Digital Commons Network^™

Nesting Forward-Mode Ad In A Functional Framework, Jeffrey M. Siskind, Barak A. Pearlmutter

Department of Electrical and Computer Engineering Technical Reports

We discuss the augmentation of a functional-programming language with a derivative- taking operator implemented with forward-mode automatic differentiation (AD). The primary technical difficulty in doing so lies in ensuring correctness in the face of nested invocation of that operator, due to the need to distinguish perturbations introduced by distinct invocations. We exhibit a series of implementations of a referentially- transparent forward-mode-AD derivative-taking operator, each of which uses a different non-referentially-transparent mechanism to distinguish perturbations. Even though the forward-mode-AD derivative-taking operator is itself referentially transparent, we hypothesize that one cannot correctly formulate this operator as a function definition in current pure …

Influence Of Phonon Scattering On The Performance Of P-I-Np-I-N Band-To-Band Tunneling Transistors, Siyuranga O. Koswatta, Mark S. Lundstrom, Dmitri E. Nikonov

Department of Electrical and Computer Engineering Faculty Publications

Power dissipation has become a major obstacle in performance scaling of modern integrated circuits and has spurred the search for devices operating at lower voltage swing. In this letter, we study p-i-n band-to-band tunneling field effect transistors taking semiconducting carbon nanotubes as the channel material. The on current of these devices is mainly limited by the tunneling barrier properties, and phonon-scattering has only a moderate effect.We show, however, that the off current is limited by phonon absorption assisted tunneling, and thus is strongly temperature dependent. Subthreshold swings below the 60 mV/decade conventional limit can be readily achieved even at room …

Inversion Capacitance-Voltage Studies On Gaas Metal-Oxide-Semiconductor Structure Using Transparent Conducting Oxide As Metal Gate, T. Yang, Y. Liu, P. D. Ye, Y. Xuan, H. Pal, Mark S. Lundstrom

Department of Electrical and Computer Engineering Faculty Publications

A systematic capacitance-voltage C-V study has been performed on GaAs metaloxide- semiconductor MOS structures with atomic-layer-deposited Al2O3 as gate dielectrics and indium tin oxide ITO as the metal gate. The transparent conducting ITO gate allows homogeneous photoillumination on the whole MOS capacitance area, such that one can easily observe the low-frequency LF C-V and quasistatic C-V of GaAs at room temperature. The semiconductor capacitance effect on GaAs MOS devices has also been identified and insightfully discussed based on the obtained LF C-V curves. The semiconductor capacitance effect becomes more important for devices with high-mobility channel materials and aggressively scaled high-k …

Inferring Undesirable Behavior From P2p Traffic Analysis, Ruben Torres, Mohammad Hajjat, Sanjay G. Rao, Marco Mellia, Maurizio Munafo

Department of Electrical and Computer Engineering Technical Reports

ABSTRACT While peer-to-peer (P2P) systems have emerged in popularity in recent years, their large-scale and complexity make them difficult to reason about. In this paper, we argue that systematic analysis of traffic characteristics of P2P systems can reveal a wealth of information about their behavior, and highlight potential undesirable activities that such systems may exhibit. As a first step to this end, we present an offline and semi-automated approach to detecting undesirable behavior. Our analysis is applied on real traffic traces collected from a Point-of-Presence (PoP) of a national-wide ISP in which over 70% of the total traffic is due …

Design, Implementation And Evaluation Of A Networking Context Aware Policy Environment, Asanga Dhammika Udugama

Theses

Future mobile networks are anticipated to have support to access heterogeneous access technologies. An important question in such environments is the decisions on when to use what access network. These decisions must take the users and mobile network operators’ perspectives into consideration. The operators usually have a focus of always-best-managed networks while the users have an always-best-connected focus. A key enabler of such environments is the use of policies to perform these handover decisions. These policies, which must be dynamic in nature, should be configurable when the requirements change. Policy decisions are always made based on the current context of …

Real-Time Hilbert Transform And Autocorrelation For Digital Wideband Communication Applications, Murthy, Dilip Srinivasa

