Digital Commons Network^™

Overview Of Fuzzy Logic, Mohamed Trabia

Mechanical Engineering Faculty Presentations

The presentation includes a brief introduction to fuzzy logic and fuzzy logic controllers. These concepts are illustrated by an example of an autonomous vehicle controller.

Comparison Of Two Distributed Fuzzy Logic Controllers For Flexible-Link Manipulators, Linda Z. Shi, Mohamed Trabia

Mechanical Engineering Faculty Presentations

The paper suggests that fuzzy logic controllers present a computationally efficient and robust alternative to conventional controllers. The paper presents two possible structures for the distributed fuzzy logic controller of a single-link flexible manipulator. A linear quadratic regulator method is used to prove the effectiveness of fuzzy logic controllers.

Design Of Fuzzy Logic Controllers For Optimal Performance, Mohamed Trabia

Mechanical Engineering Faculty Presentations

While fuzzy logic controllers are generally robust, the performance of a system whose behavior is not well understood, or that has a large number of coupled inputs and outputs, may be less than optimal. In this paper, nonlinear programming techniques are used to improve the performance of a fuzzy logic controller for navigating an autonomous vehicle.

Integration Of A Statcom And Battery Energy Storage, Zhiping Yang, Shen Chen, Lin Zhang, Stan Atcitty, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

The integration of an energy storage system, such as battery energy storage (BESS), into a FACTS device can provide dynamic decentralized active power capabilities and much needed flexibility for mitigating transmission level power flow problems. This paper introduces an integrated StatCom/BESS for the improvement of dynamic and transient stability and transmission capability; compare the performance of the different FACTS/BESS combinations, and provide experimental verification of the proposed controls on a scaled StatCom/BESS system

Software Engineering Metrics For Cots-Based Systems, Sahra Sedigh, Arif Ghafoor, Raymond A. Paul

Electrical and Computer Engineering Faculty Research & Creative Works

The paradigm shift to commercial off-the-shelf components appears inevitable, necessitating drastic changes to current software development and business practices. Quality and risk concerns currently limit the application of COTS based system design to noncritical applications. New approaches to quality and risk management will be needed to handle the growth of CBSs. Our metrics based approach and software engineering metrics can aid developers and managers in analyzing the return on investment in quality improvement initiatives for CBSs. These metrics also facilitate the modeling of cost and quality, although we need more complex models to capture the intricate relationships between cost and …

A Method For Evaluating The Dielectric Properties Of Composites Using A Combined Embedded Modulated Scattering And Near-Field Microwave Nondestructive Testing Technique, Dana M. Hughes, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

Investigation into the derivation of the dielectric property of a material with an embedded modulated PIN diode-loaded dipole is described, using an open-ended rectangular waveguide as the irradiating source. Previous measurements of the curing of a mortar specimen show the sensitivity of this combined technique and its potential for inspecting composite structures. Modification of previous algorithms for back calculating the dielectric properties of a material with a conductor backing is considered. The modification would involve replacing the reflection at the conductor with the reflection at a modulated dipole antenna. For this, comparisons between the reflection coefficients of the dipole antenna …

Modeling Dc Power-Bus Structures With Vertical Discontinuities Using A Circuit Extraction Approach Based On A Mixed-Potential Integral Equation, Jun Fan, Hao Shi, Antonio Orlandi, James L. Knighten, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

The DC power-bus is a critical aspect in high-speed digital circuit designs. A circuit extraction approach based on a mixed-potential integral equation is presented herein to model arbitrary multilayer power-bus structures with vertical discontinuities that include decoupling capacitor interconnects. Green's functions in a stratified medium are used and the problem is formulated using a mixed-potential integral equation approach. The final matrix equation is not solved, rather, an equivalent circuit model is extracted from the first-principles formulation. Agreement between modeling and measurements is good, and the utility of the approach is demonstrated for DC power-bus design.

