Engineering Commons^™

Hypercard-Based Learning Environment For Diades, Ali A. Shamsapour

Dissertations and Theses

This thesis is an attempt to create a HyperCard-based learning environment to teach DIADES and other related material. It is a departure from the classical Computer Aided Instruction methods towards a more flexible and user-controlled design. The goal was to set the foundation of a new CAI design which would closely resemble a Hyper-Text system. These systems are characterized as having interconnections between related concepts in the CAI environment.

Processing Of One-Fiber Interferometric Fiber-Optic Sensor Signals, A. Tino Alavie, Barry Grossman, Michael Thursby

Electrical Engineering and Computer Science Faculty Publications

Recent research conducted in the Fiber -Optic Sensor Systems Laboratory at Florida Institute of Technology in fiber -optic strain sensors for use in smart structures has concentrated primarily on one -fiber interferometers. Sensors using this technique are of particular interest because they are rugged and provide reasonable strain sensitivities, typically a thousand times that of microbend sensors, while requiring only a single optical fiber. As in two -fiber interferometers, some method must be used to convert the sensor signal output to an absolute strain value. One technique is to provide active phase tracking to keep the sensor signal output at …

Fiber-Optic Sensor And Smart Structures Research At Florida Institute Of Technology, Barry Grossman, Tino Alavie, Fred Ham, Jorge Franke, Michael Thursby

Electrical Engineering and Computer Science Faculty Publications

This paper discusses the fundamental issues being investigated by Florida Institute of Technology (F.I.T.) to implement the technology of smart structural systems for DoD, NASA, and commercial applications. Embedded sensors and actuators controlled by processors can provide a modification of the mechanical characteristics of composite structures to produce smart structures1-3. Recent advances in material science have spurred the development and use of composite materials in a wide range of applications from rotocraft blades and advanced tactical fighter aircraft to undersea and aerospace structures. Along with the advantages of an increased strength-to-weight ratio, the use of these materials has raised a …

Investigation Of Techniques For High Speed Cmos Arbitrary Waveform Generation, Albert Henry Nehl

Dissertations and Theses

Today a growing number of applications in design engineering, production and environmental testing, and system service require specific analog waveforms and digital patterns. Such requirements are neither satisfactorily nor easily met by the use of standard function or single purpose, custom generators.

Traditional methods of waveform generation suffer from undesirable complexity or mediocre performance and are otherwise limited. For the majority of arbitrary waveform generation applications, including medical engineering, modal analysis and electronic engineering, direct digital synthesis techniques are satisfactory. Direct digital synthesis, based generally on periodic retrieval of predetermined amplitude values, may be used to generate such waveforms. Within …

Formation And Characterization Of Thin Superconducting Y-Ba-Cu-O Films, Gyusuk Kim

Theses

Thin Y-Ba-Cu-O superconducting films were fabricated reproducibly on MgO (100) substrates by two different processes ; (1) deposition at a low substrate temperature fiom a single sintered YBa₂Cu_3.3O_x target using RF diode reactive sputtering followed by a post-annealing at around 830 ° C ; (2) deposition at the crystallization temperature under oxidizing atmosphere. The superconducting properties of films deposited by process (1) and (2) were studied. The variation of film composition and thickness as a function of distance from the target gas pressure and distance between target and substrate was studied. The Dependence of the …

Adaptive Fir Digital Filter Design And Simulation In The Noise Reduction System, Jack Jiabing Pang

Theses

The adaptive FIR digital filter is designed to suppress the noise in the tape recording and audio communication systems. The cutoff frequency of the digital FIR filters can be varied adaptively depending on the energy level of the input signal. In audio communication, especially, in tape recording systems, the noise obviously gets much bigger, when the frequency band of the system increases. The noise reduction system makes use of a phenomenon called masking, where the big signal-to-noise ratio makes human ears not sensitive to the noise. In a constant interval time, the system detects the signal level and compares the …

Sputter Deposition And Characterization Of High Tc Superconducting Thin Films, Vipulkumar Patel

Theses

Preparation of thin superconducting films by direct RF sputter deposition on Si, MgO, SrTiO₃ and quartz substrates and silver and Sl3N4 buffer layers (deposited on silicon substrates) was studied. To study resistance versus temperature characteristics of thin films and bulk materials, a computerized measurement system was developed. 1-1.5 pm thick YBaCuO films deposited on Si₃N₄/Si were found to be insulating with room temperature resistance higher than 236KΩ, while films with Ag as a buffer and/or a passivating layer exhibited metallic behavior with room temperature resistances lower than 700mΩ. The area directly under the 2.25 inches …

Fault Tolerant Benes Networks, Manoj Bhatnagar

Theses

A fairly large number of fault tolerant topologies have been proposed for the multistage interconnection networks in the recent years. However very few of these schemes have focused on the Benes network. This thesis presents two new fault tolerant architectures for the Benes network. The thesis includes algorithms to construct these fault tolerant networks from a Benes network and the reconfiguration procedure in the event of a fault. The hardware characteristics of both the fault tolerant networks have been analyzed and compared.

