Electrical and Electronics Commons^™

Automated Arrhythmia Detection In The Exercise Electrocardiogram, Gregory Ciurpita

Theses

A self-adapting, non-real time method for detecting arrhythmias in single channel Exercise ECG is described. Linear and non-linear digital filtering techniques are used to remove additive noise. A time-varying threshold technique is used to detect R-waves based on amplitude. Feature extraction and matched filter methods are used to classify QRS-waves into existing types, or to create new types. The program works on digitized data from floppy disk and plots all data along with classification results on ReGis graphics terminal or printer. This work will continue so that the system will be capable of processing three-channel ECG in real-time.

An Examination Of The Power Spectral Density Function, James Edward Coleman

Theses

The power spectral density (PSD) function is a characterization of an (ideal) signal or set of signals. It is usually associated with a stationary random process, but it need not be. In fact, to study its properties it is desirable to divorce the power PSD from any extraneous structure that may conceal its properties. Specifically, it is desirable to study Sτ(f) = | Xτ(f)|²/2T and determine how it approximates the power spectrum of a power signal S (f) = τ[R(τ)].

It is shown that it cannot be concluded (contrary to what some of the literature has reported) that …

Digitally Implemented Klapper-Kratt Fm Detector Using The Intel-292o Digital Signal Processor, Chang-Hwan Park

Theses

This thesis describes and analyses a digitally implemented FM detector, which is a new member of the family of FM detectors introduced by Drs. Klapper and Kratt.

The properties of the new detector are low delay, excellent sensitivity, extreme linearity, and compatibility of components with integrated circuit technology.

A working model is implemented by adapting FIR digital s signal processing methods, and is realized using the Single-Chip Digital Signal Processor Intel-2920 which is comprised of micro-processor, scratch-pad data RAMs, program store EPROMs, A/D and D/A conversion circuitry, and I/O circuitry.

The performance of the working model shows very good linearity …

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 …

Pressure Distributions In Microvascular Network, David Moshenberg

Theses

The objective of this study was to find a practical way of estimating the pressure distribution in a network of microvascular vessels. The pressure distribution was evaluated twice, namely before vasodilations or vasoconstrictions and after the network of vessels reached a new steady state with respect to pressure and flow. Along with determining the pressure distribtuion, the simulation also calculated an effective blood viscosity coefficient for the network.

Poiseuille's equation and the axial component of the equation of motion were used to evaluate the steady state pressure and velocity distributions in each vessel. The continuity equation (conservation of mass) was …

Microcomputer Controlled Continuous Activity Monitor For Small Caged Animals, Yogesh Parekh

Theses

The task of this instrumentation system is to measure the activity of rats in a controlled experiment. The system is designed to work in conjunction with the system for studies of metabolic rates in rats. The interface circuits take the picture from a video (vidicon) camera into the computer. Once the picture frame is taken into the high resolution graphics screen memory area, the computer uses this data to detect the activity. The movements of the rat are detected by comparing the number of pixels changed between two consecutive picture frames. The area covered by the rat determines the standing …

16-Channel Signal Analyzer For Electroencephalograms, Junnyih Chiang

Theses

An instrument has been designed to analyze 16 channels of EEG of a squirrel monkey by using several interface boards controlled by an Apple II computer. This instrumentation system is capable of performing these experiments in an automated manner. It stores the data generated on to a floppy disk, with software control and results may be printed out together with related graphs. Because of the limitation of the floppy disk capacity, we had only developed two versions:

(1) To average the EEG signal up to 8 times for all 16 channels, because a lot of memory is needed to save …

Determining Process Latitude With Electrically Measurable Test Structures, Jonathan Littlehale

Theses

Collection of linewidth data is an important part of photoresist characterization. Linewidth data are usually collected by optical measurements or scanning electron microscopy. Both of these techniques are tedious and time-consuming. In this work, electrically measurable test structures are used to collect linewidth data. These structures use a measured sheet resistance, a known length of conducting material, and the measured resistance of the structure to determine the linewidth. The benefits of using these structures include completely automated data collection and the ability to collect statistically significant amounts of data. This allows the use of existing statistical analysis software to analyze …

Constraint On The Optical Constants Of A Film-Substrate System For Operation As An External-Reflection Retarder At A Given Angle Of Incidence, R. M.A. Azzam, Bruce E. Perilloux

Electrical Engineering Faculty Publications

Given a transparent film of refractive index n₁ on an absorbing substrate of complex refractive indexn₂-jk₂, we examine the constraint on n₁, n₂, and k₂ such that the film-substrate system acts as an external-reflection retarder of specified retardance Δ at a specified angle of incidence φ. The constraint, which takes the form ƒ(n₁,n₂,k₂;φ,Δ) = 0, is portrayed graphically by equi-n₁ contours in the n₂,k₂ plane at φ = 45, 70° and for Δ …

