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2000

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Articles 61 - 90 of 282

Full-Text Articles in Electrical and Computer Engineering

The Effect Of Anode Thickness In Sofcs With Anode Supported Ysz Film, Yi-Huang Zhang, Yi Jiang, Zi-Gui Lu, Yong-Lai Dong, Jing-Wang Yan Aug 2000

The Effect Of Anode Thickness In Sofcs With Anode Supported Ysz Film, Yi-Huang Zhang, Yi Jiang, Zi-Gui Lu, Yong-Lai Dong, Jing-Wang Yan

Journal of Electrochemistry

Solid oxide fuel cells with supported yttria stabilized zirconia electrolyte films on anode substrates of various thickness have been fabricated. The electrochemical performances of the SOFCs have been examined. The results showed that the cell performance was limited by the anodic overpotential, which is caused mainly by a concentration polarization when the anode substrate is thick. The anodic overpotential was reduced obviously as the thickness of anode substrate was decreased. As a result, the performance of the SOFC cell was improved. With a 0.5 mm anode substrate, a SOFC cell produced a power density about 0.19 W/cm2 at 800 …

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A New Method For The Preparation Of The Electrodes With Very Low Platinum Loading Used In Proton Exchange Membrane Fuel Cell, Zhi-Gang Shao, Bao-Lian Yi, Ming Han, Ya-Guang Qiao, Hao Liu, Jing-Rong Yu Aug 2000

A New Method For The Preparation Of The Electrodes With Very Low Platinum Loading Used In Proton Exchange Membrane Fuel Cell, Zhi-Gang Shao, Bao-Lian Yi, Ming Han, Ya-Guang Qiao, Hao Liu, Jing-Rong Yu

Journal of Electrochemistry

Research and development on low platinum loading electrode is very important in reducing the cost of proton exchange membrane fuel cell(PEMFC) stack. This paper has put forward a new method to prepare the electrode of PEMFC. The pore forming substances were used in this methd. The low platinum loading electrodes (0.02 mgPt⋅cm-2) have already been prepared with the method. Compared with the traditional method, the new method is simple, cheep, and easy to scale up. The superior composition of the electrodes is catalyst: pore forming substance: Nafion= 3:3:1. The performance of a single cell using this …

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Method Of Testing And Diagnosing Field Programmable Gate Arrays, Miron Abramovici, Eric Seng-Kar Lee, Charles Eugene Stroud Aug 2000

Method Of Testing And Diagnosing Field Programmable Gate Arrays, Miron Abramovici, Eric Seng-Kar Lee, Charles Eugene Stroud

Electrical and Computer Engineering Faculty Patents

A method of testing field programmable gate arrays (FPGAs) includes establishing a first group of programmable logic blocks as test pattern generators or output response analyzers and a second group of programmable logic blocks as blocks under test. This is followed by generating test patterns and comparing outputs of two blocks under test with one output response analyzer. Next is the combining of results of a plurality of output response analyzers utilizing an iterative comparator in order to produce a pass/fail indication. The method also includes the step of reconfiguring each block under test so that each block under test …

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All-Solid-State Electrochromic Reflectance Device For Emittance Modulation In The Far-Infrared Spectral Region, E. B. Franke, C. L. Trimble, Mathias Schubert, John A. Woollam Aug 2000

All-Solid-State Electrochromic Reflectance Device For Emittance Modulation In The Far-Infrared Spectral Region, E. B. Franke, C. L. Trimble, Mathias Schubert, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

All-solid-state electrochromic reflectance devices for thermal emittance modulation were designed for operation in the spectral region from mid- to far-infrared wavelengths (2–40 μm). All device constituent layers were grown by magnetron sputtering. The electrochromic (polycrystalline WO3), ion conductor (Ta2O5), and Li+ ion-storage layer (amorphous WO3), optimized for their infrared (IR) optical thicknesses, are sandwiched between a highly IR reflecting Al mirror, and a 90% IR transmissive Al grid top electrode, thereby meeting the requirements for a reversible Li+ ion insertion electrochromic device to operate within the 300 K blackbody emission …

