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Articles 1 - 25 of 25
Full-Text Articles in Engineering
A Contactless Method For Measuring The Bulk Resistance Of Ii-Vi Compound Semiconductors, Edward D. Wheeler, Jack L. Boone, James L. Drewniak
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
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
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
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
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
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 …
Modeling Power Bus Decoupling On Multilayer Printed Circuit Boards, James L. Drewniak, Todd H. Hubing, Thomas Van Doren, P. Baudendistal
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 …
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
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 …
The Multirate Method For Simulation Of Power System Dynamics, J. G. Chen, Mariesa Crow
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
Investigation Of Fundamental Mechanisms Of Common-Mode Radiation From Printed Circuit Boards With Attached Cables, James L. Drewniak, Todd H. Hubing, Thomas Van Doren
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.
Simulation Of Communication Systems, William H. Tranter, Kurt Louis Kosbar
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
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.
Analysis Of Radiation From An Open-Ended Coaxial Line Into Stratified Dielectrics, Sasan Bakhtiari, Stoyan I. Ganchev, R. Zoughi
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 …
A Novel Microwave Fatigue Crack Detection Technique Using An Open-Ended Coaxial Line, Nasser N. Qaddoumi, Stoyan I. Ganchev, R. Zoughi
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.
A Powerful And Computationally Efficient Algorithm For Transmission Loss Calculation, Anoop Nanda, David V. Uy, J. Nanda, E. Khan, Mariesa Crow
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 PL 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.
Microwave Noncontact Examination Of Disbond And Thickness Variation In Stratified Composite Media, Sasan Bakhtiari, Nasser N. Qaddoumi, Stoyan I. Ganchev, R. Zoughi
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 …
A Stochastic One-Dimensional Image Model Based On Occluding Object Images, John A. Stuller
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.
Microwave Diagnosis Of Rubber Compounds, Stoyan I. Ganchev, J. Bhattacharyya, Sasan Bakhtiari, Nasser N. Qaddoumi, Deborah Brandenburg, R. Zoughi
Microwave Diagnosis Of Rubber Compounds, Stoyan I. Ganchev, J. Bhattacharyya, Sasan Bakhtiari, Nasser N. Qaddoumi, Deborah Brandenburg, R. Zoughi
Electrical and Computer Engineering Faculty Research & Creative Works
The results of a study investigating the dielectric properties of rubber compounds and their constituents in the frequency range of 5 to 24 GHz are presented. A completely filled short circuited waveguide technique was used to conduct these dielectric measurements. The influence of carbon black content in rubber was investigated for carefully prepared rubber samples. The results showed that for all frequencies, the dielectric constant increases as a function of increasing carbon black content. The variation of dielectric constant values decreases as frequency increases. The presence of curatives in uncured rubber samples was also detected, which indicates the sensitivity of …
On Fault Modeling And Testing Of Content-Addressable Memories, Waleed K. Al-Assadi, A. P. Jayasumana, Y. K. Malaiya
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
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 …
Data-Feedthrough Faults In Circuits Using Unclocked Storage Elements, Waleed K. Al-Assadi, D. Lu, A. P. Jayasumana, Y. K. Malaiya, C. Q. Tong
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
The Role Of Component Packaging In System Electromagnetic Compatibility, Todd H. Hubing
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
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
A Modular Approach To Numerical Em Modeling, Todd H. Hubing
A Modular Approach To Numerical Em Modeling, Todd H. Hubing
Electrical and Computer Engineering Faculty Research & Creative Works
Discusses the components of numerical EM modelling codes. The authors go on to discuss a modular approach to EM software development which would allow developers to focus on one component at a time. The modular approach relies on standard format input and output files for each component (or module) of the code
Order-Recursive Fir Smoothers, Jenq Tay Yuan, John A. Stuller
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