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1

Damage and fatigue Continuum damage mechanics modeling  

E-Print Network [OSTI]

-CL�S : endommagement, fatigue, métaux, béton, élastomères, roche REGC ­ 10/2006. Geomechanics in energy production, pages 849 to 877 #12;850 REGC ­ 10/2006. Geomechanics in energy production 1. Introduction Continuum

2

Ice sheets and their dynamics Continuum thermo-mechanical model of a glacier  

E-Print Network [OSTI]

Ice sheets and their dynamics Continuum thermo-mechanical model of a glacier Shallow Ice Approximation (SIA) SIA-I Iterative Improvement Technique Benchmarks Numerical modeling of ice-sheet dynamics and Cartography, Zdiby 1.6.2010 Ondej Soucek Ph.D. defense #12;Ice sheets and their dynamics Continuum thermo

Cerveny, Vlastislav

3

A Continuum Coupled Moisture-mechanical Constitutive Model for Asphalt Concrete  

E-Print Network [OSTI]

constitutive relationships are implemented in the Pavement Analysis using Nonlinear Damage Approach (PANDA) finite element (FE) package to model the moisture damage effect on the complex environmental-mechanical response of asphalt concrete. The developed...

Shakiba, Maryam

2013-12-09T23:59:59.000Z

4

Applications of Continuum Shell Model  

E-Print Network [OSTI]

The nuclear many-body problem at the limits of stability is considered in the framework of the Continuum Shell Model that allows a unified description of intrinsic structure and reactions. Technical details behind the method are highlighted and practical applications combining the reaction and structure pictures are presented.

Alexander Volya

2006-05-16T23:59:59.000Z

5

Variational Theory of Mixtures in Continuum Mechanics  

E-Print Network [OSTI]

energy is assumed to be a function of densities, entropies and suc- cessive spatial gradients of each energy function of densities, entropies and spatial gradients, an equation describing the barycentric & Drumheller, 1983] cover most of the works in continuum theory. The book by Rowlinson & Swinton [1982] gives

Boyer, Edmond

6

Challenges in Continuum Modelling of Intergranular Fracture  

E-Print Network [OSTI]

Challenges in Continuum Modelling of Intergranular Fracture V. R. Coffman*, J. P. Sethna , A. R-2501, USA Cornell Fracture Group, Rhodes Hall, Cornell University, Ithaca, NY 14853-2501, USA § Department fracture in polycrystals is often simulated by finite elements coupled to a cohesive zone model

Sethna, James P.

7

Relativistic R matrix and continuum shell model  

E-Print Network [OSTI]

Background: The $R$ matrix formalism of Lane and Thomas has proven to be a convenient reaction theory for solving many-coupled channel systems. The theory provides solutions to bound states, scattering states, and resonances for microscopic models in one formalism. Purpose: The first purpose is to extend this formalism to the relativistic case so that the many-coupled channels problem may be solved for systems in which binary breakup channels satisfy a relative Dirac equation. The second purpose is to employ this formalism in a relativistic continuum shell model. Methods: Expressions for the collision matrix and the scattering amplitude, from which observables may be calculated, are derived. The formalism is applied to the 1p-1h relativistic continuum shell model with an interaction extracted from relativistic mean-field theory. Results: The simplest of the $\\sigma +\\omega +\\rho$ exchange interactions produces a good description of the single-particle energies in $^{16}$O and $^{90}$Zr and a reasonable description of proton scattering from $^{15}$N. Conclusions: The development of a calculable, relativistic $R$ matrix and its implementation in a $1p-1h$ relativistic continuum shell model provide a simple relatively self-consist, physically justifiable model for use in knockout reactions.

J. Grineviciute; Dean Halderson

2014-04-16T23:59:59.000Z

8

A continuum damage modelling of quasi-static fatigue strength of plain concrete  

E-Print Network [OSTI]

A continuum damage modelling of quasi-static fatigue strength of plain concrete S. H. Maia,b , F of concrete. The approach is based on the framework of continuum damage mechanics where the fatigue model fatigue tests have been performed on a concrete the formulation of which is close to the one used

Paris-Sud XI, Université de

9

Nano-Continuum Modeling of a Nuclear Glass Specimen Altered for 25 Years  

SciTech Connect (OSTI)

The purpose of this contribution is to report on preliminary nano-continuum scale modeling of nuclear waste glass corrosion. The focus of the modeling is an experiment involving a French glass SON68 specimen leached for 25 years in a granitic environment. In this report, we focus on capturing the nano-scale concentration profiles. We use a high resolution continuum model with a constant grid spacing of 1 nanometer to investigate the glass corrosion mechanisms.

Steefel, Carl

2014-01-06T23:59:59.000Z

10

A Continuum Model for Carbon Nanotube-Infused Polyimides  

E-Print Network [OSTI]

A Continuum Model for Carbon Nanotube-Infused Polyimides Heather Wilson1 , Sumanth Banda2 , Ralph C, the materials need to withstand this process. The nanotube-infused polyimides are flexible enough to withstand

11

To be submitted to Continuum Mechanics and Thermodynamics From the onset of damage to rupture: construction of responses with damage  

E-Print Network [OSTI]

To be submitted to Continuum Mechanics and Thermodynamics From the onset of damage to rupture: construction of responses with damage localization for a general class of gradient damage models Kim Pham solutions for the traction problem of an elastic damaging bar. This bar has a softening behavior which obeys

Boyer, Edmond

12

Applications of a new theory extending continuum mechanics to the nanoscale  

E-Print Network [OSTI]

In this dissertation, we present the Slattery-Oh-Fu theory extending continuum mechanics to the nanoscale and its applications. We begin with an analysis of supercritical adsorption of argon, krypton, and methane on Graphon before we fully develop...

Fu, Kaibin

2005-11-01T23:59:59.000Z

13

Statistical properties of the continuum Salerno model  

E-Print Network [OSTI]

The statistical properties of the Salerno model is investigated. In particular, a comparison between the coherent and partially coherent wave modes is made for the case of a random phased wave packet. It is found that the random phased induced spectral broadening gives rise to damping of instabilities, but also a broadening of the instability region in quasi-particle momentum space. The results can be of significance for condensation of magnetic moment bosons in deep optical lattices.

M. Marklund; P. K. Shukla; R. Bingham; J. T. Mendonca

2006-08-09T23:59:59.000Z

14

Equivalent Continuum Modeling for Shock Wave Propagation in Jointed Media  

SciTech Connect (OSTI)

This study presents discrete and continuum simulations of shock wave propagating through jointed media. The simulations were performed using the Lagrangian hydrocode GEODYN-L with joints treated explicitly using an advanced contact algorithm. They studied both isotropic and anisotropic joint representations. For an isotropically jointed geologic medium, the results show that the properties of the joints can be combined with the properties of the intact rock to develop an equivalent continuum model suitable for analyzing wave propagation through the jointed medium. For an anisotropically jointed geologic medium, they found it difficult to develop an equivalent continuum (EC) model that matches the response derived from mesoscopic simulation. They also performed simulations of wave propagation through jointed media. Two appraoches are suggested for modeling the rock mass. In one approach, jointed are modeled explicitly in a Lagrangian framework with appropriate contact algorithms used to track motion along the interfaces. In the other approach, the effect of joints is taken into account using a constitutive model derived from mesoscopic simulations.

Vorobiev, O; Antoun, T

2009-12-11T23:59:59.000Z

15

Continuum modeling of a neuronal cell under blast loading Antoine Jrusalem a,  

E-Print Network [OSTI]

2012 Keywords: Continuum model Neuron Blast Cell damage Traumatic brain injury a b s t r a cContinuum modeling of a neuronal cell under blast loading Antoine Jérusalem a, , Ming Dao b by proposing a continuum model of a neuronal cell submitted to blast loading. In this approach, the cytoplasm

Suresh, Subra

16

Relativistic Point Coupling Model for Vibrational Excitations in the Continuum  

SciTech Connect (OSTI)

An implementation of the relativistic random phase approximation with the proper treatment of the continuum has been developed for the relativistic point coupling model and applied to investigate collective excitations in spherical nuclei. The results are compared with the spectral implementation of the same model. In heavy nuclei, where the escape width is negligible, we find an excellent agreement between both methods in the region of giant resonance and some discrepancies in the region of low-lying pygmy resonance. The differences are more pronounced in light nuclei due to the larger values of the escape widths.

Ring, P.; Daoutidis, J. [Physics Department Technical University Munich, 85748 Garching (Germany); Litvinova, E. [Gesellschaft fuer Schwerionenforschung mbH, 64291 Darmstadt (Germany); Niksic, T.; Paar, N.; Vretenar, D. [Physics Department, Faculty of Science, University of Zagreb (Croatia)

2009-08-26T23:59:59.000Z

17

Dense Heterogeneous Continuum Model of Two-Phase Explosion Fields  

SciTech Connect (OSTI)

A heterogeneous continuum model is proposed to describe the dispersion of a dense Aluminum particle cloud in an explosion. Let {alpha}{sub 1} denote the volume fraction occupied by the gas and {alpha}{sub 2} the fraction occupied by the solid, satisfying the volume conservation relation: {alpha}{sub 1} + {alpha}{sub 2} = 1. When the particle phase occupies a non-negligible volume fraction (i.e., {alpha}{sub 2} > 0), additional terms, proportional to {alpha}{sub 2}, appear in the conservation laws for two-phase flows. These include: (i) a particle pressure (due to particle collisions), (ii) a corresponding sound speed (which produces real eigenvalues for the particle phase system), (iii) an Archimedes force induced on the particle phase (by the gas pressure gradient), and (iv) multi-particle drag effects (which enhance the momentum coupling between phases). These effects modify the accelerations and energy distributions in the phases; we call this the Dense Heterogeneous Continuum Model. A characteristics analysis of the Model equations indicates that the system is hyperbolic with real eigenvalues for the gas phase: {l_brace}v{sub 1}, v{sub 1} {+-} {alpha}{sub 1}{r_brace} and for the 'particle gas' phase: {l_brace}v{sub 2}, v{sub 2} {+-}{alpha}{sub 2}{r_brace} and the particles: {l_brace}v{sub 2}{r_brace}, where v{sub i} and {alpha}{sub i} denote the velocity vector and sound speed of phase i. These can be used to construct a high-order Godunov scheme to integrate the conservation laws of a dense heterogeneous continuum.

Kuhl, A L; Bell, J B

2010-04-07T23:59:59.000Z

18

Identification of material parameters for continuum modeling of phase transformations in multicomponent systems  

E-Print Network [OSTI]

Identification of material parameters for continuum modeling of phase transformations called order pa- rameters, which take on specified values in the bulk phases. If the transformation

Umantsev, Alexander

19

Ad hoc continuum-atomistic thermostat for modeling heat flow in molecular dynamics simulations  

E-Print Network [OSTI]

Ad hoc continuum-atomistic thermostat for modeling heat flow in molecular dynamics simulations J 2004) An ad hoc thermostating procedure that couples a molecular dynamics (MD) simulation

Brenner, Donald W.

20

A non-continuum approach to obtain a macroscopic model for the flow of traffic  

E-Print Network [OSTI]

by continuum models for the flow of traffic. The number of vehicles in a typical section of a freeway does not justify traffic being treated as a continuum. It is also important to recognize that the basic premises of kinetic theory are not appropriate...

Tyagi, Vipin

2007-09-17T23:59:59.000Z

Note: This page contains sample records for the topic "mechanics continuum modeling" 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

Universal iso-density polarizable continuum model for molecular solvents  

E-Print Network [OSTI]

Implicit electron-density solvation models based on joint density-functional theory offer a computationally efficient solution to the problem of calculating thermodynamic quantities of solvated systems from first-principles quantum mechanics. However, despite much recent interest in such models, to date the applicability of such models to non-aqueous solvents has been limited because the determination of the model parameters requires fitting to a large database of experimental solvation energies for each new solvent considered. This work presents an alternate approach which allows development of new solvation models for a large class of protic and aprotic solvents from only simple, single-molecule ab initio calculations and readily available bulk thermodynamic data. We find that this model is accurate to nearly 1.7 kcal/mol even for solvents outside our development set.

Gunceler, Deniz

2014-01-01T23:59:59.000Z

22

A LARGE SCALE CONTINUUM-DISCRETE NUMERICAL MODELLING: APPLICATION TO OVERBURDEN DAMAGE OF A SALT CAVERN  

E-Print Network [OSTI]

CAVERN SOULEY Mountaka1 , MERCERAT Diego2 , DRIAD-LEBEAU Lynda1 , BERNARD Pascal2 1 INERIS, Ecole des collapse). KEYWORDS: cavern, numerical modelling, continuum-discrete, overburden, damage. RÃ?SUMÃ?: Dans l

Boyer, Edmond

23

Progress toward bridging from atomistic to continuum modeling to predict nuclear waste glass dissolution.  

SciTech Connect (OSTI)

This report summarizes research performed for the Nuclear Energy Advanced Modeling and Simulation (NEAMS) Subcontinuum and Upscaling Task. The work conducted focused on developing a roadmap to include molecular scale, mechanistic information in continuum-scale models of nuclear waste glass dissolution. This information is derived from molecular-scale modeling efforts that are validated through comparison with experimental data. In addition to developing a master plan to incorporate a subcontinuum mechanistic understanding of glass dissolution into continuum models, methods were developed to generate constitutive dissolution rate expressions from quantum calculations, force field models were selected to generate multicomponent glass structures and gel layers, classical molecular modeling was used to study diffusion through nanopores analogous to those in the interfacial gel layer, and a micro-continuum model (K{mu}C) was developed to study coupled diffusion and reaction at the glass-gel-solution interface.

Zapol, Peter (Argonne National Laboratory, Argonne, IL); Bourg, Ian (Lawrence Berkeley National Laboratories, Berkeley, CA); Criscenti, Louise Jacqueline; Steefel, Carl I. (Lawrence Berkeley National Laboratories, Berkeley, CA); Schultz, Peter Andrew

2011-10-01T23:59:59.000Z

24

Kinetics and mechanisms of metal sorption at the soil mineral/water interface: The continuum from adsorption to  

E-Print Network [OSTI]

GEOC 36 Kinetics and mechanisms of metal sorption at the soil mineral/water interface: The continuum from adsorption to precipitation Donald L. Sparks, Plant and Soil Sciences Department, Plant and Soil Sciences Department, University of Delaware, 531 S. College Avenue, Townsend Hall, Room 153

Sparks, Donald L.

25

THMC Modeling of EGS Reservoirs ? Continuum through Discontinuum...  

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

Accomplishments, Results and Progress Induced Seismicity - Model and Validation Fracture Geometry Stimulation Geometry Observed b-value 0.7-0.8 Event Distribution - by...

26

Continuum Models of Carbon Nanotube-Based Composites Using the Boundary Element Method  

E-Print Network [OSTI]

Continuum Models of Carbon Nanotube-Based Composites Using the Boundary Element Method Y.J. Liu)-based composites. Carbon nanotubes, formed conceptually by rolling thin graphite sheets, have been found to be extremely stiff, strong and resilient, and therefore may be ideal for reinforcing composite materials

Liu, Yijun

27

Sensitivity of the Properties of Ruthenium “Blue Dimer” to Method, Basis Set, and Continuum Model  

SciTech Connect (OSTI)

The ruthenium “blue dimer” [(bpy)2RuIIIOH2]2O4+ is best known as the first well-defined molecular catalyst for water oxidation. It has been subject to numerous computational studies primarily employing density functional theory. However, those studies have been limited in the functionals, basis sets, and continuum models employed. The controversy in the calculated electronic structure and the reaction energetics of this catalyst highlights the necessity of benchmark calculations that explore the role of density functionals, basis sets, and continuum models upon the essential features of blue-dimer reactivity. In this paper, we report Kohn-Sham complete basis set (KS-CBS) limit extrapolations of the electronic structure of “blue dimer” using GGA (BPW91 and BP86), hybrid-GGA (B3LYP), and meta-GGA (M06-L) density functionals. The dependence of solvation free energy corrections on the different cavity types (UFF, UA0, UAHF, UAKS, Bondi, and Pauling) within polarizable and conductor-like polarizable continuum model has also been investigated. The most common basis sets of double-zeta quality are shown to yield results close to the KS-CBS limit; however, large variations are observed in the reaction energetics as a function of density functional and continuum cavity model employed.

Ozkanlar, Abdullah; Clark, Aurora E.

2012-05-23T23:59:59.000Z

28

Continuum modelling of piezoelectromechanical truss beams: an application to vibration damping  

E-Print Network [OSTI]

are connected to the electrical line so that their equivalent circuits are to be regarded as part of the modularContinuum modelling of piezoelectromechanical truss beams: an application to vibration damping F modular truss beam, electric transmission line, piezoelectromechanical coupling, vibration control 1

Paris-Sud XI, Université de

29

A continuum constitutive model for amorphous metallic materials  

E-Print Network [OSTI]

A finite-deformation, Coulomb-Mohr type constitutive theory for the elastic-viscoplastic response of pressure-sensitive and plastically-dilatant isotropic materials has been developed. The constitutive model has been ...

Su, Cheng, Ph. D. Massachusetts Institute of Technology

2007-01-01T23:59:59.000Z

30

Continuum- based computational models of biological living cell  

E-Print Network [OSTI]

3.4 Vertical displacement distribution obtained from finite element analysis for SLS model with shear modulus of cortex 275 Pa, cytoplasm 200Pa. ............. 29 Figure 3.5 Force- deformation curves for the various cytoplasm shear modulus G=100.../ml. ..................................................................... 42 Figure 3.20 Indentation & force curves for various frequencies with the concentration factor c=2mg/ml. ..................................................................... 42 Figure 3.21 V=0.1?m/s, displacement (input) and reaction force...

Cheng, Feifei

2009-05-15T23:59:59.000Z

31

2.5 CONTINUUM MECHANICS (FLUIDS) Let us consider a fluid medium and use Cartesian tensors to derive the mathematical equations that  

E-Print Network [OSTI]

282 §2.5 CONTINUUM MECHANICS (FLUIDS) Let us consider a fluid medium and use Cartesian tensors to derive the mathematical equations that describe how a fluid behaves. A fluid continuum, like a solid, is the density of the fluid, ij is the stress tensor and bj is an external force per unit mass. In the cgs system

California at Santa Cruz, University of

32

2.5 CONTINUUM MECHANICS (FLUIDS) Let us consider a fluid medium and use Cartesian tensors to derive the mathematical equations that  

E-Print Network [OSTI]

282 §2.5 CONTINUUM MECHANICS (FLUIDS) Let us consider a fluid medium and use Cartesian tensors to derive the mathematical equations that describe how a fluid behaves. A fluid continuum, like a solid , i = 1, 2, 3 is a velocity field, # is the density of the fluid, # ij is the stress tensor and b j

California at Santa Cruz, University of

33

Derivation of a continuum model and the energy law for moving contact lines with insoluble surfactants  

SciTech Connect (OSTI)

A continuous model is derived for the dynamics of two immiscible fluids with moving contact lines and insoluble surfactants based on thermodynamic principles. The continuum model consists of the Navier-Stokes equations for the dynamics of the two fluids and a convection-diffusion equation for the evolution of the surfactant on the fluid interface. The interface condition, the boundary condition for the slip velocity, and the condition for the dynamic contact angle are derived from the consideration of energy dissipations. Different types of energy dissipations, including the viscous dissipation, the dissipations on the solid wall and at the contact line, as well as the dissipation due to the diffusion of surfactant, are identified from the analysis. A finite element method is developed for the continuum model. Numerical experiments are performed to demonstrate the influence of surfactant on the contact line dynamics. The different types of energy dissipations are compared numerically.

Zhang, Zhen, E-mail: matzz@nus.edu.sg; Xu, Shixin, E-mail: matxs@nus.edu.sg [Department of Mathematics, National University of Singapore, Singapore 119076 (Singapore); Ren, Weiqing, E-mail: matrw@nus.edu.sg [Department of Mathematics, National University of Singapore, Singapore 119076 (Singapore); Institute of High Performance Computing, Agency for Science, Technology and Research, Singapore 138632 (Singapore)

2014-06-15T23:59:59.000Z

34

Final Report for DOE Grant DE-FG02-03ER25579; Development of High-Order Accurate Interface Tracking Algorithms and Improved Constitutive Models for Problems in Continuum Mechanics with Applications to Jetting  

SciTech Connect (OSTI)

Much of the work conducted under the auspices of DE-FG02-03ER25579 was characterized by an exceptionally close collaboration with researchers at the Lawrence Berkeley National Laboratory (LBNL). For example, Andy Nonaka, one of Professor Miller's graduate students in the Department of Applied Science at U. C. Davis (UCD) wrote his PhD thesis in an area of interest to researchers in the Applied Numerical Algorithms Group (ANAG), which is a part of the National Energy Research Supercomputer Center (NERSC) at LBNL. Dr. Nonaka collaborated closely with these researchers and subsequently published the results of this collaboration jointly with them, one article in a peer reviewed journal article and one paper in the proceedings of a conference. Dr. Nonaka is now a research scientist in the Center for Computational Sciences and Engineering (CCSE), which is also part of the National Energy Research Supercomputer Center (NERSC) at LBNL. This collaboration with researchers at LBNL also included having one of Professor Puckett's graduate students in the Graduate Group in Applied Mathematics (GGAM) at UCD, Sarah Williams, spend the summer working with Dr. Ann Almgren, who is a staff scientist in CCSE. As a result of this visit Sarah decided work on a problem suggested by the head of CCSE, Dr. John Bell, for her PhD thesis. Having finished all of the coursework and examinations required for a PhD, Sarah stayed at LBNL to work on her thesis under the guidance of Dr. Bell. Sarah finished her PhD thesis in June of 2007. Writing a PhD thesis while working at one of the University of California (UC) managed DOE laboratories is long established tradition at UC and Professor Puckett has always encouraged his students to consider doing this. Another one of Professor Puckett's graduate students in the GGAM at UCD, Christopher Algieri, was partially supported with funds from DE-FG02-03ER25579 while he wrote his MS thesis in which he analyzed and extended work originally published by Dr. Phillip Colella, the head of ANAG, and some of his colleagues. Chris Algieri is now employed as a staff member in Dr. Bill Collins' Climate Science Department in the Earth Sciences Division at LBNL working with computational models of climate change. Finally, it should be noted that the work conducted by Professor Puckett and his students Sarah Williams and Chris Algieri and described in this final report for DOE grant # DE-FC02-03ER25579 is closely related to work performed by Professor Puckett and his students under the auspices of Professor Puckett's DOE SciDAC grant DE-FC02-01ER25473 An Algorithmic and Software Framework for Applied Partial Differential Equations: A DOE SciDAC Integrated Software Infrastructure Center (ISIC). Dr. Colella was the lead PI for this SciDAC grant, which was comprised of several research groups from DOE national laboratories and five university PI's from five different universities. In theory Professor Puckett tried to use funds from the SciDAC grant to support work directly involved in implementing algorithms developed by members of his research group at UCD as software that might be of use to Puckett's SciDAC CoPIs. (For example, see the work reported in Section 2.2.2 of this final report.) However, since there is considerable lead time spent developing such algorithms before they are ready to become `software' and research plans and goals change as the research progresses, Professor Puckett supported each member of his research group partially with funds from the SciDAC APDEC ISIC DE-FC02-01ER25473 and partially with funds from this DOE MICS grant DE-FC02-03ER25579. This has necessarily resulted in a significant overlap of project areas that were funded by both grants. In particular, both Sarah Williams and Chris Algieri were supported partially with funds from grant # DE-FG02-03ER25579, for which this is the final report, and in part with funds from Professor Puckett's DOE SciDAC grant # DE-FC02-01ER25473. For example, Sarah Williams received support from DE-FC02- 01ER25473 and DE-FC02-03ER25579, both while at UCD taking cla

Puckett, Elbridge Gerry [U.C. Davis, Department of Mathematics; Miller, Gregory Hale [.C. Davis, Department of Chemical Engineering

2012-10-14T23:59:59.000Z

35

New Dynamic Models for Planar Extensible Continuum Robot Manipulators Enver Tatlicioglu, Ian D. Walker, and Darren M. Dawson  

E-Print Network [OSTI]

or an octopus arm [15]. It is a three-section robot with nine degrees of freedom where each section hasNew Dynamic Models for Planar Extensible Continuum Robot Manipulators Enver Tatlicioglu, Ian D 3-section extensible continuum robot manipulator. The results show a much stronger match to physical

36

Continuum Level Formulation and Implementation of a Multi-scale Model for Vanadium  

SciTech Connect (OSTI)

A multi-scale approach is used to construct a continuum strength model for vanadium. The model is formulated assuming plastic deformation by dislocation motion and strain hardening due to dislocation interactions. Dislocation density is adopted as the state variable in the model. Information from molecular statics, molecular dynamics and dislocation dynamics simulations is combined to create kinetic relations for dislocation motion, strain hardening relations and evolution equations for the dislocation density. Implicit time integration of the constitutive equations is described in the context of implementation in a finite element code. Results are provided illustrating the strain, strain rate, temperature and pressure dependence of the constitutive model.

Lawrence Livermore National Laboratory

2009-08-17T23:59:59.000Z

37

Continuum-kinetic-microscopic model of lung clearance due to core-annular fluid entrainment  

SciTech Connect (OSTI)

The human lung is protected against aspirated infectious and toxic agents by a thin liquid layer lining the interior of the airways. This airway surface liquid is a bilayer composed of a viscoelastic mucus layer supported by a fluid film known as the periciliary liquid. The viscoelastic behavior of the mucus layer is principally due to long-chain polymers known as mucins. The airway surface liquid is cleared from the lung by ciliary transport, surface tension gradients, and airflow shear forces. This work presents a multiscale model of the effect of airflow shear forces, as exerted by tidal breathing and cough, upon clearance. The composition of the mucus layer is complex and variable in time. To avoid the restrictions imposed by adopting a viscoelastic flow model of limited validity, a multiscale computational model is introduced in which the continuum-level properties of the airway surface liquid are determined by microscopic simulation of long-chain polymers. A bridge between microscopic and continuum levels is constructed through a kinetic-level probability density function describing polymer chain configurations. The overall multiscale framework is especially suited to biological problems due to the flexibility afforded in specifying microscopic constituents, and examining the effects of various constituents upon overall mucus transport at the continuum scale.

Mitran, Sorin, E-mail: mitran@unc.edu

2013-07-01T23:59:59.000Z

38

Multiscale micromechanical modeling of the thermal/mechanical properties of polymer/clay nanocomposites  

E-Print Network [OSTI]

Polymer/clay nanocomposites have been observed to exhibit enhanced thermal/mechanical properties at low weight fractions (We) of clay. Continuum-based composite modeling reveals that the enhanced properties are strongly ...

Sheng, Nuo, 1977-

2006-01-01T23:59:59.000Z

39

Electric and magnetic response to the continuum for A=7 isobars in a dicluster model  

E-Print Network [OSTI]

Mirror isobars $^7$Li and $^7$Be are investigated in a dicluster model. The magnetic dipole moments and the magnetic dipole response to the continuum are calculated in this framework. The magnetic contribution is found to be small with respect to electric dipole and quadrupole excitations even at astrophysical energies, at a variance with the case of deuteron. Energy weighted molecular sum rules are evaluated and a formula for the molecular magnetic dipole sum rule is found which matches the numerical calculations. Cross-sections for photo-dissociation and radiative capture as well as the S-factor for reactions of astrophysical significance are calculated with good agreement with known experimental data.

A. Mason; R. Chatterjee; L. Fortunato; A. Vitturi

2008-11-11T23:59:59.000Z

40

Geometrical Field Representation of Solid, Fluid, and Gas as Continuum in Rational Mechanics  

E-Print Network [OSTI]

Based on the points-set transformation concept about the motion transformation in continuum, the macro classical strain is expressed by the additive addition of the intrinsic stretching of material element and its intrinsic local rotation. For zero classical strain (no macro deformation observed on its configuration surface, suitable container is required for liquid and gas to make up macro invariant configuration), the results show that: (1) For solid, the local rotation angular is zero. The material element has no intrinsic stretching. (2) For liquid, the local rotation will not change the basic gauge tensor. The material element has intrinsic plane stretching on the rotation plane. (3) For gas state, the intrinsic local rotation will amplify the basic gauge tensor. The material element has intrinsic stretching along the rotation direction. Hence, under the condition of no macro classical strain be observed, the material element has three different physical states: solid (no intrinsic stretching), fluid (plane intrinsic stretching), and gas (directional intrinsic stretching). Furthermore, for the three states, the free conditions are defined by zero intrinsic stretching. Referring to this free condition, the constitutive equations for the materials at multiple states are established.

Jianhua Xiao

2009-11-07T23:59:59.000Z

Note: This page contains sample records for the topic "mechanics continuum modeling" 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

Frame Indifferent Formulation of Maxwell's Elastic Fluid and the Rational Continuum Mechanics of the Electromagnetic Field  

E-Print Network [OSTI]

We show that the linearized equations of the incompressible elastic medium admit a `Maxwell form' in which the shear component of the stress vector plays the role of the electric field, and the vorticity plays the role of the magnetic field. Conversely, the set of dynamic Maxwell equations are strict mathematical corollaries from the governing equations of the incompressible elastic medium. This suggests that the nature of `electromagnetic field' may actually be related to an elastic continuous medium. The analogy is complete if the medium is assumed to behave as fluid in shear motions, while it may still behave as elastic solid under compressional motions. Then the governing equations of the elastic fluid are re-derived in the Eulerian frame by replacing the partial time derivatives by the properly invariant (frame indifferent) time rates. The `Maxwell from' of the frame indifferent formulation gives the frame indifferent system that is to replace the Maxwell system. This new system comprises terms already present in the classical Maxwell equations, alongside terms that are the progenitors of the Biot--Savart, Oersted--Ampere's, and Lorentz--force laws. Thus a frame indifferent (truly covariant) formulation of electromagnetism is achieved from a single postulate that the electromagnetic field is a kind of elastic (partly liquid partly solid) continuum.

Christo I. Christov

2011-03-06T23:59:59.000Z

42

Extension of a Current Continuum-Level Material Model for Soil into the Low-Density Discrete-Particle Regime  

E-Print Network [OSTI]

energies of the soil as well as into surface energy of the fractured soil particles. In this caseExtension of a Current Continuum-Level Material Model for Soil into the Low-Density Discrete a soil-material model which can be used over a wide range of soil densities. To construct such a model

Grujicic, Mica

43

Are mixed explicit/implicit solvation models reliable for studying phosphate hydrolysis? A comparative study of continuum, explicit and mixed solvation models.  

SciTech Connect (OSTI)

Phosphate hydrolysis is ubiquitous in biology. However, despite intensive research on this class of reactions, the precise nature of the reaction mechanism remains controversial. In this work, we have examined the hydrolysis of three homologous phosphate diesters. The solvation free energy was simulated by means of either an implicit solvation model (COSMO), hybrid quantum mechanical / molecular mechanical free energy perturbation (QM/MM-FEP) or a mixed solvation model in which N water molecules were explicitly included in the ab initio description of the reacting system (where N=1-3), with the remainder of the solvent being implicitly modelled as a continuum. Here, both COSMO and QM/MM-FEP reproduce Delta Gobs within an error of about 2kcal/mol. However, we demonstrate that in order to obtain any form of reliable results from a mixed model, it is essential to carefully select the explicit water molecules from short QM/MM runs that act as a model for the true infinite system. Additionally, the mixed models tend to be increasingly inaccurate the more explicit water molecules are placed into the system. Thus, our analysis indicates that this approach provides an unreliable way for modelling phosphate hydrolysis in solution.

Kamerlin, Shina C. L.; Haranczyk, Maciej; Warshel, Arieh

2009-05-01T23:59:59.000Z

44

Surveying the Free Energy Landscapes of Continuum Models: Application to Soft Matter Systems  

E-Print Network [OSTI]

A variety of methods are developed for characterising the free energy landscapes of continuum, Landau-type free energy models. Using morphologies of lipid vesicles and a multistable liquid crystal device as examples, I show that the methods allow systematic study of not only the most relevant minimum energy configurations, but also the transition pathways between any two minima, as well as their corresponding energy barriers and transition state configurations. A global view of the free energy landscapes can then be visualized using either a disconnectivity graph or a network representation. Different forms of free energy functionals and boundary conditions can be readily implemented, thus allowing these tools to be utilised for a broad range of problems.

Kusumaatmaja, Halim

2015-01-01T23:59:59.000Z

45

Prediction of Damage Zone Growth in Composites Using Continuum Damage Mechanics  

E-Print Network [OSTI]

. Failure Criteria . . . . . . . . . . . . . . . . . . . . . . . . 26 B. Constitutive Degradation Model . . . . . . . . . . . . . . . 27 C. Implementation . . . . . . . . . . . . . . . . . . . . . . . . 29 IV CONFIGURATIONS... . . . . . . . . . . . . . . . . . . . . 34 4. Line of Degraded Elements . . . . . . . . . . . . . . . 35 B. Material Properties . . . . . . . . . . . . . . . . . . . . . . 36 V RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 A. Discrete Crack...

McLendon, Wesley R.

2010-07-14T23:59:59.000Z

46

Viscoelastic acoustic response of layered polymer films at fluid-solid interfaces: Continuum mechanics approach  

E-Print Network [OSTI]

We have derived the general solution of a wave equation describing the dynamics of two-layere viscoelastic polymer materials of arbitrary thickness deposited on solid (quartz) surfaces in a fluid environment. Within the Voight model of viscoelastic element, we calculate the acoustic response of the system to an applied shear stress, i.e. we find the shift of the quartz generator resonance frequency and of the dissipation factor, and show that it strongly depends on the viscous loading of the adsorbed layers and on the shear storage and loss moduli of the overlayers. These results can readily be applied to quartz crystal acoustical measurements of the viscoelasticity of polymers, which conserve their shape under the shear deformations and do not flow, and layered structures such as protein films adsorbed from solution onto the surface of self-assembled monolayres.

M. V. Voinova; M. Rodahl; M. Jonson; B. Kasemo

1998-05-21T23:59:59.000Z

47

CONTINUUM MECHANICS (Lecture Notes)  

E-Print Network [OSTI]

equation 4.2.5 Entropy inequality 4.2.6 R´esum´e of local balance laws 4.3 Jump conditions in special cases 4.4 Local balance laws in the referential description 4.4.1 Continuity equation 4.4.2 Equation material time derivative 6. CONSTITUTIVE EQUATIONS 6.1 The need for constitutive equations 6.2 Formulation

Cerveny, Vlastislav

48

Internal noise driven generalized Langevin equation from a nonlocal continuum model  

E-Print Network [OSTI]

Starting with a micropolar formulation, known to account for nonlocal microstructural effects at the continuum level, a generalized Langevin equation (GLE) for a particle, describing the predominant motion of a localized region through a single displacement degree-of-freedom (DOF), is derived. The GLE features a memory dependent multiplicative or internal noise, which appears upon recognising that the micro-rotation variables possess randomness owing to an uncertainty principle. Unlike its classical version, the new GLE qualitatively reproduces the experimentally measured fluctuations in the steady-state mean square displacement of scattering centers in a polyvinyl alcohol slab. The origin of the fluctuations is traced to nonlocal spatial interactions within the continuum. A constraint equation, similar to a fluctuation dissipation theorem (FDT), is shown to statistically relate the internal noise to the other parameters in the GLE.

Saikat Sarkar; Shubhankar Roy Chowdhury; Debasish Roy; Ram Mohan Vasu

2015-03-10T23:59:59.000Z

49

A continuum model with a percolation threshold and tunneling-assisted interfacial conductivity for carbon nanotube-based nanocomposites  

SciTech Connect (OSTI)

A continuum model that possesses several desirable features of the electrical conduction process in carbon-nanotube (CNT) based nanocomposites is developed. Three basic elements are included: (i) percolation threshold, (ii) interface effects, and (iii) tunneling-assisted interfacial conductivity. We approach the first one through the selection of an effective medium theory. We approach the second one by the introduction of a diminishing layer of interface with an interfacial conductivity to build a 'thinly coated' CNT. The third one is introduced through the observation that interface conductivity can be enhanced by electron tunneling which in turn can be facilitated with the formation of CNT networks. We treat this last issue in a continuum fashion by taking the network formation as a statistical process that can be represented by Cauchy's probability density function. The outcome is a simple and yet widely useful model that can simultaneously capture all these fundamental characteristics. It is demonstrated that, without considering the interface effect, the predicted conductivity would be too high, and that, without accounting for the additional contribution from the tunneling-assisted interfacial conductivity, the predicted conductivity beyond the percolation threshold would be too low. It is with the consideration of all three elements that the theory can fully account for the experimentally measured data. We further use the developed model to demonstrate that, despite the anisotropy of the intrinsic CNT conductivity, it is its axial component along the CNT direction that dominates the overall conductivity. This theory is also proved that, even with a totally insulating matrix, it is still capable of delivering non-zero conductivity beyond the percolation threshold.

Wang, Yang; Weng, George J., E-mail: weng@jove.rutgers.edu [Department of Mechanical and Aerospace Engineering, Rutgers University, New Brunswick, New Jersey 08903 (United States); Meguid, Shaker A. [Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario M5S 3G8 (Canada); Hamouda, Abdel Magid [Department of Mechanical and Industrial Engineering, Qatar University, Doha (Qatar)

2014-05-21T23:59:59.000Z

50

THMC Modeling of EGS Reservoirs ?Continuum through Discontinuum Representations: Capturing Reservoir Stimulation, Evolution and Induced Seismicity  

Broader source: Energy.gov [DOE]

This research will develop a thorough understanding of complex THMC interactions through synthesis, modeling and verification.

51

Gas Kinetic Scheme for Continuum and Near-Continuum Hypersonic Flows  

E-Print Network [OSTI]

Gas Kinetic Scheme for Continuum and Near-Continuum Hypersonic Flows Wei Liao and Li-Shi Luo Old for the near-continuum flows. The gas-kinetic schemes are validated with simulations of the hypersonic flow thickness, modeling and simulation of complex hypersonic flows become very challenging for computational

Luo, Li-Shi

52

A Contribution to the Modeling of Metal Plasticity and Fracture: From Continuum to Discrete Descriptions  

E-Print Network [OSTI]

is motivated by a detailed investigation of the effects of the two types of anisotropy on the materials' effective response using finite element analysis. The model is derived using the Hill-Mandel homogenization theory and an approximate limit analysis of a...

Keralavarma, Shyam Mohan

2012-02-14T23:59:59.000Z

53

Calculation of the Gibbs Free Energy of Solvation and Dissociation of HCl in Water via Monte Carlo Simulations and Continuum Solvation Models  

SciTech Connect (OSTI)

The free energy of solvation and dissociation of hydrogen chloride in water is calculated through a combined molecular simulation quantum chemical approach at four temperatures between T = 300 and 450 K. The free energy is first decomposed into the sum of two components: the Gibbs free energy of transfer of molecular HCl from the vapor to the aqueous liquid phase and the standard-state free energy of acid dissociation of HCl in aqueous solution. The former quantity is calculated using Gibbs ensemble Monte Carlo simulations using either Kohn-Sham density functional theory or a molecular mechanics force field to determine the system’s potential energy. The latter free energy contribution is computed using a continuum solvation model utilizing either experimental reference data or micro-solvated clusters. The predicted combined solvation and dissociation free energies agree very well with available experimental data. CJM was supported by the US Department of Energy,Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

McGrath, Matthew; Kuo, I-F W.; Ngouana, Brice F.; Ghogomu, Julius N.; Mundy, Christopher J.; Marenich, Aleksandr; Cramer, Christopher J.; Truhlar, Donald G.; Siepmann, Joern I.

2013-08-28T23:59:59.000Z

54

The Ionizing Continuum of Quasars  

E-Print Network [OSTI]

The ionizing continuum shape of quasars is generally not directly observable, but indirect arguments, based on photoionization models and thin accretion disk models suggest that it should peak in the extreme UV, and drop steeply into the soft X-ray regime. However, recent observations of very soft X-ray emission in low z quasars, and far UV emission of high z quasars, suggest that the ionizing continuum of quasars does not peak in the extreme UV, and may extend as a single power law from ~1000 A to ~1 keV. If true, that has interesting implications for photoionization models and for accretion disk models. The proposed revised continuum shape will be tested directly in the near future with FUSE.

Ari Laor

1998-10-15T23:59:59.000Z

55

STATISTICAL MECHANICS MODELING OF MESOSCALE DEFORMATION IN METALS  

SciTech Connect (OSTI)

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

56

DENSE MULTIPHASE FLOW SIMULATION: CONTINUUM MODEL FOR POLY-DISPERSED SYSTEMS USING KINETIC THEORY  

SciTech Connect (OSTI)

The overall objective of the project was to verify the applicability of the FCMOM approach to the kinetic equations describing the particle flow dynamics. For monodispersed systems the fundamental equation governing the particle flow dynamics is the Boltzmann equation. During the project, the FCMOM was successfully applied to several homogeneous and in-homogeneous problems in different flow regimes, demonstrating that the FCMOM has the potential to be used to solve efficiently the Boltzmann equation. However, some relevant issues still need to be resolved, i.e. the homogeneous cooling problem (inelastic particles cases) and the transition between different regimes. In this report, the results obtained in homogeneous conditions are discussed first. Then a discussion of the validation results for in-homogeneous conditions is provided. And finally, a discussion will be provided about the transition between different regimes. Alongside the work on development of FCMOM approach studies were undertaken in order to provide insights into anisotropy or particles kinetics in riser hydrodynamics. This report includes results of studies of multiphase flow with unequal granular temperatures and analysis of momentum re-distribution in risers due to particle-particle and fluid-particle interactions. The study of multiphase flow with unequal granular temperatures entailed both simulation and experimental studies of two particles sizes in a riser and, a brief discussion of what was accomplished will be provided. And finally, a discussion of the analysis done on momentum re-distribution of gas-particles flow in risers will be provided. In particular a discussion of the remaining work needed in order to improve accuracy and predictability of riser hydrodynamics based on two-fluid models and how they can be used to model segregation in risers.

Moses Bogere

2011-08-31T23:59:59.000Z

57

Micromechanics and homogenization techniques for analyzing the continuum damage of rock salt  

SciTech Connect (OSTI)

This paper presents a model for evaluating microcrack development and dilatant behavior of crystalline rocks. The model is developed within the concepts of continuum mechanics, with special emphasis on the development of internal boundaries in the continuum by utilizing fracture mechanics based cohesive zone models. The model is capable of describing the evolution from initial debonding through complete separation and subsequent void growth of an interface. An example problem of a rock salt specimen subjected to a high deviatoric load and low confinement is presented that predicts preferential opening of fractures oriented parallel with the maximum compressive stress axis.

DeVries, K.L. [RE/SPEC Inc., Rapid City, SD (United States); Allen, D.H. [Texas A and M Univ., College Station, TX (United States). Dept. of Aerospace Engineering; Hurtado, L.D. [Sandia National Labs., Albuquerque, NM (United States)

1998-03-01T23:59:59.000Z

58

A continuum constitutive model for the mechanical behavior of woven fabrics including slip and failure  

E-Print Network [OSTI]

Woven fabrics are used in many applications, including ballistic armors and fabric-reinforced composites. Advances in small-scale technologies are enabling new applications including fabrics with embedded electronics, ...

King, Michael J. (Michael James), 1978-

2006-01-01T23:59:59.000Z

59

The continuum and wave mechanics  

E-Print Network [OSTI]

S l + ( + * * - ? % ) } J * tlnSByncdny "LRby P is positive semi-definite we bDR YnLSy ? as the square dI some IlRbSLdR Then we note that LI we ayILRy SYd IlRbSLdRG -+ and by the y:lDSLdRG DRa - 2JU A (5i) f * = H e u we can write (52) P...

Collins, Royal Eugene

1954-01-01T23:59:59.000Z

60

Estimation of Absolute Free Energies of Hydration using Continuum Methods: Accuracy of Partial Charge Models and Optimization of Nonpolar Contributions  

E-Print Network [OSTI]

Estimation of Absolute Free Energies of Hydration using Continuum Methods: Accuracy of Partial, and Irwin D. Kuntz Supporting Information Table S1. Experimental Free Energies of Hydration (Ghyd) in kcal,2-dimethylcyclohexane 1.58 36 trans-1,4-dimethylcyclohexane 2.11 37 ethene 1.28 38 propene 1.32 39 but-1-ene 1.38 40

Rizzo, Robert C.

