Digital Commons Network^™

Stochastic Estimation And Control Of Queues Within A Computer Network, Nathan C. Stuckey

Theses and Dissertations

An extended Kalman filter is used to estimate size and packet arrival rate of network queues. These estimates are used by a LQG steady state linear perturbation PI controller to regulate queue size within a computer network. This paper presents the derivation of the transient queue behavior for a system with Poisson traffic and exponential service times. This result is then validated for ideal traffic using a network simulated in OPNET. A more complex OPNET model is then used to test the adequacy of the transient queue size model when non-Poisson traffic is combined. The extended Kalman filter theory is …

Ghz Serial Passive Clock Distribution In Vlsi Using Bidirectional Signaling, Vladimir I. Prodanov, Mihai Banu

Electrical Engineering

We introduce a serial passive clock distribution technique allowing efficient and accurate skew removal at any arbitrary clock drop point. The passive transmission medium may be on-chip electrical transmission lines built in current IC technology or possible optical wave-guides in future developments. The proposed technique is naturally insensitive to practical loses and other non ideal effects and has the capability of covering large chip areas.

Novel Layered Scalable Video Coding Transmission Over Mimo Wireless Systems With Partial Csi And Adaptive Channel Selection, Daewon Song, Chang Wen Chen

Electrical Engineering and Computer Science Faculty Publications

In this paper, we present a novel layered scalable video transmission scheme over multi-input multi-output (MIMO) wireless systems. The proposed layered scalable video transmission scheme is able to adaptively select the MIMO sub-channels for prioritized delivery of layered video signals based on only estimated partial channel state information (CSI). This scheme is fundamentally different from open loop (OL)-MIMO systems such as V-BLAST in which the CSI is only available at the receiver side. Without CSI at the transmitter, data sequences in OL-MIMO are transmitted simultaneously with equal power via multiple antennas. Therefore, OL-MIMO systems are not appropriate for transmitting compressed …

Monte Carlo Simulation Of Scanning Electron Microscopy Bright Contrast Images Of Suspended Carbon Nanofibers, Makoto Suzuki, Toshishige Yamada, Cary Y. Yang

Electrical and Computer Engineering

The authors present a Monte Carlo study of previously observed bright contrast from carbon nanofibers suspended over the underlying substrate using scanning electron microscopy (SEM). The analysis shows that the origin of the bright contrast is mainly the increase in the secondary electron signal from the substrate when a gap between the nanofiber and substrate exists. The SEM signal dependence on the gap height is well reproduced by Monte Carlo simulation as well as a derived analytical expression. The bright contrast prevails when the SEM beam size is much smaller than the nanofiber diameter.

Threshold Power Of Canonical Antennas For Inducing Sar At Compliance Limits In The 300-3000 Mhz Frequency Range, Mohammod Ali, Mark G. Douglas, Abu T.M. Sayem, Antonio Faraone, Chung-Kwang Chou

Faculty Publications

A study of the specific absorption rate (SAR) in an exposed body induced by canonical antennas is presented, with the aim of determining an upper bound for the antenna transmit power that demonstrates that a product is inherently compliant with internationally accepted radio frequency (RF) exposure limits. Starting from the fundamental limits in antenna quality factor (Q) and the corresponding bandwidth, several antenna sizes are selected, and their SAR distributions are computed using the method of moments (MoM) and finite-difference time domain (FDTD) method in the frequency range 300-3000 MHz. The threshold powers are then determined, below which the peak …

The Social Construction Of Authorship: An Investigation Of Subjectivity And Rhetorical Authority In The College Writing Classroom, Johannah Rodgers

Dissertations, Theses, and Capstone Projects

Although we use the term author on a daily basis to refer to certain individuals, bodies of work, and systems of ideas, as Michel Foucault and other critics have pointed out, attempting to answer the question “What is an Author?” is by no means a simple proposition. And, starting from the position that there is no single, or definitive answer to this complex question, this dissertation seeks to contribute to the ongoing discussion of the genealogy of authorship by investigating the ways in which conceptions of the author have informed models of the writing subject in the field of rhetoric …

