Computational Engineering Commons^™

Variable Step Size Lms Adaptive Filters With Delayed Coefficient Updating, Guixian Xu

Electrical & Computer Engineering Theses & Dissertations

A new approach to delayed LMS adaptive filtering is presented, which uses a variable step size for coefficient updating to increase convergence speed and improve tracking characteristics. The new algorithm, called delayed variable step size LMS (DVLMS), is explained, analyzed, and simulated to experimentally determine performance characteristics. Three different strategies for adjusting the step size are examined, and their performance is compared. Also, simulation results are presented to show that the proposed DVLMS systems provide faster convergence and lower mis-adjustment than previously proposed DLMS systems.

Fault Tolerant Pipelined Adaptive Systems, Bhasker Reddy Allam

Electrical & Computer Engineering Theses & Dissertations

A fault tolerant pipelined architecture for high sampling rate adaptive filters is presented in this thesis. The architecture is based on the computational requirements of delayed LMS and lattice adaptive 61ters. It offers robust performance in the presence of single hardware faults, and software faults resulting from numerical instability. Two different architectures are proposed. One allows a graceful degradation in system performance in the event of a fault, and the other uses a module replacement strategy to recover from faults without decreasing performance. Analysis of the steady state error increase due to filter reconfiguration is presented. The reliability of the …

Modeling And Simulation Of Load Introduction For Fuselage Crown Panel Testing, Kevin P. Belack

Mechanical & Aerospace Engineering Theses & Dissertations

This paper discusses the mechanism and behavior of load introduction to internally pressurized fuselage crown panels. Emphasis is placed on the finite element modeling of a simulated pressure-box test machine and representative fuselage crown panel. The geometry and mesh requirements for the finite element model are examined through numerical studies which gradually increase in complexity. These numerical studies culminate in the detailed specification of boundary conditions, mesh densities, load introduction mechanisms, element choice and solution process for the simulation of a pressure-box test machine and test panel.

The results obtained using the finite element model are then compared with experimental …

Generalization Metrics For Neural Modeling Applications In System Identification, Denise M. Reeves

Electrical & Computer Engineering Theses & Dissertations

In this thesis a procedure to design multilayer feedforward networks for system identification with good prediction properties is presented. Central to the design procedure is a means to characterize the prediction capabilities of various trained neural networks. Such knowledge will allow for the identification of the best network design. For system identification purposes, a "good" model is one that is good at predicting, In particular, a good model is one that produces small prediction errors when applied to a set of cross-validation data. We formulate and implement a criterion function designed to measure the size of a trained neural network's …

Transient Simulations And Modelling Of Semi-Insulating Gaas Photoconductive Switches, Prasun Kumar Raha

Electrical & Computer Engineering Theses & Dissertations

The primary objective of this thesis is to develop a one-dimensional transient simulator for Photoconductive Semiconductor Switches (PCSS) taking into consideration the material characteristics, the internal physical effects, and the external circuit. Simulations have been performed to study the device behavior at different voltage levels for copper-doped silicon-compensated GaAs material, though other materials could easily be simulated by changing the parameters. The model includes hole transport, and the results demonstrate the effect of hole injection, with and without recombination centers. In addition to developing a one-dimensional transient simulator, the role of various physical effects, such as the field-dependence of trapping …

Observation Of Inclusive B Decays To The Charmed Baryons C++ And C0, Procario, M.; Te Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

No abstract provided.

Cyclo-Static Scheduling Of Large Grain Dataflow Algorithms On A Local Area Atamm Multicomputing Testbed, Sudeepto Roy

Electrical & Computer Engineering Theses & Dissertations

A strategy for cyclo-statically scheduling deterministic large grain dataflow (LGDF) algorithms for distributed execution on loosely coupled multicomputer architectures is presented in this research. The computational paradigm used is the ODU/NASA developed Algorithm To Architecture Mapping Model (ATAMM), which consists of marked graphs and Gantt chart representations that model the iterative execution of deterministic LGDF algorithms for different values of throughput and computation time. It is postulated that the behavior of these algorithms could be represented by the aggregate execution of an ensemble of cyclically shifted threads of a specific node sequence. Assuming the existence of one or more such …

