Digital Commons Network^™

A Combined Channel-Modified Adaptive Array Mmse Canceller And Viterbi Equalizer, Richard M. Friedman

Theses

In this thesis, a very simple scheme is proposed which couples a maximum-likelihood sequence estimator (MLSE) with a X-element canceller. The method makes use of the MLSE's channel estimator to modify the locally generated training sequence used to calculate the antenna array weights. This method will increase the array's degree of freedom for interference cancellation by allowing the dispersive, desired signal to pass through the array undisturbed. Temporal equalization of the desired signal is then accomplished using maximum-likelihood sequence estimation. The T-spaced channel estimator coefficients and the array weights are obtained simultaneously using the minimum mean square error criteria. The …

Photonic Crystals Composed Of Thick Inductive And Capacitive Meshes, Jay Shah

Theses

The transmission properties of metal meshes are studied for single meshes, photonic double layers and photonic crystals. Simulations are performed with the Flomerics Micro-Stripes program for light of infrared and millimeter wavelengths. The Micro-Stripes program solves Maxwell's equations numerically and, for simulations of the transmittance of metal meshes, has been proven as good as an experiment. Input data are the geometrical parameters, the indices of refraction and the conductivity, chosen according to the Drude model. The light is assumed to be at normal incidence and the simulation results are compared with experiments.

Single layers of inductive meshes are studied for …

Linear Feature Detection Of Rural Imagery Using Multiresolution Filters, Samuel Peter Kozaitis, Rufus H. Cofer

Electrical Engineering and Computer Science Faculty Publications

We detected roads in aerial imagery using a method based on lineal feature detection. Our method used the products of wavelet coefficients at several scales were to identify and locate lineal features. Using our approach effectively increased the size of the region we examined when looking for possible road pixels, and decreased the probability of false positive road pixels. Then, we used a shortest path algorithm to link road pixels to form road networks. Our approach restricted possible road network solutions based on the initial detection of road pixels. We found that our approach leads to an effective method for …

Imagery Chain Assessment For Feature Extraction, Rufus H. Cofer, Samuel Peter Kozaitis

Electrical Engineering and Computer Science Faculty Publications

It is shown that the image chain has important effects upon the quality of feature extraction. Exact analytic ROC results are given for the case where arbitrary multivariate normal imagery is passed to a Bayesian feature detector designed for multivariate normal imagery with a diagonal covariance matrix. Plots are provided to allow direct visual inspection of many of the more readily apparent effects. Also shown is an analytic tradeoff that says doubling background contrast is equal to halving sensor to scene distance or sensor noise. It is also shown that the results provide a lower bound to the ROC of …

An Artificial Immune System For Securing Mobile Ad Hoc Networks Against Intrusion Attacks, William S. Hortos

Electrical Engineering and Computer Science Faculty Publications

An artificial immune system (AIS) for securing mobile ad hoc networks (MANET) against intrusion attacks was presented. A state vector of features and metrics based on the published Secure Routing Protocol (SRP) for MANETs was constructed to encode network security characteristics. The results were reported along with a performance analysis comparing the AIS approach with competing techniques.

Modeling Of Short-Gap Esd Under Consideration Of Different Discharge Mechanisms, S. Bonisch, Wilifried Kalkner, David Pommerenke

Electrical and Computer Engineering Faculty Research & Creative Works

Simulation of short gap electrostatic discharge (ESD) in air needs to consider two processes: a surface process and an avalanche process. Two models, a phenomenological approach and a physical approach, considering both discharge processes are proposed for the simulation of short-gap ESD. A new mathematical derivation for the modeling of the surface process is discussed in detail. A new technique to combine surface and avalanche process models is described. Measured and simulated data based on short-gap ESD are provided and compared. Advantages and drawbacks of the proposed models are discussed. Attained results should help to optimize ESD testing.

