Computer Engineering Commons^™

Segmented Nanowires Displaying Locally Controllable Properties, Eli Anguelova Sutter, Peter Werner Sutter

Department of Electrical and Computer Engineering: Faculty Publications

Vapor-liquid-solid growth of nanowires is tailored to achieve complex one-dimensional material geometries using phase diagrams determined for nanoscale materials. Segmented one-dimensional nanowires having constant composition dis play locally variable electronic band structures that are deter mined by the diameter of the nanowires. The unique electrical and optical properties of the segmented nanowires are exploited to form electronic and optoelectronic devices. Using gold-germanium as a model system, in situ transmis sion electron microscopy establishes, for nanometer-sized Au Ge alloy drops at the tips of Ge nanowires (NWs), the parts of the phase diagram that determine their temperature dependent equilibrium composition. The …

Test Advising Framework, Yurong Wang

School of Computing: Dissertations, Theses, and Student Research

Test cases are represented in various formats depending on the process, the technique or the tool used to generate the tests. While different test case representations are necessary, this diversity challenges us in comparing test cases and leveraging strengths among them - a common test representation will help.

In this thesis, we define a new Test Case Language (TCL) that can be used to represent test cases that vary in structure and are generated by multiple test generation frameworks. We also present a methodology for transforming test cases of varying representations into a common format where they can be matched …

Xing-Zone Bridge Construction For Multi-Hop Cognitive Radio Networks With Channel Bonding, Feng Ye, Yi Qian, Yaoqing Lamar Yang, Hamid Sharif

Department of Electrical and Computer Engineering: Faculty Publications

Cognitive radio is an efficient technique to relieve the tense of wireless spectrum scarcity by allowing unlicensed secondary users (SUs) to access the licensed band opportunistically without causing interference to primary users (PUs). Although Federal Communications Commission (FCC) recently ruled that the data of PU activity schedule is accessible to SUs 24 hours ahead, which relieves SUs from heavy sensing or interruption by sudden PU activity, however, multi-hop wireless cognitive radio networks (MWCRN) suffers a unique problem caused by the fact that the spectrum resources are not unified in different areas affected by different PUs. In other words, an SU …

A Hierarchical Power Management Strategy For Multiple Single-Phase Roadway Microgrids, Yanping Jiao, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

This paper proposes a centralized hierarchical power management strategy for multiple single-phase wind/solar generation-based roadway microgrids integrated into a threephase utility distribution grid. The proposed power management strategy consists of a Central Power Management Controller (CPMC) operating at the distribution grid level to regulate the power flow between the distribution grid and the microgrids, a Supervisory Power Management Controller (SPMC) operating at the microgrid level for voltage and frequency control of each microgrid under the coordination of the CPMC, and a Local Power Management Controller operating at the unit level for power management of each individual unit under the coordination …

Sizing Router Buffer For The Internet With Heterogeneous Tcp, Peng Yang, Ertong Zhang, Lisong Xu

Department of Electrical and Computer Engineering: Faculty Publications

The router buffer sizing problem is a vital problem to the performance of the Internet. The traditional rule-of-thumb is that the router buffer size should be equal to the bandwidthdelay product (BDP) of a link. Recent studies show that the router buffer size can be significantly smaller than the BDP without causing negative impact on the TCP performance in the Internet. But a fundamental assumption of all those studies is that all the TCP traffic in the Internet is generated by the traditional RENO protocol, which, however, is no longer true as the current Internet is dominated by multiple different …

Stability And Dynamic Performance Improvement Of A Sensorless Ipmsm Drive Via Adaptive Estimated-Speed- Assisted Position Prediction And Current Quality Evaluation, Yue Zhao, Wei Qiao, Long Wu

Department of Electrical and Computer Engineering: Faculty Publications

This paper studies stability issues of sensorless torque control of high power interior permanent magnet synchronous machines (IPMSMs) under large load transients, e.g., complete torque reversals with the highest slew rate allowed. To perform a sensorless vector control, a current model-based sliding-mode observer is utilized to estimate the rotor position. The correlation between current regulation quality and position estimation accuracy is theoretically studied and experimentally verified. Based on the correlation, the accuracy of position estimation can be evaluated online indirectly. Moreover, an adaptive estimated-speed-assisted position prediction (ESAPP) scheme is proposed to improve the stability and performance of the sensorless control …