Some Contributions On Mimo Radar, Nikolaus Lehmann

Dissertations

Motivated by recent advances in Multiple Input Multiple Output (MIMO) wireless communications, this dissertation aims at exploring the potential of MIMO approaches in the radar context. In communications, MIMO systems combat the fading effects of the multi-path channel with spatial diversity. Further, the scattering environment can be used by such systems to achieve spatial multiplexing. In radar, a complex target consisting of several scatterers takes the place of the multi-path channel of the communication problem. A target's radar cross section (RCS), which determines the amount of returned power, greatly varies with the considered aspect. Those variations significantly impair the detection …

Channel-Predictive Link Layer Arq Protocols In Wireless Networks, Huseyin Dogukan Cavdar

Theses

Communication performance over a wireless channel should be considered according to two main parameters: energy and throughput. The reliable data transfer is a key to these goals. The reliable node-to-node data transfer is performed by link layer protocols. One prominent approach is Automatic Repeat Request (ARQ) protocol. The traditional ARQ protocols attempt to recover the erroneously transmitted frames by retransmitting those frames, regardless of the channel state. Since this channel state unaware behaviour may cause unnecessary retransmissions, traditional ARQ protocols are expected to be energy inefficient. Some ideas have been proposed such as stochastic learning automaton based ARQ, and channel …

Recent Progress In The Development Of Incits W1.1, Appearance-Based Image Quality Standards For Printers, Elisa H. Barney Smith

Electrical and Computer Engineering Faculty Publications and Presentations

In September 2000, INCITS W1 (the U.S. representative of ISO/IEC JTC1/SC28, the standardization committee for office equipment) was chartered to develop an appearance-based image quality standard.^(J),(2) The resulting W1.1 project is based on a proposal⁽⁴⁾ that perceived image quality can be described by a small set of broad-based attributes. There are currently five ad hoc teams, each working towards the development of standards for evaluation of perceptual image quality of color printers for one or more of these image quality attributes. This paper summarizes the work in progress.

Distributed Video Coding Based On Constrained Rate Adaptive Low Density Parity Check Codes, Rong Ke Liu, Guo Gang Hua, Chang Wen Chen

Electrical Engineering and Computer Science Faculty Publications

Distributed video coding is an emerging area of research for digital video driven partly by the widespread use of video acquisition devices by the consumers. In this paper, we present a distributed video coding scheme based on zero motion identification at the decoder and constrained rate adaptive low density parity check (LDPC) codes. Zero-motion-block identification mechanism is introduced at the decoder, which takes the characters of video sequence into account. The constrained error control decoder can use the bits in the zero motion blocks as a constraint to achieve a better decoding performance and further improve the overall video compression …

Progressive Image Transmission With Rcpt Protection, Lei Yao, Lei Cao, Chang Wen Chen

Electrical Engineering and Computer Science Faculty Publications

In this paper, a joint source-channel coding scheme is proposed for progressive image transmission over channels with both random bit errors and packet loss by using rate-compatible punctured Turbo codes (RCPT) protection only. Two technical components which are different from existing methods are presented. First, a data frame is divided into multiple CRC blocks before being coded by a turbo code. This is to secure a high turbo coding gain which is proportional to the data frame size. In the mean time, the beginning blocks in a frame may still be usable although the decoding of the entire frame fails. …

Polarizing Properties Of Embedded Symmetric Trilayer Stacks Under Conditions Of Frustrated Total Internal Reflection, Rasheed M.A. Azzam, Siva R. Perla

Electrical Engineering Faculty Publications

An error in the application of the design procedure described in a previous paper [Appl. Opt. 45, 1650 (2006)] has been corrected, and new revised figures are included in this erratum.

