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Electrical and Computer Engineering Faculty Research & Creative Works

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Articles 2221 - 2250 of 3518

Full-Text Articles in Engineering

Mobile Speed Estimation For Broadband Wireless Communications, Y. Rosa Zheng, Chengshan Xiao Jan 2007

Mobile Speed Estimation For Broadband Wireless Communications, Y. Rosa Zheng, Chengshan Xiao

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a new algorithm is proposed to estimate mobile speed for broadband wireless communications, which often encounter large number of fading channel taps causing severe intersymbol interference. Theoretical analysis is first derived and practical algorithm is proposed based on the analytical results. The algorithm employs a modified auto-covariance of received signal power to estimate the speed of mobiles. The algorithm is based on the received signals which contain unknown transmitted data, unknown frequency selective multipaths possibly including line-of-sight (LOS) component, and random receiver noise. The algorithm works well for frequency selective Rayleigh and Rician channels. The algorithm is …

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Neural Network Controller Development And Implementation For Spark Ignition Engines With High Egr Levels, Jonathan B. Vance, Atmika Singh, Brian C. Kaul, Jagannathan Sarangapani, J. A. Drallmeier Jan 2007

Neural Network Controller Development And Implementation For Spark Ignition Engines With High Egr Levels, Jonathan B. Vance, Atmika Singh, Brian C. Kaul, Jagannathan Sarangapani, J. A. Drallmeier

Electrical and Computer Engineering Faculty Research & Creative Works

Past research has shown substantial reductions in the oxides of nitrogen (NOx) concentrations by using 10% -25% exhaust gas recirculation (EGR) in spark ignition (SI) engines (see Dudek and Sain, 1989). However, under high EGR levels, the engine exhibits strong cyclic dispersion in heat release which may lead to instability and unsatisfactory performance preventing commercial engines to operate with high EGR levels. A neural network (NN)-based output feedback controller is developed to reduce cyclic variation in the heat release under high levels of EGR even when the engine dynamics are unknown by using fuel as the control input. A separate …

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Performance Analysis Of Wireless Systems With Doubly Selective Rayleigh Fading, Jingxian Wu, Chengshan Xiao Jan 2007

Performance Analysis Of Wireless Systems With Doubly Selective Rayleigh Fading, Jingxian Wu, Chengshan Xiao

Electrical and Computer Engineering Faculty Research & Creative Works

Theoretical error performances of wireless communication systems suffering from both doubly selective (time varying and frequency selective) Rayleigh fading and sampler timing offset are analyzed in this paper. Single-input-single-output systems with doubly selective fading channels are equivalently represented as discrete-time single-input-multiple-output (SIMO) systems with correlated frequency-flat fading channels, with the correlation information being determined by the combined effects of sampler timing phase, maximum Doppler spread, and power delay profile of the physical fading. Based on the equivalent SIMO system representation, closed-form error-probability expressions are derived as tight lower bounds for linearly modulated systems with fractionally spaced equalizers. The information on …

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Performance Of Doubly Fed-Induction Machine Wind-Generators During Grid And Wind Disturbances, Badrul H. Chowdhury, Murali M. Baggu Jan 2007

Performance Of Doubly Fed-Induction Machine Wind-Generators During Grid And Wind Disturbances, Badrul H. Chowdhury, Murali M. Baggu

Electrical and Computer Engineering Faculty Research & Creative Works

A doubly fed induction generator is under study for application with a wind turbine. The operation of the Doubly Fed Induction Generator (DFIG) under different disturbances namely, response to gradual increase or decrease in wind speeds, sudden change of wind speeds like wind gust and different fault scenarios near and farther to the wind turbine are demonstrated in this paper using the wind model developed by DIgSILENT® in their PowerFactory software.

