopy (SEM), energy dispersive X-ray micro analysis (EDX) and the B.E.T. method. Solute mass flux through a column was modelled by applying the assumption of a linear velocity profile and molecular diffusion. Coupling of the advection and diffusion processes was based on the model of generalised Taylor dispersion in the linear velocity profile. Experiments could be modelled applying a consistent parameterization and transport processes. The results provide evidence that it is possible to investigate matrix diffusion at the laboratory scale. The effects of matrix diffusion were demonstrated on the slightly-sorbing tracer breakthrough curves. Based on scoping calculations matrix diffusion begins to be clearly observable for non-sorbing tracer when the flow rate is 0.1 {mu}L.min{sup -1}. The experimental results presented here cannot be transferred directly to the spatial and temporal scales that prevail in an underground repository. However, the knowledge and understanding of transport and retention processes gained from this study is transferable to different scales from laboratory to in-situ conditions. (authors)

Holtta, Pirkko; Siitari-Kauppi, Marja; Huittinen, Nina [Laboratory of Radiochemistry, P.O. Box 55, University of Helsinki, FI-00014 (Finland); Poteri, Antti [VTT Processes, P.O. Box 1608, VTT, FI-02044 (Finland)

2007-07-01T23:59:59.000Z

325

Development of an ash particle deposition model considering build-up and removal mechanisms  

SciTech Connect

Slagging and fouling on heat exchanger surfaces in power boilers fired with fossil fuels and fuel mixtures has a significant influence on boiler efficiency and availability. Mathematical modelling has long been considered a suitable method to assist boiler operators to determine optimized operating conditions for an existing furnace. The ultimate goal in ash deposition prediction is hereby the determination of the total amount of material deposited and hence the determination of the total reduction in efficiency. Depending on the fuels fired the total deposited mass is a combination of ash particle deposition and ash particle erosion due to non-sticky particles. The novel ash particle deposition model presented in this work considers deposition of sticky ash particles, cleansing of deposit by non-sticky sand particles and sticking of sand due to contact with sticky ash. The steady-state modelling results for the total amount of ash deposited on the deposition probe of an entrained flow reactor presented in this work agree well with the experimental data. Only at very high fractions of sand added as non-sticky material, a significant influence of the sand on the overall mass deposited was found. Since the model considers sticking of non-sticking sand due to contact with sticky ash, the fraction of sand deposited on the probe was especially studied. Using a correction factor to consider the influence of operating time on the steady-state simulations led to good agreement between simulations and experimental data. 12 refs., 10 figs.

Kjell Strandstroem; Christian Muellera; Mikko Hupa [Abo Akademi Process Chemistry Centre, Abo (Finland)

2007-12-15T23:59:59.000Z

326

A finite element model for hygro-thermo-mechanical analysis of masonry walls with FRP reinforcement  

Science Conference Proceedings (OSTI)

Modeling the effects of humidity and temperature gradients on the structural behavior of masonry walls reinforced with fiber reinforced polymer (FRP) composite is of great importance. Study of interfacial stresses, in particular, is a key factor in predicting ... Keywords: FRP reinforced masonry, Moisture and temperature, Multi-layered permeable structure, Structural analysis

Mehran Khoshbakht; Mark W. Lin

2010-10-01T23:59:59.000Z

327

Southern “Annular Modes” Simulated by a Climate Model—Patterns, Mechanisms, and Uses  

Science Conference Proceedings (OSTI)

Both high-latitude (HLM) and low-latitude modes (LLM) of variability of zonal wind in the Southern Hemisphere have been identified. Through an analysis of a simulation for 1871–2200 by the CSIRO Mark 3 climate model, the extent to which these ...

I. G. Watterson

2007-09-01T23:59:59.000Z

328

Statistical properties of agent-based models in markets with continuous double auction mechanism  

E-Print Network (OSTI)

Real world markets display power-law features in variables such as price fluctuations in stocks. To further understand market behavior, we have conducted a series of market experiments on our web-based prediction market platform which allows us to reconstruct transaction networks among traders. From these networks, we are able to record the degree of a trader, the size of a community of traders, the transaction time interval among traders and other variables that are of interest. The distributions of all these variables show power-law behavior. On the other hand, agent-based models have been proposed to study the properties of real financial markets. We here study the statistical properties of these agent-based models and compare them with the results from our web-based market experiments. In this work, three agent-based models are studied, namely, zero-intelligence (ZI), zero-intelligence-plus (ZIP) and Gjerstad-Dickhaut (GD). Computer simulations of variables based on these three agent-based models were car...

Tseng, Jie-Jun; Lin, Chih-Ting; Wang, Sun-Chong; Li, Sai-Ping; 10.1016/j.physa.2009.12.034

2010-01-01T23:59:59.000Z

329

A model study on the circuit mechanism underlying decision-making in Drosophila  

Science Conference Proceedings (OSTI)

Previous elegant experiments in a flight simulator showed that conditioned Drosophila is able to make a clear-cut decision to avoid potential danger. When confronted with conflicting visual cues, the relative saliency of two competing cues is found to ... Keywords: Attention, Decision-making, Dopamine modulation, Drosophila, Feature binding, Systems-level circuit model

Zhihua Wu; Aike Guo

2011-05-01T23:59:59.000Z

330

Analytical modelling of hydrogen transport in reactor containments  

E-Print Network (OSTI)

There are two diffusion processes, molecular and turbulent, which should be modelled in different ways. Molecular diffusion is modelled by Wilke's formula for the multi-component gas diffusion, where the diffusion constants ...

Manno, V.

1983-01-01T23:59:59.000Z

331

MechanicalTesting  

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

structures, validation of encapsulant cure stress models, development of frac- ture mechanics tests for use in adhesion studies and understanding the failure mechanism of...

332

Infinite cloud model of electrification by the precipitation mechanism in the presence of high rates of ion generation  

SciTech Connect

We have extended a simple, infinite cloud, precipitation mechanism model of thundercloud electrification to include effects due to the presence of radioactive aerosol particles resulting from fresh debris from a nuclear explosion. These effects involve ion generation, currents due to motions of ions and charged aerosol particles, and collection of ions and aerosol particles by hydrometeors and cloud droplets. Our conclusion is that an ion pair generation rate G> or approx. =10/sup 12/m/sup -3/ s/sup -1/ will prevent significant electric field growth.

Spangler, J.D.; Rosenkilde, C.E.

1979-06-20T23:59:59.000Z

333

Infinite cloud model of electrification by the precipitation mechanism in the pressence of high rates of ion generation  

SciTech Connect

We have extended a simple, infinite-cloud, precipitation-mechanism model of thundercloud electrification to include effects due to the presence of radioactive aerosol particles. These effects involve ion generation, currents due to motions of ions and charged aerosol particles, and collection of ions and aerosol particles by hydrometeors and cloud droplets. Our conclusion is that an ion-pair generation rate G equal to or greater than 10/sup 12/m/sup -3/s/sup -1/ will prevent significant electric-field growth.

Spangler, J.D.; Rosenkilde, C.E.

1978-06-19T23:59:59.000Z

334

Emergence of Quantum Mechanics from a Sub-Quantum Statistical Mechanics  

E-Print Network (OSTI)

A research program within the scope of theories on "Emergent Quantum Mechanics" is presented, which has gained some momentum in recent years. Via the modeling of a quantum system as a non-equilibrium steady-state maintained by a permanent throughput of energy from the zero-point vacuum, the quantum is considered as an emergent system. We implement a specific "bouncer-walker" model in the context of an assumed sub-quantum statistical physics, in analogy to the results of experiments by Couder's group on a classical wave-particle duality. We can thus give an explanation of various quantum mechanical features and results on the basis of a "21st century classical physics", such as the appearance of Planck's constant, the Schr\\"odinger equation, etc. An essential result is given by the proof that averaged particle trajectories' behaviors correspond to a specific type of anomalous diffusion termed "ballistic" diffusion on a sub-quantum level. It is further demonstrated both analytically and with the aid of computer simulations that our model provides explanations for various quantum effects such as double-slit or n-slit interference. We show the averaged trajectories emerging from our model to be identical to Bohmian trajectories, albeit without the need to invoke complex wave functions or any other quantum mechanical tool. Finally, the model provides new insights into the origins of entanglement, and, in particular, into the phenomenon of a "systemic" nonlocality.

Gerhard Groessing

2013-04-12T23:59:59.000Z

335

A quantum mechanical model for the relationship between stock price and stock ownership  

SciTech Connect

The trade of a fixed stock can be regarded as the basic process that measures its momentary price. The stock price is exactly known only at the time of sale when the stock is between traders, that is, only in the case when the owner is unknown. We show that the stock price can be better described by a function indicating at any moment of time the probabilities for the possible values of price if a transaction takes place. This more general description contains partial information on the stock price, but it also contains partial information on the stock owner. By following the analogy with quantum mechanics, we assume that the time evolution of the function describing the stock price can be described by a Schroedinger type equation.

Cotfas, Liviu-Adrian [Faculty of Economic Cybernetics, Statistics and Informatics, Academy of Economic Studies, 6 Piata Romana, 010374 Bucharest (Romania)

2012-11-01T23:59:59.000Z

336

A quantum mechanical model for the relationship between stock price and stock ownership  

E-Print Network (OSTI)

The trade of a fixed stock can be regarded as the basic process that measures its momentary price. The stock price is exactly known only at the time of sale when the stock is between traders, that is, only in the case when the owner is unknown. We show that the stock price can be better described by a function indicating at any moment of time the probabilities for the possible values of price if a transaction takes place. This more general description contains partial information on the stock price, but it also contains partial information on the stock owner. By following the analogy with quantum mechanics, we assume that the time evolution of the function describing the stock price can be described by a Schrodinger type equation.

Liviu-Adrian Cotfas

2012-07-14T23:59:59.000Z

337

Electrophoretic Migration and Axial Diffusion of Individual Nanoparticles in Cylindrical Nanopores  

SciTech Connect

Membranes with straight, vertical nanopores have found widespread applications in chemical and biological sciences, including separation, detection, catalysis, and drug delivery. They can also serve as a model system to understand molecular behavior and fundamental mechanisms of separation, bridging the gap between conventional model systems such as flat surfaces and real chromatographic stationary phases such as micrometer-sized porous particles. We recently found that the axial motion of individual biomolecules inside nanopores can be significantly slower than in bulk solution. This suggests that either chromatographic adsorption was present and/or the viscosity inside the nanopores was unusually high. In this study, we measured the electrophoretic motion as well as the axial diffusion of individual nanoparticles in cylindrical alumina nanopores. We found that the electrophoretic mobilities and the diffusion coefficients of polystyrene nanoparticles were both substantially smaller compared to bulk solution independent of particle size or pore diameter. The results imply that the apparent solution viscosity in nanodomains is anomalous.

Han, Rui; Wang, Gufeng; Qi, Shengda; Ma, Changbei; Yeung, Edward S.

2012-08-01T23:59:59.000Z

338

Training and Research on Probabilistic Hydro-Thermo-Mechanical Modeling of Carbon Dioxide Geological Sequestration in Fractured Porous Rocks  

SciTech Connect

Colorado School of Mines conducted research and training in the development and validation of an advanced CO{sub 2} GS (Geological Sequestration) probabilistic simulation and risk assessment model. CO{sub 2} GS simulation and risk assessment is used to develop advanced numerical simulation models of the subsurface to forecast CO2 behavior and transport; optimize site operational practices; ensure site safety; and refine site monitoring, verification, and accounting efforts. As simulation models are refined with new data, the uncertainty surrounding the identified risks decrease, thereby providing more accurate risk assessment. The models considered the full coupling of multiple physical processes (geomechanical and fluid flow) and describe the effects of stochastic hydro-mechanical (H-M) parameters on the modeling of CO{sub 2} flow and transport in fractured porous rocks. Graduate students were involved in the development and validation of the model that can be used to predict the fate, movement, and storage of CO{sub 2} in subsurface formations, and to evaluate the risk of potential leakage to the atmosphere and underground aquifers. The main major contributions from the project include the development of: 1) an improved procedure to rigorously couple the simulations of hydro-thermomechanical (H-M) processes involved in CO{sub 2} GS; 2) models for the hydro-mechanical behavior of fractured porous rocks with random fracture patterns; and 3) probabilistic methods to account for the effects of stochastic fluid flow and geomechanical properties on flow, transport, storage and leakage associated with CO{sub 2} GS. The research project provided the means to educate and train graduate students in the science and technology of CO{sub 2} GS, with a focus on geologic storage. Specifically, the training included the investigation of an advanced CO{sub 2} GS simulation and risk assessment model that can be used to predict the fate, movement, and storage of CO{sub 2} in underground formations, and the evaluation of the risk of potential CO{sub 2} leakage to the atmosphere and underground aquifers.

Gutierrez, Marte

2013-05-31T23:59:59.000Z

339

A Simple Quantum-Mechanical Model of Spacetime II: Thermodynamics of Spacetime  

E-Print Network (OSTI)

In this second part of our series of two papers, where spacetime is modelled by a graph, where Planck size quantum black holes lie on the vertices, we consider the thermodynamics of spacetime. We formulate an equation which tells in which way an accelerating, spacelike two-surface of spacetime interacts with the thermal radiation flowing through that surface. In the low temperature limit, where most quantum black holes constituting spacetime are assumed to lie in the ground state, our equation implies, among other things, the Hawking and the Unruh effects, as well as Einstein's field equation with a vanishing cosmological constant for general matter fields. We also consider the high temperature limit, where the microscopic black holes are assumed to lie in highly excited states. In this limit our model implies, among other things, that black hole entropy depends logarithmically on its area, instead of being proportional to the area.

J. Makela

2008-05-26T23:59:59.000Z

340

Injection-Molded Long-Fiber Thermoplastic Composites: From Process Modeling to Prediction of Mechanical Properties  

SciTech Connect

This article illustrates the predictive capabilities for long-fiber thermoplastic (LFT) composites that first simulate the injection molding of LFT structures by Autodesk® Simulation Moldflow® Insight (ASMI) to accurately predict fiber orientation and length distributions in these structures. After validating fiber orientation and length predictions against the experimental data, the predicted results are used by ASMI to compute distributions of elastic properties in the molded structures. In addition, local stress-strain responses and damage accumulation under tensile loading are predicted by an elastic-plastic damage model of EMTA-NLA, a nonlinear analysis tool implemented in ABAQUS® via user-subroutines using an incremental Eshelby-Mori-Tanaka approach. Predicted stress-strain responses up to failure and damage accumulations are compared to the experimental results to validate the model.

