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Ultrashort‐Pulse Propagation In Dye Laser Amplifiers, Shuanghua Jiang, Lee W. Casperson Jan 1993

Ultrashort‐Pulse Propagation In Dye Laser Amplifiers, Shuanghua Jiang, Lee W. Casperson

Electrical and Computer Engineering Faculty Publications and Presentations

A semiclassical model is presented for ultrashort‐pulse dye laser amplifiers. The model permits a discussion of important aspects of short‐pulse amplification such as pulse shape, pulse energy, and gain saturation. Coherence effects are found to be important in characterizing the evolution of amplified pulses in the subpicosecond and femtosecond regimes. The results are compared with those obtained using the corresponding rate equation model.

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Analog Chips And Intelligent Vehicles, J. G. Harris Jan 1993

Analog Chips And Intelligent Vehicles, J. G. Harris

Electrical and Computer Engineering Faculty Research & Creative Works

Numerous digital-based sensor systems have been demonstrated on intelligent vehicles but only the most rudimentary experiments have been attempted with analog VLSI chips in real-world environments. The most significant factor in the choice between analog and digital approaches to sensory processing in intelligent vehicles will be the cost of mass production. If analog sensors can be designed with enough speed, resolution and accuracy to solve sensory processing tasks, then the low-cost of mass production ensures that analog circuits will be the technology of choice for future generations of smart sensors. Current analog VLSI sensors do not have enough resolution and …

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Robust Control Of Flexible Structures Using Multiple Shape Memory Alloy Actuators, R. Lashlee, R. Butler, Vittal S. Rao, F. Kern Jan 1993

Robust Control Of Flexible Structures Using Multiple Shape Memory Alloy Actuators, R. Lashlee, R. Butler, Vittal S. Rao, F. Kern

Electrical and Computer Engineering Faculty Research & Creative Works

The design and implementation of control strategies for large, flexible smart structures presents challenging problems. To demonstrate the capabilities of shape-memory-alloy actuators, we have designed and fabricated a three-mass test article with multiple shape-memory-alloy (NiTiNOL) actuators. The force and moment actuators were implemented on the structure to examine the effects of control structure interaction and to increase actuation force. These SMA actuators exhibit nonlinear effects due to dead band and saturation. The first step in the modeling process was the experimental determination of the transfer function matrix derived from frequency response data. A minimal state space representation was determined based …

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Efficient Simulation Of Multicarrier Digital Communication Systems In Nonlinear Channel Environments, Kevin W. Schneider, William H. Tranter Jan 1993

Efficient Simulation Of Multicarrier Digital Communication Systems In Nonlinear Channel Environments, Kevin W. Schneider, William H. Tranter

Electrical and Computer Engineering Faculty Research & Creative Works

The effectiveness of computer simulation as a tool for the design and analysis of communication systems is often limited by the long execution times required for many simulations. When simulating multicarrier digital communication systems operating over nonlinear channels, the required high sampling rate contributes significantly to long execution times. A new method that reduces the sampling rate of simulations of such systems is developed. This Partial Sum of Products (ParSOP) method reduces the sampling rate by generating only the intermodulation products that lie in a frequency band of interest. The ParSOP method requires that the bandpass nonlinearity be represented by …

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Advanced Graphics Zoom In On Operations, Max Darwin Anderson, Hardy J. Pottinger, C. M. Schroeder Jan 1993

Advanced Graphics Zoom In On Operations, Max Darwin Anderson, Hardy J. Pottinger, C. M. Schroeder

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

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A New Technique To Decompose Closely Spaced Interface And Bulk Trap States Using Temperature Dependent Pulse-Width Deep Level Transient Spectroscopy Method: An Application To Pt/Cds Photodetector, C. W. Wang, Cheng-Hsiao Wu, Jack L. Boone Jan 1993

