Nonlocal models in continuum mechanics
Johnson, N.L. [Los Alamos National Lab., NM (United States); Phan-Thien, N. [Sydney Univ., NSW (Australia). Dept. of Mechanical Engineering
1993-09-01T23:59:59.000Z
The recent appearance of nonlocal methods is examined in the light of traditional continuum mechanics. A comparison of nonlocal approaches in the fields of solid and fluid mechanics reveals that no consistent definition of a nonlocal theory has been used. We suggest a definition based on the violation of the principle of local action in continuum mechanics. From the consideration of the implications of a nonlocal theory based on this definition, we conclude that constitutive relations with nonlocal terms can confuse the traditional separation of the roles between conservation laws and constitutive relations. The diversity of motivations for the nonlocal approaches are presented, resulting primarily from deficiencies in numerical solutions to practical problems. To illustrate these concepts, the history of nonlocal terms in the field of viscoelastic fluids is reviewed. A specific example of a viscoelastic constitutive relation that contains a stress diffusion term is applied to a simple shear flow and found not to be a physical description of any known fluid. We conclude by listing questions that should be asked of nonlocal approaches.
Damage and fatigue Continuum damage mechanics modeling
-CLÉS : 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
Ice sheets and their dynamics Continuum thermo-mechanical model of a glacier
Cerveny, Vlastislav
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
Continuum models of deformation mechanisms in nanocrystalline metals
Jérusalem, Antoine, 1979-
2007-01-01T23:59:59.000Z
Nanocrystalline metals are polycrystalline metals with grain sizes in the nanometer range. They have attracted significant interest in recent years due to their unique mechanical and electrical properties. The main objective ...
Polymer Quantum Mechanics and its Continuum Limit
Alejandro Corichi; Tatjana Vukasinac; Jose A. Zapata
2007-08-22T23:59:59.000Z
A rather non-standard quantum representation of the canonical commutation relations of quantum mechanics systems, known as the polymer representation has gained some attention in recent years, due to its possible relation with Planck scale physics. In particular, this approach has been followed in a symmetric sector of loop quantum gravity known as loop quantum cosmology. Here we explore different aspects of the relation between the ordinary Schroedinger theory and the polymer description. The paper has two parts. In the first one, we derive the polymer quantum mechanics starting from the ordinary Schroedinger theory and show that the polymer description arises as an appropriate limit. In the second part we consider the continuum limit of this theory, namely, the reverse process in which one starts from the discrete theory and tries to recover back the ordinary Schroedinger quantum mechanics. We consider several examples of interest, including the harmonic oscillator, the free particle and a simple cosmological model.
A Continuum Coupled Moisture-mechanical Constitutive Model for Asphalt Concrete
Shakiba, Maryam
2013-12-09T23:59:59.000Z
procedure and give insight into the various damage inducing mechanisms in asphalt concrete. In this dissertation, thermo-hygro-mechanical constitutive relationships are developed based on the principle of virtual power and laws of thermodynamics in order...
Applications of Continuum Shell Model
Alexander Volya
2006-05-16T23:59:59.000Z
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.
The continuum and wave mechanics
Collins, Royal Eugene
1954-01-01T23:59:59.000Z
in the realm of our actual experience we find it possi? ble to define operational procedures for observing and 4 , and we A find that these procedures always yield values of ?f and "t . Further? more we always find that the observed values of the position... in our analysis of Classical Mechanics, therefore we now consider the following problem. If we consider w quantities iT HE M gnx DHqMyco and p? quantities-[ yO 4. to be defined by operations can we require that a function yA ? t j exists...
THMC Modeling of EGS Reservoirs ? Continuum through Discontinuum...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Continuum through Discontinuum Representations: Capturing Reservoir Stimulation, Evolution and Induced Seismicity THMC Modeling of EGS Reservoirs Continuum through...
Micro-Continuum Modeling of Nuclear Waste Glass Corrosion
Steefel, Carl
2014-01-01T23:59:59.000Z
21. Grambow, B. (2006). Nuclear waste glasses – How durable?Continuum Modeling of Nuclear Waste Glass Corrosion AugustContinuum Modeling of Nuclear Waste Glass Corrosion Prepared
Tawa, G.J. [Frederick Cancer Research and Development Center, MD (United States); Pratt, L.R.; Martin, R.L. [Los Alamos National Lab., NM (United States)
1996-12-31T23:59:59.000Z
We present a method for computing the electrostatic component of the solvation free energy, {Delta}G{sup el}, of a solute molecule in the presence of solvent modeled as a dielectric continuum. The method is based on an integral form of Poisson`s equation which is solved to obtain a distribution of induced polarization charge at the solute-solvent dielectric interface. The solution of Poisson`s equation is obtained by application of a boundary element procedure. The method is tested by comparing its predictions of {Delta}G{sup el} to exact values for several model problems. The method is then used in a variety of contexts to assess its qualitative prediction ability. It is first combined with a molecular mechanics treatment of the solute to evaluate the effects of aqueous solvent on the conformational equilibria of several small molecules of interest-these are N-methyl acetamide and alanine dipeptide. For both molecules dielectric continuum solvation predicts torsional free energies of solvation that are in accord with other more complete treatments of solvation. The method is then combined with ab initio and semi-empirical molecular orbital theory for the solute. Self consistent reaction field calculations (SCRF) are performed to evaluate the correlation is in general very good. Relative agreement with experiment is best for ions where electrostatics predominate and worst for non-polar neutral molecules were electrostatics are minor. Semi-empirical configuration interaction SCRF calculations are also performed in the presence of solvent in order to determine ground-to-excited state absorption energy shifts for formaldehyde and indole mine ground-to-excited state absorption energy shifts for formaldehyde and indole when placed in water. We find a rough correlation between transition energy shifts and the dipole moments of the initial and final states involved in the transition.
Relativistic R matrix and continuum shell model
J. Grineviciute; Dean Halderson
2014-04-16T23:59:59.000Z
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.
Welling, Lois
1983-01-01T23:59:59.000Z
COVER BY BEV ZUK ILLUSTRATIONS BY BECCA RANDANT CONTINUUM BY LOIS WELLING AVAILABLE FROM: LOIS WELLING 1518 WINSTON DRIVE CHAMPAIGN, ILLINOIS 61821 THIS IS AN AMATEUR PUBLICATION INTENDED SOLELY FOR ENTERTAINMENT PURPOSES AND IS NOT MEANT...
A continuum damage modelling of quasi-static fatigue strength of plain concrete
Paris-Sud XI, UniversitÃ© de
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
Nano-Continuum Modeling of a Nuclear Glass Specimen Altered for 25 Years
Steefel, Carl
2014-01-06T23:59:59.000Z
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.
A Continuum Model for Carbon Nanotube-Infused Polyimides
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
Boyer, Edmond
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
Xiao-Song Wang
2014-07-30T23:59:59.000Z
We propose a fluidic continuum model of vacuum and a sink flow model of microscopic particles. The movements of a microscopic particle driven by a stochastic force was studied based on stochastic mechanics. We show that there exists a generalized Schr\\"{o}dinger equation for the microscopic particle.
Microstructural viscoplastic continuum model for asphalt concrete
Tashman, Laith
2004-09-30T23:59:59.000Z
test. A comprehensive experiment was conducted to systematically determine the model parameters and the evolution laws that describe AC hardening, anisotropy, and damage. The experiment consisted of a set of compressive triaxial strength tests...
A study of discrete and continuum joint modeling techniques
Jung, J.; Brown, S.R.
1992-05-01T23:59:59.000Z
This paper presents the results of a numerical and experimental study in which finite element and discrete element techniques were used to analyze a layered polycarbonate plate model subjected to uniaxial compression. Also, the two analysis techniques were used to compute the response of an eight meter diameter drift in jointed-rock. The drift was subjected to in-situ and far-field induced thermal stresses. The finite element analyses used a continuum rock model to represent the jointed-rock. A comparison of the analyses showed that the finite element continuum joint model consistently predicted less joint slippage than did the discrete element analyses, although far-field displacements compared well.
Equivalent Continuum Modeling for Shock Wave Propagation in Jointed Media
Vorobiev, O; Antoun, T
2009-12-11T23:59:59.000Z
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.
Relativistic Point Coupling Model for Vibrational Excitations in the Continuum
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
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.
Dense Heterogeneous Continuum Model of Two-Phase Explosion Fields
Kuhl, A L; Bell, J B
2010-04-07T23:59:59.000Z
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.
The lipid bilayer at the mesoscale: a physical continuum model
Phillip L. Wilson; Huaxiong Huang; Shu Takagi
2008-02-26T23:59:59.000Z
We study a continuum model of the lipid bilayer based on minimizing the free energy of a mixture of water and lipid molecules. This paper extends previous work by Blom & Peletier (2004) in the following ways. (a) It formulates a more physical model of the hydrophobic effect to facilitate connections with microscale simulations. (b) It clarifies the meaning of the model parameters. (c) It outlines a method for determining parameter values so that physically-realistic bilayer density profiles can be obtained, for example for use in macroscale simulations. Points (a)-(c) suggest that the model has potential to robustly connect some micro- and macroscale levels of multiscale blood flow simulations. The mathematical modelling in point (a) is based upon a consideration of the underlying physics of inter-molecular forces. The governing equations thus obtained are minimized by gradient flows via a novel numerical approach; this enables point (b). The numerical results are shown to behave physically in terms of the effect of background concentration, in contrast to the earlier model which is shown here to not display the expected behaviour. A "short-tail" approximation of the lipid molecules also gives an analytical tool which yields critical values of some parameters under certain conditions. Point (c) involves the first quantitative comparison of the numerical data with physical experimental results.
A non-continuum approach to obtain a macroscopic model for the flow of traffic
Tyagi, Vipin
2007-09-17T23:59:59.000Z
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...
A non-continuum approach to obtain a macroscopic model for the flow of traffic
Tyagi, Vipin
2007-09-17T23:59:59.000Z
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...
Universal iso-density polarizable continuum model for molecular solvents
Gunceler, Deniz
2014-01-01T23:59:59.000Z
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.
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
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.
Sensitivity of the Properties of Ruthenium “Blue Dimer” to Method, Basis Set, and Continuum Model
Ozkanlar, Abdullah; Clark, Aurora E.
2012-05-23T23:59:59.000Z
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.
Title of dissertation: A CONTINUUM MODEL FOR FLOCKING: OBSTACLE AVOIDANCE, EQUILIBRIUM,
Anlage, Steven
ABSTRACT Title of dissertation: A CONTINUUM MODEL FOR FLOCKING: OBSTACLE AVOIDANCE, EQUILIBRIUM, AND STABILITY Nicholas Alexander Mecholsky, Doctor of Philosophy, 2010 Dissertation directed by: Professor of animal groups is a subject of growing attention. In this dissertation, we present a partial- differential
Combined atomistic-continuum modeling of short-pulse laser melting and disintegration of metal films
Zhigilei, Leonid V.
Combined atomistic-continuum modeling of short-pulse laser melting and disintegration of metal Ni and Au films irradiated by a short, from 200 fs to 150 ps, laser pulse are investigated of the inertial stress confinement, realized in the case of short 10 ps laser pulses and strong electron
Continuum modelling of piezoelectromechanical truss beams: an application to vibration damping
Paris-Sud XI, UniversitÃ© de
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
Continuum Models of Carbon Nanotube-Based Composites Using the Boundary Element Method
Liu, Yijun
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
Boyer, Edmond
A LARGE SCALE CONTINUUM-DISCRETE NUMERICAL MODELLING: APPLICATION TO OVERBURDEN DAMAGE OF A SALT damage on top of an underground solution mining, an in-situ experiment is undertaken above a salt cavity in the Lorraine region (NE of France). The overburden overlying the salt cavity is characterized by a competent
Stationary shear ows of dense granular materials : a tentative continuum modelling
-less granular media. Compressibil- ity, dilatancy and Coulomb-like friction are the three basic ingredients Abstract We propose a simple continuum model to interpret the shearing motion of dense, dry and cohesion slow motions with predominance of friction, less dense ones are usually found in vigorous motions
A continuum constitutive model for amorphous metallic materials
Su, Cheng, Ph. D. Massachusetts Institute of Technology
2007-01-01T23:59:59.000Z
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 ...
THMC Modeling of EGS Reservoirs ? Continuum through Discontinuum...
Broader source: Energy.gov (indexed) [DOE]
4.30 in GTP-MYRDD through the determination of influence of chemistry on the slip and seismic attributes of rupturing fractures. * New GTP Goals: "Model the reservoir conductivity...
Continuum-based Multiscale Computational Damage Modeling of Cementitous Composites
Kim, Sun-Myung
2011-08-08T23:59:59.000Z
-damage constitutive model, the effect of the micromechanical properties of concrete, such as aggregate shape, distribution, and volume fraction, the ITZ thickness, and the strength of the ITZ and mortar matrix on the iv tensile behavior of concrete... Page 7.1 2-D Meso-scale Analysis Model of Concrete ................................ 103 7.2 Material Properties of the ITZ and Mortar Matrix ......................... 104 7.3 The Effect of the Aggregate Shape...
Continuum Cascade Model: Branching Random Walk for Traveling Wave
Yoshiaki Itoh
2015-07-15T23:59:59.000Z
The food web is a directed graph in which nodes label species and directed links represent the predation between species. Cascade models generate random food webs. The recursion to obtain the probability distribution of the longest chain length has the solution with traveling wave. We consider a branching random walk to study the asymptotic probability on the wave front.
Puckett, Elbridge Gerry [U.C. Davis, Department of Mathematics; Miller, Gregory Hale [.C. Davis, Department of Chemical Engineering
2012-10-14T23:59:59.000Z
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
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
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.
Continuum Limits for Critical Percolation and Other Stochastic Geometric Models
Michael Aizenman
1998-06-06T23:59:59.000Z
The talk presented at ICMP 97 focused on the scaling limits of critical percolation models, and some other systems whose salient features can be described by collections of random lines. In the scaling limit we keep track of features seen on the macroscopic scale, in situations where the short--distance scale at which the system's basic variables are defined is taken to zero. Among the challenging questions are the construction of the limit, and the explanation of some of the emergent properties, in particular the behavior under conformal maps as discussed in [LPS 94]. A descriptive account of the project, and some related open problems, is found in ref. [A] and in [AB] (joint work with A. Burchard) where tools are developed for establishing a curve--regularity condition which plays a key role in the construction of the limit. The formulation of the scaling limit as a random Web measure permits to formulate the question of uniqueness of measure(s) describing systems of random curves satisfying the conditions of independence, Euclidean invariance, and regularity. The uniqueness question remains open; progress on it could shed light on the purported universality of critical behavior and the apparent conformal invariance of the critical measures. The random Web yields also another perspective on some of the equations of conformal field theory which have appeared in this context, such as the equation proposed by J. Cardy [C].
Continuum Level Formulation and Implementation of a Multi-scale Model for Vanadium
Lawrence Livermore National Laboratory
2009-08-17T23:59:59.000Z
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.
Continuum-kinetic-microscopic model of lung clearance due to core-annular fluid entrainment
Mitran, Sorin, E-mail: mitran@unc.edu
2013-07-01T23:59:59.000Z
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.
Kamerlin, Shina C. L.; Haranczyk, Maciej; Warshel, Arieh
2009-05-01T23:59:59.000Z
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.
Continuum Free-Energy formulation for a class of Lattice Boltzmann multiphase models
M. Sbragaglia; H. Chen; X. Shan; S. Succi
2009-01-29T23:59:59.000Z
It is shown that the Shan-Chen (SC) model for non-ideal lattice fluids can be made compliant with a pseudo free-energy principle by simple addition of a gradient force, whose expression is uniquely specified in terms of the fluid density. This additional term is numerically shown to provide fairly negligible effects on the system evolution during phase-separation. To the best of our knowledge, these important properties of the SC model were not noted before. The approach developed in the present work is based on a continuum analysis: further extensions, more in line with a discrete lattice theory (X. Shan, {\\it Phys Rev E}, {\\bf 77} 066702 (2008)) can be envisaged for the future.
to ferromagnetic shape memory alloys Chad M. Landis Ã Department of Aerospace Engineering and Engineering Mechanics Keywords: Phase transformation Twinning Constitutive behavior Ferromagnetic shape memory material Sensors the magnetic domain wall and the martensite twin boundary in ferromagnetic shape memory alloys
Mechanism of the Cassie-Wenzel transition via the atomistic and continuum string methods
Alberto Giacomello; Simone Meloni; Marcus Mueller; Carlo Massimo Casciola
2014-11-17T23:59:59.000Z
The string method is a general and flexible strategy to compute the most probable transition path for an activated process (rare event). We apply here the atomistic string method in the density field to the Cassie-Wenzel transition, a central problem in the field of superhydrophobicity. We discuss in detail the mechanism of wetting of a submerged hydrophobic cavity of nanometer size and its dependence on the geometry of the cavity. Furthermore, we discuss the algorithmic analogies between the string method and CREaM [Giacomello et al., Phys. Rev. Lett. 109, 226102 (2012)], a method inspired by the string that allows for a faster and simpler computation of the mechanism and of the free-energy profiles of the wetting process. This approach is general and can be employed in mesoscale and macroscopic calculations.
Surveying the Free Energy Landscapes of Continuum Models: Application to Soft Matter Systems
Kusumaatmaja, Halim
2015-01-01T23:59:59.000Z
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.
CONTINUUM MECHANICS (Lecture Notes)
Cerveny, Vlastislav
equation 4.2.5 Entropy inequality 4.2.6 RÂ´esumÂ´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
W. F. Wall
2006-05-25T23:59:59.000Z
Determining temperatures in molecular clouds from ratios of CO rotational lines or from ratios of continuum emission in different wavelength bands suffers from reduced temperature sensitivity in the high-temperature limit. In theory, the ratio of far-IR, submillimeter, or millimeter continuum to that of a 13CO (or C18O) rotational line can place reliable upper limits on the temperature of the dust and molecular gas. Consequently, far-infrared continuum data from the {\\it COBE}/{\\it DIRBE} instrument and Nagoya 4-m $\\cOone$ spectral line data were used to plot 240$\\um$/13CO J=1-0 intensity ratios against 140$\\um$/240$\\um$ dust color temperatures, allowing us to constrain the multiparsec-scale physical conditions in the Orion$ $A and B molecular clouds. The best-fitting models to the Orion clouds consist of two components: a component near the surface of the clouds that is heated primarily by a very large-scale (i.e. $\\sim 1 $kpc) interstellar radiation field and a component deeper within the clouds. The former has a fixed temperature and the latter has a range of temperatures that varies from one sightline to another. The models require a dust-gas temperature difference of 0$\\pm 2 $K and suggest that 40-50% of the Orion clouds are in the form of dust and gas with temperatures between 3 and 10$ $K. These results have a number implications that are discussed in detail in later papers. These include stronger dust-gas thermal coupling and higher Galactic-scale molecular gas temperatures than are usually accepted, an improved explanation for the N(H$_2$)/I(CO) conversion factor, and ruling out one dust grain alignment mechanism.
Internal noise driven generalized Langevin equation from a nonlocal continuum model
Saikat Sarkar; Shubhankar Roy Chowdhury; Debasish Roy; Ram Mohan Vasu
2015-03-10T23:59:59.000Z
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.
Liu, Fang; Kulik, Heather J; Martínez, Todd J
2015-01-01T23:59:59.000Z
The conductor-like polarization model (C-PCM) with switching/Gaussian smooth discretization is a widely used implicit solvation model in chemical simulations. However, its application in quantum mechanical calculations of large-scale biomolecular systems can be limited by computational expense of both the gas phase electronic structure and the solvation interaction. We have previously used graphical processing units (GPUs) to accelerate the first of these steps. Here, we extend the use of GPUs to accelerate electronic structure calculations including C-PCM solvation. Implementation on the GPU leads to significant acceleration of the generation of the required integrals for C-PCM. We further propose two strategies to improve the solution of the required linear equations: a dynamic convergence threshold and a randomized block-Jacobi preconditioner. These strategies are not specific to GPUs and are expected to be beneficial for both CPU and GPU implementations. We benchmark the performance of the new implementat...
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
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.
Broader source: Energy.gov [DOE]
This research will develop a thorough understanding of complex THMC interactions through synthesis, modeling and verification.
Hammes-Schiffer, Sharon
Model Proton-Coupled Electron Transfer Reactions in Solution: Predictions of Rates, Mechanisms isotope effects for proton-coupled electron transfer (PCET) reactions. These studies are based, the solvent is represented as a dielectric continuum, and the active electrons and transferring protons
A triple-continuum pressure-transient model for a naturally fractured vuggy reservoir
2007-01-01T23:59:59.000Z
simulation of naturally fractured reservoirs, Water Resour.model for fissured fractured reservoir, Soc. Pet. Eng. J. ,behavior of naturally fractured reservoirs, Soc. Pet. Eng.
Qu, Zhisong; Fitzgerald, Michael
2015-01-01T23:59:59.000Z
Extending the ideal MHD stability code MISHKA, a new code, MISHKA-A, is developed to study the impact of pressure anisotropy on plasma stability. Based on full anisotropic equilibrium and geometry, the code can provide normal mode analysis with three fluid closure models: the single adiabatic model (SA), the double adiabatic model (CGL) and the incompressible model. A study on the plasma continuous spectrum shows that in low beta, large aspect ratio plasma, the main impact of anisotropy lies in the modification of the BAE gap and the sound frequency, if the q profile is conserved. The SA model preserves the BAE gap structure as ideal MHD, while in CGL the lowest frequency branch does not touch zero frequency at the resonant flux surface where $m+nq=0$, inducing a gap at very low frequency. Also, the BAE gap frequency with bi-Maxwellian distribution in both model becomes higher if $p_\\perp > p_\\parallel$ with a q profile dependency. As a benchmark of the code, we study the m/n=1/1 internal kink mode. Numerical...
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
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.
Doctoral Defense "Thermal-hydro-mechanical model
Kamat, Vineet R.
Doctoral Defense "Thermal-hydro-mechanical model for freezing and thawing soils" Yao Zhang Date been implemented in a finite element system, with a thermal-hydro- mechanical framework being used
Multi-Length Scale-Enriched Continuum-Level Material Model for Kevlar
Grujicic, Mica
/multi-length scale architecture of the material microstructure; (b) nonlinear, rate-dependent and often pressure twisting, interfiber friction/sliding, etc. Material models currently employed in the computational under high-deformation rate, large-strain, and high- pressure loading conditions, the conditions
Keralavarma, Shyam Mohan
2012-02-14T23:59:59.000Z
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...
Georgiou, Georgios
integrated them into our lives.3 Polymer matrix nanocomposites (PNCs), in particular, are hybrid organic Nanocomposite Melts Pavlos S. Stephanou,*, Vlasis G. Mavrantzas,,§ and Georgios C. Georgiou Department) bracket. The model describes the polymer nanocomposite melt at a mesoscopic level by using three fields
The Ionizing Continuum of Quasars
Ari Laor
1998-10-15T23:59:59.000Z
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.