Nguyen, Ba Nghiep; Kunc, Vlastimil; Jin, Xiaoshi; Tucker III, Charles L.; Costa, Franco

2013-12-18T23:59:59.000Z

Note: This page contains sample records for the topic "diffusion mechanisms 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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341

Hydrogen trapping, diffusion, and recombination in austenitic stainless steels  

DOE Green Energy (OSTI)

Trapping, diffusion, and recombination of hydrogen in austenitic stainless steels are reviewed. It is suggested that since all of these processes are strongly interdependent and since the measured recombination rates are found to vary four orders of magnitude at any temperature, the data analysis techniques used to date are insufficient. A two-region diffusion model with surface recombination is proposed in which the surface layer is characterized by a smaller diffusion coefficient than the bulk.

Langley, R.A.

1984-01-01T23:59:59.000Z

342

Class of model problems in three-body quantum mechanics that admit exact solutions  

Science Conference Proceedings (OSTI)

An approach to solving scattering problems in three-body systems for cases where the mass of one of the particles is extremely small in relation to the masses of the other two particles and where the pair potentials of interaction between the particles involved are separable is developed. Exact analytic solutions to such model problems are found for the scattering of a light particle on two fixed centers and on two interacting heavy particles. It is shown that new resonances and a dynamical resonance enhancement may appear in a three-body system.

Takibayev, N. Zh., E-mail: teta@nursat.kz [Abay Kazakh National Pedagogical University (Kazakhstan)

2008-03-15T23:59:59.000Z

343

Lipid Flip-Flop Driven Mechanical and Morphological Changes in Model Membranes  

E-Print Network (OSTI)

We study, using dissipative particle dynamics simulations, the effect of active lipid flip-flop on model fluid bilayer membranes. We consider both cases of symmetric as well as asymmetric flip-flops. Symmetric flip-flop leads to a steady state of the membrane with an effective temperature higher than that of the equilibrium membrane and an effective surface tension lower than that of the equilibrium membrane. Asymmetric flip-flop leads to transient conformational changes of the membrane in the form of bud or blister formation, depending on the flip rate.

Sanoop Ramachandran; P. B. Sunil Kumar; Mohamed Laradji

2008-07-31T23:59:59.000Z

344

Zigzagging causility model of EPR correlations and on the interpretation of quantum mechanics  

Science Conference Proceedings (OSTI)

Being formalized inside the S-matrix scheme, the zigzagging causility model of EPR correlations has full Lorentz and CPT invariance. EPR correlations, proper or reversed, and Wheeler's smoky dragon metaphor are respectively pictured in a spacetime or in the momentum-energy space, as V-shaped, anti LAMBDA-shaped, or C-shaped ABC zigzags, with a summation at B over virtual states absolute value B>=*. The reversibility = * implies that causality is CPT-invariant, or arrowless, at the microlevel. Arrowed causality is a macroscopic emergence, corollary to wave retardation and probability increase. Factlike irreversibility states repression, not suppression, of blind statistical retrodiction- that is, of final cause.

de Beauregard, O.C.

1988-09-01T23:59:59.000Z

345

Modeling shear failure and permeability enhancement due to coupled Thermal-Hydrological-Mechanical processes in Enhanced Geothermal Reservoirs  

Science Conference Proceedings (OSTI)

The connectivity and accessible surface area of flowing fractures, whether natural or man-made, is possibly the single most important factor, after temperature, which determines the feasibility of an Enhanced Geothermal System (EGS). Rock deformation and in-situ stress changes induced by injected fluids can lead to shear failure on preexisting fractures which can generate microseismic events, and also enhance the permeability and accessible surface area of the geothermal formation. Hence, the ability to accurately model the coupled thermal-hydrologic-mechanical (THM) processes in fractured geological formations is critical in effective EGS reservoir development and management strategies. The locations of the microseismic events can serve as indicators of the zones of enhanced permeability, thus providing vital information for verification of the coupled THM models. We will describe a general purpose computational code, FEHM, developed for this purpose, that models coupled THM processes during multiphase fluid flow and transport in fractured porous media. The code incorporates several models of fracture aperture and stress behavior combined with permeability relationships. We provide field scale examples of applications to geothermal systems to demonstrate the utility of the method.

Kelkar, Sharad [Los Alamos National Laboratory

2011-01-01T23:59:59.000Z

346

A new modeling approach of STLF with integrated dynamics mechanism and based on the fusion of dynamic optimal neighbor phase points and ICNN  

Science Conference Proceedings (OSTI)

Based on the time evolution similarity principle of the topological neighbor phase points in the Phase Space Reconstruction (PSR), a new modeling approach of Short-Term Load Forecasting (STLF) with integrated dynamics mechanism and based on the fusion ...

Zhisheng Zhang; Yaming Sun; Shiying Zhang

2006-05-01T23:59:59.000Z

347

Erbium diffusion in silicon dioxide  

SciTech Connect

Erbium diffusion in silicon dioxide layers prepared by magnetron sputtering, chemical vapor deposition, and thermal growth has been investigated by secondary ion mass spectrometry, and diffusion coefficients have been extracted from simulations based on Fick's second law of diffusion. Erbium diffusion in magnetron sputtered silicon dioxide from buried erbium distributions has in particular been studied, and in this case a simple Arrhenius law can describe the diffusivity with an activation energy of 5.3{+-}0.1 eV. Within a factor of two, the erbium diffusion coefficients at a given temperature are identical for all investigated matrices.

Lu Yingwei; Julsgaard, B.; Petersen, M. Christian [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Jensen, R. V. Skougaard [Department of Physics and Nanotechnology, Aalborg University, DK-9220 Aalborg O (Denmark); Pedersen, T. Garm; Pedersen, K. [Department of Physics and Nanotechnology, Aalborg University, DK-9220 Aalborg O (Denmark); Interdisciplinary Nanoscience Center-iNANO, DK-8000 Aarhus C (Denmark); Larsen, A. Nylandsted [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Interdisciplinary Nanoscience Center-iNANO, DK-8000 Aarhus C (Denmark)

2010-10-04T23:59:59.000Z

348

Results of tritium experiments on ceramic electrolysis cells and palladium diffusers for application to fusion reactor fuel cleanup systems  

Science Conference Proceedings (OSTI)

Tritium tests at the Tritium Systems Test Assembly have demonstrated that ceramic electrolysis cells and palladium alloy diffuser developed in Japan are possible components for a fusion reactor fuel cleanup system. Both components have been successfully operated with tritium for over a year. A failure of the first electrolysis cell was most likely the result of an over voltage on the ceramic. A simple circuit was developed to eliminate this mode of failure. The palladium diffusers tubes exhibited some degradation of mechanical properties as a result of the build up of helium from the tritium decay, after 450 days of operation with tritium, however the effects were not significant enough to affect the performance. New models of the diffuser and electrolysis cell, providing higher flow rates and more tritium compatible designs are currently being tested with tritium. 8 refs., 5 figs.

Carlson, R.V.; Binning, K.E.; Konishi, S.; Yoshida, H.; Naruse, Y.

1987-01-01T23:59:59.000Z

349

Adaptive Breast Radiation Therapy Using Modeling of Tissue Mechanics: A Breast Tissue Segmentation Study  

Science Conference Proceedings (OSTI)

Purpose: To validate and compare the accuracy of breast tissue segmentation methods applied to computed tomography (CT) scans used for radiation therapy planning and to study the effect of tissue distribution on the segmentation accuracy for the purpose of developing models for use in adaptive breast radiation therapy. Methods and Materials: Twenty-four patients receiving postlumpectomy radiation therapy for breast cancer underwent CT imaging in prone and supine positions. The whole-breast clinical target volume was outlined. Clinical target volumes were segmented into fibroglandular and fatty tissue using the following algorithms: physical density thresholding; interactive thresholding; fuzzy c-means with 3 classes (FCM3) and 4 classes (FCM4); and k-means. The segmentation algorithms were evaluated in 2 stages: first, an approach based on the assumption that the breast composition should be the same in both prone and supine position; and second, comparison of segmentation with tissue outlines from 3 experts using the Dice similarity coefficient (DSC). Breast datasets were grouped into nonsparse and sparse fibroglandular tissue distributions according to expert assessment and used to assess the accuracy of the segmentation methods and the agreement between experts. Results: Prone and supine breast composition analysis showed differences between the methods. Validation against expert outlines found significant differences (P<.001) between FCM3 and FCM4. Fuzzy c-means with 3 classes generated segmentation results (mean DSC = 0.70) closest to the experts' outlines. There was good agreement (mean DSC = 0.85) among experts for breast tissue outlining. Segmentation accuracy and expert agreement was significantly higher (P<.005) in the nonsparse group than in the sparse group. Conclusions: The FCM3 gave the most accurate segmentation of breast tissues on CT data and could therefore be used in adaptive radiation therapy-based on tissue modeling. Breast tissue segmentation methods should be used with caution in patients with sparse fibroglandular tissue distribution.

Juneja, Prabhjot, E-mail: Prabhjot.Juneja@icr.ac.uk [Joint Department of Physics, Institute of Cancer Research, Sutton (United Kingdom)] [Joint Department of Physics, Institute of Cancer Research, Sutton (United Kingdom); Harris, Emma J. [Joint Department of Physics, Institute of Cancer Research, Sutton (United Kingdom)] [Joint Department of Physics, Institute of Cancer Research, Sutton (United Kingdom); Kirby, Anna M. [Department of Academic Radiotherapy, Royal Marsden National Health Service Foundation Trust, Sutton (United Kingdom)] [Department of Academic Radiotherapy, Royal Marsden National Health Service Foundation Trust, Sutton (United Kingdom); Evans, Philip M. [Joint Department of Physics, Institute of Cancer Research, Sutton (United Kingdom)] [Joint Department of Physics, Institute of Cancer Research, Sutton (United Kingdom)

2012-11-01T23:59:59.000Z

350

Development Status of the PEBBLES Code for Pebble Mechanics: Improved Physical Models and Speed-up  

SciTech Connect

PEBBLES is a code for simulating the motion of all the pebbles in a pebble bed reactor. Since pebble bed reactors are packed randomly and not precisely placed, the location of the fuel elements in the reactor is not deterministically known. Instead, when determining operating parameters the motion of the pebbles can be simulated and stochastic locations can be found. The PEBBLES code can output information relevant for other simulations of the pebble bed reactors such as the positions of the pebbles in the reactor, packing fraction change in an earthquake, and velocity profiles created by recirculation. The goal for this level three milestone was to speedup the PEBBLES code through implementation on massively parallel computer. Work on this goal has resulted in speeding up both the single processor version and creation of a new parallel version of PEBBLES. Both the single processor version and the parallel running capability of the PEBBLES code have improved since the fiscal year start. The hybrid MPI/OpenMP PEBBLES version was created this year to run on the increasingly common cluster hardware profile that combines nodes with multiple processors that share memory and a cluster of nodes that are networked together. The OpenMP portions use the Open Multi-Processing shared memory parallel processing model to split the task across processors in a single node that shares memory. The Message Passing Interface (MPI) portion uses messages to communicate between different nodes over a network. The following are wall clock speed up for simulating an NGNP-600 sized reactor. The single processor version runs 1.5 times faster compared to the single processor version at the beginning of the fiscal year. This speedup is primarily due to the improved static friction model described in the report. When running on 64 processors, the new MPI/OpenMP hybrid version has a wall clock speed up of 22 times compared to the current single processor version. When using 88 processors, a speed up of 23 times is achieved. This speedup and other improvements of PEBBLES combine to make PEBBLES more capable and more useful for simulation of a pebble bed reactor. This report details the implementation and effects of the speedup work done over the course of the fiscal year.

Joshua J. Cogliati; Abderrafi M. Ougouag

2009-12-01T23:59:59.000Z

351

Development Status of the PEBBLES Code for Pebble Mechanics: Improved Physical Models and Speed-up  

DOE Green Energy (OSTI)

PEBBLES is a code for simulating the motion of all the pebbles in a pebble bed reactor. Since pebble bed reactors are packed randomly and not precisely placed, the location of the fuel elements in the reactor is not deterministically known. Instead, when determining operating parameters the motion of the pebbles can be simulated and stochastic locations can be found. The PEBBLES code can output information relevant for other simulations of the pebble bed reactors such as the positions of the pebbles in the reactor, packing fraction change in an earthquake, and velocity profiles created by recirculation. The goal for this level three milestone was to speedup the PEBBLES code through implementation on massively parallel computer. Work on this goal has resulted in speeding up both the single processor version and creation of a new parallel version of PEBBLES. Both the single processor version and the parallel running capability of the PEBBLES code have improved since the fiscal year start. The hybrid MPI/OpenMP PEBBLES version was created this year to run on the increasingly common cluster hardware profile that combines nodes with multiple processors that share memory and a cluster of nodes that are networked together. The OpenMP portions use the Open Multi-Processing shared memory parallel processing model to split the task across processors in a single node that shares memory. The Message Passing Interface (MPI) portion uses messages to communicate between different nodes over a network. The following are wall clock speed up for simulating an NGNP-600 sized reactor. The single processor version runs 1.5 times faster compared to the single processor version at the beginning of the fiscal year. This speedup is primarily due to the improved static friction model described in the report. When running on 64 processors, the new MPI/OpenMP hybrid version has a wall clock speed up of 22 times compared to the current single processor version. When using 88 processors, a speed up of 23 times is achieved. This speedup and other improvements of PEBBLES combine to make PEBBLES more capable and more useful for simulation of a pebble bed reactor. This report details the implementation and effects of the speedup work done over the course of the fiscal year.

