Engineering Commons^™

Identification And Robust Control Of Smart Structures Using Artificial Neural Networks, R. Damle, R. Lashlee, Vittal S. Rao, Frank J. Kern

Electrical and Computer Engineering Faculty Research & Creative Works

This paper describes an integrated approach to design and implement robust controllers for smart structures. To demonstrate this procedure, we have designed and fabricated a structural test article incorporating shape memory alloy (SMA) actuators, strain gauge sensors, signal-processing circuits and digital controllers with flexible structures. A neural-network-based structural identification method to determine a state space model of the system from its experimental input/output data is presented. To reduce the learning time required to train a neural network significantly, we have developed an accelerated adaptive learning-rate algorithm. The mathematical model derived using neural networks is compared with models obtained by more …

A Contactless Method For Measuring The Bulk Resistance Of Ii-Vi Compound Semiconductors, Edward D. Wheeler, Jack L. Boone, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

A radio frequency measurement technique for measuring the bulk resistivity of II-VI compound semiconductors is described. Wafers of n-type CdS are used to demonstrate the technique. An equivalent circuit model is introduced which predicts a frequency dependence for the CdS wafer impedance which agrees well with the experiment. The model assumes a broad distribution of relaxation times associated with the polarization. The radio frequency method gives values for the resistivity within 15% of four point probe measurements for the lower resistivity wafers, and within 5% for the higher resistivity wafers.

Performance Of Bandlimited Gaussian Noise As A Spreading Code In Awgn And Single Tone Interference Channels, Tze-Yu Chu, Kurt Louis Kosbar

Electrical and Computer Engineering Faculty Research & Creative Works

This paper examines the bit error rate (BER) of a direct sequence spread spectrum (SS) system that uses bandlimited white Gaussian noise (BLWGN) as a spreading code. The performance of this "bandlimited-SS" system is examined in both additive white Gaussian noise (AWGN) and single tone jamming environments. The BLWGN spreading code is inferior to conventional codes in AWGN channels, but is more robust when a narrow band interference signal is present.

Two-Dimensional Current Transient And Trap-State Filling Of Amorphous Silicon Thin-Film Transistors, J. S. Huang, Cheng-Hsiao Wu

Electrical and Computer Engineering Faculty Research & Creative Works

Two-dimensional simulations of amorphous silicon thin-film transistors are presented for the case when source-drain voltage is turned on long before gate voltage is turned on. Discrepancies between these results and the one-dimensional results of M. F. Willums, M. Hack, P. G. LeComber, and J. G. Shaw [MRS Symp. Proc. 258, 985 (1992)] are discussed. Valid reasons for drain current decay are provided, and occupation dynamics for the trap states are shown in order to distinguish these from the one-dimensional results of C. van Berkel, J. R. Hughes, and M. J. Powell [J. Appl. Phys. 66, 4488 (1989)] where …

Correlative Tracking Of Pseudo-Noise Codes Using A Phase Shifted Reference, Kurt Louis Kosbar, Hettiachchi Upul Gunawardana

Electrical and Computer Engineering Faculty Research & Creative Works

This work investigates a first-order correlation loop for tracking pseudo-noise (PN) codes. The local reference is produced by a PN sequence generator in series with a Hilbert transform filter. The tracking performance of this non-linear loop is compared with conventional early-late delay-lock loops (ELDLL). Using a conservative definition of bandwidth, the new loop was found to be superior at moderate to low signal-to-noise ratios (SNR). Another advantage of the new structure is that it has a very large (arguably infinite) lock range.