Aspect Sensitivity Measurements Of Polar Mesosphere Summer Echoes Using Coherent Radar Imaging, P. B. Chilson, T.-Y. Yu, R. D. Palmer, S. Kirkwood

Department of Electrical and Computer Engineering: Faculty Publications

The Esrange VHF radar (ESRAD), located in northern Sweden (67.88) N, 21.10- E), has been used to investigate polar mesosphere summer echoes (PMSE). During July and August of 1998, coherent radar imaging (CRI) was used to study the dynamic evolution of PMSE with high temporal and spatial resolution. A CRI analysis provides an estimate of the angular brightness distribution within the radar’s probing volume. The brightness distribution is directly related to the radar reflectivity. Consequently, these data are used to investigate the aspect sensitivity of PMSE. In addition to the CRI analysis, the full correlation analysis (FCA) is used to …

Mitigation Of Water Vapor Interference For Infrared Polarization-Modulated Gas Filter Correlation Radiometry, David K. Lockwood

Electrical & Computer Engineering Theses & Dissertations

Gas filter correlation radiometry (GFCR) is a high-resolution, high-specificity technique for sensing gaseous species. A variation of absorption spectroscopy, GFCR has a long-proven record on orbital platforms for quantitative measurements of atmospheric constituents, as well as common usage in ground-based sensing applications. PMGFCR (Polarization-modulated GFCR) is a recent refinement of the technique with several advantages over the traditional method, including reducing the number of photodetectors required, increased sensitivity, and elimination of moving parts.

To date, no infrared remote sensors have successfully measured nitric oxide (NO) in vehicle exhaust due to spectral overlap by strong water vapor (H₂O_{v …}

Spice-Based Heat Transport Model For Non-Intrusive Thermal Diagnostic Applications, Michael Stelzer

Electrical & Computer Engineering Theses & Dissertations

Nondestructive material testing and diagnostics play an important role in reliability analysis, component wear-out testing, life-cycle estimates, and safety inspections. Of the several techniques available for nondestructive inspections, thermal analysis has been chosen to be the focus of this thesis research. An equivalence between the system of equations for the heat flow problem, and the variables of circuit theory suggests that an electrical model can be constructed to represent the actual thermal system. This electrical model is constructed based upon a finite difference discretization of the heat flow equation. Using these associations a basic one-dimensional electrical model has been constructed …

On The Solution Of A Class Of Large Body Problems With Partial Circular Symmetry (Multiple Asymmetries) By Using A Hybrid-Dimensional Finite-Difference Time-Domain (Fdtd) Method, Dean Arakaki, Wenhua Yu, Raj Mittra

Electrical Engineering

This paper presents an efficient method to solve a large body scattering problem, viz. a paraboloid reflector antenna system, with only partial circular symmetry. The asymmetry in the system is introduced by two factors, viz. the microstrip feed and an inhomogeneous radome. The paper presents a novel approach, based on the equivalence and reciprocity principles and the “equivalent” aperture theory, to overcome the asymmetry problem. The technique thereby enables substantial computational efficiencies by analyzing the majority of the three-dimensional (3-D) computational domain in an effective two-dimensional (2-D) simulation, with the remainder being analyzed using a 3-D algorithm.

Characterization And Validation Of The Gp-3 Experimental Radar System, Benjamin L. Crossley

Theses and Dissertations

The experimental GP-3 radar system was originally designed and built under contract for the Air Force Research Laboratory (AFRL). AFRL sought AFIT's support in characterizing the as delivered' performance of the GP-3. This research effort focused exclusively on software modifications and hardware validations related to the GP-3 post-processing mode. As modified, tested, and validated, the GP-3's post-processing mode is now fully operational. The GP-3 is capable of transmitting and receiving bandlimited (3.5 MHz) waveforms at X-Band frequencies. System characterization tests included, noise performance and frequency response. System noise performance characterization permitted establishment of the receiver 'noise floor' and enabled determination …

