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
Introduction to continuum mechanics for engineers
Bowen, Ray M.
1989-01-01
This textbook is intended to introduce engineering graduate students to the essentials of modern Continuum Mechanics. The objective of an introductory course is to establish certain classical continuum models within a modern framework. Engineering...
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)
2014-05-07
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
SEACAS Theory Manuals: Part II. Nonlinear Continuum Mechanics
Attaway, S.W.; Laursen, T.A.; Zadoks, R.I.
1998-09-01
This report summarizes the key continuum mechanics concepts required for the systematic prescription and numerical solution of finite deformation solid mechanics problems. Topics surveyed include measures of deformation appropriate for media undergoing large deformations, stress measures appropriate for such problems, balance laws and their role in nonlinear continuum mechanics, the role of frame indifference in description of large deformation response, and the extension of these theories to encompass two dimensional idealizations, structural idealizations, and rigid body behavior. There are three companion reports that describe the problem formulation, constitutive modeling, and finite element technology for nonlinear continuum mechanics systems.
Polymer Quantum Mechanics and its Continuum Limit
Alejandro Corichi; Tatjana Vukasinac; Jose A. Zapata
2007-08-22
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
2013-12-09
The presence and flow of moisture degrade engineering properties of asphalt concrete as part of thermodynamic, chemical, physical, and mechanical processes. This detrimental effect is referred to as moisture damage. The aim of this dissertation...
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
Equivalent Continuum Modeling for Shock Wave Propagation in Jointed...
Office of Scientific and Technical Information (OSTI)
Equivalent Continuum Modeling for Shock Wave Propagation in Jointed Media Citation Details In-Document Search Title: Equivalent Continuum Modeling for Shock Wave Propagation in...
Micro-Continuum Modeling of Nuclear Waste Glass Corrosion
Steefel, Carl
2014-01-01
21. Grambow, B. (2006). Nuclear waste glasses – How durable?Continuum Modeling of Nuclear Waste Glass Corrosion AugustContinuum Modeling of Nuclear Waste Glass Corrosion Prepared
Prediction of Damage Zone Growth in Composites Using Continuum Damage Mechanics
McLendon, Wesley R.
2010-07-14
The continuum damage mechanics (CDM) approach is widely used to model damage in polymer matrix composite materials which are represented using the homogenized properties of the fiber and matrix constituents. CDM simplifies the problem of accounting...
Antieigenvalue Analysis, New Applications: Continuum Mechanics, Economics, Number Theory
Karl Gustafson
2015-04-20
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
2015-02-06
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.
Continuum-based Multiscale Computational Damage Modeling of Cementitous Composites
Kim, Sun-Myung
2011-08-08
, aggregates, and interfacial transition zone (ITZ) and interaction among components at meso-scale, and the interaction between reinforcements, such as fiber and carbon nanotubes (CNTs) and mortar matrix or the ITZ at nano scale in order to predict more... 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...
Continuum-scale Modeling of Hydrogen and Helium Bubble Growth...
Office of Environmental Management (EM)
Continuum-scale Modeling of Hydrogen and Helium Bubble Growth in Metals Continuum-scale Modeling of Hydrogen and Helium Bubble Growth in Metals Presentation from the 34th Tritium...
continuum mechanics inviscid fluids Efficiency of a Wind Turbine
continuum mechanics inviscid fluids Efficiency of a Wind Turbine In this problem, we will determine the maximal possible power that can be extracted from a wind turbine. We imagine the following setup. Consider a tube of cross-sectional area A, with incident gas velocity v. We place some turbine
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
Atomistic to continuum modeling of solidification microstructures
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Karma, Alain; Tourret, Damien
2015-09-26
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
THMC Modeling of EGS Reservoirs ? Continuum through Discontinuum...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
THMC Modeling of EGS Reservoirs Continuum through Discontinuum Representations: Capturing Reservoir Stimulation, Evolution and Induced Seismicity THMC Modeling of EGS Reservoirs...
Nano-Continuum Modeling of a Nuclear Glass Specimen Altered for 25 Years
Steefel, Carl
2014-01-06
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-
2001-01-01
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, ...
Continuum electromechanical modeling of protein-membrane interactions Y. C. Zhou*
Lu, Benzhuo
Continuum electromechanical modeling of protein-membrane interactions Y. C. Zhou* Department; published 28 October 2010 A continuum electromechanical model is proposed to describe the membrane curvature
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
An Atomic Interaction based Continuum Model for Adhesive Contact Roger A. Sauer , Shaofan Li
An Atomic Interaction based Continuum Model for Adhesive Contact Mechanics Roger A. Sauer , Shaofan the adhesive contact between deformable bodies. To model adhesive contact, an interatomic interaction potential of the model with respect to its geometrical size and the strength of adhesion is investigated. The proposed
Comparison of Mesomechanical and Continuum Granular Flow Models for Ceramics
Curran, D. R.
2006-07-28
Constitutive models for the shear strength of ceramics undergoing fracture are needed for modeling long rod and shaped-charge jet penetration events in ceramic armor. The ceramic material ahead of the penetrator has been observed to be finely comminuted material that flows around the nose of the eroding penetrator (Shockey et al.). The most-used continuum models are of the Drucker-Prager type with an upper cutoff, or of the Mohr-Coulomb type with strain rate dependence and strain softening. A disadvantage of such models is that they have an unclear connection to the actual microscopic processes of granular flow and comminution. An alternate approach is to use mesomechanical models that describe the dynamics of the granular flow, as well as containing a description of the granular comminution and resultant material softening. However, a disadvantage of the mesomechanical models is that they are computationally more burdensome to apply. In the present paper, we compare the behaviors of a mesomechanical model, FRAGBED2, with the Walker and Johnson-Holmquist continuum models, where the granular material is subjected to simple strain histories under various confining pressures and strain rates. We conclude that the mesomechanical model can provide valuable input to the continuum models, both in interpretation of the continuum models' parameters and in suggesting their range of applicability.
Coexistence in a two-type continuum growth model
HÃ¤ggstrÃ¶m, Olle
Coexistence in a two-type continuum growth model Maria Deijfen #3; Olle Haggstrom y April 2004 Abstract We consider a stochastic model, describing the growth of two com- peting infections on R d . The growth takes place by way of spherical outbursts in the infected region, an outburst in the type 1 (2
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
LOCALIZATION FOR ONE DIMENSIONAL, CONTINUUM, BERNOULLIANDERSON MODELS
properties of disordered media are the Anderson models, whether one considers their original discrete version on Anderson models require more regularity of the probability distributions governing the coupling constants
Applications of a new theory extending continuum mechanics to the nanoscale
Fu, Kaibin
2005-11-01
In this dissertation, we present the Slattery-Oh-Fu theory extending continuum mechanics to the nanoscale and its applications. We begin with an analysis of supercritical adsorption of argon, krypton, and methane on Graphon before we fully develop...
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
Microstructural viscoplastic continuum model for asphalt concrete
Tashman, Laith
2004-09-30
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.
1992-05-01
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.
Continuum Electromechanical Modeling of Protein-Membrane Interaction
Y. C. Zhou; Benzhuo Lu; Alemayehu A. Gorfe
2010-08-17
A continuum electromechanical model is proposed to describe the membrane curvature induced by electrostatic interactions in a solvated protein-membrane system. The model couples the macroscopic strain energy of membrane and the electrostatic solvation energy of the system, and equilibrium membrane deformation is obtained by minimizing the electro-elastic energy functional with respect to the dielectric interface. The model is illustrated with the systems with increasing geometry complexity and captures the sensitivity of membrane curvature to the permanent and mobile charge distributions.
Continuum Electromechanical Modeling of Protein-Membrane Interaction
Zhou, Y C; Gorfe, Alemayehu A
2010-01-01
A continuum electromechanical model is proposed to describe the membrane curvature induced by electrostatic interactions in a solvated protein-membrane system. The model couples the macroscopic strain energy of membrane and the electrostatic solvation energy of the system, and equilibrium membrane deformation is obtained by minimizing the electro-elastic energy functional with respect to the dielectric interface. The model is illustrated with the systems with increasing geometry complexity and captures the sensitivity of membrane curvature to the permanent and mobile charge distributions.
Relativistic Point Coupling Model for Vibrational Excitations in the Continuum
Ring, P.; Daoutidis, J.; Litvinova, E.; Niksic, T.; Paar, N.; Vretenar, D.
2009-08-26
An implementation of the relativistic random phase approximation with the proper treatment of the continuum has been developed for the relativistic point coupling model and applied to investigate collective excitations in spherical nuclei. The results are compared with the spectral implementation of the same model. In heavy nuclei, where the escape width is negligible, we find an excellent agreement between both methods in the region of giant resonance and some discrepancies in the region of low-lying pygmy resonance. The differences are more pronounced in light nuclei due to the larger values of the escape widths.
Partition functions and the continuum limit in Penner matrix models
Gabriel Álvarez; Luis Martínez Alonso; Elena Medina
2014-07-23
We present an implementation of the method of orthogonal polynomials which is particularly suitable to study the partition functions of Penner random matrix models, to obtain their explicit forms in the exactly solvable cases, and to determine the coefficients of their perturbative expansions in the continuum limit. The method relies on identities satisfied by the resolvent of the Jacobi matrix in the three-term recursion relation of the associated families of orthogonal polynomials. These identities lead to a convenient formulation of the string equations. As an application, we show that in the continuum limit the free energy of certain exactly solvable models like the linear and double Penner models can be written as a sum of gaussian contributions plus linear terms. To illustrate the one-cut case we discuss the linear, double and cubic Penner models, and for the two-cut case we discuss theoretically and numerically the existence of a double-branch structure of the free energy for the gaussian Penner model.
Buckling of microtubules: An insight by molecular and continuum mechanics
Zhang, Jin; Meguid, S. A.
2014-10-27
The molecular structural mechanics method has been extended to investigate the buckling of microtubules (MTs) with various configurations. The results indicate that for relative short MTs the shear deformation effect, rather than the nonlocal effect, is mainly responsible for the limitation of their widely used Euler beam description and the observed length-dependence of their bending stiffness. In addition, the configuration effect of MTs is also studied and considered as an explanation for the large scattering of the critical buckling force and bending stiffness observed in existing experiments. This configuration effect is also found to mainly originate from the geometry of the MTs and is mainly determined by the protofilament number.
Continuum and discrete models for unbalanced woven fabrics
Angela Madeo; Gabriele Barbagallo; Marco Valerio D'Agostino; Philippe Boisse
2015-09-15
The classical models used for describing the behavior of woven fabrics do not fully account for the whole set of phenomena that occur during the testing of such materials. This lack of precision is mainly due to the absence of energy terms related to the microstructural properties of the fabric and, in particular, to the bending stiffness of the yarns. In this paper it is shown that in the unbalanced fabrics the different bending stiffnesses of the warp and weft yarns produce macroscopic effects that are extremely visible as, for example, the asymmetric S-shape during a Bias Extension Test (BET). We propose to introduce a constrained micromorphic model and a discrete model that are able to account for i) the angle variation between warp and weft tows, ii) the unbalance in the bending stiffness of the yarns and iii) the relative slipping of the tows. The constrained micromorphic model is framed in the spirit of the Principle of Virtual Powers for the equilibrium of continuum bodies. A suitable constraint is introduced by means of Lagrange multipliers in the strain energydens ity and the resulting constrained model tends a particular second gradientone. The main advantage of using such constrained micromorphic model is that the kinematical and traction boundary conditions that can be imposed on the boundary of the considered body take a natural and unique meaning. The discrete model is set up by opportunely interconnecting Euler-Bernoulli beams with different bending stiffnesses in the two directions by means of rotational and translational elastic springs. The main advantage of such discrete model is that the slipping of the tows is described in a rather realistic way. Suitable numerical simulations are presented for both the continuum and the discrete models and a comparison between the simulations and the experimental results is made showing a definitely good agreement.
The lipid bilayer at the mesoscale: a physical continuum model
Phillip L. Wilson; Huaxiong Huang; Shu Takagi
2008-02-26
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
2007-09-17
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...
Continuum modeling of diffusion and dispersion in dense granular...
Office of Scientific and Technical Information (OSTI)
Author Affiliations Los Alamos National Laboratory Los Alamos National Laboratory Mechanical & Aerospace Engineering, Princeton University Mechanical & Aerospace Engineering,...
Zapol, Peter; Bourg, Ian; Criscenti, Louise Jacqueline; Steefel, Carl I.; Schultz, Peter Andrew
2011-10-01
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.
2014-12-15
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
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Zhang, Yang; Chong, Edwin K. P.; Hannig, Jan; Estep, Donald
2013-01-01
We introduce a continuum modeling method to approximate a class of large wireless networks by nonlinear partial differential equations (PDEs). This method is based on the convergence of a sequence of underlying Markov chains of the network indexed by N , the number of nodes in the network. As N goes to infinity, the sequence converges to a continuum limit, which is the solution of a certain nonlinear PDE. We first describe PDE models for networks with uniformly located nodes and then generalize to networks with nonuniformly located, andmore »possibly mobile, nodes. Based on the PDE models, we develop a method to control the transmissions in nonuniform networks so that the continuum limit is invariant under perturbations in node locations. This enables the networks to maintain stable global characteristics in the presence of varying node locations. « less
Continuum limits of step ow models 1 Introduction
2015-08-29
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
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
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
On the validity of dielectric continuum models in application to solvation in molecular solvents
Matyushov, Dmitry
On the validity of dielectric continuum models in application to solvation in molecular solvents simulations of solvation of a point dipole in dipolarquadrupolar solvents of varying dipole moment and axial of a monotonic increase of the absolute value of the solvation chemical potential p with the solvent dielectric
Sensitivity of the Properties of Ruthenium “Blue Dimer” to Method, Basis Set, and Continuum Model
Ozkanlar, Abdullah; Clark, Aurora E.
2012-05-23
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.
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
Continuum Cascade Model: Branching Random Walk for Traveling Wave
Yoshiaki Itoh
2015-07-15
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.
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
Puckett, Elbridge Gerry; Miller, Gregory Hale
2012-10-14
Much of the work conducted under the auspices of DE-FG02-03ER25579 was characterized by an exceptionally close collaboration with researchers at the Lawrence Berkeley National Laboratory (LBNL). For example, Andy Nonaka, one of Professor Miller's graduate students in the Department of Applied Science at U. C. Davis (UCD) wrote his PhD thesis in an area of interest to researchers in the Applied Numerical Algorithms Group (ANAG), which is a part of the National Energy Research Supercomputer Center (NERSC) at LBNL. Dr. Nonaka collaborated closely with these researchers and subsequently published the results of this collaboration jointly with them, one article in a peer reviewed journal article and one paper in the proceedings of a conference. Dr. Nonaka is now a research scientist in the Center for Computational Sciences and Engineering (CCSE), which is also part of the National Energy Research Supercomputer Center (NERSC) at LBNL. This collaboration with researchers at LBNL also included having one of Professor Puckett's graduate students in the Graduate Group in Applied Mathematics (GGAM) at UCD, Sarah Williams, spend the summer working with Dr. Ann Almgren, who is a staff scientist in CCSE. As a result of this visit Sarah decided work on a problem suggested by the head of CCSE, Dr. John Bell, for her PhD thesis. Having finished all of the coursework and examinations required for a PhD, Sarah stayed at LBNL to work on her thesis under the guidance of Dr. Bell. Sarah finished her PhD thesis in June of 2007. Writing a PhD thesis while working at one of the University of California (UC) managed DOE laboratories is long established tradition at UC and Professor Puckett has always encouraged his students to consider doing this. Another one of Professor Puckett's graduate students in the GGAM at UCD, Christopher Algieri, was partially supported with funds from DE-FG02-03ER25579 while he wrote his MS thesis in which he analyzed and extended work originally published by Dr. Phillip Colella, the head of ANAG, and some of his colleagues. Chris Algieri is now employed as a staff member in Dr. Bill Collins' Climate Science Department in the Earth Sciences Division at LBNL working with computational models of climate change. Finally, it should be noted that the work conducted by Professor Puckett and his students Sarah Williams and Chris Algieri and described in this final report for DOE grant # DE-FC02-03ER25579 is closely related to work performed by Professor Puckett and his students under the auspices of Professor Puckett's DOE SciDAC grant DE-FC02-01ER25473 An Algorithmic and Software Framework for Applied Partial Differential Equations: A DOE SciDAC Integrated Software Infrastructure Center (ISIC). Dr. Colella was the lead PI for this SciDAC grant, which was comprised of several research groups from DOE national laboratories and five university PI's from five different universities. In theory Professor Puckett tried to use funds from the SciDAC grant to support work directly involved in implementing algorithms developed by members of his research group at UCD as software that might be of use to Puckett's SciDAC CoPIs. (For example, see the work reported in Section 2.2.2 of this final report.) However, since there is considerable lead time spent developing such algorithms before they are ready to become `software' and research plans and goals change as the research progresses, Professor Puckett supported each member of his research group partially with funds from the SciDAC APDEC ISIC DE-FC02-01ER25473 and partially with funds from this DOE MICS grant DE-FC02-03ER25579. This has necessarily resulted in a significant overlap of project areas that were funded by both grants. In particular, both Sarah Williams and Chris Algieri were supported partially with funds from grant # DE-FG02-03ER25579, for which this is the final report, and in part with funds from Professor Puckett's DOE SciDAC grant # DE-FC02-01ER25473. For example, Sarah Williams received support from DE-FC02- 01ER25473 and DE-FC02-03ER25579, both while at UCD taking cla
Zhang, Zhen, E-mail: matzz@nus.edu.sg; Xu, Shixin, E-mail: matxs@nus.edu.sg [Department of Mathematics, National University of Singapore, Singapore 119076 (Singapore); Ren, Weiqing, E-mail: matrw@nus.edu.sg [Department of Mathematics, National University of Singapore, Singapore 119076 (Singapore); Institute of High Performance Computing, Agency for Science, Technology and Research, Singapore 138632 (Singapore)
2014-06-15
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
1998-06-06
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].
