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Articles 601 - 630 of 1069

Full-Text Articles in Computer Engineering

Tunable Plasmonic And Hyperbolic Metamaterials Based On Enhanced Nonlinear Response, Christos Argyropoulos, Francesco Monticone, Nasim Mohammadi Estakhri, Andrea Alu Jan 2014

Tunable Plasmonic And Hyperbolic Metamaterials Based On Enhanced Nonlinear Response, Christos Argyropoulos, Francesco Monticone, Nasim Mohammadi Estakhri, Andrea Alu

Department of Electrical and Computer Engineering: Faculty Publications

We present here tunable and reconfigurable designs of linear and nonlinear plasmonic and hyperbolic metamaterials. Rich scattering features of multilayered composite nanoparticles are demonstrated, which include complex and exotic scattering signatures combining multiple dipolar Fano resonances and electromagnetic induced transparency (EIT) features. These dipoledipole multi-Fano scattering responses can be further tuned through altering the plasmonic properties of the concentric layers or the permittivity of the core, for instance, by the presence of nonlinearities. Strong third-order nonlinear effects, such as optical bistability, may also be induced in the scattering response of nonlinear nanoparticles due to the highly enhanced and confined fields …


Bayesian Network Prior: Network Analysis Of Biological Data Using External Knowledge, Senol Isci, Haluk Dogan, Cengizhan Ozturk, Hasan H. Otu Jan 2014

Bayesian Network Prior: Network Analysis Of Biological Data Using External Knowledge, Senol Isci, Haluk Dogan, Cengizhan Ozturk, Hasan H. Otu

Department of Electrical and Computer Engineering: Faculty Publications

Motivation: Reverse engineering GI networks from experimental data is a challenging task due to the complex nature of the networks and the noise inherent in the data. One way to overcome these hurdles would be incorporating the vast amounts of external biological knowledge when building interaction networks. We propose a framework where GI networks are learned from experimental data using Bayesian networks (BNs) and the incorporation of external knowledge is also done via a BN that we call Bayesian Network Prior (BNP). BNP depicts the relation between various evidence types that contribute to the event ‘gene interaction’ and is used …


Element Dependence Of Enhancement In Optics Emission From Laser-Induced Plasma Under Spatial Confinement, Changmao Li, Lianbo Guo, Xiangnan He, Zhongqi Hao, Xiangyou Li, Meng Shen, Xiaoyan Zeng, Yongfeng Lu Jan 2014

Element Dependence Of Enhancement In Optics Emission From Laser-Induced Plasma Under Spatial Confinement, Changmao Li, Lianbo Guo, Xiangnan He, Zhongqi Hao, Xiangyou Li, Meng Shen, Xiaoyan Zeng, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

In this study, the element dependence of spatial confinement effects in LIBS has been studied. Hemispheric cavities were used to confine laser-induced plasmas from aluminum samples with other trace elements. The enhancement factors were found to be dependent on the elements. Equations describing the element dependent enhancement factors were successfully deduced from the local thermodynamic equilibrium conditions, which have also been verified by the experimental results. Research results show that enhancement factors in LIBS with spatial confinement depend on the temperature, electron density, and compression ratio of plasmas, and vary with elements and atomic/ionic emission lines selected. Generally, emission lines …


A Low-Power Compact Nqr Based Explosive Detection System, Xinwang Zhang, Nathan Schemm, Sina Balkır, Michael W. Hoffman Jan 2014

A Low-Power Compact Nqr Based Explosive Detection System, Xinwang Zhang, Nathan Schemm, Sina Balkır, Michael W. Hoffman

Department of Electrical and Computer Engineering: Faculty Publications

Nuclear quadruple resonance (NQR) has been studied for explosive detection for years. Some prototype NQR-based detection systems have been reported, but were all designed from the laboratory perspective, with bulky sizes and high power consumption. To achieve a portable NQR-based detection system for field applications, a low-power compact system utilizing state-of-the-art semiconductor technologies is presented in this paper. Several novel circuits for the key modules are proposed, including a Class-D type power amplifier, a power multiplexing and matching network, a customized IC with integrated analog signal processing chain, and a microcontroller-based logic control unit. An advanced digital signal processor platform …