Continuum limits of bistable spring models of carbon nanotube arrays accounting for material damage
T. Blesgen; F. Fraternali; J. R. Raney; A. Amendola; C. Daraio
2011-12-10T23:59:59.000Z
Using chains of bistable springs, a model is derived to investigate the plastic behavior of carbon nanotube arrays with damage. We study the preconditioning effect due to the loading history by computing analytically the stress-strain pattern corresponding to a fatigue-type damage of the structure. We identify the convergence of the discrete response to the limiting case of infinitely many springs, both analytically in the framework of Gamma-convergence, as well as numerically.
MECHANICAL PROPERTY CHARACTERIZATIONS AND PERFORMANCE MODELING OF SOFC SEALS
Koeppel, Brian J.; Vetrano, John S.; Nguyen, Ba Nghiep; Sun, Xin; Khaleel, Mohammad A.
2008-03-26T23:59:59.000Z
This study provides modeling tools for the design of reliable seals for SOFC stacks. The work consists of 1) experimental testing to determine fundamental properties of SOFC sealing materials, and 2) numerical modeling of stacks and sealing systems. The material tests capture relevant temperature-dependent physical and mechanical data needed by the analytical models such as thermal expansion, strength, fracture toughness, and relaxation behavior for glass-ceramic seals and other materials. Testing has been performed on both homogenous specimens and multiple material assemblies to investigate the effect of interfacial reactions. A viscoelastic continuum damage model for a glass-ceramic seal was developed to capture the nonlinear behavior of this material at high temperatures. This model was implemented in the MSC MARC finite element code and was used for a detailed analysis of a planar SOFC stack under thermal cycling conditions. Realistic thermal loads for the stack were obtained using PNNL’s in-house multiphysics solver. The accumulated seal damage and component stresses were evaluated for multiple thermal loading cycles, and regions of high seal damage susceptible to cracking were identified. Selected test results, numerical model development, and analysis results will be presented.
Continuum modeling and simulation of granular flows through their many phases
Sachith Dunatunga; Ken Kamrin
2014-11-20T23:59:59.000Z
We propose and numerically implement a constitutive framework for granular media that allows the material to traverse through its many common phases during the flow process. When dense, the material is treated as a pressure sensitive elasto-viscoplastic solid obeying a yield criterion and a plastic flow rule given by the $\\mu(I)$ inertial rheology of granular materials. When the free volume exceeds a critical level, the material is deemed to separate and is treated as disconnected, stress-free media. A Material Point Method (MPM) procedure is written for the simulation of this model and many demonstrations are provided in different geometries. By using the MPM framework, extremely large strains and nonlinear deformations, which are common in granular flows, are representable. The method is verified numerically and its physical predictions are validated against known results.
DENSE MULTIPHASE FLOW SIMULATION: CONTINUUM MODEL FOR POLY-DISPERSED SYSTEMS USING KINETIC THEORY
Moses Bogere
2011-08-31T23:59:59.000Z
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.
King, Michael J. (Michael James), 1978-
2006-01-01T23:59:59.000Z
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, ...
Regulation mechanisms in spatial stochastic development models
Dmitri Finkelshtein; Yuri Kondratiev
2008-09-04T23:59:59.000Z
The aim of this paper is to analyze different regulation mechanisms in spatial continuous stochastic development models. We describe the density behavior for models with global mortality and local establishment rates. We prove that the local self-regulation via a competition mechanism (density dependent mortality) may suppress a unbounded growth of the averaged density if the competition kernel is superstable.
ASSISTANT PROFESSOR OF MECHANICAL ENGINEERING COMPUTATIONAL MODELING
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
A Process Model of Quantum Mechanics
William Sulis
2014-04-21T23:59:59.000Z
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.
Deinert, Mark
, any continuum approach, for example, Richards's equation or Darcy's law, is problematic at the wetting: The inadequacy of the Richards equation with standard monotonic constitutive relations and hysteretic equations of the Richards equation with standard monotonic constitutive relations and hysteretic equations of state
Rizzo, Robert C.
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
Fukuda, Ryoichi, E-mail: fukuda@ims.ac.jp; Ehara, Masahiro [Institute for Molecular Science and Research Center for Computational Science, 38 Nishigo-naka, Myodaiji, Okazaki 444-8585 (Japan) [Institute for Molecular Science and Research Center for Computational Science, 38 Nishigo-naka, Myodaiji, Okazaki 444-8585 (Japan); Elements Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, Kyoto University Katsura, Kyoto 615-8520 (Japan); Cammi, Roberto, E-mail: roberto.cammi@unipr.it [Dipartimento di Chimica Università di Parma, Viale delle Scienze, 17/A, 1-43100 Parma (Italy)] [Dipartimento di Chimica Università di Parma, Viale delle Scienze, 17/A, 1-43100 Parma (Italy)
2014-02-14T23:59:59.000Z
A perturbative approximation of the state specific polarizable continuum model (PCM) symmetry-adapted cluster-configuration interaction (SAC-CI) method is proposed for efficient calculations of the electronic excitations and absorption spectra of molecules in solutions. This first-order PCM SAC-CI method considers the solvent effects on the energies of excited states up to the first-order with using the zeroth-order wavefunctions. This method can avoid the costly iterative procedure of the self-consistent reaction field calculations. The first-order PCM SAC-CI calculations well reproduce the results obtained by the iterative method for various types of excitations of molecules in polar and nonpolar solvents. The first-order contribution is significant for the excitation energies. The results obtained by the zeroth-order PCM SAC-CI, which considers the fixed ground-state reaction field for the excited-state calculations, are deviated from the results by the iterative method about 0.1 eV, and the zeroth-order PCM SAC-CI cannot predict even the direction of solvent shifts in n-hexane for many cases. The first-order PCM SAC-CI is applied to studying the solvatochromisms of (2,2{sup ?}-bipyridine)tetracarbonyltungsten [W(CO){sub 4}(bpy), bpy = 2,2{sup ?}-bipyridine] and bis(pentacarbonyltungsten)pyrazine [(OC){sub 5}W(pyz)W(CO){sub 5}, pyz = pyrazine]. The SAC-CI calculations reveal the detailed character of the excited states and the mechanisms of solvent shifts. The energies of metal to ligand charge transfer states are significantly sensitive to solvents. The first-order PCM SAC-CI well reproduces the observed absorption spectra of the tungsten carbonyl complexes in several solvents.
Ginovska, Bojana; Camaioni, Donald M.; Dupuis, Michel
2008-07-07T23:59:59.000Z
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.
Modeling-Thermo-electrochemistry, Capacity Degradation and Mechanics...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Modeling-Thermo-electrochemistry, Capacity Degradation and Mechanics with SEI Layer Modeling-Thermo-electrochemistry, Capacity Degradation and Mechanics with SEI Layer 2011 DOE...
A Signal Processing Model of Quantum Mechanics
Chris Thron; Johnny Watts
2012-05-08T23:59:59.000Z
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.
MECHANICAL BEHAVIOUR OF PVC: MODEL EVALUATION
Miroshnychenko, Dmitri
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
Mental Models of Physical Mechanisms and Their
de Kleer, Johan
is that of mechanistic devices, including physical machines, electronic and hydraulic systems, and even hybrids such as electro--mechanical systems. Our top-level goals are: (1) to investigate what it means for a person to understand a complex system, in particular, the mental models that experts form of how a system functions
Fully coupled thermal-mechanical-fluid flow model for nonliner geologic systems
Hart, R.D.
1981-01-01T23:59:59.000Z
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.
Statistical Mechanical Models and Topological Color Codes
H. Bombin; M. A. Martin-Delgado
2007-11-03T23:59:59.000Z
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.
Failure Predictions for VHTR Core Components using a Probabilistic Contiuum Damage Mechanics Model
Fok, Alex
2013-10-30T23:59:59.000Z
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.
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...
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
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.
Mechanical Models of Fault-Related Folding
Johnson, A. M.
2003-01-09T23:59:59.000Z
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).
Continuum Partners | Open Energy Information
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 onYou are now leaving Energy.gov You are now leaving Energy.gov You are beingZealand JumpConceptual Model, clickInformationNew| OpenCongress,ConsolidatedContained Energy JumpContinuum
Human walking model predicts joint mechanics, electromyography and mechanical economy
Endo, Ken
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, ...
Tawa, G.J.; Martin, R.L.; Pratt, L.R.; Russo, T.V. [Los Alamos National Lab., NM (United States)] [Los Alamos National Lab., NM (United States)
1996-02-01T23:59:59.000Z
Electrostatic solvation free energies are calculated using a self consistent reaction field (SCRF) procedure that combines a continuum dielectric model of the solvent with both Hartree-Fock (HF) and density functional theory (DFT) for the solute. Several molecules are studied in aqueous solution. They comprise three groups: nonpolar neutral, polar neutral, and ionic. The calculated values of {Delta}G{sup e1} are sensitive to the atomic radii used to define the solute molecular surface, particularly to the value of the hydrogen radius. However, the values of {Delta}G{sup e1} exhibit reasonable correlation with experiment when a previously determined, physically motivated set of atomic radii were used to define the van der Waals surface of the solute. The standard deviation between theory and experiment is 2.51 kcal/mol for HF and 2.21 kcal/mol for DFT for the 14 molecules examined. The errors with HF or DFT are similar. The relative difference between the calculated values of {Delta}G{sup e1} and experiment is largest for nonpolar neutral molecules, intermediate for polar neutral molecules, and smallest for ions. This is consistent with the expected relative importance of nonelectrostatic contributions to the free energy that are omitted in the model. 92 refs., 4 figs., 6 tabs.
A Conceptual Approach to Two-Scale Constitutive Modelling For Hydro-Mechanical Coupling
Giang D. Nguyen; Abbas El-Zein; Terry Bennett
2014-06-05T23:59:59.000Z
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.
Nguyen, Ba Nghiep; Gao, Fei; Henager, Charles H.; Kurtz, Richard J.
2014-05-01T23:59:59.000Z
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.
Sendova, Tsvetanka Bozhidarova
2009-05-15T23:59:59.000Z
tension to the fracture surfaces and using the appropriate crack surface boundary condition, given by the jump momentum balance, leads to a sharp crack opening profile at the crack tip, in contrast to the classical theory of brittle fracture. However...
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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Science (SC) Environmental Assessments (EA) /EmailMolecularGE,Ozone LayerFES1.TopFMM NEAMS
Huang, Rui
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
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...
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 Eric Sonnenthal (PI) Jonny...
Viscoelastic{Viscoplastic Damage Model for Asphalt Concrete
Graham, Michael A.
2010-10-12T23:59:59.000Z
This thesis presents a continuum model for asphalt concrete incorporating non- linear viscoelasticity, viscoplasticity, mechanically-induced damage and moisture- induced damage. The Schapery single-integral viscoelastic model describes the nonlinear...
A micromechanical model for a viscoelastic cohesive zone
Searcy, Chad Randall, 1972-
1998-01-01T23:59:59.000Z
A micromechanical model for a viscoelastic cohesive aphics. zone is formulated herein. Care has been taken in the construction of a physically-based continuum mechanics model of the damaged region ahead of the crack tip. The homogenization...
Modeling thermal/chemical/mechanical response of energetic materials
Baer, M.R.; Hobbs, M.L.; Gross, R.J. [and others
1995-07-01T23:59:59.000Z
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.
Rock mechanics models evaluation report. [Contains glossary
Not Available
1987-08-01T23:59:59.000Z
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.
NREL: Continuum Magazine - Dan Says
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Dan Says Issue 6 Share this resource Dan Says Photo of Dan Arvizu Energy Saving Homes & Buildings This issue of Continuum focuses on NREL's research to improve the energy...
Atom-to-continuum methods for gaining a fundamental understanding of fracture.
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
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.
Quantum mechanical Hamiltonian models of the computation process
Benioff, P.
1983-01-01T23:59:59.000Z
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.
Model to predict the mechanical behaviour of oriented rigid PVC
Miroshnychenko, Dmitri
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
Modeling Control Mechanisms with Normative Multiagent Systems
van der Torre, Leon
of renewable energy. We apply a conceptual model based on normative multiagent systems (NMAS). We propose to stimulate the production of #12;energy from renewable sources [20]. The ruling involves an obligation for energy sup- pliers to produce evidence of having distributed a certain minimal amount of renewable energy
General coarse-grained red blood cell models: I. Mechanics
Fedosov, Dmitry A; Karniadakis, George E
2009-01-01T23:59:59.000Z
We present a rigorous procedure to derive coarse-grained red blood cell (RBC) models, which lead to accurate mechanical properties of realistic RBCs. Based on a semi-analytic theory linear and non-linear elastic properties of the RBC membrane can be matched with those obtained in optical tweezers stretching experiments. In addition, we develop a nearly stress-free model which avoids a number of pitfalls of existing RBC models, such as non-biconcave equilibrium shape and dependence of RBC mechanical properties on the triangulation quality. The proposed RBC model is suitable for use in many existing numerical methods, such as Lattice Boltzmann, Multiparticle Collision Dynamics, Immersed Boundary, etc.
General coarse-grained red blood cell models: I. Mechanics
Dmitry A. Fedosov; Bruce Caswell; George E. Karniadakis
2009-05-01T23:59:59.000Z
We present a rigorous procedure to derive coarse-grained red blood cell (RBC) models, which lead to accurate mechanical properties of realistic RBCs. Based on a semi-analytic theory linear and non-linear elastic properties of the RBC membrane can be matched with those obtained in optical tweezers stretching experiments. In addition, we develop a nearly stress-free model which avoids a number of pitfalls of existing RBC models, such as non-biconcave equilibrium shape and dependence of RBC mechanical properties on the triangulation quality. The proposed RBC model is suitable for use in many existing numerical methods, such as Lattice Boltzmann, Multiparticle Collision Dynamics, Immersed Boundary, etc.
Mechanisms and models of effective thermal conductivities of nanofluids.
Yu, W.; France, D. M.; Singh, D.; Timofeeva, E. V.; Smith, D. S.; Routbort, J. L.; Univ. of Illinois
2010-08-01T23:59:59.000Z
The physical mechanisms and mathematical models of the effective thermal conductivities of nanofluids have long been of interest to the nanofluid research community because the effective thermal conductivities of nanofluids cannot generally be fully explained and predicted by classical effective medium theories. This review article summarizes considerable progress made on this topic. Specifically, the physical mechanisms and mathematical models of the effective thermal conductivities of nanofluids are reviewed, the potential contributions of those physical mechanisms are evaluated, and the comparisons of the theoretical predictions and experimental data are presented along with opportunities for future research.
Modeling biofilms with dual extracellular electron transfer 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
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.
Modeling Different Failure Mechanisms in Metals
Zhang, Liang
2012-02-14T23:59:59.000Z
. Keeler [1] and Goodwin [2] first introduced the concept of the forming limit diagram (FLD). The FLD plots the limiting major and minor strains that can be achieved along different stress or strain paths. It characterizes the sheet metal formability..., the quadratic yield criterions are still often employed to examine the validity of new models. 6 Keeler and Brazier [7] observed that, for steel sheets, the limiting major strain under plane strain conditions increases with increasing sheet thickness...
Thermo-mechanical structural modelling of FRP composite sandwich panels exposed to fire
Ramroth, William T.
2006-01-01T23:59:59.000Z
CALIFORNIA, SAN DIEGO Thermo-mechanical Structural ModellingABSTRACT OF THE DISSERTATION Thermo-mechanical Structuralpolymer matrix), and thermo-mechanical (structural)
Theoretical Modeling of Mechanical-Electrical Coupling of Carbon Nanotubes
Lu, Jun-Qiang [ORNL; Jiang, Hanqiang [Arizona State University
2008-01-01T23:59:59.000Z
Carbon nanotubes have been studied extensively due to their unique properties, ranging from electrical, mechanical, optical, to thermal properties. The coupling between the electrical and mechanical properties of carbon nanotubes has emerged as a new field, which raises both interesting fundamental problems and huge application potentials. In this article, we will review our recently work on the theoretical modeling on mechanical-electrical coupling of carbon nanotubes subject to various loading conditions, including tension/compression, torsion, and squashing. Some related work by other groups will be also mentioned.
Experimental Verification of a Cracked Fuel Mechanical Model
Williford, R. E.
1982-12-01T23:59:59.000Z
This report describes the results of a series of laboratory experiments conducted to independently verify a model that describes the nonlinear mechanical behavior of cracked fuel in pelletized UO{sub 2}/Zircaloy nuclear fuel rods under normal operating conditions. After a brief description of the analytical model, each experiment is discussed in detail. Experiments were conducted to verify the general behavior and numerical values for the three primary independent modelling parameters (effective crack roughness, effective gap roughness, and total crack length), and to verify the model predictions that the effective Young's moduli for cracked fuel systems were substantially less than those for solid UO{sub 2} pellets. In general, the model parameters and predictions were confirmed, and new insight was gained concerning the complexities of cracked fuel mechanics.
Constitutive modeling of creep of single crystal superalloys
Prasad, Sharat Chand
2006-10-30T23:59:59.000Z
In this work, a constitutive theory is developed, within the context of continuum mechanics, to describe the creep deformation of single crystal superalloys. The con- stitutive model that is developed here is based on the fact that as bodies deform...
Puzzles of Galactic continuum gamma rays
I. V. Moskalenko; A. W. Strong
1998-11-14T23:59:59.000Z
Inverse Compton scattering appears to play a more important role in the diffuse Galactic continuum emission than previously thought, from MeV to GeV energies. We compare models having a large inverse Compton component with EGRET data, and find good agreement in the longitude and latitude distributions at low and high energies. We test an alternative explanation for the >1 GeV gamma-ray excess, the hard nucleon spectrum, using secondary antiprotons and positrons. At lower energies to fit the COMPTEL and OSSE data as diffuse emission requires either a steep upturn in the electron spectrum below 200 MeV or a population of discrete sources.
Continuum Representation for Simulating Discrete Events of Battery Operation
Panchagnula, Mahesh
the discrete events in the cycling studies of lithium-ion batteries as a continuum event has been proposed-order pseudo-two-dimensional lithium-ion battery model that has several coupled and nonlinear partial that are currently fol- lowed for the modeling of charge/discharge cycles of lithium-ion batteries involve different
A continuum theory of thermoelectric bodies and effective properties of thermoelectric composites
Liu, Liping
A continuum theory of thermoelectric bodies and effective properties of thermoelectric composites Science, 2012. Contents 1 Introduction 2 2 A continuum model for thermoelectric bodies 4 2.1 Experimental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.3 A constitutive model for thermoelectric materials . . . . . . . . . . . . . . . . . . . . 6 2
The hydration mechanism of ketene: 15 years later
Nguyen, Minh Tho
the self-consistent reaction field method (SCRF) and the polarizable continuum model (PCM). The hydration
A mechanical model of early salt dome growth
Irwin, Frank Albert
1988-01-01T23:59:59.000Z
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...
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
Non-Thermal Continuum toward SGRB2(N-LMH)
J. M. Hollis; P. R. Jewell; Anthony J. Remijan; F. J. Lovas
2007-03-15T23:59:59.000Z
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.
An Improved Probabilistic Fracture Mechanics Model for Pressurized Thermal Shock
Dickson, T.L.
2001-10-29T23:59:59.000Z
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.
Xu, Zhijie; Fang, Yilin; Scheibe, Timothy D.; Bonneville, Alain
2012-05-15T23:59:59.000Z
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.
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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Saleshttp://www.fnal.gov/directorate/nalcal/nalcal02_07_05_files/nalcal.gifNREL NRELChemicalIndustryIssue 3 Continuum. Clean
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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Saleshttp://www.fnal.gov/directorate/nalcal/nalcal02_07_05_files/nalcal.gifNREL NRELChemicalIndustryIssue 3 Continuum.
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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Saleshttp://www.fnal.gov/directorate/nalcal/nalcal02_07_05_files/nalcal.gifNREL NRELChemicalIndustryIssue 3 Continuum.Spring
Polarizable atomic multipole solutes in a Poisson-Boltzmann continuum Michael J. Schnieders
Ponder, Jay
Polarizable atomic multipole solutes in a Poisson-Boltzmann continuum Michael J. Schnieders in their functional forms. Here the authors describe the theory underlying a newly developed polarizable multipole Poisson-Boltzmann PMPB continuum electrostatics model, which builds on the atomic multipole optimized
Teleoperation Control of a Redundant Continuum Manipulator Using a Non-Redundant Rigid-Link Master
Teleoperation Control of a Redundant Continuum Manipulator Using a Non-Redundant Rigid-Link Master and Walker recently developed a model-based task-space controller for the Octarm continuum manipulator [22 Apoorva D. Kapadia, Ian. D. Walker and Enver Tatlicioglu Abstract: In this paper, teleoperated control
Mechanical reaction-diffusion model for bacterial population dynamics
Ngamsaad, Waipot
2015-01-01T23:59:59.000Z
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.
Comprehensive mechanisms for combustion chemistry: Experiment, modeling, and sensitivity analysis
Dryer, F.L.; Yetter, R.A. [Princeton Univ., NJ (United States)
1993-12-01T23:59:59.000Z
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.
On a Model of Quantum Mechanics and the Mind
J. Acacio de Barros
2014-04-16T23:59:59.000Z
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.
A mechanical model of early salt dome growth
Irwin, Frank Albert
1988-01-01T23:59:59.000Z
salt and the upper layer representing the overlying sediment, is used to study the mechanics of growth in the early stages of salt dome formation. Three cases of this model, each representing a particular rate of removal of the surface topography..., are examined to determine which case best fits observations of salt domes in East Texas, Northwest Germany, and the North Sea. These observations include the spacing and growth rate of the dome and the amount of deformation of the sediments above the dome...
Continuum limit of lattice gas fluid dynamics
Teixeira, C.M.
1992-01-01T23:59:59.000Z
The general theory for multiple-speed lattice gas algorithm (LGAs) is developed where previously only a single-speed theory existed. A series of microdynamical multiple-speed models are developed that effectively erase the underlying lattice from the macroscopic dynamics allowing the LGA to reproduce the results of continuum hydrodynamics exactly. The underlying lattice is the 4D FCHC lattice. This lattice: (1) Permits all integral energies, (2) Has sufficient symmetry to allow for an isotropic stress tensor for each energy individually, (3) Allows interaction amongst all energies, and (4) Has discrete microscopic Galilean invariance, all of which allows the extension of the model to higher-speeds. This lattice is the only regular lattice with these remarkable properties, all of which are required to show that the discreteness artifacts completely disappear from the LGA in the limit of infinite speeds, so that correct continuum hydrodynamic behavior results. The author verifies the removal of the discreteness artifacts from the momentum equation using a decaying shear wave experiment and shows they are still invisible for Mach numbers up to M [approximately].4 beyond the theoretical limit. Flow between flat plates replicated the expected parabolic profile of Poiseuille flow in the mean when started from rest. Two separate measurements of the kinematic viscosity of the fluid (normal pressure drop and the microscopic particle force at the wall) agreed with each other and with the shear wave viscosity to better than 1%. Cylinder flow simulations accurately reproduced drag coefficients and eddy-length to diameter ratios for Re[le]45 to within the error of experimental observation. At higher Reynolds number, Re [approx equal] 65, vortex shedding was observed to occur. CFD results for flow past cylinders at similar Reynolds numbers produce either erroneous results or rely on artificially perturbing the flow to cause phenomena that does not occur naturally in the method.
