Digital Commons Network^™

Adaptive Receivers For Direct-Spread And Multi-Carrier Code Division Multiple Access Systems, Xiangqun Liu

Theses

In this thesis, the detection of Direct Sequence Code Division Multiple Access (DS-CDMA) signals in an AWGN channel and Multi-Carrier (MC) CDMA signals in a time-dispersion channel is discussed.

The DS-CDMA receiver employs an adaptive multiuser interference canceler that utilizes deadzone limiters in the tentative decision stage. With weights adjusted adaptively, the prior knowledge of signal powers is unnecessary. The steady state error performance of this receiver is obtained and found to be superior to the performance of the same receiver using hard limiters for tentative decisions. The channel is considered non-fading in. this receiver.

Modeling the frequency selective channel …

Low Cost Schottky Barrier Solar Cells Fabricated On Cdse And Sb2S3 Films Chemically Deposited With Silicotungstic Acid, O. Savadogo, K. C. Mandal

Faculty Publications

No abstract provided.

Generalized Reverse Theorems For Multipass Applications In Matrix Optics, Lee W. Casperson, Anthony A. Tovar

Electrical and Computer Engineering Faculty Publications and Presentations

The reverse theorem that governs backward propagation through optical systems represented by transfer matrices is examined for various matrix theories. We extend several reverse theorems to allow for optical systems represented by matrices that may or may not be unimodular and that may be 2 × 2 or take on an augmented 3 × 3 form. As an example, we use the 3 × 3 form of the reverse theorem to study a laser with intracavity misaligned optics. It is shown that, by tilting one of the laser's mirrors, we can align the laser output arbitrarily, and the mirror tilt …

Biofeedback Gait Training Auditory Vs. Visual Techniques, Timothy D. Hiemenz

Electrical & Computer Engineering Theses & Dissertations

Training lower extremity amputees to walk normally is quite a difficult task. Amputees must wear a prosthesis so they can walk at all. This allows them some mobility, but their walking pattern may be unnatural. If their gait is temporally asymmetric, they need to exert more energy to move about. This research was initiated to help lower extremity amputees to walk more efficiently using biofeedback gait training. Two types of feedback were developed and tested to determine which method gave the most understandable feedback, validating its use in a clinical setting.

A normal gait cycle uses the lower limbs to …

The Impact Of Electronic Ballast Compact Fluorescent Lighting On Power Distribution Systems, Reid Iwao Sasaki

Department of Electrical and Computer Engineering Technical Reports

Due to the high costs of expanding generation and transmission capacities, utilities have been initiating programs to reduce peak power demand by the customer. A number of these programs, which are commonly referred to as demand side management programs, have turned to the promotion of electronic ballast compact fluorescent lamps (CFLs) as an alternative to traditional incandescent lamps. These lamps provide a higher luminance and increased life as compared to their incandescent counterparts. Unfortunately, electronic ballast CFLs consume large amounts of harmonic current which may prove detrimental to the power distribution system. This thesis presents an introduction to the electronic …

An Appraisal Of Electricity Supply In Nigeria And The Privatisation Option, E. I. K. Sule, C. M. Anyanwu

CBN Occasional Papers

Incessant electric power cuts in most parts of the country has become a normal feature of electricity supply throughout Nigeria. The power outages cause much inconvenience and economic losses to all and sundry. This study has shown that the most critical factor behind the incessant power failure is the problem of inadequate funding of the industry at a time it was forced to accommodate rapid expansion. Other factors include lack of autonomy, inefficiency, poor organization as well as lack of skilled manpower. The paper has examined these problems on the basis of which suggestions are made on how the worrisome …

Investigation Of Fundamental Mechanisms Of Common-Mode Radiation From Printed Circuit Boards With Attached Cables, James L. Drewniak, Todd H. Hubing, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

Fundamental mechanisms leading to common-mode radiation from printed circuit boards with attached cables have been studied. Two primary mechanisms have been identified, one associated with a differential-mode voltage that results in a common-mode current on an attached cable, and another associated with a differential-mode current that results in a common-mode current on the cable. The two mechanisms are demonstrated through numerical and experimental results.

Schottky Effect At A Metal-Polymer Interface, G. Rikken, David Braun, E. Staring, R. Demandt

Electrical Engineering

We report the observation of the Schottky effect at the interface between a metal and a semiconducting polymer by means of internal photoemission spectroscopy. The bias dependence of the barrier provides information on the electrical properties of the polymer.

Direct Relation Between Fresnel's Interface Reflection Coefficients For The Parallel And Perpendicular Polarizations: Erratum 2, R. M.A. Azzam

Electrical Engineering Faculty Publications

The record is set straight concerning two equations that determine the reflection phase shifts at a single interface from the intensity reflectances forp- and s-polarized light at one angle of incidence. These equations appeared previously in this journal [J. Opt. Soc. Am. 69, 1007 (1979); erratum, J. Opt. Soc. Am. 70, 261 (1980)].