On Physical Layer Security For Cognitive Radio Networks, Zhihui Shu, Yi Qian, Song Ci

Department of Electrical and Computer Engineering: Faculty Publications

In this article we explore the security issues on physical layer for cognitive radio networks. First we give an overview on several existing security attacks to the physical layer in cognitive radio networks. We then discuss the related countermeasures on how to defend against these attacks. We further investigate one of the most important physical layer security parameters, the secrecy capacity of a cognitive radio network, and study the outage probability of secrecy capacity of a primary user from a theoretical point of view. Furthermore, we present performance results for secrecy capacity and outage probability between a node and its …

Wind Turbine Fault Detection And Isolation Using Support Vector Machine And A Residual-Based Method, Jianwu Zeng, Dingguo Lu, Yue Zhao, Zhe Zhang, Wei Qiao, Xiang Gong

Department of Electrical and Computer Engineering: Faculty Publications

This paper proposes a novel scheme combining support vector machines (SVM) and a residual-based method for wind turbine fault detection and isolation (FDI). SVMs with radius basis function kernels are used for detecting and identifying sensor stuck and offset faults, where binary codes of fault types are used as the outputs of the SVMs to minimize the number of SVMs being used. The same output of a SVM may correspond to different types of faults and the final decision is made by all SVMs instead of one SVM. Moreover, a residual-based fault detection method using a time-variant threshold is developed …

Multilayered Plasmonic Covers For Comblike Scattering Response And Optical Tagging, Francesco Monticone, Christos Argyropoulos, Andrea Alu

Department of Electrical and Computer Engineering: Faculty Publications

We discuss the potential of multilayered plasmonic particles to tailor the optical scattering response. The interplay of plasmons localized in thin stacked shells realizes peculiar degenerate cloaking and resonant states occurring at arbitrarily close frequencies. These concepts are applied to realize ultrasharp comblike scattering responses and synthesize staggered, ideally strong superscattering states closely coupled to invisible states. We demonstrate robustness to material losses and to variations in the background medium, properties that make these structures ideal for optical tagging.

Broadband Absorbers And Selective Emitters Based On Plasmonic Brewster Metasurfaces, Christos Argyropoulos, Khai Q. Le, Nadia Mattiucci, Giuseppe D'Aguanno, Andrea Alu

Department of Electrical and Computer Engineering: Faculty Publications

We discuss the possibility of realizing utlrabroadband omnidirectional absorbers and angularly selective coherent thermal emitters based on properly patterned plasmonic metastructures. Instead of relying on resonant concentration effects that inherently limit the bandwidth, we base our design on the combination of two inherently nonresonant effects: plasmonic Brewster funneling and adiabatic plasmonic focusing. Using this approach, we propose compact, broadband absorption and emission spanning terahertz, infrared, and optical frequencies, ideal for various energy and defense applications.

Plasmonic Nanoparticles And Metasurfaces To Realize Fano Spectra At Ultraviolet Wavelengths, Christos Argyropoulos, Francesco Monticone, Giuseppe D'Aguanno, Andrea Alu

Department of Electrical and Computer Engineering: Faculty Publications

We discuss the possibility to realize sharp Fano scattering signatures in the ultraviolet (UV) range, based on dipolar scattering of nanoparticles. At these frequencies, material losses usually do not allow sharp resonant effects, hindering plasmonic applications based on higher-order multipolar modes, like conventional Fano resonances. We propose to excite degenerate scattering states supported by core-shell nanoparticles made of a sapphire core and an aluminum shell. We predict enhanced, highly confined fields, supporting sharp far-field scattering signatures from single nanoparticles and planar arrays of them. These results may lead to the design of UV filters, photodetectors, sensors, and energy-harvesting devices.

