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Electrical and Computer Engineering Faculty Research & Creative Works

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Full-Text Articles in Engineering

Simulation And Measurement For Decoupling On Multilayer Pcb Dc Power Buses, Hao Shi, F. Yuan, Fei Sha, James L. Drewniak, Todd H. Hubing, Thomas Van Doren Aug 1996

Simulation And Measurement For Decoupling On Multilayer Pcb Dc Power Buses, Hao Shi, F. Yuan, Fei Sha, James L. Drewniak, Todd H. Hubing, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

DC power bus decoupling of a multi-layer PCB is modeled by a combination of a lumped circuit model at low frequencies ( < 200 MHz), and a mixed-potential integral equation approach at high frequencies. In order to determine the lumped parameters of via interconnects, an effective procedure using a network analyzer has been developed to characterize the trace/via inductances/resistances. For an 8 inch × 10 inch ten-layer test board used in this study, the simulations show good agreement with the measurement. This method can lead to new design strategies of decoupling for multilayer PCB power buses.

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A Comparison Of An Fdtd Thin-Slot Algorithm And Method Of Moments For Modeling Slots Near Corners, Kuang-Ping Ma, James L. Drewniak, Todd H. Hubing, Thomas Van Doren Aug 1996

A Comparison Of An Fdtd Thin-Slot Algorithm And Method Of Moments For Modeling Slots Near Corners, Kuang-Ping Ma, James L. Drewniak, Todd H. Hubing, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

Subcellular FDTD algorithms for modeling thin slots in conductors have previously been developed. One algorithm that is based on a quasi-static approximation has been shown to agree well with experimental results for thin slots in planes. This FDTD thin-slot algorithm is compared herein with moment method results for thin slots near corners.

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Experimental And Numerical Investigations Of Fundamental Radiation Mechanisms In Pcb Designs With Attached Cables, David M. Hockanson, Cheung-Wei Lam, James L. Drewniak, Todd H. Hubing, Thomas Van Doren Aug 1996

Experimental And Numerical Investigations Of Fundamental Radiation Mechanisms In Pcb Designs With Attached Cables, David M. Hockanson, Cheung-Wei Lam, James L. Drewniak, Todd H. Hubing, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

Stacked-card and modules-on-backplane printed circuit board geometries are advantageous for conserving real-estate in many designs. Unfortunately, at high frequencies, current-driven noise sources may develop at the connector. The connector may effectively drive the daughter-card against the motherboard and attached cables, resulting in common-mode radiation. The connector geometry can be modified to reduce the level of the effective noise-source when high frequencies are routed between the mother-board and daughter-card. Current speeds and PCB board sizes result in geometries that are of significant dimensions in terms of wavelength at the upper frequency end of the signal spectrum. Geometries are then of sufficient …

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A Multi-Institutional Cooperative Approach To Power Engineering Education, Anil Pahwa, Kraig J. Olejniczak, S. D. Sughoff, Shelli K. Starrett, Mariesa Crow Aug 1996

A Multi-Institutional Cooperative Approach To Power Engineering Education, Anil Pahwa, Kraig J. Olejniczak, S. D. Sughoff, Shelli K. Starrett, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

This paper describes the multi-institutional cooperative effort between the University of Missouri--Rolla, Kansas State University, and the University of Arkansas to develop two new courses in flexible power system control.

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An Expert System Approach To Emc Modeling, Todd H. Hubing, James L. Drewniak, Thomas Van Doren, Navin Kashyap Aug 1996

An Expert System Approach To Emc Modeling, Todd H. Hubing, James L. Drewniak, Thomas Van Doren, Navin Kashyap

Electrical and Computer Engineering Faculty Research & Creative Works

Existing computer software for EMC analysis can be divided into three categories. Analytical modeling codes employ closed form expressions to solve problems of general interest to EMC engineers or circuit designers. Numerical modeling codes use numerical techniques to solve Maxwell's equations subject to specific boundary conditions. EMC rule checkers search a design for features that violate basic EMC design guidelines. This paper outlines the relative advantages and limitations of each of these three approaches and describes an expert system EMC modeling approach. The new approach combines analytical models, numerical models, and EMC rule-checking in order to evaluate designs in much …