Transfer Function Matrix Identification From Input-Output Frequency Response Data, Zhiqiang Gao, Bruce Tabachnik, Razvan V. Savescu

Electrical and Computer Engineering Faculty Publications

A new formulation of transfer function matrix identification in frequency domain is introduced. It reduces the problem to a simple linear least square problem. It is shown that such a system identification problem is a special case of a matrix interpolation problem and much insight can be obtained by examining its algebraic characteristics. A new approach is proposed to determine the transfer function matrix of a multi-input and multi-output system from the input-output data. It eliminates the common assumption in the literature that the frequency response of the system is given. Its efficiency and practicality …

Simulation Of Communication Systems, William H. Tranter, Kurt Louis Kosbar

Electrical and Computer Engineering Faculty Research & Creative Works

When both a complex system and a complex channel model are encountered, the result is typically a design or analysis problem that cannot be solved using traditional (pencil and paper) mathematical analysis. Computer-aided techniques, which usually involve some level of numerical simulation, can be a very valuable tool in these situations. The purpose of this article is to provide a tutorial review of some of the basic techniques of communication system simulation. The authors consider the basic techniques used to represent signals, generate signals, and model linear systems, nonlinear systems, and time-varying systems within a simulation. They consider the important …

Hardware Assists For High Performance Computing Using A Mathematics Of Arrays, H. Pottinger, W. Eatherton, L. Mullin, T. Schiefelbein

Computer Science Technical Reports

Work in progress at the University of Missouri - Rolla on hardware assists for high performance computing and communication is presented. This research consists of a field programmable gate array based rapid prototyping environment (Chameleon) being used to evaluate hardware architectures for speedup of array partitioning and routing algorithms. These algorithms have been developed using a Mathematics of Arrays (MOA) and are optimal in the sense that they reduce normal array indexing operations to a series of primitive additions based on array shape. The method is simple yet powerful, produces algorithms which are provably correct, and are independent of dimensionality. …

An Fpga Based Reconfigurable Coprocessor Board Utilizing A Mathematics Of Arrays, H. Pottinger, W. Eatherton, T. Schiefelbein, L. Mullin, R. Ziegler

Computer Science Technical Reports

Work in progress at the University of Missouri-Rolla on hardware assists for high performance computing is presented. This research consists of a novel field programmable gate array (FPGA) based reconfigurable coprocessor board (the Chameleon Coprocessor) being used to evaluate hardware architectures for speedup of array computation algorithms. These algorithms have been developed using a Mathematics of Arrays (MOA) and are optimal in the sense that they reduce normal array cartesian indexing operations to a series of primitive additions and offsets based on array shape. The method is simple yet powerful, produces algorithms which are provably correct, and are independent of …

Spatio-Temporal Pattern Recognition Using Hidden Markov Models, Kenneth H. Fielding

Theses and Dissertations

A new spatio-temporal method for identifying 3D objects found in 2D image sequences is presented. The Hidden Markov Model technique is used as a spatio-temporal classification algorithm to identify 3D objects by the temporal changes in observed shape features. A new information theoretic argument is developed that proves identifying objects based on image sequences can lead to higher classification accuracies than single look methods. A new distance measure is proposed that analyzes the performance of Hidden Markov Models in a multi-class pattern recognition problem. A three class problem identifying moving light display objects provides experimental verification of the sequence processing …

A Diffraction-Based Model Of Anisoplanatism Effects In Adaptive Optic Systems, Steven E. Troxel

Theses and Dissertations

This dissertation presents a new model for computing the angle dependent performance measures of an adaptive-optics system. By incorporating diffraction caused by the index-of-refraction variations of the atmosphere, the phase and amplitude fluctuations of the propagating wave are computed. New theory is presented, that uses the diffraction-based propagation model to yield optical transfer function (OTF) expressions that are more accurate as compared to current theory that neglects diffraction. An evaluation method for calculating the OTF is presented that utilizes a layered atmospheric model and normalized OTF expressions. The diffraction model is also used to present the first OTF signal-to-noise ratio …

Motion Estimation Using Optical Flow Field, Jingning Pan

Dissertations

Over the last decade, many low-level vision algorithms have been devised for extracting depth from intensity images. Most of them are based on motion of the rigid observer. Translation and rotation are constants with respect to space coordinates. When multi-objects move and/or the objects change shape, the algorithms cannot be used.