Image Registration Using Redundant Wavelet Transforms, Richard K. Brown

Theses and Dissertations

Imagery is collected much faster and in significantly greater quantities today compared to a few years ago. Accurate registration of this imagery is vital for comparing the similarities and differences between multiple images. Since human analysis is tedious and error prone for large data sets, we require an automatic, efficient, robust, and accurate method to register images. Wavelet transforms have proven useful for a variety of signal and image processing tasks, including image registration. In our research, we present a fundamentally new wavelet-based registration algorithm utilizing redundant transforms and a masking process to suppress the adverse effects of noise and …

Development And Testing Of A Multiple Filter Approach For Precise Dgps Positioning And Carrier-Phase Ambiguity Resolution, Paul E. Henderson

Theses and Dissertations

The most precise relative positioning obtained using differential GPS depends on accurately determining carrier-phase integer ambiguities. To achieve high precision, many current static and kinematic algorithms use a floating-point solution until enough information becomes available to fix the carrier-phase ambiguities accurately. A mew method is presented that uses a multiple model Kalman filter to resolve the carrier-phase integer ambiguities. This method starts with the floating-point results, yet smoothly and rapidly attains the precision of the correct fixed-integer solution, eliminating the need to decide when to switch from the floating to the fixed-integer solution. This method is based on a theoretically …

Redundant Wavelet-Based Image Restoration Using A Prior Information, Mary K. Marcum

Theses and Dissertations

Reconnaissance missions and satellites collect hundreds of images loaded with valuable information to be utilized by the Air Force. Intelligence operations must analyze these images to extract the information needed to help commanders make important decisions. No matter how obtained, images of this type are often degraded by noise due to disruptions such as atmospheric disturbances, optical system variations, motion, and large distance from the sensor to the source. This noise must be removed effectively to improve the quality of these images and ensure that the information contained in them can be correctly extracted. The Air Force relies on the …

Wavelet-Based Audio Embedding & Audio/Video Compression, Michael J. Mendenhall

Theses and Dissertations

With the decline in military spending, the United States relies heavily on state side support. Communications has never been more important. High-quality audio and video capabilities are a must. Watermarking, traditionally used for copyright protection, is used in a new and exciting way. An efficient wavelet-based watermarking technique embeds audio information into a video signal. Several highly effective compression techniques are applied to compress the resulting audio/video signal in an embedded fashion. This wavelet-based compression algorithm incorporates bit plane coding, first difference coding, and Huffman coding. To demonstrate the potential of this audio embedding audio/video compression system, an audio signal …

A Model To Predict Diffraction Attenuation Resulting From Signal Propagation Over Terrain In Low Earth Orbit Satellite Systems, Peter R. Pollock

Theses and Dissertations

This study focused on multipath communication propagation impairments to the LEOSAT communications channel. Two terrain diffraction models, based on the geometric theory of diffraction (GTD), were developed and applied to the space-to-ground communications channel. These models were used to predict the impact of terrain on the performance of three LEOSAT communication systems with designs based on the Iridium, Globalstar and Orbcomm implementations. The study verified the feasibility of applying models based on the GTD rather than empirical or statistical models, to approximate the effect of propagating signals over terrain. Both models confirm that signal blockage and multipath propagation, due to …

Microdot-A 4-Bit Synchronous Microcontroller For Space Applications, Kirby M. Watson

Theses and Dissertations

Satellites have limited power budgets due to the amount of power collected by the satellite's solar panels. The goal is to have a wide range of functionality, while running off a limited power source. Large microprocessors use large amounts of power to report back temperature and chemical sensor data to ground stations. By using small micro controllers to perform the data collection and minimizing the usage of the larger microprocessors, the satellites will save power. A prototype design of the Microdot 4-bit micro controller for space applications is presented. Requirements for the Microdot, such as microwatt power consumption and 23 …

The Calibration Of Bistatic Radar Cross Section Measurements, Christopher J. Bradley

