Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

Electrical and Computer Engineering

Series

1993

Institution
Keyword
Publication

Articles 31 - 60 of 103

Full-Text Articles in Engineering

Scattering Of A Light Beam From Waves At An Air-Sea Interface, Donald D. Duncan, W. H. Carter Jun 1993

Scattering Of A Light Beam From Waves At An Air-Sea Interface, Donald D. Duncan, W. H. Carter

Electrical and Computer Engineering Faculty Publications and Presentations

The authors report a new theory that describes the scattering of an upward propagating laser beam from the sea through the air-sea interface in the presence of sea waves. The sea is assumed to be a uniform dielectric and conventional scattering theory is employed by using a modification to the first Born approximation that permits treatment of surface refraction phenomena. Methods of statistical radiometry are also used in a new manner by assuming that the surface scattering function for the sea waves can be treated by a quasi-homogeneous source model to calculate the second-order correlation functions for the partially coherent …

Go to article

Spectroscopic Ellipsometry Studies Of Hf Treated Si (100) Surfaces, Huade Yao, John A. Woollam, Samual A. Alterovitz Jun 1993

Spectroscopic Ellipsometry Studies Of Hf Treated Si (100) Surfaces, Huade Yao, John A. Woollam, Samual A. Alterovitz

Department of Electrical and Computer Engineering: Faculty Publications

Both ex situ and in situ spectroscopic ellipsometry (SE) measurements have been employed to investigate the effects of HF cleaning on Si surfaces. The hydrogeniterminated (H-terminated) Si surface was modeled as an equivalent dielectric layer, and monitored in real time by SE measurements. The SE analyses indicate that after a 20-s 9:l HF dip without rinse, the Si ( 100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si (100) surface was observed, in an ultrahigh vacuum (UHV) chamber, and analyzed by the in situ SE. Evidence for desorption of the H-terminated …

Go to article

Photopolarimeter Based On Planar Grating Diffraction, R. M.A. Azzam, K. A. Giardina Jun 1993

Photopolarimeter Based On Planar Grating Diffraction, R. M.A. Azzam, K. A. Giardina

Electrical Engineering Faculty Publications

A division-of-amplitude photopolarimeter (DOAP) is described that employs a diffraction grating in the conventional spectrometer orientation with the grating grooves normal to the plane of incidence. Four coplanar diffracted orders are used for polarimetric analysis to determine all four Stokes parameters of incident light simultaneously and virtually instantaneously (with the speed being determined solely by the photodetectors and their associated electronics); a fifth order is used for alignment by autocollimation or by use of a position-sensing quadrant detector. To sensitize the instrument for the +45° and -45° azimuths of incident linearly polarized light and for the handedness of incident circular …

Go to article

Feasible Offset And Optimal Offset For Single-Layer Channel Routing, Ronald I. Greenberg, Jau-Der Shih Jun 1993

Feasible Offset And Optimal Offset For Single-Layer Channel Routing, Ronald I. Greenberg, Jau-Der Shih

Computer Science: Faculty Publications and Other Works

The paper provides an efficient method to find all feasible offsets for a given separation in a VLSI channel routing problem in one layer. The prior literature considers this task only for problems with no single-sided nets. When single-sided nets are included, the worst-case solution time increases from Theta(n) to Omega(n^2), where n is the number of nets. But, if the number of columns c is O(n), one can solve the problem in time O(n^{1.5}lg n ), which improves upon a `naive' O(cn) approach. As a corollary of this result, the same time bound suffices to find the optimal offset …

Go to article

Detection And Location Of Pipe Damage By Artificial-Neural-Netprocessed Moire Error Maps, Barry G. Grossman, Frank S. Gonzalez, Joel H. Blatt, Scott Christian Cahall May 1993

Detection And Location Of Pipe Damage By Artificial-Neural-Netprocessed Moire Error Maps, Barry G. Grossman, Frank S. Gonzalez, Joel H. Blatt, Scott Christian Cahall

