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Difference Schemes Of High Accuracy For Equation Of Spin Waves In Magnets, Mirsaid Aripov, Dauletbay Utebaev, Zhusipbay Nurullaev

Bulletin of National University of Uzbekistan: Mathematics and Natural Sciences

Three-parameter difference schemes of the finite element method with a high order of accuracy are considered in the article for a mathematical model of spin waves in magnets (Sobolev-type equations). Discretization of time and space variables is conducted on the basis of the finite element method. The parameters of the scheme allow choosing the best approximation and accuracy, and an economic algorithm for numerical implementation. Theorems on the stability and convergence of the considered difference schemes are obtained.

Analysis Of Laterally-Loaded Piles Embedded In Multi-Layered Soils Using Efficient Finite-Element Method, Hai-Peng Zhao, Xue-You Li, Jian-Hong Wan, Xiang-Zhi Zheng, Si-Wei Liu

Rock and Soil Mechanics

Mechanical analysis of laterally-loaded piles embedded in multi-layered soils is a critical step in design. Traditional finite-element method may have deficiency in accuracy and efficiency when applied to analyze this problem. An efficient finite-element method is proposed in this paper. A “pile element” that adopts the distributed “soil springs” along the element length to reflect the nonlinear behaviors of the pile-soil interactions is developed in this method. The dominant feature of the pile element is the direct integration of soil properties into the element formulation, namely, a pile element comprises both the pile and soil properties. The pile element formulation …

Research For Magnetic Shielding Effect Of 3phase Air Core Reactor In Substation By Using Different Materials, Xianjin Wang, Kai Zhou, Shilin Zhao, Yuhao Chen, Shijia Chen, Yonglu Huang

Journal of Electric Power Science and Technology

In order to research the magnetic field interference on cables nearby 3phase air core reactor and the shielding effect of different materials, this paper analyses the influence of high conductivity materials and high permeability materials on spatial magnetic field on the basis of 3D electromagnetic field simulation model. Then the influence mechanisms are expounded. Furthermore, the induced voltages in different shielding measures are calculated and discussed basing on magnetic vector potential obtained from the finite element simulation results. The results show that, for the shielding of high permeability materials, good shielding effect can be achieved only by connecting 3 phases …

Eigenvalue Problems On Atypical Domains - The Finite Element Method, Toufiic Ayoub

Undergraduate Student Research Internships Conference

Why do we care about eigenvalues and eigenvectors? What's the big deal? For many people enrolled in entry level linear algebra courses, these concepts seem like far fetched abstractions that become pointless exercises in computation. But in reality, these fundamental ideas are vital to how we live our lives every single day. But how?

Simulating Dislocation Densities With Finite Element Analysis, Ja'nya Breeden, Dow Drake, Saurabh Puri

REU Final Reports

A one-dimensional set of nonlinear time-dependent partial differential equations developed by Acharya (2010) is studied to observe how differing levels of applied strain affect dislocation walls. The framework of this model consists of a convective and diffusive term which is used to develop a linear system of equations to test two methods of the finite element method. The linear system of partial differential equations is used to determine whether the standard or Discontinuous Galerkin method will be used. The Discontinuous Galerkin method is implemented to discretize the continuum model and the results of simulations involving zero and non-zero applied strain …

Triangulation And Finite Element Method For A Variational Problem Inspired By Medical Imaging, Tim Komperda, Enrico Au-Yeung

DePaul Discoveries

We implement the finite element method to solve a variational problem that is inspired by medical imaging. In our application, the domain of the image does not need to be a rectangle and can contain a cavity in the middle. The standard approach to solve a variational problem involves formulating the problem as a partial differential equation. Instead, we solve the variational problem directly, using only techniques available to anyone familiar with vector calculus. As part of the computation, we also explore how triangulation is a useful tool in the process.

Smooth Global Approximation For Continuous Data Assimilation, Kenneth R. Brown

Theses and Dissertations

This thesis develops the finite element method, constructs local approximation operators, and bounds their error. Global approximation operators are then constructed with a partition of unity. Finally, an application of these operators to data assimilation of the two-dimensional Navier-Stokes equations is presented, showing convergence of an algorithm in all Sobolev topologies.

