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2012

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Articles 4051 - 4080 of 6304

Full-Text Articles in Engineering

Experimental And Theoretical Electronic Structure Of Eurh2as2, A. D. Palczewski, R. S. Dhaka, Y. Lee, Yogesh Singh, D. C. Johnston, B. N. Harmon, Adam Kaminski Jan 2012

Experimental And Theoretical Electronic Structure Of Eurh2as2, A. D. Palczewski, R. S. Dhaka, Y. Lee, Yogesh Singh, D. C. Johnston, B. N. Harmon, Adam Kaminski

United States Department of Energy: Publications

The Fermi surfaces (FS’s) and band dispersions of EuRh2As2 have been investigated using angle-resolved photoemission spectroscopy. The results in the high-temperature paramagnetic state are in good agreement with the full-potential linearized augmented-plane-wave calculations, especially in the context of the shape of the two-dimensional FS’s and band dispersion around the Γ (0,0) and X (π,π) points. Interesting changes in band folding are predicted by the theoretical calculations below the magnetic transition temperature TN ≈ 47 K. However, by comparing the FS’s measured at 60 and 40 K, we did not observe any signature of this transition at …

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Magnetic And Structural Transitions In The Iron-Chalcogenide High-Tc Superconductor: K0.8fe1.76se2.00, W. N. Rowan-Weetaluktuk, D. H. Ryan, J. M. Cadogan, R. Hu, S. L. Bud’Ko, Paul C. Canfield Jan 2012

Magnetic And Structural Transitions In The Iron-Chalcogenide High-Tc Superconductor: K0.8fe1.76se2.00, W. N. Rowan-Weetaluktuk, D. H. Ryan, J. M. Cadogan, R. Hu, S. L. Bud’Ko, Paul C. Canfield

United States Department of Energy: Publications

57Fe Mössbauer spectroscopy was used to study single-crystals of K0.8Fe1.76Se2.00 from 6K to 673 K. At 6 K, the hyperfine field (Bhf) is canted away from the c-axis by 18±3°. The temperature dependence of Bhf follows a spin wave model with a spin excitation gap of 9±1 meV. A sudden increase in the line width and a corresponding drop in (1/2)eQVzz at TN = 532 K are indications of strong coupling between the magnetic and structural transitions.

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Evaluation Of Niobium As Candidate Electrode Material For Dc High Voltage Photoelectron Guns, M. Bastaninejad, Md. Abdullah Mohamed, A. A. Elmustafa, P. Adderley, J. Clark, S. Covert, J. Hansknecht, C. Hernandez-Garcia, M. Poelker, R. Mammei, K. Surles-Law, P. Williams Jan 2012

Evaluation Of Niobium As Candidate Electrode Material For Dc High Voltage Photoelectron Guns, M. Bastaninejad, Md. Abdullah Mohamed, A. A. Elmustafa, P. Adderley, J. Clark, S. Covert, J. Hansknecht, C. Hernandez-Garcia, M. Poelker, R. Mammei, K. Surles-Law, P. Williams

United States Department of Energy: Publications

The field emission characteristics of niobium electrodes were compared to those of stainless steel electrodes using a DC high voltage field emission test apparatus. A total of eight electrodes were evaluated: two 304 stainless steel electrodes polished to mirror like finish with diamond grit and six niobium electrodes (two single-crystal, two large-grain, and two fine-grain) that were chemically polished using a buffered-chemical acid solution. Upon the first application of high voltage, the best large-grain and single-crystal niobium electrodes performed better than the best stainless steel electrodes, exhibiting less field emission at comparable voltage and field strength. In all cases, field …

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Monitoring The Effects Of Knickpoint Erosion On Bridge Pier And Abutment Structural Damage Due To Scour, Thanos Papanicolaou, David M. Admiraal, Christopher Wilson, Clark W. Kephart Jan 2012

Monitoring The Effects Of Knickpoint Erosion On Bridge Pier And Abutment Structural Damage Due To Scour, Thanos Papanicolaou, David M. Admiraal, Christopher Wilson, Clark W. Kephart