Electrical Engineering and Computer Science Faculty Publications

A novel automated inspection technique to recognize, locate, and quantify damage is developed. This technique is based on two already existing technologies: video moire metrology and artificial neural networks. Contour maps generated by video moire techniques provide an accurate description of surface structure that can then be automated by means of neutral networks. Artificial neural networks offer an attractive solution to the automated interpretation problem because they can generalize from the learned samples and provide an intelligent response for similar patterns having missing or noisy data. Two dimensional video moire images of pipes with dents of different depths, at several …

Go to article

Light-Emitting Diodes From Partially Conjugated Poly(P-Phenylene Vinylene), C. Zhang, David Braun, A. J. Heeger May 1993

Light-Emitting Diodes From Partially Conjugated Poly(P-Phenylene Vinylene), C. Zhang, David Braun, A. J. Heeger

Electrical Engineering

We report the effect of conversion conditions on the device characteristics of poly(p-phenylene vinylene) (PPV) light-emitting diodes. Both electroluminescence and photoluminescence intensities decrease with increasing degree of conversion. Partial conjugation enhances the electroluminescence intensity and gives an efficiency (with Ca as electron-injecting contact) as high as 0.75% photons per electron, about two orders of magnitude more efficient than from similar devices prepared from fully converted PPV. The results of constant current stress measurements suggest that the partially conjugated PPV diode is relatively stable at room temperature.

Go to article

Effects Of Crosstalk On Fidelity In Page-Oriented Volume Holographic Optical Data Storage, Gregory P. Nordin, P. Asthana May 1993

Effects Of Crosstalk On Fidelity In Page-Oriented Volume Holographic Optical Data Storage, Gregory P. Nordin, P. Asthana

Faculty Publications

Using numerical simulation, we quantitatively examine the effects of cross talk on the recall fidelity of stored binary data in a page-oriented volume holographic memory system. We discuss the trade-off between the signal-to-noise ratio of the reconstructed bits and the optical throughput of the system (i.e., the fraction of the incident beam that is diffracted to the detector plane). We show that significant gains in the signal-to-noise ratio can be achieved with modest decreases in optical throughput in the region where the highest throughput occurs. The magnitude of this trade-off is influenced by both beam degeneracy and coherent recording cross …

Go to article

Inhibition Of Surface-Related Electrical Breakdown Of Long P+-I-N+ Silicon Structures, F. E. Peterkin, P. F. Williams, B. J. Hankla, L. L. Buresh, S. A. Woodward May 1993

Inhibition Of Surface-Related Electrical Breakdown Of Long P+-I-N+ Silicon Structures, F. E. Peterkin, P. F. Williams, B. J. Hankla, L. L. Buresh, S. A. Woodward

P. F. (Paul Frazer) Williams Publications

Semiconductors such as silicon and GaAs appear attractive for use in high voltage devices because of their high bulk dielectric strength. Typically, however, such devices fail at a voltage well below that expected due to a poorly understood, surface-related breakdown process. In this letter we present empirical results which show that such breakdown of long silicon p+-i-n+ devices can be inhibited by the application of weak visible or near-infrared illumination. These results suggest a technique for avoiding surface flashover in practical high voltage devices, and provide information about the physical mechanisms responsible for initiating …

Go to article

Analysis Of Laser Pulse Chirping In Mode-Locked Vertical-Cavity Surface-Emitting Lasers, Wenbin Jiang, Dennis J. Derickson, John E. Bowers May 1993

Analysis Of Laser Pulse Chirping In Mode-Locked Vertical-Cavity Surface-Emitting Lasers, Wenbin Jiang, Dennis J. Derickson, John E. Bowers

Electrical Engineering

Mode-locked vertical cavity lasers have a large cross-sectional area and consequently a large saturation energy and large peak powers. The authors analyze excess optical bandwidth generation in these lasers and find that self-phase modulation due to optical pumping and gain saturation is the dominant factor in inducing laser pulse chirping. The large magnitude of the chirp makes intracavity prism-pair compensation difficult. Adjustment of the cavity length has a major impact on the pulse chirping, as observed experimentally. Proper adjustment can result in a large linear frequency chirp which can be compensated using external pulse compression techniques

Go to article

The Application Of Neural Networks To Optimal Robot Trajectory Planning, Daniel J. Simon May 1993

The Application Of Neural Networks To Optimal Robot Trajectory Planning, Daniel J. Simon

