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Generalized finite element method for Helmholtz equation
E-Print Network (OSTI)
This dissertation presents the Generalized Finite Element Method (GFEM) for the scalar Helmholtz equation, which describes the time harmonic acoustic wave propagation problem. We introduce several handbook functions for the Helmholtz equation, namely the planewave, wave-band, and Vekua functions, and we use these handbook functions to enrich the Finite Element space via the Partition of Unity Method to create the GFEM space. The enrichment of the approximation space by these handbook functions reduces the pollution effect due to wave number and we are able to obtain a highly accurate solution with a much smaller number of degrees-of-freedom compared with the classical Finite Element Method. The q-convergence of the handbook functions is investigated, where q is the order of the handbook function, and it is shown that asymptotically the handbook functions exhibit the same rate of exponential convergence. Hence we can conclude that the selection of the handbook functions from an admissible set should be dictated only by the ease of implementation and computational costs. Another issue addressed in this dissertation is the error coming from the artificial truncation boundary condition, which is necessary to model the Helmholtz problem set in the unbounded domain. We observe that for high q, the most significant component of the error is the one due to the artificial truncation boundary condition. Here we propose a method to assess this error by performing an additional computation on the extended domain using GFEM with high q.
Hidajat, Realino Lulie
A Study of Frontogenesis Using Finite-Element and Finite-Difference Methods
Science Conference Proceedings (OSTI)
The accuracy of finite-element and finite-difference methods used to simulate frontogenesis in a six-layer three-dimensional model employing isentropic coordinates is compared. The problem solved is that of an initial height-independent ...
A. K. Macpherson; M. H. Aksel; P. D. Hilton
Fuzzy and interval finite element method for heat conduction problem
Traditional finite element method is a well-established method to solve various problems of science and engineering. Different authors have used various methods to solve governing differential equation of heat conduction problem. In this study, heat conduction in a circular rod has been considered which is made up of two different materials viz. aluminum and copper. In earlier studies parameters in the differential equation have been taken as fixed (crisp) numbers which actually may not. Those parameters are found in general by some measurements or experiments. So the material properties are actually uncertain and may be considered to vary in an interval or as fuzzy and in that case complex interval arithmetic or fuzzy arithmetic has to be considered in the analysis. As such the problem is discretized into finite number of elements which depend on interval/fuzzy parameters. Representation of interval/fuzzy numbers may give the clear picture of uncertainty. Hence interval/fuzzy arithmetic is applied in the finite element method to solve a steady state heat conduction problem. Application of fuzzy finite element method in the said problem gives fuzzy system of linear equations in general. Here new methods have also been proposed to handle such type of fuzzy system of linear equations. Corresponding results are computed and has been reported here.
Sarangam Majumdar; Sukanta Nayak; S. Chakraverty
The Mimetic Finite Element Method and the Virtual Element Method for elliptic problems with arbitrary regularity.
SciTech Connect
We develop and analyze a new family of virtual element methods on unstructured polygonal meshes for the diffusion problem in primal form, that use arbitrarily regular discrete spaces V{sub h} {contained_in} C{sup {alpha}} {element_of} N. The degrees of freedom are (a) solution and derivative values of various degree at suitable nodes and (b) solution moments inside polygons. The convergence of the method is proven theoretically and an optimal error estimate is derived. The connection with the Mimetic Finite Difference method is also discussed. Numerical experiments confirm the convergence rate that is expected from the theory.
Manzini, Gianmarco [Los Alamos National Laboratory
Modelling well leakage in multilayer aquifer systems using the extended finite element method
The extended finite element method (XFEM) is applied to the problem of predicting the steady-state leakage from layered sedimentary aquifer systems perforated by abandoned wells. Multi-aquifer systems are modelled using a quasi-three-dimensional model ... Keywords: Extended finite element method, GFEM, Generalised finite element method, Leakage, Multi-aquifer systems, XFEM
Robert Gracie; James R. Craig
Adaptive nearest-nodes finite element method guided by gradient of linear strain energy density
In this paper, an adaptive finite element method is formulated based on the newly developed nearest-nodes finite element method (NN-FEM). In the adaptive NN-FEM, mesh modification is guided by the gradient of strain energy density, i.e., a larger gradient ... Keywords: Gradient of strain energy density, Mesh intensity, Mesh modification operator, Nearest-nodes finite element method
Yunhua Luo
An adaptive finite element method for simulating surface tension with the gradient theory of fluid interfaces
The gradient theory for the surface tension of simple fluids and mixtures is rigorously analyzed based on mathematical theory. The finite element approximation of surface tension is developed and analyzed, and moreover, an adaptive finite element method ... Keywords: 49S05, 65N30, 65N50, Adaptive finite element method, Gradient theory, Surface tension
Jisheng Kou, Shuyu Sun
2D simulation of fluid-structure interaction using finite element method
This paper deals with pressure-based finite element analysis of fluid-structure systems considering the coupled fluid and structural dynamics. The present method uses two-dimensional fluid elements and structural line elements for the numerical simulation ... Keywords: Finite element, Galerkin weighted residual method, Newmark's predictor-corrector method, Pressure formulation, Sloshing
S. Mitra; K. P. Sinhamahapatra
Finite size scaling for quantum criticality using the finite-element method
Finite size scaling for the Schr\\"{o}dinger equation is a systematic approach to calculate the quantum critical parameters for a given Hamiltonian. This approach has been shown to give very accurate results for critical parameters by using a systematic expansion with global basis-type functions. Recently, the finite element method was shown to be a powerful numerical method for ab initio electronic structure calculations with a variable real-space resolution. In this work, we demonstrate how to obtain quantum critical parameters by combining the finite element method (FEM) with finite size scaling (FSS) using different ab initio approximations and exact formulations. The critical parameters could be atomic nuclear charges, internuclear distances, electron density, disorder, lattice structure, and external fields for stability of atomic, molecular systems and quantum phase transitions of extended systems. To illustrate the effectiveness of this approach we provide detailed calculations of applying FEM to approximate solutions for the two-electron atom with varying nuclear charge; these include Hartree-Fock, density functional theory under the local density approximation, and an "exact"' formulation using FEM. We then use the FSS approach to determine its critical nuclear charge for stability; here, the size of the system is related to the number of elements used in the calculations. Results prove to be in good agreement with previous Slater-basis set calculations and demonstrate that it is possible to combine finite size scaling with the finite-element method by using ab initio calculations to obtain quantum critical parameters. The combined approach provides a promising first-principles approach to describe quantum phase transitions for materials and extended systems.
Edwin Antillon; Birgit Wehefritz-Kaufmann; Sabre Kais
Generalized Multiscale Finite Element Methods (GMsFEM)
In this paper, we propose a general approach called Generalized Multiscale Finite Element Method (GMsFEM) for performing multiscale simulations for problems without scale separation over a complex input space. As in multiscale finite element methods (MsFEMs), the main idea of the proposed approach is to construct a small dimensional local solution space that can be used to generate an efficient and accurate approximation to the multiscale solution with a potentially high dimensional input parameter space. In the proposed approach, we present a general procedure to construct the offline space that is used for a systematic enrichment of the coarse solution space in the online stage. The enrichment in the online stage is performed based on a spectral decomposition of the offline space. In the online stage, for any input parameter, a multiscale space is constructed to solve the global problem on a coarse grid. The online space is constructed via a spectral decomposition of the offline space and by choosing the eigenvectors corresponding to the largest eigenvalues. The computational saving is due to the fact that the construction of the online multiscale space for any input parameter is fast and this space can be reused for solving the forward problem with any forcing and boundary condition. Compared with the other approaches where global snapshots are used, the local approach that we present in this paper allows us to eliminate unnecessary degrees of freedom on a coarse-grid level. We present various examples in the paper and some numerical results to demonstrate the effectiveness of our method. 1
Yalchin Efendiev; Juan Galvis; Thomas Y. Hou
Error Estimates for a Combined Finite Volume--Finite Element Method for Nonlinear Convection--Diffusion Problems
The subject of this paper is the analysis of error estimates of the combined finite volume--finite element (FV--FE) method for the numerical solution of a scalar nonlinear conservation law equation with a diffusion term. Nonlinear convective terms are ... Keywords: a priori estimates, compressible Navier--Stokes equations, discrete maximum principle, error estimates, finite element method, monotone finite volume schemes, nonlinear convection-diffusion equation, numerical integration
Miloslav Feistauer; JirĒ Felcman; Mßria Lukßcovß-Medvidovß; Gerald Warnecke
Stress based finite element methods for solving contact problems: Comparisons between various solution methods
This paper deals with numerical methods for solving unilateral contact problems with friction. Although these problems are usually defined in terms of the displacement, a stress based approach to the problem is developed here. The ''equilibrium'' finite ... Keywords: Augmented Lagrangian, Condensation, Contact, Equilibrium finite elements, Friction
Franńois Kuss; Frķdķric Lebon
Modeling of wire-on-tube heat exchangers using finite element method
Wire-on-tube heat exchangers are analysed under normal operating conditions (free convection) using finite element method. Galerkin's weighted residual method is used to minimise the errors. The effects of ambient temperatures and mass flow rates of ... Keywords: finite element method, free convection, phase change, wire on-tube heat exchangers
G. A. Quadir; G. M. Krishnan; K. N. Seetharamu
IMPLICIT-EXPLICIT MULTISTEP FINITE ELEMENT METHODS FOR NONLINEAR PARABOLIC PROBLEMS Georgios boundary value problems for nonlinear parabolic equations. In space we discretize by finite element methods for the time discretization of a class of nonlinear parabolic problems of the form: Given T > 0 and u0 H, find
Akrivis, Georgios
A variational multiscale finite element method for multiphase flow in porous media
We present a stabilized finite element method for the numerical solution of multiphase flow in porous media, based on a multiscale decomposition of pressures and fluid saturations into resolved (or grid) scales and unresolved (or subgrid) scales. The ... Keywords: Conservation laws, Finite elements, Multiphase flow, Porous media, Shocks, Stabilized methods, Variational multiscale, Waterflood
Ruben Juanes
We present a stabilized finite element method for the numerical solution of multiphase flow in porous media, based on a multiscale decomposition of pressures and fluid saturations into resolved (or grid) scales and unresolved (or subgrid) scales. The ... Keywords: conservation laws, finite elements, multiphase flow, porous media, shocks, stabilized methods, variational multiscale, waterflood
Developing a time-domain finite-element method for modeling of electromagnetic cylindrical cloaks
In this paper we propose a time-domain finite element method for modeling of electromagnetic cloaks. The permittivity and permeability of the cloak model are described by the Drude dispersion model. The model to be solved is quite challenging in that ... Keywords: Finite element method, Invisibility cloak, Maxwell's equations
Jichun Li; Yunqing Huang; Wei Yang
Optimization of a large steel truss structure used in civil engineering, by finite element method
This paper presents the optimized version of a steel structure used in civil engineering obtained thru a process of structural optimization using Finite Element Method. The main advantage of this optimized structure is the cost which is 50% smaller then ... Keywords: Ansys, civil engineering, finite elements method, steel structure, structural optimization
Mihai Negru; Ivona Georgescu; Emil Albota
Multiscale finite element methods for high-contrast problems using local spectral basis functions
In this paper we study multiscale finite element methods (MsFEMs) using spectral multiscale basis functions that are designed for high-contrast problems. Multiscale basis functions are constructed using eigenvectors of a carefully selected local spectral ... Keywords: High contrast, Multiscale finite element, Porous media, Spectral
Yalchin Efendiev; Juan Galvis; Xiao-Hui Wu
Whole-Body Cerenkov Luminescence Tomography with the Finite Element SP3 Method
Whole-Body Cerenkov Luminescence Tomography with the Finite Element SP3 Method JIANGHONG ZHONG, JIE Bai oversaw the review of this article. Abstract--Generation of an accurate Cerenkov luminescence-active approach toward whole-body Cerenkov luminescence tomography. The finite element framework employs
Tian, Jie
Extended finite element method on polygonal and quadtree meshes
Adaptive re?nement for B-spline ?nite element, Internationalmatrix. The application of B-spline ?nite elements [27],
Tabarraei, A.; Sukumar, N.
Influence of p-method finite element parameters on predictions of crack front geometry
The effect of various p-method finite element model parameters on the prediction of planar crack front geometry in three dimensional structures is evaluated. An automatic crack growth method was developed using the commercial software StressCheck coupled ... Keywords: ?, Corner crack, Crack front, Finite element, Mesh, Stress intensity factor, a, b, b/a, c, ctrat, ipr, m, mrat, p-method, trans
Diane Wowk, Kyle Gamble, Ross Underhill
Partial delamination modeling in composite beams using a finite element method
A new method of modeling partial delamination in composite beams is proposed and implemented using the finite element method. Homogenized cross-sectional stiffness of the delaminated beam is obtained by the proposed analytical technique, including extension-bending, ... Keywords: Beam element, Composites, Delamination, Timoshenko beam, Vibration
S. Keshava Kumar, Ranjan Ganguli, Dineshkumar Harursampath
Finite element method for conserved phase fields: Stress-mediated diffusional phase transformation
Phase-field models with conserved phase-field variables result in a 4th order evolution partial differential equation (PDE). When coupled with the usual 2nd order thermo-mechanics equations, such problems require special treatment. In the past, the finite ... Keywords: Binary alloys, Convergence, Galerkin finite element method, Phase-field model
Mohsen Asle Zaeem; Sinisa Dj. Mesarovic
On the Equivalence of Semi-Lagrangian Schemes and Particle-in-Cell Finite Element Methods
It is shown that the semi-Lagrangian schemes with cubic spline interpolation are equivalent to a particle-in-cell finite element method. The method conserves mass, is unconditionally stable, and has a truncation error as high as fourth-order for ...
Rodolfo Bermejo
Discontinuous Galerkin finite element methods for hyperbolic nonconservative partial differential equations
We present space- and space-time discontinuous Galerkin finite element (DGFEM) formulations for systems containing nonconservative products, such as occur in dispersed multiphase flow equations. The main criterium we pose on the weak formulation is that ... Keywords: 02.60.Cb, 02.70.Dh, 35L60, 35L65, 35L67, 47.55.-t, 47.85.Dh, 65M60, 76M10, Arbitrary Lagrangian Eulerian (ALE) formulation, Discontinuous Galerkin finite element methods, Nonconservative products, Numerical fluxes, Two-phase flows
S. Rhebergen; O. Bokhove; J. J. W. van der Vegt
Numerical prediction of aerodynamic characteristics of prismatic cylinder by finite element method with Spalart-Allmaras turbulence model
Aerodynamic characteristic of prismatic cylinders is numerically investigated by using finite element method with Spalart-Allmaras turbulence model. The developed model is verified against the available experimental and numerical results for turbulent ... Keywords: Aerodynamic characteristic, Afterbody shape, Finite element method, Prismatic cylinder, Turbulent flow, Unsteady S-A model
Yan Bao; Dai Zhou; Cheng Huang; Qier Wu; Xiang-qiao Chen
A posteriori error estimates in finite element methods for general Friedrichs' systems.
In this paper we develop and analyse a new a posteriori error estimator for general Friedrichs' systems valid for most classical finite element approximations. This error estimator is based on comparison between an appropriate norm of the exact error, and the L 2 -norm of the residuals of the approximate solution. We prove that the estimator is independent of the dimension of the space and of the numerical approximation method used. Moreover the global majoration and local minoration constants are independent of the shape of the mesh. 1 Introduction A well known difficulty of the numerical solution of Friedrichs' systems is the problem of numerically resolving discontinuities, characteristic of solutions of hyperbolic problems, while simultaneously producing high-order, non-oscillatory results. The basic issue of the quality of the numerical solution obtained is fundamentally important : how accurate is this solution ? Adaptive methods attempt to answer these questions. The goal is ...
B. Achchab; A. Agouzal; J. Baranger; J.F. Maitre
Least-squares variational principles and the finite element method: theory, formulations, and models for solid and fluid mechanics
We consider the application of least-squares variational principles and the finite element method to the numerical solution of boundary value problems arising in the fields of solidand fluidmechanics.For manyof these problems least-squares principles offer many theoretical and computational advantages in the implementation of the corresponding finite element model that are not present in the traditional weak form Galerkin finite element model.Most notably, the use of least-squares principles leads to a variational unconstrained minimization problem where stability conditions such as inf-sup conditions (typically arising in mixed methods using weak form Galerkin finite element formulations) never arise. In addition, the least-squares based finite elementmodelalways yields a discrete system ofequations witha symmetric positive definite coeffcientmatrix.These attributes, amongst manyothers highlightedand detailed in this work, allow the developmentofrobust andeffcient finite elementmodels for problems of practical importance. The research documented herein encompasses least-squares based formulations for incompressible and compressible viscous fluid flow, the bending of thin and thick plates, and for the analysis of shear-deformable shell structures.
Pontaza, Juan Pablo
Finite element methods for unsaturated porous solids and their application to dam engineering problems
This work presents a finite element formulation of equations proposed in a companion paper to describe the hyperelastic response of three-phase porous media. Attention is paid to the development of consistent tangents required by the Newton-Raphson procedure ... Keywords: Concrete dams, Hydro-mechanical coupling, Multiphase porous media, Rock mass permeability, Unilateral constraints
C. Callari; A. Abati
Thermo-Poroelastic Modeling of Reservoir Stimulation and Microseismicity Using Finite Element Method with Damage Mechanics
Stress and permeability variations around a wellbore and in the reservoir are of much interest in petroleum and geothermal reservoir development. Water injection causes significant changes in pore pressure, temperature, and stress in hot reservoirs, changing rock permeability. In this work, two- and three-dimensional finite element methods were developed to simulate coupled reservoirs with damage mechanics and stress-dependent permeability. The model considers the influence of fluid flow, temperature, and solute transport in rock deformation and models nonlinear behavior with continuum damage mechanics and stress-dependent permeability. Numerical modeling was applied to analyze wellbore stability in swelling shale with two- and three-dimensional damage/fracture propagation around a wellbore and injection-induced microseismic events. The finite element method (FEM) was used to solve the displacement, pore pressure, temperature, and solute concentration problems. Solute mass transport between drilling fluid and shale formation was considered to study salinity effects. Results show that shear and tensile failure can occur around a wellbore in certain drilling conditions where the mud pressure lies between the reservoir pore pressure and fracture gradient. The fully coupled thermo-poro-mechanical FEM simulation was used to model damage/fracture propagation and microseismic events caused by fluid injection. These studies considered wellbore geometry in small-scale modeling and point-source injection, assuming singularity fluid flux for large-scale simulation. Damage mechanics was applied to capture the effects of crack initiation, microvoid growth, and fracture propagation. The induced microseismic events were modeled in heterogeneous geological media, assuming the Weibull distribution functions for modulus and permeability. The results of this study indicate that fluid injection causes the effective stress to relax in the damage phase and to concentrate at the interface between the damage phase and the intact rock. Furthermore, induced-stress and far-field stress influence damage propagation. Cold water injection causes the tensile stress and affects the initial fracture and fracture propagation, but fracture initiation pressure and far-field stress are critical to create a damage/fracture plane, which is normal to the minimum far-field stress direction following well stimulation. Microseismic events propagate at both well scale and reservoir-scale simulation; the cloud shape of a microseismic event is affected by permeability anisotropy and far-field stress, and deviatoric horizontal far-field stress especially contributes to the localization of the microseismic cloud.
Lee, Sang Hoon
An extended finite element method for hydraulic fracture propagation in deformable porous media with the cohesive crack model
In this paper, a fully coupled numerical model is developed for the modeling of the hydraulic fracture propagation in porous media using the extended finite element method in conjunction with the cohesive crack model. The governing equations, which account ... Keywords: Cohesive crack propagation, Fluid flow, Fracturing porous media, Fully coupled model, Hydraulic fracturing, XFEM
T. Mohammadnejad, A. R. Khoei
The application of the wavelet finite element method on the temperature calculation of ceramic coating diesel engine piston
In order to analyse the temperature distribution of diesel engine piston, the wavelet finite element was constructed based on Daubechies wavelet scale function and traditional finite element. And the temperature distribution of the conventional and ceramic ...
Bin Zhao
Visualization methods for high-resolution, transient, 3-D, finite element situations
Scientific visualization is the process whereby numerical data is transformed into a visual form to augment the process of discovery and understanding. Visualizing the data generated by large-scale, transient, three-dimensional finite element simulations poses many challenges due to geometric complexity, the presence of multiple materials and multiple element types, and the inherent unstructured nature of the meshes. In this paper, the direct use of finite element data structures, nodal assembly procedures, and element interpolants for volumetric adaptive surface extraction, surface rendering, vector grids and particle tracing is discussed. A brief description of a {open_quotes}direct-to-disk{close_quotes} animation system is presented, and case studies which demonstrate the use of isosurfaces, vector plots, cutting planes, reference surfaces and particle tracing are then discussed in the context of several case studies for transient incompressible viscous flow, and acoustic fluid-structure interaction simulations. An overview of the implications of massively parallel computers on visualization is presented to highlight the issues in parallel visualization methodology, algorithms. data locality and the ultimate requirements for temporary and archival data storage and network bandwidth.
Christon, M.A.
The simulation with the finite element method of the velocity and temperature fields for a nonturbionar jet burner of 35MW feeding with pulverized coal
This paper presents the analysis of coal particle combustion in nonturbionar jet burner of 35MW used the Finite Element Method made with aid of the FLUENT programme. The pulverized coal combustion simulation involves modeling a continuous gas phase flow ... Keywords: FLUENT, coal-air mixture, combustion, finite element method, injection coal, nonturbionar jet
Mihai D. L. Talu; Stefan D. L. Talu; Mihai Negru
Neutron Flux Interpolation with Finite Element Method in the Nuclear Fuel Cell Calculation using Collision Probability Method
Nuclear reactor design and analysis of next-generation reactors require a comprehensive computing which is better to be executed in a high performance computing. Flat flux (FF) approach is a common approach in solving an integral transport equation with collision probability (CP) method. In fact, the neutron flux distribution is not flat, even though the neutron cross section is assumed to be equal in all regions and the neutron source is uniform throughout the nuclear fuel cell. In non-flat flux (NFF) approach, the distribution of neutrons in each region will be different depending on the desired interpolation model selection. In this study, the linear interpolation using Finite Element Method (FEM) has been carried out to be treated the neutron distribution. The CP method is compatible to solve the neutron transport equation for cylindrical geometry, because the angle integration can be done analytically. Distribution of neutrons in each region of can be explained by the NFF approach with FEM and the calculation results are in a good agreement with the result from the SRAC code. In this study, the effects of the mesh on the k{sub eff} and other parameters are investigated.
Shafii, M. Ali [Departmen of Physics Bandung Institute of Technology, Jl. Ganesha 10, Bandung 40134 (Indonesia); Physics Department, Andalas University, Kampus Limau Manis, Padang, Sumatera Barat (Indonesia); Su'ud, Zaki; Waris, Abdul; Kurniasih, Neny [Departmen of Physics Bandung Institute of Technology, Jl. Ganesha 10, Bandung 40134 (Indonesia); Ariani, Menik [Physics Department, Sriwijaya University, Kampus Indralaya, Ogan Ilir, Sumatera Selatan (Indonesia); Departmen of Physics Bandung Institute of Technology, Jl. Ganesha 10, Bandung 40134 (Indonesia); Yulianti, Yanti [Physics Department, Lampung University, Jl.Sumantri Brojonegoro no 1, Lampung (Indonesia); Departmen of Physics Bandung Institute of Technology, Jl. Ganesha 10, Bandung 40134 (Indonesia)
Laminar backward-facing step flow using the finite element method
Laminar, incompressible flow over a backward-facing step is calculated using a finite element spatial discretization with a piecewise continuous pressure approximation and an explicit time marching algorithm. The time-accurate evolution to steady state is demonstrated for both two-dimensional (2D) and three-dimensional (3D) simulations. This approach is shown to accurately predict the lengths of the recirculation zone on the top wall and at the step for various meshes and domain lengths, for a Reynolds number of 800 based on the average inlet velocity and twice the inlet channel height. The instantaneous and steady-state results are investigated. The steady-state solutions are evaluated by comparison to published numerical and experimental results.
Kornblum, B.; McCallen, R. [Lawrence Livermore National Lab., CA (United States); Christon, M.A. [Sandia National Labs., Albuquerque, NM (United States); Kollmann, W. [Univ. of California, Davis, CA (United States) Dept. of Mechanical and Aeronautical Engineering] [and others
Grid size convergence study of the finite-element method applied to electron, positron-molecule scattering
The convergence of the fifth order Hermite polynomial, Finite Element method is studied for electron and positron scattering from N{sub 2} and C{sub 2}H{sub 2} in the static approximation in spherical coordinates. Results are compared with a single-center method employing spherical harmonic expansions in order to compare grid size requirements to number of partial waves in the single-center method. Results will be presented at the level of phase shifts, integrated and differential cross sections.
Weatherford, C.A.; Khurana, I.
A Moving-Mesh Finite Element Method and its Application to the Numerical Solution of Phase-Change
School of Computing, University of Leeds, UK R. Mahmood Computer Division, Pakistan Institute of Nuclear Science and Technology (PINSTECH), Islamabad, Pakistan A distributed Lagrangian moving-mesh finite element
Jimack, Peter
A Full-wave Model for Wave Propagation and Dissipation in the Inner Magnetosphere Using the Finite Element Method
A wide variety of plasma waves play an important role in the energization and loss of particles in the inner magnetosphere. Our ability to understand and model wave-particle interactions in this region requires improved knowledge of the spatial distribution and properties of these waves as well as improved understanding of how the waves depend on changes in solar wind forcing and/or geomagnetic activity. To this end, we have developed a two-dimensional, finite element code that solves the full wave equations in global magnetospheric geometry. The code describes three-dimensional wave structure including mode conversion when ULF, EMIC, and whistler waves are launched in a two-dimensional axisymmetric background plasma with general magnetic field topology. We illustrate the capabilities of the code by examining the role of plasmaspheric plumes on magnetosonic wave propagation; mode conversion at the ion-ion and Alfven resonances resulting from external, solar wind compressions; and wave structure and mode conversion of electromagnetic ion cyclotron waves launched in the equatorial magnetosphere, which propagate along the magnetic field lines toward the ionosphere. We also discuss advantages of the finite element method for resolving resonant structures, and how the model may be adapted to include nonlocal kinetic effects.
Ernest Valeo, Jay R. Johnson, Eun-Hwa and Cynthia Phillips
Automated quadrilateral surface discretization method and apparatus usable to generate mesh in a finite element analysis system
DOE Patents (OSTI)
An automatic quadrilateral surface discretization method and apparatus is provided for automatically discretizing a geometric region without decomposing the region. The automated quadrilateral surface discretization method and apparatus automatically generates a mesh of all quadrilateral elements which is particularly useful in finite element analysis. The generated mesh of all quadrilateral elements is boundary sensitive, orientation insensitive and has few irregular nodes on the boundary. A permanent boundary of the geometric region is input and rows are iteratively layered toward the interior of the geometric region. Also, an exterior permanent boundary and an interior permanent boundary for a geometric region may be input and the rows are iteratively layered inward from the exterior boundary in a first counter clockwise direction while the rows are iteratively layered from the interior permanent boundary toward the exterior of the region in a second clockwise direction. As a result, a high quality mesh for an arbitrary geometry may be generated with a technique that is robust and fast for complex geometric regions and extreme mesh gradations.
Blacker, Teddy D. (12205 Kashmir, N.E., Albuquerque, NM 87111)
Grid-based methods for diatomic quantum scattering problems: a finite-element, discrete variable representation in prolate spheroidal coordinates
We show how to combine finite elements and the discrete variable representation in prolate spheroidal coordinates to develop a grid-based approach for quantum mechanical studies involving diatomic molecular targets. Prolate spheroidal coordinates are a natural choice for diatomic systems and have been used previously in a variety of bound-state applications. The use of exterior complex scaling in the present implementation allows for a transparently simple way of enforcing Coulomb boundary conditions and therefore straightforward application to electronic continuum problems. Illustrative examples involving the bound and continuum states of H2+, as well as the calculation of photoionization cross sections, show that the speed and accuracy of the present approach offer distinct advantages over methods based on single-center expansions.
Tao, Liang; McCurdy, C.W.; Rescigno, T.N.
Unified framework for finite element assembly
At the heart of any finite element simulation is the assembly of matrices and vectors from discrete variational forms. We propose a general interface between problem-specific and general-purpose components of finite element programs. This interface ...
M. S. Alnaes; A. Logg; K-A. Mardal; O. Skavhaug; H. P. Langtangen
B-spline finite elements for plane elasticity problems.
??The finite element method since its development in the 1950├ó┬?┬?s has been used extensively in solving complex problems involving partial differential equations. The conventional finiteģ (more)
Aggarwal, Bhavya
Partition-of-unity finite-element method for large scale quantum molecular dynamics on massively parallel computational platforms
Over the course of the past two decades, quantum mechanical calculations have emerged as a key component of modern materials research. However, the solution of the required quantum mechanical equations is a formidable task and this has severely limited the range of materials systems which can be investigated by such accurate, quantum mechanical means. The current state of the art for large-scale quantum simulations is the planewave (PW) method, as implemented in now ubiquitous VASP, ABINIT, and QBox codes, among many others. However, since the PW method uses a global Fourier basis, with strictly uniform resolution at all points in space, and in which every basis function overlaps every other at every point, it suffers from substantial inefficiencies in calculations involving atoms with localized states, such as first-row and transition-metal atoms, and requires substantial nonlocal communications in parallel implementations, placing critical limits on scalability. In recent years, real-space methods such as finite-differences (FD) and finite-elements (FE) have been developed to address these deficiencies by reformulating the required quantum mechanical equations in a strictly local representation. However, while addressing both resolution and parallel-communications problems, such local real-space approaches have been plagued by one key disadvantage relative to planewaves: excessive degrees of freedom (grid points, basis functions) needed to achieve the required accuracies. And so, despite critical limitations, the PW method remains the standard today. In this work, we show for the first time that this key remaining disadvantage of real-space methods can in fact be overcome: by building known atomic physics into the solution process using modern partition-of-unity (PU) techniques in finite element analysis. Indeed, our results show order-of-magnitude reductions in basis size relative to state-of-the-art planewave based methods. The method developed here is completely general, applicable to any crystal symmetry and to both metals and insulators alike. We have developed and implemented a full self-consistent Kohn-Sham method, including both total energies and forces for molecular dynamics, and developed a full MPI parallel implementation for large-scale calculations. We have applied the method to the gamut of physical systems, from simple insulating systems with light atoms to complex d- and f-electron systems, requiring large numbers of atomic-orbital enrichments. In every case, the new PU FE method attained the required accuracies with substantially fewer degrees of freedom, typically by an order of magnitude or more, than the current state-of-the-art PW method. Finally, our initial MPI implementation has shown excellent parallel scaling of the most time-critical parts of the code up to 1728 processors, with clear indications of what will be required to achieve comparable scaling for the rest. Having shown that the key remaining disadvantage of real-space methods can in fact be overcome, the work has attracted significant attention: with sixteen invited talks, both domestic and international, so far; two papers published and another in preparation; and three new university and/or national laboratory collaborations, securing external funding to pursue a number of related research directions. Having demonstrated the proof of principle, work now centers on the necessary extensions and optimizations required to bring the prototype method and code delivered here to production applications.
Pask, J E; Sukumar, N; Guney, M; Hu, W
Finite element simulation of microphotonic lasing system
We present a method for performing time domain simulations of a microphotonic system containing a four level gain medium based on the finite element method. This method includes an approximation that involves expanding the pump and probe electromagnetic fields around their respective carrier frequencies, providing a dramatic speedup of the time evolution. Finally, we present a two dimensional example of this model, simulating a cylindrical spaser array consisting of a four level gain medium inside of a metal shell.
Fietz, Chris; Soukoulis, Costas M.
Analysis of an interface stabilised finite element method: The advection-diffusion-reaction equation
. Labeur and G. N. Wells. A Galerkin interface stabilisation method for the advection-diffusion and incompressible Navier-Stokes equations. Computer Methods in Applied Mechanics and Engineering, 196(49¢52):4985¢5000, 2007. [3] B. Cockburn, B. Dong, J. Guzma...
Wells, G N
The Combined Finite-Discrete Element Method applied to the Study of Rock Fracturing Behavior in 3D
Since its introduction the combined finite-discrete element method (FEM/DEM), has become an excellent tool to address a wide range of problems involving fracturing and fragmentation of solids. Within the context of rock mechanics, the FEM/DEM method has been applied to many complex industrial problems such as block caving, deep mining techniques, rock blasting, seismic waves, packing problems, rock crushing problems, etc. In the real world most of the problems involving fracture and fragmentation of solids are three dimensional problems. With the aim of addressing these problems an improved 2D/3D FEM/DEM capability has been developed at Los Alamos National Laboratory (LANL). These capabilities include state of the art 3D contact detection, contact interaction, constitutive material models, and fracture models. In this paper, Split Hopkinson Pressure Bar (SHPB) Brazilian experiments are simulated using this improved 2D/3D FEM/DEM approach which is implemented in LANL's MUNROU (Munjiza-Rougier) code. The results presented in this work show excellent agreement with both the SHPB experiments and previous 2D numerical simulations performed by other FEM/DEM research groups.
Rougier, Esteban [Los Alamos National Laboratory; Bradley, Christopher R. [Los Alamos National Laboratory; Broom, Scott T. [Geomechanics Sandia National Laboratories; Knight, Earl E. [Los Alamos National Laboratory; Munjiza, Ante [School of Engineering and Material Sciences, Queen Mary, University of London; Sussman, Aviva J. [Los Alamos National Laboratory; Swift, Robert P. [Los Alamos National Laboratory
Pollution error in the h-version of the finite-element method and the local quality of a-posteriori error estimators
In this work we study the pollution-error in the h-version of the finite element method and its effect on the local quality of a-posteriori error estimators. We show that the pollution-effect in an interior subdomain depends on the relationship between the mesh inside and outside the subdomain and the smoothness of the exact solution. We also demonstrate that it is possible to guarantee the quality of local error-estimators in the interior of a finite-element mesh-subdomain of interest by employing meshes which are sufficiently refined outside the subdomain.
Mathur, Anuj
Adaptive Mesh Refinement Solution Techniques for the Multigroup SN Transport Equation Using a Higher-Order Discontinuous Finite Element Method
In this dissertation, we develop Adaptive Mesh Refinement (AMR) techniques for the steady-state multigroup SN neutron transport equation using a higher-order Discontinuous Galerkin Finite Element Method (DGFEM). We propose two error estimations, a projection-based estimator and a jump-based indicator, both of which are shown to reliably drive the spatial discretization error down using h-type AMR. Algorithms to treat the mesh irregularity resulting from the local refinement are implemented in a matrix-free fashion. The DGFEM spatial discretization scheme employed in this research allows the easy use of adapted meshes and can, therefore, follow the physics tightly by generating group-dependent adapted meshes. Indeed, the spatial discretization error is controlled with AMR for the entire multigroup SNtransport simulation, resulting in group-dependent AMR meshes. The computing efforts, both in memory and CPU-time, are significantly reduced. While the convergence rates obtained using uniform mesh refinement are limited by the singularity index of transport solution (3/2 when the solution is continuous, 1/2 when it is discontinuous), the convergence rates achieved with mesh adaptivity are superior. The accuracy in the AMR solution reaches a level where the solution angular error (or ray effects) are highlighted by the mesh adaptivity process. The superiority of higherorder calculations based on a matrix-free scheme is verified on modern computing architectures. A stable symmetric positive definite Diffusion Synthetic Acceleration (DSA) scheme is devised for the DGFEM-discretized transport equation using a variational argument. The Modified Interior Penalty (MIP) diffusion form used to accelerate the SN transport solves has been obtained directly from the DGFEM variational form of the SN equations. This MIP form is stable and compatible with AMR meshes. Because this MIP form is based on a DGFEM formulation as well, it avoids the costly continuity requirements of continuous finite elements. It has been used as a preconditioner for both the standard source iteration and the GMRes solution technique employed when solving the transport equation. The variational argument used in devising transport acceleration schemes is a powerful tool for obtaining transportconforming diffusion schemes. xuthus, a 2-D AMR transport code implementing these findings, has been developed for unstructured triangular meshes.
Wang, Yaqi
Antenna Optimization By Using Finite Element Programs
Ion Cyclotron Frequency Heating and Current Drive play an important role in fusion experiments. The recent availability of powerful commercial finite element programs for PCÆs
F. Braun; ICRF Group
OOF: Finite Element Analysis of Microstructures - TMS
Feb 7, 2007 ... Topic Title: OOF: Finite Element Analysis of Microstructures ... and the RAM available to perform a simulation spans somewhere between threeĀ...
Efficient, accurate and flexible finite element solvers for chemotaxis problems
In the framework of finite element discretizations, we introduce a fully nonlinear Newton-like method and a linearized second order approach in time applied to certain partial differential equations for chemotactic processes incorporating two entities, ... Keywords: Chemotaxis model, Finite element, Monolithic, Newton, Nonlinear, Pattern formation
Robert Strehl; Andriy Sokolov; Stefan Turek
Explicit finite element analysis of lightly reinforced masonry shear walls
Explicit finite element analysis (FEA) of masonry shear walls containing reinforcement at spacing between 800mm and 2000mm, referred to as wide spaced reinforced masonry (WSRM), are modelled using macroscopic material characteristics for the unreinforced ... Keywords: Characteristic length, Ductility, Explicit finite element method, Failure mode, Masonry shear walls: Reinforced masonry, Quasi-static modelling
M. Dhanasekar; W. Haider
Electron-H{sub 2}{sup +} scattering using the finite-element method with iterative-variational solution of the algebraic problem
Coulomb Sturmians are used to calculate the ground state of H{sub 2}{sup +}. The required multicenter integrals are calculated to very high accuracy in momentum space. Differential cross sections describing electron scattering from the ground state of H{sub 2}{sup +} are then calculated using the finite element method. The solution of the resulting linear algebraic problem is accomplished using the iterative-variational method.
Weatherford, C.A.