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Measurement Parameter Optimization For Surface Crack Detection In Metals Using An Open-Ended Waveguide Probe, R. Zoughi, Stoyan I. Ganchev, Christian J. Huber Jun 1996

Measurement Parameter Optimization For Surface Crack Detection In Metals Using An Open-Ended Waveguide Probe, R. Zoughi, Stoyan I. Ganchev, Christian J. Huber

Electrical and Computer Engineering Faculty Research & Creative Works

Fatigue and stress induced surface crack detection in metals is an important practical issue. A newly developed microwave inspection approach, using an open-ended rectangular waveguide, has proved to be an effective tool for detecting such cracks. This novel microwave approach overcomes some of the limitations associated with the standard detection methods for surface crack detection. In addition, this approach is applicable to exposed, filled (with a dielectric such as dirt, rust, etc.) and cracks under dielectric coatings such as paint. This paper presents the basic foundation of this surface crack detection methodology along with the ways by which measurement parameters …

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A Fuzzy Logic Based Approach To Direct Load Control, K. Bhattacharyya, Mariesa Crow May 1996

A Fuzzy Logic Based Approach To Direct Load Control, K. Bhattacharyya, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

Demand side management programs are strategies designed to alter the shape of the load curve. In order to successfully implement such a strategy, customer acceptance of the program is vital. It is thus desirable to design a model for direct load control which may accommodate customer preferences. This paper presents a methodology for optimizing both customer satisfaction and utility unit commitment savings, based on a fuzzy load model for the direct load control of appliances

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Dispersion Comparison For Dsi- And Tensor-Based Nonorthogonal Fdtd, Hao Shi, James L. Drewniak May 1996

Dispersion Comparison For Dsi- And Tensor-Based Nonorthogonal Fdtd, Hao Shi, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

An explicit formulation of the finite-difference time-domain-discrete surface integral (FDTD-DSI) technique has allowed a rigorous study of numerical dispersion for the method. The study shows that the DSI- and tensor-based FDTD methods do not have the same numerical dispersion relation. It also clarifies the recently reported discrepancies in the dispersion relation between the two approaches. This study also shows that the tensor-based FDTD algorithm exhibits better dispersion properties for a two-dimensional uniformly skewed mesh.

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The Multirate Simulation Of Facts Devices In Power System Dynamics, J. G. Chen, Mariesa Crow Feb 1996

The Multirate Simulation Of Facts Devices In Power System Dynamics, J. G. Chen, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, the multirate method is applied to the problem of simulating the dynamics of a power system which contains fast components such as induction machine loads and FACTS devices. Results concerning the numerical stability and accuracy of the multirate method are presented. Implementation concerns are also addressed by studying an example power system which contains a wide range of time response behavior

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Transient And Dynamic Average-Value Modeling Of Synchronous Machine Fed Load-Commutated Converters, Keith Corzine, S. D. Sudhoff, H. J. Hegner, D. E. Delisle Jan 1996

Transient And Dynamic Average-Value Modeling Of Synchronous Machine Fed Load-Commutated Converters, Keith Corzine, S. D. Sudhoff, H. J. Hegner, D. E. Delisle

Electrical and Computer Engineering Faculty Research & Creative Works

A new average-value model of a synchronous machine fed load-commutated converter is set forth in which the stator dynamics are combined with the DC link dynamics. This model is shown to he extremely accurate in predicting system transients and in predicting frequency-domain characteristics such as the impedance looking into the synchronous machine fed load-commutated converter. The model is verified against a detailed computer simulation and against a hardware test system, thus providing a three-way comparison. The proposed model is shown to be much more accurate than models in which the stator dynamics are neglected