Electrical and Computer Engineering Faculty Publications

Interpolation of minimum jerk robot joint trajectories through an arbitrary number of knots is realized using a hardwired neural network. Minimum jerk joint trajectories are desirable for their similarity to human joint movements and their amenability to accurate tracking. The resultant trajectories are numerical rather than analytic functions of time. This application formulates the interpolation problem as a constrained quadratic minimization problem over a continuous joint angle domain and a discrete time domain. Time is discretized according to the robot controller rate. The neuron outputs define the joint angles (one neuron for each discrete value of time) and the Lagrange …

Go to article

Suboptimal Robot Joint Interpolation Within User-Specified Knot Tolerances, Daniel J. Simon, Can Isik May 1993

Suboptimal Robot Joint Interpolation Within User-Specified Knot Tolerances, Daniel J. Simon, Can Isik

Electrical and Computer Engineering Faculty Publications

Approximation of a desired robot path can be accomplished by interpolating a curve through a sequence of joint-space knots. A smooth interpolated trajectory can be realized by using trigonometric splines. But, sometimes the joint trajectory is not required to exactly pass through the given knots. The knots may rather be centers of tolerances near which the trajectory is required to pass. In this article, we optimize trigonometric splines through a given set of knots subject to user-specified knot tolerances. The contribution of this article is the straightforward way in which intermediate constraints (i.e., knot angles) are incorporated into the parameter …

Go to article

Resolution Enhancement Of Spaceborne Scatterometer Data, David G. Long, Perry J. Hardin, Peter T. Whiting May 1993

Resolution Enhancement Of Spaceborne Scatterometer Data, David G. Long, Perry J. Hardin, Peter T. Whiting

Faculty Publications

A method for generating enhanced resolution radar images of the Earth's surface using spaceborne scatterometry is presented. The technique is based on an image reconstruction technique that takes advantage of the spatial overlap in scatterometer measurements made at different times to provide enhanced imaging resolution. The reconstruction algorithm is described, and the technique is demonstrated using both simulated and actual Seasat-A Scatterometer (SASS) measurements. The technique can also be used with ERS-1 scatterometer data. The SASS-derived images, which have approximately 4-km resolution, illustrate the resolution enhancement capability of the technique, which permits utilization of both historic and contemporary scatterometer data …

Go to article

Spontaneous Coherent Pulsations In Standing-Wave Laser Oscillators: Stability Criteria For Homogeneous Broadening, Pitak Chenkosol, Lee W. Casperson May 1993

Spontaneous Coherent Pulsations In Standing-Wave Laser Oscillators: Stability Criteria For Homogeneous Broadening, Pitak Chenkosol, Lee W. Casperson

Electrical and Computer Engineering Faculty Publications and Presentations

The stability criteria for single-mode standing-wave laser oscillators in the homogeneously broadened limit are reported, and two types of criteria are distinguished. The first type (type 1) corresponds to the minimum value of the threshold parameter for which an infinitesimal perturbation away from steady state grows into an oscillatory solution. A second type (type 2) corresponds to the minimum value of threshold parameter for which large-amplitude oscillations do not decay to the steady-state solution. Undamped pulsations in single-mode homogeneously broadened standing-wave laser oscillators are found to occur at a much higher excitation level than in ring-laser oscillators with homogeneous broadening. …

Go to article

Introduction To Electrical Engineering And The Art Of Problem Solving: Volume I, P. Frazer Williams Apr 1993

Introduction To Electrical Engineering And The Art Of Problem Solving: Volume I, P. Frazer Williams

P. F. (Paul Frazer) Williams Publications

These notes were written to accompany a two-semester introductory course in Electrical Engineering. The primary goal of the course is to introduce you to the art of technical problem solving. Conventional Electrical Engineering curricula, in favorable cases at least, produce engineers who are reasonably adept at operating many of the tools important to the field, such as mathematics and circuit analysis. Often, however, these engineers lack skill in choosing which tools to use and in designing a plan of attack to solve problems which are new to them, even though they have all the information and skills needed to fabricate …

Go to article

Introduction To Electrical Engineering And The Art Of Problem Solving: Volume Ii, P. Frazer Williams Apr 1993