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Process Development For The Formation Of Post-Bonding Biorecognition Layers In Microfluidic Biosensors, Martin G. Perez, Phaninder R. Kanikella, James N. Reck, Chang-Soo Kim, Matthew O'Keefe Jan 2007

Process Development For The Formation Of Post-Bonding Biorecognition Layers In Microfluidic Biosensors, Martin G. Perez, Phaninder R. Kanikella, James N. Reck, Chang-Soo Kim, Matthew O'Keefe

Electrical and Computer Engineering Faculty Research & Creative Works

Formation of the biorecognition layers within microfluidic sensor channels must be done after the completion of the channel structure since these layers cannot withstand the wafer bonding temperature. We propose a new post-bonding immobilization process to prepare the enzyme layers within microfluidic channels of electrochemical biosensors. An array of Pt vertical electrodes is electroplated using a SU-8 mold. The cured SU-8 is then removed by plasma etching to expose the Pt electrode and to define the fluidic channel cavity simultaneously. An array of enzyme posts is formed on the Pt surface by either electropolymerizing or photopolymerizing enzyme precursor solutions injected …

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Two Neural Network Based Decentralized Controller Designs For Large Scale Power Systems, Wenxin Liu, Jagannathan Sarangapani, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Mariesa Crow, David A. Cartes Jan 2007

Two Neural Network Based Decentralized Controller Designs For Large Scale Power Systems, Wenxin Liu, Jagannathan Sarangapani, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Mariesa Crow, David A. Cartes

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents two neural network (NN) based decentralized controller designs for large scale power systems' generators, one is for the excitation control and the other is for the steam valve control. Though the control signals are calculated using local signals only, the transient and overall system stabilities can be guaranteed. NNs are used to approximate the unknown and/or imprecise dynamics of the local power system and the interconnection terms, thus the requirements for exact system parameters are released. Simulation studies with a three machine power system demonstrate the effectiveness of the proposed controller designs.

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Development And Application Of A High-Resolution Thin-Film Probe, Shaohua Li, Kuifeng Hu, Daryl G. Beetner, James L. Drewniak, James N. Reck, Matthew O'Keefe, Kai Wang, Xiaopeng Dong, Kevin P. Slattery Jan 2007

Development And Application Of A High-Resolution Thin-Film Probe, Shaohua Li, Kuifeng Hu, Daryl G. Beetner, James L. Drewniak, James N. Reck, Matthew O'Keefe, Kai Wang, Xiaopeng Dong, Kevin P. Slattery

Electrical and Computer Engineering Faculty Research & Creative Works

This paper documents the development, characterization, and application of a high-resolution thin-film magnetic-field probe. Probe diameter ranged from 5-μm to 100-μm. The 100-μm probe exhibits a 250-7μm improvement in spatial resolution compared to a conventional loop probe, measured at a height of 250 μm over differential traces with a 118-μm spacing. Electric field rejection was improved using shielding and using a 180-degree hybrid junction to separate common-mode (electric field) and differential-mode (primarily magnetic field) coupling. A network analyzer with narrow band filtering was used to detect the relatively weak signal from the probe and to allow detection of phase information. …

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Mode Suppressed Tem Cell Design For High Frequency Ic Measurements, Shaowei Deng, David Pommerenke, Todd H. Hubing, James L. Drewniak, Daryl G. Beetner, Dongshik Shin, Sungnam Kim, Hocheol Kwak Jan 2007

Mode Suppressed Tem Cell Design For High Frequency Ic Measurements, Shaowei Deng, David Pommerenke, Todd H. Hubing, James L. Drewniak, Daryl G. Beetner, Dongshik Shin, Sungnam Kim, Hocheol Kwak

Electrical and Computer Engineering Faculty Research & Creative Works

TEM cells or GTEM cells can be used to evaluate the radiated emissions of integrated circuits (ICs). The applicable frequency bandwidth of a TEM cell is limited due to the resonances of higher order modes. This paper describes how a TEM cell can be modified to extend the frequency range without changing the test topology. Several methods are proposed and implemented to suppress the higher order modes. The magnetic field coupling and electric field coupling are evaluated for the new design. The frequency bandwidth of the modified TEM cell is extended from original 1 GHz to 2.5 GHz.

