Digital Commons Network^™

A Concept For Sled Testing Minuteman Iii Guidance Systems, Hossny El-Sherief, Dave Knight, Daniel J. Simon, Myron Teeter

Electrical and Computer Engineering Faculty Publications

No abstract provided.

Analysis And Characteristics Of Compressor Stall Precursor Signals In Forward And Aft Swept High Speed Compressor, Bernard J. Frank

Theses and Dissertations

The stall characteristic of four single-stage transonic compressor rotors were investigated as they were throttled to stall. Forward-swept, backward-swept, and straight leading edge rotors were examined. Three methods of analysis (1) windowed power spectrum densities of pressure and spatial Fourier coefficients, (2) phase tracking analysis, and (3) system identification were used to identify the first appearance of modal waves and their accompanying frequencies in order to identify a stall warning time. A direct correlation between the amount of stall warning time and the shape of the compressor characteristic was found. Specifically, if the compressor characteristic had a significant period of …

Partitioning Structural Vhdl Circuits For Parallel Execution On Hypercubes, Kevin L. Kapp

Theses and Dissertations

Distributing simulations among multiple processors is one approach to reducing VHDL simulation time for large VLSI circuit designs. However, parallel simulation introduces the problem of how to partition the logic gates and system behaviors among the available processors in order to obtain maximum speedup. This research investigates deliberate partitioning algorithms that account for the complex inter-dependency structure of the circuit behaviors. Once an initial partition has been obtained, a border annealing algorithm is used to iteratively improve the partition. In addition, methods of measuring the cost of a partition and relating it to the resulting simulation performance are investigated. Structural …

Weapon System Sensor Integration For A Dis-Compatible Virtual Cockpit, Matthew N. Erichsen

Theses and Dissertations

This thesis continues the Virtual Cockpit VC research which investigates distributed interactive virtual flying, environments. The VC vl.0 used the SIMNET protocols to only communicate position and orientation over a common network. A simple cockpit instrumentation configuration and limited head- tip display, HUD showed aircraft state. With VC vl.0 weapons or sensors could not interact in the simulation environment. The VC v2.0 transitions from the SIMNET protocol to a partial implementation of the Distributed Interactive Simulation DIS v2.0.3 protocol. Simulated radar and forward looking infra-red FLIR sensors were developed to aid operator detection and designation when employing various munition types. …

A Study Of Two Dimensional Tapered Periodic Edge Treatments To Reduce Wideband Edge Diffraction, Russell A. Burleson

Theses and Dissertations

This is a brief summary of a study to reduce diffraction from an infinite two dimensional edge using tapered periodic surfaces. The concept is to use the impedance characteristics of a periodic surface to create a tapered impedance much like a tapered resistance commonly used for diffraction reduction. This approach has several advantages over. tapered resistive treatments to include ease of fabrication, better engineering control of the impedance and negligible loss absorbed by the ta per. In this study, four periodic tapers were design, built and tested. These tapers were also modeled using a variety of numerical techniques. The results …

Analyzing Adaptive Beamformer Performance In A Stable Multipath Environment, Mark Godino

Theses and Dissertations

Fighter aircraft equipped with X-Band radars having an adaptive beamforming capability exhibit degraded performance due to radome multipath reflection (RMR). The reflections from the radome into the antenna array degrade the pattern and cause the formation of large sidelobes. This phenomenon makes detection of LO targets difficult when jamming enters the high RMR sidelobes. Actual radomes are curved and cause reflected wavefronts to be nonplanar. Analyzing beamformer performance under these conditions is difficult, since the beamformer response is defined as the amplitude and phase change experienced by a complex plane wave as a function of frequency and location. To work …

Analysis And Simulation Of A Gps Receiver Design Using Combined Delay-Lock And Modified Tanlock Loops, George D. Harris

