Engineering Commons^™

Dirac's Equation In Semiclassical Physics, Lee W. Casperson

Electrical and Computer Engineering Faculty Publications and Presentations

Dirac's equation provides the most rigorous basis known for many calculations in relativistic quantum mechanics. A set of dynamical equations having greater intuitive content can be derived from Dirac's equation without any approximations. These secondary equations govern the properties of a Dirac particle as functions of time and space and are similar to the corresponding equations governing a classical charged fluid. Several new density functions are implied by these equations and are appropriate for incorporation into the various semiclassical models of physics.

Theory, Design And Applications Of Linear Transforms For Information Transmission, Adil Benyassine

Dissertations

The aim of this dissertation is to study the common features of block transforms, subband filter banks, and wavelets, and demonstrate how discrete uncertainty can be applied to evaluate these different decomposition techniques. In particular, we derive an uncertainty bound for discrete-time functions. It is shown that this bound is the same as that for continuous-time functions, if the discrete-time functions have a certain degree of regularity.

This dissertation also deals with spectral modeling in filter banks. It is shown, both theoretically and experimentally, that subspectral modeling is superior to full spectrum modeling if performed before the rate change. The …

Design And Micro-Fabrication Of Tantalum Silicide Cantilever Beam Threshold Accelerometer, Chang Joo Kim

Dissertations

Microfabricated threshold accelerometers were successfully designed and fabricated following a careful analysis of the electrical, mechanical, and fabrication issues inherent to micron-sized accelerometers. A uniform cantilever beam was chosen because of the simplicity of design and fabrication. New models for the electrostatic force exerted on the cantilever beam were developed and calculations were made that accurately predicted the electrical characteristics of the accelerometer. The calculations also provided design guidelines for optimizing the accelerometer dimensions. Computer simulation demonstrated that the error of the electrostatic force, calculated using the most accurate model, was within 2% of the actual force which was obtained …

Electrical Characteristics Of Novel Heterojunction Diodes Of Thin Relaxation Semiconductors/P-Si/, Hyung Joo Lee

Dissertations

The relaxation semiconductor is defined as one in which the dielectric relaxation time (τd;resistivity times permittivity) is greater than lifetime (τo). Non-hydrogenated amorphous Silicon Carbide (SiC) and KrF excimer laser induced disordered Si were used for the relaxation semiconductors. Both semiconductors have high resistivity, wide energy gap, and numerous defects. A novel diode, consisting of those semiconductors on p-type crystalline Silicon (c-Si), was fabricated. In the diode structure, an injecting contact was made on the relaxation material and a Schottky barrier contact was made on the c-Si.

Electrical characteristics of both diodes were found to have interesting …

On Adaptive Code Division Multiple Access Detectors, Wenping Chen

Dissertations

Several variations of adaptive CDMA synchronous receiver schemes which can automatically adjust to the system parameters, are studied in this dissertation. Unlike their non-adaptive counterparts, these adaptive detectors require no knowledge of the received signals' energies and have similar or better performance.

Minimum energy and decorrelating criterion are used to update the weights. Since weights are updated according to the changes of the detector's outputs, hence no training sequence is required. The convergences of some of the aforementioned adaptive detectors are also disscussed.

The detectors proposed in this dissertation are near-far resistant,thus rendering the high-precision power control unnecessary. Among them, …

An Adaptive Asynchronous Cdma Receiver And Its Convergence Analysis, Lizhi Zhong

Theses

An adaptive CDMA receiver scheme assuming perfect synchronization has been generalized in this thesis to the asynchronous channel, a much more practical assumption of the real system. Similar formulas are derived and as its synchronous version, it is still near-far resistant and requires no knowldge [sic] of received signal amplitudes and training sequences. Thus, sophisticated high-precision power control and user power estimation are not necessary and the receiver is particularly useful in mobile communications since it can adjust itself adaptively to changes in the power of the users. Tile convergence and transient behavior of the receiver are also investigated and …