Explicit Equations For The Polarizing Angles Of A High-Reflectance Substrate Coated By A Transparent Thin Film, R. M.A. Azzam

Electrical Engineering Faculty Publications

Simple explicit equations are derived that determine the angles of incidence at which the parallel and perpendicular polarization components of light are extinguished on reflection from a transparent film coating a high-reflectance (metallic) substrate. The polarizing angles obtained from our approximate expressions are in excellent agreement with those determined by iterative numerical solution of the exact nonlinear equations that govern such angles. For the approximation to be valid, the intensity reflectance of the film-substrate interface, evaluated at the critical angle of the film-ambient interface, must exceed 0.5.

Antireflecting And Polarizing Transparent Bilayer Coatings On Absorbing Substrates At Oblique Incidence, R. M.A. Azzam, Karim Javily

Electrical Engineering Faculty Publications

The condition of zero reflection of p- and s-polarized light by a transparent bilayer on an absorbing substrate is derived in the form |g_ν(ø,N_i)| ≤ 1, where g_ν is a function of the angle of incidence ø, the refractive indices N_i(i = 0,1,2,3) of the system, and the polarization state ν (= p or s). As an application, the air-Si₃N₄-SiO₂-Si system is considered at two laser wavelengths λ = 6328 and 3250 Å. The thicknesses of the two films of the bilayer and the …

Single-Layer Antireflection Coatings On Absorbing Substrates For The Parallel And Perpendicular Polarizations At Oblique Incidence, R. M.A. Azzam

Electrical Engineering Faculty Publications

Explicit equations are derived that determine the refractive index of a single layer that suppresses the reflection of p- or s-polarized light from the planar interface between a transparent and an absorbing medium at any given angle of incidence. The required layer thickness and the system reflectance for the orthogonal unextinguished polarization also follow explicitly. This generalizes earlier work that was limited to normal incidence or to oblique incidence at dielectric—dielectric interfaces. Specific examples are given of p- and s-antireflection layers on Si and Al substrates at λ = 6328 Å at various angles of incidence.

Extinction Of The P And S Polarizations Of A Wave On Reflection At The Same Angle From A Transparent Film On An Absorbing Substrate: Applications To Parallel-Mirror Crossed Polarizers And A Novel Integrated Polarimeter, R. M.A. Azzam

Electrical Engineering Faculty Publications

The p- and s-polarized components of light can be suppressed on reflection at the same angle of incidence from an absorbing substrate coated by a transparent thin film if the wave is refracted in the film at 45° and the constraint Re[(ε₂ - α)/(l -α)]^1/2 = α + | ε₂ - α| is satisfied, where 2α and ε₂ are the ratios of dielectric constants of the film and substrate, respectively, to that of the ambient. For high-reflectance metal substrates (|ε₂| » 1), α≈ 1, the ratio of film to ambient refractive index …

Design Criteria Of Three-Phase Three-Element Power Directional Relay Under Asymetrical Faults, Fidelis Wagoela Dakogol

Theses

An analytical investigation has been conducted on a three-phase three-machine network power system to determine the optimum Scheme of Connections of the three-phase three-element power directional relay in which the torques of the three independent dynamometer operate on a common axis providing mechanical summation of torques proportional to the power components at the terminals of different phases.

The operation of three-phase, three-element power directional relay is determined by the summation of current and voltage systems having the same phase sequences which is governed by the form of power expression that is proportional to the resulting torque for the various combinations …

Failure Rates And Leakage Current Increase In Tantalum Capacitors Of Different Manufacturers, Joseph G. Grant

Theses

This study has determined the effect of high humidity and temperature on solid tantalum capacitors, from five different sources.

The reasons for using capacitors from five different prestigious sources is to first determine how the parameters change with the different manufacturing techniques used by the different sources. Secondly to rank the different sources according to reliability. The parameters that were measured before and after the "1000 hour" high temperature and humidity test were, capacitance, leakage current, and equivalent series resistance. All the capacitors showed significant increase in leakage current after the test, but there were wide variations in catastrophic failure …

Negative Corona Current Characteristics Of An Electric Wind System, Aviti Kadete

Tanzania Journal of Engineering and Technology (TJET)

The corona current characteristics of an electric wind system are investigated. First a brief summary of the negative point to plate corona mechanism and characteristics are presented. Then empirical equations for corona currents of an electric wind system are derived. Current waveform characteristics are also discussed. The effects of placing parallel rods in between a point-plate electrode gap to the corona currents are highlighted.