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61

ASSISTANT PROFESSOR OF MECHANICAL ENGINEERING COMPUTATIONAL MODELING  

E-Print Network [OSTI]

ASSISTANT PROFESSOR OF MECHANICAL ENGINEERING COMPUTATIONAL MODELING COLLEGE OF ENGINEERING The Department of Mechanical Engineering at Colorado State University invites applications for a tenure processes with emphasis on applying the models to engineering systems of interest in the energy or materials

62

A Process Model of Quantum Mechanics  

E-Print Network [OSTI]

A process model of quantum mechanics utilizes a combinatorial game to generate a discrete and finite causal space upon which can be defined a self-consistent quantum mechanics. An emergent space-time M and continuous wave function arise through a non-uniform interpolation process. Standard non-relativistic quantum mechanics emerges under the limit of infinite information (the causal space grows to infinity) and infinitesimal scale (the separation between points goes to zero). The model has the potential to address several paradoxes in quantum mechanics while remaining computationally powerful.

William Sulis

2014-04-21T23:59:59.000Z

63

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

SciTech Connect (OSTI)

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

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

2006-11-01T23:59:59.000Z

64

The H2O2+OH ? HO2+H2O reaction in aqueous solution from a charge-dependent continuum model of solvation  

SciTech Connect (OSTI)

We applied our recently developed protocol of the conductor-like continuum model of solvation to describe the title reaction in aqueous solution. The model has the unique feature of the molecular cavity being dependent on the atomic charges in the solute, and can be extended naturally to transition states and reaction pathways. It was used to calculate the reaction energetics and reaction rate in solution for the title reaction. The rate of reaction calculated using canonical variational transition state theory CVT in the context of the equilibrium solvation path (ESP) approximation, and including correction for tunneling through the small curvature approximation (SCT) was found to be 3.6 106 M-1 s-1, in very good agreement with experiment, These results suggest that the present protocol of the conductor-like continuum model of solvation with the charge-dependent cavity definition captures accurately the solvation effects at transition states and allows for quantitative estimates of reaction rates in solutions. This work was supported by the U.S. Department of Energy's (DOE) Office of Basic Energy Sciences, Chemical Sciences program. The Pacific Northwest National Laboratory is operated by Battelle for DOE.

Ginovska, Bojana; Camaioni, Donald M.; Dupuis, Michel

2008-07-07T23:59:59.000Z

65

Modeling the mechanical response of PBX 9501  

SciTech Connect (OSTI)

An engineering overview of the mechanical response of Plastic-Bonded eXplosives (PBXs), specifically PBX 9501, will be provided with emphasis on observed mechanisms associated with different types of mechanical testing. Mechanical tests in the form of uniaxial tension, compression, cyclic loading, creep (compression and tension), and Hopkinson bar show strain rate and temperature dependence. A range of mechanical behavior is observed which includes small strain recoverable response in the form of viscoelasticity; change in stiffness and softening beyond peak strength due to damage in the form microcracks, debonding, void formation and the growth of existing voids; inelastic response in the form of irrecoverable strain as shown in cyclic tests, and viscoelastic creep combined with plastic response as demonstrated in creep and recovery tests. The main focus of this paper is to elucidate the challenges and issues involved in modeling the mechanical behavior of PBXs for simulating thermo-mechanical responses in engineering components. Examples of validation of a constitutive material model based on a few of the observed mechanisms will be demonstrated against three point bending, split Hopkinson pressure bar and Brazilian disk geometry.

Ragaswamy, Partha [Los Alamos National Laboratory; Lewis, Matthew W [Los Alamos National Laboratory; Liu, Cheng [Los Alamos National Laboratory; Thompson, Darla G [Los Alamos National Laboratory

2010-01-01T23:59:59.000Z

66

Mechanics of hydrogen storage in carbon nanotubes Y.L. Chen a  

E-Print Network [OSTI]

Mechanics of hydrogen storage in carbon nanotubes Y.L. Chen a , B. Liu a,Ã?, J. Wu a , Y. Huang b 17 July 2008 Keywords: Hydrogen storage Carbon nanotube Continuum model Analytical solution Atomistic simulations a b s t r a c t A continuum mechanics model is established for hydrogen storage in single

Jiang, Hanqing

67

Microstructure Based Modeling of ? Phase Influence on Mechanical...  

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

Based Modeling of ? Phase Influence on Mechanical Response of Cast AM Series Mg Alloys. Microstructure Based Modeling of ? Phase Influence on Mechanical Response of Cast...

68

Coupled Kinetic, Thermal, and Mechanical Modeling of FIB Micro...  

Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

Coupled Kinetic, Thermal, and Mechanical Modeling of FIB Micro-machined Electrodes Coupled Kinetic, Thermal, and Mechanical Modeling of FIB Micro-machined Electrodes 2010 DOE...

69

A Signal Processing Model of Quantum Mechanics  

E-Print Network [OSTI]

This paper develops a deterministic model of quantum mechanics as an accumulation-and-threshold process. The model arises from an analogy with signal processing in wireless communications. Complex wavefunctions are interpreted as expressing the amplitude and phase information of a modulated carrier wave. Particle transmission events are modeled as the outcome of a process of signal accumulation that occurs in an extra (non-spacetime) dimension. Besides giving a natural interpretation of the wavefunction and the Born rule, the model accommodates the collapse of the wave packet and other quantum paradoxes such as EPR and the Ahanorov-Bohm effect. The model also gives a new perspective on the 'relational' nature of quantum mechanics: that is, whether the wave function of a physical system is "real" or simply reflects the observer's partial knowledge of the system. We simulate the model for a 2-slit experiment, and indicate possible deviations of the model's predictions from conventional quantum mechanics. We also indicate how the theory may be extended to a field theory.

Chris Thron; Johnny Watts

2012-05-08T23:59:59.000Z

70

MECHANICAL BEHAVIOUR OF PVC: MODEL EVALUATION  

E-Print Network [OSTI]

MECHANICAL BEHAVIOUR OF PVC: MODEL EVALUATION BY DMYTRO MIROSHNYCHENKO A MASTER'S THESIS SUBMITTED in the prediction of the Treloar data . . . 60 3 The yield stress of oriented PVC and its prediction 66 3 of oriented PVC . . . . . . 69 3.4 Prediction of the yield stress of oriented PVC . . . . . . . . . . . . . 73

Miroshnychenko, Dmitri

71

Doctoral Defense "Thermal-hydro-mechanical model  

E-Print Network [OSTI]

Doctoral Defense "Thermal-hydro-mechanical model for freezing and thawing soils" Yao Zhang Date & Environmental Engineering Frost susceptible soils are vulnerable to frost action in seasonal freezing as well and strengthening occurs as the soils freeze, whereas settlement and thaw weakening is expected during the melting

Kamat, Vineet R.

72

Development of multicomponent hybrid density functional theory with polarizable continuum model for the analysis of nuclear quantum effect and solvent effect on NMR chemical shift  

SciTech Connect (OSTI)

We have developed the multicomponent hybrid density functional theory [MC-(HF+DFT)] method with polarizable continuum model (PCM) for the analysis of molecular properties including both nuclear quantum effect and solvent effect. The chemical shifts and H/D isotope shifts of the picolinic acid N-oxide (PANO) molecule in chloroform and acetonitrile solvents are applied by B3LYP electron exchange-correlation functional for our MC-(HF+DFT) method with PCM (MC-B3LYP/PCM). Our MC-B3LYP/PCM results for PANO are in reasonable agreement with the corresponding experimental chemical shifts and isotope shifts. We further investigated the applicability of our method for acetylacetone in several solvents.

Kanematsu, Yusuke; Tachikawa, Masanori [Quantum Chemistry Division, Yokohama City University, Seto 22-2, Kanazawa-ku, Yokohama 236-0027 (Japan)] [Quantum Chemistry Division, Yokohama City University, Seto 22-2, Kanazawa-ku, Yokohama 236-0027 (Japan)

2014-04-28T23:59:59.000Z

73

Fully coupled thermal-mechanical-fluid flow model for nonliner geologic systems  

SciTech Connect (OSTI)

A single model is presented which describes fully coupled thermal-mechanical-fluid flow behavior of highly nonlinear, dynamic or quasistatic, porous geologic systems. The mathematical formulation for the model utilizes the continuum theory of mixtures to describe the multiphase nature of the system, and incremental linear constitutive theory to describe the path dependency of nonlinear material behavior. The model, incorporated in an explicit finite difference numerical procedure, was implemented in two different computer codes. A special-purpose one-dimensional code, SNEAKY, was written for initial validation of the coupling mechanisms and testing of the coupled model logic. A general purpose commercially available code, STEALTH, developed for modeling dynamic nonlinear thermomechanical processes, was modified to include fluid flow behavior and the coupling constitutive model. The fully explicit approach in the coupled calculation facilitated the inclusion of the coupling mechanisms and complex constitutive behavior. Analytical solutions pertaining to consolidation theory for soils, thermoelasticity for solids, and hydrothermal convection theory provided verification of stress and fluid flow, stress and conductive heat transfer, and heat transfer and fluid flow couplings, respectively, in the coupled model. A limited validation of the adequacy of the coupling constitutive assumptions was also performed by comparison with the physical response from two laboratory tests. Finally, the full potential of the coupled model is illustrated for geotechnical applications in energy-resource related areas. Examples in the areas of nuclear waste isolation and cut-and-fill mining are cited.

Hart, R.D.

1981-01-01T23:59:59.000Z

74

Statistical Mechanical Models and Topological Color Codes  

E-Print Network [OSTI]

We find that the overlapping of a topological quantum color code state, representing a quantum memory, with a factorized state of qubits can be written as the partition function of a 3-body classical Ising model on triangular or Union Jack lattices. This mapping allows us to test that different computational capabilities of color codes correspond to qualitatively different universality classes of their associated classical spin models. By generalizing these statistical mechanical models for arbitrary inhomogeneous and complex couplings, it is possible to study a measurement-based quantum computation with a color code state and we find that their classical simulatability remains an open problem. We complement the meaurement-based computation with the construction of a cluster state that yields the topological color code and this also gives the possibility to represent statistical models with external magnetic fields.

H. Bombin; M. A. Martin-Delgado

2007-11-03T23:59:59.000Z

75

Failure Predictions for VHTR Core Components using a Probabilistic Contiuum Damage Mechanics Model  

SciTech Connect (OSTI)

The proposed work addresses the key research need for the development of constitutive models and overall failure models for graphite and high temperature structural materials, with the long-term goal being to maximize the design life of the Next Generation Nuclear Plant (NGNP). To this end, the capability of a Continuum Damage Mechanics (CDM) model, which has been used successfully for modeling fracture of virgin graphite, will be extended as a predictive and design tool for the core components of the very high- temperature reactor (VHTR). Specifically, irradiation and environmental effects pertinent to the VHTR will be incorporated into the model to allow fracture of graphite and ceramic components under in-reactor conditions to be modeled explicitly using the finite element method. The model uses a combined stress-based and fracture mechanics-based failure criterion, so it can simulate both the initiation and propagation of cracks. Modern imaging techniques, such as x-ray computed tomography and digital image correlation, will be used during material testing to help define the baseline material damage parameters. Monte Carlo analysis will be performed to address inherent variations in material properties, the aim being to reduce the arbitrariness and uncertainties associated with the current statistical approach. The results can potentially contribute to the current development of American Society of Mechanical Engineers (ASME) codes for the design and construction of VHTR core components.

Fok, Alex

2013-10-30T23:59:59.000Z

76

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

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

Coupled Thermal-Hydrological-Mechanical-Chemical Model and Experiments for Optimization of Enhanced Geothermal System Development and Production Coupled Thermal-Hydrological-Mechan...

77

Mechanical Models of Fault-Related Folding  

SciTech Connect (OSTI)

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

78

Continuum Electrostatics in Cell Biology  

E-Print Network [OSTI]

Recent experiments revealing possible nanoscale electrostatic interactions in force generation at kinetochores for chromosome motions have prompted speculation regarding possible models for interactions between positively charged molecules in kinetochores and negative charge on C-termini near the plus ends of microtubules. A clear picture of how kinetochores establish and maintain a dynamic coupling to microtubules for force generation during the complex motions of mitosis remains elusive. The current paradigm of molecular cell biology requires that specific molecules, or molecular geometries, for force generation be identified. However, it is possible to account for mitotic motions within a classical electrostatics approach in terms of experimentally known cellular electric charge interacting over nanometer distances. These charges are modeled as bound surface and volume continuum charge distributions. Electrostatic consequences of intracellular pH changes during mitosis may provide a master clock for the events of mitosis.

L. John Gagliardi

2010-02-06T23:59:59.000Z

79

Modeling-Thermo-electrochemistry, Capacity Degradation and Mechanics...  

Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

& Publications Microscale Electrode Design Using Coupled Kinetic, Thermal and Mechanical Modeling Modeling - Scale-Bridging Simulations Active Materials in Li-ion Batteries,...

80

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

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While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Prediction of Thermal Conductivity for Irradiated SiC/SiC Composites by Informing Continuum Models with Molecular Dynamics Data  

SciTech Connect (OSTI)

This article proposes a new method to estimate the thermal conductivity of SiC/SiC composites subjected to neutron irradiation. The modeling method bridges different scales from the atomic scale to the scale of a 2D SiC/SiC composite. First, it studies the irradiation-induced point defects in perfect crystalline SiC using molecular dynamics (MD) simulations to compute the defect thermal resistance as a function of vacancy concentration and irradiation dose. The concept of defect thermal resistance is explored explicitly in the MD data using vacancy concentrations and thermal conductivity decrements due to phonon scattering. Point defect-induced swelling for chemical vapor deposited (CVD) SiC as a function of irradiation dose is approximated by scaling the corresponding MD results for perfect crystal ?-SiC to experimental data for CVD-SiC at various temperatures. The computed thermal defect resistance, thermal conductivity as a function of grain size, and definition of defect thermal resistance are used to compute the thermal conductivities of CVD-SiC, isothermal chemical vapor infiltrated (ICVI) SiC and nearly-stoichiometric SiC fibers. The computed fiber and ICVI-SiC matrix thermal conductivities are then used as input for an Eshelby-Mori-Tanaka approach to compute the thermal conductivities of 2D SiC/SiC composites subjected to neutron irradiation within the same irradiation doses. Predicted thermal conductivities for an irradiated Tyranno-SA/ICVI-SiC composite are found to be comparable to available experimental data for a similar composite ICVI-processed with these fibers.

Nguyen, Ba Nghiep; Gao, Fei; Henager, Charles H.; Kurtz, Richard J.

2014-05-01T23:59:59.000Z

82

A Conceptual Approach to Two-Scale Constitutive Modelling For Hydro-Mechanical Coupling  

E-Print Network [OSTI]

Large scale modelling of fluid flow coupled with solid failure in geothermal reservoirs or hydrocarbon extraction from reservoir rocks usually involves behaviours at two scales: lower scale of the inelastic localization zone, and larger scale of the bulk continuum where elastic behaviour can be reasonably assumed. The hydraulic conductivities corresponding to the mechanical properties at these two scales are different. In the bulk elastic host rock, the hydraulic conductivity does not vary much with the deformation, while it significantly changes in the lower scale of the localization zone due to inelastic deformation. Increase of permeability due to fracture and/or dilation, or reduction of permeability due to material compaction can take place inside this zone. The challenge is to predict the evolution of hydraulic conductivities coupled with the mechanical behaviour of the material in all stages of the deformation process. In the early stage of diffuse deformation, the permeability of the material can be reasonably assumed to be homogenous over the whole Representative Volume Element (RVE) However, localized failure results in distinctly different conductivities in different parts of the RVE. This paper establishes a general framework and corresponding field equations to describe the hydro-mechanical coupling in both diffuse and localized stages of deformation in rocks. In particular, embedding the lower scale hydro-mechanical behaviour of the localization zone inside an elastic bulk, together with their corresponding effective sizes, helps effectively deal with scaling issues in large-scale modelling. Preliminary results are presented which demonstrate the promising features of this new approach.

Giang D. Nguyen; Abbas El-Zein; Terry Bennett

2014-06-05T23:59:59.000Z

83

A new approach to the modeling and analysis of fracture through an extension of continuum mechanics to the nanoscale  

E-Print Network [OSTI]

is the material description of T. For F near I we have ^T?(F) = ^T?(I)+C[E]+o(H); where C = D^T?(I) is the elasticity tensor. One easily shows ([22]) that if the material is isotropic at X, there exist scalars ?(X) and ?(X) such that C[E] = 2?E+?(trE...)I: ? and ? are called Lam?e moduli. If the residual stress vanishes (^T?(I) = ^T(I) = 0), (2.2) yields T = 1JT?FT = (1?tr(H)+o(H))C[E]?I+HT? = C[E]+o(H): Now, let ~u(x) be the Eulerian description of the displacement vector, where u(X) = ~u(f(X)) 8 and let1 e = 12?grad...

Sendova, Tsvetanka Bozhidarova

2009-05-15T23:59:59.000Z

84

Atomistic simulation and continuum modeling of graphene nanoribbons under uniaxial tension This article has been downloaded from IOPscience. Please scroll down to see the full text article.  

E-Print Network [OSTI]

for more Home Search Collections Journals About Contact us My IOPscience #12;IOP PUBLISHING MODELLING determination of the bulk strain energy density, the edge energy density and the hydrogen adsorption energy. These functions can be used to describe mechanical behavior of graphene nanoribbons from the initial linear

Huang, Rui

85

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

Open Energy Info (EERE)

to the most hydraulically conductive fractures in two orthogonal and vertical fracture sets. The mathematical model representing the hydro-mechanical interactions that are...

86

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

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

Coupled Thermal-Hydrological-Mechanical-Chemical Model And Experiments For Optimization Of Enhanced Geothermal System Development And Production: Evaluation of Stimulation at the...

87

Atom-to-continuum methods for gaining a fundamental understanding of fracture.  

SciTech Connect (OSTI)

This report describes an Engineering Sciences Research Foundation (ESRF) project to characterize and understand fracture processes via molecular dynamics modeling and atom-to-continuum methods. Under this aegis we developed new theory and a number of novel techniques to describe the fracture process at the atomic scale. These developments ranged from a material-frame connection between molecular dynamics and continuum mechanics to an atomic level J integral. Each of the developments build upon each other and culminated in a cohesive zone model derived from atomic information and verified at the continuum scale. This report describes an Engineering Sciences Research Foundation (ESRF) project to characterize and understand fracture processes via molecular dynamics modeling and atom-to-continuum methods. The effort is predicated on the idea that processes and information at the atomic level are missing in engineering scale simulations of fracture, and, moreover, are necessary for these simulations to be predictive. In this project we developed considerable new theory and a number of novel techniques in order to describe the fracture process at the atomic scale. Chapter 2 gives a detailed account of the material-frame connection between molecular dynamics and continuum mechanics we constructed in order to best use atomic information from solid systems. With this framework, in Chapter 3, we were able to make a direct and elegant extension of the classical J down to simulations on the scale of nanometers with a discrete atomic lattice. The technique was applied to cracks and dislocations with equal success and displayed high fidelity with expectations from continuum theory. Then, as a prelude to extension of the atomic J to finite temperatures, we explored the quasi-harmonic models as efficient and accurate surrogates of atomic lattices undergoing thermo-elastic processes (Chapter 4). With this in hand, in Chapter 5 we provide evidence that, by using the appropriate energy potential, the atomic J integral we developed is calculable and accurate at finite/room temperatures. In Chapter 6, we return in part to the fundamental efforts to connect material behavior at the atomic scale to that of the continuum. In this chapter, we devise theory that predicts the onset of instability characteristic of fracture/failure via atomic simulation. In Chapters 7 and 8, we describe the culmination of the project in connecting atomic information to continuum modeling. In these chapters we show that cohesive zone models are: (a) derivable from molecular dynamics in a robust and systematic way, and (b) when used in the more efficient continuum-level finite element technique provide results that are comparable and well-correlated with the behavior at the atomic-scale. Moreover, we show that use of these same cohesive zone elements is feasible at scales very much larger than that of the lattice. Finally, in Chapter 9 we describe our work in developing the efficient non-reflecting boundary conditions necessary to perform transient fracture and shock simulation with molecular dynamics.

McDowell, David Lynn (Georgia Institute of Technology, Atlanta, GA); Reedy, Earl David, Jr.; Templeton, Jeremy Alan; Jones, Reese E.; Moody, Neville Reid; Zimmerman, Jonathan A.; Belytschko, Ted. (Northwestern University, Evanston, IL); Zhou, Xiao Wang; Lloyd, Jeffrey T. (Georgia Institute of Technology, Atlanta, GA); Oswald, Jay (Northwestern University, Evanston, IL); Delph, Terry J. (Lehigh University, Bethlehem, PA); Kimmer, Christopher J. (Indiana University Southeast, New Albany, IN)

2011-08-01T23:59:59.000Z

88

Rock mechanics models evaluation report. [Contains glossary  

SciTech Connect (OSTI)

This report documents the evaluation of the thermal and thermomechanical models and codes for repository subsurface design and for design constraint analysis. The evaluation was based on a survey of the thermal and thermomechanical codes and models that are applicable to subsurface design, followed by a Kepner-Tregoe (KT) structured decision analysis of the codes and models. The primary recommendations of the analysis are that the DOT code be used for two-dimensional thermal analysis and that the STEALTH and HEATING 5/6 codes be used for three-dimensional and complicated two-dimensional thermal analysis. STEALTH and SPECTROM 32 are recommended for thermomechanical analyses. The other evaluated codes should be considered for use in certain applications. A separate review of salt creep models indicate that the commonly used exponential time law model is appropriate for use in repository design studies. 38 refs., 1 fig., 7 tabs.

Not Available

1987-08-01T23:59:59.000Z

89

Modeling thermal/chemical/mechanical response of energetic materials  

SciTech Connect (OSTI)

An overview of modeling at Sandia National Laboratories is presented which describes coupled thermal, chemical and mechanical response of energetic materials. This modeling addresses cookoff scenarios for safety assessment studies in systems containing energetic materials. Foundation work is discussed which establishes a method for incorporating chemistry and mechanics into multidimensional analysis. Finite element analysis offers the capabilities to simultaneously resolve reactive heat transfer and structural mechanics in complex geometries. Nonlinear conduction heat transfer, with multiple step finite-rate chemistry, is resolved using a thermal finite element code. Rate equations are solved element-by-element using a modified matrix-free stiff solver This finite element software was developed for the simulation of systems requiring large numbers of finite elements. An iterative implicit scheme, based on the conjugate gradient method, is used and a hemi-cube algorithm is employed for the determination of view factors in surface-to-surface radiation transfer The critical link between the reactive heat transfer and mechanics is the introduction of an appropriate constitutive material model providing a stress-strain relationship for quasi-static mechanics analysis. This model is formally derived from bubble nucleation theory, and parameter variations of critical model parameters indicate that a small degree of decomposition leads to significant mechanical response. Coupled thermal/chemical/mechanical analysis is presented which simulates experiments designed to probe cookoff thermal-mechanical response of energetic materials.

Baer, M.R.; Hobbs, M.L.; Gross, R.J. [and others

1995-07-01T23:59:59.000Z

90

Quantum mechanical Hamiltonian models of the computation process  

SciTech Connect (OSTI)

As noted in the proceedings of this conference it is of importance to determine if quantum mechanics imposes fundamental limits on the computation process. Some aspects of this problem have been examined by the development of different types of quantum mechanical Hamiltonian models of Turing machines. (Benioff 1980, 1982a, 1982b, 1982c). Turing machines were considered because they provide a standard representation of all digital computers. Thus, showing the existence of quantum mechanical models of all Turing machines is equivalent to showing the existence of quantum mechanical models of all digital computers. The types of models considered all had different properties. Some were constructed on two-dimensional lattices of quantum spin systems of spin 1/2 (Benioff 1982b, 1982c) or higher spins (Benioff 1980). All the models considered Turing machine computations which were made reversible by addition of a history tape. Quantum mechanical models of Bennett's reversible machines (Bennett 1973) in which the model makes a copy of the computation result and then erases the history and undoes the computation in lockstep to recover the input were also developed (Benioff 1982a). To avoid technical complications all the types of models were restricted to modelling an arbitrary but finite number of computation steps.

Benioff, P.

1983-01-01T23:59:59.000Z

91

Model to predict the mechanical behaviour of oriented rigid PVC  

E-Print Network [OSTI]

Model to predict the mechanical behaviour of oriented rigid PVC D. J. Hitt*1 and D. Miroshnychenko2 The mechanical properties of PVC sheets can be modified substantially by both uniaxial and biaxial stretching pattern in the relationship between tensile properties of oriented PVC products and imposed strains

Miroshnychenko, Dmitri

92

Modeling biofilms with dual extracellular electron transfer mechanisms  

SciTech Connect (OSTI)

Electrochemically active biofilms have a unique form of respiration in which they utilize solid external materials as their terminal electron acceptor for metabolism. Currently, two primary mechanisms have been identified for long-range extracellular electron transfer (EET): a diffusion- and a conduction-based mechanism. Evidence in the literature suggests that some biofilms, particularly Shewanella oneidensis, produce components requisite for both mechanisms. In this study, a generic model is presented that incorporates both diffusion- and conduction-based mechanisms and allows electrochemically active biofilms to utilize both simultaneously. The model was applied to Shewanella oneidensis and Geobacter sulfurreducens biofilms using experimentally generated data found the literature. Our simulation results showed that 1) biofilms having both mechanisms available, especially if they can interact, may have metabolic advantage over biofilms that can use only a single mechanism; 2) the thickness of Geobacter sulfurreducens biofilms is likely not limited by conductivity; 3) accurate intrabiofilm diffusion coefficient values are critical for current generation predictions; and 4) the local biofilm potential and redox potential are two distinct measurements and cannot be assumed to have identical values. Finally, we determined that cyclic and squarewave voltammetry are currently not good tools to determine the specific percentage of extracellular electron transfer mechanisms used by biofilms. The developed model will be a critical tool in designing experiments to explain EET mechanisms.

Renslow, Ryan S.; Babauta, Jerome T.; Kuprat, Andrew P.; Schenk, Jim; Ivory, Cornelius; Fredrickson, Jim K.; Beyenal, Haluk

2013-11-28T23:59:59.000Z

93

Approaching continuum monopoles  

SciTech Connect (OSTI)

We set up the calculation of the expectation value of the monopole creation operator in the confining phase of the 4d Georgi-Glashow model. We find that in the leading order of the perturbation theory the VEV vanishes as a power of the volume of the system. This is in accordance with our naive expectation. We expect that nonperturbative effects will introduce an effective infrared cutoff on the calculation making the VEV finite.

Kovner, Alex [Physics Department, University of Connecticut, 2152 Hillside Road, Storrs, CT 06269-3046 (United States); Khvedelidze, Arsen; McMullan, David [School of Mathematics and Statistics, University of Plymouth, Drake Circus, Plymouth PLA 8AA (United Kingdom)

2006-07-11T23:59:59.000Z

94

Material-modeling and structural-mechanics aspects  

E-Print Network [OSTI]

Material-modeling and structural-mechanics aspects of the traumatic brain injury problem M for causing traumatic brain injury. Design/methodology/approach ­ Two levels of blast peak overpressure were computational investigation of impact on a human skull/brain assembly. Keywords Brain, Injuries, Modeling

Grujicic, Mica

95

A mechanical approach to mean field spin models  

E-Print Network [OSTI]

Inspired by the bridge pioneered by Guerra among statistical mechanics on lattice and analytical mechanics on 1+1 continuous Euclidean space-time, we built a self-consistent method to solve for the thermodynamics of mean-field models defined on lattice, whose order parameters self average. We show the whole procedure by analyzing in full details the simplest test case, namely the Curie-Weiss model. Further we report some applications also to models whose order parameters do not self-average, by using the Sherrington-Kirkpatrick spin glass as a guide.

Giuseppe Genovese; Adriano Barra

2009-05-07T23:59:59.000Z

96

NREL: Continuum Magazine Home Page  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLas Conchas recoveryLaboratory | National Nuclearover two Continuum is the National Renewable

97

NREL: Continuum Magazine Home Page  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLas Conchas recoveryLaboratory | National Nuclearover two Continuum is the National

98

Continuum  

E-Print Network [OSTI]

of shut-off and that warp drive was at least six minutes away, two minutes too long for any of them, unless someone could go into that radiation filled room and fix the engines. Spock had gotten up and left the bridge and Saavik had known where he...

Welling, Lois

1983-01-01T23:59:59.000Z

99

Modelling the mechanical behaviour of pharmaceutical powders during compaction  

E-Print Network [OSTI]

are made of dry powder through a powder compaction process. In the pharmaceutical industry, billionsModelling the mechanical behaviour of pharmaceutical powders during compaction C.-Y. Wua,T, O.M. Ruddyb , A.C. Benthamb , B.C. Hancockc , S.M. Besta , J.A. Elliotta a Pfizer Institute for Pharmaceutical

Elliott, James

100

Thermal And Thermo-Mechanical Modelling of Polymer Overmoulded Electronics  

E-Print Network [OSTI]

electronics for use in the demanding automotive environment. A two shot moulding technology will protect of electronics within polymer materials is of great interest to the automotive industry as a means to protectThermal And Thermo-Mechanical Modelling of Polymer Overmoulded Electronics F. Sarvar1 , D. C

Paris-Sud XI, Université de

Note: This page contains sample records for the topic "mechanics continuum modeling" 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

Mechanical modeling of porous oxide fuel pellet A Test Problem  

SciTech Connect (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

102

Non-Thermal Continuum toward SGRB2(N-LMH)  

E-Print Network [OSTI]

An analysis of continuum antenna temperatures observed in the Green Bank Telescope (GBT) spectrometer bandpasses is presented for observations toward SgrB2(N-LMH). Since 2004, we have identified four new prebiotic molecules toward this source by means of rotational transitions between low energy levels; concurrently, we have observed significant continuum in the GBT spectrometer bandpasses centered at 85 different frequencies in the range of 1 to 48 GHz. The continuum heavily influences the molecular spectral features since we have observed far more absorption lines than emission lines for each of these new molecular species. Hence, it is important to understand the nature, distribution, and intensity of the underlying continuum in the GBT bandpasses for the purposes of radiative transfer, i.e. the means by which reliable molecular abundances are estimated. We find that the GBT spectrometer bandpass continuum is consistent with optically-thin, non thermal (synchrotron) emission with a flux density spectral index of -0.7 and a Gaussian source size of ~143" at 1 GHz that decreases with increasing frequency as nu^(-0.52). Some support for this model is provided by high frequency Very Large Array (VLA) observations of SgrB2.

J. M. Hollis; P. R. Jewell; Anthony J. Remijan; F. J. Lovas

2007-03-15T23:59:59.000Z

103

Continuum Partners | Open Energy Information  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home5b9fcbce19 NoPublic Utilities Address: 160Benin:EnergyWisconsin:2003) | OpenMinor Permit Applications JumpContainedContinuum

104

A mechanical model of early salt dome growth  

E-Print Network [OSTI]

of Department) December 1988 A Mechanical Analysis of Early Salt Dome Growth. (December 1988) Frank Albert Irwin, B. S. , Texas A&M University Chair of Advisory Committee: Dr. Raymond C. Fletcher A two-layer superposition model, the lower layer representing... of the sediments results in growth rates much higher than those observed. Analysis of the case with a diffusivity of 104m2/Ka agrees with all observa- tions. A range of diffusivities which will produce a realistic salt dome model is then determined. The lower...

Irwin, Frank Albert

1988-01-01T23:59:59.000Z

105

Hydro-mechanical modelling of geological CO2 storage and the study of possible caprock fracture mechanisms  

E-Print Network [OSTI]

Hydro-mechanical modelling of geological CO2 storage and the study of possible caprock fracture element modelling of a hypothetical underground carbon dioxide (CO2) storage operation. The hydro

106

An Improved Probabilistic Fracture Mechanics Model for Pressurized Thermal Shock  

SciTech Connect (OSTI)

This paper provides an overview of an improved probabilistic fracture mechanics (PFM) model used for calculating the conditional probabilities of fracture and failure of a reactor pressure vessel (RPV) subjected to pressurized-thermal-shock (PTS) transients. The updated PFM model incorporates several new features: expanded databases for the fracture toughness properties of RPV steels; statistical representations of the fracture toughness databases developed through application of rigorous mathematical procedures; and capability of generating probability distributions for RPV fracture and failure. The updated PFM model was implemented into the FAVOR fracture mechanics program, developed at Oak Ridge National Laboratory as an applications tool for RPV integrity assessment; an example application of that implementation is discussed herein. Applications of the new PFM model are providing essential input to a probabilistic risk assessment (PRA) process that will establish an improved technical basis for re-assessment of current PTS regulations by the US Nuclear Regulatory Commission (NRC). The methodology described herein should be considered preliminary and subject to revision in the PTS re-evaluation process.

Dickson, T.L.

2001-10-29T23:59:59.000Z

107

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

SciTech Connect (OSTI)

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

2012-05-15T23:59:59.000Z

108

Mechanical reaction-diffusion model for bacterial population dynamics  

E-Print Network [OSTI]

The effect of mechanical interaction between cells on the spreading of bacterial population was investigated in one-dimensional space. A nonlinear reaction-diffusion equation has been formulated as a model for this dynamics. In this model, the bacterial cells are treated as the rod-like particles that interact, when contacting each other, through the hard-core repulsion. The repulsion introduces the exclusion process that causes the fast diffusion in bacterial population at high density. The propagation of the bacterial density as the traveling wave front in long time behavior has been analyzed. The analytical result reveals that the front speed is enhanced by the exclusion process---and its value depends on the packing fraction of cell. The numerical solutions of the model have been solved to confirm this prediction.

Ngamsaad, Waipot

2015-01-01T23:59:59.000Z

109

Comprehensive mechanisms for combustion chemistry: Experiment, modeling, and sensitivity analysis  

SciTech Connect (OSTI)

This research program is an integrated experimental/numerical effort to study pyrolysis and oxidation reactions and mechanisms for small-molecule hydrocarbon structures under conditions representative of combustion environments. The experimental aspects of the work are conducted in large diameter flow reactors, at pressures from one to twenty atmospheres, temperatures from 550 K to 1200 K, and with observed reaction times from 10{sup {minus}2} to 5 seconds. Gas sampling of stable reactant, intermediate, and product species concentrations provides not only substantial definition of the phenomenology of reaction mechanisms, but a significantly constrained set of kinetic information with negligible diffusive coupling. Analytical techniques used for detecting hydrocarbons and carbon oxides include gas chromatography (GC), and gas infrared (NDIR) and FTIR methods are utilized for continuous on-line sample detection of light absorption measurements of OH have also been performed in an atmospheric pressure flow reactor (APFR), and a variable pressure flow (VPFR) reactor is presently being instrumented to perform optical measurements of radicals and highly reactive molecular intermediates. The numerical aspects of the work utilize zero and one-dimensional pre-mixed, detailed kinetic studies, including path, elemental gradient sensitivity, and feature sensitivity analyses. The program emphasizes the use of hierarchical mechanistic construction to understand and develop detailed kinetic mechanisms. Numerical studies are utilized for guiding experimental parameter selections, for interpreting observations, for extending the predictive range of mechanism constructs, and to study the effects of diffusive transport coupling on reaction behavior in flames. Modeling using well defined and validated mechanisms for the CO/H{sub 2}/oxidant systems.

Dryer, F.L.; Yetter, R.A. [Princeton Univ., NJ (United States)

1993-12-01T23:59:59.000Z

110

Microstructurally-based constitutive models of cytoskeletal networks for simulation of the biomechanical response of biological cells  

E-Print Network [OSTI]

The elastic and viscoelastic stress-strain behavior of cytoskeletal networks, important to many cellular functions, is modeled via a microstructurally-informed continuum mechanics approach. The force-extension behavior of ...

Palmer, Jeffrey Shane

2008-01-01T23:59:59.000Z

111

On a Model of Quantum Mechanics and the Mind  

E-Print Network [OSTI]

In this paper I discuss Stapp's (2014) interesting proposal of using the Quantum Zeno Effect to account for the mind/matter interaction. In particular, I discuss some of the motivations for it, and then argue that, in his current version, his model is circular (a solution to this, proposed by Kathryn Laskey, is presented), insofar as the mind/matter problem is concerned. I also present an alternative approach to some of the appealing aspects of using quantum mechanics to think about consciousness.

J. Acacio de Barros

2014-04-16T23:59:59.000Z

112

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

113

Effective constrained polymeric theories and their continuum limit  

E-Print Network [OSTI]

The classical limit of polymer quantum theories yields a one parameter family of `effective' theories labeled by \\lambda. Here we consider such families for constrained theories and pose the problem of taking the `continuum limit', \\lambda -> 0. We put forward criteria for such question to be well posed, and propose a concrete strategy based in the definition of appropriately constructed Dirac observables. We analyze two models in detail, namely a constrained oscillator and a cosmological model arising from loop quantum cosmology. For both these models we show that the program can indeed be completed, provided one makes a particular choice of \\lambda-dependent internal time with respect to which the dynamics is described and compared. We show that the limiting theories exist and discuss the corresponding limit. These results might shed some light in the problem of defining a renormalization group approach, and its associated continuum limit, for quantum constrained systems.

Alejandro Corichi; Tatjana Vukasinac

2012-08-02T23:59:59.000Z

114

N + 1 dimensional quantum mechanical model for a closed universe  

E-Print Network [OSTI]

A quantum mechanical model for an N + 1 dimensional universe arising from a quantum fluctuation is outlined. (3 + 1) dimensions are a closed infinitely-expanding universe and the remaining N - 3 dimensions are compact. The (3 + 1) non-compact dimensions are modeled by quantizing a canonical Hamiltonian description of a homogeneous isotropic universe. It is assumed gravity and the strong-electro-weak (SEW) forces had equal strength in the initial state. Inflation occurred when the compact N -3 dimensional space collapsed after a quantum transition from the initial state of the univers, during its evolution to the present state where gravity is much weaker than the SEW force. The model suggests the universe has no singularities and the large size of our present universe is determined by the relative strength of gravity and the SEW force today. A small cosmological constant, resulting from the zero point energy of the scalar field corresponding to the compact dimensions, makes the model universe expand forever.

T. R. Mongan

1999-02-10T23:59:59.000Z

115

Mechanical modeling of the growth of salt structures  

SciTech Connect (OSTI)

A 2D numerical model for studying the morphology and history of salt structures by way of computer simulations is presented. The model is based on conservation laws for physical systems, a fluid marker equation to keep track of the salt/sediments interface, and two constitutive laws for rocksalt. When buoyancy alone is considered, the fluid-assisted diffusion model predicts evolution of salt structures 2.5 times faster than the power-law creep model. Both rheological laws predict strain rates of the order of 4.0 {times} 10{sup {minus}15}s{sup {minus}1} for similar structural maturity level of salt structures. Equivalent stresses and viscosities predicted by the fluid-assisted diffusion law are 10{sup 2} times smaller than those predicted by the power-law creep rheology. Use of East Texas Basin sedimentation rates and power-law creep rheology indicate that differential loading is an effective mechanism to induce perturbations that amplify and evolve to mature salt structures, similar to those observed under natural geological conditions.

Alfaro, R.A.M.

1993-05-01T23:59:59.000Z

116

A continuum theory of thermoelectric bodies and effective properties of thermoelectric composites  

E-Print Network [OSTI]

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.3 A constitutive model for thermoelectric materials . . . . . . . . . . . . . . . . . . . . 6 2 composites. 1 Introduction Thermoelectric (TE) materials directly convert heat into electric energyA continuum theory of thermoelectric bodies and effective properties of thermoelectric composites

Liu, Liping

117

Thermo-mechanical modeling of plasterboard lined partition submitted to fire load.  

E-Print Network [OSTI]

Thermo-mechanical modeling of plasterboard lined partition submitted to fire load. Authors: S.heck@cstb.fr Abstract: An important problem is the development of a thermo-mechanical model of plasterboard lined and the experimental validation of a deterministic and a probabilistic thermo-mechanical model of cardboard

Paris-Sud XI, Université de

118

3.021J / 1.021J / 10.333J / 18.361J / 22.00J Introduction to Modeling and Simulation, Spring 2011  

E-Print Network [OSTI]

This subject provides an introduction to modeling and simulation (IM/S), covering continuum methods, atomistic and molecular simulation (e.g. molecular dynamics) as well as quantum mechanics. These tools play an increasingly ...

Buehler, Markus

119

Mechanical tests for validation of seismic isolation elastomer constitutive models  

SciTech Connect (OSTI)

High damping laminated elastomeric bearings are becoming the preferred device for seismic isolation of large buildings and structures, such as nuclear power plants. The key component of these bearings is a filled natural rubber elastomer. This material exhibits nonlinear behavior within the normal design range. The material damping cannot be classified as either viscous or hysteritic, but it seems to fall somewhere in between. This paper describes a series of tests that can be used to characterize the mechanical response of these elastomers. The tests are designed to determine the behavior of the elastomer in the time scale of the earthquake, which is typically from 30 to 60 seconds. The test results provide data for use in determining the material parameters associated with nonlinear constitutive models. 4 refs.

Kulak, R.F.; Hughes, T.H.

1992-01-01T23:59:59.000Z

120

Mechanical tests for validation of seismic isolation elastomer constitutive models  

SciTech Connect (OSTI)

High damping laminated elastomeric bearings are becoming the preferred device for seismic isolation of large buildings and structures, such as nuclear power plants. The key component of these bearings is a filled natural rubber elastomer. This material exhibits nonlinear behavior within the normal design range. The material damping cannot be classified as either viscous or hysteritic, but it seems to fall somewhere in between. This paper describes a series of tests that can be used to characterize the mechanical response of these elastomers. The tests are designed to determine the behavior of the elastomer in the time scale of the earthquake, which is typically from 30 to 60 seconds. The test results provide data for use in determining the material parameters associated with nonlinear constitutive models. 4 refs.

Kulak, R.F.; Hughes, T.H.

1992-05-01T23:59:59.000Z

Note: This page contains sample records for the topic "mechanics continuum modeling" 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

Continuum states in generalized Swanson models  

E-Print Network [OSTI]

A one-to-one correspondence is known to exist between the spectra of the discrete states of the non Hermitian Swanson-type Hamiltonian $ H = {\\cal{A}}^{\\dagger} {\\cal{A}} + \\alpha {\\cal{A}} ^2 + \\beta {\\cal{A}}^{\\dagger 2} $, ($\\alpha \

A. Sinha; P. Roy

2009-01-07T23:59:59.000Z

122

Microstructural viscoplastic continuum model for asphalt concrete  

E-Print Network [OSTI]

(1984)?????????.? 18 Sides et al. (1985)????????????????? 19 Desai and Zhang (1987)??????????????.. 19 Sousa et al. (1993)????????????????... 20 Strategic Highway Research Program (SHRP) Report A-357 (Lytton et al. 1993)????????????????.. 22 Florea... (1994a, 1994b)???????????????. 23 Sousa and Weissman (1994)????????????... 24 Scarpas et al. (1997a)???????????????.. 25 Lu and Wright (1998)???????????????. 27 viii CHAPTER Page Seibi et al. (2001)????????????????? 27 Huang et al. (2002...

Tashman, Laith

2004-09-30T23:59:59.000Z

123

A Mechanical Model for CCK-Induced Acalculous Gallbladder Pain  

E-Print Network [OSTI]

Associate Editor Peter E. McHugh oversaw the review of this article. Abstract—This study investigates the potential correlation between acalculous biliary pain and mechanical stress during the bile-emptying phase. This study is built on the previously developed mathematical model used to estimate stress in the gallbladder wall during emptying [Li, W. G., X. Y. Luo, et al. Comput. Math. Methods Med. 9(1):27–45, 2008]. Although the total stress was correctly predicted using the previous model, the contribution from patient-specific active stress induced by the cholecystokinin (CCK) test was overlooked. In this article, we evaluate both the active and passive components of pressure in a gallbladder, which undergoes isotonic refilling, isometric contraction and emptying during the infusion of CCK. The pressure is estimated from in vivo ultrasonographical scan measurements of gallbladder emp-tying during CCK tests, assuming that the gallbladder is a thin ellipsoidal membrane. The passive stress is caused by the volume and shape changes during refilling at the gallbladder basal pressure, whereas the active stress arises from the pressure rise during the isometric gallbladder contraction after the CCK infusion. The effect on the stress estimates of the gallbladder to the liver is evaluated to be small by comparing numerical simulations of a gallbladder model with and without a rigid ‘flat top ’ boundary. The model was applied to 51 subjects, and the peak total stress was found to have a strong correlation with the pain stimulated by CCK, as measured by the patient pain score questionnaires. Consistent with our previous study for a smaller sample, it is found that the success rate in predicting of CCK-induced pain is over 75%.

unknown authors

2010-01-01T23:59:59.000Z

124

Journal of the Mechanics and Physics of Solids 52 (2004) 24032430  

E-Print Network [OSTI]

.elsevier.com/locate/jmps A quantum-mechanically informed continuum model of hydrogen embrittlement S. Serebrinskya, E.A. Carterb, M 4 February 2004; accepted 13 February 2004 Abstract We present a model of hydrogen embrittlement for hydrogen-assisted cracking. ? 2004 Elsevier Ltd. All rights reserved. Keywords: Hydrogen embrittlement

Serebrinsky, Santiago A.