High-order continuum kinetic method for modeling plasma dynamics in phase space
Vogman, G. V.; Colella, P.; Shumlak, U.
2014-12-15
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,v_{x},v_{y}) is presented. The benchmark is based on the Dory-Guest-Harris instability and is successfully used to validate a continuum finite volume 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,v_{r},v_{z}) phase space are presented.
Continuum-kinetic-microscopic model of lung clearance due to core-annular fluid entrainment
Mitran, Sorin
2013-07-01
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-
2006-01-01
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
2008-11-11
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
2009-11-07
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
2011-03-06
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.
The pseudo-photosphere model for the continuum emission of gaseous discs
Vieira, Rodrigo G; Bjorkman, Jon E
2015-01-01
We investigate the continuum emission of viscous decretion discs around Be stars in this paper. The results obtained from non-LTE (local thermodynamic equilibrium) radiative transfer models show two regimes in the disc surface brightness profile: an inner optically thick region, which behaves as a pseudo-photosphere with a wavelength-dependent size, and an optically thin tenuous outer part, which contributes with about a third of the total flux. The isophotal shape of the surface brightness is well described by elliptical contours with an axial ratio $b/a=\\cos i$ for inclinations $iemission of gaseous discs. It provides fluxes and spectral slopes at the infrared within an accuracy of $10\\%$ and $5\\%$, respectively, when compared to the numerical results. The model indicates that the infrared spectral slope is mainly determined by both the density radial slope and the disc flaring exponent, being practic...
Mechanism of the Cassie-Wenzel transition via the atomistic and continuum string methods
Alberto Giacomello; Simone Meloni; Marcus Mueller; Carlo Massimo Casciola
2014-11-17
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
On the ability of Order Statistics to distinguish different models for continuum gamma decay
Sandoval, J. J.; Cristancho, F.
2007-10-26
A simulation procedure to calculate some important parameters to the application of Order Statistics in the analysis of continuum gamma decay is presented.
Continuum-kinetic-microscopic model of lung clearance due to core-annular fluid entrainment
Welch, Greg
model of the effect of airflow shear forces, as exerted by tidal breathing and cough, upon clearance]. Upon breakdown of this healthy-state mucociliary transport mechanism, cough can clear mucus from
Elsworth, Derek; Izadi, Ghazal; Gan, Quan; Fang, Yi; Taron, Josh; Sonnenthal, Eric
2015-07-28
This work has investigated the roles of effective stress induced by changes in fluid pressure, temperature and chemistry in contributing to the evolution of permeability and induced seismicity in geothermal reservoirs. This work has developed continuum models [1] to represent the progress or seismicity during both stimulation [2] and production [3]. These methods have been used to resolve anomalous observations of induced seismicity at the Newberry Volcano demonstration project [4] through the application of modeling and experimentation. Later work then focuses on the occurrence of late stage seismicity induced by thermal stresses [5] including the codifying of the timing and severity of such responses [6]. Furthermore, mechanistic linkages between observed seismicity and the evolution of permeability have been developed using data from the Newberry project [7] and benchmarked against field injection experiments. Finally, discontinuum models [8] incorporating the roles of discrete fracture networks have been applied to represent stimulation and then thermal recovery for new arrangements of geothermal wells incorporating the development of flow manifolds [9] in order to increase thermal output and longevity in EGS systems.
M. V. Voinova; M. Rodahl; M. Jonson; B. Kasemo
1998-05-21
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.
2008-01-01
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
A Continuum DamageBreakage Faulting Model and Solid-Granular Transitions VLADIMIR LYAKHOVSKY
Lyakhovsky, Vladimir
and YEHUDA BEN-ZION 2 Abstract--We present a thermodynamically-based formulation for mechanical modeling of a granular phase in a failure slip zone with a breakage parameter. The stressstrain relation and kinetics models. Shear heating during deformation can lead to a secondary finite-width internal localization
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
A continuum model for defect dynamics in metallic glasses Amit Acharya
Acharya, Amit
a fundamental characterization of the process of plastic deformation in a metallic glass, relating its structure and the simplest linear kinetic assumptions arising from enforcing the second law of thermodynamics mechanical model of defect dynamics in metallic glasses that accounts for topological, energetic, and kinetic
STATISTICAL MECHANICS MODELING OF MESOSCALE DEFORMATION IN METALS...
Office of Scientific and Technical Information (OSTI)
and computational modeling of dislocation dynamics of mesoscale deformation of metal single crystals. Specifically, the work aimed to implement a continuum statistical...
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)
1995-12-31
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.
Internal noise driven generalized Langevin equation from a nonlocal continuum model
Saikat Sarkar; Shubhankar Roy Chowdhury; Debasish Roy; Ram Mohan Vasu
2015-03-10
Starting with a micropolar formulation, known to account for nonlocal microstructural effects at the continuum level, a generalized Langevin equation (GLE) for a particle, describing the predominant motion of a localized region through a single displacement degree-of-freedom (DOF), is derived. The GLE features a memory dependent multiplicative or internal noise, which appears upon recognising that the micro-rotation variables possess randomness owing to an uncertainty principle. Unlike its classical version, the new GLE qualitatively reproduces the experimentally measured fluctuations in the steady-state mean square displacement of scattering centers in a polyvinyl alcohol slab. The origin of the fluctuations is traced to nonlocal spatial interactions within the continuum. A constraint equation, similar to a fluctuation dissipation theorem (FDT), is shown to statistically relate the internal noise to the other parameters in the GLE.
Liu, Fang; Kulik, Heather J; Martínez, Todd J
2015-01-01
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
2014-07-31
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.
Mechanical effects in cookoff modeling
Gross, R.J.; Baer, M.R.; Hobbs, M.L.
1994-07-01
Complete cookoff modeling of energetic material in confined geometries must couple thermal, chemical and mechanical effects. In the past, modeling has focused on the prediction of the onset of combustion behavior based only on thermal-chemistry effects with little or no regard to the mechanical behavior of the energetic material. In this paper, an analysis tool is outlined which couples thermal, chemical, and mechanical behavior for one-dimensional Geometries comprised of multi-materials. A reactive heat flow code, XCHEM, and a quasistatic mechanics code, SANTOS, have been completely coupled using, a reactive, elastic-plastic constitutive model describing pressurization of the energetic material. This new Thermally Reactive Elastic-plastic explosive code, TREX, was developed to assess the coupling, of mechanics with thermal chemistry making multidimensional cookoff analysis possible. In this study, TREX is applied to confined and unconfined systems. The confined systems simulate One-Dimensional Time to explosion (ODTX) experiments in both spherical and cylindrical configurations. The spherical ODTX system is a 1.27 cm diameter sphere of TATB confined by aluminum exposed to a constant external temperature. The cylindrical ODTX system is an aluminum tube filled with HMX, NC, and inert exposed to a constant temperature bath. Finally. an unconfined system consisting of a hollow steel cylinder filled with a propellant composed of Al, RMX, and NC, representative of a rocket motor, is considered. This model system is subjected to transient internal and external radiative/convective boundary conditions representative of 5 minutes exposure to a fire. The confined systems show significant pressure prior to ignition, and the unconfined system shows extrusion of the propellent suggesting that the energetic material becomes more shock sensitive.
Goddard, J. D.
2010-01-01
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
2013-05-16
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.
Sparks, Donald L.
GEOC 36 Kinetics and mechanisms of metal sorption at the soil mineral/water interface, Newark, DE 19717-1303 A basic understanding of the kinetics and mechanisms of metal sorption on natural and their occurrence in natural soils. Chemistry of Metals in Terrestrial and Aquatic Systems Division of Geochemistry
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)
2014-05-21
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.
Office of Energy Efficiency and Renewable Energy (EERE)
This research will develop a thorough understanding of complex THMC interactions through synthesis, modeling and verification.
Continuum Limit of a Step Flow Model of Epitaxial Growth R.V. ...
2002-02-08
We inv estigate this boundary condition by numerical simulation of the step flow ... Monte-Carlo or molecular dynamics models, because of their time eÆciency.
Surawatanawong, Panida
2010-07-14
The electronic structures and reaction mechanisms of transition-metal complexes can be calculated accurately by density functional theory (DFT) in cooperation with the continuum solvation model. The palladium catalyzed ...
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 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 ...
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
Qu, Zhisong; Fitzgerald, Michael
2015-01-01
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.
2013-08-28
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.
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
2011-12-10
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.
2008-03-26
This study provides modeling tools for the design of reliable seals for SOFC stacks. The work consists of 1) experimental testing to determine fundamental properties of SOFC sealing materials, and 2) numerical modeling of stacks and sealing systems. The material tests capture relevant temperature-dependent physical and mechanical data needed by the analytical models such as thermal expansion, strength, fracture toughness, and relaxation behavior for glass-ceramic seals and other materials. Testing has been performed on both homogenous specimens and multiple material assemblies to investigate the effect of interfacial reactions. A viscoelastic continuum damage model for a glass-ceramic seal was developed to capture the nonlinear behavior of this material at high temperatures. This model was implemented in the MSC MARC finite element code and was used for a detailed analysis of a planar SOFC stack under thermal cycling conditions. Realistic thermal loads for the stack were obtained using PNNL’s in-house multiphysics solver. The accumulated seal damage and component stresses were evaluated for multiple thermal loading cycles, and regions of high seal damage susceptible to cracking were identified. Selected test results, numerical model development, and analysis results will be presented.
Continuum Radio Emission and Diagnostics
White, Stephen
Continuum Radio Emission and Diagnostics The Sun is a strong radio source (one of the first objects discusses incoher ent emission from thermal plasma in the nonflaring so lar atmosphere; other relevant material may be found in Coherent Plasma Emission and in Solar Flares: Radio Bursts. Emission mechanisms
DENSE MULTIPHASE FLOW SIMULATION: CONTINUUM MODEL FOR POLY-DISPERSED SYSTEMS USING KINETIC THEORY
Moses Bogere
2011-08-31
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.
Rahmani, Eisa
2015-05-01
Oxidative aging is known to be one of the main contributors to reducing the service life of asphalt pavements. Asphalt concrete becomes stiffer and more brittle when it reacts with oxygen. The aged asphalt pavement is more susceptible to crack...
Regulation mechanisms in spatial stochastic development models
Dmitri Finkelshtein; Yuri Kondratiev
2008-09-04
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.
Mechanical & Aerospace Engineering
Mechanical & Aerospace Engineering The miniaturization of structural components to the sub progress in strain-gradient continuum theories to model the mechanical behavior of metallic systems at small length scales, these theories fail to represent the variety of physical mechanisms involved
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; Lewis, Matthew W; Liu, Cheng; Thompson, Darla G
2010-01-01
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.
Modeling-Thermo-electrochemistry, Capacity Degradation and Mechanics...
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Modeling-Thermo-electrochemistry, Capacity Degradation and Mechanics with SEI Layer Modeling-Thermo-electrochemistry, Capacity Degradation and Mechanics with SEI Layer 2011 DOE...
Mechanical Modeling of a WIPP Drum Under Pressure | Department...
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Mechanical Modeling of a WIPP Drum Under Pressure Mechanical Modeling of a WIPP Drum Under Pressure This document was used to determine facts and conditions during the Department...
A Signal Processing Model of Quantum Mechanics
Chris Thron; Johnny Watts
2012-05-08
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.
Ginovska, Bojana; Camaioni, Donald M.; Dupuis, Michel
2008-07-07
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.
Mechanical Model for Relativistic Blast Waves
A. M. Beloborodov; Z. L. Uhm
2006-09-02
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.
Towards a physics-based modelling of the electro-mechanical coupling in EAPs
Noy Cohen; Andreas Menzel; Gal deBotton
2015-02-03
Due to the increasing number of industrial applications of electro-active polymers (EAPs), there is a growing need for electromechanical models which accurately capture their behavior. To this end, we compare the predicted behavior of EAPs undergoing homogenous deformations according to three electromechanical models. The first model is a continuum based model composed of the mechanical Gent model and a linear relationship between the electric field and the polarization. The electrical and the mechanical responses according to the second model are based on the polymer microstructure, whereas the third model incorporates a neo-Hookean mechanical response and a microstructural based long-chains model for the electrical behavior. In the microstructural motivated models the integration from the microscopic to the macroscopic levels is accomplished by the micro-sphere technique. Four types of homogeneous boundary conditions are considered and the behaviors determined according to the three models are compared. The differences between the predictions of the models are discussed, highlighting the need for an in-depth investigation of the relations between the structure and the behaviors of the EAPs at microscopic level and their overall macroscopic response.
Mechanics of hydrogen storage in carbon nanotubes Y.L. Chen a
Jiang, Hanqing
Mechanics of hydrogen storage in carbon nanotubes Y.L. Chen a , B. Liu a,Ã, J. Wu a , Y. Huang b 17 July 2008 Keywords: Hydrogen storage Carbon nanotube Continuum model Analytical solution Atomistic simulations a b s t r a c t A continuum mechanics model is established for hydrogen storage in single
Mechanisms and Geochemical Models of Core Formation
Rubie, David C
2015-01-01
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.
1994-08-01
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
2015-01-01
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.
Quantum-Mechanical Model of Spacetime
Jarmo Makela
2007-06-20
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.
STATISTICAL MECHANICS MODELING OF MESOSCALE DEFORMATION IN METALS...
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STATISTICAL MECHANICS MODELING OF MESOSCALE DEFORMATION IN METALS Anter El-Azab 36 MATERIALS SCIENCE dislocation dynamics; mesoscale deformation of metals; crystal mechanics...
Failure Predictions for VHTR Core Components using a Probabilistic Contiuum Damage Mechanics Model
Fok, Alex
2013-10-30
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.
Mechanical Models of Fault-Related Folding
Johnson, A. M.
2003-01-09
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)
2014-10-01
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
2014-06-05
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.
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
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Gu, L.; Pallardy, S. G.; Hosman, K. P.; Sun, Y.
2015-01-19
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
Continuum Electrostatics in Cell Biology
L. John Gagliardi
2010-02-06
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.
LANL: Mechanical testing and modeling in MST
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etc.). As the effects of processing are to critical to accurate prediction of its mechanical behavior, MST hosts a range of metallographic and characterization tools. Specific...
Nguyen, Ba Nghiep; Gao, Fei; Henager, Charles H.; Kurtz, Richard J.
2014-05-01
This article proposes a new method to estimate the thermal conductivity of SiC/SiC composites subjected to neutron irradiation. The modeling method bridges different scales from the atomic scale to the scale of a 2D SiC/SiC composite. First, it studies the irradiation-induced point defects in perfect crystalline SiC using molecular dynamics (MD) simulations to compute the defect thermal resistance as a function of vacancy concentration and irradiation dose. The concept of defect thermal resistance is explored explicitly in the MD data using vacancy concentrations and thermal conductivity decrements due to phonon scattering. Point defect-induced swelling for chemical vapor deposited (CVD) SiC as a function of irradiation dose is approximated by scaling the corresponding MD results for perfect crystal ?-SiC to experimental data for CVD-SiC at various temperatures. The computed thermal defect resistance, thermal conductivity as a function of grain size, and definition of defect thermal resistance are used to compute the thermal conductivities of CVD-SiC, isothermal chemical vapor infiltrated (ICVI) SiC and nearly-stoichiometric SiC fibers. The computed fiber and ICVI-SiC matrix thermal conductivities are then used as input for an Eshelby-Mori-Tanaka approach to compute the thermal conductivities of 2D SiC/SiC composites subjected to neutron irradiation within the same irradiation doses. Predicted thermal conductivities for an irradiated Tyranno-SA/ICVI-SiC composite are found to be comparable to available experimental data for a similar composite ICVI-processed with these fibers.
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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 Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home Room NewsInformation Current HABFES OctoberEvan Racah Evan-5InformationValues61 Used4TopFLOPFMM
A Hydro-Thermo-Mechanical Numerical Model For Hdr Geothermal...
A Hydro-Thermo-Mechanical Numerical Model For Hdr Geothermal Reservoir Evaluation Jump to: navigation, search OpenEI Reference LibraryAdd to library Journal Article: A...
Coupled Thermal-Hydrological-Mechanical-Chemical Model And Experiments...
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-Hydrological-Mechanical-Chemical Model And Experiments For Optimization Of Enhanced Geothermal System Development And Production: Evaluation of Stimulation at the Newberry Volcano...
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 ...
Modeling Different Failure Mechanisms in Metals
Zhang, Liang
2012-02-14
Material failure plays an important role in human life. By investigating the failure mechanisms, people can more precisely predict the failure conditions to develop new products, to enhance product performances, and most ...