Joshua J. Cogliati; Abderrafi M. Ougouag

2009-09-01T23:59:59.000Z

352

Collective motion in quantum diffusive environment  

E-Print Network (OSTI)

The general problem of dissipation in macroscopic large-amplitude collective motion and its relation to energy diffusion of intrinsic degrees of freedom of a nucleus is studied. By applying the cranking approach to the nuclear many-body system, a set of coupled dynamical equations for the collective classical variable and the quantum mechanical occupancies of the intrinsic nuclear states is derived. Different dynamical regimes of the intrinsic nuclear motion and its consequences on time properties of collective dissipation are discussed.

V. M. Kolomietz; S. Å berg; S. V. Radionov

2007-06-16T23:59:59.000Z

353

A mechanics-based virtual model of NEES-UCSD shake table : theoretical development and experimental validation  

E-Print Network (OSTI)

17th ASCE Engineering Mechanics Conference , Newark, U.S.A,Journal of Engineering Mechanics, ASCE , 129(12). Thoen, B.Journal of Engineering Mechanics , 129(12), 2003. Van Den

Ozcelik, Ozgur

2008-01-01T23:59:59.000Z

354

Predicting information diffusion on social networks with partial knowledge  

Science Conference Proceedings (OSTI)

Models of information diffusion and propagation over large social media usually rely on a Close World Assumption: information can only propagate onto the network relational structure, it cannot come from external sources, the network structure ... Keywords: diffusion, machine learning, social networks

Anis Najar; Ludovic Denoyer; Patrick Gallinari

2012-04-01T23:59:59.000Z

355

Measurement of Solute Diffusion Behavior in Fractured Waste Glass Media  

SciTech Connect

Determination of aqueous phase diffusion coefficients of solutes through fractured media is essential for understanding and modeling contaminants transport at many hazardous waste disposal sites. No methods for earlier measurements are available for the characterization of diffusion in fractured glass blocks. We report here the use of time-lag diffusion experimental method to assess the diffusion behavior of three different solutes (Cs, Sr and Pentafluoro Benzoic Acid or PFBA) in fractured, immobilized low activity waste (ILAW) glass forms. A fractured media time-lag diffusion experimental apparatus that allows the measurement of diffusion coefficients has been designed and built for this purpose. Use of time-lag diffusion method, a considerably easier experimental method than the other available methods, was not previously demonstrated for measuring diffusion in any fractured media. Hydraulic conductivity, porosity and diffusion coefficients of a solute were experimentally measured in fractured glass blocks using this method for the first time. Results agree with the range of properties reported for similar rock media earlier, indicating that the time-lag experimental method can effectively characterize the diffusion coefficients of fractured ILAW glass media.

Saripalli, Kanaka P.; Lindberg, Michael J.; Meyer, Philip D.

2008-10-01T23:59:59.000Z

356

Performance Evaluation of K-DEMO Cable-in-conduit Conductors Using the Florida Electro-Mechanical Cable Model  

Science Conference Proceedings (OSTI)

The United States ITER Project Office (USIPO) is responsible for design of the Toroidal Field (TF) insert coil, which will allow validation of the performance of significant lengths of the conductors to be used in the full scale TF coils in relevant conditions of field, current density and mechanical strain. The Japan Atomic Energy Agency (JAEA) will build the TF insert which will be tested at the Central Solenoid Model Coil (CSMC) Test facility at JAEA, Naka, Japan. Three dimensional mathematical model of TF Insert was created based on the initial design geometry data, and included the following features: orthotropic material properties of superconductor material and insulation; external magnetic field from CSMC, temperature dependent properties of the materials; pre-compression and plastic deformation in lap joint. Major geometrical characteristics of the design were preserved including cable jacket and insulation shape, mandrel outline, and support clamps and spacers. The model is capable of performing coupled structural, thermal, and electromagnetic analysis using ANSYS. Numerical simulations were performed for room temperature conditions; cool down to 4K, and the operating regime with 68kA current at 11.8 Tesla background field. Numerical simulations led to the final design of the coil producing the required strain levels on the cable, while simultaneously satisfying the ITER magnet structural design criteria.

Zhai, Yuhu

2013-07-16T23:59:59.000Z

357

PERPENDICULAR DIFFUSION OF COSMIC RAYS FOR A GOLDREICH-SRIDHAR SPECTRUM  

SciTech Connect

Perpendicular diffusion coefficients and mean free paths of cosmic particles are computed for an anisotropic Alfvenic turbulence spectrum corresponding to the Goldreich-Sridhar model by employing an enhanced nonlinear guiding center theory. The calculations are important for understanding cosmic ray propagation in the Galaxy and in the solar system. In addition, the knowledge of diffusion coefficients is also useful for modeling charged particles which experience diffusive shock acceleration in supernova remnants and at interplanetary shock waves. To replace the parallel diffusion coefficient in our equation for the perpendicular diffusion coefficient, we employ different models such as quasilinear results and phenomenological models. The results are compared with those derived earlier. We demonstrate that the choice of the turbulence model as well as the choice of the model for the parallel diffusion coefficient has a strong influence on the perpendicular diffusion coefficient.

Shalchi, A. [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada); Buesching, I.; Schlickeiser, R. [Institut fuer Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); Lazarian, A., E-mail: andreasm4@yahoo.co [Astronomy Department, University of Wisconsin, Madison, WI 53706 (United States)

2010-12-20T23:59:59.000Z

358

THERMO-HYDRO-MECHANICAL MODELING OF WORKING FLUID INJECTION AND THERMAL ENERGY EXTRACTION IN EGS FRACTURES AND ROCK MATRIX  

DOE Green Energy (OSTI)

Development of enhanced geothermal systems (EGS) will require creation of a reservoir of sufficient volume to enable commercial-scale heat transfer from the reservoir rocks to the working fluid. A key assumption associated with reservoir creation/stimulation is that sufficient rock volumes can be hydraulically fractured via both tensile and shear failure, and more importantly by reactivation of naturally existing fractures (by shearing), to create the reservoir. The advancement of EGS greatly depends on our understanding of the dynamics of the intimately coupled rock-fracture-fluid-heat system and our ability to reliably predict how reservoirs behave under stimulation and production. Reliable performance predictions of EGS reservoirs require accurate and robust modeling for strongly coupled thermal-hydrological-mechanical (THM) processes. Conventionally, these types of problems have been solved using operator-splitting methods, usually by coupling a subsurface flow and heat transport simulators with a solid mechanics simulator via input files. An alternative approach is to solve the system of nonlinear partial differential equations that govern multiphase fluid flow, heat transport, and rock mechanics simultaneously, using a fully coupled, fully implicit solution procedure, in which all solution variables (pressure, enthalpy, and rock displacement fields) are solved simultaneously. This paper describes numerical simulations used to investigate the poro- and thermal- elastic effects of working fluid injection and thermal energy extraction on the properties of the fractures and rock matrix of a hypothetical EGS reservoir, using a novel simulation software FALCON (Podgorney et al., 2011), a finite element based simulator solving fully coupled multiphase fluid flow, heat transport, rock deformation, and fracturing using a global implicit approach. Investigations are also conducted on how these poro- and thermal-elastic effects are related to fracture permeability evolution.

Robert Podgorney; Chuan Lu; Hai Huang

2012-01-01T23:59:59.000Z

359

MASSIVELY PARALLEL FULLY COUPLED IMPLICIT MODELING OF COUPLED THERMAL-HYDROLOGICAL-MECHANICAL PROCESSES FOR ENHANCED GEOTHERMAL SYSTEM RESERVOIRS  

SciTech Connect

Development of enhanced geothermal systems (EGS) will require creation of a reservoir of sufficient volume to enable commercial-scale heat transfer from the reservoir rocks to the working fluid. A key assumption associated with reservoir creation/stimulation is that sufficient rock volumes can be hydraulically fractured via both tensile and shear failure, and more importantly by reactivation of naturally existing fractures (by shearing) to create the reservoir. The advancement of EGS greatly depends on our understanding of the dynamics of the intimately coupled rock-fracture-fluid system and our ability to reliably predict how reservoirs behave under stimulation and production. In order to increase our understanding of how reservoirs behave under these conditions, we have developed a physics-based rock deformation and fracture propagation simulator by coupling a discrete element model (DEM) for fracturing with a continuum multiphase flow and heat transport model. In DEM simulations, solid rock is represented by a network of discrete elements (often referred as particles) connected by various types of mechanical bonds such as springs, elastic beams or bonds that have more complex properties (such as stress-dependent elastic constants). Fracturing is represented explicitly as broken bonds (microcracks), which form and coalesce into macroscopic fractures when external load is applied. DEM models have been applied to a very wide range of fracturing processes from the molecular scale (where thermal fluctuations play an important role) to scales on the order of 1 km or greater. In this approach, the continuum flow and heat transport equations are solved on an underlying fixed finite element grid with evolving porosity and permeability for each grid cell that depends on the local structure of the discrete element network (such as DEM particle density). The fluid pressure gradient exerts forces on individual elements of the DEM network, which therefore deforms and fractures. Such deformation/fracturing in turn changes the permeability, which again changes the evolution of fluid pressure, coupling the two phenomena. The intimate coupling between fracturing and fluid flow makes the meso-scale DEM simulations necessary, as these methods have substantial advantages over conventional continuum mechanical models of elastic rock deformation. The challenges that must be overcome to simulate EGS reservoir stimulation, preliminary results, progress to date and near future research directions and opportunities will be discussed.

Robert Podgorney; Hai Huang; Derek Gaston

2010-02-01T23:59:59.000Z

360

Measurements of the Effects of Gravity Waves in the Middle Atmosphere Using Parametric Models of Density Fluctuations. Part II: Energy Dissipation and Eddy Diffusion  

Science Conference Proceedings (OSTI)

Part I of this series demonstrated the advantages of parametric models in estimating the gravity wave spectrum from density fluctuation measurements using a large power-aperture-product Rayleigh-scatter lidar. The spectra calculated using the ...

R. J. Sica

1999-05-01T23:59:59.000Z

Note: This page contains sample records for the topic "diffusion mechanisms 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.


361

Microsoft Word - Evaluation of an Incremental Ventilation Energy Model for Estimating Impacts of Air Sealing and Mechanical Ventilation_Final2.docx  

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

XXXXX | Logue et al., Evaluation of an Incremental Ventilation Energy Model for Estimating XXXXX | Logue et al., Evaluation of an Incremental Ventilation Energy Model for Estimating Impacts of Air Sealing and Mechanical Ventilation 1 Evaluation of an Incremental Ventilation Energy Model for Estimating Impacts of Air Sealing and Mechanical Ventilation Jennifer M. Logue, William J. N. Turner, Iain S. Walker, and Brett C. Singer Environmental Energy Technologies Division June 2012 LBNL-5796E LBNL-XXXXX | Logue et al., Evaluation of an Incremental Ventilation Energy Model for Estimating Impacts of Air Sealing and Mechanical Ventilation 2 Disclaimer This document was prepared as an account of work sponsored by the United States Government. While this document is believed to contain correct information, neither the United States Government nor any agency thereof, nor The Regents of the University of California, nor

362

Diffusion on (110) Surface of Molecular Crystal Pentaerythritol Tetranitrate  

SciTech Connect

Using classical molecular dynamics simulations, we investigate the diffusion mechanisms of admolecules on the (110) surface of molecular crystal pentaerythritol tetranitrate. Our results show that (1) admolecules are stable at off lattice sites, (2) admolecules diffuse along close-packed [1{bar 1}1] and [{bar 1}11] directions, and (3) admolecules detach from the surface at 350K and above. Based on the number of diffusion jumps as a function of temperature, we estimate the jump frequency to be v=1.14 x 10{sup 12} e{sup -0.08eV/kT} per second.

Wang, J; Golfinopoulos, T; Gee, R H; Huang, H

2007-01-25T23:59:59.000Z

363

Effect of pressure on arsenic diffusion in germanium  

SciTech Connect

We report preliminary results of a study of the activation volume for diffusion of arsenic in germanium. High-temperature high-pressure anneals were performed in a liquid argon pressure medium in a diamond anvil cell capable of reaching 5 GPa and 750 C,l which is externally heated for uniform and repeatable temperature profiles. Broadening of an ion-implanted arsenic profile was measured by Secondary Ion Mass Spectrometry. Hydrostatic pressure retards the diffusivity at 575 C, characterized by an activation volume that is +15% of the atomic volume of Ge. Implications for diffusion mechanisms are discussed.

Mitha, S.; Theiss, S.D.; Aziz, M.J. [Harvard Univ., Cambridge, MA (United States); Schiferl, D. [Los Alamos National Lab., NM (United States); Poker, D.B. [Oak Ridge National Lab., TN (United States)

1994-01-01T23:59:59.000Z

364

The Diffusion Kernel Filter Applied to Lagrangian Data Assimilation  

Science Conference Proceedings (OSTI)

The diffusion kernel filter is a sequential particle-method approach to data assimilation of time series data and evolutionary models. The method is applicable to nonlinear/non-Gaussian problems. Within branches of prediction it parameterizes ...

Paul Krause; Juan M. Restrepo

2009-12-01T23:59:59.000Z

365

Effect of Reduced Diffusion on Surface Wind and Wave Fields  

Science Conference Proceedings (OSTI)

Horizontal diffusion is used in meteorological models to reduce noise in the shorter spatial scales and to increase numerical stability. In turn, this affects the surface wind distribution. A series of tests on real situations in the ...

Luigi Cavaleri; Luciana Bertotti; Mariano Hortal; Martin Miller

1997-11-01T23:59:59.000Z

366

Diffusion driven object propulsion in density stratified fluids  

E-Print Network (OSTI)

An experimental study was conducted in order to verify the appropriateness of a two dimensional model of the flow creating diffusion driven object propulsion in density stratified fluids. Initial flow field experiments ...

Lenahan, Conor (Conor P.)

2009-01-01T23:59:59.000Z

367

International diffusion practice : lessons from South Korea's New Village Movement  

E-Print Network (OSTI)

This research focuses on how South Korea's development model-namely, the Saemaul Undong, or the New Village Movement-is diffused internationally, in particular, to the developing country of Vietnam. South Korea's successful ...