Prediction Of Peptides Binding To Mhc Class I And Ii Alleles By Temporal Motif Mining, Cem Meydan, Hasan H. Otu, Osman Ugur Sezerman

Department of Electrical and Computer Engineering: Faculty Publications

Background: MHC (Major Histocompatibility Complex) is a key player in the immune response of most vertebrates. The computational prediction of whether a given antigenic peptide will bind to a specific MHC allele is important in the development of vaccines for emerging pathogens, the creation of possibilities for controlling immune response, and for the applications of immunotherapy. One of the problems that make this computational prediction difficult is the detection of the binding core region in peptides, coupled with the presence of bulges and loops causing variations in the total sequence length. Most machine learning methods require the sequences to be …

Exploring The Microsoft .Net Micro Framework For Prototyping Applied Wireless Sensor Networks, Jay D. Carlson, Mateusz Mittek, Lance C. Pérez

Department of Electrical and Computer Engineering: Faculty Publications

Most Wireless Sensor Network platforms – such as the Mica, Iris, and Telos B families of motes – use lowpower 8-bit microprocessors which have limited memory and processing capabilities, thus requiring researchers to implement communication protocols and data processing routines using lowlevel programming practices that are tedious and cumbersome. Rich features available in modern desktop operating systems – such as threads, memory management, and exception-handling – are largely absent. The Microsoft .NET Micro Framework implements a scaled-back .NET framework suitable for development on low-cost, low-power wireless sensors, while providing developers a rapid software development environment for prototyping embedded applications. Here, …

Bearing Fault Diagnosis For Direct-Drive Wind Turbines Via Current-Demodulated Signals, Xiang Gong, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

Bearing faults account for a large portion of all faults in wind turbine generators (WTGs). Current-based bearing fault diagnosis techniques have great economic benefits and are potential to be adopted by the wind energy industry. This paper models the modulation effects of bearing faults on the stator currents of a direct-drive wind turbine equipped with a permanent-magnet synchronous generator (PMSG) operating with a variable shaft rotating frequency. Based on the analysis, a method consisting of appropriate current frequency and amplitude demodulation algorithms and a 1P-invariant power spectrum density algorithm is proposed for bearing fault diagnosis of variable-speed direct-drive wind turbines …

Inactivation Of E. Coli Affected By Medium Conductivity In Pulsed Electric Field Processing, Tanya Kirilova Gachovska, Jeyamkondan Subbiah, Harshavardhan Thippareddi, David Marx, Frazer Williams

Department of Electrical and Computer Engineering: Faculty Publications

No abstract provided.

Vibration Energy Harvesting For Wireless Underground Sensor Networks, Salman Kahrobaee, Mehmet C. Vuran

Department of Electrical and Computer Engineering: Faculty Publications

Recent developments in wireless underground communication have enabled the realization of underground sensor network applications. To this end, it is desirable to provide a sustainable operation for wireless underground sensor networks (WUSNs) with extended lifetimes as maintenance is significantly costly. One promising method towards sustainable operation is to harvest energy underground based on the vibration sources in the environment. However, to the best of our knowledge, underground vibration energy harvesting has not been investigated before. In this paper, the feasibility of vibration energy harvesting for WUSNs is investigated. First, an analytical framework is developed to model the maximum harvestable power …

A Multiagent Modeling And Investigation Of Smart Homes With Power Generation, Storage, And Trading Features, Salman Kahrobaee, Rasheed A. Rajabzadeh, Leen-Kiat Soh, Sohrab Asgarpoor

Department of Electrical and Computer Engineering: Faculty Publications

Smart homes, as active participants in a smart grid, may no longer be modeled by passive load curves; because their interactive communication and bidirectional power flow within the smart grid affects demand, generation, and electricity rates. To consider such dynamic environmental properties, we use a multiagent-system-based approach in which individual homes are autonomous agents making rational decisions to buy, sell, or store electricity based on their present and expected future amount of load, generation, and storage, accounting for the benefits each decision can offer. In the proposed scheme, home agents prioritize their decisions based on the expected utilities they provide. …

Optimum Sizing Of Distributed Generation And Storage Capacity In Smart Households, Salman Kahrobaee, Sohrab Asgarpoor, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

