Computer Engineering Commons^™

Enhanced Optical Bistability With Film-Coupled Plasmonic Nanocubes, Christos Argyropoulos, Cristian Ciraci, David R. Smith

Department of Electrical and Computer Engineering: Faculty Publications

Colloidally synthesized nanocubes strongly coupled to conducting films hold great promise for enhancing different nonlinear optical processes. They exhibit a robust and sensitive scattering response that can be easily controlled by their geometrical and material parameters. Strong local field enhancement is generated at the gap regions between the nanocubes and the metallic film. We show that strong optical bistability and all-optical switching behavior can be obtained by loading these nanogaps with Kerr nonlinear materials. Relatively low input intensities are required to obtain these nonlinear effects. The proposed design can lead to efficient, low-power, and ultrafast all-optical memories and scattering nanoswitches.

Multiplexed Fiber-Ring Laser Sensors For Ultrasonic Detection, Tongqing Liu, Lingling Hu, Ming Han

Department of Electrical and Computer Engineering: Faculty Publications

We propose and demonstrate a multiplexing method for ultrasonic sensors based on fiber Bragg gratings (FBGs) that are included inside the laser cavity of a fiber-ring laser. The multiplexing is achieved using add-drop filters to route the light signals, according to their wavelengths, into different optical paths, each of which contains a separate span of erbium-doped fiber (EDF) as the gain medium. Because a specific span of EDF only addresses a single wavelength channel, mode completion is avoided and the FBG ultrasonic sensors can be simultaneously demodulated. The proposed method is experimentally demonstrated using a two-channel system with two sensing …

Intensity-Demodulated Fiber-Ring Laser Sensor System For Acoustic Emission Detection, Ming Han, Tongqing Liu, Lingling Hu, Qi Zhang

Department of Electrical and Computer Engineering: Faculty Publications

We theoretically and experimentally demonstrate a fiber-optic ultrasonic sensor system based on a fiber-ring laser whose cavity consisting of a regular fiber Bragg grating (FBG) and a tunable optical band-pass filter (TOBPF). The FBG is the sensing element and the TOBPF is used to set the lasing wavelength at a point on the spectral slope of the FBG. The ultrasonic signal is detected by the variations of the laser output intensity in response to the cold-cavity loss modulations from the ultrasonicallyinduced FBG spectral shift. The system demonstrated here has a simple structure and low cost, making it attractive for acoustic …

A Study On Countermeasures Against Steganography: An Active Warden Approach, Qilin Qi

Department of Computer Electronics and Engineering: Dissertations, Theses, and Student Research

Digital steganography is a method used for hiding information in digital images. It can be used for secure communication. There have been many robust digital steganography methods invented in recent decades. The steganographic message can be inserted in multimedia cover signal such as audio, image and video. However, this technique also may be used by malicious users to transmit dangerous information through the Internet beyond the control of security agencies. How to detect and/or block potentially dangerous information transmission on the Internet through billions of multimedia files while not affecting innocent multimedia communications becomes a challenging problem. Existing steganalysis methods …

Clustering And Classification Of Multi-Domain Proteins, Neethu Shah

Department of Computer Science and Engineering: Dissertations, Theses, and Student Research

Rapid development of next-generation sequencing technology has led to an unprecedented growth in protein sequence data repositories over the last decade. Majority of these proteins lack structural and functional characterization. This necessitates design and development of fast, efficient, and sensitive computational tools and algorithms that can classify these proteins into functionally coherent groups.

Domains are fundamental units of protein structure and function. Multi-domain proteins are extremely complex as opposed to proteins that have single or no domains. They exhibit network-like complex evolutionary events such as domain shuffling, domain loss, and domain gain. These events therefore, cannot be represented in the …

Isolation Of High Quality Graphene From Ru By Solution Phase Intercalation, E. Koren, Eli A. Sutter, S. Bliznakov, F. Ivars-Barcelo, P. Sutter

Department of Electrical and Computer Engineering: Faculty Publications

2013 AIP Publishing LLC

The Mayaarch3d Project: A 3d Webgis For Analyzing Ancient Architecture And Landscapes, Jennifer Von Schwerin, Heather Richards-Rissetto, Fabio Remondino, Giorgio Agugario, Gabrio Girardi

Department of Anthropology: Faculty Publications

There is a need in the humanities for a 3D WebGIS with analytical tools that allow researchers to analyze 3D models linked to spatially referenced data. Geographic Information Systems (GIS) allow for complex spatial analysis of 2.5D data. For example, they offer bird’s eye views of landscapes with extruded building footprints, but one cannot ‘get on the ground’ and interact with true 3D models from a pedestrian perspective. Meanwhile, 3D models and virtual environments visualize data in 3D space, but analytical tools are simple rotation or lighting effects. The MayaArch3D Project is developing a 3D WebGIS—called QueryArch3D—to allow these two …