Workplace Monitoring Of Employee Health Using The Workstation Pc As A Platform, Priyankar Bhattacharjee Jan 2014

Workplace Monitoring Of Employee Health Using The Workstation Pc As A Platform, Priyankar Bhattacharjee

Department of Electrical and Computer Engineering: Faculty Publications

A country’s biggest asset is its workforce, given the fact that a healthy workforce can contribute to rapid growth of the economy. Chronic illnesses reduce productivity, are responsible for rising healthcare costs, and should be managed by the employer to reduce healthcare expenditures. This can be done through employee health and wellness programs, and well-designed health management initiatives. In addition, new information and communication technologies make it possible to monitor employee health with wearable devices and telehealth assisted surveillance techniques. This paper introduces a unique new approach to workplace healthcare monitoring, using the office workstation PC itself to monitor worker …


Clu: Co-Optimizing Locality And Utility In Thread-Aware Capacity Management For Shared Last Level Caches, Dongyuan Zhan, Hong Jiang, Sharad C. Seth Jan 2014

Clu: Co-Optimizing Locality And Utility In Thread-Aware Capacity Management For Shared Last Level Caches, Dongyuan Zhan, Hong Jiang, Sharad C. Seth

Department of Electrical and Computer Engineering: Faculty Publications

Most chip-multiprocessors nowadays adopt a large shared last-level cache (SLLC). This paper is motivated by our analysis and evaluation of state-of-the-art cache management proposals which reveal a common weakness. That is, the existing alternative replacement policies and cache partitioning schemes, targeted at optimizing either locality or utility of co-scheduled threads, cannot deliver consistently the best performance under a variety of workloads. Therefore, we propose a novel adaptive scheme, called CLU, to interactively co-optimize the locality and utility of co-scheduled threads in thread-aware SLLC capacity management. CLU employs lightweight monitors to dynamically profile the LRU (least recently used) and BIP (bimodal …


Intelligent Maximum Power Extraction Control For Wind Energy Conversion Systems Based On Online Q-Learning With Function Approximation, Chun Wei, Zhe Zhang, Wei Qiao, Liyan Qu Jan 2014

Intelligent Maximum Power Extraction Control For Wind Energy Conversion Systems Based On Online Q-Learning With Function Approximation, Chun Wei, Zhe Zhang, Wei Qiao, Liyan Qu

Department of Electrical and Computer Engineering: Faculty Publications

This paper proposes an intelligent maximum power point tracking (MPPT) algorithm for variable-speed wind energy conversion systems (WECSs) based on an online Q-learning algorithm. Instead of using the conventional Qlearning that uses a lookup table to store the action values for the discretized states, artificial neural networks (ANNs) are used as function approximators to output the action values by using the electrical power and rotor speed of the generator as inputs. This eliminates the need for a large storage memory. The proposed method learns the optimal speed control strategy of the WECS by updating the connecting weights of the ANNs, …


Effects Of Droplet Diameter On The Leidenfrost Temperature Of Laser Processed Multiscale Structured Surfaces, Anton Hassebrook, Corey Kruse, Chris Wilson, Troy P. Anderson, Craig Zuhlke, Dennis R. Alexander, George Gogos, Sidy Ndao Jan 2014

Effects Of Droplet Diameter On The Leidenfrost Temperature Of Laser Processed Multiscale Structured Surfaces, Anton Hassebrook, Corey Kruse, Chris Wilson, Troy P. Anderson, Craig Zuhlke, Dennis R. Alexander, George Gogos, Sidy Ndao

Department of Electrical and Computer Engineering: Faculty Publications

In this paper, an experimental investigation of the effects of droplet diameters on the Leidenfrost temperature and its shifts has been carried out. Tests were conducted on a 304 stainless steel polished surface and a stainless steel surface which was processed by a femtosecond laser to form Above Surface Growth (ASG) nano/microstructures. To determine the Leidenfrost temperatures, the droplet lifetime method was employed for both the polished and processed surfaces. A precision dropper was used to vary the size of droplets from 1.5 to 4 millimeters. The Leidenfrost temperature was shown to display shifts as high as 85 ˚C on …