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Spatial Diversity In Signal Strength Based Wlan Location Determination Systems, Anil Ramachandran, Jagannathan Sarangapani Jan 2007

Spatial Diversity In Signal Strength Based Wlan Location Determination Systems, Anil Ramachandran, Jagannathan Sarangapani

Electrical and Computer Engineering Faculty Research & Creative Works

Literature indicates that spatial diversity can be utilized to compensate channel uncertainties such as multipath fading. Therefore, in this paper, spatial diversity is exploited for locating stationary and mobile objects in the indoor environment. First, space diversity technique is introduced for small scale motion and temporal variation compensation of received signal strength and it is demonstrated analytically that it enhances location accuracy. Small scale motion refers to movements of the transmitter and/or the receiver of the order of sub-wavelengths while temporal effects refer to environmental variations with time. A novel metric is introduced for selection combining in order to improve …

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Superconducting Magnetic Energy Storage System (Smes) For Improved Dynamic System Performance, Dwaraka S. Padimiti, Badrul H. Chowdhury Jan 2007

Superconducting Magnetic Energy Storage System (Smes) For Improved Dynamic System Performance, Dwaraka S. Padimiti, Badrul H. Chowdhury

Electrical and Computer Engineering Faculty Research & Creative Works

A Superconducting Magnetic Energy Storage System (SMES) consists of a high inductance coil emulating a constant current source. Such a SMES system, when connected to a power system, is able to inject/absorb active and reactive power into or from a system. The active power injected into the system is controlled by varying the duty cycle of the switches in the dc-dc chopper while the SMES coil is discharging into the system. The reactive power is controlled by the magnitude of the converter output voltage. The storage setup is tested on a WSCC 3 machine 9 bus system. The behavior of …

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An Online Approximator-Based Fault Detection Framework For Nonlinear Discrete-Time Systems, Balaje T. Thumati, Jagannathan Sarangapani Jan 2007

An Online Approximator-Based Fault Detection Framework For Nonlinear Discrete-Time Systems, Balaje T. Thumati, Jagannathan Sarangapani

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a fault detection scheme is developed for nonlinear discrete time systems. The changes in the system dynamics due to incipient failures are modeled as a nonlinear function of state and input variables while the time profile of the failures is assumed to be exponentially developing. The fault is detected by monitoring the system and is approximated by using online approximators. A stable adaptation law in discrete-time is developed in order to characterize the faults. The robustness of the diagnosis scheme is shown by extensive mathematical analysis and simulation results.

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Application And Limits Of Ic And Pcb Scanning Methods For Immunity Analysis, Qing Cai, Jin Min, Giorgi Muchaidze, David Pommerenke Jan 2007

Application And Limits Of Ic And Pcb Scanning Methods For Immunity Analysis, Qing Cai, Jin Min, Giorgi Muchaidze, David Pommerenke

Electrical and Computer Engineering Faculty Research & Creative Works

Immunity scanning methods can be used to locate sensitive areas on PCBs and ICs. For the analysis of emissions near field scanning is used to determine the local field strength. Both methods have many similarities and differences. For both methods it is difficult to correlate between board level scanning and system level test results as neither method shows the coupling path directly. The paper shows the implementation of an immunity scanning system and analyzes the advantages and limitations of immunity near field scanning.