Uniformity Corrector And Signal Processing For A 160 X 244-Element Ir-Ccd Camera With Ptsi Schottky-Barrier Detectors, Paul D. Blume

Theses

An off-set-type, one point response uniformity corrector and the associated signal processing circuits was developed to be used for a 160 x 244-element IR-CCD camera with PtSi Schottky-barrier detectors. Image sensors with PtSi Schottky-barrier detectors exhibit two types of noise in the displayed video output, a temporal noise and a spatial fixed pattern noise. The performance of the image sensor, limited by the spatial noise which obscures low contrast detail and limits camera sensitivity, can be improved by a uniformity corrector. The uniformity corrector was constructed to substantially reduce the spatial noise in the output display by digitally subtracting a …

The Magnetotransport Analysis Of Hemt Structures At Low Fields, Naghmeh Nouri

Theses

On the basis of a study on numerous HEMT structures, a simple and useful technique was established for the characterization of 2DEG layers. This technique utilizes the magnetic field-dependence of the resistivity and Hall coefficient of the HEMT structure, to determine the values of the sheet density and mobility of 2DEG in the presence of other parallel conductive layers. This method of analysis was compared with previously used techniques such as Shubnikov-de Haas and the etch removal of the parallel conductive layers. Through this comparison and several measurements it was found that this procedure gives reproducible values for the 2DEG …

Simulation And Design Of Field Emission Diode, Yun Yuan

Theses

A new generation of microelectronic devices utilizing vacuum field emission cathodes becomes surging interest in recent years. This paper concentrates on the study of the field emission diode — a basic vacuum microelectronic device. The field emission efficiency, current spatial distribution and time dispersion of conical tips and wedges of various geometrical shapes are compared and calculated by analytical methods and computer simulations. Two field emitter heating effects, namely the Joule heating and Nottingham effect, are discussed theoretically. All the simulation results in this paper are performed on 386 based personal computer. The limiting memory space of PC induced simulation …

Infrared Tv Camera With Ptsi Schottky-Barrier Detectors, Steven J. Blume

Theses

An infrared TV camera was developed for operating various sizes of Schottky-barrier IR-CCD image sensor chips. A digitally programmable frequency synthesizer is used so that the camera has the flexibility of using a 160 x 244 or 320 x 244 image sensor developed at the David Sarnoff Research Center. The outputs of the camera are compatible with an XYZ monitor, a standard TV monitor, and a computer workstation. Operation of the camera was demonstrated with a 160 x 244 image sensor producing an output on a standard TV monitor. Performance of the IR-TV camera system was investigated by evaluating CCD …

Performance Analysis Of A Dynamic Reservation Multichannel Local Area Network, Abubakar A. Ibrahim

Theses

A reservation multiaccess protocol. is proposed to be used on multichannel local area networks. This protocol is advantageous for networks supporting integrated services. The delay and throughput performance for message transmission are obtained by analysist The delay performance of the protocol is similar to the M-CSMA/CD/IC multichannel network proposed by Marsan and Roffinella. It is found that the reservation protocol can provide better throughput-delay characteristics when the fraction of the total available bandwidth allocated to data is increased. It is also observed that the maximum throughput increases with the increase in the number of channels when the total bandwidth is …

The Design Of Decentralized Optimal Regulator Systems Using Matrix Minimum Principle, Sunny Lai Yick

Theses

This research considers the design of linear, time-varying regulator systems using Matrix Minimum Principle in the frame work of decentralized control theory. The regulator system is modeled in terms of state equation with multiple controllers. Each controller works cooperatively to optimize a common quadratic performance index. An additional constraint is imposed such that the controllers are linear time-varying functions of the outputs.

Necessary and sufficient conditions for optimality of the system are provided by the Matrix Minimum Principle and Hamilton-Jacobi Theory.

Two examples are developed to illustrate the concept.