Kim, Jung Hwa, M.C.P. Massachusetts Institute of Technology

2013-01-01T23:59:59.000Z

368

Complementarity and Classical Limit of Quantum Mechanics: Energy Measurement aspects  

E-Print Network (OSTI)

In the present contribution we discuss the role of experimental limitations in the classical limit problem. We studied some simple models and found that Quantum Mechanics does not re-produce classical mechanical predictions, unless we consider the experimental limitations ruled by uncertainty principle. We have shown that the discrete nature of energy levels of integrable systems can be accessed by classical measurements. We have defined a precise limit for this procedure. It may be used as a tool to define the classical limit as far as the discrete spectra of integrable systems are concerned. If a diffusive environment is considered, we conclude that the "lifetime" of discreteness is approximately $1/\\kappa$ ($\\kappa$ is the diffusion constant), thus it was possible to relate the classical limit of a spectra with the action of an environment and experimental resolution.

Adélcio C. Oliveira; Zolacir T. Oliveira Junior; Nestor S. Correia

2013-07-01T23:59:59.000Z

369

Free radicals in biological energy conversion: EPR studies of model systems. Final report. [Mechanism of chlorophyll participation in photosynthesis  

DOE Green Energy (OSTI)

Energy conversion in photosynthesis is known to proceed via light-induced one-electron transfer reactions involving chlorophyll and electron donors and acceptors. Although the chemical identities of all of the components have not as yet been elucidated, considerable evidence has been accumulated which points to quinones (Q) as primary electron acceptors in both green plants and bacterial photosynthesis. Furthermore, it has been established that the initial photoprocess leads to the formation of a chlorophyll cation radical (C./sup +/). The research described in this report has as its goal the elucidation of the molecular-electronic mechanism of chlorophyll participation in photosynthesis. The following reactions have been observed: (a) Photoproduction of C./sup +/ in solution in the absence of added electron acceptors. This is a low quantum yield reaction which proceeds via the lowest excited singlet state. Bacteriochlorophyll also undergoes this reaction, whereas pheophytin does not. (b) One-electron phototransfer between the chlorophyll lowest triplet state and quinones to yield a radical pair (C./sup +/ - Q./sup +/). This may either recombine or separate. The C./sup +/ formed upon separation is unstable and reacts with hydroxylic compounds to regenerate chlorophyll. The Q./sup -/ species partly reacts with oxidized solvent and partly disproportionates. Both bacteriochlorophyll and pheophytin are also able to react with quinones in this manner. The quenching of the chlorophyll lowest singlet state by quinones does not, however, lead to detectable radical formation. These reactions seem to provide acceptable models for certain aspects of photosynthetic energy conversion, and thus elucidation of their detailed mechanisms should lead to useful insights into the nature of the biological process.

Tollin, G.

1976-08-31T23:59:59.000Z

370

Sampling diffusive transition paths  

SciTech Connect

We address the problem of sampling double-ended diffusive paths. The ensemble of paths is expressed using a symmetric version of the Onsager-Machlup formula, which only requires evaluation of the force field and which, upon direct time discretization, gives rise to a symmetric integrator that is accurate to second order. Efficiently sampling this ensemble requires avoiding the well-known stiffness problem associated with sampling infinitesimal Brownian increments of the path, as well as a different type of stiffness associated with sampling the coarse features of long paths. The fine-features sampling stiffness is eliminated with the use of the fast sampling algorithm (FSA), and the coarse-feature sampling stiffness is avoided by introducing the sliding and sampling (S&S) algorithm. A key feature of the S&S algorithm is that it enables massively parallel computers to sample diffusive trajectories that are long in time. We use the algorithm to sample the transition path ensemble for the structural interconversion of the 38-atom Lennard-Jones cluster at low temperature.

F. Miller III, Thomas; Predescu, Cristian

2006-10-12T23:59:59.000Z

371

Fission Enhanced diffusion of uranium in zirconia N. Brerd, A. Chevarier, N. Moncoffre,  

E-Print Network (OSTI)

Fission Enhanced diffusion of uranium in zirconia N. Bérerd, A. Chevarier, N. Moncoffre, Institut and Fission Enhanced Diffusion (FED) of uranium into zirconia, representative of the inner face of cladding temperature is measured by an IR pyrometer. A model is proposed to deduce an apparent uranium diffusion

Paris-Sud XI, Université de

372

Dose Modeling Evaluations and Technical Support Document for the Authorized Limits Request for the C-746-U Landfill at the Paducah Gaseous Diffusion Plant, Paducah, Kentucky  

SciTech Connect

This report contains the technical basis in support of the DOE?s derivation of Authorized Limits (ALs) for the DOE Paducah C-746-U Landfill. A complete description of the methodology, including an assessment of the input parameters, model inputs, and results is provided in this report. This report also provides initial recommendations on applying the derived soil guidelines. The ORISE-derived soil guidelines are specifically applicable to the Landfill at the end of its operational life. A suggested 'upper bound' multiple of the derived soil guidelines for individual shipments is provided.

Boerner, A. J. [IEAVP, ORISE, Oak Ridge, TN (United States); Maldonado, D. G. [IEAVP, ORISE, Oak Ridge, TN (United States; Hansen, Tom [Ameriphysics, LLC (United States)

2012-06-01T23:59:59.000Z

373

Light diffusing fiber optic chamber  

DOE Patents (OSTI)

A light diffusion system for transmitting light to a target area. The light is transmitted in a direction from a proximal end to a distal end by an optical fiber. A diffusing chamber is operatively connected to the optical fiber for transmitting the light from the proximal end to the distal end and transmitting said light to said target area. A plug is operatively connected to the diffusing chamber for increasing the light that is transmitted to the target area.

Maitland, Duncan J. (Lafayette, CA)

2002-01-01T23:59:59.000Z

374

diffuse radiation | OpenEI  

Open Energy Info (EERE)

Login | Sign Up Wiki Apps Datasets Browse Upload data GDR Community Linked Data Search Share this page on Facebook icon Twitter icon diffuse radiation Dataset Summary...

375

Diffusion Flame Measurements: Notes B  

Science Conference Proceedings (OSTI)

... Profiles in steady and flickering methane/air, ethylene/air, and propane/air diffusion flames at atmospheric pressure using an axisymmetric burner ...

2012-10-17T23:59:59.000Z

376

Tracer Diffusion Databases for ICME  

Science Conference Proceedings (OSTI)

... of a large repository of stable isotopes that can be utilized for tracer diffusion .... Lattice Dynamics and Thermodynamics of Lithium Battery Materials LiMPO4 ...

377

Lithium Diffusion in Graphitic Carbon  

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

Volume 1 Start Page 1176 Issue 8 Pagination 1176-1180 Keywords anode, diffusion, graphene, lithium ion battery, transport Abstract Graphitic carbon is currently considered the...

378

Evolutionary Dynamics of Information Diffusion over Social Networks  

E-Print Network (OSTI)

Current social networks are of extremely large-scale generating tremendous information flows at every moment. How information diffuse over social networks has attracted much attention from both industry and academics. Most of the existing works on information diffusion analysis are based on machine learning methods focusing on social network structure analysis and empirical data mining. However, the dynamics of information diffusion, which are heavily influenced by network users' decisions, actions and their socio-economic interactions, is generally ignored by most of existing works. In this paper, we propose an evolutionary game theoretic framework to model the dynamic information diffusion process in social networks. Specifically, we derive the information diffusion dynamics in complete networks, uniform degree and non-uniform degree networks, with the highlight of two special networks, Erd\\H{o}s-R\\'enyi random network and the Barab\\'asi-Albert scale-free network. We find that the dynamics of information di...

Jiang, Chunxiao; Liu, K J Ray

2013-01-01T23:59:59.000Z

379

Compliant mechanisms  

E-Print Network (OSTI)

The motivation for this work has been a variety of motions like navigation of pipelines, insertion operations in assembly, and gripping actions, which require the adaptation of the mechanism to the external constraints, rather than avoid them. To this effect, efforts have been made in building mechanisms that obtain the required degrees of freedom through deformations rather than explicit joints in them. Although the use of many joints provides the required number of degrees of freedom, it does so at the cost of making the system very bulky and complex. With the advent of new polymers, the possibility of building joint-free mechanisms that fulfil the requirements of adaptation has increased. Based on this approach, a Magneto Active Polymer (MAP) material has been developed here at the Texas A\\&M University, in which the actuation is performed by the conversion of electromagnetic energy into mechanical energy. The initial experimentation has proved the vast potential of the use of such a material and a few mechanisms like a magneto active peristaltic pump, have been designed and tested for the first time using this material. In this mechanism, the pumping action is obtained when a moving magnetic field produces peristaltic waves in the magneto active material shaped as a tube. Also for the first time, experiments have been conducted to analyze the response of the MAP material to a pulsating magnetic field with the intent of using the experimental results to develop a model of the MAP. In developing the design for the peristaltic pump and other conceptual models described in this thesis, ideas have been drawn from the different modes of locomotion and actuators present in lower organisms. These have been good sources of inspiration for the work done in this thesis and they have been documented in detail.

Venkataraghavan, Janarthanan T

2001-01-01T23:59:59.000Z

380

Wafer heating mechanisms in a molecular gas, inductively coupled plasma: in situ, real time wafer surface measurements and three-dimensional thermal modeling  

Science Conference Proceedings (OSTI)

The authors report measurements and modeling of wafer heating mechanisms in an Ar/O{sub 2} inductively coupled plasma (ICP). The authors employed a commercially available on-wafer sensor system (PlasmaTemp developed by KLA-Tencor) consisting of an on-board electronics module housing battery power and data storage with 30 temperature sensors embedded onto the wafer at different radial positions. This system allows for real time, in situ wafer temperature measurements. Wafer heating mechanisms were investigated by combining temperature measurements from the PlasmaTemp sensor wafer with a three-dimensional heat transfer model of the wafer and a model of the ICP. Comparisons between pure Ar and Ar/O{sub 2} discharges demonstrated that two additional wafer heating mechanisms can be important in molecular gas plasmas compared to atomic gas discharges. The two mechanisms are heating from the gas phase and O-atom surface recombination. These mechanisms were shown to contribute as much as 60% to wafer heating under conditions of low bias power. This study demonstrated how the 'on-wafer' temperature sensor not only yields a temperature profile distribution across the wafer, but can be used to help determine plasma characteristics, such as ion flux profiles or plasma processing temperatures.

Titus, M. J.; Graves, D. B. [Department of Chemical Engineering, University of California, Berkeley, California 94720 (United States)

2008-09-15T23:59:59.000Z

Note: This page contains sample records for the topic "diffusion mechanisms 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

Radiometric modeling of mechanical draft cooling towers to assist in the extraction of their absolute temperature from remote thermal imagery.  

E-Print Network (OSTI)

??Determination of the internal temperature of a mechanical draft cooling tower (MDCT) from remotely-sensed thermal imagery is important for many applications that provide input to… (more)

Montanaro, Matthew

2009-01-01T23:59:59.000Z

382

Diffusion of liquid domains in lipid bilayer membranes  

E-Print Network (OSTI)

We report diffusion coeffcients of micron-scale liquid domains in giant unilamellar vesicles of phospholipids and cholesterol. The trajectory of each domain is tracked, and the mean square displacement grows linearly in time as expected for Brownian motion. We study domain dffusion as a function of composition and temperature, and measure how diffusion depends on domain size. We find mechanisms of domain diffusion which are consistent with membrane-dominated drag in viscous Lo phases [P.G. Saffman and M. Delbruck, PNAS 72, 3111 (1975)], and bulk-dominated drag for less viscous L$_\\alpha$ phases [B.D.Hughes et al., J. Fluid Mech. 110, 349 (1981)]. Where applicable, we obtain the membrane viscosity and report activation energies of diffusion.

Pietro Cicuta; Sarah L. Keller; Sarah L. Veatch

2006-11-18T23:59:59.000Z

383

Modeling and Computer Simulation of the Pulsed Powering of Mechanical D.C. Circuit Breakers for the CERN/LHC Superconducting Magnet Energy Extraction System  

E-Print Network (OSTI)

This article presents the results of modeling and computer simulation of non-linear devices such as the Electromagnetic Driver of a D.C. Circuit Breaker. The mechanical and electromagnetic parts of the Driver are represented as equivalent electrical circuits and all basic processes of the Driver's magnetic circuit are calculated.

Anushat, V; Erokhin, A; Kussul, A; Medvedko, A S

2000-01-01T23:59:59.000Z

384

A stochastic variational multiscale method for diffusion in heterogeneous random media  

Science Conference Proceedings (OSTI)

A stochastic variational multiscale method with explicit subgrid modelling is provided for numerical solution of stochastic elliptic equations that arise while modelling diffusion in heterogeneous random media. The exact solution of the governing equations ... Keywords: generalized polynomial chaos, multiscale finite element, operator upscaling, stochastic diffusion, subgrid modelling, variational multiscale

Badrinarayanan Velamur Asokan; Nicholas Zabaras

2006-11-01T23:59:59.000Z

385

U.S. National Committee for Rock Mechanics; and Conceptual model of fluid infiltration in fractured media. Project summary, July 28, 1997--July 27, 1998  

SciTech Connect

The title describes the two tasks summarized in this report. The remainder of the report contains information on meetings held or to be held on the subjects. The US National Committee for Rock Mechanics (USNC/RM) provides for US participation in international activities in rock mechanics, principally through adherence to the International Society for Rock Mechanics (ISRM). It also keeps the US rock mechanics community informed about new programs directed toward major areas of national concern in which rock mechanics problems represent critical or limiting factors, such as energy resources, excavation, underground storage and waste disposal, and reactor siting. The committee also guides or produces advisory studies and reports on problem areas in rock mechanics. A new panel under the auspices of the US National Committee for Rock Mechanics has been appointed to conduct a study on Conceptual Models of Fluid Infiltration in Fractured Media. The study has health and environmental applications related to the underground flow of pollutants through fractured rock in and around mines and waste repositories. Support of the study has been received from the US Nuclear Regulatory Commission and the Department of Energy`s Yucca Mountain Project Office. The new study builds on the success of a recent USNC/RM report entitled Rock Fractures and Fluid Flow: Contemporary Understanding and Applications (National Academy Press, 1996, 551 pp.). A summary of the new study is provided.