In the near future, a smart grid will accommodate customers who are prepared to invest in generation-battery systems and employ energymanagement systems in order to cut down on their electricity bills. The main objective of this paper is to determine the optimum capacity of a customer’s distributed-generation system (such as a wind turbine) and battery within the framework of a smart grid. The proposed approach involves developing an electricity management system based on stochastic variables, such as wind speed, electricity rates, and load. Then, a hybrid stochastic method based on Monte Carlo simulation and particle swarm optimization is proposed to …

Real-Time Stereo Matching On Cuda Using An Iterative Refinement Method For Adaptive Support-Weight Correspondences, Jedrzej Kowalczuk, Eric T. Psota, Lance C. Pérez

Department of Electrical and Computer Engineering: Faculty Publications

High-quality real-time stereo matching has the potential to enable various computer vision applications including semi-automated robotic surgery, teleimmersion, and 3-D video surveillance. A novel real-time stereo matching method is presented that uses a two-pass approximation of adaptive supportweight aggregation, and a low-complexity iterative disparity refinement technique. Through an evaluation of computationally efficient approaches to adaptive support-weight cost aggregation, it is shown that the two-pass method produces an accurate approximation of the support weights while greatly reducing the complexity of aggregation. The refinement technique, constructed using a probabilistic framework, incorporates an additive term into matching cost minimization and facilitates iterative processing …

Adaptive Feature Extraction And Svm Classification For Real-Time Fault Diagnosis Of Drivetrain Gearboxes, Dingguo Lu, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

Drivetrain gearboxes play an important role in many modern industrial applications. This paper presents a novel method consisting of adaptive feature extraction and support vector machine (SVM)-based classification for condition monitoring and fault diagnosis of drivetrain gearboxes operating in variable-speed conditions. An adaptive signal resampling algorithm, a frequency tracker, and a feature generation algorithm are integrated in the proposed method for effective extraction of the features of gearbox faults from the stator current signal of the AC electric machine connected to the gearbox. A radial basis function kernel-SVM classifier is designed to identify the fault in the gearbox according to …

Achievable Throughput Regions Of Fading Broadcast And Interference Channels Under Qos Constraints, Deli Qiao, Mustafa Cenk Gursoy, Senem Velipasalar

Department of Electrical and Computer Engineering: Faculty Publications

Transmission over fading broadcast and interference channels in the presence of quality of service (QoS) constraints is studied. Effective capacity, which provides the maximum constant arrival rate that a given service process can support while satisfying statistical QoS constraints, is employed as the performance metric. In the broadcast scenario, the effective capacity region achieved with superposition coding and successive interference cancellation is identified and is shown to be convex. Subsequently, optimal power control policies that achieve the boundary points of the effective capacity region are investigated, and an algorithm for the numerical computation of the optimal power adaptation schemes for …

Adaptive Threshold Displacement Algorithm For Removing Hidden Information From Digital Images, Fahimeh Rezaei, Michael Hempel, Tao Ma, Pradhumna Lal Shrestha, Dongming Peng, Hamid Sharif

Department of Electrical and Computer Engineering: Faculty Publications

The growth of the Internet and online social media, especially in recent years, also gave rise to a proliferation of online multimedia content creation and distribution. The use of modern steganography methods – the art of hiding information within multimedia – presents an unprecedented opportunity for malicious uses of these materials. Therefore, developing an effective technique to avoid the distribution of secret data is a significant problem that is addressed in this paper for digital images. We introduce a novel algorithm to remove the steganography information embedded in an image without changing the quality of the image and with no …

Adaptive Channel Allocation And Routing In Cognitive Radio Networks, Zhihui Shu, Jiazhen Zhou, Yi Qian, Rose Qingyang Hu

Department of Electrical and Computer Engineering: Faculty Publications

One of the biggest challenges in multi-hop cognitive radio networking is the dynamic change of channel availability to secondary users which could cause the breaking of routes and thus communications. To address this challenge, we propose an adaptive channel allocation and routing scheme in this paper. Our scheme is flexible so that it can react to the dynamic change of channel availability, and it can maximize the throughput by exploiting network coding opportunities. First, we model the primary users’ activity, channel availability and the interference among the secondary users in a cognitive radio network environment, and show how to implement …

Distributed Beamforming With Imperfect Phase Synchronization For Cognitive Radio Networks, Andrew Minturn, Deepraj Vernekar, Yaoqing Lamar Yang, Hamid Sharif