Optimum Renewable Generation Capacities In A Microgrid Using Generation Adequacy Study, Salman Kahrobaee, Sohrab Asgarpoor, Milad Kahrobaee Jan 2014

Optimum Renewable Generation Capacities In A Microgrid Using Generation Adequacy Study, Salman Kahrobaee, Sohrab Asgarpoor, Milad Kahrobaee

Department of Electrical and Computer Engineering: Faculty Publications

Microgrids, as small power systems, may be comprised of different types of loads and distributed generation. As the integration of renewable power generation increases, the total available generation capacity of the system will be more derated due to the effect of equipment failures and the intermittent nature of these resources. Therefore, it is critical to determine optimum renewable generation capacities and provide enough reserve margin to meet the target reliability of the microgrid. In this paper, we first model a microgrid, including conventional and renewable distributed generation and the loads. Second, we determine the renewable generation capacity required to meet …


State Of Charge Estimation Based On A Realtime Battery Model And Iterative Smooth Variable Structure Filter, Taesic Kim, Yebin Wang, Zafer Sahinoglu, Toshihiro Wada, Satoshi Hara, Wei Qiao Jan 2014

State Of Charge Estimation Based On A Realtime Battery Model And Iterative Smooth Variable Structure Filter, Taesic Kim, Yebin Wang, Zafer Sahinoglu, Toshihiro Wada, Satoshi Hara, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

This paper proposes a novel real-time model-based state of charge (SOC) estimation method for lithium-ion batteries. The proposed method includes: 1) an electrical circuit battery model incorporating the hysteresis effect, 2) a fast upper-triangular and D-diagonal recursive least square (FUDRLS)-based online parameter identification algorithm for the electrical battery model, and 3) an iterated smooth variable structure filter (ISVSF) for SOC estimation. The proposed method enables an accurate and robust condition monitoring for lithium-ion batteries. Due to its low complexity, the proposed method is suitable for the real-time embedded battery management system (BMS) application. Simulation and experiment are performed to validate …


Design And Implementation Of A Low-Cost Embedded Linux Gateway For Smart Home Health Monitoring, Mateusz Mittek, Jay D. Carlson, Lance C. Pérez Jan 2014

Design And Implementation Of A Low-Cost Embedded Linux Gateway For Smart Home Health Monitoring, Mateusz Mittek, Jay D. Carlson, Lance C. Pérez

Department of Electrical and Computer Engineering: Faculty Publications

Many wireless sensor network applications require a gateway device to interface with services running on the Internet. Because of the software complexity involved in this device, it is often realized using a real-time operating system running on an application processor. Most systems burden the user with developing the protocol handling and device configuration and management inside the application. In this paper, we present the Angelos Gateway – a turnkey, low-cost, Linux-powered WSN gateway that provides a socket-based environment for rapid network-enabled application development. Experimental results demonstrate that the proposed device is capable of high-throughput packet I/O, confirming the efficacy of …


Automated Indoor Rfid Inventorying Using A Self-Guided Micro-Aerial Vehicle, Steven A. Parkison, Eric T. Psota, Lance C. Pérez Jan 2014

Automated Indoor Rfid Inventorying Using A Self-Guided Micro-Aerial Vehicle, Steven A. Parkison, Eric T. Psota, Lance C. Pérez

Department of Electrical and Computer Engineering: Faculty Publications

A Micro-Aerial Vehicle (MAV) system is presented for automated indoor inventorying using passive radio frequency identification (RFID). This system utilizes a combination of onboard sensing and processing in order to achieve flight stabilization, generate floor maps, and perform path planning. The proposed state estimation method along with a control feedback strategy are demonstrated to be sufficiently accurate for operation in the indoor environment and the proposed path planning technique is shown to be effective for guiding the MAV while it performs automated RFID scanning.


