Digital Commons Network^™

Double-Pass High-Gain Laser Amplifiers, Janet M. Casperson, Frederick G. Moore, Lee W. Casperson

Electrical and Computer Engineering Faculty Publications and Presentations

Double-pass laser amplifiers have advantages of compactness and efficiency in the amplification of optical signals, and such amplifiers have been employed in a wide range of optical systems. Work in this area is reviewed briefly, and analytical solutions are obtained for the intensity of the electromagnetic waves in double-pass homogeneously-broadened high-gain laser amplifiers. Expressions are derived relating the output power to the input, including the effects of arbitrary mirror reflectivity and frequency detuning from line center. In the limits of weak saturation and of high reflectivity the results are consistent with earlier studies.

Detection And Robustness Of Digital Image Watermarking Signals : A Communication Theory Approach, George F. Elmasry

Dissertations

The detection and robustness of the watermark signal is studied from a communications point of view. The contributions of this dissertation are presented in two parts. The first part, which covers the detection aspect, introduces a new digital image watermarking approach that embeds meaningful information in a copyright protection watermark signal; demonstrates the need to approach the watermark signal as a power-constrained signal; studies the relationship between the watermark signal dimension and the image capacity to the signal; explains the similarities and differences between detecting the watermark signal and detecting a signal over a spread-spectrum communication channel; and analyzes the …

Evaluation Of Caltrans District 10 Automated Warning System, Year Two Progress Report, Art Maccarley

Electrical Engineering

District 10 of the California Department of Transportation (Caltrans) encompasses an area of seasonal fog and dust-related visibility problems that have been the cause of numerous multi-car traffic collisions, many fatal. In 1990, motivated by the expansion of State Route 120 (SR 120) connecting Interstate Highway 5 (I-5) and State Route 99 (SR 99), Caltrans proposed a sophisticated multi-sensor automated warning system as a means for reducing incidents in this high-traffic area. This proposal, and the significant development effort that followed, culminated in the implementation of Phase 1 of the Caltrans Automated Warning System, or “CAWS”, which entered service in …

Signal Induced Emi In Fibre Channel Cable-Connector Assemblies, Minjia Xu, S. Radu, James L. Knighten, James L. Drewniak, Todd H. Hubing, L. O. Hoeft, J. T. Dibene Ii

Electrical and Computer Engineering Faculty Research & Creative Works

The EMI performance of cable-connector assemblies designed for FC-0 transmission has been studied. Two types of cable and two connector styles were evaluated. Experimental results show that the dominant radiation mechanism for short cable lengths is the common-mode current caused by source and PCB skew that leaks to the exterior of the shield via the transfer impedance of the connector. However, the cable imbalance becomes a more significant source of common-mode current than the source skew when the cable assembly is tens of meters long.

Design And Performance Characterization Of Simultaneous Reflectance And Surface-Mapping Laser Scanner For Application In Underwater Inspection, Frank M. Caimi, Donna M. Kocak, Coy Colquitt

Electrical Engineering and Computer Science Faculty Publications

Considerable advancements have been made in undersea imaging over the past decade enabling long-range detection and observation of underwater objects in clear and turbid (cloudy) water. The image transfer characteristics of the medium (i.e. scattering and absorption) have been primary obstacles in developing high performance systems. However, the application of lasers to the imaging formation process is currently providing a means for acquiring long-range images, over 5-6 attenuation lengths in comparison to 1 -2 attenuation lengths for more conventional methods. In addition, laser technology is now offering the promise of systems capable of forming range maps and depth resolved images. …

Guest Editorial: Special Section On Acousto-Optic Devices And Optical Information Processing: Research And Developments, Partha P. Banerjee, Ting-Chung Poon

Electrical and Computer Engineering Faculty Publications

This guest editorial provides an overview of the topical area and an introduction to the articles featured in the special section.