Monte Carlo Simulation Of Millimeter-Wave Gunn Effect Oscillators, Ramani Vaidyanathan

Electrical & Computer Engineering Theses & Dissertations

Monte Carlo simulations have been carried out to investigate the performance of microwave Gunn oscillators. Three separate aspects of the simulation problem have been comprehensively addressed in this work. First, the presence of an external circuit has been self-consistently incorporated into the calculations. The inclusion of the external circuit facilitates a study of the circuit controlled regime, and correctly models effects arising from the time dependent boundary conditions. Secondly, microscopic details of the electronic relaxation mechanisms which ultimately control the frequency response limits, have been taken into account through an iterative Monte Carlo-Poisson scheme. This procedure overcomes a potential shortcoming …

Encoding Phonetic Knowledge For Use In Hidden Markov Models Of Speech Recognition, Danming Qian

Electrical & Computer Engineering Theses & Dissertations

Hidden Markov models (HMM's) have achieved considerable success for isolated-word speaker-independent automatic speech recognition. However, the performance of an HMM algorithm is limited by its inability to discriminate between similar sounding words. The problem arises because all differences between speech patterns are treated as equally important. Thus the algorithm is particularly susceptible to confusions caused by phonetically-irrelevant differences. This thesis presents two types of preprocessing schemes as candidates for improving HMM performance. The aim is to maximize the differences between phonologically-distinct speech sounds while minimizing the effect of variations in phonologically-equivalent speech sounds. The preprocessors presented are a discrete cosine …

An Expert System For Failure Analysis Of Rotating Steel Shaft, Dalal Eissa Ahmed

Archived Theses and Dissertations

No abstract provided.

The Frontal Method For Finite Element Analysis On Ibm-3090 Vector Computer, Chaerul Kamal

Civil & Environmental Engineering Theses & Dissertations

In this report, a Finite Element program based on the Frontal method was implemented on the IBM-3090 to exploit the vector capabilities offered by modern high performance vector computers. The overall computational speed for the Frontal Finite Element program was increased by 30% when the vector instructions were introduced. The Frontal solution for a system of simultaneous linear equations, however, has shown only minor improvement when vector instructions were used. More improvement in computational speed and memory storage can be expected by using the Parallel Frontal method with Substructures.

A Reiner-Rivlin Fluid Flow Through Entrance Region Of A Circular Pipe, V. G. Masanja

Tanzania Journal of Engineering and Technology (TJET)

The flow of a Reiner-Rivlin fluid with two viscosity coefficients through the entrance region of a circular pipe has been studied numerically. In particular the growth of the entrance length as a function of the Reynolds number and the non-Newtonian parameters has been examined. Where comparison could be made, the results have been compared with existing experimental -and numerical data as well as the limited theoretical work available.

Dynamic Analysis Of Linear Structural System Using Ritz Vector Method And Substructuring Formulation, Vijay R. Modi

Civil & Environmental Engineering Theses & Dissertations

In this study, the substructuring formulation is incorporated into Ritz Vector method to obtain and solve the reduced system of dynamic equilibrium equations. Two-dimensional and three-dimensional truss problems are considered in the present study. The accuracy and computational time using the proposed technique are compared with known solutions. The effect of using different number of substructures and Ritz vectors are also investigated, equations solver is utilized to Moreover, a version of a parallel further enhance the numerical performance of the proposed technique on the FLEX/32 Multicomputer.

Synthesizing Inductive Expertise, Daniel N. Osherson, Michael Stob, Scott Weinstein

University Faculty Publications and Creative Works

We consider programs that accept descriptions of inductive inference problems and return machines that solve them. Several design specifications for synthesizers of this kind are considered from a recursion-theoretic perspective.

