Computer Engineering Commons^™

S-Code: Lowest Density Mds Array Codes For Raid-6, Zhijie Huang, Hong Jiang, Ke Zhou, Yuhong Zhao, Chong Wang

School of Computing: Technical Reports

RAID, a storage architecture designed to exploit I/O parallelism and provide data reliability, has been deployed widely in computing systems as a storage building block. In large scale storage systems, in particular, RAID-6 is gradually replacing RAID-5 as the dominant form of disk arrays due to its capability of tolerating concurrent failures of any two disks. MDS (maximum distance separable) array codes are the most popular erasure codes that can be used for implementing RAID-6, since they enable optimal storage efficiency and efficient encoding and decoding algorithms. In this paper, we propose a new class of MDS array codes called …

Invariant Inferring And Monitoring In Robotic Systems, Hengle Jiang

School of Computing: Dissertations, Theses, and Student Research

System monitoring can help to detect abnormalities and avoid failures. Crafting monitors for today’s robotic systems, however, can be very difficult due to the systems’ inherent complexity and its rich operating environment.

In this work we address this challenge through an approach that automatically infers system invariants and synthesizes those invariants into monitors. This approach is inspired by existing software engineering approaches for automated invariant inference, and it is novel in that it derives invariants by observing the messages passed between system nodes and the invariants types are tailored to match the spatial, time, temporal, and architectural attributes of robotic …

Anisotropy Modulations Of Femtosecond Laser Pulse Induced Periodic Surface Structures On Silicon By Adjusting Double Pulse Delay, Weina Han, Lan Jiang, Xiaowei Li, Qingsong Wang, Hao Li, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

We demonstrate that the polarization-dependent anisotropy of the laser-induced periodic surface structure (LIPSS) on silicon can be adjusted by designing a femtosecond laser pulse train (800 nm, 50 fs, 1 kHz). By varying the pulse delay from 100 to 1600 fs within a double pulse train to reduce the deposited pulse energy, which weakens the directional surface plasmon polarition (SPP)-laser energy coupling based on the initial formed ripple structure, the polarization-dependent geometrical morphology of the LIPSS evolves from a nearly isotropic circular shape to a somewhat elongated elliptical shape. Meanwhile, the controllable anisotropy of the two-dimensional scanned-line widths with different …

Power Management In The Cluster System, Leping Wang

School of Computing: Dissertations, Theses, and Student Research

With growing cost of electricity, the power management of server clusters has become an important problem. However, most previous researchers have only addressed the challenge in traditional homogeneous environments. Considering the increasing popularity of heterogeneous and virtualized systems, this thesis develops a series of efficient algorithms respectively for power management of heterogeneous soft real-time clusters and a virtualized cluster system. It is built on simple but effective mathematical models. When deployed to a new platform, the software incurs low configuration cost because no extensive performance measurements and profiling are required. Built upon optimization, queuing theory and control theory techniques, our …

Processing Of Monolayer Materals Vlanterfacial Reactions, Peter Werner Sutter, Eli Anguelova Sutter

Department of Electrical and Computer Engineering: Faculty Publications

A method of forming and processing of graphene is disclosed based on exposure and selective intercalation of the partially graphene-covered metal Substrate with atomic or molecular intercalation species such as oxygen (O) and nitrogen oxide (NO). The process of intercalation lifts the strong metal carbon coupling and restores the characteristic Dirac behav ior of isolated monolayer graphene. The interface of graphene with metals or metal-decorated substrates also provides for controlled chemical reactions based on novel functionality of the confined space between a metal Surface and a graphene sheet.

Volunteered Geographical Information: An Alternative Solution For Overcoming The Chasm Between Stormwater Management And Community Participation, Yanfu Zhou

Community and Regional Planning Program: Theses

It is a dramatic challenge to promote public engagement in stormwater management and green infrastructure initiatives. When traditional outreach approaches made important influence on public engagement, their limitations are also obvious. With the development of Web 2.0 technology, Volunteered Geographic Information (VGI) has been emerging as one of the most important user-generated geographic contents. The crowdsourcing data that generated by volunteers through geo-web, smartphones, and other geo-devices provides invaluable mass data for decision-making. VGI can provide a better understanding of planning issues and other challenges. The research aims to develop a mobile information platform to allow citizens to report the …

Decaf: A New Event Detection Logic For The Purpose Of Fusing Delineated-Continuous Spatial Information, Kerry Q. Hart