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Process Modeling, Monitoring And Control Of Laser Metal Forming, N. Munjuluri, Sanjeev Agarwal, Frank W. Liou Aug 2000

Process Modeling, Monitoring And Control Of Laser Metal Forming, N. Munjuluri, Sanjeev Agarwal, Frank W. Liou

Electrical and Computer Engineering Faculty Research & Creative Works

Laser Metal Forming (LMF) process is one of the prominent Rapid Prototyping (RP) process that can be used to develop functional and fully dense metal parts. This paper addresses process modeling, monitoring and control of a laser metal forming system currently under development at Laser Aided Manufacturing Processes (LAMP) laboratory at University of Missouri--Rolla. This LMF system is based on a 2.5kW Nd:YAG laser as energy source and integrates five axis metal deposition and five axis machining. The current paper is aimed at characterization of effects of operating parameters such as traverse speed, mass flow-rate and laser power on the …

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Sio2-Passivated Lateral-Geometry Gan Transparent Schottky-Barrier Detectors, V. Adivarahan, Grigory Simin, J. W. Yang, A. Lunev, M. Asif Khan, M. Pala, M. Shur, R. Gaska Aug 2000

Sio2-Passivated Lateral-Geometry Gan Transparent Schottky-Barrier Detectors, V. Adivarahan, Grigory Simin, J. W. Yang, A. Lunev, M. Asif Khan, M. Pala, M. Shur, R. Gaska

Faculty Publications

We report on a transparent Schottky-barrierultraviolet detector on GaN layers over sapphire substrates. Using SiO2 surface passivation, reverse leakage currents were reduced to a value as low as 1 pA at 5 V reverse bias for 200 μm diameter device. The device exhibits a high internal gain, about 50, at low forward biases. The response time (about 15 ns) is RC limited, even in the internal gain regime. A record low level of the noise spectral density, 5×10−23 A2/Hz, was measured at 10 Hz. We attribute this low noise level to the reduced reverse leakage current.

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Analysis Of The Anodic Bonding Process And The Packaging Effects In Mems Devices, Sonya G. Iyasere Aug 2000

Analysis Of The Anodic Bonding Process And The Packaging Effects In Mems Devices, Sonya G. Iyasere

Electronic Dissertations and Theses

This paper gives a brief overview of the process of completely sealing and permanently joining glass to a semi-conductor without the use of adhesives known as anodic or electrostatic bonding. It is well known that this process will introduce thermal strain due to different coefficients of thermal expansion between any metal or semiconductor and glass. This paper will also describe the effect of the MEMS packaging process on various devices that are bonded electrostatically.

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Experimental And Numerical Study Of The Radiation From Microstrip Bends, H. Wang, Yun Ji, Todd H. Hubing, James L. Drewniak, Thomas Van Doren, Richard E. Dubroff Aug 2000

Experimental And Numerical Study Of The Radiation From Microstrip Bends, H. Wang, Yun Ji, Todd H. Hubing, James L. Drewniak, Thomas Van Doren, Richard E. Dubroff

Electrical and Computer Engineering Faculty Research & Creative Works

This paper investigates the radiation from microstrip lines with 90-degree bends. A 1-GHz TEM cell is used to measure the radiation from microstrip lines with different kinds of bends. A full wave hybrid FEM/MoM code is used to compute the radiation. Both experimental and numerical results show that there is no significant difference between the radiation from right angle bends and bends with two 45-degree corners at frequencies and trace dimensions that are likely to be found on printed circuit boards.