Machining processes simulation: specific finite element aspects
The paper presents a simulation tool designed to predict form errors of part surfaces obtained by face milling and turning processes. For these operations, the form error is often due to the flexibility of the workpiece and its supports. The finite element ... Keywords: finite elements, milling, simulation, turning
Luc Masset; Jean-Francois Debongnie
Numerical Modeling of Hydraulic Fracture Propagation Using Thermo-hydro-mechanical Analysis with Brittle Damage Model by Finite Element Method
Better understanding and control of crack growth direction during hydraulic fracturing are essential for enhancing productivity of geothermal and petroleum reservoirs. Structural analysis of fracture propagation and impact on fluid flow is a challenging issue because of the complexity of rock properties and physical aspects of rock failure and fracture growth. Realistic interpretation of the complex interactions between rock deformation, fluid flow, heat transfer, and fracture propagation induced by fluid injection is important for fracture network design. In this work, numerical models are developed to simulate rock failure and hydraulic fracture propagation. The influences of rock deformation, fluid flow, and heat transfer on fracturing processes are studied using a coupled thermo-hydro-mechanical (THM) analysis. The models are used to simulate microscopic and macroscopic fracture behaviors of laboratory-scale uniaxial and triaxial experiments on rock using an elastic/brittle damage model considering a stochastic heterogeneity distribution. The constitutive modeling by the energy release rate-based damage evolution allows characterizing brittle rock failure and strength degradation. This approach is then used to simulate the sequential process of heterogeneous rock failures from the initiation of microcracks to the growth of macrocracks. The hydraulic fracturing path, especially for fractures emanating from inclined wellbores and closed natural fractures, often involves mixed mode fracture propagation. Especially, when the fracture is inclined in a 3D stress field, the propagation cannot be modeled using 2D fracture models. Hence, 2D/3D mixed-modes fracture growth from an initially embedded circular crack is studied using the damage mechanics approach implemented in a finite element method. As a practical problem, hydraulic fracturing stimulation often involves fluid pressure change caused by injected fracturing fluid, fluid leakoff, and fracture propagation with brittle rock behavior and stress heterogeneities. In this dissertation, hydraulic fracture propagation is simulated using a coupled fluid flow/diffusion and rock deformation analysis. Later THM analysis is also carried out. The hydraulic forces in extended fractures are solved using a lubrication equation. Using a new moving-boundary element partition methodology (EPM), fracture propagation through heterogeneous media is predicted simply and efficiently. The method allows coupling fluid flow and rock deformation, and fracture propagation using the lubrication equation to solve for the fluid pressure through newly propagating crack paths. Using the proposed model, the 2D/3D hydraulic fracturing simulations are performed to investigate the role of material and rock heterogeneity. Furthermore, in geothermal and petroleum reservoir design, engineers can take advantage of thermal fracturing that occurs when heat transfers between injected flow and the rock matrix to create reservoir permeability. These thermal stresses are calculated using coupled THM analysis and their influence on crack propagation during reservoir stimulation are investigated using damage mechanics and thermal loading algorithms for newly fractured surfaces.
Min, Kyoung
Finite element analysis of multilayer coextrusion.
Multilayer coextrusion has become a popular commercial process for producing complex polymeric products from soda bottles to reflective coatings. A numerical model of a multilayer coextrusion process is developed based on a finite element discretization and two different free-surface methods, an arbitrary-Lagrangian-Eulerian (ALE) moving mesh implementation and an Eulerian level set method, to understand the moving boundary problem associated with the polymer-polymer interface. The goal of this work is to have a numerical capability suitable for optimizing and troubleshooting the coextrusion process, circumventing flow instabilities such as ribbing and barring, and reducing variability in layer thickness. Though these instabilities can be both viscous and elastic in nature, for this work a generalized Newtonian description of the fluid is used. Models of varying degrees of complexity are investigated including stability analysis and direct three-dimensional finite element free surface approaches. The results of this work show how critical modeling can be to reduce build test cycles, improve material choices, and guide mold design.
Hopkins, Matthew Morgan; Schunk, Peter Randall; Baer, Thomas A. (Proctor & Gamble Company, West Chester, OH); Mrozek, Randy A. (Army Research Laboratory, Adelphi, MD); Lenhart, Joseph Ludlow (Army Research Laboratory, Adelphi, MD); Rao, Rekha Ranjana; Collins, Robert (Oak Ridge National Laboratory); Mondy, Lisa Ann
Operator-splitting finite element algorithms for computations of high-dimensional parabolic problems
Operator-splitting finite element algorithms for computations of high-dimensional parabolic t i c l e i n f o Keywords: Operator-splitting method Finite element method Parabolic equations High-dimensional problems a b s t r a c t An operator-splitting finite element method for solving high-dimensional parabolic
Ganesan, Sashikumaar
Finite-Element Solutions of Free-Interface Density Currents
An interface-adaptive finite-element iteration scheme is designed to solve for the free interface of an inviscid steady-state density current. The method is also applied to free-surface flows over finite obstacles, but convergent solutions are ...
Qin Xu; Fu-Shen Zhang; Guang-Ping Lou
Global Superconvergence and A Posteriori Error Estimators of the Finite Element Method for a Quasi-linear Elliptic Boundary Value Problem of Nonmonotone Type
In this paper we are concerned with finite element approximations to a nonlinear elliptic partial differential equation with homogeneous Dirichlet boundary conditions. This kind of problems arises for example from modeling a stationary heat conduction ... Keywords: a posteriori error estimators, anisotropic heat conduction, finite elements, global superconvergence, nonlinear boundary problem, supercloseness
Liping Liu; Tang Liu; Michal KrĒzek; Tao Lin; Shuhua Zhang
Solid Mechanics/Finite-Element Analysis Software/Codes - TMS
CalculiX - A Free Software Three-Dimensional Structural Finite Element Program G. Dhondt and K. Wittig. Open Source (GPL) 3-D Finite Element MechanicsĀ...
Finite element form of FDV for widely varying flowfields
We present the Flowfield Dependent Variation (FDV) method for physical applications that have widely varying spatial and temporal scales. Our motivation is to develop a versatile numerical method that is accurate and stable in simulations with complex ... Keywords: Finite element, Hydrodynamics, Numerical methods, Shock waves, Special relativity
G. A. Richardson; J. T. Cassibry; T. J. Chung; S. T. Wu
parts of the kinetic energy matrix, dropping the surfacew n . The kinetic energy and potential matrix elements are
McCurdy, C.W.
ME 452 Finite Element Analysis Every Semester
ME 452 Finite Element Analysis Elective Every Semester 2004-2005 Catalog Data: Conversion. Extensive computer lab experiments using Matlab-based and commercial software systems. Prereq: ME 321, 344 of proper boundary conditions and nodal loads. 6. Conversion of distributed loads to work equivalent nodal
Mench, Matthew M.
Finite-Element Project ABAQUS Tutorial
#12;1 Introduction ABAQUS is a finite-element analysis software. Abaqus/CAE provides a pre- processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 3.6 Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 3.7 Mesh and postprocessing environment for the analysis of models. It is used in a wide range of industries like automotive
Berlin,Technische Universit├żt
Development of a Two-Dimensional Finite-Element PBL Model and Two Preliminary Model Applications
We have developed a two-dimensional finite-element model for simulating atmospheric flow in the planetary boundary layer (PBL) of the earth. The finite-element method provides a useful alternative to the conventional finite-difference method in ...
L. P. Chang; E. S. Takle; R. L. Sani
Finite element analysis of the electro jet drilling process
The electro jet drilling (EJD) process is gaining prominence in the machining of micro and macro holes in difficult-to-machine materials used in aerospace, electronics and computers, medical, and automobile industries. As the trend towards miniaturization ... Keywords: electro jet drilling, electrochemical drilling, finite element method, radial overcut
M. Sen; H. S. Shan
BOR-FDTD subgridding based on finite element principles
In this paper a recently developed provably passive and stable 3D FDTD subgridding technique, based on finite elements principles, is extended to body-of-revolution (BOR) FDTD. First, a suitable choice of basis functions is presented together with the ... Keywords: BOR-FDTD, Body-of-revolution, FDTD methods, Subgridding, h-Refinement
Wouter Tierens; Daniļl De Zutter
Finite element modeling of borehole heat exchanger systems
Single borehole heat exchanger (BHE) and arrays of BHE are modeled by using the finite element method. Applying BHE in regional discretizations optimal conditions of mesh spacing around singular BHE nodes are derived. Optimal meshes have shown superior ... Keywords: Borehole heat exchanger, Borehole thermal energy store, FEFLOW, TRNSYS
H. -J. G. Diersch; D. Bauer; W. Heidemann; W. R³haak; P. Schõtzl
A Direct Inverse Method for Inferring Open Boundary Conditions of a Finite-Element Linear Harmonic Ocean Circulation Model
A direct inverse method is presented for inferring numerical model open boundary conditions from interior observational data. The dynamical context of the method is the frequency-domain 3D linear shallow water equations. A set of weight matrices ...
Zhigang Xu
Brief paper: Distributed parameter system optimum control design via finite element discretization
The problem of designing an optimum distributed parameter system is considered. Fundamental concepts pertaining to the solution of optimum controls for distributed parameter systems by finite element methods are devised. It is demonstrated that methods ... Keywords: Distributed parameter systems, finite element method, numerical methods, optimal control, partial differential equations
R. K. Cavin, III; S. C. Tandon
FEHM (Finite Element Heat and Mass Transfer Code)
NLE Websites -- All DOE Office Websites (Extended Search)
FEHM (Finite Element Heat and Mass Transfer Code) FEHM (Finite Element Heat and Mass Transfer Code) FEHM is used to simulate groundwater and contaminant flow and transport in deep...
Component mode synthesis methods applied to 3D heterogeneous core calculations, using the mixed dual finite element solver MINOS
This paper describes a new technique for determining the pin power in heterogeneous core calculations. It is based on a domain decomposition with overlapping sub-domains and a component mode synthesis technique for the global flux determination. Local basis functions are used to span a discrete space that allows fundamental global mode approximation through a Galerkin technique. Two approaches are given to obtain these local basis functions: in the first one (Component Mode Synthesis method), the first few spatial eigenfunctions are computed on each sub-domain, using periodic boundary conditions. In the second one (Factorized Component Mode Synthesis method), only the fundamental mode is computed, and we use a factorization principle for the flux in order to replace the higher order Eigenmodes. These different local spatial functions are extended to the global domain by defining them as zero outside the sub-domain. These methods are well-fitted for heterogeneous core calculations because the spatial interface modes are taken into account in the domain decomposition. Although these methods could be applied to higher order angular approximations - particularly easily to a SPN approximation - the numerical results we provide are obtained using a diffusion model. We show the methods' accuracy for reactor cores loaded with UOX and MOX assemblies, for which standard reconstruction techniques are known to perform poorly. Furthermore, we show that our methods are highly and easily parallelizable. (authors)
Guerin, P.; Baudron, A. M.; Lautard, J. J. [Commissariat a l'Energie Atomique, DEN/DANS/DM2S/SERMA/LENR, CEA Saclay, 91191 Gif sur Yvette (France)
Summary of the Models and Methods for the FEHM Application-A Finite-Element Heat- and Mass-Transfer Code
DOE Green Energy (OSTI)
The mathematical models and numerical methods employed by the FEHM application, a finite-element heat- and mass-transfer computer code that can simulate nonisothermal multiphase multi-component flow in porous media, are described. The use of this code is applicable to natural-state studies of geothermal systems and groundwater flow. A primary use of the FEHM application will be to assist in the understanding of flow fields and mass transport in the saturated and unsaturated zones below the proposed Yucca Mountain nuclear waste repository in Nevada. The component models of FEHM are discussed. The first major component, Flow- and Energy-Transport Equations, deals with heat conduction; heat and mass transfer with pressure- and temperature-dependent properties, relative permeabilities and capillary pressures; isothermal air-water transport; and heat and mass transfer with noncondensible gas. The second component, Dual-Porosity and Double-Porosity/Double-Permeability Formulation, is designed for problems dominated by fracture flow. Another component, The Solute-Transport Models, includes both a reactive-transport model that simulates transport of multiple solutes with chemical reaction and a particle-tracking model. Finally, the component, Constitutive Relationships, deals with pressure- and temperature-dependent fluid/air/gas properties, relative permeabilities and capillary pressures, stress dependencies, and reactive and sorbing solutes. Each of these components is discussed in detail, including purpose, assumptions and limitations, derivation, applications, numerical method type, derivation of numerical model, location in the FEHM code flow, numerical stability and accuracy, and alternative approaches to modeling the component.
George A. Zyvoloski; Bruce A. Robinson; Zora V. Dash; Lynn L. Trease
FEHM: finite element heat and mass transfer code
The finite element heat and mass (FEHM) transfer code is a computer code developed to simulate geothermal and hot dry rock reservoirs. It is also applicable to natural-state studies of geothermal systems and ground-water flow. It solves the equations of heat and mass transfer for multiphase flow in porous and permeable media using the finite element method. The code also has provisions for a noncoupled tracer; that is, the tracer solutions do not affect the heat and mass transfer solutions. It can simulate two-dimensional, two-dimensional radial, or three-dimensional geometries. A summary of the equations in the model, the numerical solution procedure, and model verification and validation are provided in this report. A user's guide and sample problems are included in the appendices. 17 refs., 10 figs., 4 tabs.
Zyvoloski, G.; Dash, Z.; Kelkar, S.
OOF: Finite Element Analysis of Microstructures, OOF2 - TMS
May 8, 2007 ... Topic Title: OOF: Finite Element Analysis of Microstructures, OOF2 ... and the RAM available to perform a simulation spans somewhereĀ...
Finite Element Analysis of Erosion for Offshore Structure
Presentation Title, Finite Element Analysis of Erosion for Offshore Structure ... impacting, is one of the major failure modes that cause offshore structure damage .
The finite element analysis of water vapor diffusion in a brick with vertical holes
This paper presents a finite element analysis of water vapor diffusion in a brick with vertical holes. The isotherms, isodensity, isopressure and isohumidity surfaces considering the longitudinal and transverse direction diffusion of water vapor in a ... Keywords: brick wall, diffusion, finite element method (FEM), numerical simulation
Madalina Calbureanu; Mihai Talu; Carlos Manuel Travieso-Gonzßlez; Stefan Talu; Mihai Lungu; Raluca Malciu
Algebraic multigrid for stabilized finite element discretizations of the Navier Stokes equation
A multilevel method for the solution of systems of equations generated by stabilized Finite Element discretizations of the Euler and Navier Stokes equations on generalized unstructured grids is described. The method is ...
Okusanya, Tolulope Olawale, 1972 -
Energy conserving Anisotropic Anhysteretic Magnetic Modelling for Finite Element Analysis
To model ferromagnetic material in finite element analysis a correct description of the constitutive relationship (BH-law) must be found from measured data. This article proposes to use the energy density function as a centrepiece. Using this function, which turns out to be a convex function of the flux density, guarantees energy conservative modelling. The magnetic field strength can be seen as a derivative with respect to the flux density. Especially for anisotropic materials (from lamination and/or grain orientation) this method has advantages. Strictly speaking this method is only valid for anhysteretic and thermodynamically stable material.
Jens Krause
Finite element-based probabilistic analysis tool for orthopaedic applications
Orthopaedic implants, as well as other physical systems, contain inherent variability in geometry, material properties, component alignment, and loading conditions. While complex, deterministic finite element (FE) models do not account for the potential ... Keywords: Finite element modeling, Orthopaedic implants, Probabilistic modeling, Reliability, Sensitivity, Variability
Sarah K. Easley; Saikat Pal; Paul R. Tomaszewski; Anthony J. Petrella; Paul J. Rullkoetter; Peter J. Laz
Nonconforming cell boundary element methods for elliptic problems on triangular mesh
The nonconforming cell boundary element (CBE) methods are proposed. The methods are designed in such a way that they enjoy the mass conservation at the element level and the normal component of fluxes at inter-element boundaries are continuous for unstructured ... Keywords: Multiscale method, 65N12, 65N30, Cell boundary element method, Finite volume, Flux conservation, Mixed finite element, Nonconforming finite element
Youngmok Jeon; Eun-Jae Park
The Study on Finite Element Analysis for Anchor Support System Optimization
The anchor support design is important for the design of underground engineering. The process of optimizing the anchor support design is analyzed, the finite element method is applied to it. The anchor support system is developed including fore--process, ...
Wang Lixin; Duan Lixia
A displacement-based nonlinear finite element formulation using meshfree-enriched triangular elements for the two-dimensional large deformation analysis of elastomers
In this paper a displacement-based meshfree-enriched finite element method, which was proposed for the linear modeling of near-incompressible elasticity, is generalized for the nonlinear analysis of elastomers. A four-noded triangular element based on ... Keywords: Elastomers, Finite element, Meshfree, Near-incompressible, Nonlinear
W. Hu; C. T. Wu; M. Koishi
Adaptive iterative multiscale finite volume method
The multiscale finite volume (MSFV) method is a computationally efficient numerical method for the solution of elliptic and parabolic problems with heterogeneous coefficients. It has been shown for a wide range of test cases that the MSFV results are ... Keywords: Adaptive multiscale method, Elliptic problem, Infrequently localization improvement, Iterative multiscale finite-volume method, Iterative multiscale method, Multiphase flow, Multiscale finite-volume method, Multiscale method, Porous media
Hadi Hajibeygi; Patrick Jenny
Iterative solutions to large sparse finite element equations
Iterative methods are widely used to solve sparse linear systems due to the improvements which can be achieved in reducing the solution time and increasing the size of the problem which can be solved on a given computer compared to traditional direct solvers. The theory behind the convergence rate relationship and storage requirements for the preconditioned conjugate gradient methods using the diagonal scaling, incomplete Cholesky decomposition and SSOR preconditioners is explained in detail in this study. Sparse matrix storage techniques, such as profile, element-by-element, and compact row storage, are described along with the redefined matrix operations for each storage technique which must be used to eliminate the operations on zero elements. A procedure to directly assemble the global stiffness in compact row storage format from element stiffness matrices is introduced. Numerical studies have been performed to compare the storage requirements, the convergence rate, and the solution time for the direct and PCG methods using various storage formats. Effects of different material properties and external loading on the convergence rate and solution time are also analyzed. The test problems for this study are based on the three-dimensional linear elasticity finite element equations. The physical memory of 64 MB of RAM of the IBM RISC/6000 Model 355 workstation was the limiting factor for the size of the sparse linear system that could be solved in this study. The diagonal preconditioned conjugate gradient method with the compact row storage has solved a three-dimensional finite element problem up to a maximum of 50,000 equations on an IBM RISC/6000 Model 355 workstation with 64 MB of RAM. To apply adaptive mesh refinement on certain regions of a coarse mesh, the modeling error over a coarse mesh must be estimated. This thesis will show that the modeling error from an intermediate unconverged coarse mesh solution will closely match the modeling error from the converged solution. This result may lead to quicker solution times for a highly accurate mesh based on adaptive mesh refinement iterative methods.
Wang, Hongbing
FEHM (Finite Element Heat and Mass Transfer Code) FEHM (Finite Element Heat and Mass Transfer Code) FEHM (Finite Element Heat and Mass Transfer Code) FEHM is used to simulate groundwater and contaminant flow and transport in deep and shallow, fractured and un-fractured porous media throughout the US DOE complex. June 29, 2013 software FEHM is used to simulate groundwater and contaminant flow and transport in deep and shallow, fractured and un-fractured porous media throughout the US DOE complex. Available for thumbnail of Feynman Center (505) 665-9090 Email FEHM (Finite Element Heat and Mass Transfer Code) FEHM is used to simulate groundwater and contaminant flow and transport in deep and shallow, fractured and un-fractured porous media throughout the US DOE complex. FEHM has proved to be a valuable asset on a variety of
A frequency domain finite element model for tidal circulation
A highly efficient finite element model has been developed for the numerical prediction of depth average circulation within small scale embayments which are often characterized by irregular boundaries and bottom topography.
Westerink, Joannes J.
A geometrically-conservative, synchronized, flux-corrected remap for arbitrary Lagrangian-Eulerian computations with nodal finite elements
This article describes a conservative synchronized remap algorithm applicable to arbitrary Lagrangian-Eulerian computations with nodal finite elements. In the proposed approach, ideas derived from flux-corrected transport (FCT) methods are extended to ... Keywords: Arbitrary Lagrangian-Eulerian methods, Compatible discretizations, Geometric conservation law, Meteorological flows, Nodal finite element method, Remap, Shock hydrodynamics
A. L¾Pez Ortega; G. Scovazzi
Two-dimensional finite element multigroup diffusion theory for neutral atom transport in plasmas
Solution of the energy dependent diffusion equation in two dimensions is formulated by multigroup approximation of the energy variable and general triangular mesh, finite element discretization of the spatial domain. Finite element formulation is done by Galerkin's method. Based on this formulation, a two-dimensional multigroup finite element diffusion theory code, FENAT, has been developed for the transport of neutral atoms in fusion plasmas. FENAT solves the multigroup diffusion equation in X-Y cartesian and R-Z cylindrical/toroidal geometries. Use of the finite element method allows solution of problems in which the plasma cross-section has an arbitrary shape. The accuracy of FENAT has been verified by comparing results to those obtained using the two-dimensional discrete ordinate transport theory code, DOT-4.3. Results of application of FENAT to the transport of limiter-originated neutral atoms in a tokamak fusion machine are presented.
Hasan, M.Z.; Conn, R.W.
Surface photovoltage measurements and finite element modeling of SAW devices.
Over the course of a Summer 2011 internship with the MEMS department of Sandia National Laboratories, work was completed on two major projects. The first and main project of the summer involved taking surface photovoltage measurements for silicon samples, and using these measurements to determine surface recombination velocities and minority carrier diffusion lengths of the materials. The SPV method was used to fill gaps in the knowledge of material parameters that had not been determined successfully by other characterization methods. The second project involved creating a 2D finite element model of a surface acoustic wave device. A basic form of the model with the expected impedance response curve was completed, and the model is ready to be further developed for analysis of MEMS photonic resonator devices.
Donnelly, Christine
A finite element model for three dimensional hydraulic fracturing
This paper is devoted to the development of a model for the numerical simulation of hydraulic fracturing processes with 3d fracture propagation. It takes into account the effects of fluid flow inside the fracture, fluid leak-off through fracture walls ... Keywords: boundary elements, finite elements, hydraulic fracturing, petroleum recovery
Philippe R. B. Devloo; Paulo Dore Fernandes; S¶nia M. Gomes; Cedric Marcelo Augusto Ayala Bravo; Renato Gomes Damas
Implementation of B-splines in a Conventional Finite Element Framework
The use of B-spline interpolation functions in the finite element method (FEM) is not a new subject. B-splines have been utilized in finite elements for many reasons. One reason is the higher continuity of derivatives and smoothness of B-splines. Another reason is the possibility of reducing the required number of degrees of freedom compared to a conventional finite element analysis. Furthermore, if B-splines are utilized to represent the geometry of a finite element model, interfacing a finite element analysis program with existing computer aided design programs (which make extensive use of B-splines) is possible. While B-splines have been used in finite element analysis due to the aforementioned goals, it is difficult to find resources that describe the process of implementing B-splines into an existing finite element framework. Therefore, it is necessary to document this methodology. This implementation should conform to the structure of conventional finite elements and only require exceptions in methodology where absolutely necessary. One goal is to implement B-spline interpolation functions in a finite element framework such that it appears very similar to conventional finite elements and is easily understandable by those with a finite element background. The use of B-spline functions in finite element analysis has been studied for advantages and disadvantages. Two-dimensional B-spline and standard FEM have been compared. This comparison has addressed the accuracy as well as the computational efficiency of B-spline FEM. Results show that for a given number of degrees of freedom, B-spline FEM can produce solutions with lower error than standard FEM. Furthermore, for a given solution time and total analysis time B-spline FEM will typically produce solutions with lower error than standard FEM. However, due to a more coupled system of equations and larger elemental stiffness matrix, B-spline FEM will take longer per degree of freedom for solution and assembly times than standard FEM. Three-dimensional B-spline FEM has also been validated by the comparison of a three-dimensional model with plane-strain boundary conditions to an equivalent two-dimensional model using plane strain conditions.
Owens, Brian C.
Experimental and finite element analysis of high pressure packer elements
Packer elements are traditionally rubber seals that can operate under specified downhole conditions and provide a seal for either a short-term, retrievable, or a long-term, permanent, completion. In this case a retrievable ...
Berger, Stephanie, 1981-
On using moving windows in finite element time domain simulation for long accelerator structures
A finite element moving window technique is developed to simulate the propagation of electromagnetic waves induced by the transit of a charged particle beam inside large and long structures. The window moving along with the beam in the computational domain adopts high-order finite element basis functions through p refinement and/or a high-resolution mesh through h refinement so that a sufficient accuracy is attained with substantially reduced computational costs. Algorithms to transfer discretized fields from one mesh to another, which are the keys to implementing a moving window in a finite element unstructured mesh, are presented. Numerical experiments are carried out using the moving window technique to compute short-range wakefields in long accelerator structures. The results are compared with those obtained from the normal finite element time domain (FETD) method and the advantages of using the moving window technique are discussed.
Lee, L.-Q., E-mail: firstname.lastname@example.com [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Candel, Arno; Ng, Cho; Ko, Kwok [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States)
Multi-element microelectropolishing method
A method is provided for microelectropolishing a transmission electron microscopy nonhomogeneous multi-element compound foil. The foil is electrolyzed at different polishing rates for different elements by rapidly cycling between different current densities. During a first portion of each cycle at a first voltage a first element electrolyzes at a higher current density than a second element such that the material of the first element leaves the anode foil at a faster rate than the second element and creates a solid surface film, and such that the solid surface film is removed at a faster rate than the first element leaves the anode foil. During a second portion of each cycle at a second voltage the second element electrolyzes at a higher current density than the first element, and the material of the second element leaves the anode foil at a faster rate than the first element and creates a solid surface film, and the solid surface film is removed at a slower rate than the second element leaves the foil. The solid surface film is built up during the second portion of the cycle, and removed during the first portion of the cycle. 10 figs.
Lee, P.J.
A method is provided for microelectropolishing a transmission electron microscopy nonhomogeneous multi-element compound foil. The foil is electrolyzed at different polishing rates for different elements by rapidly cycling between different current densities. During a first portion of each cycle at a first voltage a first element electrolyzes at a higher current density than a second element such that the material of the first element leaves the anode foil at a faster rate than the second element and creates a solid surface film, and such that the solid surface film is removed at a faster rate than the first element leaves the anode foil. During a second portion of each cycle at a second voltage the second element electrolyzes at a higher current density than the first element, and the material of the second element leaves the anode foil at a faster rate than the first element and creates a solid surface film, and the solid surface film is removed at a slower rate than the second element leaves the foil. The solid surface film is built up during the second portion of the cycle, and removed during the first portion of the cycle.
Lee, Peter J. (Middleton, WI)
Experience with automatic, dynamic load balancing and adaptive finite element computation
Distributed memory, Massively Parallel (MP), MIMD technology has enabled the development of applications requiring computational resources previously unobtainable. Structural mechanics and fluid dynamics applications, for example, are often solved by finite element methods (FEMs) requiring, millions of degrees of freedom to accurately simulate physical phenomenon. Adaptive methods, which automatically refine or coarsen meshes and vary the order of accuracy of the numerical solution, offer greater robustness and computational efficiency than traditional FEMs by reducing the amount of computation required away from physical structures such as shock waves and boundary layers. On MP computers, FEMs frequently result in distributed processor load imbalances. To overcome load imbalance, many MP FEMs use static load balancing as a preprocessor to the finite element calculation. Adaptive methods complicate the load imbalance problem since the work per element is not uniform across the solution domain and changes as the computation proceeds. Therefore, dynamic load balancing is required to maintain global load balance. We describe a dynamic, fine-grained, element-based data migration system that maintains global load balance and is effective in the presence of changing work loads. Global load balance is achieved by overlapping neighborhoods of processors, where each neighborhood performs local load balancing. The method utilizes an automatic element management system library to which a programmer integrates the application`s computational description. The library`s flexibility supports a large class of finite element and finite difference based applications.
Wheat, S.R. [Sandia National Labs., Albuquerque, NM (United States); Devine, K.D. [Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Computer Science; Maccabe, A.B. [New Mexico Univ., Albuquerque, NM (United States). Dept. of Computer Science
Finite element modeling of transmission line under downburst wind loading
Despite the fact that extensive research has been carried out on transmission lines subjected to normal wind loads, their behaviour under high intensity wind loads (HIW), such as downburst, is poorly defined. This paper describes a detailed numerical ... Keywords: Downbursts, Finite element, Microbursts, Transmission line, Transmission tower, Wind load
A. Y. Shehata; A. A. El Damatty; E. Savory
Efficient Finite Element Modeling of Shallow Geothermal Systems
This paper presents a finite element modeling technique for double U-tube borehole heat exchangers (BHE) and the surrounding soil mass. Focus is placed on presenting numerical analyses describing the capability of a BHE model, previously introduced by ... Keywords: Geothermic, BHE, Heat transfer
Rafid Al-Khoury
Finite element analysis of laterally loaded fin piles
A three-dimensional analysis of laterally loaded fin piles is presented. The behaviour of fin piles is difficult to explain using simple pile-soil theories or two dimensional numerical analyses because of the complicated geometry of the piles. In this ... Keywords: 3D finite element models, Capacity of laterally loaded piles, Efficiency of fins, Fin piles, Mohr-Coulomb soil model, Monopiles
J. -R. Peng; M. Rouainia; B. G. Clarke
Modeling and computation of two phase geometric biomembranes using surface finite elements
Biomembranes consisting of multiple lipids may involve phase separation phenomena leading to coexisting domains of different lipid compositions. The modeling of such biomembranes involves an elastic or bending energy together with a line energy associated ... Keywords: Lipid bilayer, Multi-component membrane, Numerical simulation, Phase field method, Relaxation dynamics, Surface finite element method
Charles M. Elliott; Bj÷rn Stinner
Finite element lattice Boltzmann simulations of free surface flow in a concentric cylinder
The annular centrifugal contactor is a compact mixer/centrifuge device designed for liquid-liquid extraction operations in processes for recycling nuclear fuel. The flow in the annulus of a centrifugal contactor is similar to the Taylor vortex flow with ... Keywords: Concentric cylinder, Finite element method, Free surface flow, Lattice Boltzmann method
Kent E. Wardle; Taehun Lee
Inversion of Robin coefficient by a spectral stochastic finite element approach
This paper investigates a variational approach to the nonlinear stochastic inverse problem of probabilistically calibrating the Robin coefficient from boundary measurements for the steady-state heat conduction. The problem is formulated into an optimization ... Keywords: Conjugate gradient method, Robin inverse problem, Spectral stochastic finite element method, Stochastic inverse problems, Uncertainty quantification
Bangti Jin; Jun Zou
FEWA: a Finite Element model of Water flow through Aquifers
This report documents the implementation and demonstration of a Finite Element model of Water flow through Aquifers (FEWA). The particular features of FEWA are its versatility and flexibility to deal with as many real-world problems as possible. Point as well as distributed sources/sinks are included to represent recharges/pumpings and rainfall infiltrations. All sources/sinks can be transient or steady state. Prescribed hydraulic head on the Dirichlet boundaries and fluxes on Neumann or Cauchy boundaries can be time-dependent or constant. Source/sink strength over each element and node, hydraulic head at each Dirichlet boundary node, and flux at each boundary segment can vary independently of each other. Either completely confined or completely unconfined aquifers, or partially confined and partially unconfined aquifers can be dealt with effectively. Discretization of a compound region with very irregular curved boundaries is made easy by including both quadrilateral and triangular elements in the formulation. Large-field problems can be solved efficiently by including a pointwise iterative solution strategy as an optional alternative to the direct elimination solution method for the matrix equation approximating the partial differential equation of groundwater flow. FEWA also includes transient flow through confining leaky aquifers lying above and/or below the aquifer of interest. The model is verified against three simple cases to which analytical solutions are available. It is then demonstrated by two examples of how the model can be applied to heterogeneous and anisotropic aquifers with transient boundary conditions, time-dependent sources/sinks, and confining aquitards for a confined aquifer of variable thickness and for a free surface problem in an unconfined aquifer, respectively. 20 references, 25 figures, 8 tables.
Yeh, G.T.; Huff, D.D.
Calibration under uncertainty for finite element models of masonry monuments
Historical unreinforced masonry buildings often include features such as load bearing unreinforced masonry vaults and their supporting framework of piers, fill, buttresses, and walls. The masonry vaults of such buildings are among the most vulnerable structural components and certainly among the most challenging to analyze. The versatility of finite element (FE) analyses in incorporating various constitutive laws, as well as practically all geometric configurations, has resulted in the widespread use of the FE method for the analysis of complex unreinforced masonry structures over the last three decades. However, an FE model is only as accurate as its input parameters, and there are two fundamental challenges while defining FE model input parameters: (1) material properties and (2) support conditions. The difficulties in defining these two aspects of the FE model arise from the lack of knowledge in the common engineering understanding of masonry behavior. As a result, engineers are unable to define these FE model input parameters with certainty, and, inevitably, uncertainties are introduced to the FE model.
Atamturktur, Sezer,; Hemez, Francois,; Unal, Cetin
Energy- and enstrophy-conserving schemes for the shallow-water equations, based on mimetic finite elements
This paper presents a family of spatial discretisations of the nonlinear rotating shallow-water equations that conserve both energy and potential enstrophy. These are based on two-dimensional mixed finite element methods, and hence, unlike some finite difference methods, do not require an orthogonal grid. Numerical verification of the aforementioned properties is also provided.
McRae, Andrew T T
Probabilistic risk assessment for the construction phases of a bridge construction based on finite element analysis
To develop a design, engineering, and construction management information sharing system that allow the project participants to effectively share the information throughout the construction life cycle with the support of 3D, design and building information, ... Keywords: Construction phases, Finite element analysis, Improved response surface method, Risk assessment, Virtual construction
Taejun Cho; Tae Soo Kim
Rotation capacity of partial strength steel joints with three-dimensional finite element approach
This paper presents a finite element analysis of partial strength steel joints. The joint configurations are drawn from a previous experimental study, with good prediction shown by the finite element model. Failure of the joint is confined to the end ... Keywords: Ductile fracture, Finite element, Structural joint
Ana M. GirŃO Coelho
A new procedure for the construction of hierarchical high order Hdiv and Hcurl finite element spaces
This paper considers a systematic procedure for the construction of a hierarchy of high order finite element approximation for Hdiv and Hcurl spaces based on triangular and quadrilateral partitions of bidimensional domains. The principle is to choose ... Keywords: Hdiv approximating spaces, Hierarchical finite element bases, Mixed finite element formulations
Denise De Siqueira; Phillipe R. B. Devloo; S¶Nia M. Gomes
Small and large deformation analysis with the p- and B-spline versions of the Finite Cell Method
The Finite Cell Method (FCM) is an embedded domain method, which combines the fictitious domain approach with high-order finite elements, adaptive integration, and weak imposition of unfitted Dirichlet boundary conditions. For smooth problems, FCM has ... Keywords: B-spline version of the Finite Cell Method, Embedded domain methods, Fictitious domain methods, Immersed boundary methods, Large deformation solid mechanics, Weak boundary conditions, p-Version of the Finite Cell Method
Dominik Schillinger; Martin Ruess; Nils Zander; Yuri Bazilevs; Alexander D³ster; Ernst Rank
B-Spline Finite Elements and their Efficiency in Solving Relativistic Mean Field Equations
A finite element method using B-splines is presented and compared with a conventional finite element method of Lagrangian type. The efficiency of both methods has been investigated at the example of a coupled non-linear system of Dirac eigenvalue equations and inhomogeneous Klein-Gordon equations which describe a nuclear system in the framework of relativistic mean field theory. Although, FEM has been applied with great success in nuclear RMF recently, a well known problem is the appearance of spurious solutions in the spectra of the Dirac equation. The question, whether B-splines lead to a reduction of spurious solutions is analyzed. Numerical expenses, precision and behavior of convergence are compared for both methods in view of their use in large scale computation on FEM grids with more dimensions. A B-spline version of the object oriented C++ code for spherical nuclei has been used for this investigation.
W. Poeschl
P÷schl, W
Essential Boundary Conditions with Straight C1 Finite Elements in Curved Domains
The implementation of essential boundary conditions in C1 finite element analysis requires proper treatment of both the boundary conditions on second-order differentials of the solution and the curvature of the domain boundary. A method for the imposition of essential boundary conditions using straight elements (where the elements are not deformed to approximate a curved domain) is described. It is shown that pre-multiplication of the matrix equation by the local rotation matrix at each boundary node is not the optimal transformation. The uniquely optimal transformation is found, which does not take the form of a similarity transformation due to the non-orthogonality of the transformation to curved coordinates.
N.M. Ferraro, S.C. Jardin, X. Luo
Conditions for the invertibility of the isoparametric mapping for hexahedral finite elements
We consider the isoparametric mapping, which maps a given reference element onto a global element given by its vertices, for trilinear finite elements on hexahedra. We present an algorithm that checks the positivity of the Jacobian determinant depending ... Keywords: hexahedral finite elements, invertibility, isoparametric mapping
P. Knabner; S. Korotov; G. Summ
Fidelity of a Finite Element Model for Longitudinal Wave Propagation in Thick Cylindrical Wave Guides
The ability to model wave propagation in circular cylindrical bars of finite length numerically or analytically has many applications. In this thesis the capability of an explicit finite element method to model longitudinal waves in cylindrical rods with circular cross-sections is explored. Dispersion curves for the first four modes are compared to the analytical solution to determine the accuracy of various element sizes and time steps. Values for the time step and element size are determined that retain accuracy while minimizing computational time. The modeling parameters are validated by calculating a signal propagated with a broadband input force. Limitations on the applicability are considered along with modeling parameters that should be applicable to more general geometries.
Puckett, A.D.
Mimetic finite difference method for the Stokes problem on polygonal meshes
Various approaches to extend finite element methods to non-traditional elements (general polygons, pyramids, polyhedra, etc.) have been developed over the last decade. The construction of basis functions for such elements is a challenging task and may ... Keywords: Incompressible Stokes equations, Mimetic discretization, Polygonal mesh
L. BeirŃo da Veiga; V. Gyrya; K. Lipnikov; G. Manzini
A method is described for fabricating fuel elements, particularly for enclosing a plate of metal with a second metal by inserting the plate into an aperture of a frame of a second plate, placing a sheet of the second metal on each of opposite faces of the assembled plate and frame, purging with an inert gas the air from the space within the frame and the sheets while sealing the seams between the frame and the sheets, exhausting the space, purging the space with air, re-exhausting the spaces, sealing the second aperture, and applying heat and pressure to bond the sheets, the plate, and the frame to one another.
Bean, C.H.; Macherey, R.E.
From Single-Phase To Compositional Flow: Applicability Of Mixed Finite Elements
. In this paper we discuss the formulation of the governing equations that describe flow of fluids in porous media. Various types of fluid flow, ranging from single-phase flow to compositional flow, are considered. It is shown that all the differential equations governing these types of flow can be effectively rewritten in a fractional flow formulation; i.e., in terms of a global pressure and saturation (or saturations), and that mixed finite element methods can be accurately exploited to solve the pressure equation. Extensive numerical results are presented to see the performance of the mixed methods for the flow equations using different mixed finite elements. 1. Introduction Multiphase flow of fluids in porous media is physically and chemically complex. It involves heterogeneities in the porous media at many different length scales and complicated processes such as diffusion and dispersion. Numerical simulation of these phenomena is a critical step in understanding multicom...