Anticipating Vehicle-Level Emi Using A Multi-Step Approach, Geping Liu, David Pommerenke, James L. Drewniak, Richard W. Kautz, Chingchi Chen

Electrical and Computer Engineering Faculty Research & Creative Works

A multi-step procedure for anticipating vehicle-level EMI is proposed in this paper. This approach uses multi-conductor transmission line (MTL) modeling to calculate current distributions along the cable bundle. A common-mode circuit is extracted from the MTL modeling, and is employed in full-vehicle full-wave modeling to determine radiation and interference. In this paper, mode-dispersion and mode-conversion phenomena are investigated, and the ambiguous definitions of the common-mode voltage and common-mode impedance are discussed.

Online Identification Of Turbogenerator's Dynamics Using A Neuro-Identifier, Wenxin Liu, Ganesh K. Venayagamoorthy, Donald C. Wunsch

Electrical and Computer Engineering Faculty Research & Creative Works

The increasing complexity of modern power systems highlights the need for effective system identification techniques for the successful control of power system. This paper proposes a robust continually online trained neuroidentifier to predict the outputs of turbogenerator - terminal voltage and speed deviation. The inputs to the neuro-identifier are the changes of the plant's outputs and plant's inputs. It overcomes the drawback of calculating deviation signals from reference signals for different operating points in previous work. Simulation results show that the neuro-identifier can provide accurate identification under different operating conditions. Furthermore, the neuro-identifier can learn the dynamics of the system …

Modeling Issues For Full-Wave Numerical Emi Simulation, Michael A. Cracraft, Xiaoning Ye, Chen Wang, Sandeep K. R. Chandra, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

In electromagnetic modeling, agreement between modeling and measurements is a common goal. There are questions that define every model. What is to be modeled? How is it going to be modeled? At what scale is it to be modeled? Through sample results and discussion, this paper addresses some general and some specific elements of model veracity. Through determination, numerical models can certainly be pushed to match any measured results. However, in the end the question that this paper addresses is not necessarily "How good can this model be?" as it is "Is this model good enough?".

Spice Model Libraries For Via Transitions, Shaofeng Luan, Giuseppe Selli, Jun Fan, Mauro Lai, James L. Knighten, Norman W. Smith, Ray Alexander, Giulio Antonini, Antonio Ciccomancini, Antonio Orlandi, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

A procedure of building SPICE models for signal via transitions between printed circuit board layers is presented in this paper. The method of extracting parameters of SPICE models from full-wave simulation tool is demonstrated. Then the validity of SPICE models is studied by comparing the solution from SPICE model with that from the full-wave simulation.

Esd Excitation Model For Susceptibility Study, Federico Centola, David Pommerenke, Kai Wang, Thomas Van Doren, Spartaco Caniggia

Electrical and Computer Engineering Faculty Research & Creative Works

The paper provides a simplified model of a known ESD generator that allows modeling the ESD impulses (current and fields) in CST-Microwave Studio. The model is suitable for simulating the excitation of structures by ESD, but it is not intended to predict the fields and current of an ESD generator for its development purpose. The aim is to simultaneously model the ESD generator and a susceptible structure with as few details as possible but to obtain as good a match on current and fields as possible.

Design And Development Of A Low-Cost High Range Resolution X-Band Radar, Paul C. Cantu

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Synthetic Aperture Radar (SAR) is one of the main tools for microwave remote sensing because of its multi-dimensional high resolution characteristics and the capability to operate in nearly all weather conditions, day and night. The University of Nebraska-Lincoln (UNL) initiated the design and development of a low-cost airborne SAR in January 2001 to support our Airborne Remote Sensing Program. The objectives of this project are separated into various evolutionary stages. This thesis will focus on the initial phase of design and construction of an X-band high range resolution radar (HRR) using basic RF /microwave and digital components. The following stages …

Modeling Electromagnetic Wave Propagation In Electrically Large Structures, Jon Wallace

