Global ETD Search
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 27 for “"Time Discretization"”.
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On qualitative properties and convergence of time-discretization methods for semigroups
… convergence and qualitative properties of time-discretization methods for strongly continuous semigroups. Stability, convergence, and preservation of contractivity (or norm-bound) of the semigroup under time-discretization is investigated in a Banach space setting. Preservation of …
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Theoretical and numerical results for electrorheological fluids
… pressure stabilization, fully implicit Euler time discretization, and Meyer type estimates.
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A Solution of the Heat Equation with the Discontinuous Galerkin Method Using a Multilivel Calculation Method That Utilizes a Multiresolution Wavelet Basis
… the Discontinuous Galerkin Method for space and time discretization. A multilevel method is employed in the space variable. It is shown that use of this process yields the same level of accuracy as the standard Discontinuous Galerkin Method for the heat equation, but with cheaper computational …
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Improved Collocation Methods With Application to Six -Degree -of -Freedom Trajectory Optimization
… are problems in which there are two distinct timescales of the system states, that is, where a subset of the states have high-frequency variations while the remaining states vary comparatively slowly. In conventional collocation, the timescale for the discretization would be set by the need to …
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Estudo comparativo de algoritmos de integração direta, aplicados a problemas de condução de calor transiente
… in space, by the use of the Finite Element Discretization Technique, using the curved isoparametric "quadrilateral" element. For time discretization, the Hermitians-Operators were used. The development of a digital computer program in FORTRAN was done and several examples were given to …
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Implementation and experiments with the discontinuous Galerkin method for Maxwell's equations
… and error analysis; comparison of different time discretization schemes, which are not strictly part of DGM; reduction of computation time with the use of adaptive time steps; and analysis of accuracy of absorbing boundaries in scattering problems. A discussion listing advantages and …
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ΕΝΕΡΓΟΣ ΕΛΕΓΧΟΣ ΤΩΝ ΚΑΤΑΣΚΕΥΩΝ
… OF STRUCTURES UNDER DYNAMIC LOADING THE SUITABLE TIME DISCRETIZATION SCHEME IS APPLIED. IN THE FRAMEWORK OF THE THEORY OF INFINITE DISPLACEMENTS WITH LINEAR CONSTITUTE LAWS, THE STATE RELATION TAKES THE FORM OF LINEAR DYNAMIC SYSTEMS OF CONTINUOUS TIME. MATRIX APPEARING IN THIS PROCEDURE HAVE A …
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Reinforcement Learning for Self-adapting Time Discretizations of Complex Systems
… self-adapting numerical algorithms for the time discretization of complex real-world problems with Q-Learning methodologies. The specific application is ordinary differential equations which can resolve problems in mathematics, social and natural sciences, but which usually require …
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Efficient multiscale methods for micro/nanoscale solid state heat transfer
… transport equation (BTE) in the relaxation-time approximation for describing small-scale solidstate heat transfer. We first discuss a Monte Carlo (MC) solution method that builds upon the deviational energy-based Monte Carlo method presented in [J.-P. Péraud and N.G. Hadjiconstantinou, …
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Domain Decomposition Methods for Convection-Diffusion-Reaction Equations with Finite Volume Discretizations
… (CDR) model with the finite volume discretization are studied. Both overlapping and non-overlapping domain decom- position (DD) preconditioning methods are considered. With overlapping DD preconditioners, we work on a time dependent CDR model. The additive Runge-Kutta (ARK) scheme is …
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An incremental total Lagrangian formulation for general anisotropic shell-type structures
… transient analysis Newmark scheme is adopted for time discretization. An iterative solution procedure, either Newton-Raphson method or modified Riks/Wempner method, is employed to trace the nonlinear equilibrium path. The latter is also used to perform post-buckling analysis. A variety of …
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Indoor Positioning Using Synchronized Ultrasonic OFDMA Signals
… of imperfectly orthogonal signals due to a time-discretization error imposed by the clock of the transmitter's general purpose microcontroller. This error is theoretically and experimentally analyzed yielding closely matching values.</p>
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Model Reduction of Nonlinear Fire Dynamics Models
… effort to be useful in design and real-time decision making, especially when dealing with fires over large domains. To reduce the computational time while retaining the complexity of the domain and physics, our research has focused on several reduced-order modeling techniques. Our …
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Revenue management and learning in systems of reusable resources
… optimization for reusable resources under time-homogeneous demand. We demonstrate that a simple randomized policy achieves at least one half of the optimal revenue in both the pricing and assortment settings. Further, when prices are fixed a priori, we develop a method to compute the …
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From efficient high-order methods to scientific machine learning.
… on the efficient implementation of implicit time discretization schemes, achieving computational savings by exploiting the structure of serendipity elements and developing a wrapper that integrates Machine Learning with FEM packages. First, we focus on implicit Runge-Kutta methods which …
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Multiphase Flows In Vertical Pipelines
… is elaborated by discretizing the space and time scale and evaluating the flow physical variables’ dynamics along the pipe. The employed quasisteady state momentum equation numerical resolution results in more than one root, known as the multiple root problem. A mathematical constraint, …
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From efficient high-order methods to scientific machine learning.
… on the efficient implementation of implicit time discretization schemes, achieving computational savings by exploiting the structure of serendipity elements and developing a wrapper that integrates Machine Learning with FEM packages. First, we focus on implicit Runge-Kutta methods which …
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Level set methods for higher order evolution laws
… by standard linear finite elements. For the time discretization a semi-implicit discretization scheme is employed. The derivation of the numerical schemes is presented in detail, and numerous computational results are given for the 2D and 3D situation. To keep computational costs low, the …
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Adjoint based solution and uncertainty quantification techniques for variational inverse problems
… and the associated emph {adjoint model} multiple times. In practice, our knowledge of the underlying physics is incomplete and hence the associated computer model is laden with emph {model errors}. Similarly, it is not possible to measure the physical quantities exactly and hence the measurements …
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Opacity Verification and Fault Diagnosis in the Framework of Switching Output Automata
… but lack native timing semantics, while dense-time formalisms such as timed automata face undecidability or prohibitive complexity for verification tasks involving both timing constraints and partial observability. This dissertation introduces the Switching Output Automaton (SOA) framework to …
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