Zhangxin Chen; Richard E. Ewing
Modeling of interfaces in two-dimensional problems using solid finite elements with high aspect ratio
The use of standard solid finite elements with a very high aspect ratio is proposed to model the behavior of thin interface regions between distinct components of composite structural members. It is shown that these elements present the same kinematics ... Keywords: Bond-slip, Damage model, Finite elements, Interface model, Reinforced concrete, Strong discontinuity
O. L. Manzoli; A. L. Gamino; E. A. Rodrigues; G. K. S. Claro
Introduction to Finite Element Modeling Engineering analysis of mechanical systems have been addressed by deriving differential
such as equilibrium, conservation of energy, conservation of mass, the laws of thermodynamics, Maxwell's equations the fundamental ideas of the FEM ┬Ę Know the behavior and usage of each type of elements covered in this course of the FEM (don't misuse the FEM - a numerical tool) Finite Element Analysis A typical finite element
Lin, Liwei
Nonlinear geometrically adaptive finite element model of the coilbox
Hot bar heat loss in the transfer table, the rolling stage between rougher stands and finishing stands in a hot mill, is of major concern for reasons for energy consumption, metallurgical uniformity, and rollability. A mathematical model, as well as the corresponding numerical solution, is presented for the evolution of temperature in a coiling and uncoiling bar in hot mills in the form of a parabolic partial differential equation for a shape-changing domain. The space discretization is achieved via a computationally efficient geometrically adaptive finite element scheme that accommodates the change in shape of the domain, using a computationally novel treatment of the resulting thermal contact problem due to coiling. Time is discretized according to a Crank-Nicolson scheme. Finally, some numerical results are presented.
Troyani, N. [Univ. de Oriente, Puerto La Cruz (Venezuela). Dept. de Mecanica
The Bulk Tritium Shipping Package was designed by Savannah River National Laboratory. This package will be used to transport tritium. As part of the requirements for certification, the package must be shown to meet the scenarios of the Hypothetical Accident Conditions (HAC) defined in Code of Federal Regulations Title 10 Part 71 (10CFR71). The conditions include a sequential 30-foot drop event, 30-foot dynamic crush event, and a 40-inch puncture event. Finite Element analyses were performed to support and expand upon prototype testing. Cases similar to the tests were evaluated. Additional temperatures and orientations were also examined to determine their impact on the results. The peak stress on the package was shown to be acceptable. In addition, the strain on the outer drum as well as the inner containment boundary was shown to be acceptable. In conjunction with the prototype tests, the package was shown to meet its confinement requirements.
Jordan, J.
The Uranium Processing Facility Finite Element Meshing Discussion
Energy.gov (U.S. Department of Energy (DOE)) Indexed Site
Uranium Processing Facility (UPF) Uranium Processing Facility (UPF) Finite Element Meshing Discussion ...Need picture of Building... October 25, 2011 Department of Energy - Natural Phenomenon Hazard Workshop 1 Loring Wyllie Arne Halterman Degenkolb Engineers, San Francisco Purpose of Presentation * Design vs. Analysis * Discuss the mesh criteria * Discuss the evolution of the mesh of the UPF main building model * Discuss how the mesh affects the analysis process October 25, 2011 2 Department of Energy - Natural Phenomenon Hazard Workshop FEM Modeling * GTStrudl typically used for DOE projects. * Mesh size is important * What is to be captured? * How complex is the system? * Current criteria set to capture in-plane and out-of-plane response. October 25, 2011 3
Calculation of gas hydrate dissociation with finite-element model
In situ gas hydrates have been found abundantly in the Arctic regions of the US, Canada, and Russia. Gas recovery from such a hydrate reservoir under permafrost conditions is described in the present paper. The technique is based upon a finite-element transient heat-conduction model that includes the ability to handle phase change. That model is applied to field data available from the North Slope of Alaska for predicting natural-gas production. Parametric studies have also been conducted to explore the effects of hydrate zone thickness, wellbore temperature, wellbore radius, porosity, etc., on the gas production rate. Comparisons of temperature distributions throughout the medium, and the propagation of the moving dissociation front with respect to time predicted by the present scheme and a finite-difference scheme, show good agreement. The data generated in the present study may be useful in deciding on the most optimal technique for gas recovery from hydrates. Additionally, it may provide drilling engineers with valuable information to establish guidelines for safe drilling in the presence of hydrates.
Das, D.K.; Srivastava, V. (Univ. of Alaska, Fairbanks, AK (United States). Mechanical Engineering Dept.)
Constitutive model effects on finite element modeling of elastomer behavior in radial interference seal configurations
Elastomers are becoming more prevalent in everyday products, and it is very important to be able to describe their behavior. Particularly, with advancements in computer hardware and software, the use of finite element analysis in design and analysis is becoming more prevalent. However, there is no accepted and agreed upon method to generally describe elastomer behavior in the finite element codes. Evaluation of two existing material models found in most FEA packages was conducted using experimental data gathered and fit to each model's strain energy function. The effects of using various combinations of material model and experimental data have been studied. The modeling started with simple stress states and progressed to some more general in nature. The two strain energy fimctions used were the Mooney-Rivlin and a 5 term expansion of the Rivlin series called the Polynomial (N=2) function.
Jackson, Jason R.
Rossby Wave Frequencies and Group Velocities for Finite Element and Finite Difference Approximations to the Vorticity-Divergence and the Primitive Forms of the Shallow Water Equations
In this paper Rossby wave frequencies and group velocities are analyzed for various finite element and finite difference approximations to the vorticity-divergence form of the shallow water equations. Also included are finite difference solutions ...
Beny Neta; R. T. Williams
An h-Adaptive Finite-Element Technique for Constructing 3D Wind Fields
An h-adaptive, mass-consistent finite-element model (FEM) has been developed for constructing 3D wind fields over irregular terrain utilizing sparse meteorological tower data. The element size in the computational domain is dynamically controlled ...
Darrell W. Pepper; Xiuling Wang
Method for Detecting an Element
Using gamma ray spectrum analysis, this patented invention detects a desired element from a very small sample and by compares it to a small sample of ...
FEHMN 1.0: Finite element heat and mass transfer code; Revision 1
A computer code is described which can simulate non-isothermal multi-phase multicomponent flow in porous media. It is applicable to natural-state studies of geothermal systems and groundwater flow. The equations of heat and mass transfer for multiphase flow in porous and permeable media are solved sing the finite element method. The permeability and porosity of the medium are allowed to depend on pressure and temperature. The code also has provisions for movable air and water phases and noncoupled tracers; that is, tracer solutions that do not affect the heat and mass transfer solutions. The tracers can be passive or reactive. The code can simulate two-dimensional, two-dimensional radial, or three-dimensional geometries. A summary of the equations in the model and the numerical solution procedure are provided in this report. A user`s guide and sample problems are also included. The FEHMN (Finite Element Heat and Mass Nuclear) code, described in this report, is a version of FEHM (Finite Element Heat and Mass, Zyvoloski et al., 1988) developed for the Yucca Mountain Site Characterization Project (YMP). The main use of FEHMN will be to assist in the understanding of flow fields in the saturated zone below the potential Yucca Mountain repository.
Finite element implementation of nearly-incompressible rheological models based on multiplicative decompositions
The present work is concerned with the numerical integration of finite viscoelastic or viscoplastic models. A numerical integration scheme based on the definition of a flow direction and a flow amplitude as in elastoplasticity is proposed. The most original ... Keywords: Finite elements, Finite strain, Integration scheme, Viscoelasticity, Viscoplasticity
S. Lejeunes; A. Boukamel; S. Mķo
Nano-Optical Device Design with the Use of Open-Source Parallel Version FDTD and Commercial Finite Element Package
In this paper, the implementation of open-source parallel-version FDTD (Finite-Difference-Time-Domain) software, MEEP, on Texas A&M supercomputers and commercial finite element package, COMSOL, on a single workstation for the design design of nano-optical device is reported. The the computer architecture and performance of both numerical methods on the same design will be briefly described.
Liu, Y
Solar Electric Generating System II finite element analysis
On June 2, 1992, Landers` earthquake struck the Solar Electric Generating System II, located in Daggett, California. The 30 megawatt power station, operated by the Daggett Leasing Corporation (DLC), suffered substantial damage due to structural failures in the solar farm. These failures consisted of the separation of sliding joints supporting a distribution of parabolic glass mirrors. At separation, the mirrors fell to the ground and broke. It was the desire of the DLC and the Solar Thermal Design Assistance Center (STDAC) of Sandia National Laboratories (SNL) and to redesign these joints so that, in the event of future quakes, costly breakage will be avoided. To accomplish this task, drawings of collector components were developed by the STDAC, from which a detailed finite element computer model of a solar collector was produced. This nonlinear dynamic model, which consisted of over 8,560 degrees of freedom, underwent model reduction to form a low order nonlinear dynamic model containing only 40 degrees of freedom. This model was then used as a design tool to estimate joint dynamics. Using this design tool, joint configurations were modified, and an acceptable joint redesign determined. The results of this analysis showed that the implementation of metal stops welded to support shafts for the purpose of preventing joint separation is a suitable joint redesign. Moreover, it was found that, for quakes of Landers` magnitude, mirror breakage due to enhanced vibration in the trough assembly is unlikely.
Dohner, J.L.; Anderson, J.R.
A finite element simulation of biological conversion processes in landfills
Landfills are the most common way of waste disposal worldwide. Biological processes convert the organic material into an environmentally harmful landfill gas, which has an impact on the greenhouse effect. After the depositing of waste has been stopped, current conversion processes continue and emissions last for several decades and even up to 100 years and longer. A good prediction of these processes is of high importance for landfill operators as well as for authorities, but suitable models for a realistic description of landfill processes are rather poor. In order to take the strong coupled conversion processes into account, a constitutive three-dimensional model based on the multiphase Theory of Porous Media (TPM) has been developed at the University of Duisburg-Essen. The theoretical formulations are implemented in the finite element code FEAP. With the presented calculation concept we are able to simulate the coupled processes that occur in an actual landfill. The model's theoretical background and the results of the simulations as well as the meantime successfully performed simulation of a real landfill body will be shown in the following.
Robeck, M., E-mail: firstname.lastname@example.com [Department of Water and Waste Management, Building Sciences, University of Duisburg-Essen, Universitaetsstrasse 15, 45141 Essen (Germany); Ricken, T. [Institute of Mechanics/Computational Mechanics, Building Sciences, University of Duisburg-Essen, Universitaetsstrasse 15, 45141 Essen (Germany); Widmann, R. [Department of Water and Waste Management, Building Sciences, University of Duisburg-Essen, Universitaetsstrasse 15, 45141 Essen (Germany)
FEMA: a Finite Element Model of Material Transport through Aquifers
This report documents the construction, verification, and demonstration of a Finite Element Model of Material Transport through Aquifers (FEMA). The particular features of FEMA are its versatility and flexibility to deal with as many real-world problems as possible. Mechanisms included in FEMA are: carrier fluid advection, hydrodynamic dispersion and molecular diffusion, radioactive decay, sorption, source/sinks, and degradation due to biological, chemical as well as physical processes. Three optional sorption models are embodied in FEMA. These are linear isotherm and Freundlich and Langmuir nonlinear isotherms. Point as well as distributed source/sinks are included to represent artificial injection/withdrawals and natural infiltration of precipitation. All source/sinks can be transient or steady state. Prescribed concentration on the Dirichlet boundary, given gradient on the Neumann boundary segment, and flux at each Cauchy boundary segment can vary independently of each other. The aquifer may consist of as many formations as desired. Either completely confined or completely unconfined or partially confined and partially unconfined aquifers can be dealt with effectively. FEMA also includes transient leakage to or from the aquifer of interest through confining beds from or to aquifers lying below and/or above.
High dimensional model representation based formulations for fuzzy finite element analysis of structures
This paper presents a practical approach based on high dimensional model representation (HDMR) for analyzing the response of structures with fuzzy parameters. The proposed methodology involves integrated finite element modeling, HDMR based response surface ... Keywords: Explicit formulation, Finite element, Fuzzy analysis, High dimensional model representation, Implicit formulation, Response surface
A. S. Balu; B. N. Rao
Measurement and finite element analysis of temperature distribution in arc welding process
This presentation describes both the experimental measurement and finite element analysis used to study the temperature distribution during a metal inert gas (MIG) welding process, including the cooling down period. Welding was carried out on ... Keywords: FEA, MIG welding, arc welding, cracking, finite element analysis, metal inert gas welding, residual stress, simulation, temperature distribution, weldment temperature
C. K. Lee; J. Candy; C. P. H. Tan
A finite element approach for multiphase fluid flow in porous media
The main scope of this work is to carry out a mathematical framework and its corresponding finite element (FE) discretization for the partially saturated soil consolidation modelling in presence of an immiscible pollutant. A multiphase system with the ... Keywords: Consolidation, Finite elements, Immiscible pollutants, Mixture theory, Multiphase porous media
Javier L. Mroginski; H.Ariel Di Rado; Pablo A. Beneyto; Armando M. Awruch
Time domain 3D finite element modelling of train-induced vibration at high speed
The purpose of this paper is to investigate a 3D finite element (FE) coupled train-track model for the numerical modelling of the ground induced vibration due to the passage of a single high speed train locomotive. The track components such as the sleepers, ... Keywords: Finite elements, Ground vibration, High-speed, Mach cone, Railways
A. El Kacimi; P. K. Woodward; O. Laghrouche; G. Medero
Asynchronous Communication Schemes for Finite Difference Methods on Multiple GPUs
Finite difference methods continue to provide an important and parallelisable approach to many numerical simulations problems. Iterative multigrid and multilevel algorithms can converge faster than ordinary finite difference methods but can be more difficult ... Keywords: finite-difference, GPU, multiple device, CUDA
Daniel Peter Playne; Kenneth Arthur Hawick
Variable order spherical harmonic expansion scheme for the radiative transport equation using finite elements
Highlights: {yields} We developed a variable order global basis scheme to solve light transport in 3D. {yields} Based on finite elements, the method can be applied to a wide class of geometries. {yields} It is computationally cheap when compared to the fixed order scheme. {yields} Comparisons with local basis method and other models demonstrate its accuracy. {yields} Addresses problems encountered n modeling of light transport in human brain. - Abstract: We propose the P{sub N} approximation based on a finite element framework for solving the radiative transport equation with optical tomography as the primary application area. The key idea is to employ a variable order spherical harmonic expansion for angular discretization based on the proximity to the source and the local scattering coefficient. The proposed scheme is shown to be computationally efficient compared to employing homogeneously high orders of expansion everywhere in the domain. In addition the numerical method is shown to accurately describe the void regions encountered in the forward modeling of real-life specimens such as infant brains. The accuracy of the method is demonstrated over three model problems where the P{sub N} approximation is compared against Monte Carlo simulations and other state-of-the-art methods.
Surya Mohan, P., E-mail: email@example.com [Department of Computer Science, University College London, Gower Street, London WC1E 6BT (United Kingdom); Tarvainen, Tanja, E-mail: firstname.lastname@example.com [Department of Computer Science, University College London, Gower Street, London WC1E 6BT (United Kingdom); Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio (Finland); Schweiger, Martin, E-mail: email@example.com [Department of Computer Science, University College London, Gower Street, London WC1E 6BT (United Kingdom); Pulkkinen, Aki, E-mail: email@example.com [Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio (Finland); Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, 2075 Bayview Ave., Toronto, M4N 3M5 (Canada); Arridge, Simon R., E-mail: firstname.lastname@example.com [Department of Computer Science, University College London, Gower Street, London WC1E 6BT (United Kingdom)
A CAE-integrated distributed collaborative design system for finite element analysis of complex product based on SOOA
Large-scale finite element analysis of complex product needs a wider support from external CAE resources. This paper proposes a method of the distributed concurrent and collaborative design in the distributed intelligent resources environment to use ... Keywords: Collaborative design, Distributed CAE resources, Service object-oriented architecture (SOOA)
Jiaqing Yu; Jianzhong Cha; Yiping Lu; Wensheng Xu; M. Sobolewski
Effect of geometric shape on two-dimensional finite elements
Three quadrilateral elements are defined. These are an eight-nodal-point serendipity element (QUAD8s), a nine-nodal-point serendipity element (QUAD9s), and a nine-nodal-point quadrilateral element composed of two six-nodal-point triangular elements (QUAD9t). The effect that the geometric shape of the element has on the approximation function of each element is discussed. Two beam problems demonstrate that when the shape of the elements becomes skewed, the QUAD9t element significantly improves the calculated results. Finally, a recommendation is made for the QUAD8s and QUAD9t to be used together for the most efficient and accurate results.
Cook, W.A.
Finite Element Modelling and Molecular Dynamic Simulations of Carbon nanotubes/ Polymer Composites
Modeling of single-walled carbon nanotubes, multi-walled nanotubes and nanotube reinforced polymer composites using both the Finite Element method and the Molecular Dynamic simulation technique is presented. Nanotubes subjected to mechanical loading have been analyzed. Elastic moduli and thermal coefficient of expansion are calculated and their variation with diameter and length is investigated. In particular, the nanotubes are modeled using 3D elastic beam finite elements with six degrees of freedom at each node. The difficulty in modeling multi walled nanotubes is the van der Waal's forces between adjacent layers which are geometrically non linear in nature. These forces are modeled using truss elements. The nanotube-polymer interface in a nano-composite is modeled on a similar basis. While performing the molecular dynamic simulations, the geometric optimization is performed initially to obtain the minimized configuration and then the desired temperature is attained by rescaling the velocities of carbon atoms in the nanotube. Results show that the Young's modulus increases with tube diameter in molecular mechanics whereas decreases in molecular dynamics since the inter-atomic potential due to chemical reactions between the atoms is taken into consideration in molecular dynamics unlike in molecular mechanics.
Gaddamanugu, Dhatri
Computer Based Training: Engineering Technical Training Modules - Finite Element Analysis v1.0
Finite Element Analysis ETTM, Version 1.0 is a computer45based training module that allows users to access training when desired and review it at their own pace. This module provides information about the basics of finite element analysis and modeling. This training should be used for position specific and/or continuing training for individuals involved with finite element analysis. This computer-based training (CBT) module is intended for use by new engineers as well as engineers changing jobs where bas...
An Investigation of Deformation and Fluid Flow at Subduction Zones Using Newly Developed Instrumentation and Finite Element Modeling
by offshore hydrologic instrumentation monitoring in thewith continuous GPS instrumentation and seismic networks [Using Newly Developed Instrumentation and Finite Element
LaBonte, Alison L
An investigation of deformation and fluid flow at subduction zones using newly developed instrumentation and finite element modeling
LaBonte, Alison Louise
Finite element modelling of the neck-stem interface of a modular hip implant for micro-motion study
A three dimensional, non-linear finite element modelling was used to analyse component stresses and relative micromotion at the modular junction interface of a Ti-alloy modular hip implant, using ANSYS finite element software. The model was developed ... Keywords: biomechanical modelling, finite element modelling, fretting, micromotion, modular hip stem
Kassim A. Abdullah
Hexahedral finite element mesh coarsening using pillowing technique
A techniques for coarsening a hexahedral mesh is described. The technique includes identifying a coarsening region within a hexahedral mesh to be coarsened. A boundary sheet of hexahedral elements is inserted into the hexahedral mesh around the coarsening region. A column of hexahedral elements is identified within the boundary sheet. The column of hexahedral elements is collapsed to create an extraction sheet of hexahedral elements contained within the coarsening region. Then, the extraction sheet of hexahedral elements is extracted to coarsen the hexahedral mesh.
Staten, Matthew L. (Pittsburgh, PA); Woodbury, Adam C. (Provo, UT); Benzley, Steven E. (Provo, UT); Shepherd, Jason F. (Edgewood, NM)
A Finite Element-Multibody Dynamics Co-simulation Methodology Applied to FAST
A co-simulation methodology is explored whereby a finite element code and a multi-body dynamics code featuring flexible cantilevered beams can be coupled and interactively executed. The floating frame of reference formulation is used to develop the equations of motion. The floating frame is fixed at the blade root. Such a formulation results in ordinary differential equations without added algebraic constraints. A variety of loose coupling and tight coupling schemes are examined for this problem. To synchronize the coupling variables, a Gauss-Seidel type iterative algorithm is used. The resulting fixed-point iterations are accelerated using AitkenÆs adaptive relaxation technique. The methodology is evaluated for FAST, a wind turbine aeroelastic simulation code developed by NREL. As with FAST, many multi-body codes which can model flexibility employ modal methods. A proposed addition for FAST to simulate flexible effects using a finite element method module offers a potential to include a variety of non-linearities and also provides possibilities for using a high-fidelity aerodynamics module. The coupling schemes are compared and their applicability and limitations for different scenarios are pointed out. Results validating the approach are provided.
Suryakumar, Vishvas Samuel
Quadratic Galerkin Finite Element Schemes for the Vertical Discretization of Numerical Forecast Models
A finite element scheme with second-order basis functions is introduced for vertical discretization using a spectral model for horizontal discretization. The basis functions are required to be continuous, and no assumption is made concerning the ...
J. Steppeler
Finite Element Simulation of Residual Stresses in Thermo-coupled Wire Drawing Process
The objective of this paper is to calculate residual stress in drawn wire taking into account induced temperature due to plastic dissipation energy. Finite element analysis (FEA) for the simulation of wire drawing is applied. The general purpose FEA ...
R. Iankov; A. Van Bael; P. Van Houtte
TEA - a linear frequency domain finite element model for tidal embayment analysis
A frequency domain (harmonic) finite element model is developed for the numerical prediction of depth average circulation within small embayments. Such embayments are often characterized by irregular boundaries and bottom ...
Evaluation of the matrix exponential function using finite elements in time
The evaluation of a matrix exponential function is a classic problem of computational linear algebra. Many different methods have been employed for its numerical evaluation [Moler C and van Loan C 1978 SIAM Review 20 4], none of which produce a definitive algorithm which is broadly applicable and sufficiently accurate, as well as being reasonably fast. Herein, we employ a method which evaulates a matrix exponential as the solution to a first-order initial value problem in a fictitious time variable. The new aspect of the present implementation of this method is to use finite elements in the fictitious time variable. [Weatherford C A, Red E, and Wynn A 2002 Journal of Molecular Structure 592 47] Then using an expansion in a properly chosen time basis, we are able to make accurate calculations of the exponential of any given matrix as the solution to a set of simultaneous equations.
Gebremedhin, D H; Zhang, X; Wynn, A; Tanaka, G
D H Gebremedhin; C A Weatherford; X Zhang; A Wynn III; G Tanaka
Spectral analysis method for detecting an element
A method for detecting an element is described and which includes the steps of providing a gamma-ray spectrum which has a region of interest which corresponds with a small amount of an element to be detected; providing nonparametric assumptions about a shape of the gamma-ray spectrum in the region of interest, and which would indicate the presence of the element to be detected; and applying a statistical test to the shape of the gamma-ray spectrum based upon the nonparametric assumptions to detect the small amount of the element to be detected.
Blackwood, Larry G [Idaho Falls, ID; Edwards, Andrew J [Idaho Falls, ID; Jewell, James K [Idaho Falls, ID; Reber, Edward L [Idaho Falls, ID; Seabury, Edward H [Idaho Falls, ID
Structural Mechanics & Solid Mechanics A finite element toolbox to MATLAB
Structural Mechanics & Solid Mechanics Department of Mechanics and Materials CALFEM A finite.3 Copyright ┬® 1999 by Structural Mechanics, LTH, Sweden. Printed by JABE Offset, Lund, Sweden. ISRN LUTVDG/TVSM--99/9001--SE (1-265) ISSN 0281-6679 Department of Mechanics and Materials Structural Mechanics #12;The
Ehrhardt, Matthias
Pamgen, a library for parallel generation of simple finite element meshes.
Generating finite-element meshes is a serious bottleneck for large parallel simulations. When mesh generation is limited to serial machines and element counts approach a billion, this bottleneck becomes a roadblock. Pamgen is a parallel mesh generation library that allows on-the-fly scalable generation of hexahedral and quadrilateral finite element meshes for several simple geometries. It has been used to generate more that 1.1 billion elements on 17,576 processors. Pamgen generates an unstructured finite element mesh on each processor at the start of a simulation. The mesh is specified by commands passed to the library as a 'C'-programming language string. The resulting mesh geometry, topology, and communication information can then be queried through an API. pamgen allows specification of boundary condition application regions using sidesets (element faces) and nodesets (collections of nodes). It supports several simple geometry types. It has multiple alternatives for mesh grading. It has several alternatives for the initial domain decomposition. Pamgen makes it easy to change details of the finite element mesh and is very useful for performance studies and scoping calculations.
Foucar, James G.; Drake, Richard Roy; Hensinger, David M.; Gardiner, Thomas Anthony
Finite element variational formulation for beams with discontinuities
This paper presents a variational formulation of the mechanical behaviour of beams with strong discontinuities, enhanced to simulate the strain localization process. The considered strain localization zones represent the formation of dislocations and ... Keywords: Bending elements, Dislocations, Embedded discontinuities, Hinge development, Strain localization
G. Juarez; A. G. Ayala
Finite element analysis of the Arquin-designed CMU wall under a dynamic (blast) load.
The Arquin Corporation designed a CMU (concrete masonry unit) wall construction and reinforcement technique that includes steel wire and polymer spacers that is intended to facilitate a faster and stronger wall construction. Since the construction method for an Arquin-designed wall is different from current wall construction practices, finite element computer analyses were performed to estimate the ability of the wall to withstand a hypothetical dynamic load, similar to that of a blast from a nearby explosion. The response of the Arquin wall was compared to the response of an idealized standard masonry wall exposed to the same dynamic load. Results from the simulations show that the Arquin wall deformed less than the idealized standard wall under such loading conditions. As part of a different effort, Sandia National Laboratories also looked at the relative static response of the Arquin wall, results that are summarized in a separate SAND Report.
Lopez, Carlos; Petti, Jason P.
Stochastic Finite Element Analysis for Multiphase Flow in Heterogeneous Porous Media
. This study is concerned with developing a two-dimensional multiphase model that simulates the movement of NAPL in heterogeneous aquifers. Heterogeneity is dealt with in a probabilistic sense by modeling the intrinsic permeability of the porous medium as a stochastic process. The deterministic finite element method is used to spatially discretize the multiphase flow equations. The intrinsic permeability is represented in the model via its Karhunen-Loeve expansion (Ghanem and Spanos, 1991). This is a computationally expedient representation of stochastic processes by means of a discrete set of random variables. Further, the nodal unknowns, water phase saturations and water phase pressures, are represented by their stochastic spectral expansions. This representation involves an orthogonal basis in the space of random variables. The basis consists of orthogonal polynomial chaoses of consecutive orders. The relative permeabilities of water and oil phases, and the capillary pressure are ex...
R. Ghanem; S. Dham
Materials Reliability Program: Welding Residual Stress Dissimilar Metal Butt-Weld Finite Element Modeling Handbook (MRP-317)
The residual stresses imparted by the welding process are a principal factor in the process of primary water stress corrosion cracking (PWSCC) of Alloy 82/182 nickel-alloy (i.e., dissimilar metal) piping butt welds in pressurized water reactors (PWRs). Numerical methods by finite element analyses are frequently used to simulate the welding process in order to predict the residual stress distribution in the weld and base material as an input to crack growth calculations. The crack growth calculations, in ...
COYOTE : a finite element computer program for nonlinear heat conduction problems. Part I, theoretical background.
The need for the engineering analysis of systems in which the transport of thermal energy occurs primarily through a conduction process is a common situation. For all but the simplest geometries and boundary conditions, analytic solutions to heat conduction problems are unavailable, thus forcing the analyst to call upon some type of approximate numerical procedure. A wide variety of numerical packages currently exist for such applications, ranging in sophistication from the large, general purpose, commercial codes, such as COMSOL, COSMOSWorks, ABAQUS and TSS to codes written by individuals for specific problem applications. The original purpose for developing the finite element code described here, COYOTE, was to bridge the gap between the complex commercial codes and the more simplistic, individual application programs. COYOTE was designed to treat most of the standard conduction problems of interest with a user-oriented input structure and format that was easily learned and remembered. Because of its architecture, the code has also proved useful for research in numerical algorithms and development of thermal analysis capabilities. This general philosophy has been retained in the current version of the program, COYOTE, Version 5.0, though the capabilities of the code have been significantly expanded. A major change in the code is its availability on parallel computer architectures and the increase in problem complexity and size that this implies. The present document describes the theoretical and numerical background for the COYOTE program. This volume is intended as a background document for the user's manual. Potential users of COYOTE are encouraged to become familiar with the present report and the simple example analyses reported in before using the program. The theoretical and numerical background for the finite element computer program, COYOTE, is presented in detail. COYOTE is designed for the multi-dimensional analysis of nonlinear heat conduction problems. A general description of the boundary value problems treated by the program is presented. The finite element formulation and the associated numerical methods used in COYOTE are also outlined. Instructions for use of the code are documented in SAND2010-0714.
Glass, Micheal W.; Hogan, Roy E., Jr.; Gartling, David K.
Ultrascalable Implicit Finite Element Analyses in Solid Mechanics with over a Half a Billion Degrees of Freedom
We present a highly parallel finite element program, Olympus, equipped with an ultrascalable linear solver, Prometheus, applied to micro-FE bone modeling calculations on an IBM SP Power3. Scalability is demonstrated with scaled speedup studies of a non-linear analyses of a vertebral body with over a half of a billion degrees of freedom. We show parallel scalability with up to 4088 processors on the ACSI White machine. This work is significant in that, in the domain of unstructured implicit finite element analysis in solid mechanics with complex geometry, this is the first demonstration of a highly parallel, and e#cient, application of a mathematically optimal linear solution method---smoothed aggregation algebraic multigrid.
Mark F. Adams; Harun H. Bayraktar; Tony M. Keaveny; Panayiotis Papadopoulos
Adjacency-based data reordering algorithm for acceleration of finite element computations
Effective use of the processor memory hierarchy is an important issue in high performance computing. In this work, a part level mesh topological traversal algorithm is used to define a reordering of both mesh vertices and regions that increases the spatial ... Keywords: Data reordering, cache penalty model, finite element analysis, unstructured mesh
Min Zhou; Onkar Sahni; Mark S. Shephard; Christopher D. Carothers; Kenneth E. Jansen
Unstructured mesh partition improvement for implicit finite element at extreme scale
Parallel simulations at extreme scale require that the mesh is distributed across a large number of processors with equal work load and minimum inter-part communications. A number of algorithms have been developed to meet these goals and graph/hypergraph-based ... Keywords: Extreme scale, Finite element, Partition improvement, Unstructured mesh
Min Zhou; Onkar Sahni; Ting Xie; Mark S. Shephard; Kenneth E. Jansen
The Finite Element Analysis of Quartz Crystal Resonators with Nonlinear Plate Equations
in predicting the vibration frequency, energy trapping, and calculation of device properties. The analysis can. The full advantage of the finite element analysis can be taken if electrical parameters and performance-4], further analysis on important phenomena and electrical circuit parameters require the consideration
Wang, Ji
Modeling with finite element the convective heat transfer in civil building EPS insulated walls
In this paper we present the analysis of convective heat transfer in the walls of a house insulated with polystyrene. In the first part we make an evaluation of the insulation that is currently used in the houses. We start the simulation using a real ... Keywords: convective heat transfer, dew-point, finite element, polystyrene insulation
Madalina Xenia Calbureanu; Mihai Lungu; Dragos Tutunea; Raluca Malciu; Alexandru Dima
Variational Data Assimilation with a Variable Resolution Finite-Element shallow-water Equations Model
The adjoint model of a finite-element shallow-water equations model was obtained with a view to calculate the gradient of a cost functional in the framework of using this model to carry out variational data assimilation (VDA) experiments using ...
Keyun Zhu; I. Michael Navon; Xiaolei Zou
FES99: A Global Tide Finite Element Solution Assimilating Tide Gauge and Altimetric Information
An improved version of the global hydrodynamic tide solutions [finite element solutions (FESs) FES94, FES95.2.1, and FES98] has been developed, implemented, and validated. The new model is based on the resolution of the tidal barotropic equations ...
F. LefĶvre; F. H. Lyard; C. Le Provost; E. J. O. Schrama
Finite Element Analysis of a Composite Semi-Span Test Article With and Without Discrete Damage
AS&M, Inc. performed finite element analysis, with and without discrete damage, of a composite semi-span test article that represents the Boeing 220-passenger transport aircraft composite semi-span test article. A NASTRAN bulk data file and drawings ...
Lovejoy Andrew E.
Effects of Stochastic Ice Strength Perturbation on Arctic Finite Element Sea Ice Modeling
The ice strength parameter P* is a key parameter in dynamic/thermodynamic sea ice models that cannot be measured directly. Stochastically perturbing P* in the Finite Element Sea Ice¢Ocean Model (FESOM) of the Alfred Wegener Institute aims at ...
Stephan Juricke; Peter Lemke; Ralph Timmermann; Thomas Rackow
Weighted least-squares finite elements based on particle imaging velocimetry data
The solution of the Navier-Stokes equations requires that data about the solution is available along the boundary. In some situations, such as particle imaging velocimetry, there is additional data available along a single plane within the domain, and ... Keywords: Data assimilation, Finite element, Least-squares, Particle imaging velocimetry
J. J. Heys; T. A. Manteuffel; S. F. McCormick; M. Milano; J. Westerdale; M. Belohlavek
Three dimensional modeling and finite element simulation of a generic end mill
The geometry of cutting flutes and the surfaces of end mills is one of the crucial parameters affecting the quality of the machining in the case of end milling. These are usually represented by two-dimensional models. This paper describes in detail the ... Keywords: End mill, Finite element analysis, Mapping, Surface modeling, Surface patches
Puneet Tandon; Md. Rajik Khan
Geological formation - drill string dynamic interaction finite-element program (GEODYN). Phase 1. Theoretical description
The Theoretical Description for the GEODYN interactive finite-element computer program is presented. The program is capable of performing the analysis of the three-dimensional transient dynamic response of a Polycrystalline Diamond Compact Bit-Bit Sub arising from the intermittent contact of the bit with the downhole rock formations. The program accommodates nonlinear, time-dependent, loading and boundary conditions.
Baird, J.A.; Apostal, M.C.; Rotelli, R.L. Jr.; Tinianow, M.A.; Wormley, D.N.
Phase 1 user instruction manual. A geological formation - drill string dynamic interaction finite element program (GEODYN)
User instructions for the GEODYN Interactive Finite Element Computer Program are presented. The program is capable of performing the analysis of the three-dimensional transient dynamic response of a Polycrystalline Diamond Compact Bit - Bit Sub arising from the intermittent contact of the bit with the downhole rock formations. The program accommodates non-linear, time dependent, loading and boundary conditions.
Tinianow, M.A.; Rotelli, R.L. Jr.; Baird, J.A.
Finite element analysis of contact stress in a full-metallic pipe joint for hydrogen pipelines
Hydrogen gas has been widely recognized as an environmentally clean and renewable energy fuel, and it provides a way to reduce greenhouse gas and air pollution emission. A great deal of effort has been made to develop new techniques in the field of hydrogen ... Keywords: contact stress analyses, finite element model (FEM), hydrogen pipelines, metallic gasket, pipe joint
Nan Bu; Naohiro Ueno; Osamu Fukuda
Performance of a parallel algebraic multilevel preconditioner for stabilized finite element semiconductor device modeling
In this study results are presented for the large-scale parallel performance of an algebraic multilevel preconditioner for solution of the drift-diffusion model for semiconductor devices. The preconditioner is the key numerical procedure determining ... Keywords: Drift-diffusion, Finite element, Graph partitioning, Multigrid, Multilevel preconditioners, Newton-Krylov, Nonsmoothed aggregation, Schwarz domain decomposition, Semiconductor devices
Paul T. Lin; John N. Shadid; Marzio Sala; Raymond S. Tuminaro; Gary L. Hennigan; Robert J. Hoekstra
Finite element modeling of a vibrating touch screen actuated by piezo patches for haptic feedback
The aim of our work is to design a touch screen for displaying vibrotactile haptic feedback to the user via piezo patches attached to its surface. One of the challenges in the design is the selection of appropriate boundary conditions and the piezo configurations ... Keywords: finite element modeling, piezo patch actuators, touch screen, vibrotactile haptic feedback
Buket Baylan; Ugur Aridogan; Cagatay Basdogan
Design Optimization of Anchor Support System in Large Scale Underground Engineering Based on Finite Element Analysis
The anchor support design is a major content for the design of underground engineering. Proper intensity of anchor support measures helps to guarantee the surrounding rock stability and meanwhile reduce costs. A computational algorithm is proposed to ... Keywords: design optimization, anchor support, finite element analysis, underground cavern
Yuting Zhang; Ming Xiao
Heat Transport in Groundwater Systems--Finite Element Model
Solar energy is a promising alternate energy source for space heating. A method of economic long term solar energy storage is needed. Researchers have proposed storing solar energy by injecting hot water heated using solar collectors into groundwater aquifers for long term energy storage. Analytical solutions are available that predict water temperatures as hot water is injected into a groundwater aquifer, but little field and laboratory data are available to verify these models. The objectives of this study were to construct a laboratory model to simulate hot water injection into a confined aquifer, to use data from the model to verify analytical solutions modeling this process, and to evaluate the effects of physical properties and design parameters on thermal recovery efficiency. Initial studies of hot water injection into underground reservoirs were done by the petroleum industry while studying secondary and tertiary oil recovery methods. These studies involved small laboratory models. Advances in computer technology made it possible to model these systems numerically. Many assumptions must be made to predict temperature distributions and thermal efficiencies using analytical models which are not required in numerical solutions. To simulate hot water injection into a confined aquifer, a laboratory model (a 1.8288 m deep, 0.2 radian sector tank, that was 7.01 m in the radial direction) was constructed. There were 39 temperature and 15 fluid pressure measuring locations through the model. Water was supplied to the model at a constant temperature and flow rate. The flow layer was composed of a fine grained Texblast blasting sand. Four runs were made. During the initial run, no heat transfer took place and the hydraulic conductivity was measured. Three runs were made where the heat transfer was monitored. Water level data from the heat transfer runs showed that as the temperature of the aquifer increased, the hydraulic conductivity increased. Temperature data indicated that the three radii closest to the well bore reached thermal equilibrium. The equilibrium temperature decreased as radius increased. From Run 1 to Run 2, the equilibrium temperature increased at each radius because a larger flow rate was used. A vertical thermal gradient existed in the flow layer with the less dense warm water floating out over the cooler more dense water initially in the model. During the pumping cycle, the temperatures gradually decreased. The temperature of the water as it was pumped out of the model was measured and the energy recovered was computed using the initial temperature as a reference. Various other temperatures were used as a base reference to calculate recovery efficiency. There were heat losses out the sides of the model. The assumption of angular symmetry made in all analytical solutions was therefore not met. For this reason, the analytical solutions showed adequate, but not great, agreement with the experimental temperature distributions. Using the analytical solutions, the effects of changing system design parameters were evaluated. Increasing thermal conductivity in the flow layer caused the temperature distribution to spread out but had no effect on thermal efficiency. Increasing the thermal conductivity in the confining layers caused the temperature profile to not move as far from the well, and decreased thermal efficiency. Injection rates are only indirectly related to thermal efficiency. The physical parameter having the greatest effect on thermal efficiency was the flow layer thickness. As thickness increased, thermal efficiency increased.
Grubaugh, E. K.; Reddell, D. L.