Fault Models for Quantum Mechanical Switching Networks
Jacob Biamonte; Jeff S. Allen; Marek A. Perkowski
2010-01-19
The difference between faults and errors is that, unlike faults, errors can be corrected using control codes. In classical test and verification one develops a test set separating a correct circuit from a circuit containing any considered fault. Classical faults are modelled at the logical level by fault models that act on classical states. The stuck fault model, thought of as a lead connected to a power rail or to a ground, is most typically considered. A classical test set complete for the stuck fault model propagates both binary basis states, 0 and 1, through all nodes in a network and is known to detect many physical faults. A classical test set complete for the stuck fault model allows all circuit nodes to be completely tested and verifies the function of many gates. It is natural to ask if one may adapt any of the known classical methods to test quantum circuits. Of course, classical fault models do not capture all the logical failures found in quantum circuits. The first obstacle faced when using methods from classical test is developing a set of realistic quantum-logical fault models. Developing fault models to abstract the test problem away from the device level motivated our study. Several results are established. First, we describe typical modes of failure present in the physical design of quantum circuits. From this we develop fault models for quantum binary circuits that enable testing at the logical level. The application of these fault models is shown by adapting the classical test set generation technique known as constructing a fault table to generate quantum test sets. A test set developed using this method is shown to detect each of the considered faults.
Modeling thermal/chemical/mechanical response of energetic materials
Baer, M.R.; Hobbs, M.L.; Gross, R.J.
1995-07-01
An overview of modeling at Sandia National Laboratories is presented which describes coupled thermal, chemical and mechanical response of energetic materials. This modeling addresses cookoff scenarios for safety assessment studies in systems containing energetic materials. Foundation work is discussed which establishes a method for incorporating chemistry and mechanics into multidimensional analysis. Finite element analysis offers the capabilities to simultaneously resolve reactive heat transfer and structural mechanics in complex geometries. Nonlinear conduction heat transfer, with multiple step finite-rate chemistry, is resolved using a thermal finite element code. Rate equations are solved element-by-element using a modified matrix-free stiff solver This finite element software was developed for the simulation of systems requiring large numbers of finite elements. An iterative implicit scheme, based on the conjugate gradient method, is used and a hemi-cube algorithm is employed for the determination of view factors in surface-to-surface radiation transfer The critical link between the reactive heat transfer and mechanics is the introduction of an appropriate constitutive material model providing a stress-strain relationship for quasi-static mechanics analysis. This model is formally derived from bubble nucleation theory, and parameter variations of critical model parameters indicate that a small degree of decomposition leads to significant mechanical response. Coupled thermal/chemical/mechanical analysis is presented which simulates experiments designed to probe cookoff thermal-mechanical response of energetic materials.
Nuclear rotation in the continuum
Fossez, K; Jaganathen, Y; Michel, N; P?oszajczak, M
2015-01-01
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...
Constant displacement rate experiments and constitutive modeling of asphalt mixtures
Hariharakumar, Pradeep
2006-04-12
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...
Statistical Mechanics Approaches to the Modeling of Nonlinear Earthquake Physics
1 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 to the modeling of earthquake faults. We show that the frictional failure physics of earthquakes in these complex
Wang, Hai
, emerging fuel cell technolo- gies, computational fluid mechanics, ground vehicle aerodynamics, combustion students develop problem solving skills in the areas of mechanics, thermody- namics, fluid mechanics, heat advance our understanding of such areas as continuum and particulate fluid mechanics, flight mechanics
Modeling of Mechanical Overlap Joints in Magnetic Shields
Crawford, Anthony C
2015-01-01
This study determines a useful value to use for the gap width of mechanical overlap joints in models of magnetic shielding. The average value of 0.1 mm is found to agree with measurements.
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
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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...
A mechanical model for Fourier's law of heat conduction
David Ruelle
2011-02-27
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.
Atom-to-continuum methods for gaining a fundamental understanding of fracture.
McDowell, David Lynn; Reedy, Earl David, Jr.; Templeton, Jeremy Alan; Jones, Reese E.; Moody, Neville Reid; Zimmerman, Jonathan A.; Belytschko, Ted.; Zhou, Xiao Wang; Lloyd, Jeffrey T.; Oswald, Jay; Delph, Terry J.; Kimmer, Christopher J.
2011-08-01
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.
New Approach to Bounded Quantum--Mechanical Models
Francisco M. Fernández
2008-05-21
We develop an approach for the treatment of one--dimensional bounded quantum--mechanical models by straightforward modification of a successful method for unbounded ones. We apply the new approach to a simple example and show that it provides solutions to both the bounded and unbounded type of models simultaneously
A mechanical approach to mean field spin models
Giuseppe Genovese; Adriano Barra
2009-05-07
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
2015-01-01
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.
Missing links in the root-soil organic matter continuum
O'Brien, Sarah L.; Iversen, Colleen M
2009-01-01
The soil environment remains one of the most complex and poorly understood research frontiers in ecology. Soil organic matter (SOM), which spans a continuum from fresh detritus to highly processed, mineral-associated organic matter, is the foundation of sustainable terrestrial ecosystems. Heterogeneous SOM pools are fueled by inputs from living and dead plants, driven by the activity of micro- and mesofauna, and are shaped by a multitude of abiotic factors. The specialization required to measure unseen processes that occur on a wide range of spatial and temporal scales has led to the partitioning of soil ecology research across several disciplines. In the organized oral session 'Missing links in the root-soil organic matter continuum' at the annual Ecological Society of America meeting in Albuquerque, NM, USA, we joined the call for greater communication and collaboration among ecologists who work at the root-soil interface (e.g. Coleman, 2008). Our goal was to bridge the gap between scientific disciplines and to synthesize disconnected pieces of knowledge from root-centric and soil-centric studies into an integrated understanding of belowground ecosystem processes. We focused this report around three compelling themes that arose from the session: (1) the influence of the rhizosphere on SOM cycling, (2) the role of soil heterotrophs in driving the transformation of root detritus to SOM, and (3) the controlling influence of the soil environment on SOM dynamics. We conclude with a discussion of new approaches for gathering data to bridge gaps in the root-SOM continuum and to inform the next generation of ecosystem models. Although leaf litter has often been considered to be the main source of organic inputs to soil, Ann Russell synthesized a convincing body of work demonstrating that roots, rather than surface residues, control the accumulation of SOM in a variety of ecosystems. Living roots, which are chemically diverse and highly dynamic, also influence a wide range of soil processes, from the exudation of labile C compounds to the development of fungal associations. For example, Zoe Cardon demonstrated that the root-mediated redistribution of deep soil water to relatively dry shallower soil, increased soil CO{sub 2} efflux and nutrient cycling near the surface in an arid ecosystem. Andrew Kulmatiski also discussed the importance of rooting distribution throughout the soil profile for strategies of water uptake by different species in an African savanna. Later, Julie Jastrow demonstrated that living roots shape soil physical structure by promoting the formation of soil aggregates, which facilitated accrual of SOM in restored grasslands. Taken together, the evidence is compelling that living roots, and organic matter derived from root detritus, are important parts of the continuum of organic matter in the soil. Larger soil organisms (i.e. 50 {micro}m to many cm in body size) play an important role in the root-SOM continuum by grazing on roots and microbes, comminuting organic matter and aggregating soil in fecal pellets. However, litterbag and soil incubation studies necessarily exclude invertebrates, and research on faunal activity and trophic dynamics tends to be independent from research on the biogeochemistry of SOM cycling. Tim Filley used plant-derived biomarkers in invertebrate residues to bridge the gap between larger soil organisms, such as earthworms and beetle larvae, and SOM distribution. He found that larger soil organisms help to stabilize root-derived organic matter in soil aggregates. Similar coupling of biogeochemistry with food web studies could prove fruitful for describing mechanisms that underlie critical ecosystem processes. Despite considerable research efforts, the breadth of the microbial role in the root-SOM continuum remains unresolved. Using advanced pyrosequencing techniques, David Nelson demonstrated the importance of archea as nitrifiers in agricultural systems exposed to elevated [CO{sub 2}]. Rising atmospheric [CO{sub 2}] and other changing environmental factors add a layer of complexity t
Notes 01. Modeling of mechanical (lumped parameter) elements
San Andres, Luis
2008-01-01
1 / ? Luis San Andr?s 2008 1.1 Handout # 1 Modeling of Mechanical (Lumped Parameter) Elements The fundamental components of a mechanical system are: masses or inertias, springs (stiffnesses), and dampers. Lumped elements lead to ordinary... into another form of energy (usually heat). Dampers relate the element force (torque) to a translational (angular) velocity. MEEN 617 Notes: Handout 1 / ? Luis San Andr?s 2008 1.2 Our objective: to determine equivalent system elements as those capable...
Continuum discretized BCS approach for weakly bound nuclei
J. A. Lay; C. E. Alonso; L. Fortunato; A. Vitturi
2015-10-12
The Bardeen-Cooper-Schrieffer (BCS) formalism is extended by including the single-particle continuum, thus enabling the analysis of an isotopic chain from stability up to the drip line. We propose a continuum discretized generalized BCS based on single-particle pseudostates (PS). These PS are generated from the diagonalization of the single-particle Hamiltonian within a Transformed Harmonic Oscillator (THO) basis. The consistency of the results versus the size of the basis is studied. The method is applied to neutron rich Oxygen and Carbon isotopes and compared with similar previous works and available experimental data. We make use of the flexibility of the proposed model in order to study the evolution of the occupation of the low-energy continuum when the system becomes weakly bound. We find a larger influence of the non-resonant continuum as long as the Fermi level approaches zero.
Lagrangian continuum dynamics in ALEGRA.
Wong, Michael K. W.; Love, Edward
2007-12-01
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.
Modeling the Mechanical Performance of Die Casting Dies
R. Allen Miller
2004-02-27
The following report covers work performed at Ohio State on modeling the mechanical performance of dies. The focus of the project was development and particularly verification of finite element techniques used to model and predict displacements and stresses in die casting dies. The work entails a major case study performed with and industrial partner on a production die and laboratory experiments performed at Ohio State.
Mechanical models of the 1975 Kalapana, Hawaii earthquake and tsunami
Kirby, James T.
Mechanical models of the 1975 Kalapana, Hawaii earthquake and tsunami Simon J. Daya,*, Philip: Kalapana; Hilo; Kahului; Honolulu; Hilina; Hawaii; earthquake; slump; tsunami; volcano; Kilauea; extension earthquake to have affected Hawaii, after the slightly larger Great Kau earthquake of 1868 (Brigham, 1909
Modelling of the static and dynamic mechanical properties of human
Haslwanter, Thomas
Modelling of the static and dynamic mechanical properties of human otoliths DISSERTATION zur of the city of Paris #12;#12;Abstract The aim of this study is a numerical investigation of the static in the inner ears. They sense accelerations of the head. In the static case, information retrieved from them
Mechanisms, Models, and Simulations of Metal-Coated Fiber Consolidation
Wadley, Haydn
pro-gas turbine engines and other aerospace structures because cess.[6] Recent micromechanicalMechanisms, Models, and Simulations of Metal-Coated Fiber Consolidation R. VANCHEESWARAN, J of Ti-6Al-4Vcoated SiC fibers contained in cylindrical canisters have revealed an unexpectedly high
Mechanical properties and modeling of seal-forming lithologies
Kronenberg, A.K.; Russell, J.E.; Carter, N.L.; Mazariegos, R.; Ibanez, W.
1993-01-01
Specific goals and accomplishments of this research include: (1) The evaluation of models of salt diaper ascent that involve either power law, dislocation creep as determined experimentally by Horseman et al. (1993) or linear, fluid-assisted creep as reported by Spiers et al. (1988, 1990, 1992). We have compared models assuming these two, experimentally evaluated flow laws and examined the predictions they make regarding diaper incubation periods, ascent velocities, deviatoric stresses and strain rates. (2) The evaluation of the effects of differential loading on the initiation an of salt structures. (3) Examination of the role of basement faults on the initiation and morphologic evolution of salt structures. (4) Evaluation of the mechanical properties of shale as a function of pressure and determination of the nature of its brittle-ductile transition. (5) Evaluation of the mechanical anisotropies of shales with varying concentrations, distributions and preferred orientations of clay. (6) The determination of temperature and ratedependencies of strength for a shale constitutive model that can be used in numerical models that depend on viscous formulations. (7) Determination of the mechanisms of deformation for argillaceous rocks over awide range of conditions. (8) Evaluation of the effects of H[sub 2]O within clay interlayers, as adsorbed surface layers.
Mathematical modeling of mechanical vibration assisted conductivity imaging
Ammari, Habib; Kwon, Hyeuknam; Seo, Jin Keun; Woo, Eung Je
2014-01-01
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...
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
Mechanical Modeling of a WIPP Drum Under Pressure
Smith, Jeffrey A.
2014-11-25
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
Evolution of generalized couple-stress continuum theories: a critical analysis
Ali R. Hadjesfandiari; Gary F. Dargush
2014-12-30
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.
Xu, Zhijie; Fang, Yilin; Scheibe, Timothy D.; Bonneville, Alain
2012-05-15
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.
Comprehensive mechanisms for combustion chemistry: Experiment, modeling, and sensitivity analysis
Dryer, F.L.; Yetter, R.A. [Princeton Univ., NJ (United States)
1993-12-01
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.
Non-Thermal Continuum toward SGRB2(N-LMH)
J. M. Hollis; P. R. Jewell; Anthony J. Remijan; F. J. Lovas
2007-03-15
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.
Cooperative folding of muscle myosins: I. Mechanical model
Matthieu Caruel; Jean-Marc Allain; Lev Truskinovsky
2015-10-12
Mechanically induced folding of passive cross-linkers is a fundamental biological phenomenon. A typical example is a conformational change in myosin II responsible for the power-stroke in skeletal muscles. In this paper we present an athermal perspective on such folding by analyzing the simplest purely mechanical prototype: a parallel bundle of bi-stable units attached to a common backbone. We show that in this analytically transparent model, characterized by a rugged energy landscape, the ground states are always highly coherent, single-phase configurations. We argue that such cooperative behavior, ensuring collective conformational change, is due to the dominance of long- range interactions making the system non-additive. The detailed predictions of our model are in agreement with experimentally observed non-equivalence of fast force recovery in skeletal muscles loaded in soft and hard devices. Some features displayed by the model are also recognizable in the behavior of other biological systems with passive multi-stability and long-range interactions including detaching adhesive binders and pulled RNA/DNA hairpins.
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
Magnetic and Mechanical Analysis of the HQ Model Quadrupole Designs for LARP
Felice, Helene
2008-01-01
on the magnetic and mechanical design of the HQ models willIII. M ECHANICAL A NALYSIS A. Mechanical design Within LARP,two different mechanical design concepts are under study
Continuum Partners | Open Energy Information
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTIONRobertsdale, Alabama (Utility Company)| Open(Evans, Et Al.,InformationMinorConte LargeContinuum
A mechanical model of early salt dome growth
Irwin, Frank Albert
1988-01-01
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...
nrel.gov/continuum Issue 3 Driving Solar Innovations from
nrel.gov/continuum Issue 3 Spectrum The NREL of NREL Leads Driving Solar Innovations from Reaping a Wind Farm Modeling Research Laboratory to Marketplace Harvest of Hope Clean Energy Innovation NREL Visitors touring the National Renewable Energy Laboratory (NREL) are often amazed at the scope of our
New method for extracting quasi-bound states from the continuum
J. B. Faes; M. Ploszajczak
2007-09-19
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.
Curved mesh generation and mesh refinement using Lagrangian solid mechanics
Persson, P.-O.
2009-01-01
Nonlinear continuum mechanics for ?nite element analysis,nement using Lagrangian Solid Mechanics Per-Olof Persson ?methods for computational mechanics has been emphasized in
Modeling the Q-cycle mechanism of transmembrane energy conversion
Anatoly Yu. Smirnov; Franco Nori
2011-06-29
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.
Statistical mechanics models for multimode lasers and random lasers
Antenucci, F; Berganza, M Ibáñez; Marruzzo, A; Leuzzi, L
2015-01-01
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...
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
Palmer, Jeffrey Shane
2008-01-01
The elastic and viscoelastic stress-strain behavior of cytoskeletal networks, important to many cellular functions, is modeled via a microstructurally-informed continuum mechanics approach. The force-extension behavior of ...
N + 1 dimensional quantum mechanical model for a closed universe
T. R. Mongan
1999-02-10
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.
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
C. H. Young; Y. L. Shirley; N. J. Evans II; J. M. C. Rawlings
2002-10-08
We present results from the observations and modeling of seventeen Class I cores with the Submillimetre Common Users Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope (JCMT). By modeling the transfer of radiation through the envelope for nine cores, we find, for a power law distribution n(r)=n_f(r/r_f)^-p, the average and standard deviation p=1.6 +/- 0.4 and a median of p=1.8. However, the inclusion of a disk or other point-like component can cause the derived p to be shallower by as much as 0.5. In addition, we test the Shu collapse model for our sources and discuss the application of simpler analyses that derive a density power law distribution directly from the slope of the intensity radial profile. The total mass of the envelope in our sample has a range from 0.04 to 5.0 M_sun, but these masses disagree with the virial masses derived from molecular line observations. Finally, we discuss the nature of these sources in light of various evolutionary indicators and find that T_bol and L_obs/L_smm are often inconsistent in distinguishing Class 0 from Class I cores.
