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
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 ...
Thellamurege, Nandun M.; Si, Dejun; Cui, Fengchao; Li, Hui, E-mail: hli4@unl.edu [Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (United States)] [Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (United States)
2014-05-07T23:59:59.000Z
A combined quantum mechanical/molecular mechanical/continuum (QM/MM/C) style second order Møller-Plesset perturbation theory (MP2) method that incorporates induced dipole polarizable force field and induced surface charge continuum solvation model is established. The Z-vector method is modified to include induced dipoles and induced surface charges to determine the MP2 response density matrix, which can be used to evaluate MP2 properties. In particular, analytic nuclear gradient is derived and implemented for this method. Using the Assisted Model Building with Energy Refinement induced dipole polarizable protein force field, the QM/MM/C style MP2 method is used to study the hydrogen bonding distances and strengths of the photoactive yellow protein chromopore in the wild type and the Glu46Gln mutant.
Continuum Mechanics Unit code: MATH45061
Sidorov, Nikita
MATH45061 Continuum Mechanics Unit code: MATH45061 Credit Rating: 15 Unit level: Level 4 Teaching concerns the formulation and solution of problems in continuum mechanics (solid and fluid mechanics) from equations. Overview This unit describes the fundamental theory of continuum mechanics in a unified
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.
California at Santa Cruz, University of
243 Â§2.4 CONTINUUM MECHANICS (SOLIDS) In this introduction to continuum mechanics we consider to simplify the constitutive equations for elasticity. We begin our study of continuum mechanics
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...
A CONTINUUM MECHANICS PRIMER On Constitutive Theories of Materials
Liu, I-Shih
A CONTINUUM MECHANICS PRIMER On Constitutive Theories of Materials I-SHIH LIU Rio de Janeiro #12 of basic equations of material bodies. Particular emphases are placed on general physical requirements, which have to be satisfied by constitutive equations of material models. After introduction
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.
Continuum-based Multiscale Computational Damage Modeling of Cementitous Composites
Kim, Sun-Myung
2011-08-08T23:59:59.000Z
of Advisory Committee: Dr. Rashid K. Abu Al-Rub Based on continuum damage mechanics (CDM), an isotropic and anisotropic damage model coupled with a novel plasticity model for plain concrete is proposed in this research. Two different damage evolution laws... in the commercial finite element analysis program Abaqus, and the overall performance of the proposed model is verified by comparing the model predictions to various experimental data on macroscopic level. Using the proposed coupled plasticity...
Antieigenvalue Analysis, New Applications: Continuum Mechanics, Economics, Number Theory
Karl Gustafson
2015-04-20T23:59:59.000Z
My recent book Antieigenvalue Analysis, World-Scientific, 2012, presented the theory of antieigenvalues from its inception in 1966 up to 2010, and its applications within those forty-five years to Numerical Analysis, Wavelets, Statistics, Quantum Mechanics, Finance, and Optimization. Here I am able to offer three further areas of application: Continuum Mechanics, Economics, and Number Theory.
Fractional Calculus for Continuum Mechanics - anisotropic non-locality
Wojciech Sumelka
2015-02-06T23:59:59.000Z
In this paper the generalisation of previous author's formulation of fractional continuum mechanics to the case of anisotropic non-locality is presented. The considerations include the review of competitive formulations available in literature. The overall concept bases on the fractional deformation gradient which is non-local, as a consequence of fractional derivative definition. The main advantage of the proposed formulation is its analogical structure to the general framework of classical continuum mechanics. In this sense, it allows, to give similar physical and geometrical meaning of introduced objects.
BE 419 Principles of Continuum Mechanics and Dimitrije Stamenovi
Vajda, Sandor
, stress). Balance of energy (power theorem, 1st and 2nd laws of thermodynamics) 4. Constitutive equations: 1. Roberts, A. J. A One-Dimensional Introduction to Continuum Mechanics, World Scientific, Singapore of diffusion equation). Application: Slime mold aggregation. Balance of momentum (body forces, tractions
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...
Atomistic to continuum modeling of solidification microstructures
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Karma, Alain; Tourret, Damien
2015-09-26T23:59:59.000Z
We summarize recent advances in modeling of solidification microstructures using computational methods that bridge atomistic to continuum scales. We first discuss progress in atomistic modeling of equilibrium and non-equilibrium solid–liquid interface properties influencing microstructure formation, as well as interface coalescence phenomena influencing the late stages of solidification. The latter is relevant in the context of hot tearing reviewed in the article by M. Rappaz in this issue. We then discuss progress to model microstructures on a continuum scale using phase-field methods. We focus on selected examples in which modeling of 3D cellular and dendritic microstructures has been directly linked tomore »experimental observations. Finally, we discuss a recently introduced coarse-grained dendritic needle network approach to simulate the formation of well-developed dendritic microstructures. The approach reliably bridges the well-separated scales traditionally simulated by phase-field and grain structure models, hence opening new avenues for quantitative modeling of complex intra- and inter-grain dynamical interactions on a grain scale.« less
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.
Modeling dislocation density evolution in continuum crystal plasticity
Arsenlis, Athanasios, 1975-
2001-01-01T23:59:59.000Z
Dislocations are the singly most important material defects in crystal plasticity, and although dislocation mechanics has long been understood as the underlying physical basis for continuum crystal plasticity formulations, ...
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
DISCRETE-CONTINUUM MODELING OF METAL MATRIX COMPOSITES PLASTICITY
Devincre, Benoit
. For this reason, the pre- diction of the plastic properties of Metal Matrix Composites (MMCs) is some- times for plastic properties. On the one hand, the FE code treats the boundary value problem and cares of the conDISCRETE-CONTINUUM MODELING OF METAL MATRIX COMPOSITES PLASTICITY S. Groh1, B. Devincre1, F. Feyel2
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
deformation of Asphalt Concrete (AC) at high temperatures. These phenomena include strain rate dependency, confining pressure dependency, dilation, aggregate friction, anisotropy, and damage. The model is based on Perzyna's theory of viscoplasticity...
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.
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.
Keralavarma, Shyam Mohan
2012-02-14T23:59:59.000Z
. The main contributions from this research are: (i) development of a fully anisotropic continuum model of void growth for use in ductile fracture simulations and (ii) enhancing the capabilities of an existing two-dimensional DD framework for large scale...
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.
High-order continuum kinetic method for modeling plasma dynamics in phase space
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Vogman, G. V.; Colella, P.; Shumlak, U.
2014-12-15T23:59:59.000Z
Continuum methods offer a high-fidelity means of simulating plasma kinetics. While computationally intensive, these methods are advantageous because they can be cast in conservation-law form, are not susceptible to noise, and can be implemented using high-order numerical methods. Advances in continuum method capabilities for modeling kinetic phenomena in plasmas require the development of validation tools in higher dimensional phase space and an ability to handle non-cartesian geometries. To that end, a new benchmark for validating Vlasov-Poisson simulations in 3D (x,vx,vy) is presented. The benchmark is based on the Dory-Guest-Harris instability and is successfully used to validate a continuum finite volumemore »algorithm. To address challenges associated with non-cartesian geometries, unique features of cylindrical phase space coordinates are described. Preliminary results of continuum kinetic simulations in 4D (r,z,vr,vz) phase space are presented.« less
Sparks, Donald L.
GEOC 36 Kinetics and mechanisms of metal sorption at the soil mineral/water interface: The continuum from adsorption to precipitation Donald L. Sparks, Plant and Soil Sciences Department, Plant and Soil Sciences Department, University of Delaware, 531 S. College Avenue, Townsend Hall, Room 153
Continuum limits of step ow models 1 Introduction
2015-08-29T23:59:59.000Z
attachment and detachment mechanisms at the steps, we have obtained a Hamilton-Jacobi equation. for the surface height which is coupled with a di usion
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
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
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.
SUBMILLIMETRE CONTINUUM EMISSION FROM CLASS 0 SOURCES: THEORY, OBSERVATIONS, AND MODELLING
Froebrich, Dirk
) and temperature (T bol ), and age) of Class 0 sources. Speci#12;cally, we combine the information from the dust1 SUBMILLIMETRE CONTINUUM EMISSION FROM CLASS 0 SOURCES: THEORY, OBSERVATIONS, AND MODELLING M Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany 2 Institute for Astronomy, 640 N. A'ohoku Place, Hilo, HI
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
A continuum model of melt pond evolution on Arctic sea ice Daniela Flocco1
Feltham, Daniel
A continuum model of melt pond evolution on Arctic sea ice Daniela Flocco1 and Daniel L. Feltham1 to generate meltwater that accumulates in ponds. The melt ponds reduce the albedo of the sea ice cover during), which simulates the formation and evolution of the melt pond cover. In order to be compatible
California at Santa Cruz, University of
282 Â§2.5 CONTINUUM MECHANICS (FLUIDS) Let us consider a fluid medium and use Cartesian tensors to derive the mathematical equations that describe how a fluid behaves. A fluid continuum, like a solid , i = 1, 2, 3 is a velocity field, # is the density of the fluid, # ij is the stress tensor and b j
California at Santa Cruz, University of
282 Â§2.5 CONTINUUM MECHANICS (FLUIDS) Let us consider a fluid medium and use Cartesian tensors to derive the mathematical equations that describe how a fluid behaves. A fluid continuum, like a solid, is the density of the fluid, ij is the stress tensor and bj is an external force per unit mass. In the cgs system
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 ...
THEACCURACY OF NUMERICAL MODELS FOR CONTINUUM STANLY STEINBERG
Steinberg, Stanly
Water Rain Evaporation Figure 1.1. A Lake These notes are directed towards students who have some modest of water in the lake. Water can enter and leave the lake by various means: rain; evaporation; rivers and how much error is there is solving the mathematical model. #12; 2 Lake Ground Ground Water Ground
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.
Equivalent Continuum Modeling for Shock Wave Propagation in Jointed Media
Office of Scientific and Technical Information (OSTI)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:5 TablesExports to3,1,50022,3,,0,,6,1,SeparationConnect Journal Article: Discrete phase(Technical Report) |Model (JournalConnect(Technical
Equivalent Continuum Modeling for Shock Wave Propagation in Jointed Media
Office of Scientific and Technical Information (OSTI)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:5 TablesExports to3,1,50022,3,,0,,6,1,SeparationConnect Journal Article: Discrete phase(Technical Report) |Model
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-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.
Sheng, Nuo, 1977-
2006-01-01T23:59:59.000Z
Polymer/clay nanocomposites have been observed to exhibit enhanced thermal/mechanical properties at low weight fractions (We) of clay. Continuum-based composite modeling reveals that the enhanced properties are strongly ...
Electric and magnetic response to the continuum for A=7 isobars in a dicluster model
A. Mason; R. Chatterjee; L. Fortunato; A. Vitturi
2008-11-11T23:59:59.000Z
Mirror isobars $^7$Li and $^7$Be are investigated in a dicluster model. The magnetic dipole moments and the magnetic dipole response to the continuum are calculated in this framework. The magnetic contribution is found to be small with respect to electric dipole and quadrupole excitations even at astrophysical energies, at a variance with the case of deuteron. Energy weighted molecular sum rules are evaluated and a formula for the molecular magnetic dipole sum rule is found which matches the numerical calculations. Cross-sections for photo-dissociation and radiative capture as well as the S-factor for reactions of astrophysical significance are calculated with good agreement with known experimental data.
Geometrical Field Representation of Solid, Fluid, and Gas as Continuum in Rational Mechanics
Jianhua Xiao
2009-11-07T23:59:59.000Z
Based on the points-set transformation concept about the motion transformation in continuum, the macro classical strain is expressed by the additive addition of the intrinsic stretching of material element and its intrinsic local rotation. For zero classical strain (no macro deformation observed on its configuration surface, suitable container is required for liquid and gas to make up macro invariant configuration), the results show that: (1) For solid, the local rotation angular is zero. The material element has no intrinsic stretching. (2) For liquid, the local rotation will not change the basic gauge tensor. The material element has intrinsic plane stretching on the rotation plane. (3) For gas state, the intrinsic local rotation will amplify the basic gauge tensor. The material element has intrinsic stretching along the rotation direction. Hence, under the condition of no macro classical strain be observed, the material element has three different physical states: solid (no intrinsic stretching), fluid (plane intrinsic stretching), and gas (directional intrinsic stretching). Furthermore, for the three states, the free conditions are defined by zero intrinsic stretching. Referring to this free condition, the constitutive equations for the materials at multiple states are established.
Christo I. Christov
2011-03-06T23:59:59.000Z
We show that the linearized equations of the incompressible elastic medium admit a `Maxwell form' in which the shear component of the stress vector plays the role of the electric field, and the vorticity plays the role of the magnetic field. Conversely, the set of dynamic Maxwell equations are strict mathematical corollaries from the governing equations of the incompressible elastic medium. This suggests that the nature of `electromagnetic field' may actually be related to an elastic continuous medium. The analogy is complete if the medium is assumed to behave as fluid in shear motions, while it may still behave as elastic solid under compressional motions. Then the governing equations of the elastic fluid are re-derived in the Eulerian frame by replacing the partial time derivatives by the properly invariant (frame indifferent) time rates. The `Maxwell from' of the frame indifferent formulation gives the frame indifferent system that is to replace the Maxwell system. This new system comprises terms already present in the classical Maxwell equations, alongside terms that are the progenitors of the Biot--Savart, Oersted--Ampere's, and Lorentz--force laws. Thus a frame indifferent (truly covariant) formulation of electromagnetism is achieved from a single postulate that the electromagnetic field is a kind of elastic (partly liquid partly solid) continuum.
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.
Continuum Mechanics and Thermodynamics manuscript No. (will be inserted by the editor)
Monneau, Régis
dynamics: from microscopic models to macroscopic crystal plasticity A. El Hajj1 , H. Ibrahim1,2 , R to dislocations. Our study ranges from atomic models to macroscopic crystal plasticity. At each scale of the threedimensional space. We consider a perfect crystal Z3 where each position with integer coordinates is occupied
M. V. Voinova; M. Rodahl; M. Jonson; B. Kasemo
1998-05-21T23:59:59.000Z
We have derived the general solution of a wave equation describing the dynamics of two-layere viscoelastic polymer materials of arbitrary thickness deposited on solid (quartz) surfaces in a fluid environment. Within the Voight model of viscoelastic element, we calculate the acoustic response of the system to an applied shear stress, i.e. we find the shift of the quartz generator resonance frequency and of the dissipation factor, and show that it strongly depends on the viscous loading of the adsorbed layers and on the shear storage and loss moduli of the overlayers. These results can readily be applied to quartz crystal acoustical measurements of the viscoelasticity of polymers, which conserve their shape under the shear deformations and do not flow, and layered structures such as protein films adsorbed from solution onto the surface of self-assembled monolayres.
Components for Atomistic-to-Continuum Multiscale Modeling of Flow in Micro- and Nanofluidic Systems
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Adalsteinsson, Helgi; Debusschere, Bert J.; Long, Kevin R.; Najm, Habib N.
2008-01-01T23:59:59.000Z
Micro- and nanofluidics pose a series of significant challenges for science-based modeling. Key among those are the wide separation of length- and timescales between interface phenomena and bulk flow and the spatially heterogeneous solution properties near solid-liquid interfaces. It is not uncommon for characteristic scales in these systems to span nine orders of magnitude from the atomic motions in particle dynamics up to evolution of mass transport at the macroscale level, making explicit particle models intractable for all but the simplest systems. Recently, atomistic-to-continuum (A2C) multiscale simulations have gained a lot of interest as an approach to rigorously handle particle-levelmore »dynamics while also tracking evolution of large-scale macroscale behavior. While these methods are clearly not applicable to all classes of simulations, they are finding traction in systems in which tight-binding, and physically important, dynamics at system interfaces have complex effects on the slower-evolving large-scale evolution of the surrounding medium. These conditions allow decomposition of the simulation into discrete domains, either spatially or temporally. In this paper, we describe how features of domain decomposed simulation systems can be harnessed to yield flexible and efficient software for multiscale simulations of electric field-driven micro- and nanofluidics.« less
Fracture phenomena have been extensively studied in the last several decades, and continuum-known issue of this approach is the stress singularity at the crack tip/front. Another known issue of fracture) and Peridynamics, have certain advantages while modeling various fracture problems of solids due to their intrinsic
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.
Herbert, John
Symmetric versus asymmetric discretization of the integral equations in polarizable continuum form 28 April 2011 Available online 1 May 2011 a b s t r a c t Discretization of the integral equations of the integral operators. Consequently, the appropriate form of the finite-dimensional matrix equations
Narasimhan, C.S.L.; Verma, R.P. [Indian Oil Corporation Ltd., Faridabad (India)
1995-12-31T23:59:59.000Z
Modeling of hydrocracking kinetics capturing the chemistry of the process has been a continuous endeavor for the researchers. Very few approaches have been formulated so far, which either over simplify the problem or require large number of computation parameters for acceptable solution. The present paper proposes a novel and elegant approach based on continuum theory of lumping, which attempts to follow the process chemistry closely to model the complex hydrocracking kinetics for prediction of paraffins, naphthenes and aromatics (PNAs) in the product mixture. The model predictions match well with reported experimental results.
