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Electrical and Computer Engineering Faculty Research & Creative Works

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Articles 2311 - 2340 of 3518

Full-Text Articles in Engineering

A General Purpose Framework For Wireless Sensor Network Applications, Ayman Z. Faza, Sahra Sedigh Sep 2006

A General Purpose Framework For Wireless Sensor Network Applications, Ayman Z. Faza, Sahra Sedigh

Electrical and Computer Engineering Faculty Research & Creative Works

Wireless sensor networks are becoming a basis for a rapidly increasing range of applications. Habitat, flood, and wildfire monitoring are interesting examples of such applications. Each application has different requirements in terms of node functionalities, network size, complexity and cost; therefore, it is worthwhile time investment to design and implement a general purpose framework for wireless sensor networks that would be adaptable to any monitoring application of interest with a minimum amount of effort. In this manuscript, we propose a basic structure for such a framework and highlight a number of challenges anticipated during the course of this doctoral research.

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An Autonomous And Adaptable Wireless Device For Flood Monitoring, Valerio Plessi, Filippo Bastianini, Sahra Sedigh Sep 2006

An Autonomous And Adaptable Wireless Device For Flood Monitoring, Valerio Plessi, Filippo Bastianini, Sahra Sedigh

Electrical and Computer Engineering Faculty Research & Creative Works

Wireless devices can be used to monitor and record a broad range of phenomena. Their advantages include ease of installation and maintenance and considerable reduction in wiring costs. The addition of battery power and radio communication to such wireless devices can result in a completely The operating environment of monitoring systems is often hostile, due to temperature fluctuations, humidity, electromagnetic noise, and other interfering phenomena. The system should be able to adapt to changing conditions to maintain dependability in its operations This paper presents the case study of adapting a flood detection device to the environmental threat of submersion.

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Trustworthy Computing Needs, Ann K. Miller Sep 2006

Trustworthy Computing Needs, Ann K. Miller

Electrical and Computer Engineering Faculty Research & Creative Works

The very label "critical infrastructure" implies that such systems are important. They are. Within the US alone, there are approximately 28,600 networked Federal Deposit Insurance Corporation (FDIC) institutions, 2 million miles of oil/gas pipelines, 2,800 power plants with 300,000 production sites, 104 nuclear power plants, 80,000 dams, 60,000 chemical plants, 87,000 food processing plants, and 1,600 water treatment plants. And, this is just part of our national infrastructure. Add to this telecommunications and other "everyday" utilities and the scope is enormous. Most of these systems, alone, would qualify as a network-centric system; that is, a system of systems (SoS) whose …

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Dynamic Maximum Power Point Tracking Of Photovoltaic Arrays Using Ripple Correlation Control, Trishan Esram, Jonathan W. Kimball, Philip T. Krein, Patrick L. Chapman, Pallab Midya Sep 2006

Dynamic Maximum Power Point Tracking Of Photovoltaic Arrays Using Ripple Correlation Control, Trishan Esram, Jonathan W. Kimball, Philip T. Krein, Patrick L. Chapman, Pallab Midya

Electrical and Computer Engineering Faculty Research & Creative Works

A dynamically rapid method used for tracking the maximum power point of photovoltaic arrays, known as ripple correlation control, is presented and verified against experiment. The technique takes advantage of the signal ripple, which is automatically present in power converters. The ripple is interpreted as a perturbation from which a gradient ascent optimization can be realized. The technique converges asymptotically at maximum speed to the maximum power point without the benefit of any array parameters or measurements. The technique has simple circuit implementations.