Browse all Theses and Dissertations

Digital wideband receiver plays a key role in communication and radar systems, and it is used detect and analyze wide range of radio frequency (RF) signals. A digital Instantaneous Frequency Measurement (IFM) receiver is designed, where implementation of a real-time architecture of a Hilbert transform and autocorrelation algorithm is presented. Real-time architecture performs continuous monitoring and processing of the incoming signal. Prior to the previous one bit design, the input data fed to the Hilbert transform is 8-bit wide at a clock rate of 320 MHz with the input data rate is increased by a factor of eight, an 8-bit …

Simultaneous Rf/Eo Tracking And Characterization Of Dismounts, Jason M. Blackaby

Browse all Theses and Dissertations

This thesis discusses the fusion of radar frequency(RF) data and electro-optical (EO) data for tracking and characterization of dismounts (i.e., humans). Each of these sensor modalities provides unique information about the location, structure, and movement of a dismount. The person's location is tracked on the 2D ground plane using RF data for range measurements and EO data for angle measurements. Using this information, measurements are made on the structure and dynamic motion (gait) of the person. An imaging approach is used to create spatio-temporal activity maps along with a three-dimensional reconstruction of the dismount.

Intelligent Spectrum Sensor Radio, Omer Mian

Browse all Theses and Dissertations

A cognitive radio is a radio with built-in intelligence that makes it able to utilize the radio frequency spectrum more efficiently by adapting to the changing conditions and frequency availability. In this thesis a spectrum sensor radio is designed that detects transmissions in FM band and determine the range of used and unused frequencies within the band. The radio then starts a transmission on a frequency among the available frequencies. This intelligent radio system design is implemented using the Universal Software Radio Peripheral and GNU Radio with a program written in python that uses a number of GNU Radio modules …

Fpga Design Of A Hardware Efficient Pipelined Fft Processor, Ryan T. Bone

Browse all Theses and Dissertations

Digital receivers involve fast Fourier transform (FFT) computations that require a large amount of arithmetic operations. The implementation of a FFT processor is one of the most challenging parts in the realization of a wideband receiver and its hardware complexity is very high. Hence, kernel function FFT processors have been proposed to meet real-time processing requirements and to reduce hardware complexity by rounding the kernel function to predetermined kernel points so as to eliminate the multipliers and use only shifters and adders or subtractors. Because of the nonlinear nature of this approximation by the rounding errors, spurious responses are generated …

Implementation Of Null Conventional Logic In Cots Fpga's, Mohamad Rajgara

Browse all Theses and Dissertations

The digital world has been dominated by the growth of synchronous digital design techniques for last few decades. Traditional Boolean logic is symbolically incomplete since it has a separate control logic, time in the form of clock signal which be carefully integrated with the logic design, but with digital clock signal already in the GHz range, this integration is further complicated. One approach to address post GHz digital logic design is to use clockless or asynchronous digital design techniques. In the mid '90s Theaseus Logic Inc. proposed a method to design Asynchronous circuits using Null Convention Logic (NCL).This thesis introduces …

Design Of A High-Speed Architecture For Stabilization Of Video Captured Under Non-Uniform Lighting Conditions, Ming Zhu Zhang

Electrical & Computer Engineering Theses & Dissertations

Video captured in shaky conditions may lead to vibrations. A robust algorithm to immobilize the video by compensating for the vibrations from physical settings of the camera is presented in this dissertation. A very high performance hardware architecture on Field Programmable Gate Array (FPGA) technology is also developed for the implementation of the stabilization system. Stabilization of video sequences captured under non-uniform lighting conditions begins with a nonlinear enhancement process. This improves the visibility of the scene captured from physical sensing devices which have limited dynamic range. This physical limitation causes the saturated region of the image to shadow out …

A Novel Expanded 16-Dimensional Constant Envelope Q2psk Constellation, Milton I. Quinteros, Kenneth V. Cartwright, Edit J. Kaminsky, Ricardo U. Gallegos

