Digital Commons Network^™

Numerical Solutions Of Poisson's Equation In A Superlatice Device, Norman Todd Rollins

Retrospective Theses and Dissertations

The relationship between the built-in potential and the energy bands in a heterojunction device is defined using the Anderson model. Based on this model, Poisson's equation for a nonhomogeneous semiconductor device in thermal equilibrium is derived and solved analytically for the special case of a doubly intrinsic abrupt heterojunction. Several numerical methods of solving Poisson's equation for general cases are explored to find the most efficient method. The validity of the chosen numerical method is tested against both the analytical solution for a Ge/GaAs doubly intrinsic diode and recently published results from similar numerical simulation studies. A p-i-n superlattice device …

A Modified Extended Kalman Filter As A Parameter Estimator For Linear Discrete-Time Systems, Bruno Johannes Schnekenburger

Theses

This thesis presents the derivation and implementation of a modified Extended Kalman Filter used for Joint state and parameter estimation of linear discrete-time systems operating in a, stochastic Gaussian environment. A novel derivation for the discrete-time Extended Kalman Filter is also presented. In order to eliminate the main deficiencies of the Extended Kalman Filter, which are divergence and biasedness of its estimates, the filter algorithm has been modified. The primary modifications are due to Ljung, who stated global convergence properties for the modified Extended Kalman Filter, when used as a parameter estimator for linear systems.

Implementation of this filter is …

Aircraft Vertical Profile Implementation Using Directed-Graph Methods, L. T. Brewster, Paul D. Stigall

Electrical and Computer Engineering Faculty Research & Creative Works

Aircraft Vertical Profile Simulation is Realized using a Demand-Driven Minimal-Calculation Directed Graph Structure to Reduce Calculation Time and to Force Synchronization of the Performance Measurement Functions with the System State Variables. Performance-Directed Model Adaptation Makes Dynamic Vertical Profile Path Corrections, in the Presence of Fixed Drag Variations, Possible. Drag Variations Ranging from + 10 Percent to - 10 Percent Yielded Fuel Consumption Improvements of Less Than 1 Percent in the Majority of the Cases. Calculation Time Improvement for Path Simulation Ranges from a Factor of 1.19 in the Worst Case to 1.5 in the Best Case. © 1988 IEEE

Voltage Controlled Resistance Model For Mos Transistors, Joey Zong-Yi Jia

Dissertations and Theses

The voltage controlled resistance model is developed for a reliable MOS transistor resistance mapping. The model includes both system and local parameters, and incorporates the effect of rise and fall time variations on the gate delay. MOS transistor resistance mapping is applied in logic simulation and timing verification. Also, it can be used in automatic transistor sizing and critical path analysis.

Safety Related Model And Studies Of Trojan Nuclear Power Plant Electrical Distribution System, Hamidreza Sharifnia

Dissertations and Theses

The most important requirement for running a nuclear power plant safely is having a reliable safety system, especially during the emergency shutdown condition. For performing a scrutiny load flow and voltage drop study a detailed and comprehensive electrical model for the emergency electrical distribution system of the Trojan Nuclear Power Plant has been developed. This model includes the representation of the transformers, circuit breakers, motors, cables and load data from 4160 volts level down to the individual 480 volts loads.

Microprocessor Controller For A Multi-Targets System, Shoeineng Lin

Theses

This thesis presents a microprocessor controller for a multi-targets system, which is designed by a direct digital control in the modern computer-aided manufacture system. It is made up of digital control theory, computer hardware configuration and software algorithm. An example is illustrated by IBM PC/XT computer. In this example, the control laws of three simple targets are developed and implemented by C-language. Simultaneously, the computer self-test routines, such as CPU, ROM etc, are developed by intel-8088 assembly language.

Two-Dimensionat Studies Of Streamers Fn Gases, S. K. Dhali, P. F. Williams

P. F. (Paul Frazer) Williams Publications

We present the results of two-dimensional computer simulations of streamer initiation and propagation in atmospheric pressure N₂. The simulation algorithm makes use of flux-corrected transport techniques and was used as a tool to study the solutions of the transport equations under conditions suitable for streamers, for which realistic analytic solutions are not known. We present and discuss conclusions about streamer transport based on the results of these studies. Finally, we present a novel method of checking on the numerical accuracy with which the algorithm solves the transport equations.