Modeling the Q-cycle mechanism of transmembrane energy conversion
Anatoly Yu. Smirnov; Franco Nori
2011-06-29T23:59:59.000Z
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.
N + 1 dimensional quantum mechanical model for a closed universe
T. R. Mongan
1999-02-10T23:59:59.000Z
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.
Mechanical modeling of the growth of salt structures
Alfaro, R.A.M.
1993-05-01T23:59:59.000Z
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.
3.021J / 1.021J / 10.333J / 18.361J / 22.00J Introduction to Modeling and Simulation, Spring 2011
Buehler, Markus
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 ...
A computational contact model for nanoscale rubber adhesion Roger A. Sauer
A computational contact model for nanoscale rubber adhesion Roger A. Sauer Institute for Continuum Mechanics, Leibniz UniversitÂ¨at Hannover, Germany published in Constitutive Models for Rubber VI, G mechanical contact model which is capable of describing and simulating rubber adhesion at the nanometer scale
A Mechanical Model for CCK-Induced Acalculous Gallbladder Pain
unknown authors
2010-01-01T23:59:59.000Z
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%.
Free Body Analysis, Beam Mechanics, and Finite Element Modeling of the Mandible of Alligator
Free Body Analysis, Beam Mechanics, and Finite Element Modeling of the Mandible of Alligator arm mechanics, 2D and 3D beam mod- els, and three high-resolution finite element models- pared with the beam models, the Alligator finite element models exhibited less spatial variability
Title: Hydraulic modeling of a mixed water level control hydro-mechanical gate
Paris-Sud XI, UniversitÃ© de
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
Deployment Mechanism Design with Behavioral Modeling Based on Pro/Engineer Motion Skeleton
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
Unitary dilation models of Turing machines in quantum mechanics
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
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.
element modelling of a hypothetical underground carbon dioxide (CO2) storage operation. The hydro-mechanical properties of the materials modelled are chosen to be representative of a potential injection site. For high on the injection process, and on site and rock properties. Rutqvist et al. (2008) showed through a coupled
Design and modeling of carbon nanotube-based compliant mechanisms
DiBiasio, Christopher M. (Christopher Michael)
2007-01-01T23:59:59.000Z
The objective of this research is to generate the knowledge required to adapt macro- and microscale compliant mechanism theory to design carbon nanotube-based nano-scale compliant mechanisms. Molecular simulations of a ...
Amination of Ketenes: Evidence for a Mechanism Involving Enols of Amides as Intermediates
Nguyen, Minh Tho
effects are modeled by different methods: Onsager SCRF, PCM, and SCI-PCM electrostatic continuum solvation
The Near-Ultraviolet Continuum of Late-Type Stars
Carlos Allende Prieto; David L. Lambert
2000-01-28T23:59:59.000Z
Analyses of the near-ultraviolet continuum of late-type stars have led to controversial results regarding the performance of state-of-the-art model atmospheres. The release of the homogeneous IUE final archive and the availability of the high-accuracy Hipparcos parallaxes provide an opportunity to revisit this issue, as accurate stellar distances make it possible to compare observed absolute fluxes with the predictions of model atmospheres. The near-UV continuum is highly sensitive to Teff and [Fe/H], and once the gravity is constrained from the parallax, these parameters may be derived from the analysis of low-dispersion "long-wavelength" (2000-3000 A) IUE spectra for stars previously studied by Alonso et al. (1996; A&AS 117, 227) using the Infrared Flux Method (IRFM). A second comparison is carried out against the stars spectroscopically investigated by Gratton et al. (1996; A&A 314, 191). It is shown that there is a good agreement between Teffs obtained from the IRFM and from the near-UV continuum, and a remarkable correspondence between observed and synthetic fluxes for stars with 4000 <= Teff <= 6000 K of any metallicity and gravity. These facts suggest that model atmospheres provide an adequate description of the near-UV continuum forming region and that the opacities involved are essentially understood. For cooler stars, the results of the IRFM are no longer reliable, as shown by Alonso et al., but the discrepancy noticed for stars hotter than 6000 K may reflect problems in the model atmospheres and/or the opacities at these higher temperatures.
Modeling genome-wide replication kinetics reveals a mechanism for regulation of replication timing
Bechhoefer, John
Modeling genome-wide replication kinetics reveals a mechanism for regulation of replication timing, University of Massachusetts Medical School, Worcester, MA, USA * Corresponding author. Department of Physics, testable, biochemically plausible mechanism for the regulation of replication timing in eukaryotes
Song, Jing, 1972-
2004-01-01T23:59:59.000Z
Building proper reaction mechanisms is crucial to model the system dynamic properties for many industrial processes with complex chemical reaction phenomena. Because of the complexity of a reaction mechanism, computer-aided ...
Extending the nuclear chart by continuum: from oxygen to titanium
Qu, Xiaoying; Zhang, Shuangquan; Zhao, Pengwei; Shin, Ik Jae; Lim, Yeunhwan; Kim, Youngman; Meng, Jie
2013-01-01T23:59:59.000Z
Nuclear masses ranging from O to Ti isotopes are systematically investigated with relativistic continuum Hartree-Bogoliubov (RCHB) theory, which can provide a proper treatment of pairing correlations in the presence of the continuum. From O to Ti isotopes, there are 402 nuclei predicted to be bound by the density functional PC-PK1. For the 234 nuclei with mass measured, the root mean square (rms) deviation is 2.23 MeV. It is found that the proton drip-lines predicted with various mass models are roughly the same and basically agree with the observation. The neutron drip-lines predicted, however, are quite different. Due to the continuum couplings, the neutron drip-line nuclei predicted are extended further neutron-rich than other mass models. By comparison with finite-range droplet model (FRDM), the neutron drip-line nucleus predicted by RCHB theory has respectively 2(O), 10(Ne), 10(Na), 6(Mg), 8(Al), 6(Si), 8(P), 6(S), 14(K), 10(Ca), 10(Sc), and 12(Ti) more neutrons.
Continuum states in generalized Swanson models
A. Sinha; P. Roy
2009-01-07T23:59:59.000Z
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 \
Current-based 4D shape analysis for the mechanical personalization of heart models
Paris-Sud XI, Université de
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
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...
Modeling biofilms with dual extracellular electron transfer mechanisms...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
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...
N = 4 supersymmetric mechanics: Harmonic superspace as a universal tool of model-building
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
We overview applications of the harmonic superspace approach in models of N = 4supersymmetric mechanics, with emphasis on some recent results.
Min, Kyoung
2013-07-16T23:59:59.000Z
are studied using a coupled thermo-hydro-mechanical (THM) analysis. The models are used to simulate microscopic and macroscopic fracture behaviors of laboratory-scale uniaxial and triaxial experiments on rock using an elastic/brittle damage model considering...
Substrate Hydroxylation in Methane Monooxygenase: Quantitative Modeling via Mixed Quantum Mechanics/
Gherman, Benjamin F.
at an atomic level of detail.4-7 In particular, the use of ab initio quantum chemical methods based on densitySubstrate Hydroxylation in Methane Monooxygenase: Quantitative Modeling via Mixed Quantum Mechanics with mixed quantum mechanics/molecular mechanics (QM/MM) methods, the hydroxylation of methane
Salvaggio, Carl
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
Lee, Sang Hoon
2012-02-14T23:59:59.000Z
coupled thermo-poro-mechanical FEM simulation was used to model damage/fracture propagation and microseismic events caused by fluid injection. These studies considered wellbore geometry in small-scale modeling and point-source injection, assuming...
An improved structural mechanics model for the FRAPCON nuclear fuel performance code
Mieloszyk, Alexander James
2012-01-01T23:59:59.000Z
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 ...
A Hydro-Thermo-Mechanical Numerical Model For Hdr Geothermal...
Published Journal International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, 1996 DOI 10.10160148-9062(96)00002-2 Citation T. W. Hicks,R. J. Pine,J....
Characterization and modeling of polysilicon MEMS chemical-mechanical polishing
Tang, Brian D. (Brian David), 1980-
2004-01-01T23:59:59.000Z
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, ...
Notes 01. Modeling of mechanical (lumped parameter) elements
San Andres, Luis
2008-01-01T23:59:59.000Z
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...
Modeling of chemical mechanical polishing for shallow trench isolation
Lee, Brian, 1975-
2002-01-01T23:59:59.000Z
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 ...
Cambridge, University of
Experimental testing and modelling of a passive mechanical steering compensator for high of the method to the control of motorcycles steer- ing instabilities. Simulation studies have shown-- This paper presents experimental results and a modelling study of a prototype mechanical device that repre
Thermo-mechanical modelling of Black Sea Basin (de)formation S. Cloetingh*, G. Spadini1
Beekman, Fred
Thermo-mechanical modelling of Black Sea Basin (de)formation S. Cloetingh*, G. Spadini1 , J.D. Van; received in revised form 7 January 2002; accepted 19 July 2002 Abstract We present the results of a thermo by rifting and subsequent sediment loading. Thermo-mechanical modelling of integrated lithospheric strength
ThreadedComposite: A Mechanism for Building Concurrent and Parallel Ptolemy II Models
ThreadedComposite: A Mechanism for Building Concurrent and Parallel Ptolemy II Models Edward A. Lee Electrical Engineering and Computer Sciences University of California at Berkeley Technical Report No. UCBComposite: A Mechanism for Building Concurrent and Parallel Ptolemy II Models Edward A. Lee UC Berkeley eal
WELL-POSEDNESS OF A THERMO-MECHANICAL MODEL FOR SHAPE MEMORY ALLOYS UNDER TENSION
Stefanelli, Ulisse
WELL-POSEDNESS OF A THERMO-MECHANICAL MODEL FOR SHAPE MEMORY ALLOYS UNDER TENSION PAVEL KREJC´I AND ULISSE STEFANELLI Abstract. We present a model of the full thermo-mechanical evolution of a shape memory on a time-discretization of the problem are provided. 1. Introduction Shape memory alloys (SMAs) belong
Modeling benzene plume elongation mechanisms exerted by ethanol using RT3D with a general
Alvarez, Pedro J.
Modeling benzene plume elongation mechanisms exerted by ethanol using RT3D with a general substrate ethanol on benzene fate and transport in fuel-contaminated groundwater and to discern the most influential benzene plume elongation mechanisms. The model, developed as a module for the Reactive Transport in 3
Molecular-To-Continuum Fracture Analysis of Thermosetting Polymer/Solid Interfaces
KENT,MICHAEL S.; REEDY JR.,EARL DAVID; STEVENS,MARK J.
2000-01-01T23:59:59.000Z
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.
Coupled Thermal-Hydrological-Mechanical-Chemical Model And Experiments...
Model And Experiments For Optimization Of Enhanced Geothermal System Development And Production: Evaluation of Stimulation at the Newberry Volcano EGS Demonstration Site Coupled...
Mechanical models of the 1975 Kalapana, Hawaii earthquake and tsunami
Kirby, James T.
interpretation of geological data from Kilauea, along with modeling of the tsunami using recent seismic analyses) a structural interpretation of geological data with (ii) modeling of the tsunami using recent seismic analy, because of its limited onshore expression near Kalapana. We argue that several different interpretations
Assessment of reduced mechanisms using One Dimensional Stochastic Turbulence model
Chien, Li-Chun
2010-01-01T23:59:59.000Z
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
Matrix Models, Large N Limits and Noncommutative Solitons
Richard J. Szabo
2005-12-06T23:59:59.000Z
A survey of the interrelationships between matrix models and field theories on the noncommutative torus is presented. The discretization of noncommutative gauge theory by twisted reduced models is described along with a rigorous definition of the large N continuum limit. The regularization of arbitrary noncommutative field theories by means of matrix quantum mechanics and its connection to noncommutative solitons is also discussed.
A numerical modeling study on desert oasis self-supporting mechanisms
Chu, Peter C.
A numerical modeling study on desert oasis self-supporting mechanisms Peter C. Chua, *, Shihua Lub February 2005 Abstract Oasis self-supporting mechanisms due to oasis breeze circulation (OBC) are proposed from the oasis makes the oasis surface colder than the surrounding desert surface. The sensible heat
Muscle and prosthesis contributions to amputee walking mechanics: A modeling study
Ben-Yakar, Adela
Muscle and prosthesis contributions to amputee walking mechanics: A modeling study Anne K or the prosthesis must provide the functional tasks normally provided by the ankle muscles. Three-dimensional (3D and prosthesis contributions to amputee walking mechanics, including the subtasks of body support, forward
MODELISATION DU TAUX DE DEFAILLANCE EN MECANIQUE MECHANICAL FAILURE RATE MODEL
Paris-Sud XI, Université de
. Summary Electromechanical and mechanical equipment reliability databases do not seem as widespread of the reliability of (electro-)mechanical equipment and the dispersion of failure rates for apparently similar. This statement explains itself by the nature of its which do not propose prediction reliability model but present
NUMERICAL MODELLING OF AUTOGENOUS HEALING AND RECOVERY OF MECHANICAL PROPERTIES IN ULTRA-HIGH
Boyer, Edmond
in the cementitious matrix can react with carbon dioxide dissolved in the water filling the crack. Autogenous healingNUMERICAL MODELLING OF AUTOGENOUS HEALING AND RECOVERY OF MECHANICAL PROPERTIES IN ULTRA into the crack and leads to a partial recovery of mechanical properties (Young's modulus, tensile strength
Identifying Mathematical Models of the Mechanically Ventilated Lung Using Equation Discovery
Kersting, Kristian
1 Identifying Mathematical Models of the Mechanically Ventilated Lung Using Equation Discovery in intensive care medicine by all means. Nevertheless, it can induce severe mechanical stress to the lung, which generally impairs the outcome of the therapy. To reduce the risk of a ventilator induced lung
Fluorine Plasma Treatments of Poly(propylene) Films, 2 Modeling Reaction Mechanisms and
Kushner, Mark
Fluorine Plasma Treatments of Poly(propylene) Films, 2 Modeling Reaction Mechanisms and Scalinga of commodity hydrocarbon polymers such as poly(propylene) (PP) can be modified by functionalization with plasma
Application of the 3-D Hydro-Mechanical Model GEOFRAC in enhanced geothermal systems
Vecchiarelli, Alessandra
2013-01-01T23:59:59.000Z
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 ...
Haldar, Krishnendu 1978-
2012-12-06T23:59:59.000Z
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...
A First-Order Mechanical Device to Model Traumatized Craniovascular
. 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
Model construction: elements of a computational mechanism Jan M. _Zytkow
Ras, Zbigniew W.
Academy of Sciences, Warsaw, Poland zytkow@uncc.edu Abstract Model construction is one of the key scienti of the mainsteps. As a body of mass m rolls down its kinetic energy grows from zero to mv2=2, where v is the nal velocity. At the same time, its potential energy decreases from gmh to zero, where g is Earth acceleration
Transfer to the continuum and Breakup reactions
A. M. Moro; F. M. Nunes
2006-01-10T23:59:59.000Z
Reaction theory is an essential ingredient when performing studies of nuclei far from stability. One approach for the calculation of breakup reactions of exotic nuclei into two fragments is to consider inelastic excitations into the single particle continuum of the projectile. Alternatively one can also consider the transfer to the continuum of a system composed of the light fragment and the target. In this work we make a comparative study of the two approaches, underline the different inputs, and identify the advantages and disadvantages of each approach. Our test cases consist of the breakup of $^{11}$Be on a proton target at intermediate energies, and the breakup of $^8$B on $^{58}$Ni at energies around the Coulomb barrier. We find that, in practice the results obtained in both schemes are in semiquantitative agreement. We suggest a simple condition that can select between the two approaches.
Paris-Sud XI, UniversitÃ© de
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) In this paper we present the macroscopic model describing the hydro-mechanical behaviour of such class
Optical Continuum Sources in Gravitationally Lensed Quasars
L. J. Goicoechea; D. Alcalde; V. N. Shalyapin
2002-10-30T23:59:59.000Z
We review some techniques to study the nature and size of the optical continuum sources in multiple QSOs. We focus on the source originating the events with several months timescale (the rapid variability source) as well as the source that is responsible for the non-variable background component (the background source). The techniques are used to study both the rapid variability source in Q0957+561 and the main (compact) background source in Q2237+0305.
Driven cavity flow: from molecular dynamics to continuum hydrodynamics
Tiezheng Qian; Xiao-Ping Wang
2004-03-06T23:59:59.000Z
Molecular dynamics (MD) simulations have been carried out to investigate the slip of fluid in the lid driven cavity flow where the no-slip boundary condition causes unphysical stress divergence. The MD results not only show the existence of fluid slip but also verify the validity of the Navier slip boundary condition. To better understand the fluid slip in this problem, a continuum hydrodynamic model has been formulated based upon the MD verification of the Navier boundary condition and the Newtonian stress. Our model has no adjustable parameter because all the material parameters (density, viscosity, and slip length) are directly determined from MD simulations. Steady-state velocity fields from continuum calculations are in quantitative agreement with those from MD simulations, from the molecular-scale structure to the global flow. The main discovery is as follows. In the immediate vicinity of the corners where moving and fixed solid surfaces intersect, there is a core partial-slip region where the slippage is large at the moving solid surface and decays away from the intersection quickly. In particular, the structure of this core region is nearly independent of the system size. On the other hand, for sufficiently large system, an additional partial-slip region appears where the slippage varies as $1/r$ with $r$ denoting the distance from the corner along the moving solid surface. The existence of this wide power-law region is in accordance with the asymptotic $1/r$ variation of stress and the Navier boundary condition.
SYSTEMATIC CONTINUUM ERRORS IN THE Ly{alpha} FOREST AND THE MEASURED TEMPERATURE-DENSITY RELATION
Lee, Khee-Gan, E-mail: lee@astro.princeton.edu [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)
2012-07-10T23:59:59.000Z
Continuum fitting uncertainties are a major source of error in estimates of the temperature-density relation (usually parameterized as a power-law, T {proportional_to} {Delta}{sup {gamma}-1}) of the intergalactic medium through the flux probability distribution function (PDF) of the Ly{alpha} forest. Using a simple order-of-magnitude calculation, we show that few percent-level systematic errors in the placement of the quasar continuum due to, e.g., a uniform low-absorption Gunn-Peterson component could lead to errors in {gamma} of the order of unity. This is quantified further using a simple semi-analytic model of the Ly{alpha} forest flux PDF. We find that under(over)estimates in the continuum level can lead to a lower (higher) measured value of {gamma}. By fitting models to mock data realizations generated with current observational errors, we find that continuum errors can cause a systematic bias in the estimated temperature-density relation of ({delta}({gamma})) Almost-Equal-To -0.1, while the error is increased to {sigma}{sub {gamma}} Almost-Equal-To 0.2 compared to {sigma}{sub {gamma}} Almost-Equal-To 0.1 in the absence of continuum errors.
Ian Robertson
2007-04-28T23:59:59.000Z
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.
A non-isothermal PEM fuel cell model including two water transport mechanisms in the
Münster, Westfälische Wilhelms-Universität
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
Ponder, Jay
Polarizable Atomic Multipole Water Model for Molecular Mechanics Simulation Pengyu Ren and Jay W empirical potential is proposed for water. The model uses a polarizable atomic multipole description of electrostatic interactions. Multipoles through the quadrupole are assigned to each atomic center based
Samarati, Pierangela
: it defines the (high-level) rules according to which access control must be regulated.1 Security modelAccess Control: Policies, Models, and Mechanisms Pierangela Samarati1 and Sabrina De Capitani di. In this chapter we investigate the basic concepts behind access control design and enforcement, and point out
A flow resistance model for assessing the impact of vegetation on flood routing mechanics
Katul, Gabriel
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
Mechanics of collective unfolding
M Caruel; J. -M Allain; L Truskinovsky
2015-01-07T23:59:59.000Z
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.
Understanding Creep Mechanisms in Graphite with Experiments, Multiscale Simulations, and Modeling
Eapen, Jacob; Murty, Korukonda; Burchell, Timothy
2014-06-02T23:59:59.000Z
Disordering mechanisms in graphite have a long history with conflicting viewpoints. Using Raman and x-ray photon spectroscopy, 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.
Eric Wachsman; Keith L. Duncan
2006-09-30T23:59:59.000Z
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.
Atomistic Simulation Approach to a Continuum Description of Self-Assembled b-Sheet Filaments
Kamm, Roger D.
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
Continuum regularization of gauge theory with fermions
Chan, H.S.
1987-03-01T23:59:59.000Z
The continuum regularization program is discussed in the case of d-dimensional gauge theory coupled to fermions in an arbitrary representation. Two physically equivalent formulations are given. First, a Grassmann formulation is presented, which is based on the two-noise Langevin equations of Sakita, Ishikawa and Alfaro and Gavela. Second, a non-Grassmann formulation is obtained by regularized integration of the matter fields within the regularized Grassmann system. Explicit perturbation expansions are studied in both formulations, and considerable simplification is found in the integrated non-Grassmann formalism.
Radiation from charges in the continuum limit
Ianconescu, Reuven [Shenkar College of Engineering and Design, Ramat Gan 52526 (Israel)
2013-06-15T23:59:59.000Z
It is known that an accelerating charge radiates according to Larmor formula. On the other hand, any DC current following a curvilinear path, consists of accelerating charges, but in such case the radiated power is 0. The scope of this paper is to analyze and quantify how a system of charges goes from a radiating state to a non radiating state when the charges distribution goes to the continuum limit. Understanding this is important from the theoretical point of view and the results of this work are applicable to particle accelerator, cyclotron and other high energy devices.
Truong, Thanh N.
A general methodology for quantum modeling of free-energy profile of reactions in solution methodology for calculating free-energy profile of reaction in solution using quantum mechanical methods screening model GCOSMO was employed in this study, though any continuum model with existing free-energy
Quasi Sturmian Basis in Two-Electron Continuum Problems
A. S. Zaytsev; L. U. Ancarani; S. A. Zaytsev
2015-03-12T23:59:59.000Z
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.
Hadron resonances with a quark core embedded in the continuum
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
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.
Paris-Sud XI, Université de
regulation. The main contribution of this paper is to design a new control scheme based on model-free controlA Dual Model-Free Control of Underactuated Mechanical Systems, Application to The Inertia Wheel method allowing recent model-free control technique to deal with underactuated mechanical systems
Shell model nuclear matrix elements for competing mechanisms contributing to double beta decay
Horoi, Mihai [Department of Physics, Central Michigan University, Mount Pleasant, Michigan, 48859 (United States)
2013-12-30T23:59:59.000Z
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.