Performance Evaluation And Sequence Control Of An Automatedmanufacturing System, Vijaykumar D. Desai

Theses

In an automated sequential manufacturing system Programmable Logic Controllers (PLC) are widely used. As the control specification varies, the control software needs to be rewritten to accommodate the new specification. Since PLC has high flexibility, one can update the current system while it is running thereby making easier implementation. In order to design flexible, reusable and maintainable control software, a good modeling tool is required. Petri nets are such a tool. Which facilitates analysis of behavioral properties, performance evaluation, and systematic construction of discrete event simulators and controllers. In this thesis a system with one robot and five sequential work …

Single-Axis Agonistic Motion Control System With Electro-Magnetic Actuators, Alexander Rokhvarg

Theses

A novel single-axis motion control system using solenoid electromagnet actuators is built and successfully controlled using a non-linear real-time control algorithm. Procedures for defining and modeling the electromagnetic actuator are established and implemented. Discrete-time nonlinear control law with global asymptotic stability and zero steady-state error is designed and numerically optimized. Stable operation with small-signal 0dB crossover frequency of 370 Rad/sec and positioning RMS steady-state error of better than 4 micron is achieved. Time domain parameters are verified on a working prototype. A step reference response positioning a 0.35 Kg mass payload over 1 cm travel in under 30 milliseconds is …

Heart Rate Variability Studies On Ambulatory Subjects Using Ekg Derived Respiration, Xiaorui Tang

Theses

Power spectral analysis of heart rate variability (HRV) provides a powerful non-invasive too] for exploring the balance between sympathetic and parasympathetic components of the autonomic nervous system. In the spectrum of HRV, there are three distinct peaks. The high frequency (HF) band (0.15 to 0.4 Hz) is correlated with parasympathetic activity and this is the band of interest 'in the study.

Two OTOUPS Of SL113jeCtS were considered in this work, stroke survivors and subjects performing an oral presentation in front of an audience. Data were collected with a Holter monitor to allow for ambulatory recording. Respiration was derived from the …

Scheduling Of Flexible Manufacturing Systems With Automated Guided Vehicles Using Petri Net Models, Hua-Sheng Chiu

Theses

In this thesis, Petri net models for Flexible Manufacturing Systems (EMS) are constructed. A firing sequence of the Petri net from the initial marking to the final marking can be seen as a schedule of the modeled FMS. By using the branch-and-bound algorithm, an optimal schedule of the FMS can be obtained.

Automated Guided Vehicle Systems (AGVS) are increasingly used for material handling in factories and warehouses. An AGVS can reduce labor costs and is ready to be integrated into an automated factory. This thesis presents two AGVS models (shared and duty) which integrate the control of AGVS with the …

A Three Stage Large Dynamic Range Automatic Transimpedance Control Amplifier, Karim Joseph Sikias

Theses

Long haul fiber optic communication systems require extremely sensitive, low noise amplification of the weak photo diode currents generated by the received light power. Two types of amplifiers have been used for this application: a high input impedance integrating amplifier/differentiating equalizer combination or a transimpedance amplifier. Optical receivers designed with integrating amplifiers exhibit severe low frequency drift and overload problems and are not generally used in wide dynamic range receiver design. This thesis will describe an extremely wide dynamic range transimpedance amplifier incorporating unique methods to maintain stability, wide bandwidth low pulse width distortion during overload conditions.

Soft Decision Adaptive Multiuser Cdma Detector For Asynchronous Awgn Channels, Frank Viehofer

Theses

A multiuser detector in an asynchronous, additive white Gaussian noise, codedivision multipleaccess (CDMA) channel is proposed and analyzed. It employs a combination of a decorrelator and a nonlinear multiuser interference canceler that utilizes soft tentative decisions. The weights of the canceler are adaptively adjusted, in a manner that renders the knowledge of received signal energies and the use of training sequences unnecessary. The steady state error performance of the detector is obtained and found to be superior to the performance of the same detector that utilizes hard tentative decisions.

