Electrical and Electronics Commons^™

Monolithic Silicon Opto-Electro-Mechanical Light Modulator, Ching-Horng Wu

Theses

A Fabry-Perot light beam modulator of the reflection-type has been designed with process and performance parameters optimized. This design takes advantage of the economies of surface micromaching using silicon substrates and selected thin films. High performance with a low drive voltage are achieved using electrostatic actuation of a thin polysilicon diaphragm. The diaphragm is a novel corrugated structure which has maximum compliance and maintains planarity during actuation. In addition, the corrugationsuspension used provides an improved linearity of amplitude modulation response as a function of the actuation voltage.

A preliminary version of this device has been fabricated through a contract foundry …

Frequency Domain Speech Compression Using The Karhunen-Loeve Transform, Donald W. Dryley

Theses and Dissertations

The purpose of this study was test the influence of phase on the quality of speech reproduced by a speaker dependent compression system. The tests consisted of compressing frequency domain speech vectors using the Karhunen-Loeve Transform, with and without phase, then making subjective judgements as to the reproduced quality. Error Metrics were then tested for their suitability as predictors of reproduced quality. The compression software transformed each speech vector into a vector of complex Fourier coefficients (only half of the coefficients are needed as transform is hermitian). Phase was preserved by using the real frequency components to form one vector …

Self-Referenced Speckle Holography (Srsh) Image Reconstruction Performance, John R. Devey

Theses and Dissertations

The Speckle Holography technique uses a series of short exposure images and associated wave front sensor measurements to reconstruct astronomical images. The reconstruction technique effectively boosts the amplitude of high spatial frequencies to allow for finer resolution of astronomical objects. A simulation package that calculates the optical transfer function (OTF) of a telescopic system was previously developed for the Phillips Laboratory. This software was modified slightly to provide the Speckle Holography system transfer function (STF) for a telescopic system under varying seeing conditions.

Exact Modeling Of Time-Interval-Modulated Switched Networks, Weihe Niu

Dissertations and Theses

The frequency response analysis of switched networks plays a very important part in designing various kinds of power converter circuits. In this thesis two frequency response techniques for analyzing switching power converters are discussed. One method provides a mathematical description which treats the converter as a periodic time varying system. A linearized small signal model is subsequently derived. The major part of the thesis concentrates on this accurate exact small-signal technique. The derivation involves state space representation and the use of the time varying transfer function. A Fourier analysis is performed to show the relationship between the frequency response of …

Novel Cylindrical Illuminator Tip For Ultraviolet Light Delivery, Hanqun Shangguan

Dissertations and Theses

The design, processing, and sequential testing of a novel cylindrical diffusing optical fiber tip for ultraviolet light delivery is described. This device has been shown to uniformly(+/- 15%) illuminate angioplasty balloons, 20 mm in length, that are used in an experimental photochemotherapeutic treatment of swine intimal hyperplasia. Our experiments show that uniform diffusing tips of < 400 micron diameter can be reliably constructed for this and other interstitial applications. Modeling results indicate that this design is scalable to smaller diameters. The diffusing tips are made by stripping the protective buffer and etching away the cladding over a length of 20 mm from the fiber tip and replacing it with a thin layer of optical epoxy mixed with A/203 powder. To improve the uniformity and ease of fabrication, we have evaluated a new device configuration where the tip is etched into a modified conical shape, and the distal end face is polished and then coated with an optically opaque epoxy. This is shown to uniformly scatter - 70% of the light launched into the fiber without forward transmission. To our knowledge, we are the first to use this device configuration, and we have achieved a uniform cylindrical pattern of laser energy with uniformity < ± 15% of the average value. A simple computational model suitable for the interpretation of laser energy irradiance along the bare core surface of multimode optical fiber tips is proposed and experimentally verified. The model used is based on geometrical optics and Gaussian approximation. Good agreement is obtained between the calculation and experiment. We have measured the optical properties of the tips through all the sequences of the fabrication. The performances of the diffusing tips for illuminating angioplasty balloons are then evaluated by Ultraviolet Light at 365 nm. A Ti:Sapphire Ring Laser System with a doubling crystal pumped by an argon ion laser is used to generate the wavelength in this study.

