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Electrical and Computer Engineering

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2003

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Articles 91 - 120 of 313

Full-Text Articles in Engineering

Micro-Genetic Algorithm Design Of Hybrid Conventional Waveguide And Photonic Crystal Structures, J. Cai, S. Kim, Gregory P. Nordin, J. Jiang Jul 2003

Micro-Genetic Algorithm Design Of Hybrid Conventional Waveguide And Photonic Crystal Structures, J. Cai, S. Kim, Gregory P. Nordin, J. Jiang

Faculty Publications

We previously proposed the hybrid integration of photonic crystals (PhCs) and conventional index-guided waveguides (CWGs) as a potentially attractive method of realizing compact waveguide elements for large-scale planar lightwave circuits (PLCs). We now examine 90-deg bends and beamsplitters in PhC/CWG structures in which the waveguide core has a high refractive index (3.25) and yet a low refractive index contrast (1.54%) with the clad material. A PhC structure composed of a triangular or square array of air holes is placed at the intersection of input and output waveguides to obtain high efficiency 90-deg bends. We find that diffraction from the boundary …

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Progress In Spectroscopic Ellipsometry: Applications From Vacuum Ultraviolet To Infrared, James N. Hilfiker, Corey L. Bungay, Ron A. Synowicki, Thomas E. Tiwald, Craig M. Herzinger, Blaine Johs, Greg K. Pribil, John A. Woollam Jul 2003

Progress In Spectroscopic Ellipsometry: Applications From Vacuum Ultraviolet To Infrared, James N. Hilfiker, Corey L. Bungay, Ron A. Synowicki, Thomas E. Tiwald, Craig M. Herzinger, Blaine Johs, Greg K. Pribil, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

Spectroscopic ellipsometry (SE) is a noncontact and nondestructive optical technique for thin film characterization. In the past 10 yr, it has migrated from the research laboratory into the semiconductor, data storage, display, communication, and optical coating industries. The wide acceptance of SE is a result of its flexibility to measure most material types: dielectrics, semiconductors, metals, superconductors, polymers, biological coatings, and even multilayers of these materials. Measurement of anisotropic materials has also made huge strides in recent years. Traditional SE measurements cover the ultraviolet, visible, and near infrared wavelengths. This spectral range is now acquired within seconds with high accuracy …

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Automatic Classification Of African Elephant (Loxodonta Africana) Follicular And Luteal Rumbles, Michael T. Johnson, Patrick J. Clemins Jul 2003

Automatic Classification Of African Elephant (Loxodonta Africana) Follicular And Luteal Rumbles, Michael T. Johnson, Patrick J. Clemins

Dr. Dolittle Project: A Framework for Classification and Understanding of Animal Vocalizations

Recent research in African elephant vocalizations has shown that there is evidence for acoustic differences in the rumbles of females based on the phase of their estrous cycle (1). One reason for these differences might be to attract a male for reproductive purposes. Since rumbles have a fundamental frequency near 10Hz, they attenuate slowly and can be heard over a distance of several kilometers. This research exploits differences in the rumbles to create an automatic classification system that can determine whether a female rumble was made during the luteal or follicular phase of the ovulatory cycle. This system could be …

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An Adaptive Neural Network Identifier For Effective Control Of A Static Compensator Connected To A Power System, Salman Mohagheghi, Jung-Wook Park, Ganesh K. Venayagamoorthy, Mariesa Crow, Ronald G. Harley Jul 2003

An Adaptive Neural Network Identifier For Effective Control Of A Static Compensator Connected To A Power System, Salman Mohagheghi, Jung-Wook Park, Ganesh K. Venayagamoorthy, Mariesa Crow, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

A novel method for nonlinear identification of a static compensator connected to a power system using continually online trained (COT) artificial neural networks (ANNs) is presented in this paper. The identifier is successfully trained online to track the dynamics of the power network without any need for offline data and can be used in designing an adaptive neurocontroller for a static compensator connected to such system.