Laser Beam Profile Deformation Effect During Bragg Acousto-Optic Interaction: A Non-Paraxial Approximation, Ray S. Huang, Chen-Wen Tarn, Partha P. Banerjee, Doungchin Cao

Electrical and Computer Engineering Faculty Publications

It is commonly known that the spatial profiles of the diffracted light beams during Bragg acousto-optic interaction are distorted due to the Bragg angle selection mechanism. All the conventional studies on this effect use the paraxial approximation. But this approximation should be amended when the incident angle of the light is large enough that the diffracted light waves do not propagate closely along the optic axis of the acousto-optic diffraction system. By using a spatial Fourier transform approach, we rigorously study the light beam profile deformation effect of the diffracted light during the Bragg acousto-optic interaction beyond the paraxial approximation. …

Examination Of Beam Propagation In Misaligned Holographic Gratings And Comparison With The Acousto-Optic Transfer Function Model For Profiled Beams, Monish Ranjan Chatterjee, David D. Reagan

Electrical and Computer Engineering Faculty Publications

A transfer function formalism developed earlier for the propagation of profiled optical beams through acousto-optic Bragg cells is revisited and applied to a thick holographic grating. The results based on the holographic coupled wave model and the acousto-optic multiple scattering model are shown to be compatible, and equivalent parameters such as the Q and grating strength are defined for the two systems. Results for a Gaussian spatial profile are numerically computed and compared. For the holographic grating, a profiled beam may be interpreted as an angular misalignment or Bragg-angle mismatch problem. The case of Bragg-wavelength mismatch is also investigated for …

Newton Parameter Update Algorithm For Recurrent Neural Networks Applied To Adaptive System Identification And Control, Donald Allen Gates

Electrical & Computer Engineering Theses & Dissertations

This paper shows that the combination of a second-order neural network parameter update algorithm and internal network feedback can be effectively used for adaptive, nonlinear, dynamical system identification and control. Adaptive neural identification and control algorithms are typically utilized for real-time applications where the rate of adaptation is often critical. A fast, adaptive network parameter update algorithm is presented.

Simulation results show that this algorithm is capable of quickly identifying and adapting to changes in system parameters, making it feasible to use for real-time control and fault accommodation applications.

Parallel Digital Signal Processing On A Network Of Personal Computers Case Study: Space-Time Adaptive Processing, Fernando Silva

Theses and Dissertations

Network based parallel computing using personal computers is currently a popular choice for concurrent scientific computing. This work evaluates the capabilities and the performance of the AFIT Bimodal Cluster (ABC); a heterogeneous cluster of PCs connected by switched fast Ethernet and using MPICH 1.1 for interprocess communication for parallel digital signal processing using Space Time Adaptive Processing (STAP) as the case study. The MITRE RT_STAP Benchmark version 1.1 is ported and executed on the ABC, as well as on a cluster of six Sun SPARC workstations connected by a Myrinet network (the AFIT NOW), and on a IBM SP for …

A Performance Analysis Of A Low Earth Orbit Satellite System, Korkut A. Ercakar

Theses and Dissertations

This thesis provides a performance analysis of the TELEDESIC® Low Earth Orbit Satellite System. It analyzes the system's performance to meet the real-time communications constraints with a full satellite constellation. Computer simulation results are the sources to evaluate delays associated with packets transmitted from source to destination earth stations. The simulation is run at low, medium and high loading levels with two different, uniform and non-uniform, traffic distributions. The evaluated results are end-to-end packet delays and packet rejection rate. The results show that the TELEDESIC® satellite system network is capable of meeting the real-time communication requirements with delay values much …

Adaptive Interference Cancelation Techniques For Multicarrier Modulated Systems, Matthijs A. Visser

Dissertations

Current wireline systems and wireless broadcasting systems employ multicarrier modulation (MCM). This includes the high-rate digital subscriber line (HDSL), digital audio broadcasting system (DAB) and the digital terrestrial television broadcasting system (dTTb). Multicarrier modulation is also envisioned for high-speed indoor wireless local area networks (WLAN). Additionally, multicarrier code division multiple access (MC-CDMA), a hybrid of orthogonal frequency division multiplexing (OFDM) and CDMA, is proposed for the downlink (base-to-mobile) of a 3rd generation wireless system as part of the IMT-2000 standardization process.

