Electrical and Computer Engineering Commons^™

Cascaded Plasmon Resonances For Enhanced Nonlinear Optical Response, Seyfollah Toroghi

Electronic Theses and Dissertations

The continued development of integrated photonic devices requires low-power, small volume all-optical modulators. The weak nonlinear optical response of conventional optical materials requires the use of high intensities and large interaction volumes in order to achieve significant light modulation, hindering the miniaturization of all-optical switches and the development of lightweight transmission optics with nonlinear optical response. These challenges may be addressed using plasmonic nanostructures due to their unique ability to confine and enhance electric fields in sub-wavelength volumes. The ultrafast nonlinear response of free electrons in such plasmonic structures and the fast thermal nonlinear optical response of metal nanoparticles, as …

On Kernel-Base Multi-Task Learning, Cong Li

Electronic Theses and Dissertations

Multi-Task Learning (MTL) has been an active research area in machine learning for two decades. By training multiple relevant tasks simultaneously with information shared across tasks, it is possible to improve the generalization performance of each task, compared to training each individual task independently. During the past decade, most MTL research has been based on the Regularization-Loss framework due to its flexibility in specifying various types of information sharing strategies, the opportunity it offers to yield a kernel-based methods and its capability in promoting sparse feature representations. However, certain limitations exist in both theoretical and practical aspects of Regularization-Loss-based MTL. …

Are Students Satisfied With Media: A Canadian Case Study, Gerd Gidion, Luiz Fernando Capretz, Ken Meadow, Michael Grosch

Electrical and Computer Engineering Publications

The article presents partial results of a survey about media usage habits for studying and learning conducted in 2013 at Western University, a large Canadian university. The article focuses on students’ frequency of use and satisfaction with media for studying and learning. The results of this study support the assumption that student’s media usage includes a mixture of traditional and new media. The main traditional media continue to play an important role in the students’ academic life, and some new media have emerged as seemingly on equal footing or even more important than the traditional forms of media. The use …

Simplified Method To Derive The Kalman Filter Covariance Matrices To Predict Wind Speeds From A Nwp Model, Conor Lynch, Michael J. O'Mahony, Ted Scully

NIMBUS Articles

This paper espouses a simplified approach to predict wind speed 1 hour ahead for a wind turbine located on the Cork Institute of Technology (CIT) college campus by utilising a Kalman Filter to predict the bias between a campus based turbine and the output from a Numerical Weather Prediction (NWP) model for Cork Airport.

Furthermore, this paper investigates the optimum number of samples required (n) in a fixed sampling interval process to derive the covariance matrix of the system equation Qt and the covariance matrix of the observation equation Rt . The main contents of this paper include …

Application Aware For Byzantine Fault Tolerance, Hua Chai

ETD Archive

Driven by the need for higher reliability of many distributed systems, various replication-based fault tolerance technologies have been widely studied. A prominent technology is Byzantine fault tolerance (BFT). BFT can help achieve high availability and trustworthiness by ensuring replica consistency despite the presence of hardware failures and malicious faults on a small portion of the replicas. However, most state-of-the-art BFT algorithms are designed for generic stateful applications that require the total ordering of all incoming requests and the sequential execution of such requests. In this dissertation research, we recognize that a straightforward application of existing BFT algorithms is often inappropriate …

Oppositional Biogeography-Based Optimization, Mehmet Ergezer

ETD Archive

This dissertation outlines a novel variation of biogeography-based optimization (BBO), which is an evolutionary algorithm (EA) developed for global optimization. The new algorithm employs opposition-based learning (OBL) alongside BBO migration to create oppositional BBO (OB BO). Additionally, a new opposition method named quasi-reflection is introduced. Quasireflection is based on opposite numbers theory and we mathematically prove that it has the highest expected probability of being closer to the problem solution among all OBL methods that we explore. Performance of quasi-opposition is validated by mathematical analysis for a single-dimensional problem and by simulations for higher dimensions. Experiments are performed on benchmark …

Byzantine Fault Tolerance For Distributed Systems, Honglei Zhang

ETD Archive

The growing reliance on online services imposes a high dependability requirement on the computer systems that provide these services. Byzantine fault tolerance (BFT) is a promising technology to solidify such systems for the much needed high dependability. BFT employs redundant copies of the servers and ensures that a replicated system continues providing correct services despite the attacks on a small portion of the system. In this dissertation research, I developed novel algorithms and mechanisms to control various types of application nondeterminism and to ensure the long-term reliability of BFT systems via a migration-based proactive recovery scheme. I also investigated a …

Biogeography-Based Optimization Of A Variable Camshaft Timing System, George L. Thomas