Implementation Of Time-Frequency Distribution Software And Its Use To Study Biological Signals, Mansour Adib

Theses

The joint time-frequency signal representation has received considerable attention as a powerful tool for analyzing biological signals. It combine time-domain and frequency-domain analyses to yield a potentially more revealing picture of the temporal localization of a signal's spectral components. In this research we have developed algorithm which implement time-frequency signal analysis techniques on a computer system. Its primary function is to produce a variety of time-frequency representations and plots from the time series. Numerous generated signals were used to justify our computer algorithm.

Variety of time-frequency distribution were utilized to expand the concept of spectral analysis of heart rate variability, …

The Mobile Satellite Service (Mss) Systems For Global Personal Communications, Kiho Lee

Theses

A worldwide interest has arisen on personal communications via satellite systems. The recently proposed mobile satellite service(MSS) systems are categorized four areas: geostationary earth orbit(GEO) systems, medium earth orbit(MEO) systems, low earth orbit(LEO) systems, and highly elliptical orbit(HEO) systems. Most of the systems in each category are introduced and explained including some technical details. The communication links and orbital constellations of some systems are analyzed and compared with different categories, and with different systems. Some economical aspects of the systems are mentioned. The regulatory issues about frequency spectrum allocation, and the current technical trends in these systems are summarized.

Am/Fm Digital Audio Broadcasting In-Band On-Channel Transmission, Michael Meyer

Theses

This thesis examines the in-band on-channel transmission of digital audio data for application in Digital Audio Broadcasting (DAB). The premise is to use the existing FM channels for transmission of DAB. For the FM channel used for analog audio transmission, two different scenarios are suggested and investigated.

In the first scenario, to enable overlay of the new DAB and current FM transmissions, the digital data is modulated by a direct sequence spread spectrum signal to bring the average transmitted power below that of the FM signal using the same channel. The FM signal interferes with the digital transmission and it …

Simulation Of Activity Rhythms In The Hamster, Paul Qassis

Theses

In this research, an effort was made to better understand light-dark cycles which influence the physiological and psychological rhythms, circadian rhythms and their behavior. The research concentrated on mathematically modeling circadian rhythms (specifically hamsters' circadian activity rhythms) and establishing a physical correlation and creating a meaningful relationship between the mathematical model's parameters and the real biological oscillators which are responsible for these rhythms. The internal nature of the circadian rhythms is unclear. There is insufficient information and empirical data that describe them. Indirect means have to be employed for the description and exploration of such rhythms. Extensive real data analysis …

Design Of A Lapd Interface Using The T7130 Multichannel Lapd Controller And The T715a Synchronous Protocol Data Formatter, Hopeton Saint John Walker

Theses

As the ISDN telecommunications standard gains acceptance, there is an ever increasing need for intelligent interfaces to implement the L2 protocol known as LAPD. The T7130 MLC, the T7115A SPYDER-T and the MC68020 microprocessor were used to design a LAPD Interface that conforms to the LAPD protocol as specified by CCITT.

The LAPD Interface utilizes a Shared Memory Array which is attached to the Data Link Processors in a single bus configuration. The SMA Arbitration Control allows access to the SMA on a prioritized basis and was implemented as a state machine using PAL's. L2 drivers and L3 management software …

Analysis Of Intermodulation Distortion For Mesfet Small-Signal Amplifiers, Imad Saleh Ahmad

Dissertations and Theses

Using the nonlinear Volterra series representation, analytical expressions for the third-order intermodulation distortion power and intercept point for a MESFET small-signal amplifier are derived when its equivalent circuit is bilateral and includes the gate-to-drain capacitance (C_gd) explicitly as a nonlinear element. Previously developed analytical expressions treated C_gd as a linear element or incorporated it as part of gate-to-source and drainto- source capacitances (C_gs and C_ds). These new analytical expressions are then compared with experimental data and good agreement is obtained. The analytical expressions are also used to study the variation of intermodulation distortion with …