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Two Methods Of Neural Network Controlled Dynamic Channel Allocation For Mobile Radio Systems, Kelvin T. Erickson, Edward J. Wilmes Jan 1996

Two Methods Of Neural Network Controlled Dynamic Channel Allocation For Mobile Radio Systems, Kelvin T. Erickson, Edward J. Wilmes

Electrical and Computer Engineering Faculty Research & Creative Works

Two methods of dynamic channel allocation using neural networks are investigated. Both methods continuously optimize the mobile network based on changes in calling traffic. The first method uses backpropagation model predictions to aid the channel allocator. Each cell contains a backpropagation model which provides the channel allocator a call traffic prediction allowing the channel allocator to effectively optimize the network. The second method uses the same backpropagation models along with actor-critic models to perform the channel allocation. The actor-critics learn to model traffic activity between adjacent cells in real-time, and thereby learn to allocate channels dynamically between cells. The learning …

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Evaluating The Value Of Distributed Photovoltaic Generations In Radial Distribution Systems, Badrul H. Chowdhury, A. W. Sawab Jan 1996

Evaluating The Value Of Distributed Photovoltaic Generations In Radial Distribution Systems, Badrul H. Chowdhury, A. W. Sawab

Electrical and Computer Engineering Faculty Research & Creative Works

The impact of photovoltaic (PV) generations, when added to an existing rural utility's distribution system, is studied. The addition of PV is examined in the light of voltage support, loss reduction, and reduction in peak demand. Comparisons are made with the conventional and widely used methods for voltage control and loss minimization, such as the addition of series and shunt capacitors and voltage regulators. The economics of distributed PV systems in the context of conventional grid power purchases are also studied. Results of this study are meant to be used as general guidelines for evaluating the impact of significant PV …

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An Experimentally Obtainable Heat Source Due To Absorption Of Ultrasound In Biological Media, James L. Drewniak, F. Dunn Jan 1996

An Experimentally Obtainable Heat Source Due To Absorption Of Ultrasound In Biological Media, James L. Drewniak, F. Dunn

Electrical and Computer Engineering Faculty Research & Creative Works

Deposition of heat as a result of loss in an ultrasonic wave may result in damage to biological tissues. The extensive use of ultrasound for diagnostic purposes during pregnancy necessitates the evaluation of thermal risk to a developing fetus during routine clinical exposures. Because of the small ultrasonic absorption coefficient in soft tissues at low megahertz frequencies, temperature elevations exceeding 1 °C are not expected from clinically employed ultrasound systems, and there is no evidence that such small temperature increases can result in deleterious effects. However, when the propagation path includes bone, which is known to be highly lossy, theoretical …

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Unsupervised Color Image Segmentation: With Application To Skin Tumor Borders, Randy Hays Moss, G. A. Hance, Scott E. Umbaugh, William V. Stoecker Jan 1996

Unsupervised Color Image Segmentation: With Application To Skin Tumor Borders, Randy Hays Moss, G. A. Hance, Scott E. Umbaugh, William V. Stoecker

Electrical and Computer Engineering Faculty Research & Creative Works

The images used in this research were digitized from 35mm color photographic slides obtained from a private dermatology practice and from New York University. The authors compared 6 color segmentation methods and their effectiveness as part of an overall border-finding algorithm. The PCT/median cut and adaptive thresholding algorithms provided the lowest average error and show the most promise for further individual algorithm development. Combining the different methods resulted in further improvement in the number of correctly identified tumor borders, and by incorporating additional heuristics in merging the segmented object information, one could potentially further increase the success rate. The algorithm …

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Fault Classification Using Kohonen Feature Mapping, Badrul H. Chowdhury, Kunyu Wang Jan 1996

Fault Classification Using Kohonen Feature Mapping, Badrul H. Chowdhury, Kunyu Wang