Modelling the thermo-mechanical volume change behaviour of compacted expansive clays
Paris-Sud XI, Université de
Modelling the thermo-mechanical volume change behaviour of compacted expansive clays Anh-Minh Tang expansive clays are often considered as a possible buffer material in high-level deep radioactive waste disposals. After the installation of waste canisters, the engineered clay barriers are subjected to thermo
Guidoni, Leonardo
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
A Recurrent Neural Multi-Model for Mechanical Systems Dynamics Compensation
Borissova, Daniela
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
Angular approach combined to mechanical model for tool breakage detection by eddy current sensors
Paris-Sud XI, Université de
1 Angular approach combined to mechanical model for tool breakage detection by eddy current sensors solution is proposed for the estimate of cutting force using eddy current sensors implemented close eccentricity obtained during the machining from the eddy current sensors signals. Efficiency and reliability
Neural mechanisms of saccade target selection: gated accumulator model of the visualmotor cascade
Schall, Jeffrey D.
Neural mechanisms of saccade target selection: gated accumulator model of the visualmotor cascade, Vanderbilt University, PMB 407817, 2301 Vanderbilt Place, Nashville, TN 37240-7817, USA Keywords: accumulator neurons in the frontal eye field as evidence for stimulus salience that is accumulated in a network
Virtual Electrodes Mechanisms Predictions with a Current-Lifted Monodomain Model
Boyer, Edmond
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
MECHANICAL MODELING OF GLASS AND CARBON EPOXY COMPOSITES Barzin Mobasher 1
Mobasher, Barzin
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
Thermo-mechanical modeling of plasterboard lined partition submitted to fire load.
Paris-Sud XI, Université de
of full scale tests under the ISO 834 thermal loading curve [2]. This last requirement can not be met whenThermo-mechanical modeling of plasterboard lined partition submitted to fire load. Authors: S partition submitted to fire load. A fundamental key to solve such a problem is the development
MODEL OF MECHANISM BEHAVIOR FOR VERIFICATION OF PLC Jos M. Machado
Paris-Sud XI, UniversitÃ© de
MODEL OF MECHANISM BEHAVIOR FOR VERIFICATION OF PLC PROGRAMS JosÃ© 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
Lin, Liwei
Introduction to Finite Element Modeling Engineering analysis of mechanical systems have been of the FEM (don't misuse the FEM - a numerical tool) Finite Element Analysis A typical finite element quantities (e.g., strains and stresses) at selected elements Basic Theory The way finite element analysis
REVIEW AND IMPROVEMENT OF SIMPLE MECHANICAL MODELS FOR PREDICTING THE FORCE-DISPLACEMENT RESPONSE OF
Thévenaz, Jacques
engineering demand parameters and mechanical models that link local and global deformation quantities. Although unreinforced masonry (URM) is one of the most used construction materials for residential quantities, e.g. curvature profiles and shear strain profiles, we show that this is due to the formation
Comparison of problem model change mechanisms issued from CSP and TRIZ
Paris-Sud XI, Université de
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
Fluid Mechanics and Tt.ansDOrtPhenomena A Mathematical Model for a Dissolving Polymer
Edwards, David A.
Fluid Mechanics and Tt.ansDOrtPhenomena A Mathematical Model for a Dissolving Polymer David A boundary-value problem. The boundary separates the polymer into two distinct states: glassy and rub- bery- ablefront speed and a self-regulatingmass uptake. Introduction In the last few years, new uses for polymers
Continuum Study of Heavy Quark Diffusion
Thomas Neuhaus
2015-04-28T23:59:59.000Z
We report on a lattice investigation of heavy quark momentum diffusion within the pure SU(3) plasma above the deconfinement transition with the quarks treated to leading order in the heavy mass expansion. We measure the relevant "colour-electric" Euclidean correlator and based on several lattice spacing's perform the continuum extrapolation. This is necessary not only to remove cut-off effects but also the analytic continuation for the extraction of transport coefficients is well-defined only when a continuous function of the Euclidean time variable is available. We pay specific attention to scale setting in SU(3). In particular we present our determination for the critical temperature $T_c=1/({N_\\tau}a) $ at values of $N_\\tau \\le 22$.
Mavko, B.; Cizelj, L. (Jozef Stefan Inst., Reactor Engineering Div., P.O. Box 100, 61111 Ljubljana, Slovenia (YU))
1992-05-01T23:59:59.000Z
In this paper a model for estimating the failure probability of axially cracked steam generator tubes is proposed. The model compares observed crack length distribution with critical crack length distribution by means of probabilistic fracture mechanics. The observed crack length is influenced by measured data, measurement reliability, sizing accuracy, and predicted crack growth rate. The critical crack length is defined by a deterministic mechanical model. All cracks are conservatively assumed to extend through the tube wall. The effect of the plugging limit is studied along with the number of cracked tubes to perform risk-based lifetime optimization of steam generators. A numerical example presented considers hypothetical accidental operating conditions during a feedwater line break.
Coleman-Weinberg mechanism in a three-dimensional supersymmetric Chern-Simons-matter model
Ferrari, A. F. [Centro de Ciencias Naturais e Humanas, Universidade Federal do ABC, Rua Santa Adelia, 166, 09210-170, Santo Andre, SP (Brazil); Gallegos, E. A.; Gomes, M.; Silva, A. J. da [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318, 05315-970, Sao Paulo, SP (Brazil); Lehum, A. C. [Escola de Ciencias e Tecnologia, Universidade Federal do Rio Grande do Norte, Caixa Postal 1524, 59072-970, Natal, RN (Brazil); Nascimento, J. R.; Petrov, A. Yu. [Departamento de Fisica, Universidade Federal da Paraiba, Caixa Postal 5008, 58051-970, Joao Pessoa, Paraiba (Brazil)
2010-07-15T23:59:59.000Z
Using the superfield formalism, we study the dynamical breaking of gauge symmetry and superconformal invariance in the N=1 three-dimensional supersymmetric Chern-Simons model, coupled to a complex scalar superfield with a quartic self-coupling. This is an analogue of the conformally invariant Coleman-Weinberg model in four spacetime dimensions. We show that a mass for the gauge and matter superfields are dynamically generated after two-loop corrections to the effective superpotential. We also discuss the N=2 extension of our work, showing that the Coleman-Weinberg mechanism in such model is not feasible, because it is incompatible with perturbation theory.
Advani, S.H.
1983-01-01T23:59:59.000Z
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.
Development of a reduced n-heptane oxidation mechanism for HCCI combustion modeling
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
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)
Turbulence Modelling and Stirring Mechanisms in the Cosmological Large-scale Structure
Iapichino, L; Niemeyer, J C; Merklein, J
2011-01-01T23:59:59.000Z
FEARLESS (Fluid mEchanics with Adaptively Refined Large Eddy SimulationS) is a numerical scheme for modelling subgrid-scale turbulence in cosmological adaptive mesh refinement simulations. In this contribution, the main features of this tool will be outlined. We discuss the application of this method to cosmological simulations of the large-scale structure. The simulations show that the production of turbulence has a different redshift dependence in the intra-cluster medium and the warm-hot intergalactic medium, caused by the distinct stirring mechanisms (mergers and shock interactions) acting in them. Some properties of the non-thermal pressure support in the two baryon phases are also described.
Adhesive joint and composites modeling in SIERRA.
Ohashi, Yuki; Brown, Arthur A.; Hammerand, Daniel Carl; Adolf, Douglas Brian; Chambers, Robert S.; Foulk, James W., III (.,; )
2005-11-01T23:59:59.000Z
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.
Enabling HCCI modeling: The RIOT/CMCS Web Service for Automatic Reaction Mechanism Reduction
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
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.
Mentorship: The Education-Research Continuum
Correll, D
2008-05-29T23:59:59.000Z
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
Advances in constitutive modelling of jointed rock hydro mechanical interactions at laboratory scale
Paris-Sud XI, UniversitÃ© de
) 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 dÃ©bit hydraulique dans la fracture. La modÃ©lisation hydromÃ©canique rÃ©alisÃ©e Ã l'aide du code 3DEC peut
Discrete modelling of capillary mechanisms in multi-phase granular media
L. Scholtès; B. Chareyre F. Nicot; F. Darve
2012-03-06T23:59:59.000Z
A numerical study of multi-phase granular materials based upon micro-mechanical modelling is proposed. Discrete element simulations are used to investigate capillary induced effects on the friction properties of a granular assembly in the pendular regime. Capillary forces are described at the local scale through the Young-Laplace equation and are superimposed to the standard dry particle interaction usually well simulated through an elastic-plastic relationship. Both effects of the pressure difference between liquid and gas phases and of the surface tension at the interface are integrated into the interaction model. Hydraulic hysteresis is accounted for based on the possible mechanism of formation and breakage of capillary menisci at contacts. In order to upscale the interparticular model, triaxial loading paths are simulated on a granular assembly and the results interpreted through the Mohr-Coulomb criterion. The micro-mechanical approach is validated with a capillary cohesion induced at the macroscopic scale. It is shown that interparticular menisci contribute to the soil resistance by increasing normal forces at contacts. In addition, more than the capillary pressure level or the degree of saturation, our findings highlight the importance of the density number of liquid bonds on the overall behaviour of the material.
Multiscale mechanics of macromolecular materials with unfolding domains
Domenico De Tommasi; Giuseppe Puglisi; Giuseppe Saccomandi
2014-07-14T23:59:59.000Z
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.
Fang, Yilin; Nguyen, Ba Nghiep; Carroll, Kenneth C.; Xu, Zhijie; Yabusaki, Steven B.; Scheibe, Timothy D.; Bonneville, Alain
2013-09-12T23:59:59.000Z
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.
Anand, Lallit
In this Part I, of a two-part paper, we present a detailed continuum-mechanical development of a thermomechanically
Pitman, Jim
2008-01-01T23:59:59.000Z
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.
Neoclassical Simulation of Tokamak Plasmas using Continuum Gyrokinetc Code TEMPEST
Xu, X Q
2007-11-09T23:59:59.000Z
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.
Mechanical formalism for tissue dynamics
Sham Tlili; Cyprien Gay; Francois Graner; Philippe Marcq; François Molino; Pierre Saramito
2014-12-23T23:59:59.000Z
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.
Modeling, simulation, and testing of the mechanical dynamics of and RF MEMS switch.
Sumali, Hartono; Epp, David S.; Massad, Jordan Elias; Dyck, Christopher William; Starr, Michael James
2005-07-01T23:59:59.000Z
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.
Mechanical Behaviour of the Short Models of LHC Main Dipole Magnets
Andreyev, N I; Casarejos, E; Kurtyka, T; Rathjen, C; Perini, D; Siegel, N; Tommasini, D; Vanenkov, I
1998-01-01T23:59:59.000Z
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.
Mappings From Models Presenting Topological Mass Mechanisms to Purely Topological Models
Amaral, R.L.P.G.; Costa, J.V. [Instituto de Fisica, Universidade Federal Fluminense, Niteroi (Brazil); Ventura, O.S. [Centro Federal de Educacao Tecnologica do Espirito Santo, Vitoria (Brazil); Centro Universitario de Vila Velha, Vila Velha - ES (Brazil); Uniest, Cariacica-ES (Brazil); Bouffon, L.O. [Centro Federal de Educacao Tecnologica do Espirito Santo, Vitoria (Brazil); Escola Superior de Ciencias da Santa Casa de Misericordia de Vitoria, Vitoria-ES (Brazil); Lemes, V.E.R. [Instituto de Fisica, Universidade do Estado do Rio de Janeiro, Rio de Janeiro - RJ (Brazil)
2004-12-02T23:59:59.000Z
We discuss a class of mappings between the fields of the Cremmer-Sherk and pure BF model in 4D. These mappings are established both with an iterative procedure as well as with an exact mapping procedure. Related equivalences in 5D and 3D are discussed.
A minimal model for the inelastic mechanics of biopolymer networks and cells
Lars Wolff; Klaus Kroy
2012-05-27T23:59:59.000Z
Live cells have ambiguous mechanical properties. They were often described as either elastic solids or viscoelastic fluids and have recently been classified as soft glassy materials characterized by weak power-law rheology. Nonlinear rheological measurements have moreover revealed a pronounced inelastic response indicative of a competition between stiffening and softening. It is an intriguing question whether these observations can be explained from the material properties of much simpler in-vitro reconstituted networks of biopolymers that serve as reduced model systems for the cytoskeleton. Here, we explore the mechanism behind the inelastic response of cells and biopolymer networks, theoretically. Our analysis is based on the model of the inelastic glassy wormlike chain that accounts for the nonlinear polymer dynamics and transient crosslinking in biopolymer networks. It explains how inelastic and kinematic-hardening type behavior naturally emerges from the antagonistic mechanisms of viscoelastic stress-stiffening due to the polymers and inelastic fluidization due to bond breaking. It also suggests a simple set of schematic constitutive equations which faithfully reproduce the rich inelastic phenomenology of biopolymer networks and cells.
Benioff, P.A.
1981-01-01T23:59:59.000Z
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.
Supporting Kibble-Zurek Mechanism in Quantum Ising Model through a Trapped Ion
Jin-Ming Cui; Yun-Feng Huang; Zhao Wang; Dong-Yang Cao; Jian Wang; Wei-Min Lv; Yong Lu; Le Luo; Adolfo del Campo; Yong-Jian Han; Chuan-Feng Li; Guang-Can Guo
2015-05-21T23:59:59.000Z
Progress in quantum simulation has fostered the research on far-from-equilibrium dynamics. The Kibble-Zurek mechanism is the paradigmatic framework to account for the non adiabatic critical dynamics of a system driven across a phase transition in a finite time. Its study in the quantum regime is hindered by the requisite of ground state cooling. We report the experimental quantum simulation of critical dynamics in the transverse-field Ising model by a set of non-equilibrium processes in the pseudo-momentum space, that can be probed with high accuracy using a single trapped ion. Our results support the validity of the Kibble-Zurek mechanism in the quantum regime and advance the quantum simulation of critical systems far-away from equilibrium.
Continuum Thermodynamics of the SU(N) Gauge Theory
Saumen Datta; Sourendu Gupta
2010-12-30T23:59:59.000Z
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.
Freed, Alan D.; Einstein, Daniel R.
2011-04-14T23:59:59.000Z
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.
Statistical mechanics model for the transit free energy of monatomic liquids
Duane C. Wallace; Eric D. Chisolm; N. Bock; G. De Lorenzi-Venneri
2010-04-19T23:59:59.000Z
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.
M. Lin; D. Kicker; B. Damjanac; M. Board; M. Karakouzian
2006-07-05T23:59:59.000Z
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.
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
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.
Thermal and mechanical denaturation properties of a DNA model with three sites per nucleotide
Florescu, Ana-Maria; 10.1063/1.3626870
2011-01-01T23:59:59.000Z
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...
Comparison of QM-Only and QM/MM Models for the Mechanism of Tungsten-Dependent Acetylene Hydratase
Liao, Rongzhen
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
Computational tool for comparison of kinematic mechanisms and commonly used kinematic models
Hollerbach, K.; Hollister, A.M.; Van Vorhis, R.L.
1997-03-01T23:59:59.000Z
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.
The, Lih-Sin [Department of Physics and Astronomy, Clemson University, SC 29634 (United States); Burrows, Adam, E-mail: tlihsin@clemson.edu, E-mail: burrows@astro.princeton.edu [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)
2014-05-10T23:59:59.000Z
The hard X-ray continuum and gamma-ray lines from a Type Ia supernova dominate its integrated photon emissions and can provide unique diagnostics of the mass of the ejecta, the {sup 56}Ni yield and spatial distribution, its kinetic energy and expansion speed, and the mechanism of explosion. Such signatures and their time behavior 'X-ray' the bulk debris field in direct fashion, and do not depend on the ofttimes problematic and elaborate UV, optical, and near-infrared spectroscopy and radiative transfer that have informed the study of these events for decades. However, to date no hard photons have ever been detected from a Type Ia supernova in explosion. With the advent of the supernova SN 2014J in M82, at a distance of ?3.5 Mpc, this situation may soon change. Both NuSTAR and INTEGRAL have the potential to detect SN 2014J, and, if spectra and light curves can be measured, would usefully constrain the various explosion models published during the last ?30 yr. In support of these observational campaigns, we provide predictions for the hard X-ray continuum and gamma-line emissions for 15 Type Ia explosion models gleaned from the literature. The model set, containing as it does deflagration, delayed detonation, merger detonation, pulsational delayed detonation, and sub-Chandrasekhar helium detonation models, collectively spans a wide range of properties, and hence signatures. We provide a brief discussion of various diagnostics (with examples), but importantly make the spectral and line results available electronically to aid in the interpretation of the anticipated data.
On a 2D hydro-mechanical lattice approach for modelling hydraulic fracture
Grassl, Peter; Gallipoli, Domenico; Wheeler, Simon J
2014-01-01T23:59:59.000Z
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.
A mathematical model for investigating the mechanical behaviour of salt cavities
Lambert, G.M.S.; Creed, M.R.; Dean, F.; Leigh, M.J.
1988-01-01T23:59:59.000Z
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.
Equilibrium statistical mechanics and energy partition for the shallow water model
Renaud, Antoine; Bouchet, Freddy
2015-01-01T23:59:59.000Z
The aim of this paper is to use large deviation theory in order to compute the entropy of macrostates for the microcanonical measure of the shallow water system. The main prediction of this full statistical mechanics computation is the energy partition between a large scale vortical flow and small scale fluctuations related to inertia-gravity waves. We introduce for that purpose a discretized model of the continuous shallow water system, and compute the corresponding statistical equilibria. We argue that microcanonical equilibrium states of the discretized model in the continuous limit are equilibrium states of the actual shallow water system. We show that the presence of small scale fluctuations selects a subclass of equilibria among the states that were previously computed by phenomenological approaches that were neglecting such fluctuations. In the limit of weak height fluctuations, the equilibrium state can be interpreted as two subsystems in thermal contact: one subsystem corresponds to the large scale v...
Magnetic and Mechanical Analysis of the HQ Model Quadrupole Designs for LARP
Felice, Helene; Caspi, Shlomo; Ferracin, Paolo; Kashikhin, Vadim; Novitski, Igor; Sabbi, GianLuca; Zlobin, Alexander
2008-06-01T23:59:59.000Z
Insertion quadrupoles with large bore and high gradient are required to upgrade the luminosity of the Large Hadron Collider (LHC). The US LHC Accelerator Research Program is developing Nb{sub 3}Sn technology for the upgrade. This effort includes a series of 1 m long Technology Quadrupoles (TQ), to demonstrate the reproducibility at moderate field, and High-gradient Quadrupoles (HQ) to explore the magnet performance limits in terms of peak fields, forces and stresses. The HQ models are expected to achieve peak fields of 15 T or higher. A coil aperture of 90 mm, corresponding to gradients above 300 T/m, was chosen as the baseline. Peak stresses above 150 MPa are expected. Progress on the magnetic and mechanical design of the HQ models will be reported.
Thermal-mechanical modeling of deep borehole disposal of high-level radioactive waste.
Arnold, Bill Walter; Hadgu, Teklu
2010-12-01T23:59:59.000Z
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.
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
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.
I. Robertson; A. Beaudoin; J. Lambros
2005-01-31T23:59:59.000Z
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 (foreign object damage, high-strain rate forging, high-speed sheet forming, deformation behavior during forming, response to extreme conditions, etc.). 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 closely coupled 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 experimentation 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, which will include dislocation-grain boundary interactions for polycrystalline systems. One aspect of the program will involve the direct observation of specific mechanisms of micro-plasticity, as these will 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. To achieve these goals required assembling a multidisciplinary team, see Table 1, with key collaborators at the National Laboratories. One of the major issues for the team members was to learn about the expertise available and how to communicate across disciplines. The communication issue is a challenging one and is being addressed in part with weekly meetings in which the graduate students present lectures on the fundamentals of their respective areas to the entire group. Breakthroughs in science are presented but these, by necessity, assume a tutorial nature; examples of student led meetings can be found at our website http://hrdg.mse.uiuc.edu/. For example, interpreting electron micrographs and understanding what can be achieved by using electron microscopy is challenging for the modeling expert as is comprehending the input and limitations of crystal plasticity codes for an electron microscopist. Significant progress has been made at dissolving these barriers and the students are able to work across the disciplines.
Paddison, S.J.; Zawodzinski, T.A. Jr. [Los Alamos National Lab., NM (United States). Electronic and Electrochemical Materials and Devices Group; Paul, R. [Univ. of Calgary, Alberta (Canada). Dept. of Chemistry
1998-12-31T23:59:59.000Z
With the well established importance of the coupling of water and protons through electroosmotic drag in operating PEFCs the authors present here a derivation of a mathematical model that focuses on the computation of the mobility of an hydronium ion through an arbitrary cylindrical pore of a PEM with a non-uniform charge distribution on the walls of the pore. The total Hamiltonian is derived for the hydronium ion as it moves through the hydrated pore and is effected by the net potential due to interaction with the solvent molecules and the pendant side chains. The corresponding probability density is derived through solution of the Liouville equation. This probability density is then used to compute the friction tensor for the hydronium ion. The authors find two types of contributions: (a) due to the solvent-ion interactions for which they adopt the conventional continuum model; (b) due to the interaction between the pendant charges and the hydronium ion. The latter is a new result and displays the role of the non-uniform nature of the charge distribution on the pore wall.
Testing eccentricity pumping mechanisms to model eccentric long period sdB binaries with MESA
Vos, Joris; Marchant, Pablo; Van Winckel, Hans
2015-01-01T23:59:59.000Z
Hot subdwarf-B stars in long-period binaries are found to be on eccentric orbits, even though current binary-evolution theory predicts those objects to be circularised before the onset of Roche-lobe overflow (RLOF). We aim to find binary-evolution mechanisms that can explain these eccentric long-period orbits, and reproduce the currently observed period-eccentricity diagram. Three different processes are considered; tidally-enhanced wind mass-loss, phase-dependent RLOF on eccentric orbits and the interaction between a circumbinary disk and the binary. The binary module of the stellar-evolution code MESA (Modules for Experiments in Stellar Astrophysics) is extended to include the eccentricity-pumping processes. The effects of different input parameters on the final period and eccentricity of a binary-evolution model are tested with MESA. The end products of models with only tidally-enhanced wind mass-loss can indeed be eccentric, but these models need to lose too much mass, and invariably end up with a helium ...