125

Relativistic viscoelastic fluid mechanics  

E-Print Network [OSTI]

A detailed study is carried out for the relativistic theory of viscoelasticity which was recently constructed on the basis of Onsager's linear nonequilibrium thermodynamics. After rederiving the theory using a local argument with the entropy current, we show that this theory universally reduces to the standard relativistic Navier-Stokes fluid mechanics in the long time limit. Since effects of elasticity are taken into account, the dynamics at short time scales is modified from that given by the Navier-Stokes equations, so that acausal problems intrinsic to relativistic Navier-Stokes fluids are significantly remedied. We in particular show that the wave equations for the propagation of disturbance around a hydrostatic equilibrium in Minkowski spacetime become symmetric hyperbolic for some range of parameters, so that the model is free of acausality problems. This observation suggests that the relativistic viscoelastic model with such parameters can be regarded as a causal completion of relativistic Navier-Stokes fluid mechanics. By adjusting parameters to various values, this theory can treat a wide variety of materials including elastic materials, Maxwell materials, Kelvin-Voigt materials, and (a nonlinearly generalized version of) simplified Israel-Stewart fluids, and thus we expect the theory to be the most universal description of single-component relativistic continuum materials. We also show that the presence of strains and the corresponding change in temperature are naturally unified through the Tolman law in a generally covariant description of continuum mechanics.

Masafumi Fukuma; Yuho Sakatani

2011-09-01T23:59:59.000Z

126

Unitary dilation models of Turing machines in quantum mechanics  

SciTech Connect (OSTI)

A goal of quantum-mechanical models of the computation process is the description of operators that model changes in the information-bearing degrees of freedom. Iteration of the operators should correspond to steps in the computation, and the final state of halting computations should be stable under iteration. The problem is that operators constructed directly from the process description do not have these properties. In general these operators annihilate the halted state. If information-erasing steps are present, there are additional problems. These problems are illustrated in this paper by consideration of operators for two simple one-step processes and two simple Turing machines. In general the operators are not unitary and, if erasing steps are present, they are not even contraction operators. Various methods of extension or dilation to unitary operators are discussed. Here unitary power dilations are considered as a solution to these problems. It is seen that these dilations automatically provide a good solution to the initial- and final-state problems. For processes with erasing steps, recording steps must be included prior to the dilation, but only for the steps that erase information. Hamiltonians for these processes are also discussed. It is noted that {ital H}, described by exp({minus}{ital iH}{Delta})={ital U}{sup {ital T}}, where {ital U}{sup {ital T}} is a unitary step operator for the process and {Delta} a time interval, has complexity problems. These problems and those noted above are avoided here by the use of the Feynman approach to constructing Hamiltonians directly from the unitary power dilations of the model operators. It is seen that the Hamiltonians so constructed have some interesting properties.

Benioff, P. [Environmental Assessment Division, Building 900, Argonne National Laboratory, Argonne, Illinois 60439 (United States)] [Environmental Assessment Division, Building 900, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

1995-05-01T23:59:59.000Z

127

On models for viscoelastic fluid-like materials that are mechanically incompressible and  

E-Print Network [OSTI]

On models for viscoelastic fluid-like materials that are mechanically incompressible and thermally of the full Navier­Stokes­Fourier system. J. Math. Fluid Mech., 11:274­302, 2009 Mechanically incompressible;Viscoelastic fluids ­ Maxwell model F l lsld µm m Mechanical analogue: Spring ­ energy storage. Dashpot

Cerveny, Vlastislav

128

Deployment Mechanism Design with Behavioral Modeling Based on Pro/Engineer Motion Skeleton  

E-Print Network [OSTI]

kind of motion mechanisms, is often used to stretch out solar panels or antennas in spacecraftDeployment Mechanism Design with Behavioral Modeling Based on Pro/Engineer Motion Skeleton Chao.com.cn Keywords: Deployment mechanism, Motion skeleton, Behavioral modeling, Feasibility analysis Abstract

129

Title: Hydraulic modeling of a mixed water level control hydro-mechanical gate  

E-Print Network [OSTI]

Title: Hydraulic modeling of a mixed water level control hydro-mechanical gate Ludovic Cassan1 Abstract: The article describes the hydraulic functioning of a mixed water level control hydro- mechanical of the model to reproduce the functioning of this complex hydro-mechanical system. CE database Subject headings

Paris-Sud XI, Université de

130

NUMERICAL MODELLING OF AUTOGENOUS HEALING AND RECOVERY OF MECHANICAL PROPERTIES IN ULTRA-HIGH  

E-Print Network [OSTI]

, hydro-chemo- mechanical coupling ABSTRACT Cracks, caused by shrinkage or external loading, reduce. In this study, a hydro-chemo-mechanical model was developed to simulate autogenous healing by further hydration into water was modelled based on micro-mechanical observations. The diffusion process has been simulated

Boyer, Edmond

131

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

132

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

Open Energy Info (EERE)

Mechanical Fluid-Dynamical Model For Ground Movements At Campi Flegrei Caldera Jump to: navigation, search OpenEI Reference LibraryAdd to library Journal Article: A Mechanical...

133

Gas-Kinetic Scheme for Continuum and Near-Continuum Hypersonic Flows  

E-Print Network [OSTI]

Gas-Kinetic Scheme for Continuum and Near-Continuum Hypersonic Flows Wei Liao and Li-Shi Luo Old. The gas-kinetic schemes are validated with simulations of the hypersonic flow past a hollow flare at Mach and simulation of complex hypersonic flows become very challenging for computa- tional fluid dynamics (CFD) [1

Xu, Kun

134

Current-based 4D shape analysis for the mechanical personalization of heart models  

E-Print Network [OSTI]

Current-based 4D shape analysis for the mechanical personalization of heart models Lo¨ic Le Folgoc1. Abstract. Patient-specific models of the heart may lead to better understanding of cardiovascular diseases-mechanical model of the heart, from the kinematics of the endo- and epicardium, is presented in this paper. We use

Paris-Sud XI, Université de

135

A Mechanism-based Model for Deformation Twinning in Polycrystalline...  

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

in Polycrystalline FCC Steel. Abstract: Deformation twinning, a common and important plastic deformation mechanism, is the key contributor to the excellent combination of...

136

Mechanisms and modeling of single-event upset  

SciTech Connect (OSTI)

The basic mechanisms of single-event upset are reviewed, including charge collection in silicon junctions and transistors, and properties of single-event upset in CMOS static random access memory (SRAM) cells. The mechanisms are illustrated through the use of three-dimensional device and circuit simulations. Technology trends and implications for commercial devices are discussed.

Dodd, Paul E.

1998-10-12T23:59:59.000Z

137

N = 4 supersymmetric mechanics: Harmonic superspace as a universal tool of model-building  

SciTech Connect (OSTI)

We overview applications of the harmonic superspace approach in models of N = 4supersymmetric mechanics, with emphasis on some recent results.

Ivanov, E. A., E-mail: eivanov@theor.jinr.ru [Joint Institute for Nuclear Research, Bogoliubov Laboratory of Theoretical Physics (Russian Federation)

2013-08-15T23:59:59.000Z

138

A Mechanical Model for Erosion in Copper Chemical-Mechanical Polishing  

E-Print Network [OSTI]

The Chemical-mechanical polishing (CMP) process is now widely employed in the ultralarge scale integration chip fabrication. Due to the continuous advances in semiconductor fabrication technology and decreasing sub-micron ...

Noh, Kyungyoon

139

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

E-Print Network [OSTI]

of Mechanical Draft Cooling Towers to Assist in the Extraction of their Absolute Temperature from Remote Thermal Abstract Determination of the internal temperature of a mechanical draft cooling tower (MDCT) from remotelyRadiometric Modeling of Mechanical Draft Cooling Towers to Assist in the Extraction

Salvaggio, Carl

140

Thermo-mechanical model of a cardboard-plaster-cardboard composite  

E-Print Network [OSTI]

Thermo-mechanical model of a cardboard-plaster-cardboard composite plate submitted to fire load Mechanics laboratory, Marne-la-Vall´ee University, France Abstract Generally, the standard rules require with experiments in order to predict thermo- mechanical overall partition behaviour. This research is organized

Paris-Sud XI, Université de

Note: This page contains sample records for the topic "mechanics continuum modeling" 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

3D imaging and mechanical modeling of helical buckling in Medicago truncatula plant roots  

E-Print Network [OSTI]

while facing a decline in agricultural soil quality including increased mechanical impe- dance of soil3D imaging and mechanical modeling of helical buckling in Medicago truncatula plant roots Jesse L as a combination of growth-induced mechanical buckling modulated by the growth medium and a simultaneous twisting

Cohen, Itai

142

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

143

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...

San Andres, Luis

2008-01-01T23:59:59.000Z

144

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

145

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

146

Molecular-To-Continuum Fracture Analysis of Thermosetting Polymer/Solid Interfaces  

SciTech Connect (OSTI)

This report focuses on the relationship between the fundamental interactions acting across an interface and macroscopic engineering observable such as fracture toughness or fracture stress. The work encompasses experiment, theory, and simulation. The model experimental system is epoxy on polished silicon. The interfacial interactions between the substrate and the adhesive are varied continuously using self-assembling monolayer. Fracture is studied in two specimen geometries: a napkin-ring torsion geometry and a double cantilevered beam specimen. Analysis and modeling involves molecular dynamics simulations and continuum mechanics calculations. Further insight is gained from analysis of measurements in the literature of direct force measurements for various fundamental interactions. In the napkin-ring test, the data indicate a nonlinear relationship between interface strength and fracture stress. In particular, there is an abrupt transition in fracture stress which corresponds to an adhesive-to-cohesive transition. Such nonlinearity is not present in the MD simulations on the tens-of-nanometer scale, which suggests that the nonlinearity comes from bulk material deformation occurring on much larger length scales. We postulate that the transition occurs when the interface strength becomes comparable to the yield stress of the material. This postulate is supported by variation observed in the fracture stress curve with test temperature. Detailed modeling of the stress within the sample has not yet been attempted. In the DCB test, the relationship between interface strength and fracture toughness is also nonlinear, but the fracture mechanisms are quite different. The fracture does not transition from adhesive to cohesive, but remains adhesive over the entire range of interface strength. This specimen is modeled quantitatively by combining (i) continuum calculations relating fracture toughness to the stress at 90 {angstrom} from the crack tip, and (ii) a relationship from molecular simulations between fracture stress on a {approx} 90 {angstrom} scale and the fraction of surface sites which chemically bond. The resulting relationship between G{sub c} and fraction of bonding sites is then compared to the experimental data. This first order model captures the nonlinearity in the experimentally-determined relationship. A much more extensive comparison is needed (calculations extending to higher G{sub c} values, experimental data extending to lower G{sub c} values) to guide further model development.

KENT,MICHAEL S.; REEDY JR.,EARL DAVID; STEVENS,MARK J.

2000-01-01T23:59:59.000Z

147

CoEvolutionary Incremental Modelling of Robotic Cognitive Mechanisms  

E-Print Network [OSTI]

, trahania}@ics.forth.gr Abstract. Recently, brain models attempt to support cognitive abili- ties work introduces a novel com- putational framework for incremental brain modelling, which aims properly formulated neural agents to represent brain areas. A collaborative coevolutionary method

Trahanias, Panos

148

Grid sensitivity in low Reynolds number hypersonic continuum flows  

SciTech Connect (OSTI)

A computational scheme is presented to solve the unsteady Navier-Stokes equations over a blunt body at high altitude, high Mach number atmospheric reentry flow conditions. This continuum approach is directed to low Reynolds/low density hypersonic flows by accounting for non-zero bulk viscosity effects in near frozen flow conditions. A significant difference from previous studies is the inclusion of the capability to model non-zero bulk viscosity effects. The grid definition for these low Reynolds number, viscous dominated flow fields is especially important in terms of numerical stability and accurate heat transfer solutions. 11 refs., 15 figs.

Rutledge, W.H. (Sandia National Labs., Albuquerque, NM (USA)); Hoffmann, K.A. (Wichita State Univ., KS (USA). Dept. of Aerospace Engineering)

1991-01-01T23:59:59.000Z

149

Computational implementation of the multi-mechanism deformation coupled fracture model for salt  

SciTech Connect (OSTI)

The Multi-Mechanism Deformation (M-D) model for creep in rock salt has been used in three-dimensional computations for the Waste Isolation Pilot Plant (WIPP), a potential waste, repository. These computational studies are relied upon to make key predictions about long-term behavior of the repository. Recently, the M-D model was extended to include creep-induced damage. The extended model, the Multi-Mechanism Deformation Coupled Fracture (MDCF) model, is considerably more complicated than the M-D model and required a different technology from that of the M-D model for a computational implementation.

Koteras, J.R.; Munson, D.E.

1996-05-01T23:59:59.000Z

150

Modeling biofilms with dual extracellular electron transfer mechanisms...  

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

to utilize both simultaneously. The model was applied to Shewanella oneidensis and Geobacter sulfurreducens biofilms using experimentally generated data found the literature....

151

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

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

of mechanistic crack growth and grain contact models for chemically induced subcritical crack growth and pressure solution, with porosity-permeability changes * Conduct...

152

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

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

of mechanistic crack growth and grain contact models for chemically induced subcritical crack growth and pressure solution, with porosity-permeability changes * Conduct...

153

2.4 CONTINUUM MECHANICS (SOLIDS) In this introduction to continuum mechanics we consider the basic equations describing the physical  

E-Print Network [OSTI]

the basic equations describing the physical e#ects created by external forces acting upon solids and fluids

California at Santa Cruz, University of

154

Mechanical modeling of the plastic bonded explosive LX17  

E-Print Network [OSTI]

are ellipsoidal does not match LX17, which has particles with sharp corners. These corners result in stress concentrations that cannot be accounted for with a model of this type. The model to be used in this study is Hashin's composite spheres model... appear to hold only when the volume fraction is small. Hashin proposes that when the volume fraction approaches unity, the roles of the matrix and the inclusions could be swttched (Hashin, 1962). This does not seem reasonable in the case of LX17 since...

Clayton, Kyle Martin

2001-01-01T23:59:59.000Z

155

Cosmology with SKA Radio Continuum Surveys  

E-Print Network [OSTI]

Radio continuum surveys have, in the past, been of restricted use in cosmology. Most studies have concentrated on cross-correlations with the cosmic microwave background to detect the integrated Sachs-Wolfe effect, due to the large sky areas that can be surveyed. As we move into the SKA era, radio continuum surveys will have sufficient source density and sky area to play a major role in cosmology on the largest scales. In this chapter we summarise the experiments that can be carried out with the SKA as it is built up through the coming decade. We show that the SKA can play a unique role in constraining the non-Gaussianity parameter to \\sigma(f_NL) ~ 1, and provide a unique handle on the systematics that inhibit weak lensing surveys. The SKA will also provide the necessary data to test the isotropy of the Universe at redshifts of order unity and thus evaluate the robustness of the cosmological principle.Thus, SKA continuum surveys will turn radio observations into a central probe of cosmological research in th...

Jarvis, Matt J; Blake, Chris; Brown, Michael L; Lindsay, Sam N; Raccanelli, Alvise; Santos, Mario; Schwarz, Dominik

2015-01-01T23:59:59.000Z

156

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

157

A poroplastic model for hygro-chemo-mechanical damage of concrete M. Cuomo & A. Nicolosi  

E-Print Network [OSTI]

and to the prediction of long term response of concrete constructions. The crystalline and porous microstruc- tureA poroplastic model for hygro-chemo-mechanical damage of concrete M. Cuomo & A. Nicolosi Department an analytical model for calcium leaching of concrete due to water. The model is set in the framework

Paris-Sud XI, Université de

158

Vibration Stabilization of a Mechanical Model of a X-Band Linear Collider Final Focus Magnet  

SciTech Connect (OSTI)

The small beam sizes at the interaction point of a X-band linear collider require mechanical stabilization of the final focus magnets at the nanometer level. While passive systems provide adequate performance at many potential sites, active mechanical stabilization is useful if the natural or cultural ground vibration is higher than expected. A mechanical model of a room temperature linear collider final focus magnet has been constructed and actively stabilized with an accelerometer based system.

Frisch, Josef; Chang, Allison; Decker, Valentin; Doyle, Eric; Eriksson, Leif; Hendrickson, Linda; Himel, Thomas; Markiewicz, Thomas; Partridge, Richard; Seryi, Andrei; /SLAC

2006-09-28T23:59:59.000Z

159

A First-Order Mechanical Device to Model Traumatized Craniovascular  

E-Print Network [OSTI]

. This secondary response, in turn, causes cell death and potentially permanent impairment, all of which is further exacerbated by au- toregulatory dysfunction. Recovery is unpredictable and most cognitive improvement comes, but the endpoint for partial or full recovery is unknown. Modeling of injury causation and the resulting

160

Carbon Nanotube Mats and Fibers with Irradiation-Improved Mechanical Characteristics: ATheoretical Model  

E-Print Network [OSTI]

Carbon Nanotube Mats and Fibers with Irradiation-Improved Mechanical Characteristics: ATheoretical model to calculate mechanical characteristics of macroscopic mats and fibers of single-walled carbon-flow technique [4]. The SWNT fibers, which in contrast to most ordinary carbon fibers could be strongly bent with

Krasheninnikov, Arkady V.

Note: This page contains sample records for the topic "mechanics continuum modeling" 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

Multiscale Modeling of TiO2 Nanoparticle Production in Flame Reactors: Effect of Chemical Mechanism  

E-Print Network [OSTI]

Multiscale Modeling of TiO2 Nanoparticle Production in Flame Reactors: Effect of Chemical Mechanism and Engineering Mechanics, The UniVersity of Texas, Austin, Texas 78712 For titanium dioxide (TiO2) nanoparticles, catalysis, energy, and semiconductors. Titanium dioxide (TiO2) nanoparticles are traditionally used

Raman, Venkat

162

Identifying Mathematical Models of the Mechanically Ventilated Lung Using Equation Discovery  

E-Print Network [OSTI]

of the respiratory system. Equation Discovery systems extract mathematical models from observed time series data knowledge. We introduce a modification of this system and apply it to data obtained during mechanical behavior of the respiratory sys- tem under the condition of mechanical ventilation. During the last decades

Kersting, Kristian

163

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

E-Print Network [OSTI]

, 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...

Lee, Sang Hoon

2012-02-14T23:59:59.000Z

164

Mechanical Systems on an almost Kähler model of a Finsler Manifold  

E-Print Network [OSTI]

In this study, we present a new analogue of Euler-Lagrange and Hamilton equations on an almost K\\"ahler model of a Finsler manifold. Also, we give some corollories about the related mechanical systems and equations.

Mehmet Tekkoyun; O?uzhan Çelik

2012-11-06T23:59:59.000Z

165

Magneto-Thermo-Mechanical Coupling, Stability Analysis and Phenomenological Constitutive Modeling of Magnetic Shape Memory Alloys  

E-Print Network [OSTI]

Magnetic shape memory alloys (MSMAs) are a class of active materials that de- form under magnetic and mechanical loading conditions. This work is concerned with the modeling of MSMAs constitutive responses. The hysteretic magneto...

Haldar, Krishnendu 1978-

2012-12-06T23:59:59.000Z

166

Application of the 3-D Hydro-Mechanical Model GEOFRAC in enhanced geothermal systems  

E-Print Network [OSTI]

GEOFRAC is a three-dimensional, geology-based, geometric-mechanical, hierarchical, stochastic model of natural rock fracture systems. The main characteristic of GEOFRAC is that it is based on statistical input representing ...

Vecchiarelli, Alessandra

2013-01-01T23:59:59.000Z

167

Mechanical Engineering Department Seminar Series  

E-Print Network [OSTI]

Mechanical Engineering Department Seminar Series Rational Mechanics of Viral Shells: Is Continuum Theory a Stretch? William S. Klug Associate Professor, Mechanical & Aerospace Engineering, University-assembly. The capacity of these shells to respond structurally and mechanically to physical and chemical stimuli also

Eustice, Ryan

168

Hybrid Particle-Continuum Methods for Nonequilibrium Gas and Plasma Flows  

SciTech Connect (OSTI)

Two different hybrid particle-continuum methods are described for simulation of nonequilibrium gas and plasma dynamics. The first technique, used for nonequilibrium hypersonic gas flows, uses either a continuum description or a particle method throughout a flow domain based on local conditions. This technique is successful in reproducing the results of full particle simulations at a small fraction of the cost. The second method uses a continuum model of the electrons combined with a particle description of the ions and atoms for simulating plasma jets. The physical accuracy of the method is assessed through comparisons with plasma plume measurements obtained in space. These examples illustrate that the complex physical phenomena associated with nonequilibrium conditions can be simulated with physical accuracy and numerical efficiency using such hybrid approaches.

Boyd, Iain D. [Department of Aerospace Engineering, University of Michigan, Ann Arbor, MI (United States)

2011-05-20T23:59:59.000Z

169

Determining the Mechanical Constitutive Properties of Metals as Function of Strain Rate and temperature: A Combined Experimental and Modeling Approach  

SciTech Connect (OSTI)

Development and validation of constitutive models for polycrystalline materials subjected to high strain-rate loading over a range of temperatures are needed to predict the response of engineering materials to in-service type conditions. To account accurately for the complex effects that can occur during extreme and variable loading conditions, requires significant and detailed computational and modeling efforts. These efforts must be integrated fully with precise and targeted experimental measurements that not only verify the predictions of the models, but also provide input about the fundamental processes responsible for the macroscopic response. Achieving this coupling between modeling and experiment is the guiding principle of this program. Specifically, this program seeks to bridge the length scale between discrete dislocation interactions with grain boundaries and continuum models for polycrystalline plasticity. Achieving this goal requires incorporating these complex dislocation-interface interactions into the well-defined behavior of single crystals. Despite the widespread study of metal plasticity, this aspect is not well understood for simple loading conditions, let alone extreme ones. Our experimental approach includes determining the high-strain rate response as a function of strain and temperature with post-mortem characterization of the microstructure, quasi-static testing of pre-deformed material, and direct observation of the dislocation behavior during reloading by using the in situ transmission electron microscope deformation technique. These experiments will provide the basis for development and validation of physically-based constitutive models. One aspect of the program involves the direct observation of specific mechanisms of micro-plasticity, as these indicate the boundary value problem that should be addressed. This focus on the pre-yield region in the quasi-static effort (the elasto-plastic transition) is also a tractable one from an experimental and modeling viewpoint. In addition, our approach will minimize the need to fit model parameters to experimental data to obtain convergence. These are critical steps to reach the primary objective of simulating and modeling material performance under extreme loading conditions. During this project, the following achievements have been obtained: 1. Twins have been observed to act as barriers to dislocation propagation and as sources of and sinks to dislocations. 2. Nucleation of deformation twins in nitrogen strengthened steel is observed to be closely associated with planar slip bands. The appearance of long twins through heavily dislocated microstructures occurs by short twins nucleating at one slip band, propagating through the dislocation-free region, and terminating at the next slip band. This process is repeated throughout the entire grain. 3. A tamped-laser ablation loading technique has been developed to introduce high strain rate, high stress and low strains. 4. Both dislocation slip and twinning are present in high strain-rate deformed zirconium, with the relative contribution of each mode to the deformation depending on the initial texture. 5. In situ IR thermal measurements have been used to show that the majority of plastic work is dissipated as heat even under conditions in which twinning is the dominant deformation mode.

Ian Robertson

2007-04-28T23:59:59.000Z

170

Atomistic Simulation Approach to a Continuum Description of Self-Assembled b-Sheet Filaments  

E-Print Network [OSTI]

be applicable to developing continuum elastic ribbon models of other b-sheet filaments and amyloid fibrils promise as a three-dimensional cell culture matrix or as a tissue engi- neering scaffold. Due to the short). Another important aspect of b-sheet peptide self-assembly is its similarity to amyloid fibrils found

Kamm, Roger D.

171

Probabilistic uncertainty modeling for thermo-mechanical analysis of plasterboard submitted to re load  

E-Print Network [OSTI]

with a probabilistic modeling of the thermo-mechanical behavior of cardboard-plaster-cardboard (CPC) multilayer plates resistance, cardboard-plaster-cardboard multilayer, un- certainties, probabilistic model, experiments presented in the last section. A plasterboard (cardboard-plaster-cardboard (CPC) multiplayer) gives

Paris-Sud XI, Université de

172

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

E-Print Network [OSTI]

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

Münster, Westfälische Wilhelms-Universität

173

Mechanical Degradation Onset of Polyethylene Oxide Used as a Hydrosoluble Model Polymer  

E-Print Network [OSTI]

Mechanical Degradation Onset of Polyethylene Oxide Used as a Hydrosoluble Model Polymer Degradation Onset of Polyethylene Oxide Used as a Hydrosoluble Model Polymer for Enhanced Oil Recovery and for both dilute and semi dilute polyethylene oxide aqueous solutions. It reveals that the exponent k

Boyer, Edmond

174

Department of Mechanical Engineering Spring 2013 CFD Model of a Gypsum Mixer  

E-Print Network [OSTI]

PENNSTATE Department of Mechanical Engineering Spring 2013 CFD Model of a Gypsum Mixer Overview This project, in continuation of last semester's team, intends to create a computational fluid dynamic (CFD) model of the fluid flow inside CertainTeed Gypsum's gypsum mixer. Currently, the mixer outputs locally

Demirel, Melik C.

175

A flow resistance model for assessing the impact of vegetation on flood routing mechanics  

E-Print Network [OSTI]

control in urban storm water runoff [Kirby et al., 2005], and linking tidal hydrodynamic forcing to flow and field studies. The proposed model asymptotically recovers the flow resistance formulation when the waterA flow resistance model for assessing the impact of vegetation on flood routing mechanics Gabriel G

Katul, Gabriel

176

Phenomenological modelling of viscoplasticity Mechanics of Materials Laboratory, Rensselaer Polytechnic Institute, Troy, NY 12180-3590,  

E-Print Network [OSTI]

331 Phenomenological modelling of viscoplasticity E. Krempl Mechanics of Materials Laboratory. - The essentials of phenomenological modeling of metal deformation behavior at small strain are introduced together interpreted from a materials science viewpoint are re-analyzed from a phenomenological point of view

Paris-Sud XI, Université de

177

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

178

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

SciTech Connect (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

179

Hadron resonances with a quark core embedded in the continuum  

SciTech Connect (OSTI)

We investigate the excited baryons and mesons which cannot be described in terms of a simple constituent quark model, such as {Lambda}(1405) and X(3872) as a resonance in a coupled channel hadron-hadron (baryon-meson or meson-meson) scattering with a 'bound state embedded in the continuum' (BSEC). For this purpose, we solve the Lippmann-Schwinger equation including a BSEC in the momentum space. This BSEC is introduced by hand, as a state not originated from a simple baryon-meson or meson-meson system. We assume it comes from the three-quark state or quark-anti quark state and show such a picture can describe the {Lambda}(1405) and X(3872) resonances.

Shimizu, Kiyotaka [Department of Physics, Sophia University, Chiyoda-ku, Tokyo 102-8554 (Japan); Takeuchi, Sachiko [Japan College of Social Work, Kiyose, Tokyo 204-8555 (Japan); Takizawa, Makoto [Showa Pharmaceutical University, Machida, Tokyo 194-8543 (Japan)

2011-05-06T23:59:59.000Z

180

Quasi Sturmian Basis in Two-Electron Continuum Problems  

E-Print Network [OSTI]

A new type of basis functions is proposed to describe a two-electron continuum which arises as a final state in electron-impact ionization and double photoionization of atomic systems. We name these functions, which are calculated in terms of the recently introduced Quasi Sturmian functions, Convoluted Quasi Sturmian functions (CQS). By construction, the CQS functions look asymptotically like a six-dimensional spherical wave. The driven equation describing an $(e, 3e)$ process on helium in the framework of the Temkin-Poet model has been solved numerically using expansions on the basis CQS functions. The convergence behavior of the solution has been examined as the size of the basis has been increased. The calculations show that the convergence rate is significantly improved by introducing a phase factor corresponding the electron-electron interaction into the basis functions. Such a modification of the boundary conditions leads to appreciable change in the magnitude of the solution.

A. S. Zaytsev; L. U. Ancarani; S. A. Zaytsev

2015-03-12T23:59:59.000Z

Note: This page contains sample records for the topic "mechanics continuum modeling" 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

Understanding Creep Mechanisms in Graphite with Experiments, Multiscale Simulations, and Modeling  

SciTech Connect (OSTI)

Disordering mechanisms in graphite have a long history with conflicting viewpoints. Using Raman and x-ray photon spectroscoy, electron microscopy, x-ray diffraction experiments and atomistic modeling and simulations, the current project has developed a fundamental understanding of early-to-late state radiation damage mechanisms in nuclear reactor grade graphite (NBG-18 and PCEA). We show that the topological defects in graphite play an important role under neutron and ion irradiation.

Eapen, Jacob; Murty, Korukonda; Burchell, Timothy

2014-06-02T23:59:59.000Z

182

Mechanics of collective unfolding  

E-Print Network [OSTI]

Mechanically induced unfolding of passive crosslinkers is a fundamental biological phenomenon encountered across the scales from individual macro-molecules to cytoskeletal actin networks. In this paper we study a conceptual model of athermal load-induced unfolding and use a minimalistic setting allowing one to emphasize the role of long-range interactions while maintaining full analytical transparency. Our model can be viewed as a description of a parallel bundle of N bistable units confined between two shared rigid backbones that are loaded through a series spring. We show that the ground states in this model correspond to synchronized, single phase configurations where all individual units are either folded or unfolded. We then study the fine structure of the wiggly energy landscape along the reaction coordinate linking the two coherent states and describing the optimal mechanism of cooperative unfolding. Quite remarkably, our study shows the fundamental difference in the size and structure of the folding-unfolding energy barriers in the hard (fixed displacements) and soft (fixed forces) loading devices which persists in the continuum limit. We argue that both, the synchronization and the non-equivalence of the mechanical responses in hard and soft devices, have their origin in the dominance of long-range interactions. We then apply our minimal model to skeletal muscles where the power-stroke in acto-myosin crossbridges can be interpreted as passive folding. A quantitative analysis of the muscle model shows that the relative rigidity of myosin backbone provides the long-range interaction mechanism allowing the system to effectively synchronize the power-stroke in individual crossbridges even in the presence of thermal fluctuations. In view of the prototypical nature of the proposed model, our general conclusions pertain to a variety of other biological systems where elastic interactions are mediated by effective backbones.

M Caruel; J. -M Allain; L Truskinovsky

2015-01-07T23:59:59.000Z

183

Anisotropic damage modelling of biaxial behaviour and rupture of concrete structures  

E-Print Network [OSTI]

Continuum Damage Mechanics at the Representative Element Volume scale is a relevant tool to deal with largeAnisotropic damage modelling of biaxial behaviour and rupture of concrete structures Ragueneau F with damage induced anisotropy modelling for concrete-like materials. A thermodynamics based constitutive

Boyer, Edmond

184

hal-00878684,version1-30Oct2013 ings, deep reservoirs, confined pillars, etc. An accurate mechanical model is especially  

E-Print Network [OSTI]

mechanical model is especially needed in the analysis of damage, aging and degradation phenomena. Following identified by Ortiz (1985), whose model, based on mixture the- ory and damage mechanics, met most Mechanics, introducing phenomenological damage variables. Although damage is inherently a non isotropic

Boyer, Edmond

185

Lecture notes Introductory fluid mechanics  

E-Print Network [OSTI]

Lecture notes Introductory fluid mechanics Simon J.A. Malham Simon J.A. Malham (17th March 2014 of fluid mechanics and along the way see lots of interesting applications. 2 Fluid flow, the Continuum are generally incompressible--a feature essential to all modern car braking mechanisms. Fluids can be further

Malham, Simon J.A.

186

Continuum Robot Arms Inspired by Cephalopods Ian D. Walkera  

E-Print Network [OSTI]

Continuum Robot Arms Inspired by Cephalopods Ian D. Walkera , Darren M. Dawsona , Tamar Flashb Most robot manipulators feature a structure inspired by that of the human arm, in the sense of being. This paper describes our recent efforts in creating continuous backbone ("continuum") robot arms inspired

Kier, William M.

187

ccsd00001253 The exploration process of inhomogeneous continuum  

E-Print Network [OSTI]

ccsd­00001253 (version 1) : 8 Mar 2004 The exploration process of inhomogeneous continuum random) that arise as weak limits of birthday trees. We give a description of the exploration process, a function de words: Continuum random tree, exchangeable increments, exploration process, L#19;evy process, weak

188

Shell model nuclear matrix elements for competing mechanisms contributing to double beta decay  

SciTech Connect (OSTI)

Recent progress in the shell model approach to the nuclear matrix elements for the double beta decay process are presented. This includes nuclear matrix elements for competing mechanisms to neutrionless double beta decay, a comparison between closure and non-closure approximation for {sup 48}Ca, and an updated shell model analysis of nuclear matrix elements for the double beta decay of {sup 136}Xe.

Horoi, Mihai [Department of Physics, Central Michigan University, Mount Pleasant, Michigan, 48859 (United States)

2013-12-30T23:59:59.000Z

189

Mentorship: The Education-Research Continuum  

SciTech Connect (OSTI)

Mentoring of science students stems naturally from the intertwined link between science education and science research. In fact, the mentoring relationship between a student and a scientist may be thought of analogically as a type of double helix forming the 'DNA' that defines the blueprint for the next generation of scientists. Although this analogy would not meet the rigorous tests commonly used for exploring the natural laws of the universe, the image depicted does capture how creating and sustaining the future science workforce benefits greatly from the continuum between education and research. The path science students pursue from their education careers to their research careers often involves training under an experienced and trusted advisor, i.e., a mentor. For many undergraduate science students, a summer research internship at a DOE National Laboratory is one of the many steps they will take in their Education-Research Continuum. Scientists who choose to be mentors share a commitment for both science education and science research. This commitment is especially evident within the research staff found throughout the Department of Energy's National Laboratories. Research-based internship opportunities within science, technology, engineering and mathematics (STEM) exist at most, if not all, of the Laboratories. Such opportunities for students are helping to create the next generation of highly trained professionals devoted to the task of keeping America at the forefront of scientific innovation. 'The Journal of Undergraduate Research' (JUR) provides undergraduate interns the opportunity to publish their scientific innovation and to share their passion for education and research with fellow students and scientists. The theme of this issue of the JUR (Vol. 8, 2008) is 'Science for All'. Almost 20 years have passed since the American Association for the Advancement of Science published its 1989 report, 'Science for All Americans-Project 2061'. The first recommendation for learning science stated: 'The Nature of Science includes the scientific world view, scientific methods of inquiry, and the nature of the scientific enterprise'. All three elements of the 'Nature of Science' are pivotal aspects of a research internship under the mentorship of an experienced and trusted advisor. In addition to internships for undergraduates, an important ingredient in realizing 'Science for All' is collaboration involving educators and scientists as they engage science students and the public at large to promote science literacy and to develop the next generation of STEM professionals. The DOE National Laboratories, individually and collectively, form an ideal nexus for nurturing these complementary collaborations. My 'Science for All' experiences at Lawrence Livermore National Laboratory (LLNL) over the last 30 years have spanned pre-college, college, and postdoctoral activities, including mentoring of undergraduate students. Early in my mentoring career, I became aware that undergraduates in particular needed help in answering the question 'what path (or paths) will lead to a challenging and rewarding STEM career'? For many, a successful path included a research internship that would result in expanded skills and training in addition to those received from their academic education. These internship skills were helpful whether the student's next Education-Research Continuum decision was graduate school or STEM employment. My experience at LLNL mirrors that of my colleagues at other DOE National Laboratories--internships with a dedicated mentor provide undergraduates with a unique set of skills that can underpin their future options and serve to improve the number, quality, and successful outcomes of students who enter STEM careers. 'Science for All' can also be found in the goals of 'The America COMPETES Act', which call for renewed efforts to increase investments in scientific research and development, strengthen education, and encourage entrepreneurship. Mentoring is an important ingredient in reaching these goals because the succe

Correll, D

2008-05-29T23:59:59.000Z

190

Hydro-Mechanical Coupling in Damaged Porous Media Containing Isolated Cracks or/and Vugs: Model and Computations  

E-Print Network [OSTI]

Hydro-Mechanical Coupling in Damaged Porous Media Containing Isolated Cracks or/and Vugs: Model In this paper we present the development of the macroscopic model describing the hydro-mechanical coupling model in the micro-porous domain saturated by a fluid. In the crack/vug domain the Stokes equation

Paris-Sud XI, Université de

191

MECHANICAL MODELING OF GLASS AND CARBON EPOXY COMPOSITES Barzin Mobasher 1  

E-Print Network [OSTI]

MECHANICAL MODELING OF GLASS AND CARBON EPOXY COMPOSITES Barzin Mobasher 1 , Associate Member ASCE and flexural loading. INTRODUCTION In order to commercially utilize new composite materials in civil of composite laminates. The proposed methodology can be used as a new composite material or used

Mobasher, Barzin

192

Rotary Electrodynamics of a DC Motor: Motor as Mechanical Capacitor Lab 2: Modeling and System Identification  

E-Print Network [OSTI]

). · im is the current through the motor. Because the motor is in series with all other electrical). Because power is conserved, m = Kmim (motor efficiency is actually closer to 69%). Here, Km 0.00767 VRotary Electrodynamics of a DC Motor: Motor as Mechanical Capacitor Lab 2: Modeling and System

193

Virtual Electrodes Mechanisms Predictions with a Current-Lifted Monodomain Model  

E-Print Network [OSTI]

Virtual Electrodes Mechanisms Predictions with a Current-Lifted Monodomain Model Yves Coudi`ere1 cost. The source term is derived from a lifting principle ap- plied to the resolution, and an excitation part, that remains unchanged. Equivalently, we make a lifting of the stimula- tion functions

Boyer, Edmond

194

ES2A7 -Fluid Mechanics Example Classes Model Answers to Example Questions (Set III)  

E-Print Network [OSTI]

ES2A7 - Fluid Mechanics Example Classes Model Answers to Example Questions (Set III) Question 1 10610 40031.8 -- Ã?=Ã?= Ã? Ã? == APN RT d Question 2: Type of Fluid #12;Consider 2 identical vertical tubes are filled with the same height of fluid: A Newtonian fluid is used with tube X whereas a non-Newtonian fluid

Thomas, Peter J.

195

A chemo-mechanical model of lithiation in silicon , Feifei Fan b  

E-Print Network [OSTI]

-mechanical model to investigate the lithiation-induced phase transformation, morphological evolution, stress to the development of new electrode materials that are not only of high energy and high power densities, but also to the high-capacity electrodes, Li insertion/extraction induces large volumetric change and stress inside

Zhu, Ting

196

Hybrid Car-Parrinello/Molecular Mechanics Modelling of Transition Metal Complexes: Structure, Dynamics and Reactivity  

E-Print Network [OSTI]

Hybrid Car-Parrinello/Molecular Mechanics Modelling of Transition Metal Complexes: Structure). We have recently developed a QM/MM extension of a Car-Parrinello scheme [5]. These hybrid Car functional theory embedded in a classical force field description. The power of such a combined Car

Guidoni, Leonardo

197

A Recurrent Neural Multi-Model for Mechanical Systems Dynamics Compensation  

E-Print Network [OSTI]

Mexico D.F., Mexico ** Institute of Information Technologies, 1113 Sofia Abstract: The paper proposed nonlinear mechanical plants with backlash. The parameters and states of the local recurrent neural network of the plant model. For example, N a r e n d r a and P a r t h a s a r a t h y [5], applied FFNN for system

Borissova, Daniela

198

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

199

MODEL OF MECHANISM BEHAVIOR FOR VERIFICATION OF PLC Jos M. Machado  

E-Print Network [OSTI]

MODEL OF MECHANISM BEHAVIOR FOR VERIFICATION OF PLC PROGRAMS José M. Machado University of Minho on formal methods is now available for checking PLC (Programmable Logic Controller) programs. To verify a PLC program, it is necessary to consider a set of properties to prove and one of the most interesting

Paris-Sud XI, Université de

200

Towards Model-Based Estimation of the Cardiac Electro-Mechanical Activity from ECG Signals  

E-Print Network [OSTI]

Towards Model-Based Estimation of the Cardiac Electro-Mechanical Activity from ECG Signals by comparing the actual patient's ECG with computational results and the deformation of the biomechani- cal-to-access measurements on a patient: the ECG (Electrocardiogram), and a time sequence of volumetric ultrasound images

Coudière, Yves

Note: This page contains sample records for the topic "mechanics continuum modeling" 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

Formulations, simulations and evaluations associated with thermo-mechanical models for underground coal gasification  

SciTech Connect (OSTI)

Model formulations and governing equations for the investigation of the thermo-mechanical, consolidation and failure responses associated with UCG are given. Typical results from sample finite element model representations are presented. The examples quoted include the simulation of the transient temperature profiles, thermo-elastic stresses incorporating temperature dependent material properties and fracture responses. The application of the developed models to the evaluation of field experiments is demonstrated by the simulation of the Hoe Creek II experiments. The numerical experiments for different overburden failure thresholds demonstrated the pronounced sensitivity of the predicted cavity shapes with respect to the assumed properties.

Advani, S.H.

1983-01-01T23:59:59.000Z

202

Development of a reduced n-heptane oxidation mechanism for HCCI combustion modeling  

SciTech Connect (OSTI)

Homogeneous charge compression ignition (HCCI) is one of the alternatives to reduce significantly engine emissions for future regulations. This new alternative combustion process is mainly controlled by chemical kinetics in comparison with the conventional combustion in internal combustion engines. The optimization of the engine over the complete engine operation range requires an accurate analysis of the combustion process under all operating conditions; detailed modeling of the HCCI process is an opportunity to realize the engine optimization at lower cost. The combination of CFD computations with detailed chemistry leads to excessive computation times, and is not achievable with current computer capabilities. In this paper, a reduced chemical model for n-heptane is described, in view of its implementation into a CFD simulation code. In the first part, the reduction process to get to the 61-step mechanism is detailed and then the 26-step mechanism is described; this further reduction is carried out under various conditions that include a range of interest in engine applications. The third part is dedicated to extensive validation work in reference to the original detailed mechanism and two reduced mechanisms published in the literature, focusing on the prediction of ignition delay times under constant as well as variable volume conditions. A good and accurate reproduction of both ignition delay times and heat release can be reached with the 26-step model. (author)

Maroteaux, F.; Noel, L. [University Pierre et Marie Curie, INRIA Rocquencourt, B.P. 105, 78153 Le Chesnay Cedex (France)

2006-07-15T23:59:59.000Z

203

Adhesive joint and composites modeling in SIERRA.  

SciTech Connect (OSTI)

Polymers and fiber-reinforced polymer matrix composites play an important role in many Defense Program applications. Recently an advanced nonlinear viscoelastic model for polymers has been developed and incorporated into ADAGIO, Sandia's SIERRA-based quasi-static analysis code. Standard linear elastic shell and continuum models for fiber-reinforced polymer-matrix composites have also been added to ADAGIO. This report details the use of these models for advanced adhesive joint and composites simulations carried out as part of an Advanced Simulation and Computing Advanced Deployment (ASC AD) project. More specifically, the thermo-mechanical response of an adhesive joint when loaded during repeated thermal cycling is simulated, the response of some composite rings under internal pressurization is calculated, and the performance of a composite container subjected to internal pressurization, thermal loading, and distributed mechanical loading is determined. Finally, general comparisons between the continuum and shell element approaches for modeling composites using ADAGIO are given.