Electrical Engineering Faculty Publications

We introduce a 16-dimensional constant-amplitude constellation that is generated by concatenating either four constant envelope quadrature-quadrature phase shift keying (CEQ2PSK) symbols from Saha and Birdsall or four CEQ2PSK symbols recently discovered by Cartwright and also introduced here. Our new constellation doubles the number of points available for data transmission without decreasing the distance between points or increasing energy, and may therefore be used in a trellis coded modulation (TCM) system without constellation expansion penalty. Because the new constellation has constant envelope, the modulation scheme becomes very attractive for nonlinear channels such as the magnetic recording channel or the satellite channel …

Stranded Core Transformer Loss Analysis, Xingxing Zhang

University of Kentucky Master's Theses

We will present the approaches used to investigating the power loss for the stranded core transformers. One advantage of using stranded core is to reduce power loss or enhance transformer efficiency. One difficulty in the modeling of this type of transformer is that the core is not solid (there are small gaps between core wires due to circular cross section). A two dimensional finite element method with nodal basis function for magnetostatic field was developed to study the effects of the small gaps between core wires. The magnetic flux densities are compared for the uniform (solid) cores and the stranded …

Hdl Implementation And Analysis Of A Residual Register For A Floating-Point Arithmetic Unit, Akil Kaveti

University of Kentucky Master's Theses

Processors used in lower-end scientific applications like graphic cards and video game consoles have IEEE single precision floating-point hardware [23]. Double precision offers higher precision at higher implementation cost and lower performance. The need for high precision computations in these applications is not enough to justify the use double precision hardware and the extra hardware complexity needed [23]. Native-pair arithmetic offers an interesting and feasible solution to this problem. This technique invented by T. J. Dekker uses single-length floating-point numbers to represent higher precision floating-point numbers [3]. Native-pair arithmetic has been proposed by Dr. William R. Dieter and Dr. Henry …

Super Resolution 3d Scanning Using Spatial Light Modulator And Band Correction, Akshay Pethe

University of Kentucky Master's Theses

Multi Frequency Phase Measuring Profilometry is the most popular lateral contact 3-D Scanning technique. The Phase Measuring Profilometry is limited in resolution by the projector and cameras used. Conventional signal projectors have a maximum of 2000 to 4000 scan lines limiting the projector resolution. To obtain greater detail with higher resolution the PMP technique is applied to a Spatial Light Modulator (SLM) having 12000 lines, very large as compared to conventional projectors. This technology can achieve super resolution scans having varied applications. Scans achieved from PMP suffer from a certain type of artifact called “banding” which are periodic bands across …

Full-Wave Finite-Difference Time-Domain Simulation Of Electromagnetic Cloaking Structures, Yan Zhao, Christos Argyropoulos, Yang Hao

Department of Electrical and Computer Engineering: Faculty Publications

This paper proposes a radial dependent dispersive finitedifference time-domain method for the modeling of electromagnetic cloaking structures. The permittivity and permeability of the cloak are mapped to the Drude dispersion model and taken into account in dispersive FDTD simulations. Numerical simulations demonstrate that under ideal conditions, objects placed inside the cloak are ‘invisible’ to external electromagnetic fields. However for the simplified cloak based on linear transformations, the back scattering has a similar level to the case of a PEC cylinder without any cloak, rendering the object still being ‘visible’. It is also demonstrated numerically that the simplified cloak based on …

Average Min-Sum Decoding Of Ldpc Codes, Nathan Axvig, Deanna Dreher, Katherine Morrison, Eric T. Psota, Lance C. Pérez, Judy L. Walker

Department of Mathematics: Faculty Publications

Simulations have shown that the outputs of minsum (MS) decoding generally behave in one of two ways: the output either eventually stabilizes at a codeword or eventually cycles through a finite set of vectors that may include both codewords and non-codewords. This inconsistency in MS across iterations has significantly contributed to the difficulty in studying the performance of this decoder. To overcome this problem, a new decoder, average min-sum (AMS), is proposed; this decoder outputs the average of the min-sum output vectors over a finite set of iterations. Simulations comparing MS, AMS, linear programming (LP) decoding, and maximum likelihood (ML) …