A New Technique To Decompose Closely Spaced Interface And Bulk Trap States Using Temperature Dependent Pulse-Width Deep Level Transient Spectroscopy Method: An Application To Pt/Cds Photodetector, C. W. Wang, Cheng-Hsiao Wu, Jack L. Boone

Electrical and Computer Engineering Faculty Research & Creative Works

A novel method is presented here to experimentally decompose nonexponential capacitive transients into the appropriate components from the closely spaced deep trap states. Using temperature dependent pulse-width deep level transient spectroscopy (TDP-DLTS) technique, we show for the first time that two bulk trap states and one continuously distributed interface states in (Pt/CdS) photodiodes can be successfully separated. The basic principle is to set the applied pulse width to follow an averaged temperature-dependent capture time constant and divide the DLTS spectrum. In the example of Pt/CdS photodiodes, we show that all physical parameters including thermal activation energies, capture cross sections, and …

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Detection Of Skin Tumor Boundaries In Color Images, Fikret Erçal, M. Moganti, William V. Stoecker, Randy Hays Moss Jan 1993

Detection Of Skin Tumor Boundaries In Color Images, Fikret Erçal, M. Moganti, William V. Stoecker, Randy Hays Moss

Computer Science Faculty Research & Creative Works

A simple and yet effective method for finding the borders of tumors is presented as an initial step towards the diagnosis of skin tumors from their color images. The method makes use of an adaptive color metric from the red, green, and blue planes that contains information for discriminating the tumor from the background. Using this suitable coordinate transformation, the image is segmented. The tumor portion is then extracted from the segmented image and borders are drawn. Experimental results that verify the effectiveness of this approach are given

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Neural Networks In The Former Soviet Union, Donald C. Wunsch Jan 1993

Neural Networks In The Former Soviet Union, Donald C. Wunsch

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

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An Optoelectronic Implementation Of The Adaptive Resonance Neural Network, Donald C. Wunsch, T. P. Caudell, R. J. Marks, R. A. Falk, C. David Capps Jan 1993

An Optoelectronic Implementation Of The Adaptive Resonance Neural Network, Donald C. Wunsch, T. P. Caudell, R. J. Marks, R. A. Falk, C. David Capps

Electrical and Computer Engineering Faculty Research & Creative Works

A solution to the problem of implementation of the adaptive resonance theory (ART) of neural networks that uses an optical correlator which allows the large body of correlator research to be leveraged in the implementation of ART is presented. The implementation takes advantage of the fact that one ART-based architecture, known as ART1, can be broken into several parts, some of which are better to implement in parallel. The control structure of ART, often regarded as its most complex part, is actually not very time consuming and can be done in electronics. The bottom-up and top-down gated pathways, however, are …

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Automatic Color Segmentation Algorithms-With Application To Skin Tumor Feature Identification, Scott E. Umbaugh, Randy Hays Moss, William V. Stoecker, G. A. Hance Jan 1993

Automatic Color Segmentation Algorithms-With Application To Skin Tumor Feature Identification, Scott E. Umbaugh, Randy Hays Moss, William V. Stoecker, G. A. Hance

Electrical and Computer Engineering Faculty Research & Creative Works

Two color-image segmentation methods are described. The first is based on a spherical coordinate transform of original RGB data. The second is based on a mathematically optimal transform, the principal components transform (also known as eigenvector, discrete Karhunen-Loeve, or Hotelling transform). These algorithms are applied to the extraction from skin tumor images of various features such as tumor border, crust, hair scale, shiny areas, and ulcer. The results of this research will be used in the development of a computer vision system that will serve as the visual front-end of a medical expert system to automate visual feature identification for …

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Design And Implementation Of Fuzzy Logic Controllers. Thesis Final Report, 27 July 1992 - 1 January 1993, Osama A. Abihana, Oscar R. Gonzalez Jan 1993

Design And Implementation Of Fuzzy Logic Controllers. Thesis Final Report, 27 July 1992 - 1 January 1993, Osama A. Abihana, Oscar R. Gonzalez