Theses and Dissertations

Existing unified numerical electromagnetic methods are often unable to analyze electrically large structures due to the amount of memory and processing power required, necessitating approximate analyses with limited applicability. In this research a hybrid modeling methodology is adopted to solve these complex problems more efficiently than unified numerical methods and more accurately than analytical methods. Electromagnetic modeling problems are divided into two or more levels of scale. Each level analyzes a specific level of detail and only promotes the required information to the next level. The method is demonstrated by successful application to three important problems: (1) remote sensing of …

Cross-Layer Protocols Optimized For Real-Time Multimedia Services In Energy-Constrained Mobile Ad Hoc Networks, William S. Hortos

Electrical Engineering and Computer Science Faculty Publications

The optimization of cross-layer protocols for real-time multimedia services in energy-constrained mobile ad hoc networks (MANET) was presented. The cross-layer optimization was based on stochastic dynamic programming conditions derived from time-dependent models of MANET packet flows. The performance of the optimized cross-layer protocols was also determined by using dynamic programming conditions.

Real-Time Adaptive Cancellation Of Satellite Interference In Radio Astronomy, Andrew Joseph Poulsen

Theses and Dissertations

Radio astronomy is the science of observing the heavens at radio frequencies, from a few kHz to approximately 300 GHz. In recent years, radio astronomy has faced a growing interference problem as radio frequency (RF) bandwidth has become an increasingly scarce commodity. A programmable real-time DSP least-mean-square interference canceller was developed and demonstrated as a successful method of excising satellite down-link signals from both an experimental platform at BYU, and the Green Bank Telescope at the National Radio Astronomy Observatory in West Virginia. A performance analysis of this cancellation system in the radio astronomy radio frequency interference (RFI) mitigation regime …

Neuroidentification Of System Parameters For The Shunt & Series Branch Control Of Upfc, Ganesh K. Venayagamoorthy, Radha P. Kalyani, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

The crucial factor affecting the modern power systems today is load flow control. The unified power flow controller (UPFC) forms an affective means for controlling the power flow. The UPFC consists of shunt and series inverters which are conventionally controlled using linear controllers. This paper presents the design of neuroidentifiers that identify the system parameters that determine the UPFC controller outputs one-time step ahead thus, making the pathway for the design of adaptive neurocontrollers. Two neuroidentifiers are used for identifying the nonlinear dynamics of power system and UPFC, one neuroidentifier for the shunt inverter and the other for the series …

Automatic Classification Of African Elephant (Loxodonta Africana) Follicular And Luteal Rumbles, Michael T. Johnson, Patrick J. Clemins

Dr. Dolittle Project: A Framework for Classification and Understanding of Animal Vocalizations

Recent research in African elephant vocalizations has shown that there is evidence for acoustic differences in the rumbles of females based on the phase of their estrous cycle (1). One reason for these differences might be to attract a male for reproductive purposes. Since rumbles have a fundamental frequency near 10Hz, they attenuate slowly and can be heard over a distance of several kilometers. This research exploits differences in the rumbles to create an automatic classification system that can determine whether a female rumble was made during the luteal or follicular phase of the ovulatory cycle. This system could be …

Design And Testing Of Spacecraft Power Systems Using Vtb, Zhenhua Jiang, Shengyi Liu, Roger A. Dougal

Faculty Publications

A study is presented on the design and testing of spacecraft power systems using the virtual test bed (VTB). The interdisciplinary components such as solar array and battery systems were first modeled in native VTB format and validated by experiment data. The shunt regulator and battery charge controller were designed in Simulink according to the system requirements and imported to VTB. Two spacecraft power systems were then designed and tested together with the control systems.

Photonic Crystals: Modeling And Simulation, Shangping Guo

Electrical & Computer Engineering Theses & Dissertations

Photonic crystals are periodic electromagnetic media in optical wavelength scale. They possess photonic band gaps (PBGs) that inhibit the existence of light within the crystals in certain wavelength range. Such band gaps produce many interesting optical phenomena. In this dissertation, the frequency (plane wave method, PWM) and time domain (finite difference time domain method, FDTD) methods are developed for their modeling and simulation.

