Engineering Commons^™

Computer Aided Localization Of Neurological Diseases, Yusuf Parlar

Dissertations

Computers in medicine has brought new dimensions and better understanding of uncertainties in the field of medical sciences in the last decade. This thesis is focused upon the localization of neurological lesions in the human nervous system. It relates clinical neurological test outcomes to pathways of function or malfunction. Certain methods are proposed-empirical. stochastic. Deterministic-to estimate the spatial distributions of lesion probabilities.

First. a Bayesian model is presented to estimate the posterior probability of lesion from a priori information, based on the test outcomes. Due to unavailable data alternative methods and models are presented: Regression Analysis. Monte Carlo simulation, and …

On The Performance Of Minimum Redundancy Array For Multisource Direction Finding, Byung-Seub Lee

Dissertations

As an application of power spectrum estimation, the multi-source direction finding has been evolved from conventional FFT method to Superresolution methods such as Multiple Signal Classification(MUSIC) algorithm. Uniform Regular Array(URA) was mainly used in all these approaches.

The Minimum Redundancy array(MRA); a non-uniform thinned array which results in an input signals covariance matrix with minimum redundancy has been shown to have certain interesting properties for spectrum estimation. Only recently it was suggested to use the MRA for spatial estimation. The purpose of this research was to study the performance of this array in multi-source direction finding estimation and compare it …

Computer Modeling And Analysis Of Biological Rhythms, Shi Xiong Yang

Dissertations

Biological rhythms are an important phenomenon and feature of physiologic systems. Indirect means have to be employed for their description and exploration due to the unclear internal nature of the system. This study analyzed and developed several possible mathematical models using single or multidimensional nonlinear differential equations to approach the experimental circadian data. The numerical solutions of the models were obtained by computer simulation and the simulated and experimental acquired circadian data were analyzed in both the time and frequency domains. Phase plane plots, phase response curves and power spectrum analysis were employed to determine the nonlinearity of the system …

Propagation Of Millimeter Wave Signals In Forests Using The Equation Of Radiative Transfer With Strong Forward Scattering Phase Functions, Nack Yang Cho

Dissertations

A forest is a highly scattering medium at millimeter wave frequencies. The propagation of cw millimeter wave signals in forests has been studied previously, both theoretically and experimentally. Published experimental data verified that continuous wave transmission is possible over lengths of the order of a few hundred meters and that a forest acts to strongly scatter energy in the forward direction. The cw studies yielded the determination of the range dependence, beam broadening effects and depolarization effects of millimeter wave signals in a forest. However, pulse broadening effects, which are of importance particularly in the case of digital signal transmission, …

Fault-Tolerant Interconnection Networks For Multiprocessor Systems, Hamed Mohamed Nassar

Dissertations

Interconnection networks represent the backbone of multiprocessor systems. A failure in the network, therefore, could seriously degrade the system performance. For this reason, fault tolerance has been regarded as a major consideration in interconnection network design. This thesis presents two novel techniques to provide fault tolerance capabilities to three major networks: the Baseline network, the Benes network and the Clos network.

First, the Simple Fault Tolerance Technique (SFT) is presented. The SFT technique is in fact the result of merging two widely known interconnection mechanisms: a normal interconnection network and a shared bus. This technique is most suitable for networks …

Assessment Of Autonomic Regulation Of Heart Rate Variability, Shaw-Jyh Shin

Dissertations

Complex demodulation, accompanied by the techniques of interpolation, detrending and zero-phase-shift lowpass filtering were used to examine the effect of both divisions of the autonomic nervous system (sympathetic and parasympathetic) on heart rate by analyzing the heart rate variability signal from dogs under two different classical conditionings: CS+ and CS-, which cause different dynamic pattern changes in the autonomic nervous system to regulate the heart rate.

Unlike power spectral analysis, complex demodulation gives results in the time domain and shows the variation of amplitude and phase over time at a given frequency. The variation of phase indicates the frequency deviation …

Investigation Of Pre-Detection Signal Processing Of Pseudonoise Communication Signals In The Presence Of Additive White Gaussian Noise And Cw And Bursty Interference, Israel Mayk

Dissertations

By comparison to conventional communication systems, spread-spectrum systems are known to be less affected by interference because of their large dimensionality in signal space. Nevertheless, significant performance degradation is experienced when large interference exists in a few or even one signal coordinates. In this case, interference reduction techniques are also known to provide additional processing gain. A novel class of pseudonoise (PN) invariant algorithms is derived to reduce the impact of interference and restore much of the structure of PN signals received in the presence of interference and noise. A PN signal received by a pre-detection signal process (PDSP) implementing …

The Effect Of A Higher Order Pole On The Optimum Design Of Minimum Threshold Phase Locked Detectors, Bernard Zivotofsky

Dissertations

The phase lockedloop is widely used as an FM demodulator known as a phaselocked detector (PLD). It is particularly useful in the detection of weak signals because lower threshold is possible with a PLD than with a conventional limiter discriminator. An enhanced version PLD known as an extended range phaselocked detector (ERPLD) is capable of further threshold reduction. The most popular PLD is a second order type I system employing a loop filter having one real pole and one real zero.

