Engineering Commons^™

Direct Relation Between Fresnel's Interface Reflection Coefficients For The Parallel And Perpendicular Polarizations: Erratum 2, R. M.A. Azzam

Electrical Engineering Faculty Publications

The record is set straight concerning two equations that determine the reflection phase shifts at a single interface from the intensity reflectances forp- and s-polarized light at one angle of incidence. These equations appeared previously in this journal [J. Opt. Soc. Am. 69, 1007 (1979); erratum, J. Opt. Soc. Am. 70, 261 (1980)].

Transfer Function Matrix Identification From Input-Output Frequency Response Data, Zhiqiang Gao, Bruce Tabachnik, Razvan V. Savescu

Electrical and Computer Engineering Faculty Publications

A new formulation of transfer function matrix identification in frequency domain is introduced. It reduces the problem to a simple linear least square problem. It is shown that such a system identification problem is a special case of a matrix interpolation problem and much insight can be obtained by examining its algebraic characteristics. A new approach is proposed to determine the transfer function matrix of a multi-input and multi-output system from the input-output data. It eliminates the common assumption in the literature that the frequency response of the system is given. Its efficiency and practicality …

Simulation Of Communication Systems, William H. Tranter, Kurt Louis Kosbar

Electrical and Computer Engineering Faculty Research & Creative Works

When both a complex system and a complex channel model are encountered, the result is typically a design or analysis problem that cannot be solved using traditional (pencil and paper) mathematical analysis. Computer-aided techniques, which usually involve some level of numerical simulation, can be a very valuable tool in these situations. The purpose of this article is to provide a tutorial review of some of the basic techniques of communication system simulation. The authors consider the basic techniques used to represent signals, generate signals, and model linear systems, nonlinear systems, and time-varying systems within a simulation. They consider the important …

Detection Optimization Of Disbond In Layered Composites With Varying Thicknesses Using An Open-Ended Rectangular Waveguide, Stoyan I. Ganchev, Nasser N. Qaddoumi, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

The detection of air disbond in layered dielectric composite, which is an important practical issue in many industries, is studied both theoretically and experimentally. Sensitivity of disbond detection depends on certain parameters, like the frequency of operation, the distance between the sensor and the first dielectric layer, and the layered composite geometry (conductor backed or terminated by an infinite half-space of air). The impact of all these parameters is investigated theoretically and then verified experimentally.

A Novel Microwave Fatigue Crack Detection Technique Using An Open-Ended Coaxial Line, Nasser N. Qaddoumi, Stoyan I. Ganchev, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

Surface crack detection on metallic structures (aircraft fuselage, turbine blades and nuclear power plant steam generator turbines) is of utmost importance. The use of an open-ended coaxial line for this purpose is very attractive because it offers advantages such as a wide frequency band of operation, small aperture (sensing) area, and excellent sensitivity.

Analysis Of Radiation From An Open-Ended Coaxial Line Into Stratified Dielectrics, Sasan Bakhtiari, Stoyan I. Ganchev, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

Radiation from an open-ended coaxial transmission line into an N-layer dielectric medium is studied in application to nondestructive evaluation of materials. Explicit formulations for two cases of layered media, one terminated into an infinite half-space and the other into a conducting sheet are addressed in general form. In the theoretical derivations it is assumed that only the fundamental TEM mode propagates inside the coaxial line. The terminating admittance of the line is then formulated using the continuity of the power flow across the aperture. The admittance expressions for specific cases of two-layer dielectric composite with generally lossy dielectric properties, and …

Demonstration Of A Novel 3-D Autostereoscopic Display, M. W. Jones, Gregory P. Nordin, S. T. Kowel, J. H. Kulick, R. G. Lindquist, P. J. Nasiatka

Faculty Publications

We report what we believe is the first static implementation of the partial-pixel architecture, which provides a conceptual framework for the construction of real-time three-dimensional displays that are functionally equivalent to holographic stereograms (i.e., the simultaneous display of a series of stereoscopic images). The device is physically realized as a set of amplitude diffraction gratings on a chrome mask that was fabricated by standard photolithographic techniques. The intended three-dimensional object encoded in the display was strikingly visible on readout with an incoherent illumination source.

A Current-Mode Fdnr Circuit Element Using Capacitive Gyrators, Vladimir I. Prodanov, Michael M. Green

Electrical Engineering

A current-mode implementation of a frequency-dependent negative resistance (FDNR) element is presented using a novel capacitive gyrator. This FDNR element lends itself well to the design of low-pass ladder filters and its use will result in a more efficient integrated circuit implementation than filters that simulate floating inductors using resistive gyrators.