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
The von Neumann model of measurement in quantum mechanics
Mello, Pier A.
2014-01-08
We describe how to obtain information on a quantum-mechanical system by coupling it to a probe and detecting some property of the latter, using a model introduced by von Neumann, which describes the interaction of the system proper with the probe in a dynamical way. We first discuss single measurements, where the system proper is coupled to one probe with arbitrary coupling strength. The goal is to obtain information on the system detecting the probe position. We find the reduced density operator of the system, and show how Lüders rule emerges as the limiting case of strong coupling. The von Neumann model is then generalized to two probes that interact successively with the system proper. Now we find information on the system by detecting the position-position and momentum-position correlations of the two probes. The so-called 'Wigner's formula' emerges in the strong-coupling limit, while 'Kirkwood's quasi-probability distribution' is found as the weak-coupling limit of the above formalism. We show that successive measurements can be used to develop a state-reconstruction scheme. Finally, we find a generalized transform of the state and the observables based on the notion of successive measurements.
On models for viscoelastic fluid-like materials that are mechanically incompressible and
Cerveny, Vlastislav
On models for viscoelastic fluid-like materials that are mechanically incompressible and thermally of the full NavierStokesFourier system. J. Math. Fluid Mech., 11:274302, 2009 Mechanically incompressible;Viscoelastic fluids Maxwell model F l lsld µm m Mechanical analogue: Spring energy storage. Dashpot
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
Design and modeling of carbon nanotube-based compliant mechanisms
DiBiasio, Christopher M. (Christopher Michael)
2007-01-01
The objective of this research is to generate the knowledge required to adapt macro- and microscale compliant mechanism theory to design carbon nanotube-based nano-scale compliant mechanisms. Molecular simulations of a ...
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
Relativistic viscoelastic fluid mechanics
Masafumi Fukuma; Yuho Sakatani
2011-09-01
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
2011-03-27
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.
Song, Jing, 1972-
2004-01-01
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 ...
Blum, Rick
A Statistical and Physical MechanismsBased Interference and Noise Model for Array Observations is a member of IEEE. K. F. McDonald is a student member. 1 #12; Abstract A statistical noise model is developed from mathematical modeling of the physical mechanisms that generate noise in communication
The Near-Ultraviolet Continuum of Late-Type Stars
Carlos Allende Prieto; David L. Lambert
2000-01-28
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.
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)
2014-10-20
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.
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 ...
Mechanical modeling of the plastic bonded explosive LX17
Clayton, Kyle Martin
2001-01-01
and time prohibitive to use as a method of characterization, so micromechanical models are developed here. First, the viscoelastic binder and elastic particles are characterized to be used in the developed models. Analytic micromechanics models...
Substrate Hydroxylation in Methane Monooxygenase: Quantitative Modeling via Mixed Quantum Mechanics/
Gherman, Benjamin F.
Substrate Hydroxylation in Methane Monooxygenase: Quantitative Modeling via Mixed Quantum Mechanics with mixed quantum mechanics/molecular mechanics (QM/MM) methods, the hydroxylation of methane. With the current results, recent kinetic data for CH3X (X ) H, CH3, OH, CN, NO2) substrate hydroxylation in MMOH
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
2014-12-03
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
2012-01-01
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 ...
Characterization and modeling of polysilicon MEMS chemical-mechanical polishing
Tang, Brian D. (Brian David), 1980-
2004-01-01
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, ...
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
Modeling benzene plume elongation mechanisms exerted by ethanol using RT3D with a general
Alvarez, Pedro J.
Modeling benzene plume elongation mechanisms exerted by ethanol using RT3D with a general substrate ethanol on benzene fate and transport in fuel-contaminated groundwater and to discern the most influential benzene plume elongation mechanisms. The model, developed as a module for the Reactive Transport in 3
A new model for myosin dimeric motors incorporating Brownian ratchet and powerstroke mechanisms
Kawai, Ryoichi
A new model for myosin dimeric motors incorporating Brownian ratchet and powerstroke mechanisms motor proteins in general. A single motor domain is modeled using our previous work on hybrid motors that exhibit elements of both a powerstroke and a Brownian motor mechanism. The different behavior observed
Li, Teng
In situ electro-mechanical experiments and mechanics modeling of tensile cracking in indium tin Lou1,b) 1 Department of Mechanical Engineering and Materials Science, Rice University, Houston, Texas 77005, USA 2 Department of Mechanical Engineering and Maryland NanoCenter, University of Maryland
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)
2000-04-01
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.
Argyris Nicolaidis
2012-11-09
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.
Implementation of an anisotropic mechanical model for shale in Geodyn
Attaia, A.; Vorobiev, O.; Walsh, S.
2015-05-15
The purpose of this report is to present the implementation of a shale model in the Geodyn code, based on published rock material models and properties that can help a petroleum engineer in his design of various strategies for oil/gas recovery from shale rock formation.
Supporting random wave models: a quantum mechanical approach
J. D. Urbina; K. Richter
2003-04-23
We show how two-point correlation functions derived within non-isotropic random wave models are in fact quantum results that are obtained in the appropriate limit in terms of the exact Green function of the quantum system. Since no statistical model is required for this derivation, this shows that taking the wave functions as Gaussian processes is the only assumption of those random wave models. We also show how for clean systems the two-point correlation function defined through an energy average defines a Gaussian theory which substantially reduces the spurious contributions coming from the normalisation problem.
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
Mechanics-Based Modeling of Bending and Torsion in Active Cannulas
transmissions. In this paper, we consider both bending and torsion, describing the total elastic energy storedMechanics-Based Modeling of Bending and Torsion in Active Cannulas D. Caleb Rucker, and Robert J cannula more accurately than previous models, reducing tip error by 72% over a bending-only model, and 35
Vibration Stabilization of a Mechanical Model of a X-Band Linear Collider Final Focus Magnet
Frisch, Josef; Chang, Allison; Decker, Valentin; Doyle, Eric; Eriksson, Leif; Hendrickson, Linda; Himel, Thomas; Markiewicz, Thomas; Partridge, Richard; Seryi, Andrei; /SLAC
2006-09-28
The small beam sizes at the interaction point of a X-band linear collider require mechanical stabilization of the final focus magnets at the nanometer level. While passive systems provide adequate performance at many potential sites, active mechanical stabilization is useful if the natural or cultural ground vibration is higher than expected. A mechanical model of a room temperature linear collider final focus magnet has been constructed and actively stabilized with an accelerometer based system.
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
Modelling the mechanical interaction between flowing materials and retaining wire structures
Gagliardini, Olivier
Modelling the mechanical interaction between flowing materials and retaining wire structures Franc Sols Solides Structures, UJF-INPG-CNRS, Grenoble, France Received 10 March 2004; received in revised, design of structural elements may require analysing the mechanical interac- tion between a flowing
Travelling wave solutions for a quasilinear model of Field Dislocation Mechanics
Scheichl, Robert
Mechanics to a scalar problem in one spatial dimension and investigate the existence of static and slowTravelling wave solutions for a quasilinear model of Field Dislocation Mechanics Amit Acharya in the static case is not proper and it is shown that no comparison principle holds. The findings indicate
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
Mechanical Systems on an almost Kähler model of a Finsler Manifold
Mehmet Tekkoyun; O?uzhan Çelik
2012-11-06
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
2013-01-01
GEOFRAC is a three-dimensional, geology-based, geometric-mechanical, hierarchical, stochastic model of natural rock fracture systems. The main characteristic of GEOFRAC is that it is based on statistical input representing ...
Haldar, Krishnendu 1978-
2012-12-06
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 ...
DISLOCATION GENERATION IN Si: A THERMO-MECHANICAL MODEL BASED ON MEASURABLE PARAMETERS*
Balzar, Davor
DISLOCATION GENERATION IN Si: A THERMO-MECHANICAL MODEL BASED ON MEASURABLE PARAMETERS* Bhushan for predicting dislocation distribution generated by thermal stresses in Si is described. We use that can minimize dislocation generation for improved solar cell performance. INTRODUCTION Dislocations
Johnson, Joy Marie
2015-01-01
A theoretical modeling approach is developed to predict silica-specific instability in chemical-mechanical polishing (CMP) slurries. In CMP, the formation of large agglomerates is of great concern, as these large particles ...
Modeling Regional Air Quality Using the Near-Explicit Master Chemical Mechanism
Li, Jingyi
2014-08-01
structure, allowing an explicit calculation of SOA formation from individual model species. Earlier attempts in this area were aimed at developing mechanisms for regional SOA using a small number of representative species (Griffin et al., 2002b; Griffin...
Skerry, Benjamin James Oliver
2013-07-06
I have investigated epigenetic mechanisms of acquired endocrine-resistance in breast cancer using an in vitro model system based on estrogen-dependent MCF7 cells and their derivatives, LCC1 and LCC9. LCC1 cells, derived ...
Derivation of Ohm's Law in a Deterministic Mechanical Model
Chernov, Nikolai
GSP-1 Moscow V-334, Russia Abstract We study the Lorentz gas in small external electric and magnetic/T, with T the "temperature," is equal to both the asymptotic decay rate of the Gibbs entropy and minus the sum which incorporates a frictional term designed to model the interaction of the test particle with a "heat
Modeling-Thermo-electrochemistry, Capacity Degradation and Mechanics with
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious RankADVANCED MANUFACTURING OFFICESpecialAPPENDIX F Wetlandsof Energy ModelSEI Layer | Department of
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
2007-11-04
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.
Continuum physics with quenched overlap fermions
Duerr, Stephan; Hoelbling, Christian
2005-10-01
We calculate m{sub ud}=(m{sub u}+m{sub d})/2, m{sub s}, f{sub {pi}} and f{sub K} in the quenched continuum limit with UV-filtered overlap fermions. We see rather small scaling violations on lattices as coarse as a{sup -1}{approx_equal}1 GeV and conjecture that similar advantages would be manifest in unquenched studies.
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
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
Driven cavity flow: from molecular dynamics to continuum hydrodynamics
Tiezheng Qian; Xiao-Ping Wang
2004-03-06
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.
P. Evesque
2005-07-04
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
2015-08-04
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.
Sluse, D; Anguita, T; Braibant, L; Riaud, P
2015-01-01
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
2006-01-05
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.
Understanding Creep Mechanisms in Graphite with Experiments, Multiscale Simulations, and Modeling
Eapen, Jacob; Murty, Korukonda; Burchell, Timothy
2014-06-02
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
2006-09-30
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.
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
2014-12-01
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
Simulation of neoclassical transport with the continuum gyrokinetic code COGENT
Dorf, M. A.; Cohen, R. H.; Dorr, M.; Rognlien, T.; Hittinger, J.; Compton, J.; Colella, P.; Martin, D.; McCorquodale, P.
2013-01-15
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.
Mechanics of collective unfolding
M Caruel; J. -M Allain; L Truskinovsky
2015-01-07
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.
Continuum regularization of gauge theory with fermions
Chan, H.S.
1987-03-01
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.
Shell model nuclear matrix elements for competing mechanisms contributing to double beta decay
Horoi, Mihai
2013-12-30
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.
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
A. Besser; U. S. Schwarz
2007-10-24
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.
Bosonic seesaw mechanism in a classically conformal extension of the Standard Model
Naoyuki Haba; Hiroyuki Ishida; Nobuchika Okada; Yuya Yamaguchi
2015-08-27
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.
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 correlations in conjunction with the a priori specification of the existence of a particularly low energy state provide a method of introducing the aspect of minimal frustration to the energy landscapes of random
ELSEVIER Physica D 107 (1997) 322-325 Statistical mechanics of correlated energy landscape models
Plotkin, Steven S.
1997-01-01
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
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
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
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
Efficiency analysis of a pneu-mechanical Wave Energy Converter : model of the device losses,
Psaltis, Demetri
ENAC/ Efficiency analysis of a pneu-mechanical Wave Energy Converter : model of the device losses. Van Herle 1 Mots Clés: Efficiency Analysis, Power Take Off, Renewable Energy, WEC, Wave Energy. 1 have been focused on the efficiency of the different technologies on a test rig and building
Mechanics of complex bodies: commentary on the unified modelling of material substructures
Paolo Maria Mariano
2008-03-26
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.
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
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
EXCHANGE FUNCTIONS Exchange Functions is a speci cation mechanism for designing and a model for
Filman, Robert E.
to monitor and control a manufacturing process is an embedded system. 74 #12;exchange functions 75 exampleCHAPTER SEVEN EXCHANGE FUNCTIONS Exchange Functions is a speci cation mechanism for designing and a model for describing distributed and embedded systems.* Exchange Functions assumes ex- plicit processes
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
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
From Quanta to the Continuum: Opportunities for Mesoscale Science...
Office of Scientific and Technical Information (OSTI)
Quanta to the Continuum: Opportunities for Mesoscale Science Crabtree, George Argonne National Lab. (ANL), Argonne, IL (United States); Sarrao, John Los Alamos National Lab....
Quanta to the Continuum: Opportunities for Mesoscale Science...
Office of Scientific and Technical Information (OSTI)
Quanta to the Continuum: Opportunities for Mesoscale Science Sarrao, John L Los Alamos National Laboratory; Crabtree, George Argonne National Laboratory 36 MATERIALS SCIENCE;...
Mavko, B.; Cizelj, L. (Jozef Stefan Inst., Reactor Engineering Div., P.O. Box 100, 61111 Ljubljana, Slovenia (YU))
1992-05-01
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.
Continuum Study of Heavy Quark Diffusion
Thomas Neuhaus
2015-04-28
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
2014-11-10
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.
Sub-discretized surface model with application to contact mechanics in multi-body simulation
Johnson, S; Williams, J
2008-02-28
The mechanics of contact between rough and imperfectly spherical adhesive powder grains are often complicated by a variety of factors, including several which vary over sub-grain length scales. These include several traction factors that vary spatially over the surface of the individual grains, including high energy electron and acceptor sites (electrostatic), hydrophobic and hydrophilic sites (electrostatic and capillary), surface energy (general adhesion), geometry (van der Waals and mechanical), and elasto-plastic deformation (mechanical). For mechanical deformation and reaction, coupled motions, such as twisting with bending and sliding, as well as surface roughness add an asymmetry to the contact force which invalidates assumptions for popular models of contact, such as the Hertzian and its derivatives, for the non-adhesive case, and the JKR and DMT models for adhesive contacts. Though several contact laws have been offered to ameliorate these drawbacks, they are often constrained to particular loading paths (most often normal loading) and are relatively complicated for computational implementation. This paper offers a simple and general computational method for augmenting contact law predictions in multi-body simulations through characterization of the contact surfaces using a hierarchically-defined surface sub-discretization. For the case of adhesive contact between powder grains in low stress regimes, this technique can allow a variety of existing contact laws to be resolved across scales, allowing for moments and torques about the contact area as well as normal and tangential tractions to be resolved. This is especially useful for multi-body simulation applications where the modeler desires statistical distributions and calibration for parameters in contact laws commonly used for resolving near-surface contact mechanics. The approach is verified against analytical results for the case of rough, elastic spheres.
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
2005-11-01
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
2004-11-15
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...
Fang, Yilin; Nguyen, Ba Nghiep; Carroll, Kenneth C.; Xu, Zhijie; Yabusaki, Steven B.; Scheibe, Timothy D.; Bonneville, Alain
2013-09-12
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.
Inserting Group Variables into Fluid Mechanics
R. Jackiw
2004-10-28
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.
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
2005-07-01
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.
Exotic see-saw mechanism for neutrini and leptogenesis in a Pati-Salam model
Addazi, Andrea; Ricciardi, Giulia
2015-01-01
We discuss non-perturbative corrections to the neutrino sector, in the context of a D-brane Pati-Salam-like model, that can be obtained as a simple alternative to $SO(10)$ GUT's in theories with open and unoriented strings. In such D-brane models, exotic stringy instantons can correct the right-handed neutrino mass matrix in a calculable way, thus affecting mass hierarchies and modifying the see-saw mechanism to what we name exotic see-saw. For a wide range of parameters, a compact spectrum of right-handed neutrino masses can occur that gives rise to a predictive scenario for low energy observables. This model also provides a viable mechanism for Baryon Asymmetry in the Universe (BAU) through leptogenesis. Finally, a Majorana mass for the neutron is naturally predicted in the model, leading to potentially testable neutron-antineutron oscillations. Combined measurements in neutrino and neutron-antineutron sectors could provide precious informations on physics at the quantum gravity scale.
A minimal model for the inelastic mechanics of biopolymer networks and cells
Lars Wolff; Klaus Kroy
2012-05-27
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.
Song, Zhichao
2012-01-01
H. , 2003. Fracture mechanics analysis of thin coatingsK.L. , 1985. Contact Mechanics, Cambridge University Press,J. , Chaboche, J. L. , 1994. Mechanics of Solid Materials.
Mechanical rejuvenation and over-aging in the soft glassy rheology model
Mya Warren; Joerg Rottler
2008-07-04
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.
