Engineering Commons^™

A Frequency Domain Based Self-Tuning Pid Controller, John Ringwood, Aidan O'Dwyer

Conference papers

Traditionally, both explicit and implicit self-tuning controllers have employed time domain techniques for the identification and tracking of plant and controller parameters. The use of the frequency domain provides concise information on the dynamics of the process which has led to its wide acceptance as a domain for controller design. This paper demonstrates a method employing recursive, on-line measurement of the process frequency response, with a straightforward calculation of PID controller parameters. The computational effort involved is comparable with that of a time domain technique.

Model Parameter And Time Delay Estimation Using Gradient Methods, Aidan O'Dwyer, John Ringwood

Conference papers

A number of approaches have been proposed for parameter and time delay estimation of process models in single input, single output (SISO) control systems using gradient descent algorithms; some of these approaches involve the selection of a rational polynomial that is used to approximate time delay variations. This paper takes a generalised approach to the investigation of the most appropriate choice of the rational polynomial, and the gradient descent algorithm, to be used.

The Role Of Component Packaging In System Electromagnetic Compatibility, Todd H. Hubing

Electrical and Computer Engineering Faculty Research & Creative Works

Increases in the speed and density of electronic systems do not necessarily result in tougher electromagnetic compatibility problems. In fact, recent advances in packaging technology can help designers to meet electromagnetic compatibility requirements. However, working with new technologies requires us to re-evaluate existing EMC design models and guidelines. Understanding the system-level impact of component-level packaging changes, is a prerequisite for meeting stringent electromagnetic compatibility requirements in a timely and cost-effective manner.

Optimal Control Of Infinite-Order Smart Composite Structural Systems Using Distributed Sensors, Robert Butler, Vittal S. Rao

Electrical and Computer Engineering Faculty Research & Creative Works

In recent years there has been considerable interest in the design of spatially shaped distributed sensors for the control of infinite-order structural systems. The smart materials polyvinylidene fluoride (PVDF) and shape-memory alloys can be utilized in the development of customized distributed sensors. Sensor shape-optimization techniques are needed for the implementation of optimal control strategies. In this paper, a method for generating the shapes of distributed sensors using finite-dimensional approximations to desired curvature and curvature rate kernels is examined. The output of these spatially distributed sensors is utilized directly as the control signal for suppressing vibrations in infinite-order structural systems. This …

Order-Recursive Fir Smoothers, Jenq Tay Yuan, John A. Stuller

Electrical and Computer Engineering Faculty Research & Creative Works

This Paper Introduces Order-Recursive FIR Smoothers and Shows that Order-Recursive FIR Filters Are Special Forms that Occur When No Future Data Values Are Used to Estimate the Signal. the Formulation Leads Naturally to Generalizations of the Concepts of Prediction-Error Basis and Cholesky Factorization Which Are Well Known in FIR Filter Design. © 1994 IEEE

Numerical Modeling Of Cuinse2 An D Cdte Solar Cells, Jeffery L. Gray, Richard. J. Schwartz, Youn Jung Lee

Department of Electrical and Computer Engineering Technical Reports

No abstract provided.

Effective Bandgap Shrinkage In Gaas, E. S. Harmon, Michael R. Melloch, Mark S. Lundstrom

Department of Electrical and Computer Engineering Faculty Publications

Electrical measurements of the equilibrium np product (n2ie) in heavily doped n‐ and p‐GaAs were performed. The n2ieDproduct (where D is the diffusivity) was measured by fitting the collector current‐voltage characteristic of a homojunction bipolar transistor to an ideal diode equation modified to account for transport in thin base transistors.The n2ie product was then extracted from n2ieD by utilizing diffusivity results obtained with the zero‐field time‐of‐flight technique. Our results show significant effective band‐gap shrinkage in heavily doped p‐GaAs, and very little effective band‐gap shrinkage …

Thermal Velocity Limits To Diffusive Electron Transport In Thin‐Base Np+N Gaas Bipolar Transistors, E. S. Harmon, Michael R. Melloch, Mark S. Lundstrom, F. Cardone

Department of Electrical and Computer Engineering Faculty Publications

We present experimental evidence that minority electron transport across a thin, quasineutral p+ GaAs region is limited by the thermal velocity of the electrons rather than by conventional diffusive transport. A set of GaAs homojunction np+n transistors with base widths of 4000, 2000, 1000, and 500 Å was fabricated and characterized. The diffusive modelpredicts that the dc collector current of the 500‐Å base width transistors should be eight times larger than the collector current of transistors with a 4000‐Å‐wide base. The experimental results, however, show only a factor of ~3.5 increase in collector current. The measured collector …