Investigation Of The Consumer Electronics Bus, Jaesoo Yang

Dissertations

The objectives of this dissertation are to investigate the performance of the Consumer Electronics Bus (CEBus) and to develop a theoretical formulation of the Carrier Sense Multiple Access with Contention Detection and Contention Resolution (CSMA/CDCR) with three priority classes protocol utilized by the CEBus

A new priority channel assigned multiple access with embedded priority resolution (PAMA/PR) theoretical model is formulated. It incorporates the main features of the CEBus with three priority classes. The analytical results for throughput and delay obtained by this formulation were compared to simulation experiments. A close agreement has been found thus validated both theory and simulation …

On Adaptive Censored Cfar Detection, Loizos Anastasiou Prastitis

Dissertations

In an automatic radar detection system the received signal in every range resolution cell is compared with a threshold to test for the presence of a target. A Neyman-Pearson type test is used which maximizes the probability of detection for a fixed probability of false alarm. For the simple case where the noise is homogeneous a fixed threshold is chosen to achieve the designed constant false alarm rate (CFAR). In the more realistic case the noise background is non-stationary due to clutter and interference. In this situation, the threshold used for testing a particular cell is usually set adaptively using …

A Direct Method For Surface Structure Recovering Based On Uoff, Ping Lin

Theses

The unified optical flow field (UOFF) theory which can be used for estimating motion and recovering surface structure was recently established in [9, 10]. The direct method developed in [2, 3, 4, 6, 7] does not need to explicitly solve the optical flow field and to find feature correspondence. Based on the UOFF, a direct method in space domain is developed to reconstruct the curved surface structure characterized by an Nth degree polynomial equation from a pair of stereo images. The initial work on this new method was reported in [8, 11].

In this study, I basically work on simulation …

Translation Of Images On The Hypercube Using Leaf Codes, Bhavesh Patel

Theses

Image processing is used for manipulation of pictorial images. Image analysis applications are typically characterized by the need to process large quantities of image data. Some of the important transformations or operations which are car¬ried out by image processing systems are translation, scaling, superposition and rotation. Algorithms have been developed to carry out these transformations on image regions represented by quadtrees. Gargantini introduced an algorithm to translate an image region represented by a linear quadtree or leafcodes. A linear quadtree is a space efficient data structure used for storing digital images. Ziavras et.al. have proposed a modification of Gargantini's algorithm …

Optical Flow Determination And Motion Analysis, Qian Wang

Theses

Optical flow, also known as image flow, is of fundamental importance in the processing of image sequences. Various approaches to determine optical flow have been proposed --- others continue to appear. Using several sets of real image sequences, here, the results of three different approaches to the the determination of optical flow are reported, the approaches are the Gradient-based approach, the Correlation-based approach and the Correlation-feedback approach. The comparisons are primarily empirical, and they show that the performance of these different algorithms differs significantly among the different image sequences, indicating that there does not exists one superior algorithm which could …

Development Of A Model For An Objective Minimum Resolvable Temperature Difference Characterization Of An Infrared Camera, Christine Issa Mourad

Theses

The parameter almost universally adopted by the infrared community for describing the overall performance of a thermal imaging camera is the minimum resolvable temperature difference. Unfortunately, this criterion is subjectively determined by a group of observers and as a consequence significantly varying results can be obtained at different times. This project describes work on an approach which ultimately aims to replace the observers by a computer-aided installation that simulates the human process by which the MRTD is estimated. The simulation is based on a direct measurement of signal to noise ratio in the image of the target and a determination …

Reduction Of Acoustic Feedback Oscillations By Use Of Spectrum Shifting, Youssef Abdelilah

Theses

The problem of whistling noise or self-oscillation in public address systems operating in closed halls or rooms can be very disturbing to the listeners. This noise is sustained when the positive acoustic feedback, of the public address-room system, meets the oscillation criteria. This feedback system results from the acoustic sound signal reflected off the room walls and any other obstacles in the room, originating from the public address speakers and then re-entering the microphone.

When all of the audio signal components entering the public address system are shifted by a frequency increment Δf of 6 Hz, an increase of 5 …

A Successive Approximation Algorithm To Solve Motion Planning Problems, Cheng-Ming Chang

Theses

A successive approximation algorithm is presented to solve motion planning problems and optimal control problems. A motion planning problem is included in an optimal control problem and due to the heavily nonlinear and coulped differential equations describing the dynamics of the manipulator and several constraints imposed on the system, few efficient methods exist to solve this kind of problems.

The successive approximation algorithm can decompose the global nonlinear problem into several nonlinear subproblems and each subproblem is solved by the nonlinear programming method with a highly convergent rate. Because the limited constraints and variables are included in each subproblem and …

An Improved Human Gait Model Incorporating The Effects Of Muscle Activity And Joint Friction, Tae Ho Choi

Theses

In designing an artificial leg for an amputee, it is important to find those underlying principles which determine the normal human gait. For this purpose we have developed a model of human walking, in which it is possible to predict an optimal gait at any given speed of walking based on the principle of minimum mechanical energy consumption.