School of Computing: Dissertations, Theses, and Student Research

Geospatial information fusion is the process of synthesizing information from complementary data sources located at different points in space and time. Spatial phenomena are often measured at discrete locations by sensor networks, technicians, and volunteers; yet decisions often require information about locations where direct measurements do not exist. Traditional methods assume the spatial phenomena to be either discrete or continuous, an assumption that underlies and informs all subsequent analysis. Yet certain phenomena defy this dichotomy, alternating as they move across spatial and temporal scales. Precipitation, for example, appears continuous at large scales, but it can be temporally decomposed into discrete …

Security Analysis Of Phasor Measurement Units In Smart Grid Communication Infrastructures, Mehrnaz Sharifian

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

Phasor Measurement Units (PMUs), or synchrophasors, are rapidly being deployed in the smart grid with the goal of measuring phasor quantities concurrently from wide area distribution substations. By utilizing GPS receivers, PMUs can take a wide area snapshot of power systems. Thus, the possibility of blackouts in the smart grid, the next generation power grid, will be reduced. As the main enabler of Wide Area Measurement Systems (WAMS), PMUs transmit measured values to Phasor Data Concentrators (PDCs) by the synchrophasor standard IEEE C37.118. IEC 61850 and IEC 62351 are the communication protocols for the substation automation system and the security …

Using A Uav To Effectively Prolong Wireless Sensor Network Lifetime With Wireless Power Transfer, Jinfu Leng

School of Computing: Dissertations, Theses, and Student Research

Wireless sensor networks are widely used for everything from border security to monitoring waterway pollution. Supplying energy for long term deployment is a main challenge in the applications of wireless sensor networks, as batteries are the primary energy source. Current wireless sensor networks deployed for long periods either require additional infrastructure, such as solar panels, or periodic maintenance. Our research lab has proposed a novel solution that uses a micro unmanned aerial vehicle (UAV) to wirelessly charge the sensor nodes and prolong the sensor network lifetime. Recent studies have shown that significant power can be transferred wirelessly over medium distances. …

Dnn: A Distributed Namenode Filesystem For Hadoop, Ziling Huang

School of Computing: Dissertations, Theses, and Student Research

The Hadoop Distributed File System (HDFS) is the distributed storage infrastructure for the Hadoop big-data analytics ecosystem. A single node, called the NameNode of HDFS stores the metadata of the entire file system and coordinates the file content placement and retrieval actions of the data storage subsystems, called DataNodes. However the single NameNode architecture has long been viewed as the Achilles' heel of the Hadoop Distributed file system, as it not only represents a single point of failure, but also limits the scalability of the storage tier in the system stack. Since Hadoop is now being deployed at increasing scale, …

Variable Bounds Analysis Of A Climate Model Using Software Verification Techniques, Peter Revesz, Robert Woodward

School of Computing: Conference and Workshop Papers

Software verification techniques often use some approximation method that identifies the limits of the possible range of values that variables in a computer program can take during execution. Current climate models are complex computer programs that are typically iterated time-step by time-step to predict the next value of the climate-related variables. Because these iterative methods are necessarily computed only for a fixed number of iterations, they are unable to answer many long-range questions that may be posed regarding climate change, for example, whether there are natural fluctuations or whether a tipping point is reached after which there is no return …

Analysis, Optimization, And Implementation Of A Uav-Based Wireless Power Transfer System, Andrew Mittleider

School of Computing: Dissertations, Theses, and Student Research

Wireless power transfer is rapidly advancing in its ability to efficiently transfer power to a variety of devices.

As the efficiency increases, more applications for these systems arise. Since magnetic resonant wireless power transfer can only transfer a small amount of power, most current applications only focus on powering low-powered devices.

Wireless Sensor Networks are composed of many low-powered nodes which currently require human interaction to remain powered. We propose recharging a low-powered Wireless Sensor Network (WSN) with a magnetic resonant wireless power transfer system attached to a quadrotor Unmanned Aerial Vehicle (UAV).

This thesis addresses three main challenges with …

Polarization-Coupled Ferroelectric Unpolarunction Memory And Energy Storage Device, Mathias M. Schubert, Tino Hofmann, Venkata Rao Voora

Department of Electrical and Computer Engineering: Faculty Publications

A memory device is provided. The memory device includes a plurality of memory cells and a controller to write data to and read data from the memory cells. Each memory cell includes a first semiconductor material having a spontaneous polarization, a resistive ferroelectric material having a switchable spontaneous polarization, and a second semiconductor material having a spontaneous polarization, the resistive ferroelectric material being positioned between and in contact with the first and second semiconductor materials. The memory device can be configured to store energy that can be released by applying a voltage pulse to the memory device.

