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Articles 11701 - 11730 of 21751

Full-Text Articles in Engineering

Optimal Allocation Of A Statcom In A 45 Bus Section Of The Brazilian Power System Using Particle Swarm Optimization, J. C. Hernandez, Ganesh K. Venayagamoorthy, Yamille Del Valle, Ronald G. Harley May 2006

Optimal Allocation Of A Statcom In A 45 Bus Section Of The Brazilian Power System Using Particle Swarm Optimization, J. C. Hernandez, Ganesh K. Venayagamoorthy, Yamille Del Valle, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

This paper introduces the application of Particle Swarm Optimization (PSO) to solve the optimal allocation of a STATCOM in a 45 bus system which is part of the Brazilian power network. The criterion used in finding the optimal location is based on the voltage profile of the system, i.e. the voltage deviation at each bus, with respect to its optimum value, is minimized. In order to test the performance of the PSO algorithm in this particular application, different approaches for inertia weight are investigated; also different values of acceleration constants, number of iterations and maximum velocity are considered. A sensitivity …

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Overdistention Operation Of Cascaded Multilevel Inverters, Xiaomin Kou, Keith Corzine, M. W. Wielebski May 2006

Overdistention Operation Of Cascaded Multilevel Inverters, Xiaomin Kou, Keith Corzine, M. W. Wielebski

Electrical and Computer Engineering Faculty Research & Creative Works

In the past decade, the multilevel power converter has transitioned from an experimental concept to a standard product of many medium-voltage drive manufacturers. By utilizing small voltage steps, the multilevel topology offers higher power quality, higher voltage capability, lower switching losses, and improved electromagnetic compatibility over standard topologies. Recently, several researchers have focused on the cascaded multilevel inverter whereby two multilevel inverters are series connected to a motor load by splitting the neutral connection. The resulting performance is exceptional in terms of power quality since the overall number of voltage levels is effectively the product of the two cascaded inverters. …

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An Investigation Into The Structure And Reactivity Of Calcium-Zinc-Silicate Ionomer Glasses Using Mas-Nmr Spectroscopy, D. Boyd, Mark R. Towler, R. V. Law, R. G. Hill May 2006

An Investigation Into The Structure And Reactivity Of Calcium-Zinc-Silicate Ionomer Glasses Using Mas-Nmr Spectroscopy, D. Boyd, Mark R. Towler, R. V. Law, R. G. Hill

Chemical and Biochemical Engineering Faculty Research & Creative Works

The suitability of Glass Polyalkenoate Cements (GPCs) for orthopaedic applications is retarded by the presence in the glass phase of aluminum, a neurotoxin. Unfortunately, the aluminum ion plays an integral role in the setting process of GPCs and its absence is likely to hinder cement formation. However, the authors have previously shown that aluminum-free GPCs may be formulated based on calcium zinc silicate glasses and these novel materials exhibit significant potential as hard tissue biomaterials. However, there is no data available on the structure of these glasses. 29Si MAS-NMR, differential thermal analysis (DTA), X-ray diffraction (XRD), and network crosslink density …

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Time-Delay Neural Network Based Predictions Of Elephant Distribution In A South African Game Reserve, Parviz Palangpour, Ganesh K. Venayagamoorthy, Kevin Duffy May 2006

Time-Delay Neural Network Based Predictions Of Elephant Distribution In A South African Game Reserve, Parviz Palangpour, Ganesh K. Venayagamoorthy, Kevin Duffy

Electrical and Computer Engineering Faculty Research & Creative Works

A large portion of South Africa's elephant population can be found on small wildlife reserves. When confined to enclosed reserves the elephant densities are much higher than observed in the wild. The large nutritional demands and destructive foraging behavior of elephants threaten rare species of vegetation. If conservation management is to protect threatened species of vegetation, knowing how long elephants will stay in one area of the reserve as well as which area they will move to next is essential. The goal of this study is to train an artificial neural network to predict an elephant herd's next position in …

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Gas Holdup In Trayed Bubble Column Reactors, Javier Alvaré, Muthanna H. Al-Dahhan Apr 2006

Gas Holdup In Trayed Bubble Column Reactors, Javier Alvaré, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

The Sectionalization of Conventional Bubble Columns by Perforated Trays into Trayed Bubble Columns (TBCs) Has Much Potential in Biochemical and Petroleum Refining Processes, as an Effective Way to Improve the Gas-Liquid Contacting Efficiency and Reduce the Liquid Back mixing. in This Work, the Effects of Tray Geometry, Superficial Gas Velocity, and Superficial Liquid Velocity on the overall Gas Holdup Have Been Investigated. It Was Determined that the Trays Significantly Increase the overall Gas Holdup. the Tray Hole Diameter and Superficial Gas Velocity Were Determined to Be the Most Important Factors. © 2006 American Chemical Society.

