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Articles 1 - 13 of 13
Full-Text Articles in Engineering
Uncertainty Management Of Intelligent Feature Selection In Wireless Sensor Networks, Sanchita Mal-Sarkar
Uncertainty Management Of Intelligent Feature Selection In Wireless Sensor Networks, Sanchita Mal-Sarkar
ETD Archive
Wireless sensor networks (WSN) are envisioned to revolutionize the paradigm of monitoring complex real-world systems at a very high resolution. However, the deployment of a large number of unattended sensor nodes in hostile environments, frequent changes of environment dynamics, and severe resource constraints pose uncertainties and limit the potential use of WSN in complex real-world applications. Although uncertainty management in Artificial Intelligence (AI) is well developed and well investigated, its implications in wireless sensor environments are inadequately addressed. This dissertation addresses uncertainty management issues of spatio-temporal patterns generated from sensor data. It provides a framework for characterizing spatio-temporal pattern in …
On Active Disturbance Rejection Control;Stability Analysis And Applications In Disturbance Decoupling Control, Qing Zheng
ETD Archive
One main contribution of this dissertation is to analyze the stability characteristics of extended state observer (ESO) and active disturbance rejection control (ADRC). In particular, asymptotic stability of the dynamic system that describes the estimation error and the closed-loop system is established where the plant dynamics is completely known. In the face of large dynamic uncertainties, the estimation error, the closed-loop tracking error, and its up to the (n-1)st order derivatives are shown to be bounded. Furthermore, it is demonstrated that the error upper bounds, in general, monotonously decrease with the observer and control loop bandwidths. The second contribution is …
Robotics Control Using Active Disturbance Rejection Control, Ousama Said Khairallah
Robotics Control Using Active Disturbance Rejection Control, Ousama Said Khairallah
ETD Archive
Conventional robotics control has been set in stone since the sixties. The world has been waiting too long for a new age of control to change the world of Robotics. Active Disturbance Rejection Control (ADRC) is a newly reformed Control methodology. It has been used, in very limited applications, as a replacement for PID control. In this thesis, I will cover the different aspects of the kinematics and dynamics of a robotic manipulator. I will also examine the feasibility of using ADRC to control a robotic manipulator. To explain ADRC, a simple example that demonstrates the concepts and theory of …
Modeling And Feedback Control Of A Mems Electrostatic Actuator, Jason Edwards
Modeling And Feedback Control Of A Mems Electrostatic Actuator, Jason Edwards
ETD Archive
This thesis describes the mathematical modeling and closed-loop voltage control of a MEMS electrostatic actuator. The control goal is to extend the travel range of the actuator beyond the open-loop pull-in limit of one third of the initial gap. Three controller designs are presented to reach the control goal. The first controller design utilizes a regular fourth order Active Disturbance Rejection Controller (ADRC) and is able to achieve 97 of the maximum travel range. The second design also uses a fourth order ADRC, while additional modeling information is included in an Extended State Observer (ESO), which is part of the …
Load Frequency Control Of Multiple-Area Power Systems, Yao Zhang
Load Frequency Control Of Multiple-Area Power Systems, Yao Zhang
ETD Archive
In an interconnected power system, as a power load demand varies randomly, both area frequency and tie-line power interchange also vary. The objectives of load frequency control (LFC) are to minimize the transient deviations in theses variables (area frequency and tie-line power interchange) and to ensure their steady state errors to be zeros. When dealing with the LFC problem of power systems, unexpected external disturbances, parameter uncertainties and the model uncertainties of the power system pose big challenges for controller design. Active disturbance rejection control (ADRC), as an increasingly popular practical control technique, has the advantages of requiring little information …
A Frequency Response Based Approach To Dc-Dc Control Loop Design, Jack Andrew Redilla
A Frequency Response Based Approach To Dc-Dc Control Loop Design, Jack Andrew Redilla
ETD Archive
This thesis encompasses control theory, mathematical models and practical methods for developing high performance control loops for compact DC-DC power converters. In this research we compare an existing hardware control loop design developed through traditional empirical tuning methods to a control loop established by a proposed systematic design approach. To address the many problems of ad-hoc controller design for DC-DC converters, we develop a procedure utilizing tools from frequency domain analysis and loop shaping techniques. This design approach is used to ensure control loop stability and to verify improved loop performance. This systematic control loop design procedure can be utilized …
Investigation Of Generalized Dsss Under Multiple Access And Multipath, Indrasena Varakantham
Investigation Of Generalized Dsss Under Multiple Access And Multipath, Indrasena Varakantham
ETD Archive