Multiple Determination Of The Optical Constants Of Thin-Film Coating Materials, D. P. Arndt, R. M.A. Azzam, J. M. Bennett, J. P. Borgogno, C. K. Carniglia, W. E. Case, J. A. Dobrowolski, U. J. Gibson, T. Tuttle Hart, F. C. Ho, V. A. Hodgkin, W. P. Klapp, H. A. Macleod, E. Pelletier, M. K. Purvis, D. M. Quinn, D. H. Strome, R. Swenson, P. A. Temple, T. F. Thonn

Electrical Engineering Faculty Publications

The seven participating laboratories received films of two different thicknesses of Sc₂O₃ and Rh. All samples of each material were prepared in a single deposition run. Brief descriptions are given of the various methods used for determination of the optical constants of these coating materials. The measurement data are presented, and the results are compared. The mean of the variances of the Sc₂O₃refractive-index determinations in the 0.40–0.75-nm spectral region was 0.03. The corresponding variances for the refractive index and absorption coefficient of Rh were 0.35 and 0.26, respectively.

Reliability Screening Of Transformers, Bharat M. Shah

Theses

The purpose of this project is to study screening of components from the reliability point of view. The component used is electronic transformer. The screen chosen is Electrical Noise generated in the transformer insulation system and the failure mode selected is leakage current in the transformer insulation.

Experiments were conducted to monitor electrical noise generated due to partial ionization of the tiny air gaps in the transformer insulation. The voltage stress, regiured to be applied to the insulation system, for constant 59 units of noise, recorded for the sample of three hundred seventeen transformers.

The voltage readings were analyzed statiscally …

Performance Comparison Of Digital Communication Signaling Schemes, Hiroshi Okusawa

Theses

The intent of the work "Performance Comparison of Digital Communication Signaling Schemes" is to consider various signaling schemes for digital communication and their relative performances.

In order to gain a better perspective of the overall problem of digital communication signaling, the most basic ideas, such as conceptual techniques for the generation and detection of modulated signals, are outlined and provided.

The primary measure of performance -for a digital communication system is the error rate. Emphasis is placed on analyzing the probability of error for various idealized signaling schemes.

A Method For The Identification Of Parameters In Nonlinear Time-Varying Discrete Systems, Somo Coulibaly

Theses

The purpose of this thesis is to present a new technique for estimating the unknown parameters of nonlinear discrete time-varying systems.

The method is based on the model-reference control system where the model and the plant are controlled to exhibit the same output trajectory. The model is chosen to be linear and stationary. To develop the procedure of identification we assume that the structure of the nonlinear system is known and all the measurements are free of noise. A feedback input is adapted to improve the scheme. This scheme can be used to simultaneously identify the parameters when the control …

Modeling And Analysis Of Switching Dc-To-Dc Converters, Suresh Hariharan

Theses

Modeling and analysis of switching dc-to-dc converters has been achieved through several techniques. The state space averaging technique is valid only for disturbances which are less than one-tenth the switching frequency. The discrete technique does not yield accurate results. In this thesis a new approach to the stability analysis of switching regulators has been discussed and the model is far more accurate than the state space averaging technique or the discrete technique. It can be easily programmed into any computer and the results compare well with the experimental results. It also gives a good insight into the design of the …

Optimization Of The Sputtering Technology For Preparation Of Hg1-[Subscript X] Cd[Subscript X] Te Heterojunction Diodes, Kyriacos Kokkinos

Theses

The deposition of (Hg_1-xCd_x)Te onto Si and (Hg_1-yCd_y)Te (x>y) substrates by rf triode sputtering was studied. Ionized mercury vapor, in the 0.6 to 1.2 micron pressure range, was used to bombard pressed-powder targets, consisting of HgTe and CdTe particles, with effective target x value of 0.3, 0.35, and 0.4. The sputtering procedure, parameters, and system were modified to optimize film characteristics. Higher substrate temperature (270°C) was required to obtain metallic gray films with x>0.3. With substrate temperatures less than 270°C and deposition rates 0.5-1.0 micron per hour the films were …

Three-Reflection Halfwave And Quarterwave Retarders Using Dielectric-Coated Metallic Mirrors, T. F. Thonn, R. M.A. Azzam

Electrical Engineering Faculty Publications

A design procedure is described to determine the thicknesses of single-layer coatings of a given dielectric on a given metallic substrate so that a specified net phase retardance (and/or a net relative amplitude attenuation) between the p and s polarizations is achieved after three reflections from a symmetrical arrangement of three mirrors that maintain collinearity of the input and output beams. Examples are presented of halfwave and quarterwave retarders (HWR and QWR) that use a ZnS-Ag film-substrate system at the CO₂-laser wavelength λ = 10.6 µm. The equal net reflectances for the p and s polarizations are computed …