Development Of Fiber Bend Loss Edge Filter, Pengfei Wang

Doctoral

This PhD thesis addresses several aspects of macrobending loss in single-mode optical fibers. The context for the work is the development of an edge filter for a rapid wavelength measurement system. Based on scalar approximation theory and the beam propagation method, a simulation platform is developed and used to predict the macrobending loss of singlemode fiber with single or multiple coating layers. A single-mode step index fiber macrobending loss edge filter is investigated theoretically in terms of baseline loss, discrimination range and polarization dependent loss (PDL). The theoretical analysis is supported by a range of experimental investigations and results. The …

A Comparison Of Filtering Approaches For Aircraft Engine Health Estimation, Daniel J. Simon

Electrical and Computer Engineering Faculty Publications

Different approaches for the estimation of the states of linear dynamic systems are commonly used, the most common being the Kalman filter. For nonlinear systems, variants of the Kalman filter are used. Some of these variants include the LKF (linearized Kalman filter), the EKF (extended Kalman filter), and the UKF (unscented Kalman filter). With the LKF and EKF, performance varies depending on how often Jacobians (partial derivative matrices) are updated. In other words, we see a tradeoff between computational effort and filtering performance. With the unscented Kalman filter, Jacobians are not calculated but computational effort is typically high due to …

Ultrashort Laser Pulse Interaction With Photo-Thermo-Refractive Glass, Leo Siiman

Electronic Theses and Dissertations

Photo-thermo-refractive (PTR) glass is an ideal photosensitive material for recording phase volume holograms. It is a homogeneous multi-component silicate glass that demonstrates all the advantages of optical glass: thermal stability, high laser damage threshold, and a wide transparency range. Moreover the ability to record phase patterns (i.e. spatial refractive index variations) into PTR glass has resulted in the fabrication of volume holograms with diffraction efficiency greater than 99%. The conventional method of recording a hologram in PTR glass relies on exposure to continuous-wave ultraviolet laser radiation. In this dissertation the interaction between infrared ultrashort laser pulses and PTR glass is …

Cholesteric Liquid Crystal Photonic Crystal Lasers And Photonic Devices, Ying Zhou

Electronic Theses and Dissertations

This dissertation discusses cholesteric liquid crystals (CLCs) and polymers based photonic devices including one-dimensional (1D) photonic crystal lasers and broadband circular polarizers. CLCs showing unique self-organized chiral structures have been widely used in bistable displays, flexible displays, and reflectors. However, the photonic band gap they exhibit opens a new way for generating laser light at the photonic band edge (PBE) or inside the band gap. When doped with an emissive laser dye, cholesteric liquid crystals provide distributed feedback so that mirrorless lasing is hence possible. Due to the limited surface anchoring, the thickness of gain medium and feedback length is …

Extended Focus Range High Resolution Endoscopic Optical Coherence Tomography, Kye-Sung Lee

Electronic Theses and Dissertations

Today, medical imaging is playing an important role in medicine as it provides the techniques and processes used to create images of the human body or parts thereof for clinical purposes (medical procedures seeking to reveal, diagnose or examine disease) or medical science (including the study of normal anatomy and function). Modalities are developing over time to achieve the highest possible resolution, speed of image acquisition, sensitivity, and specificity. In the past decade, advances in optics, fiber, as well as laser technology have enabled the development of noninvasive optical biomedical imaging technology that can also be applied to endoscopy to …

Electrical And Computer Engineering Research Report 2008, Department Of Electrical And Computer Engineering, Michigan Technological University

Department of Electrical and Computer Engineering Annual Reports

• Department
• Research
• New Chair
• Publications
• Enterprise

Distance Relaying Algorithm For Double-Circuit Transmission Line With Compensation For Reactance Effect Under Standard Availability Of Measurements, Jan Izykowski, Marcin Bozek

Turkish Journal of Electrical Engineering and Computer Sciences

This paper deals with non-pilot distance protection of a double-circuit transmission line. Negative impact of the reactance effect, appearing in measuring a fault loop impedance, on operation of the relay is discussed. An adaptive algorithm allowing one to prevent the relay from mis- or mal-operation caused by the reactance effect is introduced. The algorithm is designed for a standard availability of measurements from one end of the double-circuit line, i.e. when three-phase voltage and current from the faulted line circuit, and additionally zero-sequence current from the healthy line circuit, are provided as the relay input signals. The algorithm is based …