Image Preprocessing For Phase- Only Filtering, Samuel Peter Kozaitis, Atikom Roeksabutr

Electrical Engineering and Computer Science Faculty Publications

We compare the performance of an optical binary phase-only correlator using several nonlinear filters for preprocessing. An image of an airfield with different but similar appearing planes is used as the input data. The performance of the correlator was measured by examining several parameters in the correlation plane. Performance criteria are the signal-to-clutter ratio, the signal-to-noise ratio for objects within the same class, and the variance of the correlation peak within a class. Input images to the correlator were preprocessed using nonlinear filters based on both median filtering and adaptive filtering. The preprocessing improved the performance of the correlator by …

Self-Mode-Locking Of A Semiconductor Laser Using Positive Feedback, Dennis J. Derickson, R. J. Helkey, A. Mar, P. A. Morton, J. E. Bowers

Electrical Engineering

A new mode-locking technique, self-mode-locking, is described which uses the detected optical pulses from the mode-locked laser as the active driving source. This technique forms narrow-width mode-locked optical pulses at low repetition rates without the use of a microwave synthesizer

Major Project Management: The Yale Telecommunications Project

ACUTA: Other Publications

Back in the good old days, when the telephone business was simpler and Saturday night television was worth watching, I can remember Ted Knight the newsman (remember him on The Mary Tyler Moore Show?) looking off into some imagined horizon in the newsroom when asked how he happened to come to his current position. With head cocked upward and his hand clutching his right lapel, he'd start in his deepest, most pompous voice: “lt all started in a small, 5,000-watt radio station..." Around here it a!! started with a 12,000-line, decade-old Centrex system and a new hospital building going up …

The Extraction Of The Equivalent Circuit Parameters Of Surface Acoustic Wave Resonators, Brent H. Horine

Retrospective Theses and Dissertations

The application of the Electronic Industries Association suggested standard, EIA-512 [1], has been successfully applied to quartz crystal resonators for extraction of the equivalent circuit model parameters. This technique has been shown to be very successful in the operation range to several hundred megahertz. This same technique is proposed to be applied to many differing types of resonators through the full spectrum of frequencies. This thesis will discuss measurement and testing of Surface Acoustic Wave (Saw) resonators at the higher frequencies. The packaging configuration in conjunction with SAW devices can lead to significant parasitic effects. In order to successfully extract …

Boundary Element-Image Method Approach To Seismic Modeling, Richard E. Dubroff

Electrical and Computer Engineering Faculty Research & Creative Works

The Boundary Element-Image Method is Proposed as a Method for Generating Synthetic Seismograms in a System of Piecewise Homogeneous Layers. the Present Approach Uses the Boundary Conditions Explicitly in Order to Develop a System of Integral Equations. Although This Method Can Be Formulated in a General Way, Specific Computational Advantages Occur When the Basis and Testing Functions Are Chosen as Harmonically Related Complex Sinusoids. -From Authors

Economic Models For Battery Energy Storage: Improvements For Existing Methods, Ronald C. Reckrodt, Max Darwin Anderson, Raymond Michael Kluczny

Electrical and Computer Engineering Faculty Research & Creative Works

While the technology required to produce viable Battery Energy Storage System exists, the economic feasibility (cost vs. benefits) of building these systems requires justification. First, a generalized decision diagram was developed to ensure that all of the economic factors were considered and properly related for the customer-side-of-the meter. Next, two economic models that had consistently given differing results were compared. One was the McKinney model developed at UM-Rolla in 1987; the second was the SYSPLAN model developed by Battelle. Differences were resolved on a point-by-point basis with reference to the current economic environment. The economic model was upgraded to include …

Reduced Order Modeling Methods For Turret-Gun System, Vittal S. Rao, Norman P. Coleman

Electrical and Computer Engineering Faculty Research & Creative Works

Reduced-order modeling techniques are used to design lower order robust controllers for a turret-gun system. The balance-truncation, Routh approximation, and L. Litz's (1980) modal techniques are used to derive the models. A critical comparison of the time and frequency response characteristics of the original and reduced order models is made. The spillover problem associated with a reduced-order model is investigated.

Growth Of Cdte And Cds/Cdte Heterojunctions On Metal Substrates By Spray Pyrolysis, Alok K. Berry, Jack L. Boone, Thomas P. Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

Preliminary results of the spray pyrolysis of thin films of CdTe on metal substrates are reported. The films are hard and adhere well to the substrate. A n-CdS/p-CdTe rectifying junction is also grown completely by spray pyrolysis on the metallic substrate. The ability to produce p-n junctions using the inexpensive and simple procedure of spray pyrolysis may lead to a viable process for mass production of solar cells. © 1990.

Fixed Mode Elimination In Decentralized Control Systems Using Eigenvalue Sensitivities, Jorge R.B. Souza, Vittal S. Rao

Electrical and Computer Engineering Faculty Research & Creative Works

The knowledge of fixed modes plays an important role in the design of decentralized controllers for large scale systems. An approach based on a parametric sensitivity of eigenvalues is proposed to select the information to be exchanged between control stations in order to eliminate decentralized fixed modes. The procedure is illustrated with an example. © 1990.