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New Double Input Dc-Dc Converters For Automotive Applications, Krishna P. Yalamanchili, Mehdi Ferdowsi, Keith Corzine Sep 2006

New Double Input Dc-Dc Converters For Automotive Applications, Krishna P. Yalamanchili, Mehdi Ferdowsi, Keith Corzine

Electrical and Computer Engineering Faculty Research & Creative Works

The energy storage unit is one of the most important subsystems in the structure of hybrid electric vehicles since it directly impacts the performance, fuel economy, cost, and weight of the vehicle. New structures for the energy storage unit, which utilize both batteries and ultracapacitors, are widely under investigation. In order to fully utilize the advantages of each energy storage device, employment of multi-input power converters is inevitable. In this paper, two new double input converters are introduced. Their different operating modes are analyzed and their voltage transfer ratios are derived. Simulation results are used to verify the expected operational …

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Oxidase-Coupled Amperometric Glucose And Lactate Sensors With Integrated Electrochemical Actuation System, Jongwon Park, Chang-Soo Kim, Minsu Choi Aug 2006

Oxidase-Coupled Amperometric Glucose And Lactate Sensors With Integrated Electrochemical Actuation System, Jongwon Park, Chang-Soo Kim, Minsu Choi

Electrical and Computer Engineering Faculty Research & Creative Works

Unpredictable baseline drift and sensitivity degradation during continuous use are two of the most significant problems of biosensors including the amperometric glucose and lactate sensors. Therefore, the capability of on-demand in situ calibration/diagnosis of biochemical sensors is indispensable for reliable long-term monitoring with minimum attendance. Another limitation of oxidase enzyme-based biosensors is the dependence of enzyme activity on the background oxygen concentration in sample solution. In order to address these issues, the electrolytic generation of oxygen and hydrogen bubbles were utilized 1) to overcome the background oxygen dependence of glucose and lactate sensors and 2) to demonstrate the feasibility of …

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Matched Filter Detection And Identification Of Electronic Circuits Based On Their Unintentional Radiated Emissions, Ahmed Shaik, Haixiao Weng, Xiaopeng Dong, Todd H. Hubing, Daryl G. Beetner Aug 2006

Matched Filter Detection And Identification Of Electronic Circuits Based On Their Unintentional Radiated Emissions, Ahmed Shaik, Haixiao Weng, Xiaopeng Dong, Todd H. Hubing, Daryl G. Beetner

Electrical and Computer Engineering Faculty Research & Creative Works

This paper describes a method for detecting electronic circuits based on their unintentional electromagnetic emissions. This concept can be applied to help find hidden electronic devices such as video cameras, active microphones, timers and computers.

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Microwave Quantitative Nde Technique For Dielectric Slab Thickness Estimation Using The Music Algorithm, Mohamed A. Abou-Khousa, R. Zoughi Aug 2006

Microwave Quantitative Nde Technique For Dielectric Slab Thickness Estimation Using The Music Algorithm, Mohamed A. Abou-Khousa, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

Non-invasive monitoring of dielectric slab thickness is of great interest in various industrial applications. This paper focuses on estimating the thickness of dielectric slabs, and consequently monitoring their variations, utilizing wideband microwave signals and the MUtiple SIgnal Characterization (MUSIC) algorithm. The performance of the proposed approach is assessed by validating simulation results with laboratory experiments. The results clearly indicate the utility of this overall approach for accurate dielectric slab thickness evaluation.

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Numerical Analysis Of Sandwiched Composite-Fss Structures, Rui Qiang, Ji Chen, Jingyu Huang, Marina Koledintseva, Richard E. Dubroff, James L. Drewniak, Fan Yang Aug 2006

Numerical Analysis Of Sandwiched Composite-Fss Structures, Rui Qiang, Ji Chen, Jingyu Huang, Marina Koledintseva, Richard E. Dubroff, James L. Drewniak, Fan Yang

Electrical and Computer Engineering Faculty Research & Creative Works

A numerical technique to analyze shielding effectiveness of sandwiched FSS-composite structures is proposed. This technique is based on using a dispersive FDTD method in conjuncture with a novel periodic boundary condition to model sandwiched FSS-composite elements. Results show that by inserting single or multilayered FSS elements into composite materials, better shielding effectiveness can be achieved.