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...
Noise-induced multistability in chemical systems: Discrete vs Continuum modeling
Andrew Duncan; Shuohao Liao; Tomas Vejchodsky; Radek Erban; Ramon Grima
2014-07-31T23:59:59.000Z
The noisy dynamics of chemical systems is commonly studied using either the chemical master equation (CME) or the chemical Fokker-Planck equation (CFPE). The latter is a continuum approximation of the discrete CME approach. We here show that the CFPE may fail to capture the CME's prediction of noise-induced multistability. In particular we find a simple chemical system for which the CME's marginal probability distribution changes from unimodal to multimodal as the system-size decreases below a critical value, while the CFPE's marginal probability distribution is unimodal for all physically meaningful system sizes.
Goddard, J. D.
2010-01-01T23:59:59.000Z
with critical-state soil mechanics, at pressures com-with critical-state soil mechanics would no doubt require a
MECHANICAL MODELS FOR INTERSEISMIC DEFORMATION IN
Kanda, Ravi
MECHANICAL MODELS FOR INTERSEISMIC DEFORMATION IN SUBDUCTION ZONES Thesis by Ravi V. S. Kanda that mechanical coupling on such asperities alone is sufficient to explain currently available geodetic
Masaki Asano; Torsten Bringmann; Gunter Sigl; Martin Vollmann
2013-05-16T23:59:59.000Z
An analysis of the Fermi gamma ray space telescope data has recently revealed a resolved gamma-ray feature close to the galactic center which is consistent with monochromatic photons at an energy of about 130 GeV. If interpreted in terms of dark matter (DM) annihilating into \\gamma\\gamma (\\gamma Z, \\gamma h), this would correspond to a DM particle mass of roughly 130 GeV (145 GeV, 155 GeV). The rate for these loop-suppressed processes, however, is larger than typically expected for thermally produced DM. Correspondingly, one would generically expect even larger tree level production rates of standard model fermions or gauge bosons. Here, we quantify this expectation in a rather model-independent way by relating the tree level and loop amplitudes with the help of the optical theorem. As an application, we consider bounds from continuum gamma rays, radio and antiproton data on the tree level amplitudes and translate them into constraints on the loop amplitudes. We find that, independently of the DM production mechanism, any DM model aiming at explaining the line signal in terms of charged standard model particles running in the loop is in rather strong tension with at least one of these constraints, with the exception of loops dominated by top quarks. We stress that attempts to explain the 130 GeV feature with internal bremsstrahlung do not suffer from such difficulties.
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.
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
Continuum electromechanical modeling of protein-membrane interactions Y. C. Zhou*
Lu, Benzhuo
of Scientific/Engineering Computing, Institute of Computational Mathematics and Scientific/Engineering Computing systems. II. MATHEMATICAL MODEL AND NUMERICAL TECHNIQUES The essential idea und of Mathematics, Colorado State University, Fort Collins, Colorado 80523, USA Benzhuo Lu State Key Laboratory
A predictive, size-dependent continuum model for dense granular flows
Henann, David Lee
Dense granular materials display a complicated set of flow properties, which differentiate them from ordinary fluids. Despite their ubiquity, no model has been developed that captures or predicts the complexities of granular ...
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.
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
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
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.
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.
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.
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
Mechanics of Materials and Structures
Vaziri, Ashkan
AND NUCLEAR MECHANICS Ashkan Vaziri, Arvind Gopinath and Vikram S. Deshpande Volume 2, Nº 6 June 2007 CONTINUUM-BASED COMPUTATIONAL MODELS FOR CELL AND NUCLEAR MECHANICS ASHKAN VAZIRI, ARVIND GOPINATH, nuclear mechanics, computational mechanics. This work has been supported by the Division of Engineering
Classical Coordination Mechanisms in the Chemical Model
Fradet, Pascal
great souvenir! Abstract Originally, the chemical model of computation has been proposed as a sim- pleClassical Coordination Mechanisms in the Chemical Model J.-P. Ban^atre P. Fradet Y. Radenac-Pierre Ban^atre) had with Gilles on topics related with programming in general and chemical programming
Modeling the mechanical response of PBX 9501
Ragaswamy, Partha [Los Alamos National Laboratory; Lewis, Matthew W [Los Alamos National Laboratory; Liu, Cheng [Los Alamos National Laboratory; Thompson, Darla G [Los Alamos National Laboratory
2010-01-01T23:59:59.000Z
An engineering overview of the mechanical response of Plastic-Bonded eXplosives (PBXs), specifically PBX 9501, will be provided with emphasis on observed mechanisms associated with different types of mechanical testing. Mechanical tests in the form of uniaxial tension, compression, cyclic loading, creep (compression and tension), and Hopkinson bar show strain rate and temperature dependence. A range of mechanical behavior is observed which includes small strain recoverable response in the form of viscoelasticity; change in stiffness and softening beyond peak strength due to damage in the form microcracks, debonding, void formation and the growth of existing voids; inelastic response in the form of irrecoverable strain as shown in cyclic tests, and viscoelastic creep combined with plastic response as demonstrated in creep and recovery tests. The main focus of this paper is to elucidate the challenges and issues involved in modeling the mechanical behavior of PBXs for simulating thermo-mechanical responses in engineering components. Examples of validation of a constitutive material model based on a few of the observed mechanisms will be demonstrated against three point bending, split Hopkinson pressure bar and Brazilian disk geometry.
STATISTICAL MECHANICS MODELING OF MESOSCALE DEFORMATION IN METALS...
Office of Scientific and Technical Information (OSTI)
Technical Report: STATISTICAL MECHANICS MODELING OF MESOSCALE DEFORMATION IN METALS Citation Details In-Document Search Title: STATISTICAL MECHANICS MODELING OF MESOSCALE...
Coupled Kinetic, Thermal, and Mechanical Modeling of FIB Micro...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Coupled Kinetic, Thermal, and Mechanical Modeling of FIB Micro-machined Electrodes Coupled Kinetic, Thermal, and Mechanical Modeling of FIB Micro-machined Electrodes 2010 DOE...
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...
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.
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 Model for Relativistic Blast Waves
A. M. Beloborodov; Z. L. Uhm
2006-09-02T23:59:59.000Z
Relativistic blast waves can be described by a mechanical model. In this model, the "blast" -- the compressed gas between the forward and reverse shocks -- is viewed as one hot body. Equations governing its dynamics are derived from conservation of mass, energy, and momentum. Simple analytical solutions are obtained in the two limiting cases of ultra-relativistic and non-relativistic reverse shock. Equations are derived for the general explosion problem.
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
Mechanisms and Geochemical Models of Core Formation
Rubie, David C
2015-01-01T23:59:59.000Z
The formation of the Earth's core is a consequence of planetary accretion and processes in the Earth's interior. The mechanical process of planetary differentiation is likely to occur in large, if not global, magma oceans created by the collisions of planetary embryos. Metal-silicate segregation in magma oceans occurs rapidly and efficiently unlike grain scale percolation according to laboratory experiments and calculations. Geochemical models of the core formation process as planetary accretion proceeds are becoming increasingly realistic. Single stage and continuous core formation models have evolved into multi-stage models that are couple to the output of dynamical models of the giant impact phase of planet formation. The models that are most successful in matching the chemical composition of the Earth's mantle, based on experimentally-derived element partition coefficients, show that the temperature and pressure of metal-silicate equilibration must increase as a function of time and mass accreted and so m...
Thermal, chemical, and mechanical cookoff modeling
Hobbs, M.L.; Baer, M.R.; Gross, R.J.
1994-08-01T23:59:59.000Z
A Thermally Reactive, Elastic-plastic eXplosive code, TREX, has been developed to analyze coupled thermal, chemical and mechanical effects associated with cookoff simulation of confined or unconfined energetic materials. In confined systems, pressure buildup precedes thermal runaway, and unconfined energetic material expands to relieve high stress. The model was developed based on nucleation, decomposition chemistry, and elastic/plastic mechanical behavior of a material with a distribution of internal defects represented as clusters of spherical inclusions. A local force balance, with mass continuity constraints, forms the basis of the model requiring input of temperature and reacted gas fraction. This constitutive material model has been incorporated into a quasistatic mechanics code SANTOS as a material module which predicts stress history associated with a given strain history. The thermal-chemical solver XCHEM has been coupled to SANTOS to provide temperature and reacted gas fraction. Predicted spatial history variables include temperature, chemical species, solid/gas pressure, solid/gas density, local yield stress, and gas volume fraction. One-Dimensional Time to explosion (ODTX) experiments for TATB and PBX 9404 (HMX and NC) are simulated using global multistep kinetic mechanisms and the reactive elastic-plastic constitutive model. Pressure explosions, rather than thermal runaway, result in modeling slow cookoff experiments of confined conventional energetic materials such as TATB. For PBX 9404, pressure explosions also occur at fast cookoff conditions because of low temperature reactions of nitrocellulose resulting in substantial pressurization. A demonstrative calculation is also presented for reactive heat flow in a hollow, propellant-filled, stainless steel cylinder, representing a rocket motor. This example simulation show
A mechanical model of the smartphone's accelerometer
Gallitto, Aurelio Agliolo
2015-01-01T23:59:59.000Z
To increase the attention of students, several physics experiments can be performed at school, as well at home, by using the smartphone as laboratory tools. In the paper we describe a mechanical model of the smartphone's accelerometer, which can be used in classroom to allow students to better understand the principle of the accelerometer even by students at the beginning of the study in physics.
Fifth World Congress on Computational Mechanics
Christakis, Nikolaos
WCCM V Fifth World Congress on Computational Mechanics July 7-12, 2002, Vienna, Austria Eds.: H Material in a Computational Fluid Dynamics Framework using Micro- Mechanical Models Nicholas Christakis London, UK e-mail: I.Bridle@gre.ac.uk Key words: granular material, continuum mechanics, micro-mechanical
Quantum-Mechanical Model of Spacetime
Jarmo Makela
2007-06-20T23:59:59.000Z
We consider a possibility to construct a quantum-mechanical model of spacetime, where Planck size quantum black holes act as the fundamental constituents of space and time. Spacetime is assumed to be a graph, where black holes lie on the vertices. Our model implies that area has a discrete spectrum with equal spacing. At macroscopic length scales our model reproduces Einstein's field equation with a vanishing cosmological constant as a sort of thermodynamical equation of state of spacetime and matter fields. In the low temperature limit, where most black holes are assumed to be in the ground state, our model implies the Unruh and the Hawking effects, whereas in the high temperature limit we find, among other things, that black hole entropy depends logarithmically on the event horizon area, instead of being proportional to the area.
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.
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).
Moloney, Joshua [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309 (United States); Michael Shull, J., E-mail: joshua.moloney@colorado.edu, E-mail: michael.shull@colorado.edu [Also at Institute of Astronomy, University of Cambridge, Cambridge CB3 0HA, UK. (United Kingdom)
2014-10-01T23:59:59.000Z
Understanding the composition and structure of the broad-line region (BLR) of active galactic nuclei (AGNs) is important for answering many outstanding questions in supermassive black hole evolution, galaxy evolution, and ionization of the intergalactic medium. We used single-epoch UV spectra from the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope to measure EUV emission-line fluxes from four individual AGNs with 0.49 ? z ? 0.64, two AGNs with 0.32 ? z ? 0.40, and a composite of 159 AGNs. With the CLOUDY photoionization code, we calculated emission-line fluxes from BLR clouds with a range of density, hydrogen ionizing flux, and incident continuum spectral indices. The photoionization grids were fit to the observations using single-component and locally optimally emitting cloud (LOC) models. The LOC models provide good fits to the measured fluxes, while the single-component models do not. The UV spectral indices preferred by our LOC models are consistent with those measured from COS spectra. EUV emission lines such as N IV ?765, O II ?833, and O III ?834 originate primarily from gas with electron temperatures between 37,000 K and 55,000 K. This gas is found in BLR clouds with high hydrogen densities (n {sub H} ? 10{sup 12} cm{sup –3}) and hydrogen ionizing photon fluxes (?{sub H} ? 10{sup 22} cm{sup –2} s{sup –1}).
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, ...
Bordenave, Charles
Thesis proposal CSF Brazil 2014 Title: Modeling of water transfer and suspended sediments is to modeling water and sediment transport at the Amazon catchment scale. Investigations will consist storage and sediment deposition on scenario in a context of global changes. Subject description: spended
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.
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.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Gu, L.; Pallardy, S. G.; Hosman, K. P.; Sun, Y.
2015-01-19T23:59:59.000Z
Using decade-long continuous observations of tree mortality and predawn leaf water potential (?pd) at the Missouri Ozark AmeriFlux (MOFLUX) site, we studied how the mortality of important tree species varied along the isohydric to anisohydric continuum and how such variations may be predicted. Water stress determined inter-annual variations in tree mortality with a time delay of one year or more, which was predicted by predawn leaf water potential integral (PLWPI), mean effective precipitation interval (a time period with no daily precipitation rates exceeding a threshold) with a daily threshold precipitation at 5 mm day-1 (MEPI5), and precipitation variability index (PVI).more »Positive temperature anomaly integral (PTAI) and vapor pressure deficit integral (VPDI) also worked reasonably well, particularly for moderate droughts. The extreme drought of the year 2012 drastically increased the mortality of all species in the subsequent year. Regardless of the degree of isohydry and drought intensity, the ?pd of all species recovered rapidly after sufficiently intense rain events. This, together with a lack of immediate leaf and branch desiccation, suggests that hydraulic disconnection in the xylem was absent even during extreme drought and tree death was caused by significant but indirect effects of drought. We also found that species occupying middle positions along the isohydric to anisohydric continuum suffered less mortality than those at either extremes (i.e. extremely isohydric or extremely anisohydric). Finally, our study suggested that species differences in mortality mechanisms can be overwhelmed and masked in extreme droughts and should be examined in a broad range of drought intensity.« less
Modeling Planarization in Chemical-Mechanical Leonard Borucki
, 2002 Abstract A mathematical model for chemical-mechanical polishing is developed. The ef- fects of padModeling Planarization in Chemical-Mechanical Polishing Leonard Borucki , Dilek Alagoz , Stephanie and compared to experimental data. 1 Problem Description 1.1 Physical Problem Chemical-mechanical polishing
Continuum Electrostatics in Cell Biology
L. John Gagliardi
2010-02-06T23:59:59.000Z
Recent experiments revealing possible nanoscale electrostatic interactions in force generation at kinetochores for chromosome motions have prompted speculation regarding possible models for interactions between positively charged molecules in kinetochores and negative charge on C-termini near the plus ends of microtubules. A clear picture of how kinetochores establish and maintain a dynamic coupling to microtubules for force generation during the complex motions of mitosis remains elusive. The current paradigm of molecular cell biology requires that specific molecules, or molecular geometries, for force generation be identified. However, it is possible to account for mitotic motions within a classical electrostatics approach in terms of experimentally known cellular electric charge interacting over nanometer distances. These charges are modeled as bound surface and volume continuum charge distributions. Electrostatic consequences of intracellular pH changes during mitosis may provide a master clock for the events of mitosis.
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:5 TablesExports(Journal Article) |govInstrumentsmfrirt DocumentationSitesWeather6Environmental SecurityExtra-Large MemoryFORFES UserPourbzixFMM NEAMS Project
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...
Mechanics,Mechanisms and Modeling of the Chemical Mechanical Polishing Process
Noh, Kyungyoon
The Chemical Mechanical polishing (CMP) process is now widely employed in the Integrated Circuit Fabrication. However, due to the complexity of process parameters on the material removal rate (MRR), mechanism of material ...
Nuclear rotation in the continuum
Fossez, K; Jaganathen, Y; Michel, N; P?oszajczak, M
2015-01-01T23:59:59.000Z
Atomic nuclei often exhibit collective rotational-like behavior in highly excited states, well above the particle emission threshold. What determines the existence of collective motion in the continuum region, is not fully understood. In this work, by studying the collective rotation of the positive-parity deformed configurations of the one-neutron halo nucleus $^{11}$Be, we assess different mechanisms that stabilize collective behavior beyond the limits of particle stability. To solve a particle-plus-core problem, we employ a coupled-channel formalism and the Berggren single-particle ensemble, which explicitly contains bound states, narrow resonances, and the scattering space. We study the valence-neutron density in the intrinsic rotor frame to assess the validity of the adiabatic approach as the excitation energy increases. We demonstrate that collective rotation of the ground band of $^{11}$Be is stabilized by (i) the fact that the $\\ell=0$ one-neutron decay channel is closed, and (ii) the angular momentum...