In this dissertation, we develop a new robust framework for the determination of dense 3-D position and motion fields from a stereo image sequence. The framework is based on unified optical flow field (UOFF). In the UOFF approach, a four frame mode is used to compute six dense 3-D …

Investigation Of Paraelectric Ptl Thin Films Using Reactive Magnetron Sputtering, Hyun Hoo Kim

Dissertations

The study of methods to prepare paraelectric perovskite PLT (Pb_1-xLa_xTi_1-x/4O₃; x=0.28) thin films has been important because thin films of this high dielectric strength material are required to make high density capacitors for dynamic random access memory. In this research, paraelectric PLT thin films were prepared on multi-layer (Pt/Ti/SiO₂/Si) and MgO substrates in a unique way by the reactive magnetron sputtering method using a multi-component metal target. The individual control of each metal area on the sputtering target had considerable influence on the stoichiometry and electrical properties of the thin …

Blind Detection In Channels With Intersymbol Interference, Raafat Edward Kamel

Dissertations

In high speed digital transmission over bandlimited channels, one of the principal impairments, besides additive white Gaussian noise, is intersymbol interference. For unknown channels, adaptive equalization is used to mitigate the interference. Different types of equalizers were proposed in the literature such as linear, decision feedback equalizers and maximum likelihood sequence estimation. The transmitter embeds sequences with the data regularly to help the equalizer adapt to the unknown channel parameters.

It is not always appropriate or feasible to send training sequences; in such cases, self adaptive or blind equalizers are used. The past ten years have witnessed an interest in …

Simulation Analysis Of Fddi Network Using Network Ii.5 Software Package, Anastassis A. Lazarides

Theses

In recent years, one of the most exciting advances in media has been the use of fiber optics in LANs. The bandwidth provided by Fiber Optic Technology has drastically increased the number of new applications that can be supported by communication networks. In order to support a variety of services, in 1986, the American National Standard Institute (ANSI) Accredited Standards Committee (ASC) X3, and the ASC X3T9.5 Task Group developed a new standard; the Fiber Distributed Data Interface (FDDI) [1]. This is a high speed (100 Mbps) optical communication network based on a token passing mode of operation. The Medium …

Deterministic And Adaptive Routing Algorithms For Mesh-Connected Computers, Yikui Cai

Theses

The two-dimensional mesh topology has been widely used in many multicomputer systems, such as the AMETEK Series 2010, Illiac IV, MPP, DAP, MasPar MP-1 and Intel Paragon. Its major advantages are its excellent scalability and simplicity. New generation multicomputer uses a switching technique called wormhole routing. The essential idea of wormhole routing is to advance a packet directly from incoming to outgoing channel without sorting it, as soon as enough information has been received in the packet header to select the outgoing channel. It has advantages of low latency and low error rate. The problems addressed by this thesis are …

Performance Analysis Of The "Fiber Distributed Data Interface (Fddi) Network" Using Petri Nets And Spnp Software Package, Savvas Eteoclis Christodoulou

Theses

The main purpose of this thesis is to model a "Fiber Distributed Data Interface" (FDDI) Network using Petri Nets, and to analyze its performance with the help of the SPNP software package. The verification of a communication protocol, by modeling it as a discrete-event system using Petri Nets is a new approach.

The correlation between the throughput rate, voice and data throughput, and the parameters of the system, such as the network load and the network speed are investigated. An overview of the "Fiber Distributed Data Interface" is provided, along with its network protocol and the limitations of its operating …

Characterization Of Lightning Induced Voltages On Overhead Power Lines, Wen-Ta Hsiao

Theses

The transient voltage surge caused by lightning is the major source contributed to the disturbance on power systems. The calculation of induced voltages, which is the propagated voltage surge on overhead power lines due to indirect lightning strokes, has been the subject of theoretical and experimental studies. The objective of this research is to develop a comprehensive numerical method to study the induced voltages on an overhead power line caused by a lightning return stroke with arbitrary shapes, for examples inclined lightning, zigzag lightning, etc.

A finite-length lightning channel of any direction in 3-D space has been modelled and closed-form …

Fast Adaptive Algorithms For Signal Separation, Robert A. Manzo

Theses

LMS and RLS type algorithms are suggested for decorrelation of multi-channel systems outputs. These algorithms act as signal separators when applied to unknown linear combinations of the inputs. The performance of the suggested algorithms is compared with that of the conventional LMS and RLS algorithms that minimize the mean square error. It. is shown that the correlation matrix eigenvalue spread associated with the LMS decorrelator is always smaller than the eigenvalue spread corresponding to the conventional LMS. resulting in faster convergence speed for the decorrelator. A new RLS type decorrelator algorithm is suggested. The RLS decorrelator is shown to be …

Interference Cancellation By Time Adjustable Sampling, Josko Zec

Theses

The problem of improving the frequency response of linear arrays is addressed in this thesis. The improvement is measured in the level of rejection of the undesired sources. A new, simple, and practical method is suggested. It is based on adjusting the sampling time in selected channels. Interference cancellation for finite bandwidth signals is accomplished only at, or close to, the carrier frequency. Wideband cancellation requires additional hardware and computational complexity. Conventional way of the wideband interference cancellation utilizes tapped delay line adaptive filters in each channel.