Pulse-Train Instabilities In A Mode-Locked Argon Laser: Experimental Studies, Duncan Leo Macfarlane, Lee W. Casperson

Electrical and Computer Engineering Faculty Publications and Presentations

The output train of pulses from an acousto-optically mode-locked argon-ion laser was studied as a function of the loss modulation frequency for small detunings from the optimum c/2L modulation. A shift away from the optimum frequency by as little as 1 part in 10⁴ was found to produce several strong lower-frequency components that amplitude modulate the mode-locked pulse train. Notably, the strongest subharmonic is a frequency near ƒopt/4. Further detuning results in an irregular, slow (of the order of 10⁵ Hz) amplitude envelope on the pulse train. The homodyne spectrum of this phase of operation represents a progressive filling-in behavior …

Transient Stability Simulation By Waveform Relaxation Methods, Marija D. Ilić, M. A. Pai, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a new methodology for power system dynamic response calculations is presented. The technique known as the waveform relaxation has been extensively used in transient analysis of VLSI circuits and it can take advantage of new architectures in computer systems such as parallel processors. The application in this paper is limited to swing equations of a large power system. Computational results are presented.

Moment Method Analysis Of The Electric Field Under Ehv Transmission Lines, T. L. Simpson, Charles W. Brice

Faculty Publications

The charge moment method is applied to the analysis of electric fields under EHV transmission lines over irregular terrain.

Model Of Hot-Film Sensor With Substrate Effects, David Mcalpine Judge

Electrical & Computer Engineering Theses & Dissertations

A detailed mathematical model is constructed to investigate the frequency response of a hot-film anemometer system. Since several diverse factors affect the frequency response, the analysis is broken down into three main parts. Each part is a detailed mathematical model. The first model consists of the ordinary differential equations which govern the electronics of the feedback system and heat transfer of the sensor. An important simplification in this model is that the rate of heat conduction from the sensor to its substrate is constant.

In the second model the unsteady state heat transfer properties of the substrate are examined by …

Computered-Aided Digital Filter Design And Simulatio, Pao-Tsan Chiang

Theses

The simulation is written by C language on AT&T Unix pc 7300 environment, some fundamental mathematics is introduced in the beginning, then digital filter specification method: window, frequency sampling, equiripple are discussed, and Kaiser window method is discussed in details for programming.

There are many problems are met in my simulation, such as F.F.T. aliasing, leakage, Picket fence convolution, correlation, but solutions are proposed.

The result could be output data and graph, GSS_Drivers graph package is utilized, because consideration of operation speed and convenience are emphasized, speed is compromised, but easy to be restructured.

A Dsp Toolkit For The Unix/C Environment Of The Pc 7300 Compute, Suwutchai Jesdanun

Theses

The Digital Signal Processing (DSP) TOOLKIT is a package of programs designed to use the fast Fourier transform (FFT) and display its output responses in graphics form. This tool provides three different window functions and five data modifiers for filter designing and spectrum analysis. Flexible features for modifying the plottings, such as y-axis auto-scaling, xy-axis scaling and center line adjusting of the graphics display, are included.

All programs are written in C programming language for the UNIX System Environment of the UNIX PC 7300 computer. The program structure of DSP TOOLKIT is designed so that modules can be added or …

The Relationship Between Linguistic And Image Based Learning Approaches For Complex Problem Solving: A Case For Computer Generated Animation In Instructional Presentation Of Complex Technical Processes, Stanley T. Bissinger

Graduate Research Papers

The purpose of this study is to provide a rationale for development of new approaches to educating students about complex technical processes. This study may also prove helpful for determining what type of technical content is better suited for computer animated presentation.

A Computer-Aided Design And Manufacturing System For Wiring Boards Production, Shiau Chia-Ming

Theses

Our purpose is to build some SBC-8052-BASIC microcontroller based instrument systems, and this thesis integrate resources from two areas into a powerful CAD/CAM system for this purpose. Since wiring board is the most popular used tool for laboratory development and small-scale manufacturing, a microcomputer-aided design and manufacturing system is developed to improve the whole efficiency from wirelisting and wiring sequences to hardware and software debugging. So anytime a circuit theory design stage is finished, the prototype can be made easily, then tested and redesigned, till last stage producing. Several practical wiring board circuits have been made through this system, it …

Microcomputer-Based Automated System To Monitor Flow And Respiratory Quotient, Chung C. Chien