Theses and Dissertations

The purpose of this thesis was to investigate the performance of two types of tracking loops used in Global Positioning System (GPS) receivers. The first loop, the Delay-Lock Loop (DLL), is responsible for maintaining synchronization with the received PN sequence. The second loop, the Modified Tanlock Loop (MTLL), is responsible for maintaining synchronization with the carrier signal. The performance of the two loops is investigated first separately then their performance is evaluated when operated together. This thesis is an investigation on the ability of these two loops to overcome corruption of the input signal due to noise. Expanding the dynamic …

Development Of A 4-Bit Parallel Analog-To-Digital Converter And A Four- Quadrant Double-Balanced Mixer Using Heterojunction Bipolar Transistor Technology, Scott F. Jokerst

Theses and Dissertations

A 4-bit parallel analog-to-digital converter (ADC) and a four- quadrant double-balanced mixer were designed and simulated using heterojunction bipolar transistor (HBT) technology to test the dc and high-frequency characteristics of HBTs. HSPICE simulations of small-scale components and the large-scale ADC operated within expected ranges. The ADC implemented with the Rockwell HBT model operated at a sampling rate of over 1 GHz, and the Fellows model also operated at a 1 GHz sampling rate. The mixer produced an intermediate frequency (IF) signal using radio frequency (RF) and local oscillator (LO) inputs. The circuit produced a +9 dB power gain with less …

An Analysis Of Fm Jamming And Noise Quality Measures, Timothy N. Taylor

Theses and Dissertations

This thesis provides a description of FM-by-noise jamming, both at RF and at the output of the radar receiver, in terms of spectra, time-domain waveforms, and univariate probability density of amplitude. Particular emphasis is given to the case where the peak frequency deviation of the FM modulator is sufficiently small that Woodward's Theorem does not provide a good approximation of the RF spectrum. Additionally, noise quality measures which have been used to measure noise quality of radar jammers are considered theoretically and experimentally, and it is concluded that a noise measure which incorporates both a spectral measure and a probability …

Hyperspectral Analysis Of Space Objects: Signal To Noise Evaluation, Daniel Hrovat

Theses and Dissertations

Hyperspectral analysis of space objects is being considered as a means of enhancing Space Object Identification. SOI capabilities. This study develops a mathematical simulation based on fundamental radiometry principles to evaluate the feasibility of hyperspectral analysis of space objects. The study uses Signal to Noise Ratio SNR as the basis for the feasibility evaluation, and addresses the question Is there enough target signal in narrow wavelength bandwidths to conduct hyperspectral measurements of space objects The analysis characterizes the target signal and noise sources using fundamental radiometry, and develops a flexible radiometry model which calculates the target signal count rate, and …

Objective Image Quality Metrics: Applications For Partially Compensated Images Of Space Objects, David J. Lee

Theses and Dissertations

Digital image reconstruction tasks currently require human intervention for a subjective evaluation of image quality. A method for unsupervised measurement of digital image quality is desired. This research investigated various parameters metrics that can be automatically extracted from a digital image and tested how well they correlated with image quality. Specifically, images of orbiting satellites captured by a partially compensated adaptive optics telescope were dealt with. Two different types of quantities were investigated 1) Fourier spectral parameters, based on the spatial- frequency sensitivities of the HVS; and 2) Histogram shape parameters i.e image statistical moments giving quantitative insight into the …

System Design Analysis Of A Lightweight Laser Satellite Terminal, Brian C. Page

Theses and Dissertations

This study investigated the technological feasibility of a man- portable satellite laser communications system. Areas of interest were an end- to-end system analysis on the communications link evaluation of atmospheric effects and evaluation of semi-conductor lasers as the laser source. A literature search revealed that satellite laser communication research is primarily directed at inter-satellite links. There have been some proposed systems for space-to-ground laser communications systems, but they all utilize large fixed ground stations. The focus of this research effort is directed at a small man-portable ground station capitalizing on recent advances in semiconductor laser devices. Baseline satellite communication systems …