Ohashi, Yuki; Brown, Arthur A.; Hammerand, Daniel Carl; Adolf, Douglas Brian; Chambers, Robert S.; Foulk, James W., III (.,; )

2005-11-01T23:59:59.000Z

204

Implementation and Application of SAPRC07 and MCM Mechanisms in the Multi-scale Community Air Quality Model  

E-Print Network [OSTI]

mechanism. In this study, two state-of-the-science photochemical mechanisms, SAPRC07 and Master Chemical Mechanism (MCM) v3.1, were implemented in the Community Multi-scale Air Quality Model (CMAQ) version 4.6 developed by the US EPA to study a high ozone (O...

Li, Jingyi

2012-02-14T23:59:59.000Z

205

Neoclassical Simulation of Tokamak Plasmas using Continuum Gyrokinetc Code TEMPEST  

SciTech Connect (OSTI)

We present gyrokinetic neoclassical simulations of tokamak plasmas with self-consistent electric field for the first time using a fully nonlinear (full-f) continuum code TEMPEST in a circular geometry. A set of gyrokinetic equations are discretized on a five dimensional computational grid in phase space. The present implementation is a Method of Lines approach where the phase-space derivatives are discretized with finite differences and implicit backwards differencing formulas are used to advance the system in time. The fully nonlinear Boltzmann model is used for electrons. The neoclassical electric field is obtained by solving gyrokinetic Poisson equation with self-consistent poloidal variation. With our 4D ({psi}, {theta}, {epsilon}, {mu}) version of the TEMPEST code we compute radial particle and heat flux, the Geodesic-Acoustic Mode (GAM), and the development of neoclassical electric field, which we compare with neoclassical theory with a Lorentz collision model. The present work provides a numerical scheme and a new capability for self-consistently studying important aspects of neoclassical transport and rotations in toroidal magnetic fusion devices.

Xu, X Q

2007-11-09T23:59:59.000Z

206

A STUDY ON THE INCAPACITATION MECHANISM MODEL OF THE JUCHIST AND MARXIST-LENINIST ARTICLES AGAINST THE CORE IMPLEMENTATION MECHANISM MODEL OF THE FUNDAMENTAL RIGHTS ARTICLES IN THE NORTH KOREAN CONSTITUTION: NORTH KOREA'S VIOLATIONS OF FUNDAMENTAL RIGHTS AND INTERNATIONAL HUMAN RIGHTS TREATIES  

E-Print Network [OSTI]

proposed by this dissertation is the incapacitation mechanism model of the Juchist and Marxist-Leninist Articles against the core implementation mechanism model of the Fundamental Rights Articles. The incapacitation mechanism model proves that all...

Jun, Woo-Suk

2014-05-31T23:59:59.000Z

207

Regenerative tree growth: binary self-similar continuum random trees and Poisson-Dirichlet compositions  

E-Print Network [OSTI]

We use a natural ordered extension of the Chinese Restaurant Process to grow a two-parameter family of binary self-similar continuum fragmentation trees. We provide an explicit embedding of Ford's sequence of alpha model trees in the continuum tree which we identified in a previous article as a distributional scaling limit of Ford's trees. In general, the Markov branching trees induced by the two-parameter growth rule are not sampling consistent, so the existence of compact limiting trees cannot be deduced from previous work on the sampling consistent case. We develop here a new approach to establish such limits, based on regenerative interval partitions and the urn-model description of sampling from Dirichlet random distributions.

Pitman, Jim

2008-01-01T23:59:59.000Z

208

Enabling HCCI modeling: The RIOT/CMCS Web Service for Automatic Reaction Mechanism Reduction  

SciTech Connect (OSTI)

New approaches are being developed to facilitate multidisciplinary collaborative research of Homogeneous Charge Compression Ignition (HCCI) combustion processes. In this paper, collaborative sharing of the Range Identification and Optimization Toolkit (RIOT) and related data and models is discussed. RIOT is a developmental approach to reduce the computational complexity of detailed chemical kinetic mechanisms, enabling their use in modeling kinetically-controlled combustion applications such as HCCI. These approaches are being developed and piloted as a part of the Collaboratory for Multiscale Chemical Sciences (CMCS) project. The capabilities of the RIOT code are shared through a portlet in the CMCS portal that allows easy specification and processing of RIOT inputs, remote execution of RIOT, tracking of data pedigree and translation of RIOT outputs (such as the reduced model) to a table view and to the commonly-used CHEMKIN mechanism format. The reduced model is thus immediately ready to be used for more efficient simulation of the chemically reacting system of interest. This effort is motivated by the need to improve computational efficiency in modeling HCCI systems. Preliminary use of the web service to obtain reduced models for this application has yielded computational speedup factors of up to 20 as presented in this paper.

Oluwole, O; Pitz, W J; Schuchardt, K; Rahn, L A; Green, Jr., W H; Leahy, D; Pancerella, C; Sj?berg, M; Dec, J

2005-12-12T23:59:59.000Z

209

Models of stochastic, spatially varying stress in the crust compatible with focal mechanism data Smith and Heaton 1  

E-Print Network [OSTI]

Models of stochastic, spatially varying stress in the crust compatible with focal mechanism data, spatially varying stress in the crust compatible with focal mechanism data ­ Smith and Heaton 3 Introduction ­ Smith and Heaton 1 Models of stochastic, spatially varying stress in the crust compatible with focal

Greer, Julia R.

210

Advances in constitutive modelling of jointed rock hydro mechanical interactions at laboratory scale  

E-Print Network [OSTI]

) INPL-LAEGO-ENSMN, Parc de Saurupt, Ecole des mines, 54000 Nancy, France) (2) INERIS, Parc de Saurupt. The hydro mechanical modelling performed using 3DEC code can be improved from the previous analysis through débit hydraulique dans la fracture. La modélisation hydromécanique réalisée à l'aide du code 3DEC peut

Paris-Sud XI, Université de

211

Inserting Group Variables into Fluid Mechanics  

E-Print Network [OSTI]

A fluid, like a quark-gluon plasma, may possess degrees of freedom indexed by a group variable, which retains its identity even in the fluid/continuum description. Conventional Eulerian fluid mechanics is extended to encompass this possibility.

R. Jackiw

2004-10-28T23:59:59.000Z

212

Continuum Thermodynamics of the SU(N) Gauge Theory  

E-Print Network [OSTI]

The thermodynamics of the deconfined phase of the SU(N) gauge theory is studied. Careful study is made of the approach to the continuum limit. The latent heat of the deconfinement transition is studied, for the theories with 3, 4 and 6 colors. Continuum estimates of various thermodynamic quantities are studied, and the approach to conformality investigated. The bulk thermodynamic quantities at different N are compared, to investigate the validity of 't Hooft scaling at these values of N.

Saumen Datta; Sourendu Gupta

2010-12-30T23:59:59.000Z

213

Relativistic corrections and non-Gaussianity in radio continuum surveys  

SciTech Connect (OSTI)

Forthcoming radio continuum surveys will cover large volumes of the observable Universe and will reach to high redshifts, making them potentially powerful probes of dark energy, modified gravity and non-Gaussianity. We consider the continuum surveys with LOFAR, WSRT and ASKAP, and examples of continuum surveys with the SKA. We extend recent work on these surveys by including redshift space distortions and lensing convergence in the radio source auto-correlation. In addition we compute the general relativistic (GR) corrections to the angular power spectrum. These GR corrections to the standard Newtonian analysis of the power spectrum become significant on scales near and beyond the Hubble scale at each redshift. We find that the GR corrections are at most percent-level in LOFAR, WODAN and EMU surveys, but they can produce O(10%) changes for high enough sensitivity SKA continuum surveys. The signal is however dominated by cosmic variance, and multiple-tracer techniques will be needed to overcome this problem. The GR corrections are suppressed in continuum surveys because of the integration over redshift — we expect that GR corrections will be enhanced for future SKA HI surveys in which the source redshifts will be known. We also provide predictions for the angular power spectra in the case where the primordial perturbations have local non-Gaussianity. We find that non-Gaussianity dominates over GR corrections, and rises above cosmic variance when f{sub NL}?>5 for SKA continuum surveys.

Maartens, Roy [Physics Department, University of the Western Cape, Cape Town 7535 (South Africa); Zhao, Gong-Bo; Bacon, David; Koyama, Kazuya [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 3FX (United Kingdom); Raccanelli, Alvise, E-mail: Roy.Maartens@port.ac.uk, E-mail: Gong-bo.Zhao@port.ac.uk, E-mail: David.Bacon@port.ac.uk, E-mail: Kazuya.Koyama@port.ac.uk, E-mail: alvise@caltech.edu [Jet Propulsion Laboratory, California Institute of Technology, Pasadena CA 91109 (United States)

2013-02-01T23:59:59.000Z

214

Development of a coupled thermo-hydro-mechanical model in discontinuous media for carbon sequestration  

SciTech Connect (OSTI)

Geomechanical alteration of porous media is generally ignored for most shallow subsurface applications, whereas CO2 injection, migration, and trapping in deep saline aquifers will be controlled by coupled multifluid flow, energy transfer, and geomechanical processes. The accurate assessment of the risks associated with potential leakage of injected CO2 and the design of effective injection systems requires that we represent these coupled processes within numerical simulators. The objectives of this study were to develop a coupled thermal-hydro-mechanical model into a single software, and to examine the coupling of thermal, hydrological, and geomechanical processes for simulation of CO2 injection into the subsurface for carbon sequestration. A numerical model is developed to couple nonisothermal multiphase hydrological and geomechanical processes for prediction of multiple interconnected processes for carbon sequestration in deep saline aquifers. The geomechanics model was based on Rigid Body-Spring Model (RBSM), one of the discrete methods to model discontinuous rock system. Poisson’s effect that was often ignored by RBSM was considered in the model. The simulation of large-scale and long-term coupled processes in carbon capture and storage projects requires large memory and computational performance. Global Array Toolkit was used to build the model to permit the high performance simulations of the coupled processes. The model was used to simulate a case study with several scenarios to demonstrate the impacts of considering coupled processes and Poisson’s effect for the prediction of CO2 sequestration.

Fang, Yilin; Nguyen, Ba Nghiep; Carroll, Kenneth C.; Xu, Zhijie; Yabusaki, Steven B.; Scheibe, Timothy D.; Bonneville, Alain

2013-09-12T23:59:59.000Z

215

Multiscale mechanics of macromolecular materials with unfolding domains  

E-Print Network [OSTI]

We propose a general multiscale approach for the mechanical behavior of three-dimensional networks of macromolecules undergoing strain-induced unfolding. Starting from a (statistically based) energetic analysis of the macromolecule unfolding strategy, we obtain a three-dimensional continuum model with variable natural configuration and an energy function analytically deduced from the microscale material parameters. The comparison with the experiments shows the ability of the model to describe the complex behavior, with residual stretches and unfolding effects, observed in different biological materials.

Domenico De Tommasi; Giuseppe Puglisi; Giuseppe Saccomandi

2014-07-14T23:59:59.000Z

216

Modeling, simulation, and testing of the mechanical dynamics of and RF MEMS switch.  

SciTech Connect (OSTI)

Mechanical dynamics can be a determining factor for the switching speed of radio-frequency microelectromechanical systems (RF MEMS) switches. This paper presents the simulation of the mechanical motion of a microswitch under actuation. The switch has a plate suspended by springs. When an electrostatic actuation is applied, the plate moves toward the substrate and closes the switch. Simulations are calculated via a high-fidelity finite element model that couples solid dynamics with electrostatic actuation. It incorporates non-linear coupled dynamics and accommodates fabrication variations. Experimental modal analysis gives results in the frequency domain that verifies the natural frequencies and mode shapes predicted by the model. An effective 1D model is created and used to calculate an actuation voltage waveform that minimizes switch velocity at closure. In the experiment, the switch is actuated with this actuation voltage, and the displacements of the switch at various points are measured using a laser Doppler velocimeter through a microscope. The experiments are repeated on several switches from different batches. The experimental results verify the model.

Sumali, Hartono; Epp, David S.; Massad, Jordan Elias; Dyck, Christopher William; Starr, Michael James

2005-07-01T23:59:59.000Z

217

Mechanical Behaviour of the Short Models of LHC Main Dipole Magnets  

E-Print Network [OSTI]

A series of single and twin aperture 1 metre magnet models has been built and tested in the framework of the R&D program of main superconducting dipole magnets for the Large Hadron Collider project. The se models, designed for a nominal field of 8.3 T at 1.8 K, have been constructed to test the performance of SC coils and to optimise various design options for the full length 15 metre long dipoles. T he models have been extensively equipped with a specially developed mechanical instrumentation, enabling both the control of main assembly parameters - like coil azimuthal and axial pre-load, stress i n the outer shrinking cylinder - and also the monitoring of magnet behaviour during cooling and energising, under the action of electromagnetic forces. The instrumentation used, mainly based on strain gauge transducers, is described and the results of mechanical measurements obtained during power tests of the models are discussed and compared with the design predictions based on Finite Element calc ulations.

Andreyev, N I; Casarejos, E; Kurtyka, T; Rathjen, C; Perini, D; Siegel, N; Tommasini, D; Vanenkov, I

1998-01-01T23:59:59.000Z

218

Quantum mechanical Hamiltonian models of discrete processes that erase their own histories: application to Turing machines  

SciTech Connect (OSTI)

Work done before on the construction of quantum mechanical Hamiltonian models of Turing machines and general descrete processes is extended here to include processes which erase their own histories. The models consist of three phases, the forward process phase in which a map T is iterated and a history of iterations is generated, a copy phase which is activated if and only if T reaches a fix point, and an erase phase which erases the iteration history, undoes the iterations of T and recovers the initial state except for the copy system. A ballast system is used to stop the evolution at the desired state. The general model so constructed is applied to Turing machines. The main changes are that the system undergoing the evolution corresponding to T iterations becomes three systems corresponding to the internal machine, the computation tape, and computation head. Also the copy phase becomes more complex since it is desired that this correspond also to a copying Turing machine.

Benioff, P.A.

1981-01-01T23:59:59.000Z

219

A fully resolved active musculo-mechanical model for esophageal transport  

E-Print Network [OSTI]

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

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

2015-01-01T23:59:59.000Z

220

Mechanical formalism for tissue dynamics  

E-Print Network [OSTI]

The understanding of morphogenesis in living organisms has been renewed by tremendous progress in experimental techniques that provide access to cell-scale, quantitative information both on the shapes of cells within tissues and on the genes being expressed. This information suggests that our understanding of the respective contributions of gene expression and mechanics, and of their crucial entanglement, will soon leap forward. Biomechanics increasingly benefits from models, which assist the design and interpretation of experiments, point out the main ingredients and assumptions, and ultimately lead to predictions. The newly accessible local information thus calls for a reflection on how to select suitable classes of mechanical models. We review both mechanical ingredients suggested by the current knowledge of tissue behaviour, and modelling methods that can help generate a rheological diagram or a constitutive equation. We distinguish cell scale ("intra-cell") and tissue scale ("inter-cell") contributions. We recall the mathematical framework developped for continuum materials and explain how to transform a constitutive equation into a set of partial differential equations amenable to numerical resolution. We show that when plastic behaviour is relevant, the dissipation function formalism appears appropriate to generate constitutive equations; its variational nature facilitates numerical implementation, and we discuss adaptations needed in the case of large deformations. The present article gathers theoretical methods that can readily enhance the significance of the data to be extracted from recent or future high throughput biomechanical experiments.

Sham Tlili; Cyprien Gay; Francois Graner; Philippe Marcq; François Molino; Pierre Saramito

2014-12-23T23:59:59.000Z

Note: This page contains sample records for the topic "mechanics continuum modeling" from the National Library of EnergyBeta (NLEBeta).
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221

Viscoelastic Model for Lung Parenchyma for Multi-Scale Modeling of Respiratory System Phase I: Hypo-Elastic Model for CFD Implementation  

SciTech Connect (OSTI)

An isotropic constitutive model for the parenchyma of lung has been derived from the theory of hypo-elasticity. The intent is to use it to represent the mechanical response of this soft tissue in sophisticated, computational, fluid-dynamic models of the lung. This demands that the continuum model be accurate, yet simple and effcient. An objective algorithm for its numeric integration is provided. The response of the model is determined for several boundary-value problems whose experiments are used for material characterization. The effective elastic, bulk, and shear moduli, and Poisson’s ratio, as tangent functions, are also derived. The model is characterized against published experimental data for lung. A bridge between this continuum model and a dodecahedral model of alveolar geometry is investigated, with preliminary findings being reported.

Freed, Alan D.; Einstein, Daniel R.

2011-04-14T23:59:59.000Z

222

Compensatory mechanisms in fish populations: Literature reviews: Volume 3, A critical review of mathematical models for fish compensation mechanisms: Final report  

SciTech Connect (OSTI)

A critical review of population dynamics models was performed to describe previous models and to recommend approaches for future research on compensation in fish population. The models were first classified into five categories, i.e., theoretical, stock-recruitment, biomass (bioenergetic), population (number), and life cycle functions. Models in each category were then reviewed for their formulations, assumptions, limitations, and performances. A majority of the models were found to have been formulated to calculate parameters that could not be directly measured. Models developed to evaluate entrainment and impingement impacts were often applied without validation against observed data. To advance the scientific understanding of fish compensation mechanisms, future research should include complimentary studies in both model development and empirical observation. Modeling will provide a theoretical framework to integrate individual compensation mechanisms and to relate them to population level responses. Empirical observation, on the other hand, will furnish data to verify the theory. The fish compensation model should use a cohort representation that allows the incorporation of the relationships between life cycle processes and environmental conditions. Growth and mortality of fish in early life stages should be related to weather, hydrology, temperature and food in addition to competition and predation. Environmental data with an inherent stochasticity should be used as input to produce verifiable real time variations in year class strength.

Chen, C.W.

1987-05-01T23:59:59.000Z

223

Statistical mechanics model for the transit free energy of monatomic liquids  

E-Print Network [OSTI]

In applying Vibration-Transit (V-T) theory of liquid dynamics to the thermodynamic properties of monatomic liquids, the point has been reached where an improved model is needed for the small (approx. 10%) transit contribution. Toward this goal, an analysis of the available high-temperature experimental entropy data for elemental liquids was recently completed [D. C. Wallace, E. D. Chisolm, and N. Bock, Phys. Rev. B 79, 051201 (2009)]. This analysis yields a common curve of transit entropy vs. T/\\theta_{tr}, where T is temperature and \\theta_{tr} is a scaling temperature for each element. In the present paper, a statistical mechanics model is constructed for the transit partition function, and is calibrated to the experimental transit entropy curve. The model has two scalar parameters, and captures the temperature scaling of experiment. The calibrated model fits the experimental liquid entropy to high accuracy at all temperatures. With no additional parameters, the model also agrees with both experiment and molecular dynamics for the internal energy vs. T for Na. With the calibrated transit model, V-T theory provides equations subject to ab initio evaluation for thermodynamic properties of monatomic liquids. This will allow the range of applicability of the theory, and its overall accuracy, to be determined. More generally, the hypothesis of V-T theory, which divides the many-atom potential energy valleys into random and symmetric classes, can also be tested for its application beyond monatomic systems.

Duane C. Wallace; Eric D. Chisolm; N. Bock; G. De Lorenzi-Venneri

2010-04-19T23:59:59.000Z

224

Mechanical defradation of Emplacement Drifts at Yucca Mountain- A Modeling Case Study. Part I: Nonlithophysal Rock  

SciTech Connect (OSTI)

This paper outlines rock mechanics investigations associated with mechanical degradation of planned emplacement drifts at Yucca Mountain, which is the designated site for the proposed U.S. high-level nuclear waste repository. The factors leading to drift degradation include stresses from the overburden, stresses induced by the heat released from the emplaced waste, stresses due to seismically related ground motions, and time-dependent strength degradation. The welded tuff emplacement horizon consists of two groups of rock with distinct engineering properties: nonlithophysal units and lithophysal units, based on the relative proportion of lithophysal cavities. The term 'lithophysal' refers to hollow, bubble like cavities in volcanic rock that are surrounded by a porous rim formed by fine-grained alkali feldspar, quartz, and other minerals. Lithophysae are typically a few centimeters to a few decimeters in diameter. Part I of the paper concentrates on the generally hard, strong, and fractured nonlithophysal rock. The degradation behavior of the tunnels in the nonlithophysal rock is controlled by the occurrence of keyblocks. A statistically equivalent fracture model was generated based on extensive underground fracture mapping data from the Exploratory Studies Facility at Yucca Mountain. Three-dimensional distinct block analyses, generated with the fracture patterns randomly selected from the fracture model, were developed with the consideration of in situ, thermal, and seismic loads. In this study, field data, laboratory data, and numerical analyses are well integrated to provide a solution for the unique problem of modeling drift degradation.

M. Lin; D. Kicker; B. Damjanac; M. Board; M. Karakouzian

2006-07-05T23:59:59.000Z

225

Thermal and mechanical denaturation properties of a DNA model with three sites per nucleotide  

E-Print Network [OSTI]

In this paper, we show that the coarse grain model for DNA, which has been proposed recently by Knotts, Rathore, Schwartz and de Pablo (J. Chem. Phys. 126, 084901 (2007)), can be adapted to describe the thermal and mechanical denaturation of long DNA sequences by adjusting slightly the base pairing contribution. The adjusted model leads to (i) critical temperatures for long homogeneous sequences that are in good agreement with both experimental ones and those obtained from statistical models, (ii) a realistic step-like denaturation behaviour for long inhomogeneous sequences, and (iii) critical forces at ambient temperature of the order of 10 pN, close to measured values. The adjusted model furthermore supports the conclusion that the thermal denaturation of long homogeneous sequences corresponds to a first-order phase transition and yields a critical exponent for the critical force equal to sigma=0.70. This model is both geometrically and energetically realistic, in the sense that the helical structure and th...

Florescu, Ana-Maria; 10.1063/1.3626870

2011-01-01T23:59:59.000Z

226

Microstructure and Mechanical Properties of n-irradiated Fe-Cr Model Alloys  

SciTech Connect (OSTI)

High chromium ( 9-12 wt %) ferritic/martensitic steels are candidate structural materials for future fusion reactors and other advanced systems such as accelerator driven systems (ADS). Their use for these applications requires a careful assessment of their mechanical stability under high energy neutron irradiation and in aggressive environments. In particular, the Cr concentration has been shown to be a key parameter to be optimized in order to guarantee the best corrosion and swelling resistance, together with the least embrittlement. In this work, the characterization of the neutron irradiated Fe-Cr model alloys with different Cr % with respect to microstructure and mechanical tests will be presented. The behavior of Fe-Cr alloys have been studied using tensile tests at different temperature range ( from -160 deg. C to 300 deg. C). Irradiation-induced microstructure changes have been studied by TEM for two different irradiation doses at 300 deg. C. The density and the size distribution of the defects induced have been determined. The tensile test results indicate that Cr content affects the hardening behavior of Fe-Cr binary alloys. Hardening mechanisms are discussed in terms of Orowan type of approach by correlating TEM data to the measured irradiation hardening. (authors)

Matijasevic, Milena; Al Mazouzi, Abderrahim [Reactor materials research, SCK-CEN, Mol (Belgium)

2008-07-01T23:59:59.000Z

227

Computational tool for comparison of kinematic mechanisms and commonly used kinematic models  

SciTech Connect (OSTI)

Accurate, reliable, and reproducible methods to measure the movements of human joints have been elusive. Currently, three-dimensional recording methods are used to track the motion of one segment relative to another as the joint moves. Six parameters describe the moving segment`s location and orientation relative to the reference segment: three translations (x, y, and z) and three rotations (yaw, pitch and roll) in the reference frame. The raw data can be difficult to interpret. For this reason, several methods have been developed to measure the motion of human joints and to describe the resulting data. For example, instant helical axes or screw deviation axes (Kinzell et al., 1972), the Joint Coordinate System of Grood and Suntay (1983), and the Euler angle method have been used to describe the movements of bones relative to each other. None of these methods takes into account the physical kinematic mechanism producing the joint motion. More recently, Lupichuk (1995) has developed an algorithm to find, for an arbitrary revolute, the axis` position and orientation in three- dimensional space. Each of these methods has advantages and disadvantages in analyzing joint kinematics. The authors have developed software to provide a means of comparing these methods for arbitrary, single degree of freedom, kinematic mechanisms. Our objective is to demonstrate the software and to show how it can be used to compare the results from the different kinematic models as they are applied to specific kinematic mechanisms.

Hollerbach, K.; Hollister, A.M.; Van Vorhis, R.L.

1997-03-01T23:59:59.000Z

228

On a 2D hydro-mechanical lattice approach for modelling hydraulic fracture  

E-Print Network [OSTI]

A 2D lattice approach to describe hydraulic fracturing is presented. The interaction of fluid pressure and mechanical response is described by Biot's theory. The lattice model is applied to the analysis of a thick-walled cylinder, for which an analytical solution for the elastic response is derived. The numerical results obtained with the lattice model agree well with the analytical solution. Furthermore, the coupled lattice approach is applied to the fracture analysis of the thick-walled cylinder. It is shown that the proposed lattice approach provides results that are independent of the mesh size. Moreover, a strong geometrical size effect on nominal strength is observed which lies between analytically derived lower and upper bounds. This size effect decreases with increasing Biot's coefficient.

Grassl, Peter; Gallipoli, Domenico; Wheeler, Simon J

2014-01-01T23:59:59.000Z

229

A mathematical model for investigating the mechanical behaviour of salt cavities  

SciTech Connect (OSTI)

Cavities in salt are widely used for the storage of natural gas and other substances. When used for the storage of gas, the pressure in the cavity may be reduced to well below the geostatic pressure in the surrounding salt. In these conditions the salt will creep and the shape and size of the cavity will change. The ability to predict these changes, and the effect they may have on the subsurface system is necessary for the efficient operation of the storage. British Gas has developed a mathematical model for investigating this mechanical behaviour of salt cavities. It is based on an extensive programme of experimental work to determine the rheological behaviour of the salt. This paper describes this model and shows how it has been used to solve a number of typical problems encountered in the planning and operation of salt cavities.

Lambert, G.M.S.; Creed, M.R.; Dean, F.; Leigh, M.J.

1988-01-01T23:59:59.000Z

230

A thermo-hydro-mechanical coupled model in local thermal non-equilibrium for fractured HDR reservoir  

E-Print Network [OSTI]

A thermo-hydro-mechanical coupled model in local thermal non-equilibrium for fractured HDR of New South Wales, Sydney 2052, Australia. Abstract The constitutive thermo-hydro-mechanical equations is next applied to simulate circulation tests at the Fenton Hill HDR reservoir. The finer thermo-hydro

Boyer, Edmond

231

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

E-Print Network [OSTI]

with hydrogen embrittlement represents a particu- larly severe degradation mechanism in metallic structures and compressors, despite the fact that they can be extremely susceptible to such hydrogen embrittlementA statistical, physical-based, micro-mechanical model of hydrogen-induced intergranular fracture

Ritchie, Robert

232

A Dual Model-Free Control of Underactuated Mechanical Systems, Application to The Inertia Wheel Inverted Pendulum  

E-Print Network [OSTI]

A Dual Model-Free Control of Underactuated Mechanical Systems, Application to The Inertia Wheel underac- tuated mechanical system: the inertia wheel inverted pendulum. Numerical simulations as well: the ball and beam [9] (where the dynamics of the beam has not been taken into account) and the Planar

Paris-Sud XI, Université de

233

Comparison of QM-Only and QM/MM Models for the Mechanism of Tungsten-Dependent Acetylene Hydratase  

E-Print Network [OSTI]

Comparison of QM-Only and QM/MM Models for the Mechanism of Tungsten-Dependent Acetylene Hydratase study on the formation of vinyl alcohol in the catalytic cycle of tungsten-dependent acetylene hydratase

Liao, Rongzhen

234

Thermal-mechanical modeling of deep borehole disposal of high-level radioactive waste.  

SciTech Connect (OSTI)

Disposal of high-level radioactive waste, including spent nuclear fuel, in deep (3 to 5 km) boreholes is a potential option for safely isolating these wastes from the surface and near-surface environment. Existing drilling technology permits reliable and cost-effective construction of such deep boreholes. Conditions favorable for deep borehole disposal in crystalline basement rocks, including low permeability, high salinity, and geochemically reducing conditions, exist at depth in many locations, particularly in geologically stable continental regions. Isolation of waste depends, in part, on the effectiveness of borehole seals and potential alteration of permeability in the disturbed host rock surrounding the borehole. Coupled thermal-mechanical-hydrologic processes induced by heat from the radioactive waste may impact the disturbed zone near the borehole and borehole wall stability. Numerical simulations of the coupled thermal-mechanical response in the host rock surrounding the borehole were conducted with three software codes or combinations of software codes. Software codes used in the simulations were FEHM, JAS3D, Aria, and Adagio. Simulations were conducted for disposal of spent nuclear fuel assemblies and for the higher heat output of vitrified waste from the reprocessing of fuel. Simulations were also conducted for both isotropic and anisotropic ambient horizontal stress in the host rock. Physical, thermal, and mechanical properties representative of granite host rock at a depth of 4 km were used in the models. Simulation results indicate peak temperature increases at the borehole wall of about 30 C and 180 C for disposal of fuel assemblies and vitrified waste, respectively. Peak temperatures near the borehole occur within about 10 years and decline rapidly within a few hundred years and with distance. The host rock near the borehole is placed under additional compression. Peak mechanical stress is increased by about 15 MPa (above the assumed ambient isotropic stress of 100 MPa) at the borehole wall for the disposal of fuel assemblies and by about 90 MPa for vitrified waste. Simulated peak volumetric strain at the borehole wall is about 420 and 2600 microstrain for the disposal of fuel assemblies and vitrified waste, respectively. Stress and volumetric strain decline rapidly with distance from the borehole and with time. Simulated peak stress at and parallel to the borehole wall for the disposal of vitrified waste with anisotropic ambient horizontal stress is about 440 MPa, which likely exceeds the compressive strength of granite if unconfined by fluid pressure within the borehole. The relatively small simulated displacements and volumetric strain near the borehole suggest that software codes using a nondeforming grid provide an adequate approximation of mechanical deformation in the coupled thermal-mechanical model. Additional modeling is planned to incorporate the effects of hydrologic processes coupled to thermal transport and mechanical deformation in the host rock near the heated borehole.

Arnold, Bill Walter; Hadgu, Teklu

2010-12-01T23:59:59.000Z

235

New findings on the atomistic mechanisms active during mechanical milling of a Fe-Y{sub 2}O{sub 3} model alloy  

SciTech Connect (OSTI)

In order to improve the mechanical properties at elevated temperatures, several types of steels are mechanically alloyed with yttria. The processes that are active during milling differ dependent on the individual powder constituents. Nevertheless, some theories exist which try to describe the mechanism of producing a metastable phase during milling. However, even in the system iron–yttria, the mechanisms taking place during milling are still not well understood. By using the example of a simple iron–yttria model alloy, this paper attempts to elucidate the structure of mechanically milled powder particles and, consequently, to clarify the functionality of mechanical alloying in the last stage of milling. Positron annihilation experiments on milled materials revealed “open” volumes which are enriched in yttria. Electron backscatter diffraction and atom probe tomography as complimentary techniques allowed an identification of these “open” volumes as mainly vacancies, where enrichments of Y and O occur. From these results, it can be concluded that especially vacancies are responsible for producing a metastable phase, whereby yttria is dissolved in pure iron.

Ressel, G.; Primig, S. [Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, A-8700 Leoben (Austria); Christian Doppler Laboratory for Early Stages of Precipitation, Montanuniversität Leoben, A-8700 Leoben (Austria); Parz, P.; Puff, W. [Institute of Materials Physics, Graz University of Technology, A-8010 Graz (Austria); Leitner, H.; Clemens, H. [Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, A-8700 Leoben (Austria)

2014-03-28T23:59:59.000Z

236

THMC Modeling of EGS Reservoirs ?Continuum through Discontinuum...  

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

- Funding received FY09: 0 - Funding committed FY10: 406,466 * Partners - LBNL - AltaRock * Barriers Overleaf Mandatory Overview Slide 3 | US DOE Geothermal Program...

237

Coupling hydrophobicity, dispersion, and electrostatics in continuum solvent models  

E-Print Network [OSTI]

PRL 96, 087802 (2006) PHYSICAL REVIEW LETTERS week ending 3The American Physical Society PRL 96, 087802 (2006) Gv PV vwe apply and the fact PRL 96, 087802 (2006) PHYSICAL REVIEW

Dzubiella, J; Swanson, JMJ; McCammon, J A

2006-01-01T23:59:59.000Z

238

Continuum-based Multiscale Computational Damage Modeling of Cementitous Composites  

E-Print Network [OSTI]

of ? , and its comparison with experimental results by Kupfer et al. (1969) ...... 32 5.1 Evolution of the damage due to the change of the compressive hardening modulus Q ? for: (a) Exponential damage evolution law in Eq. (2.48) and (b) power damage... evolution law in Eq. (2.52) ............... 71 5.2 Evolution of the damage due to the change of the compressive hardening rate constant b? for: (a) Exponential damage evolution law in Eq. (2.48) and (b) power damage evolution law in Eq. (2...

Kim, Sun-Myung

2011-08-08T23:59:59.000Z

239

THMC Modeling of EGS Reservoirs Â… Continuum through Discontinuum  

Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious RankCombustion |Energy Usage »of Energy StrainClient update resolve008Energy 8 -THEShaleTHIS

240

Sandia National Laboratories: Coupling Local to Nonlocal Continuum Models  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administration the1 -the Mid-Infrared0EnergySandia Involves Wind-FarmCool Earth Solar Cool

Note: This page contains sample records for the topic "mechanics continuum modeling" 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

Scientific uncertainties in atmospheric mercury models III: Boundary and initial conditions, model grid resolution, and Hg(II) reduction mechanism  

SciTech Connect (OSTI)

In this study, the model response in terms of simulated mercury concentration and deposition to boundary condition (BC), initial condition (IC), model grid resolution (12 km versus 36 km), and two alternative Hg(II) reduction mechanisms, was investigated. The model response to the change of gaseous elemental mercury (GEM) concentration from 0 to 2 ngm3 in IC/BC is found to be very linear (r240.99) based on the results of sensitivity simulations in July 2001. An increase of 1 ngm3 of GEM in BC resulted in an increase of 0.81 ngm3 in the monthly average of total mercury concentration, and 1270 ngm2 in the monthly total deposition. IC has similar but weaker effects compared to those of BC. An increase of 1 ngm3 of GEM in IC resulted in an increase of 0.14 ngm3 in the monthly average of total mercury concentration, and 250 ngm2 in the monthly total deposition. Varying reactive gaseous mercury (RGM) or particulate mercury (PHg) in BC/IC has much less significant impact. Simulation results at different grid resolutions show good agreement (slope 0.950 1.026, r 0.816 0.973) in mercury concentration, dry deposition, and total deposition. The agreement in wet deposition is somewhat weaker (slope 0.770 0.794, r 0.685 0.892) due to the difference in emission dilution and simulated precipitation that subsequently change reaction rates in the aqueous phase. Replacing the aqueous Hg(II)-HO2 reduction by either RGM reduction by CO (51018cm3 molecule1 s1) or photoreduction of RGM (1105 s1) gives significantly better model agreement with the wet deposition measured by Mercury Deposition Network (MDN). Possible ranges of the reduction rates are estimated based on model sensitivity results. The kinetic estimate requires further verification by laboratory studies.

Lin, Che-Jen [ORNL; Pongprueksa, Pruek [Lamar University; Lindberg, Steven Eric [ORNL; Jang, Carey [U.S. Environmental Protection Agency, Raleigh, North Carolina; Braverman, Thomas [U.S. Environmental Protection Agency, Raleigh, North Carolina; Bullock, Russell O [NOAA; Ho, Thomas [ORNL; Chu, Hsing-Wei [Lamar University

2008-03-01T23:59:59.000Z

242

Preprint UC Davis Math 199930 A continuum approximation for the  

E-Print Network [OSTI]

Preprint UC Davis Math 1999­30 A continuum approximation for the excitations of the (1; 1 and Shannon Starr Department of Mathematics University of California, Davis Davis, CA 95616­8633, USA bolina, with an appropriate scaling, the energy of low­ lying excitations of the (1; 1; : : : ; 1) interface in the d

243

Quantum Communication with Continuum Single-Photon Pulses  

E-Print Network [OSTI]

In this work, we analyze the behavior of continuum single-photon pulses in some quantum communication schemes. In particular, we consider the single-photon interference in a Mach-Zenhder interferometer, the HOM interference and the quantum bit commitment protocol.

F. F. S. Rios; R. V. Ramos

2014-05-15T23:59:59.000Z

244

Optimal Location of a Mobile Sensor Continuum for Environmental Monitoring  

E-Print Network [OSTI]

air pollution monitoring, seismic monitoring, or monitoring of large infrastructures in civil is proposed for the goal of optimal location of a mobile sensor continuum. The monitoring of pollution on a 2D or track distributed environmental phenomena (weather, seismic events, wildfires, air, soil or river

Boyer, Edmond

245

High-resolution terahertz atmospheric water vapor continuum measurements  

E-Print Network [OSTI]

High-resolution terahertz atmospheric water vapor continuum measurements David M. Slocum,* Thomas M such as pollution monitoring and the detection of energetic chemicals using remote sensing over long path lengths through the atmosphere. Although there has been much attention to atmospheric effects over narrow

Massachusetts at Lowell, University of

246

Optical lattices with exceptional points in the continuum  

E-Print Network [OSTI]

The spectral, dynamical and topological properties of physical systems described by non-Hermitian (including $\\mathcal{PT}$-symmetric) Hamiltonians are deeply modified by the appearance of exceptional points and spectral singularities. Here we show that exceptional points in the continuum can arise in non-Hermitian (yet admitting and entirely real-valued energy spectrum) optical lattices with engineered defects. At an exceptional point, the lattice sustains a bound state with an energy embedded in the spectrum of scattered states, similar to the von-Neumann Wigner bound states in the continuum of Hermitian lattices. However, the dynamical and scattering properties of the bound state at an exceptional point are deeply different from those of ordinary von-Neumann Wigner bound states in an Hermitian system. In particular, the bound state in the continuum at an exceptional point is an unstable state that can secularly grow by an infinitesimal perturbation. Such properties are discussed in details for transport of discretized light in a $\\mathcal{PT}$-symmetric array of coupled optical waveguides, which could provide an experimentally accessible system to observe exceptional points in the continuum.

S. Longhi; G. Della Valle

2014-05-30T23:59:59.000Z

247

Cosmological model with decaying vacuum energy law from principles of quantum mechanics  

E-Print Network [OSTI]

We construct the cosmological model to explain the cosmological constant problem. We built the extension of the standard cosmological model $\\Lambda$CDM by consideration of decaying vacuum energy represented by the running cosmological term. From the principles of quantum mechanics one can find that in the long term behavior survival probability of unstable states is a decreasing function of the cosmological time and has the inverse power-like form. This implies that cosmological constant $\\rho_{\\text{vac}} = \\Lambda(t) = \\Lambda_{\\text{bare}} + \\frac{\\alpha}{t^2}$ where $\\Lambda_{\\text{bare}}$ and $\\alpha$ are constants. We investigate the dynamics of this model using dynamical system methods due to a link to the $\\Lambda(H)$ cosmologies. We have found the exact solution for the scale factor as well as the indicators of its variability like the deceleration parameter and the jerk. From the calculation of the jerk we obtain a simple test of the decaying vacuum in the FRW universe. Using astronomical data (SNI...

Szydlowski, Marek

2015-01-01T23:59:59.000Z

248

Integrated modeling and field study of potential mechanisms forinduced seismicity at The Geysers Goethermal Field, California  

SciTech Connect (OSTI)

In this paper, we present progress made in a study aimed atincreasing the understanding of the relative contributions of differentmechanisms that may be causing the seismicity occurring at The Geysersgeothermal field, California. The approach we take is to integrate: (1)coupled reservoir geomechanical numerical modeling, (2) data fromrecently upgraded and expanded NCPA/Calpine/LBNL seismic arrays, and (3)tens of years of archival InSAR data from monthly satellite passes. Wehave conducted a coupled reservoir geomechanical analysis to studypotential mechanisms induced by steam production. Our simulation resultscorroborate co-locations of hypocenter field observations of inducedseismicity and their correlation with steam production as reported in theliterature. Seismic and InSAR data are being collected and processed foruse in constraining the coupled reservoir geomechanicalmodel.

Rutqvist, Jonny; Majer, Ernie; Oldenburg, Curt; Peterson, John; Vasco, Don

2006-06-07T23:59:59.000Z

249

Three-body Interactions Improve the Prediction of Rate and Mechanism in Protein Folding Models  

E-Print Network [OSTI]

Here we study the effects of many-body interactions on rate and mechanism in protein folding, using the results of molecular dynamics simulations on numerous coarse-grained C-alpha-model single-domain proteins. After adding three-body interactions explicitly as a perturbation to a Go-like Hamiltonian with native pair-wise interactions only, we have found 1) a significantly increased correlation with experimental phi-values and folding rates, 2) a stronger correlation of folding rate with contact order, matching the experimental range in rates when the fraction of three-body energy in the native state is ~ 20%, and 3) a considerably larger amount of 3-body energy present in Chymotripsin inhibitor than other proteins studied.

M. R. Ejtehadi; S. P. Avall; S. S. Plotkin

2004-07-14T23:59:59.000Z

250

X-ray continuum emission spectroscopy from hot dense matter at Gbar pressures  

SciTech Connect (OSTI)

We have measured the time-resolved x-ray continuum emission spectrum of ?30 times compressed polystyrene created at stagnation of spherically convergent shock waves within the Gbar fundamental science campaign at the National Ignition Facility. From an exponential emission slope between 7.7 keV and 8.1 keV photon energy and using an emission model which accounts for reabsorption, we infer an average electron temperature of 375 ± 21 eV, which is in good agreement with HYDRA-1D simulations.

Kraus, D., E-mail: dominik.kraus@berkeley.edu; Falcone, R. W. [Department of Physics, University of California, Berkeley, California 94720 (United States); Döppner, T.; Kritcher, A. L.; Bachmann, B.; Collins, G. W.; Hawreliak, J. A.; Landen, O. L.; Ma, T.; Le Pape, S.; Swift, D. C. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Chapman, D. A. [Plasma Physics Group, Radiation Physics Department, AWE plc, Reading RG7 4PR, United Kingdom and Centre for Fusion, Space and Astrophysics, University of Warwick, Coventry CV4 7AL (United Kingdom); Glenzer, S. H. [SLAC National Accelerator Laboratory, Menlo Park, California 94309 (United States); Neumayer, P. [GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt (Germany)

2014-11-15T23:59:59.000Z

251

A Sequential Fluid-mechanic Chemical-kinetic Model of Propane HCCI Combustion  

SciTech Connect (OSTI)

We have developed a methodology for predicting combustion and emissions in a Homogeneous Charge Compression Ignition (HCCI) Engine. This methodology combines a detailed fluid mechanics code with a detailed chemical kinetics code. Instead of directly linking the two codes, which would require an extremely long computational time, the methodology consists of first running the fluid mechanics code to obtain temperature profiles as a function of time. These temperature profiles are then used as input to a multi-zone chemical kinetics code. The advantage of this procedure is that a small number of zones (10) is enough to obtain accurate results. This procedure achieves the benefits of linking the fluid mechanics and the chemical kinetics codes with a great reduction in the computational effort, to a level that can be handled with current computers. The success of this procedure is in large part a consequence of the fact that for much of the compression stroke the chemistry is inactive and thus has little influence on fluid mechanics and heat transfer. Then, when chemistry is active, combustion is rather sudden, leaving little time for interaction between chemistry and fluid mixing and heat transfer. This sequential methodology has been capable of explaining the main characteristics of HCCI combustion that have been observed in experiments. In this paper, we use our model to explore an HCCI engine running on propane. The paper compares experimental and numerical pressure traces, heat release rates, and hydrocarbon and carbon monoxide emissions. The results show an excellent agreement, even in parameters that are difficult to predict, such as chemical heat release rates. Carbon monoxide emissions are reasonably well predicted, even though it is intrinsically difficult to make good predictions of CO emissions in HCCI engines. The paper includes a sensitivity study on the effect of the heat transfer correlation on the results of the analysis. Importantly, the paper also shows a numerical study on how parameters such as swirl rate, crevices and ceramic walls could help in reducing HC and CO emissions from HCCI engines.

Aceves, S M; Flowers, D L; Martinez-Frias, J; Smith, J R; Westbrook, C; Pitz, W; Dibble, R; Wright, J F; Akinyemi, W C; Hessel, R P

2000-11-29T23:59:59.000Z

252

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

SciTech Connect (OSTI)

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

253

The Standard model as a low-energy effective theory: what is triggering the Higgs mechanism?  

