Engineering Commons^™

Beam Propagation In Periodic Quadratic-Index Waveguides, Lee W. Casperson

Electrical and Computer Engineering Faculty Publications and Presentations

Several techniques are described for studying the propagation of off-axis polynomial Gaussian beams in media having straight axes and periodic z variations of the quadratic refraction and loss coefficients. For some periodic variations, exact analytical solutions of the paraxial equations are possible, and for sufficiently slow variations, WKB solutions can always be obtained. All results are expressed in conventional beam matrix form.

Retrospective Data Filter, Richard J. Prengaman, Robert E. Thurber, Joe Phipps, Ronald I. Greenberg, Wai L. Hom, James F. Jaworski, Guy W. Riffle

Computer Science: Faculty Publications and Other Works

In a target detection communication system, apparatus and method for determining the presence of probable targets based on contacts (which can indicate the presence of a target, noise, chatter, or objects not of interest) detected within a predefined position sector or sectors over a specified number of scans. The position of each detected contact, as a contact of interest, is compared with the positions of contacts detected at previous times or scans. Velocity profiles indicate which previous contacts support the likelihood that the contact of interest represents a target having a velocity within a defined band. The likelihood, which can …

Bonding In Metal Hexacarbonyls, Ramiro Arratia‐Perez, Cary Y. Yang

Electrical and Computer Engineering

A detailed analysis of the valence molecular orbitals (MO) in Cr(CO)₆, Mo(CO)₆, and W(CO)₆is presented. A generalized bonding scheme, which includes participation of metal p electrons in the metal–ligand bond, emerges from our results. The metal p electrons are also responsible for effecting mixings between different sets of carbonyl 5σ and 1π orbitals. In these hexacarbonyls, this ‘‘σ’’+‘‘π’’ metal–ligand bonding contribution is quantitatively as significant as the well known σ donation and π‐back‐donation components. The MO’s obtained with the Dirac scattered‐wave (DSW) method are also used to determine the importance of relativistic effects in …

An Investigation To Improve Linear Predictive Vocoder Pulse/Noise Excitation Models, Elizabeth Annella Martina Effer

Electrical & Computer Engineering Theses & Dissertations

The quality of synthetic speech from Linear Predictive (LP) vocoders is known to be degraded due to the lack of detail in the commonly used pulse/noise excitation model. In this investigation, it was hypothesized that this degradation is due to the lack of precise timing information in the pulses and to the constraint that each short-time segment of excitation be either an impulse train or white noise. Accordingly, more complex excitation models were implemented using precise timing from peaks in the residual and a mixture of pulses and noise. Since the LP residual is known to be the perfect excitation …

Design Of Multivariable Feedback Control Systems Via Spectral Assignment, Mohsen Marefat

Electrical & Computer Engineering Theses & Dissertations

During the past 15 year s significant advances have been made towards developing viable synthesis- techniques for multivariable feedback control systems. The entire aggregate of this theoretical work has been reviewed and consolidated. Diverse notations have been standardized into a single system. A two-step design philosophy for spectral assignment has been developed which first meets stability and time response requirements by assigning eigenvalues and eigenvector s and then provides for attainment of secondary objectives without significant deviation from the initial assignment. Finally, a computer-aided design package has been created to streamline the process of mathematical calculation and to allow users …

Electronic Control Of Electric Motors, Armando Castillo

Graduate Research Papers

The purpose of this study was to investigate the theoretical information on electronic control of electric motors as well as the current state-of-the-art on this topic. It was also intended to carry out some of the experimental circuits discussed, for future instructional situations.