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The Emi Benefits Of Ground Plane Stitching In Multi-Layer Power Bus Stacks, Xiaoning Ye, David M. Hockanson, Min Li, Wei Cui, S. Radu, James L. Drewniak, Thomas Van Doren, Todd H. Hubing, Richard E. Dubroff Aug 2000

The Emi Benefits Of Ground Plane Stitching In Multi-Layer Power Bus Stacks, Xiaoning Ye, David M. Hockanson, Min Li, Wei Cui, S. Radu, James L. Drewniak, Thomas Van Doren, Todd H. Hubing, Richard E. Dubroff

Electrical and Computer Engineering Faculty Research & Creative Works

The effect on EMI of stitching multiple ground planes together along the periphery of multi-layer PCB stacks is studied. Power bus noise induced EMI and radiation from the board edges is the major concern herein. The EMI at 3 meters for different via stitch spacing and layer thickness is modeled with FDTD modeling. It is shown that the ground plane stitching effectively reduces the radiated EMI that results from fringing fields at the power bus edges. Two families of curves are generated to demonstrate the variation of the radiated EMI as a function of layer thickness and stitch spacing. Further …

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Development Of A Closed-Form Expression For The Input Impedance Of Power-Ground Plane Structures, Minjia Xu, Yun Ji, Todd H. Hubing, Thomas Van Doren, James L. Drewniak Aug 2000

Development Of A Closed-Form Expression For The Input Impedance Of Power-Ground Plane Structures, Minjia Xu, Yun Ji, Todd H. Hubing, Thomas Van Doren, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

This paper analyzes the fundamental behavior of PCB power bus structures using the modal expansion method. The results are validated by experiments and full-wave numerical modeling. It is shown that the power bus can be modeled as a series LeC circuit below the first board resonance frequency. C is the interplane capacitance and Le is an effective inductance contributed by all the cavity nodes. The effects of the layer thickness, port location, board size and the feeding wire radius on the value of Le are discussed in this study. Le can be estimated from the …

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Emc Analysis Of An 18" Lcd Monitor, Theodore M. Zeeff, Todd H. Hubing, James L. Drewniak, Richard E. Dubroff, Thomas Van Doren Aug 2000

Emc Analysis Of An 18" Lcd Monitor, Theodore M. Zeeff, Todd H. Hubing, James L. Drewniak, Richard E. Dubroff, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

This paper describes a case study covering the evaluation and reduction of the radiated EMI from an 18 inches Liquid Crystal Display (LCD) monitor. The evaluation was completed in two parts: first potential EMI sources at the Printed Circuit Board (PCB) level were identified, then the EMI antennas driven by these sources were analyzed. Methods for reducing the EMI were described in detail, and where applicable, those modifications were applied. Radiated measurements demonstrate the effectiveness of these recommendations.

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Experimental And Fdtd Study Of The Emi Performance Of An Open-Pin-Field Connector For Modules-On-Backplanes, Xiaoning Ye, Jim Nadolny, James L. Drewniak, Richard E. Dubroff, Thomas Van Doren, Todd H. Hubing Aug 2000

Experimental And Fdtd Study Of The Emi Performance Of An Open-Pin-Field Connector For Modules-On-Backplanes, Xiaoning Ye, Jim Nadolny, James L. Drewniak, Richard E. Dubroff, Thomas Van Doren, Todd H. Hubing

Electrical and Computer Engineering Faculty Research & Creative Works

Experimental measurements and numerical modeling were used to study the EMI performance of a module-on-backplane connector for various configurations of signal-return pin-outs. A commercially available open-pin-field connector was used in these results to connect between the mother-board and the daughter-card. The experimental techniques, based on measuring |S21|, included both common-mode current measurements and monopole near-field probe measurements. The FDTD method was used to provide numerical support of the near-field measurements and generally agreed with the measured results for frequencies up to 3 GHz. The FDTD method was also used to investigate the relationship between the radiated EMI at …

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Experimental Evaluation Of Power Bus Decoupling On A 4-Layer Printed Circuit Board, Juan Chen, Minjia Xu, Todd H. Hubing, James L. Drewniak, Thomas Van Doren, Richard E. Dubroff Aug 2000

Experimental Evaluation Of Power Bus Decoupling On A 4-Layer Printed Circuit Board, Juan Chen, Minjia Xu, Todd H. Hubing, James L. Drewniak, Thomas Van Doren, Richard E. Dubroff

Electrical and Computer Engineering Faculty Research & Creative Works

The switching of active devices on printed circuit boards (PCBs) can cause a momentary surge or drop in the power bus voltage. Decoupling capacitors are often utilized to alleviate this problem. They help to stabilize the power bus voltage by supplying transient current to active devices. The decoupling strategy, including where to place the high-frequency decoupling capacitors, is often a topic of debate. This paper examines the effect of decoupling capacitor placement on a 4-layer printed circuit board. Some design guidelines are provided.

