Electrical and Electronics Commons^™

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 …

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) …

Computer Simulation Of Electro-Static Field Potential To Study The Effect Of An Animal On The Electric Field Between Two Charged Plates, Shekhar Gajanan Potdar

Theses

This thesis deals with plotting of equipotential lines in an electrostatic field created by two parallel charged plates. Between the plates lies a dielectric cage inside which an animal (rat) is kept, on whom anatomical tests are to be carried out after exposing it to a certain electric field intensity for a given period. Values of the actual field to which the animal is exposed can hardly be obtained experimentally. Computer simulation in this case becomes a powerful tool. Starting with the uniform field ideally created between two parallel plates, it is then neccesary to find the effect of the …

An Investigation Of Characteristics Of Blood Velocity In A Simulated Circulation System, Yung-Gang Wu

Theses

The major objective of this thesis is to find the relationship between the blood velocity and the stenosis of the vessel. Tests were performed with different degrees of stenosis at varied logitudinal positions from the testing probe in the vessel of a Z-80 microprocessor controlled artificial circulation system.

Three methods were used to detect the velocity in the vessel: continuous wave Doppler, Pulse Doppler, and a hot-film device. The first method can get the average velocity, while the latter two have the capability to find a velocity profile, and all are important indicators to the arterial occlusion phenomenon.

An analysis …

Instrumentation To Measure Ion Flux Through Biological Tissues, John Edward Obenauer

Theses

An instrument has been designed and constructed which measures the ion flux through biological tissues utilizing the short circuit current technique. The system operates in three major modes: 1) obtains the fluid resistance and potential offsets of a chamber without the tissue mounted; 2) Voltage clamp mode - clamps the potential of the tissue to a predetermined value; 3) Current clamp mode - clamps the current through the tissue to a predetermined value. The system automatically compensates for fluid resistance and potential offsets in both voltage and current clamp modes. The instrument starts clamping a particular chamber immediately after mounting …

The Detection Of Partial Discharges In Transformer Oil, Gerald J. Fitzpatrick

Theses

The level, meaning the number and the intensity Of partial discharges that occur in transformer oil per time period of applied pulse when a high voltage is applied can be used as a measure of the quality and remaining life of the oil. The level of partial discharges at a given applied voltage can be correlated with the degree of contamination of the oil by impurities such as water and conductive particles and can be used as an indicator of the proximity of the oil to breakdown. There are several approaches to the detection of partial discharges, e.g., acoustic measurements, …

Microcomputer Controlled Instrumentation System For Studies Of Metabolic Changes In Rats, Murat Dertlioglu

Theses

The system measures the respiratory exchange in rats in a controlled experiment. An interface unit provides data, received from several measurement instruments such as gas analyzers, an electronic flowmeters, electronic thermometer and an electronic hygrometer, to the computer. The data is gathered from different chambers in a multiplexed mode.

The computer samples the chambers sequentially and prints out the results and stores them on the disk. The sampling duration of each chamber and the number of the rats to be tested can be programmed. The system can perform experiments with twelve animals, in the following arrangments, either one group of …

Performance Modeling And Simulation Of Multiple Microcomputer Systems, Moorthy Narayana Hariharan

Theses

Multiple processor systems are the logical choice for applications demanding high computing power, throughput and reliability. Moderately coupled Multiple Microprocessor systems can be applied to a variety of applications demanding high performance. The structure of Multiple Microprocessor systems is examined. Various interconnection structures are analysed for performance comparisons.

Queueing theory is a powerful tool in modeling and analysing Computer systems. Queueing models are developed for popular Multiple processor interconnection topolog es like the Shared memory, Shared bus, Star and Loop configurations.

The usefulness of Digital computer Simulation techniques in estimating the performance of Multiple processor systems is demonstrated through a …

Decision Rules Applied To Spread Spectrum Signal Detection, Richard Jae Kim

Theses

Decision rules for detection of spread spectrum signals were investigated. For each decision rule, error and erasure probabilities were analyzed. The obtained data was used to plot PE vs Pe for constant signal-to-noise ratio (SNR). With the use of the probability of a word error curves the optimum threshold setting was found for a given SNR.