1998-09-01T23:59:59.000Z

386

A passive mechanism for thermal stress regulation in micro-machined beam-type structures: Modeling and experiment  

Science Conference Proceedings (OSTI)

In this article, a passive mechanism for thermal stress regulation in micro-bridge structures is proposed. The mechanism is essentially a set of precisely designed parallel chevron beams that replace one of the fixed ends of the micro-bridge. The axial ...

Pezhman A. Hassanpour; Patricia M. Nieva; Amir Khajepour

2012-05-01T23:59:59.000Z

387

Ten iterative steps for model development and evaluation applied to Computational Fluid Dynamics for Environmental Fluid Mechanics  

Science Conference Proceedings (OSTI)

Computational Fluid Dynamics (CFD) is increasingly used to study a wide variety of complex Environmental Fluid Mechanics (EFM) processes, such as water flow and turbulent mixing of contaminants in rivers and estuaries and wind flow and air pollution ... Keywords: Air and water quality, Building aerodynamics, Environmental Fluid Mechanics, River hydraulics, Transverse mixing, Wind flow

B. Blocken; C. Gualtieri

2012-07-01T23:59:59.000Z

388

Local structure of Rb{sub 2}Li{sub 4}(SeO{sub 4}){sub 3}{center_dot}2H{sub 2}O by the modeling of X-ray diffuse scattering - from average-structure to microdomain model  

Science Conference Proceedings (OSTI)

Local structure of dirubidium tetralithium tris(selenate(VI)) dihydrate - Rb{sub 2}Li{sub 4}(SeO{sub 4}){sub 3}{center_dot} 2H{sub 2}O has been determined basing on the modeling of X-ray diffuse scattering. The origin of observed structured diffuse streaks is SeO{sub 4} tetrahedra switching between two alternative positions in two quasi-planar layers existing in each unit cell and formation of domains with specific SeO{sub 4} tetrahedra configuration locally fulfilling condition for C-centering in the 2a Multiplication-Sign 2b Multiplication-Sign c superstructure cell. The local structure solution is characterized by a uniform distribution of rather large domains (ca. thousand of unit cells) in two layers, but also monodomains can be taken into account. Inside a single domain SeO{sub 4} tetrahedra are ordered along ab-diagonal forming two-string ribbons. Inside the ribbons SeO{sub 4} and LiO{sub 4} tetrahedra share the oxygen corners, whereas ribbons are bound to each other by a net of hydrogen bonds and fastened by corner sharing SeO{sub 4} tetrahedra of the neighboring layers. - Graphical abstract: Experimental sections of the reciprocal space showing diffraction effects observed for RLSO. Bragg spots are visible on sections with integer indices (1 kl section - on the left), streaks - on sections with fractional ones (1.5 kl section - on the right). At the center: resulting local structure of the A package modeled as a microdomain: two-string ribbons of ordered oxygen-corners-sharing SeO{sub 4} and LiO{sub 4} terahedra extended along ab-diagonal are seen; ribbons are bound by hydrogen bonds (shown in pink); the multiplied 2a Multiplication-Sign 2b unit cell is shown. Highlights: Black-Right-Pointing-Pointer X-ray diffuse scattering in RLSO was registered and modeled. Black-Right-Pointing-Pointer The origin of diffuse streaks is SeO{sub 4} tetrahedra switching in two structure layers. Black-Right-Pointing-Pointer The local structure is characterized by a uniform distribution of microdomains. Black-Right-Pointing-Pointer Inside a single domain SeO{sub 4} tetrahedra are ordered along ab-diagonal forming ribbons. Black-Right-Pointing-Pointer The ribbons are bound to each other by a net of hydrogen bonds.

Komornicka, Dorota [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, ul. Okolna 2, 50-420 Wroclaw (Poland); Wolcyrz, Marek, E-mail: m.wolcyrz@int.pan.wroc.pl [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, ul. Okolna 2, 50-420 Wroclaw (Poland); Pietraszko, Adam [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, ul. Okolna 2, 50-420 Wroclaw (Poland)

2012-08-15T23:59:59.000Z

389

Non-Brownian molecular self-diffusion in bulk water  

E-Print Network (OSTI)

The paper presents the velocity autocorrelation spectrum of bulk water measured by a new technique of NMR modulated gradient spin echo method. This technique is unprecedented for the spectrum measurement in the frequency interval between a few Hz to about 100 kHz with respect to directness and clarity of results and shows that a simple model of Brownian self-diffusion is not applicable to describe the diffusion dynamics of water molecules. The observed temperature dependant spectra of water show the existence of a slow chain-like dynamics in water, which we explain by coupling of diffusing molecule to broken bonds in the hydrogen bond network.

Janez Stepišnik; Aleš Mohori?; Igor Serša

2010-10-06T23:59:59.000Z

390

Two-Dimensional Simulations of Drainage Winds and Diffusion Compared to Observations  

Science Conference Proceedings (OSTI)

A vertically integrated dynamical drainage flow model is developed from conservation equations for momentum and mass in a terrain-following coordinate system. Wind fields from the dynamical model drive a Monte Carlo transport and diffusion model. ...

Alfred J. Garrett; Frank G. Smith III

1984-04-01T23:59:59.000Z

391

Sensitivity of the Ocean’s Climate to Diapycnal Diffusivity in an EMIC. Part I: Equilibrium State  

Science Conference Proceedings (OSTI)

The diapycnal diffusivity in the ocean is one of the least known parameters in current climate models. Measurements of this diffusivity are sparse and insufficient for compiling a global map. Inferences from inverse methods and energy budget ...

Fabio Dalan; Peter H. Stone; Igor V. Kamenkovich; Jeffery R. Scott

2005-07-01T23:59:59.000Z

392

Statistics of the Air-Sea Fluxes of Momentum and Mechanical Energy in a Coupled Wave-Atmosphere Model  

Science Conference Proceedings (OSTI)

An atmospheric general circulation model (GCM) and a wind wave model are coupled through the wind stress. The wind stress which forces the wave model, depends in the coupled model on the stage of development of the wave field. As the waves depend ...

Susanne L. Weber

1994-06-01T23:59:59.000Z

393

A Mechanism for the Increase of Wind Stress (Drag) Coefficient with Wind Speed over Water Surfaces: A Parametric Model  

Science Conference Proceedings (OSTI)

A mechanism is proposed for a physical explanation of the increase in wind stress (drag) coefficient with wind speed over water surfaces. The formula explicitly incorporates the contribution of both winds and waves through the parameterizations ...

S. A. Hsu

1986-01-01T23:59:59.000Z

394

Diffuser for augmenting a wind turbine  

DOE Patents (OSTI)

A diffuser for augmenting a wind turbine having means for energizing the boundary layer at several locations along the diffuser walls is improved by the addition of a short collar extending radially outward from the outlet of the diffuser.

Foreman, Kenneth M. (North Bellmore, NY); Gilbert, Barry L. (Westbury, NY)

1984-01-01T23:59:59.000Z

395

Distributed Energy Resources Market Diffusion Model  

E-Print Network (OSTI)

8] Energy Efficiency Standards Group. (2005) Tariff Analysistariffs and DER technology cost and performance data to run the Distributed Energy

Maribu, Karl Magnus; Firestone, Ryan; Marnay, Chris; Siddiqui, Afzal S.

2006-01-01T23:59:59.000Z

396

Distributed Energy Resources Market Diffusion Model  

E-Print Network (OSTI)

Generators The 2004 electricity tariffs for electriccomponents of a typical electricity tariff are: volumetricAll components of the electricity tariff are multiplied by

Maribu, Karl Magnus; Firestone, Ryan; Marnay, Chris; Siddiqui, Afzal S.

2006-01-01T23:59:59.000Z

397

Distributed Energy Resources Market Diffusion Model  

E-Print Network (OSTI)

s database of U.S. electricity rates [8]. The three main2 shows the 2004 electricity rates for all four cities. The2: Assumed 2004 electricity rates for commercial buildings (

Maribu, Karl Magnus; Firestone, Ryan; Marnay, Chris; Siddiqui, Afzal S.

2006-01-01T23:59:59.000Z

398

Distributed Energy Resources Market Diffusion Model  

E-Print Network (OSTI)

heat exchangers and absorption chillers, heat recovered fromand cooling via an absorption chiller. Cost and performanceto be 5 and that of absorption chillers to be 0.7. Table 1:

Maribu, Karl Magnus; Firestone, Ryan; Marnay, Chris; Siddiqui, Afzal S.

2006-01-01T23:59:59.000Z

399

Distributed Energy Resources Market Diffusion Model  

E-Print Network (OSTI)

of Electricity Delivery and Energy Reliability, Distributed Energy Program of the U.S. Department of Energy under regions are chosen to represent the diversity in U.S. climate and energy rates: Atlanta, Boston, Chicago, with the use of the building energy simulation program DOE-2, specific to various representative U.S. locations

400

Distributed Energy Resources Market Diffusion Model  

E-Print Network (OSTI)

International Journal of Distributed Energy Resources, 1 (Gas-Fired Distributed Energy Resources Characterizations.Firestone, R. (2004) Distributed Energy Resources Customer

Maribu, Karl Magnus; Firestone, Ryan; Marnay, Chris; Siddiqui, Afzal S.

2006-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "diffusion mechanisms 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

Distributed Energy Resources Market Diffusion Model  

E-Print Network (OSTI)

regional differences in energy markets and climates, as welldiverse climates and energy markets. These differences areanalyze the effect of other energy market policies in future

Maribu, Karl Magnus; Firestone, Ryan; Marnay, Chris; Siddiqui, Afzal S.

2006-01-01T23:59:59.000Z

402

Distributed Energy Resources Market Diffusion Model  

E-Print Network (OSTI)

commercial building load profiles, with the use of theTo generate the load profiles, the widely used buildingweekdays have the average load profile for remaining non-

Maribu, Karl Magnus; Firestone, Ryan; Marnay, Chris; Siddiqui, Afzal S.

2006-01-01T23:59:59.000Z

403

1 NUMERICAL MODELING OF COUNTERFLOW DIFFUSION ...  

Science Conference Proceedings (OSTI)

... of the inhibition, and a new cycle involving FeOOH ... on Counterflow Combustion of Liquid Fuel with Diluted ... Flames of Hydrocarbon Fuels With CF3Br ...

2012-09-07T23:59:59.000Z

404

Distributed Energy Resources Market Diffusion Model  

E-Print Network (OSTI)

heat recovery and absorption cooling 6. CONCLUSIONS ANDto recover heat, and absorption cooling is the most commonapplications and cooling via an absorption chiller. Cost and

Maribu, Karl Magnus; Firestone, Ryan; Marnay, Chris; Siddiqui, Afzal S.

2006-01-01T23:59:59.000Z

405

Investigations of Near-Field Thermal-Hydrologic-Mechanical-Chemical Models for Radioactive Waste Disposal in Clay/Shale Rock  

Science Conference Proceedings (OSTI)

Clay/shale has been considered as potential host rock for geological disposal of high-level radioactive waste throughout the world, because of its low permeability, low diffusion coefficient, high retention capacity for radionuclides, and capability to self-seal fractures. For example, Callovo-Oxfordian argillites at the Bure site, France (Fouche et al., 2004), Toarcian argillites at the Tournemire site, France (Patriarche et al., 2004), Opalinus Clay at the Mont Terri site, Switzerland (Meier et al., 2000), and Boom clay at the Mol site, Belgium (Barnichon and Volckaert, 2003) have all been under intensive scientific investigation (at both field and laboratory scales) for understanding a variety of rock properties and their relationships to flow and transport processes associated with geological disposal of radioactive waste. Figure 1-1 presents the distribution of clay/shale formations within the USA.

Liu, H.H.; Li, L.; Zheng, L.; Houseworth, J.E.; Rutqvist, J.

2011-06-20T23:59:59.000Z

406

Diffusion Barrier Characteristic and Breakdown Mechanism of Ni3P ...  

Science Conference Proceedings (OSTI)

... Transformations, and Reactive Phase Formation in Electronic Materials XII ... electrical signal delay and power loss in high-frequency electronic devices.

407

Modelling of thermo-mechanical and irradiation behavior of metallic and oxide fuels for sodium fast reactors  

E-Print Network (OSTI)

A robust and reliable code to model the irradiation behavior of metal and oxide fuels in sodium cooled fast reactors is developed. Modeling capability was enhanced by adopting a non-empirical mechanistic approach to the ...

Karahan, Aydin

2009-01-01T23:59:59.000Z

408

Application of diffusion research to solar energy policy issues  

DOE Green Energy (OSTI)

This paper examines two types of information requirements that appear to be basic to DOE solar-energy-policy decisions: (1) how can the future market success of solar energy technologies be estimated, and (2) what factors influence the adoption of solar energy technologies, and what specific programs could promote solar energy adoption most effectively. This paper assesses the ability of a body of research, referred to here as diffusion research, to supply information that could partially satisfy these requirements. This assessment proceeds, first, by defining in greater detail a series of policy issues that face DOE. These are divided into cost reduction and performance improvement issues which include issues confronting the technology development component of the solar energy program, and barriers and incentives issues which are most relevant to problems of solar energy application. Second, these issues are translated into a series of questions that the diffusion approach can help resolve. Third, various elements within diffusion research are assessed in terms of their abilities to answer policy questions. Finally, the strengths and limitations of current knowledge about the diffusion of innovations are summarized, the applicability of both existing knowledge and the diffusion approach to the identified solar-energy-policy issues are discussed, and ways are suggested in which diffusion approaches can be modified and existing knowledge employed to meet short- and long-term goals of DOE. The inquiry covers the field of classical diffusion research, market research and consumer behavior, communication research, and solar-energy market-penetration modeling.

Roessner, J. D.; Posner, D.; Shoemaker, F.; Shama, A.

1979-03-01T23:59:59.000Z

409

FLAME STRUCTURE MEASUREMENT OF POLYMER DIFFUSION FLAMES  

E-Print Network (OSTI)

of counterflow diffusion flames above condensed fuels:of counterflow diffusion flames in the forward stagnationCA, October 15-16, 1979 FLAME STRUCTURE MEASUREMENT OF

Pitz, W. J.

2011-01-01T23:59:59.000Z

410

Solar mechanics thermal response capabilities.  