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Characterizing Package/Pcb Pdn Interactions From A Full-Wave Finite-Difference Formulation, Shishuang Sun, David Pommerenke, James L. Drewniak, Kai Xiao, Sin-Ting Chen, Tzong-Lin Wu Aug 2006

Characterizing Package/Pcb Pdn Interactions From A Full-Wave Finite-Difference Formulation, Shishuang Sun, David Pommerenke, James L. Drewniak, Kai Xiao, Sin-Ting Chen, Tzong-Lin Wu

Electrical and Computer Engineering Faculty Research & Creative Works

A novel approach of equivalent circuit model extraction is developed for modeling of integrated package and PCB power distribution networks (PDN). The integrated PDNs are formulated from a full-wave finite-difference algorithm, and the resulting matrix equations are converted to equivalent circuits. The equivalent circuits, as well as the decoupling capacitors and the attached circuit components, can be analyzed with a SPICE-like solver in both the time and frequency domains. The modeling of dielectric loss is also addressed. The method is used to model three PDN problems including a simple power bus, a BGA package mounting on a PCB, and a …

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Common-Mode Radiation Resulting From Hand-Assembled Cable Bundles On Automotive Platforms, Shishuang Sun, James L. Drewniak, David Pommerenke Aug 2006

Common-Mode Radiation Resulting From Hand-Assembled Cable Bundles On Automotive Platforms, Shishuang Sun, James L. Drewniak, David Pommerenke

Electrical and Computer Engineering Faculty Research & Creative Works

A statistical cable harness model is developed to account for the random disturbance of the wire positions along hand-assembled bundles. The non-uniform random bundles are modeled as n-cascaded segments of uniform multi-conductor transmission line. At each section, all wire positions are disturbed with random numbers obeying a Gaussian distribution. In addition, a spline interpolation function is used to improve the smoothness of wires winding along the bundle. The common-mode current distribution along the bundle calculated with SPICE is injected into a full-wave tool, e.g., FDTD, as impressed current sources. Thus, the full-vehicle electromagnetic emissions from the automotive harness can …

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Microwave Reflectometry As A Novel Diagnostic Tool For Detection Of Skin Cancers, Pratik Mehta, Kundan Chand, Deepak Narayanswamy, Daryl G. Beetner, R. Zoughi, William V. Stoecker Aug 2006

Microwave Reflectometry As A Novel Diagnostic Tool For Detection Of Skin Cancers, Pratik Mehta, Kundan Chand, Deepak Narayanswamy, Daryl G. Beetner, R. Zoughi, William V. Stoecker

Electrical and Computer Engineering Faculty Research & Creative Works

More than 1 000 000 people are diagnosed with skin cancer each year in the United States, and more than 10 000 people die from the disease. Methods such as visual inspection and dermoscopy are available for early detection of skin cancers, but improvement in accuracy is needed. This paper investigates the use of microwave reflectometry as a potential diagnostic tool for detection of skin cancers. Open-ended coaxial probes were used to measure microwave properties of skin. The influences of measurement parameters such as probe application pressure, power level, and variation in reflection properties of skin with location and hydration …

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Application Of Chip-Level Emc In Automotive Product Design, Kuifeng Hu, H. Weng, Daryl G. Beetner, David Pommerenke, James L. Drewniak, K. Lavery, Jason Whiles Aug 2006

Application Of Chip-Level Emc In Automotive Product Design, Kuifeng Hu, H. Weng, Daryl G. Beetner, David Pommerenke, James L. Drewniak, K. Lavery, Jason Whiles

Electrical and Computer Engineering Faculty Research & Creative Works

Integrated circuits (ICs) are often the source of the high-frequency noise that drives electromagnetic emissions from electronic products. A case study is presented where emissions from a printed circuit board containing an automotive microcontroller are reduced significantly through analysis of the coupling mechanisms from the chip to the board and attached cables. Noise generated by the IC is explored through measurements in a semi-anechoic chamber and TEM cell, through near-field scans, and through modifications to the printed circuit board. Noise is driven by the IC through both power and I/O connections. Results show that a ferrite in series with I/O …