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Neuroidentification Of System Parameters For The Shunt & Series Branch Control Of Upfc, Ganesh K. Venayagamoorthy, Radha P. Kalyani, Mariesa Crow Jul 2003

Neuroidentification Of System Parameters For The Shunt & Series Branch Control Of Upfc, Ganesh K. Venayagamoorthy, Radha P. Kalyani, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

The crucial factor affecting the modern power systems today is load flow control. The unified power flow controller (UPFC) forms an affective means for controlling the power flow. The UPFC consists of shunt and series inverters which are conventionally controlled using linear controllers. This paper presents the design of neuroidentifiers that identify the system parameters that determine the UPFC controller outputs one-time step ahead thus, making the pathway for the design of adaptive neurocontrollers. Two neuroidentifiers are used for identifying the nonlinear dynamics of power system and UPFC, one neuroidentifier for the shunt inverter and the other for the series …

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A Ram-Based Neural Network For Collision Avoidance In A Mobile Robot, Qiang Yao, Daryl G. Beetner, Donald C. Wunsch, Bjorn Osterloh Jul 2003

A Ram-Based Neural Network For Collision Avoidance In A Mobile Robot, Qiang Yao, Daryl G. Beetner, Donald C. Wunsch, Bjorn Osterloh

Electrical and Computer Engineering Faculty Research & Creative Works

A RAM-based neural network is being developed for a mobile robot controlled by a simple microprocessor system. Conventional neural networks often require a powerful and sophisticated computer system. Training a multi-layer neural network requires repeated presentation of training data, which often results in very long learning time. The goal for this paper is to demonstrate that RAM-based neural networks are a suitable choice for embedded applications with few computational resources. This functionality is demonstrated in a simple robot powered by an 8051 microcontroller with 512 bytes of RAM. The RAM-based neural network allows the robot to detect and avoid obstacles …

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Diagnostics Of Eccentricities And Bar/End-Ring Connector Breakages In Polyphase Induction Motors Through A Combination Of Time-Series Data Mining And Time-Stepping Coupled Fe-State Space Techniques, John F. Bangura, Richard J. Povinelli, Nabeel Demerdash, Ronald H. Brown Jul 2003

Diagnostics Of Eccentricities And Bar/End-Ring Connector Breakages In Polyphase Induction Motors Through A Combination Of Time-Series Data Mining And Time-Stepping Coupled Fe-State Space Techniques, John F. Bangura, Richard J. Povinelli, Nabeel Demerdash, Ronald H. Brown

Electrical and Computer Engineering Faculty Research and Publications

This paper develops the foundations of a technique for detection and categorization of dynamic/static eccentricities and bar/end-ring connector breakages in squirrel-cage induction motors that is not based on the traditional Fourier transform frequency-domain spectral analysis concepts. Hence, this approach can distinguish between the "fault signatures" of each of the following faults: eccentricities, broken bars, and broken end-ring connectors in such induction motors. Furthermore, the techniques presented here can extensively and economically predict and characterize faults from the induction machine adjustable-speed drive design data without the need to have had actual fault data from field experience. This is done through the …

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Vertebra Shape Classification Using Mlp For Content-Based Image Retrieval, Sameer K. Antani, L. Rodney Long, George R. Thoma, R. Joe Stanley Jul 2003

Vertebra Shape Classification Using Mlp For Content-Based Image Retrieval, Sameer K. Antani, L. Rodney Long, George R. Thoma, R. Joe Stanley

Electrical and Computer Engineering Faculty Research & Creative Works

A desirable content-based image retrieval (CBIR) system would classify extracted image features to support some form of semantic retrieval. The Lister Hill National Center for Biomedical Communications, an intramural R&D division of the National Library for Medicine (NLM), maintains an archive of digitized X-rays of the cervical and lumbar spine taken as part of the second national health and nutrition examination survey (NHANES II). It is our goal to provide shape-based access to digitized X-rays including retrieval on automatically detected and classified pathology, e.g., anterior osteophytes. This is done using radius of curvature analysis along the anterior portion, and morphological …

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Design Of A Multiband Internal Antenna For Third Generation Mobile Phone Handsets, Mohammod Ali, Gerard James Hayes, Huan-Sheng Hwang, Robert A. Sadler Jul 2003