Impact Of New Generation Wide-Base Tires On Fuel Consumption, Izak M. Said, Egemen Okte, Jaime Hernandez, Imad L. Al-Qadi

Civil and Environmental Engineering Faculty Research and Publications

This study combined multiple approaches to evaluate the structural and economic impact of using new-generation wide-base tires (NG-WBT) in New Brunswick, Canada. A three-dimensional finite-element model of a typical pavement structure used in New Brunswick was used to predict critical pavement responses. The model includes measured tire-pavement contact forces among other variables overlooked in conventional flexible pavement analysis approaches. Using the model output, regression analysis was performed to predict the responses under various loadings to avoid performing the time-consuming finite-element analysis. Eight-year weight-in-motion data and critical pavement responses were used in transfer functions to predict pavement damage and the corresponding …

A Novel Variable Reluctance Resolver With Simplified Winding Arrangement And Adaptive Pi Controller, Bikram Bhandari

University of New Orleans Theses and Dissertations

Conventional variable reluctance resolvers require a complicated winding arrangement (i.e., one set of excitation winding and two sets of signal winding), high-frequency ac supply, extra circuit component to demodulate the high frequency induced voltage (i.e., amplitude demodulation circuit), and a resolver-to-digital converter with the PI controller. The thesis presents an innovative design solution to reduce the structural complexity of the resolver and improve the functionality of the controller unit. The proposed novel design simplifies the winding arrangement and eliminates the necessity of the demodulation signal processing circuit component. In addition, the conventional PI controller is being replaced by the adaptive …

A Hybrid Simulation Model To Predict The Steady-State Thermal Profile Of Hermetic Reciprocating Compressors, Fernando A. Aardoom, Victor H. P. Rosa, Cesar J. Deschamps

International Compressor Engineering Conference

Numerical simulation models are paramount to design compressors that follow reliability and efficiency requirements. This paper presents a simulation model to predict the steady-state thermal profile of hermetic reciprocating compressors. A finite element method is used to compute the temperature distribution of the solid components and the fluid in the suction and discharge lines, whereas a lumped-parameter formulation is used to evaluate the internal environment temperature and the gas temperature at the end of the compression cycle. The heat transfer between the gas and the solid components is predicted using imposed convective heat transfer coefficients; some of which are estimated …

Corrosion Modeling Of Magnesium-Based Medical Implants, Moataz Abdalla

Masters Theses and Doctoral Dissertations

Biodegradable metals have been under significant research as alternatives to the nonbiodegradable materials in the field of medical implants. In this scope, magnesium and its alloys were widely investigated due to their superior biocompatibility. However, magnesium is a highly active metal and has a high corrosion rate in aqueous environments especially body fluids. Considerable research was done to develop numerical models towards an inexpensive designing tool to assess the change of the implant’s geometry and mechanical strength during degradation. To the best of our knowledge, the effect of coating was not investigated before in the literature in terms of modeling …

Numerical Investigation Of Time-Integration Schemes Applicable To Fluid-Structure Interaction, Amirehsan Ghasemi

Masters Theses and Doctoral Dissertations

In many civil engineering applications the interaction between fluid and structures represents a crucial aspect for analysis and proper design. The simulation of this phenomenon requires the application of high-fidelity numerical methods. In the current work, the fluid and structural equations both utilize the same multistep or multistage schemes for temporal advancement. This requires the structural equations to be recast in state-space form. The implicit time-marching schemes studied in this thesis are limited to the Backward Differentiation Formula (BDF) schemes, Modified Extended-BDF schemes, and a Singly-Diagonal Implicit Runge-Kutta (SDIRK) method. Verification and validation of temporal and spatial order of accuracy …

A Hyperelastic Porous Media Framework For Ionic Polymer-Metal Composites And Characterization Of Transduction Phenomena Via Dimensional Analysis And Nonlinear Regression, Zakai J. Olsen

UNLV Theses, Dissertations, Professional Papers, and Capstones

Ionic polymer-metal composites (IPMC) are smart materials that exhibit large deformation in response to small applied voltages, and conversely generate detectable electrical signals in response to mechanical deformations. The study of IPMC materials is a rich field of research, and an interesting intersection of material science, electrochemistry, continuum mechanics, and thermodynamics. Due to their electromechanical and mechanoelectrical transduction capabilities, IPMCs find many applications in robotics, soft robotics, artificial muscles, and biomimetics. This study aims to investigate the dominating physical phenomena that underly the actuation and sensing behavior of IPMC materials. This analysis is made possible by developing a new, hyperelastic …

