Engineering Commons^™

Deep Centers In A Free-Standing Gan Layer, Z.-Q. Fang, D. C. Look, P. Visconti, D.-F. Wang, C.-Z. Lu, F. Yun, Hadis Morkoç, S. S. Park, K. Y. Lee

Electrical and Computer Engineering Publications

Schottky barrierdiodes, on both Ga and N faces of a ∼300-μm-thick free-standing GaN layer, grown by hydride vapor phase epitaxy(HVPE) on Al2O3 followed by laser separation, were studied by capacitance–voltage and deep level transient spectroscopy(DLTS) measurements. From a 1/C2 vs V analysis, the barrier heights of Ni/Au Schottky contacts were determined to be different for the two polar faces: 1.27 eV for the Ga face, and 0.75 eV for the N face. In addition to the four common DLTS traps observed previously in other epitaxial GaN including HVPE-grown GaN a new trap B′ with activation energyET=0.53 eV was found in …

Blue Photoluminescence Activated By Surface States In Gan Grown By Molecular Beam Epitaxy, Michael A. Reshchikov, P. Visconti, Hadis Morkoç

Electrical and Computer Engineering Publications

We have studied the broad blue band, which emerges in the photoluminescence(PL)spectrum of c-plane GaN layers after etching in hot H3PO4 and subsequent exposure to air. This band exhibited a 100 meV blueshift with increasing excitation intensity and a thermal quenching with activation energies of 12 and 100 meV. These observations led us to suggest that surface states may be formed on etchedsurfaces and cause bandbending, which leads to a shift in transition energy with excitation. The blue PL is related to transitions from the shallow donors filled with nonequilibrium electrons to the surface states, which capture the photogenerated …

A Software Defined Radio Platform With Direct Conversion: Soprano, Shinichiro Haruyama, Robert H. Morelos-Zaragoza

Faculty Publications

A new software defined radio platform with multiport-based direct conversion is proposed, named SOPRANO (Software Programmable and Hardware Reconfigurable Architecture for Network). The main features of SOPRANO are a high-level design methodology for digital circuits, a new mixer-less direct conversion method, and software algorithms for multi-band and multi-mode operation. We built the first prototype SOPRANO 1.0, which was able to receive PSK and QAM signals with two different carrier frequencies at 2.45 GHz and 5.25 GHz by changing signal processing software.

Microelectronics Process Engineering: A Non-Traditional Approach To Ms&E (Ingeniería De Procesos Microelectrónicos: Un Acercamiento No Tradicional A La Ciencia De Materiales E Ingeniería), E. Allen, Stacy H. Gleixner, G. Young, David W. Parent, Yasser Dessouky, L. Vanasupa

Faculty Publications

Materials Science and Engineering straddles the fence between engineering and science. In order to produce more work-ready undergraduates, we offer a new interdisciplinary program to educate materials engineers with a particular emphasis on microelectronics-related manufacturing. The bachelor's level curriculum in Microelectronics Process Engineering (J1ProE) is interdisciplinary, drawing from materials, chemical, electrical and industrial engineering programs and tied together with courses, internships and projects which integrate thin film processing with manufacturing control methods. Our graduates are prepared for entry level engineering jobs that require knowledge and experience in microelectronics-type fabrication and statistics applications in manufacturing engineering. They also go on to …

A Wideband Monopole For Reconfigurable Multiband Radio Terminals, Max Ammann

Conference papers

A wideband planar monopole employing two broadbanding techniques is investigated, and is shown to yield an impedance bandwidth ratio of 10:1 or greater for a return loss of 8 dB. The radiation pattern bandwidth is also investigated

Giant Photoresistivity And Optically Controlled Switching In Self-Assembled Nanowires, N. Kouklin, L. Menon, A. Z. Wong, D. W. Thompson, J. A. Woollam, P. F. Williams, Supriyo Bandyopadhyay

Electrical and Computer Engineering Publications

We report the observation of giant photoresistivity in electrochemically self-assembledCdS and ZnSenanowireselectrodeposited in a porous alumina film. The resistance of these nanowires increases by one to two orders of magnitude when exposed to infrared radiation, possibly because of real-space transfer of electrons from the nanowires into the surrounding alumina by photon absorption. This phenomenon has potential applications in “normally on” infrared photodetectors and optically controlled switches.