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...
Constant displacement rate experiments and constitutive modeling of asphalt mixtures
Hariharakumar, Pradeep
2006-04-12T23:59:59.000Z
The focus of this dissertation is on constant displacment rate experiments on asphalt concrete and on developing continuum models in a general thermo-mechanical setting which will corroborate with the experimental results. Modeling asphalt concrete...
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
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...
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.
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...
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.
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.
A mechanical model for Fourier's law of heat conduction
David Ruelle
2011-02-27T23:59:59.000Z
Nonequilibrium statistical mechanics close to equilibrium is a physically satisfactory theory centered on the linear response formula of Green-Kubo. This formula results from a formal first order perturbation calculation without rigorous justification. A rigorous derivation of Fourier's law for heat conduction from the laws of mechanics remains thus a major unsolved problem. In this note we present a deterministic mechanical model of a heat-conducting chain with nontrivial interactions, where kinetic energy fluctuations at the nodes of the chain are removed. In this model the derivation of Fourier's law can proceed rigorously.
Statistical Mechanics Approaches to the Modeling of Nonlinear Earthquake Physics
earthquake forecasting/prediction program in Japan, this event was a complete surprise. Similar scenarios1 Statistical Mechanics Approaches to the Modeling of Nonlinear Earthquake Physics John B. Rundle1, IN Abstract. We discuss the problem of earthquake forecasting in the context of new models for the dynamics
A mechanical approach to mean field spin models
Giuseppe Genovese; Adriano Barra
2009-05-07T23:59:59.000Z
Inspired by the bridge pioneered by Guerra among statistical mechanics on lattice and analytical mechanics on 1+1 continuous Euclidean space-time, we built a self-consistent method to solve for the thermodynamics of mean-field models defined on lattice, whose order parameters self average. We show the whole procedure by analyzing in full details the simplest test case, namely the Curie-Weiss model. Further we report some applications also to models whose order parameters do not self-average, by using the Sherrington-Kirkpatrick spin glass as a guide.
A Specific N = 2 Supersymmetric Quantum Mechanical Model: Supervariable Approach
Shukla, Aradhya
2015-01-01T23:59:59.000Z
By exploiting the supersymmetric invariant restrictions on the chiral and anti-chiral supervariables, we derive the off-shell nilpotent symmetry transformations for a specific (0 + 1)-dimensional N = 2 supersymmetric quantum mechanical model which is considered on a (1, 2)-dimensional supermanifold (parametrized by a bosonic variable t and a pair of Grassmannian variables (\\theta, \\bar\\theta). We also provide the geometrical meaning to the symmetry transformations. Finally, we show that this specific N = 2 SUSY quantum mechanical model is a model for Hodge theory.
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)
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.
Lagrangian continuum dynamics in ALEGRA.
Wong, Michael K. W.; Love, Edward
2007-12-01T23:59:59.000Z
Alegra is an ALE (Arbitrary Lagrangian-Eulerian) multi-material finite element code that emphasizes large deformations and strong shock physics. The Lagrangian continuum dynamics package in Alegra uses a Galerkin finite element spatial discretization and an explicit central-difference stepping method in time. The goal of this report is to describe in detail the characteristics of this algorithm, including the conservation and stability properties. The details provided should help both researchers and analysts understand the underlying theory and numerical implementation of the Alegra continuum hydrodynamics algorithm.
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 ...
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
Mathematical modeling of mechanical vibration assisted conductivity imaging
Ammari, Habib; Kwon, Hyeuknam; Seo, Jin Keun; Woo, Eung Je
2014-01-01T23:59:59.000Z
This paper aims at mathematically modeling a new multi-physics conductivity imaging system incorporating mechanical vibrations simultaneously applied to an imaging object together with current injections. We perturb the internal conductivity distribution by applying time-harmonic mechanical vibrations on the boundary. This enhances the effects of any conductivity discontinuity on the induced internal current density distribution. Unlike other conductivity contrast enhancing frameworks, it does not require a prior knowledge of a reference data. In this paper, we provide a mathematical framework for this novel imaging modality. As an application of the vibration-assisted impedance imaging framework, we propose a new breast image reconstruction method in electrical impedance tomography (EIT). As its another application, we investigate a conductivity anomaly detection problem and provide an efficient location search algorithm. We show both analytically and numerically that the applied mechanical vibration increas...
Evolution of generalized couple-stress continuum theories: a critical analysis
Ali R. Hadjesfandiari; Gary F. Dargush
2014-12-30T23:59:59.000Z
In this paper, we examine different generalized couple-stress continuum mechanics theories, including couple stress, strain gradient and micropolar theories. First, we investigate the fundamental requirements in any consistent size-dependent couple stress continuum mechanics, for which satisfying basic rules of mathematics and mechanics are crucial to establish a consistent theory. As a result, we show that continuum couple stress theory must be based on the displacement field and its corresponding macrorotation field as degrees of freedom, while an extraneous artificial microrotation cannot be a true continuum mechanical concept. Furthermore, the idea of generalized force and independent generalized degrees of freedom show that the normal component of the surface moment traction vector must vanish. Then, with these requirements in mind, various existing couple stress theories are examined critically, and we find that certain deviatoric curvature tensors create indeterminacy in the spherical part of the couple stress tensor. We also examine micropolar and micromorphic theories from this same perspective.
Mechanical Modeling of a WIPP Drum Under Pressure
Smith, Jeffrey A. [Sandia National Laboratories, Albuquerque, NM (United States)
2014-11-25T23:59:59.000Z
Mechanical modeling was undertaken to support the Waste Isolation Pilot Plant (WIPP) technical assessment team (TAT) investigating the February 14th 2014 event where there was a radiological release at the WIPP. The initial goal of the modeling was to examine if a mechanical model could inform the team about the event. The intention was to have a model that could test scenarios with respect to the rate of pressurization. It was expected that the deformation and failure (inability of the drum to contain any pressure) would vary according to the pressurization rate. As the work progressed there was also interest in using the mechanical analysis of the drum to investigate what would happen if a drum pressurized when it was located under a standard waste package. Specifically, would the deformation be detectable from camera views within the room. A finite element model of a WIPP 55-gallon drum was developed that used all hex elements. Analyses were conducted using the explicit transient dynamics module of Sierra/SM to explore potential pressurization scenarios of the drum. Theses analysis show similar deformation patterns to documented pressurization tests of drums in the literature. The calculated failure pressures from previous tests documented in the literature vary from as little as 16 psi to 320 psi. In addition, previous testing documented in the literature shows drums bulging but not failing at pressures ranging from 69 to 138 psi. The analyses performed for this study found the drums failing at pressures ranging from 35 psi to 75 psi. When the drums are pressurized quickly (in 0.01 seconds) there is significant deformation to the lid. At lower pressurization rates the deformation of the lid is considerably less, yet the lids will still open from the pressure. The analyses demonstrate the influence of pressurization rate on deformation and opening pressure of the drums. Analyses conducted with a substantial mass on top of the closed drum demonstrate that the drums will still open provided the pressure is high enough. Investigation teams should look for displaced drum lids when searching for drums that have pressurized and failed. The mechanical modeling study for this program is summarized in the following memo. Following a brief introduction, there is a summary of a brief literature review of previous pressure testing of drums, an explanation of the model, presentation of the key results, some discussion, and concluding with a summary and key points.
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
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
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.
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.
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.
Curved mesh generation and mesh refinement using Lagrangian solid mechanics
Persson, P.-O.
2009-01-01T23:59:59.000Z
Nonlinear continuum mechanics for ?nite element analysis,nement using Lagrangian Solid Mechanics Per-Olof Persson ?methods for computational mechanics has been emphasized in
Swift, Michael
Introduction Aim of the Paper Game Model Defense Mechanism 1 Defense Mechanism 2 Hidden Difficulty Model Defense Mechanism 1 Defense Mechanism 2 Hidden Difficulty Puzzle Conclusions Outline 1 Introduction 2 Aim of the Paper 3 Game Model Player Actions Payoff Functions 4 Defense Mechanism 1
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
New method for extracting quasi-bound states from the continuum
J. B. Faes; M. Ploszajczak
2007-09-19T23:59:59.000Z
A new parameter-free method is proposed for treatment of single-particle resonances in the real-energy continuum shell model. This method yields quasi-bound states embedded in the continuum which provide a natural generalization of weakly bound single-particle states.
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
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...
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.
The Potential of MEMS for Advancing Experiments and Modeling in Cell Mechanics
Espinosa, Horacio D.
The Potential of MEMS for Advancing Experiments and Modeling in Cell Mechanics O. Loh & A. Vaziri # Society for Experimental Mechanics 2007 Abstract Response to mechanical stimuli largely dictates cellular the hierarchical cell structure. As experimental and model-based investigations in cell mechanics advance
Statistical mechanics models for multimode lasers and random lasers
Antenucci, F; Berganza, M Ibáñez; Marruzzo, A; Leuzzi, L
2015-01-01T23:59:59.000Z
We review recent statistical mechanical approaches to multimode laser theory. The theory has proved very effective to describe standard lasers. We refer of the mean field theory for passive mode locking and developments based on Monte Carlo simulations and cavity method to study the role of the frequency matching condition. The status for a complete theory of multimode lasing in open and disordered cavities is discussed and the derivation of the general statistical models in this framework is presented. When light is propagating in a disordered medium, the system can be analyzed via the replica method. For high degrees of disorder and nonlinearity, a glassy behavior is expected at the lasing threshold, providing a suggestive link between glasses and photonics. We describe in details the results for the general Hamiltonian model in mean field approximation and mention an available test for replica symmetry breaking from intensity spectra measurements. Finally, we summary some perspectives still opened for such...
Proceedings of IMECE2007 2007 ASME International Mechanical Engineering Congress and Exposition
Regueiro, Richard A.
Proceedings of IMECE2007 2007 ASME International Mechanical Engineering Congress and Exposition particle mechanics and the discrete element method, whereas the continuum region is modeled using linear silo flows), dry soils (sand, silt, gravel), and lunar and martian regolith (soil found on the surface
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.
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.
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 ...
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
Relativistic viscoelastic fluid mechanics
Masafumi Fukuma; Yuho Sakatani
2011-09-01T23:59:59.000Z
A detailed study is carried out for the relativistic theory of viscoelasticity which was recently constructed on the basis of Onsager's linear nonequilibrium thermodynamics. After rederiving the theory using a local argument with the entropy current, we show that this theory universally reduces to the standard relativistic Navier-Stokes fluid mechanics in the long time limit. Since effects of elasticity are taken into account, the dynamics at short time scales is modified from that given by the Navier-Stokes equations, so that acausal problems intrinsic to relativistic Navier-Stokes fluids are significantly remedied. We in particular show that the wave equations for the propagation of disturbance around a hydrostatic equilibrium in Minkowski spacetime become symmetric hyperbolic for some range of parameters, so that the model is free of acausality problems. This observation suggests that the relativistic viscoelastic model with such parameters can be regarded as a causal completion of relativistic Navier-Stokes fluid mechanics. By adjusting parameters to various values, this theory can treat a wide variety of materials including elastic materials, Maxwell materials, Kelvin-Voigt materials, and (a nonlinearly generalized version of) simplified Israel-Stewart fluids, and thus we expect the theory to be the most universal description of single-component relativistic continuum materials. We also show that the presence of strains and the corresponding change in temperature are naturally unified through the Tolman law in a generally covariant description of continuum mechanics.
On Foundations of Newtonian Mechanics
Al Cheremensky
2011-03-27T23:59:59.000Z
Being based on V. Konoplev's axiomatic approach to continuum mechanics, the paper broadens its frontiers in order to bring together continuum mechanics with classical mechanics in a new theory of mechanical systems. There are derived motion equations of `abstract' mechanical systems specified for mass-points, multibody systems and continua: Newton-Euler equations, Lagrange equations of II kind and Navier-Stokes ones. Quasi-linear constitutive equations are introduced in conformity with V. Konoplev's definition of stress and strain (rate) matrices.
Double-link expandohedra: a mechanical model for expansion of a virus
Guest, Simon
Double-link expandohedra: a mechanical model for expansion of a virus By F. KovÂ´acs1 , T. Tarnai2), the derived expandohedra provide a mechanical model for the experimen- tally observed swelling of viruses such as cowpea chlorotic mottle virus (CCMV). A fully symmetric swelling motion (a finite mechanism) is found
Title: Hydraulic modeling of a mixed water level control hydro-mechanical gate
Paris-Sud XI, Université 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
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
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
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 ...
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
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
Heinzel, P. [Astronomical Institute, Academy of Sciences of the Czech Republic, Fri?ova 298, 25165 Ond?ejov (Czech Republic); Kleint, L., E-mail: pheinzel@asu.cas.cz [University of Applied Sciences and Arts Northwestern Switzerland, Bahnhofstrasse 6, 5210 Windisch (Switzerland)
2014-10-20T23:59:59.000Z
We present a novel observation of the white light flare (WLF) continuum, which was significantly enhanced during the X1 flare on 2014 March 29 (SOL2014-03-29T17:48). Data from the Interface Region Imaging Spectrograph (IRIS) in its near-UV channel show that at the peak of the continuum enhancement, the contrast at the quasi-continuum window above 2813 Å reached 100%-200% and can be even larger closer to Mg II lines. This is fully consistent with the hydrogen recombination Balmer-continuum emission, which follows an impulsive thermal and non-thermal ionization caused by the precipitation of electron beams through the chromosphere. However, a less probable photospheric continuum enhancement cannot be excluded. The light curves of the Balmer continuum have an impulsive character with a gradual fading, similar to those detected recently in the optical region on the Solar Optical Telescope on board Hinode. This observation represents a first Balmer-continuum detection from space far beyond the Balmer limit (3646 Å), eliminating seeing effects known to complicate the WLF detection. Moreover, we use a spectral window so far unexplored for flare studies, which provides the potential to study the Balmer continuum, as well as many metallic lines appearing in emission during flares. Combined with future ground-based observations of the continuum near the Balmer limit, we will be able to disentangle various scenarios of the WLF origin. IRIS observations also provide a critical quantitative measure of the energy radiated in the Balmer continuum, which constrains various models of the energy transport and deposit during flares.
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.
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
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.
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...
A Mechanical Model for Erosion in Copper Chemical-Mechanical Polishing
Noh, Kyungyoon
The Chemical-mechanical polishing (CMP) process is now widely employed in the ultralarge scale integration chip fabrication. Due to the continuous advances in semiconductor fabrication technology and decreasing sub-micron ...
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
Three-body interactions improve the prediction of rate and mechanism in protein folding models
Plotkin, Steven S.
Three-body interactions improve the prediction of rate and mechanism in protein folding models M. R-body interactions on rate and mechanism in protein folding by using the results of molecular dynamics simulations that stabilize protein structures and govern protein folding mechanisms is a fundamental problem in molecular
Neutrino mass mechanisms in 3-3-1 models: A short review
C. A. de S. Pires
2014-12-03T23:59:59.000Z
In this paper we review some mechanisms that provide light neutrinos in the framework of 3-3-1 gauge models without exotic leptons. In regard to the minimal 3-3-1 model, we call the attention to the fact that the perturbative regime of the model goes until 5 TeV. This requires alternative mechanisms in order to generate light neutrinos. In this review we discuss two mechanisms capable of generating light neutrinos in the framework of the minimal 3-3-1 model. In regard to the 3-3-1 model with right-handed neutrinos, we call the attention to the fact that in it mechanisms that generate light left-handed neutrinos also generate light right-handed neutrinos. Finally, we call the attention to the fact that the 3-3-1 model with right-handed neutrinos accommodate naturally the inverse seesaw mechanism.
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 ...
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...
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, ...
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....
Hand and Finger Kinematics and their Neural Mechanisms Lucia Castellanos August 2013 CMU-ML-13Statistical Models and Algorithms for Studying Hand and Finger Kinematics and their Neural Mechanisms Lucia Castellanos August 2013 CMU-ML-13-108 #12;#12;Statistical Models and Algorithms for Studying
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
Argyris Nicolaidis
2012-11-09T23:59:59.000Z
We suggest that the inner syntax of Quantum Mechanics is relational logic, a form of logic developed by C. S. Peirce during the years 1870 - 1880. The Peircean logic has the structure of category theory, with relation serving as an arrow (or morphism). At the core of the relational logical system is the law of composition of relations. This law leads to the fundamental quantum rule of probability as the square of an amplitude. Our study of a simple discrete model, extended to the continuum, indicates that a finite number of degrees of freedom can live in phase space. This "granularity" of phase space is determined by Planck's constant h. We indicate also the broader philosophical ramifications of a relational quantum mechanics.