A New Spatio-Temporal Data Mining Method And Its Application To Reservoir System Operation, Abhinaya Mohan

School of Computing: Dissertations, Theses, and Student Research

This thesis develops a spatio-temporal data mining method for uncertain water reservoir data. The goal of the data mining method is to learn from a history human reservoir operations in order to derive an automated controller for a reservoir system. Spatio-temporal data mining is a challenging task due to the reasons: (1) spatio-temporal datasets are usually much larger than spatial data sets, (2) many common spatial techniques are unable to deal with objects that change location, size or shape, and (3) complex and often non-linear spatio-temporal relationships cannot be separated into pure spatial and pure temporal relationships.

Support Vector Machines …

Autonomous Aerial Water Sampling, John-Paul W. Ore

School of Computing: Dissertations, Theses, and Student Research

Obtaining spatially separated, high frequency water samples from rivers and lakes is critical to enhance our understanding and effective management of fresh water resources. In this thesis we present an aerial water sampler and verify the system in field experiments. The aerial water sampler has the potential to vastly increase the speed and range at which scientists obtain water samples while reducing cost and effort. The water sampling system includes: 1) a mechanism to capture three 20 ml samples per mission; 2) sensors and algorithms for safe navigation and altitude approximation over water; and 3) software components that integrate and …

Flame-Enhanced Laser-Induced Breakdown Spectroscopy, L. Liu, S. Li, X. N. He, X. Huang, C. F. Zhang, L. S. Fan, M. X. Wang, Y. S. Zhou, K. Chen, L. Jiang, J. F. Silvain, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

Flame-enhanced laser-induced breakdown spectroscopy (LIBS) was investigated to improve the sensitivity of LIBS. It was realized by generating laser-induced plasmas in the blue outer envelope of a neutral oxy-acetylene flame. Fast imaging and temporally resolved spectroscopy of the plasmas were carried out. Enhanced intensity of up to 4 times and narrowed full width at half maximum (FWHM) down to 60% for emission lines were observed. Electron temperatures and densities were calculated to investigate the flame effects on plasma evolution. These calculated electron temperatures and densities showed that high-temperature and low-density plasmas were achieved before 4 μs in the flame environment, …

Relationship Between Photofixed Condensate, Effluent And Bulk Composition Of Several Common Rtv Materials, Fen Zhou Hanrahan, Natale J. Ianno

Department of Electrical and Computer Engineering: Faculty Publications

Raman spectroscopy and Fourier Transform Infrared (FTIR) spectroscopy are employed to analyze the bulk compositions of five kinds of Room Temperature Vulcanized (RTV) silicones (CV2568, RTV566, DC93-500, SCV2590 and SCV2590-2) that are commonly employed in orbiting spacecraft. It is found that polydimethylsiloxane (PDMS), silicon dioxide, Tetra-n-propylsilicate (NPS), silicic acid, tetraethyl orthosilicate, and trimethylsilanol are contained in all of them. The outgassing products from those silicones are characterized by FTIR. By comparing the position of the peaks, it is found that the outgassing products of each material are PDMS and NPS which are consistent with the compositions of samples determined with …

Towards A Sustainable Modular Robot System For Planetary Exploration, S. G. M. Hossain

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

This thesis investigates multiple perspectives of developing an unmanned robotic system suited for planetary terrains. In this case, the unmanned system consists of unit-modular robots. This type of robot has potential to be developed and maintained as a sustainable multi-robot system while located far from direct human intervention. Some characteristics that make this possible are: the cooperation, communication and connectivity among the robot modules, flexibility of individual robot modules, capability of self-healing in the case of a failed module and the ability to generate multiple gaits by means of reconfiguration. To demonstrate the effects of high flexibility of an individual …

Contrast Enhancement Using Silica Microspheres In Coherent Anti-Stokes Raman Spectroscopic Imaging, X. Huang, X. N. He, W. Xiong, Y. Gao, L. J. Jiang, Li Liu, Y. S. Zhou, L. Jiang, J. F. Silvain, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

Coherent anti-Stokes Raman scattering (CARS) microscopy is a powerful imaging technique that can provide chemical information of organic and nonorganic materials through vibrational spectroscopy. However, its contrast is not sufficient for monitoring thin film materials. In this study, silica microspheres were employed for enhancing the signal contrast in CARS imaging. One layer of optically transparent silica microspheres was self-assembled onto polymer grating samples to enhance the CARS signals. The highest contrast enhancement factor of 12.5 was achieved using 6.1-μm-diameter microspheres. Finite-difference timedomain method (FDTD) simulation was conducted to simulate the contrast enhancement with silica microspheres of different diameters.