One implementation of an ERPLD calls for the addition of a differentiator to the standard loop filter which replaces …

Decentralized Optimal Control With Application To Dynamic Routing In Computer Communication Networks, Ning Wang

Dissertations

This research considers the dynamic routing problem of computer communication networks in the framework of decentralized control theory. The routing dynamics are modeled in terms of a state equation with multiple controllers. Routing, or control of message flow, is formulated as an optimal control problem with multiple decision makers. Each decision maker may have access to different set of information and work cooperatively to optimize a common system performance index.

Necessary and sufficient conditions for optimality are derived for a system with a deterministic and a stochastic traffic patterns under a linear information structure and a quadratic performance index. The …

Optimization Of A New Linear Fm Detector Using Digital Signal Processing Techniques, Edward J.A. Kratt

Dissertations

This dissertation describes and synthesizes a new member of the family of FM detectors introduced earlier by Klapper and Kratt. A salient property of these detectors is low delay with excellent sensitivity. The emphasis in the new detector is on the ease of digital implementation. In addition, the new detector is also extremely linear. In congruence with the other Klapper-Kratt detectors, it makes use of zero group delay elements, balance at RF, quasi-synchronous detection and carrier cancellation. The Performance of the detector is mathematically analyzed under the conditions of a modulated input wave, sinewave [sic] interference, and noise. The results …

Application Of Fuzzy Theory To Pattern Recognition, David Usechak

Dissertations

Piecewise curve approximation is used to describe boundaries of objects in pictures and waveforms. The method consists of linear and quadratic piecewise polynomial approximations in which the error must not exceed a predetermined cost threshold. A fuzzy Bayes model is used to determine if a breakpoint exists within an interval I_n or between intervals I_n and I_n+1 and to determine whether these intervals can be merged for data compaction reasons. In order to achieve these objectives a new fast algorithm has been proposed which gives good curve/object fitting. This algorithm uses a technique for generating generalized inverse …

Broadband Base Isolated Asymetrically Fed Vhf Antenna, Peter Edward Cunningham

Dissertations

Antennas presently being used for vehicular military VHF communications are narrowband. New generation frequency hopping radios, however, require broadband antennas. The antenna must be base isolated in order to reduce undesirable pattern nulls and impedance variations caused by currents induced on the support structure. Physical constraints limit the antenna length to three meters while operating from a frequency of 30 MHz to 88 MHz.

To satisfy the above requirements a model of a broadband, base isolated, cylindrical antenna less than three meters long was analyzed and built. Equations for the current distribution as a function of the physical parameters were …

Remote Attitude Measurement Techniques, Frank John Elmer

Dissertations

A method has been developed for solving practical problems which can be expressed in terms of physical geometry. These problems often involve combining directional information observed by remotely located sensors reported in their own respective local coordinate systems. To transform this information into a common coordinate system, the attitude of the sensors must be measured with respect to this common coordinate system.

Physical geometry is a generalization of mathematical -geometry where objects define the endpoints of figures composed of ensembles of lines. A probabilistic approach has been taken which is based on the fundamental assumption that the objects can be …

Analysis Of Oscillations In Nonlinear Systems Using Multiple Input Describing Functions, Frederic Lee Swern

Dissertations

Sufficient conditions for oscillation as well as absence of oscillations are presented for a class of systems containing one lumped linear element and a differentiable nonlinearity. The results are obtained by estimating the error inherent in using a describing function analysis. Contraction type arguments are used to show common topological properties of the describing function solution and the balance of first harmonic terms of the system.

After discussing the describing function method, two theorems are presented regarding existence or nonexistence of oscillations from homotopic considerations. A graphical method for examining systems with power law nonlinearities is given using a parameter …

Investigations Of Gate Turn-Off Structures, Hans Werner Becke

Dissertations

Research and Development was done on gate turn-off devices. The aim was i) to improve turn-off capability without compromise of turn-on, on-state, and useful temperature range, ii) to implement "safe" turn-off.

A) The dependence of the electrical device characteristics on cathode width for an optimized vertical structure was determined. Fall times of 100 to 200 nsec and risetimes of <400 nsec were simultaneously obtained for average current densities of 53 A/cm² @ T_j = 125°C. From spreading resistance analysis the fast t_r and t_f response is shown to be a consequence of proper Au-distribution in the active device volume.