Electrical and Computer Engineering Faculty Research & Creative Works

Applications of neural networks to power system fault diagnosis have provided positive results and shown advantages in process speed over conventional approaches. This paper describes the application of a Kohonen neural network to fault detection and classification using the fundamental components of currents and voltages. The Electromagnetic Transients Program is used to obtain fault patterns for the training and testing of neural networks. Accurate classifications are obtained for all types of possible short circuit faults on test systems representing high voltage transmission lines. Short training time makes the Kohonen network suitable for on-line power system fault diagnosis. The method introduced …

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Dynamically Regularized Fast Rls With Application To Echo Cancellation, Steven L. Grant Jan 1996

Dynamically Regularized Fast Rls With Application To Echo Cancellation, Steven L. Grant

Electrical and Computer Engineering Faculty Research & Creative Works

This paper introduces a dynamically regularized fast recursive least squares (DR-FRLS) adaptive filtering algorithm. Numerically stabilized FRLS algorithms exhibit reliable and fast convergence with low complexity even when the excitation signal is highly self-correlated. FRLS still suffers from instability, however, when the condition number of the implicit excitation sample covariance matrix is very high. DR-FRLS, overcomes this problem with a regularization process which only increases the computational complexity by 50%. The benefits of regularization include: (1) the ability to use small forgetting factors resulting in improved tracking ability and (2) better convergence over the standard regularization technique of noise injection. …

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Input Dimension Reduction In Neural Network Training-Case Study In Transient Stability Assessment Of Large Systems, S. Muknahallipatna, Badrul H. Chowdhury Jan 1996

Input Dimension Reduction In Neural Network Training-Case Study In Transient Stability Assessment Of Large Systems, S. Muknahallipatna, Badrul H. Chowdhury

Electrical and Computer Engineering Faculty Research & Creative Works

The problem in modeling large systems by artificial neural networks (ANN) is that the size of the input vector can become excessively large. This condition can potentially increase the likelihood of convergence problems for the training algorithm adopted. Besides, the memory requirement and the processing time also increase. This paper addresses the issue of ANN input dimension reduction. Two different methods are discussed and compared for efficiency and accuracy when applied to transient stability assessment.

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Interaction Between Millimeter Oscillations And Monocrystal Hexagonal Ferrites With Modulated Resonance Frequency, Alexander A. Kitaytsev, Marina Koledintseva Jan 1996

Interaction Between Millimeter Oscillations And Monocrystal Hexagonal Ferrites With Modulated Resonance Frequency, Alexander A. Kitaytsev, Marina Koledintseva

Electrical and Computer Engineering Faculty Research & Creative Works

Investigation of non-linear stable effects taking place at ferromagnetic resonance (FMR) in monocrystal arbitrarily oriented hexagonal ferrite resonators (HFR) with controlled (modulated) resonance frequency is an urgent problem. The presented analysis is based on two approaches: the “quasistatic” approach using the static tensor of the HFR magnetic susceptibility and the “dynamic” one based on the solution of the magnetization vector motion equation (MVME) with varying time coefficients due to modulated magnetization field or HFR angle of orientation. The first approach is valid at low modulation frequencies (in comparison with the relaxation frequency of the HFR) and the second one can …

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Programmable Logic Controllers, Kelvin T. Erickson Jan 1996

Programmable Logic Controllers, Kelvin T. Erickson

Electrical and Computer Engineering Faculty Research & Creative Works

Programmable logic controllers (PLCs) are at the forefront of manufacturing automation. Many factories use programmable logic controllers to cut production costs and/or increase quality. PLCs and their unique language, ladder logic, are the workhorses of factory automation. Higher-level languages, such as sequential function charts and function blocks, ease the programming task for large systems. However, ladder logic remains the dominant language at present

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Security-Constrained Optimal Rescheduling Of Real Power Using Hopfield Neural Network, S. Ghosh, Badrul H. Chowdhury Jan 1996

Security-Constrained Optimal Rescheduling Of Real Power Using Hopfield Neural Network, S. Ghosh, Badrul H. Chowdhury