The performance of an MC-CDMA system--similar to a direct sequence CDMA (DS-CDMA) system--is limited by the presence of multiple …

On Scheduling Input Queued Cell Switches, Shizhao Li

Dissertations

Output-queued switching, though is able to offer high throughput, guaranteed delay and fairness, lacks scalability owing to the speed up problem. Input-queued switching, on the other hand, is scalable, and is thus becoming an attractive alternative. This dissertation presents three approaches toward resolving the major problem encountered in input-queued switching that has prohibited the provision of quality of service guarantees.

First, we proposed a maximum size matching based algorithm, referred to as min-max fair input queueing (MFIQ), which minimizes the additional delay caused by back pressure, and at the same time provides fair service among competing sessions. Like any maximum …

On-Line State And Parameter Estimation In Nonlinear Systems, David A. Haessig

Dissertations

On-line, simultaneous state and parameters estimation in deterministic, nonlinear dynamic systems of known structure is the problem considered. Available methods are few and fall short of user needs in that they are difficult to apply, their applicability is restricted to limited classes of systems, and for some, conditions guaranteeing their convergence don't exist.

The new methods developed herein are placed into two categories: those that involve the use of Riccati equations, and those that do not. Two of the new methods do not use Riccati equations, and each is considered to be a different extension of Friedland' s parameter observer …

Fdtd-Based Full Wave Co-Simulation Model For Hybrid Electromagnetic Systems, Tong Li

Dissertations

In high-frequency ranges, the present electronic design automation software has limited capabilities to model electromagnetic (EM) systems where there are strong field effects influencing their characteristics. In this situation, a full-wave simulation tool is desired for the analysis and design of high-speed and non-linear EM systems. It is necessary to explore the interaction between the field and electronic components during a transient process when field effects are more significant. The finite-difference time-domain (FDTD) technique receives growing attention in the area of EM system analysis and simulation due to its simplicity, flexibility and robustness. It is a full-wave simulation method that …

Dual Frequency Bi-Othogonally Polarized Antennas For Gps Applications, Anand Arun Mahale

Theses

Dual frequency bi-orthogonally polarized antenna to be used in Global Positioning System applications operating in Li (1575.42 ± 10.23 MHz) and L2 (1227.60 ± 10.23 MHz) Bands has been studied. To ensure compatibility with existing applications, the antenna size is limited in dimensions to 4.120" x 4.680" x 1.250" including the radome. Orthogonally placed two dual frequency probe excited patches were designed using a high dielectric constant substrate (ε r = 9.8 and thickness of 250 mils, Rogers TMM10i material) to obtain vertical and horizontal polarization for each band. The measured performance of this antenna showed good agreement with the …

Development Of A Context-Specific Search Engine, An Executive Information System, And A Novel Www Ready External Cost Model, Amit V. Revankar

Theses

NJPIES is associated with Information Ecology and Sustainability, a holistic approach to environmental data collection, compilation, integration and provision that puts people, not technology, at the center of the environmental information world.

The first main goal of this project was to develop an algorithm and associated computer-based tool that could perform a lifecycle cost analysis for a model system. The application developed solved the primary problem associated with the lifecycle cost analysis of a product: it accounted for all costs (e.g., environmental costs such as ecological costs and health costs associated with emissions) of the activity. A lifecycle cost analysis …

Handoff Effect On Prma (Packet Reservation Multiple Access) In Micro-Cellular System, Dongsuk Park

Theses

PRMA(Packet Reservation Multiple Access) has been proposed for third generation wireless information network by Goodman et al. [5] [4]. Due to small micro cell radius mobile initiated handoff has been proposed to disperse the burden of BS(Base Station) [14]. Even though these frequent handoffs will not burden on BS, increased contends due to handoff will affect the over all performance of PRMA.