On Interference Cancellation And Iterative Techniques, Ryuji Kohno, Robert H. Morelos-Zaragoza

Faculty Publications

Recent research activities in the area of mobile radio communications have moved to third generation (3G) cellular systems to achieve higher quality with variable transmission rate of multimedia information. In this paper, an overview is presented of various interference cancellation and iterative detection techniques that are believed to be suitable for 3G wireless communications systems. Key concepts are space-time processing and space-division multiple access (or SDMA) techniques. SDMA techniques are possible with software antennas. Furthermore, to reduce receiver implementation complexity, iterative detection techniques are considered. A particularly attractive method uses tentative hard decisions, made on the received positions with the …

A Method Of Implementing The Interleaver In 3g Wireless Communication Systems For Randomization Of Burst Errors, Eric Duquette

Inquiry: The University of Arkansas Undergraduate Research Journal

In less than a year or two, third generation ( 3G) wireless communication systems will be replacing the currently existing second generation (2G) wireless systems and be used worldwide. The 3G systems will have a higher data transfer capacity, which allows for simultaneous data, voice, and video transfer (e.g., multimedia applications) while most of 2G systems only allow for low-rate data and voice transfer. The wireless communications industry has set standards for 3G, which detail various operations of the technology. It should be noted that the 3G standards outline only the different operations and not the processes for the production …

Development Of A Building Electrical Power Systems Design Specialty, Glenn T. Wrate

Conference Papers in Published Proceedings

Enrollment in Electrical Power Engineering courses has been in a steady decline, and many institutions have dropped power and energy conversion courses. At the same time, the demand for engineers in the field has remained constant, and in some cases has increased significantly. To meet the demand for engineers in the electrical construction sector, the Milwaukee School of Engineering and local industry have worked together to develop a sequence of courses for a Building Electrical Power Systems Design Specialty in the Architectural Engineering program. This sequence includes four courses from the Electrical Engineering and Computer Science Department: Electrical Systems, and …

A Two-Stage Decoder For Pragmatic Trellis-Coded M-Psk Modulation Using A Symbol Transformation, Robert H. Morelos-Zaragoza, Advait Mogre

Faculty Publications

A two-stage decoding procedure for pragmatic trellis-coded modulation (TCM) is introduced. It applies a transformation from the received I-channel and Q-channel samples onto points in a two-dimensional (2-D) signal space that contains a coset constellation. For pragmatic TCM over M-PSK signal sets with ν coded bits per symbol, ν=1, 2, the signal points in the coset constellations represent cosets of a B/QPSK signal subset-associated with the coded bits-in the original M-PSK signal constellation. A conventional Viterbi decoder operates on the transformed symbols to estimate the coded bits. After reencoding these bits, the uncoded bits are estimated in a second stage, …

A Method Of Non-Data-Aided Carrier Recovery With Modulation Identification, Robert H. Morelos-Zaragoza, Kenta Umebayashi, Ryuji Kohno

Faculty Publications

A non-data aided carrier recovery technique using modulation format identification is proposed. This technique can also be interpreted as a modulation identification method that is robust against static phase and frequency offsets. The performance of the proposed technique is studied and analytical expressions derived for the mean acquisition time to detect lock in the cases of M-PSK, M=2,4,8, and 16-QAM modulation, with respect to frequency offset and signal-to-noise ratio. The results are verified with Monte Carlo simulations. The main advantage of the proposed method lies in its simpler implementation and faster lock detection, when compared to conventional methods.

Flowers For The World: Developing A Business Game To Support The Teaching Of Is Concepts, Trevor T. Moores, Jerry Cha-Jan Chang

Management, Entrepreneurship and Technology Faculty Research

One of the key problems in teaching fundamental concepts in information systems is how to ground the theory in experiences that the students can relate to. To overcome this problem, a business game called Flowers For The World has been developed and used across a wide variety of IS courses. This paper will describe the game and the result of using it for a 300-level course in analysis and design. The possibility exists that the game could be developed to provide a common business foundation across all business school curricula.