J. Jeknic-Dugic; M. Dugic; A. Francom
2013-08-13
We observe a Quantum Brownian Motion (QBM) Model Universe in conjunction with recently established Entanglement Relativity and Parallel Occurrence of Decoherence. The Parallel Occurrence of Decoherence establishes the simultaneous occurrence of decoherence for two mutually irreducible structures (decomposition into subsystems) of the total QBM model universe. First we find that Everett world branching for one structure excludes branching for the alternate structure and in order to reconcile this situation branching cannot be allowed for either of the structures considered. Second, we observe the non-existence of a third, "emergent structure", that could approximate both structures and also be allowed to branch. Ultimately we find unless world-branching requires additional criteria or conditions, or there is a privileged structure, that we provide a valid model that cannot be properly described by the Everett Interpretation of Quantum Mechanics.
Neoclassical Simulation of Tokamak Plasmas using Continuum Gyrokinetc Code TEMPEST
Xu, X Q
2007-11-09
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
2014-10-07
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.
Mechanical formalism for tissue dynamics
Sham Tlili; Cyprien Gay; Francois Graner; Philippe Marcq; François Molino; Pierre Saramito
2014-12-23
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.
Statistical mechanics model for the transit free energy of monatomic liquids
Duane C. Wallace; Eric D. Chisolm; N. Bock; G. De Lorenzi-Venneri
2010-04-19
In applying Vibration-Transit (V-T) theory of liquid dynamics to the thermodynamic properties of monatomic liquids, the point has been reached where an improved model is needed for the small (approx. 10%) transit contribution. Toward this goal, an analysis of the available high-temperature experimental entropy data for elemental liquids was recently completed [D. C. Wallace, E. D. Chisolm, and N. Bock, Phys. Rev. B 79, 051201 (2009)]. This analysis yields a common curve of transit entropy vs. T/\\theta_{tr}, where T is temperature and \\theta_{tr} is a scaling temperature for each element. In the present paper, a statistical mechanics model is constructed for the transit partition function, and is calibrated to the experimental transit entropy curve. The model has two scalar parameters, and captures the temperature scaling of experiment. The calibrated model fits the experimental liquid entropy to high accuracy at all temperatures. With no additional parameters, the model also agrees with both experiment and molecular dynamics for the internal energy vs. T for Na. With the calibrated transit model, V-T theory provides equations subject to ab initio evaluation for thermodynamic properties of monatomic liquids. This will allow the range of applicability of the theory, and its overall accuracy, to be determined. More generally, the hypothesis of V-T theory, which divides the many-atom potential energy valleys into random and symmetric classes, can also be tested for its application beyond monatomic systems.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Anderson-Cook, Christine M.; Morzinski, Jerome; Blecker, Kenneth D.
2015-08-19
Understanding the impact of production, environmental exposure and age characteristics on the reliability of a population is frequently based on underlying science and empirical assessment. When there is incomplete science to prescribe which inputs should be included in a model of reliability to predict future trends, statistical model/variable selection techniques can be leveraged on a stockpile or population of units to improve reliability predictions as well as suggest new mechanisms affecting reliability to explore. We describe a five-step process for exploring relationships between available summaries of age, usage and environmental exposure and reliability. The process involves first identifying potential candidatemore »inputs, then second organizing data for the analysis. Third, a variety of models with different combinations of the inputs are estimated, and fourth, flexible metrics are used to compare them. As a result, plots of the predicted relationships are examined to distill leading model contenders into a prioritized list for subject matter experts to understand and compare. The complexity of the model, quality of prediction and cost of future data collection are all factors to be considered by the subject matter experts when selecting a final model.« less
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
On the Large Mass Limit of the Continuum Theories in Kaplan's Formulation
T. Kawano; Y. Kikukawa
1994-03-03
Being inspired by Kaplan's proposal for simulating chiral fermions on a lattice, we examine the continuum analog of his domain-wall construction for two-dimensional chiral Schwinger models. Adopting slightly unusual dimensional regularization, we explicitly evaluate the one-loop effective action in the limit that the domain-wall mass goes to infinity. For anomaly-free cases, the effective action turns out to be gauge invariant in two-dimensional sense.
Collins, James J.
Mechanism of stochastic resonance enhancement in neuronal models driven by 1/f noise Daichi NozakiHugh-Nagumo FHN neuronal model, the optimal noise variance for SR could be minimized with 1. In this study, we model. We demonstrate that the aforementioned effect of 1/f noise is related to the dynamical
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
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 ...
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
A thermo-hydro-mechanical coupled model in local thermal non-equilibrium for fractured HDR reservoir
Boyer, Edmond
A thermo-hydro-mechanical coupled model in local thermal non-equilibrium for fractured HDR of New South Wales, Sydney 2052, Australia. Abstract The constitutive thermo-hydro-mechanical equations is next applied to simulate circulation tests at the Fenton Hill HDR reservoir. The finer thermo-hydro
Freed, Alan D.; Einstein, Daniel R.
2011-04-14
An isotropic constitutive model for the parenchyma of lung has been derived from the theory of hypo-elasticity. The intent is to use it to represent the mechanical response of this soft tissue in sophisticated, computational, fluid-dynamic models of the lung. This demands that the continuum model be accurate, yet simple and effcient. An objective algorithm for its numeric integration is provided. The response of the model is determined for several boundary-value problems whose experiments are used for material characterization. The effective elastic, bulk, and shear moduli, and Poisson’s ratio, as tangent functions, are also derived. The model is characterized against published experimental data for lung. A bridge between this continuum model and a dodecahedral model of alveolar geometry is investigated, with preliminary findings being reported.
Continuum Thermodynamics of the SU(N) Gauge Theory
Saumen Datta; Sourendu Gupta
2010-12-30
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.
Microstructure and Mechanical Properties of n-irradiated Fe-Cr Model Alloys
Matijasevic, Milena; Al Mazouzi, Abderrahim
2008-07-01
High chromium ( 9-12 wt %) ferritic/martensitic steels are candidate structural materials for future fusion reactors and other advanced systems such as accelerator driven systems (ADS). Their use for these applications requires a careful assessment of their mechanical stability under high energy neutron irradiation and in aggressive environments. In particular, the Cr concentration has been shown to be a key parameter to be optimized in order to guarantee the best corrosion and swelling resistance, together with the least embrittlement. In this work, the characterization of the neutron irradiated Fe-Cr model alloys with different Cr % with respect to microstructure and mechanical tests will be presented. The behavior of Fe-Cr alloys have been studied using tensile tests at different temperature range ( from -160 deg. C to 300 deg. C). Irradiation-induced microstructure changes have been studied by TEM for two different irradiation doses at 300 deg. C. The density and the size distribution of the defects induced have been determined. The tensile test results indicate that Cr content affects the hardening behavior of Fe-Cr binary alloys. Hardening mechanisms are discussed in terms of Orowan type of approach by correlating TEM data to the measured irradiation hardening. (authors)
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)
2014-03-01
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.
On a 2D hydro-mechanical lattice approach for modelling hydraulic fracture
Grassl, Peter; Gallipoli, Domenico; Wheeler, Simon J
2014-01-01
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.
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
2015-01-01
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.
Equilibrium statistical mechanics and energy partition for the shallow water model
Renaud, Antoine; Bouchet, Freddy
2015-01-01
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...
Testing spontaneous wave-function collapse models on classical mechanical oscillators
Lajos Diósi
2014-11-17
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.
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)
2014-03-28
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.
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
2013-09-04
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
2015-01-09
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.
Nicholas Rivera; Chia Wei Hsu; Bo Zhen; Hrvoje Buljan; John D. Joannopoulos; Marin Solja?i?
2015-07-03
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.
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
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)
2014-05-10
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.
Dominic J. O'. Lee
2015-04-17
Presented here, is a technical manuscript that may form the basis of later published work. In it, we develop a statistical mechanical model to describe a closed loop plectoneme, applicable for when the closed loop is sufficiently supercoiled. The model divides the system up into end loops and a braided section; the end loops are assumed to contribute little to the super-coil writhe. Within the braided section, the model incorporates interactions that depend on the structure of the molecule; in particular, we consider those that depend on helical structure. A method for approximating the steric interactions is utilized that we had previously used in other publications. We go on to construct variational approximations for our closed loop plectoneme model in two cases. The first case is where helix dependent interactions are strong, and in the second case they are considered weak. In developing these approximations, we approximate the Fuller-White condition by replacing, in all expressions that depend on twist, writhe with average writhe, valid when the braided section is sufficiently long. How this approximation is made and the conditions when this approximation is valid are also discussed. The approximation allows for a Legendre transformation of the free energy, which with the introduction of moment (or torque), effectively allowing for twist and average writhe to be treated independently in the transformed (Gibbs like) free energy. Next, we then show how one may compute the average writhe of the braided section. Lastly, we discuss how some of the approximations considered may be relaxed, and discuss how the resulting model free energy might be computed by MC simulation.
A wave-mechanical model of incoherent neutron scattering II. Role of the momentum transfer
Frauenfelder, Hans; Fenimore, Paul W
2015-01-01
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 ...
Damien Vandembroucq; Stéphane Roux
2011-12-05
We discuss aging and localization in a simple "Eshelby" mesoscopic model of amorphous plasticity. Plastic deformation is assumed to occur through a series of local reorganizations. Using a discretization of the mechanical fields on a discrete lattice, local reorganizations are modeled as local slip events. Local yield stresses are randomly distributed in space and invariant in time. Each plastic slip event induces a long-ranged elastic stress redistribution. Mimicking the effect of aging, we focus on the behavior of the model when the initial state is characterized by a distribution of high local yield stress values. A dramatic effect on the localization behavior is obtained: the system first spontaneously self-traps to form a shear band which then only slowly widens. The higher the "age" parameter the more localized the plastic strain field. Two-time correlation computed on the stress field show a divergent correlation time with the age parameter. The amplitude of a local slip event (the prefactor of the Eshelby singularity) as compared to the yield stress distribution width acts here as an effective temperature-like parameter: the lower the slip increment, the higher the localization and the decorrelation time.
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
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
A Mechanical Analog of the Two-bounce Resonance of Solitary Waves: Modeling and Experiment
Roy H. Goodman; Aminur Rahman; Michael Bellanich; Catherine Morrision
2015-03-28
We describe a simple mechanical system, a ball rolling along a specially-designed landscape, that mimics the dynamics of a well known phenomenon, the two-bounce resonance of solitary wave collisions, that has been seen in countless numerical simulations but never in the laboratory. We provide a brief history of the solitary wave problem, stressing the fundamental role collective-coordinate models played in understanding this phenomenon. We derive the equations governing the motion of a point particle confined to such a surface and then design a surface on which to roll the ball, such that its motion will evolve under the same equations that approximately govern solitary wave collisions. We report on physical experiments, carried out in an undergraduate applied mathematics course, that seem to verify one aspect of chaotic scattering, the so-called two-bounce resonance.
Swift, D. C.; Paisley, Dennis L.; Kyrala, George A.; Hauer, Allan
2002-01-01
Ab initio quantum mechanics was used to construct a thermodynamically complete and rigorous equation of state for beryllium in the hexagonal and body-centred cubic structures, and to predict elastic constants as a function of compression. The equation of state agreed well with Hugoniot data and previously-published equations of state, but the temperatures were significantly different. The hexagonal/bcc phase boundary agreed reasonably well with published data, suggesting that the temperatures in our new equation of state were accurate. Shock waves were induced in single crystals and polycrystalline foils of beryllium, by direct illumination using the TRIDENT laser at Los Alamos. The velocity history at the surface of the sample was measured using a line-imaging VISAR, and transient X-ray diffraction (TXD) records were obtained with a plasma backlighter and X-ray streak cameras. The VISAR records exhibited elastic precursors, plastic waves, phase changes and spall. Dual TXD records were taken, in Bragg and Laue orientations. The Bragg lines moved in response to compression in the uniaxial direction. Because direct laser drive was used, the results had to be interpreted with the aid of radiation hydrodynamics simulations to predict the loading history for each laser pulse. In the experiments where there was evidence of polymorphism in the VISAR record, additional lines appeared in the Bragg and Laue records. The corresponding pressures were consistent with the phase boundary predicted by the quantum mechanical equation of state for beryllium. A model of the response of a single crystal of beryllium to shock loading is being developed using these new theoretical and experimental results. This model will be used in meso-scale studies of the response of the microstructure, allowing us to develop a more accurate representation of the behaviour of polycrystalline beryllium.
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)
1997-12-31
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.
The abelian confinement mechanism revisited: New aspects of the Georgi–Glashow model
Anber, Mohamed M.
2014-02-15
The confinement problem remains one of the most difficult problems in theoretical physics. An important step toward the solution of this problem is Polyakov’s work on abelian confinement. The Georgi–Glashow model is a natural testing ground for this mechanism which has been surprising us by its richness and wide applicability. In this work, we shed light on two new aspects of this model in 2+1 D. First, we develop a many-body description of the effective degrees of freedom. Namely, we consider a non-relativistic gas of W-bosons in the background of monopole–instanton plasma. Many-body treatment is a standard toolkit in condensed matter physics. However, we add a new twist by supplying the monopole–instantons as external background field. Using this construction along with a mean-field approximation, we calculate the form of the potential between two electric probes as a function of their separation. This potential is expressed in terms of the Meijer-G function which interpolates between logarithmic and linear behavior at small and large distances, respectively. Second, we develop a systematic approach to integrate out the effect of the W-bosons at finite temperature in the range 0?T
A 1-dimensional statistical mechanics model for nucleosome positioning on genomic DNA
Tesoro, S; Morozov, A N; Sulaiman, N; Marenduzzo, D
2015-01-01
The first level of folding of DNA in eukaryotes is provided by the so called '10nm chromatin fibre', where DNA wraps around histone proteins (approx. 10 nm in size) to form nucleosomes, which go on to create a zig zagging 'bead on a string' structure. In this work we present a one dimensional statistical mechanics model to study nucleosome positioning within one such 10 nm fibre. We consider both the case of homogeneous DNA, where the problem can be mapped to a Tonks gas, and that of genomic sheep DNA, where our modelling is informed by high-resolution nucleosome positioning data. First, we consider the simple, analytically solvable, case where nucleosomes are assumed to be point like. Then, we perform numerical simulations to gauge the effect of their finite size on the nucleosomal distribution probabilities. Finally, we compare nucleosome distributions and simulated nuclease digestion patterns for the two cases (homogeneous and sheep DNA), thereby providing testable predictions of the effect of sequence on ...
Improvement of Stent Retriever Design and Efficacy of Mechanical Thrombectomy in a Flow Model
Wenger, Katharina; Nagl, Frank; Wagner, Marlies Berkefeld, Joachim
2013-02-15
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.
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
Continuum- based computational models of biological living cell
Cheng, Feifei
2009-05-15
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 ...
CONTINUUM MODELING OF ENGINEERING CONSTANTS OF ORIENTED STRANDBOARD
are influ- ites(Dai and Steiner 1994a, b). When used to enced by resin application anti heat treatments
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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power AdministrationRobust, High-Throughput Analysis ofSample SULIColin Humphreys Home ColinSandia
Continuum modeling of diffusion and dispersion in dense granular flows
Office of Scientific and Technical Information (OSTI)
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Continuum modeling of diffusion and dispersion in dense granular flows
Office of Scientific and Technical Information (OSTI)
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Equivalent Continuum Modeling for Shock Wave Propagation in Jointed Media
Office of Scientific and Technical Information (OSTI)
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Equivalent Continuum Modeling for Shock Wave Propagation in Jointed Media
Office of Scientific and Technical Information (OSTI)
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THMC Modeling of EGS Reservoirs Â… Continuum through Discontinuum
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious RankADVANCED MANUFACTURINGEnergyPlan | Department ofSUPPLEMENTSwitzerland|ofSessionsCHAPTERADVANCEDTHIS
A wave-mechanical model of incoherent neutron scattering II. Role of the momentum transfer
Hans Frauenfelder; Robert D. Young; Paul W. Fenimore
2015-08-20
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
2008-01-01
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 ...
Telleria, Maria J
2010-01-01
This thesis explains when, and why, solder-based phase change materials (PCMs) are best-suited as a means to modify a robotic mechanism's kinematic and elastomechanic behavior. The preceding refers to mechanisms that possess ...
Song, Zhichao
2012-01-01
adhesion in microelectromechanical systems. ASME J. Tribol.microtribology for microelectromechanical systems. Wear 200,forces in microelectromechanical systems: mechanisms,
Song, Zhichao
2012-01-01
surface adhesion in microelectromechanical systems. ASME J.microtribology for microelectromechanical systems. Wear 200,forces in microelectromechanical systems: mechanisms,
High strain-rate model for fiber-reinforced composites
Aidun, J.B.; Addessio, F.L.
1995-07-01
Numerical simulations of dynamic uniaxial strain loading of fiber-reinforced composites are presented that illustrate the wide range of deformation mechanisms that can be captured using a micromechanics-based homogenization technique as the material model in existing continuum mechanics computer programs. Enhancements to the material model incorporate high strain-rate plastic response, elastic nonlinearity, and rate-dependent strength degradation due to material damage, fiber debonding, and delamination. These make the model relevant to designing composite structural components for crash safety, armor, and munitions applications.
Generating coherent broadband continuum soft-x-ray radiation by
Neumark, Daniel M.