The Time Adjustable Sampling (TAS) method achieves a part of the tapped delay …

High-Frequency Analog Voltage Converter Design, Ping Xu

Dissertations and Theses

For many high-speed, high-performance circuits, purely differential inputs are needed. This project focuses on building high-speed voltage converters which can transfer a single-ended signal to a purely differential signal, or a differential input signal to a single-ended signal.

Operational transconductance amplifier (OTAs) techniques are widely used in high-speed continuous-time integrated analog signal processing (ASP) circuits because resistors, inductors, integrators, buffers, multipliers and filters can be built by OTAs and capacitors. Taking advantage of OTAs, very-high-speed voltage converters are designed in CMOS technology. These converters can work in a frequency range from DC (0Hz) up to 100MHz and higher, and keep …

The Effects Of Channel Curvature And Protusion Height On Nucleate Boiling And The Critical Heat Flux Of A Simulated Electronic Chip, John E. Leland

Office for Research Publications and Presentations

The quest for higher power yet smaller electronics has given rise to the need for very effective cooling of these electronics. Because one of the foremost problems in electronics cooling is achieving high heat flux cooling within small packages while expending minimal pumping power, one focus of this study was to investigate the effects of channel curvature on the CHF. Experimental data were obtained for flow rates of 1-7 m/s, subcoolings of 5-35"C, and radii of curvature of 25.4 and 50.8 mm. A correlation was obtained for these data which provided an excellent fit.

One condition that has been ignored …

On Issues Of Equalization With The Decorrelation Algorithm : Fast Converging Structures And Finite-Precision, Andrew James Bateman

Theses

To increase the rate of convergence of the blind, adaptive, decision feedback equalizer based on the decorrelation criterion, structures have been proposed which dramatically increase the complexity of the equalizer. The complexity of an algorithm has a direct bearing on the cost of implementing the algorithm in either hardware or software. In this thesis, more computationally efficient structures, based on the fast transversal filter and lattice algorithms, are proposed for the decorrelation algorithm which maintain the high rate of convergence of the more complex algorithms. Furthermore, the performance of the decorrelation algorithm in a finite-precision environment will be studied and …

Advanced Navigation For Planetary Vehicles Applying An Approximate Mapping Technique, Timothy R. Mcjunkin

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This thesis provides a method for compressing the information provided by JPL Mars rover obstacle sensors by creating an approximate map of the terrain around the vehicle. This thesis demonstrates that this method provides adequate information for a human operator to negotiate complex obstacles fields.

By dividing the area around the vehicle into regions and classifying each region as to how dangerous (impassable), the sensor data can be accumulated with minimal overhead. The terrain in each region has a number between zero and one, with zero meaning completely passable and one meaning completely impassable. A continuum of possible values between …

The Design Of An Augmentative Communications Device, Darren Blaser, Scott Sorenson

Undergraduate Honors Capstone Projects

There is an extremely large number of people in the modem world who have difficulty communicating. Among these are approximately 25 million people with cerebral palsy. Cerebral palsy is a disability that is usually caused during, or shortly after birth. Cerebral palsy usually affects a person's motor skills and sense of balance, often rendering them incapable of speaking clearly enough to be understood well. Because this group of people cannot communicate as effectively as other individuals, many uninformed people suppose they do not have as great a need to speak, to say things like, "How are you?", ''I'm Hungry", "Thank …

Electrical And Crystallographic Characterization Of Cdte Grown By The Vapor Transport Method, Jack L. Boone, Gene Cantwell, W. C. Harsch, J. E. Thomas, B. A. Foreman

Electrical and Computer Engineering Faculty Research & Creative Works

Crystallographic and electrical characterization techniques were performed on CdTe single crystal samples grown by the sublimation and physical vapor transport (SPVT) technique. The SPVT growth process described here has resulted in the routine growth of 45-50 mm diameter, 250-300 g boules of single crystal CdTe. As-grown material is p-type in the 5-10 ω cm range. Etch pit densities (EPD) are nominally 7x104 cm-2 along the [111] growth direction and 3x104 cm-2 along the [111] direction. X-ray full width at half maximum (FWHM) on recent samples is 8.6 arc sec compared to 8.5 arc sec theoretical. The as-grown p-type material displays …