From transient analysis it is concluded that for safe …

Statistical Averaging In Position Determination By Holography Under Turbulence Conditions, Paul Aloysius Mcgovern

Dissertations

An investigation of several, disparate phenomena is conducted with the aim of developing a novel surveying system capable of overcoming the limitations imposed by turbulence in modern surveying. This method incorporates standard holographic techniques and time domain statistical averaging of survey data.

Some pertinent characteristics of atmospheric turbulence are reviewed, and the restrictions imposed on standard surveying practices by such turbulence are identified. A model for the turbulent medium is proposed on the basis of previous work and several theoretical results are summarized and extended.

On this basis the technical characteristics of the proposed technique are developed and each step …

The Minimum Maximal-Cube Covering Approach To Switching Theory, Yu-Tsang Gene Hwang

Dissertations

This dissertation is devoted to the construction of a new algebraic structure for the K-map so that algorithms and theorems can be derived for the minimization of Boolean functions and at the same time provide for the manipulation of Boolean functions as freely as one could on the K-map.

Computer programs have been included to demonstrate the theory and numerous examples of various complexity have been worked out in the appendices.

Theory And Design Of Cyclotron-Wave Traveling-Wave Amplifiers, Arthur H. Gottfried

Dissertations

A theory and design procedure for traveling-wave tubes using cyclotron-wave interactions is developed. An analysis is presented of the energy exchange mechanism and the axial beam velocity spread induced by the r.f. interactions. The analysis of the energy spread in a realistic model of the beam with nonzero size and nonzero space-charge density shows that higher maximum efficiencies at higher power is attainable (with collector depression) in cyclotron-wave amplifiers than in synchronous-wave amplifiers.

A one-watt, and a ten-watt cyclotron-wave amplifier at 3 GHz, utilizing bifilar helix circuits, scaled from a 2 kW, 5 GHz design, were constructed. A computer was …

Noise Performance Of The Klapper-Kratt Low Delay Fm Detector, Allan Brown Tarbell

Dissertations

In this dissertation the dual differentiator version of the Klapper-Kratt FM detector family is investigated with additive Gaussian noise. Prior analysis of this new detector family has been limited to the noiseless case.

The investigation was conducted both analytically and experimentally. First, the dual differentiator version of the Klapper-Kratt detector was mathematically analyzed, assuming an unmodulated carrier plus additive Gaussian noise. This analysis was verified by assembling the detector and measuring its performance in the laboratory.

It was discovered that the Klapper-Kratt detector without limiter performs identically to the conventional limiter discriminator in the linear improvement region. When compared to …

Signal Processing Techniques For Analysis Of Heart Sounds And Electrocardiograms, Alan D. Bernstein

Dissertations

Audible heart sounds represent less than 5% of the vibrational energy associated with the cardiac cycle. In this study, experiments have been conducted to explore the feasibility of examining cardiac vibration by means of a single display encompassing the entire bandwidth of the oscillations and relating components at different frequencies. Zero-phase-shift digital filtering is shown to be required in producing such displays, which extend from a recognizable phonocardiogram at one frequency extreme to a recognizable apexcardiogram at the other. Certain features in mid-systole and early diastole, observed by means of this technique, appear not to have been previously described.

Frequency …

Synthesis Of Multiarea Grid Power Systems, Bharat C. Patel

Dissertations

This dissertation presents improved development in the formation of a generalized transmission loss (B)-matrix for a multiarea grid power system. In the procedure, the individual tie powers of each area are replaced by the net interchange, sneak and circulating powers. The latter two variables are directly eliminated in the power reference frame using actual impedances, unlike current methods that require the elimination of sneak and circulating currents, the formation of complex tie current model and the complex tie power model. Consequently, manipulation of large complex current, power and impedance matrices is avoided reducing both computer time and memory requirement. Further, …

Reliability And Surface Degradation Aspects Of Synthetic Insulator Materials For Hv Application, Satyapal S. Bhatia

Dissertations

This study is a theoretical and experimental investigation on the state of the art of synthetic insulators for outdoor high voltage transmission systems.

The surface of a polymeric material is known to be degraded by, among other things, environmental stresses such as UV, air pollutants, etc. The reliability of an insulator material is governed by the surface and other characteristics that do not drift much as a function of stresses and time.

The surface characteristics of various synthetic materials, when these materials were exposed to UV radiation in the laboratory were studied. The changes in the surface properties of these …

Reliability Of Mos Devices : Threshold Voltage Instability, Sesha Rajamani Shankar

Dissertations

A very important factor in the reliability of MOS devices is the stability of the threshold voltage. This dissertation examines the effects of positive and negative gate bias stresses at elevated temperatures on the drift in the threshold voltage of MOS field effect transistors.