A Study Of Dc Permanent Magnet Motor Noise Related To Line Current, Candace Rogers Suriano

Department of Electrical and Computer Engineering Technical Reports

Lightweight, compact and inexpensive DC permanent magnet motors are well suited for low cost high production use in industry. Unfortunately, the audible noise emanating from these motors can cause a false negative perception of the motor's quality. In cars, for example, fan motor noise can be a nuisance. The objective of this thesis is to examine the connection between motor noise and the line current wave form for a specific four pole DC permanent magnet motor. It is further concerned with identifying the underlying factors which influence the line current ripple. An audible noise to motor current transfer function is …

Field Tests Of The Dolphin--A Remotely Operated Survey Vehicle, M T. Kalcic, Edit J. Kaminsky

Electrical Engineering Faculty Publications

No abstract provided.

An Analysis Of The Payback Potential Of New Lighting Technology, James L. Cox

Masters Theses

Recent, energy saving improvements in lighting technology have been made involving the use of more efficient lamps, silver coated light reflectors, and electronic light ballasts. Research indicates that it is economically feasible to retrofit existing light fixtures to utilize the advantages of these developments. This process consists of the removal of all standard lamps and ballasts in each light fixture, the installation of a highly refined light reflector and the replacement of the existing lamps with brighter, more efficient ones. Standard magnetic ballasts are exchanged for more efficient electronic ballasts. Resulting is a light fixture that produces a comparable amount …

Threshold Characteristics Of Multimode Semiconductor Lasers, Lee W. Casperson, Mehdi Khoshnevissan

Electrical and Computer Engineering Faculty Publications and Presentations

The effects of spontaneous emission on the threshold characteristics of multimode laser oscillators with mixed line broadening are considered in detail. Most previous studies of multimode laser operation have emphasized the two limits of homogeneous and inhomogeneous broadening. With homogeneous broadening there is a tendency for oscillation in a single longitudinal mode, while in the inhomogeneous limit oscillation over much of the gain spectrum is expected. All practical lasers are somewhere between these limits, and this study explores the mode characteristics of lasers with mixed line broadening. Special attention is given to the important practical case of semiconductor diode lasers, …

Transform Method Of Processing For Speckle Strain-Rate Measurements, Donald D. Duncan, Sean J. Kirkpatrick, F. Fausten Mark, Lawrence W. Hunter

Electrical and Computer Engineering Faculty Publications and Presentations

We have developed a highly sensitive method for measuring thermal expansion, mechanical strain, and creep rates. We use the well-known technique of observing laser speckle with a pair of linear array cameras, but we employ a data-processing approach based on a two-dimensional transform of the speckle histories from each camera. This technique can effect large gauge sizes, which are important in the assessment of the spatial statistics of creep. Further, the algorithm provides simultaneous global estimates of the strain rates at both small- and large-scale sizes. This feature may be of value in the investigation of materials with different short- …

Immittance Spectroscopy Of Smart Components And Novel Devices, Mohammad Anwarul Alim, Sanjida Khanam, Martin A. Seitz

Electrical and Computer Engineering Faculty Research and Publications

AC small-signal immittance spectroscopy is employed as a viable tool to demonstrate electrical characterization, performance improvement, and quality assurance issues of smart materials-based components and novel devices. The variation in the ac response, complemented via dc measurements within a range of tolerating temperature, delineates competing phenomena occurring in the microstructures of these engineering material systems. The results are presented in a generic manner with possible explanations on the mechanisms for two selected Debye-like (nearly ideal) and non-Debye (non-ideal) low-capacitance resistors. This spectroscopic approach allows systematic development of a representative equivalent circuit, considered to be the characteristic of the devices and …

Programmable Analog Array Circuit, Marek Perkowski, Edmund Pierzchala

Electrical and Computer Engineering Faculty Publications and Presentations

There is disclosed a programmable analog or mixed analog/ digital circuit. More particularly, this invention provides a circuit architecture that is ?exible for a programmable electronic hardWare device or for an analog circuit Whose input and output signals are analog or multi-valued in nature, and primarily continuous in time. There is further disclosed a design for a current-mode integrator and sample-and-hold circuit, based upon Miller effect.