FSK (orthogonal signalling) and PSK (antipodal signalling) were considered for modulating the chips. When the PE vs Pe plots for FSK and PSK were compared, PSK performed better than FSK by a ratio of 6 dB.

Finally, analog and digital correlation of the received …

Decentralized Optimal Control With Application To Dynamic Routing In Computer Communication Networks, Ning Wang

Dissertations

This research considers the dynamic routing problem of computer communication networks in the framework of decentralized control theory. The routing dynamics are modeled in terms of a state equation with multiple controllers. Routing, or control of message flow, is formulated as an optimal control problem with multiple decision makers. Each decision maker may have access to different set of information and work cooperatively to optimize a common system performance index.

Necessary and sufficient conditions for optimality are derived for a system with a deterministic and a stochastic traffic patterns under a linear information structure and a quadratic performance index. The …

Spectral Analysis Of Brainstem Auditory Evoked Responses, Amir Hossein Massumkhani

Theses

In this study, the power spectrum density of the brainstem auditory evoked responses is estimated by the method of periodogram. Several techniques for reducing the leakage due to the finite length of data, smoothing the spectrum and reducing the ambiguity in the spectrum due to the resolution are studied. It is shown that a Hamming window reduces the leakage considerably and zero extention of the data to 512 points produces sufficient spectrum bandwidth. Three major peaks are observed at 100, 500, and 1000 Hz which are stable for different evoked responses. In one case with a delayed wave V, the …

Data Acquisition And Parameter Identification In Electro-Oculography, Wolfgang Poelzleitner

Theses

Electro-Oculography (EOG) is used in clinical ophthalmology to measure the time response of the corneoretinal potential (CRP) to changes in light intensity. An automatized data acquisition and system modeling link has been developed that significantly reduces processing time presently required for EOG. The data acquisition is performed on a microprocessor based instrument, which supervises the EOG-test, measures the potential and, after completion of the test, transfers the results to a mainframe computer. Parameter identification routines provide graphical representation and mathematical models for the CRP. Both nonlinear curve fitting methods and Least Squares System Identification schemes are used.

Optimization Of A New Linear Fm Detector Using Digital Signal Processing Techniques, Edward J.A. Kratt

Dissertations

This dissertation describes and synthesizes a new member of the family of FM detectors introduced earlier by Klapper and Kratt. A salient property of these detectors is low delay with excellent sensitivity. The emphasis in the new detector is on the ease of digital implementation. In addition, the new detector is also extremely linear. In congruence with the other Klapper-Kratt detectors, it makes use of zero group delay elements, balance at RF, quasi-synchronous detection and carrier cancellation. The Performance of the detector is mathematically analyzed under the conditions of a modulated input wave, sinewave [sic] interference, and noise. The results …

Application Of Fuzzy Theory To Pattern Recognition, David Usechak

Dissertations

Piecewise curve approximation is used to describe boundaries of objects in pictures and waveforms. The method consists of linear and quadratic piecewise polynomial approximations in which the error must not exceed a predetermined cost threshold. A fuzzy Bayes model is used to determine if a breakpoint exists within an interval I_n or between intervals I_n and I_n+1 and to determine whether these intervals can be merged for data compaction reasons. In order to achieve these objectives a new fast algorithm has been proposed which gives good curve/object fitting. This algorithm uses a technique for generating generalized inverse …

The Role Of Electrical Noise In Screening Transformers Prone To Failure, Rajeev D. Shirodkar

Theses

Insulation used as a barrier between the high voltage and low voltage windings of a transformer has sites of in- homogeneities like pinholes, cracks or voids, developed during the manufacturing process. Thus, these minute air pockets are stressed much more than the solid dielectric, on the application of a voltage stress, because the dielectric constant of the solid insulation is many times that of the air dielectric. As a result, excitation or ionization takes place in the air (gases). The amount of excited or ionized molecules is proportional to the volume of the inhomogenei- ties within the insulation.

Therefore, experiments …

Gallium Nitride Film Deposition By Ionized Cluster Beam Epitaxy, Ghulum Bakiri

Theses

An experimental Ionized Cluster Beam System similar in design to the one developed at Kyoto University in Japan was. designed and constructed in the Microelectronics Laboratory at NJIT. This involved making the working drawings, having the parts machined and then assembling the system in a vacuum system together with the necessary variable power supplies, meters, controls, gas inlets, cooling water connections, etc.

