Electrical and Computer Engineering Commons^™

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

Department of Electrical and Computer Engineering: Faculty Publications

We report the observation of giant photoresistivity in electrochemically self-assembled CdS and ZnSe nanowires electrodeposited 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.

Localization Of Carriers And Polarization Effects In Quaternary Alingan Multiple Quantum Wells, E. Kuokstis, J. Zhang, M.-Y. Ryu, J. W. Yang, Grigory Simin, M. Asif Khan, R. Gaska, M. S. Shur

Faculty Publications

We report on observing a long-wavelength band in low-temperature photoluminescence(PL)spectrum of quaternary Al_0.22In_0.02Ga_0.76N/Al_0.38In_0.01Ga_0.61N multiple quantum wells(MQWs), which were grown over sapphire substrates by a pulsed atomic-layer epitaxy technique. By comparing the excitation-power density and temperature dependence of the PLspectra of MQWs and bulk quaternary AlInGaN layers, we show this emission band to arise from the carrier and/or exciton localization at the quantum well interface disorders. PL data for other radiative transitions in MQWs indicate that excitation-dependent spectra position is determined by screening of the built-in electric field.

Two-Dimensional Fast Evanescent Wave Algorithm, W. C. Chew, L. (Lijun) J. Jiang, S. Velamparambil

Electrical and Computer Engineering Faculty Research & Creative Works

A new fast evanescent wave algorithm (FEWA) is introduced in the two-dimensional (2-D) case. It expands the Green's function into propagating waves and directional evanescent waves. Applying the evanescent wave correction technique, a procedure similar to the traditional MLFMA can be expedited. No buffer region is necessary anymore, and fewer translators are needed. Numerical examples are given to show the features of this method.

Laser Intensity Scaling Through Stimulated Scattering In Optical Fibers, Timothy H. Russell

Theses and Dissertations

The influence of stimulated scattering on laser intensity in fiber optic waveguides is examined. Stimulated Brillouin scattering (SBS) in long, multimode optical waveguides is found to generate a Stokes beam that propagates in the fiber LP01 mode. Additionally, the same process is found to combine multiple laser beams into a single spatially coherent source. Limitations in beam cleanup and combining are also investigated to identify ways to overcome them. The last portion of the dissertation theoretically examines suppression of stimulated Raman scattering in fibers to eliminate the restriction this imposes on the power of a fiber laser or amplifier. The …

Ultraviolet Light-Emitting Diodes At 340 Nm Using Quaternary Alingan Multiple Quantum Wells, V. Adivarahan, A. Chitnis, J. P. Zhang, M. Shatalov, J. W. Yang, Grigory Simin, M. Asif Khan, R. Gaska, M. S. Shur

Faculty Publications

An ultraviolet light-emitting diode with peak emission wavelength at 340 nm is reported. The active layers of the device were comprised of quaternary AlInGaN/AlInGaN multiple quantum wells, which were deposited over sapphire substrates using a pulsed atomic-layer epitaxy process that allows precise control of the composition and thickness. A comparative study of devices over sapphire and SiC substrates was done to determine the influence of the epilayer design on the performance parameters and the role of substrate absorption.

Natural Doundary Element Method For Elliptic Boundary Value Problems In Domains With Concave Angle, Qi-Kui Du, De-Hao Yu

Journal of Marine Science and Technology

In this paper the natural boundary reduction for some elliptic boundary value problems with concave angle domains and its natural boundary element methods are investigated. Natural integral equations and Poisson integral formulae are given. A finite element methods of natural integral equations are discussed in details. The convergence of approximate solutions and their error estimates are obtained. Some numerical experiments are presented to demonstrate the performance of the method and our estimates. As an application, we present the coupling of FEM and natural boundary element.