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Route Aware Predictive Congestion Control Protocol For Wireless Sensor Networks, Carl Larsen, Maciej Jan Zawodniok, Jagannathan Sarangapani Jan 2007

Route Aware Predictive Congestion Control Protocol For Wireless Sensor Networks, Carl Larsen, Maciej Jan Zawodniok, Jagannathan Sarangapani

Electrical and Computer Engineering Faculty Research & Creative Works

Congestion in wireless sensor networks (WSN) may lead to packet losses or delayed delivery of important information rendering the WSN-based monitoring or control system useless. In this paper a routing-aware predictive congestion control (RPCC) yet decentralized scheme for WSN is presented that uses a combination of a hop by hop congestion control mechanism to maintain desired level of buffer occupancy, and a dynamic routing scheme that works in concert with the congestion control mechanism to forward the packets through less congested nodes. The proposed adaptive approach restricts the incoming traffic thus preventing buffer overflow while maintaining the rate through an …

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Control Of Nonholonomic Mobile Robot Formations: Backstepping Kinematics Into Dynamics, Jagannathan Sarangapani, Travis Alan Dierks Jan 2007

Control Of Nonholonomic Mobile Robot Formations: Backstepping Kinematics Into Dynamics, Jagannathan Sarangapani, Travis Alan Dierks

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, we seek to expand framework developed to control a single nonholonomic mobile robot to include the control of formations of multiple nonholonomic mobile robots. A combined kinematic/torque control law is developed for leader-follower based formation control using backstepping in order to accommodate the dynamics of the robots and the formation in contrast with kinematic-based formation controllers. The asymptotic stability of the entire formation is guaranteed using Lyapunov theory, and numerical results are provided The kinematic controller is developed around control strategies for single mobile robots and the idea of virtual leaders. The virtual leader is replaced with …

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Frequency-Domain Measurement Method For The Analysis Of Esd Generators And Coupling, Jayong Koo, Qing Cai, Giorgi Muchaidze, Andrew Martwick, Kai Wang, David Pommerenke Jan 2007

Frequency-Domain Measurement Method For The Analysis Of Esd Generators And Coupling, Jayong Koo, Qing Cai, Giorgi Muchaidze, Andrew Martwick, Kai Wang, David Pommerenke

Electrical and Computer Engineering Faculty Research & Creative Works

A method for analyzing electrostatic discharge (ESD) generators and coupling to equipment under test in the frequency domain is proposed. In ESD generators, the pulses are excited by the voltage collapse across relay contacts. The voltage collapse is replaced by one port of a vector network analyer (VNA). All the discrete and structural elements that form the ESD current pulse and the transient fields are excited by the VNA as if they were excited by the voltage collapse. In such a way, the method allows analyzing the current and field-driven linear coupling without having to discharge an ESD generator, eliminating …

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The Electronic Passport And The Future Of Government-Issued Rfid-Based Identification, G. Matthew Ezovski, Steve Eugene Watkins Jan 2007

The Electronic Passport And The Future Of Government-Issued Rfid-Based Identification, G. Matthew Ezovski, Steve Eugene Watkins

Electrical and Computer Engineering Faculty Research & Creative Works

Passports and other identification documents may be enhanced using recent advancements in technology. Various national and international bodies are pursuing machine-readable approaches with biometric information. In particular, the international civil aviation organization (ICAO) has adopted standards whereby passports can store biometric identifiers. Countries that participate in the visa waiver program (VWP) began issuing electronic passports in 2006. However, the selection of technologies remains questionable due to privacy and security concerns. This paper examines policy regarding these electronic approaches and developments toward electronic data storage and transmission. Radio-frequency identification (RFID) devices for electronic passports and other existing identity documents are discussed.

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A New Inverter For Improved Fuel Cell Performance In Grid-Tied Application, Nagasmitha Akkinapragada, Badrul H. Chowdhury Jan 2007

A New Inverter For Improved Fuel Cell Performance In Grid-Tied Application, Nagasmitha Akkinapragada, Badrul H. Chowdhury

Electrical and Computer Engineering Faculty Research & Creative Works

The interconnection of a solid oxide fuel cell (SOFC) with the power conditioning units vis-à-vis a DC/DC converter and a DC/AC inverter for interfacing with the utility grid is presented. Fuel cells operate at low voltages and hence need to be boosted and inverted in order to be connected to the grid. The fuel cell and the DC/DC converter modeling are briefly explained. The methodology and the controller design for the control of power flow from the fuel cell to the utility grid are discussed. Power characteristics of the DC/AC inverter are compared with the characteristics of the DC/DC converter …