High Performance Switching Circuits For Vlsi, Ali Reza Feizi

Electrical & Computer Engineering Theses & Dissertations

Interconnection topology and device performance are of major concern in the design of LSI/VLSI systems, Pass networks are very suitable in this regard because of low power consumption, high density, and simple interconnection topology. A special type of pass networks called Binary Tree Structured (BTS) pass networks uses almost minimum number of transistors for the design of switching circuits. An algorithmic procedure is developed here for BTS pass networks which is very efficient in terms of both execution time and memory space. Based on these networks, the necessary and sufficient conditions are derived for the design of multiple-output pass networks. …

Randomized Routing On Fat-Trees, Ronald I. Greenberg

Computer Science: Faculty Publications and Other Works

Fat-trees are a class of routing networks for hardware-efficient parallel computation. This paper presents a randomized algorithm for routing messages on a fat-tree. The quality of the algorithm is measured in terms of the load factor of a set of messages to be routed, which is a lower bound on the time required to deliver the messages. We show that if a set of messages has load factor lambda on a fat-tree with n processors, the number of delivery cycles (routing attempts) that the algorithm requires is O(lambda+lgnlglgn) with probability 1-O(1/ …

Further Development Of Preparation And Measurement Techniques For Triode-Sputtered Mercury Cadmium Telluride Thin Films, Tai-On Chan

Theses

The modified MRC 8800 R.F. triode sputtering system was used for mercury vapor sputtering (Hg^1-xCd^x)Te targets onto N-type (111) silicon substrates with a resistivity of 70 to 90 ohm-cm. Deposition rates were in the 2.6 to 3.6 A/sec range, A Hall mobility value, at 87°K, of 2550 Cm²/V•sec with a carrier concentration of 7(10¹⁵) cm^-3 was obtained for 9 μm thick films with an X-value of 0.25. Obtaining good sputtered films reliably was dependent on having targets that would not crack when bombarded with mercury ions. Improvements in the methods used …

Present Reliability Of Liquid Crystal Display Devices, C. N. Suresh

Theses

The purpose of this Thesis is to study the life of liquid crystal display devices as at present available in the market place. To accomplish this, accelerated tempera-ture conditions at 77°C and 85°C were used.

During the last few years, there has grown a tremendous interest in wide range temperature operating and fast LCDs. It is therefore important to understand how LCDs behave under these conditions.

The reliability of a liquid crystal display is usually measured in terms of a quantative degradation in electrical performance and a degradation in visual appearance. The degradation in visual appear6knce may manifest itself as …

Robot Manipulators And Control, Theresa Wu

Theses

This paper on Robot Manipulators brings together theories from three fields : computer graphics, kinematic equations and microprocessor based control.

There are four chapters in this paper, chapter one is the conceptual development on homogeneous transformations, express the position and orientation of the transposition of an object in Cartisian coordinates. Chapter two develops the method of obtaining the Cartisian coordinate position and orientation of the end effector for a manipulator, give the joint coordinate as input and use the homogeneous transformation to express the position and orientation. Chapter 3 is a very difficult one; it solves the parameters for the …

Reliability Evaluation Of Liquid Crystal Displays Under Accelerated Test Conditions, Ravi Sankar Kalyandrug

Theses

This study has determined the effects of high temperature and humidity on the reliability of liquid crystal dis-plays.

Reliability life testing was done on variety of LCD samples under different operating conditions. All the besting was done under accelerated conditions, including high temperature of 85°C and relative humidity of 70%. A number of failure modes were identified in the long series'of tests.

Among many failure modes such as peeling of seal, degradation of polarizers etc., the most important is the degradation of alignment of liquid crystal molecules. Leakage current measurements were made on all the LCD samples before and after …

Frequency Characterization Of A Thin Linear Antenna Using Diakoptic Theory, Howard Harold Smith

Theses

A frequency dependent analytical expression for the input impedance of a thin wire antenna is obtained using diakoptic theory. In diakoptic theory the linear antenna is seperated into electrically short segments where each segment is treated as a two-port network. This approach eliminates the need for an integral equation formulation. An impedance matrix is found which characterizes coupling between all segments. By expanding the free space Green's function in a power series in wavenumber k each entry in the resultant impedance matrix is obtained as a function of frequency. Enforcement of the continuity of currents and equality of scalar potentials …

Identification Of Linear System With Feedback Input, Jyh Yang

Theses

A new procedure with feedback input is presented for identification of continuous-time systems. Using Lyapunov's direct method to prove it asymptotic stability. For the procedure to be applicable, it's assumed that all the state variables of the plant are accessible and that there is no measurement noise so the model reference scheme can be used to identify the parameters of the plant.