Generating coherent broadband continuum soft-x-ray radiation by attosecond ionization gating Thomas as the driver for high-harmonic generation that has a cosine-like electric field stabilized with respect the generation of broadband and tunable attosecond pulses. Instead of fixing the carrier-envelope phase
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
nrel.gov/continuum Issue 4 More than a Dream
nrel.gov/continuum Issue 4 LeadsNREL More than a Dream A Living Laboratory for Integrated Systems Integration NREL is a national laboratory of the U.S. Department of Energy, Office of Energy the Clean Energy Spectrum This summer NREL will officially open the largest and most sophisticated
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
ionization: Stratified symmetrical electron emission and resonantly structured ionization continuum
Kaplan, Alexander
ionization: Stratified symmetrical electron emission and resonantly structured ionization continuum, ionization produces an approximately symmetrical, stratified photoelectron cloud. S1050-2947 99 09701-2 PACS the pulse are related simply as exp (ieQ/ ) rj 0 , where the sum is taken over all the charged particles
Resonant continuum in the Hartree-Fock+BCS approximation
Sandulescu, N; Liotta, R J; Giai, Nguyen Van
2000-01-01
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.
Mechanical Engineering ME 3720 FLUID MECHANICS
Panchagnula, Mahesh
Mechanical Engineering ME 3720 FLUID MECHANICS Pre-requisite: ME 2330 Co-requisite: ME 3210) to develop an understanding of the physical mechanisms and the mathematical models of fluid mechanics of fluid mechanics problems in engineering practice. The basic principles of fluid mechanics
CODY: Continuum Dynamics Evaluation and Test Suite
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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 OutreachProductswsicloudwsiclouddenDVA N C E D B LReports from the Cloud Modeling WorkingNationalCNSSCOAL
The ramifications of diffusive volume transport in classical fluid mechanics
Bielenberg, James R. (James Ronald), 1976-
2004-01-01
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 ...
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)
2014-11-15
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.
Laubie, Hadrien Hyacinthe
2013-01-01
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 ...
Onishi, Y.; Serne, R.J.; Arnold, E.M.; Cowan, C.E.; Thompson, F.L.
1981-01-01
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.
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.
2013-12-26
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.
Sierra/solid mechanics 4.22 user's guide.
Thomas, Jesse David
2011-10-01
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.
Lyakhovsky, Vladimir
Mechanical modeling and InSAR measurements of Mount Sedom uplift, Dead Sea basin: Implications of predicted profiles: topography, uplift rate, and shear strain. The present topography of Mount Sedom stage and at the Plio-Pleistocene pre-emergent stage of the Sedom diapir, respectively. The uplift
Neumaier, Arnold
Proceedings in Applied Mathematics and Mechanics, 15 October 2007 Uncertainty modeling in autonomous robust spacecraft system design Martin Fuchs1 , Arnold Neumaier1 , and Daniela Girimonte2 1 system engineers or even of completely automated design methods capturing the reasoning of the system
Ritchie, Robert
. For the hydrogen economy to be fully realized though, efficient hydrogen storage and transportation, for exampleA statistical, physical-based, micro-mechanical model of hydrogen-induced intergranular fracture 2009 Received in revised form 10 September 2009 Accepted 17 October 2009 Keywords: Hydrogen
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
Gan, Yixiang; Kamlah, Marc
2008-07-01
In this investigation, a thermo-mechanical model of pebble beds is adopted and developed based on experiments by Dr. Reimann at Forschungszentrum Karlsruhe (FZK). The framework of the present material model is composed of a non-linear elastic law, the Drucker-Prager-Cap theory, and a modified creep law. Furthermore, the volumetric inelastic strain dependent thermal conductivity of beryllium pebble beds is taken into account and full thermo-mechanical coupling is considered. Investigation showed that the Drucker-Prager-Cap model implemented in ABAQUS can not fulfill the requirements of both the prediction of large creep strains and the hardening behaviour caused by creep, which are of importance with respect to the application of pebble beds in fusion blankets. Therefore, UMAT (user defined material's mechanical behaviour) and UMATHT (user defined material's thermal behaviour) routines are used to re-implement the present thermo-mechanical model in ABAQUS. An elastic predictor radial return mapping algorithm is used to solve the non-associated plasticity iteratively, and a proper tangent stiffness matrix is obtained for cost-efficiency in the calculation. An explicit creep mechanism is adopted for the prediction of time-dependent behaviour in order to represent large creep strains in high temperature. Finally, the thermo-mechanical interactions are implemented in a UMATHT routine for the coupled analysis. The oedometric compression tests and creep tests of pebble beds at different temperatures are simulated with the help of the present UMAT and UMATHT routines, and the comparison between the simulation and the experiments is made. (authors)
Colloquium: Mechanical formalisms for tissue dynamics
Sham Tlili; Cyprien Gay; Francois Graner; Philippe Marcq; François Molino; Pierre Saramito
2015-09-29
The understanding of morphogenesis in living organisms has been renewed by tremendous progressin experimental techniques that provide access to cell-scale, quantitative information both on theshapes of cells within tissues and on the genes being expressed. This information suggests that ourunderstanding of the respective contributions of gene expression and mechanics, and of their crucialentanglement, will soon leap forward. Biomechanics increasingly benefits from models, which assistthe design and interpretation of experiments, point out the main ingredients and assumptions, andultimately lead to predictions. The newly accessible local information thus calls for a reflectionon how to select suitable classes of mechanical models. We review both mechanical ingredientssuggested by the current knowledge of tissue behaviour, and modelling methods that can helpgenerate a rheological diagram or a constitutive equation. We distinguish cell scale ("intra-cell")and tissue scale ("inter-cell") contributions. We recall the mathematical framework developpedfor continuum materials and explain how to transform a constitutive equation into a set of partialdifferential equations amenable to numerical resolution. We show that when plastic behaviour isrelevant, the dissipation function formalism appears appropriate to generate constitutive equations;its variational nature facilitates numerical implementation, and we discuss adaptations needed in thecase of large deformations. The present article gathers theoretical methods that can readily enhancethe significance of the data to be extracted from recent or future high throughput biomechanicalexperiments.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Bouskill, N. J.; Riley, W. J.; Tang, J. Y.
2014-12-11
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
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
Bradonjic, Milan [Los Alamos National Laboratory
2009-01-01
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.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Bouskill, N. J.; Riley, W. J.; Tang, J.
2014-08-18
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
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
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
MECHANICAL TEST RESULTS ON DIPOLE MODEL C-l 25 mm ALUMINUM COLLARS
Peters, C.
2010-01-01
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
Villanueva, Joshua; Huang, Qian; Sirbuly, Donald J.
2014-09-14
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.
Linearized Perturbations of a Black Hole: Continuum Spectrum
P. T. Leung; Alec Maassen_van_den_Brink; K. W. Mak; K. Young
2003-07-08
Linearized perturbations of a Schwarzschild black hole are described, for each angular momentum $\\ell$, by the well-studied discrete quasinormal modes (QNMs), and in addition a continuum. The latter is characterized by a cut strength $q(\\gamma>0)$ for frequencies $\\omega = -i\\gamma$. We show that: (a) $q(\\gamma\\downarrow0) \\propto \\gamma$, (b) $q(\\Gamma) = 0$ at $\\Gamma = (\\ell+2)!/[6(\\ell-2)!]$, and (c) $q(\\gamma)$ oscillates with period $\\sim 1$ ($2M\\equiv1$). For $\\ell=2$, a pair of QNMs are found beyond the cut on the unphysical sheet very close to $\\Gamma$, leading to a large dipole in the Green's function_near_ $\\Gamma$. For a source near the horizon and a distant observer, the continuum contribution relative to that of the QNMs is small.
NREL Leads Energy Systems Integration, Continuum Magazine: Issue 4 (Book)
Not Available
2013-04-01
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.
Continuum particle-vibration coupling method in coordinate-space representation for finite nuclei
Kazuhito Mizuyama; Gianluca Colò; Enrico Vigezzi
2012-05-04
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.
Kronenberg, A.K.; Russell, J.E.; Carter, N.L.; Mazariegos, R.; Ibanez, W.
1993-06-01
Specific goals and accomplishments of this research include: (1) The evaluation of models of salt diaper ascent that involve either power law, dislocation creep as determined experimentally by Horseman et al. (1993) or linear, fluid-assisted creep as reported by Spiers et al. (1988, 1990, 1992). We have compared models assuming these two, experimentally evaluated flow laws and examined the predictions they make regarding diaper incubation periods, ascent velocities, deviatoric stresses and strain rates. (2) The evaluation of the effects of differential loading on the initiation an of salt structures. (3) Examination of the role of basement faults on the initiation and morphologic evolution of salt structures. (4) Evaluation of the mechanical properties of shale as a function of pressure and determination of the nature of its brittle-ductile transition. (5) Evaluation of the mechanical anisotropies of shales with varying concentrations, distributions and preferred orientations of clay. (6) The determination of temperature and ratedependencies of strength for a shale constitutive model that can be used in numerical models that depend on viscous formulations. (7) Determination of the mechanisms of deformation for argillaceous rocks over awide range of conditions. (8) Evaluation of the effects of H{sub 2}O within clay interlayers, as adsorbed surface layers.
Continuum extrapolation of energies of a four-quark system in lattice gauge theory
Petrus Pennanen
1997-01-12
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.
Continuum limits of atomistic energies allowing smooth and sharp interfaces in 1D Elasticity
Carlos Mora-Corral
2008-08-15
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.
Mechanism-based constitutive modeling of L1? single-crystal plasticity
Yin, Yuan, 1977-
2006-01-01
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 ...
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 ...
Wee, Brian (Brian J.)
2013-01-01
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 ...
3D Modeling of Coupled Rock Deformation and Thermo-Poro-Mechanical Processes in Fractures
Rawal, Chakra
2012-07-16
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...
Lu, Yihong C. S
2010-01-01
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 ...
Mechanical characterization and modelling of the heavy tungsten allow IT180
Scapin, M
2015-01-01
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.
Logue, J. M.; Turner, W. J.N.; Walker, I. S.; Singer, B. C.
2015-07-01
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.
Daniel Brown
2006-03-24
An analysis is made of a moving disturbance using a directed cyclic graph. A statistical approach is used to calculate the alternative positions in space and state of the disturbance with a defined observed time. The probability for a freely moving entity interacting in a particular spatial position is calculated and a formulation is derived for the minimum locus of uncertainty in position and momentum. This is found to accord with calculations for quantum mechanics. The model has proven amenable to computer modelling; a copy of the "SimulTime" program is available on request.
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
Mitchell, John Anthony; Epp, David S.; Wittwer, Jonathan W.
2005-10-01
Damping vibrations is important in the design of some types of inertial sensing devices. One method for adding damping to a device is to use magnetic forces generated by a static magnetic field interacting with eddy currents. In this report, we develop a 2-dimensional finite element model for the analysis of quasistatic eddy currents in a thin sheet of conducting material. The model was used for design and sensitivity analyses of a novel mechanical oscillator that consists of a shuttle mass (thin sheet of conducting material) and a set of folded spring elements. The oscillator is damped through the interaction of a static magnetic field and eddy currents in the shuttle mass. Using a prototype device and Laser Dopler Velocimetry (LDV), measurements were compared to the model in a validation study using simulation based uncertainty analyses. Measurements were found to follow the trends predicted by the model.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Anand, M.; Rajagopal, K.; Rajagopal, K. R.
2003-01-01
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
R. Fedele; M. A. Man'ko; V. I. Man'ko; V. G. Vaccaro
2002-07-30
It is shown that the transmission line technology can be suitably used for simulating quantum mechanics. Using manageable and at the same time non-expensive technology, several quantum mechanical problems can be simulated for significant tutorial purposes. The electric signal envelope propagation through the line is governed by a Schrodinger-like equation for a complex function, representing the low-frequency component of the signal, In this preliminary analysis, we consider two classical examples, i.e. the Frank-Condon principle and the Ramsauer effect.
NOTES ON THE KIVA-II SOFTWARE AND CHEMICALLY REACTIVE FLUID MECHANICS
Holst, Michael J.
NOTES ON THE KIVA-II SOFTWARE AND CHEMICALLY REACTIVE FLUID MECHANICS MICHAEL J. HOLST Numerical, California #12;NOTES ON THE KIVA-II SOFTWARE AND CHEMICALLY REACTIVE FLUID MECHANICS Michael J. Holst intro- duction to continuum mechanics, to fluid mechanics, and to the mechanics of chemically reactive
Black Hole Spin via Continuum Fitting and the Role of Spin in Powering Transient Jets
Jeffrey E. McClintock; Ramesh Narayan; James F. Steiner
2013-06-28
The spins of ten stellar black holes have been measured using the continuum-fitting method. These black holes are located in two distinct classes of X-ray binary systems, one that is persistently X-ray bright and another that is transient. Both the persistent and transient black holes remain for long periods in a state where their spectra are dominated by a thermal accretion disk component. The spin of a black hole of known mass and distance can be measured by fitting this thermal continuum spectrum to the thin-disk model of Novikov and Thorne; the key fit parameter is the radius of the inner edge of the black hole's accretion disk. Strong observational and theoretical evidence links the inner-disk radius to the radius of the innermost stable circular orbit, which is trivially related to the dimensionless spin parameter a_* of the black hole (|a_*| 0.95. The robustness of the method is demonstrated by the dozens or hundreds of independent and consistent measurements of spin that have been obtained for several black holes, and through careful consideration of many sources of systematic error. Among the results discussed is a dichotomy between the transient and persistent black holes; the latter have higher spins and larger masses. Also discussed is recently discovered evidence in the transient sources for a correlation between the power of ballistic jets and black hole spin.
Improved microscopic-macroscopic approach incorporating the effects of continuum states
Tajima, Naoki; Takahara, Satoshi
2010-01-01
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...
Development of a model to calculate mechanical specific energy for air hammer drilling systems
Okuchaba, Boma Jeremiah
2009-05-15
drilling time could be reduced. Real-time monitoring of Mechanical Specific Energy will enable drilling engineers to detect when the optimum drilling rate for a given set of drilling parameters is not being achieved. Numerous works have been done on air...
International Journal of Applied Mechanics Vol. 1, No. 3 (2009) 443467
Huang, Rui
2009-01-01
, the bending modulus of graphene is obtained. Buckling of graphene ribbons under uniaxial compression drawn tremendous interests recently. By combining continuum and atomistic approaches, this paper of nonlinear continuum mechanics is developed for graphene under both in-plane and bend- ing deformation
Andersohn, Alexander
2013-08-27
-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...
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...
Jung, Yong-Woon; Mascagni, Michael
2014-09-28
We developed a model describing the structure and contractile mechanism of the actomyosin ring in fission yeast, Schizosaccharomyces pombe. The proposed ring includes actin, myosin, and ?-actinin, and is organized into a structure similar to that of muscle sarcomeres. This structure justifies the use of the sliding-filament mechanism developed by Huxley and Hill, but it is probably less organized relative to that of muscle sarcomeres. Ring contraction tension was generated via the same fundamental mechanism used to generate muscle tension, but some physicochemical parameters were adjusted to be consistent with the proposed ring structure. Simulations allowed an estimate of ring constriction tension that reproduced the observed ring constriction velocity using a physiologically possible, self-consistent set of parameters. Proposed molecular-level properties responsible for the thousand-fold slower constriction velocity of the ring relative to that of muscle sarcomeres include fewer myosin molecules involved, a less organized contractile configuration, a low ?-actinin concentration, and a high resistance membrane tension. Ring constriction velocity is demonstrated as an exponential function of time despite a near linear appearance. We proposed a hypothesis to explain why excess myosin heads inhibit constriction velocity rather than enhance it. The model revealed how myosin concentration and elastic resistance tension are balanced during cytokinesis in S. pombe.
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
Assessing continuum postulates in simulations of granular flow
Rycroft, Chris
2009-01-01
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
NUMERICAL MODELING FOR THE FORMATION MECHANISM OF 3D TOPOGRAPHY ON MICROBIAL MAT SURFACES
Patel, Harsh Jay
2013-09-27
a node in the fluid to solid (aggregate or the particle) ? b number of discrete velocities 14 In order to stochastically solve the stochastic solute diffusion equation (Eq. 6), initial and boundary conditions are specified before solving...) Model........................................... 1.2.2 The Diffusion Limited Aggregation-Cellular Automata (DLA-CA) Model................................................................................................ 1.2.3 The Reaction-Diffusion...
ES2A7 -Fluid Mechanics Example Classes Model Answers to Example Questions (Set II)
Thomas, Peter J.
of msvp = 2 -1 . Calculate the mean model wind tunnel speed if the model is made to 1/10 scale. Assume in a wind tunnel. The airspeed range to be investigated is at the docking end of its range, a maximum -=-=-= --- Question 4: Sliding Board #12;A board with an area slides down an inclined ramp as is schematically
Broader source: Energy.gov [DOE]
NREL, under the Physics of Reliability: Evaluating Design Insights for Component Technologies in Solar (PREDICTS) Program will be developing a physics-based computational degradation model to assess the kinetic oxidation rates; realistic model light attenuation and transport; and multi-layer treatment with variable properties Simulation based experimental design.