Coronado, Eduardo A. [Department of Chemistry, University of California, and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [Department of Chemistry, University of California, and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Batista, Victor S. [Department of Chemistry, University of California, and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [Department of Chemistry, University of California, and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Miller, William H. [Department of Chemistry, University of California, and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [Department of Chemistry, University of California, and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
2000-04-01T23:59:59.000Z
In this paper we investigate the nonadiabatic photodissociation dynamics of ICN in the A(tilde sign) continuum, using a semiclassical initial value representation method which is able to describe electronically nonadiabatic processes through the quantization of the classical electron-nuclear model Hamiltonian of Meyer and Miller [J. Chem. Phys. 70, 3214 (1979)]. We explore the capabilities of this semiclassical technique as applied to studying the ICN absorption spectrum, and the CN rotational distribution, through direct comparison of our semiclassical results with experimental data, and with full quantum mechanical calculations. We find that the Meyer-Miller Hamiltonian, quantized according to the semiclassical prescription, describes the ICN photodissociation dynamics in excellent agreement with full-quantum mechanical calculations. (c) 2000 American Institute of Physics.
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
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.
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
THE MECHANICS OF CONTINUUM ROBOTS: MODELBASED SENSING AND CONTROL
as well as career advice. In addition, the National Science Foundation, the National Institutes of Health, and Xianshi Xie. I have really enjoyed our interactions, whether digging into a problem, philosophizing about
Uncertainty Quantification in Modeling HIV Viral Mechanics H.T. Banks1,2
Uncertainty Quantification in Modeling HIV Viral Mechanics H.T. Banks1,2 , Robert Baraldi1 for the resulting parameter estimates. Key Words: In-host HIV-1 progression models, uncertainty quantification of [7] for further analysis. A major motivation for revisiting this model is its potential to be readily
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
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
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
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
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...
Lee, Sang Hoon
2012-02-14T23:59:59.000Z
, changing rock permeability. In this work, two- and three-dimensional finite element methods were developed to simulate coupled reservoirs with damage mechanics and stress-dependent permeability. The model considers the influence of fluid flow, temperature...
Mechanical Systems on an almost Kähler model of a Finsler Manifold
Mehmet Tekkoyun; O?uzhan Çelik
2012-11-06T23:59:59.000Z
In this study, we present a new analogue of Euler-Lagrange and Hamilton equations on an almost K\\"ahler model of a Finsler manifold. Also, we give some corollories about the related mechanical systems and equations.
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 ...
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
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.
Paris-Sud XI, Université 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
Emergent Semiclassical Time in Quantum Gravity. I. Mechanical Models
Edward Anderson
2007-11-04T23:59:59.000Z
Strategies intended to resolve the problem of time in quantum gravity by means of emergent or hidden timefunctions are considered in the arena of relational particle toy models. In situations with `heavy' and `light' degrees of freedom, two notions of emergent semiclassical WKB time emerge; these are furthermore equivalent to two notions of emergent classical `Leibniz--Mach--Barbour' time. I futhermore study the semiclassical approach, in a geometric phase formalism, extended to include linear constraints, and with particular care to make explicit those approximations and assumptions used. I propose a new iterative scheme for this in the cosmologically-motivated case with one heavy degree of freedom. I find that the usual semiclassical quantum cosmology emergence of time comes hand in hand with the emergence of other qualitatively significant terms, including back-reactions on the heavy subsystem and second time derivatives. I illustrate my analysis by taking it further for relational particle models with linearly-coupled harmonic oscillator potentials. As these examples are exactly soluble by means outside the semiclassical approach, they are additionally useful for testing the justifiability of some of the approximations and assumptions habitually made in the semiclassical approach to quantum cosmology. Finally, I contrast the emergent semiclassical timefunction with its hidden dilational Euler time counterpart.
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.
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.
Sluse, D; Anguita, T; Braibant, L; Riaud, P
2015-01-01T23:59:59.000Z
Testing the standard Shakura-Sunyaev model of accretion is a challenging task because the central region of quasars where accretion takes place is unresolved with telescopes. The analysis of microlensing in gravitationally lensed quasars is one of the few techniques which can test this model, yielding to the measurement of the size and of the temperature profile of the accretion disc. We present spectroscopic observations of the gravitationally lensed broad absorption line quasar H1413+117, which reveal partial microlensing of the continuum emission that appears to originate from two separated regions, a microlensed region corresponding the compact accretion disc, and a non-microlensed region, more extended and contributing to at least 30\\% of the total UV-continuum flux. Because this extended continuum is occulted by the broad absorption line clouds, it is not associated to the host galaxy, but rather to light scattered in the neighbourhood of the central engine. We measure the amplitude of microlensing of t...
A multiscale Molecular Dynamics approach to Contact Mechanics
C. Yang; U. Tartaglino; B. N. J. Persson
2006-01-05T23:59:59.000Z
The friction and adhesion between elastic bodies are strongly influenced by the roughness of the surfaces in contact. Here we develop a multiscale molecular dynamics approach to contact mechanics, which can be used also when the surfaces have roughness on many different length-scales, e.g., for self affine fractal surfaces. As an illustration we consider the contact between randomly rough surfaces, and show that the contact area varies linearly with the load for small load. We also analyze the contact morphology and the pressure distribution at different magnification, both with and without adhesion. The calculations are compared with analytical contact mechanics models based on continuum mechanics.
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.
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
On models for viscoelastic fluid-like materials that are mechanically incompressible and
Cerveny, Vlastislav
of state. Liquids.) Viscoelastic fluid like materials. (Internal energy has a non-thermal contributionOn models for viscoelastic fluid-like materials that are mechanically incompressible and thermallyBoussinesq approximation. Math. Models Methods Appl. Sci., 6(8):11571167, 1996 #12;OberbeckBoussinesq system
Efficient Barrier Synchronization Mechanism for the BSP Model on Message-Passing Architectures
Ha, Soonhoi
Efficient Barrier Synchronization Mechanism for the BSP Model on Message-Passing Architectures Jin-742, KOREA jinsoo, sha, csjhonÂ¡ @comp.snu.ac.kr Abstract The Bulk Synchronous Parallel (BSP) model of computa- tion can be used to develop efficient and portable programs for a range of machines
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
P. Evesque
2005-07-04T23:59:59.000Z
It has been proposed recently a new incremental modelling to describe the mechanics of soil. It is based on two parameters called the pseudo Young modulus E=1/Co and the pseudo Poisson coefficient n, which both evolve during compression. Evolution of n is known since it shall fit the Rowe's law of dilatancy, but Co has to be evaluated from experiment. In this paper we proposed a way to evaluate the Co variation from other mechanical modelling. The way cyclic behaviour of drained sample can be modelled is also described.
Modelling the Mechanics and Hydrodynamics of Swimming E. coli
Jinglei Hu; Mingcheng Yang; Gerhard Gompper; Roland G. Winkler
2015-08-04T23:59:59.000Z
The swimming properties of an E. coli-type model bacterium are investigated by mesoscale hy- drodynamic simulations, combining molecular dynamics simulations of the bacterium with the multiparticle particle collision dynamics method for the embedding fluid. The bacterium is com- posed of a spherocylindrical body with attached helical flagella, built up from discrete particles for an efficient coupling with the fluid. We measure the hydrodynamic friction coefficients of the bacterium and find quantitative agreement with experimental results of swimming E. coli. The flow field of the bacterium shows a force-dipole-like pattern in the swimming plane and two vor- tices perpendicular to its swimming direction arising from counterrotation of the cell body and the flagella. By comparison with the flow field of a force dipole and rotlet dipole, we extract the force- dipole and rotlet-dipole strengths for the bacterium and find that counterrotation of the cell body and the flagella is essential for describing the near-field hydrodynamics of the bacterium.
Force Transduction and Lipid Binding in MscL: A Continuum-Molecular Approach
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Vanegas, Juan M.; Arroyo, Marino; Fotiadis, Dimitrios
2014-12-01T23:59:59.000Z
The bacterial mechanosensitive channel MscL, a small protein mainly activated by membrane tension, is a central model system to study the transduction of mechanical stimuli into chemical signals. Mutagenic studies suggest that MscL gating strongly depends on both intra-protein and interfacial lipid-protein interactions. However, there is a gap between this detailed chemical information and current mechanical models of MscL gating. Here, we investigate the MscL bilayer-protein interface through molecular dynamics simulations, and take a combined continuum-molecular approach to connect chemistry and mechanics. We quantify the effect of membrane tension on the forces acting on the surface of the channel, andmore »identify interactions that may be critical in the force transduction between the membrane and MscL. We find that the local stress distribution on the protein surface is largely asymmetric, particularly under tension, with the cytoplasmic side showing significantly larger and more localized forces, which pull the protein radially outward. The molecular interactions that mediate this behavior arise from hydrogen bonds between the electronegative oxygens in the lipid headgroup and a cluster of positively charged lysine residues on the amphipathic S1 domain and the C-terminal end of the second trans-membrane helix. We take advantage of this strong interaction (estimated to be 10–13 kT per lipid) to actuate the channel (by applying forces on protein-bound lipids) and explore its sensitivity to the pulling magnitude and direction. We conclude by highlighting the simple motif that confers MscL with strong anchoring to the bilayer, and its presence in various integral membrane proteins including the human mechanosensitive channel K2P1 and bovine rhodopsin.« less
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.
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.
Simulation of neoclassical transport with the continuum gyrokinetic code COGENT
Dorf, M. A.; Cohen, R. H.; Dorr, M.; Rognlien, T.; Hittinger, J.; Compton, J. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Colella, P.; Martin, D.; McCorquodale, P. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
2013-01-15T23:59:59.000Z
The development of the continuum gyrokinetic code COGENT for edge plasma simulations is reported. The present version of the code models a nonlinear axisymmetric 4D (R, v{sub Parallel-To }, {mu}) gyrokinetic equation coupled to the long-wavelength limit of the gyro-Poisson equation. Here, R is the particle gyrocenter coordinate in the poloidal plane, and v{sub Parallel-To} and {mu} are the guiding center velocity parallel to the magnetic field and the magnetic moment, respectively. The COGENT code utilizes a fourth-order finite-volume (conservative) discretization combined with arbitrary mapped multiblock grid technology (nearly field-aligned on blocks) to handle the complexity of tokamak divertor geometry with high accuracy. Topics presented are the implementation of increasingly detailed model collision operators, and the results of neoclassical transport simulations including the effects of a strong radial electric field characteristic of a tokamak pedestal under H-mode conditions.
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.
Lecture notes Introductory fluid mechanics
Malham, Simon J.A.
Lecture notes Introductory fluid mechanics Simon J.A. Malham Simon J.A. Malham (15th September 2014 of fluid mechanics and along the way see lots of interesting applications. 2 Fluid flow, the Continuum are generally incompressible--a feature essential to all modern car braking mechanisms. Fluids can be further
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
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.
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
A. Besser; U. S. Schwarz
2007-10-24T23:59:59.000Z
Biochemistry and mechanics are closely coupled in cell adhesion. At sites of cell-matrix adhesion, mechanical force triggers signaling through the Rho-pathway, which leads to structural reinforcement and increased contractility in the actin cytoskeleton. The resulting force acts back to the sites of adhesion, resulting in a positive feedback loop for mature adhesion. Here we model this biochemical-mechanical feedback loop for the special case when the actin cytoskeleton is organized in stress fibers, which are contractile bundles of actin filaments. Activation of myosin II molecular motors through the Rho-pathway is described by a system of reaction-diffusion equations, which are coupled into a viscoelastic model for a contractile actin bundle. We find strong spatial gradients in the activation of contractility and in the corresponding deformation pattern of the stress fiber, in good agreement with experimental findings.
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
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
Construction of a Mechanical Model for the Expansion of a Virus
Guest, Simon
Construction of a Mechanical Model for the Expansion of a Virus S.D. Guest1 , F. KovÃ¡cs2 , T@eng.cam.ac.uk, fax +44 1223 332662 Abstract Many viruses have an outer protein coat with the structure of a truncated icosahedron, and can expand following changes to the environment around the virus. The protein coat consists
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
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
Statistical mechanics of a correlated energy landscape model for protein folding funnels
Plotkin, Steven S.
Statistical mechanics of a correlated energy landscape model for protein folding funnels Steven S scientists view protein folding as a complex chemical reaction. Another fruitful analogy from statistical possible protein configurations is sufficient for understanding folding kinetics in many re- gimes
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
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
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
ES2A7 -Fluid Mechanics Example Classes Model Answers to Example Questions (Set III)
Thomas, Peter J.
ES2A7 - Fluid Mechanics Example Classes Model Answers to Example Questions (Set III) Question 1 10610 40031.8 -- ×=×= × × == APN RT d Question 2: Type of Fluid #12;Consider 2 identical vertical tubes are filled with the same height of fluid: A Newtonian fluid is used with tube X whereas a non-Newtonian fluid
Mechanics of complex bodies: commentary on the unified modelling of material substructures
Paolo Maria Mariano
2008-03-26T23:59:59.000Z
Basic issues of the general model-building framework of the mechanics of complex bodies are discussed. Attention is focused on the representation of the material elements, the conditions for the existence of ground states in conservative setting and the interpretation of the nature of the various balance laws occurring.
Bosonic seesaw mechanism in a classically conformal extension of the Standard Model
Naoyuki Haba; Hiroyuki Ishida; Nobuchika Okada; Yuya Yamaguchi
2015-08-27T23:59:59.000Z
We suggest the so-called bosonic seesaw mechanism in the context of a classically conformal $U(1)_{B-L}$ extension of the Standard Model with two Higgs doublet fields. The $U(1)_{B-L}$ symmetry is radiatively broken via the Coleman-Weinberg mechanism, which also generates the mass terms for the two Higgs doublets through quartic Higgs couplings. Their masses are all positive but, nevertheless, the electroweak symmetry breaking is realized by the bosonic seesaw mechanism. Analyzing the renormalization group evolutions for all model couplings, we find that a large hierarchy among the quartic Higgs couplings, which is crucial for the bosonic seesaw mechanism to work, is dramatically reduced toward high energies. Therefore, the bosonic seesaw is naturally realized with only a mild hierarchy, if some fundamental theory, which provides the origin of the classically conformal invariance, completes our model at some high energy, for example, the Planck scale. We identify the regions of model parameters which satisfy the perturbativity of the running couplings and the electroweak vacuum stability as well as the naturalness of the electroweak scale.
ELSEVIER Physica D 107 (1997) 322-325 Statistical mechanics of correlated energy landscape models
Plotkin, Steven S.
1997-01-01T23:59:59.000Z
ELSEVIER Physica D 107 (1997) 322-325 PHYSICA Statistical mechanics of correlated energy landscape in the energy landscape of heteropolymers and proteins, specifically their role in the glass transition q are quantitatively similar to the results for an uncorrelated landscape or random energy model
Modelling of Industrial Processes for Polymer Extrusion and Injection Moulding
Eindhoven, Technische Universiteit
/Continuum Mechanics. Faculty: Mathematics and Computing Science. Eindhoven University of Technology (EUT) Our mainModelling of Industrial Processes for Polymer Melts: Extrusion and Injection Moulding Fons van de Ven Eindhoven University of Technology P.O.Box 513; 5600 MB Eindhoven, The Netherlands Abstract
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.
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 $N_\\tau \\le 22$.
Continuum and Three-Nucleon Force Effects on 9Be Energy Levels
Joachim Langhammer; Petr Navratil; Sofia Quaglioni; Guillaume Hupin; Angelo Calci; Robert Roth
2014-11-10T23:59:59.000Z
We extend the recently proposed ab initio no-core shell model with continuum to include three-nucleon (3N) interactions beyond the few-body domain. The extended approach allows for the assessment of effects of continuum degrees of freedom as well as of the 3N force in ab initio calculations of structure and reaction observables of p- and lower-sd-shell nuclei. As first application we concentrate on energy levels of the 9Be system for which all excited states lie above the n-8Be threshold. For all energy levels, the inclusion of the continuum significantly improves the agreement with experiment, which was an issue in standard no-core shell model calculations. Furthermore, we find the proper treatment of the continuum indispensable for reliable statements about the quality of the adopted 3N interaction from chiral effective field theory. In particular, we find the 1/2+ resonance energy, which is of astrophysical interest, in good agreement with experiment.
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.
Continuum Robot Arms Inspired by Cephalopods Ian D. Walkera
Kier, William M.