Scanner Parameter Estimation Using Bilevel Scans Of Star Charts, Elisa H. Barney Smith

Electrical and Computer Engineering Faculty Publications and Presentations

Scanning a high contrast image in bilevel mode results in image degradation. This is caused by two primary effects: blurring and thresholding. This paper expands on a method of estimating a joint distortion parameter, called the edge spread, from a star sector test chart in order to calculate the values of the point spread function width and binarization threshold. This theory is also described for variations in the source pattern which can represent degradations caused by repetition of the bilevel process as would be seen in printing then scanning, or in repeated photocopying. Estimation results are shown for the basic …

Rules For A Cellular Automaton To Model Quantum-Dot Cellular Automata, Teresa Cole, John C. Lusth

Electrical and Computer Engineering Faculty Publications and Presentations

Quantum-dot cellular automata are one of several new device architectures whose operation is based on local interactions, much like cellular automata. We have implemented several rule sets for a cellular automaton that could be used to model the behavior of quantum-dot cellular automata and used them to test most of the wire and gate configurations proposed for these devices. Arrangements of cells for which any particular cell has neighbors which are not adjacent to each other generally behave as expected. Unfavorable arrangements of cells such as those with bends and crosses tend to either have incorrect outputs or be unstable …

Design And Applications Of Volume Holographic Optical Elements, Steven C. Dunn

Retrospective Theses and Dissertations

Volume gratings were studied both theoretically and experimentally in order to design and analyze practical volume holographic optical elements. The diffraction of finite (Gaussian) beams by transmission gratings is investigated. A closed form solution for the off-Bragg profiles is obtained, and the distortion in the resulting profiles is analyzed. Criteria for when the finiteness of the beam has a minimal effect on the angular selectivity response are given. A model is developed to investigate the cross talk in multiplexed gratings Experimental verification in LiNb0₃ and PTR glass is demonstrated. The diffraction efficiency and output profiles of finite beams diffracted …

Cationic Surfactant Mediated Hybridization And Hydrophobization Of Dna Molecules At The Liquid/Liquid Interface And Their Phase Transfer, Murali Sastry, Ashavani Kumar, Mrunalini Pattarkine, Vidya Ramakrishnan, Krishna N. Ganesh

Faculty Works

Hybridization of complementary oligonucleotides mediated by a cationic surfactant at the water/hexane interface leads to hydrophobic, double-helical DNA which may be readily phase transferred to the organic phase and cast into thin films on solid substrates.

Experimental Investigation Of Performance Of A Single Phase Upqc For Voltage Sensitive And Non-Linear Loads, Malabika Basu, S. P. Das, Gopal K. Dubey

Conference papers

A unified power quality conditioner (UPQC) is proposed in this paper. It protects the consumer at the load end from supply voltage sag, and provides unity power factor condition at the utility for different values of load power factor. A PC-based closed loop control scheme is proposed and experimental investigation is carried out in the laboratory. Selected experimental results are reported along with control circuit and phasor diagram to validate the proposition.

Low Voltage Regulator Modules And Single Stage Front-End Converters, Wei Gu

Retrospective Theses and Dissertations

Evolution in microprocessor technology poses new challenges for supplying power to these devices. To meet demands for faster and more efficient data processing, modem microprocessors are being designed with lower voltage implementations. More devices will be packed on a single processor chip and the processors will operate at higher frequencies, exceeding 1GHz. New high-performance microprocessors may require from 40 to 80 watts of power for the CPU alone. Load current must be supplied with up to 30A/µs slew rate while keeping the output voltage within tight regulation and response time tolerances. Therefore, special power supplies and Voltage Regulator Modules (VRMs) …

Cubic Hamiltonian Graphs And Generalized Knight's Tours, Siew Hui Ong

Student Works (2000-2009)