Achieving Robustness And Capacity Gains In Covert Timing Channels, Fahimeh Rezaei, Michael Hempel, Pradhumna Lal Shrestha, Hamid Sharif Jan 2014

Achieving Robustness And Capacity Gains In Covert Timing Channels, Fahimeh Rezaei, Michael Hempel, Pradhumna Lal Shrestha, Hamid Sharif

Department of Electrical and Computer Engineering: Faculty Publications

In this paper, we introduce a covert timing channel (CTC) algorithm and compare it to one of the most prevailing CTC algorithms, originally proposed by Cabuk et al. CTC is a form of covert channels – methods that exploit network activities to transmit secret data over packet-based networks – by modifying packet timing. This algorithm is a seminal work, one of the most widely cited CTCs, and the foundation for many CTC research activities. In order to overcome some of the disadvantages of this algorithm we introduce a covert timing channel technique that leverages timeout thresholds. The proposed algorithm is …


Monitoring Igbt’S Health Condition Via Junction Temperature Variations, Bo Tian, Wei Qiao, Ze Wang, Tanya Gachovska, Jerry L. Hudgins Jan 2014

Monitoring Igbt’S Health Condition Via Junction Temperature Variations, Bo Tian, Wei Qiao, Ze Wang, Tanya Gachovska, Jerry L. Hudgins

Department of Electrical and Computer Engineering: Faculty Publications

Insulated gate bipolar transistor (IGBT) failures are a major issue in modern power electronics applications. Two most dominated failure mechanisms of IGBTs are solder fatigue and bond wire wear-out. This paper proposes a new method to online monitor an IGBT’s health condition by using the instantaneous junction temperature variation between present and the first operating cycles of the IGBT with the same operating current. In this work, the instantaneous junction temperature of an IGBT is estimated from a thermal network model. The proposed method is validated by experimental results obtained from accelerated aging tests for IGBTs.


Diversity Order And Coding Gain Of General-Order Rectangular Qam In Mimo Relay With Tas/Mrc In Nakagami-M Fading, Won Mee Jang Jan 2014

Diversity Order And Coding Gain Of General-Order Rectangular Qam In Mimo Relay With Tas/Mrc In Nakagami-M Fading, Won Mee Jang

Department of Electrical and Computer Engineering: Faculty Publications

Recently, multiple-input–multiple-output (MIMO) relay networks have been an active area of research, particularly with combining single transmit antenna selection (TAS) and receiver maximal ratio combining (MRC). Moreover, generalorder rectangular quadrature amplitude modulation (QAM) has received much attention for its high spectral efficiency and flexible modulation scheme. However, the analytical performance of general-order rectangular QAM has not been found in the literature forMIMO relay with TAS/MRC in Nakagami-mfading channels in spite of its practical usefulness. In addition, the analytical performance of general-order rectangular QAM often comes with enormous computational complexity. Therefore, it is hardly possible to understand the analytical solution unless …


Yeast Pheromone Pathway Modeling Using Petri Nets, Stephen D. Scott, Abhishek Majumdar, Jitender S. Deogun, Steven D. Harris Jan 2014

Yeast Pheromone Pathway Modeling Using Petri Nets, Stephen D. Scott, Abhishek Majumdar, Jitender S. Deogun, Steven D. Harris

School of Computing: Conference and Workshop Papers

Background: Our environment is composed of biological components of varying magnitude. The relationships between the different biological elements can be represented as a biological network. The process of mating in S. cerevisiae is initiated by secretion of pheromone by one of the cells. Our interest lies in one particular question: how does a cell dynamically adapt the pathway to continue mating under severe environmental changes or under mutation (which might result in the loss of functionality of some proteins known to participate in the pheromone pathway). Our work attempts to answer this question. To achieve this, we first propose a …


A Comparison Of A Campus Cluster And Open Science Grid Platforms For Protein- Guided Assembly Using Pegasus Workflow Management System, Natasha Pavlovikj, Kevin Begcy, Sairam Behera, Malachy Campbell, Harkamal Walia, Jitender S. Deogun Jan 2014