The theory and algorithm of plane wave method are studied in detail and implemented in a unique and efficient approach. PWM is used to obtain the gap and mode information of ideal and defective photonic crystals. Several …

Diagnostics Of Eccentricities And Bar/End-Ring Connector Breakages In Polyphase Induction Motors Through A Combination Of Time-Series Data Mining And Time-Stepping Coupled Fe-State Space Techniques, John F. Bangura, Richard J. Povinelli, Nabeel Demerdash, Ronald H. Brown

Electrical and Computer Engineering Faculty Research and Publications

This paper develops the foundations of a technique for detection and categorization of dynamic/static eccentricities and bar/end-ring connector breakages in squirrel-cage induction motors that is not based on the traditional Fourier transform frequency-domain spectral analysis concepts. Hence, this approach can distinguish between the "fault signatures" of each of the following faults: eccentricities, broken bars, and broken end-ring connectors in such induction motors. Furthermore, the techniques presented here can extensively and economically predict and characterize faults from the induction machine adjustable-speed drive design data without the need to have had actual fault data from field experience. This is done through the …

Atmospheric Water Vapor Lidar Measurements Using Analog And Photon Counting Techniques, Anuj Maheshkumar Shah

Electrical & Computer Engineering Theses & Dissertations

Atmospheric water vapor measurements are essential for the understanding of Earth's weather and radiation budget, along with the water cycle. The remote sensing Differential Absorption Lidar (DIAL) technique is a commanding method used for water vapor measurements from aircraft, spaceborne, and ground-based platforms. The new unmanned aerial vehicle (UAV) water vapor DIAL system provides great feasibility due to the weight and size limitations. The system has significantly less weight, power consumption, and noise presence, thus making it great for UAV applications.

This thesis discusses a UAV water vapor DIAL system that was designed, developed, and evaluated. The research effort was …

Monte Carlo Analysis Of Millimeter-Wave Gan Based Gunn Effect Oscillators, Sridhara Viswanadham

Electrical & Computer Engineering Theses & Dissertations

Gunn diodes are one of the most common high frequency solid-state oscillators at the present time, and are considered as promising devices for millimeter and submillimeter wave applications. Monte Carlo studies of Gunn diodes based on bulk wurtzite GaN have been carried out in this thesis research. Two structures have been examined: (i) devices with conventional single notch structure and (ii) repetitive structures with serial segments to fashion a "multiple domain" device. Wurtzite GaN has been chosen because of the high drift velocity and because analytical expressions for the band structure have recently become available. Performance parameters of interest such …

Progress In Spectroscopic Ellipsometry: Applications From Vacuum Ultraviolet To Infrared, James N. Hilfiker, Corey L. Bungay, Ron A. Synowicki, Thomas E. Tiwald, Craig M. Herzinger, Blaine Johs, Greg K. Pribil, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

Spectroscopic ellipsometry (SE) is a noncontact and nondestructive optical technique for thin film characterization. In the past 10 yr, it has migrated from the research laboratory into the semiconductor, data storage, display, communication, and optical coating industries. The wide acceptance of SE is a result of its flexibility to measure most material types: dielectrics, semiconductors, metals, superconductors, polymers, biological coatings, and even multilayers of these materials. Measurement of anisotropic materials has also made huge strides in recent years. Traditional SE measurements cover the ultraviolet, visible, and near infrared wavelengths. This spectral range is now acquired within seconds with high accuracy …

An Adaptive Neural Network Identifier For Effective Control Of A Static Compensator Connected To A Power System, Salman Mohagheghi, Jung-Wook Park, Ganesh K. Venayagamoorthy, Mariesa Crow, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

A novel method for nonlinear identification of a static compensator connected to a power system using continually online trained (COT) artificial neural networks (ANNs) is presented in this paper. The identifier is successfully trained online to track the dynamics of the power network without any need for offline data and can be used in designing an adaptive neurocontroller for a static compensator connected to such system.