Theses and Dissertations

Recent advances in signal processing and remote sensing have highlighted the importance of bistatic radar systems for the purposes of environmental monitoring, surveillance, and tracking radar. The calibration of such systems has been problematic-much more so than similar monostatic systems, primarily as a result of the lack of reference objects suitable for calibrating at any given bistatic angle. This research deals with the problems of calibrating full-polarimetric laboratory-environment bistatic radar systems, including the lack of suitable calibration targets and procedures, and operational considerations such as alignment and mounting. Several popular bistatic calibration techniques are classified, evaluated, and comparisons are made …

Using Gps As A Reference System To Hit A Moving Target, Daryl J. Burnette

Theses and Dissertations

The Affordable Moving Surface Target Engagement (AMSTE) project attempts to develop affordable solutions to the precise moving target surface target engagement problem. Up to this point, most of the error analysis performed for the AMSTE project has been at the error variance level, generating root-sum-square (RSS) total errors from error budgets consisting of constant error variances. In reality, the level of error for both Global Positioning System (GPS) positioning and radar targeting systems is highly dependent upon the given situation (such as the distance between sensor and target, the altitude differences, etc.) This research generates a more comprehensive model of …

Broadband Application Of High Impedance Ground Planes, Keven J. Golla

Theses and Dissertations

Electrical conductors have long been the only materials available to antenna designers for reflecting structures. However, recently reported high impedance ground plane (HIGP) structures offer an alternative by creating image currents and reflections, within a limited frequency stop-band, that are in-phase with a source rather than out-of-phase as for a perfect electric conducting (PEC) surface. Also, the high impedance structures suppress surface waves while surface waves propagate on PEC surfaces. This research explores broadband antenna applications for HIGP structures. A broadband surface mount antenna is applied to both a homogeneous narrowband HIGP and a spatially varying broadband HIGP design. Measurements …

An Objective Evaluation Of Four Sar Image Segmentation Algorithms, Jason B. Gregga

Theses and Dissertations

Because of the large number of SAR images the Air Force generates and the dwindling number of available human analysts, automated methods must be developed. A key step towards automated SAR image analysis is image segmentation. There are many segmentation algorithms, but they have not been tested on a common set of images, and there are no standard test methods. This thesis evaluates four SAR image segmentation algorithms by running them on a common set of data and objectively comparing them to each other and to human segmentors. This objective comparison uses a multi-metric a approach with a set of …

A Low Power Application-Specific Integrated Circuit (Asic) Implementation Of Wavelet Transform/Inverse Transform, Daniel N. Harvala

Theses and Dissertations

A unique ASIC was designed implementing the Haar Wavelet transform for image compression/decompression. ASIC operations include performing the Haar wavelet transform on a 512 by 512 square pixel image, preparing the image for transmission by quantizing and thresholding the transformed data, and performing the inverse Haar wavelet transform, returning the original image with only minor degradation. The ASIC is based on an existing four-chip FPGA implementation. Implementing the design using a dedicated ASIC enhances the speed, decreases chip count to a single die, and uses significantly less power compared to the FPGA implementation. A reduction of RAM accesses was realized …

Enhanced Transition Temperature In A Quantum Confined High-TC Superconductor, L. Menon, D. Yu, Yi Liu, B. Jayaram

P. F. (Paul Frazer) Williams Publications

A slight enhancement of the onset transition temperature T_c has been observed in quantum dots of the high-T_c superconductor yttrium–barium–copper oxide (Y₁Ba₂Cu₃O_7-δ). The dots were formed when YBCO particles (diameter ≤600 nm) were exposed to an RF plasma to produce a Coulomb crystal. The plasma damages the particles and causes 20–25 nm sized isolated islands of the correct 1-2-3 stoichiometry to segregate within each particle. We believe that quantum confinement of carriers within these islands leads to discretization of the quasi-particle density-of-states which can account for the slight increase …

Development Of Objective-Oriented Components For Atm Networks Simulation With Emphasis On Switch Architecture, Boon Pin Tan