DOE Green Energy (OSTI)

In many applications, the thermal response of structures exposed to solar heat loads is of interest. Solar mechanics governing equations were developed and integrated with the Calore thermal response code via user subroutines to provide this computational simulation capability. Solar heat loads are estimated based on the latitude and day of the year. Vector algebra is used to determine the solar loading on each face of a finite element model based on its orientation relative to the sun as the earth rotates. Atmospheric attenuation is accounted for as the optical path length varies from sunrise to sunset. Both direct and diffuse components of solar flux are calculated. In addition, shadowing of structures by other structures can be accounted for. User subroutines were also developed to provide convective and radiative boundary conditions for the diurnal variations in air temperature and effective sky temperature. These temperature boundary conditions are based on available local weather data and depend on latitude and day of the year, consistent with the solar mechanics formulation. These user subroutines, coupled with the Calore three-dimensional thermal response code, provide a complete package for addressing complex thermal problems involving solar heating. The governing equations are documented in sufficient detail to facilitate implementation into other heat transfer codes. Suggestions for improvements to the approach are offered.

Dobranich, Dean D.

2009-07-01T23:59:59.000Z

411

High-level open evolvable systems design by process-oriented modeling: application to DNA replication mechanism  

Science Conference Proceedings (OSTI)

Open Evolvable Systems' design requires a methodological [1] and conceptual paradigm different from the conventional software design. Evolvable Systems' research [2, 6, 16, and 17] has established itself as a new research field, but the content is more ... Keywords: abstractions, design, design patterns, evolvable systems, framework, method, methodologies, modeling, process-oriented modeling, requirements analysis, requirements and architecture modeling, software engineering, specification

Behzad Bastani; Hoda Bastani

2007-11-01T23:59:59.000Z

412

Diffusion of Hydrogen in Titanium  

Science Conference Proceedings (OSTI)

Sep 1, 1994 ... TMS Member price: 10.00. Non-member price: 25.00. TMS Student Member price : 10.00. Product In Stock. Description The diffusion of ...

413

Programming reaction-diffusion processors  

Science Conference Proceedings (OSTI)

In reaction-diffusion (RD) processors, both the data and the results of the computation are encoded as concentration profiles of the reagents. The computation is performed via the spreading and interaction of wave fronts. Most prototypes of RD computers ...

Andrew Adamatzky

2004-09-01T23:59:59.000Z

414

Infinite cloud model of electrification by the precipitation mechanism in a possible rainout situation. Interim report, 14 January 1976--30 July 1977  

SciTech Connect

This report examines the extent to which the ionization associated with a radioactive aerosol will limit electric field growth in a thundercloud. Favored mechanisms for thundercloud electrification, called precipitation mechanisms, involve charge separation in collisions between falling hydrometeors and cloud droplets followed by separation of the resulting charged objects as the hydrometeors fall through the cloud and the droplets move with the updraft. We have extended a simple, infinite-cloud, precipitation-mechanism model to include effects due to the presence of radioactive aerosol particles. These effects involve ion generation, convection currents due to motions of ions and charged aerosol particles, and collection of ions and aerosol particles by hydrometeors and cloud droplets.

Spangler, J.D.

1977-01-01T23:59:59.000Z

415

Microstructural Evolution and interfacial motion in systems with diffusion barriers  

SciTech Connect

This research program was designed to model and simulate phase transformations in systems containing diffusion barriers. The modeling work included mass flow, phase formation, and microstructural evolution in interdiffusing systems. Simulation work was done by developing Cahn-Hilliard and phase field equations governing both the temporal and spatial evolution of the composition and deformation fields and other important phase variables.

Perry H. Leo

2009-03-05T23:59:59.000Z

416

Patterns of Turbulent and Double-Diffusive Phenomena: Observations from a Rapid-Profiling Microconductivity Probe  

Science Conference Proceedings (OSTI)

Throughout much of the ocean interior, the diapycnal buoyancy flux is maintained by both mechanical and double-diffusive processes. Assessing the relative roles of each is a challenge, particularly in complex coastal environments. During February–...

Matthew Alford; Robert Pinkel

2000-05-01T23:59:59.000Z

417

Minimum Uncertainty, Coherence and Squeezing in Diffusion Processes, and Stochastic Quantization  

E-Print Network (OSTI)

We show that uncertainty relations, as well as minimum uncertainty coherent and squeezed states, are structural properties for diffusion processes. Through Nelson stochastic quantization we derive the stochastic image of the quantum mechanical coherent and squeezed states.

Salvatore De Martino; Silvio De Siena; Fabrizio Illuminati; Giuseppe Vitiello

1993-10-18T23:59:59.000Z

418

MINIMUM UNCERTAINTY AND SQUEEZING IN DIFFUSION PROCESSES AND STOCHASTIC QUANTIZATION 1  

E-Print Network (OSTI)

We show that uncertainty relations, as well as minimum uncertainty coherent and squeezed states, are structural properties for diffusion processes. Through Nelson stochastic quantization we derive the stochastic image of the quantum mechanical coherent and squeezed states. 1

S. De Martino; S. De Siena; F. Illuminati; G. Vitiello

1993-01-01T23:59:59.000Z

419

Information diffusion through blogspace  

Science Conference Proceedings (OSTI)

We study the dynamics of information propagation in environments of low-overhead personal publishing, using a large collection of weblogs over time as our example domain. We characterize and model this collection at two levels. First, we present a macroscopic ... Keywords: blogs, information propagation, memes, topic characterization, topic structure, viral propagation, viruses

Daniel Gruhl; R. Guha; David Liben-Nowell; Andrew Tomkins

2004-05-01T23:59:59.000Z

420

LLNL SMP Light Diffuser Fabrication and Preliminary Data  

SciTech Connect

We are developing a cylindrical light diffuser using shape memory polymer (SMP) whose diameter, length, stiffness, and diffusion profile can be tailored to suit a particular application. The cylindrical SMP diffuser is made by casting SMP around the end of a glass optical fiber using a teflon tube as the casting mold, and abrading the cured SMP surface to cause the light to leak radially outward. The inner diameter of the casting tube is slightly larger than the fiber diameter. A smaller teflon tube is positioned over the fiber (between the fiber and the casting tube) to approximately center the fiber tip in the casting tube. As the SMP cures, it bonds with the optical fiber, creating a strong joint without the need for additional adhesives or mechanical fixtures. A close-up of the SMP-fiber joint and the finished SMP diffuser are shown in Fig.1. The SMP formulation (developed in-house) was specifically designed to be optically transparent in the visible and near-infrared regions; the spectral absorption of the SMP is shown in Fig. 2. The low absorption is important because (1) it allows the light to travel the length of the diffuser without suffering excessive loss due to absorption and (2) it permits delivery of up to 7 W (300 {micro}m SMP rod on 100 {micro}m core multimode fiber) of laser power into the diffuser without damaging the diffuser. SMP is a good wave guiding material with a refractive index of approximately 1.5. Also, the SMP stiffness can be tailored from stiff (e.g. acrylic, Ea {approx} 10{sup 9} Pa) to very flexible (e.g. silicon rubber, Ea {approx} 10{sup 6} Pa). Finally, since SMP can self-actuate, the SMP diffuser could be designed to actuate into a shape other than a straight rod (e.g. 2D or 3D coil).

Small IV, W

2006-06-02T23:59:59.000Z

Note: This page contains sample records for the topic "diffusion mechanisms 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.


421

A lattice Boltzmann algorithm for calculation of the laminar jet diffusion flame  

Science Conference Proceedings (OSTI)

A new two-distribution lattice Boltzmann equation (LBE) algorithm is presented to solve the laminar diffusion flames within the context of Burke-Schumann flame sheet model. One distribution models the transport of the Schvab-Zeldovich coupling function, ... Keywords: TVD scheme, laminar diffusion flame, lattice Boltzmann equation, quasi-incompressible flow

Taehun Lee; Ching-Long Lin; Lea-Der Chen

2006-06-01T23:59:59.000Z

422

CORELLI: the Elastic Diffuse Scattering Spectrometer at SNS | ORNL Neutron  

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

The Elastic Diffuse Scattering Spectrometer The Elastic Diffuse Scattering Spectrometer CORELLI The CORELLI instrument. CORELLI is a statistical chopper spectrometer with energy discrimination. It's designed and optimized to probe complex disorder in crystalline materials through diffuse scattering of single-crystal samples. The momentum transfer ranges from 0.5 to 12 Ã…-1, and the energy of incident neutrons ranges from 10 to 200 meV. This instrument combines the high efficiency of white-beam Laue diffraction with energy discrimination by modulating the beam with a statistical chopper. A cross-correlation method is used to reconstruct the elastic signal from the modulated data. Accurate modeling of the short-range order associated with the diffuse scattering requires measurements over large volumes of three-dimensional reciprocal space, with sufficient momentum

423

Low Dose Studies with Focused X-rays in Cell and Tissue Models: Mechanisms of Bystander and Genomic Instability Responses  

SciTech Connect

The management of the risks of exposure of people to ionizing radiation is important in relation to its uses in industry and medicine, also to natural and man-made radiation in the environment. The vase majority of exposures are at a very low level of radiation dose. The risks are of inducing cancer in the exposed individuals and a smaller risk of inducing genetic damage that can be transmitted to children conceived after exposure. Studies of these risks in exposed population studies with any accuracy above the normal levels of cancer and genetic defects unless the dose levels are high. In practice, this means that our knowledge depends very largely on the information gained from the follow-up of the survivors of the atomic bombs dropped on Japanese cities. The risks calculated from these high-dose short-duration exposures then have to be projected down to the low-dose long-term exposures that apply generally. Recent research using cells in culture has revealed that the relations hi between high- and low-dose biological damage may be much more complex than had previously been thought. The aims of this and other projects in the DOE's Low-Dose Program are to gain an understanding of the biological actions of low-dose radiation, ultimately to provide information that will lead to more accurate quantification of low-dose risk. Our project is based on the concept that the processes by which radiation induces cancer start where the individual tracks of radiation impact on cells and tissues. At the dose levels of most low-dose exposures, these events are rare and any individual cells only ''sees'' radiation tracks at intervals averaging from weeks to years apart. This contracts with the atomic bomb exposures where, on average, each cell was hit by hundreds of tracks instantaneously. We have therefore developed microbeam techniques that enable us to target cells in culture with any number of tracks, from one upwards. This approach enables us to study the biological basis of the relationship between high- and low-dose exposures. The targeting approach also allows us to study very clearly a newly recognized effect of radiation, the ''bystander effect'', which appears to dominate some low-dose responses and therefore may have a significant role in low-dose risk mechanisms. Our project also addresses the concept that the background of naturally occurring oxidative damage that takes place continually in cells due to byproducts of metabolism may play a role in treatments that modify the levels of oxidative damage, either alone or in combination with low-dose irradiation. In this project, we have used human and rodent cell lines and each set of experiments has been carried out on a single cell type. However, low-dose research has to extend into tissues because signaling between cells of different types is likely to influence the responses. Our studies have therefore also included microbeam experiments using a model tissue system that consists of an explant of a small piece of pig ureter grown in culture. The structure of this tissue is similar to that of epithelium and there it relates to the tissues in which carcinoma arises. Our studies have been able to measure bystander-induced changes in the cells growing out from the tissue fragment after it has been targeted with a few radiation tracks to mimic a low-dose exposure.

Barry D. Michael; Kathryn Held; Kevin Prise

2002-12-19T23:59:59.000Z

424

Low Dose Studies with Focused X-Rays in cell and Tissue Models: Mechanisms of Bystander and Genomic Instability Responses  

SciTech Connect

The management of the risks of exposure of people to ionizing radiation is important in relation to its uses in industry and medicine, also to natural and man-made radiation in the environment. The vase majority of exposures are at a very low level of radiation dose. The risks are of inducing cancer in the exposed individuals and a smaller risk of inducing genetic damage that can be indicate that they are low. As a result, the risks are impossible to detect in population studies with any accuracy above the normal levels of cancer and genetic defects unless the dose levels are high. In practice, this means that our knowledge depends very largely on the information gained from the follow-up of the survivors of the atomic bombs dropped on Japanese cities. The risks calculated from these high-dose short-duration exposures then have to be projected down to the low-dose long-term exposures that apply generally. Recent research using cells in culture has revealed that the relationship between high- and low-dose biological damage may be much more complex than had previously been thought. The aims of this and other projects in the DOE's Low-Dose Program are to gain an understanding of the biological actions of low-dose radiation, ultimately to provide information that will lead to more accurate quantification of low-dose risk. Our project is based on the concept that the processes by which radiation induces cancer start where the individual tracks of radiation impact on cells and tissues. At the dose levels of most low-dose exposures, these events are rare and any individual cells only ''sees'' radiation tracks at intervals averaging from weeks to years apart. This contrasts with the atomic bomb exposures where, on average, each cell was hit by hundreds of tracks instantaneously. We have therefore developed microbeam techniques that enable us to target cells in culture with any numbers of tracks, from one upwards. This approach enables us to study the biological ha sis of the relationship between high- and low-dose exposures. The targeting approach also allows us to study very clearly a newly recognized effect of radiation, the ''bystander effect'', which appears to dominate some low-dose responses and therefore may have a significant role in low-dose risk mechanisms. Our project also addresses the concept that the background of naturally occurring oxidative damage that takes place continually in cells due to byproducts of metabolism may play a role in low-dose radiation risk. This project therefore also examines how cells are damaged by treatments that modify the levels of oxidative damage, either alone or in combination with low-dose irradiation. In this project, we have used human and rodent cell lines and each set of experiments has been carried out on a single cell type. However, low-dose research has to extend into tissues because signaling between cells of different types is likely to influence the responses. Our studies have therefore also included microbeam experiments using a model tissue system that consists of an explant of a small piece of pig ureter grown in culture. The structure of this tissue is similar to that of epithelium and therefore it relates to the tissues in which carcinoma arises. Our studies have been able to measure bystander-induced changes in the cells growing out from the tissue fragment after it has been targeted with a few radiation tracks to mimic a low-dose exposure.