Electrical & Computer Engineering Faculty Publications

The main objectives of our research are to present a self-contained overview of fuzzy sets and fuzzy logic, develop a methodology for control system design using fuzzy logic controllers, and to design and implement a fuzzy logic controller for a real system. We first present the fundamental concepts of fuzzy sets and fuzzy logic. Fuzzy sets and basic fuzzy operations are defined. In addition, for control systems, it is important to understand the concepts of linguistic values, term sets, fuzzy rule base, inference methods, and defuzzification methods. Second, we introduce a four-step fuzzy logic control system design procedure. The design …

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Fuzzy Logic Applied To Adaptive Kalman Filtering, Marlys Rae Remus Dec 1992

Fuzzy Logic Applied To Adaptive Kalman Filtering, Marlys Rae Remus

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

The Kalman filter provides an effective means of estimating the state of a system from noisy measurements given that the system parameters are completely specified. The innovations sequence for a properly specified Kalman filter will be a zero-mean white noise process. However, when the system parameters change with time the Kalman filter will need to be adapted to compensate for the changes. Traditionally this has been accomplished by using nonlinear filtering, parallel Kalman filtering and covariance matching techniques. These methods have produced good results at the expense of large amounts of computational time. Necessary changes in the system parameters become …

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Semiconductor P-N Junction Space Charge Region Capacitance, Mohammad Humayun Habib Dec 1992

Semiconductor P-N Junction Space Charge Region Capacitance, Mohammad Humayun Habib

Dissertations and Theses

The classical capacitance voltage characteristics based on the depletion approximation, is adequate at reverse bias, but introduces errors at high forward bias. Because of its inherent simplicity and compactness this classical depletion model is well studied and widely used in circuit simulators. In this work, a new model for the semiconductor space charge region (SCR) capacitance, based on physical justification, will be derived. This new model takes three input parameters, C0 , Vbi and m, thus eliminating the fitting parameter FC currently used in SPICE. This new model is applicable for any applied voltage and will be compared with the …

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An Object-Oriented Computer Aided Design Program For Modern Control Systems Analysis, Frederick L. Trevino Dec 1992

An Object-Oriented Computer Aided Design Program For Modern Control Systems Analysis, Frederick L. Trevino

Theses and Dissertations

This investigation is a continuation of the ICECAP-PC research project conducted under Prof. Gary B. Lamont at the Air Force Institute of Technology. It is an ongoing development of a public domain Computer Aided Design (CAD) package for Control Engineering students and faculty, with a special emphasis on education. This investigation focuses on three areas. First, an object-oriented environment is specified, designed and implemented. The functional structure of ICECAP-PC is then converted into an object-oriented structure because object-orientation provides an advanced logic and implementation structure and effectively addresses common software engineering issues. Additionally, a new interface featuring pull-down menus, mouse …

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Optical Haar Wavelet Transforms Using Computer Generated Holography, Peter G. Block Dec 1992

Optical Haar Wavelet Transforms Using Computer Generated Holography, Peter G. Block

Theses and Dissertations

This research introduces an optical implementation of the continuous wavelet transform to filter images. The wavelet transform is modeled as a correlation process and is implemented with a Vander Lugt correlator. The orthonormal basis set used is composed of two one-dimensional Haar functions and a two-dimensional Haar function. Each wavelet, as well as its first two dyadic scalings, is implemented with computer generated holography. The Interferogram method, which represents a function only in terms of its phase, is used to encode the wavelet functions. The results are imaged onto a CCD array and captured using a framegrabber. The optical results …

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Etann Hardware Implementation For Radar Emitter Identification, James B. Calvin Jr. Dec 1992

Etann Hardware Implementation For Radar Emitter Identification, James B. Calvin Jr.