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2nd Annual Undergraduate Research Conference Abstract Book, University Of Missouri--Rolla Apr 2006

2nd Annual Undergraduate Research Conference Abstract Book, University Of Missouri--Rolla

Undergraduate Research Conference at Missouri S&T

No abstract provided.

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Method And Apparatus For Solder-Less Attachment Of An Electronic Device To A Textile Circuit, James A. Zollo, Bonnie Bachman, Alan R. Beatty, Stephen O. Bozzpme, Nitin B. Desai, Ronald J. Kelley, Rami C. Levy Apr 2006

Method And Apparatus For Solder-Less Attachment Of An Electronic Device To A Textile Circuit, James A. Zollo, Bonnie Bachman, Alan R. Beatty, Stephen O. Bozzpme, Nitin B. Desai, Ronald J. Kelley, Rami C. Levy

Economics Faculty Research & Creative Works

A method and apparatus form electrical connections between electronic circuits and conductive threads (102, 104, 106, 108) that are interwoven into textile material (130). Electronic circuits (128), such as semiconductor dies, are connected to a carrier (132) and electrical connections (136) are made to conductive connection areas (110, 112, 114, 116) on the carrier (132). Conductive stitching (202, 204, 206, 208) provides electrical contacts for both the conductive connection areas (110, 112, 114, 116) on the carrier (132) and the conductive threads (102, 104, 106, 108) that are interwoven into the textile material (130). Optionally, a thin, flexible substrate material …

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Method For Preparation Of Nanometer Cerium-Based Oxide Particles, X.-D. Zhou, Wayne Huebner, Harlan U. Anderson Apr 2006

Method For Preparation Of Nanometer Cerium-Based Oxide Particles, X.-D. Zhou, Wayne Huebner, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

The invention comprises novel undoped and doped nanometer-scale CeO2 particles as well as a novel semi-batch reactor method for directly synthesizing the novel particles at room temperature. The powders exhibited a surface area of approximately 170 m2/g with a particle size of about 3-5 nm, and are formed of single crystal particles that are of uniform size and shape. The particles’ surface area could be decreased down to 5 m2/g, which corresponds to a particle size of 100 nm, by thermal annealing at temperatures up to 1000° C. Control over the particle size, size distribution …

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The Phase Stability Of Cerium Species In Aqueous Systems Iii. The Ce(Iii/Iv)-H2o-H2o2/O2 System Dimeric Ce(Iv) Species, Pu Yu, Thomas J. O'Keefe Apr 2006

The Phase Stability Of Cerium Species In Aqueous Systems Iii. The Ce(Iii/Iv)-H2o-H2o2/O2 System Dimeric Ce(Iv) Species, Pu Yu, Thomas J. O'Keefe

Materials Science and Engineering Faculty Research & Creative Works

Equilibria and thermodynamic data for cerium dimer species were calculated for both the Ce-H2O-O2 and Ce-H2O-H2O2 systems. It was found that Ce (IV) has a tendency to form dimers, especially when the total cerium concentration is higher than 0.001 M. There are three major soluble dimer forms considered in this paper: (CeOCe)6+,(CeOCe)(OH)5+, and (CeOCe)(OH)24+, all having very similar standard potentials (E0 Ce(IV)dimer/Ce(III)01.66∀0.02V). When they coexist in solution, the concentration ratio of the Ce (IV) dimer to Ce3+ depends on the total cerium concentrations, the …

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Semiempirical Electromagnetic Modeling Of Crack Detection And Sizing In Cement-Based Materials Using Near-Field Microwave Methods, Jagadish Nadakuduti, Genda Chen, R. Zoughi Apr 2006