Providing Flexible File-Level Data Filtering For Big Data Analytics, Lei Xu, Ziling Huang, Hong Jiang, Lei Tian, David Swanson

School of Computing: Technical Reports

The enormous amount of big data datasets impose the needs for effective data filtering technique to accelerate the analytics process. We propose a Versatile Searchable File System, VSFS, which provides a transparent, flexible and near real-time file-level data filtering service by searching files directly through the file system. Therefore, big data analytics applications can transparently utilize this filtering service without application modifications. A versatile index scheme is designed to adapt to the exploratory and ad-hoc nature of the big data analytics activities. Moreover, VSFS uses a RAM-based distributed architecture to perform file indexing. The evaluations driven by three real-world analytics …

Introduction To Special Issue Of Journal Of Defense Modeling And Simulation: Novel Approaches To Defense And Military Modeling And Simulation, Scott D. Snyder, James M. Taylor Jr.

Peter Kiewit Institute: Faculty Publications

Developing solutions to complex problems in government and industry is a daunting task that often requires tremendous investment in time and resources to solve. Modeling and simulation (M&S) has incredible potential to streamline development and cut costs by conducting virtual experiments that give insight into performance under various test conditions. As many program managers in the federal acquisition process can attest, realistic testing of live equipment in an operational environment can be some of the most expensive parts of a development program. M&S can provide insight into mission success of yetto- bedesigned systems without the need to actually build and …

Simple Multi-Attribute Rating Technique For Renewable Energy Deployment Decisions (Smart Redd), James M. Taylor Jr., Betty Love

Peter Kiewit Institute: Faculty Publications

In the effort to provide electrical power service and the sustaining fuel required to run generators at forward-deployed bases in Afghanistan and Iraq over more than 10 years, the United States military spent billions of dollars and a paid a heavy toll in terms of human casualties. The green energy linear program for optimizing deployments (GELPOD) proof-of-concept model showed that a linear program could be used to optimize combat deployment of energy generation systems to minimize cost and casualties. Results indicated that reduction in both cost and casualties for renewable energy sources was highly dependent on fuel cost and deployment …

Fiber-Optic Temperature Sensor Using A Fabry–Pérot Cavity Filled With Gas Of Variable Pressure, Yujie Lu, Ming Han, Jiajun Tian

Department of Electrical and Computer Engineering: Faculty Publications

We report a high-temperature fiber-optic sensor based on measuring the spectral fringes of a Fabry–Pérot (FP) cavity on a microstructure fiber (MF) when the gas pressure in the cavity is varied through the holes in the MF. Theoretical analysis shows that the absolute temperature can be deduced from the slope of the spectral shift versus pressure curve, which requires no calibration and is insensitive to the FP cavity length variations. For demonstration, we fabricated a miniature sensor whose FP cavity is formed by sandwiching a fuse-silica tube between a side-hole MF and a solid-core fiber. Using the holes in the …

An Interconnection And Damping Assignment Passivity-Based Controller For A Dc–Dc Boost Converter With A Constant Power Load, Jianwu Zeng, Zhe Zhang, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

This paper proposes an adaptive interconnection and damping assignment (IDA) passivity-based controller (PBC) with a complementary proportional integral (PI) controller for dc–dc boost converters with constant power loads (CPLs). The plant is modeled as a port-controlled Hamiltonian system (PCHS). A virtual circuit that interprets the parameters of the PCHS is then derived to determine the parameters of the IDA-PBC for the system to work in the underdamping, critical-damping, and overdamping modes. Moreover, a complementary PI controller is designed to eliminate the steady-state output voltage error of the IDA-PBC caused by the load variation. Simulation studies are carried out inMATLAB/Simulink to …

An Effective Heat Propagation Path-Based Online Adaptive Thermal Model For Igbt Modules, Ze Wang, Wei Qiao, Bo Tian, Liyan Qu