Electrical and Computer Engineering Faculty Research & Creative Works

A new method for security-constrained corrective rescheduling of real power using the Hopfield neural network is presented. The proposed method is based on solution of a set of differential equations obtained from transformation of an energy function. Results from this work are compared with the results from a method based on dual linear programming formulation of the optimal corrective rescheduling. The minimum deviations in real power generations and loads at buses are combined to form the objective function for optimization. Inclusion of inequality constraints on active line flow limits and equality constraint on real power generation load balance assures a …

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A Hybrid Observer For High Performance Brushless Dc Motor Drives, Keith Corzine, S. D. Sudhoff Jan 1996

A Hybrid Observer For High Performance Brushless Dc Motor Drives, Keith Corzine, S. D. Sudhoff

Electrical and Computer Engineering Faculty Research & Creative Works

Brushless DC motor drive systems are used in a wide variety of applications. These drives may be classified as being one of two types: sinusoidal drives in which there are no low-frequency harmonics in the current waveforms and no low-frequency torque ripple; and nonsinusoidal drives in which there is considerable low-frequency harmonic content, both in the current and torque waveforms. Although sinusoidal drives feature superior performance, they are generally more expensive since rotor position must be sensed on a continuous basis, thus requiring an optical encoder or a resolver, whereas relatively inexpensive Hall-effect sensors may be used for nonsinusoidal drives. …

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Analysis Of A Single-Phase Induction Machine With A Shifted Auxiliary Winding, T. A. Walls, Scott D. Sudhoff Jan 1996

Analysis Of A Single-Phase Induction Machine With A Shifted Auxiliary Winding, T. A. Walls, Scott D. Sudhoff

Electrical and Computer Engineering Faculty Research & Creative Works

This paper extents the method of multiple reference frames to the analysis of asymmetrical induction motors with non-orthogonal stator windings, with particular emphasis on the permanent split capacitor (PSC) machine. The predictions of the method are verified by comparison to both experimental results and to results obtained using a machine variable computer simulation. Once verified, the method is used to derive the transfer function relating rotor speed to load torque disturbance, which is of particular interest when analyzing PSC machines driving compressor loads. It is shown that the transfer function exhibits a distinct resonant point, and that the magnitude of …

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The Effect Of Excitation Limits On Voltage Stability, Jyothi Ayyagari, Mariesa Crow Dec 1995

The Effect Of Excitation Limits On Voltage Stability, Jyothi Ayyagari, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

Voltage collapse has been commonly associated with insufficient reactive power support. Steady state studies have related reactive power generation limitations to the sudden onset of voltage instability. This paper extends this approach to the dynamic case. The relationship between the dynamic models and steady state behavior is established. The dynamic model is then used to investigate the sudden change in system stability when the maximum excitation limit is reached. Several illustrative examples are analyzed. Corrective actions are proposed which will move the physical system away from the region of instability.

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Calibration And Measurement Of Dielectric Properties Of Finite Thickness Composite Sheets With Open-Ended Coaxial Sensors, Stoyan I. Ganchev, Nasser N. Qaddoumi, Sasan Bakhtiari, R. Zoughi Dec 1995

Calibration And Measurement Of Dielectric Properties Of Finite Thickness Composite Sheets With Open-Ended Coaxial Sensors, Stoyan I. Ganchev, Nasser N. Qaddoumi, Sasan Bakhtiari, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

The application of open-ended coaxial sensors for dielectric measurement of finite thickness composite sheets is studied. Expressions for calculation of the complex aperture admittance for two geometries are presented. These expressions are used to calculate the dielectric constant of infinite half-space as well as finite thickness slabs. A more efficient method of such calculations, using a personal computer, for low to medium loss dielectrics is demonstrated. The question of when a dielectric layer may be considered as infinitely thick is also addressed, and examples are presented. A different calibration technique (compared to the conventional ones) is described and successfully implemented. …

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Stop That Noise, Thomas Van Doren, Todd H. Hubing, Fei Sha, James L. Drewniak, David M. Hockanson Oct 1995

Stop That Noise, Thomas Van Doren, Todd H. Hubing, Fei Sha, James L. Drewniak, David M. Hockanson

Electrical and Computer Engineering Faculty Research & Creative Works

The authors discuss electromagnetic compatibility (EMC) and electromagnetic interference (EMI). After a brief look at the causes of EMI, they describe conductive coupling and electromagnetic radiative coupling. Career opportunities in EMC problem solving are looked at.