Constraint Objects, Divesh Srivastava, Raghu Ramakrishnan, Peter Revesz

CSE Conference and Workshop Papers

We describe the Constraint Object Data Model (CODM), which enhances an object-based data model with existential constraints to naturally represent partially specified information. We present the Constraint Object Query Language (COQL), a declarative, rule-based query language that can be used to infer relationships about and monotonically refine information represented in the CODM. COQL has a model-theoretic and an equivalent fixed-point semantics, based on the notions of constraint entailment and "proofs in all possible worlds." We also provide a novel polynomial-time algorithm for quantifier elimination for set-order constraints, a restricted class of set constraints that uses membership of subset-equal.

Fluttering Fountains: Stability Criteria, Lee W. Casperson

Electrical and Computer Engineering Faculty Publications and Presentations

The fluttering oscillations that have long been seen in falling sheets of water have recently been subjected to detailed theoretical analysis. In this study stability criteria for these oscillations are derived and discussed. These criteria provide insight into the physical mechanisms of the instability and may be employed in the design of fluttering waterfall systems.

The Effects Of Channel Curvature And Protusion Height On Nucleate Boiling And The Critical Heat Flux Of A Simulated Electronic Chip, John E. Leland

Office for Research Publications and Presentations

The quest for higher power yet smaller electronics has given rise to the need for very effective cooling of these electronics. Because one of the foremost problems in electronics cooling is achieving high heat flux cooling within small packages while expending minimal pumping power, one focus of this study was to investigate the effects of channel curvature on the CHF. Experimental data were obtained for flow rates of 1-7 m/s, subcoolings of 5-35"C, and radii of curvature of 25.4 and 50.8 mm. A correlation was obtained for these data which provided an excellent fit.

One condition that has been ignored …

High Resolution Liquid Crystal Phase Grating Formed By Fringing Fields From Interdigitated Electrodes, Gregory P. Nordin, M. Friends, J. M. Jarem, S. T. Kowel, J. H. Kulick, T. Leslie, R. G. Lindquist

Faculty Publications

We report the formation of thin anisotropic phase gratings in a nematic liquid-crystalline film by use of lateral (fringing) electric fields induced by transparent interdigitated electrodes. These gratings yield high diffraction efficiency (>30%) with a strong dependence on the readout beam incidence angle. In addition, the formation of a defect wall is observed that has a significant effect on the diffraction properties of the phase grating.

Electrical And Crystallographic Characterization Of Cdte Grown By The Vapor Transport Method, Jack L. Boone, Gene Cantwell, W. C. Harsch, J. E. Thomas, B. A. Foreman

Electrical and Computer Engineering Faculty Research & Creative Works

Crystallographic and electrical characterization techniques were performed on CdTe single crystal samples grown by the sublimation and physical vapor transport (SPVT) technique. The SPVT growth process described here has resulted in the routine growth of 45-50 mm diameter, 250-300 g boules of single crystal CdTe. As-grown material is p-type in the 5-10 ω cm range. Etch pit densities (EPD) are nominally 7x104 cm-2 along the [111] growth direction and 3x104 cm-2 along the [111] direction. X-ray full width at half maximum (FWHM) on recent samples is 8.6 arc sec compared to 8.5 arc sec theoretical. The as-grown p-type material displays …

Donor Complex Formation Due To A High-Dose Ge Implant Into Si, Ashawant Gupta, M. Mahmudur Rahman, Jianmin Qiao, Cary Y. Yang

Electrical and Computer Engineering

To investigate boron deactivation and/or donor complex formation due to a high‐dose Ge and C implantation and the subsequent solid phase epitaxy, SiGe and SiGeC layers were fabricated and characterized. Cross‐sectional transmission electron microscopy indicated that the SiGe layer with a peak Ge concentration of 5 at. % was strained; whereas, for higher concentrations, stacking faults were observed from the surface to the projected range of the Ge as a result of strain relaxation. Photoluminescence (PL) results were found to be consistent with dopant deactivation due to Ge implantation and the subsequent solid phase epitaxial growth of the amorphous layer. …

Optimal Kernel Development For Real-Time Communications, Monica G. Beltran

FIU Electronic Theses and Dissertations

The purpose of this research is to develop an optimal kernel which would be used in a real-time engineering and communications system. Since the application is a real-time system, relevant real-time issues are studied in conjunction with kernel related issues. The emphasis of the research is the development of a kernel which would not only adhere to the criteria of a real-time environment, namely determinism and performance, but also provide the flexibility and portability associated with non-real-time environments. The essence of the research is to study how the features found in non-real-time systems could be applied to the real-time system …

Interferometric Determination Of The Quadratic Electro-Optic Coefficient Of Nitrobenzene, Harshad P. Sardesai, William C. Nunnally, P. F. Williams