In this thesis we investigate and compare the average performances of ordinary and generalized direct sequence spread spectrum (DSSS) systems under multi-path fading and multiple-access interference. As part of multiple access performance, we also consider generation of orthogonal and semi-orthogonal codes using various algorithms, and compare cross correlation properties of codes formed by 2-level and 3-level signature sequences. In order to simulate ordinary and generalized DSSS performance under various scenarios, we develop a complete Java library with classes that are well encapsulated with regard to communication modules and loosely coupled so that we can reuse them to create any type …
Experimental Study Of Multirate Margin In Software Defined Multirate Radio, Tianning Shen
Experimental Study Of Multirate Margin In Software Defined Multirate Radio, Tianning Shen
ETD Archive
Due to the recent development of spectrally-efficient modulation schemes, IEEE 802.11 Wifi and IEEE 802.16 WiMax radios support wireless communication at multiple bit rates. While high-rate transmission allows delivering more information in less time, the corresponding performance improvement is less than expected due to the PHY- and MAC-layer overheads, imposed by the 802.11/16 standards. This is particularly true in wireless ad hoc networks as there exist rate-distance and rate-hop count tradeoffs. The concept of multi-rate margin is proposed in this thesis, which exploits the difference in communication characteristics at different rates and serves as the fundamental ingredient for an opportunistic …
Multihop Transmission Opportunistic Protocol On Software Radio, Sachin C. Hirve
Multihop Transmission Opportunistic Protocol On Software Radio, Sachin C. Hirve
ETD Archive
The need of high speed communication motivates us to use high bit rate communication to transmit more information in as little time as possible. However, MAC layer protocol overheads dominate the transmission capability particularly at high rates and hinder high speed transmission. Opportunistic transmission has been proposed to help to overcome this disadvantage by transmitting packets back-to-back without inter-packet delays. Though this approach alleviates the problem in single-hop wireless LAN scenario, it doesn't help in multi-hop networks. This thesis presents an approach for multi-hop wireless networks, which is named as Multi-hop Transmission OPportunity (MTOP). It achieves better performance by ensuring …
Performance Engineering Of A Lightweight Fault Tolerance Framework, Hua Chai
Performance Engineering Of A Lightweight Fault Tolerance Framework, Hua Chai
ETD Archive
It is well-known that the Paxos algorithm can be used to build provably correct practical fault tolerant systems. In this thesis, a lightweight consensus framework - Paxos-Based Fault Tolerance (PFT) framework and its practical implementation is presented. It also includes how the system tolerates faults under practical conditions where the replicas might not be strictly homogeneous due to the asynchrony of their deployment environment. A comprehensive performance evaluation study is performed on the PFT framework. The approaches that can optimize the fault tolerance mechanisms under various practical scenarios are also discussed
On Traffic Analysis Attacks To Encrypted Voip Calls, Yuanchao Lu
On Traffic Analysis Attacks To Encrypted Voip Calls, Yuanchao Lu
ETD Archive
The increasing popularity of VoIP telephony has brought a lot of attention and concern over security and privacy issues of VoIP communication. This thesis proposes a new class of traffic analysis attacks to encrypted VoIP calls. The goal of these attacks is to detect speaker or speech of encrypted VoIP calls. The proposed traffic analysis attacks exploit silent suppression, an essential feature of VoIP telephony. These attacks are based on application-level features so that the attacks can detect the same speech or the same speaker of different VoIP calls made with different VoIP codecs. We evaluate the proposed attacks by …
Tracking In Wireless Sensor Network Using Blind Source Separation Algorithms, Anil Babu Vikram
Tracking In Wireless Sensor Network Using Blind Source Separation Algorithms, Anil Babu Vikram
ETD Archive
This thesis describes an approach to track multiple targets using wireless sensor networks. In most of previously proposed approaches, tracking algorithms have access to the signal from individual target for tracking by assuming (a) there is only one target in a field, (b) signals from different targets can be differentiated, or (c) interference caused by signals from other targets is negligible because of attenuation. We propose a general tracking approach based on blind source separation, a statistical signal processing technique widely used to recover individual signals from mixtures of signals. By applying blind source separation algorithms to mixture signals collected …
Biogeography-Based Optimization: Synergies With Evolutionary Strategies, Immigration Refusal, And Kalman Filters, Dawei Du
ETD Archive
Biogeography-based optimization (BBO) is a recently developed heuristic algorithm which has shown impressive performance on many well known benchmarks. The aim of this thesis is to modify BBO in different ways. First, in order to improve BBO, this thesis incorporates distinctive techniques from other successful heuristic algorithms into BBO. The techniques from evolutionary strategy (ES) are used for BBO modification. Second, the traveling salesman problem (TSP) is a widely used benchmark in heuristic algorithms, and it is considered as a standard benchmark in heuristic computations. Therefore the main task in this part of the thesis is to modify BBO to …