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High Resolution Millimeter Wave Detection Of Vertical Cracks In The Space Shuttle External Tank Spray-On-Foam Insulation (Sofi), Sergey Kharkovsky, R. Zoughi, F. L. Hepburn Aug 2006

High Resolution Millimeter Wave Detection Of Vertical Cracks In The Space Shuttle External Tank Spray-On-Foam Insulation (Sofi), Sergey Kharkovsky, R. Zoughi, F. L. Hepburn

Electrical and Computer Engineering Faculty Research & Creative Works

Space Shuttle Columbia's catastrophic failure, the separation of a piece of spray-on-foam insulation (SOFI) from the external tank (ET) in the Space Shuttle Discovery's flight in 2005 and crack detected in its ET foam prior to its successful launch in 2006 emphasize the need for effective nondestructive methods for inspecting the shuttle ET SOFI. Millimeter wave nondestructive testing methods have been considered as potential and effective inspection tools for evaluating the integrity of the SOFI. This paper presents recent results of an investigation for the purpose of detecting vertical cracks in SOFI panels using a focused millimeter wave (150 GHz) …

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Cascaded Multilevel Converters With Non-Integer Or Dynamically Changing Dc Voltage Ratios, Shuai Lu, Keith Corzine Aug 2006

Cascaded Multilevel Converters With Non-Integer Or Dynamically Changing Dc Voltage Ratios, Shuai Lu, Keith Corzine

Electrical and Computer Engineering Faculty Research & Creative Works

Multilevel converters made of cascaded cells (MCCC) offer a high number of voltage levels with a given switch count. Many variants of the MCCC topology have been introduced over years. Mostly, only integer DC voltage ratios between the cascaded converter cells have been applied to its PWM modulation. This is mainly due to the non-uniform distribution of voltage vectors with the non-integer DC ratios. It poses difficulty to the conventional SVM modulators relying on locating the equilateral "triangle" made of three nearest vectors enclosing the reference vector. In this paper, an original modulation method is introduced to operate with any …

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Predicting Tem Cell Measurements From Near Field Scan Data, Haixiao Weng, Daryl G. Beetner, Richard E. Dubroff Aug 2006

Predicting Tem Cell Measurements From Near Field Scan Data, Haixiao Weng, Daryl G. Beetner, Richard E. Dubroff

Electrical and Computer Engineering Faculty Research & Creative Works

A procedure is proposed for predicting TEM cell measurements from near field scans by modeling near-field scan data using equivalent sources. The first step in this procedure is to measure the tangential electric and magnetic fields over the circuit. Electric and magnetic fields are estimated from probe measurements by compensating for the characteristics of the probe. An equivalent magnetic and electric current model representing emissions is then generated from the compensated fields. These equivalent sources are used as an impressed source in an analytical formula or full wave simulation to predict measurements within the TEM cell. Experimental verification of the …

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Signal Link-Path Characterization Up To 20 Ghz Based On A Stripline Structure, Jianmin Zhang, James L. Drewniak, David Pommerenke, Richard E. Dubroff, Zhiping Yang, Wheling Cheng, John C. Fisher, Sergio Camerlo Aug 2006

Signal Link-Path Characterization Up To 20 Ghz Based On A Stripline Structure, Jianmin Zhang, James L. Drewniak, David Pommerenke, Richard E. Dubroff, Zhiping Yang, Wheling Cheng, John C. Fisher, Sergio Camerlo

Electrical and Computer Engineering Faculty Research & Creative Works

Dielectric properties and losses are two critical issues in signal link-path characterization. To obtain the substrate dielectric properties for a planar transmission line, an analytical solution is derived and validated based on a stripline structure and measured scattering parameters with TRL de-embedding. The characterized dielectric property is used to evaluate dielectric loss and conductor loss. The total loss is thereby found from their summation. The calculated total loss is compared to the measured total loss, and the conductor loss and dielectric loss are then quantifiable. Since the conventional description using the loss tangent and dielectric constant to represent material properties …