Adaptive Co-Scheduler For Highly Dynamic Resources, Kartik Vedalaveni

Department of Computer Electronics and Engineering: Dissertations, Theses, and Student Research

There are many kinds of scientific applications that run on high throughput computational (HTC) grids. HTC may utilize clusters opportunistically, only running on a given cluster when it is otherwise idle. These widely dispersed HTC clusters are heterogeneous in terms of capability and availability, but can provide significant computing power in aggregate. The scientific algorithms run on them also vary greatly. Some scientific algorithms might use high rates of disk I/O and some might need large amounts of RAM. Most schedulers only consider cpu availability, but unchecked demand on these associated resources that aren’t managed by resource managers may give …

Online Ecosystems In Software Development, Corey J. Jergensen

Department of Computer Science and Engineering: Dissertations, Theses, and Student Research

Software projects are no longer developed as individual, monolithic projects. In- stead, they exist as part of an ecosystem where related projects are developed together using a common underlying technical infrastructure and common project cultures.

This work explores characteristics of online software communities by comparing and contrasting two software ecosystems that are both related to programming, but provide different functions. The first is Stack Overflow, a programming question and answer forum. The second is Gnome, an open-source, Linux desktop environment. Both are examples of online communities because: (1) the communities are composed of smaller projects or topics, (2) users contributions …

Solving The Search For Source Code, Kathryn T. Stolee

Department of Computer Science and Engineering: Dissertations, Theses, and Student Research

Programmers frequently search for source code to reuse using keyword searches. When effective and efficient, a code search can boost programmer productivity, however, the search effectiveness depends on the programmer's ability to specify a query that captures how the desired code may have been implemented. Further, the results often include many irrelevant matches that must be filtered manually. More semantic search approaches could address these limitations, yet existing approaches either do not scale, are not flexible enough to find approximate matches, or require complex specifications.

We propose a novel approach to semantic search that addresses some of these limitations and …

Decentralized Collision Avoidance, Jayasri K. Janardanan

Department of Computer Science and Engineering: Dissertations, Theses, and Student Research

Autonomous Robots must carry out their tasks as independently as possible and each robot may be assigned different tasks at different locations. As these tasks are being performed, the robots have to navigate correctly such that the assigned tasks are completed efficiently, while also avoiding each other and other obstacles. To accomplish effective navigation, we must ensure that the robots are calibrated to avoid colliding with any kind of object on its path. Each robot has to sense the obstacles on its path and take necessary corrective measure to avoid those obstacles. In a situation with multiple robots, robots may …

User Modeling Via Machine Learning And Rule-Based Reasoning To Understand And Predict Errors In Survey Systems, Leonard Cleve Stuart

Department of Computer Science and Engineering: Dissertations, Theses, and Student Research

User modeling is traditionally applied to systems were users have a large degree of control over their goals, the content they view, and the manner in which they navigate through the system. These systems aim to both recommend useful goals to users and to assist them in achieving perceived goals. Systems such as online or telephone surveys are different in that users have only a singular goal of survey completion, extremely limited control over navigation, and content is restricted to prescribed set of survey tasks; changing the user modeling problem to one in which the best means of assisting users …

Cross-Layer Optimized Wireless Video Surveillance, Yun Ye

Department of Computer Electronics and Engineering: Dissertations, Theses, and Student Research

A wireless video surveillance system contains three major components, the video capture and preprocessing, the video compression and transmission over wireless sensor networks (WSNs), and the video analysis at the receiving end. The coordination of different components is important for improving the end-to-end video quality, especially under the communication resource constraint. Cross-layer control proves to be an efficient measure for optimal system configuration. In this dissertation, we address the problem of implementing cross-layer optimization in the wireless video surveillance system.

The thesis work is based on three research projects. In the first project, a single PTU (pan-tilt-unit) camera is used …

Accuracy Improvement Of Quantitative Analysis By Spatial Confinement In Laser-Induced Breakdown Spectroscopy, L. B. Guo, Z. Q. Hao, M. Shen, W. Xiong, X. N. He, Z. Q. Xie, M. Gao, X. Y. Li, X. Y. Zeng, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

To improve the accuracy of quantitative analysis in laser-induced breakdown spectroscopy, the plasma produced by a Nd:YAG laser from steel targets was confined by a cavity. A number of elements with low concentrations, such as vanadium (V), chromium (Cr), and manganese (Mn), in the steel samples were investigated. After the optimization of the cavity dimension and laser fluence, significant enhancement factors of 4.2, 3.1, and 2.87 in the emission intensity of V, Cr, and Mn lines, respectively, were achieved at a laser fluence of 42.9 J/cm2 using a hemispherical cavity (diameter: 5 mm). More importantly, the correlation coefficient of the …