Electrical And Computer Engineering Research Report 2007, Department Of Electrical And Computer Engineering, Michigan Technological University

Department of Electrical and Computer Engineering Annual Reports

• About the Department
• Graduates and Research
• NSF CAREER Award Winner
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Hardware Implementation Of Active Disturbance Rejection Control For Vibrating Beam Gyroscope, David Avanesian

ETD Archive

Obtaining the approximation of rotation rate form a Z-Axis MEMS gyroscope is a challenging problem. Currently, most commercially available MEMS gyroscopes are operating in an open-loop for purposes of simplicity and cost reduction. However, MEMS gyroscopes are still fairly expensive and are not robust during operation. The purpose of this research was to develop a high-performance and low-cost MEMS gyroscope using analog Active Disturbance Rejection Control (ADRC) system. By designing and implementing analog ADRC both above requirements were satisfied. Analog ADRC provides the fastest response time possible (because the circuit is analog), eliminates both internal and external disturbances, and increases …

Byzantine Fault Tolerant Coordination For Web Services Atomic Transactions, Honglei Zhang

ETD Archive

This thesis describes a Byzantine fault tolerant coordination framework for Web services atomic transactions. In the framework, all core services, including transaction activation, registration, completion, and distributed commit, are replicated and protected by Byzantine fault tolerance mechanisms. The traditional two-phase commit protocol is extended by a Byzantine fault tolerant version that can tolerate arbitrary faults on the coordinator and the initiator sides, and some types of malicious faults on the participant side. To achieve Byzantine fault tolerance in an efficient manner, and to limit the types of malicious behaviors of the coordinator, a novel decision certificate is introduced. The decision …

Magnetic Anisotropy And Crystalline Texture In Bao(Fe2o3)(6) Thin Films Deposited On Gan/Al2o3, P. R. Ohodnicki, K. Y. Goh, Y. Hanlumyuang, K. Ramos, M. E. Mchenry, Z. Cai, K. Ziemer, H. Morkoc, N. Biyikli, Z. Chen, C. Vittoria, V. G. Harris

Electrical and Computer Engineering Publications

BaO(Fe2O3)6 (BaM) thin films were deposited by pulsed laser deposition on GaN∕Al2O3 substrates. A pole figure obtained from the (006) reflection indicated that ∼81% of the film volume had the c axis tilted less than 5° from the film normal. A low anisotropy field was inferred from vector coil vibrating sample magnetometer (VVSM) measurements. The reduction in Hafrom literature values and a two-step switching of the easy axis magnetization is postulated to result from interdiffusion and misalignment effects. To alleviate interdiffusion and to improve the c-axis alignment, experiments were repeated with lower deposition temperatures, thinner films, and MgO buffer layers. …

Multilingual Articulatory Features For Speech Recognition, Brian M. Ore

Browse all Theses and Dissertations

Articulatory features describe the way in which the speech organs are used when producing speech sounds. Research has shown that incorporating this information into speech recognizers can lead to an improvement in system performance. The majority of previous work, however, has been limited to detecting articulatory features in a single language. In this thesis, Gaussian Mixture Models (GMMs) and Multi-Layer Perceptrons (MLPs) were used to detect articulatory features in English, German, Spanish, and Japanese. The outputs of the detectors were used to form the feature set for a Hidden Markov Model (HMM)-based phoneme recognizer. The best overall detection and recognition …

An Optimized Macrobending Fiber Based Edge Filter, Pengfei Wang, Gerald Farrell, Qian Wang, Ginu Rajan

Articles

An optimized all-fiber edge filter is developed, based on a one-turn macrobending bare fiber structure. The discrimination range is 16.32 dB over a wavelength range from 1500 to 1600 nm, which can be employed for wavelength measurement applications. It offers a simpler structure compared to the previously developed macrobending fiber loss edge filters, without an increase in the polarization-dependent loss.

Implementation Of A Mems Laboratory Course With Modular, Multidisciplinary Team Projects, S J. Lee, S Gleixner, T R. Hsu, David W. Parent

Faculty Publications

No abstract provided.

