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Articles 1 - 25 of 25
Full-Text Articles in Engineering
Adaptive Multicast On Mobile Ad Hoc Networks Using Tree-Based Meshes With Variable Density Of Redundant Paths, Sangman Moh, Sang Jun Lee, Chansu Yu
Adaptive Multicast On Mobile Ad Hoc Networks Using Tree-Based Meshes With Variable Density Of Redundant Paths, Sangman Moh, Sang Jun Lee, Chansu Yu
Electrical and Computer Engineering Faculty Publications
Multicasting has been extensively studied for mobile ad hoc networks (MANETs) because it is fundamental to many ad hoc network applications requiring close collaboration of multiple nodes in a group. A general approach is to construct an overlay structure such as multicast tree or mesh and to deliver a multicast packet to multiple receivers over the overlay structure. However, it either incurs a lot of overhead (multicast mesh) or performs poorly in terms of delivery ratio (multicast tree). This paper proposes an adaptive multicast scheme, called tree-based mesh with k-hop redundant paths (TBM k ), …
Active Disturbance Rejection Control For Mems Gyroscopes, Qing Zheng, Lili Dong, Dae Hui Lee, Zhiqiang Gao
Active Disturbance Rejection Control For Mems Gyroscopes, Qing Zheng, Lili Dong, Dae Hui Lee, Zhiqiang Gao
Electrical and Computer Engineering Faculty Publications
A new control method is presented to drive the drive axis of a Micro-Electro-Mechanical Systems (MEMS) gyroscope to resonance and to regulate the output amplitude of the axis to a fixed level. It is based on a unique active disturbance rejection control (ADRC) strategy, which actively estimates and compensates for internal dynamic changes of the drive axis and external disturbances in real time. The stability analysis shows that both the estimation error and the tracking error of the drive axis output are bounded and that the upper bounds of the errors monotonously decrease with the increase of the controller bandwidth. …
Glenn Research Center Quantum Communicator Receiver Design And Development, Murad Hizlan, John D. Lekki, Binh V. Nguyen
Glenn Research Center Quantum Communicator Receiver Design And Development, Murad Hizlan, John D. Lekki, Binh V. Nguyen
Electrical and Computer Engineering Faculty Publications
We investigate, design, and develop a prototype real-time synchronous receiver for the second-generation quantum communicator recently developed at the National Aeronautics and Space Administration (NASA) Glenn Research Center. This communication system exploits the temporal coincidences between simultaneously fired low-power laser sources to communicate at power levels several orders of magnitude less than what is currently achievable through classical means, with the ultimate goal of creating ultra-low-power microsize optical communications and sensing devices. The proposed receiver uses a unique adaptation of the early-late gate method for symbol synchronization and a newly identified 31-bit synchronization word for frame synchronization. This receiver, implemented …
A Practical Approach To Disturbance Decoupling Control, Qing Zheng, Zhongzhou Chen, Zhiqiang Gao
A Practical Approach To Disturbance Decoupling Control, Qing Zheng, Zhongzhou Chen, Zhiqiang Gao
Electrical and Computer Engineering Faculty Publications
In this paper, a unique dynamic disturbance decoupling control (DDC) strategy, based on the active disturbance rejection control (ADRC) framework, is proposed for square multivariable systems. With the proposed method, it is shown that a largely unknown square multivariable system is readily decoupled by actively estimating and rejecting the effects of both the internal plant dynamics and external disturbances. By requiring as little information on plant model as possible, the intention is to make the new method practical. The stability analysis shows that both the estimation error and the closed-loop tracking error are bounded and the error upper bounds …
Randomcast: An Energy-Efficient Communication Scheme For Mobile Ad Hoc Networks, Sunho Lim, Chansu Yu, Chita R. Das
Randomcast: An Energy-Efficient Communication Scheme For Mobile Ad Hoc Networks, Sunho Lim, Chansu Yu, Chita R. Das
Electrical and Computer Engineering Faculty Publications
In mobile ad hoc networks (MANETs), every node overhears every data transmission occurring in its vicinity and thus, consumes energy unnecessarily. However, since some MANET routing protocols such as dynamic source routing (DSR) collect route information via overhearing, they would suffer if they are used in combination with 802.11 PSM. Allowing no overhearing may critically deteriorate the performance of the underlying routing protocol, while unconditional overhearing may offset the advantage of using PSM. This paper proposes a new communication mechanism, called RandomCast, via which a sender can specify the desired level of overhearing, making a prudent balance between energy and …
A New Control Method For Input-Output Harmonic Elimination Of The Pwm Boost-Type Rectifier Under Extreme Unbalanced Operating Conditions, Ana Vladan Stankovic, Ke Chen
A New Control Method For Input-Output Harmonic Elimination Of The Pwm Boost-Type Rectifier Under Extreme Unbalanced Operating Conditions, Ana Vladan Stankovic, Ke Chen
Electrical and Computer Engineering Faculty Publications
Under severe fault conditions in the distribution system, not only input voltages but also input impedances must be considered as unbalanced. This paper presents a new control method for input-output harmonic elimination of the pulsewidth-modulation (PWM) boost-type rectifier under conditions of both unbalanced input voltages and unbalanced input impedances. The range of imbalance in both input voltages and input impedances, for which the proposed method is valid, is analyzed in detail. An analytical approach for complete harmonic elimination shows that PWM boost-type rectifier can operate at unity power factor under extremely unbalanced operating conditions resulting in a smooth (constant) power …