Applying Time-Frequency Distribution Function To Doa Of Mobile Active Sensor, Shun-Hsyung Chang, Jun-Cheng Liu, Chih-Wei Chiu

Journal of Marine Science and Technology

Increasing the accuracy of time-frequency detection in engineering is always the goal that scientists are striving to achieve, because it is widely applied in the fields of Radar, Sonar, the exploration of earthquake epicenter etc. The current high-resolution time-frequency methods are mostly based on the structure of time-frequency distribution function of Cohen Family. Time frequency distribution function can trace the instantaneous frequency of nonstationary signal. This paper combines the process principle of multi-aperture Radar and Array signal and applies time-frequency distribution function in DOA of active sensor devices. By decoding of physical characteristics from the changes of frequency, which can …

Testing Exception And Error Cases Using Runtime Fault Injection, James A. Whittaker, Florence E. Mottay, Ibrahim K. El-Far

Electrical Engineering and Computer Science Faculty Publications

Fault injection deals with the insertion or simulation of faults in order to test the robustness and fault tolerance of a software application. Such measures are generally performed on software that is mission critical, to the extent that failure could have significant negative ramifications. Actual injection of faults can be performed either at compile time, when additional code is inserted to force error conditions to evaluate to true, or at runtime during which faults are injected into the software's execution environment. This paper focuses on the latter type of fault injection and presents a new mechanism for inserting environmental faults. …

Nonlinear Suppression Of Range Ambiguity In Pulse Doppler Radar, Jon M. Anderson

Theses and Dissertations

Coherent pulse train processing is most commonly used in airborne pulse Doppler radar, achieving adequate transmitter/receiver isolation and excellent resolution properties while inherently inducing ambiguities in Doppler and range. First introduced by Palermo in 1962 using two conjugate LFM pulses, the primary nonlinear suppression objective involves reducing range ambiguity, given the waveform is nominally unambiguous in Doppler, by using interpulse and intrapulse coding (pulse compression) to discriminate received ambiguous pulse responses. By introducing a nonlinear operation on compressed (undesired) pulse responses within individual channels, ambiguous energy levels are reduced in channel outputs. This research expands the NLS concept using discrete …

Survivable Mobile Operating System, James Whittaker, Mohommad Samarah

Electrical Engineering and Computer Science Faculty Publications

Although there is a large body of work on cryptographic techniques and algorithms that provide basic building blocks to solve specific security problems, relatively little work has been done in investigating security issues in mobile system contexts. Conventional security controls work well for static code, but break down with code mobility. In this paper, we investigate the need for end-to-end security in mobile and wireless operating systems. We study the implications of mobility - specifically, ways in which the operating system may facilitate communication security. We suggest a framework for designing security into mobile devices by building encryption into the …

Projection-Based Image Registration In The Presence Of Fixed-Pattern Noise, Ernest Armstrong, Stephen C. Cain, Majeed M. Hayat

Electrical and Computer Engineering Faculty Research and Publications

A computationally efficient method for image registration is investigated that can achieve an improved performance over the traditional two-dimensional (2-D) cross-correlation-based techniques in the presence of both fixed-pattern and temporal noise. The method relies on transforming each image in the sequence of frames into two vector projections formed by accumulating pixel values along the rows and columns of the image. The vector projections corresponding to successive frames are in turn used to estimate the individual horizontal and vertical components of the shift by means of a one-dimensional (1-D) cross-correlation-based estimator. While gradient-based shift estimation techniques are computationally efficient, they often …

Spectroscopic Ellipsometry And Electrical Studies Of As-Grown And Rapid Thermal Oxidized Si1−X−YGeXCY Films, W. K. Choi, W. Feng, L. K. Bera, Cary Y. Yang, J. Mi

Electrical and Computer Engineering

Transmission electron microscopy results showed the formation of SiC precipitation in a rapid thermally oxidized (RTO) Si_1−x−yGe_xC_y sample with high-C content. The spectroscopic ellipsometry results showed that the E₁ gap increased and E₂ gap decreased as the C concentration increased. For the oxidized samples, the amplitude of the E₂ transitions reduced rapidly and the E₁ transition shifted to a lower energy. The reduction in the E₂ transitions was due to the presence of the oxide layer. A high-Ge content layer and the low-C content in the RTO films accounted for …