Over 400 p-channel enhancement mode devices were life tested under different temperature and gate bias conditions for periods of up to 15,000 hours, and the drift in their threshold voltages studied and analyzed. It was found that under both negative and positive bias-temperature tests, the threshold voltage drifted towards more negative values, though in the negative …

Acoustical Holography By Holographic Interferometry, Amin Mohamed Hanafy

Dissertations

The ability to "see" with sound has long been an intriguing concept. It is apparent that ultrasonic energy can give an image of an object not obtainable with light or even with x-rays.

In this dissertation, a novel "three-step acoustical holographic imaging system" is described and several means for its implementation are analyzed. A novel holographic acoustic image converter, which constitutes a fundamental link in the three step imaging method was also developed. The use of optical holographic techniques to convert an arbitrary acoustic image to a visible image is conducted and resulted in the introduction of the new technique …

Application Of Multilevel Control Techniques To Classes Of Distributed Parameter Plants, Frederick Donald Chichester

Dissertations

This study concerns the application of a combination of multilevel hierarchical systems analysis techniques and Pontryagin's minimum principle (multilevel control) to the problem of controlling optimally two classes of dynamic distributed parameter plants representing concentrations balances in streams, rivers and estuaries. The concentrations treated in this study are those deemed the most effective indicators of water quality, dissolved oxygen (DO) and biochemical oxygen demand (BOD).

One class of plants treated in this study consists of linear continuous distributed parameter plants represented mathematically by sets of simultaneous partial differential equations. Optimal control of a plant of this class is initiated by …

The Effects Of Optical Path Perturbations During Recording On A Reconstructed Holographic Image, Stevan Israel Feldman

Dissertations

The effects of optical path perturbations occurring during recording on the reconstructed image of a hologram are investigated. It is shown that such variations of optical path are equivalent to conditions of holographic interferometry which can be classified in three categories: 1) object motion alone, 2) film motion alone, and 3) simultaneous film and object motion; all motions are defined with respect to the stationary reference source during the recording of the hologram.

The theory concerning the effects of object motion alone on the radiance distribution of a reconstructed holographic image has already been developed by previous researchers and is …

Investigation And Optimum Design Of The Generalized Second-Order Phase-Locked Loop, William Allen Novick

Dissertations

In this dissertation, a second-order phase-locked loop (PLL) in which the loop filter contains complex zeros is investigated in both its linear and nonlinear modes of operation; prior designs used a filter containing a simple zero on the negative real axis. This "generalized" second-order PLL had been heretofore essentially unexplored.

The basic characteristics of the generalized second-order PLL operating in the linear mode including the open and closed-loop responses and the corresponding root locus were generated and compared against those of the conventional second-order PLL. As in the conventional case, the generalized second-order PLL is found to be unconditionally stable. …

An Investigation Of The Optical Absorption Properties Of Silicon As Related To Its Electrical Conductivity, Onofrio Louis Russo

Dissertations

The purpose of this study is to demonstrate the feasibility of obtaining the electrical conductivity of band gap semiconductors, by considering the absorption of radiation in the visible region. The experimental evidence confirmed predictions that the conductivities of the silicon samples are related to the horizontal displacement of energy in the absorption curves. The material used in this study was p-doped silicon, although the approach should be valid in general for either elemental or compound semiconductors.

The absorption coefficient for silicon was measured in the radiation region between 2.0 and 3.0 ev. This region above the indirect band gap (= …

Optimal Control And Identification Of Stochastic Systems Using Differential Game Theory, Harry Marvin Burbank

Dissertations

This dissertation deals with linear systems subjected to stochastic disturbances. The class of stochastic processes considered is the class of second order stochastic processes characterized by having finite continuous covariance. The properties of the covariance provide means to formulate optimization problems without the difficulties present when the covariance is not finite or continuous.

The first aspect studied was several classes of optimal control problems. The effects of the stochastic processes were approximated by the effects of its first two moments. This procedure resulted in allowing optimal system controls to be found whatever the first two moments of the stochastic input …

The Theory Of Multiple Measurements Techniques In Distributed Parameter Systems, Babajimi Claudius Okunseinde

Dissertations

A comprehensive theory of multiple measurements for the optimum on-line state estimation and parameter identification in a class of noisy, dynamic distributed systems, is developed in this study. Often in practical monitoring and control problems, accurate measurements of a critical variable are not available in a desired form or at a desired sampling rate. Rather, noisy independent measurements of related forms of the variable may be available at different sampling rates. Multiple measurements theory thus involves the optimum weighting and combination of different types of available measurements. One of the contributions of this work is the development of a unique …