In this paper, we analyze the handoff effect on PRMA performance under micro-cellular system. Steady state speech terminal model with handoff is proposed.. Stabilities are derived based on proposed steady state terminal model[F(c_s)=M] and also increased …

Graphical User Interface For The Dsp : Using Texas Instruments Tms320c31 And Labview, Tahir Nazir

Theses

Digital Signal Processors (DSP's) have become very popular due to their ease of operation, economic value, adaptability and availability. However, the development environments for the DSP are still the archaic Assembly and C language programming. It is tedious, error prone and time consuming to develop and use DSP applications using these compared to Graphical User Interface development tools if available. In the modern age programming is very heavily done in object oriented graphical languages like the Visual C++ and Visual Basic. Windows also gives a good graphical user interface.

LAB VIEW with its readily available ensemble of good analysis, programming …

Radiative Properties Of Ir Materials, Manish R. Babladi

Theses

The objective of this thesis is to study the radiative properties of materials of interest in the infrared range of wavelengths. In particular, three distinct materials have been considered here - Erbium oxide, alumina and quartz. Erbium oxide has unique selective line emission, which gives a high emittance at a particular wavelength and low emittance in the rest of the infrared spectrum. It has applications in the design and development of thermophotovoltaic (TPV) generators. Because of its selective emission properties, erbium oxide assists in concentrating the radiant energy into a narrow band near the bandgap energy of the TPV cell, …

Vibration Control Of Ultra-High Precision Magnetic Leadscrew Using Recurrent Neural Network, Bhaskar Vinayak Dani

Theses

Ultra-high precision positioning is of strategic importance to modern industrial processes such as semiconductor manufacturing. Traditional drives with mechanical transmission elements exhibit nonlinearities such as friction, backlash and hysteresis which limit the system performance significantly. The magnetic leadscrew in this work belongs to the class of contactless drives which overcome the above mentioned limitations of contact-type drives. The operation is based on leadscrew/nut coupling but unlike mechanical Ieadscrews, the threads of the nut and the leadscrew are aligned magnetically and do not come in contact. Thus, "hard" nonlinearities are substantially reduced resulting in high precision and high resolution.

The dynamics …

A Worst-Case Analysis Of Direct-Sequence Spread-Spectrum In Multipath Channels, Murad Hizlan, Xuedong Liu

Electrical and Computer Engineering Faculty Publications

We consider a direct-sequence spread-spectrum system operating in an indoors environment in the presence of multiaccess and multipath interference, and additive white Gaussian noise. We focus on the worst-case bit error probability of this system with a constraint on signal-to-interference ratio, and derive a Chernoff-type upper bound on this error probability. We evaluate the upper bound for a special case in order to gain understanding of the basic worst-case performance. We also compare the effects of the worst-case multipath interference with those of the worst-case multiuser interference of …

Low-Temperature Molecular Beam Epitaxy Of Gaas: A Theoretical Investigation Of Antisite Incorporation And Reflection High-Energy Diffraction Oscillations, K. Natarajan, Rama Venkat, Donald L. Dorsey

Electrical & Computer Engineering Faculty Research

Surface dynamics dominate the incorporation of charged, As+Ga, and neutral, As0Ga, antisite arsenic, and the temporal variation of reflection high-energy electron diffraction(RHEED) intensity in the low-temperature molecular beam epitaxy of (100) gallium arsenide(GaAs). A rate equation model is proposed which includes the presence and dynamics of a physisorbed arsenic (PA) layer riding the growth surface. The PA layer dictates the incorporation and concentration of As+Ga and As0Ga. Additionally, it influences the RHEED oscillations (ROs) behavior and the RO’s dependence on its coverage through its contribution to the reflected intensity. The model results for the dependence of As+Ga and As0Ga concentrations …

Stratified Volume Diffractive Optical Elements As High Efficiency Gratings, Gregory P. Nordin, D. M. Chambers

Faculty Publications

We propose stratified volume diffractive optical elements as a new type of diffractive optical element that is capable of functioning as a high-efficiency grating in applications with requirements not suited to traditional holographic or diffractive optical techniques. In this approach, diffractive optical fabrication methods are used to construct an optical structure that emulates volume grating behavior. We discuss the diffraction properties of stratified volume diffractive optical elements and compare them with those used previously in both volume holographic optical elements and stratified volume holographic optical elements. A systematic design process is then presented for deriving structure parameters. We illustrate this …