Kathy Held; Kevin Prise; Barry Michael; Melvyn Folkard

2002-12-14T23:59:59.000Z

425

Multiscale framework for predicting the coupling between deformation and fluid diffusion in porous rocks  

SciTech Connect

In this project, a predictive multiscale framework will be developed to simulate the strong coupling between solid deformations and fluid diffusion in porous rocks. We intend to improve macroscale modeling by incorporating fundamental physical modeling at the microscale in a computationally efficient way. This is an essential step toward further developments in multiphysics modeling, linking hydraulic, thermal, chemical, and geomechanical processes. This research will focus on areas where severe deformations are observed, such as deformation bands, where classical phenomenology breaks down. Multiscale geometric complexities and key geomechanical and hydraulic attributes of deformation bands (e.g., grain sliding and crushing, and pore collapse, causing interstitial fluid expulsion under saturated conditions), can significantly affect the constitutive response of the skeleton and the intrinsic permeability. Discrete mechanics (DEM) and the lattice Boltzmann method (LBM) will be used to probe the microstructure---under the current state---to extract the evolution of macroscopic constitutive parameters and the permeability tensor. These evolving macroscopic constitutive parameters are then directly used in continuum scale predictions using the finite element method (FEM) accounting for the coupled solid deformation and fluid diffusion. A particularly valuable aspect of this research is the thorough quantitative verification and validation program at different scales. The multiscale homogenization framework will be validated using X-ray computed tomography and 3D digital image correlation in situ at the Advanced Photon Source in Argonne National Laboratories. Also, the hierarchical computations at the specimen level will be validated using the aforementioned techniques in samples of sandstone undergoing deformation bands.

Josà © E. Andrade; John W. Rudnicki

2012-12-14T23:59:59.000Z

426

Investigation of the Gas-Diffusion-Electrode Used as Lithium/Air Cathode in Non-aqueous Electrolyte and the Importance of Carbon Material Porosity  

SciTech Connect

The gas-diffusion-electrode used in a Li-air cell has been studied in a unique homemade electrochemical cell. Three major obstacles for the development of a feasible Li-air system were discussed with a focus on the development of a functional gas-diffusion-electrode in non-aqueous electrolytes and the way of avoiding the passivation of gas-diffusion-electrodes caused by the deposition of the reduction products. It is the first time that the importance of establishing the 3-phase electrochemical interface in non-aqueous electrolyte is demonstrated by creating air-diffusion paths and an air saturated portion for an air cathode. A model mechanism of electrode passivation by the reaction products was also proposed. Lithium oxides formed during O{sub 2} reduction tend to block small pores, preventing them from further utilization in the electrochemical reaction. On the other hand, lithium oxides would accumulate inside the large pores during the reduction until the density of oxides becomes high enough to choke-off the mass transfer. Carbon materials with a high surface area associated with larger pores should be selected to make the gas-diffusion-electrode for Li-air battery. For the first time, a near linear relationship between the capacity of GDE in a non-aqueous electrolyte and the average pore diameter was demonstrated, which could be used to estimate the capacity of the GDE quantitatively.

Qu, D.; Yang, X.; Tran, C.

2010-04-02T23:59:59.000Z

427

ME346A Introduction to Statistical Mechanics Wei Cai Stanford University Win 2011 Handout 12. Ising Model  

E-Print Network (OSTI)

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 4.2 Monte Carlo simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4 is destroyed by thermal fluc- tuation. Hence the 2D Ising model has a critical temperature Tc, belo

Cai, Wei

428

An efficient algorithm for solving a multi-layer convection-diffusion problem applied to air pollution problems  

Science Conference Proceedings (OSTI)

An urban scale Eulerian non-reactive multilayer air pollution model is proposed describing convection, turbulent diffusion and emission. A mass-consistent wind field model developed by authors is included in the air pollution model. An Adaptive Finite ... Keywords: Adaptive Finite Element Method, Air pollution modeling, PDE numerical methods, Parabolic convection-diffusion PDE, Parallel algorithm, Splitting methods

L. Ferragut, M. I. Asensio, J. M. Cascón, D. Prieto, J. Ramírez

2013-11-01T23:59:59.000Z

429

Effect of macromolecular crowding on the rate of diffusion-limited enzymatic reaction  

E-Print Network (OSTI)

The cytoplasm of a living cell is crowded with several macromolecules of different shapes and sizes. Molecular diffusion in such a medium becomes anomalous due to the presence of macromolecules and diffusivity is expected to decrease with increase in macromolecular crowding. Moreover, many cellular processes are dependent on molecular diffusion in the cell cytosol. The enzymatic reaction rate has been shown to be affected by the presence of such macromolecules. A simple numerical model is proposed here based on percolation and diffusion in disordered systems to study the effect of macromolecular crowding on the enzymatic reaction rates. The model explains qualitatively some of the experimental observations.

Manish Agrawal; S. B. Santra; Rajat Anand; Rajaram Swaminathan

2008-07-19T23:59:59.000Z

430

Application of the multi-mechanism deformation model for three-dimensional simulations of salt : behavior for the strategic petroleum reserve.  

Science Conference Proceedings (OSTI)

The U.S. Strategic Petroleum Reserve stores crude oil in 62 solution-mined caverns in salt domes located in Texas and Louisiana. Historically, three-dimensional geomechanical simulations of the behavior of the caverns have been performed using a power law creep model. Using this method, and calibrating the creep coefficient to field data such as cavern closure and surface subsidence, has produced varying degrees of agreement with observed phenomena. However, as new salt dome locations are considered for oil storage facilities, pre-construction geomechanical analyses are required that need site-specific parameters developed from laboratory data obtained from core samples. The multi-mechanism deformation (M-D) model is a rigorous mathematical description of both transient and steady-state creep phenomena. Recent enhancements to the numerical integration algorithm within the model have created a more numerically stable implementation of the M-D model. This report presents computational analyses to compare the results of predictions of the geomechanical behavior at the West Hackberry SPR site using both models. The recently-published results using the power law creep model produced excellent agreement with an extensive set of field data. The M-D model results show similar agreement using parameters developed directly from laboratory data. It is also used to predict the behavior for the construction and operation of oil storage caverns at a new site, to identify potential problems before a final cavern layout is designed.

Ehgartner, Brian L.; Sobolik, Steven Ronald; Bean, James E.

2010-07-01T23:59:59.000Z

431

Numerical Simulations of Atmospheric Transport and Diffusion over Coastal Complex Terrain  

Science Conference Proceedings (OSTI)

The purpose of this study was to demonstrate the feasibility of operating the three-dimensional atmospheric models HOTMAC (higher-order turbulence model for atmospheric circulation) and RAPTAD (random puff transport and diffusion) to forecast the ...

T. Yamada; S. Bunker; M. Moss

1992-06-01T23:59:59.000Z

432

Determining Greenland Ice Sheet sensitivity to regional climate change: one-way coupling of a 3-D thermo-mechanical ice sheet model with a mesoscale climate model  

E-Print Network (OSTI)

responsible almost 40% of the ice sheet’s total dischargeCurrently, no coupled Greenland Ice Sheet model experimentaccelerated melting of Greenland ice sheet, Science, v. 313,

Schlegel, Nicole-Jeanne

2011-01-01T23:59:59.000Z

433

THE SPATIO-TEMPORAL EVOLUTION OF SOLAR FLARES OBSERVED WITH AIA/SDO: FRACTAL DIFFUSION, SUB-DIFFUSION, OR LOGISTIC GROWTH?  

SciTech Connect

We explore the spatio-temporal evolution of solar flares by fitting a radial expansion model r(t) that consists of an exponentially growing acceleration phase, followed by a deceleration phase that is parameterized by the generalized diffusion function r(t){proportional_to}{kappa}(t - t{sub 1}){sup {beta}/2}, which includes the logistic growth limit ({beta} = 0), sub-diffusion ({beta} = 0-1), classical diffusion ({beta} = 1), super-diffusion ({beta} = 1-2), and the linear expansion limit ({beta} = 2). We analyze all M- and X-class flares observed with Geostationary Operational Environmental Satellite and Atmospheric Imaging Assembly/Solar Dynamics Observatory (SDO) during the first two years of the SDO mission, amounting to 155 events. We find that most flares operate in the sub-diffusive regime ({beta} = 0.53 {+-} 0.27), which we interpret in terms of anisotropic chain reactions of intermittent magnetic reconnection episodes in a low plasma-{beta} corona. We find a mean propagation speed of v = 15 {+-} 12 km s{sup -1}, with maximum speeds of v{sub max} = 80 {+-} 85 km s{sup -1} per flare, which is substantially slower than the sonic speeds expected for thermal diffusion of flare plasmas. The diffusive characteristics established here (for the first time for solar flares) is consistent with the fractal-diffusive self-organized criticality model, which predicted diffusive transport merely based on cellular automaton simulations.

Aschwanden, Markus J., E-mail: aschwanden@lmsal.com [Lockheed Martin Advanced Technology Center, Solar and Astrophysics Laboratory, Organization ADBS, Building 252, 3251 Hanover Street, Palo Alto, CA 94304 (United States)

2012-09-20T23:59:59.000Z

434

Bohmian Mechanics  

E-Print Network (OSTI)

Bohmian mechanics is a theory about point particles moving along trajectories. It has the property that in a world governed by Bohmian mechanics, observers see the same statistics for experimental results as predicted by quantum mechanics. Bohmian mechanics thus provides an explanation of quantum mechanics. Moreover, the Bohmian trajectories are defined in a non-conspiratorial way by a few simple laws.

Detlef Duerr; Sheldon Goldstein; Roderich Tumulka; Nino Zanghi

2009-03-15T23:59:59.000Z

435

Mechanical down jar mechanism  

SciTech Connect

This paper describes a mechanical down jar mechanism for freeing stuck objects within a well bore and for conducting other down hole activities. It comprises: an elongate tubular housing having anvil means; mandrel means adapted for connection to an object to be moved downwardly within the well bore and being disposed in telescoping relation with the anvil means and the elongate tubular housing, the mandrel means adapted to be struck by the anvil means to impart a downwardly directed jarring force to the object; the elongate tubular housing having internal firing and recocking detent groove means located in axially spaced relation and forming a firing lug support land therebetween; a radially expandable and retractable firing lug assembly being disposed within the elongate tubular housing and in absence of force being applied axially thereto being radially restrained by the firing lug support land; load spring means being disposed within the elongate tubular housing and being in downward force transmitting relation with the firing lug assembly; recocking spring means being disposed within the elongate tubular housing and having upward axial force transmitting relation with the firing lug assembly.

Taylor, W.T.

1991-12-03T23:59:59.000Z

436

Oxygen diffusion in UO2+x and (U,Pu)O2+-x  

SciTech Connect

In the first part of this report we revisit an earlier study of oxygen diffusion in UO{sub 2+x}, in which we used density functional theory (DFT) calculations to parameterize a kinetic Monte Carlo (kMC) model. The results from these earlier kMC simulations are reproduced in Fig. 1 and they indicate fairly good agreement with available experiments. This work was later expanded to include a larger temperature range. However, since the publication of this study there have been a number of advancements in DFT methodology for UO{sub 2} and UO{sub 2+x} providing increased accuracy. We have also gained better understanding of the oxygen clustering phenomena occurring in UO{sub 2+x}. For these two reasons, the DFT calculations of the migration barriers of single oxygen interstitials and di-interstitial clusters have been repeated using the LDA+U and GGA+U methodologies. The earlier study used regular GGA and, even though this method captures similar trends as the more advanced LDA+U and GGA+U techniques, it does not fulfill the quantitative requirements set by some applications. Additionally, we have identified a mechanism for the most stable quad-interstitial clusters to migrate and here we calculate the corresponding barriers within both the LDA+U and GGA+U methodologies. The new LDA+U and GGA+U data sets are analyzed in terms of available experiments. In the second part of this report we present initial results for the impact of Pu on oxygen diffusion in UO{sub 2}. The first step in understanding this process is to calculate the binding energies of oxygen vacancies and interstitials to a Pu ion in the UO{sub 2} matrix. Possible diffusion mechanisms are discussed for (U,Pu)O{sub 2-x}, (U,Pu)O{sub 2} and (U,Pu)O{sub 2+x}.

Andersson, Anders D. [Los Alamos National Laboratory; Liu, Xiang-Yang [Los Alamos National Laboratory

2012-05-03T23:59:59.000Z

437

Mechanisms Determining the Atlantic Thermohaline Circulation Response to Greenhouse Gas Forcing in a Non-Flux-Adjusted Coupled Climate Model  

Science Conference Proceedings (OSTI)

Models of the North Atlantic thermohaline circulation (THC) show a range of responses to the high-latitude warming and freshening characteristic of global warming scenarios. Most simulate a weakening of the THC, with some suggesting possible ...

R. B. Thorpe; J. M. Gregory; T. C. Johns; R. A. Wood; J. F. B. Mitchell

2001-07-01T23:59:59.000Z

438

A Model Study of Oceanic Mechanisms Affecting Equatorial Pacific Sea Surface Temperature during the 1997–98 El Niño  

Science Conference Proceedings (OSTI)

In this study, the processes affecting sea surface temperature variability over the 1992–98 period, encompassing the very strong 1997–98 El Niño event, are analyzed. A tropical Pacific Ocean general circulation model, forced by a combination of ...

Jérôme Vialard; Christophe Menkes; Jean-Philippe Boulanger; Pascale Delecluse; Eric Guilyardi; Michael J. McPhaden; Gurvan Madec

2001-07-01T23:59:59.000Z

439

Preferential mode of gas invasion in sediments : grain-scale model of coupled multiphase fluid flow and sediment mechanics  

E-Print Network (OSTI)

We present a discrete element model for simulating, at the grain scale, gas migration in brine-saturated deformable media. We rigorously account for the presence of two fluids in the pore space by incorporating forces on ...

Jain, Antone Kumar

2009-01-01T23:59:59.000Z

440

Fractional reaction-diffusion equations  

E-Print Network (OSTI)

In a series of papers, Saxena, Mathai, and Haubold (2002, 2004a, 2004b) derived solutions of a number of fractional kinetic equations in terms of generalized Mittag-Leffler functions which provide the extension of the work of Haubold and Mathai (1995, 2000). The subject of the present paper is to investigate the solution of a fractional reaction-diffusion equation. The results derived are of general nature and include the results reported earlier by many authors, notably by Jespersen, Metzler, and Fogedby (1999) for anomalous diffusion and del-Castillo-Negrete, Carreras, and Lynch (2003) for reaction-diffusion systems with L\\'evy flights. The solution has been developed in terms of the H-function in a compact form with the help of Laplace and Fourier transforms. Most of the results obtained are in a form suitable for numerical computation.