This thesis is divided into two parts, both related to hamiltonian graphs. The first part deals with 3-connected cubic bipartite planar graphs. By assuming that all 3-connected cubic bipartite planar graphs are hamiltonian, lower bounds for the number of Hamilton cycles in cubic bipartite planar graphs with given cyclic connectivity are obtained in Chapter 2. In Chapter 3, we show that Barnette's Conjecture is equivalent to the conjecture which states that for any two edges x and y on the same face of a 3-connected cubic bipartite planar hamiltonian graph, there is a Hamilton cycle passing through x and y1 …

Vhdl Implementation For Jawi Character Recognition, Mustafa Norita Adila

Student Works (2000-2009)

Kewujudan tulisan jawi sejak dahulu lagi telah menghasilkan pelbagai karya penting dalam perkembangan islam. Sebagai satu bahasa pengantara, tulisan jawi dianggap penting dalam bidang penulisan. Tidak terhad hanya kepada buku-buku, dokumen-dokumen dan manuskrip-manuskrip yang ditulis dalam tulisan jawi, malah penggunaanya amat meluas dan meliputi keseluruhan bidang. Menyedari kepentingannya, timbul minat saya untuk mengkaji dengan lebih mendalam bagaimana komputer boleh mengenali dan memahami tulisan ini tanpa menggunakan tenaga manusia berdasarkan kepada beberapa kajian yang sedia ada yang telah dijalankan oleb mereka yang pakar dalam teknologi komputer digital. Secara keseluruhan, kajian ini akan membantu memudahkan lagi pengecaman tulisan tangan jawi yang dilakukan …

Optical Coherent Communication System Using Phase Shift Keying, Syed Javaid Iqbal

Student Works (2000-2009)

This thesis presents the experimental study and design of a coherent communication system by using phase shift keying (PSK). Systems are designed by using all passive elements, which make the system very easy to operate, and less maintenance is required. All the PSK designs are based on a single light source. In this thesis there are five different types of PSK with a single light source communication systems are designed. All designs are experimentally tested in free space. The systems are • All optical two-channel PSK communication system, by using single light source, "All optical single channel, two-way PSK communication, …

Analysis And Synthesis Of Primary Side Cycle By Cycle Control Of Isolated Flyback Converters, Radoslaw Nalepa

Theses

This work presents the analysis and design of an isolated flyback converter, without feedback from the load side. The converter is controlled from the primary side using the switch voltage and innovative control circuit topologies.

A detail study of the flyback circuit is undertaken including all known parasitics. Besides the standard parasitics, for example the capacitor resistive effect, other more subtle effects are included in the model development such as inter coil couplingj source capacitance etc. Development of these models has provided information about circuit simplifications without losing accuracy of the model. As a consequence of this model development, it …

Remote Monitoring System, Chin Kee Tan

Student Works (2000-2009)

Research is conducted to analysis and evaluate about the Remote Monitoring System. The details process of developing the Remote Monitoring System will be discussed throughout whole section of this project. The primary objective of this project is to explore on how Remote Monitoring CCTV process work as well as the application area used in Remote Monitoring CCTV system. This project involves creating a real time monitoring video camera system as a prototype. The developer will perform the development of the system according to system development life cycle. Stages of the system development life cycle for developing the remote monitoring software …

Study Of Dynamics And Mechanism Of Metal-Induced Silicon Growth, Elena A. Guliants, Wayne A. Anderson

Electrical and Computer Engineering Faculty Publications

The present study addresses the mechanism of metal-induced growth of device-quality silicon thin films. Si deposition was performed by magnetron sputtering on a 25-nm-thick Ni prelayer at 525–625 °C and yielded a continuous, highly crystalline film with a columnar structure. A Ni disilicide intermediate layer formed as a result of the Ni reaction with Si deposit provides a sufficient site for the Si epitaxial growth because lattice mismatch is small between the two materials. The reaction between Ni and Si was observed to progress in several stages. The NixSiy phase evolution in a Ni:Si layer was studied by x-ray photoelectron …

Resonant Energy Transfer From Argon Dimers To Atomic Oxygen In Microhollow Cathode Discharges, M. Moselhy, R. H. Stark, K. H. Schoenbach, U. Kogelschatz

Bioelectrics Publications

The emission of atomic oxygen lines at 130.2 and 130.5 nm from a microhollow cathode discharge in argon with oxygen added indicates resonant energy transfer from argon dimers to oxygen atoms. The internal efficiency of the vacuum-ultraviolet (VUV) radiation was measured as 0.7% for a discharge in 1100 Torr argon with 0.1% oxygen added. The direct current VUV point source operates at voltages below 300 V and at current levels of milliamperes.