Department of Electrical and Computer Engineering: Faculty Publications

In this paper, we present the analysis and simulation evaluation of a cognitive radio network employing a distributed beamforming technique with imperfect phase synchronization in the presence of a primary receiver. Our system model consists of a group of cognitive transmitters, each with an ideal isotropic antenna and equal transmit power, communicating with a secondary receiver in the farfield. The objective of the network of cognitive transmitters is to optimize its beampattern in the direction of the secondary receiver while minimizing the beampattern in the direction of the primary receiver to a certain threshold. The phases of the transmitted signals …

Geospatial Virtual Heritage: A Gesture-Based 3d Gis To Engage The Public With Ancient Maya Archaeology, Heather Richards-Rissetto, Jim Robertsson, Jennifer Von Schwerin, Giorgio Agugario, Fabio Remondino, Gabrio Girardi

Department of Anthropology: Faculty Publications

This paper presents our research to develop a gesture-based 3D GIS system to engage the public in cultural heritage. It compares two types of interaction—device-based vs. natural interaction— and summarizes the beta-testing results of a 3D GIS tool for archaeology, called QueryArch3D, in which participants used device-based interaction (i.e. mouse and keyboard). It follows with a description of the gesture-based system—that we developed in response to these beta-tests. The system uses QueryArch3D and Microsoft’s Kinect to enable people use body movements (in lieu of keyboard or mouse) to navigate a virtual reality landscape, query 3D objects, and call up photos, …

Substantive Collaboration: Are We Ready To Lead?, Mark Askren

Information Technology Services: Publications

Although MOOCs have received the most attention in higher education this year, another issue is affecting colleges and universities and the IT community on a much broader scale: the perception that the higher education business model is “broken.” This isn’t an IT problem by definition, but IT leaders have not contributed effectively to a solution. At least not yet. So what can we, as IT leaders, do individually and collectively to change the outcome? The answer is clear. We have to collaborate. Substantially. And in ways that are far-reaching and very challenging. We have to change our core processes and …

Human Performance Regression Testing, Amanda Swearngin, Myra B. Cohen, Bonnie E. John, Rachel K. E. Bellamy

School of Computing: Conference and Workshop Papers

As software systems evolve, new interface features such as keyboard shortcuts and toolbars are introduced. While it is common to regression test the new features for functional correctness, there has been less focus on systematic regression testing for usability, due to the effort and time involved in human studies. Cognitive modeling tools such as CogTool provide some help by computing predictions of user performance, but they still require manual effort to describe the user interface and tasks, limiting regression testing efforts. In recent work, we developed CogTool-Helper to reduce the effort required to generate human performance models of existing systems. …

Trading Wind Power In A Competitive Electricity Market Using Stochastic Programing And Game Theory, Ting Dai, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

Wind power is one of the most rapidly growing clean and renewable energy sources. However, due to the uncertainty and intermittency of wind power, the increasing penetration of wind power into the electric power system will pose challenges to power system operators. Moreover, as a participant in a competitive electricity market, a wind power producer’s behavior and profit will be influenced by other participants’ behaviors. This paper proposes a model of using stochastic programming to generate optimal bidding strategies to maximize the total profits of wind and conventional power producers in both the energy market and a bilateral reserve market, …

Application-Aware Routing For Multi-Hop Cognitive Radio Networks With Channel Bonding, Feng Ye, Jiazhen Zhou, Rose Qingyang Hu

Department of Electrical and Computer Engineering: Faculty Publications

Due to the unequal spectrum resources in different areas, multi-hop wireless cognitive radio network (MWCRN) faces the challenge of a relatively poor performance. In this paper, we propose an application-aware routing scheme with channel bonding technique to help improve the efficiency and performance of a MWCRN network. More specifically, we formulate an optimization problem aiming to meet the application request, as well as operating at low transmission cost. To solve this problem, we first study the greatest lower bound of transmission cost named as Utopian cost, as well as an upper bound of transmission cost. Moreover, we propose two distributed …

Imbalance Fault Detection Of Direct-Drive Wind Turbines Using Generator Current Signals, Xiang Gong, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

No abstract provided.