Burnham, A K; Gee, R; Maiti, A; Qiu, R; Rajasekar, P; Weeks, B; Zepeda-Ruiz, L
2005-11-03
Experimental measurements suggest that pentaerythritoltetranitrate (PETN) undergoes changes at the molecular level that cause macroscopic changes in the overall PETN powder characteristics over time. These changes have been attributed to the high molecular mobility of PETN, but the underlying mechanism(s) responsible for this redistribution are still uncertain. Two basic approaches have been implemented in the past year to provide insight into the nature of these underlying mechanisms. The first approach is of an experimental nature, utilizing both AFM and evaporation measurements, which address both surface mobility and evaporation. These data include AFM measurements performed at LLNL and evaporation rate measurements performed at Texas Tech. These results are compared to earlier vapor pressure measurements performed at SNL, and estimates of recrystallization time frames are given. The second approach utilizes first-principle calculations and simulations that will be used to compare directly to those experimental quantities measured. We are developing an accurate intermolecular potential for PETN, which via kinetic Monte Carlo (KMC) simulations would mimic real crystallite shapes. Once the basic theory is in place for the growth of single crystallites, we will be in a position to investigate realistic grain coarsening phenomena in multi-crystallite simulations. This will also enable us to study how to control the morphological evolution, e.g., through thermal cycling, or through the action of custom additives and impurities.
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
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)
2014-05-28
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.
Wave-packet continuum discretization for quantum scattering
O. A. Rubtsova; V. I. Kukulin; V. N. Pomerantsev
2015-01-15
A general approach to a solution of few- and many-body scattering problems based on a continuum-discretization procedure is described in detail. The complete discretization of continuous spectrum is realized using stationary wave packets which are the normalized states constructed from exact non-normalized continuum states. Projecting the wave functions and all scattering operators like $t$-matrix, resolvent, etc. on such a wave-packet basis results in a formulation of quantum scattering problem entirely in terms of discrete elements and linear equations with regular matrices. It is demonstrated that there is a close relation between the above stationary wave packets and pseudostates which are employed often to approximate the scattering states with a finite $L_2$ basis. Such a fully discrete treatment of complicated few- and many-body scattering problems leads to significant simplification of their practical solution. Also we get finite-dimensional approximations for complicated operators like effective interactions between composite particles constructed via the Feshbach-type projection formalism. As illustrations to this general approach we consider several important particular problems including multichannel scattering and scattering in the three-nucleon system within the Faddeev framework.
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)
2014-05-28
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
Derivation of Newton's Law of Gravitation Based on a Fluid Mechanical Singularity Model of Particles
Xiao-Song Wang
2006-10-25
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.
Song, Zhichao
2012-01-01
Greenwood, J.A. , 1997. Adhesion of elastic spheres. Proc.to the Maugis model of adhesion between elastic spheres. J.determination of interfacial adhesion properties by wedge
A Mechanical Fluid-Dynamical Model For Ground Movements At Campi...
The most important roles in the proposed model are played by the effect of lateral stress-strain discontinuities marking the inner caldera borders and by the response of the...
Lester, Brian T
2015-08-25
the local and global responses of this system with an emphasis on the response of these composites to thermal loadings. First, the effective transformation characteristics of SMA composites with a stiff, elastic matrix are modeled using an efficient...
Heydarkhan Tehrani, Ardeshir
2013-08-26
of such numerical studies are based on characterizing the MNPCs through simple microstructures, as circular particles or straight fibers embedded in a specific polymer matrix. Although these geometries are effective in virtual modeling some types of composite...
Particle-scale CO2 adsorption kinetics modeling considering three reaction mechanisms
Suh, Dong-Myung; Sun, Xin
2013-09-01
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
2004-02-19
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.
Central engines of Gamma Ray Bursts. Magnetic mechanism in the collapsar model
Maxim V. Barkov; Serguei S. Komissarov
2008-09-08
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
Evans, James W. [Ames Laboratory; Liu, Da-Jiang [Ames Laboratory
2014-05-20
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)
2014-05-21
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.
Skinner, F. K.; Department of Medicine , University of Toronto, 200 Elizabeth Street, Toronto, Ontario M5G 2C4; Department of Physiology, University of Toronto Medical Sciences Building, 3rd Floor, 1 King's College Circle, Toronto, Ontario M5S 1A8 ; Ferguson, K. A.; Department of Physiology, University of Toronto Medical Sciences Building, 3rd Floor, 1 King's College Circle, Toronto, Ontario M5S 1A8
2013-12-15
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.
Statistical Mechanics of Two-dimensional Foams: Physical Foundations of the Model
Marc Durand
2015-07-16
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.
On the use of Extreme Value Theory in analyses of continuum gamma decay
Garcia-Ruiz, R. F.; Cristancho, F.
2010-08-04
Extreme Value theory seems to be a promising tool for analysing experimental continuum gamma decay spectra in order to obtain physical parameters at high excitation energy.
Barker, Erin I.; Choi, Kyoo Sil; Sun, Xin; Deda, Erin; Allison, John; Li, Mei; Forsmark, Joy; Zindel, Jacob; Godlewski, Larry
2014-09-30
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.
Persistent energy flow for a stochastic wave equation model in nonequilibrium statistical mechanics
Lawrence E. Thomas
2012-04-29
We consider a one-dimensional partial differential equation system modeling heat flow around a ring. The system includes a Klein-Gordon wave equation for a field satisfying spatial periodic boundary conditions, as well as Ornstein-Uhlenbeck stochastic differential equations with finite rank dissipation and stochastic driving terms modeling heat baths. There is an energy flow around the ring. In the case of a linear field with different (fixed) bath temperatures, the energy flow can persist even when the interaction with the baths is turned off. A simple example is given.
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)
2014-05-07
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.
Small-energy series for one-dimensional quantum-mechanical models with non-symmetric potentials
Paolo Amore; Francisco M. Fernández
2014-10-21
We generalize a recently proposed small-energy expansion for one-dimensional quantum-mechanical models. The original approach was devised to treat symmetric potentials and here we show how to extend it to non-symmetric ones. Present approach is based on matching the logarithmic derivatives for the left and right solutions to the Schr\\"odinger equation at the origin (or any other point chosen conveniently) . As in the original method, each logarithmic derivative can be expanded in a small-energy series by straightforward perturbation theory. We test the new approach on four simple models, one of which is not exactly solvable. The perturbation expansion converges in all the illustrative examples so that one obtains the ground-state energy with an accuracy determined by the number of available perturbation corrections.
Ã?agin, Tahir
1 Presented at the 27th Leeds-Lyon Symposium on Tribology, Tribological Research: From Model Experiment to Industrial Problems: Mechanics, Materials Science, Physico-chemistry Lyon, France, September 5
Welch, Stephen; Miles, Steward; Kumar, Suresh; Lemaire, Tony; Chan, Alan
A hierarchy of coupling strategies for integrating advanced three-dimensional modelling methodologies for prediction of the thermo-mechanical response of structures in fire has been developed and systematically assessed. ...
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)
2012-11-01
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.
A quantum mechanical model for the relationship between stock price and stock ownership
Liviu-Adrian Cotfas
2012-09-05
The trade of a fixed stock can be regarded as the basic process that measures its momentary price. The stock price is exactly known only at the time of sale when the stock is between traders, that is, only in the case when the owner is unknown. We show that the stock price can be better described by a function indicating at any moment of time the probabilities for the possible values of price if a transaction takes place. This more general description contains partial information on the stock price, but it also contains partial information on the stock owner. By following the analogy with quantum mechanics, we assume that the time evolution of the function describing the stock price can be described by a Schrodinger type equation.
Melanin, a promising radioprotector: Mechanisms of actions in a mice model
Kunwar, A.; Adhikary, B.; Jayakumar, S.; Barik, A.; Chattopadhyay, S.; Raghukumar, S.; Priyadarsini, K.I.
2012-10-15
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
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.
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
SEACAS Theory Manuals: Part III. Finite Element Analysis in Nonlinear Solid Mechanics
Laursen, T.A.; Attaway, S.W.; Zadoks, R.I.
1999-03-01
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.
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
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
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
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
2015-07-13
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.
Nguyen, Ba Nghiep; Kunc, Vlastimil; Jin, Xiaoshi; Tucker III, Charles L.; Costa, Franco
2013-12-18
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.
J. Froehlich; M. Griesemer; B. Schlein
2000-09-27
In models of (non-relativistic and pseudo-relativistic) electrons interacting with static nuclei and with the (ultraviolet-cutoff) quantized radiation field, the existence of asymptotic electromagnetic fields is established. Our results yield some mathematically rigorous understanding of Rayleigh scattering and of the phenomenon of relaxation of isolated atoms to their ground states. Our proofs are based on propagation estimates for electrons inspired by similar estimates known from $N$-body scattering theory.
Cances, Benjamin; Benedetti, Marc; Farges, Francois; Brown, Gordon E. Jr.
2007-02-02
Gold is a highly valuable metal that can concentrate in iron-rich exogenetic horizons such as laterites. An improved knowledge of the retention mechanisms of gold onto highly reactive soil components such as iron oxy-hydroxides is therefore needed to better understand and predict the geochemical behavior of this element. In this study, we use EXAFS information and titration experiments to provide a realistic thermochemical description of the sorption of trivalent gold onto iron oxy-hydroxides. Analysis of Au LIII-edge XAFS spectra shows that aqueous Au(III) adsorbs from chloride solutions onto goethite surfaces as inner-sphere square-planar complexes (Au(III)(OH,Cl)4), with dominantly OH ligands at pH > 6 and mixed OH/Cl ligands at lower pH values. In combination with these spectroscopic results, Reverse Monte Carlo simulations were used to constraint the possible sorption sites on the surface of goethite. Based on this structural information, we calculated sorption isotherms of Au(III) on Fe oxy-hydroxides surfaces, using the CD-MUSIC (Charge Distribution - MUlti SIte Complexation) model. The various Au(III)-sorbed species were identified as a function of pH, and the results of these EXAFS+CD-MUSIC models are compared with titration experiments. The overall good agreement between the predicted and measured structural models shows the potential of this combined approach to better model sorption processes of transition elements onto highly reactive solid surfaces such as goethite and ferrihydrite.
Ozcelik, Ozgur
2008-01-01
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.
2000-11-01
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.
Probing the quantum phase transition in the Dicke model through mechanical vibrations
J. P. Santos; K. Furuya; F. L. Semião
2011-03-04
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.
Adsorption of small weak organic acids on goethite: Modeling of mechanisms
Filius, J.D.; Hiemstra, T.; Riemsdijk, W.H. Van
1997-11-15
The adsorption of lactate, oxalate, malonate, phthalate, and citrate has been determined experimentally as a function of concentration, pH, and ionic strength. The data have been described with the CD-MUSIC model of Hiemstra and Van Riemsdijk which allows a distribution of charge of the organic molecule over the surface and the Stern layer. Simultaneously, the concentration, pH, and salt dependency as well as the basic charging behavior of goethite could be described well. On the basis of model calculations, a distinction is made between inner and outer sphere complexation of weak organic acids by goethite. The results indicate that the affinity of the organic acids is dominated by the electrostatic attraction. The intrinsic affinity constants for the exchange reaction of surface water groups and organic acids, expressed per bond, increases with increasing number of reactive groups on the organic molecule. Ion pair formation between noncoordinated carboxylic groups of adsorbed organic acids and cations of the background electrolyte proved to be important for the salt dependency. The knowledge obtained may contribute to the interpretation of the binding of larger organic acids like fulvic and humic acids.
Salloum, Maher N.; Shugard, Andrew D.; Kanouff, Michael P.; Gharagozloo, Patricia E.
2013-03-01
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.
A Mathematical Analysis of Atomistic-to-Continuum (AtC) Multiscale Coupling Methods
Gunzburger, Max
2013-11-13
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.
Rodriguez, David
2011-01-01
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.
Juneja, Prabhjot; Harris, Emma J.; Kirby, Anna M.; Evans, Philip M.
2012-11-01
Purpose: To validate and compare the accuracy of breast tissue segmentation methods applied to computed tomography (CT) scans used for radiation therapy planning and to study the effect of tissue distribution on the segmentation accuracy for the purpose of developing models for use in adaptive breast radiation therapy. Methods and Materials: Twenty-four patients receiving postlumpectomy radiation therapy for breast cancer underwent CT imaging in prone and supine positions. The whole-breast clinical target volume was outlined. Clinical target volumes were segmented into fibroglandular and fatty tissue using the following algorithms: physical density thresholding; interactive thresholding; fuzzy c-means with 3 classes (FCM3) and 4 classes (FCM4); and k-means. The segmentation algorithms were evaluated in 2 stages: first, an approach based on the assumption that the breast composition should be the same in both prone and supine position; and second, comparison of segmentation with tissue outlines from 3 experts using the Dice similarity coefficient (DSC). Breast datasets were grouped into nonsparse and sparse fibroglandular tissue distributions according to expert assessment and used to assess the accuracy of the segmentation methods and the agreement between experts. Results: Prone and supine breast composition analysis showed differences between the methods. Validation against expert outlines found significant differences (P<.001) between FCM3 and FCM4. Fuzzy c-means with 3 classes generated segmentation results (mean DSC = 0.70) closest to the experts' outlines. There was good agreement (mean DSC = 0.85) among experts for breast tissue outlining. Segmentation accuracy and expert agreement was significantly higher (P<.005) in the nonsparse group than in the sparse group. Conclusions: The FCM3 gave the most accurate segmentation of breast tissues on CT data and could therefore be used in adaptive radiation therapy-based on tissue modeling. Breast tissue segmentation methods should be used with caution in patients with sparse fibroglandular tissue distribution.
Invariants in Supersymmetric Classical Mechanics
A. Alonso Izquierdo; M. A. Gonzalez Leon; J. Mateos Guilarte
2000-04-07
The bosonic second invariant of SuperLiouville models in supersymmetric classical mechanics is described.
Zhai, Yuhu
2013-07-16
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.
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
2014-11-08
We have made a number of developments in the regional coupled model WRF-Chem, with the aim of making the model more suitable for prediction of atmospheric composition and of interactions between air quality and weather. We have worked on the European domain, with a particular focus on making the model suitable for the study of night time chemistry and oxidation by the nitrate radical in the UK atmosphere. A reduced form of the Common Reactive Intermediates gas-phase chemical mechanism (CRIv2-R5) has been implemented to enable more explicit simulation of VOC degradation. N2O5 heterogeneous chemistry has been added to the existing sectional MOSAIC aerosol module, and coupled to both the CRIv2-R5 and existing CBM-Z gas phase scheme. Modifications have also been made to the sea-spray aerosol emission representation, allowing the inclusion of primary organic material in sea-spray aerosol. Driven by appropriate emissions, wind fields and chemical boundary conditions, implementation of the different developments is illustrated in order to demonstrate the impact that these changes have in the North-West European domain. These developments are now part of the freely available WRF-Chem distribution.
Robert Podgorney; Chuan Lu; Hai Huang
2012-01-01
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.
2015-08-01
This issue of Continuum Magazine covers the depth and breadth of NREL's ever-expanding analytical capabilities. For example, in one project we are leading national efforts to create a computer model of one of the most complex systems ever built. This system, the eastern part of the North American power grid, will likely host an increasing percentage of renewable energy in years to come. Understanding how this system will work is important to its success - and NREL analysis is playing a major role. We are also identifying the connections among energy, the environment and the economy through analysis that will point us toward a 'water smart' future.
Is the Higgs Mechanism of Fermion Mass Generation a Fact? A Yukawa-less First-Two-Generation Model
Diptimoy Ghosh; Rick Sandeepan Gupta; Gilad Perez
2015-08-06
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.
Mechanical Properties and Plasticity of a Model Glass Loaded Under Stress Control
Vladimir Dailidonis; Valery Ilyin; Pankaj Mishra; Itamar Procaccia
2014-06-09
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.
Cances, Benjamin; Benedetti, Marc; Farges, Francois; Brown, Gordon E.., Jr.; /Stanford U., Geo. Environ. Sci. /SLAC, SSRL
2006-12-13
Gold is a highly valuable metal that can concentrate in iron-rich exogenetic horizons such as laterites. An improved knowledge of the retention mechanisms of gold onto highly reactive soil components such as iron oxyhydroxides is therefore needed to better understand and predict the geochemical behavior of this element. In this study, we use EXAFS information and titration experiments to provide a realistic thermochemical description of the sorption of trivalent gold onto iron oxy-hydroxides. Analysis of Au L{sub III}-edge XAFS spectra shows that aqueous Au(III) adsorbs from chloride solutions onto goethite surfaces as inner-sphere square-planar complexes (Au(III)(OH,Cl){sub 4}), with dominantly OH ligands at pH > 6 and mixed OH/Cl ligands at lower pH values. In combination with these spectroscopic results, Reverse Monte Carlo simulations were used to constraint the possible sorption sites on the surface of goethite. Based on this structural information, we calculated sorption isotherms of Au(III) on Fe oxy-hydroxides surfaces, using the CD-MUSIC (Charge Distribution--Multi Site Complexation) model. The various Au(III)-sorbed species were identified as a function of pH, and the results of these EXAFS+CD-MUSIC models are compared with titration experiments. The overall good agreement between the predicted and measured structural models shows the potential of this combined approach to better model sorption processes of transition elements onto highly reactive solid surfaces such as goethite and ferrihydrite.