A Novel Microwave Method For Detection Of Long Surface Cracks In Metals, Chin-Yung Yeh, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

A novel microwave technique for detecting long surface cracks in metals is described. This technique utilizes an open-ended waveguide to probe the surface of a metal. In the absence of a crack the metal surface is seen as a relatively good short-circuit load. However, in the presence of a crack higher order modes are generated which in turn change the reflection properties at the waveguide aperture. This change brings about a perturbation in the standing wave characteristics which is then probed by a diode detector. The experimental and theoretical foundations of this technique are given, along with several examples. It …

Identifying And Quantifying Printed Circuit Board Inductance, Todd H. Hubing, Thomas Van Doren, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

The concepts of inductance and partial inductance play a key role in printed circuit board (PCB) modeling. The inductance of the signal path is an important parameter in high-speed signal integrity calculations. Delta_I noise modeling, crosstalk calculations, and common-mode source identification all rely heavily on accurate estimations of the partial inductance associated with traces, vias, and signal return paths on printed circuit boards. The paper begins by identifying and quantifying the parameters that affect the inductance of typical PCB geometries. Closed-form equations are provided for estimating the partial inductances of simple trace, via, and ground plane configurations. Finally, the issue …

Common Mode Currents Induced On Wires Attached To Multilayer Printed Wire Boards With Segmented Ground Planes, R. Lee Hill, Thomas Van Doren, Todd H. Hubing, James L. Drewniak, Franz Gisn

Electrical and Computer Engineering Faculty Research & Creative Works

An investigation has been undertaken to further study the fundamental mechanisms responsible for inducing high frequency common mode currents on wires attached to multilayer printed wire boards (PWBs). Previous work reported in the EMC literature has demonstrated that the presence of unintended common mode currents on the external cables of electronic equipment is often the primary source of radiated EMI at frequencies above 30 MHz. In an attempt to reduce the magnitude of these currents to yield `quieter' electronic products, many EMC engineers have implemented segmented or `gapped' ground plane geometries in mulilayer PWB designs. The objective of this study …

Investigation Of Fundamental Mechanisms Of Common-Mode Radiation From Printed Circuit Boards With Attached Cables, James L. Drewniak, Todd H. Hubing, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

Fundamental mechanisms leading to common-mode radiation from printed circuit boards with attached cables have been studied. Two primary mechanisms have been identified, one associated with a differential-mode voltage that results in a common-mode current on an attached cable, and another associated with a differential-mode current that results in a common-mode current on the cable. The two mechanisms are demonstrated through numerical and experimental results.

The Multirate Method For Simulation Of Power System Dynamics, J. G. Chen, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, the multirate method is introduced to analyse power system behavior for systems with widely varying time constants. Estimates for computational speed-up are derived based on a linear system approach. The method is applied to a small power system example and the results, both in terms of accuracy and computation time, are compared to traditional simulation methods

Modeling Power Bus Decoupling On Multilayer Printed Circuit Boards, James L. Drewniak, Todd H. Hubing, Thomas Van Doren, P. Baudendistal

Electrical and Computer Engineering Faculty Research & Creative Works

Power bus decoupling designs on multilayer printed circuit boards must adequately account for the power bus interplane capacitance and its consequences for the design. Lumped element models for a power bus on a multilayer printed circuit board where an appreciable or entire portion of a layer is devoted to power and ground have been developed. The models are applicable below the distributed resonances of the board. Analytical, circuit simulation, and experimental studies have been conducted to test the models, investigate the effects of the distributed interplane capacitance of the power bus, and the effect of interconnect inductance associated with surface-mount …

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 …

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 …

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.

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.

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 …

On Fault Modeling And Testing Of Content-Addressable Memories, Waleed K. Al-Assadi, A. P. Jayasumana, Y. K. Malaiya

Electrical and Computer Engineering Faculty Research & Creative Works

Associative or content addressable memories can be used for many computing applications. This paper discusses fault modeling for the content addressable memory (CAM) chips. Detailed examination of a single CAM cell is presented. A functional fault model for a CAM architecture executing exact match derived from the single cell model is presented. An efficient testing strategy can be derived using the proposed fault model

Neural Network Enhancement Of The Los Alamos Force Deployment Estimator, Bobby Turner, Donald C. Wunsch

Electrical and Computer Engineering Faculty Research & Creative Works

The Force Deployment Estimator (FDE) is a decision support system. It allocates transportation resources given inputs such as forces to be deployed and their desired arrival times. Other inputs are assumptions about conditions that affect performance: carrier start time, node capacity, sustainment shipping time, bulk sustainment per day, ammo sustainment per day, unit start time, carrier service time, carrier round trip time, and carrier reassignment time. Outputs include the mean and standard deviation of estimated unit arrival times versus goal times, and data files for post-processing. However, when a goal time is not met, the simulator gives no explanation of …

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.