Losslees Compression Of Rgb Color Images, Nasir D. Memon, Khalid Sayood

Department of Electrical and Computer Engineering: Faculty Publications

Although much work has been done toward developing lossless algorithms for compressing image data, most techniques reported have been for two-tone or gray-scale images. It is generally accepted that a color image can be easily encoded by using a gray-scale compression technique on each of the three accounts the substantial correlations that are present between color planes. Although several lossy compression schemes that exploit such correlations have been reported in the literature, we are not aware of any such techniques for lossless compression. Because of the difference in goals, the best way of exploiting redundancies for lossy and lossless compression …

Campus Telecommunications Systems: Managing Change, Association Of College And University Telecommunications Administrators

ACUTA: Other Publications

The purpose of this book is to provide a broadbased understanding of the rapidly changing environment of campus telecommunications. The anticipated audience for this material is the non-technical university administrator who may not have direct responsibility for telecommunications, but has a need to understand the general environment in which his telecommunications manager functions and the basic concepts of the technology. Five topic areas were selected that best cover the preponderance of issues. No attempt has been made to associate or closely coordinate materials from one chapter's subject to that of any other. Each chapter generally stands alone. In total, however, …

Multilevel Block Coded 8-Psk Modulations Using Unequal Error Protection Codes For The Rayleigh Fading Channel, Robert H. Morelos-Zaragoza, Tadeo Kamasi, Shu Lin

Faculty Publications

This paper introduces new block coded 8-PSK modulations with unequal error protection (UEP) capabilities for Rayleigh fading channels. The design of efficient block coded modulations (BCM) over 8-PSK signal sets, for the specific purpose of UEP, over Rayleigh fading channels is considered. UEP is desirable in communications systems where part of the source information is more important, or error sensitive, such as the transmission of coded speech and data broadcasting. The proposed block modulation codes are based on the multilevel construction of Imai and Hirakawa (1977). It is shown that the use of binary linear UEP (LUEP) codes as component …

Characterization Of Cadmium Sulfide Films Deposited By Chemical Bath Method, Quazi Galib Samdami, Hameed A. Naseem, W. D. Brown

Journal of the Arkansas Academy of Science

Thin filmcadmium sulfide is a leading candidate in the fabrication of large area solar cells. The chemical bath deposition method is one of the least expensive sources for the fabrication of device quality cadmium sulfide thin films.Inthe present work, the deposition of CdS films on glass substrate from an aqueous solution containing cadmium acetate, ammonia, ammonium acetate, and thiourea are investigated. The structural properties of CdS films are characterized. Good quality thin films within 0.1 - o.5 |im thickness were obtained in30 minute deposition time, and at 70*-90*C. The films show preferential orientations. The optical transmittance of the films are …

Qpsk Block-Modulation Codes For Unequal Error Protection, Robert H. Morelos-Zaragoza, Shu Lin

Faculty Publications

Unequal error protection (UEP) codes find applications in broadcast channels, as well as in other digital communication systems, where messages have different degrees of importance. Binary linear UEP (LUEP) codes combined with a Gray mapped QPSK signal set are used to obtain new efficient QPSK block-modulation codes for unequal error protection. Several examples of QPSK modulation codes that have the same minimum squared Euclidean distance as the best QPSK modulation codes, of the same rate and length, are given. In the new constructions of QPSK block-modulation codes, even-length binary LUEP codes are used. Good even-length binary LUEP codes are obtained …

An Optical Backplane Demonstrator System Based On Fet-Seed Smart Pixel Arrays And Diffractive Lenslet Arrays, D. V. Plant, B. Robertson, Harvard Scott Hinton, W. M. Robertson, G. C. Boisset, N. H. Kim, Y. S. Liu, M. R. Otazo, D. R. Rolston, A. Z. Shang

Electrical and Computer Engineering Faculty Publications

We have demonstrated a representative portion of an optical backplane using FET-SEED smart pixels and free-space optics to interconnect printed circuit boards (PCB's) in a two board, unidirectional link configuration. 4×4 arrays of FET-SEED transceivers were designed, fabricated, and packaged all the PCB level, The optical interconnection was constructed using diffractive microoptics, and custom optomechanics. The system was operated in two modes, one showing high data throughput, 100 MBit/sec, and the other demonstrating large connection densities, 2222 channel/cm2.