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Influence Of An Extended Stub At Connector Ports On Signal Launches And Trl De-Embedding, Jianmin Zhang, James L. Drewniak, David Pommerenke, Bruce Archambeault, Zhiping Yang, Wheling Cheng, John Fisher, Sergio Camerlo Aug 2006

Influence Of An Extended Stub At Connector Ports On Signal Launches And Trl De-Embedding, Jianmin Zhang, James L. Drewniak, David Pommerenke, Bruce Archambeault, Zhiping Yang, Wheling Cheng, John Fisher, Sergio Camerlo

Electrical and Computer Engineering Faculty Research & Creative Works

Characterization of PCBs (Printed Circuit Boards) is usually associated with measurement using a VNA (Vector Network Analyzer) in the frequency-domain or a TDR (Time Domain Reflectometer) in the time-domain. The often used signal launch techniques on PCBs based on the VNA or TDR measurement in the microwave frequency range use SMA or 3.5 mm connectors, in edge-launch or vertical-launch fashions. The signal transition between the launch port and the DUT (Device Under Test) introduces errors in the measurement, which is dominant when compared with a transmission line itself on the PCB as the technologies of PCB manufacturing well developed today. …

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Engineering Of Ferrite-Graphite Composite Media For Microwave Shields, Marina Koledintseva, Poorna Chander Ravva, James L. Drewniak, Alexander A. Kitaytsev, Andrey A. Shinkov Aug 2006

Engineering Of Ferrite-Graphite Composite Media For Microwave Shields, Marina Koledintseva, Poorna Chander Ravva, James L. Drewniak, Alexander A. Kitaytsev, Andrey A. Shinkov

Electrical and Computer Engineering Faculty Research & Creative Works

An electromagnetic shielding of objects using ferrite-graphite composites is considered. The analytical model, using the Maxwell Garnett formulation for multiphase mixtures, results of computations based on this model and plane-wave formulation, and some experimental results are represented.

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A Method For Charactering Emi Coupling Paths And Source Properties In Complex Systems, Shishuang Sun, Gang Feng, Chong Ding, David Pommerenke, James L. Drewniak Aug 2006

A Method For Charactering Emi Coupling Paths And Source Properties In Complex Systems, Shishuang Sun, Gang Feng, Chong Ding, David Pommerenke, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

A method for charactering EMI coupling paths in complex systems is presented. While it is relatively easy to determine the EMI antenna structures or the sources of EMI, it is often quite difficult to identify, and even more difficult to quantify coupling paths. This paper introduces a measurement-based method to quantify EMI coupling paths, and the source strengths can be indirectly determined by applying linear system theory. Circuit design guidelines, e.g., the permissible even-mode current in a differential signal, can be derived with the knowledge of the coupling path and EMI limits. Moreover, the EMI can be better predicted with …

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Comparison Of X-Ray, Millimeter Wave, Shearography And Through-Transmission Ultrasonic Methods For Inspection Of Honeycomb Composites, Mohamed A. Abou-Khousa, Adam C. Ryley, Sergey Kharkovsky, R. Zoughi, David J. Daniels, Nicholas A. Kreitinger, Gary J. Steffes Aug 2006

Comparison Of X-Ray, Millimeter Wave, Shearography And Through-Transmission Ultrasonic Methods For Inspection Of Honeycomb Composites, Mohamed A. Abou-Khousa, Adam C. Ryley, Sergey Kharkovsky, R. Zoughi, David J. Daniels, Nicholas A. Kreitinger, Gary J. Steffes

Electrical and Computer Engineering Faculty Research & Creative Works

Honeycomb composites are increasingly finding utility in a variety of environments and applications, such as aircraft structural components, flight control components, radomes, etc. In-service and environmental stresses can produce unwanted flaws that adversely affect the structural integrity and functionality of these composites. These flaws may be in the forms of disbonds, delaminations, impact damage, crushed honeycomb, moisture intrusion, internal cracks, etc. There are several nondestructive testing (NDT) methods that may be used to inspect these composites for the presence and evaluation of these flaws. Such NDT methods include X-ray computed tomography, near-field millimeter wave, shearography, and ultrasonic testing. To assess …