Simple High-Quality Lossy Image Coding Scheme, Shaolin Bi, Khalid Sayood

Department of Electrical and Computer Engineering: Faculty Publications

A simple yet efficient image data compression method is presented. This method is based on coding only those segments of the image that are perceptually significant to the reconstruction of the image. Sequences of image pixels whose gray-level differences from the pixels of the previous row exceed two prespecified thresholds are considered significant. These pixels are coded using a differential pulse code modulation scheme that uses a 15-level recursively indexed nonuniform quantizer for the first pixel in a segment and a 7-level recursively indexed nonuniform quantizer for all other pixels in the segment. The quantizer outputs are Huffman coded. Simulation …

National Engineering Education Delivery System (Needs), Alice M. Agogino, Sheri Sheppard, Kate Mink, James G. Harris, Lawrence Genalo, Jaya Krishnagopalan, Dave Martin, John Saylor

Electrical Engineering

The Synthesis Coalition, supported by the National Science Foundation and industrial partners, is comprised of the following eight educational institutions: California Polytechnic State University at San Luis Obispo, Comell, Hampton, Iowa State, Southern, Stanford, and Tuskegee Universities, and the University of California at Berkeley (1].

The National Engineering Education Delivery System (NEEDS) is an entirely new courseware development and distribution system which will provide Widespread, rapid, electronic access to an almost arbitrarily large number of diverse instructional modules (2-4). Curricular material in the NEEDS database are organized by a diverse range of indices. Links across disciplines are provided in the …

Sensitivity Improvement Of A 1-Μm Ladar System Incorporating An Active Optical Fiber Preamplifier, Michael S. Salisbury, Paul F. Mcmanamon, Bradley D. Duncan

Electro-Optics and Photonics Faculty Publications

In an effort to increase the SNR of a continuous wave, 1-μm all solid state ladar system, a rare-earth-doped optical fiber amplifier is investigated as a preamplifier for ladar return signals. The experimental system is detailed and a theoretical analysis of the fiber amplifier's effect on both heterodyne and direct detection schemes is provided. Beginning with the optical powers incident on the detector, the signal and noises are analyzed, through the detector electronics, to predict the SNR. The SNR is then plotted as a function of the return signal power, and a SNR threshold is defined to determine a minimum …

Periodic Pn Sequence Delay Estimation Using Phase Spectrum Data, Kurt Louis Kosbar, Jorge J. Zaninovich

Electrical and Computer Engineering Faculty Research & Creative Works

An algorithm for estimating the delay of a periodic pseudonoise (PN) sequence is presented. It is a rapid, block-based estimator that can be used for both linear and nonlinear codes. The algorithm exploits the periodicity of the difference between the phase spectra of the received sequence and a local reference. The estimator takes the Fourier transform of the phase spectrum difference data, and searches for the fundamental frequency. Unlike previously described methods, phase unwrapping is not required. The performance in the presence of additive white Gaussian noise (AWGN) and a continuous wave (CW) jammer is investigated using computer simulation. Comparisons …

On Generalized Adaptive Neural Filter, Zhiqiang Zhang

Dissertations

Linear filters have historically been used in the past as the most useful tools for suppressing noise in signal processing. It has been shown that the optimal filter which minimizes the mean square error (MSE) between the filter output and the desired output is a linear filter provided that the noise is additive white Gaussian noise (AWGN). However, in most signal processing applications, the noise in the channel through which a signal is transmitted is not AWGN; it is not stationary, and it may have unknown characteristics.

To overcome the shortcomings of linear filters, nonlinear filters ranging from the median …

A High-Temperature Pressure Sensor Utilizing Linear Voltage Differential Transformer (Lvdt) And Silicon Wafer-To-Wafer Fusion Bonding Technologies, Robert Sylvester Okojie

Theses

A novel high-temperature pressure sensor was designed based on the principle of magnetic induction. The device is meant to correct the problems inherent in conventional Solid-State pressure transducers such as piezoresistive and capacitive at temperatures above 300°C. Prominent among these problems are increased leakage current, reduced absolute sensitivity, redistributed impurity concentration profile, and thermal mismatch.