A Comparison Of A Campus Cluster And Open Science Grid Platforms For Protein- Guided Assembly Using Pegasus Workflow Management System, Natasha Pavlovikj, Kevin Begcy, Sairam Behera, Malachy Campbell, Harkamal Walia, Jitender S. Deogun

School of Computing: Conference and Workshop Papers

Scientific workflows are a useful tool for managing large and complex computational tasks. Due to its intensive resource requirements, the scientific workflows are often executed on distributed platforms, including campus clusters, grids and clouds. In this paper we build a scientific workflow for blast2cap3, the protein-guided assembly, using the Pegasus Workflow Management System (Pegasus WMS). The modularity of blast2cap3 allows us to decompose the existing serial approach on multiple tasks, some of which can be run in parallel. Afterwards, this workflow is deployed on two distributed execution platforms: Sandhills, the University of Nebraska Campus Cluster, and the Open Science …


Transforming Web Tables To A Relational Database, David W. Embley, George Nagy, Sharad C. Seth Jan 2014

Transforming Web Tables To A Relational Database, David W. Embley, George Nagy, Sharad C. Seth

School of Computing: Conference and Workshop Papers

HTML tables represent a significant fraction of web data. The often complex headers of such tables are determined accurately using their indexing property. Isolated headers are factored to extract category hierarchies. Web tables are then transformed into a canonical form and imported into a relational database. The proposed processing allows for the formulation of arbitrary SQL queries over the collection of induced relational tables.


A Ga-Svm Hybrid Classifier For Multiclass Fault Identification Of Drivetrain Gearboxes, Dingguo Lu, Wei Qiao Jan 2014

A Ga-Svm Hybrid Classifier For Multiclass Fault Identification Of Drivetrain Gearboxes, Dingguo Lu, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

This paper presents a genetic algorithm (GA)- support vector machine (SVM) hybrid classifier for multiclass fault identification of drivetrain gearboxes in variable-speed operational conditions. An adaptive feature extraction algorithm is employed to effectively extract the features of gearbox faults from the stator current signal of an AC machine connected to the gearbox. The multiclass GA-SVM classifier is used to identify the faults in the gearbox according to the fault features extracted. A GA is designed to find the optimal parameters of the SVM to obtain the best classification accuracy. The proposed hybrid classifier is validated on a gearbox connected with …


Optimal Energy Scheduling For A Smart Entity, Amin Fakhrazari, Hamid Vakilzadian, F. Fred Choobineh Jan 2014

Optimal Energy Scheduling For A Smart Entity, Amin Fakhrazari, Hamid Vakilzadian, F. Fred Choobineh

Department of Electrical and Computer Engineering: Faculty Publications

Real-time availability of electricity prices via a smart power grid has a potential bilateral benefit to electricity users and suppliers. The users can reduce their costs by consuming energy during low-price hours and balancing their energy usage during other hours. This in turn benefits energy utility companies by reducing their peak power demand. This article describes an optimal shrinking horizon model for electricity-consuming units based on user preferences. The proposed model optimizes the end user’s electricity cost while meeting preferred comfort levels. The user can set preferences in the model using a tristate flexibility parameter for each electric-power-consuming unit. The …


A Security Protocol For Advanced Metering Infrastructure In Smart Grid, Feng Ye, Yi Qian, Rose Qingyang Hu Jan 2014

A Security Protocol For Advanced Metering Infrastructure In Smart Grid, Feng Ye, Yi Qian, Rose Qingyang Hu

Department of Electrical and Computer Engineering: Faculty Publications

In this paper, we propose a security protocol for advanced metering infrastructure (AMI) in smart grid. AMI is one of the important components in smart grid and it suffers from various vulnerabilities due to its uniqueness compared with wired networks and traditional wireless mesh networks. Our proposed security protocol for AMI includes initial authentication, secure uplink data aggregation/recovery, and secure downlink data transmission. Compared with existing researches in such area, our proposed security protocol let the customers be treated fairly, the privacy of customers be protected, and the control messages from the service provider be delivered safely and timely.