Introduction To Electrical Engineering And The Art Of Problem Solving: Volume Ii, P. Frazer Williams

P. F. (Paul Frazer) Williams Publications

These notes were written to accompany a two-semester introductory course in Electrical Engineering. The primary goal of the course is to introduce you to the art of technical problem solving. Conventional Electrical Engineering curricula, in favorable cases at least, produce engineers who are reasonably adept at operating many of the tools important to the field, such as mathematics and circuit analysis. Often, however, these engineers lack skill in choosing which tools to use and in designing a plan of attack to solve problems which are new to them, even though they have all the information and skills needed to fabricate …

Go to article

Acoustical Boundary Location Through Texture Analysis Of Multibeam Bathymetric Sonar Data, Herb Barad, Andrews B. Martinez, Brian S. Bourgeois, Edit J. Kaminsky Apr 1993

Acoustical Boundary Location Through Texture Analysis Of Multibeam Bathymetric Sonar Data, Herb Barad, Andrews B. Martinez, Brian S. Bourgeois, Edit J. Kaminsky

Electrical Engineering Faculty Publications

Texture analysis is performed on multibeam sonar signal returns discriminated angularity by beamforming. A collection of fourteen texture features are computed via co-occurrence matrices and data reduction is then performed using a principal components transformation. Acoustical boundaries (boundaries between regions with homogeneous acoustical properties) are evident from the features. Results indicate that seafloor bottom characteristics can be extracted from these texture features.

Go to article

Electrostatic Positioning Of Droplets In Turbulent Flows (Lstm 375/Te/93), Nihad E. Daidzic, Adrian Melling Apr 1993

Electrostatic Positioning Of Droplets In Turbulent Flows (Lstm 375/Te/93), Nihad E. Daidzic, Adrian Melling

Aviation Department Publications

Report LSTM 375/TE/93, Lehrstuhl fuer Stroemungsmechanik Universitaet Erlangen-Nuernberg Cauerstr. 4, 8520 Erlangen Germany.

Go to article

Fiber Optic Sensor For The Simultaneous Detection Of Strain And Temperature, Barry G. Grossman, Walid Emil Costandi Mar 1993

Fiber Optic Sensor For The Simultaneous Detection Of Strain And Temperature, Barry G. Grossman, Walid Emil Costandi

Electrical Engineering and Computer Science Faculty Publications

For simple interferometric fiberoptic sensors, the effects of strain and temperature are indistinguishable. This paper addresses that problem by demonstrating a single wavelength, two-mode polarimetric fiberoptic sensor capable of simultaneously measuring temperature and strain. The sensor consists of two interferometers, a polarimetric and a two-mode, formed in a single elliptical core fiber. The interferometers respond with different sensitivities to strain and temperature like simultaneous functions of the two variables. A technique is developed by which the outputs of the interferometers are used simultaneously to measure strain and temperature with rms errors less than 30 με and 1°C. Finally, measurement results …

Go to article

A Systolic Simulation And Transformation System, Ronald I. Greenberg, H.-C. Oh Mar 1993

A Systolic Simulation And Transformation System, Ronald I. Greenberg, H.-C. Oh

Computer Science: Faculty Publications and Other Works

This paper presents a CAD tool, SystSim, to ease the design of systolic systems. Given a high-level, functional description of processors, and a high-level description of their interconnection, SystSim will perform simulations and provide graphical output. SystSim will also perform transformations such as retiming, which eases use of the methodology of Leiserson and Saxe of designing a system with broadcasting and then obtaining a systolic system through retiming.

Go to article

Analysis Of Weighted Fan-Out/Fan-In Volume Holographic Interconnections, Gregory P. Nordin, P. Asthana, B. Keith Jenkins, A. R. Tanguay Mar 1993

Analysis Of Weighted Fan-Out/Fan-In Volume Holographic Interconnections, Gregory P. Nordin, P. Asthana, B. Keith Jenkins, A. R. Tanguay