R. K. Saxena; A. M. Mathai; H. J. Haubold

2006-04-21T23:59:59.000Z

Note: This page contains sample records for the topic "diffusion mechanisms 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.


441

Anomalous diffusion and scaling in coupled stochastic processes  

SciTech Connect

Inspired by problems in biochemical kinetics, we study statistical properties of an overdamped Langevin processes with the friction coefficient depending on the state of a similar, unobserved, process. Integrating out the latter, we derive the Pocker-Planck the friction coefficient of the first depends on the state of the second. Integrating out the latter, we derive the Focker-Planck equation for the probability distribution of the former. This has the fonn of diffusion equation with time-dependent diffusion coefficient, resulting in an anomalous diffusion. The diffusion exponent can not be predicted using a simple scaling argument, and anomalous scaling appears as well. The diffusion exponent of the Weiss-Havlin comb model is derived as a special case, and the same exponent holds even for weakly coupled processes. We compare our theoretical predictions with numerical simulations and find an excellent agreement. The findings caution against treating biochemical systems with unobserved dynamical degrees of freedom by means of standandard, diffusive Langevin descritpion.

Bel, Golan [Los Alamos National Laboratory; Nemenman, Ilya [Los Alamos National Laboratory

2009-01-01T23:59:59.000Z

442

Detailed stress tensor measurements in a centrifugal compressor vaneless diffuser  

Science Conference Proceedings (OSTI)

Detailed flow measurements have been made in the vaneless diffuser of a large low-speed centrifugal compressor using hot-wire anemometry. The three time mean velocity components and full stress tensor distributions have been determined on eight measurement plans within the diffuser. High levels of Reynolds stress result in the rapid mixing out of the blade wake. Although high levels of turbulent kinetic energy are found in the passage wake, they are not associated with strong Reynolds stresses and hence the passage wake mixes out only slowly. Low-frequency meandering of the wake position is therefore likely to be responsible for the high kinetic energy levels. The anisotropic nature of the turbulence suggests that Reynolds stress turbulence models are required for CFD modeling of diffuser flows.

Pinarbasi, A.; Johnson, M.W. [Univ. of Liverpool (United Kingdom). Dept. of Mechanical Engineering

1996-04-01T23:59:59.000Z

443

Ice Formation in Gas-Diffusion Layers  

SciTech Connect

Under sub-freezing conditions, ice forms in the gas-diffusion layer (GDL) of a proton exchange membrane fuel cell (PEMFC) drastically reducing cell performance. Although a number of strategies exist to prevent ice formation, there is little fundamental understanding of the mechanisms of freezing within PEMFC components. Differential scanning calorimetry (DSC) is used to elucidate the effects of hydrophobicity (Teflon® loading) and water saturation on the rate of ice formation within three commercial GDLs. We find that as the Teflon® loading increases, the crystallization temperature decreases due to a change in internal ice/substrate contact angle, as well as the attainable level of water saturation. Classical nucleation theory predicts the correct trend in freezing temperature with Teflon® loading.

Dursch, Thomas; Radke, Clayton J.; Weber, Adam Z.

2010-07-10T23:59:59.000Z

444

Diffusive transport without detailed balance in motile bacteria: Does microbiology need statistical physics?  

E-Print Network (OSTI)

Microbiology is the science of microbes, particularly bacteria. Many bacteria are motile: they are capable of self-propulsion. Among these, a significant class execute so-called run-and-tumble motion: they follow a fairly straight path for a certain distance, then abruptly change direction before repeating the process. This dynamics has something in common with Brownian motion (it is diffusive at large scales), and also something in contrast. Specifically, motility parameters such as the run speed and tumble rate depend on the local environment and hence can vary in space. When they do so, even if a steady state is reached, this is not generally invariant under time-reversal: the principle of detailed balance, which restores the microscopic time-reversal symmetry of systems in thermal equilibrium, is mesoscopically absent in motile bacteria. This lack of detailed balance (allowed by the flux of chemical energy that drives motility) creates pitfalls for the unwary modeller. Here I review some statistical mechanical models for bacterial motility, presenting them as a paradigm for exploring diffusion without detailed balance. I also discuss the extent to which statistical physics is useful in understanding real or potential microbiological experiments.

M. E. Cates

2012-08-20T23:59:59.000Z

445

The Mechanics of Implementing a Consistent Instructional Feedback Model in the Development of a Computer-Based Engineering Course  

Science Conference Proceedings (OSTI)

A computer-based education course to teach an undergraduate engineering course in statics has been developed at Texas A&M University. In the initial design phase, the authors used a very simply constructed feedback model. However, once development was ...

Clayton C. Nelson; Billie J. Hughes; Ralph E. Virgo

1987-05-01T23:59:59.000Z

446

Tracer Diffusion Db- NIST09  

Science Conference Proceedings (OSTI)

... DCu Cu-Zn, 780oC Atom Fraction Zinc (X Zn ) 0.0 0.1 0.2 0.3 Tra cer Diffusion Co ... Au-Ni, 900 o C Atom fraction nickel (X Ni ) 0.0 0.2 0.4 0.6 0.8 1.0 ...

2012-10-04T23:59:59.000Z

447

Test Program for High Efficiency Gas Turbine Exhaust Diffuser  

DOE Green Energy (OSTI)

This research relates to improving the efficiency of flow in a turbine exhaust, and thus, that of the turbine and power plant. The Phase I SBIR project demonstrated the technical viability of “strutlets” to control stalls on a model diffuser strut. Strutlets are a novel flow-improving vane concept intended to improve the efficiency of flow in turbine exhausts. Strutlets can help reduce turbine back pressure, and incrementally improve turbine efficiency, increase power, and reduce greenhouse gas emmission. The long-term goal is a 0.5 percent improvement of each item, averaged over the US gas turbine fleet. The strutlets were tested in a physical scale model of a gas turbine exhaust diffuser. The test flow passage is a straight, annular diffuser with three sets of struts. At the end of Phase 1, the ability of strutlets to keep flow attached to struts was demonstrated, but the strutlet drag was too high for a net efficiency advantage. An independently sponsored followup project did develop a highly-modified low-drag strutlet. In combination with other flow improving vanes, complicance to the stated goals was demonstrated for for simple cycle power plants, and to most of the goals for combined cycle power plants using this particular exhaust geometry. Importantly, low frequency diffuser noise was reduced by 5 dB or more, compared to the baseline. Appolicability to other diffuser geometries is yet to be demonstrated.

Norris, Thomas R.

2009-12-31T23:59:59.000Z

448

From transport to diffusion through a space asymptotic approach  

Science Conference Proceedings (OSTI)

The spatially asymptotic theory is a useful approach to the neutron transport model for nuclear reactor physics applications. For steady-state problems the transport equation is taken in an infinite medium and it is treated by the Fourier transform. ... Keywords: Neutron diffusion, Neutron transport, Space asymptotic theory

S. Dulla; S. Canepa; P. Ravetto

2010-07-01T23:59:59.000Z

449

Addressing the Recalcitrance of Cellulose Degradation through Cellulase Discovery, Nano-scale Elucidation of Molecular Mechanisms, and Kinetic Modeling  

DOE Green Energy (OSTI)

This research project was designed to play a vital role in the development of low cost sugars from cellulosic biomass and contributing to the national effort to displace fossil fuel usage in the USA transportation sector. The goal was to expand the portfolio of cell wall degrading enzymes through innovative research at the nano-scale level, prospecting for novel cellulases and building a kinetic framework for the development of more effective enzymatic conversion processes. More precisely, the goal was to elucidate the molecular mechanisms for some cellulases that are very familiar to members of our research team and to investigate what we hope are novel cellulases or new enzyme combinations from the world of plant pathogenic fungi and bacteria. Hydrolytic activities of various cellulases and cellulase cocktails were monitored at the nanoscale of cellulose fibrils and the microscale of pretreated cellulose particles, and we integrated this insight into a heterogeneous reaction framework. The over-riding approach for this research program was the application of innovative and cutting edge optical and high-throughput screening and analysis techniques for observing how cellulases hydrolyze real substrates.

Walker, Larry P., Bergstrom, Gary; Corgie, Stephane; Craighead, Harold; Gibson, Donna; Wilson, David

2011-06-13T23:59:59.000Z

450

An estimation of the pattern of diffusion of mobile phones: The case of Colombia  

Science Conference Proceedings (OSTI)

This paper examines the diffusion pattern of mobile telephony in Colombia. The empirical modelling approach adopted in the paper starts off by choosing between the two functional forms that are most frequently used in the literature, namely the Gompertz ... Keywords: C53, Colombia, Gompertz curve, L96, Logistic curve, Mobile telecommunications, O30, Technology diffusion

Luis Fernando Gamboa; Jesús Otero

2009-11-01T23:59:59.000Z

451

Numerical fluid solutions for nonlocal electron transport in hot plasmas: Equivalent diffusion versus nonlocal source  

Science Conference Proceedings (OSTI)

Flux limitation and preheat are important processes in electron transport occurring in laser produced plasmas. The proper calculation of both of these has been a subject receiving much attention over the entire lifetime of the laser fusion project. Where ... Keywords: Equivalent diffusion, Implicit-explicit diffusion algorithm, Krook model, Nonlocal electron transport, Numerical stability

Denis Colombant; Wallace Manheimer

2010-06-01T23:59:59.000Z

452

Further investigations of diffuser augmented wind turbines. Part 2. Technical report. Final report  

DOE Green Energy (OSTI)

A multiphased investigation is described which involves three test facilities of several compact diffuser approaches. Screens, to simulate a wind turbine, and a three-bladed, fixed-pitch turbine have been with the diffuser models. A candidate baseline design is described and some of the key issues are discussed that can lead to future full scale implementation.

Foreman, K.M.; Gilbert, B.L.

1979-07-01T23:59:59.000Z

453

Ocean Turbulence. Part II: Vertical Diffusivities of Momentum, Heat, Salt, Mass, and Passive Scalars  

Science Conference Proceedings (OSTI)

A Reynolds stress–based model is used to derive algebraic expressions for the vertical diffusivities K?(? = m, h, s) for momentum, heat, and salt. The diffusivities are expressed as K?(R?, N, RiT, ?)in terms of the density ratio R? = ?s?S/?z(...

V. M. Canuto; A. Howard; Y. Cheng; M. S. Dubovikov

2002-01-01T23:59:59.000Z

454

Bohmian mechanics contradicts quantum mechanics  

E-Print Network (OSTI)

Bohmian mechanics contradicts quantum mechanics Arnold Neumaier Institut fur Mathematik, Universit://solon.cma.univie.ac.at/#24;neum/ Abstract. It is shown that, for a harmonic oscillator in the ground state, Bohmian mechanics and quantum mechanics predict values of opposite sign for certain time correlations. The discrepancy can

Neumaier, Arnold

455

Ice Formation in Gas-Diffusion Layers  

E-Print Network (OSTI)

of California. Ice Formation in Gas-Diffusion Layers Thomasconditions, ice forms in the gas-diffusion layer (GDL) of areaction of reactant gases (1). A number of strategies exist

Dursch, Thomas

2013-01-01T23:59:59.000Z

456

Synergistic diffuser/heat-exchanger design  

E-Print Network (OSTI)

The theoretical and numerical evaluation of synergistic diffusing heat-exchanger design is presented. Motivation for this development is based on current diffuser and heat-exchange technologies in cogeneration plants, which ...

Lazzara, David S. (David Sergio), 1980-

2004-01-01T23:59:59.000Z

457

Diffusion Tubes for Ambient NO2 Monitoring  

E-Print Network (OSTI)

in the field of diffusive sampling, and other stakeholders. The following (in alphabetical order) actively or vapour phase pollutant directly from the surrounding air by means of diffusion, without actively drawing

Short, Daniel

458

Hierarchical 3D diffusion wavelet shape priors  

E-Print Network (OSTI)

In this paper, we propose a novel representation of prior knowledge for image segmentation, using diffusion wavelets that can reflect arbitrary continuous interdependencies in shape data. The application of diffusion ...

Langs, Georg

459

Classical diffusive dynamics for the quasiperiodic kicked rotor  

E-Print Network (OSTI)

We study the classical dynamics of a quasiperiodic kicked rotor, whose quantum counterpart is known to be an equivalent of the 3D Anderson model. Using this correspondence allowed for a recent experimental observation of the Anderson transition with atomic matter waves. In such a context, it is particularly important to assert the chaotic character of the classical dynamics of this system. We show here that it is a 3D anisotropic diffusion. Our simple analytical predictions for the associated diffusion tensor are found in good agreement with the results of numerical simulations.

Gabriel Lemarié; Dominique Delande; Jean Claude Garreau; Pascal Szriftgiser

2010-03-23T23:59:59.000Z

460

Least-squares variational principles and the finite element method: theory, formulations, and models for solid and fluid mechanics  

E-Print Network (OSTI)

We consider the application of least-squares variational principles and the finite element method to the numerical solution of boundary value problems arising in the fields of solidand fluidmechanics.For manyof these problems least-squares principles offer many theoretical and computational advantages in the implementation of the corresponding finite element model that are not present in the traditional weak form Galerkin finite element model.Most notably, the use of least-squares principles leads to a variational unconstrained minimization problem where stability conditions such as inf-sup conditions (typically arising in mixed methods using weak form Galerkin finite element formulations) never arise. In addition, the least-squares based finite elementmodelalways yields a discrete system ofequations witha symmetric positive definite coeffcientmatrix.These attributes, amongst manyothers highlightedand detailed in this work, allow the developmentofrobust andeffcient finite elementmodels for problems of practical importance. The research documented herein encompasses least-squares based formulations for incompressible and compressible viscous fluid flow, the bending of thin and thick plates, and for the analysis of shear-deformable shell structures.

Pontaza, Juan Pablo

2003-12-01T23:59:59.000Z

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