Integrating Research Results Into A Power Engineering Curriculum, Chanan Singh, Kraig J. Olejniczak, Kevin Tomsovic, Richard D. Christie, Anil Pahwa, Kwang Y. Lee, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents summaries of the activities of six research active power engineering educators which were presented in a panel session of the same name at the IEEE Power Engineering Society Winter Meeting on February 3, 1997 in New York City, USA. Each of the panelists discusses how research results are incorporated into courses and how students benefit from this approach.

Output Control Of Vertical Microcavity Light Emitting Device, James A. Lott

AFIT Patents

An improved intracavity sensor based output power control for microcavity light emitting devices. An improved phototransistor transducer is both configured and physically disposed so that it passively transmits the spurious optical energy output of the microcavity light emitting device while simultaneously generating a light determined electrical signal of easily used large magnitude that is nearly free of error. The base-collector region of the transistor is disposed with a quantum well absorbing layer and produces a signal responsive to a selected emission wavelength. The configuration of the optical energy communicating transducer is arranged so that it is improved in sensitivity and …

Comprehensive Analysis Of Edge Detection In Color Image Processing, Shu-Yu Zhu, Konstantinos N. Kostas Plataniotis, Anastasios N. Venetsanopoulos

Electrical Engineering and Computer Science Faculty Publications

Various approaches to edge detection for color images, including techniques extended from monochrome edge detection as well as vector space approaches, are examined. In particular, edge detection techniques based on vector order statistic operators and difference vector operators are studied in detail. Numerous edge detectors are obtained as special cases of these two classes of operators. The effect of distance measures on the performance of different color edge detectors is studied by employing distance measures other than the Euclidean norm. Variations are introduced to both the vector order statistic operators and the difference vector operators to improve noise performance. They …

Routing And Scheduling I/O Transfers On Wormhole-Routed Mesh Networks, Bhagirath Narahari, Sunil Shende, Rahul Simha, S. R. Subramanya

Electrical and Computer Engineering Faculty Research & Creative Works

This paper studies the problem of routing and scheduling parallel I/O operations to minimize the time required to transfer data between processors and I/O devices. In particular, a 2-dimensional mesh architecture is considered in which routing is performed using wormhole switching and I/O nodes are placed on the periphery of the mesh. Two broad classes of data transfer mechanisms are examined: schedules with blocking (SB), in which packets may be temporarily blocked during transit, and schedules with no blocking (SNB), in which packets are never blocked in the network. For both classes, optimal scheduling is shown to be NP-complete, and …

Development And Testing Of An Ac Micro Hollow Cathode Simulator, Thomas E. Caldwell

Electrical & Computer Engineering Theses & Dissertations

The use of AC source plasma discharge devices in applications such as material processing and film deposition has increased in recent years due to improvements in discharge efficiency made possible by devices such as the micro hollow cathode. Designing hollow cathodes for specific applications requires an understanding of the processes that govern the discharge. Simulation is an inexpensive tool for understanding hollow cathode operation and optimizing the device for specific applications. This thesis describes the development of an AC micro hollow cathode simulator. It details the theoretical models used in the simulation and presents the results of test cases intended …

Stability Analysis And Augmentation Of A Closed-Loop Computer Control System Subject To Electromagnetic Disturbances, Mustafa Doğan

Electrical & Computer Engineering Theses & Dissertations

Most electronic and electrical equipment is not only a potential source of electromagnetic interference (EMI) but can also malfunction when exposed to certain levels of ambient EMI. This phenomena becomes more significant for digital control-computers automating the command and control performances in complex plants. Such EM disturbances can introduce transient signals on analog sensor and actuator lines, change data values on digital buses and in memory, or even produce logic changes in the CPU. The result of these so called computer upsets is the introduction of some degree of degradation in the quality of the control signal ranging from a …