Mid-America Transportation Center: Final Reports and Technical Briefs

The goal of this study was to conduct a field-oriented evaluation, coupled with advanced laboratory techniques, of channel degradation in a stream of the Deep Loess Region of western Iowa, namely, Mud Creek. The Midwestern United States is an ideal place for such a study, considering that approximately $1 billion of infrastructure and farmland has been lost recently to channel degradation. A common form of channel degradation in this region is associated with the formation of knickpoints, which naturally manifest as short waterfalls within the channel that migrate upstream. As flow plunges over a knickpoint face, scouring of the downstream …

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Development Of A Methodology For Assessment Of Crash Costs At Highway- Rail Grade Crossings In Nebraska, Aemal Khattak, Eric Thompson Jan 2012

Development Of A Methodology For Assessment Of Crash Costs At Highway- Rail Grade Crossings In Nebraska, Aemal Khattak, Eric Thompson

Mid-America Transportation Center: Final Reports and Technical Briefs

An accurate measure of crash costs is required to support effective decision-making about transportation investments. In particular, underinvestment will occur if measurement fails to capture the full cost of crashes. Such mis-measurement and underinvestment may be occurring in the case of crashes at highway-rail grade crossings (HRGCs). HRGC crash costs can be substantial because of the severity of crashes. However, another important potential cost is the disruption to the transportation and logistics system. Existing methodologies capture the first set of costs but often fail to fully capture the second set. This research provides a standardized methodology for assessing the expected …

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Safety Improvements At Highway-Railroad Crossing For Pedestrians And Bicyclists And The Assessment Of Long- Term Effects Of Centerline Curbing, Aemal Khattak, Zheng Luo Jan 2012

Safety Improvements At Highway-Railroad Crossing For Pedestrians And Bicyclists And The Assessment Of Long- Term Effects Of Centerline Curbing, Aemal Khattak, Zheng Luo

Mid-America Transportation Center: Final Reports and Technical Briefs

The focus of the research reported herein was on assessing the long-term effectiveness of median barriers at highway-rail grade crossings (HRGCs), the impacts of barrier maintenance in resurrecting safety, and on exploring and assessing ways to improve pedestrian and bicyclist safety at HRGCs. Nebraska has about 7,000 HRGCs and each one represents a potential conflict point among trains and highway users, i.e., motorists, pedestrians, and bicyclists. Safety at HRGCs is compromised when highway users resort to unsafe maneuvers, such as passing around closed gates when trains are approaching. Gate-related violations by motorists, pedestrians, and bicyclists were studied at three selected …

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Implementation Of Warm-Mix Asphalt Mixtures In Nebraska Pavements, Yong-Rak Kim, Jun Zhang, Hoki Ban Jan 2012

Implementation Of Warm-Mix Asphalt Mixtures In Nebraska Pavements, Yong-Rak Kim, Jun Zhang, Hoki Ban

Mid-America Transportation Center: Final Reports and Technical Briefs

The primary objective of this research is to evaluate the feasibility of several WMA mixtures as potential asphalt paving mixtures for Nebraska pavements. To that end, three well-known WMA additives (i.e., Sasobit, Evotherm, and Advera synthetic zeolite) were evaluated. For a more realistic evaluation of the WMA approaches, trial pavement sections of the WMA mixtures and their HMA counterparts were implemented in Antelope County, Nebraska. More than one ton of field-mixed loose mixtures was collected at the time of paving and was transported to the NDOR and UNL laboratories to conduct comprehensive laboratory evaluations and pavement performance predictions of the …

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Speed Limit Recommendation In Vicinity Of Signalized, High-Speed Intersection, Anuj Sharma Ph.D., Laurence Rilett Ph.D., Zifeng Wu M.S., Shefang Wang Jan 2012

Speed Limit Recommendation In Vicinity Of Signalized, High-Speed Intersection, Anuj Sharma Ph.D., Laurence Rilett Ph.D., Zifeng Wu M.S., Shefang Wang