Continuous Modulations Of Femtosecond Laserinduced Periodic Surface Structures And Scanned Line-Widths On Silicon By Polarization Changes, Weina Han, Lan Jiang, Xiaowei Li, Pengjun Liu, Le Xu, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

Large-area, uniform laser-induced periodic surface structures (LIPSS) are of wide potential industry applications. The continuity and processing precision of LIPSS are mainly determined by the scanning intervals of adjacent scanning lines. Therefore, continuous modulations of LIPSS and scanned line-widths within one laser scanning pass are of great significance. This study proposes that by varying the laser (800 nm, 50 fs, 1 kHz) polarization direction, LIPSS and the scanned line-widths on a silicon (111) surface can be continuously modulated with high precision. It shows that the scanned line-width reaches the maximum when the polarization direction is perpendicular to the scanning direction. …

Improving Virtual Collaboration: Modeling For Recommendation Systems In A Classroom Wiki Environment, Derrick A. Lam

Department of Computer Science and Engineering: Dissertations, Theses, and Student Research

Collaboration is of increased importance in today’s society, with increased emphasis placed on working jointly with others, whether it is in the classroom, in the lab, in the workplace, or virtually across the world. The wiki is one particular virtual collaboration tool that is gaining particular prominence in recent years, enabling people – either in small project groups or as part of the wiki’s entire user base – to socially construct knowledge asynchronously on a wide variety of topics. However, there are few intelligent support tools for wikis available, particularly those providing recommendation-based support to users.

This thesis investigates the …

Vsfs: A Versatile Searchable File System For Hpc Analytics, Lei Xu, Ziling Huang, Hong Jiang, Lei Tian, David Swanson

CSE Technical Reports

Big-data/HPC analytics applications have urgent needs for file-search services to drastically reduce the scale of the input data to accelerate analytics. Unfortunately, the existing solutions either are poorly scalable for large-scale systems, or lack well-integrated interface to allow applications to easily use them. We propose a distributed searchable file system, VSFS, which provide a novel and flexible POSIX-compatible searchable file system namespace that can be seamlessly integrate with any legacy code without modification. Additionally, to provide real-time indexing and searching performance, VSFS uses DRAM-based distributed consistent hashing ring to manages all file-index. The results of our evaluation show that VSFS …

Fastlane: Flow-Based Channel Assignment In Dense Wireless Networks, Dane N. Seaberg

Department of Computer Science and Engineering: Dissertations, Theses, and Student Research

Wireless communication in dense networks is becoming more apparent and presents challenges in achieving reliable and near real-time communication. While some works have begun to address dense wireless networks, few address both reliability and latency. In this work we introduce FastLane, a method of ow-based channel assignment for dense wireless networks, which works to achieve reliable, near real-time communication in a dense environment with single-radio devices. FastLane uses an assignment mechanism that assigns channels at a ow-level granularity, rather than a tree-level or link-level granularity. Our scheme also takes into account channel quality and can adapt as the quality changes …

Design And Implementation Of A Hybrid Technology Networking System, Sushanta Mohan Rakshit

Department of Computer Electronics and Engineering: Dissertations, Theses, and Student Research

The safety of rail transport has always been the top priority for the Federal
Railroad Administration (FRA). Legacy technology, like wayside monitoring, is still
in place and is largely relied upon for detection of faults. Modern technology like
Radio Frequency Identification (RFID) has been introduced recently. However, this
is largely used to detect a particular railcar rather than to monitor it for problems.
Wireless Sensor Network (WSN) technology is being evaluated by the railroads for real-time or near real-time monitoring of the status of railcars for timely response to problems and also for trend analysis.

ZigBee has been the networking …

Formation Of Multiscale Surface Structures On Nickel Via Above Surface Growth And Below Surface Growth Mechanisms Using Femtosecond Laser Pulses, Craig A. Zuhlke, Troy P. Anderson, Dennis R. Alexander

Department of Electrical and Computer Engineering: Faculty Publications

The formation of self-organized micro- and nano-structured surfaces on nickel via both above surface growth (ASG) and below surface growth (BSG) mechanisms using femtosecond laser pulse illumination is reported. Detailed stepped growth experiments demonstrate that conical mound-shaped surface structure development is characterized by a balance of growth mechanisms including scattering from surface structures and geometric effects causing preferential ablation of the valleys, flow of the surface melt, and redeposition of ablated material; all of which are influenced by the laser fluence and the number of laser shots on the sample. BSG-mound formation is dominated by scattering, while ASG-mound formation is …