A Neural Network-Based Approach For Control Of Capacitors Installed On Distribution Systems For Power Loss Reduction, Almoataz Youssef Abdelaziz

Almoataz Youssef Abdelaziz

A neural network for capacitor switching in electric distribution systems for the purpose of power loss reduction is presented in this paper. An optimization technique (sensitive node method) for allocating the compensating capacitors is used to generate the training set patterns of the neural network. The required input data of the neural network at varying loading conditions are directly obtained from a load flow study of the distribution system. Load variations are assumed to follow a randomized function that generates a randomized matrix which is employed for implementing the different load levels. The developed neural network is based on a …

Development Of Hiv Model And Its Simulation, D. K. Chaturvedi, Pritam Singh, S. K. Gaur, D. S. Mishra

D. K. Chaturvedi Dr.

The article discusses model developmetn for HIV infected population using the System Dynamics technique. The technique has an advantage over conventional modeling technique as it is dependent more on causal relationships that involve qualitative and quantitative variables to model socioeconomic problems of a complex nature. The model has been simulated and the results haven been compared witht he available data.

Techniques For The Regeneration Of Wideband Speech From Narrowband Speech, Jason A. Fuemmeler, Russell C. Hardie, William R. Gardner

Electrical and Computer Engineering Faculty Publications

This paper addresses the problem of reconstructing wideband speech signals from observed narrowband speech signals. The goal of this work is to improve the perceived quality of speech signals which have been transmitted through narrowband channels or degraded during acquisition. We describe a system, based on linear predictive coding, for estimating wideband speech from narrowband. This system employs both previously identified and novel techniques. Experimental results are provided in order to illustrate the system’s ability to improve speech quality. Both objective and subjective criteria are used to evaluate the quality of the processed speech signals.

Deconvolution Of Chirp Sidescan Sonar Data, Juliette W. Ioup, Maria T. Kalcic, Dale Bibee, Edit J. Kaminsky, George E. Ioup

Electrical Engineering Faculty Publications

No abstract provided.

Energy Storage Systems For Advanced Power Applications, Aysen Arsoy, Yilu Liu, Paul F. Ribeiro, Brian K. Johnson, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

While energy storage technologies do not represent energy sources, they provide valuable added benefits to improve stability power quality, and reliability of supply. Battery technologies have improved significantly in order to meet the challenges of practical electric vehicles and utility applications. Flywheel technologies are now used in advanced nonpolluting uninterruptible power supplies. Advanced capacitors are being considered as energy storage for power quality applications. Superconducting energy storage systems are still in their prototype stages but receiving attention for utility applications. The latest technology developments, some performance analysis, and cost considerations are addressed. This paper concentrates on the performance benefits of …

Multimedia Web-Based Resources For Engineering Education: The Media Design And Assessment Laboratory At Umr, Vicki M. Eller, Steve Eugene Watkins, Richard H. Hall, Joel Balestra, Asha S. Rao

Business and Information Technology Faculty Research & Creative Works

The Design, Development, and Assessment of Web-Based Multimedia Learning Resources Are Important Aspects of Engineering Education. the Media Design and Assessment Laboratory at the University of Missouri-Rolla Was Established to Facilitate the Interaction between Web Designers and Content Providers. It Was Created under the Auspices of the Instructional Software Development Center. This Paper Will Discuss Design Philosophy in Terms of the Identification of Fundamental Concepts, Development Steps, and Assessment Implementation within the Context of Ongoing Projects. These Projects Include Modules for an Optics Curriculum, Tutorials for an Interdisciplinary Course, and Interactive Software for a Basic Engineering Course.

Power System Deregulation, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

Given the difficulties encountered by the state of California in deregulating their electric power industry, many people are questioning the wisdom of such a move. To better understand the motivation behind deregulation, the author looks at the cost of energy nationwide in the United States. For example, she considers some of the regional energy costs from August 2001.

A Computer Vision System For The Automatic Inspection Of Geometric Distortions In Television Displays, Geoffrey C. Yerem

Masters Theses

The ability to automatically measure the image quality of a television display is a valuable resource. In display manufacturing, automatic inspection enables automatic television alignment, which reduces manufacturing costs and improves product quality. Automatic inspection also comes in handy during competitive analysis and engineering review. Primarily though, commercial inspection systems are built and used for manufacturing.