E-Print Network [OSTI]

The discovery of the Higgs by ATLAS and CMS at the LHC not only provided the last missing building block of the electroweak Standard Model, the mass of the Higgs has been found to have a very peculiar value about 126 GeV, which is such that vacuum stability is extending up to the Planck scale. This may have much deeper drawback than anticipated so far. The impact on the running of the SM gauge, Yukawa and Higgs couplings up to the Planck scale has been discussed in several articles recently. Here we consider the impact on the running masses and we discuss the role of quadratic divergences within the Standard Model. The change of sign of the coefficient of the quadratically divergent terms showing up at about mu_0 ~ 1.4 x 10^16 GeV may be understood as a first order phase transition restoring the symmetric phase, while its large negative values at lower scales triggers the Higgs mechanism, running parameters evolve in such a way that the symmetry is restored two orders of magnitude before the Planck scale. Thus, the electroweak phase transition takes place at the scale mu_0 and not at the electroweak scale v ~ 250 GeV. The SM Higgs system and its phase transition could play a key role for the inflation of the early universe. Also baryogenesis has to be reconsidered under the aspect that perturbative arguments surprisingly work up to the Planck scale.

Fred Jegerlehner

2014-07-02T23:59:59.000Z

254

Tubular Enhanced Geodesic Active Contours for Continuum Robot Detection using 3D Ultrasound  

E-Print Network [OSTI]

Tubular Enhanced Geodesic Active Contours for Continuum Robot Detection using 3D Ultrasound continuum robots in 3D ultrasound images. The proposed approach combines geodesic active contours Enhanced Geodesic Active Contours (TEGAC), is demonstrated through ex vivo intracardiac experiments

Dupont, Pierre

255

Mechanical Thrombectomy of Iliac Vein Thrombosis in a Pig Model Using the Rotarex and Aspirex Catheters  

SciTech Connect (OSTI)

PurposeTo investigate the efficacy and safety of mechanical thrombectomy for iliac vein thrombosis using Rotarex and Aspirex catheters in a pig model.Materials and MethodsIliac vein thrombosis was induced in six pigs by means of an occlusion-balloon catheter and thrombin injection. The presence of thrombi was verified by digital subtraction angiography (DSA) and computed tomography (CT). Thrombectomy was performed using 6F and 8F Rotarex and 6F, 8F, and 10F Aspirex catheters (Straub Medical AG, Wangs, Switzerland). After intervention, DSA and CT were repeated to evaluate the efficacy of mechanical thrombectomy and to exclude local complications. In addition, pulmonary CT was performed to rule out pulmonary embolism. Finally, all pigs were killed, and iliac veins were dissected to perform macroscopic and histological examination.ResultsThrombus induction was successfully achieved in all animals as verified by DSA and CT. Subsequent thrombectomy lead to incomplete recanalization of the iliac veins with residual thrombi in all cases. However, the use of the 6F and 8F Rotarex catheters caused vessel perforation and retroperitoneal hemorrhage in all cases. Application of the Aspirex device caused one small transmural perforation in a vessel treated with a 10F Aspirex catheter, and this was only seen microscopically. Pulmonary embolism was detected in one animal treated with the Rotarex catheters, whereas no pulmonary emboli were seen in animals treated with the Aspirex catheters.ConclusionThe Aspirex catheter allowed subtotal and safe recanalization of iliac vein thrombosis. In contrast, the use of the Rotarex catheter caused macroscopically obvious vessel perforations in all cases.

Minko, P., E-mail: peterminko@yahoo.com; Bücker, A. [University Hospital Homburg/Saar, Department of Diagnostic and Interventional Radiology (Germany); Laschke, M.; Menger, M. [University Hospital Homburg/Saar, Institute of Clinical and Experimental Surgery (Germany); Bohle, R. [University Hospital Homburg/Saar, Department of Pathology (Germany); Katoh, M. [University Hospital Homburg/Saar, Department of Diagnostic and Interventional Radiology (Germany)

2013-06-08T23:59:59.000Z

256

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

257

Modeling and implementation of solder-activated joints for single actuator, centimeter-scale robotic mechanisms  

E-Print Network [OSTI]

This thesis explains when, and why, solder-based phase change materials (PCMs) are best-suited as a means to modify a robotic mechanism's kinematic and elastomechanic behavior. The preceding refers to mechanisms that possess ...

Telleria, Maria J

2010-01-01T23:59:59.000Z

258

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

E-Print Network [OSTI]

adhesion in microelectromechanical systems. ASME J. Tribol.microtribology for microelectromechanical systems. Wear 200,forces in microelectromechanical systems: mechanisms,

Song, Zhichao

2012-01-01T23:59:59.000Z

259

The ramifications of diffusive volume transport in classical fluid mechanics  

E-Print Network [OSTI]

The thesis that follows consists of a collection of work supporting and extending a novel reformulation of fluid mechanics, wherein the linear momentum per unit mass in a fluid continuum, m, is supposed equal to the volume ...

Bielenberg, James R. (James Ronald), 1976-

2004-01-01T23:59:59.000Z

260

Vortex topology and the continuum limit of lattice gauge theories  

E-Print Network [OSTI]

We study the stability of Z_2 topological vortex excitations in d+1 dimensional SU(2) Yang-Mills theory on the lattice at T=0. This is found to depend on d and on the coupling considered. We discuss the connection with lattice artifacts causing bulk transitions in the beta_A-beta_F plane and draw some conclusions regarding the continuum limit of the theory.

G. Burgio

2007-10-02T23:59:59.000Z

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


261

NREL Leads Energy Systems Integration, Continuum Magazine: Issue 4 (Book)  

SciTech Connect (OSTI)

Continuum Magazine showcases NREL's latest and most impactful clean energy innovations. This issue, 'NREL Leads Energy Systems Integration' explores the discipline of energy systems integration, in particular the role of the laboratory's new, one-of-a-kind Energy System Integration Facility. NREL scientists, engineers, and analysts deeply understand the fundamental science and technologies underpinning major energy producing and consuming systems, as well as the transmission infrastructure and communications and data networks required to integrate energy systems at all scales.

Not Available

2013-04-01T23:59:59.000Z

262

Linear elastic fracture mechanics in anisotropic solids : application to fluid-driven crack propagation  

E-Print Network [OSTI]

Fracture mechanics is a field of continuum mechanics with the objective to predict how cracks initiate and propagate in solids. It has a wide domain of application. While aerospace engineers want to make sure a defect in ...

Laubie, Hadrien Hyacinthe

2013-01-01T23:59:59.000Z

263

To appear as: "Berkeley on Ordinary Objects," The Continuum Companion to Berkeley, eds. Bertil Belfrage and Dick Brook (New York: Continuum Press) (approx. 5,000 words) in  

E-Print Network [OSTI]

. Bertil Belfrage and Dick Brook (New York: Continuum Press) (approx. 5,000 words) in preparation (draft objects ­ tables and chairs, cats and dogs ­ fit into Berkeley's metaphysics

McDonough, Jeffrey

264

Sierra/solid mechanics 4.22 user's guide.  

SciTech Connect (OSTI)

Sierra/SolidMechanics (Sierra/SM) is a Lagrangian, three-dimensional code for the analysis of solids and structures. It provides capabilities for explicit dynamic and implicit quasistatic and dynamic analyses. The explicit dynamics capabilities allow for the efficient and robust solution of models subjected to large, suddenly applied loads. For implicit problems, Sierra/SM uses a multi-level iterative solver, which enables it to effectively solve problems with large deformations, nonlinear material behavior, and contact. Sierra/SM has a versatile library of continuum and structural elements, and an extensive library of material models. The code is written for parallel computing environments, and it allows for scalable solutions of very large problems for both implicit and explicit analyses. It is built on the SIERRA Framework, which allows for coupling with other SIERRA mechanics codes. This document describes the functionality and input structure for Sierra/SM.

Thomas, Jesse David

2011-10-01T23:59:59.000Z

265

Mechanical Engineering ME 3720 FLUID MECHANICS  

E-Print Network [OSTI]

Mechanical Engineering ME 3720 FLUID MECHANICS Pre-requisite: ME 2330 Co-requisite: ME 3210) to develop an understanding of the physical mechanisms and the mathematical models of fluid mechanics of fluid mechanics problems in engineering practice. The basic principles of fluid mechanics

Panchagnula, Mahesh

266

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

SciTech Connect (OSTI)

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

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

1981-01-01T23:59:59.000Z

267

CGILS: Results from the First Phase of an International Project to Understand the Physical Mechanisms of Low Cloud Feedbacks in Single Column Models  

SciTech Connect (OSTI)

Large Eddy Models (LES) and Single Column Models (SCM) are used in a surrogate climate change 101 to investigate the physical mechanism of low cloud feedbacks in climate models. Enhanced surface-102 driven boundary layer turbulence and shallow convection in a warmer climate are found to be 103 dominant mechanisms in SCMs.

Zhang, Minghua; Bretherton, Christopher S.; Blossey, Peter; Austin, Phillip A.; Bacmeister, J.; Bony, Sandrine; Brient, Florent; Cheedela, Suvarchal K.; Cheng, Anning; Del Genio, Anthony D.; De Roode, Stephan R.; Endo , Satoshi; Franklin, Charmaine N.; Golaz, Jean-Christophe; Hannay, Cecile; Heus, Thijs; Isotta, Francesco A.; Jean-Louis, Dufresne; Kang, In-Sik; Kawai, Hideaki; Koehler, M.; Larson, Vincent E.; Liu, Yangang; Lock, Adrian; Lohmann, U.; Khairoutdinov, Marat; Molod, Andrea M.; Neggers, Roel; Rasch, Philip J.; Sandu, Irina; Senkbeil, Ryan; Siebesma, A. P.; Siegenthaler-Le Drian, Colombe; Stevens, Bjorn; Suarez, Max; Xu, Kuan-Man; Von Salzen, Knut; Webb, Mark; Wolf, Audrey; Zhao, M.

2013-12-26T23:59:59.000Z

268

Models of Stochastic, Spatially Varying Stress in the Crust Compatible with Focal-Mechanism Data, and How Stress Inversions  

E-Print Network [OSTI]

Models of Stochastic, Spatially Varying Stress in the Crust Compatible with Focal-Mechanism Data. Heaton Abstract Evidence suggests that slip in earthquakes and the resultant stress changes are spatially heterogeneous. If crustal stress from past earthquakes is spatially hetero- geneous, then earthquake focal

Greer, Julia R.

269

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

E-Print Network [OSTI]

of remote thermal imagery. Knowledge of the temperature of the cooling towers is necessary for inputRadiometric Modeling of Mechanical Draft Cooling Towers to Assist in the Extraction of their Absolute Temperature from Remote Thermal Imagery Matthew Montanaroa, Carl Salvaggioa, Scott D. Browna

Salvaggio, Carl

270

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

E-Print Network [OSTI]

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

Borja, Ronaldo I.

271

Modelling of reactive gas transport in unsaturated soil. A coupled thermo-hydro-chemical-mechanical approach.  

E-Print Network [OSTI]

??This thesis presents the development of a reactive gas transport equation under coupled framework of thermal, hydraulic, chemical and mechanical (THCM) behaviour of variably saturated… (more)

Masum, Shakil Al

2012-01-01T23:59:59.000Z

272

Microstructure and Mechanical Property Studies on Neutron-Irradiated Ferritic Fe-Cr Model Alloys  

SciTech Connect (OSTI)

Model Fe, Fe-10Cr and Fe-14Cr alloys were irradiated in Advanced Test Reactor at 300°C and 450°C to target doses of 0.01, 0.1 and 1 dpa. The microstructure and the mechanical property of irradiated specimens were investigated using TEM, APT and hardness measurements. The irradiation-induced hardening was consistent with the observed microstructures. For lower doses of 0.01 and 0.1 dpa, the formation of dislocation loops was the primarily contributor to the hardening; no a’ precipitates of resolvable sizes were observed. By 1 dpa, additional increase in hardening were attributed to the formation of a high density of 1-2 nm a' precipitates. In Fe, the hardness increased less as a function of irradiation dose compared to Fe-Cr alloys because of the lack of a' precipitation and differences in loop structures. Three single-parameter effects have been studied: the Cr content, the irradiation temperature and the grain size. The addition of Cr reduced the mobility of both ½<111> and <100> dislocation loops, leading to a smaller loop size and higher loop density. Also, the Cr contents were positively correlated to the density of a' precipitates, but were less relevant to the precipitate size. Higher irradiation temperature of 450°C resulted in a preferential production of the immobile <100> loops over the mobile ½<111> loops (ex. a ratio of 8:1 in Fe-10Cr irradiated 450°C to 0.01 dpa). At lower temperature of 300°C, heterogeneous formation of dislocation loops at the vicinity of line dislocations frequently. In Fe, the development of dislocation loops was suppressed (compared to Fe-Cr alloys) due to a combination of smaller grain size, high initial dislocation density and high defect mobility.

Jian Gan; Maria Okuniewski; Wei-Ying Chen; Yinbin Miao; Carolyn A. Tomchik; James F. Stubbins; Y. Q. Wu; Stu A. Maloy

2014-06-01T23:59:59.000Z

273

Emission lines and optical continuum in low-luminosity radio galaxies  

E-Print Network [OSTI]

We present spectroscopic observations of a complete sub-sample of 13 low-luminosity radio galaxies selected from the 2Jy sample. The underlying continuum in these sources is carefully modelled in order to make a much-needed comparison between the emission line and continuum properties of FRIs with those of other classes of radio sources. We find that 5 galaxies in the sample show a measurable UV excess: 2 of the these sources are BL Lacs and in the remaining 3 galaxies we argue that the most likely contributor to the UV excess is a young stellar component. Excluding the BL Lacs, we therefore find that \\~30% of the sample show evidence for young stars, which is similar to the results obtained for higher luminosity samples. We compare our results with far-infrared measurements in order to investigate the far-infrared-starburst link. The nature of the optical-radio correlations is investigated in light of this new available data and, in contrast to previous studies, we find that the FRI sources follow the correlations with a similar slope to that found for the FRIIs. Finally, we compare the luminosity of the emission lines in the FRI and BL Lac sources and find a significant difference in the [OIII] line luminosities of the two groups. Our results are discussed in the context of the unified schemes.

K. A. Wills; R. Morganti; C. N. Tadhunter; T. G. Robinson; M. Villar-Martin

2003-10-09T23:59:59.000Z

274

Theory of continuum damping of toroidal Alfven Eigenmodes in finite-[beta] tokamaks  

SciTech Connect (OSTI)

We have formulated a general theoretical approach for analyzing two-dimensional structures of high-n Toroidal Alfven Eigenmodes (TAE) in large aspect-ratio, finite-[beta] tokamaks. Here, n is the toroidal wave number and [beta] is the ratio between plasma and magnetic pressures. The present approach generalizes the standard ballooning-mode formalism and is capable of treating eigenmodes with extended global radial structures as well as finite coupling between discrete and continuous spectra. Employing the well-known (s,[alpha]) model equilibrium and assuming a linear equilibrium profile, we have applied the present approach and calculated the corresponding resonant continuum damping rate of TAE modes. Here, s and [alpha] denote, respectively, the strengths of magnetic shear and pressure gradients. In particular, it is found that there exists a critical [alpha][sub c](s), such that, as [alpha] [yields] [alpha][sub c], the continuum damping rate is significantly enhanced and, thus, could suppress the potential TAE instability.

Zonca, F.; Chen, Liu.

1993-05-01T23:59:59.000Z

275

Theory of continuum damping of toroidal Alfven Eigenmodes in finite-{beta} tokamaks  

SciTech Connect (OSTI)

We have formulated a general theoretical approach for analyzing two-dimensional structures of high-n Toroidal Alfven Eigenmodes (TAE) in large aspect-ratio, finite-{beta} tokamaks. Here, n is the toroidal wave number and {beta} is the ratio between plasma and magnetic pressures. The present approach generalizes the standard ballooning-mode formalism and is capable of treating eigenmodes with extended global radial structures as well as finite coupling between discrete and continuous spectra. Employing the well-known (s,{alpha}) model equilibrium and assuming a linear equilibrium profile, we have applied the present approach and calculated the corresponding resonant continuum damping rate of TAE modes. Here, s and {alpha} denote, respectively, the strengths of magnetic shear and pressure gradients. In particular, it is found that there exists a critical {alpha}{sub c}(s), such that, as {alpha} {yields} {alpha}{sub c}, the continuum damping rate is significantly enhanced and, thus, could suppress the potential TAE instability.

Zonca, F.; Chen, Liu

1993-05-01T23:59:59.000Z

276

Negative-parity {Lambda}{sub Q} baryons in the baryon-meson continuum  

SciTech Connect (OSTI)

The negative-parity charmed baryons are investigated by employing the quark model as well as the effective baryon meson model with a bound state embedded in the continuum. Especially the mass difference between the J{sup P} 1/2{sup -} and 3/2{sup -}{Lambda}{sub c}{sup +} baryons is discussed. The observed value of this mass splitting is almost the same as that of {Xi}{sub c}, about 30 MeV. It is found that most of this splitting can be reproduced by assuming a simple qqQ configuration. The coupling to the baryon-meson scattering state may enlarge the splitting as it does for the {Lambda}(1405)(1/2{sup -}) and {Lambda}(1520)(3/2{sup -}) case. We investigate this coupling effect and find that with an appropriately modified coupling or the pole energy, the peak can be reproduced.

Takeuchi, Sachiko [Japan College of Social Work, Kiyose, Tokyo, 204-8555 (Japan); Takizawa, Makoto [Showa Pharmaceutical University, Machida, Tokyo, 194-8543 (Japan); Shimizu, Kiyotaka [Department of Physics, Sophia University, Chiyoda-ku, Tokyo 102-8554 (Japan)

2011-10-21T23:59:59.000Z

277

On the ionizing continuum in active galactic nuclei: clues from ISO  

E-Print Network [OSTI]

The ISO coronal line spectrum of the brightest Seyfert galaxies from the CfA sample is presented and modeled. ISO observations of [O IV] 25.9 $\\mu$, [Ne V] 14.3 $\\mu$, [Mg VIII] 3.02 $\\mu$ and [Si IX] 2.58 $\\mu$ lines are presented; their relationship with the soft part of the ionizing spectrum from 50 to 300 eV is investigated. Pure photoionization models reproduce the line ratios, setting ranges for the ionization parameter and the optical depth of the emitting clouds. On the basis of the available data alone it is not possible to distinguish between a power-law or a blackbody distribution as the intrinsic shape of the UV ionizing spectrum. However, for the brightest Seyferts analyzed, namely, NGC 1068, Circinus and NGC 4151, a black-body UV continuum is favored.

M. Almudena Prieto; Sueli M. Viegas

1999-11-15T23:59:59.000Z

278

Mechanism-based constitutive modeling of L1? single-crystal plasticity  

E-Print Network [OSTI]

Ni3Al, an L12 structure intermetallic crystal, is the basic composition of the [gamma]' precipitates in nickel-based superalloys and is a major strengthening mechanism contributing to the superalloys' outstanding ...

Yin, Yuan, 1977-

2006-01-01T23:59:59.000Z

279

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...

Rawal, Chakra

2012-07-16T23:59:59.000Z

280

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

Note: This page contains sample records for the topic "mechanics continuum modeling" 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

Assessment and preliminary model development of shape memory polymers mechanical counter pressure space suits  

E-Print Network [OSTI]

This thesis seeks to assess the viability of a space qualified shape memory polymer (SMP) mechanical counter pressure (MCP) suit. A key development objective identified by the International Space Exploration Coordination ...

Wee, Brian (Brian J.)

2013-01-01T23:59:59.000Z

282

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

283

Calculation of Solvation Free Energies of Charged Solutes Using Mixed Cluster/Continuum Vyacheslav S. Bryantsev, Mamadou S. Diallo,, and William A. Goddard III*,  

E-Print Network [OSTI]

Calculation of Solvation Free Energies of Charged Solutes Using Mixed Cluster/Continuum Models methodologies make systematic errors in the computed free energies because of the incorrect accounting consideration. We analyze two different thermodynamic cycles for calculating the solvation free energies

Goddard III, William A.

284

A study on aerodynamics and mechanisms of elementary morphing models for flapping wing in bat forward flight  

E-Print Network [OSTI]

The large active wing deformation is a significant way to generate high aerodynamic forces required in bat flapping flight. Besides the twisting, the elementary morphing models of a bat wing are proposed, such as wing-bending in the spanwise direction, wing-cambering in the chordwise direction, and wing area-changing. A plate of aspect ratio 3 is used to model a bat wing and a three dimensional unsteady panel method is applied to predict the aerodynamic forces. It is found that the cambering model has a great positive influence on the lift, followed by area-changing model and then the bending model. The further study indicates that the vortex control is a main mechanism to produce high aerodynamic forces, and the mechanisms for the aerodynamic force enhancement are the asymmetry of the cambered wing and the amplifier effects of wing area-changing and wing bending. The lift and thrust are mainly generated during the downstroke and almost negligible forces during the upstroke by the integrated morphing model-wi...

Zi-Wu, Guan

2014-01-01T23:59:59.000Z

285

Wave-packet continuum discretization for quantum scattering  

E-Print Network [OSTI]

A general approach to a solution of few- and many-body scattering problems based on a continuum-discretization procedure is described in detail. The complete discretization of continuous spectrum is realized using stationary wave packets which are the normalized states constructed from exact non-normalized continuum states. Projecting the wave functions and all scattering operators like $t$-matrix, resolvent, etc. on such a wave-packet basis results in a formulation of quantum scattering problem entirely in terms of discrete elements and linear equations with regular matrices. It is demonstrated that there is a close relation between the above stationary wave packets and pseudostates which are employed often to approximate the scattering states with a finite $L_2$ basis. Such a fully discrete treatment of complicated few- and many-body scattering problems leads to significant simplification of their practical solution. Also we get finite-dimensional approximations for complicated operators like effective interactions between composite particles constructed via the Feshbach-type projection formalism. As illustrations to this general approach we consider several important particular problems including multichannel scattering and scattering in the three-nucleon system within the Faddeev framework.

O. A. Rubtsova; V. I. Kukulin; V. N. Pomerantsev

2015-01-15T23:59:59.000Z

286

Spectral Evolution of the Continuum and Disc Line in Dipping in GRO J1655-40  

E-Print Network [OSTI]

The discovery is reported of emission features in the X-ray spectrum of GRO J1655-40 obtained using Rossi-XTE on 1997, Feb 26. The features have been fitted firstly by two Gaussian lines, which in four spectra have average energies of 5.85+/-0.08 keV and 7.32+/-0.13 keV, strongly suggestive that these are the red- and blueshifted wings of an iron disc line from material with velocity ~0.33 c. The blue wing is apparently less bright than expected for a disc line subject to Doppler boosting, however, known absorption in the spectrum of GRO J1655-40 at energies between ~7 and 8 keV can reduce the apparent brightness of the blue wing. The spectra have also been fitted well using the full relativistic disc line model of Laor, plus an absorption line. This gives a restframe energy between 6.4 and 6.8 keV indicating that the line is from highly ionized iron K_alpha. The Laor model also shows that the line originates at radii extending from ~10 Schwarzschild radii (r_S) outwards. The line is direct evidence for the black hole nature of the compact object. The continuum is well described by dominant disc blackbody emission plus Comptonized emission. During dipping, spectral evolution is well modelled by allowing progressive covering of the disc blackbody and simple absorption of the Comptonized emission showing that the thermal emission is more extended. Acceptable fits are only obtained by including the disc line in the covering term, indicating that it originates in the same inner disc region as the thermal continuum. Dip ingress times and durations are used to provide the radius of the disc blackbody emitter as 170-370 r_S, and the radius of the absorber.

M. Balucinska-Church

2001-01-22T23:59:59.000Z

287

Mechanisms of aerosol-forced AMOC variability in a state of the art climate model  

E-Print Network [OSTI]

with a new state-of-the-art Earth system model. Anthropogenic aerosols have previously been highlighted anthropogenic aerosols force a strengthening of the AMOC by up to 20% in our state-of-the-art Earth system model

288

Planck early results: Spectral energy distributions and radio continuum spectra of northern extragalactic radio sources  

E-Print Network [OSTI]

Spectral energy distributions (SEDs) and radio continuum spectra are presented for a northern sample of 104 extragalactic radio sources, based on the Planck Early Release Compact Source Catalog (ERCSC) and simultaneous multifrequency data. The nine Planck frequencies, from 30 to 857 GHz, are complemented by a set of simultaneous observations ranging from radio to gamma-rays. This is the first extensive frequency coverage in the radio and millimetre domains for an essentially complete sample of extragalactic radio sources, and it shows how the individual shocks, each in their own phase of development, moving in the relativistic jet, shape the radio spectra. The SEDs presented in this paper were fitted with second and third degree polynomials to estimate the frequencies of the synchrotron and inverse Compton (IC) peaks, and the spectral indices of low and high frequency radio data, including the Planck ERCSC data, were calculated. SED modelling methods are discussed, with an emphasis on proper, physical modelli...

Aatrokoski, J; Aghanim, N; Aller, H D; Aller, M F; Angelakis, E; Arnaud, M; Ashdown, M; Aumont, J; Baccigalupi, C; Balbi, A; Banday, A J; Barreiro, R B; Bartlett, J G; Battaner, E; Benabed, K; Benoît, A; Berdyugin, A; Bernard, J -P; Bersanelli, M; Bhatia, R; Bonaldi, A; Bonavera, L; Bond, J R; Borrill, J; Bouchet, F R; Bucher, M; Burigana, C; Burrows, D N; Cabella, P; Capalbi, M; Cappellini, B; Cardoso, J -F; Catalano, A; Cavazzuti, E; Cayón, L; Challinor, A; Chamballu, A; Chary, R -R; Chiang, L -Y; Christensen, P R; Clements, D L; Colafrancesco, S; Colombi, S; Couchot, F; Coulais, A; Cutini, S; Cuttaia, F; Danese, L; Davies, R D; Davis, R J; de Bernardis, P; de Gasperis, G; de Rosa, A; de Zotti, G; Delabrouille, J; Delouis, J -M; Dickinson, C; Dole, H; Donzelli, S; Doré, O; Dörl, U; Douspis, M; Dupac, X; Efstathiou, G; Enßlin, T A; Finelli, F; Forni, O; Frailis, M; Franceschi, E; Fuhrmann, L; Galeotta, S; Ganga, K; Gargano, F; Gasparrini, D; Gehrels, N; Giard, M; Giardino, G; Giglietto, N; Giommi, P; Giordano, F; Giraud-Héraud, Y; González-Nuevo, J; Górski, K M; Gratton, S; Gregorio, A; Gruppuso, A; Harrison, D; Henrot-Versillé, S; Herranz, D; Hildebrandt, S R; Hivon, E; Hobson, M; Holmes, W A; Hovest, W; Hoyland, R J; Huffenberger, K M; Jaffe, A H; Juvela, M; Keihänen, E; Keskitalo, R; King, O; Kisner, T S; Kneissl, R; Knox, L; Krichbaum, T P; Kurki-Suonio, H; Lagache, G; Lähteenmäki, A; Lamarre, J -M; Lasenby, A; Laureijs, R J; Lavonen, N; Lawrence, C R; Leach, S; Leonardi, R; León-Tavares, J; Linden-V\\ornle, M; Lindfors, E; López-Caniego, M; Lubin, P M; Macías-Pérez, J F; Maffei, B; Maino, D; Mandolesi, N; Mann, R; Maris, M; Martínez-González, E; Masi, S; Massardi, M; Matarrese, S; Matthai, F; Max-Moerbeck, W; Mazziotta, M N; Mazzotta, P; Melchiorri, A; Mendes, L; Mennella, A; Michelson, P F; Mingaliev, M; Mitra, S; Miville-Deschênes, M -A; Moneti, A; Monte, C; Montier, L; Morgante, G; Mortlock, D; Munshi, D; Murphy, A; Naselsky, P; Natoli, P; Nestoras, I; Netterfield, C B; Nieppola, E; Nilsson, K; N\\orgaard-Nielsen, H U; Noviello, F; Novikov, D; Novikov, I; O'Dwyer, I J; Osborne, S; Pajot, F; Partridge, B; Pasian, F; Patanchon, G; Pavlidou, V; Pearson, T J; Perdereau, O; Perotto, L; Perri, M; Perrotta, F; Piacentini, F; Piat, M; Plaszczynski, S; Platania, P; Pointecouteau, E; Polenta, G; Ponthieu, N; Poutanen, T; Prézeau, G; Prunet, S; Puget, J -L; Rachen, J P; Rainó, S; Reach, W T; Readhead, A; Rebolo, R; Reeves, R; Reinecke, M; Reinthal, R; Renault, C; Ricciardi, S; Richards, J; Riller, T; Riquelme, D; Ristorcelli, I; Rocha, G; Rosset, C; Rowan-Robinson, M; Rubi\; Rusholme, B; Saarinen, J; Sandri, M; Savolainen, P; Scott, D; Seiffert, M D; Sievers, A; Sillanpää, A; Smoot, G F; Sotnikova, Y; Starck, J -L; Stevenson, M; Stivoli, F; Stolyarov, V; Sudiwala, R; Sygnet, J -F; Takalo, L; Tammi, J; Tauber, J A; Terenzi, L; Thompson, D J; Toffolatti, L; Tomasi, M; Tornikoski, M; Torre, J -P; Tosti, G; Tramacere, A; Tristram, M; Tuovinen, J; Türler, M; Turunen, M; Umana, G; Ungerechts, H; Valenziano, L; Valtaoja, E; Varis, J; Verrecchia, F; Vielva, P; Villa, F; Vittorio, N; Wandelt, B D; Wu, J; Yvon, D; Zacchei, A; Zensus, J A; Zhou, X; Zonca, A

2011-01-01T23:59:59.000Z

289

On the choice of time in the continuum limit of polymeric effective theories  

E-Print Network [OSTI]

In polymeric quantum theories, a natural question pertains to the so called continuum limit, corresponding to the limit where the `discreteness parameter' $\\lambda$ approaches zero. In particular one might ask whether the limit exists and, in that case, what the limiting theory is. Here we review recent results on the classical formulation of the problem for a soluble model in loop quantum cosmology. We show that it is only through the introduction of a particular $\\lambda$-dependent internal time function that the limit $\\lambda\\to 0$ can be well defined. We then compare this result with the existing analysis in the quantum theory, where the dynamics was cast in terms of an internal ($\\lambda$-independent) parameter for which the limit does not exist. We briefly comment on the steps needed to define the corresponding time parameter in the quantum theory for which the limit was shown to exist classically.

Alejandro Corichi; Tatjana Vukasinac

2012-09-12T23:59:59.000Z

290

Continuum quasiparticle random phase approximation for astrophysical direct neutron capture reaction of neutron-rich nuclei  

E-Print Network [OSTI]

We formulate a many-body theory to calculate the cross section of direct radiative neutron capture reaction by means of the Hartree-Fock-Bogoliubov mean-field model and the continuum quasiparticle random phase approximation (QRPA). A focus is put on very neutron-rich nuclei and low-energy neutron kinetic energy in the range of O(1 keV) - O(1 MeV), relevant for the rapid neutron-capture process of nucleosynthesis. We begin with the photo-absorption cross section and the E1 strength function, then, in order to apply the reciprocity theorem, we decompose the cross section into partial cross sections corresponding to different channels of one- and two-neutron emission decays of photo-excited states. Numerical example is shown for the photo-absorption of $^{142}$Sn and the neutron capture of $^{141}$Sn.

Masayuki Matsuo

2014-10-31T23:59:59.000Z

291

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

292

Carbon nanotube mats and fibers with irradiationimproved mechanical characteristics: a theoretical model  

E-Print Network [OSTI]

1 Carbon nanotube mats and fibers with irradiation­improved mechanical characteristics characteristics of macroscopic mats and fibers of single­walled carbon nanotubes. We further investigate, which in contrast to most ordinary carbon fibers could be strongly bent without breaking, had much

Nordlund, Kai

293

Carbon nanotube mats and fibers with irradiation-improved mechanical characteristics: a theoretical model  

E-Print Network [OSTI]

1 Carbon nanotube mats and fibers with irradiation-improved mechanical characteristics characteristics of macroscopic mats and fibers of single-walled carbon nanotubes. We further investigate]. The SWNT fibers, which in contrast to most ordinary carbon fibers could be strongly bent without breaking

Nordlund, Kai

294

Quantum Entanglement and Decoherence: Beyond Particle Models. A Farewell to Quantum Mechanics's Weirdness  

E-Print Network [OSTI]

Combining abstract to laboratory projected quantum states a general analysis of headline quantum phenomena is presented. Standard representation mode is replaced; instead quantum states sustained by elementary material constituents occupy its place. Renouncing to assign leading roles to language originated in classical physics when describing genuine quantum processes, together with sustainment concept most, if not all weirdness associated to Quantum Mechanics vanishes.

O. Tapia

2014-04-02T23:59:59.000Z

295

Development and validation of a transition model based on a mechanical approximation  

E-Print Network [OSTI]

A new 3D transition turbulence model, more accurate and faster than an empirical transition model, is proposed. The model is based on the calculation of the pre-transitional u'v' due to mean flow shear. The present transition model is fully described and verified against eight benchmark test cases. Computations are performed for the ERCOFTAC flat-plate T3A, T3C and T3L test cases. Further, the model is validated for bypass, cross-flow and separation induced transition and compared with empirical transition models. The model presents very good results for bypass transition under zero-pressure gradient and with pressure gradient flow conditions. Also the model is able to correctly predict separation induced transition. However, for very low speed and low free-stream turbulence intensity the model delays separation induced transition onset. The model also shows very good results for transition under complex cross-flow conditions in three-dimensional geometries. The 3D tested case was the 6:1 prolate-spheroid und...

Vizinho, R; Silvestre, M

2015-01-01T23:59:59.000Z

296

QCD thermodynamics with continuum extrapolated Wilson fermions II  

E-Print Network [OSTI]

We continue our investigation of 2+1 flavor QCD thermodynamics using dynamical Wilson fermions in the fixed scale approach. Two additional pion masses, approximately 440 MeV and 285 MeV, are added to our previous work at 545 MeV. The simulations were performed at 3 or 4 lattice spacings at each pion mass. The renormalized chiral condensate, strange quark number susceptibility and Polyakov loop is obtained as a function of the temperature and we observe a decrease in the light chiral pseudo-critical temperature as the pion mass is lowered while the pseudo-critical temperature associated with the strange quark number susceptibility or the Polyakov loop is only mildly sensitive to the pion mass. These findings are in agreement with previous continuum results obtained in the staggered formulation.

Szabolcs Borsanyi; Stephan Durr; Zoltan Fodor; Christian Holbling; Sandor D. Katz; Stefan Krieg; Daniel Nogradi; Kalman K. Szabo; Balint C. Toth; Norbert Trombitas

2015-04-14T23:59:59.000Z

297

QCD thermodynamics with continuum extrapolated Wilson fermions II  

E-Print Network [OSTI]

We continue our investigation of 2+1 flavor QCD thermodynamics using dynamical Wilson fermions in the fixed scale approach. Two additional pion masses, approximately 440 MeV and 285 MeV, are added to our previous work at 545 MeV. The simulations were performed at 3 or 4 lattice spacings at each pion mass. The renormalized chiral condensate, strange quark number susceptibility and Polyakov loop is obtained as a function of the temperature and we observe a decrease in the light chiral pseudo-critical temperature as the pion mass is lowered while the pseudo-critical temperature associated with the strange quark number susceptibility or the Polyakov loop is only mildly sensitive to the pion mass. These findings are in agreement with previous continuum results obtained in the staggered formulation.

Borsanyi, Szabolcs; Fodor, Zoltan; Holbling, Christian; Katz, Sandor D; Krieg, Stefan; Nogradi, Daniel; Szabo, Kalman K; Toth, Balint C; Trombitas, Norbert

2015-01-01T23:59:59.000Z

298

UMBRAL DYNAMICS IN THE NEAR-INFRARED CONTINUUM  

SciTech Connect (OSTI)

We detected peaks of oscillatory power at 3 and {approx}6.5 minutes in the umbra of the central sunspot of the active region NOAA AR 10707 in data obtained in the near-infrared (NIR) continuum at 1565.7 nm. The NIR data set captured umbral dynamics around 50 km below the {tau}{sub 500} = 1 level. The umbra does not oscillate as a whole, but rather in distinct parts that are distributed over the umbral surface. The most powerful oscillations, close to a period of {approx}6.5, do not propagate upward. We noted a plethora of large umbral dots (UDs) that persisted for {>=}30 minutes and stayed in the same locations. The peaks of oscillatory power above the detected UDs are located at 3 and 5 minute oscillations, but are very weak in comparison with the oscillations of {approx}6.5 minutes.

Andic, A.; Cao, W.; Goode, P. R. [Also at Big Bear Solar Observatory, 40398 North Shore Lane, Big Bear City, CA 92314 (United States)

2011-08-01T23:59:59.000Z

299

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

2009-10-21T23:59:59.000Z

300

Vehicle Technologies Office Merit Review 2014: Coupled Hierarchical Models for Thermal, Mechanical, Electrical and Electrochemical Processes  

Broader source: Energy.gov [DOE]

Presentation given by [company name] at 2014 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about coupled hierarchical models...

Note: This page contains sample records for the topic "mechanics continuum modeling" 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

A simplified model for estimating population-scale energy impacts of building envelope air-tightening and mechanical ventilation retrofits  

SciTech Connect (OSTI)

Changing the air exchange rate of a home (the sum of the infiltration and mechanical ventilation airflow rates) affects the annual thermal conditioning energy. Large-scale changes to air exchange rates of the housing stock can significantly alter the residential sector's energy consumption. However, the complexity of existing residential energy models is a barrier to the accurate quantification of the impact of policy changes on a state or national level. The Incremental Ventilation Energy (IVE) model developed in this study combines the output of simple air exchange models with a limited set of housing characteristics to estimate the associated change in energy demand of homes. The IVE model was designed specifically to enable modellers to use existing databases of housing characteristics to determine the impact of ventilation policy change on a population scale. The IVE model estimates of energy change when applied to US homes with limited parameterisation are shown to be comparable to the estimates of a well-validated, complex residential energy model.

Logue, J. M.; Turner, W. J.N.; Walker, I. S.; Singer, B. C.

2015-01-01T23:59:59.000Z

302

Modeling astrophysical outflows via the unified Dynamo-Reverse Dynamo mechanism  

E-Print Network [OSTI]

The unified Dynamo-Reverse Dynamo (Dy-RDy) mechanism, capable of simultaneously generating large scale outflows and magnetic fields from an ambient microscopic reservoir, is explored in a broad astrophysical context. The Dy-RDy mechanism is derived via Hall magnetohydrodynamics, which unifies the evolution of magnetic field and fluid vorticity. It also introduces an intrinsic length scale, the ion skin depth, allowing for the proper normalization and categorization of microscopic and macroscopic scales. The large scale Alfv\\'en Mach number $\\mathcal{M}_{A}$, defining the relative "abundance" of the flow field to the magnetic field is shown to be tied to a microscopic scale length that reflects the characteristics of the ambient short scale reservoir. The dynamo (Dy), preferentially producing the large scale magnetic field, is the dominant mode when the ambient turbulence is mostly kinetic, while the outflow producing reverse dynamo (RDy) is the principal manifestation of a magnetically dominated turbulent res...

Lingam, Manasvi

2015-01-01T23:59:59.000Z

303

Thermo-mechanical modelling of the aircraft tyre Lama Elias-Birembaux, Iulian Rosu, Frederic Lebon  

E-Print Network [OSTI]

was created by rotating the axisymmetric 2-D model around the tire axis. In the 2-D model (fig.1 (b)) CAX4T(H) and CAX3T elements from hal-01021033,version1-9Jul2014 #12;ABAQUS element library were selected

Paris-Sud XI, Université de

304

ES2A7 -Fluid Mechanics Example Classes Model Answers to Example Questions (Set II)  

E-Print Network [OSTI]

of msvp = 2 -1 . Calculate the mean model wind tunnel speed if the model is made to 1/10 scale. Assume in a wind tunnel. The airspeed range to be investigated is at the docking end of its range, a maximum -=-=-= --- Question 4: Sliding Board #12;A board with an area slides down an inclined ramp as is schematically

Thomas, Peter J.

305

Project Profile: Predictive Physico-Chemical Modeling of Intrinsic Degradation Mechanisms for Advanced Reflector Materials  

Broader source: Energy.gov [DOE]

NREL, under the Physics of Reliability: Evaluating Design Insights for Component Technologies in Solar (PREDICTS) Program will be developing a physics-based computational degradation model to assess the kinetic oxidation rates; realistic model light attenuation and transport; and multi-layer treatment with variable properties Simulation based experimental design.

306

MECHANICAL TEST RESULTS ON DIPOLE MODEL C-l 25 mm ALUMINUM COLLARS  

E-Print Network [OSTI]

P~. FI'9 . ~ C.C rv'IW\\ 707~-Th ALUMINUM ' ~LAI2.. o Pl.ATTDIPOLE MODEL C-1 25 mm ALUMINUM COLLARS C. Peters FebruaryON DIPOLE MODEL C-I 25 mm ALUMINUM COLLARS· Craig Peters

Peters, C.

2010-01-01T23:59:59.000Z

307

A density functional theory model of mechanically activated silyl ester hydrolysis  

SciTech Connect (OSTI)

To elucidate the mechanism of the mechanically activated dissociation of chemical bonds between carboxymethylated amylose (CMA) and silane functionalized silicon dioxide, we have investigated the dissociation kinetics of the bonds connecting CMA to silicon oxide surfaces with density functional calculations including the effects of force, solvent polarizability, and pH. We have determined the activation energies, the pre-exponential factors, and the reaction rate constants of candidate reactions. The weakest bond was found to be the silyl ester bond between the silicon and the alkoxy oxygen atom. Under acidic conditions, spontaneous proton addition occurs close to the silyl ester such that neutral reactions become insignificant. Upon proton addition at the most favored position, the activation energy for bond hydrolysis becomes 31 kJ?mol{sup ?1}, which agrees very well with experimental observation. Heterolytic bond scission in the protonated molecule has a much higher activation energy. The experimentally observed bi-exponential rupture kinetics can be explained by different side groups attached to the silicon atom of the silyl ester. The fact that different side groups lead to different dissociation kinetics provides an opportunity to deliberately modify and tune the kinetic parameters of mechanically activated bond dissociation of silyl esters.

Pill, Michael F.; Schmidt, Sebastian W. [Department of Applied Sciences and Mechatronics, Munich University of Applied Sciences, Lothstr. 34, 80335 Munich (Germany) [Department of Applied Sciences and Mechatronics, Munich University of Applied Sciences, Lothstr. 34, 80335 Munich (Germany); Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel, Olshausenstraße 40, 24098 Kiel (Germany); Center for Nanoscience (CeNS), Geschwister-Scholl-Platz 1, 80539 Munich (Germany); Beyer, Martin K. [Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel, Olshausenstraße 40, 24098 Kiel (Germany) [Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel, Olshausenstraße 40, 24098 Kiel (Germany); Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens-Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck (Austria); Clausen-Schaumann, Hauke [Department of Applied Sciences and Mechatronics, Munich University of Applied Sciences, Lothstr. 34, 80335 Munich (Germany) [Department of Applied Sciences and Mechatronics, Munich University of Applied Sciences, Lothstr. 34, 80335 Munich (Germany); Center for Nanoscience (CeNS), Geschwister-Scholl-Platz 1, 80539 Munich (Germany); Kersch, Alfred, E-mail: akersch@hm.edu [Department of Applied Sciences and Mechatronics, Munich University of Applied Sciences, Lothstr. 34, 80335 Munich (Germany)] [Department of Applied Sciences and Mechatronics, Munich University of Applied Sciences, Lothstr. 34, 80335 Munich (Germany)

2014-01-28T23:59:59.000Z

308

Continuum Mechanics and Thermodynamics manuscript No. (will be inserted by the editor)  

E-Print Network [OSTI]

, embedded thermocouples, infrared thermography to ultra fast pyrometry. Two quantities are generally derived

309

A Mathematical Analysis of Atomistic-to-Continuum (AtC) Multiscale Coupling Methods  

SciTech Connect (OSTI)

We have worked on several projects aimed at improving the efficiency and understanding of multiscale methods, especially those applicable to problems involving atomistic-to-continuum coupling. Activities include blending methods for AtC coupling and efficient quasi-continuum methods for problems with long-range interactions.