Design Of A Multiband Internal Antenna For Third Generation Mobile Phone Handsets, Mohammod Ali, Gerard James Hayes, Huan-Sheng Hwang, Robert A. Sadler

Faculty Publications

A multiband internal antenna is introduced. The antenna consists of a driven meander-line element and two parasitic elements. The design is particularly unique since it supports the third generation mobile phone handsets where multiband operation is greatly desired. The proposed antenna operates effectively in the aMPS 800 (824-894 MHz), GSM 900 (880-960 MHz), and GSM 1900 (1850-1990 MHz) bands within 2.5:1 (voltage standing wave ratio (VSWR). Detail design criteria with respect to geometrical parameter variation are given. Experimental data (VSWR and pattern) obtained from a laboratory prototype are also presented.

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Design And Testing Of Spacecraft Power Systems Using Vtb, Zhenhua Jiang, Shengyi Liu, Roger A. Dougal Jul 2003

Design And Testing Of Spacecraft Power Systems Using Vtb, Zhenhua Jiang, Shengyi Liu, Roger A. Dougal

Faculty Publications

A study is presented on the design and testing of spacecraft power systems using the virtual test bed (VTB). The interdisciplinary components such as solar array and battery systems were first modeled in native VTB format and validated by experiment data. The shunt regulator and battery charge controller were designed in Simulink according to the system requirements and imported to VTB. Two spacecraft power systems were then designed and tested together with the control systems.

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Evolved Reversible Cascades Realized On The Cam-Brain Machine (Cbm), Andrzej Buller, Marek Perkowski Jul 2003

Evolved Reversible Cascades Realized On The Cam-Brain Machine (Cbm), Andrzej Buller, Marek Perkowski

Electrical and Computer Engineering Faculty Publications and Presentations

This paper presents a new approach to reversible cascade evolution based on a 3D cellular automaton. As a research platform we used the ATR's CAMBrain Machine (CBM). Reversible circuits are investigated because they are expected to dissipate much less energy than their irreversible counterparts. One day they will be implemented as nano-scale 3-dimensional chips. A circuit is reversible if the number of its inputs equals the number of its outputs and there is a one-to-one mapping between spaces of input vectors and output vectors. This paper provides: (1) a brief introduction to reversible logic concentrating on definitions and properties of …

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Analytical Ise Calculation And Optimum Control System Design, Tony Kealy, Aidan O'Dwyer Jul 2003

Analytical Ise Calculation And Optimum Control System Design, Tony Kealy, Aidan O'Dwyer

Conference papers

Abstract – In control system theory, a performance index is a quantitative measure of the performance of a system and is chosen so that emphasis is given to the important system parameters. In this paper, the authors demonstrate two methods to determine analytically the Integral of the Square of the Error (ISE) performance index value for a first-order-plus-dead-time (FOPDT) process model under PI control. The ability of proportional/integral (PI) and proportional/integral/derivative (PID) controllers to compensate most practical industrial processes has led to their wide acceptance in industrial applications. The most direct way to set up PI/PID controller parameters is the …

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Optical Communications By Frequency Content Of Femtosecond Laser Pulses, Dennis Alexander, Mark L. Rohlfs Jun 2003

Optical Communications By Frequency Content Of Femtosecond Laser Pulses, Dennis Alexander, Mark L. Rohlfs

Department of Electrical and Computer Engineering: Faculty Publications

A free-space optical communications System is provided capable of transmitting data over long distances through the atmosphere. The communications System according to the present invention comprises an optical transmitter at a first location, the optical transmitter comprising a femtosecond pulsed laser Source for producing a train of femtosecond laser pulses. The optical transmitter further comprises a laser pulse width modulator to provide a pulse width modulated train of femtosecond laser pulses corresponding to the data being transmitted. The communications System further com prises an optical receiver at a Second location for receiving the modulated train of femtosecond laser pulses. The …

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Actuator Fault Compensation For A Helicopter Model, Xiao-Hua Yu Jun 2003

Actuator Fault Compensation For A Helicopter Model, Xiao-Hua Yu

Electrical Engineering

A fault-tolerant system is the one that can continue its operation without significant impact on performance in the presence of hardware and/or software errors. In this paper, the design of a fault-tolerant flight controller to control UH-60 helicopter is investigated. A 9th-order state space representation of the helicopter model operating at the forward mode with 80 knots is presented; then a fault-tolerant optimal feedback controller is designed and tested.