Semiempirical Electromagnetic Modeling Of Crack Detection And Sizing In Cement-Based Materials Using Near-Field Microwave Methods, Jagadish Nadakuduti, Genda Chen, R. Zoughi

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Detection and characterization of cracks in cement-based materials is an integral part of damage evaluation for health monitoring of civil structures. Microwave signals are able to penetrate inside of dielectric materials (e.g., cement-based materials) and are sensitive to local, physical, geometrical, and dielectric variations in a structure. This makes microwave nondestructive testing and evaluation (NDT&E) techniques suitable for inspection and health monitoring of civil structures. Near-field microwave NDT&E techniques offer the added advantage of providing high spatial resolution, requiring simple hardware that may be portable, low power, fast, real time, and robust. Additionally, these techniques are noncontact and one-sided. Besides …

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A Time-Based Vlsi Potentiostat For Ion Current Measurements, Harpreet S. Narula, John G. Harris Apr 2006

A Time-Based Vlsi Potentiostat For Ion Current Measurements, Harpreet S. Narula, John G. Harris

Electrical and Computer Engineering Faculty Research & Creative Works

A time-based CMOS integrated potentiostatic control circuit has been designed and fabricated. The design maintains a constant bias potential between the reference and working electrodes for an amperometric chemical sensor. A technique of converting input currents into time for amperometric measurements is proposed. This technique eliminates current amplifying circuitry, reduces matching problems, and increases dynamic range while saving on area and power consumption. Redox currents ranging from 1 pA to 200 nA can be measured with a maximum nonlinearity of ±0.1% over this range. The design can be used to generate cyclic voltammograms for an electrochemical reaction by sweeping the …

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Extraction Of Dispersive Material Parameters Using Vector Network Analyzers And Genetic Algorithms, Jianmin Zhang, Marina Koledintseva, David Pommerenke, James L. Drewniak, Konstantin Rozanov, Giulio Antonini, Antonio Orlandi Apr 2006

Extraction Of Dispersive Material Parameters Using Vector Network Analyzers And Genetic Algorithms, Jianmin Zhang, Marina Koledintseva, David Pommerenke, James L. Drewniak, Konstantin Rozanov, Giulio Antonini, Antonio Orlandi

Electrical and Computer Engineering Faculty Research & Creative Works

A novel method to extract dispersive properties for dielectrics over a wide frequency range is proposed. This method is based on measuring scattering parameters for planar transmission lines and applying genetic algorithms. The scattering parameters are converted into ABCD matrix parameters. The complex propagation constant of the TEM wave inside the line is obtained from A-parameters of the ABCD matrix. For planar transmission lines, analytical or empirical formulas for dielectric loss,conductor loss, anaphase constant are known. The genetic algorithm is then used to extract the Debye parameters for the dielectric substrates. FDTD modeling is used to verify the dispersive parameter …

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Freeze-Spray Processing Of Layered Ceramic Composites (Preprint), Oratai Jongprateep, Q. Fu, A. Abbott, Fatih Dogan Apr 2006

Freeze-Spray Processing Of Layered Ceramic Composites (Preprint), Oratai Jongprateep, Q. Fu, A. Abbott, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

Thermal gradients and associated stresses are critical in designing with ceramic composites having low thermal conductivity. In order to reduce the stresses from thermal gradients, compositional gradients are employed in designing of composite structures. This study addresses development of freeze-spray process to fabricate layered ceramic structures with controlled layer thickness and microstructural development. The composites were processed by spraying of ceramic slurries with low binder content and relatively high solids loadings up to 40 vol on a cooled substrate. The frozen parts were freeze-dried and sintered at elevated temperatures. The relationship between microstructural development and thermal expansion behavior of Al …

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Automated Oxidase-Coupled Amperometric Microsensor With Integrated Electrochemical Actuation System For Continuous Sensing Of Saccharoids, Yadunandana Yellambalase, Jongwon Park, Chang-Soo Kim, Minsu Choi, Nohpill Park, Fabrizio Lombardi Apr 2006

Automated Oxidase-Coupled Amperometric Microsensor With Integrated Electrochemical Actuation System For Continuous Sensing Of Saccharoids, Yadunandana Yellambalase, Jongwon Park, Chang-Soo Kim, Minsu Choi, Nohpill Park, Fabrizio Lombardi