Analysis Of The Feasibility Of Utilizing Wakeup Radios To Optimize Energy And Latency Performance Of Wireless Sensor Networks, Benjamin D. Parks

Department of Computer Electronics and Engineering: Dissertations, Theses, and Student Research

Wireless sensor networks (WSNs) have the potential to radically improve our lives by pervasive environmental monitoring in many applications. However, there are many applications that would be ideal for WSNs, but where reportable events occur with long (days, weeks) or unpredictable durations between occurrences. These uses are hampered by the high energy and latency costs of always-on and periodic wakeup networks, which waste energy on node synchronization and idle monitoring of the RF channel, and exhibit unacceptably high latency for urgent events, e.g., alarms. This thesis proposes, designs, assembles and tests, in a multi-hop WSN test bed, a wakeup receiver …

Energy-Efficient Failure Recovery In Hadoop Cluster, Weiyue Xu

Department of Computer Science and Engineering: Dissertations, Theses, and Student Research

Based on U.S. Environmental Protection Agency’s estimation, only in U.S., billions of dollars are spent on the electricity cost of data centers each year, and the cost is continually increasing very quickly. Energy efficiency is now used as an important metric for evaluating a computing system. However, saving energy is a big challenge due to many constraints. For example, in one of the most popular distributed processing frameworks, Hadoop, three replicas of each data block are randomly distributed in order to improve performance and fault tolerance, but such a mechanism limits the largest number of machine that can be turned …

Microfluidic Refractive Index Sensor Based On An All-Silica In-Line Fabry–Perot Interferometer Fabricated With Microstructured Fibers, Jiajun Tian, Yujie Lu, Qi Zhang, Ming Han

Department of Electrical and Computer Engineering: Faculty Publications

We report a microfluidic fiber-optic refractive index (RI) sensor based on an in-line Fabry-Perot (FP) interferometer, which is formed by a silica tube sandwiched by two microstructured fibers (MFs). The sensor reported here can be fabricated at low cost, possess a robust structure, and has microfluidic capability. The micro-sized holes in the MFs naturally function as microfluidic channels through which liquid samples can be efficiently and conveniently delivered into and out of the FP cavity by a pressure/vacuum pump system for high-performance RI measurement. Due to the microfluidic capability enabled by the MFs, only sub microliter sample is required. We …

Distributed Fiber-Optic Laser-Ultrasound Generation Based On Ghost-Mode Of Tilted Fiber Bragg Gratings, Jiajun Tian, Qi Zhang, Ming Han

Department of Electrical and Computer Engineering: Faculty Publications

Active ultrasonic testing is widely used for medical diagnosis, material characterization and structural health monitoring. Ultrasonic transducer is a key component in active ultrasonic testing. Due to their many advantages such as small size, light weight, and immunity to electromagnetic interference, fiber-optic ultrasonic transducers are particularly attractive for permanent, embedded applications in active ultrasonic testing for structural health monitoring. However, current fiberoptic transducers only allow effective ultrasound generation at a single location of the fiber end. Here we demonstrate a fiber-optic device that can effectively generate ultrasound at multiple, selected locations along a fiber in a controllable manner based on …

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

Department of Computer Science and Engineering: 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 …

Binocular Video Object Tracking With Fast Disparity Estimation, Yun Ye, Song Ci, Yanwei Liu, Haohong Wang, Aggelos K. Katsaggelos

Department of Electrical and Computer Engineering: Faculty Publications

This paper presents a binocular PTU (pan-tilt unit) camera video object tracking scheme using the MeanShift algorithm and the runtime disparity estimation. The proposed method is to accommodate the requirement of 3D content generation and accurate tracking in more advanced video surveillance applications. The disparity estimation process for each stereoscopic pair is formulated as an energy minimization problem. The iterative solution procedure is implemented in a course-to-fine manner. The estimated disparity is used to scale the tracking window by the MeanShift algorithm, i.e. the size of the tracking area is adjustable according to its inner disparity, and thus the moving …

A Survey On Smart Grid Communication Infrastructures: Motivations, Requirements And Challenges, Ye Yan, Yi Qian, Hamid Sharif, David Tipper

Department of Electrical and Computer Engineering: Faculty Publications

A communication infrastructure is an essential part to the success of the emerging smart grid. A scalable and pervasive communication infrastructure is crucial in both construction and operation of a smart grid. In this paper, we present the background and motivation of communication infrastructures in smart grid systems. We also summarize major requirements that smart grid communications must meet. From the experience of several industrial trials on smart grid with communication infrastructures, we expect that the traditional carbon fuel based power plants can cooperate with emerging distributed renewable energy such as wind, solar, etc, to reduce the carbon fuel consumption …

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 …