Student Works (2000-2009)

Asynchronous Transfer Mode (ATM) is considered to be the ground on which B-ISDN is to be built. It is the new generation of communication networks that are being deployed throughout the telecommunication industry. The basic functions of ATM switch are to direct cells from input port to output port and to buffer cell destined to the same output port from different input port. This project focuses on the development of an object-oriented simulator for simulation. The simulator is designed and implemented to ensure the correctness of routing within the switch fabric, fairness of switching and to guarantee quality of service …

A Comparison Of The Dynamic Performance Of Facts With Energy Storage To A Unified Power Flow Controller, Lin Zhang, Shen Chen, Zhiping Yang, Aysen Arsoy, Yilu Liu, Stan Atcitty, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

The integration of an energy storage system into FACTS devices may lead to a more economical and/or flexible transmission controller. Various energy storage systems have received considerable attention in power utility applications due to their characteristics that range from rapid response, high power, high efficiency, and four-quadrant control. The enhanced performance of combined FACTS/ESS may have greater appeal to transmission service providers. Integrating an energy storage system into a FACTS device can provide dynamic decentralized active power capabilities and much needed flexibility for mitigating transmission level power flow problems. This paper presents a comprehensive comparison between the dynamic performances of …

Video Indexing And Summarization Using Motion Activity, Kadir Askin Peker

Dissertations

In this dissertation, video-indexing techniques using low-level motion activity characteristics and their application to video summarization are presented. The MPEG-7 motion activity feature is defined as the subjective level of activity or motion in a video segment. First, a novel psychophysical and analytical framework for automatic measurement of motion activity in compliance with its subjective perception is developed. A psychophysically sound subjective ground truth for motion activity and a test-set of video clips is constructed for this purpose. A number of low-level, compressed domain motion vector based, known and novel descriptors are then described. It is shown that these descriptors …

Phase-Locked Loop, Delay-Locked Loop, And Linear Decorrelating Detector For Asynchronous Multirate Ds-Cdma System, Sok-Kyu Lee

Dissertations

The performance of phase synchronization and code tracking of a digital phase-locked loop (PLL) and delay-locked loop (DLL), respectively, is investigated in wideband asynchronous multirate DS-CDMA system. Dynamic Partial Correlation (DPC) method is proposed to evaluate the autocorrelation and its power spectrum density (PSD) of the cross-correlated terms in the presence of multirate multiple access interference (MMAI) under additive white gaussian noise (AWGN) and fading channel environments. The steady-state probability density function (PDF) and variance of the phase estimator error and code tracking jitter is evaluated by solving the first-order Fokker-Planck equation.

Among many linear multiuser detectors which decouple the …

Resource Allocation For Cdma Downlink To Achieve Maximum Throughput, Anil Bircan

Dissertations

Growing interest in cellular phones, wireless modems, instant messaging, pagers with the increasing use of the Internet in daily life indicate that wireless high speed Internet access and wireless multimedia applications are in great demand. The barrier to satisfy this demand is the provision of sufficiently high bit rates in severe wireless mobile channel conditions, for a multitude of services, each requiring different and perhaps even time-varying quality of services (QoS) that can be more demanding than the QoS required by today's voice service. New generation systems will enable provision of a multitude of services each with different QoS and …

Nonlinear Optical Properties Of Nano Structures, Mahesh U. Ajgaonkar

Dissertations

Nonlinear optical properties of nanoscale semiconductors had been a topic of intense research in recent years in attempts to realize all-optical communication systems. These semiconductor nanoclusters, in the range of 1-100nm are hosted in a dielectric material and are considered as a particular example of Conditional Artificial Dielectric (CAD). It has been reported that the dielectric properties of such materials will be greatly changed by light intensity.

Two main paths to realize nano semiconductor clusters are reported in this dissertation. The Pulsed Laser Deposition (PLD) technique is first described. Here we were investigating the effect of surface modification of nano …