Inverting The Ratio Of The Complex Parallel And Perpendicular Reflection Coefficients Of An Absorbing Substrate Using A Transparent Thin-Film Coating, R. M.A. Azzam

Electrical Engineering Faculty Publications

An absorbing substrate can be coated with a transparent thin film of refractive index N₁ (within a certain range) and thickness d such that the ratio of complex reflection coefficients for the p_and s polarizations of the film-covered substrate ρ = R_p/R_s is the inverse of that of the film-free substrate ρ¯ = R¯_p/R¯_s at an angle of incidence ø. A method to determine the relationship among ø, N₁, and d that inverts ρ (i.e., makes ρ = 1/ρ¯) for a given substrate at a given wavelength is described and is …

Inverting The Ratio Of The Complex Parallel And Perpendicular Reflection Coefficients Of An Absorbing Substrate Using A Transparent Thin-Film Coating, Rasheed M.A. Azzam

Electrical Engineering Faculty Publications

An absorbing substrate can be coated with a transparent thin film of refractive index N₁ (within a certain range) and thickness d such that the ratio of complex reflection coefficients for the p_and s polarizations of the film-covered substrate ρ = R_p/R_s is the inverse of that of the film-free substrate ρ¯ = R¯_p/R¯_s at an angle of incidence ø. A method to determine the relationship among ø, N₁, and d that inverts ρ (i.e., makes ρ = 1/ρ¯) for a given substrate at a given wavelength is described and is …

A 250-Kv Two-Pulse Modulator For The Gas Flow Switch Test Facility, David Michael Barrett

Electrical & Computer Engineering Theses & Dissertations

High-pressure spark gap switches are often used in pulsed power systems because of their high power capabilities. Unfortunately, these switches cannot be operated at high repetition rates because of the time required for the switch to recover. However, the recovery rate of a spark gap may be improved by flowing a gas through the interelectrode region so as to remove the hot gases and debris.

A test facility has been designed and constructed at Old Dominion University to evaluate the performance of gas-flow spark gap switches operating over a wide range of voltages and flow parameters. The facility consists of …

Computer Based Instrumentation System For Measurement Of Cardiac Output In Small Animals, Prasad L. Gavaskar

Theses

The task of the instrumentation system is to measure cardiac output in animals like rats, dogs, etc. A thermal-dilution method is used for this purpose. The temperature change due to injection of saline is picked up by thermo-couple microprobes implanted in the blood-vessel. The signal after conditioning is fed to a data acquisition system controlled by a computer.

With the help of a computer it is thus possible to monitor and control an experiment on several animals. The computer can sample the chambers sequentially. The sampling cycle duration and frequency are programmable. The data is collected and processed to determine …

Automated Instrumentation System To Monitor Behavioral Experiments, Dilip S. Gokhale

Theses

An instrumentation system has been designed to monitor behavioral experiments on monkeys. This instrumentation system is capable of performing these experiments in an automated manner without any human intervention. It is capable of monitoring these experiments concurrently in six boxes. It exhibits several features that make it more versatile than previous instrumentation systems. It is also capable of storing the data generated on to a floppy disk and later transmitting it to the mainframe.

Another feature that makes it more versatile is the flexibility of the system. Presently it is configured to run experiments with variable interval schedules. However with …

Reliability Studies On Solid Tantalum Electrolytic Capacitors, Hamed Nassar

Theses

The primary objective of this thesis is to determine and analyze the failure mechanisms of solid tantalum capacitors, pinpoint the causes, and suggest the precautionary measures that prevent the occurrence of these failures. To achieve this goal, the study went in two directions, theoretical and experimental. The theoretical part-is a comprehensive review of the work -done on tantalum capacitors since 1960 up to date.

The experimental part of the study is a life test (1000 hours) of solid tantalum capacitors under humidity and high temperature. To avoid the misconception that could happen by investigating a particular manufacturer's product, units from …

Magnetohydrodynamic Synchronous Generator With Exhaust Divertor Plasma Of Fusion Reactor, Prabir Kumar Majumdar

Theses

It is the intent of this thesis to develop design concept of a MHD-Synchronous generator for generation of A-C electric power utilizing the exhaust divertor plasma of Tokomak fusion reactor.

The main physical structure of the MHD-Synchronous generating system consists of (1) a linear induction accelerator at the divertor channel to accelerate the plasma velocity sufficient enough to provide rotational effect on the exhaust cylinder by turbine action; (2) a D-C field coil as a source of magnetic field at the entrance of the exhaust chambers; (3) turbine blade on the upper portion of the cylindrical current sheet and (4) …