Gunzburger, Max

2013-11-13T23:59:59.000Z

310

Learning-Based Configuration Estimation of a Multi-Segment Continuum Robot  

E-Print Network [OSTI]

rotational accuracy in the range of 1 -2 is achieved. I. INTRODUCTION Continuum robots are continuously Orifice Translumenal Endoscopic Surgery (NOTES) [3]. Continuum robots have been investigated recently of accuracy due to friction, extension and torsion of their actuation lines, kinematic approximations

Simaan, Nabil

311

Modeling Frameworks for Representing the Mechanical Behavior of Tissues with a Specific Look at Vasculature  

E-Print Network [OSTI]

Many mechanicstic models aimed at predicting tissue behavior attempt to connect constitutive factors (such as effects due to collagen or fibrin concentrations) with the overall tissue behavior. Such a link between constitutive and material behaviors...

Andersohn, Alexander

2013-08-27T23:59:59.000Z

312

Derivation of Newton's Law of Gravitation Based on a Fluid Mechanical Singularity Model of Particles  

E-Print Network [OSTI]

We speculate that the universe may be filled with a kind of fluid which may be called aether or tao. Thus, Newton's law of gravitation is derived by methods of hydrodynamics based on a sink flow model of particles.

Xiao-Song Wang

2006-10-25T23:59:59.000Z

313

NUMERICAL MODELING FOR THE FORMATION MECHANISM OF 3D TOPOGRAPHY ON MICROBIAL MAT SURFACES  

E-Print Network [OSTI]

though, that nutrient limitation coupled with fluid motion may play a key role as a physical control. Under this model, competitions of nutrients were setup among growing microbial communities, which later evolve into specially arranged, 3D mats. However...

Patel, Harsh Jay

2013-09-27T23:59:59.000Z

314

Length-scale dependent mechanical properties of Al-Cu eutectic alloy: Molecular dynamics based model and its experimental verification  

SciTech Connect (OSTI)

This paper attempts to gain an understanding of the effect of lamellar length scale on the mechanical properties of two-phase metal-intermetallic eutectic structure. We first develop a molecular dynamics model for the in-situ grown eutectic interface followed by a model of deformation of Al-Al{sub 2}Cu lamellar eutectic. Leveraging the insights obtained from the simulation on the behaviour of dislocations at different length scales of the eutectic, we present and explain the experimental results on Al-Al{sub 2}Cu eutectic with various different lamellar spacing. The physics behind the mechanism is further quantified with help of atomic level energy model for different length scale as well as different strain. An atomic level energy partitioning of the lamellae and the interface regions reveals that the energy of the lamellae core are accumulated more due to dislocations irrespective of the length-scale. Whereas the energy of the interface is accumulated more due to dislocations when the length-scale is smaller, but the trend is reversed when the length-scale is large beyond a critical size of about 80?nm.

Tiwary, C. S., E-mail: cst.iisc@gmail.com; Chattopadhyay, K. [Department of Materials Engineering, Indian Institute of Science, Bangalore 560012 (India); Chakraborty, S.; Mahapatra, D. R. [Department of Aerospace Engineering, Indian Institute of Science, Bangalore 560012 (India)

2014-05-28T23:59:59.000Z

315

Particle-scale CO2 adsorption kinetics modeling considering three reaction mechanisms  

SciTech Connect (OSTI)

In the presence of water (H2O), dry and wet adsorptions of carbon dioxide (CO2) and physical adsorption of H2O happen concurrently in a sorbent particle. The three reactions depend on each other and have a complicated, but important, effect on CO2 capturing via a solid sorbent. In this study, transport phenomena in the sorbent were modeled, including the tree reactions, and a numerical solving procedure for the model also was explained. The reaction variable distribution in the sorbent and their average values were calculated, and simulation results were compared with experimental data to validate the proposed model. Some differences, caused by thermodynamic parameters, were observed between them. However, the developed model reasonably simulated the adsorption behaviors of a sorbent. The weight gained by each adsorbed species, CO2 and H2O, is difficult to determine experimentally. It is known that more CO2 can be captured in the presence of water. Still, it is not yet known quantitatively how much more CO2 the sorbent can capture, nor is it known how much dry and wet adsorptions separately account for CO2 capture. This study addresses those questions by modeling CO2 adsorption in a particle and simulating the adsorption process using the model. As adsorption temperature changed into several values, the adsorbed amount of each species was calculated. The captured CO2 in the sorbent particle was compared quantitatively between dry and wet conditions. As the adsorption temperature decreased, wet adsorption increased. However, dry adsorption was reduced.

Suh, Dong-Myung; Sun, Xin

2013-09-01T23:59:59.000Z

316

Fracture mechanics models developed for piping reliability assessment in light water reactors: piping reliability project  

SciTech Connect (OSTI)

The efforts concentrated on modifications of the stratified Monte Carlo code called PRAISE (Piping Reliability Analysis Including Seismic Events) to make it more widely applicable to probabilistic fracture mechanics analysis of nuclear reactor piping. Pipe failures are considered to occur as the result of crack-like defects introduced during fabrication, that escape detection during inspections. The code modifications allow the following factors in addition to those considered in earlier work to be treated: other materials, failure criteria and subcritical crack growth characteristic; welding residual and vibratory stresses; and longitudinal welds (the original version considered only circumferential welds). The fracture mechanics background for the code modifications is included, and details of the modifications themselves provided. Additionally, an updated version of the PRAISE user's manual is included. The revised code, known as PRAISE-B was then applied to a variety of piping problems, including various size lines subject to stress corrosion cracking and vibratory stresses. Analyses including residual stresses and longitudinal welds were also performed.

Harris, D.O.; Lim, E.Y.; Dedhia, D.D.; Woo, H.H.; Chou, C.K.

1982-06-01T23:59:59.000Z

317

Central engines of Gamma Ray Bursts. Magnetic mechanism in the collapsar model  

E-Print Network [OSTI]

In this study we explore the magnetic mechanism of hypernovae and relativistic jets of long duration gamma ray bursts within the collapsar scenario. This is an extension of our earlier work [1]. We track the collapse of massive rotating stars onto a rotating central black hole using axisymmetric general relativistic magnetohydrodynamic code that utilizes a realistic equation of state and takes into account the cooling associated with emission of neutrinos and the energy losses due to dissociation of nuclei. The neutrino heating is not included. We describe solutions with different black hole rotation, mass accretion rate, and strength of progenitor's magnetic field. Some of them exhibits strong explosions driven by Poynting-dominated jets with power up to $12\\times10^{51} {erg s}^{-1}$. These jets originate from the black hole and powered via the Blandford-Znajek mechanism. A provisional criterion for explosion is derived. A number of simulation movies can be downloaded from http://www.maths.leeds.ac.uk/~serguei/research/movies/anim.html

Maxim V. Barkov; Serguei S. Komissarov

2008-09-08T23:59:59.000Z

318

Physical process Mechanical mechanisms  

E-Print Network [OSTI]

1 Physical process Generation · Mechanical mechanisms F = m·a · Electric/Magnetic mechanisms F ­ Quadrupoles......shear stress fluctuations ­ High order poles...... phys. interpretation difficult Governing

Berlin,Technische Universität

319

Modeling oscillatory dynamics in brain microcircuits as a way to help uncover neurological disease mechanisms: A proposal  

SciTech Connect (OSTI)

There is an undisputed need and requirement for theoretical and computational studies in Neuroscience today. Furthermore, it is clear that oscillatory dynamical output from brain networks is representative of various behavioural states, and it is becoming clear that one could consider these outputs as measures of normal and pathological brain states. Although mathematical modeling of oscillatory dynamics in the context of neurological disease exists, it is a highly challenging endeavour because of the many levels of organization in the nervous system. This challenge is coupled with the increasing knowledge of cellular specificity and network dysfunction that is associated with disease. Recently, whole hippocampus in vitro preparations from control animals have been shown to spontaneously express oscillatory activities. In addition, when using preparations derived from animal models of disease, these activities show particular alterations. These preparations present an opportunity to address challenges involved with using models to gain insight because of easier access to simultaneous cellular and network measurements, and pharmacological modulations. We propose that by developing and using models with direct links to experiment at multiple levels, which at least include cellular and microcircuit, a cycling can be set up and used to help us determine critical mechanisms underlying neurological disease. We illustrate our proposal using our previously developed inhibitory network models in the context of these whole hippocampus preparations and show the importance of having direct links at multiple levels.

Skinner, F. K. [Toronto Western Research Institute, University Health Network, Krembil Discovery Tower, Toronto Western Hospital, 60 Leonard Street, 7th floor, 7KD411, Toronto, Ontario M5T 2S8 (Canada) [Toronto Western Research Institute, University Health Network, Krembil Discovery Tower, Toronto Western Hospital, 60 Leonard Street, 7th floor, 7KD411, Toronto, Ontario M5T 2S8 (Canada); Department of Medicine (Neurology), University of Toronto, 200 Elizabeth Street, Toronto, Ontario M5G 2C4 (Canada); Department of Physiology, University of Toronto Medical Sciences Building, 3rd Floor, 1 King's College Circle, Toronto, Ontario M5S 1A8 (Canada); Ferguson, K. A. [Toronto Western Research Institute, University Health Network, Krembil Discovery Tower, Toronto Western Hospital, 60 Leonard Street, 7th floor, 7KD411, Toronto, Ontario M5T 2S8 (Canada) [Toronto Western Research Institute, University Health Network, Krembil Discovery Tower, Toronto Western Hospital, 60 Leonard Street, 7th floor, 7KD411, Toronto, Ontario M5T 2S8 (Canada); Department of Physiology, University of Toronto Medical Sciences Building, 3rd Floor, 1 King's College Circle, Toronto, Ontario M5S 1A8 (Canada)

2013-12-15T23:59:59.000Z

320

Persistent energy flow for a stochastic wave equation model in nonequilibrium statistical mechanics  

E-Print Network [OSTI]

We consider a one-dimensional partial differential equation system modeling heat flow around a ring. The system includes a Klein-Gordon wave equation for a field satisfying spatial periodic boundary conditions, as well as Ornstein-Uhlenbeck stochastic differential equations with finite rank dissipation and stochastic driving terms modeling heat baths. There is an energy flow around the ring. In the case of a linear field with different (fixed) bath temperatures, the energy flow can persist even when the interaction with the baths is turned off. A simple example is given.

Lawrence E. Thomas

2012-04-29T23:59:59.000Z

Note: This page contains sample records for the topic "mechanics continuum modeling" from the National Library of EnergyBeta (NLEBeta).
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321

Discriminating binding mechanisms of an intrinsically disordered protein via a multi-state coarse-grained model  

SciTech Connect (OSTI)

Many proteins undergo a conformational transition upon binding to their cognate binding partner, with intrinsically disordered proteins (IDPs) providing an extreme example in which a folding transition occurs. However, it is often not clear whether this occurs via an “induced fit” or “conformational selection” mechanism, or via some intermediate scenario. In the first case, transient encounters with the binding partner favour transitions to the bound structure before the two proteins dissociate, while in the second the bound structure must be selected from a subset of unbound structures which are in the correct state for binding, because transient encounters of the incorrect conformation with the binding partner are most likely to result in dissociation. A particularly interesting situation involves those intrinsically disordered proteins which can bind to different binding partners in different conformations. We have devised a multi-state coarse-grained simulation model which is able to capture the binding of IDPs in alternate conformations, and by applying it to the binding of nuclear coactivator binding domain (NCBD) to either ACTR or IRF-3 we are able to determine the binding mechanism. By all measures, the binding of NCBD to either binding partner appears to occur via an induced fit mechanism. Nonetheless, we also show how a scenario closer to conformational selection could arise by choosing an alternative non-binding structure for NCBD.

Knott, Michael [Department of Chemistry, Cambridge University, Lensfield Road, Cambridge CB2 1EW (United Kingdom)] [Department of Chemistry, Cambridge University, Lensfield Road, Cambridge CB2 1EW (United Kingdom); Best, Robert B., E-mail: robertbe@helix.nih.gov [Department of Chemistry, Cambridge University, Lensfield Road, Cambridge CB2 1EW (United Kingdom); Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520 (United States)

2014-05-07T23:59:59.000Z

322

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

2012-09-05T23:59:59.000Z

323

Physiologically realistic modelling of a mechanism for neural representation of intervals of time  

E-Print Network [OSTI]

-8610, Japan c CREST, Japan Science and Technology (JST), Saitama 332-0012, Japan Abstract A model, Fuji Xerox Co. Ltd., 430 Sakai, Nakai-machi, Ashigarakami-gun, Kanagawa 259-0157, Japan b Department as well as the difference stated above, will lead us to the idea that an interval of time, T

Fukai, Tomoki

324

Multi-Configuration Model Tuning for Precision Opto-Mechanical Systems  

E-Print Network [OSTI]

on a testbed at the MIT Space Systems Lab (SSL) in order to gauge its usefulness. The traditional model tuning will be performed by a colleague in the SSL who will use such methods as trial-and- error parameter updating comments. Thanks to the DOCS team at MIT's SSL, esp

325

Modelling the thermal quenching mechanism in quartz based on time-resolved optically stimulated luminescence  

E-Print Network [OSTI]

, Denmark c Nordic Laboratory for Luminescence Dating, Department of Earth Science, Aarhus University, Risø luminescence Pulsed OSL Thermoluminescence Quartz Luminescence lifetimes Kinetic rate equations Kinetic model temperature is raised, and has been observed in both thermo- luminescence (TL) and optically stimulated

Chen, Reuven

326

Development of Advanced Thermal-Hydrological-Mechanical-Chemical (THMC) Modeling Capabilities for Enhanced Geothermal Systems  

Broader source: Energy.gov [DOE]

Project objectives: Develop a general framework for effective flow of water, steam and heat in in porous and fractured geothermal formations. Develop a computational module for handling coupled effects of pressure, temperature, and induced rock deformations. Develop a reliable model of heat transfer and fluid flow in fractured rocks.

327

Small-energy series for one-dimensional quantum-mechanical models with non-symmetric potentials  

E-Print Network [OSTI]

We generalize a recently proposed small-energy expansion for one-dimensional quantum-mechanical models. The original approach was devised to treat symmetric potentials and here we show how to extend it to non-symmetric ones. Present approach is based on matching the logarithmic derivatives for the left and right solutions to the Schr\\"odinger equation at the origin (or any other point chosen conveniently) . As in the original method, each logarithmic derivative can be expanded in a small-energy series by straightforward perturbation theory. We test the new approach on four simple models, one of which is not exactly solvable. The perturbation expansion converges in all the illustrative examples so that one obtains the ground-state energy with an accuracy determined by the number of available perturbation corrections.

Paolo Amore; Francisco M. Fernández

2014-10-21T23:59:59.000Z

328

Melanin, a promising radioprotector: Mechanisms of actions in a mice model  

SciTech Connect (OSTI)

The radioprotective effect of extracellular melanin, a naturally occurring pigment, isolated from the fungus Gliocephalotrichum simplex was examined in BALB/C mice, and the probable mechanism of action was established. At an effective dose of 50 mg/kg body weight, melanin exhibited both prophylactic and mitigative activities, increasing the 30-day survival of mice by 100% and 60%, respectively, after exposure to radiation (7 Gy, whole body irradiation (WBI)). The protective activity of melanin was primarily due to inhibition of radiation-induced hematopoietic damages as evidenced by improvement in spleen parameters such as index, total cellularity, endogenous colony forming units, and maintenance of circulatory white blood cells and platelet counts. Melanin also reversed the radiation-induced decrease in ERK phosphorylation in splenic tissue, which may be the key feature in its radioprotective action. Additionally, our results indicated that the sustained activation of AKT, JNK and P38 proteins in splenic tissue of melanin pre-treated group may also play a secondary role. This was also supported by the fact that melanin could prevent apoptosis in splenic tissue by decreasing BAX/Bcl-XL ratio, and increasing the expressions of the proliferation markers (PCNA and Cyclin D1), compared to the radiation control group. Melanin also reduced the oxidative stress in hepatic tissue and abrogated immune imbalance by reducing the production of pro-inflammatory cytokines (IL6 and TNF?). In conclusion, our results confirmed that fungal melanin is a very effective radioprotector against WBI and the probable mechanisms of radioprotection are due to modulation in pro-survival (ERK) signaling, prevention of oxidative stress and immunomodulation. -- Highlights: ? Melanin showed promising radioprotection under pre and post irradiation condition. ? Melanin protects the hematopoietic system from radiation induced damage. ? Melanin modulates pro-survival pathways, immune system and prevents oxidative stress.

Kunwar, A., E-mail: amitbio@rediffmail.com [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Adhikary, B. [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)] [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Jayakumar, S. [Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)] [Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Barik, A. [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)] [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Chattopadhyay, S. [Bio-Organic Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)] [Bio-Organic Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Raghukumar, S. [Myko Tech Private Limited, Dona Paula, Goa?403004 (India)] [Myko Tech Private Limited, Dona Paula, Goa?403004 (India); Priyadarsini, K.I., E-mail: kindira@barc.gov.in [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

2012-10-15T23:59:59.000Z

329

FIRESTRUC - Integrating advanced three-dimensional modelling methodologies for predicting thermo-mechanical behaviour of steel and composite structures subjected to natural fires   

E-Print Network [OSTI]

A hierarchy of coupling strategies for integrating advanced three-dimensional modelling methodologies for prediction of the thermo-mechanical response of structures in fire has been developed and systematically assessed. ...

Welch, Stephen; Miles, Steward; Kumar, Suresh; Lemaire, Tony; Chan, Alan

330

Tuning the Fano Resonance with an Intruder Continuum  

E-Print Network [OSTI]

Through a combination of experiment and theory we establish the possibility of achieving strong tuning of Fano resonances (FRs), by allowing their usual two-path geometry to interfere with an additional, 'intruder', continuum. As the coupling strength to this intruder is varied, we predict strong modulations of the resonance line shape that, in principle at least, may exceed the amplitude of the original FR itself. For a proof-of-concept demonstration of this phenomenon, we construct a nanoscale interferometer from nonlocally coupled quantum point contacts and utilize the unique features of their density of states to realize the intruder. External control of the intruder coupling is enabled by means of an applied magnetic field, in the presence of which we demonstrate the predicted distortions of the FR. This general scheme for resonant control should be broadly applicable to a variety of wave-based systems, opening up the possibility of new applications in areas such as chemical and biological sensing and secure communications.

J. Fransson; M. -G. Kang; Y. Yoon; S. Xiao; Y. Ochiai; J. L. Reno; N. Aoki; J. P. Bird

2014-03-11T23:59:59.000Z

331

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

2009-10-21T23:59:59.000Z

332

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

SciTech Connect (OSTI)

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

333

A STATISTICAL STUDY OF THE SPECTRAL HARDENING OF CONTINUUM EMISSION IN SOLAR FLARES  

SciTech Connect (OSTI)

The observed hard X-ray and {gamma}-ray continuum in solar flares is interpreted as Bremsstrahlung emission of accelerated non-thermal electrons. It has been noted for a long time that in many flares the energy spectra show hardening at energies around or above 300 keV. In this paper, we first conduct a survey of spectral hardening events that were previously studied in the literature. We then perform a systematic examination of 185 flares from the Solar Maximum Mission. We identify 23 electron-dominated events whose energy spectra show clear double power laws. A statistical study of these events shows that the spectral index below the break ({gamma}{sub 1}) anti-correlates with the break energy ({epsilon}{sub b}). Furthermore, {gamma}{sub 1} also anti-correlates with Fr, the fraction of photons above the break compared to the total photons. A hardening spectrum, as well as the correlations between ({gamma}{sub 1}, {epsilon}{sub b}) and ({gamma}{sub 1}, Fr), provide stringent constraints on the underlying electron acceleration mechanism. Our results support a recent proposal that electrons are being accelerated diffusively at a flare termination shock with a width of the order of an ion inertial length scale.

Kong, X.; Chen, Y. [Institute of Space Sciences and School of Space Science and Physics, Shandong University, Weihai 264209 (China); Li, G., E-mail: xl_kong@hotmail.com, E-mail: gang.li@uah.edu [Department of Physics and CSPAR, University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

2013-09-10T23:59:59.000Z

334

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

SciTech Connect (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

335

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

SciTech Connect (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

336

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

SciTech Connect (OSTI)

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

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

2013-03-01T23:59:59.000Z

337

Low Energy Continuum and Lattice Effective Field Theories  

E-Print Network [OSTI]

In the first part of the thesis we consider the constraints of causality and unitarity for particles interacting via strictly finite-range interactions. We generalize Wigner's causality bound to the case of non-vanishing partial-wave mixing. Specifically we analyze the system of the low-energy interactions between protons and neutrons. We also analyze low-energy scattering for systems with arbitrary short-range interactions plus an attractive $1/r^{\\alpha}$ tail for $\\alpha\\geq2$. In particular, we focus on the case of $\\alpha=6$ and we derive the constraints of causality and unitarity also for these systems and find that the van der Waals length scale dominates over parameters characterizing the short-distance physics of the interaction. This separation of scales suggests a separate universality class for physics characterizing interactions with an attractive $1/r^{6}$ tail. We argue that a similar universality class exists for any attractive potential $1/r^{\\alpha}$ for $\\alpha\\geq2$. In the second part of the thesis we present lattice Monte Carlo calculations of fermion-dimer scattering in the limit of zero-range interactions using the adiabatic projection method. The adiabatic projection method uses a set of initial cluster states and Euclidean time projection to give a systematically improvable description of the low-lying scattering cluster states in a finite volume. We use L\\"uscher's finite-volume relations to determine the $s$-wave, $p$-wave, and $d$-wave phase shifts. For comparison, we also compute exact lattice results using Lanczos iteration and continuum results using the Skorniakov-Ter-Martirosian equation. For our Monte Carlo calculations we use a new lattice algorithm called impurity lattice Monte Carlo. This algorithm can be viewed as a hybrid technique which incorporates elements of both worldline and auxiliary-field Monte Carlo simulations.

Serdar Elhatisari

2014-09-14T23:59:59.000Z

338

average atom model: Topics by E-print Network  

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

(chemical potential, average ionic charge, free electron density, bound and continuum wave-functions and occupation numbers) are obtained from the average-atom model. The...

339

THE RADIO CONTINUUM STRUCTURE OF CENTAURUS A AT 1.4 GHz  

SciTech Connect (OSTI)

A 45 deg{sup 2} radio continuum imaging campaign of the nearest radio galaxy, Centaurus A, is reported. Using the Australia Telescope Compact Array and the Parkes 64 m radio telescope at 1.4 GHz, the spatial resolution of the resultant image is {approx}600 pc ({approx}50''), resolving the {approx}>500 kpc giant radio lobes with approximately five times better physical resolution compared to any previous image, and making this the most detailed radio continuum image of any radio galaxy to date. In this paper, we present these new data and discuss briefly some of the most interesting morphological features that we have discovered in the images. The two giant outer lobes are highly structured and considerably distinct. The southern part of the giant northern lobe naturally extends out from the northern middle lobe with uniformly north-streaming emission. The well known northern loop is resolved into a series of semi-regular shells with a spacing of approximately 25 kpc. The northern part of the giant northern lobe also contains identifiable filaments and partial ring structures. As seen in previous single-dish images at lower angular resolution, the giant southern lobe is not physically connected to the core at radio wavelengths. Almost the entirety of the giant southern lobe is resolved into a largely chaotic and mottled structure which appears considerably different (morphologically) to the diffuse regularity of the northern lobe. We report the discovery of a vertex and a vortex near the western boundary of the southern lobe, two striking, high surface brightness features that are named based on their morphology and not their dynamics (which are presently unknown). The vortex and vertex are modeled as reaccelerated lobe emission due to shocks from the active galactic nucleus itself or from the passage of a dwarf elliptical galaxy through the lobe. Preliminary polarimetric and spectral index studies support a plasma reacceleration model and could explain the origin of the Faraday rotation structure detected in the southern lobe. In addition, there are a series of low surface brightness wisps detected around the edges of both the giant lobes.

Feain, I. J.; Cornwell, T. J.; Ekers, R. D.; Calabretta, M. R.; Norris, R. P.; O'Sullivan, S.; McClure-Griffiths, N. M. [CSIRO Astronomy and Space Science, P.O. Box 76, Epping, NSW 1710 (Australia); Johnston-Hollitt, M. [School of Chemical and Physical Sciences, Victoria University of Wellington, P.O. Box 600, Wellington (New Zealand); Ott, J. [National Radio Astronomical Observatory, Charlottesville, P.O. Box O, 1003 Lopezville Road, Socorro, NM 87801-0387 (United States); Lindley, E.; Gaensler, B. M.; Murphy, T.; Bland-Hawthorn, J. [Sydney Institute for Astronomy, School of Physics, University of Sydney, Sydney, NSW 2006 (Australia); Middelberg, E. [Astronomisches Institut der Universitaet Bochum, Universitaetsstr. 150, D-44801 Bochum (Germany); Jiraskova, S., E-mail: ilana.feain@csiro.au [Department of Astrophysics/IMAPP, Radboud University Nijmegen, P.O. Box 9010, NL-6500 GL Nijmegen (Netherlands)

2011-10-10T23:59:59.000Z

340

Computer as a physical system: a microscopic quantum mechanical Hamiltonian model of computers represented by Turing machines  

SciTech Connect (OSTI)

A microscopic quantum mechanical model of computers as represented by Turing machines is constructed. It is shown that for each number N and Turing machine Q there exists a Hamiltonian H/sub N//sup Q/ and a class of appropriate initial states such that, if PSI/sub Q//sup N/(0) is such an initial state, then PSI/sub Q//sup N/(t) = exp(-iH/sub N//sup Q/t) PSI/sub Q//sup N/(0) correctly describes at times t/sub 3/, t/sub 6/,..., t/sub 3N/ model states that correspond to the completion of the first, second,..., Nth computation step of Q. The model parameters can be adjusted so that for an arbitrary time interval ..delta.. around t/sub 3/, t/sub 6/,..., t/sub 3N/, the machine part of PSI/sub Q//sup N/(t) is stationary. 1 figure.

Benioff, P.

1980-01-01T23:59:59.000Z

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


341

Gaseous Chemistry and Aerosol Mechanism Developments for Version 3.5.1 of the Online Regional Model, WRF-Chem  

SciTech Connect (OSTI)

We have made a number of developments in the regional coupled model WRF-Chem, with the aim of making the model more suitable for prediction of atmospheric composition and of interactions between air quality and weather. We have worked on the European domain, with a particular focus on making the model suitable for the study of night time chemistry and oxidation by the nitrate radical in the UK atmosphere. A reduced form of the Common Reactive Intermediates gas-phase chemical mechanism (CRIv2-R5) has been implemented to enable more explicit simulation of VOC degradation. N2O5 heterogeneous chemistry has been added to the existing sectional MOSAIC aerosol module, and coupled to both the CRIv2-R5 and existing CBM-Z gas phase scheme. Modifications have also been made to the sea-spray aerosol emission representation, allowing the inclusion of primary organic material in sea-spray aerosol. Driven by appropriate emissions, wind fields and chemical boundary conditions, implementation of the different developments is illustrated in order to demonstrate the impact that these changes have in the North-West European domain. These developments are now part of the freely available WRF-Chem distribution.

Archer-Nicholls, Scott; Lowe, Douglas; Utembe, Steve; Allan, James D.; Zaveri, Rahul A.; Fast, Jerome D.; Hodnebrog, Oivind; Denier van der Gon, Hugo; McFiggans, Gordon

2014-11-08T23:59:59.000Z

342

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

SciTech Connect (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

343

A unified electrostatic and cavitation model for first-principles molecular dynamics in solution  

E-Print Network [OSTI]

The electrostatic continuum solvent model developed by Fattebert and Gygi is combined with a first-principles formulation of the cavitation energy based on a natural quantum-mechanical definition for the surface of a solute. Despite its simplicity, the cavitation contribution calculated by this approach is found to be in remarkable agreement with that obtained by more complex algorithms relying on a large set of parameters. Our model allows for very efficient Car-Parrinello simulations of finite or extended systems in solution, and demonstrates a level of accuracy as good as that of established quantum-chemistry continuum solvent methods. We apply this approach to the study of tetracyanoethylene dimers in dichloromethane, providing valuable structural and dynamical insights on the dimerization phenomenon.

Damian A. Scherlis; Jean-Luc Fattebert; Francois Gygi; Matteo Cococcioni; Nicola Marzari

2005-10-06T23:59:59.000Z

344

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

SciTech Connect (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

345

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

SciTech Connect (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

2009-12-01T23:59:59.000Z

346

A novel mechanism and kinetic model to explain enhanced xylose yields from dilute sulfuric acid compared to hydrothermal pretreatment of corn stover  

E-Print Network [OSTI]

A novel mechanism and kinetic model to explain enhanced xylose yields from dilute sulfuric acid stover Dilute sulfuric acid Hydrothermal pretreatment Kinetic model Xylose a b s t r a c t Pretreatment of corn stover in 0.5% sulfuric acid at 160 °C for 40 min realized a maximum monomeric plus oligomeric

California at Riverside, University of

347

Techniques to treat the continuum applied to electromagnetictransitions in $^8$Be  

E-Print Network [OSTI]

Bremsstrahlung emission in collisions between charged nuclei is equivalent to nuclear gamma decay between continuum states. The way the continuum spectrum can be treated is not unique, and efficiency and accuracy of cross section calculations depend on the chosen method. In this work we describe, relate, and compare three different methods in practical calculations of inelastic cross sections, that is, by (i) treating the initial and final states as pure continuum states on the real energy axis, (ii) discretizing the continuum states on the real energy axis with a box boundary condition, and (iii) complex rotation of the hamiltonian(complex scaling method). The electric quadrupole transitions, $2^+ \\rightarrow 0^+$ and $4^+ \\rightarrow 2^+$, in $\\alpha+\\alpha$ scattering are taken as an illustration.

E. Garrido; A. S. Jensen; D. V. Fedorov

2013-12-20T23:59:59.000Z

348

A continuum theory of amorphous solids undergoing large deformations, with application to polymeric glasses  

E-Print Network [OSTI]

This paper summarizes a recently developed continuum theory for the elastic-viscoplastic deformation of amorphous solids such as polymeric and metallic glasses. Introducing an internal-state variable that represents the ...

Anand, Lallit

349

Cavitation Thermometry Using Molecular and Continuum Sonoluminescence Lawrence S. Bernstein* and Mitchell R. Zakin  

E-Print Network [OSTI]

Cavitation Thermometry Using Molecular and Continuum Sonoluminescence Lawrence S. Bernstein (SB) sonoluminescence (SL) is explored as a probe of bubble temperature during cavitational collapse discrete intervals along the cavitational collapse time line, thus yielding different cavitation

Suslick, Kenneth S.

350

Configuration and Joint Feedback for Enhanced Performance of Multi-Segment Continuum Robots  

E-Print Network [OSTI]

and Natural Orifice Transluminal Endoscopic Surgery (NOTES) emphasize this need. Current designs of continuum algorithms in order to meet the desired accuracy. The lack of accuracy is due to friction, extension

Simaan, Nabil

351

Photodissociation of O2 via the Herzberg continuum: Measurements of O-atom alignment and orientation  

E-Print Network [OSTI]

resonantly enhanced multiphoton ionization 2 1 REMPI near 225 nm and the ions collected in a velocity regions: the Herzberg continuum 242­200 nm , the Schumann­Runge bands 200­176 nm , and the Schumann

Zare, Richard N.

352

Mapping between the order of thermal denaturation and the shape of the critical line of mechanical unzipping in 1-dimensional DNA models  

E-Print Network [OSTI]

In this Letter, we investigate the link between thermal denaturation and mechanical unzipping for two models of DNA, namely the Dauxois-Peyrard-Bishop model and a variant thereof we proposed recently. We show that the critical line that separates zipped from unzipped DNA sequences in mechanical unzipping experiments is a power-law in the temperature-force plane. We also prove that for the investigated models the corresponding critical exponent is proportional to the critical exponent alpha, which characterizes the behaviour of the specific heat in the neighbourhood of the critical temperature for thermal denaturation.

Buyukdagli, Sahin; 10.1016/j.cplett.2009.11.061

2010-01-01T23:59:59.000Z

353

Computational mechanics  

SciTech Connect (OSTI)

The Computational Mechanics thrust area sponsors research into the underlying solid, structural and fluid mechanics and heat transfer necessary for the development of state-of-the-art general purpose computational software. The scale of computational capability spans office workstations, departmental computer servers, and Cray-class supercomputers. The DYNA, NIKE, and TOPAZ codes have achieved world fame through our broad collaborators program, in addition to their strong support of on-going Lawrence Livermore National Laboratory (LLNL) programs. Several technology transfer initiatives have been based on these established codes, teaming LLNL analysts and researchers with counterparts in industry, extending code capability to specific industrial interests of casting, metalforming, and automobile crash dynamics. The next-generation solid/structural mechanics code, ParaDyn, is targeted toward massively parallel computers, which will extend performance from gigaflop to teraflop power. Our work for FY-92 is described in the following eight articles: (1) Solution Strategies: New Approaches for Strongly Nonlinear Quasistatic Problems Using DYNA3D; (2) Enhanced Enforcement of Mechanical Contact: The Method of Augmented Lagrangians; (3) ParaDyn: New Generation Solid/Structural Mechanics Codes for Massively Parallel Processors; (4) Composite Damage Modeling; (5) HYDRA: A Parallel/Vector Flow Solver for Three-Dimensional, Transient, Incompressible Viscous How; (6) Development and Testing of the TRIM3D Radiation Heat Transfer Code; (7) A Methodology for Calculating the Seismic Response of Critical Structures; and (8) Reinforced Concrete Damage Modeling.

Goudreau, G.L.

1993-03-01T23:59:59.000Z

354

$^4{\\rm He}$+$n$+$n$ continuum within an ab initio framework  

E-Print Network [OSTI]

The low-lying continuum spectrum of the $^6{\\rm He}$ nucleus is investigated for the first time within an ab initio framework that encompasses the $^4{\\rm He}$+$n$+$n$ three-cluster dynamics characterizing its lowest decay channel. This is achieved through an extension of the no-core-shell model combined with the resonating-group method, in which energy-independent non-local interactions among three nuclear fragments can be calculated microscopically starting from realistic nucleon-nucleon interactions and consistent ab initio many-body wave functions of the clusters. The three-cluster Schr\\"odinger equation is solved with three-body scattering boundary conditions by means of the hyperspherical-harmonic method on a Lagrange mesh. Using a soft similarity-renormalization-group evolved chiral nucleon-nucleon potential, we find the known $J^\\pi = 2^+$ resonance as well as a result consistent with a new low-lying second $2^+$ resonance recently observed at GANIL at $2.6$ MeV above the $^6$He ground state. We also find resonances in the $2^-$, $1^+$ and $0^-$ channels, while no low-lying resonances are present in the $0^+$ and $1^-$ channels.

Carolina Romero-Redondo; Sofia Quaglioni; Petr Navrátil; Guillaume Hupin

2014-04-07T23:59:59.000Z

355

Probing the mass loss history of carbon stars using CO line and dust continuum emission  

E-Print Network [OSTI]

An extensive modelling of CO line emission from the circumstellar envelopes around a number of carbon stars is performed. By combining radio observations and infrared observations obtained by ISO the circumstellar envelope characteristics are probed over a large radial range. In the radiative transfer analysis the observational data are consistently reproduced assuming a spherically symmetric and smooth wind expanding at a constant velocity. The combined data set gives better determined envelope parameters, and puts constraints on the mass loss history of these carbon stars. The importance of dust in the excitation of CO is addressed using a radiative transfer analysis of the observed continuum emission, and it is found to have only minor effects on the derived line intensities. The analysis of the dust emission also puts further constraints on the mass loss rate history. The stars presented here are not likely to have experienced any drastic long-term mass loss rate modulations, at least less than a factor of about 5, over the past thousands of years. Only three, out of nine, carbon stars were observed long enough by ISO to allow a detection of CO far-infrared rotational lines.

F. L. Schoeier; N. Ryde; H. Olofsson

2002-06-05T23:59:59.000Z

356

Beta relaxation in the shear mechanics of equilibrium viscous liquids: Phenomenology and network modeling of the alpha-beta merging region  

E-Print Network [OSTI]

The phenomenology of the beta relaxation process in the shear-mechanical response of glass-forming liquids is summarized and compared to that of the dielectric beta process. Furthermore, we discuss how to model the observations by means of standard viscoelastic modeling elements. Necessary physical requirements to such a model are outlined, and it is argued that physically relevant models must be additive in the shear compliance of the alpha and beta parts. A model based on these considerations is proposed and fitted to data for Polyisobutylene 680.

Bo Jakobsen; Kristine Niss; Claudio Maggi; Niels Boye Olsen; Tage Christensen; Jeppe C. Dyre

2010-05-26T23:59:59.000Z

357

Gradient Plasticity Model and its Implementation into MARMOT  

SciTech Connect (OSTI)

The influence of strain gradient on deformation behavior of nuclear structural materials, such as boby centered cubic (bcc) iron alloys has been investigated. We have developed and implemented a dislocation based strain gradient crystal plasticity material model. A mesoscale crystal plasticity model for inelastic deformation of metallic material, bcc steel, has been developed and implemented numerically. Continuum Dislocation Dynamics (CDD) with a novel constitutive law based on dislocation density evolution mechanisms was developed to investigate the deformation behaviors of single crystals, as well as polycrystalline materials by coupling CDD and crystal plasticity (CP). The dislocation density evolution law in this model is mechanism-based, with parameters measured from experiments or simulated with lower-length scale models, not an empirical law with parameters back-fitted from the flow curves.

Barker, Erin I.; Li, Dongsheng; Zbib, Hussein M.; Sun, Xin

2013-08-01T23:59:59.000Z

358

RATDAMPER - A Numerical Model for Coupling Mechanical and Hydrological Properties within the Disturbed Rock Zone at the Waste Isolation Pilot Plant  

SciTech Connect (OSTI)

A numerical model for predicting damage and permeability in the disturbed rock zone (DRZ) has been developed. The semi-empirical model predicts damage based on a function of stress tensor invariant. For a wide class of problems hydrologic/mechanical coupling is necessary for proper analysis. The RATDAMPER model incorporates dilatant volumetric strain and permeability. The RATDAMPER model has been implemented in a weakly coupled code, which combines a finite element structural code and a finite difference multi-phase fluid flow code. Using the development of inelastic volumetric strain, a value of permeability can be assigned. This flexibility allows empirical permeability functional relationships to be evaluated.

RATH,JONATHAN S.; PFEIFLE,T.W.; HUNSCHE,U.

2000-11-27T23:59:59.000Z

359

Mechanism of methanol synthesis on Cu(100) and Zn/Cu(100) surfaces: Comparative dipped adcluster model study  

SciTech Connect (OSTI)

The mechanism of methanol synthesis from CO{sub 2} and H{sub 2} on Cu(100) and Zn/Cu(100) surfaces was studied using the dipped adcluster model (DAM) combined with ab initio Hartree-Fock (HF) and second-order Moeller-Plesset (MP2) calculations. On clean Cu(100) surface, calculations show that five successive hydrogenations are involved in the hydrogenation of adsorbed CO{sub 2} to methanol, and the intermediates are formate, dioxomethylene, formaldehyde, and methoxy. The rate-limiting step is the hydrogenation of formate to formaldehyde, and the Cu-Cu site is responsible for the reaction on Cu(100). The roles of Zn on Zn/Cu(100) catalyst are to modify the rate-limiting step of the reaction: to lower the activation energies of this step and to stabilize the dioxomethylene intermediate at the Cu-Zn site. The present comparative results indicate that the Cu-Zn site is the active site, which cooperates with the Cu-Cu site to catalyze methanol synthesis on a Cu-based catalyst. Electron transfer from surface to adsorbates is the most important factor in affecting the reactivity of these surface catalysts.

Nakatsuji, Hiroshi; Hu, Zhenming

2000-03-05T23:59:59.000Z

360

A general mechanism for producing scale-invariant perturbations and small non-Gaussianity in ekpyrotic models  

E-Print Network [OSTI]

We explore a new type of entropic mechanism for generating density perturbations in a contracting phase in which there are two scalar fields, but only one has a steep negative potential. This first field dominates the energy density and is the source of the ekpyrotic equation of state. The second field has a negligible potential, but its kinetic energy density is coupled to the first field with a non-linear sigma-model type interaction. We show that for any ekpyrotic equation of state it is possible to choose the potential and the kinetic coupling such that exactly scale-invariant (or nearly scale-invariant) entropy perturbations are produced. The corresponding background solutions are stable, and the bispectrum of the entropy perturbations vanishes as no non-Gaussianity is produced during the ekpyrotic phase. Hence, the only contribution to non-Gaussianity comes from the non-linearity of the conversion process during which entropic perturbations are turned into adiabatic ones, resulting in a local non-Gaussianity parameter $f_{NL} \\sim 5$.

Anna Ijjas; Jean-Luc Lehners; Paul J. Steinhardt

2014-06-06T23:59:59.000Z

Note: This page contains sample records for the topic "mechanics continuum modeling" 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

A multiscale mechanobiological model of bone remodelling predicts site-specific bone loss in the femur during osteoporosis and mechanical disuse  

E-Print Network [OSTI]

We propose a multiscale mechanobiological model of bone remodelling to investigate the site-specific evolution of bone volume fraction across the midshaft of a femur. The model includes hormonal regulation and biochemical coupling of bone cell populations, the influence of the microstructure on bone turnover rate, and mechanical adaptation of the tissue. Both microscopic and tissue-scale stress/strain states of the tissue are calculated from macroscopic loads by a combination of beam theory and micromechanical homogenisation. This model is applied to simulate the spatio-temporal evolution of a human midshaft femur scan subjected to two deregulating circumstances: (i) osteoporosis and (ii) mechanical disuse. Both simulated deregulations led to endocortical bone loss, cortical wall thinning and expansion of the medullary cavity, in accordance with experimental findings. Our model suggests that these observations are attributable to a large extent to the influence of the microstructure on bone turnover rate. Mec...

Lerebours, C; Scheiner, S; Pivonka, P

2015-01-01T23:59:59.000Z

362

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 (OSTI)

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.

NONE

1998-09-01T23:59:59.000Z

363

Detection of the thermal radio continuum emission from the G9.62+0.19-F Hot Core  

E-Print Network [OSTI]

We present new high resolution and high sensitivity multi-frequency VLA radio continuum observations of the G9.62+0.19-F hot molecular core. We detect for the first time faint centimetric radio continuum emission at the position of the core. The centimetric continuum spectrum of the source is consistent with thermal emission from ionised gas. This is the first direct evidence that a newly born massive star is powering the G9.62+0.19-F hot core.

L. Testi; P. Hofner; S. Kurtz; M. Rupen

2000-06-15T23:59:59.000Z

364

18th World Conference on Nondestructive Testing, 16-20 April 2012, Durban, South Africa Multidomain modelling of the magneto-mechanical behaviour of dual-  

E-Print Network [OSTI]

modelling of the magneto-mechanical behaviour of dual- phase steels F MBALLA-MBALLA 1,2 , O HUBERT 1. The dual-phase is a steel composed of ferrite and martensite phases. Each phase can be considered of high performance steels as dual phase (DP) steels has been observed. Steel production involves several

Paris-Sud XI, Université de

365

Electron density and temperature measurement by continuum radiation emitted from weakly ionized atmospheric pressure plasmas  

SciTech Connect (OSTI)

The electron-atom neutral bremsstrahlung continuum radiation emitted from weakly ionized plasmas is investigated for electron density and temperature diagnostics. The continuum spectrum in 450–1000?nm emitted from the argon atmospheric pressure plasma is found to be in excellent agreement with the neutral bremsstrahlung formula with the electron-atom momentum transfer cross-section given by Popovi?. In 280–450?nm, however, a large discrepancy between the measured and the neutral bremsstrahlung emissivities is observed. We find that without accounting for the radiative H{sub 2} dissociation continuum, the temperature, and density measurements would be largely wrong, so that it should be taken into account for accurate measurement.