ETD Archive

Automotive system optimization problems are difficult to solve with traditional optimization techniques because the optimization problems are complex, and the simulations are computationally expensive. These two characteristics motivate the use of evolutionary algorithms and meta-modeling techniques respectively. In this work, we apply biogeography-based optimization (BBO) to radial basis function (RBF)-based lookup table controls of a variable camshaft timing system for fuel economy optimization. Also, we reduce computational search effort by finding an effective parameterization of the problem, optimizing the parameters of the BBO algorithm for the problem, and estimating the cost of a portion of the candidate solutions in BBO …

Laboratory Measurements Of The Deep Venusian Atmosphere, Timothy J. Palinski

ETD Archive

NASA Glenn Research Center has designed and built a test chamber that can recreate the hot, dense atmospheric conditions of the deep Venusian atmosphere, where pressures range as high as 92 atmospheres and temperatures as high as 740 K. The majority of this thesis lies in experimentally measuring and quantifying the infrared absorption of CO2 at Venus-like conditions in this laboratory setting. In particular, we describe the challenges and solutions involved in achieving repeatable laboratory test conditions, as well as the iterative process of modifying/optimizing our experimental test setup, including proposed future improvements. We discuss our measured CO2 absorption spectra, …

Tcp Ftat (Fast Transmit Adaptive Transmission): A New End-To-End Congestion Control Algorithm, Mohammed Ahmed Melegy Mohammed Afifi

ETD Archive

Congestion Control in TCP is the algorithm that controls allocation of network resources for a number of competing users sharing a network. The nature of computer networks, which can be described from the TCP protocol perspective as unknown resources for unknown traffic of users, means that the functionality of the congestion control algorithm in TCP requires explicit feedback from the network on which it operates. Unfortunately this is not the way it works with TCP, as one of the fundamental principles of the TCP protocol is to be end-to-end, in order to be able to operate on any network, which …

Program Verification Of Freertos Using Microsoft Dafny, Matthew J. Matias

ETD Archive

FreeRTOS is a popular real-time and embedded operating system. Real-time software requires code reviews, software tests, and other various quality assurance activities to ensure minimal defects. This free and open-source operating system has claims of robustness and quality [26]. Real-time and embedded software is found commonly in systems directly impacting human life and require a low defect rate. In such critical software, traditional quality assurance may not suce in minimizing software defects. When traditional software quality assurance is not enough for defect removal, software engineering formal methods may help minimize defects. A formal method such as program verication is useful …

Electrostatically Controlled Enzymatic Reaction, Metabolic Processes And Microbial Generation Of Electric Power, Yang Song

ETD Archive

This thesis shows that electric fields can be used to control electron transport in biological systems and improve the performance of biological devices using an external gating voltage. It has recently been shown that an ultrasensitive detection method based on electric field effect can be used to control the kinetics of enzymatic conversion of glucose. The first part of the thesis is a mechanistic study of the enzyme catalyzed conversion of glucose to gluconolactone using the field effect enzymatic detection (FEED) technique. Use of a voltage controlled enzymatic system decreased electrons tunnel between electrode and active center of glucose oxidase …

Bio-Inspired Optimization Of Ultra-Wideband Patch Antennas Using Graphics Processing Unit Acceleration, Brian Vyhnalek

ETD Archive

Ultra-wideband (UWB) wireless systems have recently gained considerable attention as effective communications platforms with the properties of low power and high data rates. Applications of UWB such as wireless USB put size constraints on the antenna, however, which can be very dicult to meet using typical narrow band antenna designs. The aim of this thesis is to show how bio-inspired evolutionary optimization algorithms, in particular genetic algorithm (GA), particle swarm optimization (PSO) and biogeography-based optimization (BBO) can produce novel UWB planar patch antenna designs that meet a size constraint of a 10 mm 10 mm patch. Each potential antenna design …

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 …

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

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

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 …

Design Optimization Of Single-Sided Axial Flux Permanent Magnet Machines By Differential Evolution, Xu Yang, Dean Patterson, Jerry Hudgins

Department of Electrical and Computer Engineering: Faculty Publications

In this paper, a design optimization approach for single-sided axial flux permanent magnet (AFPM) machines using a differential evolution algorithm for is presented. The objectives of the design optimization are to maximize the output torque per unit cost (Nm/$) and maximize the efficiency. A paremetric 2-D FEA model of an AFPM is built. A sensitivity study of design variables is carried out to determine the correlation between the design variables and the objectives, enabling the removal of insignificant design variables. Design constraints including geometrical and operating limits are considered. A total of five independent variables are employed in the optimization …

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

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

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 …