Theses

An instrument system has been designed to monitor Respiratory Quotient experiments on rats which are living within whole-body calorimeters. By using multiplexing techniques, this system is capable of monitoring Respiratory Quotients in six calorimeters (animal chambers). It exhibits some features that make it more versatile than the previous system. One of the features of this instrument is that it uses a more accurate method of determining rapid changes in gas exchange between subject and environment. The value of this method is its ability to assess the rapid change in metabolic rate which occurs as a result of change in activity, …

A Data Compression System Using Arithmetic Code, Seokrim Choi

Theses

Generally it is difficult to compress data, from statistically unknown sources, with significant compression ratio. To achieve this, the compression scheme should have an ability to gather context information of the source, adaptively. For better compression, it is desirable to separate the context gathering scheme from coding itself. Arithmetic code is very flexible and can accept any kind of context gathering scheme which can generate probabilities. One context gathering algorithm which generates Markov type probability adaptively is studied and implemented in software using Arithmetic code. This scheme performs well and results in compression ratio better than any existing algorithms such …

Ksc2408 Digital Filter Evaluation System For The Ecg, Chi-Tong Chung

Theses

A hardware implementation in digital filters by using the high speed and high precision KSC2408 digital filter chips, demonstrates the power of the KSC2408 and proves that the real time digital filters can be implemented without complex circuitry and without high expense.

The system consists of two parts - the digital filter board and the IBM PC; the former handles the data filtering, the latter handles the analog-to-digital data conversion and data display. The KSC2408 is programmed as a 16th order Butterworth digital filter to have flat response in the passband and good attenuation in the stopband.

Investigation Of The Size Of Gallium Clusters Formed Using A Modified Ion Cluster Beam Source With A Crucible Temperature Of 1250 Degrees C, Sujit M. Shah

Theses

Energy analysis of the ionized gallium clusters was done by retarding field method. The objective of this research was to investigate the possibility of gallium cluster formation during nozzle jet expansion and to estimate the probability of ionization of clusters. The measurements at a crucible temperature of 1250°C corresponding to gallium vapor pressure of 0.23 torr (inside the crucible) showed that no large cluster sizes could be obtained. The relationship between mass deposition rate (atoms/cm2-sec) and cluster size (atoms/cluster) showed that there were two distinct peaks. One with a cluster size of 1 atom/cluster and the other with about 13 …

Graphical Interpretation Of U.S. Tidal Data, Vaheh Shahbazian

Theses

Numerous Shore line operations relating to industry and conservation would benefit from convenient access to continuous tidal predictions. Easy Graphical access to continuous long term predictions of tidal heights at a location of interest will simplify operations that are sensetive to tidal predictions. A specific example, is the implementation of a protective measurements against flooding and destruction of shoreline facilities particularly at times of high tides.

This thesis consists of three things. First, rendering NOAA's data in a form accessable to a PC user. Second, it provides a Basic program for prediction of tides. Third , PC user programming Resourses …

Reliability Studies On Microcircuit, Salim Shehadeh

Theses

The primary objective of this thesis is to determine and analyze the failure mechanisms of Low Power Schottky microcircuit device (2-Input NAND Gate). Pinpoint the causes, and suggest the precautionary measures that prevent the occurrence of these failures. To achieve this goal, the study went in two directions, theoretical and experimental. The theoretical part is a comprehensive review of the work done on Low Power Schottky 2-Input NAND Gates since 1960 up to date.

The experimental part of the study is a life test ( 1000 hours ) of 2-Input NAND Gates under humidity and high temperature.

For each unit, …

Method Of Moments Analysis Of Very Thin Wires Using The Mini-Numerical Electromagnetics Code, Douglas F. Stolarz

Theses

The analysis of thin wire antenna systems in the presence of a conducting ground plane is an important engineering problem. This thesis presents an analysis of wire radiators using the method of moments as implemented in the Mini-Numerical Electromagnetics Code (MININEC). Due to singularities in the formulation, MININEC yields inaccurate results for very thin wires. This code was modified by introducing filament currents for very thin wire structures thereby eliminating inaccuracy due to the treatment of singularities.