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Emi From Airflow Aperture Arrays In Shielding Enclosures-Experiments, Fdtd, And Mom Modeling, Min Li, Joe Nuebel, James L. Drewniak, Richard E. Dubroff, Todd H. Hubing, Thomas Van Doren Aug 2000

Emi From Airflow Aperture Arrays In Shielding Enclosures-Experiments, Fdtd, And Mom Modeling, Min Li, Joe Nuebel, James L. Drewniak, Richard E. Dubroff, Todd H. Hubing, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

Aperture arrays designed to provide airflow through shielding enclosures can provide part of the coupling path from interior sources to external electromagnetic interference (EMI). In this work, radiation through aperture arrays is investigated numerically and experimentally. FDTD modeling is compared with measurements on aperture arrays in a test enclosure. The method of moments (MoM) is also utilized to study radiation from apertures and to investigate the mutual coupling between apertures in an infinite conducting plane. A simple design equation for the relation between aperture size and number and shielding effectiveness is proposed.

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Quantifying Decoupling Capacitor Location, Jun Fan, James L. Knighten, Antonio Orlandi, Norman W. Smith, James L. Drewniak Aug 2000

Quantifying Decoupling Capacitor Location, Jun Fan, James L. Knighten, Antonio Orlandi, Norman W. Smith, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

Decoupling capacitor location in DC power bus design is a critical design choice for which proven guidelines are not well established. The mutual inductance between two closely spaced vias can have a great impact on the coupling between an IC and a decoupling capacitor. This coupling is a function of the spacing between the IC and capacitor, and spacing between power and ground layers. The impact of the mutual inductance on decoupling, i.e., local versus global decoupling, was studied, using a circuit extraction approach based on a mixed-potential integral equation. Modeling indicates that local decoupling has benefits over global decoupling …

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Fdtd And Fem/Mom Modeling Of Emi Resulting From A Trace Near A Pcb Edge, Daniel P. Berg, Motoshi Tanaka, Yun Ji, Xiaoning Ye, James L. Drewniak, Todd H. Hubing, Richard E. Dubroff, Thomas Van Doren Aug 2000

Fdtd And Fem/Mom Modeling Of Emi Resulting From A Trace Near A Pcb Edge, Daniel P. Berg, Motoshi Tanaka, Yun Ji, Xiaoning Ye, James L. Drewniak, Todd H. Hubing, Richard E. Dubroff, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

PCB traces routed near board edges and carrying high-speed signals are considered to contribute to EMI problems. Consequently, design maxims state that traces that might have intentional or unintentional high frequency components on them be kept away from board edges. This costs valuable surface area as boards become more densely designed. Further, design maxims concerning traces near board edges are not well quantified. The increase in EMI as a trace is routed increasingly closer to the PCB edge has been studied experimentally and with numerical modeling.

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Finite Element Modeling Of Patch Antenna And Cavity Sources, Yun Ji, Todd H. Hubing, James L. Drewniak Aug 2000

Finite Element Modeling Of Patch Antenna And Cavity Sources, Yun Ji, Todd H. Hubing, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

This paper examines two different approaches that can be used to model patch antennas and cavities fed by a coaxial cable. The probe model represents the feed as a current filament along the center conductor of the coaxial cable. The coaxial-cable model enforces the analytical field distribution at the cable opening. These two models have been implemented in a hybrid FEM/MoM code. A power bus structure and a cavity geometry with coaxial-cable feeds are investigated. Numerical results obtained for these two examples are compared with measurements. It is shown that the probe model should only be applied to electrically short …