Ellipsis 3D: A particle-in-cell finite-element hybrid code for modelling mantle convection and lithospheric deformation
We have extended the two-dimensional geodynamics finite-element code ''Ellipsis'' to three-dimensions. Ellipsis uses a hybrid particle in a cell scheme, which combines a fixed mesh of computational points and a dense arrangement of mobile material points. ... Keywords: Finite-element, Lithosphere, Mantle convection, Mixed scheme, Particle-in-cell
Craig O'Neill; Louis Moresi; Dietmar M³ller; Rich Albert; Frķdķric Dufour
A finite element analysis technique for predicting as-sprayed residual stresses generated by the plasma spray coating process
It is essential to analyze the residual stresses during the deposition of plasma sprayed coatings since they adversely affect the coatings' performance during their service. In this article, finite element coupled heat transfer and elastic-plastic thermal ... Keywords: Finite element analysis, Heat transfer, Plasma spraying, Residual stresses, Thermal barrier coatings
H. W. Ng; Z. Gan
A hybrid-mixed finite element formulation for the geometrically exact analysis of three-dimensional framed structures
This paper addresses the development of a hybrid-mixed finite element formulation for the quasi-static geometrically exact analysis of three-dimensional framed structures with linear elastic behavior. The formulation is based on a modified principle ... Keywords: Complementary energy principle, Geometrically exact analysis, Hybrid-mixed finite elements, One-dimensional beam model, Three-dimensional framed structures
H. A. Santos; P. M. Pimenta; J. P. Almeida
An Object-Oriented Finite Element Framework for Multiphysics Phase Field Simulations
The phase field approach is a powerful and popular method for modeling microstructure evolution. In this work, advanced numerical tools are used to create a phase field framework that facilitates rapid model development. This framework, called MARMOT, is based on Idaho National Laboratory's finite element Multiphysics Object-Oriented Simulation Environment. In MARMOT, the system of phase field partial differential equations (PDEs) are solved simultaneously with PDEs describing additional physics, such as solid mechanics and heat conduction, using the Jacobian-Free Newton Krylov Method. An object-oriented architecture is created by taking advantage of commonalities in phase fields models to facilitate development of new models with very little written code. In addition, MARMOT provides access to mesh and time step adaptivity, reducing the cost for performing simulations with large disparities in both spatial and temporal scales. In this work, phase separation simulations are used to show the numerical performance of MARMOT. Deformation-induced grain growth and void growth simulations are included to demonstrate the muliphysics capability.
Michael R Tonks; Derek R Gaston; Paul C Millett; David Andrs; Paul Talbot
The Accuracy of a Finite-Element Vertical Discretization Scheme for Primitive Equation Models: Comparison with a Finite-Difference Scheme
The accuracy of a slightly modified version of the finite-element vertical discretization scheme first described in Staniforth and Daley is studied with respect to a set of Rossby and gravity analytical normal modes obtained as solutions of a ...
Michel Bķland; Jean C¶tķ; Andrew Staniforth
Finite element analysis of bending in a threaded connector for a 5 1/2-in. Marine riser
This paper describes the development of a new finite element modelling technique for performing nonlinear bending analysis of tubulars and its application to a threaded connector for a 5-1/2 inch production tubing marine riser. A finite element technique has been developed for analyzing bending loads applied to an axisymmetric geometry. The method uses a Fourier series solution. The first two terms of the series are solved simultaneously, allowing nonlinearities to be included since the method does not use superposition, which normally requires linearity. Existing methods of analysis require either a linear elastic assumption, and axisymmetric approximation of bending loads, or a full three dimensional analysis. The new technique includes nonlinearities in mechanical properties, gapping, and friction. It is more accurate than the method where axisymmetric loads are applied so that pipe OD stresses are the same as those that would result from bending. The model is considerably less complicated to use than a three dimensional model and is also considerably less expensive. The method described above is applied to a 5-1/2 inch threaded connector. The connector is analyzed under make-up, tension, pressure, bending, and shear loads. Predictions include average and reversing stresses in the pin and box wall and at stress concentrations. These predictions can be used to evaluate the fatigue life of the connector.
Allen, M.B.; Eichberger, L.C.
FEHMN 1.0: Finite element heat and mass transfer code
A computer code is described which can simulate non-isothermal multiphase multicomponent flow in porous media. It is applicable to natural-state studies of geothermal systems and ground-water flow. The equations of heat and mass transfer for multiphase flow in porous and permeable media are solved using the finite element method. The permeability and porosity of the medium are allowed to depend on pressure and temperature. The code also has provisions for movable air and water phases and noncoupled tracers; that is, tracer solutions that do not affect the heat and mass transfer solutions. The tracers can be passive or reactive. The code can simulate two-dimensional, two-dimensional radial, or three-dimensional geometries. A summary of the equations in the model and the numerical solution procedure are provided in this report. A user`s guide and sample problems are also included. The main use of FEHMN will be to assist in the understanding of flow fields in the saturated zone below the proposed Yucca Mountain Repository. 33 refs., 27 figs., 12 tabs.
FINITE DIFFERENCE METHODS FOR THE WIDE-ANGLE `PARABOLIC' EQUATION GEORGIOS AKRIVIS Abstract. We consider a model initial and boundary value problem for the wide-angle `parabolic' equation Lur = icu, the wide-angle `parabolic'equation of underwater acoustics. Given R > 0, ┬Ą 0, > 0, , and q real
Fluorescence photon migration by the boundary element method
The use of the boundary element method (BEM) is explored as an alternative to the finite element method (FEM) solution methodology for the elliptic equations used to model the generation and transport of fluorescent light in highly scattering media, without the need for an internal volume mesh. The method is appropriate for domains where it is reasonable to assume the fluorescent properties are regionally homogeneous, such as when using highly specific molecularly targeted fluorescent contrast agents in biological tissues. In comparison to analytical results on a homogeneous sphere, BEM predictions of complex emission fluence are shown to be more accurate and stable than those of the FEM. Emission fluence predictions made with the BEM using a 708-node mesh, with roughly double the inter-node spacing of boundary nodes as in a 6956-node FEM mesh, match experimental frequency-domain fluorescence emission measurements acquired on a 1087 cm{sup 3} breast-mimicking phantom at least as well as those of the FEM, but require only 1/8 to 1/2 the computation time.
Fedele, Francesco [Department of Civil and Environmental Engineering, University of Vermont, Burlington, VT 05405 (United States); Eppstein, Margaret J. [Department of Computer Science, University of Vermont, Burlington, VT 05405 (United States)]. E-mail: firstname.lastname@example.com; Laible, Jeffrey P. [Department of Civil and Environmental Engineering, University of Vermont, Burlington, VT 05405 (United States); Godavarty, Anuradha [Photon Migration Laboratories, Department of Chemistry, Texas A and M University, College Station, TX 77842-3012 (United States); Sevick-Muraca, Eva M. [Photon Migration Laboratories, Department of Chemistry, Texas A and M University, College Station, TX 77842-3012 (United States)
Finite element strategies for the efficient analysis and evaluation of solar collector structures
Concentrating or reflecting structures for solar energy systems must be evaluated as to their structural integrity and optical performance. Computer studies can be used as an integral part of these evaluations. The computer studies make use of finite element structural codes coupled with post-processors that calculate optical data. If the analysis of a solar structure is to be carried out in an efficient manner, these computer codes must have certain capabilities. A number of solar energy projects at Sandia National Laboratories have made extensive use of finite element analyses. The analyses have been useful in evaluating design concepts which hold promise for large scale use in solar energy projects. Analysis procedures have been developed for some structures so that evaluations can be carried out in a straightforward manner.
Koteras, J. R.
Superconvergence of finite element approximations by a computer-based approach
In this thesis we present a study of superconvergence which can be applied to practical meshes. We introduce a new definition of superconvergence which extends the classical definition to practical computations. The new definition allows us to determine points of least error for entire classes of local geometries, materials and element types. Based on the new definition we developed a methodology to study superconvergence in practical grids. This methodology is completely computer-based. We give several examples to show the application of this methodology to finite element meshes like the ones employed in engineering computations.
Gangaraj, Srihari Kumar
Development of Modeling and Simulation for Magnetic Particle Inspection Using Finite Elements
Magnetic particle inspection (MPI) is a widely used nondestructive inspection method for aerospace applications essentially limited to experiment-based approaches. The analysis of MPI characteristics that affect sensitivity and reliability contributes not only reductions in inspection design cost and time but also improvement of analysis of experimental data. Magnetic particles are easily attracted toward a high magnetic field gradient. Selection of a magnetic field source, which produces a magnetic field gradient large enough to detect a defect in a test sample or component, is an important factor in magnetic particle inspection. In this work a finite element method (FEM) has been employed for numerical calculation of the MPI simulation technique. The FEM method is known to be suitable for complicated geometries such as defects in samples. This thesis describes the research that is aimed at providing a quantitative scientific basis for magnetic particle inspection. A new FEM solver for MPI simulation has been developed in this research for not only nonlinear reversible permeability materials but also irreversible hysteresis materials that are described by the Jiles-Atherton model. The material is assumed to have isotropic ferromagnetic properties in this research (i.e., the magnetic properties of the material are identical in all directions in a single crystal). In the research, with a direct current field mode, an MPI situation has been simulated to measure the estimated volume of magnetic particles around defect sites before and after removing any external current fields. Currently, this new MPI simulation package is limited to solving problems with the single current source from either a solenoid or an axial directional current rod.
Jun-Youl Lee
Materials Science and Engineering B 117 (2005) 5361 Finite element analysis-based design of a fluid-flow control nano-valve
of a fluid-flow control nano-valve M. Grujicica,, G. Caoa, B. Pandurangana, W.N. Royb a Department A finite element method-based procedure is developed for the design of molecularly functionalized nano-size devices. The procedure is aimed at the single-walled carbon nano-tubes (SWCNTs) used in the construction
Grujicic, Mica
Finite volume methods for unidirectional dispersive wave models
We extend the framework of the finite volume method to dispersive unidirectional water wave propagation in one space dimension. In particular we consider a KdV-BBM type equation. Explicit and IMEX Runge-Kutta type methods are used for time discretizations. The fully discrete schemes are validated by direct comparisons to analytic solutions. Invariants conservation properties are also studied. Main applications include important nonlinear phenomena such as dispersive shock wave formation, solitary waves and their various interactions.
Dutykh, Denys; Mitsotakis, Dimitrios
Finite-Difference Lattice Boltzmann Methods for binary fluids
We investigate two-fluid BGK kinetic methods for binary fluids. The developed theory works for asymmetric as well as symmetric systems. For symmetric systems it recovers Sirovich's theory and is summarized in models A and B. For asymmetric systems it contributes models C, D and E which are especially useful when the total masses and/or local temperatures of the two components are greatly different. The kinetic models are discretized based on an octagonal discrete velocity model. The discrete-velocity kinetic models and the continuous ones are required to describe the same hydrodynamic equations. The combination of a discrete-velocity kinetic model and an appropriate finite-difference scheme composes a finite-difference lattice Boltzmann method. The validity of the formulated methods is verified by investigating (i) uniform relaxation processes, (ii) isothermal Couette flow, and (iii) diffusion behavior.
Aiguo Xu
Modeling brittle fracture, slip weakening, and variable friction in geomaterials with an embedded strong discontinuity finite element.
Localized shear deformation plays an important role in a number of geotechnical and geological processes. Slope failures, the formation and propagation of faults, cracking in concrete dams, and shear fractures in subsiding hydrocarbon reservoirs are examples of important effects of shear localization. Traditional engineering analyses of these phenomena, such as limit equilibrium techniques, make certain assumptions on the shape of the failure surface as well as other simplifications. While these methods may be adequate for the applications for which they were designed, it is difficult to extrapolate the results to more general scenarios. An alternative approach is to use a numerical modeling technique, such as the finite element method, to predict localization. While standard finite elements can model a wide variety of loading situations and geometries quite well, for numerical reasons they have difficulty capturing the softening and anisotropic damage that accompanies localization. By introducing an enhancement to the element in the form of a fracture surface at an arbitrary position and orientation in the element, we can regularize the solution, model the weakening response, and track the relative motion of the surfaces. To properly model the slip along these surfaces, the traction-displacement response must be properly captured. This report focuses on the development of a constitutive model appropriate to localizing geomaterials, and the embedding of this model into the enhanced finite element framework. This modeling covers two distinct phases. The first, usually brief, phase is the weakening response as the material transitions from intact continuum to a body with a cohesionless fractured surface. Once the cohesion has been eliminated, the response along the surface is completely frictional. We have focused on a rate- and state-dependent frictional model that captures stable and unstable slip along the surface. This model is embedded numerically into the element using a generalized trapezoidal formulation. While the focus is on the constitutive model of interest, the framework is also developed for a general surface response. This report summarizes the major research and development accomplishments for the LDRD project titled 'Cohesive Zone Modeling of Failure in Geomaterials: Formulation and Implementation of a Strong Discontinuity Model Incorporating the Effect of Slip Speed on Frictional Resistance'. This project supported a strategic partnership between Sandia National Laboratories and Stanford University by providing funding for the lead author, Craig Foster, during his doctoral research.
Regueiro, Richard A. (University of Colorado, Boulder, CO); Borja, R. I. (Stanford University, Stanford, CA); Foster, C. D. (Stanford University, Stanford, CA)
Adapting a Beam-Based Rotordynamics Model to Accept a General Three-Dimensional Finite-Element Casing Model
The subject of this thesis is an extension of a two-dimensional, axisymmetric, Timoshenko-beam finite-element rotordynamic code to include a three-dimensional non-axisymmetric solid-element casing model. Axisymmetric beams are sufficient to model rotors. Spring and damper forces provide the interface between the rotor and its casing and capture the dynamics of the full model. However, axisymmetric beams limit the modeling of real-case machine structures, where the casing is not axisymmetric. Axisymmetric and non-axisymmetric 3D finite element casing structures are modeled. These structures are then reduced using a technique called substructuring. Modal equations are developed for axisymmetric and non-axisymmetric casing models. In a 3D non-axisymmetric model, structural dynamics modes can be modeled by lateral modes in two orthogonal planes. Modal information of the complex 3D casing structures are generated, and then incorporated into the 2D code after a series of pre-processing steps. A reduction method called Component Mode Synthesis (CMS) is used to reduce the large dimensionality involved in calculation of rotordynamic coefficients. The results from the casing structures are merged with the rotor model to create a combined rotor-casing model. The analysis of the combined structure shows that there is a difference in the natural frequencies and unbalance response between the model that uses symmetrical casing and the one that uses non-axisymmetric casing. XLTRC2 is used as an example of a two-dimensional axisymmetric beam-element code. ANSYS is used as a code to build three-dimensional non-axisymmetric solid-element casing models. The work done in this thesis opens the scope to incorporate complex non-axisymmetric casing models with XLTRC2.
James, Stephen M.
A Spectral General Circulation Model Using a Piecewise-Constant Finite-Element Representation on a Hybrid Vertical Coordinate System
A numerical scheme for the vertical discretization of primitive equations in a generalized pressure-type coordinate is developed through application of the Galerkin formalism with piecewise-constant finite elements: this methodology affords an ...
Renķ Laprise; Claude Girard
Finite Element Analysis of Ballistic Penetration of Plain Weave Twaron CT709« Fabrics: A Parametric Study
The ballistic impact of Twaron CT709« plain weave fabrics is studied using an explicit finite element method. Many existing approximations pertaining to woven fabrics cannot adequately represent strain rate-dependent behavior exhibited by the Twaron fabrics. One-dimensional models based on linear viscoelasticity can account for rate dependency but are limited by the simplifying assumptions on the fabric architecture and stress state. In the current study, a three-dimensional fabric model is developed by treating each individual yarn as a continuum. The yarn behavior is phenomenologically described using a three-dimensional linear viscoelastic constitutive relation. A user subroutine VUMAT for ABAQUS/Explicit« is developed to incorporate the constitutive behavior. By using the newly developed viscoelasticity model, a parametric study is carried out to analyze the effects of various parameters on the impact behavior of the Twaron fabrics, which include projectile shape and mass, gripping conditions, inter-yarn friction, and the number of fabric layers. The study leads to the determination of the optimal number of fabric layers and the optimized level of inter-yarn friction that are needed to achieve the maximum energy absorption at specified impact speeds. The present study successfully utilizes the combination of 3D weave architecture and the strain rate dependent material behavior. Majority of the existing work is based either on geometry simplification or assumption of elastic material behavior. Another significant advantage with the present approach is that the mechanical constitutive relation, coded in FORTRAN«, is universal in application. The desired material behavior can be obtained by just varying the material constants in the code. This allows for the extension of this work to any fabric material which exhibits a strain-rate dependent behavior in addition to Twaron«. The results pertaining to optimal number of fabric layers and inter-yarn friction levels can aid in the manufacturing of fabric with regard to the desired level of lubrication/additives to improve the fabric performance under impact.
Gogineni, Sireesha
Departamento de Projeto MecŌ??anico (DPM), Faculdade de Engenharia MecŌ??anica (FEM), Uni┬Ł versidade Estadual de
Three-dimensional finite element modeling of a magnet array spinning above a conductor
Drag forces due to eddy currents induced by the relative motion of a conductor and a magnetic field occur in many practical devices: motors, brakes, magnetic bearings, and magnetically levitated vehicles. Recently, finite element codes have included solvers for 3-D eddy current geometries and have the potential to be very useful in the design and analysis of these devices. In this paper, numerical results from three-dimensional modeling of a magnet array spinning above a conductor are compared to experimental results in order to assess the capabilities of these codes.
Lorimer, W.L.; Lieu, D.K. [Univ. of California, Berkeley, CA (United States). Dept. of Mechanical Engineering; Hull, J.R.; Mulcahy, T.M.; Rossing, T.D. [Argonne National Lab., IL (United States)
Implementation of two geologic constitutive models in the HONDO finite-element code
Two constitutive models for use with geologic materials have been incorporated into the HONDO finite-element program. Both models have the same behavior in tension, using a stress criterion to form cracks normal to the maximum principal stress. In compression, the two models give upper and lower bound solutions to the unconfined postfailure strength. The first model uses a Coulomb criterion to form explicit shear cracks, while the second model uses an elastic-plastic formulation developed by Krieg. Two sample applications, an indentor test and fracture of a borehole, are presented.
Swenson, D.V.
A hierarchical fracture model for the iterative multiscale finite volume method
An iterative multiscale finite volume (i-MSFV) method is devised for the simulation of multiphase flow in fractured porous media in the context of a hierarchical fracture modeling framework. Motivated by the small pressure change inside highly conductive ... Keywords: Fractured porous media, Hierarchical fractured modeling, Iterative multiscale finite volume, Iterative multiscale methods, Multiscale finite volume, Multiscale fracture modeling, Multiscale methods
Hadi Hajibeygi; Dimitris Karvounis; Patrick Jenny
A finite-element approximation of a quasi-magnetostatic 3D eddy current model by fractional-step A-? scheme
We propose in this paper a fractional-step A-@j scheme for a quasi-magnetostatic 3D eddy current model by means of finite-element approximations. Bounds for continuous and discrete error in finite time are given, and it is verified that provided the ... Keywords: Eddy current problem, Error estimates, Finite-element approximation, Fractional-step A-? scheme
Changfeng Ma
A Spectral-Element Discontinuous Galerkin Lattice Boltzmann Method...
Discontinuous Galerkin Lattice Boltzmann Method for Simulating Natural Convection Heat Transfer in a Horizontal Concentric Annulus Title A Spectral-Element Discontinuous...
Abstract-Finite element stiffness and consistent mass matrices are derived for helically wound, symmetrical composite tubes. The tubular element is considered to have constant cross-section and small deformations restricted to a plane. Each node has three degrees of freedom: axial and transverse displacement and rotation (slope oftransverse displacement). Shell theory and lamination theory are used to formulate element stiffness matrices. The stiffness and mass matrices derived from the helically wound tubular composite material are reduced to symmetrically laminated composite beam. The free vibration and natural frequency are investigated for five different materials: steel, aluminum, carbon/N5280, Kevlar-49/epoxy and graphite/epoxy composites and various layup configurations. One application of a rotating flexible beam is investigated. The dynamic model of the flexible rotating beam includes the coupled effect between the rigid body motion and the flexible motion. The inverse dynamic simulation is performed by a prescribed driving torque in the numerical simulation. The influence of flexibility on rigid body motion are presented and discussed. From the numerical results, the composite material strongly possesses the lower power consumption and the passive control in damping the vibration of the structure. INTRODUcnON
C. I. Chen; V. H. Mucino; E. J. Barbero
Lagrangian finite element analysis of the penetration of earth penetrating weapons
Buried targets, such as hardened missile silos, that are resistant to the effects of air blast from above-ground or surface-burst explosions may be vulnerable to the effects of ground motion produced by nearby underground explosions. An earth penetrating weapon (EPW) is being developed to exploit this phenomena. To design the EPW system, loads on the weapon due to the penetration event must be determined. This paper presents the methodology for performing Lagrangian finite-element analysis of the penetration event in two and three dimensions. In order to describe the methodology, results from analyses done for a particular EPW impacting a particular target medium are presented. The results for impacts with nonzero angles of incidence and nonzero angles of attack show the importance of being able to calculate three dimensional penetration loads. 62 figs.
Rosinsky, R.W.
Finite volume local evolution Galerkin method for two-dimensional relativistic hydrodynamics
The paper proposes a second-order accurate finite volume local evolution Galerkin (FVLEG) method for two-dimensional special relativistic hydrodynamical (RHD) equations. Instead of using the dimensional splitting method or solving one-dimensional local ... Keywords: Evolution operator, Finite volume local evolution Galerkin method, Genuinely multi-dimensional method, Relativistic hydrodynamics
Kailiang Wu, Huazhong Tang
Point-wise hierarchical reconstruction for discontinuous Galerkin and finite volume methods for solving conservation laws
We develop a new hierarchical reconstruction (HR) method [17,28] for limiting solutions of the discontinuous Galerkin and finite volume methods up to fourth order of accuracy without local characteristic decomposition for solving hyperbolic nonlinear ... Keywords: Discontinous Galerkin method, Finite volume method, Hierarchical reconstruction, Hyperbolic conservation laws, Limiter
Zhiliang Xu; Yingjie Liu; Huijing Du; Guang Lin; Chi-Wang Shu
Spectral element method in time for rapidly actuated systems
In this paper, the spectral element (SE) method is applied in time to find the entire time-periodic or transient solution of time-dependent differential equations. The time-periodic solution is computed by enforcing periodicity of the element set. Of ... Keywords: 65D30, 65M06, 65M60, 65M70, 74H45, Aeroacoustic, Limit-cycle oscillations, Rapid excitation, Spectral element, Time periodicity, Transient response, Wave equation
Mohammad H. Kurdi; Philip S. Beran
A method is presented for joining sections of uranium rod which are clad in a corrosion-resistant material of higher melting point than uranium. The method includes the steps of preferentially- etching the uranium in the ends of the sections to be joined to depress the level of the uranium slighily below that of the cladding, bringing the ends to be joined together, applying axial pressure to the joint, and heli-arc welding the joint while rotating the joint, to fuse the cladding to a uniform depth of about 50% of the thickness of the cladding.
Noland, R.A.; Stone, C.C.
Finite element analysis of grain-matrix micro-cracking in shale within the context of a multiscale modeling
, hydrofracturing, or oil shale production. Current macro- scale and multiscale models do not account simultaneouslyFinite element analysis of grain-matrix micro-cracking in shale within the context of a multiscale-cracking in shale at grain-matrix inter- faces, assuming constituents are composed of quart silt grains
Regueiro, Richard A.
Numerical Prediction of the 10¢11 June 1985 Squall Line with the Canadian Regional Finite-Element Model
In an effort to improve operational forecasts of mesoscale convective systems (MCSs), a mesoscale version of the operational Canadian Regional Finite-Element (RFE) Model with a grid size of 25 km is used to predict an intense MCS that occurred ...
Stķphane Bķlair; Da-Lin Zhang; Jocelyn Mailhot
Two-dimensional finite element simulation of fracture and fatigue behaviours of alumina microstructures for hip prosthesis
, finite element, fatigue, fracture, ceramic, microstructure * Corresponding author. Email address: email@example.com #12;2 1. Introduction Alumina is known as a primary ceramic material in biomedical industry. Particularly, Al2O3 is widely used as the material of a femoral head and an acetabular cup of hip
Paris-Sud XI, Universit├® de
Coupled Transient Finite Element Simulation of Quench in Jefferson Lab's 11 GeV Super High Momentum Spectrometer Superconducting Magnets
This paper presents coupled transient thermal and electromagnetic finite element analysis of quench in the Q2, Q3, and dipole superconducting magnets using Vector Fields Quench code. Detailed temperature distribution within coils and aluminum force collars were computed at each time step. Both normal (quench with dump resistor) and worst-case (quench without dump resistor) scenarios were simulated to investigate the maximum temperatures. Two simulation methods were utilized, and their algorithms, implementation, advantages, and disadvantages are discussed. The first method simulated the coil using nonlinear transient thermal analysis directly linked with the transient circuit analysis. It was faster because only the coil was meshed and no eddy current was modeled. The second method simulated the whole magnet including the coil, the force collar, and the iron yoke. It coupled thermal analysis with transient electromagnetic field analysis which modeled electromagnetic fields including eddy currents within the force collar. Since eddy currents and temperature in the force collars were calculated in various configurations, segmentation of the force collars was optimized under the condition of fast discharge.
E. Sun, P. Brindza, S. Lassiter, M. Fowler, E. Xu
Multiscale finite-volume method for compressible multiphase flow in porous media
The Multiscale Finite-Volume (MSFV) method has been recently developed and tested for multiphase-flow problems with simplified physics (i.e. incompressible flow without gravity and capillary effects) and proved robust, accurate and efficient. However, ... Keywords: compressibility, finite-volume methods, multiphase flow in porous media, multiscale methods, reservoir simulation
Ivan Lunati; Patrick Jenny
Methods and devices for fabricating and assembling printable semiconductor elements
The invention provides methods and devices for fabricating printable semiconductor elements and assembling printable semiconductor elements onto substrate surfaces. Methods, devices and device components of the present invention are capable of generating a wide range of flexible electronic and optoelectronic devices and arrays of devices on substrates comprising polymeric materials. The present invention also provides stretchable semiconductor structures and stretchable electronic devices capable of good performance in stretched configurations.
Nuzzo, Ralph G; Rogers, John A; Menard, Etienne; Lee, Keon Jae; Khang, Dahl-Young; Sun, Yugang; Meitl, Matthew; Zhu, Zhengtao
Nuzzo, Ralph G. (Champaign, IL); Rogers, John A. (Champaign, IL); Menard, Etienne (Durham, NC); Lee, Keon Jae (Daejeon, KR); Khang, Dahl-Young (Urbana, IL); Sun, Yugang (Champaign, IL); Meitl, Matthew (Raleigh, NC); Zhu, Zhengtao (Urbana, IL)
Nuzzo, Ralph G. (Champaign, IL); Rogers, John A. (Champaign, IL); Menard, Etienne (Urbana, IL); Lee, Keon Jae (Savoy, IL); Khang, Dahl-Young (Urbana, IL); Sun, Yugang (Champaign, IL); Meitl, Matthew (Champaign, IL); Zhu, Zhengtao (Urbana, IL)
Finite element modeling of concentrating solar collectors for evauation of gravity loads, bending, and optical characterization.
Understanding the effects of gravity and wind loads on concentrating solar power (CSP) collectors is critical for performance calculations and developing more accurate alignment procedures and techniques. This paper presents a rigorous finite-element model of a parabolic trough collector that is used to determine the impact of gravity loads on bending and displacements of the mirror facets and support structure. The geometry of the LUZ LS-2 parabolic trough collector was modeled using SolidWorks, and gravity-induced loading and displacements were simulated in SolidWorks Simulation. The model of the trough collector was evaluated in two positions: the 90{sup o} position (mirrors facing upward) and the 0{sup o} position (mirrors facing horizontally). The slope errors of the mirror facet reflective surfaces were found by evaluating simulated angular displacements of node-connected segments along the mirror surface. The ideal (undeformed) shape of the mirror was compared to the shape of the deformed mirror after gravity loading. Also, slope errors were obtained by comparing the deformed shapes between the 90{sup o} and 0{sup o} positions. The slope errors resulting from comparison between the deformed vs. undeformed shape were as high as {approx}2 mrad, depending on the location of the mirror facet on the collector. The slope errors resulting from a change in orientation of the trough from the 90{sup o} position to the 0{sup o} position with gravity loading were as high as {approx}3 mrad, depending on the location of the facet.
Christian, Joshua M.; Ho, Clifford Kuofei
Utilization of a finite element model to verify spent nuclear fuel storage rack welds
Elastic and plastic finite element analyses were performed for the inner tie block assembly of a 25 port fuel rack designed for installation at the Idaho National Engineering and Environmental Laboratory (INEEL) Idaho Chemical Processing Plant (ICPP). The model was specifically developed to verify the adequacy of certain welds joining components of the fuel storage rack assembly. The work scope for this task was limited to an investigation of the stress levels in the inner tie welds when the rack was subjected to seismic loads. Structural acceptance criteria used for the elastic calculations performed were as defined by the rack`s designer. Structural acceptance criteria used for the plastic calculations performed as part of this effort were as defined in Subsection NF and Appendix F of Section III of the ASME Boiler and Pressure Vessel Code. The results confirm that the welds joining the inner tie block to the surrounding rack structure meet the acceptance criteria. The analysis results verified that the inner tie block welds should be capable of transferring the expected seismic load without structural failure.
Nitzel, M.E.
Finite element analyses of continuous filament ties for masonry applications : final report for the Arquin Corporation.
Finite-element analyses were performed to simulate the response of a hypothetical vertical masonry wall subject to different lateral loads with and without continuous horizontal filament ties laid between rows of concrete blocks. A static loading analysis and cost comparison were also performed to evaluate optimal materials and designs for the spacers affixed to the filaments. Results showed that polypropylene, ABS, and polyethylene (high density) were suitable materials for the spacers based on performance and cost, and the short T-spacer design was optimal based on its performance and functionality. Simulations of vertical walls subject to static loads representing 100 mph winds (0.2 psi) and a seismic event (0.66 psi) showed that the simulated walls performed similarly and adequately when subject to these loads with and without the ties. Additional simulations and tests are required to assess the performance of actual walls with and without the ties under greater loads and more realistic conditions (e.g., cracks, non-linear response).
Quinones, Armando, Sr. (Arquin Corporation, La Luz, NM); Bibeau, Tiffany A.; Ho, Clifford Kuofei
Electrical and thermal finite element modeling of arc faults in photovoltaic bypass diodes.
Arc faults in photovoltaic (PV) modules have caused multiple rooftop fires. The arc generates a high-temperature plasma that ignites surrounding materials and subsequently spreads the fire to the building structure. While there are many possible locations in PV systems and PV modules where arcs could initiate, bypass diodes have been suspected of triggering arc faults in some modules. In order to understand the electrical and thermal phenomena associated with these events, a finite element model of a busbar and diode was created. Thermoelectrical simulations found Joule and internal diode heating from normal operation would not normally cause bypass diode or solder failures. However, if corrosion increased the contact resistance in the solder connection between the busbar and the diode leads, enough voltage potentially would be established to arc across micron-scale electrode gaps. Lastly, an analytical arc radiation model based on observed data was employed to predicted polymer ignition times. The model predicted polymer materials in the adjacent area of the diode and junction box ignite in less than 0.1 seconds.
Bower, Ward Isaac; Quintana, Michael A.; Johnson, Jay
Multi-scale finite-volume method for elliptic problems in subsurface flow simulation
In this paper we present a multi-scale finite-volume (MSFV) method to solve elliptic problems with many spatial scales arising from flow in porous media. The method efficiently captures the effects of small scales on a coarse grid, is conservative, and ... Keywords: finite-volume, multi-scale physics, subsurface flow, upscaling
P. Jenny; S. H. Lee; H. A. Tchelepi
A method is given for preparing a fuel element for a nuclear reactor. The method includes the steps of sandblasting a body of uranium dioxide to roughen the surface thereof, depositing a thin layer of carbon thereon by thermal decomposition of methane, and cladding the uranium dioxide body with zirconium by gas pressure bonding. (AEC)
Layer, E.H. Jr.; Peet, C.S.
User's Manual for the FEHM Application-A Finite-Element Heat- and Mass-Transfer Code
This document is a manual for the use of the FEHM application, a finite-element heat- and mass-transfer computer code that can simulate nonisothermal multiphase multicomponent flow in porous media. The use of this code is applicable to natural-state studies of geothermal systems and groundwater flow. A primary use of the FEHM application will be to assist in the understanding of flow fields and mass transport in the saturated and unsaturated zones below the proposed Yucca Mountain nuclear waste repository in Nevada. The equations of heat and mass transfer for multiphase flow in porous and permeable media are solved in the FEHM application by using the finite-element method. The permeability and porosity of the medium are allowed to depend on pressure and temperature. The code also has provisions for movable air and water phases and noncoupled tracers; that is, tracer solutions that do not affect the heat- and mass-transfer solutions. The tracers can be passive or reactive. The code can simulate two-dimensional, two-dimensional radial, or three-dimensional geometries. In fact, FEHM is capable of describing flow that is dominated in many areas by fracture and fault flow, including the inherently three-dimensional flow that results from permeation to and from faults and fractures. The code can handle coupled heat and mass-transfer effects, such as boiling, dryout, and condensation that can occur in the near-field region surrounding the potential repository and the natural convection that occurs through Yucca Mountain due to seasonal temperature changes. The code is also capable of incorporating the various adsorption mechanisms, ranging from simple linear relations to nonlinear isotherms, needed to describe the very complex transport processes at Yucca Mountain. This report outlines the uses and capabilities of the FEHM application, initialization of code variables, restart procedures, and error processing. The report describes all the data files, the input data, including individual input records or parameters, and the various output files. The system interface is described, including the software environment and installation instructions. Examples illustrating various aspects of the code are sprinkled throughout the report, and the final section demonstrates how to construct an input file, shows typical code execution, and gives three examples: heat conduction in a square, a reactive-transport problem, and Problem 5, Case of the DOE Code Comparison Project.
A study of detonation timing and fragmentation using 3-D finite element techniques and a damage constitutive model
The transient dynamics finite element computer program, PRONTO-3D, has been used in conjunction with a damage constitutive model to study the influence of detonation timing on rock fragmentation during blasting. The primary motivation of this study is to investigate the effectiveness of precise detonators in improving fragmentation. PRONTO-3D simulations show that a delay time of 0.0 sec between adjacent blastholes results in significantly more fragmentation than a 0.5 ms delay.
Preece, D.S.; Thorne, B.J.
Abstract A COUPLED CFD FINITE ELEMENT ANALYSIS METHODOLOGY IN A BIFURCATION PIPE IN A NUCLEAR PLANT HEAT EXCHANGER
The accurate calculation of temperature distribution in key parts of a nuclear plant plays a crucial role in maximising the power output and the plant efficiency, whilst ensuring safe operation. The need for making the most profitable use of the available sources of energy requires the full exploitation of plant operational capacity. Temperature dependent material properties mean that increasing the power output in a nuclear plant may reduce the life of the welds in the pipes of the heat exchanger (boiler), operating in very demanding conditions. Rolls-Royce plc was requested to come up with a suitable solution that shielded critical pipe weld locations, reducing local temperatures, so allowing a useful increase in power output from the plant. Part of the heat shield design process was a comprehensive thermal analysis of the installation. Traditionally fluid and solid simulations are conducted separately or using conjugate analysis. Standard methods rely on the application of boundary conditions to the wall surface, which are commonly based on empirical heat transfer coefficient correlations or approximate read across of the CFD results. An alternative approach using conjugate calculations can be adopted, but the computational cost and meshing difficulties in matching the fluid and solid grids makes this unaffordable in terms of analysis time. This paper presents the application of an improved method using a communication library (SC89) between the in-house finite element (FE) code SC03, and the commercial computational fluid dynamics (CFD) code FLUENT. The method has been validated using test data from a Perspex model, where heat transfer coefficients were measured using a transient liquid crystal technique.
J. A. Dixon; A. Guijarro Valencia; P. Irel; P. Ridl; N. Hills
Nuclear fuel elements and method of making same
A nuclear fuel element for a high temperature gas nuclear reactor that has an average operating temperature in excess of 2000.degree. C., and a method of making such a fuel element. The fuel element is characterized by having fissionable fuel material localized and stabilized within pores of a carbon or graphite member by melting the fissionable material to cause it to chemically react with the carbon walls of the pores. The fissionable fuel material is further stabilized and localized within the pores of the graphite member by providing one or more coatings of pyrolytic carbon or diamond surrounding the porous graphite member so that each layer defines a successive barrier against migration of the fissionable fuel from the pores, and so that the outermost layer of pyrolytic carbon or diamond forms a barrier between the fissionable material and the moderating gases used in an associated high temperature gas reactor. The method of the invention provides for making such new elements either as generally spherically elements, or as flexible filaments, or as other relatively small-sized fuel elements that are particularly suited for use in high temperature gas reactors.
Schweitzer, Donald G. (Bayport, NY)
Design method for turbomachine blades with finite thickness by the circulation method
This paper presents a procedure to extend a recently developed three-dimensional inverse method for infinitely thin blades to handle blades with finite thickness. In this inverse method, the prescribed quantities are the blade pressure loading and the blade thickness distributions, and the calculated quantity is the blade mean camber line. The method is formulated in the fully inverse mode whereby the blade shape is determined iteratively using the flow-tangency condition along the blade surfaces. Design calculations are presented for an inlet guide vane, an impulse turbine blade, and a compressor blade in the two-dimensional inviscid- and incompressible-flow limit. Consistency checks are carried out for these design calculations using a panel analysis method and the analytical solution for the Gostelow profile.