Continuum Robot Arms Inspired by Cephalopods Ian D. Walkera , Darren M. Dawsona , Tamar Flashb in the development of a new class of soft, continuous backbone ("continuum") robot manipulators. Our work is strongly to delicate tasks in cluttered and/or unstructured environments. Our aim is to endow these compliant robotic
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-only and QM/MM approaches for the modeling of enzymatic reactions. For this purpose, we present a QM/MM case of the previously suggested one-water attack mechanism. The QM/MM calculations with the minimal QM region M1 (32
Folds above angular fault bends: mechanical constraints for backlimb trishear kinematic models
Zhang, Li
2004-11-15T23:59:59.000Z
for the degree of MASTER OF SCIENCE Approved as to style and content by: Judith S. Chester (Chair of Committee) Frederick M. Chester (Member) Charles P. Aubeny (Member) Andrew Hajash Jr. (Head of Department) August 2003 Major Subject: Geology iii ABSTRACT Folds... above Angular Fault Bends: Mechanical Constraints for Backlimb Trishear Kinematic Models. (August 2003) Li Zhang, B.E.; M.S., Southwest Petroleum Institute, P.R.China Chair of Advisory Committee: Dr. Judith S. Chester The backlimb trishear velocity eld...
Fluid Mechanics Unit code: MATH20502
Sidorov, Nikita
MATH20502 Fluid Mechanics Unit code: MATH20502 Credit Rating: 10 Unit level: Level 2 Teaching to continuum mechanics in general and theoretical fluid mechanics in particular. The material provides mathematics. Fluid mechanics is concerned with understanding, and hence predicting, the properties (pressure
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.
Inserting Group Variables into Fluid Mechanics
R. Jackiw
2004-10-28T23:59:59.000Z
A fluid, like a quark-gluon plasma, may possess degrees of freedom indexed by a group variable, which retains its identity even in the fluid/continuum description. Conventional Eulerian fluid mechanics is extended to encompass this possibility.
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.
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.
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.
Song, Zhichao
2012-01-01T23:59:59.000Z
H. , 2003. Fracture mechanics analysis of thin coatingsK.L. , 1985. Contact Mechanics, Cambridge University Press,J. , Chaboche, J. L. , 1994. Mechanics of Solid Materials.
Anand, Lallit
In this Part I, of a two-part paper, we present a detailed continuum-mechanical development of a thermomechanically
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.
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.
MECHANICS OF SOLIDS [published as a section of the article on MECHANICS in the 1993 printing of the
MECHANICS OF SOLIDS [published as a section of the article on MECHANICS in the 1993 printing INTRODUCTION The application of the principles of mechanics to bulk matter is conventionally divided into the mechanics of fluids and the mechanics of solids. The entire subject is often called continuum mechanics
Mechanical rejuvenation and over-aging in the soft glassy rheology model
Mya Warren; Joerg Rottler
2008-07-04T23:59:59.000Z
Mechanical rejuvenation and over-aging of glasses is investigated through stochastic simulations of the soft glassy rheology (SGR) model. Strain- and stress-controlled deformation cycles for a wide range of loading conditions are analyzed and compared to molecular dynamics simulations of a model polymer glass. Results indicate that deformation causes predominantly rejuvenation, whereas over-aging occurs only at very low temperature, small strains, and for high initial energy states. Although the creep compliance in the SGR model exhibits full aging independent of applied load, large stresses in the nonlinear creep regime cause configurational changes leading to rejuvenation of the relaxation time spectrum probed after a stress cycle. During recovery, however, the rejuvenated state rapidly returns to the original aging trajectory due to collective relaxations of the internal strain.
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.
Confinement on $R^{3}\\times S^{1}$: continuum and lattice
Michael C. Ogilvie
2014-10-07T23:59:59.000Z
There has been substantial progress in understanding confinement in a class of four-dimensional SU(N) gauge theories using semiclassical methods. These models have one or more compact directions, and much of the analysis is based on the physics of finite-temperature gauge theories. The topology $R^{3}\\times S^{1}$ has been most often studied, using a small compactification circumference $L$ such that the running coupling $g^{2}\\left(L\\right)$ is small. The gauge action is modified by a double-trace Polyakov loop deformation term, or by the addition of periodic adjoint fermions. The additional terms act to preserve $Z(N)$ symmetry and thus confinement. An area law for Wilson loops is induced by a monopole condensate. In the continuum, the string tension can be computed analytically from topological effects. Lattice models display similar behavior, but the theoretical analysis of topological effects is based on Abelian lattice duality rather than on semiclassical arguments. In both cases the key step is reducing the low-energy symmetry group from $SU(N)$ to the maximal Abelian subgroup $U(1)^{N-1}$ while maintaining $Z(N)$ symmetry.
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.
A Source for Ultrafast Continuum Infrared and Terahertz Radiation
Petersen, Poul B.
A compact and stable method for generating high-intensity linearly polarized continuum mid-IR and terahertz light using ultrafast femtosecond (fs) laser pulses is demonstrated. Continuous light generation from <400cm?1 ...
Outlining a scholarly workbench publication and data as a continuum
Paris-Sud XI, Université de
Outlining a scholarly workbench publication and data as a continuum Laurent Romary INRIA viewed from the point of view of research repositories · Publication repositories Where do we stand · A multidisciplinary field Publications: importance of conferences, long- standing culture of publication
Mechanical Modeling of a WIPP Drum Under Pressure | Department of Energy
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:1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:5 TablesExports to3,1,50022,3,,0,,6,1,Separation 23 362 334Department ofEnergyEnergy Mapping Opportunities forMechanical Modeling of a WIPP Drum
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.
Mueller, Karl
for the mechanics and kinematics of compressive wedges Phaedra Upton,1,2 Karl Mueller,3 and Yue-Gau Chen4 Received develop three-dimensional mechanical models of a compressive wedge and investigate how the form and kinematics of the outboard wedge are affected by variation in initial topography, material properties
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.
On the Vainshtein mechanism in the minimal model of massive gravity
Renaux-Petel, Sébastien, E-mail: srenaux@lpthe.jussieu.fr [Laboratoire de Physique Théorique et Hautes Energies, Université Pierre and Marie Curie - Paris VI, CNRS-UMR 7589, 4 place Jussieu, Paris, 75252 (France)
2014-03-01T23:59:59.000Z
We reinvestigate the fate of the Vainhstein mechanism in the minimal model of dRGT massive gravity. As the latter is characterised by the complete absence of interactions in the decoupling limit, we study their structure at higher energies. We show that in static spherically symmetric configurations, the lowest energy scale of interactions is pushed up to the Planck mass. This fact points towards an absence of Vainshtein mechanism in this framework, but does not prove it. By resorting to the exact vacuum equations of motion, we show that there is indeed an obstruction that precludes any recovery of General Relativity under the conditions of stationarity and spherical symmetry. However, we argue that the latter are too restrictive and might miss some important physical phenomena. Indeed, we point out that in generic non spherically symmetric or time-dependent situations, interactions arising at energies arbitrarily close to the energy scale of the decoupling limit reappear. This leads us to question whether the small degree of spherical symmetry breaking in the solar system can be sufficient to give rise to a successful Vainshtein mechanism.
Testing spontaneous wave-function collapse models on classical mechanical oscillators
Lajos Diósi
2014-11-17T23:59:59.000Z
We show that the heating effect of spontaneous wave-function collapse models implies an experimentally significant increment $\\Delta T$ of equilibrium temperature in a mechanical oscillator. The obtained form $\\Delta T$ is linear in the oscillator's relaxation time $\\tau$ and independent of the mass. The oscillator can be in a classical thermal state, the effect $\\Delta T$ is classical for a wide range of frequencies and quality factors. We note that the test of $\\Delta T$ does not necessitate quantum state monitoring but tomography. In both gravity-related (DP) and continuous spontaneous localization (CSL) models the strong-effect edge of their parameter range can be challenged in existing experiments on classical oscillators. For the CSL theory, the conjectured highest collapse rate parameter values become immediately constrained by evidences from current experiments on extreme slow-ring-down oscillators.
Oscillation of a Rotating Levitated Droplet: Analysis with a Mechanical Model
Kitahata, Hiroyuki; Koyano, Yuki; Matsumoto, Satoshi; Nishinari, Katsuhiro; Watanabe, Tadashi; Hasegawa, Koji; Kanagawa, Tetsuya; Kaneko, Akiko; Abe, Yutaka
2015-01-01T23:59:59.000Z
A droplet of millimeter-to-centimeter scale can exhibit electrostatic levitation, and such levitated droplets can be used for the measurement of the surface tension of the liquids by observing the characteristic frequency of oscillatory deformation. In the present study, a simple mechanical model is proposed by considering a single mode of oscillation in the ellipsoidal deformation of a levitated rotating droplet. By measuring the oscillation frequency with respect to the rotational speed and oscillation amplitude, it is expected that the accuracy of the surface tension measurement could be improved. Using the proposed model, the dependences of the characteristic frequency of oscillatory deformation and the averaged aspect ratio are calculated with respect to the rotational angular velocity of a rotating droplet. These dependences are found to be consistent with the experimental observations.
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.
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...
Lecture notes Introductory incompressible fluid mechanics
Malham, Simon J.A.
Lecture notes Introductory incompressible fluid mechanics Simon J.A. Malham Simon J.A. Malham (23rd of fluid mechanics and along the way see lots of interesting applications. 2 Fluid flow, the Continuum. Liquids are generally incompressible--a feature essential to all modern car braking mechanisms. Fluids can
Nicholas Rivera; Chia Wei Hsu; Bo Zhen; Hrvoje Buljan; John D. Joannopoulos; Marin Solja?i?
2015-07-03T23:59:59.000Z
A bound state in the continuum (BIC) is an unusual localized state that is embedded in a continuum of extended states. Here, we present the general condition for BICs to arise from wave equation separability and show that the directionality and dimensionality of their resonant radiation can be controlled by exploiting perturbations of certain symmetry. Using this general framework, we construct new examples of separable BICs in realistic models of optical potentials for ultracold atoms, photonic systems, and systems described by tight binding. Such BICs with easily reconfigurable radiation patterns allow for applications such as the storage and release of waves at a controllable rate and direction, systems that switch between different dimensions of confinement, and experimental realizations in atomic, optical, and electronic systems.
Modelling the Fluid Mechanics of Cilia and Flagella in Reproduction and Development
Thomas D. Montenegro-Johnson; Andrew A. Smith; David J. Smith; Daniel Loghin; John R. Blake
2013-09-04T23:59:59.000Z
Cilia and flagella are actively bending slender organelles, performing functions such as motility, feeding and embryonic symmetry breaking. We review the mechanics of viscous-dominated microscale flow, including time-reversal symmetry, drag anisotropy of slender bodies, and wall effects. We focus on the fundamental force singularity, higher order multipoles, and the method of images, providing physical insight and forming a basis for computational approaches. Two biological problems are then considered in more detail: (1) left-right symmetry breaking flow in the node, a microscopic structure in developing vertebrate embryos, and (2) motility of microswimmers through non-Newtonian fluids. Our model of the embryonic node reveals how particle transport associated with morphogenesis is modulated by the gradual emergence of cilium posterior tilt. Our model of swimming makes use of force distributions within a body-conforming finite element framework, allowing the solution of nonlinear inertialess Carreau flow. We find that a three-sphere model swimmer and a model sperm are similarly affected by shear-thinning; in both cases swimming due to a prescribed beat is enhanced by shear-thinning, with optimal Deborah number around 0.8. The sperm exhibits an almost perfect linear relationship between velocity and the logarithm of the ratio of zero to infinite shear viscosity, with shear-thickening hindering cell progress.
A fully resolved active musculo-mechanical model for esophageal transport
Wenjun Kou; Amneet Pal Singh Bhalla; Boyce E. Griffith; John E. Pandolfino; Peter J. Kahrilas; Neelesh A. Patankar
2015-01-09T23:59:59.000Z
Esophageal transport is a physiological process that mechanically transports an ingested food bolus from the pharynx to the stomach via the esophagus, a multi-layered muscular tube. This process involves interactions between the bolus, the esophagus, and the neurally coordinated activation of the esophageal muscles. In this work, we use an immersed boundary (IB) approach to simulate peristaltic transport in the esophagus. The bolus is treated as a viscous fluid that is actively transported by the muscular esophagus, which is modeled as an actively contracting, fiber-reinforced tube. A simplified version of our model is verified by comparison to an analytic solution to the tube dilation problem. Three different complex models of the multi-layered esophagus, which differ in their activation patterns and the layouts of the mucosal layers, are then extensively tested. To our knowledge, these simulations are the first of their kind to incorporate the bolus, the multi-layered esophagus tube, and muscle activation into an integrated model. Consistent with experimental observations, our simulations capture the pressure peak generated by the muscle activation pulse that travels along the bolus tail. These fully resolved simulations provide new insights into roles of the mucosal layers during bolus transport. In addition, the information on pressure and the kinematics of the esophageal wall due to the coordination of muscle activation is provided, which may help relate clinical data from manometry and ultrasound images to the underlying esophageal motor function.
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.
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 ...
A wave-mechanical model of incoherent neutron scattering II. Role of the momentum transfer
Frauenfelder, Hans; Fenimore, Paul W
2015-01-01T23:59:59.000Z
We recently introduced a wave-mechanical model for quasi-elastic neutron scattering (QENS) in proteins. We call the model ELM for "Energy Landscape Model". We postulate that the spectrum of the scattered neutrons consists of lines of natural width shifted from the center by fluctuations. ELM is based on two facts: Neutrons are wave packets; proteins have low-lying substates that form the free-energy landscape (FEL). Experiments suggest that the wave packets are a few hundred micrometers long. The interaction between the neutron and a proton in the protein takes place during the transit of the wave packet. The wave packet exerts the force $F(t) = dQ(t)/dt$ on the protein moiety, a part of the protein surrounding the struck proton. $Q(t)$ is the wave vector (momentum) transferred by the neutron wave packet to the proton during the transit. The ensuing energy is stored in the energy landscape and returned to the neutron as the wave packet exits. Kinetic energy thus is changed into potential energy and back. The ...
Paris-Sud XI, Université de
1 Thermo-mechanical FE model with memory effect for 304L austenitic stainless steel presenting. Keywords: 304L stainless steel; thermal fatigue; F.E. modelling. #12;2 1 Introduction The 304L stainless-hardened stainless steel were carried out by Taleb and Hauet [4], Taheri et al [5]. To predict the behaviour
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
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.
Investigation on mechanism of coal liquefaction-hydrocracking of model compounds
Wu, J.Z. [Tongji Univ. (China); Gao, J.S.; Hang, Y.Z. [East China Univ. of Science and Technology (China); Oelert, H.H. [Inst. of Chemical and Fuel (Germany)
1997-12-31T23:59:59.000Z
There is strong evidence for the existence of -O-CH{sub 2}- and -CH{sub 2}-CH{sub 2}-bridge linkages in coal, especially in low rank coals, so there is a close relationship between hydrocracking kinetic of model compounds and coal liquefaction. In a tube autoclave with the volume of 17 ml the hydrocracking experiments of six model compounds are carried out in the presence of tetralin. The results show that the stability order of six model compounds in hydrocracking is as follows: Ph-Ch{sub 2}-Ph > Ph-O-Ph > Ph-Ch{sub 2}-Ch{sub 2}-Ph > Ph-O-CH{sub 2}-Ph > Ph-CH{sub 2}-S-CH{sub 2}-Ph > Ph-CH{sub 2}-S-S-CH{sub 2}-Ph. Introducing 10% (in weight) of benzyl phenyl ether can increase the decomposition ratios of diphenyl methane and diphenyl ether from 4.3% to 12.6% and 18.3% to 31.5% respectively. From the hydrocracking kinetic experiments for both benzyl phenyl ether (BPE) and dibenzyl (DB), the reaction corresponds to first order. The apparent activation (DE) is 83.9 kJ/mol for BPE and 150 kJ/mol for DB in the range of temperature 330--450 C, that is, the same as coal liquefaction. The influence of initial hydrogen pressure on hydrocracking of model compounds is also described in this paper. Under the conditions of the experiments the decomposition ratios (DR) of model compounds increase linearly with the increase of initial hydrogen pressure, e.g., DR is only 34.3% under 3.0 MPa (420 C), but 56.8% can be obtained when the initial hydrogen pressure reaches 8.5 MPa. Moreover, changing the initial pressure can influence not only DR of model compounds but also their hydrocracking mechanisms. Applying Mo-Ni, Y- and 5A-sieves to hydrocracking of model compounds are all effective. For more stable compounds such as dibenzyl methane and diphenyl ether the Y-sieve is better than the Mo-Ni catalyst, but it is just contrary to crack for benzyl phenyl ether.