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Channel Estimation And Phase-Correction For Robust Underwater Acoustic Communications, Y. Rosa Zheng Jan 2007

Channel Estimation And Phase-Correction For Robust Underwater Acoustic Communications, Y. Rosa Zheng

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents a new channel estimation, equalization, and phase correction scheme to combat the convergence and stability problem encountered by time-domain adaptive equalizers in underwater acoustic communication systems. Large Doppler spread and symbol scaling in underwater channels have been challenging problems causing significant phase drift and performance degradation. Our new method targets this problem by first allowing phase errors in the estimation of the fading channel coefficients and then perform group-wise (rather than symbol-wise) phase estimation and correction after equalization and multiple channel combining. Single transmitter and multiple receiver data obtained through ocean experiments have been processed using the …

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Characterizing The Electric Field Coupling From Ic Heatsink Structures To External Cables Using Tem Cell Measurements, Shaowei Deng, Todd H. Hubing, Daryl G. Beetner Jan 2007

Characterizing The Electric Field Coupling From Ic Heatsink Structures To External Cables Using Tem Cell Measurements, Shaowei Deng, Todd H. Hubing, Daryl G. Beetner

Electrical and Computer Engineering Faculty Research & Creative Works

One method for evaluating the unintentional radiated emissions from integrated circuits (ICs) involves mounting the IC on a printed circuit board (PCB) embedded in the wall of a transverse electromagnetic (TEM) cell. The signal voltages on the IC and its package produce electric fields that can couple to cables and other structures attached to the PCB, inducing common-mode currents that can be a primary source of unintentional radiated emissions. The signal currents in the IC and its package produce magnetic fields that can also result in common-mode currents on larger radiating structures. This paper describes a TEM cell measurement method …

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Design Of An Fpga Logic Element For Implementing Asynchronous Null Convention Logic Circuits, Scott C. Smith Jan 2007

Design Of An Fpga Logic Element For Implementing Asynchronous Null Convention Logic Circuits, Scott C. Smith

Electrical and Computer Engineering Faculty Research & Creative Works

Two versions of a reconfigurable logic element are developed for use in constructing afield-programmable gate array NULL convention logic (NCL) field-programmable gate array (FPGA): one with extra embedded registration capability, which requires additional area, and one without. Both versions can be configured as any of the 27 fundamental NCL gates, including resettable and inverting variations, and both can utilize embedded registration for gates with three or fewer inputs; however, only the version with the additional embedded registration capability can utilize embedded registration with four-input gates. These two approaches are compared with each other and with an existing approach, showing that …

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Doppler Spread Estimation For Broadband Wireless Ofdm Systems, Jun Tao, Jingxian Wu, Chengshan Xiao Jan 2007

Doppler Spread Estimation For Broadband Wireless Ofdm Systems, Jun Tao, Jingxian Wu, Chengshan Xiao

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, we present a new Doppler spread estimation algorithm for broadband wireless orthogonal frequency division multiplexing (OFDM) systems with time-varying and frequency-selective Rayleigh fading. The algorithm is developed by analyzing the statistical properties of the power of received signals in the time domain, thus it excludes the influence of inter- carrier interference introduced by channel variation within one OFDM symbol. The operation of the algorithm doesn't require the knowledge of fading coefficients, transmitted data symbols, or signal-to-noise ratio (SNR). It works well under time-selective and frequency-selective Rayleigh fading channel with SNR as low as 0 dB. Moreover, unlike …

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Training Winner-Take-All Simultaneous Recurrent Neural Networks, Xindi Cai, Danil V. Prokhorov, Donald C. Wunsch Jan 2007

Training Winner-Take-All Simultaneous Recurrent Neural Networks, Xindi Cai, Danil V. Prokhorov, Donald C. Wunsch

Electrical and Computer Engineering Faculty Research & Creative Works

The winner-take-all (WTA) network is useful in database management, very large scale integration (VLSI) design, and digital processing. The synthesis procedure of WTA on single-layer fully connected architecture with sigmoid transfer function is still not fully explored. We discuss the use of simultaneous recurrent networks (SRNs) trained by Kalman filter algorithms for the task of finding the maximum among N numbers. The simulation demonstrates the effectiveness of our training approach under conditions of a shared-weight SRN architecture. A more general SRN also succeeds in solving a real classification application on car engine data.