Mass-Spring Model for Simulation of Heart Valve Tissue Mechanical Behavior Peter E. Hammer1,2,4,*
1 Mass-Spring Model for Simulation of Heart Valve Tissue Mechanical Behavior Peter E. Hammer1, Cambridge, MA Abbreviated title: Mass-Spring Model for Simulation of Heart Valve Tissue * Address, MA, USA. E-mail address: peter.hammer@childrens.harvard.edu. #12;2 Abstract Heart valves
Spin Matrix Theory: A quantum mechanical model of the AdS/CFT correspondence
Troels Harmark; Marta Orselli
2014-10-31T23:59:59.000Z
We introduce a new quantum mechanical theory called Spin Matrix theory (SMT). The theory is interacting with a single coupling constant g and is based on a Hilbert space of harmonic oscillators with a spin index taking values in a Lie (super)algebra representation as well as matrix indices for the adjoint representation of U(N). We show that SMT describes N=4 super-Yang-Mills theory (SYM) near zero-temperature critical points in the grand canonical phase diagram. Equivalently, SMT arises from non-relativistic limits of N=4 SYM. Even though SMT is a non-relativistic quantum mechanical theory it contains a variety of phases mimicking the AdS/CFT correspondence. Moreover, the infinite g limit of SMT can be mapped to the supersymmetric sector of string theory on AdS_5 x S^5. We study SU(2) SMT in detail. At large N and low temperatures it is a theory of spin chains that for small g resembles planar gauge theory and for large g a non-relativistic string theory. When raising the temperature a partial deconfinement transition occurs due to finite-N effects. For sufficiently high temperatures the partially deconfined phase has a classical regime. We find a matrix model description of this regime at any coupling g. Setting g=0 it is a theory of N^2+1 harmonic oscillators while for large g it becomes 2N harmonic oscillators.
HO,PAULINE; JOHANNES,JUSTINE E.; BUSS,RICHARD J.; MEEKS,ELLEN
2001-05-01T23:59:59.000Z
As part of a project with SEMATECH, detailed chemical reaction mechanisms have been developed that describe the gas-phase and surface chemistry occurring during the fluorocarbon plasma etching of silicon dioxide and related materials. The fluorocarbons examined are C{sub 2}F{sub 6}, CHF{sub 3} and C{sub 4}F{sub 8}, while the materials studied are silicon dioxide, silicon, photoresist, and silica-based low-k dielectrics. These systems were examined at different levels, ranging from in-depth treatment of C{sub 2}F{sub 6} plasma etch of oxide, to a fairly cursory examination of C{sub 4}F{sub 8} etch of the low-k dielectric. Simulations using these reaction mechanisms and AURORA, a zero-dimensional model, compare favorably with etch rates measured in three different experimental reactors, plus extensive diagnostic absolute density measurements of electron and negative ions, relative density measurements of CF, CF{sub 2}, SiF and SiF{sub 2} radicals, ion current densities, and mass spectrometric measurements of relative ion densities.
Three-body Interactions Improve the Prediction of Rate and Mechanism in Protein Folding Models
M. R. Ejtehadi; S. P. Avall; S. S. Plotkin
2004-07-14T23:59:59.000Z
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.
Rutqvist, Jonny; Majer, Ernie; Oldenburg, Curt; Peterson, John; Vasco, Don
2006-06-07T23:59:59.000Z
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.
A Sequential Fluid-mechanic Chemical-kinetic Model of Propane HCCI Combustion
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
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.
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
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
Dislocations and morphological instabilities: Continuum modeling of misfitting heteroepitaxial films
Rutenberg, Andrew
-well lasers, and light-emitting diodes. These nanoscale components have been traditionally obtained from
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...
Coupling hydrophobicity, dispersion, and electrostatics in continuum solvent models
Dzubiella, J; Swanson, JMJ; McCammon, J A
2006-01-01T23:59:59.000Z
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
Sandia Energy - 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's PossibleRadiation Protection245C Unlimited ReleaseWelcomeLong LifetimeConcentrating SolarCoupling
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 DataDepartment of Energy Your Density Isn'tOriginEducationVideoStrategic| Department of EnergyFOR IMMEDIATE RELEASEWORLD'S
The Standard model as a low-energy effective theory: what is triggering the Higgs mechanism?
Fred Jegerlehner
2014-07-02T23:59:59.000Z
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.
The ramifications of diffusive volume transport in classical fluid mechanics
Bielenberg, James R. (James Ronald), 1976-
2004-01-01T23:59:59.000Z
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 ...
Quantum Communication with Continuum Single-Photon Pulses
F. F. S. Rios; R. V. Ramos
2014-05-15T23:59:59.000Z
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.
A non-singular continuum theory of dislocations
Cai, Wei
of the dislocation equations of motion. Alternatively, a can be chosen to match the atomistic and continuum energies-singular, self-consistent framework for computing the stress field and the total elastic energy of a general as the negative derivative of the total energy with respect to the dislocation position, is equal to the force
Optimal Location of a Mobile Sensor Continuum for Environmental Monitoring
Boyer, Edmond
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
Continuum Theory of Epitaxial Crystal Growth, I Abstract 1 Introduction
with appropriate boundary conditions at the continuum level to describe the growth ... epitaxial, i.e. layer by layer growth of a crystalline thin lm on a suitably ...... [13] Mullins W.W., Theory of Thermal Grooving, J. Appl. Phys., 28(1957), 333{
Measurement Scales on the Continuum R. DUNCANLUCEAND LOUISNARENS
Barrett, Jeffrey A.
Measurement Scales on the Continuum R. DUNCANLUCEAND LOUISNARENS In a seminal article in 1946, S. S. Stevens noted that the numerical measures then in common use exhibited three admissible groups-theories of measurement- center not on the classical methods that evolved in physics, which are well understood
MULTI-WAVELENGTH RADIO CONTINUUM EMISSION STUDIES OF DUST-FREE RED GIANTS
O'Gorman, Eamon; Harper, Graham M. [School of Physics, Trinity College Dublin, Dublin 2 (Ireland); Brown, Alexander [Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309 (United States); Drake, Stephen [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Richards, Anita M. S. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom)
2013-10-01T23:59:59.000Z
Multi-wavelength centimeter continuum observations of non-dusty, non-pulsating K spectral-type red giants directly sample their chromospheres and wind acceleration zones. Such stars are feeble emitters at these wavelengths, however, and previous observations have provided only a small number of modest signal-to-noise measurements slowly accumulated over three decades. We present multi-wavelength Karl G. Jansky Very Large Array thermal continuum observations of the wind acceleration zones of two dust-free red giants, Arcturus (? Boo: K2 III) and Aldebaran (? Tau: K5 III). Importantly, most of our observations of each star were carried out over just a few days, so that we obtained a snapshot of the different stellar atmospheric layers sampled at different wavelengths, independent of any long-term variability. We report the first detections at several wavelengths for each star including a detection at 10 cm (3.0 GHz: S band) for both stars and a 20 cm (1.5 GHz: L band) detection for ? Boo. This is the first time single (non-binary) luminosity class III red giants have been detected at these continuum wavelengths. Our long-wavelength data sample the outer layers of ? Boo's atmosphere where its wind velocity is approaching (or possibly has reached) its terminal value and the ionization balance is becoming frozen-in. For ? Tau, however, our long-wavelength data are still sampling its inner atmosphere, where the wind is still accelerating probably due to its lower mass-loss rate. We compare our data with published semi-empirical models based on ultraviolet data, and the marked deviations highlight the need for new atmospheric models to be developed. Spectral indices are used to discuss the possible properties of the stellar atmospheres, and we find evidence for a rapidly cooling wind in the case of ? Boo. Finally, we develop a simple analytical wind model for ? Boo based on our new long-wavelength flux measurements.
Laubie, Hadrien Hyacinthe
2013-01-01T23:59:59.000Z
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 ...
Telleria, Maria J
2010-01-01T23:59:59.000Z
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 ...
Wang, Yong, Ph. D. Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics
2008-01-01T23:59:59.000Z
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 ...
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
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.
Song, Zhichao
2012-01-01T23:59:59.000Z
adhesion in microelectromechanical systems. ASME J. Tribol.microtribology for microelectromechanical systems. Wear 200,forces in microelectromechanical systems: mechanisms,
X-ray continuum emission spectroscopy from hot dense matter at Gbar pressures
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
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.
Sierra/solid mechanics 4.22 user's guide.
Thomas, Jesse David
2011-10-01T23:59:59.000Z
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.
Particle-in-Cell Modeling of Magnetized Argon Plasma Flow Through Small Mechanical Apertures
Adam B. Sefkow and Samuel A. Cohen
2009-04-09T23:59:59.000Z
Motivated by observations of supersonic argon-ion flow generated by linear helicon-heated plasma devices, a three-dimensional particle-in-cell (PIC) code is used to study whether stationary electrostatic layers form near mechanical apertures intersecting the flow of magnetized plasma. By self-consistently evaluating the temporal evolution of the plasma in the vicinity of the aperture, the PIC simulations characterize the roles of the imposed aperture and applied magnetic field on ion acceleration. The PIC model includes ionization of a background neutral-argon population by thermal and superthermal electrons, the latter found upstream of the aperture. Near the aperture, a transition from a collisional to a collisionless regime occurs. Perturbations of density and potential, with mm wavelengths and consistent with ion acoustic waves, propagate axially. An ion acceleration region of length ~ 200?300 ?D,e forms at the location of the aperture and is found to be an electrostatic double layer, with axially-separated regions of net positive and negative charge. Reducing the aperture diameter or increasing its length increases the double layer strength.
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
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.
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
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.
Ritchie, Robert
and compressors, despite the fact that they can be extremely susceptible to such hydrogen embrittlement, is well documented. Hydrogen, either as an external gas, resulting from electrochemical reactionsA statistical, physical-based, micro-mechanical model of hydrogen-induced intergranular fracture
A thermo-hydro-mechanical coupled model in local thermal non-equilibrium for fractured HDR reservoir
Boyer, Edmond
artificially fractured hot dry rock (HDR) reservoirs requires three main ingredients: (1) a proper thermoA thermo-hydro-mechanical coupled model in local thermal non-equilibrium for fractured HDR reservoir Rachel Geleta,b , Benjamin Loreta, , Nasser Khalilib aLaboratoire Sols, Solides, Structures, B
Non-Linear Continuum Regression Using Genetic Programming Ben.McKay@ncl.ac.uk
Fernandez, Thomas
Non-Linear Continuum Regression Using Genetic Programming Ben McKay Ben.McKay@ncl.ac.uk Mark Willis In this contribution, genetic programming is combined with continuum regression to produce two novel non-linear-based' strategy. Having discussed continuum regression, the modifications required to extend the algorithm for non-linear
Information Technology Security Training Requirements Appendix A --Learning Continuum A-1
Information Technology Security Training Requirements APPENDIX A Appendix A -- Learning Continuum A-1 #12;Information Technology Security Training Requirements Appendix A -- Learning Continuum A-2 #12;Information Technology Security Training Requirements APPENDIX A -- LEARNING CONTINUUM T R A I N I N G E D U
NREL Leads Energy Systems Integration, Continuum Magazine: Issue 4 (Book)
Not Available
2013-04-01T23:59:59.000Z
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.
Vortex topology and the continuum limit of lattice gauge theories
G. Burgio
2007-10-02T23:59:59.000Z
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.
McDonough, Jeffrey
. 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
Microstructure and Mechanical Property Studies on Neutron-Irradiated Ferritic Fe-Cr Model Alloys
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
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.
Continuum limits of atomistic energies allowing smooth and sharp interfaces in 1D Elasticity
Carlos Mora-Corral
2008-08-15T23:59:59.000Z
In this paper we present two atomistic models for the energy of a one-dimensional elastic crystal. We assume that the macroscopic displacement equals the microscopic one. The energy of the first model is given by a two-body interaction potential, and we assume that the atoms follow a continuous and piecewise smooth macroscopic (continuum) deformation. We calculate the first terms of the Taylor expansion (with respect to the parameter representing the interatomic distance) of the atomistic energy, and obtain that the coefficients of that Taylor expansion represent, respectively, an elastic energy, a sharp-interface energy, and a smooth-interface energy. The second atomistic model is a variant of the first one, and its Taylor expansion predicts, in addition, a new term that accounts for the repulsion force between two sharp interfaces.
Heydarkhan Tehrani, Ardeshir
2013-08-26T23:59:59.000Z
This dissertation is devoted to the virtual investigation of the mechanical behavior of micro/nano polymer composites (MNPCs). Advanced composite materials are favored by the automotive industry and army departments for their customizable tailored...
Physical understanding and modeling of chemical mechanical planarization in dielectric materials
Xie, Xiaolin, Ph. D. Massachusetts Institute of Technology
2007-01-01T23:59:59.000Z
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 ...
Wee, Brian (Brian J.)
2013-01-01T23:59:59.000Z
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 ...
Heydarkhan Tehrani, Ardeshir
2013-08-26T23:59:59.000Z
This dissertation is devoted to the virtual investigation of the mechanical behavior of micro/nano polymer composites (MNPCs). Advanced composite materials are favored by the automotive industry and army departments for their customizable tailored...
Eichenfield, Matt; Safavi-Naeini, Amir H; Vahala, Kerry J; Painter, Oskar
2009-01-01T23:59:59.000Z
Periodically structured materials can sustain both optical and mechanical excitations which are tailored by the geometry. Here we analyze the properties of dispersively coupled planar photonic and phononic crystals: optomechanical crystals. In particular, the properties of co-resonant optical and mechanical cavities in quasi-1D (patterned nanobeam) and quasi-2D (patterned membrane) geometries are studied. It is shown that the mechanical Q and optomechanical coupling in these structures can vary by many orders of magnitude with modest changes in geometry. An intuitive picture is developed based upon a perturbation theory for shifting material boundaries that allows the optomechanical properties to be designed and optimized. Several designs are presented with mechanical frequency ~ 1-10 GHz, optical Q-factor Qo > 10^7, motional masses meff 100 femtograms, optomechanical coupling length LOM 10^7.
Physical and numerical modeling of the external fluid mechanics of OTEC pilot plants
Singarella, Paul N.
1982-01-01T23:59:59.000Z
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 ...
Mechanical characterization and modelling of the heavy tungsten allow IT180
Scapin, M
2015-01-01T23:59:59.000Z
Pure tungsten or its alloys(WHA) find applications in several fields, especially due to the fact that these materials show a good combination of mechanical and thermal properties and they are commonly used in aerospace, automotive, metal working processes, military and nuclear technologies. Looking at the scientific literature, a lack in the mechanical characterization over wide ranges in temperature and strain-rates was found, especially forW–Ni–Cu alloys.
Paris-Sud XI, Université de
A chemo-poro-mechanical model of oilwell cement carbonation under CO2 geological storage conditions may impact the mechanical behaviour of wellbore cement in the context of CO2 storage. The model process. The major chemical reactions occurring within cement and their consequences on the volumes
NUMERICAL MODELING FOR THE FORMATION MECHANISM OF 3D TOPOGRAPHY ON MICROBIAL MAT SURFACES
Patel, Harsh Jay
2013-09-27T23:59:59.000Z
determined. A deterministic model includes both a dynamic model, and a static model. Compared to a deterministic solute diffusion model, a stochastic diffusion model has one or more stochastic elements. Concentration diffusion system formulated... solute diffusion equation, which merely appears in the form of a number line, the quasi-2D solute diffusion equation forms a Cartesian grid system. Also, for the explicit quasi-2D solute diffusion equation (Eq. 4), concentration variation is measured...
Emission lines and optical continuum in low-luminosity radio galaxies
K. A. Wills; R. Morganti; C. N. Tadhunter; T. G. Robinson; M. Villar-Martin
2003-10-09T23:59:59.000Z
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.
Wide-Area Mapping of 155 Micron Continuum Emission from the Orion Molecular Cloud Complex
S. Arimura; H. Shibai; T. Teshima; T. Nakagawa; M. Narita; S. Makiuti; Y. Doi; R. P. Verma; S. K. Ghosh; T. N. Rengarajan; M. Tanaka; H. Okuda
2004-03-03T23:59:59.000Z
We present the results of a wide-area mapping of the far-infrared continuum emission toward the Orion complex by using a Japanese balloon-borne telescope. The 155-um continuum emission was detected over a region of 1.5 deg^2 around the KL nebula with 3' resolution similar to that of the IRAS 100-um map. Assuming a single-temperature model of the thermal equilibrium dust, maps of the temperature and the optical depth were derived from the 155 um intensity and the IRAS 100 um intensity. The derived dust temperature is 5 - 15 K lower and the derived dust optical thickness were derived from the 155-um intensity and the IRAS 100-um intensity. The derived dust temperature is 5 - 15 K lower and the derived dust optical depth is 5 - 300 times larger than those derived from the IRAS 60 and 100-um intensities due to the significant contribution of the statistically heated very small grains to the IRAS 60-um intensity. The optical-thickness distribution shows a filamentary dust ridge that has a 1.5 degrees extent in the north - south direction and well resembles the Integral-Shaped Filament (ISF) molecular gas distribution. The gas-to-dust ratio derived from the CO molecular gas distribution along the ISF is in the range 30 - 200, which may be interpreted as being an effect of CO depletion due to the photodissociation and/or the freezing on dust grains.
Negative-parity {Lambda}{sub Q} baryons in the baryon-meson continuum
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
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.
On the ionizing continuum in active galactic nuclei: clues from ISO
M. Almudena Prieto; Sueli M. Viegas
1999-11-15T23:59:59.000Z
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.
Physical process Mechanical mechanisms
Berlin,Technische Universität
1 Physical process Generation · Mechanical mechanisms F = m·a · Electric/Magnetic mechanisms F = B·i·l · Fluid dynamic/Hydraulic mechanisms q, p, ij · Thermal/Optical #12;2 Source unit
Mitchell, John Anthony; Epp, David S.; Wittwer, Jonathan W.
2005-10-01T23:59:59.000Z
Damping vibrations is important in the design of some types of inertial sensing devices. One method for adding damping to a device is to use magnetic forces generated by a static magnetic field interacting with eddy currents. In this report, we develop a 2-dimensional finite element model for the analysis of quasistatic eddy currents in a thin sheet of conducting material. The model was used for design and sensitivity analyses of a novel mechanical oscillator that consists of a shuttle mass (thin sheet of conducting material) and a set of folded spring elements. The oscillator is damped through the interaction of a static magnetic field and eddy currents in the shuttle mass. Using a prototype device and Laser Dopler Velocimetry (LDV), measurements were compared to the model in a validation study using simulation based uncertainty analyses. Measurements were found to follow the trends predicted by the model.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Anand, M.; Rajagopal, K.; Rajagopal, K. R.
2003-01-01T23:59:59.000Z
Multiple interacting mechanisms control the formation and dissolution of clots to maintain blood in a state of delicate balance. In addition to a myriad of biochemical reactions, rheological factors also play a crucial role in modulating the response of blood to external stimuli. To date, a comprehensive model for clot formation and dissolution, that takes into account the biochemical, medical and rheological factors, has not been put into place, the existing models emphasizing either one or the other of the factors. In this paper, after discussing the various biochemical, physiologic and rheological factors at some length, we develop a modelmore »for clot formation and dissolution that incorporates many of the relevant crucial factors that have a bearing on the problem. The model, though just a first step towards understanding a complex phenomenon, goes further than previous models in integrating the biochemical, physiologic and rheological factors that come into play.« less
Oni?, D
2015-01-01T23:59:59.000Z
In this paper, the integrated continuum radio-spectrum of supernova remnant (SNR) W44 was analyzed up to 70 GHz, testing the different emission models that can be responsible for its particular shape. {\\it Planck's} observations made possible to analyze the high frequency part of radio-emission from SNRs. Although the quality of radio-continuum spectrum (a high scatter of data points at same frequencies) prevents us to make definite conclusions, we emphasize the possibility of spinning-dust emission detection towards this remnant. In addition, a concave-down feature, due to synchrotron losses, can not be definitely dismissed by the present knowledge of the integrated radio continuum spectrum of this SNR.
Mechanisms of aerosol-forced AMOC variability in a state of the art climate model
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
A Superstring Theory for Fractal Spacetime, Chaos and Quantumlike Mechanics in Atmospheric Flows
A. M. Selvam; Suvarna Fadnavis
1998-06-03T23:59:59.000Z
Atmospheric flows exhibit long-range spatiotemporal correlations manifested as the fractal geometry to the global cloud cover pattern concomitant with inverse power law form for spectra of temporal fluctuations. Such non-local connections are ubiquitous to dynamical systems in nature and are identified as signatures of self-organized criticality A recently developed cell dynamical system model for atmospheric flows predicts the observed self-organized criticality as intrinsic to quantumlike mechanics governing flow dynamics. The model predicts the following: (a) The flow structure consists of an overall logarithmic spiral trajectory with the quasiperiodic Penrose tiling pattern for the internal structure. (b) The universal algorithm for self-organized criticality is expressed in terms of the universal Feigenbaum's constants. (c) The Feigenbaum's constants are expressed as functions of the golden mean. (d) The quantum mechanical constants ' fine structure constant' and 'ratio of proton mass to electron mass' which are pure numbers and obtained by experimental observations only, are now derived in terms of the Feigenbaum's constant a. (e) Atmospheric flow structure follows Kepler's third law of planetary motion. Therefore Newton's inverse square law for gravitation applies to eddy masses also. The centripetal acceleration representing inertial masses (of eddies) are equivalent to gravitational masses. Fractal structure to the space-time continuum can be visualized as a nested continuum of vortex (eddy) circulations whose inertial masses obey Newton's inverse square law of gravitation. The model concepts are equivalent to a superstring model for subatomic dynamics which incorporates gravitational forces.
Goddard III, William A.
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
R. Fedele; M. A. Man'ko; V. I. Man'ko; V. G. Vaccaro
2002-07-30T23:59:59.000Z
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.
Thomas, Brian G.
the flow-rate and solidification time histories. An efficient one-dimensional (1-D) heat transfer model
Multiscale Modeling of TiO2 Nanoparticle Production in Flame Reactors: Effect of Chemical Mechanism
Raman, Venkat
, catalysis, energy, and semiconductors. Titanium dioxide (TiO2) nanoparticles are traditionally used and Engineering Mechanics, The UniVersity of Texas, Austin, Texas 78712 For titanium dioxide (TiO2) nanoparticles in the flame with detailed titanium oxidation chemistry, compared to one-step chemistry. Finally, a large
3D imaging and mechanical modeling of helical buckling in Medicago truncatula plant roots
Cohen, Itai
such as drought impedes root growth and conse- quently has severe negative effects on yield (1). As world popu they grow. Soil compaction resulting from agricultural activities or from environ- mental changes while facing a decline in agricultural soil quality including increased mechanical impe- dance of soil
Spectral Evolution of the Continuum and Disc Line in Dipping in GRO J1655-40
M. Balucinska-Church
2001-01-22T23:59:59.000Z
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.
Development and validation of a transition model based on a mechanical approximation
Vizinho, R; Silvestre, M
2015-01-01T23:59:59.000Z
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...
Wave-packet continuum discretization for quantum scattering
O. A. Rubtsova; V. I. Kukulin; V. N. Pomerantsev
2015-01-15T23:59:59.000Z
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.
Logue, J. M.; Turner, W. J.N.; Walker, I. S.; Singer, B. C.
2015-01-01T23:59:59.000Z
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, Jennifer M.
2014-01-01T23:59:59.000Z
weather files for representative cities within each climatewas modeled in the representative city for each of the sevenclimate zones and representative cities were used: 2A hot/
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...
