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 100 for “"Gradient method"”.
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A gradient method for optimizing stochastic systems
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1964.
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A Modified Preconditioned Conjugate Gradient Method for Approximating the Scattering Amplitude
<p>In this thesis, we look at an iterative method for approximating the scattering amplitude that involves solving two linear systems: a forward system A<strong>x</strong>=<strong>b</strong> and an adjoint system A<sup>T</sup><strong>y</strong>=<strong>g</strong>. Once these two systems are solved, …
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Construction of Centroidal Voronoi Tessellations Using A Conjugate Gradient Method Based On Trust Regions
… new algorithm for computing CVTs--the conjugate gradient method based on trust regions (CGTR). This algorithm significantly speeds up the computation of CVTs. Numerical experiments are also conducted to substantiate theoretical analysis.</p>
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The Gradient Method of Sensitivity and a Study of Stability of Antibiotics in Agar
The fundamentals of antibiotic therapy and laboratory investigations have been fully explored for more than a decade since penicillin was made available for general use. Investigators delved into their mode of action and factors influencing their activity and the correlation between in vitro …
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Optimization Based Domain Decomposition Methods for Linear and Nonlinear Problems
Optimization based domain decomposition methods for the solution of partial differential equations are considered. The crux of the method is a constrained minimization problem for which the objective functional measures the jump in the dependent variables across the common boundaries between …
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From Proximal Point Method to Accelerated Methods on Riemannian Manifolds
… a Riemannian analog of Nesterov's accelerated gradient method (AGM). In this thesis, we establish the first globally accelerated gradient method for Riemannian manifolds. Toward establishing our result, the first part of the thesis revisits Nesterov's AGM and develops a conceptually simple …
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The direct determination of nonlinear displacements of arbitrarily supported shallow shells using mathematical programming techniques
… for minimizing the shell potential several methods which have appeared in the literature are evaluated. These include the method of steepest descent, the conjugate gradient method, the variable metric method and the generalized Newton-Raphson procedure. A combination of the conjugate …
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Adaptive finite element simulation of incompressible viscous flow
A finite element method is employed for solving two- and three-dimensional incompressible flows. The formulation is based on a segregated solution method. In this segregated formulation, the velocities and pressures are uncoupled and the equations for each are solved one after the other. This …
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Sample Complexity of Incremental Policy Gradient Methods for Solving Multi-Task Reinforcement Learning
… this problem, we are interested in studying the gradient approach, which iteratively updates an estimate of the optimal policy using the gradients of the value functions. The classic policy gradient method, however, may be expensive to implement in the multi-task settings as it requires access to …
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Dynamic relaxation analysis of pretensioned networks supported by compression arches
… with the application of direct integration methods, particularly Dynamic Relaxation, to the nonlinear formfinding and analysis of pretensioned networks supported by compression arches. The development and application of such methods is reviewed in Chapter 2. The automated control of Dynamic …
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A Parallel-In-Time Gradient-Type Method For Optimal Control Problems
… proposes and analyzes a new parallel-in-time gradient-type method for time-dependent optimal control problems. When the classical gradient method is applied to time-dependent optimal control problems, each iteration requires the forward solution of the state equations followed by the backward …
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Asymptotic Behaviour and Derivation of Mean Field Models
… asymptotic behaviour of the Arrow-Hurwicz-Uzawa gradient method, which is a dynamical system for locating saddle points of concave-convex functions. This method is widely used in distributed optimisation over networks, for example in power systems and in rate control in communication networks. …
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Polynomial Preconditioning for Conjugate Gradient Methods
… If A is large and sparse, an iterative method is required. When A is hermitian positive definite (hpd), the conjugate gradient method of Hestenes and Stiefel is popular. When A is hermitian indefinite (hid), the conjugate residual method may be used. If A is ill-conditioned, these …
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Method comparison for analysis of LNAPL natural source zone depletion using CO₂ fluxes
… the vadose zone. Building on this concept, three methods have recently emerged to quantify rates of NSZD using soil gas fluxes; these include the gradient, chamber, and trap methods. Unfortunately, side-by-side field applications of the methods have shown differing estimates of NSZD, leaving …
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EFFECTIVE TRAINING OF NEURAL NETWORKS FOR BETTER GENERALIZATION
… We propose DRAG, a dimension-reduced adaptive gradient method that unifies the benefits of SGD and Adam, and a memory-efficient Shampoo using 4-bit Cholesky quantization with error feedback, enabling scalable second-order training. From the data side, we investigate why data-centric strategies …
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Elementos finitos para a análise limite de cascas axissimétricas via programação não-linear
… technique (SUMT), the generalized reduced gradient method and the tolerance flexible method are utilized for statically admissible and kinematically admissible approaches. Therefore, upper bounds and lower bounds of the collapse loads are found for some problems: conical, spherical, …
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A Parallel Aggregation Algorithm for Inter-Grid Transfer Operators in Algebraic Multigrid
… approaches to solve such problems. Multigrid methods can be used to solve large-scale problems, or even better they can be used to precondition the conjugate gradient method, yielding better results in general. Capabilities of multigrid algorithms rely on the effectiveness of the inter-grid …
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Heat transfer, evaporation and carbon dioxide transfer in soil
… daily evaporation estimated from the heat pulse method agreed well with the daily evaporation estimated from Bowen ratio and micro-lysimeter methods. The results showed that heat pulse sensors alone could accurately determine subsurface soil water evaporation with time and depth, and surface and …
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Investigating a Second-Order Optimization Strategy for Neural Networks
… investigates the application of the conjugate gradient method CG for the optimization of artificial neural networks (NNs) and compares this method with common first-order optimization methods, especially the stochastic gradient descent (SGD). The presented research results show that CG can …
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