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Apparatus, Method And System For Common-Mode Stabilization In Circuits Having Differential Operation, George Palaskas, Vladimir Prodanov Jun 2003

Apparatus, Method And System For Common-Mode Stabilization In Circuits Having Differential Operation, George Palaskas, Vladimir Prodanov

Electrical Engineering

A system, method and apparatus are disclosed for common-mode voltage feedback. The preferred system includes a plurality of differential circuits, a corresponding plurality of common-mode voltage detectors, a corresponding plurality of buffer circuits, and a common-mode control circuit. Each differential circuit is operative to produce a first differential output voltage and a second differential output voltage. Each corresponding common-mode voltage detector is operative to provide a common-mode voltage from the first differential output voltage and the second differential output voltage. The common-mode control circuit provides a control voltage signal from the common-mode voltage and from a reference voltage. Each buffer …

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Aircraft Turbofan Engine Health Estimation Using Constrained Kalman Filtering, Daniel J. Simon, D. L. Simon Jun 2003

Aircraft Turbofan Engine Health Estimation Using Constrained Kalman Filtering, Daniel J. Simon, D. L. Simon

Electrical and Computer Engineering Faculty Publications

No abstract provided.

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Improving Learning Implicit User Interest Hierarchy With Variable Length Phrases, Hyoung-Rae Kim, Philip K. Chan Jun 2003

Improving Learning Implicit User Interest Hierarchy With Variable Length Phrases, Hyoung-Rae Kim, Philip K. Chan

Electrical Engineering and Computer Science Faculty Publications

A continuum of general to specific interests of a user called a user interest hierarchy (UIH) represents a user's interests at different abstraction levels. A UIH can be learned from a set of web pages visited by a user. In this paper, we focus on improving learning the UIH by adding phrases. We propose the VPF algorithm that can find variable length phrases without any user-defined parameter. To identify meaningful phrases, we examine various correlation functions with respect to well-known properties and other properties that we propose.

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Boundary Detection In Tokenizing Network Application Payload For Anomaly Detection, Rachna Vargiya, Philip K. Chan Jun 2003

Boundary Detection In Tokenizing Network Application Payload For Anomaly Detection, Rachna Vargiya, Philip K. Chan

Electrical Engineering and Computer Science Faculty Publications

Most of the current anomaly detection methods for network traffic rely on the packet header for studying network traffic behavior. We believe that significant information lies in the payload of the packet and hence it is important to model the payload as well. Since many protocols exist and new protocols are frequently introduced, parsing the payload based on the protocol specification is time-consuming. Instead of relying on the specification, we propose four different characteristics of streams of bytes, which can help us develop algorithms for parsing the payload into tokens. We feed the extracted tokens from the payload to anomaly …

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Determining The Number Of Clusters/Segments In Hierarchical Clustering/Segmentation Algorithms, Stan Salvador, Philip K. Chan Jun 2003

Determining The Number Of Clusters/Segments In Hierarchical Clustering/Segmentation Algorithms, Stan Salvador, Philip K. Chan

Electrical Engineering and Computer Science Faculty Publications

We investigate techniques to automatically determine the number of clusters to return from hierarchical clustering and segmentation algorithms. We propose an efficient algorithm, the L Method, that finds the "knee" in a '# of clusters vs. clustering evaluation metric' graph. Using the knee is well-known but is not a particularly well-understood method to determine the number of clusters. We explore the feasibility of this method, and attempt to determine in which situations it will and will not work.

