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 84 for “"Numerical stability"”.
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Numerical stability of Monte Carlo neutron transport and isotopic depletion for nuclear reactor analysis
… strongly contributing to previous reports of instability. It is shown that attempting to minimise clustering effects produces more stable burn-up calculations. Furthermore, accounting for clustering is shown to allow for the accurate simulation of xenon transients in simple systems which have …
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Experimental and numerical stability analysis of cable in conduit superconductor for the ITER project
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1997.
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Control of a nonlinear underactuated system with adaptation, numerical stability verification, and the use of the LQR Trees algorithm
… a suitable Lyapunov Candidate used for proofs of stability, with claims of local stability made using Barbalat's Lemma. This provides us with a local domain of attraction for the altered classical nonlinear adaptive controller. In addition, the algorithm known as LQR Trees is applied to the system …
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High-Order and Wavelet-Adaptive Immersed Methods for PDEs on Complex Domain Geometries
… methods brings a promising solution to the numerical simulation of interface-coupled multi-physics problems, such as multi-phase flows and fluidstructure interactions. This renders necessitates the design of novel high-order and efficient solvers based on immersed methods. This thesis …
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Accelerated gradient techniques and adaptive signal processing
… convergence speed, computational complexity and numerical stability. Extensive simulation results are presented to demonstrate the performance of the proposed algorithms when applied to the fields of adaptive noise cancelling, broad band adaptive array processing and narrow band adaptive spectral …
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High-Order Finite-Difference Schemes and Their Application to Computational Acoustics
<p>The primary focus of this study is upon the numerical stability of high-order finite-difference schemes and their application to duct acoustics. Since acoustic waves are known to be non-dissipative and non-dispersive, high-order schemes are favored for their low dissipation and low dispersion …
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Characteristic function pricing with the Heston-LIBOR hybrid model
… model. We also implement measures to improve the numerical stability of the characteristic function derived in this dissertation as well as the one derived by Grzelak and Oosterlee. The ultimate aim of the dissertation is to prevent these characteristic functions from exploding for given parameter …
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Scalar Scattering Theory and Physics-inspired Optimization for Computational Imaging
… solving the TIE, which significantly enhances numerical stability, and discusses the analytical relationship between non-paraxial formulations and conventional phase retrieval methods, deepening our understanding of the field. In the domain of optical scattering, where information in photons is …
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Numerical solution of multicomponent population balance systems with applications to particulate processes
… better understand particle formation mechanisms, numerical solutions could be employed, however current numerical solutions are generally restricted to a either a limited selection of growth laws or a limited solution range. This lack of modeling ability precludes the accurate and/or fast solution …
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Broadband Macromodeling Techniques for Interconnects and Electronic Packages
… characteristics of the structures such as stability, causality, and passivity are preserved during the model construction. Also, a new method is formulated based on vector-fitting method in z-domain. It has the advantage of faster convergence and better numerical stability compared to the …
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Simulation methods for polydisperse, multiphase flows using moment methods
… of physical system, there is currently a lack of numerical solution methods to solve for these types of flows. In this work, three new numerical procedures are developed in order to accurately solve for systems containing polydisperse multiphase flows, and flows with velocity distributions. The …
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An Improvement of Convection Fidelity in Euler Calculations
… in Euler calculations by eliminating the numerical diffusion inherent in conventional approaches. In conventional approaches which solve for the time-dependent conservation equations, the numerical diffusion is either built-in through finite truncations or added externally for reasons of …
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A 3-dimensional H-adaptive algorithm for groundwater flow and contaminant transport
… weighting of the advection terms provides numerical stability. An explicit time marching scheme is used to solve the transient equations. By utilizing unstructured adaptive meshing, concentration is accurately resolved; Benchmark cases were used to check the feasibility of GWADAPT3. The …
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A Fast Timing Simulator With Accurate Reduced-Order Interconnect Models
… models is further improved to achieve absolute numerical stability in addition to their theoretical passivity and stability. Unlike other approaches, the interconnect simulation methods in ILLIADS-I do not handle the interconnect network separately for obtaining and then placing a corresponding …
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Domain partitioning to bound moments of differential equations using semidefinite optimization
… domain and normalizing each partition to ensure numerical stability. Using the adjoint operator, linear constraints involving the boundary conditions and moments of the solution are developed for each partition. Semidefinite constraints are imposed on the moments, and an optimization problem is …
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A Numerical Method for solving the Periodic Burgers' Equation through a Stochastic Differential Equation
… partial differential equations (PDEs), can be numerically challenging for small values of the viscosity parameter. For example, these equations can develop discontinuous solutions (or solutions with large gradients) from smooth initial data. Aside from numerical stability issues, standard …
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Constrained Optimization on SO(3), via Pseudospectral Collocation
… settings. The proposed formulation improves numerical stability and computational efficiency by combining the spectral properties of LGL collocation with the computational advantages of the Cayley transform. The LGL-based constrained optimization preserves the geometry and is more …
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A computer model for sound propagation around conical seamounts
… field in each layer. In order to maintain numerical stability, the Direct Global Matrix approach is used. The radial eigenfunctions are expressed as functions of normalized Hankel and Bessel functions, and the linear system that arise is organized in an unconditionally stable matrix. The …
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Resolution of grain scale interactions using the Discrete Element Method
… systems. Currently, a popular tool for numerically investigating granular systems is the Discrete Element Method (DEM). Nearly all implementations of the DEM, however, use spheres to represent particles despite mounting evidence showing that shape at multiple scales (sphericity, …
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Magnetic-field-induced antiferromagnetism in the Kondo lattice
… operations are specially organized to maintain numerical stability down to arbitrarily low temperatures. Spectral data is extracted from the imaginary-time correlation functions using an improved analytic continuation technique. The weak, secondary peaks of the single-electron spectral function …
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