Vertebra Shape Classification Using Mlp For Content-Based Image Retrieval, Sameer K. Antani, L. Rodney Long, George R. Thoma, R. Joe Stanley

Electrical and Computer Engineering Faculty Research & Creative Works

A desirable content-based image retrieval (CBIR) system would classify extracted image features to support some form of semantic retrieval. The Lister Hill National Center for Biomedical Communications, an intramural R&D division of the National Library for Medicine (NLM), maintains an archive of digitized X-rays of the cervical and lumbar spine taken as part of the second national health and nutrition examination survey (NHANES II). It is our goal to provide shape-based access to digitized X-rays including retrieval on automatically detected and classified pathology, e.g., anterior osteophytes. This is done using radius of curvature analysis along the anterior portion, and morphological …

Optical Communications By Frequency Content Of Femtosecond Laser Pulses, Dennis Alexander, Mark L. Rohlfs

Department of Electrical and Computer Engineering: Faculty Publications

A free-space optical communications System is provided capable of transmitting data over long distances through the atmosphere. The communications System according to the present invention comprises an optical transmitter at a first location, the optical transmitter comprising a femtosecond pulsed laser Source for producing a train of femtosecond laser pulses. The optical transmitter further comprises a laser pulse width modulator to provide a pulse width modulated train of femtosecond laser pulses corresponding to the data being transmitted. The communications System further com prises an optical receiver at a Second location for receiving the modulated train of femtosecond laser pulses. The …

Actuator Fault Compensation For A Helicopter Model, Xiao-Hua Yu

Electrical Engineering

A fault-tolerant system is the one that can continue its operation without significant impact on performance in the presence of hardware and/or software errors. In this paper, the design of a fault-tolerant flight controller to control UH-60 helicopter is investigated. A 9th-order state space representation of the helicopter model operating at the forward mode with 80 knots is presented; then a fault-tolerant optimal feedback controller is designed and tested.

Apparatus, Method And System For Common-Mode Stabilization In Circuits Having Differential Operation, George Palaskas, Vladimir Prodanov

Electrical Engineering

A system, method and apparatus are disclosed for common-mode voltage feedback. The preferred system includes a plurality of differential circuits, a corresponding plurality of common-mode voltage detectors, a corresponding plurality of buffer circuits, and a common-mode control circuit. Each differential circuit is operative to produce a first differential output voltage and a second differential output voltage. Each corresponding common-mode voltage detector is operative to provide a common-mode voltage from the first differential output voltage and the second differential output voltage. The common-mode control circuit provides a control voltage signal from the common-mode voltage and from a reference voltage. Each buffer …

Learning Rules From System Call Arguments And Sequences For Anomaly Detection, Guarav Tandon, Philip K. Chan

Electrical Engineering and Computer Science Faculty Publications

Many approaches have been suggested and various systems have been modeled to detect intrusions from anomalous behavior of systems calls as a result of an attack. Though these techniques have been shown to be quite effective, a key element seems to be missing -- the inclusion and utilization of the system call arguments to create a richer, more valuable signature and to use this information to model the intrusion detection system more accurately. We put forth the idea of adopting a rule learning approach that mobilizes rules based upon system calls and models the system for normal traffic using system …

Identifying Outliers Via Clustering For Anomaly Detection, Muhammad H. Arshad, Philip K. Chan

Electrical Engineering and Computer Science Faculty Publications

Detecting known vulnerabilities (Signature Detection) is not sufficient for complete security. This has raised recent interest in Anomaly Detection (AD), in which a model is built from normal behavior and significant deviations from this model are flagged anomalous. However, most AD algorithm assume clean training data, which could be hard to obtain. Our proposed algorithm relaxes. For this, we define the notion a strong outlier, which is suspicious at both local and global levels. Finally we illustrate the effectiveness of our approach on the DARPA '99 dataset and find that our approach is at par in number of detections at …