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Optimal Statcom Sizing And Placement Using Particle Swarm Optimization, J. C. Hernandez, Ganesh K. Venayagamoorthy, Yamille Del Valle, Ronald G. Harley Aug 2006

Optimal Statcom Sizing And Placement Using Particle Swarm Optimization, J. C. Hernandez, Ganesh K. Venayagamoorthy, Yamille Del Valle, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

Heuristic approaches are traditionally applied to find the size and location of Flexible AC Transmission Systems (FACTS) devices in a small power system. Nevertheless, more sophisticated methods are required for placing them in a large power network. Recently, the Particle Swarm Optimization (PSO) technique has been applied to solve power engineering optimization problems giving better results than classical methods. This paper shows the application of PSO for optimal sizing and allocation of a Static Compensator (STATCOM) in a power system. A 45 bus system (part of the Brazilian power network) is used as an example to illustrate the technique. Results …

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An Alternative Target Density Function For Radar Imaging, Askin Demirkol, Levent Acar, Robert S. Woodley, Erol Emre Aug 2006

An Alternative Target Density Function For Radar Imaging, Askin Demirkol, Levent Acar, Robert S. Woodley, Erol Emre

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, an alternative Target Density Function (TDF) is proposed to image the radar targets in a dense target environment. It is produced by wavelet theory considering a new range and angle plane different from the conventional methods. It is shown that Wavelet theory can be used as approach to imaging by active sensors by transmitting a waveform which is a kernel for this transform such as a window function. Although the imaging is obtained via the phased array radars, the problem associated with beamforming in linear phased array radar system is bypassed in this new algorithm.

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Millimeter-Wave Detection Of Localized Anomalies In The Space Shuttle External Fuel Tank Insulating Foam, Sergey Kharkovsky, R. Zoughi, J. T. Case, Mohamed A. Abou-Khousa, F. L. Hepburn Jul 2006

Millimeter-Wave Detection Of Localized Anomalies In The Space Shuttle External Fuel Tank Insulating Foam, Sergey Kharkovsky, R. Zoughi, J. T. Case, Mohamed A. Abou-Khousa, F. L. Hepburn

Electrical and Computer Engineering Faculty Research & Creative Works

The Space Shuttle Columbia's catastrophic accident emphasizes the growing need for developing and applying effective, robust, and life-cycle-oriented nondestructive testing (NDT) methods for inspecting the shuttle external fuel tank spray on foam insulation (SOFI). Millimeter-wave NDT techniques were one of the methods chosen for evaluating their potential for inspecting these structures. Several panels with embedded anomalies (mainly voids) were produced and tested for this purpose. Near-field and far-field millimeter-wave NDT methods were used for producing images of the anomalies in these panels. This paper presents the results of an investigation for the purpose of detecting localized anomalies in several SOFI …

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Neural Network Based Decentralized Excitation Control Of Large Scale Power Systems, Wenxin Liu, Ganesh K. Venayagamoorthy, Donald C. Wunsch, David A. Cartes, Jagannathan Sarangapani Jul 2006

Neural Network Based Decentralized Excitation Control Of Large Scale Power Systems, Wenxin Liu, Ganesh K. Venayagamoorthy, Donald C. Wunsch, David A. Cartes, Jagannathan Sarangapani

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents a neural network (NN) based decentralized excitation controller design for large scale power systems. The proposed controller design considers not only the dynamics of generators but also the algebraic constraints of the power flow equations. The control signals are calculated using only local signals. The transient stability and the coordination of the subsystem controllers can be guaranteed. NNs are used to approximate the unknown/imprecise dynamics of the local power system and the interconnections. All signals in the closed loop system are guaranteed to be uniformly ultimately bounded (UUB). Simulation results with a 3-machine power system demonstrate the …