Improvement of Stent Retriever Design and Efficacy of Mechanical Thrombectomy in a Flow Model
Wenger, Katharina, E-mail: kwenger@stud.uni-frankfurt.de [Institute of Neuroradiology, University of Frankfurt am Main (Germany)] [Institute of Neuroradiology, University of Frankfurt am Main (Germany); Nagl, Frank, E-mail: fnagl@acandis.com [Acandis GmbH and Co KG (Germany)] [Acandis GmbH and Co KG (Germany); Wagner, Marlies, E-mail: Marlies.Wagner@kgu.de; Berkefeld, Joachim, E-mail: berkefeld@em.uni-frankfurt.de [Institute of Neuroradiology, University of Frankfurt am Main (Germany)] [Institute of Neuroradiology, University of Frankfurt am Main (Germany)
2013-02-15T23:59:59.000Z
In vitro experiments were performed to evaluate the efficacy of mechanical intracranial thrombectomy comparing the newly developed Aperio stent retriever and standard devices for stroke treatment. The Aperio (A), with an increased working length of 4 cm and a special cell design for capturing and withholding clots, was compared to three benchmark devices: the Solitaire retrievable stent (B), the Merci X6 (C), and the Merci L5 retriever (D). In a vascular glass model with pulsatile flow, reminiscent of the M1 segment of the middle cerebral artery, we repeatedly induced occlusion by generating thrombi via a modified Chandler loop system. The numbers of recanalization attempts, peripheral embolizations, and recanalizations at the site of occlusion were recorded during 10 retrieval experiments with each device. Eleven devices were able to remove the blood clots from the occluded branch. In 34 of 40 experiments, restoration of flow was obtained in 1-3 attempts. The main differences between the study devices were observed in terms of clot withholding and fragmentation during retrieval. Although there was only one fragmentation recorded for device A, disengagement of the whole clot or peripheral embolization of fragments occurred more frequently (5-7 times) with devices B, C, and D. In a vascular model, the design of device A was best at capturing and withholding thrombi during retrieval. Further study will be necessary to see whether this holds true in clinical applications.
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.
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
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:1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:5(Million Cubic Feet) Oregon (Including Vehicle Fuel) (Million CubicRefiners SwitchBenefitsBeam LineSandian asckho Home AboutCenter forArevaCoupling
THMC Modeling of EGS Reservoirs Â… Continuum through Discontinuum
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on DeliciousPlasma |Efficiency Â» Searchto Increase Bioenergy Crop Production0 - In the Matter NovemberWORLD'STHIS
Continuum modeling of diffusion and dispersion in dense granular flows
Office of Scientific and Technical Information (OSTI)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:5 TablesExports to3,1,50022,3,,0,,6,1,Separation 23TribalInformationConference: CatalyticSignaturesSciTechConnectElectronMeasurementsand
Continuum modeling of diffusion and dispersion in dense granular flows
Office of Scientific and Technical Information (OSTI)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:5 TablesExports to3,1,50022,3,,0,,6,1,Separation 23TribalInformationConference:
Continuum- based computational models of biological living cell
Cheng, Feifei
2009-05-15T23:59:59.000Z
All living creatures, despite their profound diversity, share a common architectural building block: the cell. Cells are the basic functional units of life, yet are themselves comprised of numerous components with distinct ...
A wave-mechanical model of incoherent neutron scattering II. Role of the momentum transfer
Hans Frauenfelder; Robert D. Young; Paul W. Fenimore
2015-08-20T23:59:59.000Z
We recently introduced a wave-mechanical model for quasi-elastic neutron scattering (QENS) in proteins. We call the model ELM for "Energy Landscape Model". We postulate that the spectrum of the scattered neutrons consists of lines of natural width shifted from the center by fluctuations. ELM is based on two facts: Neutrons are wave packets; proteins have low-lying substates that form the free-energy landscape (FEL). Experiments suggest that the wave packets are a few hundred micrometers long. The interaction between the neutron and a proton in the protein takes place during the transit of the wave packet. The wave packet exerts the force $F(t) = dQ(t)/dt$ on the protein moiety, a part of the protein surrounding the struck proton. $Q(t)$ is the wave vector (momentum) transferred by the neutron wave packet to the proton during the transit. The ensuing energy is stored in the energy landscape and returned to the neutron as the wave packet exits. Kinetic energy thus is changed into potential energy and back. The interaction energy is proportional to $Q$, not to $Q^2$. To develop and check the ELM, we use published work on dehydrated proteins after reversing improper normalizations. In such proteins only vibrations are active and the effects caused by the neutron momentum can be studied undisturbed by external fluctuations. ELM has predictive power. For example it quantitatively predicts the observed inelastic incoherent fraction $S(Q, T)$ over a broad range of temperature and momentum $Q$ with one coefficient if $S(0, T)$ is known.
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 ...
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,
Song, Zhichao
2012-01-01T23:59:59.000Z
surface adhesion in microelectromechanical systems. ASME J.microtribology for microelectromechanical systems. Wear 200,forces in microelectromechanical systems: mechanisms,
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 ...
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
Resonant continuum in the Hartree-Fock+BCS approximation
Sandulescu, N; Liotta, R J; Giai, Nguyen Van
2000-01-01T23:59:59.000Z
A method for incorporating the effect of the resonant continuum into Hartree-Fock+BCS equations is proposed. This method is implemented for a Skyrme force in the mean field part and for a pairing interaction of seniority type. As an example the influence of the width of resonant states on the pairing properites of nuclei close to the drip line is analyzed.
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
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 ...
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.
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.
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.
Komatitsch, Dimitri
Three-dimensional mechanical models for the June 2000 earthquake sequence in the south Iceland, University of Iceland, Reykjavik, Iceland A B S T R A C TA R T I C L E I N F O Article history: Received 11 Keywords: South Iceland seismic zone Lithospheric heterogeneity influences Finite-element method Co
Borja, Ronaldo I.
Mechanical models of fracture reactivation and slip on bedding surfaces during folding June 2008 Accepted 5 June 2008 Available online 13 June 2008 Keywords: Fold Fracture reactivation Bed methods to investigate the reactivation of fractures (opening and shearing) and the development of bedding
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
California at Santa Cruz, University of
behave when subjected to external influences. External influences which a#ect the properties concentrate upon the macroscopic properties rather than the microscopic properties of the material. We treat a linear elastic material. In contrast, a plastic material is one which deforms under applied forces
California at Santa Cruz, University of
behave when subjected to external influences. External influences which affect the properties concentrate upon the macroscopic properties rather than the microscopic properties of the material. We treat a linear elastic material. In contrast, a plastic material is one which deforms under applied forces
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Bouskill, N. J.; Riley, W. J.; Tang, J. Y.
2014-01-01T23:59:59.000Z
Accurate representation of ecosystem processes in land models is crucial for reducing predictive uncertainty in energy and greenhouse gas feedbacks with the climate. Here we describe an observational and modeling meta-analysis approach to benchmark land models, and apply the method to the land model CLM4.5 with two versions of belowground biogeochemistry. We focused our analysis on the aboveground and belowground responses to warming and nitrogen addition in high-latitude ecosystems, and identified absent or poorly parameterized mechanisms in CLM4.5. While the two model versions predicted similar soil carbon stock trajectories following both warming and nitrogen addition, other predicted variables (e.g., belowgroundmore »respiration) differed from observations in both magnitude and direction, indicating that CLM4.5 has inadequate underlying mechanisms for representing high-latitude ecosystems. On the basis of observational synthesis, we attribute the model–observation differences to missing representations of microbial dynamics, aboveground and belowground coupling, and nutrient cycling, and we use the observational meta-analysis to discuss potential approaches to improving the current models. However, we also urge caution concerning the selection of data sets and experiments for meta-analysis. For example, the concentrations of nitrogen applied in the synthesized field experiments (average = 72 kg ha-1 yr-1) are many times higher than projected soil nitrogen concentrations (from nitrogen deposition and release during mineralization), which precludes a rigorous evaluation of the model responses to likely nitrogen perturbations. Overall, we demonstrate that elucidating ecological mechanisms via meta-analysis can identify deficiencies in ecosystem models and empirical experiments.« less
Haldar, Krishnendu 1978-
2012-12-06T23:59:59.000Z
-mechanical responses of such materials are governed by two major mechanisms which are variant reorientation and field induced phase transformation (FIPT). The most widely used material for variant reorientation is Ni2 MnGa which can produce up to 6% magnetic field...
A critical exponent for shortest-path scaling in continuum percolation
Kroese, Dirk P.
A critical exponent for shortest-path scaling in continuum percolation Tim Brereton1 , Christian to study the scaling behavior of shortest path lengths in continuum percolation. These studies suggest that the critical exponent governing this scaling is the same for both continuum and lattice percolation. We use
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
Bradonjic, Milan [Los Alamos National Laboratory
2009-01-01T23:59:59.000Z
In this paper we study reputation mechanisms, and show how the notion of reputation can help us in building truthful online auction mechanisms. From the mechanism design prospective, we derive the conditions on and design a truthful online auction mechanism. Moreover, in the case when some agents may lay or cannot have the real knowledge about the other agents reputations, we derive the resolution of the auction, such that the mechanism is truthful. Consequently, we move forward to the optimal one-gambler/one-seller problem, and explain how that problem is refinement of the previously discussed online auction design in the presence of reputation mechanism. In the setting of the optimal one-gambler problem, we naturally rise and solve the specific question: What is an agent's optimal strategy, in order to maximize his revenue? We would like to stress that our analysis goes beyond the scope, which game theory usually discusses under the notion of reputation. We model one-player games, by introducing a new parameter (reputation), which helps us in predicting the agent's behavior, in real-world situations, such as, behavior of a gambler, real-estate dealer, etc.
Villanueva, Joshua; Huang, Qian; Sirbuly, Donald J., E-mail: dsirbuly@ucsd.edu [Department of NanoEngineering, University of California San Diego, La Jolla, California 92093 (United States)
2014-09-14T23:59:59.000Z
Mechanical characterization is important for understanding small-scale systems and developing devices, particularly at the interface of biology, medicine, and nanotechnology. Yet, monitoring sub-surface forces is challenging with current technologies like atomic force microscopes (AFMs) or optical tweezers due to their probe sizes and sophisticated feedback mechanisms. An alternative transducer design relying on the indentation mechanics of a compressible thin polymer would be an ideal system for more compact and versatile probes, facilitating measurements in situ or in vivo. However, application-specific tuning of a polymer's mechanical properties can be burdensome via experimental optimization. Therefore, efficient transducer design requires a fundamental understanding of how synthetic parameters such as the molecular weight and grafting density influence the bulk material properties that determine the force response. In this work, we apply molecular-level polymer scaling laws to a first order elastic foundation model, relating the conformational state of individual polymer chains to the macroscopic compression of thin film systems. A parameter sweep analysis was conducted to observe predicted model trends under various system conditions and to understand how nano-structural elements influence the material stiffness. We validate the model by comparing predicted force profiles to experimental AFM curves for a real polymer system and show that it has reasonable predictive power for initial estimates of the force response, displaying excellent agreement with experimental force curves. We also present an analysis of the force sensitivity of an example transducer system to demonstrate identification of synthetic protocols based on desired mechanical properties. These results highlight the usefulness of this simple model as an aid for the design of a new class of compact and tunable nanomechanical force transducers.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Bouskill, N. J.; Riley, W. J.; Tang, J.
2014-08-18T23:59:59.000Z
Accurate representation of ecosystem processes in land models is crucial for reducing predictive uncertainty in energy and greenhouse gas feedbacks with the atmosphere. Here we describe an observational and modeling meta-analysis approach to benchmark land models, and apply the method to the land model CLM4.5 with two versions of belowground biogeochemistry. We focused our analysis on the above and belowground high-latitude ecosystem responses to warming and nitrogen addition, and identified mechanisms absent, or poorly parameterized in CLM4.5. While the two model versions predicted similar trajectories for soil carbon stocks following both types of perturbation, other variables (e.g., belowground respiration) differedmore »from the observations in both magnitude and direction, indicating the underlying mechanisms are inadequate for representing high-latitude ecosystems. The observational synthesis attribute these differences to missing representations of microbial dynamics, characterization of above and belowground functional processes, and nutrient competition. We use the observational meta-analyses to discuss potential approaches to improving the current models (e.g., the inclusion of dynamic vegetation or different microbial functional guilds), however, we also raise a cautionary note on the selection of data sets and experiments to be included in a meta-analysis. For example, the concentrations of nitrogen applied in the synthesized field experiments (average =72 kg ha-1 yr-1) are many times higher than projected soil nitrogen concentrations (from nitrogen deposition and release during mineralization), which preclude a rigorous evaluation of the model responses to nitrogen perturbation. Overall, we demonstrate here that elucidating ecological mechanisms via meta-analysis can identify deficiencies in both ecosystem models and empirical experiments.« less
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.
MECHANICAL TEST RESULTS ON DIPOLE MODEL C-l 25 mm ALUMINUM COLLARS
Peters, C.
2010-01-01T23:59:59.000Z
RESULTS ON DIPOLE MODEL C-1 25 mm ALUMINUM COLLARS C. PetersRESULTS ON DIPOLE MODEL C-I 25 mm ALUMINUM COLLARS· CraigON DIPOLE MODEL C-I 25 mm ALUMINUM COLLARS Craig Peters
Continuum particle-vibration coupling method in coordinate-space representation for finite nuclei
Kazuhito Mizuyama; Gianluca Colò; Enrico Vigezzi
2012-05-04T23:59:59.000Z
In this paper we present a new formalism to implement the nuclear particle-vibration coupling (PVC) model. The key issue is the proper treatment of the continuum, that is allowed by the coordinate space representation. Our formalism, based on the use of zero-range interactions like the Skyrme forces, is microscopic and fully self-consistent. We apply it to the case of neutron single-particle states in $^{40}$Ca, $^{208}$Pb and $^{24}$O. The first two cases are meant to illustrate the comparison with the usual (i.e., discrete) PVC model. However, we stress that the present approach allows to calculate properly the effect of PVC on resonant states. We compare our results with those from experiments in which the particle transfer in the continuum region has been attempted. The latter case, namely $^{24}$O, is chosen as an example of a weakly-bound system. Such a nucleus, being double-magic and not displaying collective low-lying vibrational excitations, is characterized by quite pure neutron single-particle states around the Fermi surface.
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.
Continuum extrapolation of energies of a four-quark system in lattice gauge theory
Petrus Pennanen
1997-01-12T23:59:59.000Z
A continuum extrapolation of static two- and four-quark energies calculated in quenched SU(2) lattice Monte Carlo is carried out based on Sommer's method of setting the scale. The beta-function is obtained as a side product of the extrapolations. Four-quark binding energies are found to be essentially constant at beta >= 2.35 unlike the two-body potentials. A model for four-quark energies, with explicit gluonic degrees of freedom removed, is fitted to these energies and the behaviour of the parameters of the model is investigated. An extension of the model using the first excited states of the two-body gluon field as additional basis states is found to be necessary for quarks at the corners of regular tetrahedra.
Characterization and Modeling of Chemical-Mechanical Polishing for Polysilicon Microstructures
Tang, Brian D.
Long the dominant method of wafer planarization in the integrated circuit (IC) industry, chemical-mechanical polishing is starting to play an important role in microelectromechnical systems (MEMS). We present an experiment ...
3D Modeling of Coupled Rock Deformation and Thermo-Poro-Mechanical Processes in Fractures
Rawal, Chakra
2012-07-16T23:59:59.000Z
Problems involving coupled thermo-poro-chemo-mechanical processes are of great importance in geothermal and petroleum reservoir systems. In particular, economic power production from enhanced geothermal systems, effective water-flooding of petroleum...
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...
Lu, Yihong C. S
2010-01-01T23:59:59.000Z
Osteoarthritis (OA) is the most common form of joint disorder. Individuals who have sustained an acute traumatic joint injury are at greater risk for the development of OA. The mechanisms by which injury causes cartilage ...
Mechanism-based constitutive modeling of L1? single-crystal plasticity
Yin, Yuan, 1977-
2006-01-01T23:59:59.000Z
Ni3Al, an L12 structure intermetallic crystal, is the basic composition of the [gamma]' precipitates in nickel-based superalloys and is a major strengthening mechanism contributing to the superalloys' outstanding ...
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.
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 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 ...
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 ...
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.
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...
LBNL-XXXXX | Logue et al., Evaluation of an Incremental Ventilation Energy Model for Estimating Impacts of Air Sealing and Mechanical Ventilation 1 Evaluation of an Incremental Ventilation Energy Model for Estimating Impacts of Air Sealing and Mechanical Ventilation Jennifer M. Logue, William J. N
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
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
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
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.
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
Thomas, Brian G.
the flow-rate and solidification time histories. An efficient one-dimensional (1-D) heat transfer model
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.
Improved microscopic-macroscopic approach incorporating the effects of continuum states
Tajima, Naoki; Takahara, Satoshi
2010-01-01T23:59:59.000Z
The Woods-Saxon-Strutinsky method (the microscopic-macroscopic method) combined with Kruppa's prescription for positive energy levels, which is necessary to treat neutron rich nuclei, is studied to clarify the reason for its success and to propose improvements for its shortcomings. The reason why the plateau condition is met for the Nilsson model but not for the Woods-Saxon model is understood in a new interpretation of the Strutinsky smoothing procedure as a low-pass filter. Essential features of Kruppa's level density is extracted in terms of the Thomas-Fermi approximation modified to describe spectra obtained from diagonalization in truncated oscillator bases. A method is proposed which weakens the dependence on the smoothing width by applying the Strutinsky smoothing only to the deviations from a reference level density. The BCS equations are modified for the Kruppa's spectrum, which is necessary to treat the pairing correlation properly in the presence of continuum. The potential depth is adjusted for th...