The procedure results in the convergence of every parameter of a model to the corresponding one of the system as the time approaching to infinite i.e. t→∞. Digital computer simulations are provided to demonstrate the feasibility of the …

An Application Of A Heuristic Search Algorithm In Biomedical Images On The Magiscan Ii Image Analysis System, Patricia S. Humes

Masters Theses

The goal of this project was to successfully apply a heuristic search algorithm in the image analysis environment of the Magiscan II Image Analysis System. The purpose of this particular application was to enable the specific segmentation of a white blood cell image by outlining the boundary of the cell nucleus, a process not currently possible with the existing system software.

The method used involved tracing boundaries by choosing points based on a calculated cost factor. The cost factor has several input parameters that will enable it to be applied in a wide variety of applications. Several different cells' nuclei …

A Theoretical Basis For Practical Amplifier Design Using Cascaded Operational Amplifiers, David J. Comer

Faculty Publications

A procedure is developed for the design of amplifiers to meet specified gain and bandwidth figures. The number of required operational amplifier stages is minimised. A figure of merit is introduced to determine if a particular operational amplifier can be used to satisfy a given set of specifications.

An Inventory Of Maine's Telecommunications System, Maine State Planning Office

Maine Collection

An Inventory of Maine's Telecommunications System

Prepared for the Maine State Planning Office by Joseph M. Chaisson and Valerie Lamont of the Telecommunications Research Program at Westbrook College in Portland, Maine. July, 1985.

"The Primary purpose of this report is to provide information for Governor Brennan's Task Force on Telecommunications. The inventory also can be widely used as a reference by persons and organizations concerned with providing telecommunications services in Maine."

Contents: Introduction / Local Telephone Service / Mobile Telephone Service / Digital Termination Service / Cable Television / Paging Systems / Intra-State (Intra-LATA) Public Services / Intra-State (Intra-LATA) Private …

Minimum Probability Of Electron-Hole Pair Generation By Blackbody Radiation, Cheng-Hsiao Wu

Electrical and Computer Engineering Faculty Research & Creative Works

Using the small-perturbation assumption that all the useful work is in the form of electron-hole pairs when photons from a blackbody radiation source are incident on a quantum device, we derive the minimum probability of generation of one or more pairs of electron holes. Using the Planck radiation formula for the solar spectrum at 6000 K and for the quantum device at 300 K, this minimum probability is about 0.8 at low photon frequency and approaches the limiting value of 0.95 at high frequency. Its relation to maximum efficiency of a quantum device is discussed.

The Unification And Decomposition Of Processing Structures Using Lattice Theoretic Methods, David L. Livingston

Electrical & Computer Engineering Theses & Dissertations

The purpose of this dissertation is to demonstrate that lattice theoretic methods can be used to decompose and unify computational structures over a variety of processing systems. The unification arguments provide a better understanding of the intricacies of the development of processing system decomposition. Since abstract algebraic techniques are used, the decomposition process is systematized which makes it conducive to the use of computers as tools for decomposition. A general algorithm using the lattice theoretic method is developed to examine the structures and therefore decomposition properties of integer and polynomial rings. Two fundamental representations, the Sino-correspondence and the weighted radix …

Color Display Of Vowel Spectra As A Training Aid For The Deaf, Amir Jalali Jagharghi

Electrical & Computer Engineering Theses & Dissertations

The objective of this research was to develop a transformation for mapping speech parameters to color parameter. This transformation is done in real-time, and the resulting color parameter are continuously displayed on a color monitor. This visual speech display is to be used as a speech articulation training aid for the deaf. The conversion of speech acoustic signals into speech parameter was accomplished using special -purpose electronics. The real-time conversion of speech parameter to display parameter was controlled by an 8086/8088 microprocessor operating in an S-100 bus structure. The coefficients of the Karhunen-Loeve series expansion of speech power spectra were …

High Discharge Rate Characteristics Of Nickel-Cadmium Batteries For Pulse Load Filtering, Gregory M. Gearing, Michael B. Cimino, David H. Fritts, John F. Leonard, Anthony J. Terzuoli Jr.