This thesis combined the Biot Savart magnetostatic principle and the theory of deflecting clamped circular plates to obtain the microelectromechanical relationship. The problem of thermal mismatch was resolved by the symmetrical layering of a Si₃N₄/TaSi₂/Si₃N₄ sandwich, …

Traffic Management Of A Satellite Communication Network Using Stochastic Optimization, Ambalavanar Arulambalam

Theses

The performance of nonhierachial circuit switched networks at moderate load conditions is improved when alternate routes are made available. However, alternate routes introduce instability under heavy and overloaded conditions, and under these load conditions network performance is found to deteriorate. To alleviate this problem, a control mechanism is used where, a fraction of the capacity of each link is reserved for direct routed calls.

In this work, a traffic management scheme is developed to enhance the performance of a mesh-connected, circuit-switched satellite communication network. The network load is measured and the network is continually adapted by reconfiguring the map to …

A Parallel Processing Architecture For Dqdb Protocol Implementation, Nilesh Vinubhai Gandhi

Theses

The high bandwidth transmission links, which have been provided by the advances of Fiber Optics Technology, reduce drastically the packet transmission times and place new demands on the nodal protocol processing. Segmentation and reassembly of packets, computation of checksums, introduction of source and destination addresses, etc., must be performed extremely fast in order to prevent node processing from becoming the bottleneck of the transmission. Parallel processing enables the execution of the previous tasks on multiple packets simultaneously and therefore has the potential of addressing the issue of fast node processing successfully. In this thesis we focus on the Medium Access …

An Efficient Guaranteed Bandwidth And Balancing Mechanism For High Speed Mans, Venediktos Hadjisavvas

Theses

The Distributed Queue Dual Bus (DQDB) has become the IEEE 802.6 stan-dard for Metropolitan Area Networks (MANs). The main advantage of DQDB is that its throughput performance is not affected by the network parameters such as size, number of connected stations, or channel bandwidth. Its main drawback is that the location of the stations on the bus strongly affects their performance. For this reason a Bandwidth Balancing Mechanism (BBM_DQDB) has been proposed and included in the 802.6 standard that can provide the requested bandwidth by the lightly loaded stations and evenly distribute the remaining bandwidth among the overloaded stations. The …

Investigation Of The Pl Cebus Performance With And Without Acknowledgment, Menghan Pan

Theses

The power line implementation of the consumer electronic bus (PL CEBUS) is a promising and inexpensive approach for home automation. Since the intro¬duction of the PL CEBUS standards, there has been increasing efforts on evaluating its performance. However, all the works have been performed for unacknowledged networks. This thesis presents the first successful evaluation of the PL CEBUS with acknowledment. Three different cases, namely, 600, 300 and 100 bits packet sizes, have been considered. The evaluation included the simulation of performance parameters such as message and packet delays, message throughput, and channel throughput. Acknowledged network performance has been confirmed to …

Linear Ccd Motion Detection System, Thekepat J. Sudesh

Theses

The mechanical response to electrical stimuli of the human membrane represents an important area of research in medicine. A linear sensing system was designed and fabricated to measure the displacements (along a specified direction) and the frequency response of a ear membrane, the Outer Hair Cell (OHC). The output of this system was a voltage proportional to the instantaneous position of the bimorph and could be displayed on an oscilloscope.

The system consisted of optics to project the image of the vibrating membrane onto a Linear CCD Camera and electronic analog and digital circuitry which produced an instantaneous voltage proportional …

Object Oriented Design Of Petri Net Simulator, Himanshu Juneja

Theses

Petri nets are highly useful for modeling discrete event dynamic systems. The objective of this effort is to develop a tool for drawing, editing and simulating Petri nets using object oriented programming on a standard platform. The object oriented approach was chosen because of its code reuse and extendability features which simplify the task of adding features to the tool as the model evolves. The design stresses on modeling of the problem by objects which closely relate the system design with the implementation.

