Engineering Commons^™

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 Parameter Identification System For The Human Electroretinogram, Yu-Huai Hsiao

Theses

The human Electroretinogram (ERG) is obtained in a clinical test to detect physiological abnormalities in the eye. A mathematical model of the ERG has been developed, as well as a system to identify its parameters. The system utilizes several computers. The data acquisition and initial processing is done on a previously developed system at the Eye Institute of New Jersey and the University of Medicine and Dentistry of New Jersey, which has been modified to provide the facility for further processing. Software was developed to use a MINC-11/23 computer at New Jersey Institute of Technology to transfer data between the …

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 …

Reliability Problems And Failure Mechanisms Of Solid Tantalum Capacitors, Ghanshyam B. Nakrani

Theses

Today, reliability is acknowledged as an important item in design and the operation of the electronic systems.

This thesis provides some theory, and experiments are instituted to evaluate the reliability for SOLID TANTALUM CAPACITORS made by different manufacturers. The experimental life test work was done at high temperature of 9S 2°C and high humidity of 95 ± 3% on transfer molded tantalum capacitors.

Literature study concentrates on the reliability in solid tantalum capacitors developed between 1961 and 1984.

Several failure mechanisms with figures are illustrated to point out how higher reliability of solid tantalum capacitors may be developed.

The bibliography …

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 …

Computerized Instrumentation System For Indirect Measurement Of Metabolic Changes In Rats, Holger Tebbje

Theses

This work describes the further development of a system for the measurement of the energy expenditure of rats. Based on the concept of indirect calorimetry the respiratory exchange is monitored in a controlled experiment. Rats are held in cages through which air is drawn and analyzed. Transducers and sensors, interfaced to the computer, are measuring the composition and the physical parameters of the gas entering and leaving the chambers. The data recieved is processed, displayed on a screen, printed and stored for later analysis.

The accuracy and repeatability of the system improved by measuring additional parameters like barometric pressure and …

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.

Digital Fm-Demodulation Using Digital Signal Processing Techniques, Peter Wagner

Theses

This thesis presents the results of research in the area of digital demodulation of FM signals. The first part of the thesis describes the performance of digital Hilbert-transformers and Differentiators that are optimized in a determined bandwidth. These digital filters are used to build a digital Klapper-Kratt detector. According to this procedure, the coefficients of the digital Klapper-Kratt detectors up to the filter length N=25 are calculated and the resulting discriminator ripple computed and evaluated. One suggested algorithm gives the opportunity to balance the detector at a certain center-frequency. The major part of this thesis describes a new approach towards …

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 …

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 …

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.

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 …

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 …

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 …

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 …

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 …

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 …

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 …

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 …