Electrical and Computer Engineering Faculty Research & Creative Works

Recent developments for biosensors have been mainly focused on miniaturization and exploratory use of new materials. It should be emphasized that the absence of a novel "in-situ self-calibration/diagnosis technique" that is not connected to an external apparatus is a key obstacle to the realization of a biosensor for continuous use with minimum attendance. To address this deficiency, a novel needle-type biosensor system with fully automated operations is being developed, in which a novel oxidase-coupled amperometric sensor with oxygen depleting/generating actuator is interfaced with an electrochemical instrument and a perfusion system. Labview virtual instrument has been also developed to oversee the …

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High Accuracy Disbond Thickness Estimation Scheme Employing Multiple-Frequency Near-Field Microwave Measurements, Mohamed A. Abou-Khousa, R. Zoughi Apr 2006

High Accuracy Disbond Thickness Estimation Scheme Employing Multiple-Frequency Near-Field Microwave Measurements, Mohamed A. Abou-Khousa, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

Microwave nondestructive evaluation (NDE) techniques have shown great potential for disbond detection in multi-layer dielectric structures. However, a quantitative disbond thickness estimation scheme has not been introduced yet. In this paper, we propose a maximum-likelihood (ML) disbond thickness estimation scheme utilizing multiple independent measurements obtained at different frequencies. By simulations and experiments, we show that the proposed scheme produces highly accurate disbond thickness estimates.

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Dual-Polarized Microwave Near-Field Reflectometer For Non-Invasive Inspection Of Carbon Fiber Reinforced Polymer (Cfrp) Strengthened Structures, Sergey Kharkovsky, Adam C. Ryley, Vivian Stephen, R. Zoughi Apr 2006

Dual-Polarized Microwave Near-Field Reflectometer For Non-Invasive Inspection Of Carbon Fiber Reinforced Polymer (Cfrp) Strengthened Structures, Sergey Kharkovsky, Adam C. Ryley, Vivian Stephen, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

Carbon fiber reinforced polymer (CFRP) composites are increasingly being used in strengthening structures of civil infrastructures, aerospace and automotive industries. Subsequent to the application of CFRP, detection and evaluation of the structural integrity of the member becomes a critical issue. Microwave non-invasive inspection techniques have been successfully used for inspecting these structures. A novel inspection system with a dual-polarized microwave near-field waveguide probe for detecting defects such as disbond between CFRP laminates and strengthened structures is presented. It is shown that this system provides automatic removal of the influence of undesired standoff distance (or surface roughness) variations. It may simultaneously …

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Inspection Of Spray On Foam Insulation (Sofi) Using Microwave And Millimeter Wave Synthetic Aperture Focusing And Holography, Joseph Toby Case, Frank L. Hepburn, R. Zoughi Apr 2006

Inspection Of Spray On Foam Insulation (Sofi) Using Microwave And Millimeter Wave Synthetic Aperture Focusing And Holography, Joseph Toby Case, Frank L. Hepburn, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

The Space Shuttle Columbia's catastrophic failure is thought to have been caused by a dislodged piece of external tank spray on foam insulation (SOFI) striking and significantly damaging the left wing of the orbiter, which may have been due to a flawed section of SOFI. Microwave and millimeter wave nondestructive evaluation (NDE) methods have shown great potential detecting anomalies in SOFI such as small air voids using a horn and lens in a (real) focused configuration. Synthetic focusing methods may also be used to detect air voids in SOFI and may additionally offer the ability to locate the defect in …

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Jitter Analysis Of Pwm Scheme In High Speed Serial Link, Rui Tang, Yong-Bin Kim, Minsu Choi, Fabrizio Lombardi Apr 2006

Jitter Analysis Of Pwm Scheme In High Speed Serial Link, Rui Tang, Yong-Bin Kim, Minsu Choi, Fabrizio Lombardi

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents a jitter analysis method for PWM (pulse width modulation) scheme in high-speed serial links. The data rate of PWM with N different pulse widths (PWM-N) scheme is (log2N) x (symbol rate). However it increases the timing jitter of the transmitted signal. The timing jitter is determined by the pulse widths of PWM symbols and the characteristics of the communication channel. The analysis of the first-order systems and the second-order systems demonstrates that data dependent jitter (DDJ) strongly depends on the -3dB frequency and the damping ratio of the systems. The proposed jitter analysis method makes …