Park, Sanghoo; Choe, Wonho, E-mail: wchoe@kaist.ac.kr [Department of Physics, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Youn Moon, Se [High-enthalpy Plasma Research Center, Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju 561-756 (Korea, Republic of); Park, Jaeyoung [5771 La Jolla Corona Drive, La Jolla, CA 92037 (United States)

2014-02-24T23:59:59.000Z

366

Quantum Mechanics associated with a Finite Group  

E-Print Network [OSTI]

I describe, in the simplified context of finite groups and their representations, a mathematical model for a physical system that contains both its quantum and classical aspects. The physically observable system is associated with the space containing elements fxf for f an element in the regular representation of a given finite group G. The Hermitian portion of fxf is the Wigner distribution of f whose convolution with a test function leads to a mathematical description of the quantum measurement process. Starting with the Jacobi group that is formed from the semidirect product of the Heisenberg group with its automorphism group SL(2,F{N}) for N an odd prime number I show that the classical phase space is the first order term in a series of subspaces of the Hermitian portion of fxf that are stable under SL(2,F{N}). I define a derivative that is analogous to a pseudodifferential operator to enable a treatment that parallels the continuum case. I give a new derivation of the Schrodinger-Weil representation of the Jacobi group. Keywords: quantum mechanics, finite group, metaplectic. PACS: 03.65.Fd; 02.10.De; 03.65.Ta.

Robert W. Johnson

2006-04-20T23:59:59.000Z

367

On the continuum limit of gauge-fixed compact U(1) lattice gauge theory  

E-Print Network [OSTI]

We investigate the continuum limit of a compact formulation of the lattice U(1) gauge theory in 4 dimensions using a nonperturbative gauge-fixed regularization. We find clear evidence of a continuous phase transition in the pure gauge theory for all values of the gauge coupling (with gauge symmetry restored). When probed with quenched staggered fermions with U(1) charge, the theory clearly has a chiral transition for large gauge couplings. We identify the only possible region in the parameter space where a continuum limit with nonperturbative physics may appear.

Subhasish Basak; Asit K De; Tilak Sinha

2003-11-26T23:59:59.000Z

368

AMEAerospace & Mechanical  

E-Print Network [OSTI]

AMEAerospace & Mechanical Engineering #12;Aerospace and Mechanical Engineers design complex mechanical, thermal, fluidic, acousti- cal, optical, and electronic systems, with char- acteristic sizes space. Aerospace and Mechanical Engineering (AME) students conduct basic and applied research within

Wang, Hai

369

Deliberate Science, Continuum Magazine: Clean Energy Innovation at NREL, Winter 2012 (Book)  

SciTech Connect (OSTI)

This quarterly magazine is dedicated to stepping beyond the technical journals to reveal NREL's vital work in a real-world context for our stakeholders. Continuum provides insights into the latest and most impactful clean energy innovations, while spotlighting those talented researchers and unique facilities that make it all happen. This edition focuses on deliberate science.

Not Available

2012-02-01T23:59:59.000Z

370

Efficient Evaluation of Binding Free Energy Using Continuum Electrostatics Danzhi Huang and Amedeo Caflisch*  

E-Print Network [OSTI]

Efficient Evaluation of Binding Free Energy Using Continuum Electrostatics Solvation Danzhi Huang of the absolute free energy of binding. A predictive accuracy of about 1.0 kcal/mol is obtained for 13 and 29 into proteins of known structure require fast and accurate methods for the evaluation of binding free energies.1

Caflisch, Amedeo

371

Gravity Probe B Experiment in 7D Space-and-Time Continuum  

E-Print Network [OSTI]

This study deals with application of field equations in seven-dimensional space-and-time continuum to calculate geodetic and orbital gyroscope precession. It was demonstrated that unlike the classic theory the assumptions made completely correspond to the Gravity Probe B findings.

Yu. A. Portnov

2012-04-24T23:59:59.000Z

372

Classical Trajectories of the Continuum States of the ${\\cal{PT}}$ symmetric Scarf II potential  

E-Print Network [OSTI]

We apply the factorization technique developed by Kuru et. al. [Ann. Phys. {\\bf 323} (2008) 413] to obtain the exact analytical classical trajectories and momenta of the continuum states of the non Hermitian but ${\\cal{PT}}$ symmetric Scarf II potential. In particular, we observe that the strange behaviour of the quantum version at the spectral singularity has an interesting classical analogue.

Anjana Sinha

2012-06-29T23:59:59.000Z

373

Stiffness Control of a Continuum Manipulator in Contact with a Soft Environment  

E-Print Network [OSTI]

-environment interaction has focused on industrial robots interacting with stiff en- vironments in assembly operations and other manufacturing tasks [1]. In these applications, robot position control is in- feasible since and Pierre E. Dupont, Senior Member, IEEE Abstract-- Stiffness control of a continuum robot can pre- vent

Dupont, Pierre

374

Terahertz atmospheric attenuation and continuum effects David M. Slocum,*a  

E-Print Network [OSTI]

Terahertz atmospheric attenuation and continuum effects David M. Slocum,*a Thomas M. Goyette such as pollution monitoring and detection of energetic chemicals are of particular interest. Although there has been much attention to atmospheric effects over narrow frequency windows, accurate measurements across

Massachusetts at Lowell, University of

375

Initial Tests for an Analog Continuum Correlator for CMB Interferometry Huan T. Tran  

E-Print Network [OSTI]

: Lyman Page Abstract We are proposing to build a high frequency interferometer to study the CMB;2 Initial Tests for an Analog Continuum Correlator for CMB Interferometry Huan T. Tran Abstract We-15) and work below 35 GHz and hence rely heavily on HEMT technology. We are in the initial planning stages

376

ccsd-00001253(version1):8Mar2004 The exploration process of inhomogeneous continuum  

E-Print Network [OSTI]

ccsd-00001253(version1):8Mar2004 The exploration process of inhomogeneous continuum random trees trees. We give a description of the exploration process, a function defined on [0, 1] that encodes increments, exploration process, L´evy process, weak convergence. Mathematics Subject Classification: 60C05

Paris-Sud XI, Université de

377

A Model for the Nonlinear Mechanical Behavior of Asphalt Binders and its Application in Prediction of Rutting Susceptibility  

E-Print Network [OSTI]

The mechanical behavior of asphalt binders is nonlinear. The binders exhibit shear thinning/thickening behavior in steady shear tests and non-proportational behavior in other standard viscoelastic tests such as creep-recovery or stress relaxation...

Srinivasa Parthasarathy, Atul

2013-04-30T23:59:59.000Z

378

Mechanical characterization of lithium-ion battery micro components for development of homogenized and multilayer material models  

E-Print Network [OSTI]

The overall battery research of the Impact and Crashworthiness Laboratory (ICL) at MIT has been focused on understanding the battery's mechanical properties so that individual battery cells and battery packs can be ...

Miller, Kyle M. (Kyle Mark)

2014-01-01T23:59:59.000Z

379

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

SciTech Connect (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

380

Programmable Mechanical Metamaterials  

E-Print Network [OSTI]

We create mechanical metamaterials whose response to uniaxial compression can be programmed by lateral confinement, allowing monotonic, non-monotonic and hysteretic behavior. These functionalities arise from a broken rotational symmetry which causes highly nonlinear coupling of deformations along the two primary axes of these metamaterials. We introduce a soft mechanism model which captures the programmable mechanics, and outline a general design strategy for confined mechanical metamaterials. Finally, we show how inhomogeneous confinement can be explored to create multi stability and giant hysteresis.

Bastiaan Florijn; Corentin Coulais; Martin van Hecke

2014-07-17T23:59:59.000Z

Note: This page contains sample records for the topic "mechanics continuum modeling" 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

CONTINUUM CONTRIBUTIONS TO THE SDO/AIA PASSBANDS DURING SOLAR FLARES  

SciTech Connect (OSTI)

Data from the Multiple EUV Grating Spectrograph component of the Extreme-ultraviolet Variability Experiment (EVE) on board the Solar Dynamics Observatory (SDO) were used to quantify the contribution of continuum emission to each of the extreme ultraviolet (EUV) channels of the Atmospheric Imaging Assembly (AIA), also on SDO, during an X-class solar flare that occurred on 2011 February 15. Both the pre-flare-subtracted EVE spectra and fits to the associated free-free continuum were convolved with the AIA response functions of the seven EUV passbands at 10 s cadence throughout the course of the flare. It was found that 10%-25% of the total emission in the 94 Å, 131 Å, 193 Å, and 335 Å passbands throughout the main phase of the flare was due to free-free emission. Reliable measurements could not be made for the 171 Å channel, while the continuum contribution to the 304 Å channel was negligible due to the presence of the strong He II emission line. Up to 50% of the emission in the 211 Å channel was found to be due to free-free emission around the peak of the flare, while an additional 20% was due to the recombination continuum of He II. The analysis was extended to a number of M- and X-class flares and it was found that the level of free-free emission contributing to both the 171 Å and 211 Å passbands increased with increasing GOES class. These results suggest that the amount of continuum emission that contributes to AIA observations during flares is more significant than stated in previous studies which used synthetic, rather than observed, spectra. These findings highlight the importance of spectroscopic observations carried out in conjunction with those from imaging instruments so that the data are interpreted correctly.

Milligan, Ryan O.; McElroy, Sarah A., E-mail: r.milligan@qub.ac.uk [Astrophysics Research Centre, School of Mathematics and Physics, Queen's University Belfast, University Road, Belfast BT7 1NN (United Kingdom)

2013-11-01T23:59:59.000Z

382

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

383

Discrete element modeling of rock deformation, fracture network development and permeability evolution under hydraulic stimulation  

SciTech Connect (OSTI)

Key challenges associated with the EGS reservoir development include the ability to reliably predict hydraulic fracturing and the deformation of natural fractures as well as estimating permeability evolution of the fracture network with time. We have developed a physics-based rock deformation and fracture propagation simulator by coupling a discrete element model (DEM) for fracturing with a network flow model. In DEM model, 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 and internal load is applied. The natural fractures are represented by a series of connected line segments. Mechanical bonds that intersect with such line segments are removed from the DEM model. A network flow model using conjugate lattice to the DEM network is developed and coupled with the DEM. The fluid pressure gradient exerts forces on individual elements of the DEM network, which therefore deforms the mechanical bonds and breaks them if the deformation reaches a prescribed threshold value. Such deformation/fracturing in turn changes the permeability of the flow network, which again changes the evolution of fluid pressure, intimately coupling the two processes. The intimate coupling between fracturing/deformation of fracture networks and fluid flow makes the meso-scale DEM- network flow simulations necessary in order to accurately evaluate the permeability evolution, 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. Methodology for coupling the DEM model with continuum flow and heat transport models will also be discussed.

Shouchun Deng; Robert Podgorney; Hai Huang

2011-02-01T23:59:59.000Z

384

From Discrete Space-Time to Minkowski Space: Basic Mechanisms, Methods and Perspectives  

E-Print Network [OSTI]

This survey article reviews recent results on fermion system in discrete space-time and corresponding systems in Minkowski space. After a basic introduction to the discrete setting, we explain a mechanism of spontaneous symmetry breaking which leads to the emergence of a discrete causal structure. As methods to study the transition between discrete space-time and Minkowski space, we describe a lattice model for a static and isotropic space-time, outline the analysis of regularization tails of vacuum Dirac sea configurations, and introduce a Lorentz invariant action for the masses of the Dirac seas. We mention the method of the continuum limit, which allows to analyze interacting systems. Open problems are discussed.

Felix Finster

2008-02-22T23:59:59.000Z

385

Hierarchical Models for Batteries: Overview with Some Case Studies  

SciTech Connect (OSTI)

Batteries are complex multiscale systems and a hierarchy of models has been employed to study different aspects of batteries at different resolutions. For the electrochemistry and charge transport, the models span from electric circuits, single-particle, pseudo 2D, detailed 3D, and microstructure resolved at the continuum scales and various techniques such as molecular dynamics and density functional theory to resolve the atomistic structure. Similar analogies exist for the thermal, mechanical, and electrical aspects of the batteries. We have been recently working on the development of a unified formulation for the continuum scales across the electrode-electrolyte-electrode system - using a rigorous volume averaging approach typical of multiphase formulation. This formulation accounts for any spatio-temporal variation of the different properties such as electrode/void volume fractions and anisotropic conductivities. In this talk the following will be presented: The background and the hierarchy of models that need to be integrated into a battery modeling framework to carry out predictive simulations, Our recent work on the unified 3D formulation addressing the missing links in the multiscale description of the batteries, Our work on microstructure resolved simulations for diffusion processes, Upscaling of quantities of interest to construct closures for the 3D continuum description, Sample results for a standard Carbon/Spinel cell will be presented and compared to experimental data, Finally, the infrastructure we are building to bring together components with different physics operating at different resolution will be presented. The presentation will also include details about how this generalized approach can be applied to other electrochemical storage systems such as supercapacitors, Li-Air batteries, and Lithium batteries with 3D architectures.

Pannala, Sreekanth [ORNL; Mukherjee, Partha P [ORNL; Allu, Srikanth [ORNL; Nanda, Jagjit [ORNL; Martha, Surendra K [ORNL; Dudney, Nancy J [ORNL; Turner, John A [ORNL

2012-01-01T23:59:59.000Z

386

Application of the multi-mechanism deformation model for three-dimensional simulations of salt : behavior for the strategic petroleum reserve.  

SciTech Connect (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

387

Multiscale modeling of clay-water systems  

E-Print Network [OSTI]

The engineering properties of soils are highly affected by clay content and clay-water interactions. However, existing macro-scale continuum models have no length scale to describe the evolution of the clay microstructure ...

Ebrahimi, Davoud

2014-01-01T23:59:59.000Z

388

Green's function method for strength function in three-body continuum  

E-Print Network [OSTI]

Practical methods to compute dipole strengths for a three-body system by using a discretized continuum are analyzed. New techniques involving Green's function are developed, either by correcting the tail of the approximate wave function in a direct calculation of the strength function or by using a solution of a driven Schroedinger equation in a summed expression of the strength. They are compared with the complex scaling method and the Lorentz integral transform, also making use of a discretized continuum. Numerical tests are performed with a hyperscalar three-body potential in the hyperspherical-harmonics formalism. They show that the Lorentz integral transform method is less practical than the other methods because of a difficult inverse transform. These other methods provide in general comparable accuracies.

Y. Suzuki; W. Horiuchi; D. Baye

2010-02-10T23:59:59.000Z

389

Continuum resonance induced electromagnetic torque by a rotating plasma response to static resonant magnetic perturbation field  

SciTech Connect (OSTI)

A numerical study is carried out, based on a simple toroidal tokamak equilibrium, to demonstrate the radial re-distribution of the electromagnetic torque density, as a result of a rotating resistive plasma (linear) response to a static resonant magnetic perturbation field. The computed electromagnetic torque peaks at several radial locations even in the presence of a single rational surface, due to resonances between the rotating response, in the plasma frame, and both Alfven and sound continuum waves. These peaks tend to merge together to form a rather global torque distribution, when the plasma resistivity is large. The continuum resonance induced net electromagnetic torque remains finite even in the limit of an ideal plasma.

Liu Yueqiang; Connor, J. W.; Cowley, S. C.; Ham, C. J.; Hastie, R. J.; Hender, T. C. [Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom)

2012-10-15T23:59:59.000Z

390

Developing the Galactic Diffuse Emission Model for the GLAST Large Area Telescope  

SciTech Connect (OSTI)

Diffuse emission is produced in energetic cosmic ray (CR) interactions, mainly protons and electrons, with the interstellar gas and radiation field and contains the information about particle spectra in distant regions of the Galaxy. It may also contain information about exotic processes such as dark matter annihilation, black hole evaporation etc. A model of the diffuse emission is important for determination of the source positions and spectra. Calculation of the Galactic diffuse continuum g-ray emission requires a model for CR propagation as the first step. Such a model is based on theory of particle transport in the interstellar medium as well as on many kinds of data provided by different experiments in Astrophysics and Particle and Nuclear Physics. Such data include: secondary particle and isotopic production cross sections, total interaction nuclear cross sections and lifetimes of radioactive species, gas mass calibrations and gas distribution in the Galaxy (H{sub 2}, H I, H II), interstellar radiation field, CR source distribution and particle spectra at the sources, magnetic field, energy losses, g-ray and synchrotron production mechanisms, and many other issues. We are continuously improving the GALPROP model and the code to keep up with a flow of new data. Improvement in any field may affect the Galactic diffuse continuum g-ray emission model used as a background model by the GLAST LAT instrument. Here we report about the latest improvements of the GALPROP and the diffuse emission model.

Moskalenko, Igor V.; Strong, Andrew W.; Digel, Seth W.; Porter, Troy A.

2007-04-30T23:59:59.000Z

391

Homotypic clusters of transcription factor binding sites: a model system for understanding the physical mechanics of gene expression  

E-Print Network [OSTI]

architectures influence the physical mechanisms that ultimately lead to transcription. A first step towards developing a more mechanistic view of CRE organization is to dissect common and simple organizational patterns [1]. One of themost common CRE build- ing... ,25,26].With this new technology, it is possible to experimentally test how different TF binding site organizations influ- ence gene expression. Even with the development of techniques to synthesize DNA more efficiently, it is still very difficult to study how...

Ezer, Daphne; Zabet, Nicolae Radu; Adryan, Boris

2014-08-01T23:59:59.000Z

392

Fano-type coupling of a bound paramagnetic state with 2D continuum  

SciTech Connect (OSTI)

We analyze an effect of a bound impurity state located at a tunnel distance from a quantum well (QW). The study is focused on the resonance case when the bound state energy lies within the continuum of the QW states. Using the developed theory we calculate spin polarization of 2D holes induced by paramagnetic (Mn) delta-layer in the vicinity of the QW and indirect exchange interaction between two impurities located at a tunnel distance from electron gas.

Rozhansky, I. V. [A.F. Ioffe Physical Technical Institute, 194021 St.Petersburg, Russia and Lappeenranta University of Technology, P.O. Box 20, FI-53851, Lappeenranta (Finland); Averkiev, N. S. [A.F. Ioffe Physical Technical Institute, 194021 St.Petersburg (Russian Federation); Lähderanta, E. [Lappeenranta University of Technology, P.O. Box 20, FI-53851, Lappeenranta (Finland)

2013-12-04T23:59:59.000Z

393

Molecular three-continuum approximation for ionization of H{sub 2} by electron impact  

SciTech Connect (OSTI)

A molecular three-continuum-type approximation is developed to study the (e,2e) reaction for H{sub 2} targets. The molecular nature of the target is treated within the framework of a two-effective-center approximation. The correlate motion of the particles in the final channel of the reaction is taken into account by an adequate product of Coulomb functions. Triple differential cross sections are computed. A good agreement with the available experiments is obtained.

Stia, C.R. [Instituto de Fisica Rosario, CONICET-UNR, Avenida Pellegrini 250, 2000 Rosario (Argentina); Fojon, O.A.; Rivarola, R.D. [Instituto de Fisica Rosario, CONICET-UNR, Avenida Pellegrini 250, 2000 Rosario (Argentina); Escuela de Ciencias Exactas y Naturales, Facultad de Ciencias Exactas, Ingenieria y Agrimensura, Universidad Nacional de Rosario, 2000 Rosario (Argentina); Weck, P.F. [Instituto de Fisica Rosario, CONICET-UNR, Avenida Pellegrini 250, 2000 Rosario (Argentina); Institut de Physique, Laboratoire de Physique Moleculaire et des Collisions, Universite de Metz, Technopole 2000, 1 Boulevard Arago, 57078 Metz Cedex 3 (France); Hanssen, J.; Joulakian, B. [Institut de Physique, Laboratoire de Physique Moleculaire et des Collisions, Universite de Metz, Technopole 2000, 1 Boulevard Arago, 57078 Metz Cedex 3 (France)

2002-11-01T23:59:59.000Z

394

Chaos, Scaling and Existence of a Continuum Limit in Classical Non-Abelian Lattice Gauge Theory  

E-Print Network [OSTI]

We discuss space-time chaos and scaling properties for classical non-Abelian gauge fields discretized on a spatial lattice. We emphasize that there is a ``no go'' for simulating the original continuum classical gauge fields over a long time span since there is a never ending dynamical cascading towards the ultraviolet. We note that the temporal chaotic properties of the original continuum gauge fields and the lattice gauge system have entirely different scaling properties thereby emphasizing that they are entirely different dynamical systems which have only very little in common. Considered as a statistical system in its own right the lattice gauge system in a situation where it has reached equilibrium comes closest to what could be termed a ``continuum limit'' in the limit of very small energies (weak non-linearities). We discuss the lattice system both in the limit for small energies and in the limit of high energies where we show that there is a saturation of the temporal chaos as a pure lattice artifact. ...

Nielsen, Holger Bech; Rugh, S E; Nielsen, Holger Bech; Rugh, Hans Henrik; Rugh, Svend Erik

1996-01-01T23:59:59.000Z

395

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]

in running RCM’s over Greenland to produce high-qualityoutlet glaciers. For Greenland, this detail is specificallyCurrently, no coupled Greenland Ice Sheet model experiment

Schlegel, Nicole-Jeanne

2011-01-01T23:59:59.000Z

396

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

397

Continuum electromechanical modeling of protein-membrane interactions Y. C. Zhou*  

E-Print Network [OSTI]

and topological transformations of membrane are crucial steps in numerous transport and signaling processes of cells, includ- ing cell migration, membrane trafficking, and ion conduc- tance 1­3 . There are various sorting complex required for transport III ESCRT III in- duced membrane budding or protrusion 5

Lu, Benzhuo

398

10.1098/rspa.2004.1282 A continuum anisotropic model  

E-Print Network [OSTI]

momentum balance, ice-thickness distribution evolution equation (Thorndike et al. 1975), constitutive are a constitutive law for sea-ice stress, relating stress to the material properties of sea ice and to internal variables describing the sea-ice state, and equations describ- ing the evolution of these variables. The sea

Feltham, Daniel

399

A triple-continuum pressure-transient model for a naturally fractured vuggy reservoir  

E-Print Network [OSTI]

reservoir. The fraction of oil reserves in a vuggy fracturedcontribute to oil and gas reserves and production [Kossackreserves estimation. Field Examples Pressure transient data from two oil-

2007-01-01T23:59:59.000Z

400

A Force-Based Blending Model for Atomistic-to-Continuum Coupling  

E-Print Network [OSTI]

, for the United States Department of Energy's National Nuclear Security Administration under Contract DE-AC04 balance at points in the bridge region. Simple patch tests and computational experiments are used to study Institute, Troy NY 12180 ({fishj,nuggehal}@ scorec.rpi.edu). Supported in part by the Department of Energy

Bochev, Pavel

Note: This page contains sample records for the topic "mechanics continuum modeling" 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

Hyperelastic continuum modeling of cubic crystals based on first-principles calculations  

E-Print Network [OSTI]

We propose new constitutive equations that capture the low-temperature hyperelastic response of cubic-symmetry single crystals up to large volumetric and deviatoric deformations in the region of stability of the equilibrium ...

Salvetti, Matteo Francesco

2010-01-01T23:59:59.000Z

402

An Effective Continuum Model for the Gas Evolution in Internal Steam Drives  

SciTech Connect (OSTI)

This report examines the gas phase growth from a supersaturated, slightly compressible, liquid in a porous medium, driven by heat transfer and controlled by the application of a constant-rate decline of the system pressure.

Tsimpanogiannis, Ioannis N.; Yortsos, Yanis C.

2002-06-11T23:59:59.000Z

403

Multi-Length Scale-Enriched Continuum-Level Material Model for Kevlar  

E-Print Network [OSTI]

engineering analyses of ballistic/blast impact protective structures made of this type of material do materials and struc- tures. These materials/structures are commonly used in various protective systems whose projectiles (e.g., bullets, mine, IED or turbine fragments, etc.). Development of the aforementioned

Grujicic, Mica

404

Discontinuous Modelling of Crack Propagation in a Gradient-Enhanced Continuum  

E-Print Network [OSTI]

of freedom and with the symmetries Kba #3; Kab, Kbp #3; Kbq #3; Kaq, Kqa #3; Kqb #3; Kpb, Kqp #3; Kqq #3; Kpq and Kaa #3; ? BTu #6; 1 #24; ? #8; DBu d? (27a) Kab #3; ?! BTu #6; 1 #24; ? #8; DBu d? (27b) Kap #3;#23;#24; ? BTu ?? ?? ?? ?e D?Ne d? (27c) Kaq #3... ;#23;#24; ? ! BTu ?? ?? ?? ?e D?Ne d? (27d) Kbb #3; ?! BTu #6; 1 #24; ? #8; DBu d? (27e) Kpa #3;#23;#24; ? NTe ??eq ?? T Bu d? (27f) Kpb #3;#23;#24; ? ! NTe ??eq ?? T Bu d? (27g) Kpp #3; ? NTe Ne BTe cBe d? (27h) Kpq #3; ?! NTe Ne BTe cBe d? ffi (27i...

Simone, A; Wells, G N; Sluys, L J

405

Continuum Mechanics and Thermodynamics vol. 24 pp. 505-513 (2012). H. Gouin A. Muracchini T. Ruggeri  

E-Print Network [OSTI]

, are the specific body force and the heat supply; is the heat conductivity and the scalars and µ are the visco

Paris-Sud XI, Université de

2012-01-01T23:59:59.000Z

406

A unified gas-kinetic scheme for continuum and rarefied flows Kun Xu a,*, Juan-Chen Huang b  

E-Print Network [OSTI]

a Mathematics Department, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong b makes these methods useless in the continuum flow regime, especially in the high Reynolds number flow

Xu, Kun

407

A Hybrid approach to molecular continuum processes combiningGaussian basis functions and the discrete variable representation  

SciTech Connect (OSTI)

Gaussian basis functions, routinely employed in molecular electronic structure calculations, can be combined with numerical grid-based functions in a discrete variable representation to provide an efficient method for computing molecular continuum wave functions. This approach, combined with exterior complex scaling, obviates the need for slowly convergent single-center expansions, and allows one to study a variety of electron-molecule collision problems. The method is illustrated by computation of various bound and continuum properties of H2+.

Rescigno, Thomas N.; Horner, Daniel A.; Yip, Frank L.; McCurdy,C. William

2005-08-29T23:59:59.000Z

408

Processes, mechanisms, parameters, and modeling approaches for partially saturated flow in soil and rock media; Yucca Mountain Site Characterization Project  

SciTech Connect (OSTI)

This report discusses conceptual models and mathematical equations, analyzes distributions and correlations among hydrological parameters of soils and tuff, introduces new path integration approaches, and outlines scaling procedures to model potential-driven fluid flow in heterogeneous media. To properly model the transition from fracture-dominated flow under saturated conditions to matrix-dominated flow under partially saturated conditions, characteristic curves and permeability functions for fractures and matrix need to be improved and validated. Couplings from two-phase flow, heat transfer, solute transport, and rock deformation to liquid flow are also important. For stochastic modeling of alternating units of welded and nonwelded tuff or formations bounded by fault zones, correlations and constraints on average values of saturated permeability and air entry scaling factor between different units need to be imposed to avoid unlikely combinations of parameters and predictions. Large-scale simulations require efficient and verifiable numerical algorithms. New path integration approaches based on postulates of minimum work and mass conservation to solve flow geometry and potential distribution simultaneously are introduced. This verifiable integral approach, together with fractal scaling procedures to generate statistical realizations with parameter distribution, correlation, and scaling taken into account, can be used to quantify uncertainties and generate the cumulative distribution function for groundwater travel times.

Wang, J.S.Y.; Narasimhan, T.N. [Lawrence Berkeley Lab., CA (United States)

1993-06-01T23:59:59.000Z

409

The effect of football helmet energy absorption mechanisms on the mitigation of cervical spinal injuries: a mathematical model  

E-Print Network [OSTI]

. The variables which are used for the mathematical model are as follows: head Head acceleration [ft/sec ] 2 x totso Torso acceleration [ft/sec ] 2 head Head velocity [ft/sec] x torso Torso velocity [ft/sec] Xl?, d Head displacement [ft] mh?d Head mass [ibm...

Yung, Adelino

1995-01-01T23:59:59.000Z

410

The holographic mapping of the Standard Model onto the black hole horizon, Part I: Abelian vector field, scalar field and BEH Mechanism  

E-Print Network [OSTI]

Interactions between outgoing Hawking particles and ingoing matter are determined by gravitational forces and Standard Model interactions. In particular the gravitational interactions are responsible for the unitarity of the scattering against the horizon, as dictated by the holographic principle, but the Standard Model interactions also contribute, and understanding their effects is an important first step towards a complete understanding of the horizon's dynamics. The relation between in- and outgoing states is described in terms of an operator algebra. In this paper, the first of a series, we describe the algebra induced on the horizon by U(1) vector fields and scalar fields, including the case of an Englert-Brout-Higgs mechanism, and a more careful consideration of the transverse vector field components.

G. 't Hooft

2005-04-25T23:59:59.000Z

411

Mechanics, mechanisms, and modeling of the chemical mechanical polishing process  

E-Print Network [OSTI]

The ever-increasing demand for high-performance microelectronic devices has motivated the semiconductor industry to design and manufacture Ultra-Large-Scale Integrated (ULSI) circuits with smaller feature size, higher ...

Lai, Jiun-Yu

2001-01-01T23:59:59.000Z

412

Chaos, Scaling and Existence of a Continuum Limit in Classical Non-Abelian Lattice Gauge Theory  

E-Print Network [OSTI]

We discuss space-time chaos and scaling properties for classical non-Abelian gauge fields discretized on a spatial lattice. We emphasize that there is a ``no go'' for simulating the original continuum classical gauge fields over a long time span since there is a never ending dynamical cascading towards the ultraviolet. We note that the temporal chaotic properties of the original continuum gauge fields and the lattice gauge system have entirely different scaling properties thereby emphasizing that they are entirely different dynamical systems which have only very little in common. Considered as a statistical system in its own right the lattice gauge system in a situation where it has reached equilibrium comes closest to what could be termed a ``continuum limit'' in the limit of very small energies (weak non-linearities). We discuss the lattice system both in the limit for small energies and in the limit of high energies where we show that there is a saturation of the temporal chaos as a pure lattice artifact. Our discussion focuses not only on the temporal correlations but to a large extent also on the spatial correlations in the lattice system. We argue that various conclusions of physics have been based on monitoring the non-Abelian lattice system in regimes where the fields are correlated over few lattice units only. This is further evidenced by comparison with results for Abelian lattice gauge theory. How the real time simulations of the classical lattice gauge theory may reach contact with the real time evolution of (semi-classical aspects of) the quantum gauge theory (e.g. Q.C.D.) is left as an important question to be further examined.

Holger Bech Nielsen; Hans Henrik Rugh; Svend Erik Rugh

1996-11-18T23:59:59.000Z

413

Chaos, scaling and existence of a continuum limit in classical non-Abelian lattice gauge theory  

SciTech Connect (OSTI)

We discuss space-time chaos and scaling properties for classical non-Abelian gauge fields discretized on a spatial lattice. We emphasize that there is a {open_quote}no go{close_quotes} for simulating the original continuum classical gauge fields over a long time span since there is a never ending dynamical cascading towards the ultraviolet. We note that the temporal chaotic properties of the original continuum gauge fields and the lattice gauge system have entirely different scaling properties thereby emphasizing that they are entirely different dynamical systems which have only very little in common. Considered as a statistical system in its own right the lattice gauge system in a situation where it has reached equilibrium comes closest to what could be termed a {open_quotes}continuum limit{close_quotes} in the limit of very small energies (weak non-linearities). We discuss the lattice system both in the limit for small energies and in the limit of high energies where we show that there is a saturation of the temporal chaos as a pure lattice artifact. Our discussion focuses not only on the temporal correlations but to a large extent also on the spatial correlations in the lattice system. We argue that various conclusions of physics have been based on monitoring the non-Abelian lattice system in regimes where the fields are correlated over few lattice units only. This is further evidenced by comparison with results for Abelian lattice gauge theory. How the real time simulations of the classical lattice gauge theory may reach contact with the real time evolution of (semi-classical aspects of) the quantum gauge theory (e.g. Q.C.D.) is left an important question to be further examined.

Nielsen, H.B. [Niels Bohr Inst., Kobenhavn (Denmark); Rugh, H.H. [Univ. of Warwick, Coventry (United Kingdom); Rugh, S.E. [Los Alamos National Lab., NM (United States)

1996-12-31T23:59:59.000Z

414

Addressing the Recalcitrance of Cellulose Degradation through Cellulase Discovery, Nano-scale Elucidation of Molecular Mechanisms, and Kinetic Modeling  

SciTech Connect (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

415

Thermo-mechanical and neutron lifetime modeling and design of Be pebbles in the neutron multiplier for the LIFE engine  

SciTech Connect (OSTI)

Concept designs for the laser-initiated fusion/fission engine (LIFE) include a neutron multiplication blanket containing Be pebbles flowing in a molten salt coolant. These pebbles must be designed to withstand the extreme irradiation and temperature conditions in the blanket to enable a safe and cost-effective operation of LIFE. In this work, we develop design criteria for spherical Be pebbles on the basis of their thermomechanical behavior under continued neutron exposure. We consider the effects of high fluence/fast flux on the elastic, thermal and mechanical properties of nuclear-grade Be. Our results suggest a maximum pebble diameter of 30 mm to avoid tensile failure, coated with an anti-corrosive, high-strength metallic shell to avoid failure by pebble contact. Moreover, we find that the operation temperature must always be kept above 450 C to enable creep to relax the stresses induced by swelling, which we estimate to be at least 16 months if uncoated and up to six years when coated. We identify the sources of uncertainty on the properties used and discuss the advantages of new intermetallic beryllides and their use in LIFE's neutron multiplier. To establish Be-pebble lifetimes with improved confidence, reliable experiments to measure irradiation creep must be performed.

DeMange, P; Marian, J; de Caro, M S; Caro, A

2009-03-16T23:59:59.000Z

416

Quasielastic electron- and neutrino-nucleus scattering in a continuum random phase approximation approach  

E-Print Network [OSTI]

We present a continuum random phase approximation approach to study electron- and neutrino-nucleus scattering cross sections, in the kinematic region where quasielastic scattering is the dominant process. We show the validity of the formalism by confronting inclusive ($e,e'$) cross sections with the available data. We calculate flux-folded cross sections for charged-current quasielastic antineutrino scattering off $^{12}$C and compare them with the MiniBooNE cross-section measurements. We pay special emphasis to the contribution of low-energy nuclear excitations in the signal of accelerator-based neutrino-oscillation experiments.

V. Pandey; N. Jachowicz; T. Van Cuyck; J. Ryckebusch; M. Martini

2015-01-16T23:59:59.000Z

417

Quasielastic electron- and neutrino-nucleus scattering in a continuum random phase approximation approach  

E-Print Network [OSTI]

We present a continuum random phase approximation approach to study electron- and neutrino-nucleus scattering cross sections, in the kinematic region where quasielastic scattering is the dominant process. We show the validity of the formalism by confronting inclusive ($e,e'$) cross sections with the available data. We calculate flux-folded cross sections for charged-current quasielastic antineutrino scattering off $^{12}$C and compare them with the MiniBooNE cross-section measurements. We pay special emphasis to the contribution of low-energy nuclear excitations in the signal of accelerator-based neutrino-oscillation experiments.

Pandey, V; Van Cuyck, T; Ryckebusch, J; Martini, M

2015-01-01T23:59:59.000Z

418

A Cluster of 1.3 cm Continuum Sources in OMC1 South  

E-Print Network [OSTI]

We present sensitive 1.3 cm radio continuum observations of the region OMC1 South (OMC-1S) in Orion using the Very Large Array in its B configuration. We detect eleven radio sources clustered in a $30{''} \\times 30{''}$ region, of which only three had been detected previously at radio wavelengths in deep 3.6 cm observations. The eight new radio sources are compact ($\\theta_s \\leq 0\\rlap.{''}1$) and we set lower limits to their spectral indices, $\\alpha > 0.8 \\pm 0.3$ (with $S_\

Luis A. Zapata; Luis F. Rodriguez; Stanley E. Kurtz; C. R. O'Dell; Paul T. P. Ho

2004-07-01T23:59:59.000Z

419

A damage mechanics based approach to structural deterioration and reliability  

SciTech Connect (OSTI)

Structural deterioration often occurs without perceptible manifestation. Continuum damage mechanics defines structural damage in terms of the material microstructure, and relates the damage variable to the macroscopic strength or stiffness of the structure. This enables one to predict the state of damage prior to the initiation of a macroscopic flaw, and allows one to estimate residual strength/service life of an existing structure. The accumulation of damage is a dissipative process that is governed by the laws of thermodynamics. Partial differential equations for damage growth in terms of the Helmholtz free energy are derived from fundamental thermodynamical conditions. Closed-form solutions to the equations are obtained under uniaxial loading for ductile deformation damage as a function of plastic strain, for creep damage as a function of time, and for fatigue damage as function of number of cycles. The proposed damage growth model is extended into the stochastic domain by considering fluctuations in the free energy, and closed-form solutions of the resulting stochastic differential equation are obtained in each of the three cases mentioned above. A reliability analysis of a ring-stiffened cylindrical steel shell subjected to corrosion, accidental pressure, and temperature is performed.

Bhattcharya, B.; Ellingwood, B. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Civil Engineering

1998-02-01T23:59:59.000Z

420

Mechanism and computational model for Lyman-{alpha}-radiation generation by high-intensity-laser four-wave mixing in Kr-Ar gas  

SciTech Connect (OSTI)

We present a theoretical model combined with a computational study of a laser four-wave mixing process under optical discharge in which the non-steady-state four-wave amplitude equations are integrated with the kinetic equations of initial optical discharge and electron avalanche ionization in Kr-Ar gas. The model is validated by earlier experimental data showing strong inhibition of the generation of pulsed, tunable Lyman-{alpha} (Ly-{alpha}) radiation when using sum-difference frequency mixing of 212.6 nm and tunable infrared radiation (820-850 nm). The rigorous computational approach to the problem reveals the possibility and mechanism of strong auto-oscillations in sum-difference resonant Ly-{alpha} generation due to the combined effect of (i) 212.6-nm (2+1)-photon ionization producing initial electrons, followed by (ii) the electron avalanche dominated by 843-nm radiation, and (iii) the final breakdown of the phase matching condition. The model shows that the final efficiency of Ly-{alpha} radiation generation can achieve a value of {approx}5x10{sup -4} which is restricted by the total combined absorption of the fundamental and generated radiation.

Louchev, Oleg A.; Saito, Norihito; Wada, Satoshi [Advanced Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198 (Japan); Bakule, Pavel [STFC, ISIS Facility, Rutherford Appleton Laboratory, Chilton, Oxfordshire OX11 0QX (United Kingdom); Yokoyama, Koji [Advanced Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198 (Japan); Advanced Meson Science Laboratory, RIKEN Nishina Center, RIKEN, Wako, Saitama 351-0198 (Japan); Ishida, Katsuhiko; Iwasaki, Masahiko [Advanced Meson Science Laboratory, RIKEN Nishina Center, RIKEN, Wako, Saitama 351-0198 (Japan)

2011-09-15T23:59:59.000Z

Note: This page contains sample records for the topic "mechanics continuum modeling" 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

PHYSICAL REVIEW E 83, 021304 (2011) Response of a noncohesive packing of grains to a localized force: Deviation from continuum elasticity  

E-Print Network [OSTI]

commonly used to model the behavior of cohesionless soils in civil engineering or in soil mechanics the mechanical behavior of grain piles, we investigate the response of a noncohesive two-dimensional packing between neighboring grains is generally larger than the number of equilibrium mechanical equations

Clamond, Didier

422

Mechanical Engineering Colloquium September 19, 2014  

E-Print Network [OSTI]

Mechanical Engineering Colloquium September 19, 2014 Macdonald Engineering Building (MD) 267 from 11 - 12 pm Professor Harry Dankowicz Department of Mechanical Science and Engineering University of Illinois, Urbana-Champaign Discontinuity-induced Bifurcations in Models of Mechanical Contact, Capillary

Barthelat, Francois

423

A weak-value model for virtual particles supplying the electric current in graphene: the minimal conductivity and the Schwinger mechanism  

E-Print Network [OSTI]

We propose a model for the electric current in graphene in which electric carriers are supplied by virtual particles allowed by the uncertainty relations. The process to make a virtual particle real is described by a weak value of a group velocity: the velocity is requisite for the electric field to give the virtual particle the appropriate changes of both energy and momentum. With the weak value, we approximately estimate the electric current, considering the ballistic transport of the electric carriers. The current shows the quasi-Ohimic with the minimal conductivity of the order of e^2/h per channel. Crossing a certain ballistic time scale, it is brought to obey the Schwinger mechanism.

Kazuhiro Yokota; Nobuyuki Imoto

2014-07-04T23:59:59.000Z

424

A damage mechanics approach to life prediction for a salt structure  

SciTech Connect (OSTI)

Excavated rooms in natural bedded salt formations are being considered for use as repositories for nuclear waste. It is presumed that deformation of the rooms by creep will lead to loss of structural integrity and affect room life history and seal efficiency. At projected repository temperatures, two possible fracture mechanisms in salt are creep-induced microcracking in triaxial compression and cleavage in tension. Thus, an accurate prediction of room life and seal degradation requires a reliable description of the creep and damage processes. While several constitutive models that treat either creep or fracture in salt are available in the literature, very few models have considered creep and damage in a coupled manner. Previously, Munson and Dawson formulated a set of creep equations for salt based on the consideration of dislocation mechanisms in the creep process. This set of creep equations has been generalized to include continuum, isotropic damage as a fully coupled variable in the response equation. The extended model has been referred to as the Multimechanism Deformation Coupled Fracture (MDCF) model. A set of material constants for the creep and damage terms was deduced based on test data for both clean and argillaceous salt. In this paper, the use of the MDCF model for establishing the failure criteria and for analyzing the creep response of a salt structure is demonstrated. The paper is divided into three parts. A summary of the MDCF model is presented first, which is followed by an evaluation of the MDCF model against laboratory data. Finally, finite-element calculations of the creep and damage response of a salt structure are presented and compared against in-situ field measurements.

Chan, K.S.; Bodner, S.R. [Southwest Research Inst., San Antonio, TX (United States); DeVries, K.L.; Fossum, A.F. [RE/SPEC, Inc., Rapid City, SD (United States); Munson, D.E. [Sandia National Labs., Albuquerque, NM (United States)

1995-03-01T23:59:59.000Z

425

MASTER OF SCIENCE MECHANICAL ENGINEERING  

E-Print Network [OSTI]

MASTER OF SCIENCE IN MECHANICAL ENGINEERING 75 DEVELOPMENT OF A MODEL TO PREDICT AND ASSESS SURFACE Master of Science in Mechanical Engineering-December 2000 Advisors: Charles N. Calvano, Department of Mechanical Engineering David W. Byers, Naval Surface Warfare Center-Carderock Division Survivability has

426

A Deep HST Search for Escaping Lyman Continuum Flux at z~1.3: Evidence for an Evolving Ionizing Emissivity  

E-Print Network [OSTI]

We have obtained deep Hubble Space Telescope far-UV images of 15 starburst galaxies at z~1.3 in the GOODS fields to search for escaping Lyman continuum photons. These are the deepest far-UV images m_{AB}=28.7, 3\\sigma, 1" diameter) over this large an area (4.83 arcmin^2) and provide the best escape fraction constraints for any galaxy at any redshift. We do not detect any individual galaxies, with 3\\sigma limits to the Lyman Continuum (~700 \\AA) flux 50--149 times fainter (in f_nu) than the rest-frame UV (1500 \\AA) continuum fluxes. Correcting for the mean IGM attenuation (factor ~2), as well as an intrinsic stellar Lyman Break (~3), these limits translate to relative escape fraction limits of f_{esc,rel}4 and reionization of the intergalactic medium at z>6. [Abridged

Siana, Brian; Ferguson, Henry C; Brown, Thomas M; Giavalisco, Mauro; Dickinson, Mark; Chary, Ranga-Ram; de Mello, Duilia F; Conselice, Christopher J; Bridge, Carrie R; Gardner, Jonathan P; Colbert, James W; Scarlata, Claudia

2010-01-01T23:59:59.000Z

427

CX-001424: Categorical Exclusion Determination | Department of...  

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

Determination CX-001424: Categorical Exclusion Determination Thermal-Hydrological-Mechanical-Chemical Modeling of Enhanced Geothermal System Reservoirs - Continuum through...

428

Spectroscopic investigation of the vibrational quasi-continuum arising from internal rotation of a methyl group  

SciTech Connect (OSTI)

The goal of this project is to use spectroscopic techniques to investigate in detail phenomena involving the vibrational quasi-continuum in a simple physical system. Acetaldehyde was chosen for the study because: (i) methyl groups have been suggested to be important promotors of intramolecular vibrational relaxation, (ii) the internal rotation of a methyl group is an easily describle large-amplitude motion, which should retain its simple character even at high levels of excitation, and (iii) the aldehyde carbonyl group offers the possibility of both vibrational and electronic probing. The present investigation of the ground electronic state has three parts: (1) understanding the {open_quotes}isolated{close_quotes} internal-rotation motion below, at, and above the top of the torsional barrier, (2) understanding in detail traditional (bond stretching and bending) vibrational fundamental and overtone states, and (3) understanding interactions involving states with multiquantum excitations of at least one of these two kinds of motion.