Constraints on AGN accretion disc viscosity derived from continuum variability
Rhaana L. C. Starling; Aneta Siemiginowska; Phil Uttley; Roberto Soria
2003-09-10T23:59:59.000Z
We estimate a value of the viscosity parameter in AGN accretion discs for the PG quasar sample. We assume that optical variability on time-scales of months to years is caused by local instabilities in the inner accretion disc. Comparing the observed variability time-scales to the thermal time-scales of alpha-disc models we obtain constraints on the viscosity parameter for the sample. We find that, at a given L/L_Edd, the entire sample is consistent with a single value of the viscosity parameter, alpha. We obtain constraints of 0.01 < alpha < 0.03 for 0.01 < L/L_Edd < 1.0. This narrow range suggests that these AGN are all seen in a single state, with a correspondingly narrow spread of black hole masses or accretion rates. The value of alpha we derive is consistent with predictions by current simulation s in which MHD turbulence is the primary viscosity mechanism.
A density functional theory model of mechanically activated silyl ester hydrolysis
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
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.
ES2A7 -Fluid Mechanics Example Classes Model Answers to Example Questions (Set II)
Thomas, Peter J.
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
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.
MECHANICAL TEST RESULTS ON DIPOLE MODEL C-l 25 mm ALUMINUM COLLARS
Peters, C.
2010-01-01T23:59:59.000Z
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
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
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.
Competing mechanisms of chiral symmetry breaking in a generalized Gross-Neveu model
Boehmer, Christian; Thies, Michael [Institut fuer Theoretische Physik III, Universitaet Erlangen-Nuernberg, D-91058 Erlangen (Germany)
2010-05-15T23:59:59.000Z
Chiral symmetry of the 2-dimensional chiral Gross-Neveu model is broken explicitly by a bare mass term as well as a splitting of scalar and pseudoscalar coupling constants. The vacuum and light hadrons--mesons and baryons which become massless in the chiral limit--are explored analytically in leading order of the derivative expansion by means of a double sine-Gordon equation. Depending on the parameters, this model features new phenomena as compared to previously investigated 4-fermion models: spontaneous breaking of parity, a nontrivial chiral vacuum angle, twisted kinklike baryons whose baryon number reflects the vacuum angle, crystals with alternating baryons, and appearance of a false vacuum.
Hernelind, J.
2009-01-01T23:59:59.000Z
Time ( day) Measured SKI STUK SKB JAEA (b) Relative humidityROCMAS SKB (Sweden) ABAQUS STUK (Finland) ELMER 2. OUTLINEunit volume. 3.5 The STUK model The numerical calculations
3D Modeling of Coupled Rock Deformation and Thermo-Poro-Mechanical Processes in Fractures
Rawal, Chakra
2012-07-16T23:59:59.000Z
and failure of weak planes of the formation with creation of new fractures, which impacts reservoir response. Incorporation of geomechanical factor into engineering analyses using fully coupled geomechanics-reservoir flow modeling exhibits computational...
NUMERICAL MODELING FOR THE FORMATION MECHANISM OF 3D TOPOGRAPHY ON MICROBIAL MAT SURFACES
Patel, Harsh Jay
2013-09-27T23:59:59.000Z
, an innovative modeling approach was employed that focuses on the interface growth of the microbial mat surfaces using a combined stochastic and deterministic approach. A range of different initial conditions were simulated to evaluate the 3D topography evolution...
Andersohn, Alexander
2013-08-27T23:59:59.000Z
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...
Derivation of Newton's Law of Gravitation Based on a Fluid Mechanical Singularity Model of Particles
Xiao-Song Wang
2006-10-25T23:59:59.000Z
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.
Particle-scale CO2 adsorption kinetics modeling considering three reaction mechanisms
Suh, Dong-Myung; Sun, Xin
2013-09-01T23:59:59.000Z
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.
Central engines of Gamma Ray Bursts. Magnetic mechanism in the collapsar model
Maxim V. Barkov; Serguei S. Komissarov
2008-09-08T23:59:59.000Z
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
Harris, D.O.; Lim, E.Y.; Dedhia, D.D.; Woo, H.H.; Chou, C.K.
1982-06-01T23:59:59.000Z
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.
QCD thermodynamics with continuum extrapolated Wilson fermions II
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
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.
QCD thermodynamics with continuum extrapolated Wilson fermions II
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
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.
Continuum and line emission of flares on red dwarf stars
Morchenko, Egor; Livshits, Moisey
2015-01-01T23:59:59.000Z
The emission spectrum has been calculated of a homogeneous pure hydrogen layer, which parameters are typical for a flare on a red dwarf. The ionization and excitation states were determined by the solution of steady-state equations taking into account the continuum and all discrete hydrogen levels. We consider the following elementary processes: electron-impact transitions, spontaneous and induced radiative transitions, and ionization by the bremsstrahlung and recombination radiation of the layer itself. The Biberman--Holstein approximation was used to calculate the scattering of line radiation. Asymptotic formulae for the escape probability are obtained for a symmetric line profile taking into account the Stark and Doppler effects. The approximation for the core of the H$-\\alpha$ line by a gaussian curve has been substantiated. The spectral intensity of the continuous spectrum, the intensity of the lines of the Balmer series and the magnitude of the Balmer jump have been calculated. The conditions have been ...
UMBRAL DYNAMICS IN THE NEAR-INFRARED CONTINUUM
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
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.
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
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.
Welch, Stephen; Miles, Steward; Kumar, Suresh; Lemaire, Tony; Chan, Alan
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. ...
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
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.
Mechanisms of Selenate Adsorption on Iron Oxides and Hydroxides
Sparks, Donald L.
- bonding mechanisms on hematite, goethite, and hydrous ferric oxide (HFO). It was learned that selenate-sphere surface complexes on goethite and HFO. This continuum of adsorption mechanisms is strongly affected for thesurfaceandimpliesthatthesamemechanismsarepresent in both systems. Zhang and Sparks (1) analyzed selenate adsorption on goethite using a triple
Continuum Mechanics and Thermodynamics manuscript No. (will be inserted by the editor)
softening often occurs, and may induce catastrophic events, such as adiabatic shear failure in metals [6@lmt.ens-cachan.fr H. Trumel CEA, DAM Le Ripault F-37260 Monts, France. Tel.: (33) 2 47 34 44 12 Fax: (33) 2 47 34 E
Applications of a new theory extending continuum mechanics to the nanoscale
Fu, Kaibin
2005-11-01T23:59:59.000Z
for three different sizes of the bubble. . . . . . . 100 V Computational results from Equation (5.60). . . . . . . . . . . . . . . 100 x LIST OF FIGURES FIGURE Page 1 A material body consisting of two adjoining phases, A and B. . . . . 13 2 Two semi... observations are from Specovius and Findenegg (1978). The dashed-dot curve represents the computations of Sokolowski (1982). . 19 4 ?? (? mol/m2) as a function of P (MPa) for argon on Graphon at 25?C predicted by (2.11) (the solid curve). The experimental...
Persistent energy flow for a stochastic wave equation model in nonequilibrium statistical mechanics
Lawrence E. Thomas
2012-04-29T23:59:59.000Z
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.
Barker, Erin I.; Choi, Kyoo Sil; Sun, Xin; Deda, Erin; Allison, John; Li, Mei; Forsmark, Joy; Zindel, Jacob; Godlewski, Larry
2014-09-30T23:59:59.000Z
Magnesium alloys have become popular alternatives to aluminums and steels for the purpose of vehicle light-weighting. However, Mg alloys are hindered from wider application due to limited ductility as well as poor creep and corrosion performance. Understanding the impact of microstructural features on bulk response is key to improving Mg alloys for more widespread use and for moving towards truly predicting modeling capabilities. This study focuses on modeling the intrinsic features, particularly volume fraction and morphology of beta phase present, of cast Mg alloy microstructure and quantifying their impact on bulk performance. Computational results are compared to experimental measurements of cast plates of Mg alloy with varying aluminum content.
A quantum mechanical model for the relationship between stock price and stock ownership
Liviu-Adrian Cotfas
2012-09-05T23:59:59.000Z
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.
Melanin, a promising radioprotector: Mechanisms of actions in a mice model
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
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.
Chen, Reuven
, Denmark c Nordic Laboratory for Luminescence Dating, Department of Earth Science, Aarhus University, RisÃ¸ 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
Physiologically realistic modelling of a mechanism for neural representation of intervals of time
Fukai, Tomoki
-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
Multi-Configuration Model Tuning for Precision Opto-Mechanical Systems
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
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.
A Mathematical Analysis of Atomistic-to-Continuum (AtC) Multiscale Coupling Methods
Gunzburger, Max
2013-11-13T23:59:59.000Z
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.
Kelkar, Sharad [Los Alamos National Laboratory
2011-01-01T23:59:59.000Z
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.
Nguyen, Ba Nghiep; Kunc, Vlastimil; Jin, Xiaoshi; Tucker III, Charles L.; Costa, Franco
2013-12-18T23:59:59.000Z
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.
W. F. Wall
2007-03-26T23:59:59.000Z
Far-infrared continuum data from the {\\it COBE}/{\\it DIRBE} instrument were combined with Nagoya 4-m $\\cOone$ spectral line data to infer the multiparsec-scale physical conditions in the Orion$ $A and B molecular clouds, using 140$\\um$/240$\\um$ dust color temperatures and the 240$\\um$/$\\cOone$ intensity ratios. In theory, the ratio of far-IR, submillimeter, or millimeter continuum to that of a $\\cO$ (or $\\Co$) rotational line can place reliable upper limits on the temperature of the dust and molecular gas on multi-parsec scales; on such scales, both the line and continuum emission are optically thin, resulting in a continuum-to-line ratio that suffers no loss of temperature sensitivity in the high-temperature limit as occurs for ratios of CO rotational lines or ratios of continuum emission in different wavelength bands. Two-component models fit the Orion data best, where one has a fixed-temperature and the other has a spatially varying temperature. The former represents gas and dust towards the surface of the clouds that are heated primarily by a very large-scale (i.e. $\\sim 1 $kpc) interstellar radiation field. The latter represents gas and dust at greater depths into the clouds and are shielded from this interstellar radiation field and heated by local stars. The inferred physical conditions are consistent with those determined from previously observed maps of $\\COone$ and $\\Jtwo$ that cover the entire Orion$ $A and B molecular clouds. The models require that the dust-gas temperature difference is 0$\\pm 2 $K. If this surprising result applies to much of the Galactic ISM, except in unusual regions such as the Galactic Center, then there are a number implications.
Salloum, Maher N.; Shugard, Andrew D.; Kanouff, Michael P.; Gharagozloo, Patricia E.
2013-03-01T23:59:59.000Z
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.
Modeling Regional Air Quality Using the Near-Explicit Master Chemical Mechanism
Li, Jingyi
2014-08-01T23:59:59.000Z
C. ................................................................................................................. 32 Figure 2-6 Pollutant rose for isopentane at C35C. Panels (a)-(c) are based on the data where the predicted wind direction and wind speed agree well with observations. Panels (d)-(f) are based on the remaining data. Units are ppb... during the entire episode. Model performance criteria and goals for particulate matter are based on the recommendations of Boylan and Russell (2006). MFB=2/N×?(Cp-Co)/(Cp+Co). Cp=predictions; Co=observations; N=number of data points. (b) Predicted...
Class of model problems in three-body quantum mechanics that admit exact solutions
Takibayev, N. Zh., E-mail: teta@nursat.kz [Abay Kazakh National Pedagogical University (Kazakhstan)
2008-03-15T23:59:59.000Z
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.
Zhai, Yuhu
2013-07-16T23:59:59.000Z
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.
Benioff, P.
1980-01-01T23:59:59.000Z
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.
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
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.
Robert Podgorney; Chuan Lu; Hai Huang
2012-01-01T23:59:59.000Z
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.
California at Riverside, University of
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 Â°C for 40 min realized a maximum monomeric plus oligomeric
Paris-Sud XI, Université de
Impact of drainage on soil-forming mechanisms in a French Albeluvisol: Input of mineralogical data. This was considered as a model case to study the velocity of mineralogical changes in soil as a result of eluviation modelling based on mineralogical data in order to identify and characterise the mineralogical
Rodriguez, David
2011-01-01T23:59:59.000Z
Experimental tests of Bell inequalities often require supplementary assumptions, one of the usual ones being the "no-enhancement" assumption. Here we show how an already well known Local Hidden Variables (LHV) model for the Clauser-Horne-Shimony-Holt inequality, when extended to account for the probabilities of detection when the polarizers are removed (such as how it would need to be done in a test of the Clauser-Horne inequality), gives rise, as the most natural feature, to the so-called "enhancement" (breaking of the no-enhancement assumption formulated by Clauser and Horne themselves for the operational expression of their inequality). Aside from exposing that key role of enhancement, our work is useful (at least in our case it has been) to gain understanding on some other known results. We also add some comments that we think may be thought-provoking.
A unified electrostatic and cavitation model for first-principles molecular dynamics in solution
Damian A. Scherlis; Jean-Luc Fattebert; Francois Gygi; Matteo Cococcioni; Nicola Marzari
2005-10-06T23:59:59.000Z
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.
Buyukdagli, Sahin; 10.1016/j.cplett.2009.11.061
2010-01-01T23:59:59.000Z
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.
Goudreau, G.L.
1993-03-01T23:59:59.000Z
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.
Karl Svozil
2001-06-29T23:59:59.000Z
Three extensions and reinterpretations of nonclassical probabilities are reviewed. (i) We propose to generalize the probability axiom of quantum mechanics to self-adjoint positive operators of trace one. Furthermore, we discuss the Cartesian and polar decomposition of arbitrary normal operators and the possibility to operationalize the corresponding observables. Thereby we review and emphasize the use of observables which maximally represent the context. (ii) In the second part, we discuss Pitowsky polytopes for automaton logic as well as for generalized urn models and evaluate methods to find the resulting Boole-Bell type (in)equalities. (iii) Finally, so-called ``parameter cheats'' are introduced, whereby parameters are transformed bijectively and nonlinearly in such a way that classical systems mimic quantum correlations and vice versa. It is even possible to introduce parameter cheats which violate the Boole-Bell type inequalities stronger than quantum ones, thereby trespassing the Tsirelson limit. The price to be paid is nonuniformity.
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...
Development Status of the PEBBLES Code for Pebble Mechanics: Improved Physical Models and Speed-up
Joshua J. Cogliati; Abderrafi M. Ougouag
2009-12-01T23:59:59.000Z
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.
Modeling mechanical properties of core-shell rubber-modified epoxies
Wang, X.; Xiao, K.; Ye, L.; Mai, Y.W.; Wang, C.H.; Rose, L.R.F.
2000-01-24T23:59:59.000Z
Experiments have been carried out to quantify the effects of rubber content and strain rate on the elastic and plastic deformation behavior of core-shell rubber-modified epoxies. Both the Young's modulus and the yield stress were found to be slightly dependent on strain rate, but very sensitive to the volume fraction of rubber particles. Finite element analyses have also been performed to determine the influences of rubber content on the bulk elasticity modulus and the yield stress. By comparing with experimental results, it is found that the Young's modulus of rubber-toughened epoxies can be accurately estimated using the Mori-Tanaka method, provided that the volume fraction of rubber particles is appropriately evaluated. A yield function is provided that the volume fraction of rubber particles is appropriately evaluated. A yield function is proposed to quantify the effects of hydrostatic stress on the plastic yielding behaviors of rubber-modified epoxies. Agreement with experimental results is good. Also, a visco-plastic model is developed to simulate the strain-rate-dependent stress-strain relations.
Model checking quantum Markov chains
Yuan Feng; Nengkun Yu; Mingsheng Ying
2013-11-14T23:59:59.000Z
Although the security of quantum cryptography is provable based on the principles of quantum mechanics, it can be compromised by the flaws in the design of quantum protocols and the noise in their physical implementations. So, it is indispensable to develop techniques of verifying and debugging quantum cryptographic systems. Model-checking has proved to be effective in the verification of classical cryptographic protocols, but an essential difficulty arises when it is applied to quantum systems: the state space of a quantum system is always a continuum even when its dimension is finite. To overcome this difficulty, we introduce a novel notion of quantum Markov chain, specially suited to model quantum cryptographic protocols, in which quantum effects are entirely encoded into super-operators labelling transitions, leaving the location information (nodes) being classical. Then we define a quantum extension of probabilistic computation tree logic (PCTL) and develop a model-checking algorithm for quantum Markov chains.
Model checking quantum Markov chains
Feng, Yuan; Ying, Mingsheng
2012-01-01T23:59:59.000Z
Although the security of quantum cryptography is provable based on the principles of quantum mechanics, it can be compromised by the flaws in the design of quantum protocols and the noise in their physical implementations. So, it is indispensable to develop techniques of verifying and debugging quantum cryptographic systems. Model-checking has proved to be effective in the verification of classical cryptographic protocols, but an essential difficulty arises when it is applied to quantum systems: the state space of a quantum system is always a continuum even when its dimension is finite. To overcome this difficulty, we introduce a novel notion of quantum Markov chain, specially suited to model quantum cryptographic protocols, in which quantum effects are entirely encoded into super-operators labelling transitions, leaving the location information (nodes) being classical. Then we define a quantum extension of probabilistic computation tree logic (PCTL) and develop a model-checking algorithm for quantum Markov c...
Chaos and Quantumlike Mechanics in Atmospheric Flows : A Superstring Theory for Supergravity
A. Mary Selvam
1997-10-22T23:59:59.000Z
The author has identified quantumlike mechanics in atmospheric flows with intrinsic nonlocal space-time connections manifested as the selfsimilar fractal geometry to the global cloud cover pattern concomitant with inverse power law form for power spectra of temporal fluctuations. Such long-range spatiotemporal correlations are generic to dynamical systems in nature and are recently identified as signatures of selforganized criticality, a field of study belonging to the newly emerging discipline of nonlinear dynamics and chaos. The author has presented a universal thory of chaos which postulates that spatial integration of enclosed small scale fluctuations result in the generation of a hierarchical scale invariant eddy continuum(network) with ordered two-way energy flow between the scales. The model concepts lead to the following results. (1) The eddy energy spectrum follows normal distribution characteristics,i.e.,the square of the eddy amplitude represents the probability density,a result which is observed in the subatomic dynamics of quantum systems. (2) Wave-particle duality is attributed to the bimodal (formation and dissipation) phenomenological form for manifestation of energy in the bidirectional energy flow intrinsic to eddy circulations,e.g., formation and dissipation respectively of clouds in updrafts and downdrafts of atmospheric eddies. (3) The nested continuum of eddy flow trajectories follow Kepler's third law of planetary motion. Therefore,inverse square law form for centripetal force, representing inertial or gravitational force is intrinsic to the hierarchical eddy continuum. The above model is analogous to a superstring model where manifestation of matter is visualised as vibrational modes in stringlike energy flow patterns.
The nature and size of the optical continuum source in QSO 2237+0305
V. N. Shalyapin; L. J. Goicoechea; D. Alcalde; E. Mediavilla; J. A. Munoz; R. Gil-Merino
2002-07-11T23:59:59.000Z
From the peak of a gravitational microlensing high-magnification event in the A component of QSO 2237+0305, which was accurately monitored by the GLITP collaboration, we derived new information on the nature and size of the optical V-band and R-band sources in the far quasar. If the microlensing peak is caused by a microcaustic crossing, we firstly obtained that the standard accretion disk is a scenario more reliable/feasible than other usual axially symmetric models. Moreover, the standard scenario fits both the V-band and R-band observations with reduced chi-square values very close to one. Taking into account all these results, a standard accretion disk around a supermassive black hole is a good candidate to be the optical continuum main source in QSO 2237+0305. Secondly, using the standard source model and a robust upper limit on the transverse galactic velocity, we inferred that 90 per cent of the V-band and R-band luminosities are emitted from a region with radial size less than 1.2 10^{-2} pc (= 3.7 10^{16} cm, at 2*sigma confidence level).
Bo Jakobsen; Kristine Niss; Claudio Maggi; Niels Boye Olsen; Tage Christensen; Jeppe C. Dyre
2010-05-26T23:59:59.000Z
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.
Low Energy Continuum and Lattice Effective Field Theories
Serdar Elhatisari
2014-09-14T23:59:59.000Z
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.
Gradient Plasticity Model and its Implementation into MARMOT
Barker, Erin I.; Li, Dongsheng; Zbib, Hussein M.; Sun, Xin
2013-08-01T23:59:59.000Z
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.
Techniques to treat the continuum applied to electromagnetictransitions in $^8$Be
E. Garrido; A. S. Jensen; D. V. Fedorov
2013-12-20T23:59:59.000Z
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.
Caflisch, Amedeo
Continuum Electrostatic Energies of Macromolecules in Aqueous Solutions Marco Scarsi, Joannis evaluation of electrostatic energies of macromolecules in aqueous solutions is useful for many problems for obtaining correct electrostatic energies of molecules in solution. In addition, it is demonstrated
Suslick, Kenneth S.
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
Schlegel, Nicole-Jeanne
2011-01-01T23:59:59.000Z
ice sheet model with a mesoscale climate model By Nicole-ice sheet model with a mesoscale climate model Copyrightice sheet model with a mesoscale climate model by Nicole-
Modeling of microstructural effects on electromigration failure
Ceric, H. [Christian Doppler Laboratory for Reliability Issues in Microelectronics at the Institute for Microelectronics, TU Wien (Austria); Orio, R. L. de; Zisser, W.; Selberherr, S. [Institute for Microelectronics, TU Wien, Gußhausstraße 27-29, A-1040 Wien (Austria)
2014-06-19T23:59:59.000Z
Current electromigration models used for simulation and analysis of interconnect reliability lack the appropriate description of metal microstructure and consequently have a very limited predictive capability. Therefore, the main objective of our work was obtaining more sophisticated electromigration tools. The problem is addressed through a combination of different levels of atomistic modeling and already available, continuum level macroscopic models. A novel method for an ab initio calculation of the effective valence for electromigration is presented and its application on the analysis of EM behavior is demonstrated. Additionally, a simple analytical model for the early electromigration lifetime is obtained. We have shown that its application provides a reasonable estimate for the early electromigration failures including the effect of microstructure. A simulation study is also applied on electromigration failure in tin solder bumps, where it contributed the understanding of the role of tin crystal anisotropy in the degradation mechanism of solder bumps.
$^4{\\rm He}$+$n$+$n$ continuum within an ab initio framework
Carolina Romero-Redondo; Sofia Quaglioni; Petr Navrátil; Guillaume Hupin
2014-04-07T23:59:59.000Z
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.
Titus, M. J.; Graves, D. B. [Department of Chemical Engineering, University of California, Berkeley, California 94720 (United States)
2008-09-15T23:59:59.000Z
The authors report measurements and modeling of wafer heating mechanisms in an Ar/O{sub 2} inductively coupled plasma (ICP). The authors employed a commercially available on-wafer sensor system (PlasmaTemp developed by KLA-Tencor) consisting of an on-board electronics module housing battery power and data storage with 30 temperature sensors embedded onto the wafer at different radial positions. This system allows for real time, in situ wafer temperature measurements. Wafer heating mechanisms were investigated by combining temperature measurements from the PlasmaTemp sensor wafer with a three-dimensional heat transfer model of the wafer and a model of the ICP. Comparisons between pure Ar and Ar/O{sub 2} discharges demonstrated that two additional wafer heating mechanisms can be important in molecular gas plasmas compared to atomic gas discharges. The two mechanisms are heating from the gas phase and O-atom surface recombination. These mechanisms were shown to contribute as much as 60% to wafer heating under conditions of low bias power. This study demonstrated how the 'on-wafer' temperature sensor not only yields a temperature profile distribution across the wafer, but can be used to help determine plasma characteristics, such as ion flux profiles or plasma processing temperatures.