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A Fuzzy Based Load Model For Power System Direct Load Control, K. Bhattacharyya, Mariesa Crow Sep 1995

A Fuzzy Based Load Model For Power System Direct Load Control, K. Bhattacharyya, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

Demand side management programs are strategies designed to alter the shape of the load curve. In order to successfully implement such a strategy, customer acceptance of the program is vital. It is thus desirable to design a model for direct load control which may accommodate customer preferences. This paper presents a methodology for optimizing both customer satisfaction and utility unit commitment savings, based on a fuzzy load model for the direct load control of appliances.

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Fdtd Modeling Of Thin Wires For Simulating Common-Mode Radiation From Structures With Attached Cables, David M. Hockanson, James L. Drewniak, Todd H. Hubing, Thomas Van Doren Aug 1995

Fdtd Modeling Of Thin Wires For Simulating Common-Mode Radiation From Structures With Attached Cables, David M. Hockanson, James L. Drewniak, Todd H. Hubing, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

The analysis of shielding enclosures is complicated by the existence of apertures and cables. The finite-difference time-domain (FDTD) method can model shielding enclosures with complex geometries, but has difficulty modeling wires and cables of arbitrary radii. Modeling the wire by setting the axial component of the electric field to zero in the FDTD results in a wire with a radius determined by the mesh discretisation. Neglecting wire radius in applications such as electromagnetic interference (EMI) or printed circuit board modeling may result in gross errors because near field quantities are typically sensitive to wire thickness. Taflove (1990) developed a wire …

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Study Of Interconnect Vias By The Discrete Surface Integral Method, Hao Shi, James L. Drewniak Aug 1995

Study Of Interconnect Vias By The Discrete Surface Integral Method, Hao Shi, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

A non-orthogonal time-domain full-wave solver, is developed based on the Discrete Surface Integral (DSI) technique. Closed form expressions are derived for the coefficients used in the leap-frog computation scheme so that the DSI technique can be implemented as a generalized finite-difference procedure. This procedure is employed to investigate the propagation characteristics of a typical interconnect via in printed circuits. The numerically calculated scattering parameters show consistent behavior with measured results. A square via with equal area is also evaluated.

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A Comparison Of Fdtd Algorithms For Subcellular Modeling Of Slots In Shielding Enclosures, Kuang-Ping Ma, James L. Drewniak Aug 1995

A Comparison Of Fdtd Algorithms For Subcellular Modeling Of Slots In Shielding Enclosures, Kuang-Ping Ma, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

Thin slot modeling for the finite-difference time-domain (PDTD) method is investigated. Two subcellular algorithms for modeling thin slots with the FDTD method are compared for application to shielding enclosures in EMC. The stability of the algorithms is investigated, and comparisons between the two methods for slots in planes, and slots in loaded cavities are also made.

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Diagnosing And Modeling Common-Mode Radiation From Printed Circuit Boards With Attached Cables, James L. Drewniak, Fei Sha, Todd H. Hubing, Thomas Van Doren, J. Shaw Aug 1995

Diagnosing And Modeling Common-Mode Radiation From Printed Circuit Boards With Attached Cables, James L. Drewniak, Fei Sha, Todd H. Hubing, Thomas Van Doren, J. Shaw

Electrical and Computer Engineering Faculty Research & Creative Works

A procedure for diagnosing and modeling radiation from printed circuit boards with attached cables is presented through a case study of a production model electronic control unit. Procedures for determining EMI antennas, IC sources, and mechanisms by which noise is coupled from the IC source to the antenna are suggested.

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