Voltage Collapse. An Engineering Challenge, Mariesa Crow, Bernard C. Lesieutre

Electrical and Computer Engineering Faculty Research & Creative Works

Voltage collapse is characterised by a loss of control of the voltage levels in a power system. Although all of the precise mechanisms that affect voltage collapse have not yet been identified, voltage instabilities are known to occur when the power system is operating under a stressed state. The authors discuss voltage collapse and its relationship with the point of maximum power transfer and how voltage collapse can be better predicted

Neural Network Diagnosis Of Malignant Melanoma From Color Images, Fikret Erçal, Hsi-Chieh Lee, William V. Stoecker, Randy Hays Moss, Anurag Chawla

Computer Science Faculty Research & Creative Works

Malignant melanoma is the deadliest form of all skin cancers. Approximately 32,000 new cases of malignant melanoma were diagnosed in 1991 in the United States, with approximately 80% of patients expected to survive 5 years. Fortunately, if detected early, even malignant melanoma may be treated successfully, Thus, in recent years, there has been rising interest in the automated detection and diagnosis of skin cancer, particularly malignant melanoma. Here, the authors present a novel neural network approach for the automated separation of melanoma from 3 benign categories of tumors which exhibit melanoma-like characteristics. The approach uses discriminant features, based on tumor …

A Stochastic One-Dimensional Image Model Based On Occluding Object Images, John A. Stuller

Electrical and Computer Engineering Faculty Research & Creative Works

This Paper Provides New Insights into the Formation of One-Dimensional (Line-Scan) Image Autocorrelation Functions. We Model a Line Scan as a Composition of Individual Object-Images that Have Random Positions, Widths and Intensities and that Occlude One Another. We Derive the Autocorrelation Function of This Model as a Function of Object-Image Width and Intensity Distributions. We Show that Any Assumption Regarding the Form of the Autocorrelation Function Places a Constraint on Object-Image Width and Intensity Distributions and We Derive the Object-Image Width Distribution Associated with the Widely Used Symmetric-Exponential Autocovariance Model.

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

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 …

The Adaptive Control Of Smart Structures Using Neural Networks, Vittal Rao, Rajendra Damle, Chris Tebbe, Frank J. Kern

Electrical and Computer Engineering Faculty Research & Creative Works

The application of adaptive control algorithms for vibration suppression of smart structures is investigated in this paper. An accurate mathematical representation is not required in this approach. The controller adapts to the parameter variations of the structural system by updating the controller gains. When the desired performance of an unknown plant with respect to an input signal can be specified in the form of a linear or a non-linear differential equation, stable control can be achieved using model-reference adaptive control (MRAC) techniques. The conventional MRAC techniques have been successfully implemented on a smart-structure test article resulting in perfect model following. …

Data-Feedthrough Faults In Circuits Using Unclocked Storage Elements, Waleed K. Al-Assadi, D. Lu, A. P. Jayasumana, Y. K. Malaiya, C. Q. Tong

Electrical and Computer Engineering Faculty Research & Creative Works

Some faults in storage elements (SEs) do not manifest as stuck-at-0/1 faults. These include data-feedthrough faults that cause the SE cell to exhibit combinational behaviour. The authors investigate the implications of such faults on the behaviour of circuits using unclocked SEs. It is shown that effects of data-feedthrough faults at the behavioural level are different from those due to stuck-at faults, and therefore tests generated for the latter may be inadequate