Free Space Optical Data Center Architecture Design With Fully Connected Racks, Abdelbaset S. Hamza, Jitender S. Deogun, Dennis R. Alexander Jan 2014

Free Space Optical Data Center Architecture Design With Fully Connected Racks, Abdelbaset S. Hamza, Jitender S. Deogun, Dennis R. Alexander

Department of Electrical and Computer Engineering: Faculty Publications

In this paper, we propose a novel design of a data center (DC) using free space optical (FSO) technology. The proposed FSO-DC design is based on fixed, non-mechanical, FSO links facilitating the realization of fully connected FSO racks and rows/columns of racks. Each rack becomes a point of intersection of three fully connected sub-networks. We investigate requirements, advantages and challenges of the proposed design. We develop and analyze a switch-free, fully connected FSO rack, present its link budget analysis and validate it by simulation. Results establish the feasibility of a switch-free FSO rack based on the proposed FSO-DC design. A …


Enhanced Pool-Boiling Heat Transfer And Critical Heat Flux Using Femtosecond Laser Surface Processing, Corey M. Kruse, Troy P. Anderson, Chris Wilson, Craig A. Zuhlke, Dennis R. Alexander, George Gogos, Sidy Ndao Jan 2014

Enhanced Pool-Boiling Heat Transfer And Critical Heat Flux Using Femtosecond Laser Surface Processing, Corey M. Kruse, Troy P. Anderson, Chris Wilson, Craig A. Zuhlke, Dennis R. Alexander, George Gogos, Sidy Ndao

Department of Electrical and Computer Engineering: Faculty Publications

In this paper, we present the experimental investigation of pool boiling heat transfer on multiscale (micro/nano) functionalized metallic surfaces. The multiscale structures were fabricated via a femtosecond laser surface process (FLSP) technique which forms mound-like microstructures covered by layers of nanoparticles. Using a pool boiling experimental setup with deionized water as the working fluid, both the heat transfer coefficient and critical heat flux were investigated. The polished reference sample was found to have a critical heat flux of 91 W/cm2 at 40 °C of superheat and a maximum heat transfer coefficient of 23,000 W/m2-K. The processed sample …


Fault Diagnosis For Drivetrain Gearboxes Using Pso-Optimized Multiclass Svm Classifier, Dingguo Lu, Wei Qiao Jan 2014

Fault Diagnosis For Drivetrain Gearboxes Using Pso-Optimized Multiclass Svm Classifier, Dingguo Lu, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

A novel method consisting of an adaptive feature extraction scheme and a particle swarm optimization (PSO)- optimized multiclass support vector machine (SVM) classifier is proposed for condition monitoring and fault diagnosis of drivetrain gearboxes in variable-speed operational conditions. The adaptive feature extraction scheme consists of an adaptive signal resampling algorithm, a frequency tracker, and a feature generation algorithm for effective extraction of the features of gearbox faults from the stator current signal of the AC electric machine connected to the gearbox. The multiclass SVM classifier is designed to identify different faults in the gearbox according to the fault features extracted. …


Characterizing The Rf Performance Of The Ez430-Chronos Wrist Watch, Francisco J. Mora-Becerra, Pedro Sathler, Jay D. Carlson, Eric T. Psota, Lance C. Pérez Jan 2014

Characterizing The Rf Performance Of The Ez430-Chronos Wrist Watch, Francisco J. Mora-Becerra, Pedro Sathler, Jay D. Carlson, Eric T. Psota, Lance C. Pérez

Department of Electrical and Computer Engineering: Faculty Publications

The Texas Instruments eZ430-Chronos development kit is a popular wireless platform for researchers, commercial developers, and hobbyists. Built into the form factor of a standard wrist watch, the Chronos is ideal for wireless body area networks (WBANs), indoor localization, and activity detection. Many of these applications requires knowledge of the RF performance of the platform, which has never been characterized by Texas Instruments nor any third parties. Here, we provide experimental data characterizing the RF performance of the eZ430-Chronos watch in various configurations, including when worn by a person while sitting, standing, and reaching. The RF performance of the Chronos …