Eleven deposition runs were then attempted to grow gallium nitride utilizing the system constructed. In a typical deposition run, gallium was vaporized from a boron nitride crucible at 1000° C and allowed to expand through a 0.5 mm …

An Experimental System For Observation Of The Rat Coronary Microcirculation Using Digital Image Processing, Wolfgang Braun

Theses

A system was constructed which allows direct observation of the coronary microcirculation of the beating rat heart. An EKG triggered strobe is used on the microscope light source to "stop" the action of the beating heart so the surface microvessels can be observed di rectly under the microscope. Experimental results are recorded on videotape and played back for frame-by-frame analysis of the data using digital Image processing techniques such as digital filtering, image extraction, image enhancement and edge detection.

The application of image enhancement techniques (high order and low order enhancement methods ) as well as edge detection using a …

A Parameter Identification System For The Human Visual Evoked Response, Robert Kalle Michaels

Theses

The Human Visual Evoked Response (VER) provides a useful tool for analyzing an individual's visual system. However, mere inspection of the signal may not always be the best way to make a diagnosis of the patient. To aid in this diagnosis a parameter identification system has been developed which fits the response to an analog model. The development of the model was based on the results of a survey of previous work in the field. Data were acquired from a data acquisition/processing system developed at the New Jersey University of Medicine and Dentistry and the Eye Institute of New Jersey. …

Automated Instrumentation System For Studies Of Metabolic Rates In Rats, Suhas P. Pathak

Theses

The task of the instrumentation system is to measure the respiratory exchange in rats in a controlled experiment. Air is drawn at a predeter-mined rate in and out of rat chambers. The proportion of oxygen and carbon dioxide in the ensuing air indicates the respiratory rate of the rat. The entire operation is controlled by a microcomputer whose most important functions are: to direct the flow of air through the rat chambers by switching valves; and to collect data about the percentages of gases in question.

Thus with the help of a computer it is possible to monitor and control …

Broadband Base Isolated Asymetrically Fed Vhf Antenna, Peter Edward Cunningham

Dissertations

Antennas presently being used for vehicular military VHF communications are narrowband. New generation frequency hopping radios, however, require broadband antennas. The antenna must be base isolated in order to reduce undesirable pattern nulls and impedance variations caused by currents induced on the support structure. Physical constraints limit the antenna length to three meters while operating from a frequency of 30 MHz to 88 MHz.

To satisfy the above requirements a model of a broadband, base isolated, cylindrical antenna less than three meters long was analyzed and built. Equations for the current distribution as a function of the physical parameters were …

Moment Method Solution Of The Time-Dependent Transport Equation To Describe The Scattering Of Gaussian Plane Wave Pulses By A Forest, Nack Yang Cho

Theses

The time dependent transport equation is used to study the transmission of periodic pulses through a forest. The forest is assumed to occupy a half-space region, to be statistically homogeneous and to scatter energy isotropically A periodic sequence of Gaussian plane wave pulses is assumed to enter the forest normally from free space. The transport equation is solved by the moment method using triangular expansion functions. Numerical results indicate the dependence of the incoherent intensity on penetration depth, observation angle, albedo and pulse repetition rate.

Computer Aided Analysis Of Electroencephalographic Waveforms, Edward Tadeusz Polkowski

Theses

An approach to analysis of EEG waveforms is described. The procedure utilizes a PDP -11 computer to perform a Fast Fourier Transform on four channels of data simultaneously. The transforms are done in real time and. the results are plotted in a manner which allows the operator to easily determine the major background activity and to check for left-right symmetries in brain waves. Patient data is used to verify the computer output against actual clinical diagnoses.

Blood Pressure Signal Simulation In An Artificial Circulation System, Shaw-Jyh Shin

Theses

The major objective of this thesis is to produce a desired pressure waveform in an artifical circulation system by using a Z-80 microcomputer controlled stepper motor. This will simulate the desired blood pressure waveform in the human body and can be used for clinical application.

A microcomputer simulation was used for setting up an electrical circuit model to represent the artificial circulation system as well as for finding out the relationship between motor speed (piston displacement) and pressure waveform.

Using this techniques, a desired pressure waveform which represents the blood pressure waveform in the human body can be obtained.