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Identifying Outliers Via Clustering For Anomaly Detection, Muhammad H. Arshad, Philip K. Chan Jun 2003

Identifying Outliers Via Clustering For Anomaly Detection, Muhammad H. Arshad, Philip K. Chan

Electrical Engineering and Computer Science Faculty Publications

Detecting known vulnerabilities (Signature Detection) is not sufficient for complete security. This has raised recent interest in Anomaly Detection (AD), in which a model is built from normal behavior and significant deviations from this model are flagged anomalous. However, most AD algorithm assume clean training data, which could be hard to obtain. Our proposed algorithm relaxes. For this, we define the notion a strong outlier, which is suspicious at both local and global levels. Finally we illustrate the effectiveness of our approach on the DARPA '99 dataset and find that our approach is at par in number of detections at …

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Learning Rules From System Call Arguments And Sequences For Anomaly Detection, Guarav Tandon, Philip K. Chan Jun 2003

Learning Rules From System Call Arguments And Sequences For Anomaly Detection, Guarav Tandon, Philip K. Chan

Electrical Engineering and Computer Science Faculty Publications

Many approaches have been suggested and various systems have been modeled to detect intrusions from anomalous behavior of systems calls as a result of an attack. Though these techniques have been shown to be quite effective, a key element seems to be missing -- the inclusion and utilization of the system call arguments to create a richer, more valuable signature and to use this information to model the intrusion detection system more accurately. We put forth the idea of adopting a rule learning approach that mobilizes rules based upon system calls and models the system for normal traffic using system …

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A Neuromorphic Controller For A Distillation Column, Xiao-Hua Yu Jun 2003

A Neuromorphic Controller For A Distillation Column, Xiao-Hua Yu

Electrical Engineering

This paper investigates the design of a neural network based controller to control the concentration of the overhead and bottom product in the model of a distillation column. Satisfactory computer simulation results of this approach are obtained.

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Cmos Transconductor With Increased Dynamic Range, Vladimir I. Prodanov Jun 2003

Cmos Transconductor With Increased Dynamic Range, Vladimir I. Prodanov

Electrical Engineering

A CMOS transconductor that operates with increased dynamic range while maintaining one or more other basic operating characteristics at substantially the same value in comparison to a prior art transconductor circuit is provided. One embodiment, among others, comprises an input stage circuit comprising several pluralities of transistors with each plurality configured such that certain terminals of the transistors are electrically connected, and the several pluralities are electrically interconnected through one or more terminals of each plurality. Another embodiment comprises modifying an input stage of an existing transconductor circuit to provide a transconductor circuit that operates with increased dynamic range while …

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Modeling, Fabrication, And Optimization Of Niobium Cavities: Phase Ii Final Report, Robert A. Schill Jr., Mohamed Trabia, William Culbreth Jun 2003

Modeling, Fabrication, And Optimization Of Niobium Cavities: Phase Ii Final Report, Robert A. Schill Jr., Mohamed Trabia, William Culbreth

Transmutation Sciences Materials (TRP)

Niobium cavities are important parts of the integrated NC/SC high-power linacs. Over the years, researchers in several countries have tested various cavity shapes. They concluded that elliptically shaped cells are the most appropriate shape for superconducting cavities. The need for very clean surfaces lead to the use of a buffered chemical polishing produce for surface cleaning to get good performance of the cavities. The second phase has resulted in an experimental setup of a fluid flow experiment with experimentation to be completed in the third year. Some of these results were presented at American Nuclear Society, Student Conference April 2-5, …

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Modified Sagnac Experiment For Measuring Travel-Time Difference Between Counter-Propagating Light Beams In A Uniformly Moving Fiber, Yi Zheng, Aiping Yao, Ruyong Wang, Dean Langley Jun 2003

Modified Sagnac Experiment For Measuring Travel-Time Difference Between Counter-Propagating Light Beams In A Uniformly Moving Fiber, Yi Zheng, Aiping Yao, Ruyong Wang, Dean Langley

Electrical and Computer Engineering Faculty Publications

A fiber optic conveyor has been developed for investigating the travel-time difference between two counter-propagating light beams in uniformly moving fiber. Our finding is that there is a travel-time difference Δt = 2vΔl/c2 in a fiber segment of length Δl moving with the source and detector at a speed v, whether the segment is moving uniformly or circularly.