The modified code was tested on a monopole over a perfect ground, symmetrical and asymmetrical dipoles in free space, and inverted L and …

Probabilistic Technique In Power Flow Analysis, Dun-Ren Tzeng

Theses

This thesis describes and examines a technique which permits the power flow problem in a power system to be analyzed probabilistically. Both the deterministic and the probabilistic power flow theories have been presented. A mathematical model and a program have been developed to carry out the probabilistic power flow calculation. Two power systems and seven different loading cases have been used to test the technique. The results including the sensitivity coefficient matrices, the expected line flows with their variances, and 25 of 176 probability density function curves, have been shown and discussed. An easy way to predict the possible abnormal …

Weighted Least Square State Estimation In Power System, Jinn-I. Wu

Theses

In this thesis two methods for power system real-time monitoring are presented, programed and tested. Method 1 is not new and method 2 is a modification of method 1. The two methods are comparable in performance and they solve the problem satisfactorily.

These methods are iterative and the problem of choosing a convergence criterion is unexplored yet. This problem has been discussed, guidelines are presented to select an optimal convergence criterion.

The concept of confidence level and techniques for error detection are investigated. programs to detect bad data and to establish a confidence level have been written and some tests …

Time Series Analysis Of Respiration Component In Heart Rate Variability, Anuradha Ramaswamy Iyengar

Theses

Time series signal processing techniques (Fourier based) were applied to analyze the relationship between heart rate and respiration. This analysis takes advantage of the different timing charecteristics of the autonomic nervous system inputs to analyze their influence on the heart rate.

Data from three experiments were analyzed. The first set of data was from helicopter pilots of the US Army. They injected atropine into themselves on certain days. The effect of atropine on the heart rate spectrum and the relationship between heart rate and respiration was studied. It was found that atropine abolishes the respiration peak in the heart rate …

Mizer : A Ruled Based Cad Tool For Logic Optimization, Sandip Mukerjee

Theses

This objective of this research was to develop a knowledge based CAD tool, to address the problems of Logic Design. MIZER is an expert system, that accepts functional specifications of a logic circuit and connectivity description of its implementation to generate an optimal design. This information is then used to develop a hazard free circuit that brings about an optimization in area and timing. It stores the newly created design into its knowledge base with the approval of the designer, for future use.

Analysis Of An Inertial Navigation System On A Silicon Wafer, Ashok K. Parida

Theses

This thesis describes a self-contained inertial navigation system for commercial vehicles. It is low cost miniature system employing some of the newest techniques in micromechanical and microelectronic hardware.

The system employes an array of vibrating tuning fork gyros, a number of feedback force-balance accelerometers, and a central processing unit, all fabricated on a silicon wafer using integrated circuit fabrication technology. A miniature platform (size of a golf ball) driven by gearless torque motors is used to provide a quiet environment for the gyros and accelerometers. There are radio links between components that are on and off the platform (eliminating need …

Synthetic Aperture Multi-Telescope Tracker Apparatus, Richard A. Carreras, Salvatore J. Cusumano, Morton B. Jenks, Robert I. Suizu

AFIT Patents

A plurality of telescopes provide output return signals which are applied both directly and in sampled form to a photo-detector cell. The detected signals from the photo-detector will represent the constant and transient errors of the telescope system. A low pass filter insures that the tracker provides only the constant or D.C. component of the error, while a high pass filter insures that the existing measuring devices for each telescope beam provide only the transient or A.C. component of the error. The A.C. and D.C. error signals are summed together with the appropriate applied gains on each channel such that …

Antireflection Of An Absorbing Substrate By An Absorbing Thin Film At Normal Incidence, R. M.A. Azzam, E. Bu-Habib, J. Casset, G. Chassaing, P. Gravier

Electrical Engineering Faculty Publications

An absorbing substrate of complex refractive index n₂ - jk₂ at wavelength λ can be coated by an absorbing thin film of complex refractive index n₁ - jk₁ and thickness d to achieve zero reflection at normal incidence. For given n₂,k₂ multiple solutions (n₁,k₁,d/λ) are found that correspond to infinitely many distinct antireflection layers. This is demonstrated for a Si substrate at two wavelengths (6328 and 4420 Å). The response of these absorbing antireflection layers to changes of the angle of incidence from 0 …

Fast Thermal Generation Rescheduling, F. Eugenio Villaseca, B. Fardanesh

Electrical and Computer Engineering Faculty Publications

A new dynamic programming algorithm for fast rescheduling thermal generation is presented. The savings in computational times are brought about by the introduction of two new techniques: the variable truncation dynamic programming and the limitation of the solution space to be searched. Several examples on a 20 machine system are used to illustrate the application of the algorithm and to show that optimal solutions are obtained at significantly reduced computational times.