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Distributed Arithmetic Implementation Of Multivariable Controllers For Smart Structural Systems, Lingfeng Yuan, Sridhar Sana, Hardy J. Pottinger, Vittal S. Rao Aug 2000

Distributed Arithmetic Implementation Of Multivariable Controllers For Smart Structural Systems, Lingfeng Yuan, Sridhar Sana, Hardy J. Pottinger, Vittal S. Rao

Electrical and Computer Engineering Faculty Research & Creative Works

Smart structural systems require the electronic control systems which are integrated into the structures to be small, lightweight and power-efficient. The field programmable gate array (FPGA) is a good platform to implement such controllers. In our previous work, FPGA-based digital controllers were built and tested on a simple structural system. In order to implement multivariable controllers, the hardware resources for FPGA-based architecture need to be further reduced. Distributed arithmetic (DA) has long been proven to be a very efficient means to mechanize computations that are dominated by inner products involving constant multiplicand. The computational requirements of the smart structural controllers …

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Real-Time Performance Analysis Of Wireless Multimedia Networks Based On Partially Observed Multivariate Point Processes, William S. Hortos Jul 2000

Real-Time Performance Analysis Of Wireless Multimedia Networks Based On Partially Observed Multivariate Point Processes, William S. Hortos

Electrical Engineering and Computer Science Faculty Publications

Third-generation (3G) wireless networks will support integrated multimedia services based on a cellular extension of a packet-switched architecture using variants of the Internet protocol (IP). Services can be categorized as real-time and delaysensitive, or non-real-time and delay-insensitive. Each call, arriving to or active within the network, carries demand for one or more services in parallel; each service type with a guaranteed quality of service (QoS). Admission of new calls to the wireless IP network (WIN) from the gateway of a wired network or from a mobile subscriber (MS) is allowed by call admission control (CAC) procedures. Roaming of the MSs …

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Pattern Classification Approach To Underwater Acoustic Communications Based On The Wigner-Ville Distribution, Frank M. Caimi, Gamal A. Hassan Jul 2000

Pattern Classification Approach To Underwater Acoustic Communications Based On The Wigner-Ville Distribution, Frank M. Caimi, Gamal A. Hassan

Electrical Engineering and Computer Science Faculty Publications

This paper describes an approach and preliminary results associated with the use of pattern recognition techniques to identify transmitted information (symbols) in a temporally variant acoustic channel. The method allows the observation of the transmitted signal simultaneously in both time and frequency space and does not necessarily rely on the application of adaptive algorithms for reception. The observation of the symbol energy from the Wigner-Ville Distribution as two-dimensional pattern can allow the determination of channel characteristics over short symbol sequences and can provide a means for symbol detection. For the QPSK modulation used, wavelet filtering provides a basis for noise …

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2deg Channel-Dependent Model For Hg1-Xcdxte Based Pseudomorphic Hemts, Hang-Ming Dai, Thomas J. Sanders Jul 2000

2deg Channel-Dependent Model For Hg1-Xcdxte Based Pseudomorphic Hemts, Hang-Ming Dai, Thomas J. Sanders

Electrical Engineering and Computer Science Faculty Publications

HgCdTe has emerged as an important electronic material because of its IRFPA applications. Technologies for growing the material are advanced and current sources for the material are more readily available than in the past. This brings an advantage to the manufacturing other types of HgCdTe devices. PHEMTs are attractive as applications of high-speed devices. In this paper, a model for PHEMT devices by using Hg1 Cd1Te as device materials is presented. High digital performance of the device is expected because electron mobility ofthe material is very high at low temperatures.