Improvement To The Data Logging Capability Of A Cough Monitoring System, Matthew Barlow

Inquiry: The University of Arkansas Undergraduate Research Journal

Data logging capability of a previously developed self contained cough recorder using an accelerometer as the sensing element is improved by using a secure digital memory card for later retrieval on a computer. Firmware is developed to enhance the functionality of the cough recorder. Existing libraries are modified for increased write rates. Increased writing speed allows 8-bit sampling at rates exceeding 8kHz, allowing for detailed time and frequency domain analysis. Additional features have also been developed to enable easy management of recordings, such as a file system compatibility with Microsoft Windows., and unique file names for each recording.

Atmospheric Turbulence Compensation Of Point Source Images Using Asynchronous Stochastic Parallel Gradient Descent Technique On Amos 3.6 M Telescope, Mikhail Vorontsov, Jim F. Riker, Gary W. Carhart, Venkata S. Rao Gudimetla, Leonid A. Beresnev, Thomas Weyrauch

Electrical and Computer Engineering Faculty Publications

The Stochastic Parallel Gradient Descent Technique-based Adaptive Optics (SPGD-AO) system described in this presentation does not use a conventional wavefront sensor. It uses a metric signal collected by a single pixel detector placed behind a pinhole in the image plane to drive three deformable mirrors (DMs). The system is designed to compensate the image for turbulence effects. The theory behind this method is described in detail in [1]. However this technique, while widely simulated and tested in the laboratory, was not yet verified in astronomical field site experiments. During the month of May 2007, a series of experiments with SPGD-AO …

Adaptive Optics Performance Over Long Horizontal Paths: Aperture Effects In Multi-Conjugate Adaptive Optical Systems, Miao Yu, Mikhail Vorontsov, Svetlana Lachinova, Jim F. Riker, Venkata S. Rao Gudimetla

Electrical and Computer Engineering Faculty Publications

We analyze various scenarios of the aperture effects in adaptive optical receiver-type systems when inhomogeneities of the wave propagation medium are distributed over long horizontal propagation path, or localized in a few thin layers remotely located from the receiver telescope pupil. Phase aberration compensation is performed using closed-loop control architectures based on phase conjugation and decoupled stochastic parallel gradient descent (DSPGD) control algorithms. Both receiver system aperture diffraction effects and the impact of wave-front corrector position on phase aberration compensation efficiency are analyzed for adaptive systems with single or multiple wave-front correctors.

Stirling Convertor Control For A Lunar Concept Rover, Gina Blaze

ETD Archive

NASA Glenn Research Center is developing various circuits for a lunar concept rover powered by both a stirling convertor and lithium ion batteries. To begin, a survey of six analog, non-power factor correcting controllers was done for an Advanced Stirling Convertor (ASC) design one was selected to control the stirling convertor. Next, a constant power circuit and lithium ion battery charger was designed, built and tested based on simulation in PSpice. The constant power circuit enables the stirling convertor to maintain a constant power when additional power is required from the batteries

United States Patent Application Publication: System And Method For Sequence Distance Measure For Phylogenetic Tree Construction, K. Sayood, Hasan H. Otu, Steven H. Hinrichs

Department of Electrical and Computer Engineering: Faculty Publications

The present invention permits identification of biological materials following recovery of DNA using standard techniques by comparing a mathematical characterization of the unknown sequence with the mathematical characterization of DNA sequences of known genera and species. The clinical identification of infectious organisms is required for accurate diagnosis and selection of antimicrobial therapeutics. The invention allows an ab initio approach with the potential for rapid identification of biological materials of unknown origin. The approach provides for identification and classification of emergent or new organisms without previous phenotypic identification. The technique may also be used in monitoring situations where the need exists …

A Map Estimator For Simultaneous Superresolution And Detector Nonunifomity Correct, Russell C. Hardie, Douglas R. Droege