Design Of A Modulation System Simulator, Vincent Carl Dale

Computational Modeling & Simulation Engineering Theses & Dissertations

The development of a Modulation System Simulator is described. The Modulation System Simulator is used to investigate the performance, in the presence of noise, of various analog and digital modulation systems. The methods of modulation studied using this simulator are amplitude modulation, frequency modulation, pulse amplitude modulation, pulse code modulation, amplitude shift keying modulation, and frequency shift keying modulation. For each of these modulation systems a mathematical model is devised and then analyzed to predict the performance of each modulation system in the presence of noise. The results of this theoretical analysis are then compared with the experimental results obtained …

Design Of Efficient Algorithms Through Minimization Of Data Transfers, Yong Mo Chong

Electrical & Computer Engineering Theses & Dissertations

This thesis explores the time optimal implementation of computational graphs on a finite register machine. The implementation fully exploits the machine architecture, especially, the number of registers. The derived algorithms allow one to obtain time efficient implementations of a given graph in machines with a known number of registers.

These optimization procedures are applied to digital signal processing graphs. It is shown that the regular structure of these graphs allows one to identify computational kernels which, when used repeatedly, can cover the entire graph. The l- and r-register implementations of Hadamard and Fast Fourier Transforms using various computational kernels are …

Speech Spectral Modeling And Speech Synthesis Using Finite Impulse Response Digital Filters, Paul Edward Gordy

Computational Modeling & Simulation Engineering Theses & Dissertations

Synthetic speech can be produced using a discrete-time model of human speech production. This model depends on the use of digital filters to model the spectral characteristics of the vocal tract. Speech spectra can be efficiently encoded using a set of principal components basis vectors; however, these vectors are not in a convenient mathematical form for directly determining a digital filter for the speech production model. If discrete cosine basis vectors are used to approximate the principal components basis vectors, then the cosine basis vector coefficients can be used to determine a Finite Impulse Response(FIR) digital filter for speech spectral …

Comparison Of Steady-State Pipe Network Computer Programs, Michael Bernice Holloway

Civil & Environmental Engineering Theses & Dissertations

Four widely used computer programs for the analysis of steady state flows in pipe networks are compared. These programs are NEWTH, written by Jeppson; KENTUCKY, written by Wood; FLOW, written by Epp and Fowler; and LIQSS, written by Stoner. Differences, similarities, advantages and disadvantages of these programs, and various options available are discussed for the benefit of possible future users. In addition, the efficiency of NEWTH, KENTUCKY, and FLOW was tested by simulating a typical network by each program. The listing of LIQSS was not available, and thus was not included in this comparison. In simulation, KENTUCKY used over twice …

A Dimensionality Reduction Algorithm For The Karhunen Loeve Transform, Salomi T. Charalambous

Computational Modeling & Simulation Engineering Theses & Dissertations

The Karhunen Loeve Transform has conclusively been shown to be the optimum data compression algorithm for signals belonging to the same second order stationary process. Consequently, researchers have been searching for a fast implementation for the transform. Fast imple­mentation methods similar to those developed for other orthogonal transforms are generally not applicable to the Karhunen Loeve Transform (KLT). Also, since the basis vectors composing the transformation matrix of the KLT are the eigenvectors of the covariance matrix of the input process, they must be computed first. The research re­ ported here is an attempt to reduce the dimensionality of the …

An Efficient Dft Algorithm Using The Walsh Transform, Albert P. Gerheim

Electrical & Computer Engineering Theses & Dissertations

The matrix transformation relating the sequency and frequency domains is derived. It is shown that these­ frequency-to-frequency conversion can be performed via a computationally efficient sparse matrix algorithm. The sequency-to-frequency algorithm can be used with a fast Hadamard transform to implement a discrete Fourier trans­ form. The efficiencies of this combined algorithm and a radix-two fast Fourier transform are compared.

The algorithm is applied to the sequency domain de­ sign of a Wiener digital filter. Improved computational efficiencies are achieved relative to the procedure de­veloped by Kahveci and Hall (9).

Computer Solution To Inverse Problems Of Elliptic Form: V²U(X,Y) = G(A,U,X,Y), Frederick Alvin Jeter

Dissertations and Theses

One important aspect of our present age of monolithic high speed computers is the computer's capability to solve complex problems hitherto impossible to tackle due to their complexity. This paper explains how to use a. digital computer to solve a specific type of problem; specifically, to find the inverse solution of a in the elliptical equation V²U(x,y) = g(a,U,x,y), with appropriate boundary conditions. This equation is very useful in the electronics field. The knowns are the complete set of boundary values of U(x,y) and a set of observations taken on internal points of U(x,y). Given this information, plus …