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Articles 1 - 19 of 19
Full-Text Articles in Engineering
Adaptive Control Of An Active Magnetic Bearing With External Disturbance, Lili Dong, Silu You
Adaptive Control Of An Active Magnetic Bearing With External Disturbance, Lili Dong, Silu You
Electrical and Computer Engineering Faculty Publications
Adaptive back stepping control (ABC) is originally applied to a linearized model of an active magnetic bearing (AMB) system. Our control goal is to regulate the deviation of the magnetic bearing from its equilibrium position in the presence of an external disturbance and system uncertainties. Two types of ABC methods are developed on the AMB system. One is based on full state feedback, for which displacement, velocity, and current states are assumed available. The other one is adaptive observer based back stepping controller (AOBC) where only displacement output is measurable. An observer is designed for AOBC to estimate velocity and …
Modified Active Disturbance Rejection Control For Time-Delay Systems, Shen Zhao, Zhiqiang Gao
Modified Active Disturbance Rejection Control For Time-Delay Systems, Shen Zhao, Zhiqiang Gao
Electrical and Computer Engineering Faculty Publications
Industrial processes are typically nonlinear, time-varying and uncertain, to which active disturbance rejection control (ADRC) has been shown to be an effective solution. The control design becomes even more challenging in the presence of time delay. In this paper, a novel modification of ADRC is proposed so that good disturbance rejection is achieved while maintaining system stability. The proposed design is shown to be more effective than the standard ADRC design for time-delay systems and is also a unified solution for stable, critical stable and unstable systems with time delay. Simulation and test results show the effectiveness and practicality of …
On The Centrality Of Disturbance Rejection In Automatic Control, Zhiqiang Gao
On The Centrality Of Disturbance Rejection In Automatic Control, Zhiqiang Gao
Electrical and Computer Engineering Faculty Publications
In this paper, it is shown that the problem of automatic control is, in essence, that of disturbance rejection, with the notion of disturbance generalized to symbolize the uncertainties, both internal and external to the plant. A novel, unifying concept of disturbance rejector is proposed to compliment the traditional notion of controller. The new controller-rejector pair is shown to be a powerful organizing principle in the realm of automatic control, leading to a Copernican moment where the model-centric design philosophy is replaced by the one that is control-centric in the following sense: the controller is designed for a canonical model …
M-Ary Energy Detection Of A Gaussian Fsk Uwb System, Song Cui, Fuqin Xiong
M-Ary Energy Detection Of A Gaussian Fsk Uwb System, Song Cui, Fuqin Xiong
Electrical and Computer Engineering Faculty Publications
The energy detection M-ary Gaussian frequency-shift keying (FSK) system is proposed in this paper. The system performance is analyzed in additive white Gaussian noise channels, multipath channels, and in the presence of synchronization errors. The numerical results show that the M-ary modulation achieves the higher data rate than the binary modulation. However, it also results in performance degradation.
Energy Detection Uwb System Based On Pulse Width Modulation, Song Cui, Fuqin Xiong
Energy Detection Uwb System Based On Pulse Width Modulation, Song Cui, Fuqin Xiong
Electrical and Computer Engineering Faculty Publications
A new energy detection ultra-wideband system based on pulse width modulation is proposed. The bit error rate (BER) performance of this new system is slightly worst than that of a pulse position modulation (PPM) system in additive white Gaussian noise channels. In multipath channels, this system does not suffer from cross-modulation interference as PPM, so it can achieve better BER performance than PPM when cross-modulation interference occurs. In addition, when synchronisation errors occur, this system is more robust than PPM.