P. F. (Paul Frazer) Williams Publications

An interferometric method that was used to measure the electro-optic s₁₁ coefficient of nitrobenzene is presented. The method uses a Mach-Zehnder interferometer arrangement that produces a finite fringe interferogram. A nitrobenzene Kerr cell is placed in one arm of the interferometer and a pulsed high voltage is applied to the two rectangular electrodes. The voltage application causes the fringe image to shift in time, and this fringe shift is measured by a streak camera that streaks the fringe image across a slit. The streak start time is chosen before the application of the voltage pulse and ends after the …

Basic Resonant Topologies For Switching Power Supplies, Zacharias K. Vachaparambil

Department of Electrical and Computer Engineering Technical Reports

The objective of this thesis is to study the basic resonant converter topologies for switching power supplies and to compare their performance under different operating conditions. The series and parallel resonant converters are analyzed in detail. The analysis uses the state plane method, which gives a good insight of the operation of the converter. It is found that these converters have more desirable characteristics when operated at a frequency above the resonant frequency rather than below it. Analytical results are verified by sinlulation and experiment.

A Powerful And Computationally Efficient Algorithm For Transmission Loss Calculation, Anoop Nanda, David V. Uy, J. Nanda, E. Khan, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

This paper deals with the formulation of transmission loss P_L of a power system through a set of new coefficients (A coefficients) which are extremely efficient, exact and robust and suitable for real time application. Results on a few IEEE test systems are exciting and encouraging. They demonstrate that these A coefficients faithfully represent the system loss, are extremely robust and need not be re-evaluated for changes in the system loading conditions either for evaluation of system loss or cost of generation for economic load dispatch.

Characterization Of Electromagnetically Coupled Superquadric Loop Antennas For Mobile Communications Applications, Michael A. Jensen, Yahya Rahmat-Samii

Faculty Publications

Analysis of two mutually coupled loop antennas with arbitrary relative orientation and position and possibly different geometries is presented. The antennas are represented by generalised superquadric curves, which include circular, elliptical, and rectangular loop geometries, and they may be located either in a homogeneous region or next to an infinite ground plane. A Galerkin-type moment method with piecewise sinusoidal subsectional basis and weighting functions is used. Special consideration is given to implement the solution using curved wire segments instead of the commonly employed linear segments to improve computational efficiency. This very general computational tool is used to investigate the behaviour …

Determination Of Density Of Trap States At Y2O3-Stabilized Zro2/Si Interface Of Yba2Cu3O7-Δ/Y2O3-Stabilized Zro2/Si Capacitors, Jianmin Qiao, Kuohsu Wang, Cary Y. Yang

Electrical and Computer Engineering

Yba₂Cu₃O_7-δ/yttria‐stabilized zirconia (YSZ)/silicon superconductor‐insulator‐semiconductor capacitors are characterized with current‐voltage and capacitance‐voltage (C‐V) measurements at different temperatures between 223 and 80 K. As a result of ‘‘freezing’’ of mobile ions in YSZ, effects of trapped charge at the YSZ/Si interface dominate the device electrical properties at superconducting temperatures. Density of interface states and its temperature dependence are determined using a modified high frequency C‐V method, in which the temperature dependences of band gap, Fermi level, and active dopant and intrinsic carrier concentrations are considered. At superconducting temperatures, e.g., 80 K, the interface state density within …

An Artifically Intelligent Word Recognizer To Control Appliances And Switches: The Home That Listens To Your Every Command, Joseph Bauer, Rick Steurer

Opportunities for Undergraduate Research Experience Program (OURE)

The most natural and informal means of communication and control is speech communication. Therefore, it also goes to say that control of home appliances, stereo, computer, and heating thermostat to name a few will naturally tend to this form of control.

A word recognition home controller was designed, constructed, and tested successfully. This paper will discuss the low-cost overall design, implementation, and results of a presently constructed and working "home controller." The results of this successful project in voice control are very promising and agree with the original hypothesis: A home that listens to your command is very much a …

A Design Methodology For A Multi-Fpga Based Rapid Prototyping System, William Eatherton

Opportunities for Undergraduate Research Experience Program (OURE)

The movement of universities from university-created digital design software to commercial design tools has resulted in a need for a revision of existing rapid prototyping systems. The rapid prototyping system created at North Carolina State University (NCSU) and centered on a FPGA-based board (called the Anyboard), was revised to use Mentor Graphics, a sophisticated industrial EDA tool, rather than board specific software. To provide a guide for future students at UMR and other schools using the Anyboard, an example design was created with Mentor Graphics to route data between a PC bus, SRAMs, and an arithmetic logic unit.