Faculty Publications

Several tests of specially fabricated nickel-cadmium batteries having circular disk type electrodes were considered. These batteries were evaluated as filter elements between a constant current power supply and a five hertz pulsed load demanding approximately twice the power supply current during the load on portion of the cycle. Short tests lasting 10,000 cycles were conducted at up to a 21 C rate and an equivalent energy density of over 40 Joules per pound. In addition, two batteries were subjected to 10⁷ charge/discharge cycles, one at a 6.5 C rate and the other at a 13 C rate. Assuming an …

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 Mean Return Time To A State For A Markov Chain Representing In Telephone Conversations, M Luhanga

Tanzania Journal of Engineering and Technology (TJET)

The mean return time to a state for a Markov chain representing N off-hook telephone conversations can be obtained by using ergodic flow rates [1] or renewal theory [2]. In this paper it is shown that the same result may be obtained by using no more knowledge of stochastic processes than the solution of time-homogeneous Chapman-Kolmogorov equations.

An Electro Hydrodynamic Study Of The Negative Corona Electric Wind, Henry Thadei Kadete

Tanzania Journal of Engineering and Technology (TJET)

The velocity of corona generated electric wind is measured. From the velocity profile mass movement and electrokinetic conversion efficiencies are deduced. High speed schlieren photographs illustrate the form of the velocity distribution function as well as its high degree of turbulence.

Simple Graphic Routines Ease Drawing Of Artwork For The Fabrication Of Microstrip Lines, H Mgombelo

Tanzania Journal of Engineering and Technology (TJET)

A method which uses simple graphic routines available to general computer users for drawing diagrams intended to be reproduced on printed circuit boards (PCB's) is presented. Experimental verifications for the created microchip lines are reported.

Identification Of Defect Centers In Hg1-XCdXTe Using Their Energy Ievel Composition Dependence, Charles W. Myles, P. F. Williams, R. A. Chapman, E. G. Bylander

P. F. (Paul Frazer) Williams Publications

We have extended the Kobayashi, Sankey, and Dow [Phys. Rev. B 25,6367 (1982)] theory of deep levels in Hg_1-xCd_xTe to include (vacancy, impurity) nearest-neighbor pairs. In qualitative agreement with the results obtained by these workers for isolated point defects, we find that the composition dependences (dE /dx) of the defect energy levels associated with such complexes depend on the site occupied by the impurity atom. Furthermore, we find that the composition dependences of some of the defect levels produced by such a complex are very different than the dE /dx of levels associated with …

Quantification Of Indian Rights: Problems Of Proof, Harry R. Sachse

The Federal Impact on State Water Rights (Summer Conference, June 11-13)

32 pages.

Spontaneous Coherent Pulsations In Ring-Laser Oscillators: Stability Criteria, Lee W. Casperson

Electrical and Computer Engineering Faculty Publications and Presentations

The stability criteria implied by a simplified semiclassical laser model are considered in detail. It is found that two types of criteria must be distinguished. The first concerns the smallest pump rate for which infinitesimal perturbations of the steady-state solution will increase with time, and the second concerns the smallest pump rate for which large amplitude modulations will not damp away.

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 …

A Pitch Based Processor For The Analysis Of Steady State Laryngeal Modes, Tzyy-Jenq Lou

Theses

A data acquisition and analysis stem for use in the study of laryngeal dynamics has been built and tested. The special feature of the system is the computer controlled digitizing rate and coordinated subject pitch prompting. Tokens of steady state laryngeal vibration are obtained from an electroglottograph when the subject intones a series of computer prompted pitchs in a musically scalar sequence. The digital samples of this data are captured by the system at a basic rate of 200 samples per laryngeal cycle. This procedure enables the system to perform a modal analysis of laryngeal function, not unlike the analysis …