Linearized Biogeography-Based Optimization With Re-Initialization And Local Search, Dan Simon, Mahamed G. H. Omran, Maurice Clerc
Linearized Biogeography-Based Optimization With Re-Initialization And Local Search, Dan Simon, Mahamed G. H. Omran, Maurice Clerc
Electrical and Computer Engineering Faculty Publications
Biogeography-based optimization (BBO) is an evolutionary optimization algorithm that uses migration to share information among candidate solutions. One limitation of BBO is that it changes only one independent variable at a time in each candidate solution. In this paper, a linearized version of BBO, called LBBO, is proposed to reduce rotational variance. The proposed method is combined with periodic re-initialization and local search operators to obtain an algorithm for global optimization in a continuous search space. Experiments have been conducted on 45 benchmarks from the 2005 and 2011 Congress on Evolutionary Computation, and LBBO performance is compared with the results …
Mediator-Less Immunodetection With Voltage-Controlled Intrinsic Amplification For Ultrasensitive And Rapid Detection Of Microorganism Pathogens, Jiapeng Wang, Yan Xu, Siu-Tung Yau
Mediator-Less Immunodetection With Voltage-Controlled Intrinsic Amplification For Ultrasensitive And Rapid Detection Of Microorganism Pathogens, Jiapeng Wang, Yan Xu, Siu-Tung Yau
Electrical and Computer Engineering Faculty Publications
A mediator-less immunodetection method for microorganisms is realized by incorporating the newly developed field-effect enzymatic detection (FEED) technique with the conventional electrochemical immunosensing approach. The gating voltage of FEED facilitates the transduction of electrical signal through the bulky immune complex so that the detection does not rely on the use of mediators or other diffusional substances. The voltage-controlled intrinsic amplification provided by the detection system allows detection in low-concentration samples without target pre-enrichment, leading to ultrasensitive and rapid detection. The detection approach is demonstrated with E. coliO157:H7, a model microorganism, in milk with an estimated detection limit of 20 CFU …
Hybrid Biogeography-Based Evolutionary Algorithms, Haiping Ma, Dan Simon, Minrui Fei, Xinzhan Shu, Zixiang Chen
Hybrid Biogeography-Based Evolutionary Algorithms, Haiping Ma, Dan Simon, Minrui Fei, Xinzhan Shu, Zixiang Chen
Electrical and Computer Engineering Faculty Publications
Hybrid evolutionary algorithms (EAs) are effective optimization methods that combine multiple EAs. We propose several hybrid EAs by combining some recently-developed EAs with a biogeography-based hybridization strategy. We test our hybrid EAs on the continuous optimization benchmarks from the 2013 Congress on Evolutionary Computation (CEC) and on some real-world traveling salesman problems. The new hybrid EAs include two approaches to hybridization: (1) iteration-level hybridization, in which various EAs and BBO are executed in sequence; and (2) algorithm-level hybridization, which runs various EAs independently and then exchanges information between them using ideas from biogeography. Our empirical study shows that the new …
Application Aware For Byzantine Fault Tolerance, Hua Chai
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 …
Biogeography-Based Optimization For Combinatorial Problems And Complex Systems, Dawei Du
Biogeography-Based Optimization For Combinatorial Problems And Complex Systems, Dawei Du
ETD Archive
Biogeography-based optimization (BBO) is a heuristic evolutionary algorithm that has shown good performance on many problems. In this dissertation, three problem1s 1 are researched for BBO: convergence speed and optimal solution convergence of BBO,1 1BBO application to combinatorial problems, and BBO application to complex systems. The first problem is to analyze BBO from two perspectives: how the components of BBO affect its convergence speed and the reason that BBO converges to the optimal solution. For the first perspective, which is convergence speed, we analyze the two essential components of BBO -- population construction and information sharing. For the second perspective, …
Oppositional Biogeography-Based Optimization, Mehmet Ergezer
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
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
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
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
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 …
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 …
Program Verification Of Freertos Using Microsoft Dafny, Matthew J. Matias
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 …
Bio-Inspired Optimization Of Ultra-Wideband Patch Antennas Using Graphics Processing Unit Acceleration, Brian Vyhnalek
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 …
Dynamic Modeling And Analysis Of Generalized Power Flow Controller, B. Vyakaranam, F. E. Villaseca
Dynamic Modeling And Analysis Of Generalized Power Flow Controller, B. Vyakaranam, F. E. Villaseca
Electrical and Computer Engineering Faculty Publications
This paper presents a unified solution to compute power quality indices in the generalized unified power flow controller (GUPFC) during steady and transient conditions using a dynamic harmonic domain technique. This technique allows the user to analyze harmonics generated in the GUPFC more precisely than using time domain techniques. The derivation of a model is presented and then simulated in the presence of voltage disturbances to demonstrate its use in power quality assessment. The results of the proposed model are validated against time domain simulations.