Mid-America Transportation Center: Final Reports and Technical Briefs

This report presents the results of Nebraska Department of Roads (NDOR) research project SPR-P1 (11) M307, which evaluated the traffic operations and safety effects of 5 mph and 10 mph speed limit reductions in the vicinity of high-speed, signalized intersections with advance warning flashers (AWF). The methodology involved two studies: 1) field study of the impact of speed limit reduction at seven high-speed intersections, 2) crash analysis using the 10-year history from 28 high-speed intersections. In the field study, traffic operational effects of the reduced speed limits were analyzed for seven high-speed, signalized intersections with AWF, using the Quantile regression …

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Assessing The Structural, Driver And Economic Impacts Of Traffic Pole Mounted Wind Power Generator And Solar Panel Hybrid System, Anuj Sharma Ph.D., Justice Appiah Ph.D., Scott K. Rosenbaugh Jan 2012

Assessing The Structural, Driver And Economic Impacts Of Traffic Pole Mounted Wind Power Generator And Solar Panel Hybrid System, Anuj Sharma Ph.D., Justice Appiah Ph.D., Scott K. Rosenbaugh

Mid-America Transportation Center: Final Reports and Technical Briefs

This project evaluates the physical and economic feasibility of using existing traffic infrastructure to mount wind power generators. Some possible places to mount a light weight wind generator and solar panel hybrid system are: i) Traffic signal pole and ii) Street Light pole. Traffic signal poles can themselves have multiple designs depending on type of mount (mast arm vs. span wire) and the width of the intersection (load carried) etc. The close proximity of street light poles and traffic signal poles to the traffic cabinets, which can be used for storing the battery banks, make them good candidates to mount …

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Concrete Surface With Nano-Particle Additives For Improved Wearing Resistance To Increasing Truck Traffic, Genda Chen, Dongming Yan Ph.D., Chenglin Wu Ph.D., Nicholas Leventis Ph.D, Shruti Mahadik Ph.D., Zhibin Lin Ph.D Jan 2012

Concrete Surface With Nano-Particle Additives For Improved Wearing Resistance To Increasing Truck Traffic, Genda Chen, Dongming Yan Ph.D., Chenglin Wu Ph.D., Nicholas Leventis Ph.D, Shruti Mahadik Ph.D., Zhibin Lin Ph.D

Mid-America Transportation Center: Final Reports and Technical Briefs

This study focused on the use of nanotechnology in concrete to improve the wearing resistance of concrete. The nano materials used were polymer cross-linked aerogels, carbon nanotubes, and nano-SiO2, nano-CaCO3, and nano-Al2O3 particles. As an indirect measurement of the concrete wearing resistance, the tensile and compressive properties and the permeability of concrete were evaluated for various mix designs. The optimal amount of nano material additives were determined following the American Society of Testing Methods (ASTM) standard test methodologies. The test results from the materials were compared for their mechanical behaviors. This type of technology may potentially improve the comfort level …

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Pilot Study On Rugged Fiber Optic Brillouin Sensors For Large-Strain Measurements To Ensure The Safety Of Transportation Structures, Genda Chen, Zhi Zhou, Hai Xiao, Ying Huang Jan 2012

Pilot Study On Rugged Fiber Optic Brillouin Sensors For Large-Strain Measurements To Ensure The Safety Of Transportation Structures, Genda Chen, Zhi Zhou, Hai Xiao, Ying Huang

Mid-America Transportation Center: Final Reports and Technical Briefs

Brillouin-scattering Optical Time Domain Reflectometry (BOTDR) is a viable technology for simultaneous, distributed strain and temperature measurements for miles-long transportation structures. It is a promising tool to ensure the smooth operation and safety of bridge structures that are key links in surface transportation networks or between various transportation modes: i.e., from airport to train station. Currently, telecom-grade optical fibers are widely used in civil engineering for strain and temperature measurements. These fibers are very fragile and easy to break during installation and measurement. In order to understand the ultimate behavior of structures, more rugged optical fibers such as carbon/polyimide coated …