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An Investigation Into Non-Verbal Sound-Based Modes Of Human-To-Computer Communication With Rehabilitation Applications, Ted Burke Jun 2003

An Investigation Into Non-Verbal Sound-Based Modes Of Human-To-Computer Communication With Rehabilitation Applications, Ted Burke

Conference Papers

During the course of our work in the National Rehabilitation Hospital in Ireland we have encountered patients who, while unable to speak, are capable of making reproducible utterances. We present techniques used to harness such utterances, in addition to whistling, as a means of communication and control. A simple technique for identifying the phonemes /o/ and /s/ (in single-symbol ARPAbet notation) is presented with applications. The use of pitch variation as a means of controlling a continuously variable parameter is described with two applications - a microcontroller based light dimmer switch and a computer program which facilitates mouse pointer control. …

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A Software Debugger Interface For An 8051 Hardware Model, Lokesh Verma, Hardy J. Pottinger, Daryl G. Beetner Jun 2003

A Software Debugger Interface For An 8051 Hardware Model, Lokesh Verma, Hardy J. Pottinger, Daryl G. Beetner

Electrical and Computer Engineering Faculty Research & Creative Works

A VHDL model of the 8051 microcontroller is a key component for a course in hardware-software codesign, in its second year of development at University of Missouri-Rolla. Our paper discusses a software-centric user interface developed for this model using Tcl/Tk. preliminary experience with using the debugger in an undergraduate laboratory is discussed.

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Pulse Train™, A Novel Digital Control Method, Applied To A Discontinuous Conduction Mode Flyback Converter, Mark Telefus, Anatoly Shteynberg, Mehdi Ferdowsi, Ali Emadi Jun 2003

Pulse Train™, A Novel Digital Control Method, Applied To A Discontinuous Conduction Mode Flyback Converter, Mark Telefus, Anatoly Shteynberg, Mehdi Ferdowsi, Ali Emadi

Electrical and Computer Engineering Faculty Research & Creative Works

Pulse TrainTM, a new digital control technique for DC-DC converters is introduced and applied to a Flyback converter operating in discontinuous conduction mode (DCM). In contrast to the conventional analog control methods, the principal idea of this new algorithm is to use real time analysis. The proposed technique is appropriate for any converter operating in DCM. However, this work mainly focuses on Flyback converter. In this paper, the main mathematical concept of the new control algorithm is introduced and simulations as well as experimental results are presented.

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Cooperative Path Planning For Timing Critical Missions, Timothy W. Mclain, Randal W. Beard Jun 2003

Cooperative Path Planning For Timing Critical Missions, Timothy W. Mclain, Randal W. Beard

Faculty Publications

This paper presents a cooperative path planning approach for teams of vehicles operating under timing constraints. A cooperative control approach based on coordination variables and coordination functions is introduced and applied to cooperative timing problems. Three types of timing constraints are considered: simultaneous arrival, tight sequencing, and loose sequencing. Simulation results demonstrating the approach are presented.

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Thermal Management Of Algan-Gan Hfets On Sapphire Using Flip-Chip Bonding With Epoxy Underfill, Jie Sun, H. Fatima, Alexei Koudymov, A. Chitnis, X. Hu, H.-M Wang, J. Zhang, Grigory Simin, J. Yang, Asif Khan Jun 2003

Thermal Management Of Algan-Gan Hfets On Sapphire Using Flip-Chip Bonding With Epoxy Underfill, Jie Sun, H. Fatima, Alexei Koudymov, A. Chitnis, X. Hu, H.-M Wang, J. Zhang, Grigory Simin, J. Yang, Asif Khan

Faculty Publications

Self-heating imposes the major limitation on the output power of GaN-based HFETs on sapphire or SiC. SiC substrates allow for a simple device thermal management scheme; however, they are about a factor 20-100 higher in cost than sapphire. Sapphire substrates of diameters exceeding 4 in are easily available but the heat removal through the substrate is inefficient due to its low thermal conductivity. The authors demonstrate that the thermal impedance of GaN based HFETs over sapphire substrates can be significantly reduced by implementing flip-chip bonding with thermal conductive epoxy,underfill. They also show that in sapphire-based flip-chip mounted devices the heat …

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