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.
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
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.
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...
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
Andersohn, Alexander
2013-08-27T23:59:59.000Z
-suited for multiscale modeling, I came across the term representative volume element (or RVE) used commonly in biomaterials. Not finding a definition for the mesoscale well-suited for the aim of multiscale modeling, an alternative definition was provided herein... are similar, there are some clear differences. The differences outlined in this section are evidence that a new definition for the mesoscale, tailored for multiscale modeling, was needed. Some elements of the RVE, which is mostly used in biomaterials...
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.
Mechanical & Aerospace Engineering
Mechanical & Aerospace Engineering With the increases in computational power and numerical methods a series of research challenges. These challenges involve many branches of mechanical engineering: mechanics, dynamics, tribology, statistical modeling, experimentation, and numerical methods. During
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...
Assessing continuum postulates in simulations of granular flow
Rycroft, Chris
2009-01-01T23:59:59.000Z
Prager, D. C. Drucker, Soil mechanics and plastic analysisWroth, Critical State Soil Mechanics, McGraw-Hill, 1968. L.In Critical State Soil Mechanics (CSSM) (59), an initially
Binding energy and mechanical stability of single- and multi-walled carbon nanotube serpentines
Zhao, Junhua, E-mail: junhua.zhao@163.com, E-mail: timon.rabczuk@uni-weimar.de [Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology, Jiangnan University, 214122 Wuxi (China); Institute of Structural Mechanics, Bauhaus University, 99423 Weimar (Germany); Lu, Lixin [Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology, Jiangnan University, 214122 Wuxi (China); Rabczuk, Timon, E-mail: junhua.zhao@163.com, E-mail: timon.rabczuk@uni-weimar.de [Institute of Structural Mechanics, Bauhaus University, 99423 Weimar (Germany)
2014-05-28T23:59:59.000Z
Recently, Geblinger et al. [Nat. Nanotechnol. 3, 195 (2008)] and Machado et al. [Phys. Rev. Lett. 110, 105502 (2013)] reported the experimental and molecular dynamics realization of S-like shaped single-walled carbon nanotubes (CNTs), the so-called CNT serpentines. We reported here results from continuum modeling of the binding energy ? between different single- and multi-walled CNT serpentines and substrates as well as the mechanical stability of the CNT serpentine formation. The critical length for the mechanical stability and adhesion of different CNT serpentines are determined in dependence of E{sub i}I{sub i}, d, and ?, where E{sub i}I{sub i} and d are the CNT bending stiffness and distance of the CNT translation period. Our continuum model is validated by comparing its solution to full-atom molecular dynamics calculations. The derived analytical solutions are of great importance for understanding the interaction mechanism between different single- and multi-walled CNT serpentines and substrates.
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
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
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.
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.
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.
Zakhor, Avideh
for Mechatronic Systems" Klaus Janschek Technische Universität Dresden, Germany ABSTRACT Mechatronic systems. This makes mechatronic systems increasingly highly critical subject to failures at different technological such as "systems" (in particular mechatronic systems), "models", "design" and "dependability" with special focus
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...
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
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.
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...
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.
Xie, S; Boyle, J S; Cederwall, R T; Potter, G L; Zhang, M; Lin, W
2004-02-19T23:59:59.000Z
This study implements a revised convective triggering condition in the National Center for Atmospheric Research (NCAR) Community Atmosphere Model (CAM2) model to reduce its excessive warm season daytime precipitation over land. The new triggering mechanism introduces a simple dynamic constraint on the initiation of convection that emulates the collective effects of lower level moistening and upward motion of the large-scale circulation. It requires a positive contribution from the large-scale advection of temperature and moisture to the existing positive Convective Available Potential Energy (CAPE) for model convection to start. In contrast, the original convection triggering function in CAM2 assumes that convection is triggered whenever there is positive CAPE, which results in too frequent warm season convection over land arising from strong diurnal variation of solar radiation. We examine the impact of the new trigger on CAM2 simulations by running the climate model in Numerical Weather Prediction (NWP) mode so that more available observations and high-frequency NWP analysis data can be used to evaluate model performance. We show that the modified triggering mechanism has led to considerable improvements in the simulation of precipitation, temperature, moisture, clouds, radiations, surface temperature, and surface sensible and latent heat fluxes when compared to the data collected from the Atmospheric Radiation Measurement (ARM) program at its South Great Plains (SGP) site. Similar improvements are also seen over other parts of the globe. In particular, the surface precipitation simulation has been significantly improved over both the continental United States and around the globe; the overestimation of high clouds in the equatorial tropics has been substantially reduced; and the temperature, moisture, and zonal wind are more realistically simulated. Results from this study also show that some systematic errors in the CAM2 climate simulations can be detected in the early stage of model integration. Examples are the extremely overestimated high clouds in the tropics in the vicinity of ITCZ and the spurious precipitation maximum in the east of the Rockies. This has important implications in studies of these model errors since running the climate model in NWP mode allows us to perform a more in-depth analysis during a short time period where more observations are available and different model errors from various processes have not compensated for the systematic errors.
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.
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
SEACAS Theory Manuals: Part III. Finite Element Analysis in Nonlinear Solid Mechanics
Laursen, T.A.; Attaway, S.W.; Zadoks, R.I.
1999-03-01T23:59:59.000Z
This report outlines the application of finite element methodology to large deformation solid mechanics problems, detailing also some of the key technological issues that effective finite element formulations must address. The presentation is organized into three major portions: first, a discussion of finite element discretization from the global point of view, emphasizing the relationship between a virtual work principle and the associated fully discrete system, second, a discussion of finite element technology, emphasizing the important theoretical and practical features associated with an individual finite element; and third, detailed description of specific elements that enjoy widespread use, providing some examples of the theoretical ideas already described. Descriptions of problem formulation in nonlinear solid mechanics, nonlinear continuum mechanics, and constitutive modeling are given in three companion reports.
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.
Evans, James W. [Ames Laboratory; Liu, Da-Jiang [Ames Laboratory
2014-05-20T23:59:59.000Z
We develop statistical mechanical models amenable to analytic treatment for the dissociative adsorption of O2 at hollow sites on fcc(100) metal surfaces. The models incorporate exclusion of nearest-neighbor pairs of adsorbed O. However, corresponding simple site-blocking models, where adsorption requires a large ensemble of available sites, exhibit an anomalously fast initial decrease in sticking. Thus, in addition to blocking, our models also incorporate more facile adsorption via orientational steering and funneling dynamics (features supported by ab initio Molecular Dynamics studies). Behavior for equilibrated adlayers is distinct from those with finite adspecies mobility. We focus on the low-temperature limited-mobility regime where analysis of the associated master equations readily produces exact results for both short- and long-time behavior. Kinetic Monte Carlo simulation is also utilized to provide a more complete picture of behavior. These models capture both the initial decrease and the saturation of the experimentally observed sticking versus coverage, as well as features of non-equilibrium adlayer ordering as assessed by surface-sensitive diffraction.
Evans, James W. [Ames Laboratory – USDOE, Iowa State University, Ames, Iowa 50011 (United States) [Ames Laboratory – USDOE, Iowa State University, Ames, Iowa 50011 (United States); Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States); Liu, Da-Jiang [Ames Laboratory – USDOE, Iowa State University, Ames, Iowa 50011 (United States)] [Ames Laboratory – USDOE, Iowa State University, Ames, Iowa 50011 (United States)
2014-05-21T23:59:59.000Z
We develop statistical mechanical models amenable to analytic treatment for the dissociative adsorption of O{sub 2} at hollow sites on fcc(100) metal surfaces. The models incorporate exclusion of nearest-neighbor pairs of adsorbed O. However, corresponding simple site-blocking models, where adsorption requires a large ensemble of available sites, exhibit an anomalously fast initial decrease in sticking. Thus, in addition to blocking, our models also incorporate more facile adsorption via orientational steering and funneling dynamics (features supported by ab initio Molecular Dynamics studies). Behavior for equilibrated adlayers is distinct from those with finite adspecies mobility. We focus on the low-temperature limited-mobility regime where analysis of the associated master equations readily produces exact results for both short- and long-time behavior. Kinetic Monte Carlo simulation is also utilized to provide a more complete picture of behavior. These models capture both the initial decrease and the saturation of the experimentally observed sticking versus coverage, as well as features of non-equilibrium adlayer ordering as assessed by surface-sensitive diffraction.
Statistical Mechanics of Two-dimensional Foams: Physical Foundations of the Model
Marc Durand
2015-07-16T23:59:59.000Z
In a recent series of papers [1--3], a statistical model that accounts for correlations between topological and geometrical properties of a two-dimensional shuffled foam has been proposed and compared with experimental and numerical data. Here, the various assumptions on which the model is based are exposed and justified: the equiprobability hypothesis of the foam configurations is argued. The range of correlations between bubbles is discussed, and the mean field approximation that is used in the model is detailed. The two self-consistency equations associated with this mean field description can be interpreted as the conservation laws of number of sides and bubble curvature, respectively. Finally, the use of a "Grand-Canonical" description, in which the foam constitutes a reservoir of sides and curvature, is justified.
The Master of Science in Mechanical Engineering -Non-Thesis Program Planning Sheet
Lin, Xi
in Materials Sci. ME 515* Vibration of Complex Mechanical Systems ME 521* Continuum Mechanics ME 524* SkeletalThe Master of Science in Mechanical Engineering - Non-Thesis Program Planning Sheet Student Name Master of Science in Mechanical Engineering Curricular Requirements The program requires 32 credit hours
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.
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.
A quantum mechanical model for the relationship between stock price and stock ownership
Cotfas, Liviu-Adrian [Faculty of Economic Cybernetics, Statistics and Informatics, Academy of Economic Studies, 6 Piata Romana, 010374 Bucharest (Romania)
2012-11-01T23:59:59.000Z
The trade of a fixed stock can be regarded as the basic process that measures its momentary price. The stock price is exactly known only at the time of sale when the stock is between traders, that is, only in the case when the owner is unknown. We show that the stock price can be better described by a function indicating at any moment of time the probabilities for the possible values of price if a transaction takes place. This more general description contains partial information on the stock price, but it also contains partial information on the stock owner. By following the analogy with quantum mechanics, we assume that the time evolution of the function describing the stock price can be described by a Schroedinger type equation.
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.
Mechanism of bistability: Tonic spiking and bursting in a neuron model Andrey Shilnikov*
Calabrese, Ronald
. The methods of qualitative theory of slow-fast sys- tems applied to biophysically realistic neuron models can Neurons are observed in one of three fundamental, gener- ally defined modes: silence, tonic spiking formation 3,4 . Neurons in bursting mode differ in their ability to transmit information and respond
Clapham, Lynann
The Magnetic Flux Leakage (MFL) inspection method is the most cost effective technique for detecting corrosion and metal loss in in-service pipelines. The principle of the technique is relatively straightforward) has become a powerful modeling tool for studying MFL signals from corrosion defects [1
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.
Continuum Mechanics and Thermodynamics manuscript No. (will be inserted by the editor)
Spiga, Giampiero
by the RankineHugoniot conditions, the re- actions proceed until chemical equilibrium is reached. Physical of these kinds of chemical reactions [4,5]. The paper is organized as follows. In Sect. 2 we present a general
Prediction of Damage Zone Growth in Composites Using Continuum Damage Mechanics
McLendon, Wesley R.
2010-07-14T23:59:59.000Z
individuals who have worked before and beside me developing the framework on which this re- search was conducted, and friends who have supported me through my graduate studies. I am grateful to Larissa Gorbatikh, whom I have not met, but to whom I an indebted...
Time-dependent quantum mechanical study of molecular oxygen in the Schumann-Runge continuum
Balakrishnan, N.; Jamieson, M.J.
Balakrishnan,N. Jamieson,M.J. Dalgarno,A. Li,Y. Buenker,R.J. Journal of Chemical Physics, Vol. 112 pp 1255-1259
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
? current changes. In order to maintain a certain constant current, the tip is raised and lowered accordingly, and this movement pattern is magnified and displayed on screen. Both AFM and STM can be used to get detailed images of nanomaterials and determine...
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 ...
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
2015-07-13T23:59:59.000Z
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
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.
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
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.
Ozcelik, Ozgur
2008-01-01T23:59:59.000Z
17th ASCE Engineering Mechanics Conference , Newark, U.S.A,Journal of Engineering Mechanics, ASCE , 129(12). Thoen, B.Journal of Engineering Mechanics , 129(12), 2003. Van Den
BRANNON,REBECCA M.
2000-11-01T23:59:59.000Z
A theory is developed for the response of moderately porous solids (no more than {approximately}20% void space) to high-strain-rate deformations. The model is consistent because each feature is incorporated in a manner that is mathematically compatible with the other features. Unlike simple p-{alpha} models, the onset of pore collapse depends on the amount of shear present. The user-specifiable yield function depends on pressure, effective shear stress, and porosity. The elastic part of the strain rate is linearly related to the stress rate, with nonlinear corrections from changes in the elastic moduli due to pore collapse. Plastically incompressible flow of the matrix material allows pore collapse and an associated macroscopic plastic volume change. The plastic strain rate due to pore collapse/growth is taken normal to the yield surface. If phase transformation and/or pore nucleation are simultaneously occurring, the inelastic strain rate will be non-normal to the yield surface. To permit hardening, the yield stress of matrix material is treated as an internal state variable. Changes in porosity and matrix yield stress naturally cause the yield surface to evolve. The stress, porosity, and all other state variables vary in a consistent manner so that the stress remains on the yield surface throughout any quasistatic interval of plastic deformation. Dynamic loading allows the stress to exceed the yield surface via an overstress ordinary differential equation that is solved in closed form for better numerical accuracy. The part of the stress rate that causes no plastic work (i.e-, the part that has a zero inner product with the stress deviator and the identity tensor) is given by the projection of the elastic stressrate orthogonal to the span of the stress deviator and the identity tensor.The model, which has been numerically implemented in MIG format, has been exercised under a wide array of extremal loading and unloading paths. As will be discussed in a companion sequel report, the CKP model is capable of closely matching plate impact measurements for porous materials.
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...
Probing the quantum phase transition in the Dicke model through mechanical vibrations
J. P. Santos; K. Furuya; F. L. Semião
2011-03-04T23:59:59.000Z
This paper is concerned with quantum dynamics of a system coupled to a critical reservoir. In this context, we employ the Dicke model which is known to exhibit a super radiant quantum phase transition (QPT) and we allow one of the mirrors to move under a linear restoring force. The electromagnetic field couples to the movable mirror though radiation pressure just like in typical optomechanical setups. We show that, in the thermodynamical limit, the super-radiant phase induces a classical driving force on the mirror without causing decoherence.
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.
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.
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.
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.
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.
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.
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.
Is the Higgs Mechanism of Fermion Mass Generation a Fact? A Yukawa-less First-Two-Generation Model
Diptimoy Ghosh; Rick Sandeepan Gupta; Gilad Perez
2015-08-06T23:59:59.000Z
It is now established that the major source of electroweak symmetry breaking (EWSB) is due to the observed Higgs particle. However, whether the Higgs mechanism is responsible for the generation of all the fermion masses, in particular, the fermions of the first two generations, is an open question. In this letter we present a construction where the light fermion masses are generated through a secondary, subdominant and sequestered source of EWSB. This fits well with the approximate U(2) global symmetry of the observed structure of the flavor sector. We first realize the above idea using a calculable two Higgs doublet model. We then show that the first two generation masses could come from technicolor dynamics, while the third generation fermions, as well as the electroweak gauge bosons get their masses dominantly from the Higgs mechanism. We also discuss how the small CKM mixing between the first two generations and the third generation, and soft mixing between the sequestered EWSB components arise in this setup. A typical prediction of this scenario is a significant reduction of the couplings of the observed Higgs boson to the first two generation of fermions.
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.
Mechanical Properties and Plasticity of a Model Glass Loaded Under Stress Control
Vladimir Dailidonis; Valery Ilyin; Pankaj Mishra; Itamar Procaccia
2014-06-09T23:59:59.000Z
Much of the progress achieved in understanding plasticity and failure in amorphous solids had been achieved using experiments and simulations in which the materials were loaded using strain control. There is paucity of results under stress control. Here we present a new method that was carefully geared to allow loading under stress control either at $T=0$ or at any other temperature, using Monte-Carlo techniques. The method is applied to a model perfect crystalline solid, to a crystalline solid contaminated with topological defects, and to a generic glass. The highest yield stress belongs to the crystal, the lowest to the crystal with a few defects, with the glass in between. Although the glass is more disordered than the crystal with a few defects, it yields stress is much higher than that of the latter. We explain this fact by considering the actual microscopic interactions that are typical to glass forming materials, pointing out the reasons for the higher cohesive nature of the glass. The main conclusion of this paper is that the instabilities encountered in stress-control condition are the identical saddle-node bifurcation seen in strain-control. Accordingly one can use the latter condition to infer about the former. Finally we discuss temperature effects and comment on the time needed to see a stress controlled material failure.