Department of Electrical and Computer Engineering: Faculty Publications

The information of junction temperature is crucial for operation management of IGBT modules. In practice, junction temperature is typically estimated by using an electrothermal model. IGBT modules are subject to various aging processes during operation, some of which, e.g. substrate solder crack, changes the thermal impedance of an IGBT module. However, in the literature little work has included the aging effects into online thermal behavior modeling of IGBT modules. This paper proposes an Effective Heat Propagation Path (EHPP)-based online adaptive thermal model for IGBT modules, where the EHPP is proposed to quantify the impact of substrate solder cracks on the …

An Isolated Multiport Dc–Dc Converter For Simultaneous Power Management Of Multiple Different Renewable Energy Sources, Jianwu Zeng, Wei Qiao, Liyan Qu, Yanping Jiao

Department of Electrical and Computer Engineering: Faculty Publications

This paper proposes a new isolated multiport dc–dc converter for simultaneous power management of multiple renewable energy sources, which can be of different types and capacities. The proposed dc–dc converter only uses one controllable switch in each port to which a source is connected. Therefore, it has the advantages of simple topology and minimum number of power switches. A general topology of the proposed converter is first introduced. Its principle and operation are then analyzed. The proposed converter is applied for simultaneous maximum power point tracking (MPPT) control of a wind/solar hybrid generation system consisting of one wind turbine generator …

Evaluation Of Ann Estimation-Based Mppt Control For A Dfig Wind Turbine, Chun Wei, Liyan Qu, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

This paper proposes an artificial neuronal network (ANN) estimation-based wind speed sensolress MPPT algorithm for wind turbines equipped with doubly-fed induction generators (DFIG). The ANN is designed to produce the optimal control signal for the DFIG power or speed controller. The optimal parameters of the ANN are determined by using a particle swarm optimization (PSO) algorithm. A 3.6 MW DFIG wind turbine is simulated in PSCAD to evaluate and compare the proposed MPPT method with the traditional tip speed ratio (TSR) and turbine power profile-based MPPT methods in both the speed control and power control modes in variable wind speed …

A Flux Vector-Based Discrete-Time Direct Torque Control For Salient-Pole Permanent-Magnet Synchronous Generators, Zhe Zhang, Yue Zhao, Jianwu Zeng, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

This paper proposes a flux vector-based discretetime direct torque control (DTC) scheme for salient-pole permanent-magnet synchronous generators (PMSGs) used in the variable-speed, direct-drive wind energy conversion systems (WECSs). The discrete-time control law is derived from the perspective of flux space vectors and load angle with the torque and stator flux information only. The saliency of the PMSG is eliminated by the active flux concept. Compared with the existing space vector modulation (SVM)-based DTCs, the proposed scheme removes the use of PI regulators and is less dependent on the machine parameters, e.g., stator inductances and permanent-magnet flux linkage, while maintaining the …

Improved Rotor Position And Speed Estimators For Sensorless Control Of Interior Permanent-Magnet Synchronous Machines, Yue Zhao, Wei Qiao, Long Wu

Department of Electrical and Computer Engineering: Faculty Publications

Model-based rotor position/speed estimators are commonly used for sensorless control of interior permanentmagnet synchronous machines (IPMSMs) operating in the medium- and high-speed regions. A rotor position/speed estimation scheme usually contains three major parts: 1) a state observer; 2) a position estimator; and 3) a speed estimator. This paper proposes a sliding-mode observer (SMO) as the state observer to estimate the position-related system states, which are the extended electromotive force components in this paper. Then, two major contributions are made to achieve improved position and speed estimation. First, the rotor speed is estimated independently using a model reference adaptive system (MRAS)-based …

Thyristor-Controlled Switch Capacitor Placement In Large-Scale Power Systems Via Mixed Integer Linear Programming And Taylor Series Expansion, Omid Ziaee, F. Fred Choobineh

Department of Electrical and Computer Engineering: Faculty Publications

Allocation of flexible alternating current transmission system (FACTS) devices to an electric power transmission network may be formulated as a nonlinear mathematical program. Solving such a nonlinear program for a large transmission network is computationally very expensive, and obtaining the optimal solution may be impossible. We present a Taylor series expansion approximation of the nonlinearities of the problem and propose a mixed integer linear program (MILP) for finding the optimum location and proper settings of a Thyristor-Controlled Series Capacitor (TCSC) in an electric power network. The objective of this problem is to minimize total generation cost based on the DC …