Jiang, J.; Dang, T. [Syracuse Univ., NY (United States). Dept. of Mechanical, Aerospace and Manufacturing Engineering
ERROR ESTIMATES FOR FINITE DIFFERENCE METHODS FOR A WIDE-ANGLE `PARABOLIC' EQUATION G. D. AKRIVIS-value problem for a third-order p.d.e., a wide-angle `parabolic' equation frequently used in underwater. wide-angle `parabolic' equation, Underwater Acoustics, finite difference error esti- mates, interface
Modeling complex wells with the multi-scale finite-volume method
In this paper, an extension of the multi-scale finite-volume (MSFV) method is devised, which allows to simulate flow and transport in reservoirs with complex well configurations. The new framework fits nicely into the data structure of the original MSFV ... Keywords: Gravity, Heterogeneous media, Multi-phase flow, Multi-scale finite-volume, Porous media, Well modeling
Patrick Jenny; Ivan Lunati
Adaptive multiscale finite-volume method for nonlinear multiphase transport in heterogeneous formations
In the previous multiscale finite-volume (MSFV) method, an efficient and accurate multiscale approach was proposed to solve the elliptic flow equation. The reconstructed fine-scale velocity field was then used to solve the nonlinear hyperbolic transport ... Keywords: Adaptivity, Multigrid, Multiphase flow, Multiscale finite-volume, Nonlinear transport, Porous media, Reservoir simulation
S. H. Lee; H. Zhou; H. A. Tchelepi
Adaptive Algebraic Multigrid for Finite Element Elliptic Equations with Random Coefficients
This thesis presents a two-grid algorithm based on Smoothed Aggregation Spectral Element Agglomeration Algebraic Multigrid (SA-{rho}AMGe) combined with adaptation. The aim is to build an efficient solver for the linear systems arising from discretization of second-order elliptic partial differential equations (PDEs) with stochastic coefficients. Examples include PDEs that model subsurface flow with random permeability field. During a Markov Chain Monte Carlo (MCMC) simulation process, that draws PDE coefficient samples from a certain distribution, the PDE coefficients change, hence the resulting linear systems to be solved change. At every such step the system (discretized PDE) needs to be solved and the computed solution used to evaluate some functional(s) of interest that then determine if the coefficient sample is acceptable or not. The MCMC process is hence computationally intensive and requires the solvers used to be efficient and fast. This fact that at every step of MCMC the resulting linear system changes, makes an already existing solver built for the old problem perhaps not as efficient for the problem corresponding to the new sampled coefficient. This motivates the main goal of our study, namely, to adapt an already existing solver to handle the problem (with changed coefficient) with the objective to achieve this goal to be faster and more efficient than building a completely new solver from scratch. Our approach utilizes the local element matrices (for the problem with changed coefficients) to build local problems associated with constructed by the method agglomerated elements (a set of subdomains that cover the given computational domain). We solve a generalized eigenproblem for each set in a subspace spanned by the previous local coarse space (used for the old solver) and a vector, component of the error, that the old solver cannot handle. A portion of the spectrum of these local eigen-problems (corresponding to eigenvalues close to zero) form the coarse basis used to define the new two-level method of our interest. We illustrate the performance of this adaptive two-level procedure with a large set of numerical experiments that demonstrate its efficiency over building the solvers from scratch.
Kalchev, D
Tangential residual as error estimator in the boundary element method
In this paper a new error estimator based on tangential derivative Boundary Integral Equation residuals for 2D Laplace and Helmholtz equations is shown. The direct problem for general mixed boundary conditions is solved using standard and hypersingular ... Keywords: Adaptivity, Boundary Integral Equation residual, Boundary element method, Error estimation, Mesh adaptation, Mesh refinement, Nodal sensitivity
Alejandro E. MartĒnez-Castro; Rafael Gallego
Method and apparatus for diagnosing breached fuel elements
The invention provides an apparatus and method for diagnosing breached fuel elements in a nuclear reactor. A detection system measures the activity of isotopes from the cover gas in the reactor. A data acquisition and processing system monitors the detection system and corrects for the effects of the cover-gas clean up system on the measured activity and further calculates the derivative curve of the corrected activity as a function of time. A plotting system graphs the derivative curve, which represents the instantaneous release rate of fission gas from a breached fuel element. 8 figs.
Gross, K.C.; Lambert, J.D.B.; Nomura, S.
Finite-element analyses of blade and slot coating flows using an implicit pseudo-solid domain mapping technique coupled with unstructured grids
In coating processes (e.g. in blade coating) the flow domain inherently contains free surfaces and three-phase contact lines, and characteristic length scales of flow features in the dimension transverse to the web-movement vary by an order of magnitude or more from a fraction of a millimeter or more to tens of microns or less). The presence of free surfaces and three-phase contact lines, and the sudden changes of flow geometry and directions create difficulties in theoretical analyses of such flows. Though simulations of coating flows via finite-element methods using structured grids have been reportedly demonstrated in the literature, achieving high efficiency of such numerical experiments remains a grand challenge -- mainly due to difficulties in local mesh-refinement and in avoiding unacceptably distorted grids. High efficiency of computing steady flow fields under various process conditions is crucial in shortening turn-around time in design and optimization of coating-flow processes. In this paper we employ a fully-implicit, pseudo-solid, domain mapping technique coupled with unstructured meshes to analyze blade and slot coating flows using Galerkin`s method with finite element basis functions. We demonstrate the robustness and efficiency of our unique technique in circumventing shortcomings of mesh-motion schemes currently being used in the coating-flow research community. Our goal is to develop an efficient numerical tool, together with a suitable optimization toolkit, that can be used routinely in design and optimization of coating-flow processes.
Chen, K.S.; Schunk, P.R.; Sackinger, P.A.
A comparison between microscopic methods for finite temperature Bose gases
We analyze the equilibrium properties of a weakly interacting, trapped quasi-one-dimensional Bose gas at finite temperatures and compare different theoretical approaches. We focus in particular on two stochastic theories: a number-conserving Bogoliubov (ncB) approach and a stochastic Gross-Pitaevskii equation (sGPe) that have been extensively used in numerical simulations. Equilibrium properties like density profiles, correlation functions, and the condensate statistics are compared to predictions based upon a number of alternative theories. We find that due to thermal phase fluctuations, and the corresponding condensate depletion, the ncB approach loses its validity at relatively low temperatures. This can be attributed to the change in the Bogoliubov spectrum, as the condensate gets thermally depleted, and to large fluctuations beyond perturbation theory. Although the two stochastic theories are built on different thermodynamic ensembles (ncB: canonical, sGPe: grand-canonical), they yield the correct conden...
Cockburn, S P; Proukakis, N P; Henkel, C
Method for measuring recovery of catalytic elements from fuel cells
A method is provided for measuring the concentration of a catalytic clement in a fuel cell powder. The method includes depositing on a porous substrate at least one layer of a powder mixture comprising the fuel cell powder and an internal standard material, ablating a sample of the powder mixture using a laser, and vaporizing the sample using an inductively coupled plasma. A normalized concentration of catalytic element in the sample is determined by quantifying the intensity of a first signal correlated to the amount of catalytic element in the sample, quantifying the intensity of a second signal correlated to the amount of internal standard material in the sample, and using a ratio of the first signal intensity to the second signal intensity to cancel out the effects of sample size.
Shore, Lawrence (Edison, NJ); Matlin, Ramail (Berkeley, NJ)
Method for detection of antibodies for metallic elements
An apparatus and method for detecting antibodies specific to non-protein antigens. The apparatus is an immunological plate containing a plurality of plastic projections coated with a non-protein material. Assays utilizing the plate are capable of stabilizing the non-protein antigens with detection levels for antibodies specific to the antigens on a nanogram level. A screening assay with the apparatus allows for early detection of exposure to non-protein materials. Specifically metallic elements are detected. 10 figures.
Barrick, C.W.; Clarke, S.M.; Nordin, C.W.
The Matrix Element Method: Past, Present, and Future
The increasing use of multivariate methods, and in particular the Matrix Element Method (MEM), represents a revolution in experimental particle physics. With continued exponential growth in computing capabilities, the use of sophisticated multivariate methods-- already common-- will soon become ubiquitous and ultimately almost compulsory. While the existence of sophisticated algorithms for disentangling signal and background might naively suggest a diminished role for theorists, the use of the MEM, with its inherent connection to the calculation of differential cross sections will benefit from collaboration between theorists and experimentalists. In this white paper, we will briefly describe the MEM and some of its recent uses, note some current issues and potential resolutions, and speculate about exciting future opportunities.
Gainer, James S; Matchev, Konstantin T; Mrenna, Stephen; Park, Myeonghun
James S. Gainer; Joseph Lykken; Konstantin T. Matchev; Stephen Mrenna; Myeonghun Park
Nonlinear Krylov and moving nodes in the method of lines
We report on some successes and problem areas in the Method of Lines from our work with moving node finite element methods. First, we report on our ''nonlinear Krylov accelerator'' for the modified Newton's method on the nonlinear equations of our stiff ... Keywords: Iterative linear solver, Method of lines, Moving finite elements, Moving node finite elements, Nonlinear Krylov method
Keith Miller
Methods for removing transuranic elements from waste solutions
This report outlines a treatment scheme for separating and concentrating the transuranic (TRU) elements present in aqueous waste solutions stored at Argonne National Laboratory (ANL). The treatment method selected is carrier precipitation. Potential carriers will be evaluated in future laboratory work, beginning with ferric hydroxide and magnetite. The process will result in a supernatant with alpha activity low enough that it can be treated in the existing evaporator/concentrator at ANL. The separated TRU waste will be packaged for shipment to the Waste Isolation Pilot Plant.
Slater, S.A.; Chamberlain, D.B.; Connor, C.; Sedlet, J.; Srinivasan, B.; Vandegrift, G.F.
Combined characteristics and finite volume methods for sediment transport and bed morphology in surface water flows
Abstract: We propose a new numerical method for solving the equations of coupled sediment transport and bed morphology by free-surface water flows. The mathematical formulation of these models consists of the shallow water equations for the hydraulics, ... Keywords: Bed morphology, Finite volume scheme, Method of characteristics, Sediment transport, Shallow water equations
Fayssal Benkhaldoun; Mohammed Sea'd
Finite element modelling and analysis of bolted joints of three dimensional tubular structures
A Hungarian "Steel Cooling Tower Consortium" aimed to develop a new type steel cooling tower, in the framework of a governmental R&D project. Members of the structure are prefabricated tubular elements characterized by high radius-to-thickness ratio. ... Keywords: bolted endplate connection, gusset plate, model development, non-linear FEM, steel cooling tower, thin-walled section, tubular structure, virtual experiment
L. G. Vigh; L. Dunai
18.086 Mathematical Methods for Engineers II, Spring 2005
Scientific computing: Fast Fourier Transform, finite differences, finite elements, spectral method, numerical linear algebra. Complex variables and applications. Initial-value problems: stability or chaos in ordinary ...
Strang, Gilbert
Intercomparison of the finite difference and nodal discrete ordinates and surface flux transport methods for a LWR pool-reactor benchmark problem in X-Y geometry
The aim of the present work is to compare and discuss the three of the most advanced two dimensional transport methods, the finite difference and nodal discrete ordinates and surface flux method, incorporated into the transport codes TWODANT, TWOTRAN-NODAL, MULTIMEDIUM and SURCU. For intercomparison the eigenvalue and the neutron flux distribution are calculated using these codes in the LWR pool reactor benchmark problem. Additionally the results are compared with some results obtained by French collision probability transport codes MARSYAS and TRIDENT. Because the transport solution of this benchmark problem is close to its diffusion solution some results obtained by the finite element diffusion code FINELM and the finite difference diffusion code DIFF-2D are included.
O'Dell, R.D.; Stepanek, J.; Wagner, M.R.
Scalable implicit finite element solver for massively parallel processing with demonstration to 160K cores
Implicit methods for partial differential equations using unstructured meshes allow for an efficient solution strategy for many real-world problems (e.g., simulation-based virtual surgical planning). Scalable solvers employing these methods not only ...
Onkar Sahni; Min Zhou; Mark S. Shephard; Kenneth E. Jansen
Computational upscaled modeling of heterogeneous porous media flow utilizing finite volume method
In this dissertation we develop and analyze numerical method to solve general elliptic boundary value problems with many scales. The numerical method presented is intended to capture the small scales e?ect on the large scale solution without resolving the small scale details, which is done through the construction of a multiscale map. The multiscale method is more e?ective when the coarse element size is larger than the small scale length. To guarantee a numerical conservation, a ?nite volume element method is used to construct the global problem. Analysis of the multiscale method is separately done for cases of linear and nonlinear coe?cients. For linear coe?cients, the multiscale ?nite volume element method is viewed as a perturbation of multiscale ?nite element method. The analysis uses substantially the existing ?nite element results and techniques. The multiscale method for nonlinear coe?cients will be analyzed in the ?nite element sense. A class of correctors corresponding to the multiscale method will be discussed. In turn, the analysis will rely on approximation properties of this correctors. Several numerical experiments verifying the theoretical results will be given. Finally we will present several applications of the multiscale method in the ?ow in porous media. Problems that we will consider are multiphase immiscible ?ow, multicomponent miscible ?ow, and soil in?ltration in saturated/unsaturated ?ow.
Ginting, Victor Eralingga
Numerical study on transient heat transfer under soil with plastic mulch in agriculture applications using a nonlinear finite element model
In this paper is developed a simple mathematical model of transient heat transfer under soil with plastic mulch in order to determine with numerical studies the influence of different plastic mulches on the soil temperature and the evolutions of temperatures at different depths with time. The governing differential equations are solved by a Galerkin Finite Element Model, taking into account the nonlinearities due to radiative heat exchange between the soil surface, the plastic mulch and the atmosphere. The model was validated experimentally giving good approximation of the model to the measured data. Simulations were run with the validated model in order to determine the optimal combination of mulch optical properties to maximize the soil temperature with a Taguchi's analysis, proving that the material most used nowadays in Colombia is not the optimal and giving quantitative results of the properties the optimal mulch must possess.
De Castro, Carlos Armando
Comparative Finite Element Analysis of the Stress-Strain States in Three Different Bonded Solid Oxide Fuel Cell Seal Designs
One of the critical issues in designing and fabricating a high performance planar solid oxide fuel cell (pSOFC) stack is the development of the appropriate materials and techniques for hermetically sealing the metal and ceramic components. We are currently developing a foil-based approach that appears to offer good hermeticity and mechanical integrity, while minimizing the generation of interfacial stresses in either of the joint substrate materials, particulary the ceramic cell. Prior experimental work conducted on small-scale samples demonstrated the viability of the concept. Here we present recent results from computational analyses undertaken to investigate potential issues associated with scaling up the seal to full-scale pSOFC stack dimensions/geometry. Here we employ finite element modeling to assess the potential thermal cycling performance of this design, specifically as it pertains to sealing components with vastly different thermal expansion properties.
Weil, K. Scott; Koeppel, Brian J.
Finite Difference Methods for the Heat Equation MATH 418, PDE LAB Spring 2013
Finite Difference Methods for the Heat Equation MATH 418, PDE LAB Spring 2013 Lab #5 We seek numerical solutions of the heat equation u t = c2 2 u x2 , 0 0 (1) with boundary conditions u(0) Here x = L/(N + 1). The collection of points (4), (5) is called the computational grid. The matrix-grid
Bardsley, John
The Finite Segment Method for Recursive Approach to Flexible Multibody Dynamics
In this paper we study the dynamics and kinematics of serial flexible link manipulators using the finite segment method. In our analysis the flexible manipulators are divided into a set of rigid bodies coupled with springs and dampers. The dynamic equations ...
Hongli Sun; Hongtao Wu; Bing Shao; Fuyang Tian
A Variable Resolution Global Model Based upon Fourier and Finite Element Representation
We describe the development and preliminary testing of a numerical scheme designed to predict the global circulation which can also telescope into local subdomains of enhanced vertical and horizontal resolution. The accuracy of the method appears ...
Jan Paegle
Parallel Finite Element Electron-Photon Transport Analysis on 2-D Unstructured Mesh
A computer code has been developed to solve the linear Boltzmann transport equation on an unstructured mesh of triangles, from a Pro/E model. An arbitriwy arrangement of distinct material regions is allowed. Energy dependence is handled by solving over an arbitrary number of discrete energy groups. Angular de- pendence is treated by Legendre-polynomial expansion of the particle cross sections and a discrete ordinates treatment of the particle fluence. The resulting linear system is solved in parallel with a preconditioned conjugate-gradients method. The solution method is unique, in that the space-angle dependence is solved si- multaneously, eliminating the need for the usual inner iterations. Electron cross sections are obtained from a Goudsrnit-Saunderson modifed version of the CEPXS code. A one-dimensional version of the code has also been develop@ for testing and development purposes.
Drumm, C.R.
Solid modeling techniques to build 3D finite element models of volcanic systems: An example from the Rabaul Caldera system, Papua New Guinea
Simulating the deformation of active volcanoes is challenging due to inherent mechanical complexities associated with heterogeneous distributions of rheologic properties and irregular geometries associated with the topography and bathymetry. From geologic ... Keywords: 3D geometry, Deformation, Finite Elements Models, Rabaul Caldera
Erika Ronchin, Timothy Masterlark, Joan MartĒ Molist, Steve Saunders, Wei Tao
Method of determining lanthanidies in a transition element host
A phosphor composition contains a lanthanide activator element within a host matrix having a transition element as a major component. The host matrix is composed of certain rare earth phosphates or vanadates such as YPO.sub.4 with a portion of the rare earth replaced with one or more of the transition elements. On X-ray or other electromagnetic excitation, trace lanthanide impurities or additives within the phosphor are spectrometrically determined from their characteristic luminescence.
De Kalb, Edward L. (Ames, IA); Fassel, Velmer A. (Ames, IA)
Discrete Element Method Applied to the Vibration Process of Coke ...
In the present work, effects of particle shape and size distribution on vibrated bulk density (VBD) of dry coke samples have been investigated. Discrete ElementĀ...
A top quark mass measurement using a matrix element method
A measurement of the mass of the top quark is presented, using top-antitop pair (t{bar t}) candidate events for the lepton+jets decay channel. The measurement makes use of Tevatron p{bar p} collision data at centre-of-mass energy {radical}s = 1.96 TeV, collected at the CDF detector. The top quark mass is measured by employing an unbinned maximum likelihood method where the event probability density functions are calculated using signal (t{bar t}) and background (W+jets) matrix elements, as well as a set of parameterised jet-to-parton mapping functions. The likelihood function is maximised with respect to the top quark mass, the fraction of signal events, and a correction to the jet energy scale (JES) of the calorimeter jets. The simultaneous measurement of the JES correction ({Delta}{sub JES}) provides an in situ jet energy calibration based on the known mass of the hadronically decaying W boson. Using 578 lepton+jets candidate events corresponding to 3.2 fb{sup -1} of integrated luminosity, the top quark mass is measured to be m{sub t} = 172.4 {+-} 1.4 (stat+{Delta}{sub JES}) {+-} 1.3 (syst) GeV=c{sup 2}, one of the most precise single measurements to date.
Linacre, Jacob Thomas; /Oxford U.
Multi-element probabilistic collocation method in high dimensions
We combine multi-element polynomial chaos with analysis of variance (ANOVA) functional decomposition to enhance the convergence rate of polynomial chaos in high dimensions and in problems with low stochastic regularity. Specifically, we employ the multi-element ... Keywords: Domain decomposition, Sparse grids, Stochastic partial differential equations
Jasmine Foo; George Em Karniadakis
A spectral-element discontinuous Galerkin lattice Boltzmann method for nearly incompressible flows
We present a spectral-element discontinuous Galerkin lattice Boltzmann method for solving nearly incompressible flows. Decoupling the collision step from the streaming step offers numerical stability at high Reynolds numbers. In the streaming step, we ... Keywords: Discontinous Galerkin method, Lattice Boltzmann method, Spectral element method
Misun Min; Taehun Lee
Finite Element Solution of the Self-Adjoint Angular Flux Equation for Coupled Electron-Photon Transport
A novel approach is proposed for charged particle transport calculations using a recently developed second-order, self-adjoint angular flux (SAAF) form of the Boltzmann transport equation with continuous slowing-down. A finite element discretization that is linear continuous in space and linear discontinuous (LD) in energy is described and implemented in a one-dimensional, planar geometry, multigroup, discrete ordinates code for charged particle transport. The cross-section generating code CEPXS is used to generate the electron and photon transport cross sections employed in this code. The discrete ordinates SAAF transport equation is solved using source iteration in conjunction with an inner iteration acceleration scheme and an outer iteration acceleration scheme. Outer iterations are required with the LD energy discretization scheme because the two angular flux unknowns within each group are coupled, which gives rise to effective upscattering. The inner iteration convergence is accelerated using diffusion synthetic acceleration, and the outer iteration convergence is accelerated using a diamond difference approximation to the LD energy discretization. Computational results are given that demonstrate the effectiveness of our convergence acceleration schemes and the accuracy of our discretized SAAF equation.
Liscum-Powell, Jennifer L. [Sandia National Laboratories (United States); Prinja, Anil B. [University of New Mexico (United States); Morel, Jim E. [Los Alamos National Laboratory (United States); Lorence, Leonard J Jr. [Sandia National Laboratories (United States)
Finite element analyses of continuous filament ties for masonry applications:final report for the Arquin Corporation.
Finite-element analyses were performed to simulate the response of a hypothetical masonry shear wall with and without continuous filament ties to various lateral loads. The loads represented three different scenarios: (1) 100 mph wind, (2) explosive attack, and (3) an earthquake. In addition, a static loading analysis and cost comparison were performed to evaluate optimal materials and designs for the spacers affixed to the filaments. Results showed that polypropylene, ABS, and polyethylene (high density) were suitable materials for the spacers based on performance and cost, and the short T-spacer design was optimal based on its performance and functionality. Results of the shear-wall loading simulations revealed that simulated walls with the continuous filament ties yielded factors of safety that were at least ten times greater than those without the ties. In the explosive attack simulation (100 psi), the simulated wall without the ties failed (minimum factor of safety was less than one), but the simulated wall with the ties yielded a minimum factor of safety greater than one. Simulations of the walls subject to lateral loads caused by 100 mph winds (0.2 psi) and seismic events with a peak ground acceleration of 1 ''g'' (0.66 psi) yielded no failures with or without the ties. Simulations of wall displacement during the seismic scenarios showed that the wall with the ties resulted in a maximum displacement that was 20% less than the wall without the ties.
Quinones, Armando (Arquin Corporation, La Luz, NM); Bibeau, Tiffany A.; Ho, Clifford Kuofei
A finite element analysis modeling tool for solid oxide fuel cell development: coupled electrochemistry, thermal and flow analysis in MARC«
A 3D simulation tool for modeling solid oxide fuel cells is described. The tool combines the versatility and efficiency of a commercial finite element analysis code, MARC{reg_sign}, with an in-house developed robust and flexible electrochemical (EC) module. Based upon characteristic parameters obtained experimentally and assigned by the user, the EC module calculates the current density distribution, heat generation, and fuel and oxidant species concentration, taking the temperature profile provided by MARC{reg_sign} and operating conditions such as the fuel and oxidant flow rate and the total stack output voltage or current as the input. MARC{reg_sign} performs flow and thermal analyses based on the initial and boundary thermal and flow conditions and the heat generation calculated by the EC module. The main coupling between MARC{reg_sign} and EC is for MARC{reg_sign} to supply the temperature field to EC and for EC to give the heat generation profile to MARC{reg_sign}. The loosely coupled, iterative scheme is advantageous in terms of memory requirement, numerical stability and computational efficiency. The coupling is iterated to self-consistency for a steady-state solution. Sample results for steady states as well as the startup process for stacks with different flow designs are presented to illustrate the modeling capability and numerical performance characteristic of the simulation tool.
Khaleel, Mohammad A.; Lin, Zijing; Singh, Prabhakar; Surdoval, Wayne; Collin, D
Nonlinear finite-element analysis of a reinforced-concrete Mark III containment under pressure and gravity loads. [BWR
An analysis of a Mark III reactor containment vessel subjected to a uniformly increasing internal pressure and gravity loads is carried out in order to ascertain the load carrying capacity of the structure under hydrogen burn. The analysis is conducted by using a nonlinear finite element model that includes nonlinearities in the strain-displacement relations as well as in the material constitutive equations. In this analysis, the nonlinear behavior of the liner and reinforcement steels is described by a von Mises elastic-plastic model with isotropic hardening. A recently developed elastic-plastic-fracture model that includes both the cracking and crushing limit states is used for the plain concrete. Consistent smearing and de-smearing procedures are then used to represent the composite material properties of the reinforced concrete by an anisotropic and locally homogeneous continuum. Results pertaining to the critical regions of the containment where cracking of the concrete, yielding of the reinforcement bars, and substantial straining of the liner take place are discussed.
Sharma, S.; Reich, M.; Shteyngart, S.; Chang, T.Y.
A fuel element consisting of uranium nitride and uranium carbide in the form of discrete particles in a solid coherent matrix of a metal such as steel, beryllium, uranium, or zirconium and clad with a metal such as steel, aluminum, zirconium, or beryllium is described. The element is made by mixing powdered uranium nitride and uranium carbide with powdered matrix metal, then compacting and sintering the mixture. (AEC)
Kingston, W.E.; Kopelman, B.; Hausner, H.H.
An Efficient Finite Difference Method for Parameter Sensitivities of Continuous Time Markov Chains
We present an efficient finite difference method for the computation of parameter sensitivities for a wide class of continuous time Markov chains. The motivating class of models, and the source of our examples, are the stochastic chemical kinetic models commonly used in the biosciences, though other natural application areas include population processes and queuing networks. The method is essentially derived by making effective use of the random time change representation of Kurtz, and is no harder to implement than any standard continuous time Markov chain algorithm, such as "Gillespie's algorithm" or the next reaction method. Further, the method is analytically tractable, and, for a given number of realizations of the stochastic process, produces an estimator with substantially lower variance than that obtained using other common methods. Therefore, the computational complexity required to solve a given problem is lowered greatly. In this work, we present the method together with the theoretical analysis de...
Anderson, David F
Finite Element-Based
Analyzing Upper Tails of Grain Size Distributions Using Extreme Value ... Strain Gradient and Degradation in Magnetic Properties: Focus Transformer Steel.
Preprint of the paper "A Validation of the Boundary Element Method for Grounding Grid Design and
- cades for substation grounding analysis, such as the Average Potential Method (APM), have been recentlyPreprint of the paper "A Validation of the Boundary Element Method for Grounding Grid Design://caminos.udc.es/gmni #12;A VALIDATION OF THE BOUNDARY ELEMENT METHOD FOR GROUNDING GRID DESIGN AND COMPUTATION I. Colominas
Colominas, Ignasi
The use of direct boundary element method for gaining insight into complex seismic site response
The boundary element method is specially well suited for the analysis of the seismic response of valleys of complicated topography and stratigraphy. In this paper the method's capabilities are illustrated using as an example an irregularity stratified ... Keywords: Boundary element method, Euroseistest, Local conditions, Numerical modelling, Site effects
Sonia ┴lvarez-Rubio; Juan Josķ Benito; Francisco Josķ Sßnchez-Sesma; Enrique Alarc¾n
Interfacial temperature measurements, high-speed visualization and finite-element simulations of droplet impact and evaporation on a solid surface
The objective of this work is to investigate the coupling of fluid dynamics, heat transfer and mass transfer during the impact and evaporation of droplets on a heated solid substrate. A laser-based thermoreflectance method is used to measure the temperature at the solid-liquid interface, with a time and space resolution of 100 {\\mu}s and 20 {\\mu}m, respectively. Isopropanol droplets with micro- and nanoliter volumes are considered. A finite-element model is used to simulate the transient fluid dynamics and heat transfer during the droplet deposition process, considering the dynamics of wetting as well as Laplace and Marangoni stresses on the liquid-gas boundary. For cases involving evaporation, the diffusion of vapor in the atmosphere is solved numerically, providing an exact boundary condition for the evaporative flux at the droplet-air interface. High-speed visualizations are performed to provide matching parameters for the wetting model used in the simulations. Numerical and experimental results are compar...
Bhardwaj, Rajneesh; Attinger, Daniel
Method for recovering catalytic elements from fuel cell membrane electrode assemblies
A method for recovering catalytic elements from a fuel cell membrane electrode assembly is provided. The method includes converting the membrane electrode assembly into a particulate material, wetting the particulate material, forming a slurry comprising the wetted particulate material and an acid leachate adapted to dissolve at least one of the catalytic elements into a soluble catalytic element salt, separating the slurry into a depleted particulate material and a supernatant containing the catalytic element salt, and washing the depleted particulate material to remove any catalytic element salt retained within pores in the depleted particulate material.
Shore, Lawrence (Edison, NJ); Matlin, Ramail (Berkeley Heights, NJ); Heinz, Robert (Ludwigshafen, DE)
Modeling the steady-state ISV (in situ vitrification) process: A 3-D finite element analysis of coupled thermal-electric fields
Steady-state modeling considerations for simulating the in situ vitrification (ISV) process are documented based upon the finite element numerical approach. Recommendations regarding boundary condition specifications and mesh discretization are presented. The effects of several parameters on the ISV process response are calculated and the results discussed. The parameters investigated include: (1) electrode depth, (2) ambient temperature, (3) supplied current, (4) electrical conductivity, (5) electrode separation, and (6) soil/waste characterization. 13 refs., 29 figs., 1 tab.
Langerman, M.A.
Pultrusion manufacturing process development by computational modelling and methods
This paper deals with the modelling and development of computational schemes to simulate pultrusion processes. Two different computational methods, finite differences and elements, are properly developed and critically analyzed. The methods are applied ... Keywords: Degree of cure, Finite difference method, Finite element method, Numerical modelling, Pultrusion, Temperature
P. Carlone; G. S. Palazzo; R. Pasquino
Application of the finite difference method to the problem of pursuit in the distributed-parameter systems
The problem of pursuit in the controlled systems of parabolic type without mixed derivatives with variable coefficients was considered and solved using the finite difference method. Sufficient conditions for pursuit completion were established. Keywords: 02.30.Yy
M. Sh. Mamatov
A Method for Imposing Surface Stress and Heat Flux Conditions in Finite-Difference Models with Steep Terrain
A numerical implementation of the surface stress boundary condition is presented for finite-difference models in which the terrain slope and curvature cannot necessarily be considered small. The method involves reducing the discretized stress ...
C. C. Epifanio
A process and a device for the continuous monitoring of fuel elements while in use in a liquid-metal-cooled, argonblanketed nuclear reactor are presented. A fraction of the argon gas is withdrawn, contacted with a negative electrical charge for attraction of any alkali metal formed from argon by neutron reaction, and recycled into the reactor. The electrical charge is introduced into water, and the water is examined for radioactive alkali metals. (AEC)
Smith, R.R.; Echo, M.W.; Doe, C.B.
Analysis of a metallic nano-rod polarizer using finite-difference-time-domain method
The polarization behavior of metallic nano-rods has been analyzed by means of the finite-difference-time-domain method. When the average spacing between the nano-rods is less than a half wavelength, the layer reflects the light polarized parallel to the nano-rods, as in a nano-slit. However, when the spacing is larger than a half wavelength, the metallic surface absorbs the light, polarized perpendicular to the rods, leading to a polarization reversal. Multiple layers of nano-rods can make a polarizer with a high extinction ratio and good transmittance.
Ju, Young-Gu
Computational methods in structural engineering.
???The present research is focused on computational methods in structural engineering. The main work includes three parts: 1) the development of cubic B-spline finite elementsģ (more)
Yang, Hao (??)
A high resolution finite volume method for efficient parallel simulation of casting processes on unstructured meshes
We discuss selected aspects of a new parallel three-dimensional (3-D) computational tool for the unstructured mesh simulation of Los Alamos National Laboratory (LANL) casting processes. This tool, known as {bold Telluride}, draws upon on robust, high resolution finite volume solutions of metal alloy mass, momentum, and enthalpy conservation equations to model the filling, cooling, and solidification of LANL castings. We briefly describe the current {bold Telluride} physical models and solution methods, then detail our parallelization strategy as implemented with Fortran 90 (F90). This strategy has yielded straightforward and efficient parallelization on distributed and shared memory architectures, aided in large part by new parallel libraries {bold JTpack9O} for Krylov-subspace iterative solution methods and {bold PGSLib} for efficient gather/scatter operations. We illustrate our methodology and current capabilities with source code examples and parallel efficiency results for a LANL casting simulation.
Kothe, D.B.; Turner, J.A.; Mosso, S.J. [Los Alamos National Lab., NM (United States); Ferrell, R.C. [Cambridge Power Computer Assoc. (United States)
GPU-accelerated 3D neutron diffusion code based on finite difference method
Finite difference method, as a traditional numerical solution to neutron diffusion equation, although considered simpler and more precise than the coarse mesh nodal methods, has a bottle neck to be widely applied caused by the huge memory and unendurable computation time it requires. In recent years, the concept of General-Purpose computation on GPUs has provided us with a powerful computational engine for scientific research. In this study, a GPU-Accelerated multi-group 3D neutron diffusion code based on finite difference method was developed. First, a clean-sheet neutron diffusion code (3DFD-CPU) was written in C++ on the CPU architecture, and later ported to GPUs under NVIDIA's CUDA platform (3DFD-GPU). The IAEA 3D PWR benchmark problem was calculated in the numerical test, where three different codes, including the original CPU-based sequential code, the HYPRE (High Performance Pre-conditioners)-based diffusion code and CITATION, were used as counterpoints to test the efficiency and accuracy of the GPU-based program. The results demonstrate both high efficiency and adequate accuracy of the GPU implementation for neutron diffusion equation. A speedup factor of about 46 times was obtained, using NVIDIA's Geforce GTX470 GPU card against a 2.50 GHz Intel Quad Q9300 CPU processor. Compared with the HYPRE-based code performing in parallel on an 8-core tower server, the speedup of about 2 still could be observed. More encouragingly, without any mathematical acceleration technology, the GPU implementation ran about 5 times faster than CITATION which was speeded up by using the SOR method and Chebyshev extrapolation technique. (authors)
Xu, Q.; Yu, G.; Wang, K. [Dept. of Engineering Physics, Tsinghua Univ. (China)
B-Spline Boundary Element Method for Ships.
??The development of a three dimensional B-Spline based method, which is suitable for the steady-state potential flow analysis of free surface piercing bodies in hydrodynamics,ģ (more)
Aggarwal, Aditya Mohan
Fatigue life calculation of desuperheater for solving pipe cracking issue using finite element method (FEM) software
Desuperheater assembly experiences thermal cycling in operation by design. During power plant's start up
Aravinda Kumar; Jeetendra Kumar Singh; K. Mohan
is of order ( x)1=2. This *University of Minnesota Army High Performance Computing Research Center, 1100 Foundation grant DSM-9103997 and by the University of Minnesota Army High Performance Computing Research
Keywords: biosensor, finite element method, dispersion relations *Contact: email@example.com
is lower than in the substrate, shear waves will be transmitted into the guiding layer. The guiding layer waves measured by an electric circuit. Our previous work concentrated on the development of mathematical are being varied, can hardly be performed. A way to speed up numerical simulations consists in the usage
Turova, Varvara
Studies on Nano-Indentation of Polymeric Thin Films Using Finite Element Methods
In this paper, the numerical simulation for nano-indentation is performed to measure time-dependent behavior of polymeric films. The possibility to extract the relaxed shear modulus of the polymer is evaluated using a rigid ...
Shen, Xiaojun
S>A method is described for separating plutonium, in a valence state of less than five, from an aqueous solution in which it is dissolved. The niethod consists in adding potassium and sulfate ions to such a solution while maintaining the solution at a pH of less than 7.1, and isolating the precipitate of potassium plutonium sulfate thus formed.
Duffield, R.B.
Method for the removal of elemental mercury from a gas stream
A method is provided to remove elemental mercury from a gas stream by reacting the gas stream with an oxidizing solution to convert the elemental mercury to soluble mercury compounds. Other constituents are also oxidized. The gas stream is then passed through a wet scrubber to remove the mercuric compounds and oxidized constituents. 7 figs.
Mendelsohn, M.H.; Huang, H.S.
A method is provided to remove elemental mercury from a gas stream by reacting the gas stream with an oxidizing solution to convert the elemental mercury to soluble mercury compounds. Other constituents are also oxidized. The gas stream is then passed through a wet scrubber to remove the mercuric compounds and oxidized constituents.
Mendelsohn, Marshall H. (Downers Grove, IL); Huang, Hann-Sheng (Darien, IL)
A method for the removal of elemental mercury from a gas stream
Mendelsohn, Marshall H.; Huang, Hann-Sheng
This patent relates to an improved method for the decontamination of plutonium. The process consists broadly in an improvement in a method for recovering plutonium from radioactive uranium fission products in aqueous solutions by decontamination steps including byproduct carrier precipitation comprising the step of introducing a preformed aqueous slurry of a hydroxide of a metal of group IV B into any aqueous acidic solution which contains the plutonium in the hexavalent state, radioactive uranium fission products contaminant and a by-product carrier precipitate and separating the metal hydroxide and by-product precipitate from the solution. The process of this invention is especially useful in the separation of plutonium from radioactive zirconium and columbium fission products.
Sutton, J.B.
Top Quark Mass Measurement in the Lepton + Jets Channel Using a Matrix Element Method and in situ Jet Energy Calibration
A precision measurement of the top quark mass m_t is obtained using a sample of ttbar events from ppbar collisions at the Fermilab Tevatron with the CDF II detector. Selected events require an electron or muon, large missing transverse energy, and exactly four high-energy jets, at least one of which is tagged as coming from a b quark. A likelihood is calculated using a matrix element method with quasi-Monte Carlo integration taking into account finite detector resolution and jet mass effects. The event likelihood is a function of m_t and a parameter DJES to calibrate the jet energy scale /in situ/. Using a total of 1087 events, a value of m_t = 173.0 +/- 1.2 GeV/c^2 is measured.
T. Aaltonen et al.
Low energy collective modes of deformed superfluid nuclei within the finite amplitude method
Background: The major challenge for nuclear theory is to describe and predict global properties and collective modes of atomic nuclei. Of particular interest is the response of the nucleus to a time-dependent external field that impacts the low-energy multipole and beta-decay strength. Purpose: We propose a method to compute low-lying collective modes in deformed nuclei within the finite amplitude method (FAM) based on the quasiparticle random-phase approximation (QRPA). By using the analytic property of the response function, we find the QRPA amplitudes by computing the residua of the FAM amplitudes by means of a contour integration around the QRPA poles in a complex frequency plane. Methods: We use the superfluid nuclear density functional theory with Skyrme energy density functionals, FAM-QRPA approach, and the conventional matrix formulation of the QRPA (MQRPA). Results: We demonstrate that the complex-energy FAM-QRPA method reproduces low-lying collective states obtained within the conventional matrix formulation of the QRPA theory. Illustrative calculations are performed for the isoscalar monopole strength in deformed 24Mg and for low-lying K = 0 quadrupole vibrational modes of deformed Yb and Er isotopes. Conclusions: The proposed FAM-QRPA approach allows one to efficiently calculate low-lying collective modes in spherical and deformed nuclei throughout the entire nuclear landscape, including shape-vibrational excitations, pairing vibrational modes, and beta-decay rates.