Self-Consistent Simulations Of Electroporation Dynamics In Biological Cells Subjected To Ultrashort Electrical Pulses, R. P. Joshi, Q. Hu, R. Aly, K. H. Schoenbach, H. P. Hjalmarson

Bioelectrics Publications

The temporal dynamics of electroporation of cells subjected to ultrashort voltage pulses are studied based on a coupled scheme involving the Laplace, Nernst-Plank, and Smoluchowski equations. A pore radius dependent energy barrier for ionic transport, accounts for cellular variations. It is shown that a finite time delay exists in pore formation, and leads to a transient overshoot of the transmembrane potential V_mem beyond 1.0 V. Pore resealing is shown to consist of an initial fast process, a 10⁻⁴s delay, followed by a much slower closing at a time constant of about 10 ⁻¹s. This establishes a …

Comparison Of Two B-Polynomial Methods: Application To The Identification Of Time Delayed Processes, Ruiyao Gao, Aidan O'Dwyer

Conference papers

An extensive literature exists on the estimation of the model parameters of time delayed processes. The objective of this paper is to review the main B-polynomial approaches to the delay estimation problem. More specifically, two algorithms are discussed and compared theoretically and in simulation. The algorithms involve various procedures to assess how the model relates to the observed data, to a priori knowledge, and to the algorithms’ intended use. Simulation results indicate that both the algorithms can suitably identify the model parameters, including the time delay. This paper also discusses advantages and disadvantages of the methods and gives some guidelines …

An Efficient Indirect Branch Predictor, Yul Chu, M. R. Ito

Electrical and Computer Engineering Faculty Publications

In this paper, we present a new hybrid branch predictor called the GoStay2, which can effectively reduce indirect misprediction rates. The GoStay2 has two different mechanisms compared to other 2- stage hybrid predictors that use a Branch Target Buffer (BTB) as the first stage predictor: Firstly, to reduce conflict misses in the first stage, a new effective 2-way cache scheme is used instead of a 4-way setassociative. Secondly, to reduce mispredictions caused by an inefficient predict and update rule, a new selection mechanism and update rule are proposed. We have developed a simulation program by using Shade and Spixtools, provided …

Combining Multiple Representations For Pen-Based Handwritten Digit Recognition, Fevzi̇ Ali̇moğlu, Ethem Alpaydin

Turkish Journal of Electrical Engineering and Computer Sciences

We investigate techniques to combine multiple representations of a handwritten digit to increase classification accuracy without significantly increasing system complexity or recognition time. In pen-based recognition, the input is the dynamic movement of the pentip over the pressure sensitive tablet. There is also the image formed as a result of this movement. On a real-world database of handwritten digits containing more than 11,000 handwritten digits, we notice that the two multi-layer perceptron (MLP) based classifiers using these representations make errors on different patterns implying that a suitable combination of the two would lead to higher accuracy. We implement and compare …

Factory Automation: A Controls Course For Every University, Kelvin T. Erickson

Electrical and Computer Engineering Faculty Research & Creative Works

The majority of new control engineering positions is now in manufacturing and involves programmable logic controllers (PLCs). The paper describes two courses developed at the University of Missouri-Rolla to satisfy this demand. Both courses present the subject of programming PLCs with an emphasis on the design of the programs. Both courses contain an integral laboratory component that solidifies the concepts presented in the lectures. The philosophy and pedagogical features of the two courses are first described, followed by the structure of the lecture and the laboratory exercises.