Investigation Of Cebus Traffic Across A Router, With And Without Acknowledgment, Wannakuwattawaduge Lalith Fernando

Theses

A power line and twisted pair implementation of the Consumer Electronic Bus(CEBus) has great potential toward inexpensive home automation. Since the introduction of the CEBus Standard, there has been increasing efforts on evaluating its performance. However, most of the work has been performed for unacknowledged networks. Pan[18] was able to implement an acknowledged network for PL CEBus. In this thesis, the acknowledgment process has been taken one step further. The effect of acknowledgment on a Power Line and Twisted Pair CEBus network interconnected by a router is studied. CEBus network performance parameters such as message and packet delays, message throughput, …

Impact Of Field-Dependent Electronic Trapping Across Coulomb Repulsive Potentials On Low Frequency Charge Oscillations, R. P. Joshi, K. H. Schoenbach, P. K. Raha

Bioelectrics Publications

We have performed Monte Carlo simulations to obtain the field dependence of electronic trapping across repulsive potentials in GaAs. Such repulsive centers are associated with deep level impurities having multiply charged states. Our results reveal a field‐dependent maxima in the electronic capture coefficient, and the overall shape is seen to depend on the background electron density due to the effects of screening. Based on the Monte Carlo calculations, we have examined the stability of compensated semiconductors containing such repulsive centers. Our analysis indicates a potential for low frequency charge oscillations which is in keeping with available experimental data.

A Multi-Dimensional Model Of Passive Mesfets For Use In Non-Linear Microwave Signal Processing, Roger Dorval

Theses

A multi-dimensional model which accurately predicts device non-linearities over frequency and power has been developed for MESFETs used in a passive configuration in microwave signal processing applications.

Historically, MESFETs have been used in linear control applications as passive microwave switches and attenuators. More recently, MESFETs operated as passive elements have been employed as power-sensitive non-linear transfer function generators to produce limiters, phase shifters, and linearizers. These devices offer simplicity, high performance, and the opportunity for application in MMIC technology.

This thesis deals with a mapping of passive MESFET non-linear characteristics, and provides insight into the causes of non-linearity in MESFETs …

Polarimetric Fiber Optic Weigh-In-Motion Sensor, Jieping Wang

Theses

During the past decade, the demand for new methods of measuring the weight of moving vehicles has grown substantially. In the 1980's, several techniques for weighing vehicles in motion were developed. However, they often suffer from high installation and maintenance costs as well as low accuracy. This thesis describes a new technique based on polarization preserving optical fibers. A fibercore HB600 Bow-Tie fiber with an initial beat length of 1.16 mm was employed in the present study. Sensor response is discussed in terms of the effects of force amplitudes and velocities on the calibration parameter T_f. T_{f …}

A Check Parameter Method For Use In Designing Relays, H Kadete

Tanzania Journal of Engineering and Technology (TJET)

Low quality magnetic steel available locally has been successfully used as core material for a relay. New design principles as well as construction procedure used in development of a prototype are presented. Then the new approach is assessed and found to deliver acceptable accuracy.

Practical Aspects In Sensing Vrm Magneti- Sation Characteristics For Rotor Position Detection, N Mvungi

Tanzania Journal of Engineering and Technology (TJET)

The detection of rotor position (stator/roror poles overlap) in a variable reluc- tance motor using the dependence of permeance on rotor position is the core of the effort to eliminate the need of a physical position sensor in the rotor shaft in the positional feedback operation of the motor. The reliability of the whole proc- ess Of eliminating the need of a physical sensor rests squarely On the ability to measure the instantaneous permeance ofa phase when the motor is in operation and at stand still. This paper presents an experimental investigation on the in- triguing problems of obtaining repeatable …

Optical Wavelet Transform For Fingerprint Identification, Robert P. Macdonald

Theses and Dissertations

The Federal Bureau of Investigation FBI has recently sanctioned a wavelet fingerprint image compression algorithm developed for reducing storage requirements of digitized fingerprints. This research implements an optical wavelet transform of a fingerprint image, as the first step in an optical fingerprint identification process. Wavelet filters are created from computer generated holograms of biorthogonal wavelets, the same wavelets implemented in the FBI algorithm. Using a detour phase holographic technique, a complex binary filter mask is created with both symmetry and linear phase. The wavelet transform is implemented with continuous shift using an optical correlation between binarized fingerprints written on a …

Color Image Segmentation, Kimberley A. Mccrae

Theses and Dissertations

The most difficult stage of automated target recognition ATR is segmentation. Current AFIT segmentation problems include faces and tactical targets previous efforts to segment these objects have used intensity and motion cues. This thesis develops a color preprocessing scheme to be used with the other segmentation techniques. A neural network is trained to identify the color of a desired object, eliminating all but that color from the scene. Gabor correlations and 2D wavelet transformations will be performed on stationary images and 3D wavelet transforms on multispectral data will incorporate color and motion detection into the machine visual system. The thesis …