Nobuo Hinohara; Markus Kortelainen; Witold Nazarewicz
An algorithm for transferring 2D arbitrary hp-refined finite element axially symmetric meshes to three dimensions
of Petroleum Engineering, The University of Texas in Austin (3) Institute for Computational Engineering and Sciences, ICES, The University of Texas in Austin Abstract The 2D and 3D fully automatic hp adaptive Finite is solved on the coarse and on the fine mesh. The energy norm (H1 Sobolev space norm) difference between
Torres-Verd├Łn, Carlos
Coupling methodology of 1D finite difference and 3D finite volume CFD codes based on the Method of Characteristics
This paper describes the methodology followed to perform a co-simulation between 1D (OpenWAM) and 3D (FLUENT) CFD codes. The Method of Characteristics (MoC) has been chosen to transfer the information between the two domains by properly updating the ... Keywords: 1D modeling, 1D-3D coupling, CFD simulation, Co-simulation, Method of Characteristics, User defined function
J. Galindo; A. Tiseira; P. Fajardo; R. Navarro
Finite element formulation of the self-excited forces for time-domain assessment of wind-induced dynamic response and flutter stability limit of cable-supported bridges
In this paper it is shown how unsteady self-excited aerodynamic forces modelled by rational functions can be introduced into a finite element beam model, using the nodal displacement degrees of freedom of the element to characterize the aeroelastic system. ... Keywords: Aerodynamic derivatives, Cable-supported bridges, FEM, Flutter, Wind loading
Ole žIseth; Anders R÷Nnquist; Ragnar Sigbj÷Rnsson
The robust estimation method for a finite mixture of Poisson mixed-effect models
When analyzing clustered count data derived from several latent subpopulations, the finite mixture of the Poisson mixed-effect model is an immediate strategy to model the underlying heterogeneity. Within the generalized linear mixed model framework, ... Keywords: Finite mixture, Minimum Hellinger distance, Non-parametric maximum likelihood, Robustness
Liming Xiang; Kelvin K. W. Yau; Andy H. Lee
A Sequential Element Rejection and Admission (SERA) method for compliant mechanisms design
A Sequential Element Rejection and Admission (SERA) method to design compliant mechanisms with topology optimization techniques is presented in this work. This procedure allows material to flow between two different material models: `real' and `virtual'. ... Keywords: Compliant mechanisms, Parameter study, SERA method, Topology optimization
Cristina Alonso, Osvaldo M. Querin, Rubķn Ansola
The use of Ixaru's method in locating the poles of the S-matrix in strictly finite-range potentials
Energies of the S-matrix poles are calculated by solving the radial Schroedinger equation numerically by using Ixaru's CPM(2) method. The trajectories of the poles in the complex wave number plane are determined for two nuclear potentials that are zero beyond finite distances. These are the Woods-Saxon form with cutoff and the Salamon-Vertse potential, which goes to zero smoothly at a finite distance. Properties of the trajectories are analyzed for real and complex values of the depths of the corresponding potentials.
Vertse, Tamas; Lovas, R. G.; Racz, A.; Salamon, P. [University of Debrecen, Faculty of Informatics, Chair of Applied Mathematics and Probability, Debrecen, Hungary and Institute of Nuclear Research of the Hungarian Academy of Sciences, Debrecen (Hungary); Institute of Nuclear Research of the Hungarian Academy of Sciences, Debrecen (Hungary); University of Debrecen, Faculty of Informatics, Chair of Applied Mathematics and Probability, Debrecen (Hungary); Institute of Nuclear Research of the Hungarian Academy of Sciences, Debrecen (Hungary)
A Drift-Diffusion-Reaction Model for Excitonic Photovoltaic Bilayers: Asymptotic Analysis and A 2-D HDG Finite-Element Scheme
We present and discuss a mathematical model for the operation of bilayer organic photovoltaic devices. Our model couples drift-diffusion-recombination equations for the charge carriers (specifically, electrons and holes) with a reaction-diffusion equation for the excitons/ polaron pairs and Poisson's equation for the self-consistent electrostatic potential. The material difference (i.e. the HOMO/LUMO gap) of the two organic substrates forming the bilayer device are included as a work-function potential. Firstly, we perform an asymptotic analysis of the scaled one-dimensional stationary state system i) with focus on the dynamics on the interface and ii) with the goal of simplifying the bulk dynamics away for the interface. Secondly, we present a twodimensional Hybrid Discontinuous Galerkin Finite Element numerical scheme which is very well suited to resolve i) the material changes ii) the resulting strong variation over the interface and iii) the necessary upwinding in the discretization of drift-diffusion equ...
Brinkman, Daniel; Markowich, Peter A; Wolfram, Marie-Therese
Two-dimensional nonlinear finite element analysis of well damage due to reservoir compaction, well-to-well interactions, and localization on weak layers
In this paper the authors present the results of a coupled nonlinear finite element geomechanics model for reservoir compaction and well-to-well interactions for the high-porosity, low strength diatomite reservoirs of the Belridge field near Bakersfield, California. They show that well damage and failures can occur under the action of two distinct mechanisms: shear deformations induced by pore compaction, and subsidence, and shear deformations due to well-to-well interactions during production or water injection. They show such casting damage or failure can be localized to weak layers that slide or slip under shear due to subsidence. The magnitude of shear displacements and surface subsidence agree with field observations.
Hilbert, L.B. Jr. [Univ. of California, Berkeley, CA (United States); Fredrich, J.T. [Sandia National Labs., Albuquerque, NM (United States); Bruno, M.S. [Terralog Technologies USA, Inc., Arcadia, CA (United States); Deitrick, G.L.; Rouffignac, E.P. de [Shell Exploration and Production Co., Houston, TX (United States)
Finite element simulation for ultraviolet excimer laser processing of patterned Si/SiGe/Si(100) heterostructures
Ultraviolet (UV) Excimer laser assisted processing is an alternative strategy for producing patterned silicon germanium heterostructures. We numerically analyzed the effects caused by pulsed 193 Excimer laser radiation impinging on patterned amorphous hydrogenated silicon (a-Si:H) and germanium (a-Ge:H) bilayers deposited on a crystalline silicon substrate [Si(100)]. The proposed two dimensional axisymmetric numerical model allowed us to estimate the temperature and concentration gradients caused by the laser induced rapid melting and solidification processes. Energy density dependence of maximum melting depth and melting time evolution as well as three dimensional temperature and element distribution have been simulated and compared with experimentally obtained results.
Conde, J. C.; Chiussi, S.; Gontad, F.; Gonzalez, P. [Dpto. Fisica Aplicada, University of Vigo, E-36310 Vigo (Spain); Martin, E. [Dpto. Mecanica, Maquinas, Motores Termicos y Fluidos, University of Vigo, E-36310 Vigo (Spain); Serra, C. [CACTI, University of Vigo, E-36310 Vigo (Spain)
Adaptive fully implicit multi-scale finite-volume method for multi-phase flow and transport in heterogeneous porous media
We describe a sequential fully implicit (SFI) multi-scale finite volume (MSFV) algorithm for nonlinear multi-phase flow and transport in heterogeneous porous media. The method extends the recently developed multiscale approach, which is based on an IMPES ... Keywords: coupled flow and transport, finite-volume, heterogeneous porous media, immiscible multi-phase flow, multiscale methods, numerical simulation
voronoi_fe_meshing_rev_2.doc 12:48 10.08.01 1/19 AUTOMATIC FINITE ELEMENT MESHING
element method, stress corrosion cracking # Corresponding author. Tel. +49/7247/82 4155 Fax +49 and propagation in creep [6], [7], thermal fatigue [8] and intergranular stress-corrosion [9]. The applications like aggregates of grains in polycrystals, patterns of intergranular cracks and composites. Solution
Cizelj, Leon
Serpentine: Finite Difference Methods for Wave Propagation in Second Order Formulation
Wave propagation phenomena are important in many DOE applications such as nuclear explosion monitoring, geophysical exploration, estimating ground motion hazards and damage due to earthquakes, non-destructive testing, underground facilities detection, and acoustic noise propagation. There are also future applications that would benefit from simulating wave propagation, such as geothermal energy applications and monitoring sites for carbon storage via seismic reflection techniques. In acoustics and seismology, it is of great interest to increase the frequency bandwidth in simulations. In seismic exploration, greater frequency resolution enables shorter wave lengths to be included in the simulations, allowing for better resolution in the seismic imaging. In nuclear explosion monitoring, higher frequency seismic waves are essential for accurate discrimination between explosions and earthquakes. When simulating earthquake induced motion of large structures, such as nuclear power plants or dams, increased frequency resolution is essential for realistic damage predictions. Another example is simulations of micro-seismic activity near geothermal energy plants. Here, hydro-fracturing induces many small earthquakes and the time scale of each event is proportional to the square root of the moment magnitude. As a result, the motion is dominated by higher frequencies for smaller seismic events. The above wave propagation problems are all governed by systems of hyperbolic partial differential equations in second order differential form, i.e., they contain second order partial derivatives of the dependent variables. Our general research theme in this project has been to develop numerical methods that directly discretize the wave equations in second order differential form. The obvious advantage of working with hyperbolic systems in second order differential form, as opposed to rewriting them as first order hyperbolic systems, is that the number of differential equations in the second order system is significantly smaller. Another issue with re-writing a second order system into first order form is that compatibility conditions often must be imposed on the first order form. These (Saint-Venant) conditions ensure that the solution of the first order system also satisfies the original second order system. However, such conditions can be difficult to enforce on the discretized equations, without introducing additional modeling errors. This project has previously developed robust and memory efficient algorithms for wave propagation including effects of curved boundaries, heterogeneous isotropic, and viscoelastic materials. Partially supported by internal funding from Lawrence Livermore National Laboratory, many of these methods have been implemented in the open source software WPP, which is geared towards 3-D seismic wave propagation applications. This code has shown excellent scaling on up to 32,768 processors and has enabled seismic wave calculations with up to 26 Billion grid points. TheWPP calculations have resulted in several publications in the field of computational seismology, e.g.. All of our current methods are second order accurate in both space and time. The benefits of higher order accurate schemes for wave propagation have been known for a long time, but have mostly been developed for first order hyperbolic systems. For second order hyperbolic systems, it has not been known how to make finite difference schemes stable with free surface boundary conditions, heterogeneous material properties, and curvilinear coordinates. The importance of higher order accurate methods is not necessarily to make the numerical solution more accurate, but to reduce the computational cost for obtaining a solution within an acceptable error tolerance. This is because the accuracy in the solution can always be improved by reducing the grid size h. However, in practice, the available computational resources might not be large enough to solve the problem with a low order method.
Petersson, N A; Sjogreen, B
A piezoelectric solid shell element based on a mixed variational formulation for geometrically linear and nonlinear applications
The paper is focused on a piezoelectric solid shell finite element formulation. A geometrically nonlinear theory allows large deformations and includes stability problems. The formulation is based on a variational principle of the Hu-Washizu type including ... Keywords: Finite element method, Mixed formulation, Piezoelectricity, Smart structures, Solid shell element
Sven Klinkel; Werner Wagner
Comparison of the calculated neutron noise using finite differences and the Analytical Nodal Method
noise in the frequency domain via the reactor transfer function using 2-group diffusion theory in 2 Viktor Larsson , Christophe Demazi├©re Chalmers University of Technology, Department of Nuclear: Neutron noise ANM Finite differences 2-group theory a b s t r a c t In this paper, a comparison
Demazi├©re, Christophe
SetExp: a method of transformation of timed automata into finite state automata
Real-time discrete event systems are discrete event systems with timing constraints, and can be modeled by timed automata. The latter are convenient for modeling real-time discrete event systems. However, due to their infinite state space, timed automata ... Keywords: Discrete event systems, Finite state automata, Modeling, Real-time system, Timed automata
Lucien Ouedraogo; Ahmed Khoumsi; Mustapha Nourelfath
Wind Turbine Post-Stall Airfoil Performance Characteristics Guidelines for Blade-Element Momentum Methods: Preprint
The objective of this study was to provide post-stall airfoil data input guidelines for the prediction of peak and post-peak rotor power when using blade-element momentum theory. A steady-state data set from the Unsteady Aerodynamic Experiment (UAE) rotor test was used to provide guidelines for the development of a global post-stall method for the prediction of post-stall 3-D airfoil characteristics to be used with 2-D airfoil data. Based on these UAE data, methods to emulate the 3-D aerodynamics in the post-stall region were explored. Also suggested are experimental tests needed to better understand the 3-D flow physics and to quantify needed theory or empirical factors for a global post-stall approach to support blade-element momentum methods.
Tangler, J. L.; Kocurek, J. D.
On the generalized eigenvalue method for energies and matrix elements in lattice field theory
We discuss the generalized eigenvalue problem for computing energies and matrix elements in lattice gauge theory, including effective theories such as HQET. It is analyzed how the extracted effective energies and matrix elements converge when the time separations are made large. This suggests a particularly efficient application of the method for which we can prove that corrections vanish asymptotically as $\\exp(-(E_{N+1}-E_n) t)$. The gap $E_{N+1}-E_n$ can be made large by increasing the number $N$ of interpolating fields in the correlation matrix. We also show how excited state matrix elements can be extracted such that contaminations from all other states disappear exponentially in time. As a demonstration we present numerical results for the extraction of ground state and excited B-meson masses and decay constants in static approximation and to order $1/m_b$ in HQET.
Benoit Blossier; Michele Della Morte; Georg von Hippel; Tereza Mendes; Rainer Sommer
An improved method for extracting matrix elements from lattice three-point functions
The extraction of matrix elements from baryon three-point functions is complicated by the fact that the signal-to-noise drops rapidly as a function of time. Using a previously discussed method to improve the signal-to-noise for lattice two-point functions, we use this technique to do so for lattice three-point functions, using electromagnetic form factors for the nucleon and Delta as an example.
C. Aubin, K. Orginos
Rolling Element Bearing Stiffness Matrix Determination (Presentation)
Current theoretical bearing models differ in their stiffness estimates because of different model assumptions. In this study, a finite element/contact mechanics model is developed for rolling element bearings with the focus of obtaining accurate bearing stiffness for a wide range of bearing types and parameters. A combined surface integral and finite element method is used to solve for the contact mechanics between the rolling elements and races. This model captures the time-dependent characteristics of the bearing contact due to the orbital motion of the rolling elements. A numerical method is developed to determine the full bearing stiffness matrix corresponding to two radial, one axial, and two angular coordinates; the rotation about the shaft axis is free by design. This proposed stiffness determination method is validated against experiments in the literature and compared to existing analytical models and widely used advanced computational methods. The fully-populated stiffness matrix demonstrates the coupling between bearing radial, axial, and tilting bearing deflections.
Guo, Y.; Parker, R.
DOLFIN: Automated finite element computing
of examples are presented to demonstrate the use of the library in application code. Categories and Subject Descriptors: G.4 [Mathematical software]: Algorithm Design, Effi- ciency, User Interfaces; G.1.8 [Numerical analysis]: Partial differential equations... backend. DOLFIN relies on a form compiler for generation of the problem-specific code. The form compiler generates code conforming to the UFC (Unified Form-assembly Code) interface, either at compile-time or run- time, and the generated code is called...
Logg, Anders; Wells, G N
DOLFIN: Automated Finite Element Computing
of examples are presented to demonstrate the use of the library in application code. Categories and Subject Descriptors: G.4 [Mathematical software]: Algorithm Design, Effi- ciency, User Interfaces; G.1.8 [Numerical analysis]: Partial differential equations... for generation of the problem-specific code. The form compiler generates code conforming to the UFC (Unified Form-assembly Code) interface, either at compile-time or run-time, and the generated code is called during assembly by DOLFIN. A small interface layer...
Object-Oriented Finite Elements
... OOF2 is one program, but can be loaded modularly ... Floating ? Require a field to have a particular profile, allow profile to relax ? Force ...
CAM-SE: A scalable spectral element dynamical core for the Community Atmosphere Model
The Community Atmosphere Model (CAM) version 5 includes a spectral element dynamical core option from NCAR's High-Order Method Modeling Environment. It is a continuous Galerkin spectral finite-element method designed for fully unstructured quadrilateral ... Keywords: atmospheric modeling, dynamical core, global circulation model, parallel scalability, spectral elements
John M. Dennis; Jim Edwards; Katherine J. Evans; Oksana Guba; Peter H. Lauritzen; Arthur A. Mirin; Amik St-Cyr; Mark A. Taylor; Patrick H. Worley
Top Quark Mass Measurement in the Lepton + Jets Channel Using a Matrix Element Method and \\textit{in situ} Jet Energy Calibration
A precision measurement of the top quark mass m{sub t} is obtained using a sample of t{bar t} events from p{bar p} collisions at the Fermilab Tevatron with the CDF II detector. Selected events require an electron or muon, large missing transverse energy, and exactly four high-energy jets, at least one of which is tagged as coming from a b quark. A likelihood is calculated using a matrix element method with quasi-Monte Carlo integration taking into account finite detector resolution and jet mass effects. The event likelihood is a function of m{sub t} and a parameter {Delta}{sub JES} used to calibrate the jet energy scale in situ. Using a total of 1087 events, a value of m{sub t} = 173.0 {+-} 1.2 GeV/c{sup 2} is measured.
Aaltonen, T.; /Helsinki Inst. of Phys.; Alvarez Gonzalez, B.; /Cantabria Inst. of Phys.; Amerio, S.; /INFN, Padua; Amidei, D.; /Michigan U.; Anastassov, A.; /Northwestern U.; Annovi, A.; /Frascati; Antos, J.; /Comenius U.; Apollinari, G.; /Fermilab; Appel, J.A.; /Fermilab; Apresyan, A.; /Purdue U.; Arisawa, T.; /Waseda U. /Dubna, JINR
Convergency analysis of the high-order mimetic finite difference method
We prove second-order convergence of the conservative variable and its flux in the high-order MFD method. The convergence results are proved for unstructured polyhedral meshes and full tensor diffusion coefficients. For the case of non-constant coefficients, we also develop a new family of high-order MFD methods. Theoretical result are confirmed through numerical experiments.
Lipnikov, Konstantin [Los Alamos National Laboratory; Veiga Da Beirao, L [UNIV DEGLI STUDI; Manzini, G [NON LANL
Solution of Nonlinear Finite Difference Ocean Models by Optimization Methods with Sensitivity and Observational Strategy Analysis
Dynamical models driven by ōobservedö forcing fields (e.g., the wind) have a true solution uncertainty owing to observational errors in the driving. This uncertainty is usually hidden from view because conventional numerical methods do not easily ...
Jens Schr÷ter; Carl Wunsch
Accelerated staggered coupling schemes for problems of thermoelasticity at finite strains
This paper introduces a fully implicit partitioned coupling scheme for problems of thermoelasticity at finite strains utilizing the p-version of the finite element method. The mechanical and the thermal fields are partitioned into symmetric subproblems ... Keywords: Convergence acceleration, Partitioned coupling schemes, Thermoelasticity, Time adaptivity
Patrick Erbts; Alexander D³Ster
Calculation of large ion densities under HVdc transmission lines by the finite difference method
A calculation method for large ion densities (charged aerosols) under HVdc transmission lines was developed considering both the charging mechanism of aerosols by small ions and the drifting process by wind. Large ion densities calculated by this method agreed well with the ones measured under the Shiobara HVdc test line on the lateral profiles at ground level up to about 70m downwind from the line. Measured values decreased more quickly than calculated ones farther downwind from the line. Considering the effect of point discharge from ground cover (earth corona) improved the agreement in the farther downwind region.
Suda, Tomotaka; Sunaga, Yoshitaka [Central Research Institute of Electrical Power Industry, Komae, Tokyo (Japan)
Method of locating a leaking fuel element in a fast breeder power reactor
Leaking fuel elements in a fast reactor are identified by measuring the ratio of .sup.134 Xe to .sup.133 Xe in the reactor cover gas following detection of a fuel element leak, this ratio being indicative of the power and burnup of the failed fuel element. This procedure can be used to identify leaking fuel elements in a power breeder reactor while continuing operation of the reactor since the ratio measured is that of the gases stored in the plenum of the failed fuel element. Thus, use of a cleanup system for the cover gas makes it possible to identify sequentially a multiplicity of leaking fuel elements without shutting the reactor down.
Honekamp, John R. (Downers Grove, IL); Fryer, Richard M. (Idaho Falls, ID)
Methods for manufacturing porous nuclear fuel elements for high-temperature gas-cooled nuclear reactors
Methods for manufacturing porous nuclear fuel elements for use in advanced high temperature gas-cooled nuclear reactors (HTGR's). Advanced uranium bi-carbide, uranium tri-carbide and uranium carbonitride nuclear fuels can be used. These fuels have high melting temperatures, high thermal conductivity, and high resistance to erosion by hot hydrogen gas. Tri-carbide fuels, such as (U,Zr,Nb)C, can be fabricated using chemical vapor infiltration (CVI) to simultaneously deposit each of the three separate carbides, e.g., UC, ZrC, and NbC in a single CVI step. By using CVI, a thin coating of nuclear fuel may be deposited inside of a highly porous skeletal structure made, for example, of reticulated vitreous carbon foam.
Youchison, Dennis L. (Albuquerque, NM); Williams, Brian E. (Pocoima, CA); Benander, Robert E. (Pacoima, CA)
Shock capturing with PDE-based artificial viscosity for an adaptive, higher-order discontinuous Galerkin finite element method
The accurate simulation of supersonic and hypersonic flows is well suited to higher-order (p > 1), adaptive computational fluid dynamics (CFD). Since these cases involve flow velocities greater than the speed of sound, an ...
Barter, Garrett E. (Garrett Ehud), 1979-
Shock Capturing with PDE-Based Artificial Viscosity for an Adaptive, Higher-Order Discontinuous Galerkin Finite Element Method
Barter, Garrett Ehud
Two-dimensional finite element method simulation of a four-quadrant transducer prototype machine considering skewed slots
A four-quadrant transducer (4QT) electric machine is an integrated electric machine used for hybrid electric vehicles. In this article a 4QT prototype machine that is radially integrated by two permanent-magnet synchronous machines is analyzed. Skewed slots are adopted for the two machines
Ping Zheng; Peter Thelin; Erik Nordlund; Chandur Sadarangani
Hybridized enriched space-time finite element method for analysis of thin-walled structures immersed in generalized Newtonian fluids
The paper addresses the numerical treatment of a specific class of fluid-structure interaction problems: flow-immersed thin structures undergoing considerable motion and deformation. The simultaneous solution procedure uses a mixed-hybrid velocity-based ... Keywords: Embedded thin structure, Enriched space-time approximation, Fluid-structure interaction, Strong coupling
A. Zilian; H. Netuzhylov
A self-adaptive goal-oriented hp finite element method with electromagnetic applications. Part II: Electrodynamics
for Computational Engineering and Sciences (ICES), The University of Texas at Austin, Austin, TX 78712, United States b Department of Petroleum and Geosystems Engineering, The University of Texas at Austin, Austin singularities. The goal-oriented refinement strategy is an extension of a fully automatic, energy-norm based, hp
Detection of specific atomic elements in a substance and particularly the applicability to well logging are discussed. The principal novelty resides in the determination of several of the auxiliary energy peaks in addition to the main energy peak of the gamma-ray energy spectrum of a substance and comparison of such peaks to the spectrum of the specific atomic element being tested for. thus resulting in identification of same. The invention facilitates the identification of specific elements even when in the presence of other elements having similar gamma energy spectra as to the main energy peaks.
Putman, J.L.
GOMA 6.0 : a full-Newton finite element program for free and moving boundary problems with coupled fluid/solid momentum, energy, mass, and chemical species transport : user%3CU%2B2019%3Es guide.
Goma 6.0 is a finite element program which excels in analyses of multiphysical processes, particularly those involving the major branches of mechanics (viz. fluid/solid mechanics, energy transport and chemical species transport). Goma is based on a full-Newton-coupled algorithm which allows for simultaneous solution of the governing principles, making the code ideally suited for problems involving closely coupled bulk mechanics and interfacial phenomena. Example applications include, but are not limited to, coating and polymer processing flows, super-alloy processing, welding/soldering, electrochemical processes, and solid-network or solution film drying. This document serves as a user's guide and reference.
Schunk, Peter Randall; Rao, Rekha Ranjana; Chen, Ken Shuang; Labreche, Duane A.; Sun, Amy Cha-Tien; Hopkins, Matthew Morgan; Moffat, Harry K.; Roach, Robert Allen; Hopkins, Polly L.; Notz, Patrick K.; Roberts, Scott Alan; Sackinger, Philip A.; Subia, Samuel Ramirez; Wilkes, Edward Dean; Baer, Thomas A.; Noble, David R.; Secor, Robert B. [3M Engineering Systems and Technology, St. Paul, MN
A Deformable Object Tracking Algorithm Based on the Boundary Element Method that is Robust to Occlusions and Spurious Edges
The manipulation of deformable objects is an important problem in robotics and arises in many applications including biomanipulation, microassembly, and robotic surgery. For some applications, the robotic manipulator itself may be deformable. Vision-based ... Keywords: Artificial neural networks, Boundary element method, Deformable object tracking, Edge detection, Robust statistics, Robust tracking
Michael A. Greminger; Bradley J. Nelson
Integrating complementarity into the 2D displacement discontinuity boundary element method to model faults and fractures with frictional contact properties
We present a two-dimensional displacement discontinuity method (DDM) in combination with a complementarity solver to simulate quasi-static slip on cracks as models for faults and fractures in an otherwise homogeneous, isotropic, linear elastic material. ... Keywords: Boundary element model, Complementarity, Friction, Frictional strength
Elizabeth Ritz; Ovunc Mutlu; David D. Pollard
Apparatus and method for heterodyne-generated two-dimensional detector array using a single element detector
Apparatus and method for heterodyne-generated, two-dimensional detector array using a single detector. Synthetic-array heterodyne detection, permits a single-element optical detector to behave as though it were divided into an array of separate heterodyne detector elements. A fifteen-element synthetic array has successfully been experimentally realized on a single-element detector, permitting all of the array elements to be read out continuously and in parallel from one electrical connection. A CO.sub.2 laser and a single-element HgCdTe photodiode are employed. A different heterodyne local oscillator frequency is incident upon the spatially resolvable regions of the detector surface. Thus, different regions are mapped to different heterodyne beat frequencies. One can determine where the photons were incident on the detector surface even though a single electrical connection to the detector is used. This also prevents the destructive interference that occurs when multiple speckles are imaged (similar to spatial diversity), In coherent LIDAR this permits a larger field of view. An acoustooptic modulator generates the local oscillator frequencies and can achieve adequate spatial separation of optical frequencies of the order of a megahertz apart.
Strauss, Charlie E. (Santa Fe, NM)
Apparatus and method are disclosed for heterodyne-generated, two-dimensional detector array using a single detector. Synthetic-array heterodyne detection, permits a single-element optical detector to behave as though it were divided into an array of separate heterodyne detector elements. A fifteen-element synthetic array has successfully been experimentally realized on a single-element detector, permitting all of the array elements to be read out continuously and in parallel from one electrical connection. A CO{sub 2} laser and a single-element HgCdTe photodiode are employed. A different heterodyne local oscillator frequency is incident upon the spatially resolvable regions of the detector surface. Thus, different regions are mapped to different heterodyne beat frequencies. One can determine where the photons were incident on the detector surface even though a single electrical connection to the detector is used. This also prevents the destructive interference that occurs when multiple speckles are imaged (similar to spatial diversity), In coherent LIDAR this permits a larger field of view. An acoustooptic modulator generates the local oscillator frequencies and can achieve adequate spatial separation of optical frequencies of the order of a megahertz apart. 4 figs.
Strauss, C.E.
The Adaptive Spectral Element Method and Comparisons with More Traditional Formulations for Ocean Modeling
Triangular spectral elements offer high accuracy in complex geometries, but solving the related matrix problem can be cumbersome and time consuming. In restricted applications, recent developments have led to a family of discontinuous Galerkin ...
Frķdķric Dupont; Charles A. Lin
This patent relates to ceramic composition, and to neutronic reactor fuel elements formed therefrom. These ceramic elements have high density and excellent strength characteristics and are formed by conventional ceramic casting and sintering at a temperature of about 2700 deg F in a nitrogen atmosphere. The composition consists of silicon carbide, silicon, uranium oxide and a very small percentage of molybdenum. Compositions containing molybdenum are markedly stronger than those lacking this ingredient.
Duckworth, W.H.
A fourth-order symplectic finite-difference time-domain (FDTD) method for light scattering and a 3D Monte Carlo code for radiative transfer in scattering systems
When the finite-difference time-domain (FDTD) method is applied to light scattering computations, the far fields can be obtained by either a volume integration method, or a surface integration method. In the first study, we investigate the errors associated with the two near-to-far field transform methods. For a scatterer with a small refractive index, the surface approach is more accurate than its volume counterpart for computing the phase functions and extinction efficiencies; however, the volume integral approach is more accurate for computing other scattering matrix elements. If a large refractive index is involved, the results computed from the volume integration method become less accurate, whereas the surface method still retains the same order of accuracy as in the situation of a small refractive index. In my second study, a fourth order symplectic FDTD method is applied to the problem of light scattering by small particles. The total-field/ scattered-field (TF/SF) technique is generalized for providing the incident wave source conditions in the symplectic FDTD (SFDTD) scheme. Numerical examples demonstrate that the fourthorder symplectic FDTD scheme substantially improves the precision of the near field calculation. The major shortcoming of the fourth-order SFDTD scheme is that it requires more computer CPU time than the conventional second-order FDTD scheme if the same grid size is used. My third study is on multiple scattering theory. We develop a 3D Monte Carlo code for the solving vector radiative transfer equation, which is the equation governing the radiation field in a multiple scattering medium. The impulse-response relation for a plane-parallel scattering medium is studied using our 3D Monte Carlo code. For a collimated light beam source, the angular radiance distribution has a dark region as the detector moves away from the incident point. The dark region is gradually filled as multiple scattering increases. We have also studied the effects of the finite size of clouds. Extending the finite size of clouds to infinite layers leads to underestimating the reflected radiance in the multiple scattering region, especially for scattering angles around 90 degrees. The results have important applications in the field of remote sensing.
Zhai, Pengwang
Preprint of the paper "A General Formulation based on the Boundary Element Method for the Analysis
cost) to the analysis of large grounding systems in electrical substations. In this paper we present a new Boundary Element formulation for substation grounding systems embedded in layered soils of Grounded Instalations in Layered Soils" I. Colominas, F. Navarrina, J. Aneiros, M. Casteleiro (1998) En
A Well-balanced Finite Volume-Augmented Lagrangian Method for an Integrated Herschel-Bulkley Model
We are interested in the derivation of an integrated Herschel-Bulkley model for shallow flows, as well as in the design of a numerical algorithm to solve the resulting equations. The goal is to simulate the evolution of thin sheet of viscoplastic materials ... Keywords: Avalanche, Finite volume, Herschel-Bulkley, Variational inequality, Viscous shallow water, Well balanced
C. Acary-Robert; E. D. Fernßndez-Nieto; G. Narbona-Reina; P. Vigneaux
Forecasting the Surface Weather Elements with a Local Dynamical-Adaptation Method Using a Variational Technique
A simple method of dynamical adaptation of a mesoscale model has been tested to produce meteorological parameters locally adapted at meteorological stations. This method is based on the use of a soil model in association with a surface boundary-...
Christine Marais; Luc Musson-Genon
Finite density phase transition of QCD with N{sub f}=4 and N{sub f}=2 using canonical ensemble method
In a progress toward searching for the QCD critical point, we study the finite density phase transition of N{sub f}=4 and 2 lattice QCD at finite temperature with the canonical ensemble approach. We develop a winding number expansion method to accurately project out the particle number from the fermion determinant which greatly extends the applicable range of baryon number sectors to make the study feasible. Our lattice simulation was carried out with the clover fermions and improved gauge action. For a given temperature, we calculate the baryon-chemical potential from the canonical approach to look for the mixed phase as a signal for the first-order phase transition. In the case of N{sub f}=4, we observe an 'S-shape' structure in the chemical potential-density plane due to the surface tension of the mixed phase in a finite volume which is a signal for the first-order phase transition. We use the Maxwell construction to determine the phase boundaries for three temperatures below T{sub c}. The intersecting point of the two extrapolated boundaries turns out to be at the expected first-order transition point at T{sub c} with {mu}=0. This serves as a check for our method of identifying the critical point. We also studied the N{sub f}=2 case, but do not see a signal of the mixed phase for temperature as low as 0.83T{sub c}.
Li Anyi [Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506 (United States) and Department of Physics, Duke University, Durham, North Carolina 27708 (United States); Alexandru, Andrei [Physics Department, George Washington University, Washington, D.C. 20052 (United States); Liu, Keh-Fei [Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506 (United States); Meng Xiangfei [Department of Physics, Nankai University, Tianjin 300071 (China); National Supercomputing Center, Tianjin 300457 (China)
Method of pressurizing and stabilizing rock by periodic and repeated injections of a settable fluid of finite gel strength
A finite region of overpressure can be created in solid underground formations by the periodic injection of a fluid that has finite gel strength that subsequently, after each injection, partially sets--i.e., equivalently becomes a very much stronger gel. A region of overpressure is a region in which the static, locked in pressure is larger than what was there before. A region of overpressure can be used to prevent a roof of a tunnel from caving by adding compressive stresses in the roof. A sequence of regions of overpressure can be used to lift an arch or dome underground, squeeze off water or gas flows, stabilize dams, foundations, large underground rooms, etc. In general, the stress or pressure distribution in rock can be altered and engineered in a fashion that is more advantageous than what would have been the case without overstressing. 3 figs.
Colgate, S.A.
A novel method for fatigue testing of MEMS devices containing movable elements
In this paper we present an electronic circuit for position or capacitance estimation of MEMS electrostatic actuators based on a switched capacitor technique. The circuit uses a capacitive divider configuration composed by a fixed capacitor and the variable capacitance of the electrostatic actuator for generating a signal that is a function of the input voltage and capacitive ratio. The proposed circuit can be used to actuate and to sense position of an electrostatic MEMS actuator without extra sensing elements. This approach is compatible with the requirements of most analog feedback systems and the circuit topology of pulsed digital oscillators (PDO).
Szucs, Z
Method of manufacturing iron aluminide by thermomechanical processing of elemental powders
A powder metallurgical process of preparing iron aluminide useful as electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 20 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1 % rare earth metal, .ltoreq.1% oxygen, and/or .ltoreq.3% Cu. The process includes forming a mixture of aluminum powder and iron powder, shaping the mixture into an article such as by cold rolling the mixture into a sheet, and sintering the article at a temperature sufficient to react the iron and aluminum powders and form iron aluminide. The sintering can be followed by hot or cold rolling to reduce porosity created during the sintering step and optional annealing steps in a vacuum or inert atmosphere.
Deevi, Seetharama C. (Midlothian, VA); Lilly, Jr., A. Clifton (Chesterfield, VA); Sikka, Vinod K. (Oak Ridge, TN); Hajaligol, Mohammed R. (Richmond, VA)
Thermodynamic evaluation of the CdTe deposition by an elemental co-evaporation method under isothermal transport conditions
Thermodynamic potential diagrams were used to predict the conditions for depositing cadmium telluride thin films from two independent elemental sources, Cd and Te, while keeping sources and substrate at the same temperature. The potential diagrams also allowed the evaluation of the influence of gaseous contaminants, such as oxygen, on the formed condensed phases. The method may be applied to the deposition of other compounds as long as their vapor pressures are much smaller than the vapor pressures of the constituent elements. The thermodynamic calculation suggested that the film may be deposited under total pressure of 10-4 mbar and at temperatures as low as 450 deg. C. This total pressure is easily achieved by a mechanical pump and the low temperature range allows the use of low cost glass substrates. The preliminary results showed that the films deposited under the conditions predicted by the thermodynamic calculations were uniform and crystalline, as confirmed by scanning electron microscopy and X-ray diffraction.
Ribeiro, M.C.R. [Pontificia Universidade Catolica do Rio de Janeiro, Departamento de Ciencia dos Materiais e Metalurgia, Rua Marques de Sao Vicente, 225 Gavea, 22453-900 Rio de Janeiro, RJ (Brazil)]. E-mail: firstname.lastname@example.com; Cruz, L.R. [Instituto Militar de Engenharia, Departamento de Engenharia Mecanica e de Materiais, Praca General Tiburcio, 80 Urca, 22290-270 Rio de Janeiro, RJ (Brazil); Avillez, R.R. de [Pontificia Universidade Catolica do Rio de Janeiro, Departamento de Ciencia dos Materiais e Metalurgia, Rua Marques de Sao Vicente, 225 Gavea, 22453-900 Rio de Janeiro, RJ (Brazil)
Highly Accurate Schemes for PDE-Based Morphology with General Convex Structuring Elements
The two fundamental operations in morphological image processing are dilation and erosion. These processes are defined via structuring elements. It is of practical interest to consider a variety of structuring element shapes. The realisation of dilation/erosion ... Keywords: Dilation, Erosion, Finite difference method, Flux-corrected transport scheme, Mathematical morphology, Partial differential equation
Michael Breu?; Joachim Weickert
Manufacturing Methods and Properties of Powder-Based Parts with ...
... of the main incentives of the Collaborative Research Centre 653 ōGentelligent ... A Finite Element-Phase Field Study of Solid State Phase Transformation: ... A Novel Method for Joining of Stainless Steel (SS-316)through Microwave Energy.
Method for removing sulfur oxide from waste gases and recovering elemental sulfur
A continuous catalytic fused salt extraction process is described for removing sulfur oxides from gaseous streams. The gaseous stream is contacted with a molten potassium sulfate salt mixture having a dissolved catalyst to oxidize sulfur dioxide to sulfur trioxide and molten potassium normal sulfate to solvate the sulfur trioxide to remove the sulfur trioxide from the gaseous stream. A portion of the sulfur trioxide loaded salt mixture is then dissociated to produce sulfur trioxide gas and thereby regenerate potassium normal sulfate. The evolved sulfur trioxide is reacted with hydrogen sulfide as in a Claus reactor to produce elemental sulfur. The process may be advantageously used to clean waste stack gas from industrial plants, such as copper smelters, where a supply of hydrogen sulfide is readily available.
Moore, Raymond H. (Richland, WA)
Spectral element/smoothed profile method for turbulent flow simulations of waterjet propulsion systems
We have developed fast numerical algorithms [1] for flows with complex moving domains, e.g. propellers in free-space and impellers in waterjets, by combining the smoothed profile method (SPM, [2, 3, 4]) with the spectral ...
Luo, Xian
A measurement of the top quark mass with a matrix element method
The authors present a measurement of the mass of the top quark. The event sample is selected from proton-antiproton collisions, at 1.96 TeV center-of-mass energy, observed with the CDF detector at Fermilab's Tevatron. They consider a 318 pb{sup -1} dataset collected between March 2002 and August 2004. They select events that contain one energetic lepton, large missing transverse energy, exactly four energetic jets, and at least one displaced vertex b tag. The analysis uses leading-order t{bar t} and background matrix elements along with parameterized parton showering to construct event-by-event likelihoods as a function of top quark mass. From the 63 events observed with the 318 pb{sup -1} dataset they extract a top quark mass of 172.0 {+-} 2.6(stat) {+-} 3.3(syst) GeV/c{sup 2} from the joint likelihood. The mean expected statistical uncertainty is 3.2 GeV/c{sup 2} for m{sub t} = 178 GTeV/c{sup 2} and 3.1 GeV/c{sup 2} for m{sub t} = 172.5 GeV/c{sup 2}. The systematic error is dominated by the uncertainty of the jet energy scale.
Gibson, Adam Paul; /UC, Berkeley
It's Elemental - The Element Phosphorus
Silicon Silicon Previous Element (Silicon) The Periodic Table of Elements Next Element (Sulfur) Sulfur The Element Phosphorus [Click for Isotope Data] 15 P Phosphorus 30.973762 Atomic Number: 15 Atomic Weight: 30.973762 Melting Point: 317.30 K (44.15┬░C or 111.47┬░F) Boiling Point: 553.65 K (280.5┬░C or 536.9┬░F) Density: 1.82 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Non-metal Period Number: 3 Group Number: 15 Group Name: Pnictogen What's in a name? From the Greek word for light bearing, phosphoros. Say what? Phosphorus is pronounced as FOS-fer-es. History and Uses: In what is perhaps the most disgusting method of discovering an element, phosphorus was first isolated in 1669 by Hennig Brand, a German physician and alchemist, by boiling, filtering and otherwise processing as many as 60
Method of loading organic materials with group III plus lanthanide and actinide elements
Disclosed is a composition of matter comprising a tributyl phosphate complex of a group 3, lanthanide, actinide, or group 13 salt in an organic carrier and a method of making the complex. These materials are suitable for use in solid or liquid organic scintillators, as in x-ray absorption standards, x-ray fluorescence standards, and neutron detector calibration standards.
