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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 33 for “"variational formulation"”.
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The variational formulation of a pseudo feedback control algorithm
… demonstrated. The procedure is developed using a variational formulation of the optimal control problem. A convex index of performance is presumed. The Finite Element Method is used in conjunction with a variable mesh gridation scheme to produce accurate local approximations of the weak functional …
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A Variational Formulation Describing the Attractors of Some Open, Dissipative, Electromechanical Systems
Submitted by Jesse Garrison (jagarris@illinois.edu) on 2012-01-13T18:32:34Z No. of bitstreams: 1 1997_dueweke.pdf: 2541154 bytes, checksum: c57cedd3fd08e4e236d205f829780758 (MD5)
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Solution of 2-D contact problems using a variational formulation with Lagrange multipliers
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1982.
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Chemically driven soft bioinspired systems and the variational formulation of physics-informed neural networks
… have studied in this work. In the conventional formulation, physics-informed neural networks (PINN) solve differential equations by minimizing a phenomenological loss function constructed based on these equations. However, higher order derivatives present in many differential equations lead to …
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Stabilized variational formulation for direct solution of inverse problems in heat conduction and elasticity with discontinuities
… however, and therefore it is desirable to have formulations that can accommodate discontinuities in both data and solution. Toward this end, we present a mixed variational formulation for this class of problems that handles discontinuities well. We motivate the mixed formulation by examining the …
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Cosmological perturbation theory and the variational principle in gravitation
… reviewed over the period 1960-1993. Secondly the variational principle, apropos of gravitation, is formulated and discussed. These two fields are then synthesised via a variational formulation of general relativity and cosmological perturbation theory. In the process new light is shed on Covariant …
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A Hybrid Variational-Level Set Approach to Handle Topological Changes
… then followed by an optimization step, using a variational formulation, that seeks to improve boundary mesh conformity to the zero level contour of the level set function. The advantage of this method is that it directly allows for using a variational formulation of the physics being modeled and …
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The use of a non-classical friction law in finite-element analysis of contact problems
… priori. Finite element approximations based on a variational formulation of the problem, developed by Oden and Pires, are used to generate a discretised version. The solution procedure incorporates an iterative algorithm for the determination of the extent of the contact surface. Alternative …
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Análise dinâmica de placas pelo método dos elementos finitos
… forces. Initially a brief exposition of the variational formulation concerning the dynamics of thin plates is presented and the finite element method is applied to this formulation. Three types of elements are presented (triangular with 9 degrees of freedon, retangular with 12 degrees of …
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Optimization of Plane Wave Directions in Plane Wave Discontinuous Galerkin Methods for the Helmholtz Equation
… a tracking type objective functional and the variational formulation of the PWDG method as a constraint. The necessary optimality conditions are derived and numerically solved by a projected gradient method. Numerical results are given which illustrate the benefits of the approach.
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Issues related to finite element techniques for two dimensional transmission structures
… Maxwell's equations is developed through a novel variational formulation involving the method of Lagrange multipliers, with attention given to the physical basis of the obtained functional. This model is then applied to the problem of determining the propagation constant of a waveguide.
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The solution of steady-state free surface problems by the finite element method
… thesis is concerned with the development of a variational formulation for the problem of viscous incompressible free surface flows, and with the development and implementation of algorithms for the solution of this problem by finite elements. The study is restricted to two-dimensional steady …
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Formulation, analysis and solution algorithms for a model of gradient plasticity within a discontinuous Galerkin framework
… using a discontinuous Galerkin finite element formulation. Both the small- and finite-strain theories are investigated. Considerable attention is focused on developing a firm mathematical foundation for the model of gradient plasticity restricted to the infinitesimal-strain regime. The key …
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Continuum Analytical Shape Sensitivity Analysis of 1-D Elastic Bar
… of this work is the derivation of three variational formulations for obtaining shape sensitivities, one in terms of the local sensitivity and two in terms of the material sensitivity. These derivations involve evaluating (a) the variational form of the continuum sensitivity equations, or …
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The solar corona: modeled, discretized, visualized
… shape of the filaments is determined based on a variational formulation. Lastly, we apply the entire model to output visual renderings of the whole sun and put the output to various tests. The fidelity of the method is demonstrated by comparing the resulting renderings with actual images of our …
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A Multilevel Fast Multipole Algorithm for Analyzing Radiation and Scattering From Wire Antennas in a Complex Environment
A hybrid VSIE-MLFMA formulation is applied to solve for scattering and radiation solutions from wire antennas, IBC surfaces, and inhomogeneous dielectric objects. Unlike the traditional method of moments, the VSIE-MLFMA formulation has a computational complexity of O( N log N) for both CPU time and …
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Anisotropic variational models and PDEs for inverse imaging problems
In this thesis we study new anisotropic variational regularisers and partial differential equations (PDEs) for solving inverse imaging problems that arise in a variety of real-world applications. Firstly, we introduce a new anisotropic higher-order total directional variation regulariser. We …
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Fluid dynamics in action
… Lagrangian description of fluids. We develop the variational formulation based on symmetry principles defined on such fluid space-time. Through a prescribed correspondence, the dynamical fields are mapped to the standard fluid variables, such as temperature, chemical potential and velocity. This …
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Vibration Energy Harvesting for the Development of autonomous monitoring Systems. Application to railway Bridges
… lumped-parameter models are derived from a variational formulation for bimorph and unimorph cantilever configurations, enabling the development of a novel efficient design optimisation procedure. The models are validated through numerical simulations, laboratory testing, and in-field …
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Συμβολή στην ανάλυση των εκσκαφών με την μέθοδο των πεπερασμένων στοιχείων
… INCLUSION OF GHOST ELEMENTS AND MATHEMATICAL FORMULATION. THE CONVENTIONAL APPROACH BASED ON LINEAR MATERIAL BEHAVIOR OF COMPUTING DISPLACEMENTS AND STRESSES AS IF THE EXCAVATION WERECOMPLETED IN A SINGLE STAGE DOES NOT ACCOUNT FOR PATH DEPENDENCY AND NONLINEARITY INTRODUCED BY INCREMENTAL …
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