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Computation For Crosstalk Effects In P-On-N Hg1-Xcdxte Heterojunction Irfpa Radiated By Using Uniformly Parallel Light, Hang-Ming Dai, Thomas J. Sanders Jul 2000

Computation For Crosstalk Effects In P-On-N Hg1-Xcdxte Heterojunction Irfpa Radiated By Using Uniformly Parallel Light, Hang-Ming Dai, Thomas J. Sanders

Electrical Engineering and Computer Science Faculty Publications

in our work, a three-dimensional IRFPA model has been constructed to conduct device simulations for drift-diffusion based Hg1 CdTe devices. The model uses the finite element method and numerical errors are automatically eliminated during computation. Computational results can thus easily achieve accuracy. The computer model was constructed by using C++ language. We have successfully represented simulation results in three-dimensional graphics. In this paper, a model for analyzing infrared-illuminated p-on-n photodiodes is presented. The computational results were verified analytically and experimentally. Furthermore, an IRFPA device model was built for calculating crosstalk by using uniformly collimated infrared radiation. Devices used for the …

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A Technique For Analyzing Radiation From Conformal Antennas Mounted On Arbitrarily-Shaped Conducting Bodies, Dean Arakaki, Douglas H. Werner, Raj Mittra Jul 2000

A Technique For Analyzing Radiation From Conformal Antennas Mounted On Arbitrarily-Shaped Conducting Bodies, Dean Arakaki, Douglas H. Werner, Raj Mittra

Electrical Engineering

This paper presents an efficient method to solve the problem of radiation from conformal aperture and microstrip antennas mounted on arbitrarily shaped conducting bodies. The method, based on the surface equivalence and reciprocity principles, uses a combination of the finite difference time domain (FDTD) and method of moments (MoM) techniques to substantially improve the computational efficiency of the radiation pattern calculation. When the geometry and location of the radiating element are modified, only a small portion of the overall analysis requires re-simulation. This leads to a significant improvement in computational efficiency over presently used techniques, and can substantially improve the …

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Electrical Properties Of Rapid Thermal Oxides On Si1−X−YGeXCY Films, L. K. Bera, W. K. Choi, W. Feng, Cary Y. Yang, J. Mi Jul 2000

Electrical Properties Of Rapid Thermal Oxides On Si1−X−YGeXCY Films, L. K. Bera, W. K. Choi, W. Feng, Cary Y. Yang, J. Mi

Electrical and Computer Engineering

The electrical characteristics of rapid thermal oxides on Si1−x−yGexCy layers are reported. X-ray photoelectron spectroscopy results indicate segregation of Ge at the SiO2/Si1−x−yGexCy interface, a thin GeO2 layer at the oxide surface, and elemental Ge at the interface and in the oxide. The interface state density of the samples ranges from 3.0×1011 to 3.6×1012 eV−1 cm−2. All the samples show electron trapping behavior and the trap generation rate decreases with increasing C concentration. The charge-to-breakdown value and the oxide breakdown field are …

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Role Of Laboratory Education In Power Engineering: Is The Virtual Laboratory Feasible? Part I, S. Iwamoto, G. G. Karady, Kraig J. Olejniczak, H. A. Mantooth, Mariesa Crow, Gerald T. Heydt Jul 2000

Role Of Laboratory Education In Power Engineering: Is The Virtual Laboratory Feasible? Part I, S. Iwamoto, G. G. Karady, Kraig J. Olejniczak, H. A. Mantooth, Mariesa Crow, Gerald T. Heydt

Electrical and Computer Engineering Faculty Research & Creative Works

IEEE PES sponsors a panel session in the summer power meeting in Seattle on laboratory education in power engineering. Six short papers and one full paper summarize the opinions of the panelist. This paper contains the summary of four of the presentations. The objective of the panel is to discuss the role of laboratory education in power engineering at both the graduate and undergraduate level. The question is what type of laboratory course is needed? Power electronics, electric machines, system simulation, etc? the second objective is to assess the status and value of computer based virtual laboratories. This includes the …

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An Improved Statcom Model For Power Flow Analysis, Zhiping Yang, Chen Shen, Lingli Zhang, Mariesa Crow Jul 2000

An Improved Statcom Model For Power Flow Analysis, Zhiping Yang, Chen Shen, Lingli Zhang, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