Rank Conditioned Rank Selection Filters For Signal Restoration, Russell C. Hardie, Kenneth E. Barner

Electrical and Computer Engineering Faculty Publications

A class of nonlinear filters called rank conditioned rank selection (RCRS) filters is developed and analyzed in this paper. The RCRS filters are developed within the general framework of rank selection(RS) filters, which are filters constrained to output an order statistic from the observation set. Many previously proposed rank order based filters can be formulated as RS filters. The only difference between such filters is in the information used in deciding which order statistic to output. The information used by RCRS filters is the ranks of selected input samples, hence the name rank conditioned rank selection filters. The number of …

Vegetation Studies Of The Amazon Basin Using Enhanced Resolution Seasat Scatterometer Data, David G. Long, Perry J. Hardin, Peter T. Whiting

Faculty Publications

The Seasat-A scatterometer (SASS) was designed to measure the near-surface wind field over the ocean by inferring the wind from measurements of the surface radar backscatter. While backscatter measurements were also made over land, they have been primarily used for the calibration of the instrument. This has been due in part to the low resolution of the scatterometer measurements (nominally 50 km). In a separate paper the present authors introduced a new method for generating enhanced resolution radar measurements of the Earth's surface using spaceborne scatterometry. In the present paper, the method is used with SASS data to study vegetation …

Microwave Noncontact Examination Of Disbond And Thickness Variation In Stratified Composite Media, Sasan Bakhtiari, Nasser N. Qaddoumi, Stoyan I. Ganchev, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

Numerical and experimental results of a microwave noncontact, nondestructive detection and evaluation of disbonds and thickness variations in stratified composite media are presented. The aperture admittance characteristics of a flange mounted rectangular waveguide radiating into a layered, generally lossy dielectric media backed or unbacked by a conducting sheet is modeled. The theoretical implementation is based on a Fourier transform boundary matching technique to construct the field components in each medium, coupled with a stationary form of the terminating aperture admittance of the waveguide. The model can serve as a reliable test bed for real-time examination of layered composite media. Experimental …

Ultrafast Dynamics In Field-Enhanced Saturate Absorbers, J. R. Karin, R. J. Helkey, Dennis J. Derickson, R. Nagarajan, D. S. Allin, J. E. Bowers, R. L. Thornton

Electrical Engineering

Absorption recovery dynamics of GaAs/AlGaAs field-enhanced waveguide saturable absorbers are studied by pump-probe differential transmission measurements. We compare the response of bulk and single quantum well absorbers at different reverse bias levels and pump powers, and find an ultrafast transient in the response, followed by a slower rise before the final recovery. The absorption fully recovers after a few picoseconds, which is an important result for mode-locked lasers.

Epistemic Decision Theory Applied To Multiple-Target Tracking, T. K. Moon, Scott E. Budge, W. C. Stirling, J. B. Thompson

Electrical and Computer Engineering Faculty Publications

A decision philosophy that seeks the avoidance of error by trading off belief of truth and value of information is applied to the problem of recognizing tracks from multiple targets (MTT). A successful MTT methodology should be robust in that its performance degrades gracefully as the conditions of the collection become less favorable to optimal operation. By stressing the avoidance, rather than the explicit minimization, of error, the authors obtain a decision rule for trajectory-data association that does not require the resolution of all conflicting hypotheses when the database does not contain sufficient information to do so reliably. This rule, …

Electromagnetic Characteristics Of Superquadric Wire Loop Antennas, Michael A. Jensen, Yahya Rahmat-Samii

Faculty Publications

The analysis of antenna configurations in the form of a generalized superquadric loop, which includes circular, elliptical and rectangular loop geometries, is presented in this paper. Use of a Galerkin form of the moment method with piecewise sinusoidal subsectional basis and testing functions provides rapid numerical convergence and accurate representation of the antenna current. A convenient parametric representation for the superquadric curve is developed to allow a subsectional formulation using curved wire segments, rather than the commonly employed piecewise linear segments, to construct the geometry. Both magnetic frill and delta gap source models are implemented to allow a detailed study …

Classification Using Set-Valued Kalman Filtering And Levi's Decision Theory, T.K. Moon, Scott E. Budge

Electrical and Computer Engineering Faculty Publications

We consider the problem of using Levi's expected epistemic decision theory for classification when the hypotheses are of different informational values, conditioned on convex sets obtained from a set-valued Kalman filter. The background of epistemic utility decision theory with convex probabilities is outlined and a brief introduction to set-valued estimation is given. The decision theory is applied to a classifier in a multiple-target tracking scenario. A new probability density, appropriate for classification using the ratio of intensities, is introduced.

Epistemic Decision Theory Applied To Multiple-Target Tracking, Wynn C. Stirling, T. K. Moon, S. E. Budge, J. B. Thompson

Faculty Publications

A decision philosophy that seeks the avoidance of error by trading off belief of truth and value of information is applied to the problem of recognizing tracks from multiple targets (MTT). A successful MTT methodology should be robust in that its performance degrades gracefully as the conditions of the collection become less favorable to optimal operation. By stressing the avoidance, rather than the explicit minimization, of error, the authors obtain a decision rule for trajectory-data association that does not require the resolution of all conflicting hypotheses when the database does not contain sufficient information to do so reliably. This rule, …