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Ultrasonically Set Glass Polyalkenoate Cements For Orthodontic Applications, D. A. Tanner, N. Rushe, Mark R. Towler Apr 2006

Ultrasonically Set Glass Polyalkenoate Cements For Orthodontic Applications, D. A. Tanner, N. Rushe, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

There is an accepted clinical requirement for a luting cement that can be command set upon satisfactory placement of an orthodontic appliance onto dentition. This work evaluates the suitability of ultrasound, imparted from a dental scaler, as a potential mechanism for achieving this. The net setting times and subsequent compressive strengths of a range of commercial and experimental glass polyalkenoate cements (GPCs) were evaluated, using modified ISO 9917 methods, when set both chemically and by ultrasound. The ultrasound was applied to the GPC through an orthodontic brace. It was possible to command set GPCs by the application of five to …

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Structural And Magnetic Properties Of La Mn₁₋ₓfeₓo₃ (0 < X < 1.0), X.-D. Zhou, L. R. Pederson, Qingsheng Cai, Jinbo Yang, B. J. Scarfino, M. Kim, William B. Yelon, William Joseph James, Harlan U. Anderson, C. Wang Apr 2006

Structural And Magnetic Properties Of La Mn₁₋ₓfeₓo₃ (0 < X < 1.0), X.-D. Zhou, L. R. Pederson, Qingsheng Cai, Jinbo Yang, B. J. Scarfino, M. Kim, William B. Yelon, William Joseph James, Harlan U. Anderson, C. Wang

Materials Science and Engineering Faculty Research & Creative Works

Electronic, structural, and magnetic properties of Mn-doped lanthanum ferrites were studied by neutron diffraction, superconducting quantum interference device, and impedance spectroscopy. Neutron diffraction refinements were performed with the constraint of full La occupancy, which showed the presence of excess oxygen when x < 0.4. Mixed valent Mn cations and cation vacancies, therefore, exist in all the samples. The samples with x > 0.7 are magnetically ordered at room temperature with orthorhombic symmetry (Pbnm). When x < 0.3 the structure is rhombohedral and magnetically disordered above 16 K. The majority carriers, electron holes, correspond to high oxidation states of Mn. The carrier concentration is determined from the Seebeck coefficients, and is a function of temperature and Fe concentration. The measurements of conductivity and Seebeck coefficients show polaron hopping at elevated temperatures.

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Optimisation Of The Composition Of An Acrylic Bone Cement: Application To Relative Amounts Of The Initiator And The Activator/Co-Initiator In Surgical Simplex®P, S. Madigan, M. R. Towler, G. Lewis Apr 2006

Optimisation Of The Composition Of An Acrylic Bone Cement: Application To Relative Amounts Of The Initiator And The Activator/Co-Initiator In Surgical Simplex®P, S. Madigan, M. R. Towler, G. Lewis

Chemical and Biochemical Engineering Faculty Research & Creative Works

In cemented arthroplasties, the two-part self-curing acrylic bone cement is currently the only material used for anchoring the total joint replacement to the contiguous bone. In virtually all commercially available formulations of this cement, the agents used for the initiation and activation/co-initiation of the radical polymerisation reaction are benzoyl peroxide (BPO) and N, N dimethyl-paratoluidine (DMPT), respectively. There are no reports in the open literature on the rationale for the amounts of these and other constituents in the formulations of the cement. Given the concerns that have been raised in the literature regarding the effect of residual DMPT on the …

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Frequency-Selective Power Transducers "Hexagonal Ferrite Resonator-Semiconductor Element", Marina Koledintseva Mar 2006

Frequency-Selective Power Transducers "Hexagonal Ferrite Resonator-Semiconductor Element", Marina Koledintseva

Electrical and Computer Engineering Faculty Research & Creative Works

The transducers studied herein allow for frequency-selective measurement of mm-wave power parameters. Frequency selectivity is assured by a monocrystalline hexagonal ferrite resonator (HFR). The HFR is in direct contact with a semiconductor element (SE)—an unpackaged Hall-element, or a chip transistor (or diode). Power absorbed by the HFR at the ferromagnetic resonance converts to heat, and the heat flux penetrates through the current-carrying SE. A number of thermo/electro/magnetic phenomena accompany the Hall-effect in a semiconductor and cause a voltage in addition to the Hall-effect voltage. The conversion coefficient of a transducer is analyzed using the power balance equation. Some experimental results …