Lerebours, C; Scheiner, S; Pivonka, P
2015-01-01T23:59:59.000Z
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...
Shuanhu Qi; Hans Behringer; Friederike Schmid
2013-09-26T23:59:59.000Z
We develop a multiscale hybrid scheme for simulations of soft condensed matter systems, which allows one to treat the system at the particle level in selected regions of space, and at the continuum level elsewhere. It is derived systematically from an underlying particle-based model by field theoretic methods. Particles in different representation regions can switch representations on the fly, controlled by a spatially varying tuning function. As a test case, the hybrid scheme is applied to simulate colloid-polymer composites with high resolution regions close to the colloids. The hybrid simulations are significantly faster than reference simulations of a pure particle-based model, and the results are in good agreement.
Raboin, P J
1998-01-01T23:59:59.000Z
The Computational Mechanics thrust area is a vital and growing facet of the Mechanical Engineering Department at Lawrence Livermore National Laboratory (LLNL). This work supports the development of computational analysis tools in the areas of structural mechanics and heat transfer. Over 75 analysts depend on thrust area-supported software running on a variety of computing platforms to meet the demands of LLNL programs. Interactions with the Department of Defense (DOD) High Performance Computing and Modernization Program and the Defense Special Weapons Agency are of special importance as they support our ParaDyn project in its development of new parallel capabilities for DYNA3D. Working with DOD customers has been invaluable to driving this technology in directions mutually beneficial to the Department of Energy. Other projects associated with the Computational Mechanics thrust area include work with the Partnership for a New Generation Vehicle (PNGV) for ''Springback Predictability'' and with the Federal Aviation Administration (FAA) for the ''Development of Methodologies for Evaluating Containment and Mitigation of Uncontained Engine Debris.'' In this report for FY-97, there are five articles detailing three code development activities and two projects that synthesized new code capabilities with new analytic research in damage/failure and biomechanics. The article this year are: (1) Energy- and Momentum-Conserving Rigid-Body Contact for NIKE3D and DYNA3D; (2) Computational Modeling of Prosthetics: A New Approach to Implant Design; (3) Characterization of Laser-Induced Mechanical Failure Damage of Optical Components; (4) Parallel Algorithm Research for Solid Mechanics Applications Using Finite Element Analysis; and (5) An Accurate One-Step Elasto-Plasticity Algorithm for Shell Elements in DYNA3D.
NONE
1998-09-01T23:59:59.000Z
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.
Li, Teng
oxide thin films on polyimide substrates Cheng Peng,1 Zheng Jia,2 Dan Bianculli,1 Teng Li,2,a) and Jun thicknesses (200 and 80 nm) deposited on polyimide substrates inside a scanning electron microscope. The crack model, the cohesive toughness and fracture strength of ITO thin films and the ITO/polyimide interfacial
Paris-Sud XI, Université de
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
Pore-scale study of capillary trapping mechanism during CO2 injection in geological formations
Bandara, Uditha C.; Tartakovsky, Alexandre M.; Palmer, Bruce J.
2011-11-01T23:59:59.000Z
Geological sequestration of CO{sub 2} gas emerged as a promising solution for reducing amount of green house gases in atmosphere. A number of continuum scale models are available to describe the transport phenomena of CO{sub 2} sequestration. These models rely heavily on a phenomenological description of subsurface transport phenomena and the predictions can be highly uncertain. Pore-scale models provide a better understanding of fluid displacement processes, nonetheless such models are rare. In this work we use a Smoothed Particle Hydrodynamics (SPH) model to study pore-scale displacement and capillary trapping mechanisms of super-critical CO{sub 2} in the subsurface. Simulations are carried out to investigate the effects of gravitational, viscous, and capillary forces in terms of Gravity, Capillary, and Bond numbers. Contrary to the other published continuum scale investigations, we found that not only Gravity number but also Capillary number plays an important role on the fate of injected CO{sub 2}. For large Gravity numbers (on the order of 10), most of the injected CO{sub 2} reaches the cap-rock due to gravity segregation. A significant portion of CO{sub 2} gets trapped by capillary forces when Gravity number is small (on the order of 0.1). When Gravity number is moderately high (on the order of 1), trapping patterns are heavily dependent on Capillary number. If Capillary number is very small (less than 0.001), then capillary forces dominate the buoyancy forces and a significant fraction of injected CO{sub 2} is trapped by the capillary forces. Conversely, if Capillary number is high (higher than 0.001), capillary trapping is relatively small since buoyancy dominates the capillary forces. In addition, our simulations reveal different types of capillary trapping and flow displacement mechanisms during and after injection. In gravity dominated cases leave behind was the widespread trapping mechanism. Division was the primary trapping mechanism in viscous dominated cases. In capillary dominated cases, snap-off of the CO{sub 2} plume is the most commonly observed displacement mechanism. Large CO{sub 2} blobs are created due to coalescence mechanism.
Progress in Statistical Crack Mechanics : An Approach to Initiation
Dienes, John K.; Middleditch, J. (John); Kershner, James D.; Zuo, Q. K. (Qiuhai K.); Starobin, A. J. (Andre J.)
2002-01-01T23:59:59.000Z
We have developed a general theory for the formation of hot spots from defects in explosives and propellants, and applied the theory to a variety of issues concerning the sensitivity of reactive materials. The defects of greatest concern in PBXs are cracks formed in the explosive grains, which are normally brittle. The theory accounts for the opening, shear, growth, and coalescence of cracks. In addition, the theory accounts for the heating caused by interfacial friction in closed (shear) cracks and the ignition process that results. Heat conduction and chemical reactions are treated on a smaller spatial scale than the overall continuum response; this is accomplished in the numerical (FEA) simulation with a sub-grid model. In previous work we have shown the feasibility of using this approach to model explosions that result from relatively mild insults, where many other hot-spot mechanisms fail. This paper addresses some of the complications that arise as mechanical failure and heating are examined in greater detail, including the effects of crack orientation, friction, melting, viscosity in molten regions, radial crack formation via a new approach to percolation theory, and 3-D effects.
Model error estimation in composite impact response prediction using hierarchical Bayes networks
Salas Mendez, Pablo Antonio
2010-01-01T23:59:59.000Z
in Progressive Failure Analysis . . . 4.0.2 ModelingPuck and H. Schurmann, “Failure analysis of frp laminates byComposite laminate failure analysis using multi- continuum
Detection of the thermal radio continuum emission from the G9.62+0.19-F Hot Core
L. Testi; P. Hofner; S. Kurtz; M. Rupen
2000-06-15T23:59:59.000Z
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.
NREL: Continuum Magazine - Building Better: Advanced Energy Design...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
case study for the AEDG for K-12 School Buildings: Achieving 50% Energy Savings Toward a Net Zero Energy Building. More than 200,000 energy model runs are needed to develop a...
Rutqvist, Jonny; Majer, Ernie; Oldenburg, Curt; Peterson, John; Vasco, Don
2006-01-01T23:59:59.000Z
coupled reservoir geomechanical numerical modeling, (2) datacoupled reservoir geomechanical numerical modeling, (2) datareservoir geomechanical analysis will be corroborated with, and constrained by, data
Mechanical Engineering Department Seminar Series
Papalambros, Panos
Challenges through Modeling, Control and Design Micheal Zinn Associate Professor, Mechanical & Biomedical overcome them, we have undertaken a coordinated effort to develop improved modeling, controls, and device manipulation approaches. The modeling investigation has focused on developing improved models by which
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
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.
Li, Jingyi
2012-02-14T23:59:59.000Z
aldehydes generated from parent VOCs are tracked separately using tagged reactive species approach (Ying and Krishnan, 2010). As an example, the freshly emitted formaldehyde in the mechanisms is tracked using species HCHO, while the secondary formaldehyde...
Miller, Kyle M. (Kyle Mark)
2014-01-01T23:59:59.000Z
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 ...
Geyer, Hartmut
While neuroscientists identify increasingly complex neural circuits that control animal and human gait, biomechanists find that locomotion requires little control if principles of legged mechanics are heeded that shape and ...
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
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.
On the continuum limit of gauge-fixed compact U(1) lattice gauge theory
Subhasish Basak; Asit K De; Tilak Sinha
2003-11-26T23:59:59.000Z
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.
From Discrete Space-Time to Minkowski Space: Basic Mechanisms, Methods and Perspectives
Felix Finster
2008-02-22T23:59:59.000Z
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.
Karahan, Aydin
2009-01-01T23:59:59.000Z
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 ...
Continuum limit physics from 2+1 flavor domain wall QCD
Aoki, Y.; Izubuchi, T.; Arthur, R.; Blum, T.; Boyle, P.A.; Brommel, D.; Christ, N.H.; Dawson, C.; Flynn, J.M.; Jin, X.Y.; Jung, C.; Kelly, C.; Li, M.; Lichtl, A.; Lightman, M.; Lin, M.F.; Mawhinney, R.D.; Maynard,C.M.; Ohta, S.; Pendleton, B.J.; Sachrajda, C.T.; Scholz, E.E.; Soni, A.; Wennekers, J.; Zanotti, J.M.; Zhou, R.
2011-04-22T23:59:59.000Z
We present physical results obtained from simulations using 2+1 flavors of domain wall quarks and the Iwasaki gauge action at two values of the lattice spacing a, [a{sup -1} = 1.73(3) GeV and a{sup -1} = 2.28(3) GeV]. On the coarser lattice, with 24{sup 3} x 64 x 16 points (where the 16 corresponds to L{sub s}, the extent of the 5th dimension inherent in the domain wall fermion formulation of QCD), the analysis of C. Allton et al. Phys. Rev. D 78 is extended to approximately twice the number of configurations. The ensembles on the finer 32{sup 3} x 64 x 16 lattice are new. We explain in detail how we use lattice data obtained at several values of the lattice spacing and for a range of quark masses in combined continuum-chiral fits in order to obtain results in the continuum limit and at physical quark masses. We implement this procedure for our data at two lattice spacings and with unitary pion masses in the approximate range 290-420 MeV (225-420 MeV for partially quenched pions). We use the masses of the {pi} and K mesons and the {Omega} baryon to determine the physical quark masses and the values of the lattice spacing. While our data in the mass ranges above are consistent with the predictions of next-to-leading order SU(2) chiral perturbation theory, they are also consistent with a simple analytic ansatz leading to an inherent uncertainty in how best to perform the chiral extrapolation that we are reluctant to reduce with model-dependent assumptions about higher order corrections. In some cases, particularly for f{sub {pi}}, the pion leptonic decay constant, the uncertainty in the chiral extrapolation dominates the systematic error. Our main results include f{sub {pi}} = 124(2){sub stat}(5){sub syst} MeV, f{sub K}/f{sub {pi}} = 1.204(7)(25) where f{sub K} is the kaon decay constant, m{sub s}{sup MS} (2 GeV) = (96.2 {+-} 2.7) MeV and m{sub ud}{sup MS} (2 GeV) = (3.59 {+-} 0.21) MeV (m{sub s}/m{sub ud} = 26.8 {+-} 1.4) where m{sub s} and m{sub ud} are the mass of the strange quark and the average of the up and down quark masses, respectively, [{Sigma}{sup MS} (2 GeV)]{sup 1/3} = 256(6) MeV, where {Sigma} is the chiral condensate, the Sommer scale r{sub 0} = 0.487(9) fm and r{sub 1} = 0.333(9) fm.
Continuum Extrapolation of Moments of Nucleon Quark Distributions in Full QCD
Dreher, P; Capitani, S; Dolgov, D S; Edwards, R; Eicker, N; Heller, U M; Lipert, T; Negele, J W; Pochinsky, A V; Renner, D B; Schilling, K; Lipert, Th.
2002-01-01T23:59:59.000Z
Moments of light cone quark density, helicity, and transversity distributions are calculated in unquenched lattice QCD at $\\beta = 5.5$ and $\\beta = 5.3$ using Wilson fermions on $ 16^3 \\times 32 $ lattices. These results are combined with earlier calculations at $\\beta = 5.6$ using SESAM configurations to study the continuum limit.
Deliberate Science, Continuum Magazine: Clean Energy Innovation at NREL, Winter 2012 (Book)
Not Available
2012-02-01T23:59:59.000Z
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.
Continuum limit for three-dimensional mass-spring networks and discrete Korn's inequality.
Berlyand, Leonid
) and the domain sizes (large scale)), which represents local energy in the neighborhood of a point. For periodic a discrete network of a large number of concen- trated masses (particles) connected by elastic springs. We. For generic non-periodic arrays of particles we describe continuum limit in terms of local energy
ORIGINAL RESEARCH Minerals Form a Continuum Phase in Mature Cancellous Bone
Price, Paul A.
ORIGINAL RESEARCH Minerals Form a Continuum Phase in Mature Cancellous Bone Po-Yu Chen · Damon the hierarchical structure of mineral in mature bone. A method to completely deproteinize bone without altering of mineral and protein constituents. SEM revealed that bone minerals are fused together and form a sheet
Microscale gas flow: A comparison of Grad's 13 moment equations and other continuum approaches
Victoria, University of
Microscale gas flow: A comparison of Grad's 13 moment equations and other continuum approaches are being manufactured in quantity [2][3], e.g., pumps, turbines, valves and nozzles. These devices and chemical sensors, and fuel cells. The gas and fluid flows in devices of this size exhibit behavior that can
Caflisch, Amedeo
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
Classical Trajectories of the Continuum States of the ${\\cal{PT}}$ symmetric Scarf II potential
Anjana Sinha
2012-06-29T23:59:59.000Z
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.
Ringhofer, Christian
is of the order of weeks. The production planning problem, i.e. to control the outflux of a factory, the push-pull point (PPP), along the production line. The paper showed that the heuristic PPP controlA continuum description for a DES control problem Dieter Armbruster, Michael Herty and Christian
W. F. Wall
2006-01-24T23:59:59.000Z
The reliability of modeling the far-IR continuum to 13CO J=1-0 spectral line ratios applied to the Orion clouds (Wall 2006) is tested by applying the models to simulated data. The two-component models are found to give the dust-gas temperature difference, $\\DT$, to within 1 or 2$ $K. However, other parameters like the column density per velocity interval and the gas density can be wrong by an order of magnitude or more. In particular, the density can be systematically underestimated by an order of magnitude or more. The overall mass of the clouds is estimated correctly to within a few percent. The one-component models estimate the column density per velocity interval and density within factors of 2 or 3, but their estimates of $\\DT$ can be wrong by 20$ $K. They also underestimate the mass of the clouds by 40-50%. These results may permit us to reliably constrain estimates of the Orion clouds' physical parameters, based on the real observations of the far-IR continuum and 13CO J=1-0 spectral line. Nevertheless, other systematics must be treated first. These include the effects of background/foreground subtraction, effects of the HI component of the ISM, and others. These will be discussed in a future paper (Wall 2006a).
CONTINUUM CONTRIBUTIONS TO THE SDO/AIA PASSBANDS DURING SOLAR FLARES
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
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.
Smets, Quentin; Verreck, Devin; Vandervorst, Wilfried; Groeseneken, Guido; Heyns, Marc M. [Imec, Kapeldreef 75, 3001 Heverlee (Belgium); KULeuven, 3001 Leuven (Belgium); Verhulst, Anne S.; Rooyackers, Rita; Merckling, Clément; Simoen, Eddy; Collaert, Nadine; Thean, Voon Y. [Imec, Kapeldreef 75, 3001 Heverlee (Belgium); Van De Put, Maarten; Sorée, Bart [Imec, Kapeldreef 75, 3001 Heverlee (Belgium); Universiteit Antwerpen, 2020 Antwerpen (Belgium)
2014-05-14T23:59:59.000Z
Promising predictions are made for III-V tunnel-field-effect transistor (FET), but there is still uncertainty on the parameters used in the band-to-band tunneling models. Therefore, two simulators are calibrated in this paper; the first one uses a semi-classical tunneling model based on Kane's formalism, and the second one is a quantum mechanical simulator implemented with an envelope function formalism. The calibration is done for In{sub 0.53}Ga{sub 0.47}As using several p+/intrinsic/n+ diodes with different intrinsic region thicknesses. The dopant profile is determined by SIMS and capacitance-voltage measurements. Error bars are used based on statistical and systematic uncertainties in the measurement techniques. The obtained parameters are in close agreement with theoretically predicted values and validate the semi-classical and quantum mechanical models. Finally, the models are applied to predict the input characteristics of In{sub 0.53}Ga{sub 0.47}As n- and p-lineTFET, with the n-lineTFET showing competitive performance compared to MOSFET.
Hierarchical Models for Batteries: Overview with Some Case Studies
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
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.
Ehgartner, Brian L.; Sobolik, Steven Ronald; Bean, James E.
2010-07-01T23:59:59.000Z
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.
Wong, K.W. (Kansas Univ., Lawrence, KS (USA). Dept. of Physics and Astronomy); Ching, W.Y. (Missouri Univ., Kansas City, MO (USA). Dept. of Physics)
1990-02-01T23:59:59.000Z
The authors discuss the possibility of both n-type and p-type carrier coupling in the excitonic enhancement model (EEM) for high temperature superconductivity. It is argued that p-type quasi-particles will generally lead to a higher T{sub c} than the n-type. The differences between EEM model and other exciton-related models are illuminated by the corresponding Feynman diagrams for the carrier coupling.
Developing the Galactic Diffuse Emission Model for the GLAST Large Area Telescope
Moskalenko, Igor V.; Strong, Andrew W.; Digel, Seth W.; Porter, Troy A.
2007-04-30T23:59:59.000Z
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.
Multiscale modeling of clay-water systems
Ebrahimi, Davoud
2014-01-01T23:59:59.000Z
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 ...
Triple-decker: Interfacing atomistic-mesoscopic-continuum flow regimes
Fedosov, Dmitry A. [Division of Applied Mathematics, Brown University, 182 George St., Box F, Providence, RI 02912 (United States); Karniadakis, George Em [Division of Applied Mathematics, Brown University, 182 George St., Box F, Providence, RI 02912 (United States)], E-mail: gk@dam.brown.edu
2009-03-01T23:59:59.000Z
Multiscale flow phenomena in microfluidic and biomedical applications require the use of heterogeneous modeling approaches. In this paper we present a hybrid method based on coupling the Molecular Dynamics (MD) method, the Dissipative Particle Dynamics (DPD) method, and the incompressible Navier-Stokes (NS) equations. MD, DPD, and NS are formulated in separate subdomains and are coupled via an overlapping region by communicating state information at the subdomain boundaries. Imposition of boundary conditions in the MD and DPD systems involves particle insertion and deletion, specular wall reflection and body force terms. The latter includes a boundary pressure force in order to minimize near-boundary density fluctuations, and an adaptive shear force which enforces the tangential velocity component of boundary conditions. The triple-decker algorithm is verified for prototype flows, including simple and multi-layer fluids (Couette, Poiseuille, and lid-driven cavity), using highly accurate reference solutions. A zero-thickness interface is also possible if it is aligned with the flow streamlines.
Nanyao Lu; George Helou; Michael W. Werner; Harriet L. Dinerstein; Daniel A. Dale; Nancy A. Silbermann; Sangeeta Malhotra; Charles A. Beichman; Thomas H. Jarrett
2003-01-23T23:59:59.000Z
We present ISO-PHOT spectra of the regions 2.5-4.9um and 5.8-11.6um for a sample of 45 disk galaxies from the U.S. ISO Key Project on Normal Galaxies. The spectra can be decomposed into three spectral components: (1) continuum emission from stellar photospheres, which dominates the near-infrared (2.5- 4.9um; NIR) spectral region; (2) a weak NIR excess continuum, which has a color temperature of ~ 1000K, carries a luminosity of a few percent of the total far-infrared luminosity L(FIR), and most likely arises from the ISM; and (3) the well-known broad emission features at 6.2, 7.7, 8.6 and 11.3 um, which are generally attributed to aromatic carbon particles. These aromatic features in emission (AFEs) dominate the mid-infrared (5.8-11.6 um; MIR) part of the spectrum, and resemble the so-called Type-A spectra observed in many non-stellar sources and the diffuse ISM in our own Galaxy. The relative strengths of the AFEs vary by 15-25% among the galaxies. However, little correlation is seen between these variations and either IRAS 60um-to-100um flux density ratio R(60/100) or the FIR-to-blue luminosity ratio L(FIR)/L(B), suggesting that the observed variations are not a direct consequence of the radiation field differences among the galaxies. We demonstrate that the NIR excess continuum and AFE emission are correlated, suggesting that they are produced by similar mechanisms and similar (or the same) material. On the other hand, as the current star-formation activity increases, the overall strengths of the AFEs and the NIR excess continuum drop significantly with respect to that of the far-infrared emission from large dust grains. This is likely a consequence of the preferential destruction in intense radiation fields of the small carriers responsible for the NIR/AFE emission.
Jain, Antone Kumar
2009-01-01T23:59:59.000Z
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 ...
Schlegel, Nicole-Jeanne
2011-01-01T23:59:59.000Z
in running RCM’s over Greenland to produce high-qualityoutlet glaciers. For Greenland, this detail is specificallyCurrently, no coupled Greenland Ice Sheet model experiment
Zhou, Chongwu
, robotics, and the development of new tools for integrated approaches to concurrent engineeringAME Aerospace & Mechanical Engineering #12;Aerospace and Mechanical Engineers design complex Engineering (AME) students conduct basic and applied research within and across the usual disciplinary
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
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.
Green's function method for strength function in three-body continuum
Y. Suzuki; W. Horiuchi; D. Baye
2010-02-10T23:59:59.000Z
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.
Coupling lattice Boltzmann and continuum equations for flow and reactive transport in porous media.
Coon, Ethan [Los Alamos National Laboratory; Porter, Mark L. [Los Alamos National Laboratory; Kang, Qinjun [Los Alamos National Laboratory; Moulton, John D. [Los Alamos National Laboratory; Lichtner, Peter C. [Los Alamos National Laboratory
2012-06-18T23:59:59.000Z
In spatially and temporally localized instances, capturing sub-reservoir scale information is necessary. Capturing sub-reservoir scale information everywhere is neither necessary, nor computationally possible. The lattice Boltzmann Method for solving pore-scale systems. At the pore-scale, LBM provides an extremely scalable, efficient way of solving Navier-Stokes equations on complex geometries. Coupling pore-scale and continuum scale systems via domain decomposition. By leveraging the interpolations implied by pore-scale and continuum scale discretizations, overlapping Schwartz domain decomposition is used to ensure continuity of pressure and flux. This approach is demonstrated on a fractured medium, in which Navier-Stokes equations are solved within the fracture while Darcy's equation is solved away from the fracture Coupling reactive transport to pore-scale flow simulators allows hybrid approaches to be extended to solve multi-scale reactive transport.