In the past two decades, the advent of microcomputers has made automatic inspection feasible through the use of computer vision. Most of the approaches developed can be divided into two groups: fixtured systems, with fixed or movable cameras, and position independent systems, which …

Hierarchical Image Segmentation Using The Watershed Algorithim With A Streaming Implementation, Annapoorani Gothandaraman

Masters Theses

We have implemented a graphical user interface (GUI) based semi-automatic hierarchical segmentation scheme, which works in three stages. In the first stage, we process the original image by filtering and threshold the gradient to reduce the level of noise. In the second stage, we compute the watershed segmentation of the image using the rainfalling simulation approach. In the third stage, we apply two region merging schemes, namely implicit region merging and seeded region merging, to the result of the watershed algorithm. Both the region merging schemes are based on the watershed depth of regions and serve to reduce the over …

Greenland Snow Accumulation Estimates From Satellite Radar Scatterometer Data, Mark R. Drinkwater, David G. Long, Andrew W. Bingham

Faculty Publications

Data collected by the C band ERS-2 wind scatterometer (EScat), the Ku band ADEOS-1 NASA scatterometer (NSCAT), and the Ku band SeaWinds on QuikScat (QSCAT) satellite instruments are used to illustrate spatiotemporal variability in snow accumulation on the Greenland ice sheet. Microwave radar backscatter images of Greenland are derived using the scatterometer image reconstruction (SIR) method at 3-day intervals over the periods 1991–1998 and 1996–1997 for EScat and NSCAT, respectively. The backscatter coefficient σ° normalized to 40° incidence, A, and gradient in backscatter, B, in the range 20°–60° are compared with historical snow accumulation data and recent measurements …

Research Progress On Proton Exchange Membranes Of Fuel Cells, Jing-Rong Yu, Dan-Min Xing, Fu-Qiang Liu, Jian-Guo Liu, Bao-Lian Yi

Journal of Electrochemistry

The proton exchange membrane fuel cells(PEMFC) use proton exchange membranes(PEM) as their electrolytes. The performance of the PEMFC is strongly dependent on the characteristics of the PEM. In this paper, the requirements of the PEM utilized in the PEMFC were analyzed. The per_fluorinated, partially fluorinated and non_fluorinated PEM were introduced respectively. The structures, preparation, properties of the various types of PEM and their applications in the PEMFC were also discussed in detail.

An Investigation Of Structural Properties Of Li-Al-Mixed Doped Spinels Materials Li_(1+X) Al_Ymn_(2-Y)O_4, Zi-Shan Zheng, Zi-Long Tang, Zhong-Tai Zhang, Wan-Ci Sheng

Journal of Electrochemistry

Al and Li elements were co_doped into host spinel lithium manganese oxide by a simple and economical preparation technology . There was an investigation of the influence of doped Al contents on the initial capacity and cycling performance of the materials. The investigation of the XRD patterns, the analysis of the SEM micrographs and the determination of IR spectroscopy showed that the particles of dopant materials are fine, narrowly distributed and well crystallized, and the bonds Mn_O are stronger than these of undoped materials. The resulted materials have a high initial capacity of 119 mAh/g and good cycling characterization. The …

The Influence Of Synthesis Conditions On The Electrochemical Properties Of Spinel Limn_2o_4, Jun Feng Xu, Zhi Yu Jiang

Journal of Electrochemistry

The electrochemical properties of spine LiMn 2O 4 synthesized via a solid state reaction were investigated. Electrolysis MnO 2(EMD), Li 2CO 3,LiOH and LiNO 3 were used as the initial materials. It was found that the electrochemical properties of LiMn 2O 4 were strongly influenced by the synthesis conditions. The LiMn 2O 4 samples prepared via the reaction of EMD and LiNO 3 showed the best properties for a lithium ion intercalation reaction. The procedure includes two steps: pretreatment at 280 ℃ for 6 hours to initiate the permeation of melting LiNO 3 into the micropores of EMD particles, followed …