A Hybrid Biofuel Cell Based On Electrooxidation Of Glucose Using Ultra-Small Silicon Nanoparticles, Yongki Choi, Gang Wang, Munir H. Nayfeh, Siu-Tung Yau
A Hybrid Biofuel Cell Based On Electrooxidation Of Glucose Using Ultra-Small Silicon Nanoparticles, Yongki Choi, Gang Wang, Munir H. Nayfeh, Siu-Tung Yau
Electrical and Computer Engineering Faculty Publications
The ultra-small silicon nanoparticle was shown to be an electrocatalyst for the electrooxidation of glucose. The oxidation appeared to be a first order reaction which involves the transfer of 1 electron. The oxidation potential showed a low onset of −0.4V vs. Ag/AgCl (−0.62V vs. RHE). The particle was used as the anode catalyst of a prototype hybrid biofuel cell, which operated on glucose and hydrogen peroxide. The output power of the hybrid cell showed a dependence on the enzymes used as the cathode catalyst. The power density was optimized to 3.7μW/cm2 when horseradish peroxidase was …
Design And Implementation Of A Byzantine Fault Tolerance Framework For Web Services, Wenbing Zhao
Design And Implementation Of A Byzantine Fault Tolerance Framework For Web Services, Wenbing Zhao
Electrical and Computer Engineering Faculty Publications
Many Web services are expected to run with high degree of security and dependability. To achieve this goal, it is essential to use a Web services compatible framework that tolerates not only crash faults, but Byzantine faults as well, due to the untrusted communication environment in which the Web services operate. In this paper, we describe the design and implementation of such a framework, called BFT-WS. BFT-WS is designed to operate on top of the standard SOAP messaging framework for maximum interoperability. It is implemented as a pluggable module within the Axis2 architecture, as such, it requires minimum changes …
Proactive Service Migration For Long-Running Byzantine Fault-Tolerant Systems, Wenbing Zhao, H. Zhang
Proactive Service Migration For Long-Running Byzantine Fault-Tolerant Systems, Wenbing Zhao, H. Zhang
Electrical and Computer Engineering Faculty Publications
A proactive recovery scheme based on service migration for long-running Byzantine fault-tolerant systems is described. Proactive recovery is an essential method for ensuring the long-term reliability of fault-tolerant systems that are under continuous threats from malicious adversaries. The primary benefit of our proactive recovery scheme is a reduced vulnerability window under normal operation. This is achieved in two ways. First, the time-consuming reboot step is removed from the critical path of proactive recovery. Second, the response time and the service migration latency are continuously profiled and an optimal service migration interval is dynamically determined during runtime based on the observed …
Drive-Mode Control For Vibrational Mems Gyroscopes, Lili Dong, David Avanesian
Drive-Mode Control For Vibrational Mems Gyroscopes, Lili Dong, David Avanesian
Electrical and Computer Engineering Faculty Publications
This paper presents a novel design methodology and hardware implementation for the drive-mode control of vibrational micro-electro-mechanical systems gyroscopes. Assuming that the sense mode (axis) of the gyroscope is operating under open loop, the drive-mode controller compensates an undesirable mechanical spring-coupling term between the two vibrating modes, attenuates the effect of mechanical-thermal noise, and most importantly, forces the output of the drive mode to oscillate along a desired trajectory. The stability and robustness of the control system are successfully justified through frequency-domain analysis. The tracking error between the real output and the reference signal for the drive mode is proved …
A Novel Discrete Dimming Ballast For Linear Fluorescent Lamps, Haiyan Wang, Ana Vladan Stankovic, Louis Nerone, David Kachmarik
A Novel Discrete Dimming Ballast For Linear Fluorescent Lamps, Haiyan Wang, Ana Vladan Stankovic, Louis Nerone, David Kachmarik
Electrical and Computer Engineering Faculty Publications
A novel discrete dimming ballast for linear fluorescent lamps is proposed in this paper. A proposed dimming control circuit is combined with a ballast module for multiple lamps to realize control of three discrete lighting levels. Compared with conventional step dimming or ON-OFF control methods, the proposed discrete dimming method has the following advantages: 1) digital signal is generated by the dimming control circuit to control the lamps' turn- ON and -OFF, which makes the system more reliable and integrated; 2) the proposed discrete dimming system replaces relays, which are necessary in conventional lamp ON-OFF control, and therefore decreases the …
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 …
Minimizing Spatial And Time Reservation With Collision-Aware Dcf In Mobile Ad Hoc Networks, Lubo Song, Chansu Yu
Minimizing Spatial And Time Reservation With Collision-Aware Dcf In Mobile Ad Hoc Networks, Lubo Song, Chansu Yu
Electrical and Computer Engineering Faculty Publications
Carrier sensing is widely adopted in wireless communication to protect data transfers from collisions. For example, distributed coordination function (DCF) in IEEE 802.11 standard renders a node to defer its communication if it senses the medium busy. For the duration of deferment, each frame carries, in its MAC header, a 16-bit number in microseconds during which any overhearing node must defer. However, even if the carrier signal is detected, both ongoing and a new communication can be simultaneously successful depending on their relative positions in the network or equivalently, their mutual interference level. Supporting multiple concurrent communications is …