Our model is an extension of the model proposed by Mochon and McMahon (1980). Their model assumes that during the swing phase of walking mechanical energy is conserved. Non-conservative forces due to muscle activity are assumed to occur during the double support …

Studies Of Wet Thermal Oxidation Of Silicon And Porous Silicon, Nilesh A. Gharia

Theses

Wet Thermal Oxidation of Silicon in VLSI is an extremely important step in the formation of field oxides. Understanding oxidation kinetics is critical for process reproducibility. The present study aims at gaining an insight into the oxidation kinetics through large experimental data at process temperatures of 800°C, 900°C, 1000°C and 1100°C with a bubbler temperature of 98°C. Oxides with thicknesses ranging from 100A to 7000A have been grown. Rate constants are obtained for the growth kinetics. Extensive characterization studies have been performed on MOS structures produced after wet oxidation.

In addition, porous silicon which assumes a growing significance in the …

Microwave Gaas Mesfet Nonlinearity And Large-Signal Modeling, Yan He

Theses

The nonlinearity analysis for a 0.5μm gate length microwave GaAs metal-semiconductor field-effect transistor (MESFET) by HP85150B Microwave Design System was investigated. The analysis starts with the construction of a large-signal MESFET equivalent circuit model. This model consists of bias dependent elements that were extracted by the optimization of DC and small-signal S-parameter measurement data. The details on this construction procedure are included in this work. The MESFET third-order intermodulation distortion was then simulated by HP85150B Microwave Design System. Reasonable agreement was obtained between simulation and measurement results. Microwave GaAs MESFET nonlinearity principles and large-signal modeling technique review are also presented. …

Partial Vlsi Implementation Of The Architecture For Reusable Components (Arc), Deepak Kakadasam

Theses

This work describes a novel VLSI implementation of the Architecture for Reusable Components (ARC) processor, using Hardware Description Language (HDL). The main goal here is to achieve efficient execution of reusable software through proper hardware support. This involves the hard wired implementation of each instruction designed for the ARC processor.

Instructions are broken down into their logical functions, then modeled and simulated through the hierarchical design methods that HDL offers. The structural model of the processor has been developed and simulated. The purpose here has been to begin work on the design and implementation of the ARC processor.

The instructions …

Torque And Current Response Due To Singularity Changes Of Induction Machine Slip, Jessie G. Orpilla

Theses

Recognizing that the prime purpose of the 3 phase induction motor is to deliver torque with minimum line current. This thesis studies the torque as well as the current response produced by the singularity changes in the induction machine slip. It is desirable that the torque to be maximized for a given value of line current at the corresponding load slip.

This thesis analyzes the torque and current response, when a slip at no-load is changed to a unit-step, Qu(t), a unit-impulse, Qδ(t), a pulse characterized by Q[u(t)-u(t-T)], a unit-ramp, Qt, and a sinusoidal, Qsint, slip. The responses are analyzed …

A Programmable Integrated Power Supply For The Electrostatic-Drive Micromotor, Chao Ye

Theses

A 6-phase bipolarized, high-voltage power supply with rectangular pulse shape has been designed to study the special operational characteristics of various electrostatic-drive micromotors. In particular the design powers the variable-capacitance side-drive micromotor. This power supply provides variable frequency, variable voltage, and variable duty-cycle control. Simulation has been used extensively in the design and design verification.

The bipolarization (dual voltage polarity) of each pair of the phases reduces physical clamping of the rotor to the electrical shield beneath it. Thus, bipolarization of the voltage supplied to the stator nodes reduces charge build-up on the rotor.

The output frequency range varying from …

Three Dimensional Magnetic Field Sensors And Array In Bicmos Technology, Bingda Wang

Theses

This thesis presents new designs of three dimensional magnetic field sensors in BiCMOS technology. The detailed design of the merged structure device by common diffusion and the high gain transduction circuit are presented. The merged structure has the advantage of less area, less external contacts and less parasitic capacitance. Cross-sensitivity is also eliminated by employing the merged structure. Three active on-chip loads are introduced to improve the sensitivity. The SPICE simulation results show that when a relative change in current ΔI/I is 0.001, about 13.6 mV and 8.5mV can be detected at the output in X(or Y) and Z directions, …

Timed Petri Net Simulation Of Flexible Manufacturing Systems, Yan Chen

Theses

Standard Petri nets have been used to model and analyze Flexible Manufacturing Systems. The timed Petri net, which can incorporate the time delay associated with manufacturing events, provides additional information about real time behavior of practical systems. The Timed Petri Net Simulation Tool, a highly interactive graphical tool, is applied to simulate the modeled flexible manufacturing systems. Timed Petri net models are experimented with. Machine utilization data and throughput are obtained. Analysis of the results shows that the system performance can be optimized by choosing proper parameters.