Theses and Dissertations

This study investigated classification of 30 radar emitters with 16 signal features using Intel's 80170NX chip, the Electronically Trainable Analog Neural Network (ETANN). Software tools were developed to characterize the ETANN sigmoidal transfer function for use in a custom simulator, known as Neural Graphics. Neural Graphics operates on a Silicon Graphics workstation. The Intel Neural Network Training System simulators were used in early experiments, but were found to be inefficient in training on data used in this research. Using a modified Neural Graphics simulator, single chip and multi-chip experiments were performed to provide benchmark results prior to performing chip-in-loop training. …

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A Generic Template Extractor (Gentex) In C For Vlsi Design Verification, Kenneth J. Mcclellan Jr. Dec 1992

A Generic Template Extractor (Gentex) In C For Vlsi Design Verification, Kenneth J. Mcclellan Jr.

Theses and Dissertations

The problem of VLSI design verification through circuit extraction was analyzed. The problems of creating a simple template format, the permutability of pins, maintaining connectivity, and performance were focused on. A generic template extractor (GENTEX) was developed in the C programming language for use as a testbed to find solutions to these problems. Six different extraction algorithms were tested with GENTEX and compared based on performance. EDIF translation programs were used to interface with GENTEX on both the input and output sides. One translation program converted an EDIF representation of a schematic into the template format used by GENTEX. The …

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Signal Approximation With A Wavelet Neural Network, Charles M. Westphal Dec 1992

Signal Approximation With A Wavelet Neural Network, Charles M. Westphal

Theses and Dissertations

This study investigated the use of Wavelet Neural Networks (WNN) for signal approximation. The particular wavelet function used in this analysis consisted of a summation of sigmoidal functions (a sigmoidal wavelet). The sigmoidal wavelet has the advantage of being easily implemented in hardware via specialized electronic devices like the Intel Electronically Trainable Analog Neural Network (ETANN) chip. The WNN representation allows the determination of the number of hidden-layer nodes required to achieve a desired level of approximation accuracy. Results show that a bandlimited signal can be accurately approximated with a WNN trained with irregularly sampled data. Signal approximation, Wavelet neural …

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On The Difficulty Of Manhattan Channel Routing, Ronald I. Greenberg, Joseph Jaja, Sridhar Krishnamurthy Dec 1992

On The Difficulty Of Manhattan Channel Routing, Ronald I. Greenberg, Joseph Jaja, Sridhar Krishnamurthy

Computer Science: Faculty Publications and Other Works

We show that channel routing in the Manhattan model remains difficult even when all nets are single-sided. Given a set of n single-sided nets, we consider the problem of determining the minimum number of tracks required to obtain a dogleg-free routing. In addition to showing that the decision version of the problem isNP-complete, we show that there are problems requiring at least d+Omega(sqrt(n)) tracks, where d is the density. This existential lower bound does not follow from any of the known lower bounds in the literature.

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Optimal Control Of The Starfire Beam Director, Troy V. Lanier Dec 1992

Optimal Control Of The Starfire Beam Director, Troy V. Lanier

Theses and Dissertations

The Starfire Beam Director (SBD) is located at the Starfire Optical Range at Kirtland Air Force Base in Albuquerque, New Mexico. The SBD capabilities include tracking celestial objects and active or passive tracking of artificial satellites to support the Phillips Laboratory Ground Based Laser Acquisition, Tracking, and Pointing (GBL ATP) program. The pointing and tracking accuracy needed to support such experiments is micron rad to sub-grad level. To accomplish this goal requires precise pointing of the massive 6 ton 1 -meter clear aperture coelostat. The purpose of this thesis is to use optimal control design techniques to develop a controller …

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Design And Development Of A High-Speed Winograd Fast Fourier Transform Processor Board, James F. Herron Dec 1992

Design And Development Of A High-Speed Winograd Fast Fourier Transform Processor Board, James F. Herron