Bell, Zane W. (Oak Ridge, TN); Huei-Ho, Chuen (Oak Ridge, TN); Brown, Gilbert M. (Knoxville, TN); Hurlbut, Charles (Sweetwater, TX)
Application of discrete element method to the analysis of free-flow outlet of coal from high coals at underground coal mining
The mathematical model is developed on the basis of the Discrete Elements Method for investigation of processes of gravitational flow of the granular materials. The problem about free-flow outlet of coal from high coals in sublevel caving systems is ... Keywords: discrete element modeling, granular medium, numerical simulation, powered support, rock massif, underground coal mining
Vladimir I. Klishin; Sergey V. Klishin
Method for quantitative determination and separation of trace amounts of chemical elements in the presence of large quantities of other elements having the same atomic mass
Photoionization via autoionizing atomic levels combined with conventional mass spectroscopy provides a technique for quantitative analysis of trace quantities of chemical elements in the presence of much larger amounts of other elements with substantially the same atomic mass. Ytterbium samples smaller than 10 ng have been detected using an ArF* excimer laser which provides the atomic ions for a time-of-flight mass spectrometer. Elemental selectivity of greater than 5:1 with respect to lutetium impurity has been obtained. Autoionization via a single photon process permits greater photon utilization efficiency because of its greater absorption cross section than bound-free transitions, while maintaining sufficient spectroscopic structure to allow significant photoionization selectivity between different atomic species. Separation of atomic species from others of substantially the same atomic mass is also described.
Miller, C.M.; Nogar, N.S.
It's Elemental - The Element Copper
Nickel Nickel Previous Element (Nickel) The Periodic Table of Elements Next Element (Zinc) Zinc The Element Copper [Click for Isotope Data] 29 Cu Copper 63.546 Atomic Number: 29 Atomic Weight: 63.546 Melting Point: 1357.77 K (1084.62┬░C or 1984.32┬░F) Boiling Point: 2835 K (2562┬░C or 4644┬░F) Density: 8.933 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 4 Group Number: 11 Group Name: none What's in a name? From the Latin word cuprum, which means "from the island of Cyprus." Say what? Copper is pronounced as KOP-er. History and Uses: Archaeological evidence suggests that people have been using copper for at least 11,000 years. Relatively easy to mine and refine, people discovered methods for extracting copper from its ores at least 7,000 years ago. The
It's Elemental - The Element Hafnium
Lutetium Lutetium Previous Element (Lutetium) The Periodic Table of Elements Next Element (Tantalum) Tantalum The Element Hafnium [Click for Isotope Data] 72 Hf Hafnium 178.49 Atomic Number: 72 Atomic Weight: 178.49 Melting Point: 2506 K (2233┬░C or 4051┬░F) Boiling Point: 4876 K (4603┬░C or 8317┬░F) Density: 13.3 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 6 Group Number: 4 Group Name: none What's in a name? From the Latin word for the city of Copenhagen, Hafnia. Say what? Hafnium is pronounced as HAF-neeem. History and Uses: Hafnium was discovered by Dirk Coster, a Danish chemist, and Charles de Hevesy, a Hungarian chemist, in 1923. They used a method known as X-ray spectroscopy to study the arrangement of the outer electrons of atoms in
Analytical Method of Torque Calculation for Interior Permanent Magnet Synchronous Machines
method for performing the output torque calculations of an interior permanent magnet synchronous motor circuit, inductance, permanent magnet machine, synchronous motors, torque. I. NOMENCLATURE BFE brushless field excitation IPMSM interior permanent magnet synchronous motor FEA finite element analysis mmf
Tolbert, Leon M.
OOF: Finite Element Analysis of Microstructures
... (This menu is called ``tee'' because it acts like the Unix tee command, which is used to save a copy of data in a pipe.) Menus, Functions, Variables. ...
NIST Home Page. ... The image may be a scanned micrograph of a composite material, a satellite image of the earth, the result of a computer ...
... oriented with a globe, with the origin at the center of the earth and -axis ... Contents /* Send mail to the OOF Team *//* Go to the OOF Home Page */. ...
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... This button opens another identical Function Window with identical arguments. Having two function windows allows you to repeatedly execute ...
... with the word ``OOF'' prominently in the upper left hand corner. ... nx and ny of about 20 are about right if you ... Use the mouse or the tab key to set more ...
Estimating local thickness for finite element analysis
Within the development of motor vehicles, crash safety is one of the most important attributes. To comply with the ever increasing requirements of shorter cycle times and costs reduction, car manufacturers keep intensifying the use of virtual development ... Keywords: FEA mesh, automotive crash simulations, ray tracing, structural modelling, thickness estimation
VŌnio Ferreira; LuĒs Paulo Santos; Ricardo Simoes; Markus Franzen; Omar O. Ghouati
Finite Element Modeling of Pharmaceutical Powder Compaction ...
First Principles Modeling of Shape Memory Alloy Magnetic Refrigeration Materials ... of Lithium Battery Materials LiMPO4 (M = Mn, Fe, Co, and Ni): A Comparative ... Forming-Crush Simulation Optimization Using Internal State Variable Model.
Neutron Diffraction And Finite Element Simulations.
For example, this was done by Bucezek at al. [18] on a cylinder made of brass. As the materials are different, their results cannot be applied for the present study,Ā...
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Using Finite Element Analysis in Failure Analysis
Symposium, Charles R. Morin Memorial Symposium on Failure Analysis and ... Tools for Failure Event Database Management and Probability Risk Analysis forĀ...
Accuracy Analysis of a Spectral Element Atmospheric Model Using a Fully Implicit Solution Framework
A fully implicit (FI) time integration method has been implemented into a spectral finite-element shallow-water equation model on a sphere, and it is compared to existing fully explicit leapfrog and semi-implicit methods for a suite of test ...
Katherine J. Evans; Mark A. Taylor; John B. Drake
A Design Procedure for Sonotrodes Based on Dynamic Finite ...
... Based on Dynamic Finite Elements and Laser Triangulation Measurements ... experience acquired on the field about the behaviour of ultrasonic systems inĀ...
It's Elemental - The Element Actinium
Radium Previous Element (Radium) The Periodic Table of Elements Next Element (Thorium) Thorium The Element Actinium Click for Isotope Data 89 Ac Actinium 227 Atomic Number: 89...
It's Elemental - The Element Fermium
Einsteinium Previous Element (Einsteinium) The Periodic Table of Elements Next Element (Mendelevium) Mendelevium The Element Fermium Click for Isotope Data 100 Fm Fermium 257...
It's Elemental - The Element Neptunium
Uranium Previous Element (Uranium) The Periodic Table of Elements Next Element (Plutonium) Plutonium The Element Neptunium Click for Isotope Data 93 Np Neptunium 237 Atomic...
It's Elemental - The Element Ruthenium
Technetium Previous Element (Technetium) The Periodic Table of Elements Next Element (Rhodium) Rhodium The Element Ruthenium Click for Isotope Data 44 Ru Ruthenium 101.07 Atomic...
A Measurement of the Top Quark Mass with the D0 Detector at s**(1/2) = 1.96-TeV using the Matrix Element Method
Using a data set of 158 and 169 pb{sup -1} of D0 Run-II data in the electron and muon plus jets channel, respectively, the top quark mass has been measured using the Matrix Element Method. The method and its implementation are described. Its performance is studied in Monte Carlo using ensemble tests and the method is applied to the Moriond 2004 data set.
Kroeninger, Kevin Alexander; /Bonn U.
Application of a Direct Inverse Data Assimilation Method to the M2 Tide on the Newfoundland and Southern Labrador Shelves
The barotropic M2 tide over the Newfoundland and southern Labrador Shelves and adjacent deep ocean is studied using a linear harmonic finite-element model and a newly developed direct inverse method for data assimilation. The dataset includes ...
Zhigang Xu; Ross M. Hendry; John W. Loder
A non-hybrid method for the PDF equations of turbulent flows on unstructured grids
In probability density function (PDF) methods of turbulent flows, the joint PDF of several flow variables is computed by numerically integrating a system of stochastic differential equations for Lagrangian particles. A set of parallel algorithms is proposed ... Keywords: Finite element method, Langevin equation, Monte-Carlo method, Particle tracking, Particle-in-cell method, Probability density function method, Scalar dispersion, Turbulent flow, Unstructured grids
J. Bakosi; P. Franzese; Z. Boybeyi
Root-cause analysis of the better performance of the coarse-mesh finite-difference method for CANDU-type reactors
Recent assessment results indicate that the coarse-mesh finite-difference method (FDM) gives consistently smaller percent differences in channel powers than the fine-mesh FDM when compared to the reference MCNP solution for CANDU-type reactors. However, there is an impression that the fine-mesh FDM should always give more accurate results than the coarse-mesh FDM in theory. To answer the question if the better performance of the coarse-mesh FDM for CANDU-type reactors was just a coincidence (cancellation of errors) or caused by the use of heavy water or the use of lattice-homogenized cross sections for the cluster fuel geometry in the diffusion calculation, three benchmark problems were set up with three different fuel lattices: CANDU, HWR and PWR. These benchmark problems were then used to analyze the root cause of the better performance of the coarse-mesh FDM for CANDU-type reactors. The analyses confirm that the better performance of the coarse-mesh FDM for CANDU-type reactors is mainly caused by the use of lattice-homogenized cross sections for the sub-meshes of the cluster fuel geometry in the diffusion calculation. Based on the analyses, it is recommended to use 2 x 2 coarse-mesh FDM to analyze CANDU-type reactors when lattice-homogenized cross sections are used in the core analysis. (authors)
Shen, W. [Candu Energy Inc., 2285 Speakman Dr., Mississauga, ON L5B 1K (Canada)
Higher order FE-FV method on unstructured grids for transport and two-phase flow with variable viscosity in heterogeneous porous media
This paper presents higher order methods for the numerical modeling of two-phase flow with simultaneous transport and adsorption of viscosifying species within the individual phases in permeable porous media. The numerical scheme presented addresses ... Keywords: Finite-element finite volume method, Flow in porous media, Monotone upwind scheme for conservation laws, Slope limiter, Transport, Unstructured grid
K. S. Schmid; S. Geiger; K. S. Sorbie
A measurement of the top quark mass in 1.96 TeV proton-antiproton collisions using a novel matrix element method
A measurement of the top quark mass in t{bar t} {yields} l + jets candidate events, obtained from p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron using the CDF II detector, is presented. The measurement approach is that of a matrix element method. For each candidate event, a two dimensional likelihood is calculated in the top pole mass and a constant scale factor, 'JES', where JES multiplies the input particle jet momenta and is designed to account for the systematic uncertainty of the jet momentum reconstruction. As with all matrix elements techniques, the method involves an integration using the Standard Model matrix element for tt production and decay. however, the technique presented is unique in that the matrix element is modified to compensate for kinematic assumptions which are made to reduce computation time. Background events are dealt with through use of an event observable which distinguishes signal from background, as well as through a cut on the value of an event's maximum likelihood. Results are based on a 955 pb{sup -1} data sample, using events with a high-p{sub T} lepton and exactly four high-energy jets, at least one of which is tagged as coming from a b quark; 149 events pass all the selection requirements. They find M{sub meas} = 169.8 {+-} 2.3(stat.) {+-} 1.4(syst.) GeV/c{sup 2}.
Freeman, John C.; /LBL, Berkeley
A Measurement of the Top Quark Mass in 1.96 TeV Proton-Antiproton Collisions Using a Novel Matrix Element Method
A measurement of the top quark mass in t{bar t} {yields} l + jets candidate events, obtained from p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron using the CDF II detector, is presented. The measurement approach is that of a matrix element method. For each candidate event, a two dimensional likelihood is calculated in the top pole mass and a constant scale factor, 'JES', where JES multiplies the input particle jet momenta and is designed to account for the systematic uncertainty of the jet momentum reconstruction. As with all matrix element techniques, the method involves an integration using the Standard Model matrix element for t{bar t} production and decay. However, the technique presented is unique in that the matrix element is modified to compensate for kinematic assumptions which are made to reduce computation time. Background events are dealt with through use of an event observable which distinguishes signal from background, as well as through a cut on the value of an event's maximum likelihood. Results are based on a 955 pb{sup -1} data sample, using events with a high-p{sub T} lepton and exactly four high-energy jets, at least one of which is tagged as coming from a b quark; 149 events pass all the selection requirements. They find M{sub meas} = 169.8 {+-} 2.3(stat.) {+-} 1.4(syst.) GeV/c{sup 2}.
CDF Collaboration; Freeman, John; Freeman, John
The Use of Finite-Volume Methods for Atmospheric Advection of Trace Species. Part I: Test of Various Formulations in a General Circulation Model
In the context of advection of trace species by 3D atmospheric flows, a comparative test of a hierarchy of finite volume transport schemes initially derived by B. Van Leer is presented. Those schemes are conservative by construction and Van Leer ...
Frķdķric Hourdin; Alexandre Armengaud
Finite Temperature Aging Holography
We construct the gravity background which describes the dual field theory with aging invariance. We choose the decay modes of the bulk scalar field in the internal spectator direction to obtain the dissipative behavior of the boundary correlation functions of the dual scalar fields. In particular, the two-time correlation function at zero temperature has the characteristic features of the aging system: power law decay, broken time translation and dynamical scaling. We also construct the black hole backgrounds with asymptotic aging invariance. We extensively study characteristic behavior of the finite temperature two-point correlation function via analytic and numerical methods.
Seungjoon Hyun; Jaehoon Jeong; Bom Soo Kim
SK 1 of finite abelian groups. I
This paper lays the theoretical foundation for calculating the Whitehead groups of finite abelian ... The White- head group of a group G is ... computational methods; the results of all computations as well as the ad- ditional methods leading toĀ...
It's Elemental - The Element Lithium
(Helium) The Periodic Table of Elements Next Element (Beryllium) Beryllium The Element Lithium Click for Isotope Data 3 Li Lithium 6.941 Atomic Number: 3 Atomic Weight: 6.941...
It's Elemental - The Element Plutonium
Next Element (Americium) Americium The Element Plutonium Click for Isotope Data 94 Pu Plutonium 244 Atomic Number: 94 Atomic Weight: 244 Melting Point: 913 K (640C or...
Spectral resolution for a five-element, filtered, x-ray detector array using the method of Backus and Gilbert
The generalized method of Backus and Gilbert (BG) is described and applied to the inverse problem of obtaining the spectrum from a five-channel, filtered array of x-ray detectors. This diagnostic is routinely fielded on the Z facility at Sandia National Laboratories to study soft x-ray photons ({approx}100-2300 eV), emitted by high density Z-pinch plasmas. The BG method defines spectral resolution limits on the system of response functions that are in good agreement with a classical unfold method, based on a histogram representation of the source spectrum. The resolution so defined is independent of the source spectrum. For noise-free, simulated data the BG approximating function is also in reasonable agreement with the source spectrum (150 eV blackbody) and the unfolded spectrum. This function may be used as an initial trial function for iterative methods or a regularization model.(c) 2000 American Institute of Physics. (c)
Fehl, D. L. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1196 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185-1196 (United States); Biggs, F. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1196 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185-1196 (United States); Chandler, G. A. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1196 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185-1196 (United States); Stygar, W. A. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1196 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185-1196 (United States)
Spectral Resolution for Five-Element, Filtered, X-Ray Detector (XRD) Arrays Using the Methods of Backus and Gilbert
The generalized method of Backus and Gilbert (BG) is described and applied to the inverse problem of obtaining spectra from a 5-channel, filtered array of x-ray detectors (XRD's). This diagnostic is routinely fielded on the Z facility at Sandia National Laboratories to study soft x-ray photons ({le}2300 eV), emitted by high density Z-pinch plasmas. The BG method defines spectral resolution limits on the system of response functions that are in good agreement with the unfold method currently in use. The resolution so defined is independent of the source spectrum. For noise-free, simulated data the BG approximating function is also in reasonable agreement with the source spectrum (150 eV black-body) and the unfold. This function may be used as an initial trial function for iterative methods or a regularization model.
A B-Spline-Based Colocation Method to Approximate the Solutions to the Equations of Fluid Dynamics
The potential of a B-spline collocation method for numerically solving the equations of fluid dynamics is discussed. It is known that B-splines can resolve curves with drastically fewer data than can their standard shape function counterparts. This feature promises to allow much faster numerical simulations of fluid flow than standard finite volume/finite element methods without sacrificing accuracy. An example channel flow problem is solved using the method.
Johnson, Richard Wayne; Landon, Mark Dee
The potential of a B-spline collocation method for numerically solving the equations of fluid dynamics is discussed. It is known that B-splines can resolve complex curves with drastically fewer data than can their standard shape function counterparts. This feature promises to allow much faster numerical simulations of fluid flow than standard finite volume/finite element methods without sacrificing accuracy. An example channel flow problem is solved using the method.
M. D. Landon; R. W. Johnson
Groundwater prospecting for sandstone-type uranium deposits: the merits of mineral-solution equilibria versus single element tracer methods. Volume II
This report presents the results of further research on the groundwater geochemistry of 96 well waters in two uraniferous aquifers in Texas and Wyoming, and is a continuation of the work presented by Chatham et al. (1981). In this study variations in concentrations of U, As, Mo, Se and V were compared with the saturation state of the groundwater with respect to mineral phases of these elements known or expected to occur in each area. The non-radiogenic trace elements exhibited strong redox dependence consistent with thermodynamic predictions, but their variations did not pinpoint existing uranium ore bodies, because of a shift in groundwater flow patterns since the time of ore emplacement. Saturation levels of trace element minerals such as realgar, native Se, and molybdenite showed broad anomalies around the ore-bearing areas, similar to patterns found for U minerals by Langmuir and Chatham (1980), and Chatham et al. (1981). The radiogenic elements Ra and Rn showed significant anomalies directly within the ore zones. Helium anomalies were displaced in the direction of groundwater flow, but by their magnitude and areal extent provided strong evidence for the existence of nearby uranium accumulations. Uranium isotope ratios showed no systematic variations within the two aquifers studied. Saturation maps for kaolinite, illite, montmorillonite and the zeolites analcime and clinoptilolite provided 1 to 2 km anomalies around the ore at the Texas site. Saturation values for the gangue minerals pyrite and calcite defined the redox interface and often suggested the position of probable uranium mineralization. When properly used, the groundwater geochemical concepts for exploration can accurately pinpoint uranium mineralization at a fraction of the cost of conventional methods that involve test drilling and geophysical and core logging.
Wanty, R.B.; Langmuir, D.; Chatham, J.R.
Inverse Transformation Optics and Reflection Analysis for Two-Dimensional Finite Embedded Coordinate Transformation
Inverse transformation optics is introduced, and used to calculate the boundary reflection of a two-dimensional (2D) finite embedded coordinate transformation which is discontinuous at the boundary. For an electromagnetic excitation of particular polarization, many pairs of original medium (in a virtual space) and transformation function can give exactly the same anisotropic medium through a conventional procedure of transformation optics. Non-uniqueness of these pairs is then exploited for the analysis and calculation of the boundary reflection. The reflection at the boundary of the anisotropic transformation medium (associated with vacuum in the virtual space) is converted to the simple reflection between two isotropic media in a virtual space by a new transformation continuous at the boundary. A necessary condition for reflectionless boundary of finite embedded coordinate transformation is found as a special case. The theory is verified numerically with the finite element method.
Zhang, Pu; He, Sailing
optimizing the forging of critical aircraft parts by the use of finite ...
requires the usage of finite element simulations to ensure a proper .... Due to the typical forging temperature and the low stacking fault energy of the alloys,Ā...
It's Elemental - Element Concentration Game
symbols of the elements. After you have had time to study the cards, the computer will flip them over and ask you to find a particular element. Click on the card that contains...
The synthetic elements
Prior to 1940, the heaviest element known was uranium, discovered in 1789. Since that time the elements 93 through 109 have been synthesized and identified and the elements 43, 61, 85, and 87 which were missing form the periodic tables of the 1930's have been discovered. The techniques and problems involved in these discoveries and the placement of the transuranium elements in the periodic table will be discussed. The production and positive identification of elements heavier than Md (Z=101), which have very short half-lives and can only be produced an atom-at-a-time, are very difficult and there have been controversies concerning their discovery. Some of the new methods which have been developed and used in these studies will be described. The prospects for production of still heavier elements will be considered.
Hoffman, D.C.
Trace element emissions
The Energy & Environmental Research Center (EERC) is carrying out an investigation that will provide methods to predict the fate of selected trace elements in integrated gasification combined cycle (IGCC) and integrated gasification fuel cell (IGFC) systems to aid in the development of methods to control the emission of trace elements determined to be air toxics. The goal of this project is to identify the effects of critical chemical and physical transformations associated with trace element behavior in IGCC and IGFC systems. The trace elements included in this project are arsenic, chromium, cadmium, mercury, nickel, selenium, and lead. The research seeks to identify and fill, experimentally and/or theoretically, data gaps that currently exist on the fate and composition of trace elements. The specific objectives are to (1) review the existing literature to identify the type and quantity of trace elements from coal gasification systems, (2) perform laboratory-scale experimentation and computer modeling to enable prediction of trace element emissions, and (3) identify methods to control trace element emissions.
Benson, S.A.; Erickson, T.A.; Steadman, E.N.; Zygarlicke, C.J.; Hauserman, W.B.; Hassett, D.J.
Finite volume schemes for Boussinesq type equations
Finite volume schemes are commonly used to construct approximate solutions to conservation laws. In this study we extend the framework of the finite volume methods to dispersive water wave models, in particular to Boussinesq type systems. We focus mainly on the application of the method to bidirectional nonlinear, dispersive wave propagation in one space dimension. Special emphasis is given to important nonlinear phenomena such as solitary waves interactions.
It's Elemental - The Element Sulfur
Phosphorus Phosphorus Previous Element (Phosphorus) The Periodic Table of Elements Next Element (Chlorine) Chlorine The Element Sulfur [Click for Isotope Data] 16 S Sulfur 32.065 Atomic Number: 16 Atomic Weight: 32.065 Melting Point: 388.36 K (115.21┬░C or 239.38┬░F) Boiling Point: 717.75 K (444.60┬░C or 832.28┬░F) Density: 2.067 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Non-metal Period Number: 3 Group Number: 16 Group Name: Chalcogen What's in a name? From the Sanskrit word sulvere and the Latin word sulphurium. Say what? Sulfur is pronounced as SUL-fer. History and Uses: Sulfur, the tenth most abundant element in the universe, has been known since ancient times. Sometime around 1777, Antoine Lavoisier convinced the rest of the scientific community that sulfur was an element. Sulfur is a
It's Elemental - The Element Magnesium
Sodium Sodium Previous Element (Sodium) The Periodic Table of Elements Next Element (Aluminum) Aluminum The Element Magnesium [Click for Isotope Data] 12 Mg Magnesium 24.3050 Atomic Number: 12 Atomic Weight: 24.3050 Melting Point: 923 K (650┬░C or 1202┬░F) Boiling Point: 1363 K (1090┬░C or 1994┬░F) Density: 1.74 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 3 Group Number: 2 Group Name: Alkaline Earth Metal What's in a name? For Magnesia, a district in the region of Thessaly, Greece. Say what? Magnesium is pronounced as mag-NEE-zhi-em. History and Uses: Although it is the eighth most abundant element in the universe and the seventh most abundant element in the earth's crust, magnesium is never found free in nature. Magnesium was first isolated by Sir Humphry Davy, an
It's Elemental - The Element Europium
Samarium Samarium Previous Element (Samarium) The Periodic Table of Elements Next Element (Gadolinium) Gadolinium The Element Europium [Click for Isotope Data] 63 Eu Europium 151.964 Atomic Number: 63 Atomic Weight: 151.964 Melting Point: 1095 K (822┬░C or 1512┬░F) Boiling Point: 1802 K (1529┬░C or 2784┬░F) Density: 5.24 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 6 Group Number: none Group Name: Lanthanide What's in a name? Named after the continent of Europe. Say what? Europium is pronounced as yoo-RO-pee-em. History and Uses: Europium was discovered by Eug├©ne-Antole Demar├¦ay, a French chemist, in 1896. Demar├¦ay suspected that samples of a recently discovered element, samarium, were contaminated with an unknown element. He was able to produce
It's Elemental - The Element Potassium
Argon Argon Previous Element (Argon) The Periodic Table of Elements Next Element (Calcium) Calcium The Element Potassium [Click for Isotope Data] 19 K Potassium 39.0983 Atomic Number: 19 Atomic Weight: 39.0983 Melting Point: 336.53 K (63.38┬░C or 146.08┬░F) Boiling Point: 1032 K (759┬░C or 1398┬░F) Density: 0.89 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 4 Group Number: 1 Group Name: Alkali Metal What's in a name? From the English word potash. Potassium's chemical symbol comes from the Latin word for alkali, kalium. Say what? Potassium is pronounced as poh-TASS-ee-em. History and Uses: Although potassium is the eighth most abundant element on earth and comprises about 2.1% of the earth's crust, it is a very reactive element
An integrated method for material properties characterization based on pulsed laser generated surface acoustic waves
A novel integrated method enabling the study of nano-structured materials is presented, which is based on the imaging and monitoring of the spatiotemporal evolution of short-pulse-laser-generated Surface Acoustic Waves (SAWs). The method combines a 3D ... Keywords: Dynamic laser interferometry, Finite Elements, Nano-acoustics, Nanostructures
Yannis Orphanos, Vasilis Dimitriou, Evaggelos Kaselouris, Efthimios Bakarezos, Nikolaos Vainos, Michael Tatarakis, Nektarios A. Papadogiannis
An optimization-based approach to enforcing mass conservation in level set methods
This paper presents a new conservative level set method for numerical simulation of evolving interfaces. A PDE-constrained optimization problem is formulated and solved in an iterative fashion. The proposed optimal control procedure constrains the level ... Keywords: Evolving interfaces, Finite elements, Level set methods, Mass conservation, PDE-constrained optimization, Transport equations
Dmitri Kuzmin
Increasing the Locality of Iterative Methods and Its Application to the Simulation of Semiconductor Devices
Irregular codes are present in many scientific applications, such as finite element simulations. In these simulations the solution of large sparse linear equation systems is required, which are often solved using iterative methods. The main kernel of ... Keywords: data locality, irregular codes, iterative methods, reordering techniques, semiconductor devices simulation
J.C. Pichel; D.B. Heras; J.C. Cabaleiro; A.J. GarcĒa-Loureiro; F.F. Rivera
A consistent and stabilized continuous/discontinuous Galerkin method for fourth-order incompressible flow problems
This paper presents a new consistent and stabilized finite-element formulation for fourth-order incompressible flow problems. The formulation is based on the C^0-interior penalty method, the Galerkin least-square (GLS) scheme, which assures that the ... Keywords: Discontinuous Galerkin methods, Fourth-order problems, GLS stability, Second gradient
A. G. B. Cruz; E. G. Dutra Do Carmo; F. P. Duda
It's Elemental - Isotopes of the Element Protactinium
Thorium Previous Element (Thorium) The Periodic Table of Elements Next Element (Uranium) Uranium Isotopes of the Element Protactinium Click for Main Data Most of the isotope data...
It's Elemental - Isotopes of the Element Neptunium
Uranium Previous Element (Uranium) The Periodic Table of Elements Next Element (Plutonium) Plutonium Isotopes of the Element Neptunium Click for Main Data Most of the isotope...
It's Elemental - Isotopes of the Element Nobelium
Mendelevium Previous Element (Mendelevium) The Periodic Table of Elements Next Element (Lawrencium) Lawrencium Isotopes of the Element Nobelium Click for Main Data Most of the...
It's Elemental - Isotopes of the Element Fermium
Einsteinium Previous Element (Einsteinium) The Periodic Table of Elements Next Element (Mendelevium) Mendelevium Isotopes of the Element Fermium Click for Main Data Most of the...
It's Elemental - Isotopes of the Element Ruthenium
Technetium Previous Element (Technetium) The Periodic Table of Elements Next Element (Rhodium) Rhodium Isotopes of the Element Ruthenium Click for Main Data Most of the isotope...
It's Elemental - Isotopes of the Element Molybdenum
Niobium Previous Element (Niobium) The Periodic Table of Elements Next Element (Technetium) Technetium Isotopes of the Element Molybdenum Click for Main Data Most of the isotope...
It's Elemental - Isotopes of the Element Sulfur
Phosphorus Previous Element (Phosphorus) The Periodic Table of Elements Next Element (Chlorine) Chlorine Isotopes of the Element Sulfur Click for Main Data Most of the isotope...
It's Elemental - Isotopes of the Element Argon
Chlorine Previous Element (Chlorine) The Periodic Table of Elements Next Element (Potassium) Potassium Isotopes of the Element Argon Click for Main Data Most of the isotope data...
Modeling Nuclear Pasta and the Transition to Uniform Nuclear Matter with the 3D Skyrme-Hartree-Fock Method at Finite Temperature I: Core-Collapse Supernovae
The first results of a new three-dimensional, finite temperature Skyrme-Hartree-Fock+BCS study of the properties of inhomogeneous nuclear matter at densities and temperatures leading to the transition to uniform nuclear matter are presented. Calculations are carried out in a cubic box representing a unit cell of the locally periodic structure of the matter. A constraint is placed on the two independent components of the quadrupole moment of the neutron density in order to investigate the dependence of the total energy-density of matter on the geometry of the nuclear structure in the unit cell. This approach allows self-consistent modeling of effects such as (i) neutron drip, resulting in a neutron gas external to the nuclear structure, (ii) shell effects of bound and unbound nucleons, (iii) the variety of exotic nuclear shapes that emerge, collectively termed `nuclear pasta' and (iv) the dissolution of these structures into uniform nuclear matter as density and/or temperature increase. In part I of this work ...
Stone, W G Newton J R
It's Elemental - The Element Cerium
Lanthanum Lanthanum Previous Element (Lanthanum) The Periodic Table of Elements Next Element (Praseodymium) Praseodymium The Element Cerium [Click for Isotope Data] 58 Ce Cerium 140.116 Atomic Number: 58 Atomic Weight: 140.116 Melting Point: 1071 K (798┬░C or 1468┬░F) Boiling Point: 3697 K (3424┬░C or 6195┬░F) Density: 6.770 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 6 Group Number: none Group Name: Lanthanide What's in a name? Named for the asteroid Ceres. Say what? Cerium is pronounced as SER-ee-em. History and Uses: Cerium was discovered by J├Čns Jacob Berzelius and Wilhelm von Hisinger, Swedish chemists, and independently by Martin Heinrich Klaproth, a German chemist, in 1803. Cerium is the most abundant of the rare earth elements
It's Elemental - The Element Indium
Cadmium Cadmium Previous Element (Cadmium) The Periodic Table of Elements Next Element (Tin) Tin The Element Indium [Click for Isotope Data] 49 In Indium 114.818 Atomic Number: 49 Atomic Weight: 114.818 Melting Point: 429.75 K (156.60┬░C or 313.88┬░F) Boiling Point: 2345 K (2072┬░C or 3762┬░F) Density: 7.31 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 5 Group Number: 13 Group Name: none What's in a name? Named after the bright indigo line in its spectrum. Say what? Indium is pronounced as IN-dee-em. History and Uses: Indium was discovered by the German chemists Ferdinand Reich and Hieronymus Theodor Richter in 1863. Reich and Richter had been looking for traces of the element thallium in samples of zinc ores. A brilliant indigo line in
It's Elemental - The Element Neon
Fluorine Fluorine Previous Element (Fluorine) The Periodic Table of Elements Next Element (Sodium) Sodium The Element Neon [Click for Isotope Data] 10 Ne Neon 20.1797 Atomic Number: 10 Atomic Weight: 20.1797 Melting Point: 24.56 K (-248.59┬░C or -415.46┬░F) Boiling Point: 27.07 K (-246.08┬░C or -410.94┬░F) Density: 0.0008999 grams per cubic centimeter Phase at Room Temperature: Gas Element Classification: Non-metal Period Number: 2 Group Number: 18 Group Name: Noble Gas What's in a name? From the Greek word for new, neos. Say what? Neon is pronounced as NEE-on. History and Uses: Neon was discovered by Sir William Ramsay, a Scottish chemist, and Morris M. Travers, an English chemist, shortly after their discovery of the element krypton in 1898. Like krypton, neon was discovered through the
It's Elemental - The Element Manganese
Chromium Chromium Previous Element (Chromium) The Periodic Table of Elements Next Element (Iron) Iron The Element Manganese [Click for Isotope Data] 25 Mn Manganese 54.938045 Atomic Number: 25 Atomic Weight: 54.938045 Melting Point: 1519 K (1246┬░C or 2275┬░F) Boiling Point: 2334 K (2061┬░C or 3742┬░F) Density: 7.3 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 4 Group Number: 7 Group Name: none What's in a name? From the Latin word for magnet, magnes. Say what? Manganese is pronounced as MAN-ge-nees. History and Uses: Proposed to be an element by Carl Wilhelm Scheele in 1774, manganese was discovered by Johan Gottlieb Gahn, a Swedish chemist, by heating the mineral pyrolusite (MnO2) in the presence of charcoal later that year.
It's Elemental - The Element Titanium
Scandium Scandium Previous Element (Scandium) The Periodic Table of Elements Next Element (Vanadium) Vanadium The Element Titanium [Click for Isotope Data] 22 Ti Titanium 47.867 Atomic Number: 22 Atomic Weight: 47.867 Melting Point: 1941 K (1668┬░C or 3034┬░F) Boiling Point: 3560 K (3287┬░C or 5949┬░F) Density: 4.5 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 4 Group Number: 4 Group Name: none What's in a name? From the Greek word Titans, the mythological "first sons of the Earth." Say what? Titanium is pronounced as tie-TAY-nee-em. History and Uses: Titanium was discovered in 1791 by the Reverend William Gregor, an English pastor. Pure titanium was first produced by Matthew A. Hunter, an American metallurgist, in 1910. Titanium is the ninth most abundant element in the
It's Elemental - The Element Nitrogen
Carbon Carbon Previous Element (Carbon) The Periodic Table of Elements Next Element (Oxygen) Oxygen The Element Nitrogen [Click for Isotope Data] 7 N Nitrogen 14.0067 Atomic Number: 7 Atomic Weight: 14.0067 Melting Point: 63.15 K (-210.00┬░C or -346.00┬░F) Boiling Point: 77.36 K (-195.79┬░C or -320.44┬░F) Density: 0.0012506 grams per cubic centimeter Phase at Room Temperature: Gas Element Classification: Non-metal Period Number: 2 Group Number: 15 Group Name: Pnictogen What's in a name? From the Greek words nitron and genes, which together mean "saltpetre forming." Say what? Nitrogen is pronounced as NYE-treh-gen. History and Uses: Nitrogen was discovered by the Scottish physician Daniel Rutherford in 1772. It is the fifth most abundant element in the universe and makes up
It's Elemental - The Element Sodium
Neon Neon Previous Element (Neon) The Periodic Table of Elements Next Element (Magnesium) Magnesium The Element Sodium [Click for Isotope Data] 11 Na Sodium 22.98976928 Atomic Number: 11 Atomic Weight: 22.98976928 Melting Point: 370.95 K (97.80┬░C or 208.04┬░F) Boiling Point: 1156 K (883┬░C or 1621┬░F) Density: 0.97 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 3 Group Number: 1 Group Name: Alkali Metal What's in a name? From the English word soda and from the Medieval Latin word sodanum, which means "headache remedy." Sodium's chemical symbol comes from the Latin word for sodium carbonate, natrium. Say what? Sodium is pronounced as SO-dee-em. History and Uses: Although sodium is the sixth most abundant element on earth and comprises
It's Elemental - The Element Francium
Radon Radon Previous Element (Radon) The Periodic Table of Elements Next Element (Radium) Radium The Element Francium [Click for Isotope Data] 87 Fr Francium 223 Atomic Number: 87 Atomic Weight: 223 Melting Point: 300 K (27┬░C or 81┬░F) Boiling Point: Unknown Density: Unknown Phase at Room Temperature: Solid Element Classification: Metal Period Number: 7 Group Number: 1 Group Name: Alkali Metal Radioactive What's in a name? Named for the country of France. Say what? Francium is pronounced as FRAN-see-em. History and Uses: Francium was discovered by Marguerite Catherine Perey, a French chemist, in 1939 while analyzing actinium's decay sequence. Although considered a natural element, scientists estimate that there is no more than one ounce of francium in the earth's crust at one time. Since there is so little
It's Elemental - The Element Technetium
Molybdenum Molybdenum Previous Element (Molybdenum) The Periodic Table of Elements Next Element (Ruthenium) Ruthenium The Element Technetium [Click for Isotope Data] 43 Tc Technetium 98 Atomic Number: 43 Atomic Weight: 98 Melting Point: 2430 K (2157┬░C or 3915┬░F) Boiling Point: 4538 K (4265┬░C or 7709┬░F) Density: 11 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 5 Group Number: 7 Group Name: none Radioactive and Artificially Produced What's in a name? From the Greek word for artificial, technetos. Say what? Technetium is pronounced as tek-NEE-she-em. History and Uses: Technetium was the first artificially produced element. It was isolated by Carlo Perrier and Emilio Segr├© in 1937. Technetium was created by bombarding molybdenum atoms with deuterons that had been accelerated by a
It's Elemental - The Element Cobalt
Iron Iron Previous Element (Iron) The Periodic Table of Elements Next Element (Nickel) Nickel The Element Cobalt [Click for Isotope Data] 27 Co Cobalt 58.933195 Atomic Number: 27 Atomic Weight: 58.933195 Melting Point: 1768 K (1495┬░C or 2723┬░F) Boiling Point: 3200 K (2927┬░C or 5301┬░F) Density: 8.86 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 4 Group Number: 9 Group Name: none What's in a name? From the German word for goblin or evil spirit, kobald and the Greek word for mine, cobalos. Say what? Cobalt is pronounced as KO-bolt. History and Uses: Cobalt was discovered by Georg Brandt, a Swedish chemist, in 1739. Brandt was attempting to prove that the ability of certain minerals to color glass blue was due to an unknown element and not to bismuth, as was commonly
It's Elemental - The Element Bromine
Selenium Selenium Previous Element (Selenium) The Periodic Table of Elements Next Element (Krypton) Krypton The Element Bromine [Click for Isotope Data] 35 Br Bromine 79.904 Atomic Number: 35 Atomic Weight: 79.904 Melting Point: 265.95 K (-7.2┬░C or 19.0┬░F) Boiling Point: 331.95 K (58.8┬░C or 137.8┬░F) Density: 3.11 grams per cubic centimeter Phase at Room Temperature: Liquid Element Classification: Non-metal Period Number: 4 Group Number: 17 Group Name: Halogen What's in a name? From the Greek word for stench, bromos. Say what? Bromine is pronounced as BRO-meen. History and Uses: The only nonmetallic element that is a liquid at normal room temperatures, bromine was produced by Carl L├Čwig, a young chemistry student, the summer before starting his freshman year at Heidelberg. When he showed his
It's Elemental - The Element Oxygen
Nitrogen Nitrogen Previous Element (Nitrogen) The Periodic Table of Elements Next Element (Fluorine) Fluorine The Element Oxygen [Click for Isotope Data] 8 O Oxygen 15.9994 Atomic Number: 8 Atomic Weight: 15.9994 Melting Point: 54.36 K (-218.79┬░C or -361.82┬░F) Boiling Point: 90.20 K (-182.95┬░C or -297.31┬░F) Density: 0.001429 grams per cubic centimeter Phase at Room Temperature: Gas Element Classification: Non-metal Period Number: 2 Group Number: 16 Group Name: Chalcogen What's in a name? From the greek words oxys and genes, which together mean "acid forming." Say what? Oxygen is pronounced as OK-si-jen. History and Uses: Oxygen had been produced by several chemists prior to its discovery in 1774, but they failed to recognize it as a distinct element. Joseph
It's Elemental - The Element Darmstadtium
Roentgenium The Element Darmstadtium Click for Isotope Data 110 Ds Darmstadtium 281 Atomic Number: 110 Atomic Weight: 281 Melting Point: Unknown Boiling Point: Unknown...