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Direct Torque Control Of Five-Phase Induction Motor Using Space Vector Modulation With Harmonics Elimination And Optimal Switching Sequence, Shuai Lu, Keith Corzine Mar 2006

Direct Torque Control Of Five-Phase Induction Motor Using Space Vector Modulation With Harmonics Elimination And Optimal Switching Sequence, Shuai Lu, Keith Corzine

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper an effective direct torque control (DTC) for a 5-phase induction motor with sinusoidally distributed windings is developed. First by coordinate transformation, the converter/motor models are represented by two independent equivalent d-q circuit models; and the 5-phase VSI input are decoupled into the torque producing and non-torque producing harmonics sets. Then with the torque production component of the induction motor model, the space vector modulation (SVM) can be applied to the five-phase induction motor DTC control, resulting in considerable torque ripple reduction over the lookup table method. Based on the decoupled system model, the current distortion issue due …

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Acoustic Detection And Classification Of Microchiroptera Using Machine Learning: Lessons Learned From Automatic Speech Recognition, Mark D. Skowronski, John G. Harris Mar 2006

Acoustic Detection And Classification Of Microchiroptera Using Machine Learning: Lessons Learned From Automatic Speech Recognition, Mark D. Skowronski, John G. Harris

Electrical and Computer Engineering Faculty Research & Creative Works

Current automatic acoustic detection and classification of microchiroptera utilize global features of individual calls (i.e., duration, bandwidth, frequency extrema), an approach that stems from expert knowledge of call sonograms. This approach parallels the acoustic phonetic paradigm of human automatic speech recognition (ASR), which relied on expert knowledge to account for variations in canonical linguistic units. ASR research eventually shifted from acoustic phonetics to machine learning, primarily because of the superior ability of machine learning to account for signal variation. To compare machine learning with conventional methods of detection and classification, nearly 3000 search-phase calls were hand labeled from recordings of …

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Nanometal Containing Nanocomposites And Photolithographic Polyaniline Nanofibers, Frank D. Blum, Sunil K. Pillalamarri, Lalani K. Werake, J. Greg Story, Massimo F. Bertino, Akira Tokuhiro Mar 2006

Nanometal Containing Nanocomposites And Photolithographic Polyaniline Nanofibers, Frank D. Blum, Sunil K. Pillalamarri, Lalani K. Werake, J. Greg Story, Massimo F. Bertino, Akira Tokuhiro

Chemistry Faculty Research & Creative Works

A report on recent progress from our laboratories on the nanostructures produced from novel synthesis techniques will be discussed. Using high-energy radiation (γ-rays) we have been able to produce conducting polymer nanofibers and nanorods of polyaniline and polypyrrole without the use of a separate template or capping agent. This technique has been extended, with the addition of metal ions, to a "one pot" synthesis, producing conducting nanocomposites. These nanocomposites contain metal nanoparticles which decorate the conducting nanofibers. We have also recently shown that these systems can be photopatterned to produce novel structures. We believe that these systems will be useful …

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An Estimative Current Mode Controller For Dc-Dc Converters Operating In Continuous Conduction Mode, Mehdi Ferdowsi Mar 2006

An Estimative Current Mode Controller For Dc-Dc Converters Operating In Continuous Conduction Mode, Mehdi Ferdowsi

Electrical and Computer Engineering Faculty Research & Creative Works

A new digital average-current-mode controller for converters operating in continuous conduction mode is introduced. The principal idea of the proposed control scheme is to estimate the required value of the duty ratio based on the dynamic of the converter using the measured samples of current and voltage signals. The proposed control scheme is stable for any value of the duty ratio without employing an external ramp. Furthermore, it is robust, accurate, and has a fast dynamic response.