Faculty Publications

The feasibility of employing volume holographic techniques for the implementation of highly multiplexed weighted fan-out/fan-in interconnections is analyzed on the basis of interconnection fidelity, optical throughput, and complexity of recording schedule or implementation hardware. These feasibility criteria were quantitatively evaluated using the optical beam propagation method to numerically simulate the diffraction characteristics of volume holographic interconnections recorded in a linear holographic material. We find that conventional interconnection architectures (that are based on a single coherent optical source) exhibit a direct trade-off between interconnection fidelity and optical throughput on the one hand, and recording schedule or hardware complexity on the other. …

Go to article

A Fault-Tolerant Optimal Interpolative Net, Daniel J. Simon, Hossny El-Sherief Mar 1993

A Fault-Tolerant Optimal Interpolative Net, Daniel J. Simon, Hossny El-Sherief

Electrical and Computer Engineering Faculty Publications

The optimal interpolative (OI) classification network is extended to include fault tolerance and make the network more robust to the loss of a neuron. The OI Net has the characteristic that the training data are fit with no more neurons than necessary. Fault tolerance further reduces the number of neurons generated during the learning procedure while maintaining the generalization capabilities of the network. The learning algorithm for the fault tolerant OI Net is presented in a recursive format, allowing for relatively short training times. A simulated fault tolerant OI Net is tested on a navigation satellite selective problem.

Go to article

Terrain Classification In Sar Images Using Principal Components Analysis And Neural Networks, Mahmood R. Azimi-Sadjadi, Saleem Ghaloum, R. Zoughi Mar 1993

Terrain Classification In Sar Images Using Principal Components Analysis And Neural Networks, Mahmood R. Azimi-Sadjadi, Saleem Ghaloum, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

The development of a neural network-based classifier for classifying three distinct scenes (urban, park and water) from several polarized SAR images of San Francisco Bay area is discussed. The principal component (PC) scheme or Karhunen-Loeve (KL) transform is used to extract the salient features of the input data, and to reduce the dimensionality of the feature space prior to the application to the neural networks. Employing PC scheme along with polarized images used in this study, led to substantial improvements in the classification rates when compared with previous studies. When a combined polarization architecture is used the classification rate for …

Go to article

Minimizing Channel Density With Movable Terminals, Ronald I. Greenberg, Jau-Der Shih Mar 1993

Minimizing Channel Density With Movable Terminals, Ronald I. Greenberg, Jau-Der Shih

Computer Science: Faculty Publications and Other Works

We give algorithms to minimize density for channels with terminals that are movable subject to certain constraints. The main cases considered are channels with linear order constraints, channels with linear order constraints and separation constraints, channels with movable modules containing fixed terminals, and channels with movable modules and terminals. In each case, previous results for running time and space are improved by a factor of L/lg n and L , respectively, where L is the channel length and n is the number of terminals.

Go to article

Optical Image Analysis Using Fractal Techniques, Samuel Peter Kozaitis, Harold Gregory Andrews, Wesley E. Foor Feb 1993

Optical Image Analysis Using Fractal Techniques, Samuel Peter Kozaitis, Harold Gregory Andrews, Wesley E. Foor

Electrical Engineering and Computer Science Faculty Publications

Using an optical technique, we classified images of natural terrain based on their fractal dimension. We calculated the fractal dimension from an optically generated power spectrum obtained with a magneto-optic spatial light modulator (SLM). By using the fractal dimension to classify images of natural terrain, our post processing was simpler that when a ring-wedge detector was used.

Go to article

Feature-Based Correlation Filters For Object Recognition, Samuel Peter Kozaitis, Wesley E. Foor Feb 1993

Feature-Based Correlation Filters For Object Recognition, Samuel Peter Kozaitis, Wesley E. Foor

Electrical Engineering and Computer Science Faculty Publications

Using an optical correlator, we experimentally evaluated a binary phase-only filter (BPOF) designed to recognize objects not in the training set used to design the filter. Such a filter is essential for recognizing objects from actual sensors. We used an approach that is as descriptive as a BPOF yet robust to object and background variations of an unknown or nonrepeatable type. We generated our filter by comparing the values of spatial frequencies of a training set. Our filter was easily calculated and offered potentially superior performance to other correlation filters.