Theses and Dissertations

Since 1985, the Air Force Institute of Technology has pursued a project to develop a 4080-point Discrete Fourier Transform processor using the Winograd Fourier Transform Algorithm (WFTA) and Good-Thomas Prime Factoring Algorithm (PFA). In the first attempt to build a working system, this research effort designed and constructed, in part, a modified single processor architecture in order to demonstrate the proof of concept of the WFTA system design. This prototype architecture is simpler in implementation but uses the same principles and procedures as those of the 4080-point WFTA design. The design developed in this thesis was validated using the Very …

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Version And Transaction Management In Osmagic: An Object-Oriented Database Implementation Of The Magic Vlsi Layout Design Tool, Gary M. Lightner Dec 1992

Version And Transaction Management In Osmagic: An Object-Oriented Database Implementation Of The Magic Vlsi Layout Design Tool, Gary M. Lightner

Theses and Dissertations

The goal of this thesis was to study the feasibility of using an object-oriented database management system to provide the functionality and performance needed to support a complex computer-aided design tool. We do this by modifying OSMagic, a prototype system of the Magic very large scale integrated (VLSI) circuit design tool implemented on the ObjectStore object- oriented database management system. OSMagic was changed to support three different interfaces to ObjectStore and to work in a networking environment. We then designed and examined the use of version and transaction management models as a means of addressing the weaknesses of the prototype …

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Scientific Visualization Of Volumetric Radar Cross Section Data, Thomas G. Wojszynski Dec 1992

Scientific Visualization Of Volumetric Radar Cross Section Data, Thomas G. Wojszynski

Theses and Dissertations

For aircraft design and mission planning, designers, threat analysts, mission planners, and pilots require a Radar Cross Section (RCS) central tendency with its associated distribution about a specified aspect and its relation to a known threat, Historically, RCS data sets have been statically analyzed to evaluate a d profile. However, Scientific Visualization, the application of computer graphics techniques to produce pictures of complex physical phenomena. appears to be a more promising tool to interpret this data. This work describes data reduction techniques and a surface rendering algorithm to construct and display a complex polyhedron from adjacent contours of RCS data. …

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Theory And Implementation Of Wavelet Analyses In Rational Resolution Decompositions, Bruce P. Anderson Dec 1992

Theory And Implementation Of Wavelet Analyses In Rational Resolution Decompositions, Bruce P. Anderson

Theses and Dissertations

The multiresolution analysis (MRA) developed by Mallat and Meyer and further discussed by Daubechies is a useful tool in the analysis of sampled signals such as images and speech. This thesis develops the theory and implementation of a rational-resolution analysis (RRA) as an extension of the dyadic MRA for arbitrary rational dilation factors. We present a method to calculate families of compactly-supported scaling functions and wavelets based on arbitrary integer dilation factors and provide examples. The perfect- reconstruction properties of the RRA are discussed and it is demonstrated that the compactly-supported scaling functions and wavelets do not yield perfect- reconstruction. …

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Design And Characterization Of Optically Pumped Vertical Cavity Surface Emitting Lasers, Richard J. Bagnell Dec 1992

Design And Characterization Of Optically Pumped Vertical Cavity Surface Emitting Lasers, Richard J. Bagnell

Theses and Dissertations

Vertical Cavity Surface Emitting Lasers (VCSELs) are a form of semiconductor laser which have their cavity oriented orthogonally to the plane of the wafer. The orientation necessitates short cavities, highly reflective mirrors and a relatively high gain/loss ratio. Even so, the resultant superior exit beam characteristics and the tight packing density of the finished lasers provide strong motivation for pursuing the growth of these structures. This thesis details the design of an optically pumped InGaAs multiple quantum well periodic gain structure VCSEL with a 950 nm lasing wavelength. These growths were to be a first attempt at VCSEL construction, so …

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Automated Control Of Aircraft In Formation Flight, Louis E. Buzogany Dec 1992