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Power Absorption Of Near Field Of Elementary Radiators In Proximity Of A Composite Layer, Marina Koledintseva, Poorna Chander Ravva, Jingyu Huang, James L. Drewniak, M. M. Sabirov, V. V. Bodrov, I. V. Sourkova, V. I. Sourkov Mar 2006

Power Absorption Of Near Field Of Elementary Radiators In Proximity Of A Composite Layer, Marina Koledintseva, Poorna Chander Ravva, Jingyu Huang, James L. Drewniak, M. M. Sabirov, V. V. Bodrov, I. V. Sourkova, V. I. Sourkov

Electrical and Computer Engineering Faculty Research & Creative Works

Near-field behavior of elementary electric and magnetic dipoles close to a plane layer (or layers) of engineered composite materials is analyzed using the rigorous analytical approach. Some results of computations are represented for composite media containing conductive inclusions. These composites provide shielding mainly due to absorption of electromagnetic energy. The effect of conductivity of inclusions and their geometry (through their aspect ratio) on the absorption and radiation efficiency of a radiator near composite layers is analyzed.

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Fusion Of Microwave And Eddy Current Data For A Multi-Modal Approach In Evaluating Corrosion Under Paint And In Lap Joints, Kapil Gupta, Mohammad Tayeb Ahmad Ghasr, Sergey Kharkovsky, R. Zoughi, R. Joe Stanley, Ajay Padwal, Matthew O'Keefe, Donald D. Palmer, J. Blackshire, Gary Steffes, N. Wood Mar 2006

Fusion Of Microwave And Eddy Current Data For A Multi-Modal Approach In Evaluating Corrosion Under Paint And In Lap Joints, Kapil Gupta, Mohammad Tayeb Ahmad Ghasr, Sergey Kharkovsky, R. Zoughi, R. Joe Stanley, Ajay Padwal, Matthew O'Keefe, Donald D. Palmer, J. Blackshire, Gary Steffes, N. Wood

Electrical and Computer Engineering Faculty Research & Creative Works

Critical aircraft structures are susceptible to hidden corrosion. Find-it and fix-it approaches are inefficient as it relates to managing the problems associated with corrosion. More comprehensive corrosion information may be obtained using data fusion from several detection and evaluation methods. To this end, microwave, conventional and pulsed eddy current data from a multi-layer corroded panel, representing an aircraft lap joint, are fused and used as inputs to a structural analysis model to obtain a comprehensive snapshot of the corroded environment. This paper presents the data fusion algorithm and the structural analysis model along with a discussion of the results.

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Millimeter Wave Imaging Of Corrosion Under Paint: Comparison Of Two Probes, Mohammad Tayeb Ahmad Ghasr, Sergey Kharkovsky, R. Zoughi, Matthew O'Keefe, Ajay Padwal, Donald D. Palmer Mar 2006

Millimeter Wave Imaging Of Corrosion Under Paint: Comparison Of Two Probes, Mohammad Tayeb Ahmad Ghasr, Sergey Kharkovsky, R. Zoughi, Matthew O'Keefe, Ajay Padwal, Donald D. Palmer

Electrical and Computer Engineering Faculty Research & Creative Works

Critical aircraft structures are susceptible to harsh environmental conditions that cause corrosion of these structural components. It is of great importance to detect corrosion under paint, particularly in its early stages. Millimeter wave nondestructive evaluation methods have shown great potential for detecting corrosion under paint and evaluating its properties. This paper presents and compares the results of using two distinct millimeter wave detection methods; namely a standard single probe and a newly developed differential probe for detecting corrosion under paint.

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Non-Unity Active Pfc Methods For Filter Size Optimization, Yongxiang Chen, Jonathan W. Kimball, Philip T. Krein Mar 2006

Non-Unity Active Pfc Methods For Filter Size Optimization, Yongxiang Chen, Jonathan W. Kimball, Philip T. Krein

Electrical and Computer Engineering Faculty Research & Creative Works

Active power factor correction seeks to obtain unity power factor and sinusoidal line currents. Optimized nonsinusoidal line currents reduce filter capacitor requirements with a nonunity target power factor. Implementation methods are presented that permit reduced power factor to be traded off against filter size in a nearly optimum manner. A simple waveform shape can reduce filter component size by about 40% in active PFC converters at the same level of complexity as in conventional PFC designs while yielding power factor as high as 0.9. Two approximate methods to generate appropriate shapes are presented. They offer direct practical implementation of nonunity …

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