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Cost-Driven Repair Of A Nanowire Crossbar Architecture, Yadunandana Yellambalase, Shanrui Zhang, Minsu Choi, Nohpill Park, Fabrizio Lombardi Jul 2006

Cost-Driven Repair Of A Nanowire Crossbar Architecture, Yadunandana Yellambalase, Shanrui Zhang, Minsu Choi, Nohpill Park, Fabrizio Lombardi

Electrical and Computer Engineering Faculty Research & Creative Works

The recent development of nanoscale materials and assembly techniques has resulting in the manufacturing of high-density computational systems. These systems consist of nanometer-scale elements and are likely to have many manufacturing imperfections (defects); thus, defect-tolerance is considered as one of the most some algorithms for repairing defective crosspoints in a nanoscale crossbar architecture; furthermore we estimate the efficiency and cost-effectiveness of each algorithm. Also, for a given design and manufacturing environment, we propose a cost-driven method to find a balanced solution by which figures of merit such as area, repair time and reconfiguration cost can be taken into account. Probabilistic …

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A Radar Sensing Algorithm By Gabor Theory, Askin Demirkol, Levent Acar, Robert S. Woodley Jul 2006

A Radar Sensing Algorithm By Gabor Theory, Askin Demirkol, Levent Acar, Robert S. Woodley

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, an alternative Target Density Function( TDF) is proposed for narrowband radar model. This is achieved by estimating a new target density function by Gabor theory. It is shown how Gabor transform can be used to obtaining wideband target density function by transmitting a waveform which is a kernel for this transform. The windowing characteristics of this theory is plausible to reaching an accurate result. The presented wideband target density function is developed in a various manner different from the conventional methods.

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An Efficient Discontinuous-Mode Model Of A Switch Pole, Jonathan W. Kimball Jul 2006

An Efficient Discontinuous-Mode Model Of A Switch Pole, Jonathan W. Kimball

Electrical and Computer Engineering Faculty Research & Creative Works

Simulating switching power supplies presents many challenges. A variety of switch pole models is available, from the physics-based to the behavioral. The present work develops and demonstrates a behavioral model that works well in discontinuous mode. The new model eliminates the extremely fast time constants normally associated with switches in a high impedance state. Simulation time is improved and fixed-time-step algorithms are now stable with reasonable step size.

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An Approach To Active Sensor Imaging, Askin Demirkol, Levent Acar, Robert S. Woodley Jul 2006

An Approach To Active Sensor Imaging, Askin Demirkol, Levent Acar, Robert S. Woodley

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, an alternative Target Density Function (TDF) is proposed to image the radar targets in a dense target environment. It is obtained by considering a novel range and scanning angle plane different from the conventional methods. An alternative method is briefly proposed for smoothing the target density function by taking advantage of Walsh functions. Although the imaging is obtained via the phased array radars, the problem associated with beamforming in linear phased array radar system is bypassed in this new algorithm.

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Hysteresis And Delta Modulation Control Of Converters Using Sensorless Current Mode, Jonathan W. Kimball, Philip T. Krein, Yongxiang Chen Jul 2006

Hysteresis And Delta Modulation Control Of Converters Using Sensorless Current Mode, Jonathan W. Kimball, Philip T. Krein, Yongxiang Chen

Electrical and Computer Engineering Faculty Research & Creative Works

Sensorless current mode (SCM) is a control formulation for dc-dc converters that results in voltage-source characteristics, excellent open-loop tracking, and near-ideal source rejection. Hysteresis and delta modulation are well-known, easy-to-construct large-signal methods for switched systems. Combining either large-signal method with SCM creates a controller that is simpler and more robust than a pulse-width modulation (PWM) based controller. The small-signal advantages of PWM-based SCM are retained and expanded to include converter response to large-signal disturbances. These approaches can be used with any converter topology over a broad range of operating conditions. In the present work, hysteresis and delta modulation SCM controllers …

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