Hougen, J.T. [NIST, Gaithersburg, MD (United States)

1993-12-01T23:59:59.000Z

429

More on the continuum limit of gauge-fixed compact U(1) lattice gauge theory  

E-Print Network [OSTI]

We have verified various proposals that were suggested in our last paper concerning the continuum limit of a compact formulation of the lattice U(1) pure gauge theory in 4 dimensions using a nonperturbative gauge-fixed regularization. Our study reveals that most of the speculations are largely correct. We find clear evidence of a continuous phase transition in the pure gauge theory at "arbitrarily" large couplings. When probed with quenched staggered fermions with U(1) charge, the theory clearly has a chiral transition for large gauge couplings whose intersection with the phase transition in the pure gauge theory continues to be a promising area for nonperturbative physics. We probe the nature of the continuous phase transition by looking at gauge field propagators in the momentum space and locate the region on the critical manifold where free photons can be recovered.

Asit K. De; Tilak Sinha

2005-06-30T23:59:59.000Z

430

Energy Saving Homes and Buildings, Continuum Magazine, Spring 2014 / Issue 6 (Book)  

SciTech Connect (OSTI)

This issue of Continuum focuses on NREL's research to improve the energy efficiency of residential and commercial buildings. Heating, cooling, and lighting our homes and commercial structures account for more than 70% of all electricity used in the United States. That costs homeowners, businesses, and government agencies more than $400 billion annually, about 40% of our nation's total energy costs. Producing that energy contributes almost 40% of our nation's carbon dioxide emissions.By 2030, an estimated 900 billion square feet of new and rebuilt construction will be developed worldwide, providing an unprecedented opportunity to create efficient, sustainable buildings. Increasing the energy performance of our homes alone could potentially eliminate up to 160 million tons of greenhouse gas emissions and lower residential energy bills by $21 billion annually by the end of the decade.

Not Available

2014-03-01T23:59:59.000Z

431

Mechanical memory  

DOE Patents [OSTI]

A first-in-first-out (FIFO) microelectromechanical memory apparatus (also termed a mechanical memory) is disclosed. The mechanical memory utilizes a plurality of memory cells, with each memory cell having a beam which can be bowed in either of two directions of curvature to indicate two different logic states for that memory cell. The memory cells can be arranged around a wheel which operates as a clocking actuator to serially shift data from one memory cell to the next. The mechanical memory can be formed using conventional surface micromachining, and can be formed as either a nonvolatile memory or as a volatile memory.

Gilkey, Jeffrey C. (Albuquerque, NM); Duesterhaus, Michelle A. (Albuquerque, NM); Peter, Frank J. (Albuquerque, NM); Renn, Rosemarie A. (Albuquerque, NM); Baker, Michael S. (Albuquerque, NM)

2006-05-16T23:59:59.000Z

432

Mechanical memory  

DOE Patents [OSTI]

A first-in-first-out (FIFO) microelectromechanical memory apparatus (also termed a mechanical memory) is disclosed. The mechanical memory utilizes a plurality of memory cells, with each memory cell having a beam which can be bowed in either of two directions of curvature to indicate two different logic states for that memory cell. The memory cells can be arranged around a wheel which operates as a clocking actuator to serially shift data from one memory cell to the next. The mechanical memory can be formed using conventional surface micromachining, and can be formed as either a nonvolatile memory or as a volatile memory.

Gilkey, Jeffrey C. (Albuquerque, NM); Duesterhaus, Michelle A. (Albuquerque, NM); Peter, Frank J. (Albuquerque, NM); Renn, Rosemarie A. (Alburquerque, NM); Baker, Michael S. (Albuquerque, NM)

2006-08-15T23:59:59.000Z

433

Radio-Continuum Emission From The Young Galactic Supernova Remnant G1.9+0.3  

E-Print Network [OSTI]

We present an analysis of a new Australia Telescope Compact Array (ATCA) radio-continuum observation of supernova remnant (SNR) G1.9+0.3, which at an age of $\\sim$181$\\pm$25 years is the youngest known in the Galaxy. We analysed all available radio-continuum observations at 6-cm from the ATCA and the Very Large Array. Using this data we estimate an expansion rate for G1.9+0.3 of 0.563%$\\pm$0.078% per year between 1984 and 2009. We note that in the 1980's G1.9+0.3 expanded somewhat slower (0.484% per year) than more recently (0.641% per year). We estimate that the average spectral index between 20-cm and 6-cm, across the entire SNR is $\\alpha=-0.72\\pm 0.26$ which is typical for younger SNRs. At 6-cm, we detect an average of 6% fractionally polarised radio emission with a peak of 17%$\\pm$3%. The polarised emission follows the contours of the strongest of X-ray emission. Using the new equipartition formula we estimate a magnetic field strength of B$\\approx 273\\mu$G, which to date, is one of the highest magnetic field strength found for any SNR and consistent with G1.9+0.3 being a very young remnant. This magnetic field strength implies a minimum total energy of the synchrotron radiation of E$_{\\textrm{min}} \\approx$ 1.8$\\times$10$^{48}$ ergs.

A. Y. De Horta; M. D. Filipovi?; E. J. Crawford; F. H. Stootman; T. G. Pannuti; L. M. Bozzetto; J. D. Collier; E. R. Sommer; A. R. Kosakowski

2014-08-22T23:59:59.000Z

434

A micro to macro approach to polymer matrix composites damage modeling : final LDRD report.  

SciTech Connect (OSTI)

Capabilities are developed, verified and validated to generate constitutive responses using material and geometric measurements with representative volume elements (RVE). The geometrically accurate RVEs are used for determining elastic properties and damage initiation and propagation analysis. Finite element modeling of the meso-structure over the distribution of characterizing measurements is automated and various boundary conditions are applied. Plain and harness weave composites are investigated. Continuum yarn damage, softening behavior and an elastic-plastic matrix are combined with known materials and geometries in order to estimate the macroscopic response as characterized by a set of orthotropic material parameters. Damage mechanics and coupling effects are investigated and macroscopic material models are demonstrated and discussed. Prediction of the elastic, damage, and failure behavior of woven composites will aid in macroscopic constitutive characterization for modeling and optimizing advanced composite systems.

English, Shawn Allen; Brown, Arthur A.; Briggs, Timothy M.

2013-12-01T23:59:59.000Z

435

Multiscale Modeling of Grain Boundary Segregation and Embrittlement in Tungsten for Mechanistic Design of Alloys for Coal Fired Plants  

SciTech Connect (OSTI)

Based on a recent discovery of premelting-like grain boundary segregation in refractory metals occurring at high temperatures and/or high alloying levels, this project investigated grain boundary segregation and embrittlement in tungsten (W) based alloys. Specifically, new interfacial thermodynamic models have been developed and quantified to predict high-temperature grain boundary segregation in the W-Ni binary alloy and W-Ni-Fe, W-Ni-Ti, W-Ni-Co, W-Ni-Cr, W-Ni-Zr and W-Ni-Nb ternary alloys. The thermodynamic modeling results have been experimentally validated for selected systems. Furthermore, multiscale modeling has been conducted at continuum, atomistic and quantum-mechanical levels to link grain boundary segregation with embrittlement. In summary, this 3-year project has successfully developed a theoretical framework in combination with a multiscale modeling strategy for predicting grain boundary segregation and embrittlement in W based alloys.

Luo, Jian; Tomar, Vikas; Zhou, Naixie; Lee, Hongsuk

2013-06-30T23:59:59.000Z

436

Utility-Scale Future, Continuum Magazine: Clean Energy Innovation at NREL, Spring 2011, Issue 1 Vol. 1  

SciTech Connect (OSTI)

This quarterly magazine is dedicated to stepping beyond the technical journals to reveal NREL's vital work in a real-world context for our stakeholders. Continuum provides insights into the latest and most impactful clean energy innovations, while spotlighting those talented researchers and unique facilities that make it all happen. This edition focuses on creating a utility-scale future.

Not Available

2011-08-01T23:59:59.000Z

437

Spectro-interferometry of the Be star delta Sco: Near-Infrared Continuum and Gas Emission Region Sizes in 2007  

E-Print Network [OSTI]

We present near-infrared H and K-band spectro-interferometric observations of the gaseous disk around the primary Be star in the delta Sco binary system, obtained in 2007 (between periastron passages in 2000 and 2011). Observations using the CHARA/MIRC instrument at H-band resolve an elongated disk with a Gaussian FWHM 1.18 x 0.91 mas. Using the Keck Interferometer, the source of the K-band continuum emission is only marginally spatially resolved, and consequently we estimate a relatively uncertain K-band continuum disk FWHM of 0.7 +/- 0.3 mas. Line emission on the other hand, He1 (2.0583 micron) and Br gamma (2.1657 micron), is clearly detected, with about 10% lower visibilities than those of the continuum. When taking into account the continuum/line flux ratio this translates into much larger sizes for the line emission regions: 2.2 +/- 0.4 mas and 1.9 +/- 0.3 mas for He1 and Br gamma respectively. Our KI data also reveal a relatively flat spectral differential phase response, ruling out significant off-cen...

Millan-Gabet, R; Touhami, Y; Gies, D; Hesselbach, E; Pedretti, E; Thureau, N; Zhao, M; Brummelaar, T ten

2010-01-01T23:59:59.000Z

438

On the continuum radio-spectrum of Cas A: possible evidence of the non-linear particle acceleration  

E-Print Network [OSTI]

Integrated radio-spectrum of Cas A in continuum was analyzed with special emphasis on possible high frequency spectral curvature. We conclude that the most probable scenario is that Planck's new data reveal the imprint of non-linear particle acceleration in the case of this young Galactic supernova remnant (SNR).

Oni?, D

2015-01-01T23:59:59.000Z

439

Accepted to SPIE DSS Conference April 29-May 3, 2013, Baltimore, MD Terahertz atmospheric attenuation and continuum effects  

E-Print Network [OSTI]

Terahertz atmospheric attenuation and continuum effects David M. Slocum,*a Thomas M. Goyette,a Elizabeth J interest in the terahertz frequency region. Applications such as pollution monitoring and detection of energetic chemicals are of particular interest. Although there has been much attention to atmospheric

Massachusetts at Lowell, University of

440

Mechanical fault interaction within the Los Angeles Basin: A two-dimensional analysis using mechanical efficiency  

E-Print Network [OSTI]

Mechanical fault interaction within the Los Angeles Basin: A two-dimensional analysis using mechanical efficiency Michele L. Cooke Geosciences Department, University of Massachusetts-Amherst, Amherst July 2002. [1] Mechanical models examine deformation within eight different structural cross sections

Cooke, Michele

Note: This page contains sample records for the topic "mechanics continuum modeling" 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

Mechanism of Interaction Between the General Anesthetic Halothane and a Model Ion Channel Protein, I: Structural Investigations via X-Ray Reflectivity from Langmuir Monolayers  

SciTech Connect (OSTI)

We previously reported the synthesis and structural characterization of a model membrane protein comprised of an amphiphilic 4-helix bundle peptide with a hydrophobic domain based on a synthetic ion channel and a hydrophilic domain with designed cavities for binding the general anesthetic halothane. In this work, we synthesized an improved version of this halothane-binding amphiphilic peptide with only a single cavity and an otherwise identical control peptide with no such cavity, and applied x-ray reflectivity to monolayers of these peptides to probe the distribution of halothane along the length of the core of the 4-helix bundle as a function of the concentration of halothane. At the moderate concentrations achieved in this study, approximately three molecules of halothane were found to be localized within a broad symmetric unimodal distribution centered about the designed cavity. At the lowest concentration achieved, of approximately one molecule per bundle, the halothane distribution became narrower and more peaked due to a component of {approx}19Angstroms width centered about the designed cavity. At higher concentrations, approximately six to seven molecules were found to be uniformly distributed along the length of the bundle, corresponding to approximately one molecule per heptad. Monolayers of the control peptide showed only the latter behavior, namely a uniform distribution along the length of the bundle irrespective of the halothane concentration over this range. The results provide insight into the nature of such weak binding when the dissociation constant is in the mM regime, relevant for clinical applications of anesthesia. They also demonstrate the suitability of both the model system and the experimental technique for additional work on the mechanism of general anesthesia, some of it presented in the companion parts II and III under this title.

Strzalka, J.; Liu, J; Tronin, A; Churbanova, I; Johansson, J; Blasie, J

2009-01-01T23:59:59.000Z

442

Residential Mechanical Precooling  

SciTech Connect (OSTI)

This research conducted by the Alliance for Residential Building Innovation team evaluated mechanical air conditioner pre-cooling strategies in homes throughout the United States. EnergyPlus modeling evaluated two homes with different performance characteristics in seven climates. Results are applicable to new construction homes and most existing homes built in the last 10 years, as well as fairly efficient retrofitted homes.

German, A.; Hoeschele, M.

2014-12-01T23:59:59.000Z

443

Effect of Pressure Relaxation on the Mechanisms of Short-Pulse Laser Melting Dmitriy S. Ivanov and Leonid V. Zhigilei  

E-Print Network [OSTI]

in a computational study that combines molecular dynamics simulations with a continuum description of the laser laser irradiation. In this Letter we report the results of a molecular dynamics (MD) simulation study excitation and subsequent relaxation of the conduction band electrons. Two competing melting mechanisms

Zhigilei, Leonid V.

444

6When you heat a rubber band, it contracts. If you only know about point particles and ideal gases, this behavior is perplexing. But, a simple classical statistical mechanics model of a chain  

E-Print Network [OSTI]

gases, this behavior is perplexing. But, a simple classical statistical mechanics model of a chain for given N and M. Call the result (N,M). (b) Using Stirling's approximation in the form ln(N!) N ln(N) - N and extent R, in the regime Na >> R. Write down the expression for the free energy of the chain (in

Ha, Taekjip

445

Mechanics of collective unfolding  

E-Print Network [OSTI]

Mechanically induced unfolding of passive crosslinkers is a fundamental biological phenomenon encountered across the scales from individual macro-molecules to cytoskeletal actin networks. In this paper we study a conceptual model of athermal load-induced unfolding and use a minimalistic setting allowing one to emphasize the role of long-range interactions while maintaining full analytical transparency. Our model can be viewed as a description of a parallel bundle of N bistable units confined between two shared rigid backbones that are loaded through a series spring. We show that the ground states in this model correspond to synchronized, single phase configurations where all individual units are either folded or unfolded. We then study the fine structure of the wiggly energy landscape along the reaction coordinate linking the two coherent states and describing the optimal mechanism of cooperative unfolding. Quite remarkably, our study shows the fundamental difference in the size and structure of the folding-u...

Caruel, M; Truskinovsky, L

2015-01-01T23:59:59.000Z

446

Radio Continuum Observations of the Galactic Center: Photoevaporative Proplyd-like Objects near Sgr A*  

E-Print Network [OSTI]

We present radio images within 30$''$ of Sgr A* based on recent VLA observations at 34 GHz with 7.8 microJy sensitivity and resolution $\\sim88\\times46$ milliarcseconds (mas). We report 44 partially resolved compact sources clustered in two regions in the E arm of ionized gas that orbits Sgr A*. These sources have size scales ranging between ~50 and 200 mas (400 to 1600 AUs), and a bow-shock appearance facing the direction of Sgr A*. Unlike the bow-shock sources previously identified in the near-IR but associated with massive stars, these 34 GHz sources do not appear to have near-IR counterparts at 3.8 $\\mu$m. We interpret these sources as a candidate population of photoevaporative protoplanetary disks (proplyds) that are associated with newly formed low mass stars with mass loss rates ~10^{-7} - 10^{-6} solar mass per year and are located at the edge of a molecular cloud outlined by ionized gas. The disks are externally illuminated by strong Lyman continuum radiation from the ~100 OB and WR massive stars dist...

Yusef-Zadeh, F; Wardle, M; Cotton, W; Schödel, R; Royster, M J

2015-01-01T23:59:59.000Z

447

Production of excitons in grazing collisions of protons with LiF surfaces: An onion model  

SciTech Connect (OSTI)

In this work we evaluate the production of excitons of a lithium fluoride crystal induced by proton impact in the intermediate and high energy regime (from 100 keV to 1 MeV). A simple model is proposed to account for the influence of the Coulomb grid of the target by dressing crystal ions to transform them in what we call onions. The excited states of these onions can be interpreted as excitons. Within this model, total cross section and stopping power are calculated by using the first Born and the continuum distorted-wave (CDW) eikonal initial-state (EIS) approximations. We found that between 7 and 30 excitons per incident proton are produced in grazing collisions with LiF surfaces, becoming a relevant mechanism of inelastic transitions.

Miraglia, J. E.; Gravielle, M. S. [Instituto de Astronomia y Fisica del Espacio, Consejo Nacional de Investigaciones Cientificas y Tecnicas and Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Casilla de Correo 67, Sucursal 28, (C1428EGA) Buenos Aires (Argentina)

2011-12-15T23:59:59.000Z

448

Agreement Mechanisms  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsruc Documentation RUCProductstwrmrAre theAdministratorCFM LEAPAgenda AgendaAgreement Mechanisms

449

Subsurface Uranium Fate and Transport: Integrated Experiments and Modeling of Coupled Biogeochemical Mechanisms of Nanocrystalline Uraninite Oxidation by Fe(III)-(hydr)oxides - Project Final Report  

SciTech Connect (OSTI)

Subsurface bacteria including sulfate reducing bacteria (SRB) reduce soluble U(VI) to insoluble U(IV) with subsequent precipitation of UO2. We have shown that SRB reduce U(VI) to nanometer-sized UO2 particles (1-5 nm) which are both intra- and extracellular, with UO2 inside the cell likely physically shielded from subsequent oxidation processes. We evaluated the UO2 nanoparticles produced by Desulfovibrio desulfuricans G20 under growth and non-growth conditions in the presence of lactate or pyruvate and sulfate, thiosulfate, or fumarate, using ultrafiltration and HR-TEM. Results showed that a significant mass fraction of bioreduced U (35-60%) existed as a mobile phase when the initial concentration of U(VI) was 160 µM. Further experiments with different initial U(VI) concentrations (25 - 900 ?M) in MTM with PIPES or bicarbonate buffers indicated that aggregation of uraninite depended on the initial concentrations of U(VI) and type of buffer. It is known that under some conditions SRB-mediated UO2 nanocrystals can be reoxidized (and thus remobilized) by Fe(III)-(hydr)oxides, common constituents of soils and sediments. To elucidate the mechanism of UO2 reoxidation by Fe(III) (hydr)oxides, we studied the impact of Fe and U chelating compounds (citrate, NTA, and EDTA) on reoxidation rates. Experiments were conducted in anaerobic batch systems in PIPES buffer. Results showed EDTA significantly accelerated UO2 reoxidation with an initial rate of 9.5?M day-1 for ferrihydrite. In all cases, bicarbonate increased the rate and extent of UO2 reoxidation with ferrihydrite. The highest rate of UO2 reoxidation occurred when the chelator promoted UO2 and Fe(III) (hydr)oxide dissolution as demonstrated with EDTA. When UO2 dissolution did not occur, UO2 reoxidation likely proceeded through an aqueous Fe(III) intermediate as observed for both NTA and citrate. To complement to these laboratory studies, we collected U-bearing samples from a surface seep at the Rifle field site and have measured elevated U concentrations in oxic iron-rich sediments. To translate experimental results into numerical analysis of U fate and transport, a reaction network was developed based on Sani et al. (2004) to simulate U(VI) bioreduction with concomitant UO2 reoxidation in the presence of hematite or ferrihydrite. The reduction phase considers SRB reduction (using lactate) with the reductive dissolution of Fe(III) solids, which is set to be microbially mediated as well as abiotically driven by sulfide. Model results show the oxidation of HS– by Fe(III) directly competes with UO2 reoxidation as Fe(III) oxidizes HS– preferentially over UO2. The majority of Fe reduction is predicted to be abiotic, with ferrihydrite becoming fully consumed by reaction with sulfide. Predicted total dissolved carbonate concentrations from the degradation of lactate are elevated (log(pCO2) ~ –1) and, in the hematite system, yield close to two orders-of-magnitude higher U(VI) concentrations than under initial carbonate concentrations of 3 mM. Modeling of U(VI) bioreduction with concomitant reoxidation of UO2 in the presence of ferrihydrite was also extended to a two-dimensional field-scale groundwater flow and biogeochemically reactive transport model for the South Oyster site in eastern Virginia. This model was developed to simulate the field-scale immobilization and subsequent reoxidation of U by a biologically mediated reaction network.

Peyton, Brent M. [Montana State University; Timothy, Ginn R. [University of California Davis; Sani, Rajesh K. [South Dakota School of Mines and Technology

2013-08-14T23:59:59.000Z

450

Toward a new paradigm for reactive flow modeling.  

SciTech Connect (OSTI)

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

Schmitt, Robert Gerard

2005-08-01T23:59:59.000Z

451

Constitutive modeling of the finite deformation behavior of membranes possessing a triangulated networked microstructure  

E-Print Network [OSTI]

Many biological, natural and synthetic materials possess a networked or micro-truss-like microstructure. In this thesis work, a general microstructurally-informed continuum level constitutive model of the large stretch ...

Arslan, Melis

2005-01-01T23:59:59.000Z

452

Photometric Trends in the Visible Solar Continuum and Their Sensitivity to the Center-to-Limb Profile  

E-Print Network [OSTI]

Solar irradiance variations over solar rotational time-scales are largely determined by the passage of magnetic structures across the visible solar disk. Variations on solar cycle time scales are thought to be similarly due to changes in surface magnetism with activity. Understanding the contribution of magnetic structures to total solar irradiance and solar spectral irradiance requires assessing their contributions as a function of disk position. Since only relative photometry is possible from the ground, the contrasts of image pixels are measured with respect to a center-to-limb intensity profile. Using nine years of full-disk red and blue continuum images from the Precision Solar Photometric Telescope at the Mauna Loa Solar Observatory (PSPT/MLSO), we examine the sensitivity of continuum contrast measurements to the center-to-limb profile definition. Profiles which differ only by the amount of magnetic activity allowed in the pixels used to determine them yield oppositely signed solar cycle length continuu...

Peck, Courtney

2015-01-01T23:59:59.000Z

453

Eulerian hydrocode modeling of a dynamic tensile extrusion experiment (u)  

SciTech Connect (OSTI)

Eulerian hydrocode simulations utilizing the Mechanical Threshold Stress flow stress model were performed to provide insight into a dynamic extrusion experiment. The dynamic extrusion response of copper (three different grain sizes) and tantalum spheres were simulated with MESA, an explicit, 2-D Eulerian continuum mechanics hydrocode and compared with experimental data. The experimental data consisted of high-speed images of the extrusion process, recovered extruded samples, and post test metallography. The hydrocode was developed to predict large-strain and high-strain-rate loading problems. Some of the features of the features of MESA include a high-order advection algorithm, a material interface tracking scheme and a van Leer monotonic advection-limiting. The Mechanical Threshold Stress (MTS) model was utilized to evolve the flow stress as a function of strain, strain rate and temperature for copper and tantalum. Plastic strains exceeding 300% were predicted in the extrusion of copper at 400 m/s, while plastic strains exceeding 800% were predicted for Ta. Quantitative comparisons between the predicted and measured deformation topologies and extrusion rate were made. Additionally, predictions of the texture evolution (based upon the deformation rate history and the rigid body rotations experienced by the copper during the extrusion process) were compared with the orientation imaging microscopy measurements. Finally, comparisons between the calculated and measured influence of the initial texture on the dynamic extrusion response of tantalum was performed.

Burkett, Michael W [Los Alamos National Laboratory; Clancy, Sean P [Los Alamos National Laboratory

2009-01-01T23:59:59.000Z

454

Nuclear breathing mode in neutron-rich Nickel isotopes: sensitivity to the symmetry energy and the role of the continuum  

E-Print Network [OSTI]

In this new era of radioactive beam facilities, the discovery of novel modes of excitation in nuclei far away from stability represents an area of intense research activity. In addition, these modes of excitation appear to be sensitive to the uncertain density dependence of the symmetry energy. We study the emergence, evolution, and nature of both the soft and giant isoscalar monopole modes as a function of neutron excess in three unstable Nickel isotopes: 56Ni, 68Ni, and 78Ni. The distribution of isoscalar monopole strength is computed in a relativistic random-phase approximation using several accurately calibrated effective interactions. In particular, a non-spectral Green's function approach is adopted that allows for an exact treatment of the continuum without any reliance on discretization. The discretization of the continuum is neither required nor admitted. In the case of 56Ni, the lack of low-energy strength results in a direct correlation between the centroid energy of the giant monopole resonance and the incompressibility coefficient of symmetric nuclear matter. In contrast, the large neutron excess in both 68Ni and 78Ni generates a significant, yet relatively featureless, amount of low-energy strength that is driven by transitions into the continuum. Moreover, the evolution of monopole strength with neutron excess displays sensitivity to the density dependence of the symmetry energy. Our results suggest that future measurements of the distribution of isoscalar monopole strength at radioactive beam facilities using a very long chain of both stable and unstable isotopes could place important constraints on the equation of state of neutron-rich matter and ultimately on the properties of neutron stars. However, given the nature of the low-energy monopole excitations, a proper treatment of the continuum is essential.

J. Piekarewicz

2014-10-14T23:59:59.000Z

455

The Relationship Between the High Energy Continuum and Emission Lines in QSOs: A Low-Redshift Sample  

E-Print Network [OSTI]

Quasar emission lines are sensitive to both the luminosity and shape of the quasars' high energy continuum - primarily in the soft X-ray and the (obscured) extreme ultraviolet. We initiate the first large-scale, multi-line investigation of correlations between the QSO soft X-ray continuum and UV line emission, using an IUE/Einstein sample. We characterize the distributions of line equivalent and velocity widths (EW and FWHM) of 85 QSOs in the IUE atlas of Lanzetta et al. (1993), using a new error analysis for objective, automated line measurements, and contrast measured line parameters to the QSO continuum spectral energy distributions (SEDs). We find significant correlations between EW and UV luminosity (e.g., the well-studied Baldwin effect) for Lya, CIV, HeII, and CIII. EW(CIII) and EW(HeII) show previously unreported correlations with Lx which for CIII appears to be primary. The line ratios CIII/Lya and HeII/Lya both show strongest dependence on Lx. EW(Lya) correlates strongly with spectral slopes \\alpha_{uv} and \\alpha_{ox}, but NOT with Lx. We argue that one simple geometrical interpretation of the Baldwin effect (BEff) as a result of a distribution of disk inclinations is not plausible. The BEff weakens or disappears when line emission is correctly compared to the luminosity in the continuum bandpass relevant to its production, which suggests that the BEff is due to a change in SED with luminosity. Our prediction that no BEff relative to X-ray luminosity should be found for FeII or MgII emission lines, will be tested in a later paper, extended to a wider redshift/luminosity range.

Paul J. Green

1996-03-18T23:59:59.000Z

456

A 3D Orthotropic Strain-Rate Dependent Elastic Damage Material Model.  

SciTech Connect (OSTI)

A three dimensional orthotropic elastic constitutive model with continuum damage and cohesive based fracture is implemented for a general polymer matrix composite lamina. The formulation assumes the possibility of distributed (continuum) damage followed b y localized damage. The current damage activation functions are simply partially interactive quadratic strain criteria . However, the code structure allows for changes in the functions without extraordinary effort. The material model formulation, implementation, characterization and use cases are presented.

English, Shawn Allen

2014-09-01T23:59:59.000Z

457

$K \\rightarrow ??$ $?I=3/2$ decay amplitude in the continuum limit  

E-Print Network [OSTI]

We present new results for the amplitude $A_2$ for a kaon to decay into two pions with isospin $I=2$: Re$A_2 = 1.50(4)_\\mathrm{stat}(14)_\\mathrm{syst}\\times 10^{-8}$ GeV; Im$A_2 = -6.99(20)_\\mathrm{stat}(84)_\\mathrm{syst}\\times 10^{-13}$ GeV. These results were obtained from two ensembles generated at physical quark masses (in the isospin limit) with inverse lattice spacings $a^{-1}=1.728(4)$ GeV and $2.358(7)$ GeV. We are therefore able to perform a continuum extrapolation and hence largely to remove the dominant systematic uncertainty from our earlier results, that due to lattice artefacts. The only previous lattice computation of $K\\to\\pi\\pi$ decays at physical kinematics was performed using an ensemble at a single, rather coarse, value of the lattice spacing ($a^{-1}\\simeq 1.37(1)$ GeV). We confirm the observation that there is a significant cancellation between the two dominant contributions to Re$A_2$ which we suggest is an important ingredient in understanding the $\\Delta I=1/2$ rule, Re$A_0$/Re$A_2\\simeq 22.5$, where the subscript denotes the total isospin of the two-pion final state. Our result for $A_2$ implies that the electroweak penguin contribution to $\\epsilon^\\prime/\\epsilon$ is Re($\\epsilon^\\prime/\\epsilon)_\\textrm{EWP}=-(6.6\\pm 1.0)\\times 10^{-4}$.

T. Blum; P. A. Boyle; N. H. Christ; J. Frison; N. Garron; T. Janowski; C. Jung; C. Kelly; C. Lehner; A. Lytle; R. D. Mawhinney; C. T. Sachrajda; A. Soni; H. Yin; D. Zhang

2015-02-01T23:59:59.000Z

458

The application of high-resolution 3D seismic data to model the distribution of mechanical and hydrogeological properties of a potential host rock for the deep storage of radioactive waste in France  

E-Print Network [OSTI]

In the context of a deep geological repository of high-level radioactive wastes, the French National Radioactive Waste Management Agency (Andra) has conducted an extensive characterization of the Callovo-Oxfordian argillaceous rock and surrounding formations in the Eastern Paris Basin. As part of this project, an accurate 3D seismic derived geological model is needed. The paper shows the procedure used for building the 3D seismic constrained geological model in depth by combining time-to-depth conversion of seismic horizons, consistent seismic velocity model and elastic impedance in time. It also shows how the 3D model is used for mechanical and hydrogeological studies. The 3D seismic field data example illustrates the potential of the proposed depth conversion procedure for estimating density and velocity distributions, which are consistent with the depth conversion of seismic horizons using the Bayesian Kriging method. The geological model shows good agreement with well log data obtained from a reference we...

Mari, Jean-Luc

2014-01-01T23:59:59.000Z

459

Vehicle Technologies Office Merit Review 2014: Coupling of Mechanical Behavior of Cell Components to Electrochemical-Thermal Models for Computer-Aided Engineering of Batteries under Abuse  

Broader source: Energy.gov [DOE]

Presentation given by NREL at 2014 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about coupling of mechanical behavior of cell...

460

Hierarchical Modeling of Activation Mechanisms in the ABL and EGFR Kinase Domains: Thermodynamic and Mechanistic Catalysts of Kinase Activation by Cancer Mutations  

E-Print Network [OSTI]

Structural and functional studies of the ABL and EGFR kinase domains have recently suggested a common mechanism of activation by cancer-causing mutations. However, dynamics and mechanistic aspects of kinase activation by ...

Dixit, Anshuman; Verkhivker, Gennady M.

2009-08-28T23:59:59.000Z

Note: This page contains sample records for the topic "mechanics continuum modeling" 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.


461

The aim of the present work is to propose a new micro-mechanical model in the con-text of the deductive approach used to derive interface models. This model, based on a  

E-Print Network [OSTI]

] to evaluate the global behaviour of the dam- aged HEM-1 defining thus a second equivalent homogeneous medium to model HEM-2 as an interface or a joint. The properties of this joint are deduced from those of the HEM-2 as a composite material formed by units (bricks, natural stones, marble, granite, limestone, concrete block, etc

Paris-Sud XI, Université de

462

adaptive mechanisms regulate: Topics by E-print Network  

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

Alexandra I. Cristea 265 Statistical Mechanics: A Possible Model for Market-based Electric Power Control CiteSeer Summary: Statistical mechanics provides a useful analog for...

463

Qualitative insights on fundamental mechanics  

E-Print Network [OSTI]

The gap between classical mechanics and quantum mechanics has an important interpretive implication: the Universe must have an irreducible fundamental level, which determines the properties of matter at higher levels of organization. We show that the main parameters of any fundamental model must be theory-independent. They cannot be predicted, because they cannot have internal causes. However, it is possible to describe them in the language of classical mechanics. We invoke philosophical reasons in favor of a specific model, which treats particles as sources of real waves. Experimental considerations for gravitational, electromagnetic, and quantum phenomena are outlined.

G. N. Mardari

2006-11-10T23:59:59.000Z

464

Continuum Mech. Thermodyn. DOI 10.1007/s00161-013-0320-y  

E-Print Network [OSTI]

June 2013 / Accepted: 21 August 2013 © Springer-Verlag Berlin Heidelberg 2013 Abstract Heat transfer. Struchtrup (B) Mechanical Engineering, University of Victoria, Victoria, BC, Canada E-mail: struchtr

Struchtrup, Henning

465

A Learning Algorithm for Visual Pose Estimation of Continuum Robots Austin Reiter, Roger E. Goldman, Andrea Bajo, Konstantinos Iliopoulos, Nabil Simaan, and Peter K. Allen  

E-Print Network [OSTI]

-Endoscopic Single-Site surgery [3], and Natural Orifice Transluminal Endoscopic Surgery (NOTES) [4]. Continuum of accuracy due to friction, extension and torsion of their actuation lines, shape discrepancy from nominal

Simaan, Nabil

466

Mechanical & Aerospace Engineering  

E-Print Network [OSTI]

Mechanical & Aerospace Engineering An experimental methodology is presented for mechanism verification of physics-based prognosis of mechanical damage, such as fatigue. The proposed experimental methodology includes multi-resolution in-situ mechanical testing, advanced imaging analysis, and mechanism

467

Upscaling geochemical reaction rates using pore-scale network modeling  

E-Print Network [OSTI]

. To examine the scaling behavior of reaction kinetics, these continuum-scale rates from the network model as a valuable research tool for examining upscaling of geochemical kinetics. The pore-scale model allowsUpscaling geochemical reaction rates using pore-scale network modeling Li Li, Catherine A. Peters

Peters, Catherine A.

468

Numerical modelling of ice sheets, streams, and shelves  

E-Print Network [OSTI]

Numerical modelling of ice sheets, streams, and shelves Ed Bueler Karthaus, September 2012 models can actually help you, the reader, understand the behavior of partic- ular ice flows. Their most numerical codes produce numbers, but we want numbers that actually come from our continuum model. We analyse

Bueler, Ed

469

Hydraulic fracture mechanism in unconsolidated formations.  

E-Print Network [OSTI]

??Most models developed for hydraulic fracturing in unconsolidated sands are based on Linear Elastic Fracture Mechanics (LEFM) and tensile fracture (Mode I fracture). However, in… (more)

Hosseini, Seyed Mehran

2012-01-01T23:59:59.000Z

470

Mildly relativistic X-ray transient 080109 and SN2008D: Towards a continuum from energetic GRB/XRF to ordinary Ibc SN  

E-Print Network [OSTI]

We analyze the hitherto available space-based X-ray data as well as ground-based optical data of the X-ray transient 080109/SN2008D. From the data we suggest that (i) The initial transient (\\lesssim 800 sec) is attributed to the reverse shock emission of a mildly relativistic (\\Gamma \\sim a few) outflow stalled by the dense stellar wind. (ii) The subsequent X-ray afterglow (\\lesssim 2\\times 10^4 sec) can be ascribed to the forward shock emission of the outflow, with a kinetic energy \\sim 10^{46} erg, when sweeping up the stellar wind medium. (iii) The late X-ray flattening (\\gtrsim 2\\times 10^4$ sec) is powered by the fastest non-decelerated component of SN2008D's ejecta. (iv) The local event rate of X-ray transient has a lower limit of \\sim 1.6\\times 10^4 yr^{-1} Gpc^{-3}, indicating a vast majority of X-ray transients have a wide opening angle of \\gtrsim 100 degree. The off-axis viewing model is less likely. (v) Transient 080109/SN2008D may lead to a continuum from GRB-SN to under-luminous GRB-/XRF-SN to X-...

Xu, Dong; Fan, Yi-Zhong

2008-01-01T23:59:59.000Z

471

The Great Observatories Origins Deep Survey: Constraints on the Lyman Continuum Escape Fraction Distribution of Lyman--Break Galaxies at 3.4  

E-Print Network [OSTI]

We use ultra-deep ultraviolet VLT/VIMOS intermediate-band and VLT/FORS1 narrow-band imaging in the GOODS Southern field to derive limits on the distribution of the escape fraction (f_esc) of ionizing radiation for L >~ L*(z=3) Lyman Break Galaxies (LBGs) at redshift 3.4--4.5. Only one LBG, at redshift z=3.795, is detected in its Lyman continuum (LyC; S/N~5.5), the highest redshift galaxy currently known with a direct detection. Its ultraviolet morphology is quite compact (R_eff=0.8, kpc physical). Three out of seven AGN are also detected in their LyC, including one at redshift z=3.951 and z850 = 26.1. From stacked data (LBGs) we set an upper limit to the average f_esc in the range 5%--20%, depending on the how the data are selected (e.g., by magnitude and/or redshift). We undertake extensive Monte Carlo simulations that take into account intergalactic attenuation, stellar population synthesis models, dust extinction and photometric noise in order to explore the moments of the distribution of the escaping radi...

Vanzella, E; Inoue, A; Nonino, M; Fontanot, F; Cristiani, S; Grazian, A; Dickinson, M; Stern, D; Tozzi, P; Giallongo, E; Ferguson, H; Spinrad, H; Boutsia, K; Fontana, A; Rosati, P

2010-01-01T23:59:59.000Z

472

Quasi-bound states and continuum absorption background of polar Al{sub 0.5}Ga{sub 0.5}N/GaN quantum dots  

SciTech Connect (OSTI)

A theoretical interpretation of the photoluminescence excitation spectra of self-organized polar GaN/(Al,Ga)N quantum dots is presented. A numerical method assuming a realistic shape of the dots and including the built-in electric field effects is developed to calculate their energy structure and hence their optical absorption. The electron and hole spectra show the existence of a set of quasi-bound states that does not originate from the wetting layer and plays a crucial role in the observed absorption spectrum of the GaN/(Al,Ga)N dots. Transitions involving these quasi-bound states and wetting layer states give a sufficient explanation for the observed continuum absorption background. The properties of this absorption band, especially its extension, depend strongly on the dot's size. Our simulation provides a natural explanation of the experimental luminescence excitation spectra of ensembles of dots of different heights. Our theoretical model can be convenient for future optical studies including systems with more complicated potentials.

Elmaghraoui, D., E-mail: elmaghraouidonia@yahoo.fr; Triki, M. [Laboratoire de physique de la matière condensé, Faculté des sciences de Tunis, Campus universitaire 2092 El Manar (Tunisia); Jaziri, S. [Laboratoire de physique de la matière condensé, Faculté des sciences de Tunis, Campus universitaire 2092 El Manar (Tunisia); Laboratoire de Physique des Matériaux, Faculté des Sciences de Bizerte 7021 Jarzouna (Tunisia); Leroux, M.; Brault, J. [Centre de Recherche sur l'Hetero-Epitaxie et ses Applications, Centre National de la Recherche Scientifique, Rue B. Gregory, 06560 Valbonne (France)

2014-07-07T23:59:59.000Z

473

ETC With a GIM Mechanism  

E-Print Network [OSTI]

We construct an extended technicolor model of quarks and leptons which preserves a GIM mechanism. Furthermore, there is only a minimal technicolor sector, in accordance with recent precision measurements of electroweak parameters. We also show how to incorporate custodial SU(2) and massless neutrinos into such a model.

L. Randall

1992-10-13T23:59:59.000Z

474

Using path sampling to build better Markovian state models: Predicting the folding rate and mechanism of a tryptophan zipper beta hairpin  

E-Print Network [OSTI]

propose an efficient method for the prediction of protein folding rate constants and mechanisms. We use While experiments can yield a wealth of insight into protein folding, it is difficult for experiments of protein folding. The comparison of the rate prediction with experiment could be used as a test

Snow, Christopher

475

A quantum mechanical derivation of the Schwarzschild radius and its quantum correction using a model density distribution: Skin of a black hole  

E-Print Network [OSTI]

Using a single particle density distribution for a system of self-gravitating particles which ultimately forms a black hole, we from a condensed matter point of view derive the Schwarzschild radius and by including the quantum mechanical exchange energy we find a small correction to the Schwarzschild radius, which we designate as the skin of the black hole.

Subodha Mishra

2007-03-16T23:59:59.000Z

476

Impact of drainage on soil-forming mechanisms in a French Albeluvisol: Input of mineralogical data in mass-balance modelling  

E-Print Network [OSTI]

Impact of drainage on soil-forming mechanisms in a French Albeluvisol: Input of mineralogical data Research on soil pedogenesis has mainly focused on the long-term soil formation and has most often neglected recent soil evolutions in response to human practices. Such recent soil evolutions are however

Paris-Sud XI, Université de

477

Methods for modeling impact-induced reactivity changes in small reactors.  

SciTech Connect (OSTI)

This paper describes techniques for determining impact deformation and the subsequent reactivity change for a space reactor impacting the ground following a potential launch accident or for large fuel bundles in a shipping container following an accident. This technique could be used to determine the margin of subcriticality for such potential accidents. Specifically, the approach couples a finite element continuum mechanics model (Pronto3D or Presto) with a neutronics code (MCNP). DAGMC, developed at the University of Wisconsin-Madison, is used to enable MCNP geometric queries to be performed using Pronto3D output. This paper summarizes what has been done historically for reactor launch analysis, describes the impact criticality analysis methodology, and presents preliminary results using representative reactor designs.

Tallman, Tyler N.; Radel, Tracy E.; Smith, Jeffrey A.; Villa, Daniel L.; Smith, Brandon M. (U. of Wisconsin, Madison, WI); Radel, Ross F.; Lipinski, Ronald J.; Wilson, Paul Philip Hood (U. of Wisconsin, Madison, WI)

2010-10-01T23:59:59.000Z

478

Modeling  

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

an implementation of a single-fluid inter- face model in the ALE-AMR code to simulate surface tension effects. The model does not require explicit information on the physical...

479

Subsidence prediction for the forthcoming TONO UCG project. [Rubble model and block model  

SciTech Connect (OSTI)

The motion of the strata that overlie the TONO UCG Project partial-seam test is calculated using the analyses that have been developed for the prediction of subsidence above coal mines. This purely mechanical analysis of the overburden response to the formation of a void in the underlying coal seam is based on the analysis of two codes. The first is a finite-element code that uses a nonlinear rubble model to describe both the kinematics of roof fall and the continuum behavior of broken and unbroken strata. The second is a block code that treats the overburden as an assemblage of blocks. The equations of motion are solved for each block using an explicit integration operator. As both of these calculations are two-dimensional in nature, they are used to calibrate the semi-empirical, complementary influence function model. This model permits the extension of the two-dimensional analyses to three dimensions by using computationally efficient algorithms. These techniques are calibrated to UCG projects by analyzing the Hoe Creek 3 burn. Their application to the TONO project required the estimation of the lateral extent of the cavity for the partial-seam test. The estimates utilized the projected tons of coal to be removed and two scenarios for the burn sequence. The subsidence analytical techniques were combined with the expected patterns of coal removal to place an upper bound on the surface subsidence that can be anticipated at the TONO UCG site. 9 figures.

Sutherland, H.R.; Hommert, P.J.; Taylor, L.M.; Benzley, S.E.

1983-01-01T23:59:59.000Z

480

Continuum-Limit of the Upper Critical-Field H-Star-C2 for Superconducting Networks  

E-Print Network [OSTI]

H, ($"'"1 (with d the spatial dimension of the network) as the universal limiting behavior of H,*2(T) as T T,u, H 2 0. We demon- strate with several examples that this is not true for networks with low point-group symmetry. We then propose that the above... and infinite superconducting networks; in particular, for infinite periodic networks, they proposed the formula (7.) dH (bulk) (7-) (1) 2 tr&'(T) as the universal behavior of H, 2(T) in the continuum lim- it, i.e., as T T,o and H, 2 0. In the above, d...

Hu, Chia-Ren.

1987-01-01T23:59:59.000Z

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