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Use Of Fiber Bragg Grating (Fbg) Sensors For Performing Automated Bridge Pier Structural Damage Detection And Scour Monitoring, A.N. Thanos Papnicolaou Ph.D., Achilleas Tsakiris Jan 2012

Use Of Fiber Bragg Grating (Fbg) Sensors For Performing Automated Bridge Pier Structural Damage Detection And Scour Monitoring, A.N. Thanos Papnicolaou Ph.D., Achilleas Tsakiris

Mid-America Transportation Center: Final Reports and Technical Briefs

The goal of this study was to evaluate the performance of Fiber Bragg Grating (FBG) sensors able to detect impacts with different frequencies on a bridge pier. The FBG technology was evaluated under controlled conditions in a laboratory flume set-up to mimic the flow, sediment, and design characteristics of a pier structure. The system was calibrated using site-specific properties to relate strain to a known magnitude force for different bridge pier designs, different scour depths, and structural impacts. The FBGs proved a reliable measure of strain and displacement for key components of bridge structures, such as piers, during varying flow …

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Improving Freight Fire Safety: Experiment Testing And Computer Modeling To Further Development Of Mist-Controlling Additives For Fire Mitigation, Albert Ratner Ph.D., University Of Iowa Jan 2012

Improving Freight Fire Safety: Experiment Testing And Computer Modeling To Further Development Of Mist-Controlling Additives For Fire Mitigation, Albert Ratner Ph.D., University Of Iowa

Mid-America Transportation Center: Final Reports and Technical Briefs

With the purpose to minimize or prevent crash-induced fires in road and rail transportation, the current interest in bio-derived and blended transportation fuels is increasing. Based on two years of preliminary testing and analysis, it appears to be clear that polymeric additives may be added to diesel fuel to mitigate the formation of fine mists while allow regular flow through the fuel system. In this work, computer modeling was adapted as a fast and cost-effective methodology to identify the target range where polymeric additives could impact the shear-thickening effect on fuels. The Volume of Fraction (VOF) method was used within …

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Transportation Impacts Of The Chicago River Closure To Prevent An Asian Carp Infestation, Aaron Strong Ph.D., Nikhil Sikka Ph.D., Lindsay Salvatore Ph.D. Jan 2012

Transportation Impacts Of The Chicago River Closure To Prevent An Asian Carp Infestation, Aaron Strong Ph.D., Nikhil Sikka Ph.D., Lindsay Salvatore Ph.D.

Mid-America Transportation Center: Final Reports and Technical Briefs

This project develops a simple linear programming model of the Upper Midwest regions rail transportation network to test whether a closure of the Chicago River to freight traffic would impact the capacity constraint of the rail system. The result suggest that the rail network in the Upper Midwest regions are nowhere near approaching capacity and that a closure would have little impact on the rail network. Two noteworthy sets of commodities may be adversely affected, cereal grains and other agricultural product and gravel and crushed stone.

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Measurement Of Semiconductor Surface Potential Using The Scanning Electron Microscope, Jennifer T. Heath, Chun-Sheng Jiang, Mowafak M. Al-Jassim Jan 2012

Measurement Of Semiconductor Surface Potential Using The Scanning Electron Microscope, Jennifer T. Heath, Chun-Sheng Jiang, Mowafak M. Al-Jassim

Faculty Publications

We calibrate the secondary electron signal from a standard scanning electron microscope to voltage, yielding an image of the surface or near-surface potential. Data on both atomically abrupt heterojunction GaInP/GaAs and diffused homojunction Si solar cell devices clearly show the expected variation in potential with position and applied bias, giving depletion widths and locating metallurgical junctions to an accuracy better than 10 nm. In some images, distortion near the p-n junction is observed, seemingly consistent with the effects of lateral electric fields (patch fields). Reducing the tube bias removes this distortion. This approach results in rapid and straightforward collection of …

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An Improved Prediction Model For Spacecraft Damage Following Orbital Debris Impact, Joel E. Williamsen, William P. Schonberg Jan 2012

An Improved Prediction Model For Spacecraft Damage Following Orbital Debris Impact, Joel E. Williamsen, William P. Schonberg

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This paper offers a new set of 'generic', data-Based hole size and crank length prediction models for spherical orbital debris particles impacting multi-plate targets at velocities up to ~12 km/s. the equations are applicable to a wide variety of spacecraft target configurations, but are limited to hole sizes above, but relatively near, the ballistic limit of the impacting particles. Additional work is underway to expand these models to diameters farther above the ballistic limit for the described shield types.