From Engineering Electromagnetics To Electromagnetic Engineering: Using Computational Electromagnetics For Synthesis Problems, Anton G. Tijhuis, Martijn C. Van Beurden, Bastiaan P. De Hon, Hubregt J. Visser

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a two-stage approach is proposed for using computational electromagnetics in antenna engineering. First, stochastic optimization techniques are used in combination with approximate models. Second, line-search techniques are combined with full-wave modeling. For the first stage, we show an illustrative example. The second stage is considered in detail; both the acceleration of the underlying field computations and the implementation of the optimization are discussed.

A Macro-Bend Fiber Based Wavelength Demodulation System For Optical Fiber Sensing Applications, Ginu Rajan

Doctoral

This thesis considers the design and development of a wide range all fiber interrogation system with a rapid measurement capability for extracting reliable measure and information from fiber Bragg grating sensors. Existing passive and active interrogation systems have certain limitations and do not satisfy all requirements. In this thesis a wavelength demodulation system is proposed, based on a macro-bend fiber filter employed in a ratiometric detection scheme. A theoretical model and analysis of an edge filter based ratiometric wavelength measurement (RWM) system is presented. A fiber edge filter is realized by carefully selecting an appropriate bend radius and number of …

Evaluation Of An Image Processing Algorithm For Scene Change Detection, Daniel Flores

Open Access Theses & Dissertations

Despite the efforts to reduce traffic accidents by government entities and automobile manufactures, the numbers of accidents are not considerably reduced. An evaluation of an algorithm based on the fly's eye is done on this research applying its principles to detect scene change on images for printed circuit boards providing initial steps to implement this algorithm on vehicular traffic to keep track of objects moving on the field for collision avoidance purposes. The effectiveness of the algorithm is addressed through a comparison of its performance with that found in experimental data.

Modular Fast Direct Analysis Using Non-Radiating Local-Global Solution Modes, Xin Xu

University of Kentucky Doctoral Dissertations

This dissertation proposes a modular fast direct (MFD) analysis method for a class of problems involving a large fixed platform region and a smaller, variable design region. A modular solution algorithm is obtained by first decomposing the problem geometry into platform and design regions. The two regions are effectively detached from one another using basic equivalence concepts. Equivalence principles allow the total system model to be constructed in terms of independent interaction modules associated with the platform and design regions. These modules include interactions with the equivalent surface that bounds the design region. This dissertation discusses how to analyze (fill …

Can Laser Speckle Flowmetry Be Made A Quantitative Tool?, Donald D. Duncan, Sean J. Kirkpatrick

Electrical and Computer Engineering Faculty Publications and Presentations

The ultimate objective of laser speckle flowmetry (and a host of specific implementations such as laser speckle contrast analysis, LASCA or LSCA; laser speckle spatial contrast analysis, LSSCA; laser speckle temporal contrast analysis, LSTCA; etc.) is to infer flow velocity from the observed speckle contrast. Despite numerous demonstrations over the past 25 years of such a qualitative relationship, no convincing quantitative relationship has been proven. One reason is a persistent mathematical error that has been propagated by a host of workers; another is a misconception about the proper autocorrelation function for ordered flow. Still another hindrance has been uncertainty in …

A Highly Reliable Non-Volatile File System For Small Satellites, Rama Krishna Nimmagadda

University of Kentucky Master's Theses

Recent Advancements in Solid State Memories have resulted in packing several Giga Bytes (GB) of memory into tiny postage stamp size Memory Cards. Of late, Secure Digital (SD) cards have become a de-facto standard for all portable handheld devices. They have found growing presence in almost all embedded applications, where huge volumes of data need to be handled and stored.

For the very same reason SD cards are being widely used in space applications also. Using these SD Cards in space applications requires robust radiation hardened SD cards and Highly Reliable Fault Tolerant File Systems to handle them. The present …