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Validation Of Worst-Case And Statistical Models For An Automotive Emc Expert System, Daryl G. Beetner, Haixiao Weng, Meilin Wu, Todd H. Hubing Jan 2007

Validation Of Worst-Case And Statistical Models For An Automotive Emc Expert System, Daryl G. Beetner, Haixiao Weng, Meilin Wu, Todd H. Hubing

Electrical and Computer Engineering Faculty Research & Creative Works

Previous papers have presented algorithms for an EMC expert system used to predict potential electromagnetic compatibility problems in a vehicle early in the design process. Here, the accuracy of inductive and capacitive coupling algorithms are verified through representative measurements of crosstalk within an automobile. Worst-case estimates used by the algorithms are compared to measured values and are compared to values estimated using statistical methods. The worst-case algorithms performed well up to 10-20 MHz, but overestimated measured results by several dB in some cases and up to 10-15 dB in others. An approximate statistical variation of the current expert system algorithms …

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Wave Propagation On Power Cables With Special Regard To Metallic Screen Design, R. Papazyan, Per Pettersson, David Pommerenke Jan 2007

Wave Propagation On Power Cables With Special Regard To Metallic Screen Design, R. Papazyan, Per Pettersson, David Pommerenke

Electrical and Computer Engineering Faculty Research & Creative Works

The high frequency properties of coaxial power cables are modeled using time- and frequency-domain numerical simulations. This is required due to the complex helical structure of the outer metallic screen. The finite element (FEM) and finite difference time domain methods (FDTD) have been employed to study the effect of screen spiralization. It is established that this screen design causes a dependence of the cable high frequency characteristics on the surrounding medium. Analytical model based on modal analysis of wave propagation in coaxial cables confirms the numerical observations.

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Neural Network Control Of Robot Formations Using Rise Feedback, Jagannathan Sarangapani, Travis Alan Dierks Jan 2007

Neural Network Control Of Robot Formations Using Rise Feedback, Jagannathan Sarangapani, Travis Alan Dierks

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a combined kinematic/torque control law is developed for leader-follower based formation control using backstepping in order to accommodate the dynamics of the robots and the formation in contrast with kinematic-based formation controllers that are widely reported in the literature. A neural network (NN) is introduced along with robust integral of the sign of the error (RISE) feedback to approximate the dynamics of the follower as well as its leader using online weight tuning. It is shown using Lyapunov theory that the errors for the entire formation are asymptotically stable and the NN weights are bounded as opposed …

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Online Reinforcement Learning Control Of Unknown Nonaffine Nonlinear Discrete Time Systems, Qinmin Yang, Jagannathan Sarangapani Jan 2007

Online Reinforcement Learning Control Of Unknown Nonaffine Nonlinear Discrete Time Systems, Qinmin Yang, Jagannathan Sarangapani

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a novel neural network (NN) based online reinforcement learning controller is designed for nonaffine nonlinear discrete-time systems with bounded disturbances. The nonaffine systems are represented by nonlinear auto regressive moving average with exogenous input (NARMAX) model with unknown nonlinear functions. An equivalent affine-like representation for the tracking error dynamics is developed first from the original nonaffine system. Subsequently, a reinforcement learning-based neural network (NN) controller is proposed for the affine-like nonlinear error dynamic system. The control scheme consists of two NNs. One NN is designated as the critic, which approximates a predefined long-term cost function, whereas an …