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Afit Graduate School Of Engineering And Management Catalog 2012-2013, Graduate School Of Engineering And Management, Air Force Institute Of Technology Jan 2012

Afit Graduate School Of Engineering And Management Catalog 2012-2013, Graduate School Of Engineering And Management, Air Force Institute Of Technology

AFIT Documents

The Graduate Catalog represents the offerings, programs, and requirements in effect at the time of publication.

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Jumpstarting A Global Mobile Computing Lab At Pace University, Christelle Scharff Jan 2012

Jumpstarting A Global Mobile Computing Lab At Pace University, Christelle Scharff

Cornerstone 2 Reports : Community Outreach and Empowerment Through Service Learning and Volunteerism

Mobile applications are the future of computing. This project focuses on jumpstarting a mobile lab at Pace University. It reaches out to the university community and beyond by integrating different events including a competition on mobile application development and hosting external speakers. A high school event and a panel discussion with experts in the field are planned.

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Current-Based Diagnosis For Gear Tooth Breaks In Wind Turbine Gearboxes, Dingguo Lu, Xiang Gong, Wei Qiao Jan 2012

Current-Based Diagnosis For Gear Tooth Breaks In Wind Turbine Gearboxes, Dingguo Lu, Xiang Gong, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

Gearbox faults constitute a significant portion of all faults and downtime in wind turbines (WTs). Current-based gearbox fault diagnosis has significant advantages over traditional vibration-based techniques in terms of cost, implementation, and reliability. This paper derives a mathematical model for a WT drive train consisting of a twostage gearbox and a permanent magnet (PM) generator, from which the characteristic frequencies of gear tooth breaks in generator stator current frequency spectra are clearly identified. A adaptive signal resampling algorithm is proposed to convert the variable fault characteristic frequencies to constant values for WTs running at variable speeds. A fault detector is …

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Energy Efficiency In Multiaccess Fading Channels Under Qos Constraints, Deli Qiao, Mustafa Cenk Gursoy, Senem Velipasalar Jan 2012

Energy Efficiency In Multiaccess Fading Channels Under Qos Constraints, Deli Qiao, Mustafa Cenk Gursoy, Senem Velipasalar

Department of Electrical and Computer Engineering: Faculty Publications

In this article, transmission over multiaccess fading channels under quality-of-service (QoS) constraints is studied in the low-power and wideband regimes. QoS constraints are imposed as limitations on the buffer violation probability. The effective capacity, which characterizes the maximum constant arrival rates in the presence of such statistical QoS constraints, is employed as the performance metric. A two-user multiaccess channel model is considered, and the minimum bit energy levels and wideband slope regions are characterized for different transmission and reception strategies, namely time-division multiple-access (TDMA), superposition coding with fixed decoding order, and superposition coding with variable decoding order. It is shown …

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Matching And Funneling Light At The Plasmonic Brewster Angle, Christos Argyropoulos, Giuseppe D'Aguanno, Nadia Mattiucci, Neset Akozbek, Mark J. Bloemer, Andrea Alu Jan 2012

Matching And Funneling Light At The Plasmonic Brewster Angle, Christos Argyropoulos, Giuseppe D'Aguanno, Nadia Mattiucci, Neset Akozbek, Mark J. Bloemer, Andrea Alu