Performance Analysis Of Pyramid Mapping Algorithms For The Hypercube, Jing-Chiou Liou

Theses

Comparative performance analysis of algorithms that map pyramids and multilevel structures onto the hypercube are presented. The pyramid structure is appropriate for low-level and intermediate-level computer vision algorithms. It is not only efficient for the support of both local and global operations but also capable of supporting the implementation of multilevel solvers. Nevertheless, pyramids lack the capability of efficient implementation of the majority of scientific algorithms and their cost may become unacceptably high. On a different horizon, hypercube machines have widely been used in the field of parallel computing due to their small diameter, high degree of fault tolerance, and …

Application Of Imaging Pyrometry For Remote Temperature Measurements, Michael B. Kaplinsky

Theses

The radiometric model of an IR image sensor has been developed. Based on this model, the application of imaging pyrometry to remote temperature measurements has been investigated. This analysis provides the estimation of temperature accuracy achievable by imaging pyrometry in conjunction with a number of radiometric methods. The detection of radiation emitted across the full spectral bandwidth of the imager as well as utilization of narrow-passband filters was analyzed for a target with known emissivity.

The methods of two-wavelength ratio radiometry and multi-wavelength radiometry were considered for the targets with unknown emissivity. The optimal selection of the wavelengths for the …

Modal Control Of Flexible Beam Using Smart Mateirals, Sujata Mallepalle

Theses

In this work, the dynamics and control aspects of a vibrating flexible beam using modal analysis are studied. To damp the vibrations of the system, the vibrations of each mode has to he controlled, which can he done if we know the individual mode shape. and the resonance frequency. These quantities can be derived mathematically or measured experimentally with a spectrum analyzer. Individual modal velocities can be computed by integration of the product of beam velocity and the mode shape, over the interval of beam length. The integration is carried out using numerical methods. The necessary discrete ordinates are obtained …

Design Of Holographic Optical Interconnections, Su-Chiou Tsay

Theses

Optics have many advantages over electronics in interconnecting systems together, particularly in terms of higher transmission speed and better immunity to noise. Optical interconnections may be used at all levels of computing: for local area networks, between processors or memory elements, and between boards.

In this thesis, we attempted to generate a new type of computer hologram for optical interconnection purposes. The holographic method is very promising whenever integrated optical interconnections are considered. In this research we have tried two designs: the shortest path grating design which can maximize the global output energy and the single input maximum output grating …

Studies Of Electron-Beam Penetration And Free-Carrier Generation In Diamond Films, R. P. Joshi, K. H. Schoenbach, C. Molina, W. W. Hofer

Bioelectrics Publications

Experimental observations of the energy‐dependent electron‐beam penetration in type II‐A natural diamond are reported. The experimental data are compared with results obtained from numerical Monte Carlo simulations, and the results are in very good agreement. The results also reveal that a threshold energy of about 125 keV is necessary for complete penetration for a 35 μm sample. It is found that over the 30–180 keV range, the energy dependence of the penetration depth and total path length exhibits a power‐law relation. Monte Carlo simulations have also been performed to investigate the excess carrier‐generation profiles within diamond for a set of …

Surface Emitting Semiconductor Lasers And Arrays, Gary A. Evans, Jacob M. Hammer

Electrical Engineering Research

No abstract provided.

Temporal Development Of Electric Field Structures In Photoconductive Gaas Switches, K. H. Schoenbach, J. S. Kenney, F.E. Peterkin, R. J. Allen

Bioelectrics Publications

The temporal development of the electric field distribution in semi‐insulating GaAs photoconductive switches operated in the linear and lock‐on mode has been studied. The field structure was obtained by recording a change in the absorption pattern of the switch due to the Franz–Keldysh effect at a wavelength near the band edge of GaAs. In the linear mode, a high field layer develops at the cathode contact after laser activation. With increasing applied voltage, domainlike structures become visible in the anode region and the switch transits into the lock‐on state, a permanent filamentary electrical discharge. Calibration measurements show the field intensity …