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Optimal Neuro-Fuzzy External Controller For A Statcom In The 12-Bus Benchmark Power System, Salman Mohagheghi, Ganesh K. Venayagamoorthy, Ronald G. Harley Jan 2007

Optimal Neuro-Fuzzy External Controller For A Statcom In The 12-Bus Benchmark Power System, Salman Mohagheghi, Ganesh K. Venayagamoorthy, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

An optimal neuro-fuzzy external controller is designed in this paper for a static compensator (STATCOM) in the 12-bus benchmark power system. The controller provides an auxiliary reference signal for the STATCOM in such a way that it improves the damping of the rotor speed deviations of its neighboring generators. A Mamdani fuzzy rule base constitutes the core of the controller. A heuristic dynamic programming-based approach is used to further train the controller and enable it to provide nonlinear optimal control at different operating conditions of the power system. Simulation results are provided that indicate the proposed neuro-fuzzy external controller is …

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Reinforcement Learning Based Output-Feedback Controller For Complex Nonlinear Discrete-Time Systems, Peter Shih, Jagannathan Sarangapani Jan 2007

Reinforcement Learning Based Output-Feedback Controller For Complex Nonlinear Discrete-Time Systems, Peter Shih, Jagannathan Sarangapani

Electrical and Computer Engineering Faculty Research & Creative Works

A novel reinforcement-learning based output-adaptive neural network (NN) controller, also referred as the adaptive-critic NN controller, is developed to track a desired trajectory for a class of complex feedback nonlinear discrete-time systems in the presence of bounded and unknown disturbances. This nonlinear discrete-time system consists of a second order system in nonstrict form and an affine nonlinear discrete-time system tightly coupled together. Two adaptive critic NN controllers are designed - primary one for the nonstrict system and the secondary one for the affine system. A Lyapunov function shows the uniformly ultimate boundedness (UUB) of the closed-loop tracking error, weight estimates …

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Frequency-Domain Channel Estimation And Equalization For Broadband Wireless Communications, Y. Rosa Zheng, Chengshan Xiao Jan 2007

Frequency-Domain Channel Estimation And Equalization For Broadband Wireless Communications, Y. Rosa Zheng, Chengshan Xiao

Electrical and Computer Engineering Faculty Research & Creative Works

Frequency-domain equalization (FDE) is an effective technique for high data rate wireless communication systems suffering from very long intersymbol interference. Most of existing FDE algorithms are limited to quasi-static or slow time-varying fading channels, where least mean squares (LMS) or recursive least squares (RLS) adaptive algorithms were utilized for channel estimation. In this paper, we employ interpolation method to develop channel estimation algorithm in the frequency domain. We show that the new channel estimation algorithm can significantly outperform LMS and RLS algorithms. Numerical examples demonstrate that the new algorithm can track time-varying fading channels with Doppler up to 300-400 Hz. …

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Incorporating The Effects Of Magnetic Saturation In A Coupled-Circuit Model Of A Claw-Pole Alternator, Hua Bai, Steven Pekarek, Jerry L. Tichenor, Walter Eversman, Duane J. Buening, Gregory R. Holbrook, Ronald J. Krefta Jan 2007

Incorporating The Effects Of Magnetic Saturation In A Coupled-Circuit Model Of A Claw-Pole Alternator, Hua Bai, Steven Pekarek, Jerry L. Tichenor, Walter Eversman, Duane J. Buening, Gregory R. Holbrook, Ronald J. Krefta

Electrical and Computer Engineering Faculty Research & Creative Works

A method of representing the effects of magnetic saturation in a coupled-circuit model of a claw-pole alternator is presented. In the approach considered, the airgap flux density produced by each winding is expressed as a function of magnetic operating point. A challenge in the implementation is that the airgap flux densities consist of several significant harmonics, each of which changes at a distinct rate as iron saturates. Despite this complication, it is shown that relatively simple measurements can be used to determine model parameters. The model is implemented in the analysis of several alternator/rectifier systems using a commercial state-model-based circuit …

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