Department of Electrical and Computer Engineering: Faculty Publications

The ultrabroadband impedance matching of metallic gratings at the plasmonic Brewster angle [A. Al`u et al., Phys. Rev. Lett. 106, 123902 (2011)] is analyzed here in several realistic scenarios and configurations, and in the case of nonmonochromatic excitation. This phenomenon is the analogy of the well-known Brewster transmission for dielectric slabs but, when applied to plasmonic gratings, has the remarkable property of funneling and concentrating light within subwavelength slits. We analyze here how the presence of absorption and of realistic substrates and/or superstrates may influence the phenomenon, its beamwidth and angular selectivity, and its overall performance in the case …

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Method For Increasing The Efficiency Of Organic Photovoltaic Cells, Jinsong Huang, Yongbo Yuan Jan 2012

Method For Increasing The Efficiency Of Organic Photovoltaic Cells, Jinsong Huang, Yongbo Yuan

Department of Mechanical and Materials Engineering: Faculty Publications

The present invention is directed to an organic photovoltaic cell that contains one or more dipole regions generally disposed between an organic active region and the electrodes and a process for producing such an organic photovoltaic cell.

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Lte Phy Performance Analysis Under 3gpp Standards Parameters, Fahimeh Rezaei, Michael Hempel, Hamid Sharif Jan 2012

Lte Phy Performance Analysis Under 3gpp Standards Parameters, Fahimeh Rezaei, Michael Hempel, Hamid Sharif

Department of Electrical and Computer Engineering: Faculty Publications (to 2015)

Long Term Evolution (LTE) has been introduced by 3GPP (3rd Generation Partnership Project) and is poised to dominate the 4th generation (4G) of mobile telecommunication networks. In this article, we present an in-depth analysis of the LTE physical layer’s characteristics and its performance. Our work is unique in providing a detailed performance study based on Release 8 of the 3GPP standard. Several works have discussed the LTE performance; however, most have been restricted to limited scenarios. Our work shows a more comprehensive investigation of the maximum data throughput under different conditions and scenarios. Our performance study includes TDD and FDD …

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Modeling, Simulation, And Validation Of A Power Sic Bjt, Tanya Kirilova Gachovska, Jerry L. Hudgins, Angus Bryant, Enrico Santi, Alan Mantooth, Anant K. Agarwal Jan 2012

Modeling, Simulation, And Validation Of A Power Sic Bjt, Tanya Kirilova Gachovska, Jerry L. Hudgins, Angus Bryant, Enrico Santi, Alan Mantooth, Anant K. Agarwal

Department of Electrical and Computer Engineering: Faculty Publications

This paper presents a physics-based model of a silicon carbide bipolar junction transistor and verification of its validity through experimental testing. The Fourier series solution is used to solve the ambipolar diffusion equation in the transistor collector region. The model is realized using MATLAB and Simulink. The experimental results of static operation and also the simulated and experimental results of switching waveforms are given.

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A Multicell Battery System Design For Electric And Plug-In Hybrid Electric Vehicles, Taesic Kim, Wei Qiao, Liyan Qu Jan 2012

A Multicell Battery System Design For Electric And Plug-In Hybrid Electric Vehicles, Taesic Kim, Wei Qiao, Liyan Qu

Department of Electrical and Computer Engineering: Faculty Publications

The performance of electric vehicles (EVs) and plug-in hybrid electric vehicle (PHEVs) strongly relies on their battery storage system, which consists of multiple battery cells connected in series and parallel. However, cell state variations are commonly present, which reduces the energy conversion efficiency of the battery system. Furthermore, in a large battery system the risk of catastrophic faults of cells increases because a large numbers of cells are used. To solve these problems, this paper proposes a novel power electronics-enabled, self-X, multicell battery system design. The proposed battery system can self-heal from failures or abnormal operations of single or multiple …

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Wind Speed And Rotor Position Sensorless Control For Direct-Drive Pmg Wind Turbines, Wei Qiao, Xu Yang, Xiang Gong Jan 2012

Wind Speed And Rotor Position Sensorless Control For Direct-Drive Pmg Wind Turbines, Wei Qiao, Xu Yang, Xiang Gong