Human Visual System Enhancement Of Reconstructed Satellite Images, James E. Treleaven

Theses and Dissertations

This research investigated the enhancement of satellite images. The goal was to develop and test a suite of image enhancement software routines to improve the quality of reconstructed images for the human visual system. The primary focus was to enhance satellite features. Enhancement was accomplished in both the spatial domain and the frequency domain. In the spatial domain, routines were developed to enhance image contrast and edges. In the frequency domain, a routine was developed using research into the human visual system. The transfer function of the human visual system was used to develop a filter for frequency domain enhancement. …

Simultaneous Design Of Active Vibration Control And Passive Damping, Michele Lynn Devereaux Gaudreault

Theses and Dissertations

A modified form of the standard linear quadratic regulator LQR cost functional is used to optimally blend active vibration control and passive structural damping, whether viscous or viscoelastic. Viscoelastic damping is first modelled by a standard linear model, and then by a fractional derivative model. For the viscous damping case and the classically modelled viscoelastic damping case, a sub-optimal closed form solution is derived that is independent of the initial conditions. An iterative technique that minimizes the average value of the cost functional and one that minimizes the maximum value are developed. Both techniques are applicable to viscous and viscoelastic …

Analysis And Characteristics Of Compressor Stall Precursor Signals In Forward And Aft Swept High Speed Compressor, Bernard J. Frank

Theses and Dissertations

The stall characteristic of four single-stage transonic compressor rotors were investigated as they were throttled to stall. Forward-swept, backward-swept, and straight leading edge rotors were examined. Three methods of analysis (1) windowed power spectrum densities of pressure and spatial Fourier coefficients, (2) phase tracking analysis, and (3) system identification were used to identify the first appearance of modal waves and their accompanying frequencies in order to identify a stall warning time. A direct correlation between the amount of stall warning time and the shape of the compressor characteristic was found. Specifically, if the compressor characteristic had a significant period of …

Exploring Qdes As A Tool For Determining Limits Of Achievable Performance In Aircraft Design, Mark F. Reidinger

Theses and Dissertations

This thesis explores the usefulness of a computer aided control design software package called QDES in determining the limits of achievable aircraft performance as it relates to controller capability. Modern aircraft, particularly fighters, are being designed to be statically unstable to enhance their maneuverability and performance. It is possible that the aircraft, although physically capable of a certain level of performance due to its engine/ airframe combination, may be uncontrollable up to this level. This study sought to develop a methodology to use QDES to make a preliminary analysis of an aircraft design to determine if there exists a controller …

Optimal Control Design Advantages Utilizing Two-Degree-Of-Freedom Controllers, Michael J. Stephens

Theses and Dissertations

The purpose of this study was to investigate and describe the differences between a one-degree-of-freedom (1-DOF) controller, in which a controller is placed in a single location in the control loop, and a two-degree- of-freedom (2-DOF) controller, in which two separate controllers are designed -- one in the feedback loop and the other as a prefilter in the forward loop. The approach involved summarizing the major rules governing loop shaping for performance and robustness in the 1-DOF case and then extending the concepts to the 2-DOF case. H₂ optimization was utilized to perform several types of SISO examples and …

Electrical Properties Of P-Type Gainp2, Roy S. Calfas

Theses and Dissertations

The GaInP₂ n⁺—p junction diode has recently become important to the development of high efficiency GaInP₂GaAs dual junction solar cells, which have a demonstrated air mass 1.5 conversion efficiencies in excess of 27. In order to study the effects of long term exposure to the space environment, the GaInP₂ n+—p junction diodes were irradiated with a 1 MeV electron beam with a fluence of 10¹⁶ electrons/cm². Since little is known about deep level defects traps in GaInP₂, a deep level transient spectroscopy DLTS study was made to characterize the …

Partitioning Structural Vhdl Circuits For Parallel Execution On Hypercubes, Kevin L. Kapp

Theses and Dissertations

Distributing simulations among multiple processors is one approach to reducing VHDL simulation time for large VLSI circuit designs. However, parallel simulation introduces the problem of how to partition the logic gates and system behaviors among the available processors in order to obtain maximum speedup. This research investigates deliberate partitioning algorithms that account for the complex inter-dependency structure of the circuit behaviors. Once an initial partition has been obtained, a border annealing algorithm is used to iteratively improve the partition. In addition, methods of measuring the cost of a partition and relating it to the resulting simulation performance are investigated. Structural …