Adsorption And Oxidation Of Methanol On Pt And Sb, S Modified Pt Electrodes Using Cyclic Voltammetry And Eqcm, Guo-Liang Chen, Sheng-Pei Chen, Heng Lin, Xing-Hong Zheng, Shi-Gang Sun

Journal of Electrochemistry

The processes of adsorption and oxidation of methanol on Pt, Pt/Sb ad and Pt/S ad electrodes were studied by using cyclic voltammetry and electrochemical quartz crystal microba_lance (EQCM). The results demonstrated that the oxidation of methanol depends strongly on oxidation states of electrode surface. Sb adatoms on Pt surface can adsorb oxygen at relatively low potentials, and exhibit catalytic effects for methanol oxidation. In contrast to Pt electrodes, the oxidation peak potential of methanol in this case negatively shifted to about 130 mV. In a contrary, the oxidation of S adatoms consumes oxygen species of Pt electrode surface. As a …

Electrosynthesis Of A New Electroactive Poly(2,2'-Diaminophenyloxydisulfide), Yu Zhi Su, Yan Wen Rao, Ye Yang, Mei-Bing Chen, Yin Ling Qiu, Yong-Hua Zhang, Ke Cheng Gong

Journal of Electrochemistry

A new electroactive poly(2,2' diaminophenyloxydisulfide) (PDAPD) was successfully synthesized from acetonitrile(AN)/tetrahydrofuran(THF)solutions containing the supporting electrolyte(LiClO 4)and the various kinds of acids(HCl,CF 3COOH,CCl 3COOH) on Pt electrode by consecutive cyclic voltammiry. The effects of the concentrations of supporting electrolyte(LiClO 4) and acid(HCl,CF 3COOH,CCl 3COOH) on electrodepositon of PDAPD film were investigated. The best experimental conditions for electrosynthesis of a highly electroactive conducting polymer film are that the concentrations are 0.1 mol/L and between 0.05 mol/L～0.5 mol/L,respectively for LiClO 4 and HCl.

The Research Of Organic Electrolyte Solutions For Li-Ion Batteries, Quang Chao Zhuang, Shan Wu, Wen Yuan Liu, Zhao-Da Lu

Journal of Electrochemistry

The characteristics of organic electrolyte solutions and its influences on the ion conductivity are summarized. The chemistry and electrochemistry of organic electrolyte solutions and characteristics of ordinary organic solvents are introduced. Progresses in studies of organic electrolyte solutions such as electrolyte salts, organic solvents, additives in recent years are reviewed, current situation of the studies of organic electrolyte solutions were also discussed.

The Investigation Of Prepare Condition For Micropores Membranes From Poly(Vinylidene Fluoride), Xu-Mei Ren, Feng Wu, Ying Bai, Hang-Jun Li, Xue Jie Huang

Journal of Electrochemistry

The micropores membranes from Poly (vinylidene fluoride) were prepared by the phase inversion process. The effects of the casting solution composition, exposure time prior to coagulation and temperature of the coagulation bath on properties of prepared membranes were investigated. For all prepared membranes an asymmetric structure, sometimes without a dense skin layer, was observed.

Studies On The Properties Of The Anodic Films Formed On Lead- Lanthanum And Lead-Samarium Alloys In Sulfuric Acid Solution, Hou Tian Liu, Chun Xuao Yang, Hai Heng Liang, Jiong Yang, Wei-Fang Zhou

Journal of Electrochemistry

AC voltammetry,linear sweep voltammetry,and cyclic voltammetry were applied to study the anodic corrosion of Pb,Pb 1.0at%La and Pb 1.0at%Sm electrodes in 4.5 mol·dm -3 H 2SO 4 solution (25 ℃).The experiment results show that samarium can inhibit the anodic corrosion of lead and decrease the impedance of anodic Pb(Ⅱ) film. Lanthanum can also decrease the impedance of the anodic Pb(Ⅱ)film, but the effect is smaller.