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.
Mechanical & Aerospace Engineering
Mechanical & Aerospace Engineering Bone is a biological material with excellent material properties the properties at lower level serve as inputs for modeling at the next structural level. Mechanical properties and applied mechanics at Northwestern University. Prior to joining the faculty of mechanical engineering
Mechanical & Aerospace Engineering
Mechanical & Aerospace Engineering An integrated fatigue damage diagnosis and prognosis framework time scale model is introduced and used as the mechanism model to predict the crack propagation is Mechanical Engineering. He received his Bachelor's degree in civil and environmental engineering at Harbin
of continuum robot that uses a series of concentric, precurved super- elastic tubes (typically made of nitinol
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).
Telleria, Maria J.
We explain 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 joints ...
Liu, H.H.
2012-01-01T23:59:59.000Z
Strength and elasto-plastic properties of non- industrialplastic regimes. The impact of damage on mechanical and hydraulic properties
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.
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-
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.
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
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.
Philippe Laurent; Lev Titarchuk
2006-11-06T23:59:59.000Z
In Paper by Titarchuk & Shrader the general formulation and results for photon reprocessing (downscattering) that included recoil and Comptonization effects due to divergence of the flow were presented. Here we show the Monte Carlo (MC) simulated continuum and line spectra. We also provide an analytical description of the simulated continuum spectra using the diffusion approximation. We have simulated the propagation of monochromatic and continuum photons in a bulk outflow from a compact object. Electron scattering of the photons within the expanding flow leads to a decrease of their energy which is of first order in V/c (where V is the outflow velocity). The downscattering effect of first order in V/c in the diverging flow is explained by semi-analytical calculations and confirmed by MC simulations. We conclude that redshifted lines and downscattering bumps are intrinsic properties of the powerful outflows for which Thomson optical depth is greater than one. We fitted our model line profiles to the observations using four free parameters, \\beta=V/c, optical depth of the wind \\tau, the wind temperature kT_e and the original line photon energy E_0. We show how the primary spectrum emitted close to the black hole is modified by reprocessing in the warm wind. In the framework of the our wind model the fluorescent iron line K_alpha is formed in the partly ionized wind as a result of illumination by central source continuum photons. The demonstrated application of our outflow model to the XMM observations of MCG 6-30-15, and to the ASCA observations of GRO J1655-40, points out a potential powerful spectral diagnostic for probes of the outflow-central object connection in Galactic and extragalactic BH sources.
MECHANICAL ENGINEERING What is Mechanical
MECHANICAL ENGINEERING What is Mechanical Engineering? Mechanical engineering is one of the broadest engineering fields. Mechanical engineers are found in virtually all productive industries, from aircraft and automotive to consumer products and building equipment. In these jobs, mechanical engineers
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
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.
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
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.
A model for the Pockels effect in distorted liquid crystal blue phases
F. Castles
2015-07-29T23:59:59.000Z
Recent experiments have found that a mechanically distorted blue phase can exhibit a primary linear electro-optic (Pockels) effect [F. Castles \\textit{et al}. Nature Mater. \\textbf{13}, 817 (2014)]. Here it is shown that flexoelectricity can account for the experimental results and a model, which is based on continuum theory but takes account of the sub-unit-cell structure, is proposed. The model provides a quantitative description of the effect accurate to the nearest order of magnitude and predicts that the Pockels coefficient(s) in an optimally-distorted blue phase may be two orders of magnitude larger than in lithium niobate.
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.
similar to an elephant trunk or octopus tentacle. Example continuum robots applications include subsea
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.
NREL: Continuum Magazine - Computing Advances Enable More Efficient...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
participating companies navigate the process by analyzing the building design, performing energy modeling, and suggesting design alternatives. But the utility struggled to ensure...
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
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
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 ...
Srinivasa Parthasarathy, Atul
2013-04-30T23:59:59.000Z
tests. Moreover, they develop normal stress differences even in simple shear flows - a characteristic feature of nonlinear viscoelastic behavior. Many researchers have asserted the importance of considering the nonlinearity of the mechanical behavior...
Matheu, David M. (David Michael), 1974-
2003-01-01T23:59:59.000Z
A host of vital, current, and developing technologies, such as pyrolysis, thermal cracking, partial oxidation, and high-efficiency combustion engines, involve complex, gas-phase chemical mechanisms with hundreds of species ...
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.
A. M. Gainutdinov; N. Read; H. Saleur; R. Vasseur
2014-12-15T23:59:59.000Z
The periodic sl(2|1) alternating spin chain encodes (some of) the properties of hulls of percolation clusters, and is described in the continuum limit by a logarithmic conformal field theory (LCFT) at central charge c=0. This theory corresponds to the strong coupling regime of a sigma model on the complex projective superspace $\\mathbb{CP}^{1|1} = \\mathrm{U}(2|1) / (\\mathrm{U}(1) \\times \\mathrm{U}(1|1))$, and the spectrum of critical exponents can be obtained exactly. In this paper we push the analysis further, and determine the main representation theoretic (logarithmic) features of this continuum limit by extending to the periodic case the approach of [N. Read and H. Saleur, Nucl. Phys. B 777 316 (2007)]. We first focus on determining the representation theory of the finite size spin chain with respect to the algebra of local energy densities provided by a representation of the affine Temperley-Lieb algebra at fugacity one. We then analyze how these algebraic properties carry over to the continuum limit to deduce the structure of the space of states as a representation over the product of left and right Virasoro algebras. Our main result is the full structure of the vacuum module of the theory, which exhibits Jordan cells of arbitrary rank for the Hamiltonian.
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
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...
Christov, C. I. [Dept. of Mathematics, University of Louisiana at Lafayette, LA 70504-1010 (United States)
2010-12-22T23:59:59.000Z
A transversely isotropic elastic continuum is considered in four dimensions, three of which are isotropic, and the properties of the material change only related to the fourth dimension. The model employs two dilational and three shear Lame coefficients. The isotropic dilational coefficient is assumed to be much larger than the second dilational coefficient, and the three shear coefficients. This amounts to a material that is virtually incompressible in the three isotropic dimensions. The first and third shear coefficients are positive, while the second shear coefficient is assumed to be negative. As a result, in the equations of elastic equilibrium, the second derivatives of the displacement with respect to the fourth coordinate enter with negative sign. This makes the equations hyperbolic, with a fourth dimension opposing to the other three. The hyperbolic nature of the fourth dimension allows to be interpreted as time.
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.
A SUZAKU DISCOVERY OF A SLOWLY VARYING HARD X-RAY CONTINUUM FROM THE TYPE I SEYFERT GALAXY NGC 3516
Noda, Hirofumi [Department of Astronomy, School of Science, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Makishima, Kazuo; Nakazawa, Kazuhiro [Department of Physics, School of Science, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Yamada, Shin'ya [Cosmic Radiation Laboratory, Institute of Physical and Chemical Research (RIKEN), Wako, Saitama 351-0198 (Japan)
2013-07-10T23:59:59.000Z
The bright type I Seyfert galaxy NGC 3516 was observed by Suzaku twice, in 2005 October 12-15 and 2009 October 28-November 2, for a gross time coverage of 242 and 544 ks and a net exposure of 134 and 255 ks, respectively. The 2-10 keV luminosity was 2.8 Multiplication-Sign 10{sup 41} erg s{sup -1} in 2005 and 1.6 Multiplication-Sign 10{sup 41} erg s{sup -1} in 2009. The 1.4-1.7 keV and 1.7-10 keV count rates both exhibited peak-to-peak variations of a factor of {approx}2 in 2005 and {approx}4 in 2009. In both observations, the 15-45 keV count rate was less variable. The 2-10 keV spectrum in 2005 was significantly more convex than that in 2009. Through a count-count plot technique, the 2-45 keV signals in both sets of data were successfully decomposed in a model-independent way into two distinct broadband components. One is a variable emission with a featureless spectral shape, and the other is a non-varying hard component accompanied by a prominent Fe-K emission line at 6.33 keV (6.40 keV in the rest frame). The former was successfully fitted by an absorbed power-law model, while the latter requires a new hard continuum in addition to a reflection component from distant materials. The spectral and variability differences between the two observations are mainly attributed to long-term changes of this new hard continuum, which was stable on timescales of several hundreds of kiloseconds.
Detlef Duerr; Sheldon Goldstein; Roderich Tumulka; Nino Zanghi
2009-03-15T23:59:59.000Z
Bohmian mechanics is a theory about point particles moving along trajectories. It has the property that in a world governed by Bohmian mechanics, observers see the same statistics for experimental results as predicted by quantum mechanics. Bohmian mechanics thus provides an explanation of quantum mechanics. Moreover, the Bohmian trajectories are defined in a non-conspiratorial way by a few simple laws.
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 ...
Berdichevsky, Victor
Differentiate. Mechanical Engineering Technology The Division.et.eng.wayne.edu Division of Engineering Technology Bachelors of Science in Mechanical Engineering Technology Get ready for a dynamic career in Mechanical Engineering Technology
Dynamic soil-structure interaction-comparison of FEM model with experimental results
Srinivasan, Palanivel Rajan
2000-01-01T23:59:59.000Z
Linearly elastic finite element models are developed for particular scale-model gravity retaining wall structures. The sand is modeled as a homogenous isotropic linearly elastic continuum. Models are created in four ...
Thomas, Brian G.
of Mechanical and Industrial Engineering University of Illinois at Urbana-Champaign Urbana, Illinois 61801, USA heat transfer, fluid flow and initial solidification in the meniscus region. The oscillation, when the mold moves downward faster than the casting speed. Oscillation also pumps molten flux
Intrinsic dissipation in a nano-mechanical resonator
Kunal, K.; Aluru, N. R., E-mail: aluru@illinois.edu [Department of Mechanical Science and Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)
2014-09-07T23:59:59.000Z
We investigate the effect of size on intrinsic dissipation in nano-structures. We use molecular dynamics simulation and study dissipation under two different modes of deformation: stretching and bending mode. In the case of stretching deformation (with uniform strain field), dissipation takes place due to Akhiezer mechanism. For bending deformation, in addition to the Akhiezer mechanism, the spatial temperature gradient also plays a role in the process of entropy generation. Interestingly, we find that the bending modes have a higher Q factor in comparison with the stretching deformation (under the same frequency of operation). Furthermore, with the decrease in size, the difference in Q factor between the bending and stretching deformation becomes more pronounced. The lower dissipation for the case of bending deformation is explained to be due to the surface scattering of phonons. A simple model, for phonon dynamics under an oscillating strain field, is considered to explain the observed variation in dissipation rate. We also studied the scaling of Q factor with initial tension, in a beam under flexure. We develop a continuum theory to explain the observed results.
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.
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.
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.
Generation of intense continuum extreme-ultraviolet radiation by many-cycle
Loss, Daniel
LETTERS Generation of intense continuum extreme-ultraviolet radiation by many-cycle laser fields P in ultrashort pulse engineering have recently led to the breakthroughs of the generation of attosecond (10-18 s) pulse trains17 and isolated pulses811 . Although trains of multiple pulses can be generated through
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
None
2014-10-01T23:59:59.000Z
This issue of Continuum highlights the many ways NREL partners with private industry and other research institutions. You will find references to many of the partnerships and examples of the scope of our engagement with industry leaders, government organizations, and startups.
Continuum charged D* spin alignment at s?=10.5GeV
Ammar, Raymond G.; Baringer, Philip S.; Bean, Alice; Besson, David Zeke; Coppage, Don; Darling, C.; Davis, Robin E. P.; Kotov, S.; Kravchenko, I.; Kwak, Nowhan; Zhou, L.
1998-07-29T23:59:59.000Z
A measurement of the spin alignment of charged D* mesons produced in continuum e+e-?cc¯ events at s?=10.5GeV is presented. This study using 4.72fb(-1) of CLEO II data shows that there is little evidence of any D* spin alignment.
On the Role of Continuum Structural Topology Optimization in Concept Design of Civil Structures
Swan Jr., Colby Corson
1 On the Role of Continuum Structural Topology Optimization in Concept Design of Civil Structures Center for Computer-Aided Design The University of Iowa Iowa City, Iowa 2001 Structures Congress · Structural domain is discretized into a mesh of volume/area elements. · A solid volume-fraction design
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.
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
Alfven Continuum and Alfven Eigenmodes in the National Compact Stellarator Experiment
Fesenyuk, O. P.; Kolesnichenko, Ya. I.; Lutsenko, V. V.; White, R. B.; Yakovenko, Yu. V.
2004-09-17T23:59:59.000Z
The Alfven continuum (AC) in the National Compact Stellarator Experiment (NCSX) is investigated with the AC code COBRA. The resonant interaction of Alfven eigenmodes and the fast ions produced by neutral beam injection is analyzed. Alfven eigenmodes residing in one of the widest gaps of the NCSX AC, the ellipticity-induced gap, are studied with the code BOA-E.
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
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.
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.
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).
Odegard, Gregory M.
2010-01-01T23:59:59.000Z
of Electrostrictive Polymers using a Hyperelasticity-Based Approach A.W. Richards and G.M. Odegard1 Department-based and polymer-based electroactive materials, a fully-characterized model has not yet been developed to predict the response of transversely-isotropic polymer electrostrictives. A constitutive model is developed within
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.
Mechanical & Aerospace Engineering
Mechanical & Aerospace Engineering Mutliphaseflows of the form of fuel sprays and thin films play) two-phase flows with emphasis on sprays and thin films, (iii) fluid mechanics with emphasis and evaporation and the objective is to obtain predictive models that are able to reproduce both dynamic
Mechanical Systems Signal Processing
Ray, Asok
Mechanical Systems and Signal Processing Mechanical Systems and Signal Processing 21 (2007) 866 and analytical models. This paper attempts to address this inadequacy by taking advantage of advanced signal processing and pattern recognition tools. Since a vast majority of structural components that are prone
Mechanical Engineering 1 Mechanical Engineering
Haller, Gary L.
Mechanical Engineering 1 Mechanical Engineering Director of undergraduate studies: Corey O'Hern, M203 ML, 432-4258, corey.ohern@yale.edu; seas.yale.edu/departments/mechanical- engineering-and-materials-science FACULTY OF THE DEPARTMENT OF MECHANICAL ENGINEERING AND MATERIALS SCIENCE Professors Charles Ahn, Ira
Bohmian mechanics contradicts quantum mechanics
Neumaier, Arnold
Bohmian mechanics contradicts quantum mechanics Arnold Neumaier Institut fur Mathematik, Universit://solon.cma.univie.ac.at/#24;neum/ Abstract. It is shown that, for a harmonic oscillator in the ground state, Bohmian mechanics and quantum mechanics predict values of opposite sign for certain time correlations. The discrepancy can
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 ...
Viscoelastic{Viscoplastic Damage Model for Asphalt Concrete
Graham, Michael A.
2010-10-12T23:59:59.000Z
in experiments, and their model was limited to uniaxial loading. Chehab et al. (2003) developed a continuum viscoelastoplastic model for undamaged asphalt concrete, but its scope was also limited to uniaxial characterization. Uzan (2005) developed a damaged...
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.
STRUCTURAL ENGINEERING, MECHANICS AND MATERIALS
Wang, Yuhang
· Structural Health Monitoring · Structural Reliability Graduate Studies Structural Engineering, Mechanics sensing device for structural health monitoring and control. 3D finite element modeling and simulationSTRUCTURAL ENGINEERING, MECHANICS AND MATERIALS offers graduate instruction and research
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.
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
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.
Fry, R.J.M.
1984-01-01T23:59:59.000Z
The point at which the common final pathway for induction of cancer by chemical carcinogens and ionizing radiation has not been identified. Although common molecular targets are suggested by recent findings about the role of oncogenes, the mechanism by which the deposition of radiation energy and the formation of adducts or other DNA lesions induced by chemicals affects the changes in the relevant targets may be quite different. The damage to DNA that plays no part in the transformation events, but that influences the stability of the genome, and therefore, the probability of subsequent changes that influence tumorigenesis may be more readily induced by some agents than others. Similarly, the degree of cytotoxic effects that disrupt tissue integrity and increase the probability of expression of initiated cells may be dependent on the type of carcinogen. Also, evidence was presented that repair of the initial lesions could be demonstrated after exposure to low-LET radiation but not after exposure to chemical carcinogens.