The StatCom is traditionally modeled for power flow analysis as a PV or PQ bus depending on its primary application. The active power is either set to zero (neglecting the StatCom losses) or calculated iteratively. The StatCom voltage and reactive power compensation are usually related through the magnetics of the StatCom. This traditional power flow model of the StatCom neglects the impact of the high-frequency effects and the switching characteristics of the power electronics on the active power losses and the reactive power injection (absorption). In this paper, the authors propose a new StatCom model appropriate for power flow analysis …

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An Iterative Approach To Multisensor Sea Ice Classification, David G. Long, Mark R. Drinkwater, Quinn P. Remund Jul 2000

An Iterative Approach To Multisensor Sea Ice Classification, David G. Long, Mark R. Drinkwater, Quinn P. Remund

Faculty Publications

Characterizing the variability in sea ice in the polar regions is fundamental to an understanding of global climate and the geophysical processes governing climate changes. Sea ice can be grouped into a number of general classes with different characteristics. Multisensor data from NSCAT, ERS-2, and SSM/I are reconstructed into enhanced resolution imagery for use in ice-type classification. The resulting twelve-dimensional data set is linearly transformed through principal component analysis to reduce data dimensionality and noise levels. An iterative statistical data segmentation algorithm is developed using maximum likelihood (ML) and maximum a posteriori (MAP) techniques. For a given ice type, the …

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Azimuth Variation In Microwave Scatterometer And Radiometer Data Over Antarctica, David G. Long, Mark R. Drinkwater Jul 2000

Azimuth Variation In Microwave Scatterometer And Radiometer Data Over Antarctica, David G. Long, Mark R. Drinkwater

Faculty Publications

While designed for ocean observation, scatterometer and radiometer data have proven very useful in a variety of cryosphere studies. Over large regions of Antarctica, ice sheet and bedrock topography and the snow deposition, drift, and erosional environment combine to produce roughness on various scales. Roughness ranges from broad, basin-scale ice-sheet topography at 100 km wavelengths to large, spatially coherent dune fields at 10 km wavelength to erosional features on the meter scale known as sastrugi. These roughness scales influence the microwave backscattering and emission properties of the surface, combining to introduce azimuth-angle dependencies in the satellite observation data. In this …

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Diversity Performance Of Dual-Antenna Handsets Near Operator Tissue, Michael A. Jensen, Bruce M. Green Jul 2000

Diversity Performance Of Dual-Antenna Handsets Near Operator Tissue, Michael A. Jensen, Bruce M. Green

Faculty Publications

This paper presents a computational and experimental study of the diversity performance of two dual-antenna handsets operating indoors in the 902-928 MHz industrial, scientific, and medical (ISM) band. Of particular interest is the effect of the operator tissue on the diversity operation. Key indicators of diversity gain such as branch mean effective gain (MEG) and envelope correlation coefficient are obtained from finite-difference time-domain (FDTD) method simulations as well as from experimental measurements in three different indoor environments. Diversity gain for the handsets is also measured directly. Reasonable agreement is observed between the experimental and simulated results, with both approaches indicating …

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Neural Networks Versus Nonparametric Neighbor-Based Classifiers For Semisupervised Classification Of Landsat Thematic Mapper Imagery, Perry J. Hardin Jul 2000

Neural Networks Versus Nonparametric Neighbor-Based Classifiers For Semisupervised Classification Of Landsat Thematic Mapper Imagery, Perry J. Hardin

Faculty Publications

Semisupervised classification is one approach to converting multiband optical and infrared imagery into landcover maps. First, a sample of image pixels is extracted and clustered into several classes. The analyst next combines the clusters by hand to create a smaller set of groups that correspond to a useful landcover classification. The remaining image pixels are then assigned to one of the aggregated cluster groups by use of a per-pixel classifier. Since the cluster aggregation process frequently creates groups with multivariate shapes ill suited for parametric classifiers, there has been renewed interest in nonparametric methods for the task. This research reports …

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