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
of continuum robot that uses a series of concentric, precurved super- elastic tubes (typically made of nitinol
Li, Yangmin
2014-01-01
-based proportion compliant mechanisms. Precis Eng (2014), http://dx.doi.org/10.1016/j.precisioneng.2013 analytical model for flexure-based proportion compliant mechanisms Qiaoling Menga , Yangmin Lia,b, , Jia Xua model for flexure-based proportion compliant mechanisms. The displacement and stiffness calculations
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 ...
Ding Yang; Ligang Cao; Zhongyu Ma
2013-09-03
Journal of Combinatorial Theory, Series B, 98(1):173-225, 2008n exotic nuclei are studied in the framework of a fully self-consistent relativistic continuum random phase approximation (RCRPA). In this method the contribution of the continuum spectrum to nuclear excitations is treated exactly by the single particle Green's function. Different from the cases in stable nuclei, there are strong low-energy excitations in neutron-rich nuclei and proton-rich nuclei. The neutron or proton excess pushes the centroid of the strength function to lower energies and increases the fragmentation of the strength distribution. The effect of treating the contribution of continuum exactly are also discussed.
Liu, H.H.
2012-01-01
Strength and elasto-plastic properties of non- industrialplastic regimes. The impact of damage on mechanical and hydraulic properties
Schlegel, Nicole-Jeanne
2011-01-01
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-
Low Energy Continuum and Lattice Effective Field Theories
Serdar Elhatisari
2014-09-14
In the first part of the thesis we consider the constraints of causality and unitarity for particles interacting via strictly finite-range interactions. We generalize Wigner's causality bound to the case of non-vanishing partial-wave mixing. Specifically we analyze the system of the low-energy interactions between protons and neutrons. We also analyze low-energy scattering for systems with arbitrary short-range interactions plus an attractive $1/r^{\\alpha}$ tail for $\\alpha\\geq2$. In particular, we focus on the case of $\\alpha=6$ and we derive the constraints of causality and unitarity also for these systems and find that the van der Waals length scale dominates over parameters characterizing the short-distance physics of the interaction. This separation of scales suggests a separate universality class for physics characterizing interactions with an attractive $1/r^{6}$ tail. We argue that a similar universality class exists for any attractive potential $1/r^{\\alpha}$ for $\\alpha\\geq2$. In the second part of the thesis we present lattice Monte Carlo calculations of fermion-dimer scattering in the limit of zero-range interactions using the adiabatic projection method. The adiabatic projection method uses a set of initial cluster states and Euclidean time projection to give a systematically improvable description of the low-lying scattering cluster states in a finite volume. We use L\\"uscher's finite-volume relations to determine the $s$-wave, $p$-wave, and $d$-wave phase shifts. For comparison, we also compute exact lattice results using Lanczos iteration and continuum results using the Skorniakov-Ter-Martirosian equation. For our Monte Carlo calculations we use a new lattice algorithm called impurity lattice Monte Carlo. This algorithm can be viewed as a hybrid technique which incorporates elements of both worldline and auxiliary-field Monte Carlo simulations.
Gradient Plasticity Model and its Implementation into MARMOT
Barker, Erin I.; Li, Dongsheng; Zbib, Hussein M.; Sun, Xin
2013-08-01
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.
Expectations for the hard x-ray continuum and gamma-ray line...
Office of Scientific and Technical Information (OSTI)
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 56Ni yield...
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
Philippe Laurent; Lev Titarchuk
2006-11-06
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.
Probing primordial non-Gaussianity via iSW measurements with SKA continuum surveys
Raccanelli, Alvise; Doré, Olivier E-mail: olivier.dore@caltech.edu; Bacon, David J.; Maartens, Roy E-mail: roy.maartens@gmail.com; and others
2015-01-01
The Planck CMB experiment has delivered the best constraints so far on primordial non-Gaussianity, ruling out early-Universe models of inflation that generate large non-Gaussianity. Although small improvements in the CMB constraints are expected, the next frontier of precision will come from future large-scale surveys of the galaxy distribution. The advantage of such surveys is that they can measure many more modes than the CMB—in particular, forthcoming radio surveys with the Square Kilometre Array will cover huge volumes. Radio continuum surveys deliver the largest volumes, but with the disadvantage of no redshift information. In order to mitigate this, we use two additional observables. First, the integrated Sachs-Wolfe effect—the cross-correlation of the radio number counts with the CMB temperature anisotropies—helps to reduce systematics on the large scales that are sensitive to non-Gaussianity. Second, optical data allows for cross-identification in order to gain some redshift information. We show that, while the single redshift bin case can provide a ?(f{sub NL}) ? 20, and is therefore not competitive with current and future constraints on non-Gaussianity, a tomographic analysis could improve the constraints by an order of magnitude, even with only two redshift bins. A huge improvement is provided by the addition of high-redshift sources, so having cross-ID for high-z galaxies and an even higher-z radio tail is key to enabling very precise measurements of f{sub NL}. We use Fisher matrix forecasts to predict the constraining power in the case of no redshift information and the case where cross-ID allows a tomographic analysis, and we show that the constraints do not improve much with 3 or more bins. Our results show that SKA continuum surveys could provide constraints competitive with CMB and forthcoming optical surveys, potentially allowing a measurement of ?(f{sub NL}) ? 1 to be made. Moreover, these measurements would act as a useful check of results obtained with other probes at other redshift ranges with other methods.
A model for the Pockels effect in distorted liquid crystal blue phases
F. Castles
2015-07-29
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.
similar to an elephant trunk or octopus tentacle. Example continuum robots applications include subsea
Zhou, Chongwu
AME Aerospace & Mechanical Engineering #12;Aerospace and Mechanical Engineers design complex mechanical, thermal, uidic, acoustical, optical, and electronic systems, with characteristic sizes ranging and far underground, to near-Earth, planetary, interplanetary and galactic space. Aerospace and Mechanical
Matheu, David M. (David Michael), 1974-
2003-01-01
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 ...
Miller, Kyle M. (Kyle Mark)
2014-01-01
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 ...
Srinivasa Parthasarathy, Atul
2013-04-30
The mechanical behavior of asphalt binders is nonlinear. The binders exhibit shear thinning/thickening behavior in steady shear tests and non-proportational behavior in other standard viscoelastic tests such as creep-recovery ...
A Site-Scale Model For Fluid And Heat Flow In The Unsaturated...
multicomponent fluid and heat flow through porous and fractured rock. Fracture and matrix flow is treated using both dual-permeability and effective-continuum modeling...
Som, S; Longman, D. E.; Luo, Z; Plomer, M; Lu, T; Senecal, P.K.; Pomraning, E (Energy Systems); (Univ. of Connecticut); (CONVERGENT Science)
2012-01-01
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
2014-12-15
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.
Christov, C. I. [Dept. of Mathematics, University of Louisiana at Lafayette, LA 70504-1010 (United States)
2010-12-22
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.
Radio Continuum and Star Formation in CO-rich Early Type Galaxies
D. M. Lucero; L. M. Young
2007-08-29
In this paper we present new high resolution VLA 1.4 GHz radio continuum observations of five FIR bright CO-rich early-type galaxies and two dwarf early-type galaxies. The position on the radio-FIR correlation combined with striking agreements in morphology between high resolution CO and radio maps show that the radio continuum is associated with star formation in at least four of the eight galaxies. The average star formation rate for the sample galaxies detected in radio is approximately 2 solar masses per year. There is no evidence of a luminous AGN in any of our sample galaxies. We estimate Toomre Q values and find that the gas disks may well be gravitationally unstable, consistent with the above evidence for star formation activity. The radio continuum emission thus corroborates other recent suggestions that star formation in early type galaxies may not be uncommon.
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)
2014-02-24
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)
2013-07-10
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.
Karahan, Aydin
2009-01-01
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 ...
Ryuichi Nakayama
2011-12-13
A simple conformal quantum mechanics model of a d-component variable is proposed, which exactly reproduces the retarded Green functions and conformal weights of conformally coupled scalar fields in de Sitter spacetime seen by a static patch observer. It is found that the action integral of this model is automatically expressed by a complex integral over the time variable t along a closed contour in a way which is typical to the Schwinger-Keldysh formalism of a thermofield theory. Hence this model is at finite temperature. The case of conformally coupled scalar fields in 3d Schwarzschild de Sitter space is also considered and then a large-N matrix model is obtained.
Detlef Duerr; Sheldon Goldstein; Roderich Tumulka; Nino Zanghi
2009-03-15
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.
A continuum theory of phase separation kinetics for active Brownian particles
Joakim Stenhammar; Adriano Tiribocchi; Rosalind J. Allen; Davide Marenduzzo; Michael E. Cates
2013-10-03
Active Brownian particles (ABPs), when subject to purely repulsive interactions, are known to undergo activity-induced phase separation broadly resembling an equilibrium (attraction-induced) gas-liquid coexistence. Here we present an accurate continuum theory for the dynamics of phase-separating ABPs, derived by direct coarse-graining, capturing leading-order density gradient terms alongside an effective bulk free energy. Such gradient terms do not obey detailed balance; yet we find coarsening dynamics closely resembling that of equilibrium phase separation. Our continuum theory is numerically compared to large-scale direct simulations of ABPs and accurately accounts for domain growth kinetics, domain topologies and coexistence densities.
Dynamic soil-structure interaction-comparison of FEM model with experimental results
Srinivasan, Palanivel Rajan
2000-01-01
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 different configurations...
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
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)
2014-05-14
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 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.
2011-04-22
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.
Ehgartner, Brian L.; Sobolik, Steven Ronald; Bean, James E.
2010-07-01
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.
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)
2014-09-07
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.
Nonlinear Sigma Models with Compact Hyperbolic Target Spaces
Gubser, Steven; Schoenholz, Samuel S; Stoica, Bogdan; Stokes, James
2015-01-01
We explore the phase structure of nonlinear sigma models with target spaces corresponding to compact quotients of hyperbolic space, focusing on the case of a hyperbolic genus-2 Riemann surface. The continuum theory of these models can be approximated by a lattice spin system which we simulate using Monte Carlo methods. The target space possesses interesting geometric and topological properties which are reflected in novel features of the sigma model. In particular, we observe a topological phase transition at a critical temperature, above which vortices proliferate, reminiscent of the Kosterlitz-Thouless phase transition in the $O(2)$ model. Unlike in the $O(2)$ case, there are many different types of vortices, suggesting a possible analogy to the Hagedorn treatment of statistical mechanics of a proliferating number of hadron species. Below the critical temperature the spins cluster around six special points in the target space known as Weierstrass points. The diversity of compact hyperbolic manifolds suggest...
2014-10-01
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.
Gravity Probe B Experiment in 7D Space-and-Time Continuum
Yu. A. Portnov
2012-04-24
This study deals with application of field equations in seven-dimensional space-and-time continuum to calculate geodetic and orbital gyroscope precession. It was demonstrated that unlike the classic theory the assumptions made completely correspond to the Gravity Probe B findings.
Deliberate Science, Continuum Magazine: Clean Energy Innovation at NREL, Winter 2012 (Book)
Not Available
2012-02-01
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.
Form-Finding of Long Span Bridges with Continuum Topology Optimization
Swan Jr., Colby Corson
(Ground structures) #12;Applied loads SupportsStarting Design domain Elements of Continuum topology) 900 elements 60 elements (d) 200 elements Long-Span Bridge Problem "2-Supports" Design domain with 12 Engineering Center for Computer-Aided Design The University of Iowa #12;Objective Statement To develop
Radio Continuum Surveys with Square Kilometre Array Pathfinders Ray P. Norris1,2
Norris, Ray
Radio Continuum Surveys with Square Kilometre Array Pathfinders Ray P. Norris1,2 , J. Afonso3 , D,1 Accepted by PASA, 22 October 2012 Abstract: In the lead-up to the Square Kilometre Array (SKA) project & Background The Square Kilometre Array (SKA) is a proposed ma- jor internationally-funded radio telescope
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.
2004-09-17
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.
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
Using Multiconformation Continuum Electrostatics to Compare Chloride Binding Motifs in -Amylase,
Gunner, Marilyn
Using Multiconformation Continuum Electrostatics to Compare Chloride Binding Motifs in -Amylase electrostatics (MCCE), we show that the changes of chloride binding to -amylase, human serum albumin (HSA) and Omp32 with pH, and of -amylase with mutation agree well with experimental data. The three proteins
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
Solvent Quality Dependent Continuum van der Waals Attraction and Phase Behavior for Colloids Bearing
Chan, Derek Y C
Solvent Quality Dependent Continuum van der Waals Attraction and Phase Behavior for Colloids dispersion as a function of solvent quality and particle volume fraction is compared with theoretical.5 M NaCl as a function of temperature, which controls solvent quality for the adsorbed Pluronic
sition from a localized solvent-bound ground state to the continuum of the solvent conduc-
Wong, Joyce
sition from a localized solvent-bound ground state to the continuum of the solvent conduc- tion species account for es in the immediate and solvent-separated contact pairs. The ET reaction being of two well-defined configurations, an immediate or solvent-separated contact pair. Both configura- tions
Using Continuum Robots to Enable Transoral Access to the Peripheral Lung for Minimally Invasive Biopsy Arthur W. Mahoney, Philip J. Swaney, and Robert J. Webster III Lung cancer kills more people than reach regions adjacent to bronchii. Enables access to the peripheral lung for biopsy without puncturing
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
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
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.
1998-07-29
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.
New metamaterials with macroscopic behavior outside that of continuum elastodynamics
Graeme W. Milton
2007-06-14
Metamaterials are constructed such that, for a narrow range of frequencies, the momentum density depends on the local displacement gradient, and the stress depends on the local velocity. In these models the momentum density generally depends not only on the strain, but also on the local rotation, and the stress is generally not symmetric. A variant is constructed for which, at a fixed frequency, the momentum density is independent of the local rotation (but still depends on the strain) and the stress is symmetric (but still depends on the velocity). Generalizations of these metamaterials may be useful in the design of elastic cloaking devices.
Litster, Shawn
in polymer electrolyte fuel cells (PEFCs) to elucidate the interfacial morphology. The model employs measured Elsevier B.V. All rights reserved. 1. Introduction Polymer electrolyte fuel cells (PEFC) are promising, mathematical models are valuable tools often used in evaluating multiphase transport phenomena in PEFC
Odegard, Gregory M.
2010-01-01
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
Lee, Chin-Fei; Hirano, Naomi; Shang, Hsien; Ho, Paul T. P.; Krasnopolsky, Ruben; Zhang, Qizhou
2014-05-10
HH 212 is a nearby (400 pc) Class 0 protostellar system showing several components that can be compared with theoretical models of core collapse. We have mapped it in the 350 GHz continuum and HCO{sup +} J = 4-3 emission with ALMA at up to ?0.''4 resolution. A flattened envelope and a compact disk are seen in the continuum around the central source, as seen before. The HCO{sup +} kinematics shows that the flattened envelope is infalling with small rotation (i.e., spiraling) into the central source, and thus can be identified as a pseudodisk in the models of magnetized core collapse. Also, the HCO{sup +} kinematics shows that the disk is rotating and can be rotationally supported. In addition, to account for the missing HCO{sup +} emission at low-redshifted velocity, an extended infalling envelope is required, with its material flowing roughly parallel to the jet axis toward the pseudodisk. This is expected if it is magnetized with an hourglass B-field morphology. We have modeled the continuum and HCO{sup +} emission of the flattened envelope and disk simultaneously. We find that a jump in density is required across the interface between the pseudodisk and the disk. A jet is seen in HCO{sup +} extending out to ?500 AU away from the central source, with the peaks upstream of those seen before in SiO. The broad velocity range and high HCO{sup +} abundance indicate that the HCO{sup +} emission traces internal shocks in the jet.
CONTINUUM CONTRIBUTIONS TO THE SDO/AIA PASSBANDS DURING SOLAR FLARES
Milligan, Ryan O.; McElroy, Sarah A.
2013-11-01
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.
Hierarchical Models for Batteries: Overview with Some Case Studies
Pannala, Sreekanth; Mukherjee, Partha P; Allu, Srikanth; Nanda, Jagjit; Martha, Surendra K; Dudney, Nancy J; Turner, John A
2012-01-01
Batteries are complex multiscale systems and a hierarchy of models has been employed to study different aspects of batteries at different resolutions. For the electrochemistry and charge transport, the models span from electric circuits, single-particle, pseudo 2D, detailed 3D, and microstructure resolved at the continuum scales and various techniques such as molecular dynamics and density functional theory to resolve the atomistic structure. Similar analogies exist for the thermal, mechanical, and electrical aspects of the batteries. We have been recently working on the development of a unified formulation for the continuum scales across the electrode-electrolyte-electrode system - using a rigorous volume averaging approach typical of multiphase formulation. This formulation accounts for any spatio-temporal variation of the different properties such as electrode/void volume fractions and anisotropic conductivities. In this talk the following will be presented: The background and the hierarchy of models that need to be integrated into a battery modeling framework to carry out predictive simulations, Our recent work on the unified 3D formulation addressing the missing links in the multiscale description of the batteries, Our work on microstructure resolved simulations for diffusion processes, Upscaling of quantities of interest to construct closures for the 3D continuum description, Sample results for a standard Carbon/Spinel cell will be presented and compared to experimental data, Finally, the infrastructure we are building to bring together components with different physics operating at different resolution will be presented. The presentation will also include details about how this generalized approach can be applied to other electrochemical storage systems such as supercapacitors, Li-Air batteries, and Lithium batteries with 3D architectures.