LONG-TERM OPTICAL CONTINUUM COLOR VARIABILITY OF NEARBY ACTIVE GALACTIC NUCLEI
Sakata, Yu; Minezaki, Takeo; Yoshii, Yuzuru; Uchimoto, Yuka Katsuno; Sugawara, Shota [Institute of Astronomy, School of Science, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Kobayashi, Yukiyasu [National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Koshida, Shintaro [Department of Astronomy, School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0013 (Japan); Aoki, Tsutomu; Tomita, Hiroyuki [Kiso Observatory, Institute of Astronomy, School of Science, University of Tokyo, 10762-30 Mitake, Kiso, Nagano 397-0101 (Japan); Enya, Keigo; Suganuma, Masahiro, E-mail: yusakata@ioa.s.u-tokyo.ac.j [Institute of Space and Astronomical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan)
2010-03-01T23:59:59.000Z
We examine whether the spectral energy distribution of optical continuum emission of active galactic nuclei (AGNs) changes during flux variation, based on accurate and frequent monitoring observations of 11 nearby Seyfert galaxies and QSOs carried out in the B, V, and I bands for seven years by the MAGNUM telescope. The multi-epoch flux data in any two different bands obtained on the same night show a very tight linear flux-to-flux relationship for all target AGNs. The flux of the host galaxy within the photometric aperture is carefully estimated by surface brightness fitting to available high-resolution Hubble Space Telescope images and MAGNUM images. The flux of narrow emission lines in the photometric bands is also estimated from available spectroscopic data. We find that the non-variable component of the host galaxy plus narrow emission lines for all target AGNs is located on the fainter extension of the linear regression line of multi-epoch flux data in the flux-to-flux diagram. This result strongly indicates that the spectral shape of AGN continuum emission in the optical region ({approx}4400-7900 A) does not systematically change during flux variation. The trend of spectral hardening that optical continuum emission becomes bluer as it becomes brighter, which has been reported by many studies, is therefore interpreted as the domination of the variable component of the nearly constant spectral shape of an AGN as it brightens over the non-variable component of the host galaxy plus narrow lines, which is usually redder than AGN continuum emission.
A Counterexample to a Generalized Saari's Conjecture with a Continuum of Central Configurations
Manuele Santoprete
2009-09-27T23:59:59.000Z
In this paper we show that in the $n$-body problem with harmonic potential one can find a continuum of central configurations for $n=3$. Moreover we show a counterexample to an interpretation of Jerry Marsden Generalized Saari's conjecture. This will help to refine our understanding and formulation of the Generalized Saari's conjecture, and in turn it might provide insight in how to solve the classical Saari's conjecture for $n\\geq 4$.
A Counterexample to a Generalized Saari's Conjecture with a Continuum of Central Configurations
Santoprete, Manuele
2009-01-01T23:59:59.000Z
In this paper we show that in the $n$-body problem with harmonic potential one can find a continuum of central configurations for $n=3$. Moreover we show a counterexample to an interpretation of Jerry Marsden Generalized Saari's conjecture. This will help to refine our understanding and formulation of the Generalized Saari's conjecture, and in turn it might provide insight in how to solve the classical Saari's conjecture for $n\\geq 4$.
Entropy Production and Equilibrium Conditions in General-Covariant Continuum Physics
Wolfgang Muschik; Horst-Heino v. Borzeszkowski
2015-01-03T23:59:59.000Z
Starting out with an entropy identity, the entropy flux, the entropy production and the corresponding Gibbs and Gibbs-Duhem equations of general-covariant conti\\-nuum thermodynamics are established. Non-dissipative materials and equilibria are investigated. It is proved that equilibrium conditions only put on material properties cannot generate equilibria, rather additionally, the Killing property of the 4-temperature is a necessary condition for space-times in which equilibria are possible.
G. 't Hooft
2005-04-25T23:59:59.000Z
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.
Burton, Geoffrey R.
is typically a complex multi-phase material). In one-dimension models have been employed to investigate runaway through phase changes and temperature dependent parameters in Nylon ??. and a paper by Zeng for the heat and moisture transport with a phase change from solid to liquid [],[]. This simulation also
Paris-Sud XI, Université de
Hammamet, Tunisia 1 Models and methods for knowledge formalisation in a PLM context Alain BERNARDa an efficient PLM system. This strategic need mainly comes from the new relationship that subcontractors have for PLM integration. SMEs need specific PLM environments but the main difficulty is to succeed in defining
Continuum Mechanics and Thermodynamics vol. 24 pp. 505-513 (2012). H. Gouin A. Muracchini T. Ruggeri
Paris-Sud XI, Université de
2012-01-01T23:59:59.000Z
, are the specific body force and the heat supply; is the heat conductivity and the scalars and µ are the visco
Mechanics, mechanisms, and modeling of the chemical mechanical polishing process
Lai, Jiun-Yu
2001-01-01T23:59:59.000Z
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 ...
A unified gas-kinetic scheme for continuum and rarefied flows Kun Xu a,*, Juan-Chen Huang b
Xu, Kun
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
Gamma-Ray Burst Energy Spectra: Theoretical Models, Old and New
M. G. Baring
1995-07-17T23:59:59.000Z
The modelling of gamma-ray burst (GRB) spectra has considerable potential for increasing the understanding of these enigmatic sources. A diversity of ideas and analyses has been generated over the last two decades to explain line features and continuum shapes, encompassing both older galactic neutron star and ``new age'' cosmological source models. This paper reviews some of the highlights of these studies, discussing the merits and limitations of various ideas, and in particular their compatibility with the observational data. The first focus will be on continuum models for GRBs, which include optically thin synchrotron emission and resonant Compton upscattering near galactic neutron stars, while the synchrotron and non-magnetic inverse Compton scattering mechanisms are prominent in the less well-developed cosmological scenarios. Line formation scenarios will then be discussed, in particular the scattering model for producing cyclotron features, which remains the only viable explanation for the Ginga observations of double lines. Absorption-like line production in cosmological burst models is generally difficult, though interesting notions such as femtolensing interference patterns have been proffered.
A Force-Based Blending Model for Atomistic-to-Continuum Coupling
Bochev, Pavel
, 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
An Effective Continuum Model for the Gas Evolution in Internal Steam Drives
Tsimpanogiannis, Ioannis N.; Yortsos, Yanis C.
2002-06-11T23:59:59.000Z
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.
A triple-continuum pressure-transient model for a naturally fractured vuggy reservoir
2007-01-01T23:59:59.000Z
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-
Broader source: Energy.gov [DOE]
Presentation given by Lawrence Berkley National Laboratory at 2015 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about...
10.1098/rspa.2004.1282 A continuum anisotropic model
Feltham, Daniel
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
Paris-Sud XI, Université de
in geomechanics, petroleum engineering, and generally for geo-environmental problems. However, any complete
A triple-continuum pressure-transient model for a naturally fractured vuggy reservoir
2007-01-01T23:59:59.000Z
well test data from a fractured-vuggy reservoir in Westernwell test data from a fractured-vuggy reservoir in Westerndata for two wells from a naturally fractured vuggy oil reservoir,
Discontinuous Modelling of Crack Propagation in a Gradient-Enhanced Continuum
Simone, A; Wells, G N; Sluys, L J
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...
Continuum-scale Modeling of Hydrogen and Helium Bubble Growth in Metals |
Office of Environmental Management (EM)
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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742 33 111 1,613PortsmouthBartlesvilleAbout Â» Contact Us Contact Us
NREL: Continuum Magazine - Making a Computer Model of the Most Complex
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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Saleshttp://www.fnal.gov/directorate/nalcal/nalcal02_07_05_files/nalcal.gifNREL NRELChemicalIndustry Photo of aSystem Ever
Noncommutative Field Theory from Quantum Mechanical Space-Space Noncommutativity
Marcos Rosenbaum; J. David Vergara; L. Roman Juarez
2007-09-21T23:59:59.000Z
We investigate the incorporation of space noncommutativity into field theory by extending to the spectral continuum the minisuperspace action of the quantum mechanical harmonic oscillator propagator with an enlarged Heisenberg algebra. In addition to the usual $\\star$-product deformation of the algebra of field functions, we show that the parameter of noncommutativity can occur in noncommutative field theory even in the case of free fields without self-interacting potentials.
Rescigno, Thomas N.; Horner, Daniel A.; Yip, Frank L.; McCurdy,C. William
2005-08-29T23:59:59.000Z
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+.
Lee, Khee-Gan; Spergel, David N. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Suzuki, Nao, E-mail: lee@astro.princeton.edu [E.O. Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States)
2012-02-15T23:59:59.000Z
Continuum fitting is an important aspect of Ly{alpha} forest science, since errors in the derived optical depths scale with the fractional continuum error. However, traditional methods of estimating continua in noisy and moderate-resolution spectra (e.g., Sloan Digital Sky Survey, SDSS; S/N {approx}< 10 pixel{sup -1} and R {approx} 2000), such as power-law extrapolation or dividing by the mean spectrum, achieve no better than {approx}15% rms accuracy. To improve on this, we introduce mean-flux-regulated principal component analysis (MF-PCA) continuum fitting. In this technique, PCA fitting is carried out redward of the quasar Ly{alpha} line in order to provide a prediction for the shape of the Ly{alpha} forest continuum. The slope and amplitude of this continuum prediction is then corrected using external constraints for the Ly{alpha} forest mean flux. This requires prior knowledge of the mean flux, (F), but significantly improves the accuracy of the flux transmission, F {identical_to} exp (- {tau}), estimated from each pixel. From tests on mock spectra, we find that MF-PCA reduces the errors to 8% rms in S/N {approx} 2 spectra, and <5% rms in spectra with S/N {approx}> 5. The residual Fourier power in the continuum is decreased by a factor of a few in comparison with dividing by the mean continuum, enabling Ly{alpha} flux power spectrum measurements to be extended to {approx}2 Multiplication-Sign larger scales. Using this new technique, we make available continuum fits for 12,069 z > 2.3 Ly{alpha} forest spectra from SDSS Data Release 7 for use by the community. This technique is also applicable to future releases of the ongoing Baryon Oscillations Spectroscopic Survey, which obtains spectra for {approx}150, 000 Ly{alpha} forest spectra at low signal-to-noise (S/N {approx} 2).
DeMange, P; Marian, J; de Caro, M S; Caro, A
2009-03-16T23:59:59.000Z
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.
Walker, Larry P., Bergstrom, Gary; Corgie, Stephane; Craighead, Harold; Gibson, Donna; Wilson, David
2011-06-13T23:59:59.000Z
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.
PHYSICS CURRICULUM PH 101: Introductory Physics I -Mechanics, oscillations and waves (2:1)
Srinivasan, N.
:1) Temperature, The First Law of Thermodynamics, Kinetic Theory of Gases and Maxwell -Boltzmann Statistics, Heat and Charged Particles, Momentum and Angular Momentum, Two Body Central Force Problems, Collision Theory, Small Oscillations, Coupled Oscillators and Normal Modes, Continuum Mechanics of solids and fluids
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
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.
Borja, R I; White, J A
2010-02-19T23:59:59.000Z
We develop conservation laws for coupled hydro-mechanical processes in unsaturated porous media using three-phase continuum mixture theory. From the first law of thermodynamics, we identify energy-conjugate variables for constitutive modeling at macroscopic scale. Energy conjugate expressions identified relate a certain measure of effective stress to the deformation of the solid matrix, the degree of saturation to the matrix suction, the pressure in each constituent phase to the corresponding intrinsic volume change of this phase, and the seepage forces to the corresponding pressure gradients. We then develop strong and weak forms of boundary-value problems relevant for 3D finite element modeling of coupled hydro-mechanical processes in unsaturated porous media. The paper highlights a 3D numerical example illustrating the advances in the solution of large-scale coupled finite element systems, as well as the challenges in developing more predictive tools satisfying the basic conservation laws and the observed constitutive responses for unsaturated porous materials.
Kazuhiro Yokota; Nobuyuki Imoto
2014-07-04T23:59:59.000Z
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.
A Cluster of 1.3 cm Continuum Sources in OMC1 South
Luis A. Zapata; Luis F. Rodriguez; Stanley E. Kurtz; C. R. O'Dell; Paul T. P. Ho
2004-07-01T23:59:59.000Z
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_\
Development of a Mechanistic-Based Healing Model for Self-Healing Glass Seals
Xu, Wei; Stephens, Elizabeth V.; Sun, Xin; Khaleel, Mohammad A.; Zbib, Hussein M.
2012-10-01T23:59:59.000Z
Self-healing glass, a recent development of hermetic sealant materials, has the ability to effectively repair damage when heated to elevated temperatures; thus, able to extend its service life. Since crack healing morphological changes in the glass material are usually temperature and stress dependent, quantitative studies to determine the effects of thermo-mechanical conditions on the healing behavior of the self-healing glass sealants are extremely useful to accommodate the design and optimization of the sealing systems within SOFCs. The goal of this task is to develop a mechanistic-based healing model to quantify the stress and temperature dependent healing behavior. A two-step healing mechanism was developed and implemented into finite element (FE) models through user-subroutines. Integrated experimental/kinetic Monte Carlo (kMC) simulation methodology was taken to calibrate the model parameters. The crack healing model is able to investigate the effects of various thermo-mechanical factors; therefore, able to determine the critical conditions under which the healing mechanism will be activated. Furthermore, the predicted results can be used to formulate the continuum damage-healing model and to assist the SOFC stack level simulations in predicting and evaluating the effectiveness and the performance of various engineering seal designs.
ALMA Imaging of Millimeter/Submillimeter Continuum Emission in Orion KL
Hirota, Tomoya; Kurono, Yasutaka; Honma, Mareki
2015-01-01T23:59:59.000Z
We have carried out high resolution observations with Atacama Large Millimeter/Submillimeter Array (ALMA) of continuum emission from Orion KL region. We identify 11 compact sources at ALMA band 6 (245 GHz) and band 7 (339 GHz), including Hot Core, Compact Ridge, SMA1, IRc4, IRc7, and a radio source I (Source I). Spectral energy distribution (SED) of each source is determined by using previous 3 mm continuum emission data. Physical properties such as size, mass, hydrogen number density and column density are discussed based on the dust graybody SED. Among 11 identified sources, Source I, a massive protostar candidate, is a dominant energy source in Orion KL. We extensively investigate its SED from centimeter to submillimeter wavelengths. The SED of Source I can be fitted with a single power-law index of 1.97 suggesting an optically thick emission. We employ the H$^{-}$ free-free emission as an opacity source of this optically thick emission. The temperature, density, and mass of the circumstellar disk associat...
A Précis of Some Recent Developments in Computational Failure Mechanics
De Borst, R; Askes, Harm; Gutiérrez, Miguel A; Remmers, Joris J C; Wells, G N
2002-01-01T23:59:59.000Z
WCCM V Fifth World Congress on Computational Mechanics July 7-12, 2002, Vienna, Austria Eds.: H.A. Mang, F.G. Rammerstorfer, J. Eberhardsteiner A Pre´cis of Some Recent Developments in Computational Failure Mechanics Rene´ de Borst*, Harm Askes... transition from a (higher-order) continuum description to a genuine discontinuum in a numerical context. This is ex- tremely powerful, since now the entire failure process, from small-scale yielding or the initiation of voids and micro-cracks up...
A micro to macro approach to polymer matrix composites damage modeling : final LDRD report.
English, Shawn Allen; Brown, Arthur A.; Briggs, Timothy M.
2013-12-01T23:59:59.000Z
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.
Luo, Jian; Tomar, Vikas; Zhou, Naixie; Lee, Hongsuk
2013-06-30T23:59:59.000Z
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.
Mechanical & Industrial Engineering
Mountziaris, T. J.
on the PI's current research on energy harvesting nanowires, Li-ion batteries, and PEM fuel cells. In energy nanowires from both modeling and in-situ quantitative microscopy perspectives. In Li-ion battery work, we-ion intercalation into nanowires. The last, electro-mechanical characterization of degraded and fresh electrode
Residential Mechanical Precooling
German, A.; Hoeschele, M.
2014-12-01T23:59:59.000Z
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.
Rupture mechanism of liquid crystal thin films realized by large-scale molecular simulations
Nguyen, Trung D [ORNL] [ORNL; Carrillo, Jan-Michael Y [ORNL] [ORNL; Brown, W Michael [ORNL] [ORNL; Matheson, Michael A [ORNL] [ORNL
2014-01-01T23:59:59.000Z
The ability of liquid crystal (LC) molecules to respond to changes in their environment makes them an interesting candidate for thin film applications, particularly in bio-sensing, bio-mimicking devices, and optics. Yet the understanding of the (in)stability of this family of thin films has been limited by the inherent challenges encountered by experiment and continuum models. Using unprecedented largescale molecular dynamics (MD) simulations, we address the rupture origin of LC thin films wetting a solid substrate at length scales similar to those in experiment. Our simulations show the key signatures of spinodal instability in isotropic and nematic films on top of thermal nucleation, and importantly, for the first time, evidence of a common rupture mechanism independent of initial thickness and LC orientational ordering. We further demonstrate that the primary driving force for rupture is closely related to the tendency of the LC mesogens to recover their local environment in the bulk state. Our study not only provides new insights into the rupture mechanism of liquid crystal films, but also sets the stage for future investigations of thin film systems using peta-scale molecular dynamics simulations.
Strzalka, J.; Liu, J; Tronin, A; Churbanova, I; Johansson, J; Blasie, J
2009-01-01T23:59:59.000Z
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.
Energy Saving Homes and Buildings, Continuum Magazine, Spring 2014 / Issue 6 (Book)
Not Available
2014-03-01T23:59:59.000Z
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.
Hougen, J.T. [NIST, Gaithersburg, MD (United States)
1993-12-01T23:59:59.000Z
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.
More on the continuum limit of gauge-fixed compact U(1) lattice gauge theory
Asit K. De; Tilak Sinha
2005-06-30T23:59:59.000Z
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.
Bridging a gap between continuum-QCD and ab initio predictions of hadron observables
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Binosi, Daniele; Chang, Lei; Papavassiliou, Joannis; Roberts, Craig D.
2015-03-01T23:59:59.000Z
Within contemporary hadron physics there are two common methods for determining the momentum- dependence of the interaction between quarks: the top-down approach, which works toward an ab initio computation of the interaction via direct analysis of the gauge-sector gap equations; and the bottom-up scheme, which aims to infer the interaction by fitting data within a well-defined truncation of those equations in the matter sector that are relevant to bound-state properties. We unite these two approaches by demonstrating that the renormalisation-group-invariant running-interaction predicted by contemporary analyses of QCD’s gauge sector coincides with that required in order to describe ground-state hadron observablesmore »using a nonperturbative truncation of QCD’s Dyson–Schwinger equations in the matter sector. This bridges a gap that had lain between nonperturbative continuum-QCD and the ab initio prediction of bound-state properties.« less
Zhigilei, Leonid V.
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
Radio-Continuum Emission From The Young Galactic Supernova Remnant G1.9+0.3
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
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.
Ha, Taekjip
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
Not Available
2011-08-01T23:59:59.000Z
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.
Oldenburg, Amy
-numerical-aperture fiber continuum generation source for optical coherence tomography Daniel L. Marks, Amy L. Oldenburg and a practical enhancement to a fiber-optic optical coherence tomography system. © 2002 Op- tical Society custom-made optical components or specialized fibers that are not mass produced or readily available
On the continuum radio-spectrum of Cas A: possible evidence of the non-linear particle acceleration
Oni?, D
2015-01-01T23:59:59.000Z
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).
The detection of non-thermal radio continuum spokes and the study of star formation in the Cartwheel
Y. D. Mayya; D. Bizyaev; R. Romano; J. A. Garcia-Barreto; E. I. Vorobyov
2005-01-14T23:59:59.000Z
New sensitive Very Large Array 20 cm continuum observations of the Cartwheel, the prototypical collisional ring galaxy, were carried out with the principal aim of tracing supernova remnants that are expected to lie in the wake of the expanding ring and in the ring itself. We detect predominantly non-thermal radio continuum emission from regions associated with 13 ring HII complexes. The emission interior to the ring is confined to structures that resemble spokes of the wheel. The spokes start near bright HII complexes, and extend to around 6 arcsec (4 kpc) inward in the direction of the geometrical center of the ring. There is no apparent positional coincidence between the radio continuum and optical spokes. Radial distribution of intensity along the spokes suggests that the past star formation rate (SFR) in the Cartwheel was much lower than the current SFR. New Halpha observations were used to revise the current SFR in the Cartwheel. The revised value is 18 Msun/yr, which is a factor of 4 lower than the value reported previously, but is in good agreement with the SFR estimated from far infrared luminosity. About 30% of the observed 20 cm continuum non-thermal emission seems to originate in processes that are not related to star formation. Revised SFR in the Cartwheel is comparable to that in the rest of the ring galaxies.
Millan-Gabet, R; Touhami, Y; Gies, D; Hesselbach, E; Pedretti, E; Thureau, N; Zhao, M; Brummelaar, T ten
2010-01-01T23:59:59.000Z
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...
Statistical mechanics of gene competition
Venegas-Ortiz, Juan; Ortiz, Juan Venegas
2013-11-28T23:59:59.000Z
Statistical mechanics has been applied to a wide range of systems in physics, biology, medicine and even anthropology. This theory has been recently used to model the complex biochemical processes of gene expression and ...
Production of excitons in grazing collisions of protons with LiF surfaces: An onion model
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
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.
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
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.
DAMAGE MODELING OF INJECTION-MOLDED SHORT- AND LONG-FIBER THERMOPLASTICS
Nguyen, Ba Nghiep; Kunc, Vlastimil; Bapanapalli, Satish K.; Phelps, Jay; Tucker III, Charles L.
2009-10-30T23:59:59.000Z
This article applies the recent anisotropic rotary diffusion – reduced strain closure (ARD-RSC) model for predicting fiber orientation and a new damage model for injection-molded long-fiber thermoplastics (LFTs) to analyze progressive damage leading to total failure of injection-molded long-glass-fiber/polypropylene (PP) specimens. The ARD-RSC model was implemented in a research version of the Autodesk Moldflow Plastics Insight (MPI) processing code, and it has been used to simulate injection-molding of a long-glass-fiber/PP plaque. The damage model combines micromechanical modeling with a continuum damage mechanics description to predict the nonlinear behavior due to plasticity coupled with damage in LFTs. This model has been implemented in the ABAQUS finite element code via user-subroutines and has been used in the damage analyses of tensile specimens removed from the injection-molded long-glass-fiber/PP plaques. Experimental characterization and mechanical testing were performed to provide input data to support and validate both process modeling and damage analyses. The predictions are in agreement with the experimental results.
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...
Eulerian hydrocode modeling of a dynamic tensile extrusion experiment (u)
Burkett, Michael W [Los Alamos National Laboratory; Clancy, Sean P [Los Alamos National Laboratory
2009-01-01T23:59:59.000Z
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.