Design And Construction Of An Active Alignment Demonstrator For A Free-Space Optical Interconnect, G. C. Boisset, B. Robertson, Harvard Scott Hinton

Electrical and Computer Engineering Faculty Publications

An x-y active alignment system based on Risley beam steerers is described. The demonstrator features a quadrant detector which detects the misalignment error between the center of a spot of light and the center of the quadrant detector. This misalignment error is then used by a new algorithm to calculate the rotational displacement required for the two Risley beam steerers to steer the spot of light to the center of the quadrant detector. The experimental results indicate that any spot misaligned by up to 160 μm on the quadrant detector will be systematically centered by the demonstrator system.

Finite Impulse Response Utilizing The Principles Of Superposition, Scott Edward Carter

Retrospective Theses and Dissertations

Window functions have been greatly utilized in the synthesis of finite impulse response (FIR) filters implemented using surface acoustic wave (SAW) devices. The critical parameter in any FIR design in the impulse response length, which must be optimized for the given design specifications in order to reduce the size of each device. To this end, many design algorithms have been introduced such as Remez exchange, linear programming, and least mean squares. A new algorithm has been derived which is efficient and accurate for the design of arbitrary filter specifications requiring less computations than the current algorithms. The FIR design is …

Enhanced 911 Service In A Private Branch Exchange Using Uswest Ps/Ali Service

ACUTA: Other Publications

In This Issue

Author

Introduction

EP11 Operation Overview

US West Communications E911 Private Switch/Automatic Location

Identification Feature

Implementation of E911 with PS/ALI At Colorado State University

Overview

Planning ALI Database Input

SL- 100 PBX Database and Trunking

Pre-Testing

Other Issues and Difficulties

Cost

Conclusion

Addendum A

Addendum B

Polishing Of Cvd-Diamond Substrates Using Reactive Ion Etching, Gopi M.R. Sirineni, Hameed A. Naseem, W. D. Brown, A. P. Malshe

Journal of the Arkansas Academy of Science

Multichip modules (MCM)have proved to be a viable packaging technology for achieving small size and high performance. By their nature, MCMs typically integrate multiple bare die into a module that can be the plastic or ceramic package. As a result, the MCMrequires an efficient mechanism for removing excess heat. Diamond with its excellent thermal conductivity, is the ideal choice as a substrate material for these applications. Chemical vapor deposited (CVD) diamond substrates makes possible the practical realization of a novel diamond based 3-D MCM. However, the diamond films grown by CVD technique are polycrystalline and have non-uniform filmroughness and randomly …

Electrical Power Dispatch To Motors Using Digital Modulating Techniques, David Michael Canny

Theses

The trend towards digital and microprocessor based control of power electronic converters has increased the level of research into digital modulating techniques. This thesis examines the inherent digital nature of Binary Rate Modulation with particular attention concentrated on its suitability for dispatching power to three-phase loads. The circuit topology of a three-level inverter is also examined and its performance aspects are compared with those of the more conventional two-level inverter.

Integral cycle Binary Rate Modulation is applied to an ac voltage controller and this method of power dispatch, which displays an optimal ac cycle positioning property, is compared with Pulse …

A Two-Dimensional Image Model Based On Occlusion And Maximum Entropy, John A. Stuller

Electrical and Computer Engineering Faculty Research & Creative Works

This Paper Provides New Insights into the Formation of Two-Dimensional Image Autocorrelation Functions. We Model an Image as a Maximum-Entropy Composition of Individual Occluding Object Images that Have Random Positions, Shapes and Intensities. We Derive the Autocorrelation Function of This Image Model, Give an Example, and Comment on the Reasonableness of the Frequently-Made Assumptions of Autocovariance Separability and Isotropy.