Finite Element Analysis Of Convective Flow Through Porous Medium With Variable Suction, Parul Saxena, Manju Agarwal

Information Sciences Letters

The investigation has been carried out to analyse the convective flow through a porous medium with variable suction. The finite element analysis has been used for computational results. The effect of different dimensionless numbers on the convective flow has been done using Matlab. The effect of magnetic parameter on the flow has been analysed. The fluid behavior has been also observed with the variation of the permeability parameter.

Finite Element Approximation Of Nonlocal Dynamic Fracture Models, P. K. Jha, R. Lipton

Faculty Publications

In this work we estimate the convergence rate for time stepping schemes applied to nonlocal dynamic fracture modeling. Here we use the nonlocal formulation given by the bond based peridynamic equation of motion. We begin by establishing the existence of H2 peridynamic solutions over any finite time interval. For this model the gradients can become large and steep slopes appear and localize when the non-locality of the model tends to zero. In this treatment spatial approximation by finite elements are used. We consider the central-difference scheme for time discretization and linear finite elements for discretization in the spatial variable. The …

Correlating With Local Variation In Collagen Level And Mechanical Properties Of The Heart Tissues, Talayeh Tavangar

Electronic Theses and Dissertations

The determination of the myocardium's tissue properties is essential in constructing finite element (FE) models of the heart. To obtain accurate results, especially for functionally modeling the heart, we must determine the tissue properties in-vivo. The calculation of the heart tissue properties remains a challenging area as it is categorized as a heterogeneous, anisotropic, nonlinear soft tissue that undergoes large deformation. In this work, we tried to introduce and evaluated a finite element method to determine the mechanical properties of the cardiac tissue. The introduced method combined a finite element modeling with the experimentally obtained images from the left and …

Parallel Anisotropic Unstructured Grid Adaptation, Christos Tsolakis, Nikos Chrisochoides, Michael A. Park, Adrien Loseille, Todd Michal

Computer Science Faculty Publications

Computational fluid dynamics (CFD) has become critical to the design and analysis of aerospace vehicles. Parallel grid adaptation that resolves multiple scales with anisotropy is identified as one of the challenges in the CFD Vision 2030 Study to increase the capacity and capability of CFD simulation. The study also cautions that computer architectures are undergoing a radical change, and dramatic increases in algorithm concurrency will be required to exploit full performance. This paper reviews four different methods to parallel anisotropic grid adaptation. They cover both ends of the spectrum: 1) using existing state-of-the-art software optimized for a single core and …

Evaluating Reserve Strength Of Girder Bridges Due To Bridge Rail Load Shedding, Yao Wang, Mirela D. Tumbeva, Ashley P. Thrall

JTRP Technical Reports

This research experimentally and numerically evaluated the reserve strength of girder bridges due to bridge rail load shedding. The investigation included: (1) performing non-destructive field testing on two steel girder bridges and one prestressed concrete girder bridge, (2) developing validated finite element numerical models, and (3) performing parametric numerical investigations using the validated numerical modeling approach. Measured data indicated that intact, integral, reinforced concrete rails participate in carrying live load. Research results culminated in recommendations to evaluate the reserve strength of girder bridges due to the participation of the rail, as well as recommendations for bridge inspectors for evaluating steel …

Development Of Triangular And Tetrahedral Finite Elements For Solutions To Thermoelastic Instabilities Using Hotspotter, Cortney Samuel Leneave

Electronic Theses and Dissertations

The objective of the work presented in this thesis is to develop first-order triangular and tetrahedral elements for solutions to Thermoelastic Instabilities (TEI) regarding sliding friction systems in Hotspotter.

Hotspotter software uses a finite element method and an eigenvalue method and is an important tool because currently no other commercial software exists which solves the TEI problem for critical velocities and wave numbers of a system. Hotspotter currently uses quadrilateral and hexahedral elements for two and three dimensional analysis, respectively. Typically, tri and tet elements are used in industry when doing static and dynamic stress analysis. Therefore, the Hotspotter user …