C++ is used for implementing the object oriented design, and the XView toolkit is used for building …

Hardware Design For Jpeg And A Comparative Study Of Jpeg And Mpeg Image Compression Algorithms, Aravind Soundararajan

Theses

The complete PC-based hardware design along with the initialization and control software of the JPEG algorithm is presented in this thesis. The hardware could run in real-time to compress, decompress and display still frame images. LSI Logic JPEG chipset was used in the design. This is a dedicated chipset for the JPEG compression algorithm.

A simulation software was used for studying the performance of MPEG video compression algorithm. Various video test sequences were compressed through the codec simulation software and the resulting rate-distortion performance was calculated. These are compared with the performance of JPEG based image sequence compressor.

It is …

Proposal For A Dod Combined Battlefield Electromagnetic Environmental Effects (E3) Initiative, George H. Baker Iii

School of Integrated Sciences - Faculty Scholarship

The presentation emphasizes the growing importance of electromagnetic survivability and compatibility. Operation Desert Storm demonstrated the clear military advantage provided by sophisticated electronic weapon and communication systems. In addition, the offensive tactic of taking out the enemy's eyes and ears during the air war paid off, giving our military decisive air superiority. The lessons for the future are clear. High-tech electronics now so dominates the battlefield that the outcome of future conflicts could well be decided by electronics attrition rather than human casualties. Our Desert Storm experience thus accentuates the importance of guaranteeing that our electronic systems will not be …

Acoustic Correlates Of Vowel Perception As Determined From Synthesis Experiments With Multi-Tone Stimuli, Zhongjiang Zhang

Electrical & Computer Engineering Theses & Dissertations

An essential requirement of speech signal processing is to extract information (features or parameters) from the speech signal which encode the information carried by the signal. The objective of this thesis work was to examine and evaluate two feature sets as acoustic correlates for vowel perception. They are formants and DCTCs. Formants are the frequencies of spectral peaks of the speech signal. DCTCs are the Discrete Cosine Transform Coefficients of the magnitude spectrum and are thus features which encode the global spectral shape of speech signal.

There are different opinions regarding which feature set is a more accurate representation for …

Coordinated Intelligent Control Via Epistemic Utility Theory, Wynn C. Stirling

Faculty Publications

An approach to local reactive coordinated intelligent control based on the concept of an epistemic system, together with a principle of action that may be exercised locally, is presented. An epistemic system provides a mechanism for agents to characterize their knowledge corpora, options, goals, and beliefs. Levi's rule of epistemic utility provides a principle of action for decision making by comparing the informational value of rejection with the belief of correctness. Decisions are made locally and reactively, rather than globally. Coordination is implemented between agents by sharing and learning the epistemic systems of other agents. The resulting coordination model is …

Identification Of Variegated Coloring In Skin Tumors: Neural Network Vs. Rule-Based Induction Methods, Ajaya Durg, William V. Stoecker, J. P. Cookson, Scott E. Umbaugh, Randy Hays Moss

Chemistry Faculty Research & Creative Works

The use of neural networks for automatic identification of variegated coloring, which is believed to be one of the most predictive features for malignant melanoma, is described. The Nestor development system (NDS) was chosen for neural network implementation. At the heart of NDS is a three-layer neural network called a restricted Coulomb energy (RCE) network. The learning scheme and the database for detection of variegated coloring are discussed. Results are reported

Electronic Simulation Of The Temporal Characteristics Of Photon Memory Echoes And Some Related Applications, Yuwen Kuo, Monish Ranjan Chatterjee

Electrical and Computer Engineering Faculty Publications

The characteristics of nonlinear photon memory echoes are investigated by means of SPICE simulations using equivalent resonator ensembles. By developing implicit nonlinear circuit models in the memory echo domain, the triple product formalism of electronic holography, involving correlation and convolution, is tested for the storage and recall of arbitrary signals and/or data bit streams in both time-inverted and nontime-inverted modes. Furthermore, a few specific optical data processing applications are also simulated in which the mixed binary multiplication of two or more binary bit streams is achieved.

Higher order products, optical pattern recognition, and other possible applications are also discussed. It …