Steganography Attack Based On Discrete Spring Transform And Image Geometrization, Qilin Qi, Aaron Sharp, Yaoqing Lamar Yang, Dongming Peng, Hamid Sharif Jan 2014

Steganography Attack Based On Discrete Spring Transform And Image Geometrization, Qilin Qi, Aaron Sharp, Yaoqing Lamar Yang, Dongming Peng, Hamid Sharif

Department of Electrical and Computer Engineering: Faculty Publications

In order to prevent harmful secret information sharing by steganography, a new active-warden countermeasure approach against steganography is proposed in this paper. Differently from the other countermeasure approaches presented in current literature which need to have some knowledge of the steganographic algorithms to be attacked, our proposed method is a generic method which is independent of any particular steganography methods being utilized. In other words, our approach blindly attacks the steganography without any prior knowledge of the used algorithms or their existence. In general, the hidden information is embedded in a carrier by adjusting the coefficients of the audio or …


Study On Case Temperature Distribution For Condition Monitoring Of Multidie Igbt Modules, Bo Tian, Ze Wang, Wei Qiao Jan 2014

Study On Case Temperature Distribution For Condition Monitoring Of Multidie Igbt Modules, Bo Tian, Ze Wang, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

The parasitic and proximity effects in multidie insulated-gate bipolar transistor (IGBT) modules lead to nonuniform distributions of junction temperature (TJ) and case temperature (TC) among different dies. This feature can be used to monitor the operating and health condition of multidie IGBT modules. This paper reports a comprehensive study on the distribution of TC and its influence on TJ estimation using a thermal network model for a multidie IGBT module before and after aging. Specifically, experimental studies using accelerated aging tests are conducted for a 9-die IGBT module. Results demonstrate that the …


Modeling Molecular Communications At Nano-Scale With Applications In Medicine And Microbiology, Tadeusz A. Wysocki Jan 2014

Modeling Molecular Communications At Nano-Scale With Applications In Medicine And Microbiology, Tadeusz A. Wysocki

Department of Electrical and Computer Engineering: Faculty Publications

No abstract provided.


An Isolated Multiport Bidirectional Dc-Dc Converter For Pv-Battery-Dc Microgrid Applications, Jianwu Zeng, Wei Qiao, Liyan Qu Jan 2014

An Isolated Multiport Bidirectional Dc-Dc Converter For Pv-Battery-Dc Microgrid Applications, Jianwu Zeng, Wei Qiao, Liyan Qu

Department of Electrical and Computer Engineering: Faculty Publications

This paper proposes a new isolated, multiport, bidirectional DC-DC converter with the least number of switches for photovoltaic (PV)-battery-DC microgrid applications. The proposed converter is able to perform the maximum power point tracking (MPPT) control for the PV system when solar energy is available as well as control the charge and discharge of the battery with the PV system and the DC microgrid. Simulation and experimental studies are carried out and validate the proposed converter for simultaneous power management of a PV-battery system connected to a DC microgrid.


A Low-Power Compact Nqr Based Explosive Detection System, Xinwang Zhang, Nathan Schemm, Sina Balkır, Michael W. Hoffman Jan 2014

A Low-Power Compact Nqr Based Explosive Detection System, Xinwang Zhang, Nathan Schemm, Sina Balkır, Michael W. Hoffman

Department of Electrical and Computer Engineering: Faculty Publications

Nuclear quadruple resonance (NQR) has been studied for explosive detection for years. Some prototype NQR-based detection systems have been reported, but were all designed from the laboratory perspective, with bulky sizes and high power consumption. To achieve a portable NQR-based detection system for field applications, a low-power compact system utilizing state-of-the-art semiconductor technologies is presented in this paper. Several novel circuits for the key modules are proposed, including a Class-D type power amplifier, a power multiplexing and matching network, a customized IC with integrated analog signal processing chain, and a microcontroller-based logic control unit. An advanced digital signal processor platform …