Department of Electrical and Computer Engineering: Faculty Publications

This paper proposes a wind speed and rotor position sensorless control for wind turbines directly driving permanent magnetic generators (PMGs). A sliding-mode observer is designed to estimate the rotor position of the PMG by using the measured stator currents and the commanded stator voltages obtained from the control scheme of the machine-side converter of the PMG wind turbine. The rotor speed of the PMG (i.e., the turbine shaft speed) is estimated from its back electromotive force using a model adaptive reference system observer. Based on the measured output electrical power and estimated rotor speed of the PMG, the mechanical power …

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Analog Sensing Front-End System For Harmonic Signal Classification, Daniel J. White, Peter William, Michael W. Hoffman, Sina Balkir, Nathan Schemm Jan 2012

Analog Sensing Front-End System For Harmonic Signal Classification, Daniel J. White, Peter William, Michael W. Hoffman, Sina Balkir, Nathan Schemm

Department of Electrical and Computer Engineering: Faculty Publications

This paper presents the design of an Analog-to- Information spectral decomposition scheme suitable for parallel low-power analog and mixed-signal VLSI implementation. The novel scheme extracts sufficient information to achieve good back end signal detection and classification performance while using less power than purely digital spectral techniques such as FFT. Simulations of a prototype system in a mixed-signal 130nm CMOS process show a feasible solution space given an on-line self-calibrating system.

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Permanent Magnet Generator Design And Control For Large Wind Turbines, Xu Yang, Dean Patterson, Jerry L. Hudgins Jan 2012

Permanent Magnet Generator Design And Control For Large Wind Turbines, Xu Yang, Dean Patterson, Jerry L. Hudgins

Department of Electrical and Computer Engineering: Faculty Publications

Direct drive permanent magnet generators(PMGs) are increasingly capturing the global wind market in large onshore and offshore applications. The aim of this paper is to provide a quick overview of permanent magnet generator design and related control issues for large wind turbines. Generator systems commonly used in wind turbines, the permanent magnet generator types, and control methods are reviewed in the paper. The current commercial PMG wind turbine on market is surveyed. The design of a 5 MW axial flux permanent magnet (AFPM) generator for large wind turbines is discussed and presented in detail.

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Performance Analysis For Direction Of Arrival Estimating Algorithms, Pradhumna Shrestha, Michael Hempel, Puttipong Mahasukhon, Tao Ma, Hamid Sharif Jan 2012

Performance Analysis For Direction Of Arrival Estimating Algorithms, Pradhumna Shrestha, Michael Hempel, Puttipong Mahasukhon, Tao Ma, Hamid Sharif

Department of Electrical and Computer Engineering: Faculty Publications (to 2015)

Smart antennas have emerged as one of the most promising directions in supporting maximum communication link throughput. In this paper, we have investigated the impact of smart antennas on a complex mobile network such as a railroad wireless communications system. The objective is to analyze the selection of a Direction-Of-Arrival (DOA) estimation algorithm which provides the maximum efficiency when deployed in our railroad testbeds for wireless vehicular communication. Our findings are discussed to provide an indepth understanding of how different algorithms should be selected to support efficient network operations.

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Quantitative Performance Analysis Of 3.65 Ghz Mobile Wimax, Pradhumna Shrestha, Michael Hempel, Puttipong Mahasukhon, Tao Ma, Hamid Sharif Jan 2012

Quantitative Performance Analysis Of 3.65 Ghz Mobile Wimax, Pradhumna Shrestha, Michael Hempel, Puttipong Mahasukhon, Tao Ma, Hamid Sharif

Department of Electrical and Computer Engineering: Faculty Publications (to 2015)

3.65 GHz Mobile WiMAX spectrum is often a better commercial solution due to its attractive licensing requirements, in spite of the slightly lower coverage area. However, no significant performance data has been reported for 3.65 GHz equipment behavior. In this paper, we have presented an in depth analysis of a 3.65 GHz Mobile WiMAX solution. Our reported data can also contribute in performing link budget analyses and benchmarking similar equipment.

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