Automated Control Of Aircraft In Formation Flight, Louis E. Buzogany

Theses and Dissertations

In this study, an automated formation control system for an aircraft formation comprised of one lead and multiple wing aircraft is analyzed. Second- order models of the C-130 aircraft are developed in order to accurately model the flying qualities of large aircraft. This automated formation control system is capable of controlling the C-130 aircraft in maneuvering formation flight, thus reducing the wing's pilot workload. During formation flight, the wing aircraft continuously measures the lead aircraft's relative position with an ideal on-board position sensor. This information, in addition to Proportional Plus Integral feedback control, is used to maintain the aircraft in …

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Cepstral And Auditory Model Features For Speaker Recognition, John M. Colombi Dec 1992

Cepstral And Auditory Model Features For Speaker Recognition, John M. Colombi

Theses and Dissertations

The TIMIT and KING databases, as well as a ten day AFIT speaker corpus, are used to compare proven spectral processing techniques to an auditory neural representation for speaker identification. The feature sets compared were Linear Predictive Coding (LPC) cepstral coefficients and auditory nerve firing rates using the Payton model. This auditory model provides for the mechanisms found in the human middle and inner auditory periphery as well as neural transduction. Clustering algorithms were used to generate speaker specific codebooks - one statistically based and the other a neural approach. These algorithms are the Linde-Buzo-Gray (LBG) algorithm and a Kohonen …

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Kalman Filter Tracking Of A Ballistic Missile Using Forward Looking Infrared Measurements And Doppler Returns, Michael L. Ching Dec 1992

Kalman Filter Tracking Of A Ballistic Missile Using Forward Looking Infrared Measurements And Doppler Returns, Michael L. Ching

Theses and Dissertations

The Air Force Institute of Technology (AFIT) has been involved in developing Kalman Filter trackers for airborne targets for the last 14 years. The goal of this particular thesis was to track a ballistic missile in the boost phase at ranges up to 2000 km, in order to control a high energy laser weapon designed to destroy the target The filter developed combined an existing 'FLIR' filter, which estimated location of the plume intensity centroid based on measurements from a forward looking infrared sensor (FLIR), and an existing center-of-mass filter, which estimated the offset between the plume and missile center-of-mass …

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An Analytical And Experimental Investigation Of Fm-By-Noise Jamming, Charles J. Daly Dec 1992

An Analytical And Experimental Investigation Of Fm-By-Noise Jamming, Charles J. Daly

Theses and Dissertations

Among the jamming waveforms used in Electronic Warfare, FM-by-noise is the least understood, and no exhaustive analytical and experimental investigation of the subject exists. This investigation presents a thorough review, consolidation, and elucidation of the theory of FM-by-noise. To explain and predict the behavior of FM-by-noise at RF and IF, three useful ratios, namely the deviation-to-victim ratio, the noise-to-victim ratio, and the sweep- to-victim ratio, are developed. To complement the theory, results of FM-by-noise jamming experiments conducted using commercial test and measurement equipment are presented. Specifically, the time- and frequency-domain behavior of FM-by- noise at RF and IF is studied …

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Remote Sensing Of Turbulence And Transverse Atmospheric Wind Profiles Using Optical Reference Sources, Steven C. Koeffler Dec 1992

Remote Sensing Of Turbulence And Transverse Atmospheric Wind Profiles Using Optical Reference Sources, Steven C. Koeffler

Theses and Dissertations

This thesis examines a remote sensing technique for measuring the atmospheric structure constant and the transverse atmospheric wind velocity as a function of altitude by performing temporal and spatial correlations of band pass filtered wave front slope sensor measurements. Two point sources are used to illuminate two pairs-of cc>-located wave front slope sensors. The sources and sensors are arranged to give rise to crossed optical paths. For each pair of wave front slope sensors, the output of the larger sensor is subtracted from the output of the smaller sensor. This band pass filters the smaller sensor's output. The filtered …

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