It's Elemental - The Element Berkelium
Californium The Element Berkelium Click for Isotope Data 97 Bk Berkelium 247 Atomic Number: 97 Atomic Weight: 247 Melting Point: 1323 K (1050C or 1922F) Boiling...
It's Elemental - The Element Tungsten
melting point of all metallic elements and is used to make filaments for incandescent light bulbs, fluorescent light bulbs and television tubes. Tungsten expands at nearly the...
The first results of a new three-dimensional, finite temperature Skyrme-Hartree-Fock+BCS study of the properties of inhomogeneous nuclear matter at densities and temperatures leading to the transition to uniform nuclear matter are presented. Calculations are carried out in a cubic box representing a unit cell of the locally periodic structure of the matter. A constraint is placed on the two independent components of the quadrupole moment of the neutron density in order to investigate the dependence of the total energy-density of matter on the geometry of the nuclear structure in the unit cell. This approach allows self-consistent modeling of effects such as (i) neutron drip, resulting in a neutron gas external to the nuclear structure, (ii) shell effects of bound and unbound nucleons, (iii) the variety of exotic nuclear shapes that emerge, collectively termed `nuclear pasta' and (iv) the dissolution of these structures into uniform nuclear matter as density and/or temperature increase. In part I of this work the calculation of the properties of inhomogeneous nuclear matter in the core collapse of massive stars is reported. Calculations are performed at baryon number densities of $n_{\\rm b}$ = 0.04 - 0.12 fm$^{\\rm -3}$, a proton fraction of $y_{\\rm p}=0.3$ and temperatures in the range 0 - 7.5 MeV. A wide variety of nuclear shapes are shown to emerge. It is suggested that thermodynamical properties change smoothly in the pasta regime up to the transition to uniform matter; at that transition, thermodynamic properties of the matter vary discontinuously.
W. G. Newton J. R. Stone
Efficient double beta decay nuclear matrix elements computations
We have developed a shell model code for the accurate computation of the two-body matrix elements of the transition operators involved in the neutrinoless double beta decay. This code features coupled cluster method short-range correlations with Jastrow-like functions, finite nucleon size effect and higher order nucleon current corrections. We present the results obtained for {sup 48}Ca and {sup 82}Se, then we compare them with other results in the literature. In the case of {sup 48}Ca, we also study the contributions of the included effects and find good agreement with other published results.
Neacsu, Andrei [Horia Hulubei Foundation (FHH) 407 Atomistilor, Horia Hulubei National Institute for Physics and Nuclear Engineering (IFIN-HH) 30 Reactorului, Magurele-Bucharest 077125 (Romania)
Vectorized Finite State Automata
We present a technique of finite state parsing based on vectorization and describe the application of this technique to a well-known problem of natural language processing, that of extracting relational information from English text. We define Vectorized Finite State Automata, the theoretical model behind the applied system, and discuss their significance.
Andrßs Kornai
This patent shows a method for detecting leaks in jacketed fuel elements. The element is placed in a sealed tank within a nuclear reactor, and, while the reactor operates, the element is sparged with gas. The gas is then led outside the reactor and monitored for radioactive Xe or Kr. (AEC)
Whitham, G.K.; Smith, R.R.
Bounded sequence testing from deterministic finite state machines
The W- andWp-methods are the basis for conformance testing from a deterministic finite state machine (DFSM) when the conformance relation considered is equivalence. However, many DFSM applications use only input sequences of limited length. In such cases, ... Keywords: Finite state machines, Specification-based testing, Test selection, W-method, Wp-method
Florentin Ipate
It's Elemental - The Element Gadolinium
Europium Europium Previous Element (Europium) The Periodic Table of Elements Next Element (Terbium) Terbium The Element Gadolinium [Click for Isotope Data] 64 Gd Gadolinium 157.25 Atomic Number: 64 Atomic Weight: 157.25 Melting Point: 1586 K (1313┬░C or 2395┬░F) Boiling Point: 3546 K (3273┬░C or 5923┬░F) Density: 7.90 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 6 Group Number: none Group Name: Lanthanide What's in a name? Named for the mineral gadolinite which was named after Johan Gadolin, a Finnish chemist. Say what? Gadolinium is pronounced as GAD-oh-LIN-ee-em. History and Uses: Spectroscopic evidence for the existence of gadolinium was first observed by the Swiss chemist Jean Charles Galissard de Marignac in the minerals
It's Elemental - The Element Mercury
Gold Gold Previous Element (Gold) The Periodic Table of Elements Next Element (Thallium) Thallium The Element Mercury [Click for Isotope Data] 80 Hg Mercury 200.59 Atomic Number: 80 Atomic Weight: 200.59 Melting Point: 234.32 K (-38.83┬░C or -37.89┬░F) Boiling Point: 629.88 K (356.73┬░C or 674.11┬░F) Density: 13.5336 grams per cubic centimeter Phase at Room Temperature: Liquid Element Classification: Metal Period Number: 6 Group Number: 12 Group Name: none What's in a name? Named after the planet Mercury. Mercury's chemical symbol comes from the Greek word hydrargyrum, which means "liquid silver." Say what? Mercury is pronounced as MER-kyoo-ree. History and Uses: Mercury was known to the ancient Chinese and Hindus and has been found in 3500 year old Egyptian tombs. Mercury is not usually found free in nature
It's Elemental - The Element Boron
Beryllium Beryllium Previous Element (Beryllium) The Periodic Table of Elements Next Element (Carbon) Carbon The Element Boron [Click for Isotope Data] 5 B Boron 10.811 Atomic Number: 5 Atomic Weight: 10.811 Melting Point: 2348 K (2075┬░C or 3767┬░F) Boiling Point: 4273 K (4000┬░C or 7232┬░F) Density: 2.37 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Semi-metal Period Number: 2 Group Number: 13 Group Name: none What's in a name? From the Arabic word Buraq and the Persian word Burah, which are both words for the material "borax." Say what? Boron is pronounced as BO-ron. History and Uses: Boron was discovered by Joseph-Louis Gay-Lussac and Louis-Jaques Th├®nard, French chemists, and independently by Sir Humphry Davy, an English chemist,
It's Elemental - The Element Thorium
Actinium Actinium Previous Element (Actinium) The Periodic Table of Elements Next Element (Protactinium) Protactinium The Element Thorium [Click for Isotope Data] 90 Th Thorium 232.03806 Atomic Number: 90 Atomic Weight: 232.03806 Melting Point: 2023 K (1750┬░C or 3182┬░F) Boiling Point: 5061 K (4788┬░C or 8650┬░F) Density: 11.72 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 7 Group Number: none Group Name: Actinide Radioactive What's in a name? Named for the Scandinavian god of war, Thor. Say what? Thorium is pronounced as THOR-ee-em or as THO-ree-em. History and Uses: Thorium was discovered by J├Čns Jacob Berzelius, a Swedish chemist, in 1828. He discovered it in a sample of a mineral that was given to him by the Reverend Has Morten Thrane Esmark, who suspected that it contained an
It's Elemental - The Element Chromium
Vanadium Vanadium Previous Element (Vanadium) The Periodic Table of Elements Next Element (Manganese) Manganese The Element Chromium [Click for Isotope Data] 24 Cr Chromium 51.9961 Atomic Number: 24 Atomic Weight: 51.9961 Melting Point: 2180 K (1907┬░C or 3465┬░F) Boiling Point: 2944 K (2671┬░C or 4840┬░F) Density: 7.15 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 4 Group Number: 6 Group Name: none What's in a name? From the Greek word for color, chroma. Say what? Chromium is pronounced as KROH-mee-em. History and Uses: Chromium was discovered by Louis-Nicholas Vauquelin while experimenting with a material known as Siberian red lead, also known as the mineral crocoite (PbCrO4), in 1797. He produced chromium oxide (CrO3) by mixing
It's Elemental - The Element Iron
Manganese Manganese Previous Element (Manganese) The Periodic Table of Elements Next Element (Cobalt) Cobalt The Element Iron [Click for Isotope Data] 26 Fe Iron 55.845 Atomic Number: 26 Atomic Weight: 55.845 Melting Point: 1811 K (1538┬░C or 2800┬░F) Boiling Point: 3134 K (2861┬░C or 5182┬░F) Density: 7.874 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 4 Group Number: 8 Group Name: none What's in a name? From the Anglo-Saxon word iron. Iron's chemical symbol comes from the Latin word for iron, ferrum. Say what? Iron is pronounced as EYE-ern. History and Uses: Archaeological evidence suggests that people have been using iron for at least 5000 years. Iron is the cheapest and one of the most abundant of all metals, comprising nearly 5.6% of the earth's crust and nearly all of the
It's Elemental - The Element Molybdenum
Niobium Niobium Previous Element (Niobium) The Periodic Table of Elements Next Element (Technetium) Technetium The Element Molybdenum [Click for Isotope Data] 42 Mo Molybdenum 95.96 Atomic Number: 42 Atomic Weight: 95.96 Melting Point: 2896 K (2623┬░C or 4753┬░F) Boiling Point: 4912 K (4639┬░C or 8382┬░F) Density: 10.2 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 5 Group Number: 6 Group Name: none What's in a name? From the Greek word for lead, molybdos. Say what? Molybdenum is pronounced as meh-LIB-deh-nem. History and Uses: Molybdenum was discovered by Carl Welhelm Scheele, a Swedish chemist, in 1778 in a mineral known as molybdenite (MoS2) which had been confused as a lead compound. Molybdenum was isolated by Peter Jacob Hjelm in 1781. Today,
It's Elemental - The Element Cesium
Xenon Xenon Previous Element (Xenon) The Periodic Table of Elements Next Element (Barium) Barium The Element Cesium [Click for Isotope Data] 55 Cs Cesium 132.9054519 Atomic Number: 55 Atomic Weight: 132.9054519 Melting Point: 301.59 K (28.44┬░C or 83.19┬░F) Boiling Point: 944 K (671┬░C or 1240┬░F) Density: 1.93 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 6 Group Number: 1 Group Name: Alkali Metal What's in a name? From the Latin word for sky blue, caesius. Say what? Cesium is pronounced as SEE-zee-em. History and Uses: Cesium was discovered by Robert Wilhelm Bunsen and Gustav Robert Kirchhoff, German chemists, in 1860 through the spectroscopic analysis of Durkheim mineral water. They named cesium after the blue lines they observed in its
It's Elemental - The Element Iridium
Osmium Osmium Previous Element (Osmium) The Periodic Table of Elements Next Element (Platinum) Platinum The Element Iridium [Click for Isotope Data] 77 Ir Iridium 192.217 Atomic Number: 77 Atomic Weight: 192.217 Melting Point: 2719 K (2446┬░C or 4435┬░F) Boiling Point: 4701 K (4428┬░C or 8002┬░F) Density: 22.42 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 6 Group Number: 9 Group Name: none What's in a name? From the Latin word for rainbow, iris. Say what? Iridium is pronounced as i-RID-ee-em. History and Uses: Iridium and osmium were discovered at the same time by the British chemist Smithson Tennant in 1803. Iridium and osmium were identified in the black residue remaining after dissolving platinum ore with aqua regia, a mixture
It's Elemental - The Element Gold
Platinum Platinum Previous Element (Platinum) The Periodic Table of Elements Next Element (Mercury) Mercury The Element Gold [Click for Isotope Data] 79 Au Gold 196.966569 Atomic Number: 79 Atomic Weight: 196.966569 Melting Point: 1337.33 K (1064.18┬░C or 1947.52┬░F) Boiling Point: 3129 K (2856┬░C or 5173┬░F) Density: 19.282 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 6 Group Number: 11 Group Name: none What's in a name? From the Sanskrit word Jval and the Anglo-Saxon word gold. Gold's chemical symbol comes from the the latin word for gold, aurum. Say what? Gold is pronounced as GOLD. History and Uses: An attractive and highly valued metal, gold has been known for at least 5500 years. Gold is sometimes found free in nature but it is usually found
It's Elemental - The Element Rhenium
Tungsten Tungsten Previous Element (Tungsten) The Periodic Table of Elements Next Element (Osmium) Osmium The Element Rhenium [Click for Isotope Data] 75 Re Rhenium 186.207 Atomic Number: 75 Atomic Weight: 186.207 Melting Point: 3459 K (3186┬░C or 5767┬░F) Boiling Point: 5869 K (5596┬░C or 10105┬░F) Density: 20.8 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 6 Group Number: 7 Group Name: none What's in a name? From the Latin word for the Rhine River, Rhenus. Say what? Rhenium is pronounced as REE-nee-em. History and Uses: Rhenium was discovered by the German chemists Ida Tacke-Noddack, Walter Noddack and Otto Carl Berg in 1925. They detected rhenium spectroscopically in platinum ores and in the minerals columbite ((Fe, Mn, Mg)(Nb, Ta)2O6),
It's Elemental - The Element Osmium
Rhenium Rhenium Previous Element (Rhenium) The Periodic Table of Elements Next Element (Iridium) Iridium The Element Osmium [Click for Isotope Data] 76 Os Osmium 190.23 Atomic Number: 76 Atomic Weight: 190.23 Melting Point: 3306 K (3033┬░C or 5491┬░F) Boiling Point: 5285 K (5012┬░C or 9054┬░F) Density: 22.57 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 6 Group Number: 8 Group Name: none What's in a name? From the Greek word for a smell, osme. Say what? Osmium is pronounced as OZ-mee-em. History and Uses: Osmium and iridium were discovered at the same time by the British chemist Smithson Tennant in 1803. Osmium and iridium were identified in the black residue remaining after dissolving platinum ore with aqua regia, a mixture
It's Elemental - The Element Antimony
Tin Tin Previous Element (Tin) The Periodic Table of Elements Next Element (Tellurium) Tellurium The Element Antimony [Click for Isotope Data] 51 Sb Antimony 121.760 Atomic Number: 51 Atomic Weight: 121.760 Melting Point: 903.78 K (630.63┬░C or 1167.13┬░F) Boiling Point: 1860 K (1587┬░C or 2889┬░F) Density: 6.685 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Semi-metal Period Number: 5 Group Number: 15 Group Name: Pnictogen What's in a name? From the Greek words anti and monos, which together mean "not alone." Antimony's chemical symbol comes from its historic name, Stibium. Say what? Antimony is pronounced as AN-the-MOH-nee. History and Uses: Antimony has been known since ancient times. It is sometimes found free in nature, but is usually obtained from the ores stibnite (Sb2S3) and
It's Elemental - The Element Astatine
Polonium Polonium Previous Element (Polonium) The Periodic Table of Elements Next Element (Radon) Radon The Element Astatine [Click for Isotope Data] 85 At Astatine 210 Atomic Number: 85 Atomic Weight: 210 Melting Point: 575 K (302┬░C or 576┬░F) Boiling Point: Unknown Density: about 7 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Semi-metal Period Number: 6 Group Number: 17 Group Name: Halogen Radioactive What's in a name? From the Greek word for unstable, astatos. Say what? Astatine is pronounced as AS-teh-teen or as AS-teh-ten. History and Uses: Astatine was produced by Dale R. Carson, K.R. MacKenzie and Emilio Segr├© by bombarding an isotope of bismuth, bismuth-209, with alpha particles that had been accelerated in a device called a cyclotron. This created
It's Elemental - The Element Platinum
Iridium Iridium Previous Element (Iridium) The Periodic Table of Elements Next Element (Gold) Gold The Element Platinum [Click for Isotope Data] 78 Pt Platinum 195.084 Atomic Number: 78 Atomic Weight: 195.084 Melting Point: 2041.55 K (1768.4┬░C or 3215.1┬░F) Boiling Point: 4098 K (3825┬░C or 6917┬░F) Density: 21.46 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 6 Group Number: 10 Group Name: none What's in a name? From the Spainsh word for silver, platina. Say what? Platinum is pronounced as PLAT-en-em. History and Uses: Used by the pre-Columbian Indians of South America, platinum wasn't noticed by western scientists until 1735. Platinum can occur free in nature and is sometimes found in deposits of gold-bearing sands, primarily those found in
It's Elemental - The Element Arsenic
Germanium Germanium Previous Element (Germanium) The Periodic Table of Elements Next Element (Selenium) Selenium The Element Arsenic [Click for Isotope Data] 33 As Arsenic 74.92160 Atomic Number: 33 Atomic Weight: 74.92160 Melting Point: 1090 K (817┬░C or 1503┬░F) Boiling Point: 887 K (614┬░C or 1137┬░F) Density: 5.776 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Semi-metal Period Number: 4 Group Number: 15 Group Name: Pnictogen What's in a name? From the Latin word arsenicum, the Greek word arsenikon and the Arabic word Az-zernikh. Say what? Arsenic is pronounced as AR-s'n-ik. History and Uses: Although arsenic compounds were mined by the early Chinese, Greek and Egyptian civilizations, it is believed that arsenic itself was first identified by Albertus Magnus, a German alchemist, in 1250. Arsenic occurs
It's Elemental - The Element Barium
Cesium Cesium Previous Element (Cesium) The Periodic Table of Elements Next Element (Lanthanum) Lanthanum The Element Barium [Click for Isotope Data] 56 Ba Barium 137.327 Atomic Number: 56 Atomic Weight: 137.327 Melting Point: 1000 K (727┬░C or 1341┬░F) Boiling Point: 2170 K (1897┬░C or 3447┬░F) Density: 3.62 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 6 Group Number: 2 Group Name: Alkaline Earth Metal What's in a name? From the Greek word for heavy, barys. Say what? Barium is pronounced as BAR-ee-em. History and Uses: Barium was first isolated by Sir Humphry Davy, an English chemist, in 1808 through the electrolysis of molten baryta (BaO). Barium is never found free in nature since it reacts with oxygen in the air, forming barium oxide
Laminated metal composite formed from low flow stress layers and high flow stress layers using flow constraining elements and method of making same
This invention relates to a laminated metal composite, comprising alternating layers of low flow stress material and high flow stress material, and formed using flow constraining elements around each low flow stress layer; and a method of making same. A composite is a combination of at least two chemically distinct materials with a distinct interface separating the two materials. A metal matrix composite (MMC) is a composite material composed of a metal and a nonmetallic reinforcing agent such as silicon carbide (SiC) or graphite in continuous or discontinuous fiber, whisker, or discrete particulate form. A laminate is a material composed of several bonded layers. It is possible to have a laminate composed of multi-layers of a single type of material bonded to each other. However, such a laminate would not be considered to be a composite. The term {open_quotes}laminated metal composite{close_quotes} (LMC), as used herein, is intended to include a structural material composed of: (1) layers of metal or metal alloys interleaved with (2) a different metal, a metal alloy, or a metal matrix composite (MMC) containing strengthening agents.
Syn, C.K.; Lesuer, D.R.
Size Effect of Element in Structural Blasting Demolition
Performed the size effect of the unit in numerical simulation of blasting demoLition. Considered three elemental sizes, which were 10, 20 and 40 cm. Adopt 40 cm element, the structure was damaged more seriously. This resulted in the bigger error in predicting ... Keywords: blasting demoLition, finite element, numerical simulation, size effect
Guo-liang Yang; Lin-lin Jiang; Yu-long Che
An operator splitting scheme with a distributed Lagrange multiplier based fictitious domain method for wave propagation problems
We propose a novel fictitious domain method based on a distributed Lagrange multiplier technique for the solution of the time-dependent problem of scattering by an obstacle. We study discretizations that include a fully conforming approach as well as ... Keywords: Fictitious domains, Mixed finite element methods, Operator splitting, Perfectly matched layer
Vrushali A. Bokil; Roland Glowinski
Neutronic fuel element fabrication
This disclosure describes a method for metallurgically bonding a complete leak-tight enclosure to a matrix-type fuel element penetrated longitudinally by a multiplicity of coolant channels. Coolant tubes containing solid filler pins are disposed in the coolant channels. A leak-tight metal enclosure is then formed about the entire assembly of fuel matrix, coolant tubes and pins. The completely enclosed and sealed assembly is exposed to a high temperature and pressure gas environment to effect a metallurgical bond between all contacting surfaces therein. The ends of the assembly are then machined away to expose the pin ends which are chemically leached from the coolant tubes to leave the coolant tubes with internal coolant passageways. The invention described herein was made in the course of, or under, a contract with the U.S. Atomic Energy Commission. It relates generally to fuel elements for neutronic reactors and more particularly to a method for providing a leak-tight metal enclosure for a high-performance matrix-type fuel element penetrated longitudinally by a multiplicity of coolant tubes. The planned utilization of nuclear energy in high-performance, compact-propulsion and mobile power-generation systems has necessitated the development of fuel elements capable of operating at high power densities. High power densities in turn require fuel elements having high thermal conductivities and good fuel retention capabilities at high temperatures. A metal clad fuel element containing a ceramic phase of fuel intimately mixed with and bonded to a continuous refractory metal matrix has been found to satisfy the above requirements. Metal coolant tubes penetrate the matrix to afford internal cooling to the fuel element while providing positive fuel retention and containment of fission products generated within the fuel matrix. Metal header plates are bonded to the coolant tubes at each end of the fuel element and a metal cladding or can completes the fuel-matrix enclosure by encompassing the sides of the fuel element between the header plates.
Korton, George (Cincinnati, OH)
It's Elemental - The Element Praseodymium
Today, praseodymium is primarily obtained through an ion exchange process from monazite sand ((Ce, La, Th, Nd, Y)PO4), a material rich in rare earth elements. Praseodymium's...
It's Elemental - The Element Neodymium
Today, neodymium is primarily obtained from through an ion exchange process monazite sand ((Ce, La, Th, Nd, Y)PO4), a material rich in rare earth elements. Neodymium makes up...
It's Elemental - The Element Samarium
1879. Today, samarium is primarily obtained through an ion exchange process from monazite sand ((Ce, La, Th, Nd, Y)PO4), a material rich in rare earth elements that can contain as...
It's Elemental - The Element Lanthanum
Today, lanthanum is primarily obtained through an ion exchange process from monazite sand ((Ce, La, Th, Nd, Y)PO4), a material rich in rare earth elements that can contain as...
It's Elemental - The Element Promethium
(Samarium) Samarium The Element Promethium Click for Isotope Data 61 Pm Promethium 145 Atomic Number: 61 Atomic Weight: 145 Melting Point: 1315 K (1042C or 1908F) Boiling...
It's Elemental - The Element Cadmium
(Indium) Indium The Element Cadmium Click for Isotope Data 48 Cd Cadmium 112.411 Atomic Number: 48 Atomic Weight: 112.411 Melting Point: 594.22 K (321.07C or 609.93F)...
It's Elemental - The Element Lutetium
(Hafnium) Hafnium The Element Lutetium Click for Isotope Data 71 Lu Lutetium 174.9668 Atomic Number: 71 Atomic Weight: 174.9668 Melting Point: 1936 K (1663C or 3025F)...
It's Elemental - The Element Holmium
(Erbium) Erbium The Element Holmium Click for Isotope Data 67 Ho Holmium 164.93032 Atomic Number: 67 Atomic Weight: 164.93032 Melting Point: 1747 K (1474C or 2685F)...
It's Elemental - The Element Chlorine
Sulfur Sulfur Previous Element (Sulfur) The Periodic Table of Elements Next Element (Argon) Argon The Element Chlorine [Click for Isotope Data] 17 Cl Chlorine 35.453 Atomic Number: 17 Atomic Weight: 35.453 Melting Point: 171.65 K (-101.5┬░C or -150.7┬░F) Boiling Point: 239.11 K (-34.04┬░C or -29.27┬░F) Density: 0.003214 grams per cubic centimeter Phase at Room Temperature: Gas Element Classification: Non-metal Period Number: 3 Group Number: 17 Group Name: Halogen What's in a name? From the Greek word for greenish yellow, chloros. Say what? Chlorine is pronounced as KLOR-een or as KLOR-in. History and Uses: Since it combines directly with nearly every element, chlorine is never found free in nature. Chlorine was first produced by Carl Wilhelm Scheele, a Swedish chemist, when he combined the mineral pyrolusite (MnO2) with
It's Elemental - The Element Zinc
Copper Copper Previous Element (Copper) The Periodic Table of Elements Next Element (Gallium) Gallium The Element Zinc [Click for Isotope Data] 30 Zn Zinc 65.38 Atomic Number: 30 Atomic Weight: 65.38 Melting Point: 692.68 K (419.53┬░C or 787.15┬░F) Boiling Point: 1180 K (907┬░C or 1665┬░F) Density: 7.134 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 4 Group Number: 12 Group Name: none What's in a name? From the German word zink. Say what? Zinc is pronounced as ZINK. History and Uses: Although zinc compounds have been used for at least 2,500 years in the production of brass, zinc wasn't recognized as a distinct element until much later. Metallic zinc was first produced in India sometime in the 1400s by heating the mineral calamine (ZnCO3) with wool. Zinc was rediscovered by
It's Elemental - The Element Fluorine
Oxygen Oxygen Previous Element (Oxygen) The Periodic Table of Elements Next Element (Neon) Neon The Element Fluorine [Click for Isotope Data] 9 F Fluorine 18.9984032 Atomic Number: 9 Atomic Weight: 18.9984032 Melting Point: 53.53 K (-219.62┬░C or -363.32┬░F) Boiling Point: 85.03 K (-188.12┬░C or -306.62┬░F) Density: 0.001696 grams per cubic centimeter Phase at Room Temperature: Gas Element Classification: Non-metal Period Number: 2 Group Number: 17 Group Name: Halogen What's in a name? From the Latin and French words for flow, fluere. Say what? Fluorine is pronounced as FLU-eh-reen or as FLU-eh-rin. History and Uses: Fluorine is the most reactive of all elements and no chemical substance is capable of freeing fluorine from any of its compounds. For this reason, fluorine does not occur free in nature and was extremely difficult for
Discontinuous Galerkin Methods and Local Time Stepping for Wave Propagation
Locally refined meshes impose severe stability constraints on explicit time-stepping methods for the numerical simulation of time dependent wave phenomena. To overcome that stability restriction, local time-stepping methods are developed, which allow arbitrarily small time steps precisely where small elements in the mesh are located. When combined with a discontinuous Galerkin finite element discretization in space, which inherently leads to a diagonal mass matrix, the resulting numerical schemes are fully explicit. Starting from the classical Adams-Bashforth multi-step methods, local time stepping schemes of arbitrarily high accuracy are derived. Numerical experiments validate the theory and illustrate the usefulness of the proposed time integration schemes.
Grote, M. J.; Mitkova, T. [University of Basel, Rheinsprung 21, CH-4051 Basel (Switzerland)
A ceramic fuel element for a nuclear reactor that has improved structural stability as well as improved cooling and fission product retention characteristics is presented. The fuel element includes a plurality of stacked hollow ceramic moderator blocks arranged along a tubular raetallic shroud that encloses a series of axially apertured moderator cylinders spaced inwardly of the shroud. A plurality of ceramic nuclear fuel rods are arranged in the annular space between the shroud and cylinders of moderator and appropriate support means and means for directing gas coolant through the annular space are also provided. (AEC)
Bean, R.W.
It's Elemental - Isotopes of the Element Thorium
Table of Elements Next Element (Protactinium) Protactinium Isotopes of the Element Thorium Click for Main Data Most of the isotope data on this site has been obtained from...
It's Elemental - The Element Lead
Thallium Thallium Previous Element (Thallium) The Periodic Table of Elements Next Element (Bismuth) Bismuth The Element Lead [Click for Isotope Data] 82 Pb Lead 207.2 Atomic Number: 82 Atomic Weight: 207.2 Melting Point: 600.61 K (327.46┬░C or 621.43┬░F) Boiling Point: 2022 K (1749┬░C or 3180┬░F) Density: 11.342 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 6 Group Number: 14 Group Name: none What's in a name? From the Anglo-Saxon word lead. Lead's chemical symbol comes from the Latin word for waterworks, plumbum. Say what? Lead is pronounced as LED. History and Uses: Lead has been known since ancient times. It is sometimes found free in nature, but is usually obtained from the ores galena (PbS), anglesite (PbSO4), cerussite (PbCO3) and minum (Pb3O4). Although lead makes up only
It's Elemental - The Element Iodine
Tellurium Tellurium Previous Element (Tellurium) The Periodic Table of Elements Next Element (Xenon) Xenon The Element Iodine [Click for Isotope Data] 53 I Iodine 126.90447 Atomic Number: 53 Atomic Weight: 126.90447 Melting Point: 386.85 K (113.7┬░C or 236.7┬░F) Boiling Point: 457.55 K (184.4┬░C or 364.0┬░F) Density: 4.93 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Non-metal Period Number: 5 Group Number: 17 Group Name: Halogen What's in a name? From the Greek word for violet, iodes. Say what? Iodine is pronounced as EYE-eh-dine or as EYE-eh-din. History and Uses: Iodine was discovered by the French chemist Barnard Courtois in 1811. Courtois was extracting sodium and potassium compounds from seaweed ash. Once these compounds were removed, he added sulfuric acid (H2SO4) to
Base Elements
Table 4┬Ā┬Ā┬ĀPrincipal effects of superalloy base elements on alloy characteristics...to ╬│Ō?▓ or ╬│Ō?│ Requires fcc stabilizer Cobalt prices have been known to be volatile in the past. Suitable for creep-resistant applications with low stresses or
Nuclear fuel element
A nuclear fuel element and a method of manufacturing the element. The fuel element is comprised of a metal primary container and a fuel pellet which is located inside it and which is often fragmented. The primary container is subjected to elevated pressure and temperature to deform the container such that the container conforms to the fuel pellet, that is, such that the container is in substantial contact with the surface of the pellet. This conformance eliminates clearances which permit rubbing together of fuel pellet fragments and rubbing of fuel pellet fragments against the container, thus reducing the amount of dust inside the fuel container and the amount of dust which may escape in the event of container breach. Also, as a result of the inventive method, fuel pellet fragments tend to adhere to one another to form a coherent non-fragmented mass; this reduces the tendency of a fragment to pierce the container in the event of impact.
Zocher, Roy W. (Los Alamos, NM)
Badly Shaped Elements (BadlyShapedElements)
... shaped elements. Synopsis. BadlyShapedElements ( threshold ). Details. Base class: SkelModTargets; Parameters: threshold The threshold shape ...
Mesh generation and numerical analysis of a Galerkin method for highly conductive prefractal layers
In this paper we provide a piecewise linear Galerkin approximation of a second order transmission problem across a highly conductive prefractal layer of von Koch type. We firstly generate an appropriate mesh adapted to the geometric shape of the interface ... Keywords: A priori error estimate, Adaptive mesh refinement, Finite element methods, Highly conductive layers, Transmission problems, Von Koch curve
Patrizia Bagnerini; Annalisa Buffa; Elisa Vacca
A stochastic variational multiscale method for diffusion in heterogeneous random media
A stochastic variational multiscale method with explicit subgrid modelling is provided for numerical solution of stochastic elliptic equations that arise while modelling diffusion in heterogeneous random media. The exact solution of the governing equations ... Keywords: generalized polynomial chaos, multiscale finite element, operator upscaling, stochastic diffusion, subgrid modelling, variational multiscale
Badrinarayanan Velamur Asokan; Nicholas Zabaras
A Jacobian-free Newton Krylov method for mortar-discretized thermomechanical contact problems
Multibody contact problems are common within the field of multiphysics simulation. Applications involving thermomechanical contact scenarios are also quite prevalent. Such problems can be challenging to solve due to the likelihood of thermal expansion ... Keywords: Mortar finite element method, Pellet cladding interaction, Reactor fuel performance, Reactor multiphysics simulation, Thermomechanical contact
Glen Hansen
Error estimation for the HHT method in non-linear solid dynamics
This work presents a new error estimator that can be used in both linear and non-linear solid and structural dynamic problems. Specifically, this estimator is developed for the Hilber-Hughes-Taylor (HHT) method and it takes into account the error made ... Keywords: Error estimation, Finite elements, Solid dynamics, Structural dynamics, Time integration
Luis M. Lacoma; Ignacio Romero
A fuel element was developed for a gas cooled nuclear reactor. The element is constructed in the form of a compacted fuel slug including carbides of fissionable material in some cases with a breeder material carbide and a moderator which slug is disposed in a canning jacket of relatively impermeable moderator material. Such canned fuel slugs are disposed in an elongated shell of moderator having greater gas permeability than the canning material wherefore application of reduced pressure to the space therebetween causes gas diffusing through the exterior shell to sweep fission products from the system. Integral fission product traps and/or exterior traps as well as a fission product monitoring system may be employed therewith. (AEC)
Fortescue, P.; Zumwalt, L.R.
Standard Elements
Table 1┬Ā┬Ā┬ĀASTM standards applicable to element-level testing of composites...Composite Plates Subjected to a Distributed Load Plate flexure D 6484 Open-Hole Compression Strength of Polymer Matrix Composites Open-hole compression strength Z 5370Z Compression After Impact Strength of Fiber-Resin Composites Compression after impact Z 7225Z Mixed Mode I-Mode II...
(4.5 hours total) with 16 GB RAM - Final Model: * Approximately 116 hours with 48 GB RAM * Required GTStrudl Version 32 October 25, 2011 14 Department of Energy - Natural...
Finite Element Analysis of Residual Stress of Plasma-Sprayed ...
Aerosol Route Synthesis of Copper Oxide Nanoparticles Using Copper Nitrate Solution Ę AlGaAs-Based Optical ... Defect Energetics and Fission Product Transport in ZrC ... Enhancing Mineral Beneficiation by High Intensity Power Ultrasound.
Expressive and scalable finite element simulation beyond 1000 cores
). The primary motivations are to reduce the memory overhead associated with multiple MPI processes, and to map better onto linear solvers that are known to work best when threaded (e.g. LU solvers). 1.2 Parallel file input and output DOLFIN I/O was based around... XML formats, with memory scalability achieved using SAX parsing (line-by-line read) for input, and using VTK XML output for post-processing, which uses a one-file-per-process (and per time step) model. Issues with these approaches include: Ģ XML...
Richardson, Chris J.; Wells, Garth N.
Representations of finite element tensors via automated code generation
.71 856736 0.17 p = 2, q = 4 54300 4.36 337692 1.01 2058876 0.23 p = 3, q = 1 3044 0.36 30236 0.16 379964 0.02 p = 3, q = 2 12488 0.92 126368 0.26 1370576 0.03 p = 3, q = 3 36664 1.73 391552 0.37 4034704 0.05 p = 3, q = 4 92828 2.55 950012 0.49 9566012 0.06 p... = 3 950 8.26 6800 1.73 42998 0.39 251876 0.10 p = 2, q = 4 2457 10.10 15987 2.15 95247 0.48 585567 0.10 p = 3, q = 1 181 2.44 1715 1.02 20991 0.16 218767 0.03 p = 3, q = 2 550 3.78 6992 0.78 73596 0.11 754084 0.02 p = 3, q = 3 1910 4.21 20100 0...
Oelgaard, Kristian B; Wells, G N
Flexible finite-element modeling of global geomagnetic depth sounding
Modeling in 2D and 3D for Geomagnetic Depth Sounding (31, 16610. Banks, R. , 1969: Geomagnetic variations and the1997: Introduction to geomagnetic fields. Cambridge Univ Pr.
Ribaudo, Joseph Thomas
Finite Element Investigation of Woven Glass¢Epoxy Composites ...
A10: Mechanical Properties and Weld-Ability of Laser Welded Metal Bellows ..... J5: Electrical Conductivity of Diesel-Biodiesel Blends Evaluated by theĀ...
Comparison of Classical Tools and Modern Finite Element Modeling ...
... including: operating practice, slag conductivity, temperature, power intensity, ... Design and Commissioning of the Ausmelt TSL Lead Smelter at Yunnan TinĀ...
Finite Element Implementation of a Thermodynamic Description of Piezoelectric Microstructures
, UK). The thermal-depoling experiments were conducted by annealing the poled samples for 2 h up to 700
Garc├Ła, R. Edwin
Development of a Finite Element Model of Warping Inflatable Wings
fabric composites that harden after deployment and exposure to UV radiation or of rugged woven materials, internal pressurization and a woven fabric shell structure. This effort includes determination of material
Jacob, Jamey
Finite Element Modeling of Shallow Foundations on Nonlinear Soil Medium
Engineering Mechanics Division, ASCE, 102(EM2): 249-263. [Engineering Division, ASCE, 105(GT12):1435- 1454. [5]Engineering Mechanics Division, ASCE, 97(EM5):1381-1395. [7
Zhang, Jian; Tang, Yuchuan
Topology Design using B-spline Finite Elements.
??Topology optimization is an approach to find the optimal material distribution or layout within a given feasible design space. The entire geometry is treated asģ (more)
Parthasarathy, Anand
Finite Element Based Stress Analysis and Optimization of Crankshaft
Results achieved from aforementioned analysis were used in optimization of the ... Phase Transformations Based on a Grain Boundary and Interfacial EnergyĀ...
Incorporating Radiant Heat Exchange into Finite Element Models of ...
In order to simplify this non-linear mode of heat transfer, the effects of ... Technical Risk Mitigation Through Rheometallurgical Generation of Process andĀ...
A Free Software Three-Dimensional Structural Finite Element ... - TMS
Nov 7, 2007 ... Calculix is an Open Source solid mechanics modeling program written and maintained by employees of MTU Munich, an Aero EngineĀ...
Finite Element formulation for nonlinear analysis of masonry walls
The work builds upon previous developments made by the authors in the context of the nonlinear, in-plane analysis of masonry walls. The structural behavior is characterized by phenomena, such as strain localization, damage, and friction, which need to ... Keywords: In-plane nonlinear masonry mechanics, Mohr-Coulomb frictional behavior, Non-associated plasticity
S. Brasile; R. Casciaro; G. Formica