Go to article

Semiconducting Polymer-Buckminsterfullerene Heterojunctions: Diodes, Photodiodes, And Photovoltaic Cells, N. S. Sariciftci, David Braun, C. Zhang, V. I. Srdanov, A. J. Heeger, G. Stucky, F. Wudl Feb 1993

Semiconducting Polymer-Buckminsterfullerene Heterojunctions: Diodes, Photodiodes, And Photovoltaic Cells, N. S. Sariciftci, David Braun, C. Zhang, V. I. Srdanov, A. J. Heeger, G. Stucky, F. Wudl

Electrical Engineering

The characterization of rectifying heterojunctions (diodes) fabricated from a semiconducting polymer, a soluble derivative of poly(phenylene-vinylene), and buckminsterfullerene, C60, are reported. Rectification ratios in the current versus voltage characteristics exceed 104. When illuminated, the devices exhibit a large photoresponse as a result of photoinduced electron transfer across the heterojunction interface from the semiconducting polymer (donor) onto C60 (acceptor). The photodiode and photovoltaic responses are characterized. Photoinduced electron transfer across the donor-accepted rectifying heterojunction offers potential for photodetector and for solar cell applications.

Go to article

Using Spreadsheets To Teach Problem Solving In A First Year Class, A. John Boye, P. F. Williams, Rodney J. Soukup Feb 1993

Using Spreadsheets To Teach Problem Solving In A First Year Class, A. John Boye, P. F. Williams, Rodney J. Soukup

P. F. (Paul Frazer) Williams Publications

The “problem solving” portion of a two semester first year electrical engineering course is described. This course makes use of personal computers and spreadsheets to try to improve students’ problem solving skills. The goal is to give students a better understanding of engineering concepts and not just mathematical details. In addition to describing the course contents, a brief review of the rationale that was used in selecting the hardware and software used in the course is also given.

Go to article

Explicit Asymmetric Bounds For Robust Stability Of Continuous And Discrete-Time-Systems, Zhiqiang Gao, P J. Antsaklis Feb 1993

Explicit Asymmetric Bounds For Robust Stability Of Continuous And Discrete-Time-Systems, Zhiqiang Gao, P J. Antsaklis

Electrical and Computer Engineering Faculty Publications

The problem of robust stability in linear systems with parametric uncertainties is considered. Explicit stability bounds on uncertain parameters are derived and expressed in terms of linear inequalities for continuous systems and inequalities with quadratic terms for discrete-time systems. Cases where system parameters are nonlinear functions of an uncertainty are also examined

Go to article

Open-Ended Rectangular Waveguide For Nondestructive Thickness Measurement And Variation Detection Of Lossy Dielectric Slabs Backed By A Conducting Plate, Sasan Bakhtiari, Stoyan I. Ganchev, R. Zoughi Feb 1993

Open-Ended Rectangular Waveguide For Nondestructive Thickness Measurement And Variation Detection Of Lossy Dielectric Slabs Backed By A Conducting Plate, Sasan Bakhtiari, Stoyan I. Ganchev, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

Solutions of fields inside a slab of a generally lossy dielectric medium backed by a conducting plate, placed outside a waveguide-fed rectangular aperture, are evoked in the application to the microwave nondestructive thickness measurement of such dielectric slabs. Upon construction of the waveguide terminating admittance expression from its variational form, an inverse problem is then solved to extract the slab thickness from the conductance and susceptance in a recursive manner. A comparison between the experimental and theoretical results showed that the significance of higher order modes is minimal; hence, the dominant mode assumption is, in general, valid to describe the …

Go to article

Fiber Optic Microdeformation Sensors For Smart Structures, Lawrence S. Criscione Jan 1993

Fiber Optic Microdeformation Sensors For Smart Structures, Lawrence S. Criscione

Opportunities for Undergraduate Research Experience Program (OURE)

When optical fibers are stressed, the deformations at the core-cladding interface induce signal attenuation. Because of their durable physical properties (high melting point) optical fibers can be embedded into certain composite materials at the manufacturing stage. Stresses on the composite induces stresses on the embedded fiber. The amount of stress on the fiber, and thus the stress on the composite, can be determined by measuring the attenuation of a signal passing through the fiber. Force was applied to a single mode and a multimode fiber in a microbend inducing plate, and the attenuation this stress created was measured.

Go to article

First Prev Next Last