Electrical and Computer Engineering Faculty Publications

During digital video acquisition, imagery may be degraded by a number of phenomena including undersampling, blur, and noise. Many systems, particularly those containing infrared focal plane array (FPA) sensors, are also subject to detector nonuniformity. Nonuniformity, or fixed pattern noise, results from nonuniform responsivity of the photodetectors that make up the FPA. Here we propose a maximuma posteriori (MAP) estimation framework for simultaneously addressing undersampling, linear blur, additive noise, and bias nonuniformity. In particular, we jointly estimate a superresolution (SR) image and detector bias nonuniformity parameters from a sequence of observed frames. This algorithm can be applied to video in …

Optimization Of Zonal Wavefront Estimation And Curvature Measurements, Weiyao Zou

Electronic Theses and Dissertations

Optical testing in adverse environments, ophthalmology and applications where characterization by curvature is leveraged all have a common goal: accurately estimate wavefront shape. This dissertation investigates wavefront sensing techniques as applied to optical testing based on gradient and curvature measurements. Wavefront sensing involves the ability to accurately estimate shape over any aperture geometry, which requires establishing a sampling grid and estimation scheme, quantifying estimation errors caused by measurement noise propagation, and designing an instrument with sufficient accuracy and sensitivity for the application. Starting with gradient-based wavefront sensing, a zonal least-squares wavefront estimation algorithm for any irregular pupil shape and size …

Design, Modeling, And Control Of Three-Port Converters For Solar Power Applications, Justin M. Reese

Electronic Theses and Dissertations

This paper describes the results of research into multi-port converter design and control, specifically a pair of three-port topologies based on the half-bridge and full-bridge topologies. These converters are capable of simultaneous and independent regulation of two out of their three ports, while the third port provides the power balance in the system. A dynamic model was developed for each topology to aid in testing and for designing the control loops. The models were then used to design the control structures, and the results were tested in Simulink. In addition, a basic outline of a system level architecture to control …

Advanced Coding And Modulation For Ultra-Wideband And Impulsive Noises, Libo Yang

Electronic Theses and Dissertations

The ever-growing demand for higher quality and faster multimedia content delivery over short distances in home environments drives the quest for higher data rates in wireless personal area networks (WPANs). One of the candidate IEEE 802.15.3a WPAN proposals support data rates up to 480 Mbps by using punctured convolutional codes with quadrature phase shift keying (QPSK) modulation for a multi-band orthogonal frequency-division multiplexing (MB-OFDM) system over ultra wideband (UWB) channels. In the first part of this dissertation, we combine more powerful near-Shannon-limit turbo codes with bandwidth efficient trellis coded modulation, i.e., turbo trellis coded modulation (TTCM), to further improve the …

Modeling,Design,And Characterization Of Monolithic Bi-Directional Power Semiconductor Switch, Yue Fu

Electronic Theses and Dissertations

Bidirectional power switching devices are needed in many power management applications, particularly in lithium-ion battery protection circuitry. A monolithic bidirectional power switch fabricated with a simplified CMOS technology is introduced in this dissertation. Throughout the design process, ISE TCAD tool plays an important role. Design variables are carefully analyzed to improve the device performance or yield the best trade off. Optimization is done with the help of TCAD simulation and theoretical calculations. The device has been successfully fabricated using simplified 0.5 micron CMOS process. The experimental result shows a breakdown voltage of 25V. Due to the interdigitated source to source …

Integrated Topologies And Digital Control For Satellite Power Management And Distribution Systems, Hussam Al-Atrash

Electronic Theses and Dissertations

This work is focused on exploring advanced solutions for space power management and distribution (PMAD) systems. As spacecraft power requirements continue to increase, paralleled by the pressures for reducing cost and overall system weight, power electronics engineers will continue to face major redesigns of the space power systems in order to meet such challenges. Front-end PMAD systems, used to interface the solar sources and battery backup to the distribution bus, need to be designed with increased efficiency, reliability, and power density. A new family of integrated single-stage power converter structures is introduced here. This family allows the interface and control …