A Model Of Dc Glow Discharges With Abnormal Cathode Fall, Karl H. Schoenbach, Hao Chen, G. Schaefer

Bioelectrics Publications

A model for an abnormal glow discharge, including a self‐consistent analysis of the cathode fall, was developed. It combines microscopic particle simulation by means of Monte Carlo methods with a fluid model of the gas discharge. The model allows calculations of the steady‐state electrical field distribution, the charged‐particle densities, and the current densities along the axis of the discharge. The model was used to simulate a glow discharge in 80% He and 20% SF₆ at a pressure of 8 Torr with a current density of 1 A/cm². The computed discharge voltage agrees well with measured values. The …

The Parallel Implementation Of The Waveform Relaxation Method For Transient Stability Simulations, Marija D. Ilić, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, the authors extend the results of their earlier paper on waveform relamtion (WR), which is a parallel algorithm for transient stability analysis. The WR algorithm is extended to a structure-preserving power system model in which the loads are retained. This results in a system of differential/ algebraic equations (DAEs). Power systems exhibit several unique dynamic properties which may be exploited in an advantageous manner by the WR algorithm. This leads to a greater computational efficiency than most other direct methods of simulation. This paper presents several theoretical results as well as computational results on parallel implementation.

Design Of Robust Controllers For Gas Turbine Engines, David E. Moellenhoff, Vittal S. Rao, Charles A. Skarvan

Electrical and Computer Engineering Faculty Research & Creative Works

This paper describes robust controller design methodologies for gas turbine engines. A linear state variable model for the engine is derived using partial derivatives. The Linear Quadratic Gaussian with Loop Transfer Recovery (LQG/LTR) and the Parameter Robust Linear Quadratic Gaussian (PRLQG) robust controller design methodologies have been used to design a controller for gas turbine engines. A new method is proposed by combining the features of LQG/LTR and PRLQG methods and yields good robustness properties with respect to both unstructured uncertainties in the frequency domain and structured parameter variations in the time domain. The new procedure is illustrated with the …

Reduced Order Robust Controllers For An Experimental Flexible Grid, Vittal S. Rao, M. Westerheide, Alok Das

Electrical and Computer Engineering Faculty Research & Creative Works

A procedure for the design and implementation of reduced-order robust controllers for active vibration control on an experimental flexible grid structure is presented. The experimental structure consists of a 5-ft x 5-ft grid made of 2-in-wide, 1/8-in-thick aluminum strips. The grid hangs vertically, being cantilevered at the top to a large T-beam anchored to a cinder block wall. The grid structure is represented by a 75-degree-of-freedom finite-element model, and the controller uses three piezoelectric accelerometer sensors to command three Non collocated DC motor torquers. The modified balance-truncation model-reduction method is used to derive a control synthesis model. These reduced-order models …

Bundled Cable Parameters And Their Impact On Emi Measurement Repeatability, Todd H. Hubing

Electrical and Computer Engineering Faculty Research & Creative Works

EMI (electromagnetic interference) test procedures specify that long cables should be bundled at their center in some circumstances. The author investigates the effect of cable bundling using analytical models and measurements. He examines how cable bundle parameters such as length and "tightness'' can affect the repeatability of the measurement. Simple models of a bundled cable suggest that relatively small changes in the geometry of the bundle can significantly affect the common-mode cable current. Parameters such as length, tightness, location and the number of turns determine the impedance of the bundle. As the impedance of the cable bundle changes, the resonant …

A Balancing Method For Reduced Order Modelling Of Unstable Systems, Rajiva Prakash, Vittal S. Rao

Electrical and Computer Engineering Faculty Research & Creative Works

Moore's balancing method of model reduction has many attractive properties and is used widely in practice. However, this method suffers from the drawback that it is not applicable for unstable systems. This paper introduces a balancing method of model reduction to overcome this problem. The proposed technique obtains the reduced order model by balancing and truncating frequency domain controllability and observability Gramians. Analytical treatment is given for associated properties of the Gramians, and the balancing and truncation steps of model reduction. A numerical example is used to demonstrate the new approach. © 1990.

Influence Of Copper Doping On The Performance Of Optically Controlled Gaas Switches, St. T. Ko, V. K. Lakdawala, K. H. Schoenbach, M. S. Mazzola

Electrical & Computer Engineering Faculty Publications

The influence of the copper concentration in silicon-doped gallium arsenide on the photoionization and photoquenching of charge carriers was studied both experimentally and theoretically. The studies indicate that the compensation ratio (N_Cu/N_Si) is an important parameter for the GaAs:Si:Cu switch systems with regard to the turn-on and turn-off performance. The optimum copper concentration for the use of GaAs:Si:Cu as an optically controlled closing and opening switch is determined.