Engineering Commons^™

Interface Characteristics Of Vertically Aligned Carbon Nanofibers For Interconnect Applications, Yusuke Ominami, Quoc Ngo, Makoto Suzuki, Alexander J. Austin, Cary Y. Yang, Alan M. Cassell, Jun Li

Electrical and Computer Engineering

The authors characterize the detailed interface structure of Ni-catalyzed vertically aligned carbon nanofibers (CNFs) prepared by plasma-enhanced chemical vapor deposition for interconnect applications. Stacked graphitic layers and cup-shape structures of CNFs around the interface region have been observed using high-resolution scanning transmission electron microscopy. The interaction between the Ni catalyst and Ti layer dramatically affects the CNF structure during initial growth. The effect of interface nanostructures on contact resistance is also discussed.

College Of Engineering Senior Design Competition Fall 2006, University Of Nevada, Las Vegas

Fred and Harriet Cox Senior Design Competition Projects

Part of every UNLV engineering student’s academic experience, the senior design project stimulates engineering innovation and entrepreneurship. Each student in their senior year chooses, plans, designs and prototypes a product in this required element of the curriculum. A capstone to the student’s educational career, the senior design project encourages the student to use everything learned in the engineering program to create a practical, real world solution to an engineering challenge.

The senior design competition helps to focus the senior students in increasing the quality and potential for commercial application for their design projects. Judges from local industry evaluate the projects …

A Bayesian Perspective On Estimating Mean, Variance, And Standard-Deviation From Data, Travis E. Oliphant

Faculty Publications

This article shows how to compute confidence intervals for mean, standard-deviation, and variance using Bayesian methods. The method is implemented in SciPy as scipy.stats.bayes_mvs After reviewing some classical estimators for mean, variance, and standard-deviation and showing that un-biased estimates are not usually desirable, a Bayesian perspective is employed to determine what is known about mean, variance, and standard deviation given only that a data set in-fact has a common mean and variance. Maximum-entropy is used to argue that the likelihood function in this situation should be the same as if the data were independent and identically distributed Gaussian. A non-informative …

Inter-Turn Fault Diagnosis In Induction Motors Using The Pendulous Oscillation Phenomenon, Behrooz Mirafzal, Richard J. Povinelli, Nabeel Demerdash

Electrical and Computer Engineering Faculty Research and Publications

A robust interturn fault diagnostic approach based on the concept of magnetic field pendulous oscillation, which occurs in induction motors under faulty conditions, is introduced in this paper. This approach enables one to distinguish and classify an unbalanced voltage power supply and machine manufacturing/construction imperfections from an interturn fault. The experimental results for the two case studies of a set of 5-hp and 2-hp induction motors verify the validity of the proposed approach. Moreover, it can be concluded from the experimental results that if the circulating current level in the shorted loop increases beyond the phase current level, an interturn …

Machine Learning For Computer Security, Philip K. Chan, Richard P. Lippmann

Electrical Engineering and Computer Science Faculty Publications

The prevalent use of computers and internet has enhanced the quality of life for many people, but it has also attracted undesired attempts to undermine these systems. This special topic contains several research studies on how machine learning algorithms can help improve the security of computer systems.

A Fuzzy Logic Controller For Autonomous Wheeled Vehicles, Mohamed Trabia, Linda Z. Shi, Neil Eugene Hodge

Mechanical Engineering Faculty Research

Autonomous vehicles have potential applications in many fields, such as replacing humans in hazardous environments, conducting military missions, and performing routine tasks for industry. Driving ground vehicles is an area where human performance has proven to be reliable. Drivers typically respond quickly to sudden changes in their environment. While other control techniques may be used to control a vehicle, fuzzy logic has certain advantages in this area; one of them is its ability to incorporate human knowledge and experience, via language, into relationships among the given quantities. Fuzzy logic controllers for autonomous vehicles have been successfully applied to address various …

Novel Capacitance Extraction Method Using Direct Boundary Integral Equation Method And Hierarchical Approach, L. (Lijun) J. Jiang, B. J. Rubin, J. D. Morsey, H. T. Hu, A. Elfadel

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a novel hierarchical capacitance extraction method is introduced. It takes advantage of surface integral equations to have far less unknowns than the volumetric method. It uses the "divide and conquer" strategy to hierarchically solve the dense capacitance matrix efficiently. It partitions the problem into small regions (cells) automatically and each region is analyzed separately. An inverse binary-tree browse procedure is employed to combine cell capacitance matrixes from leafy level of the tree to the root. A global capacitance matrix is obtained at the root without computing charge distribution. Benchmarks using the developed code CSurf are provided to …

Numerical Analysis Of Sandwiched Composite-Fss Structures, Qiang Rui, Chen Ji, Huang Jingyu, Maria Koledintseva, Richard E. Dubroff, James L. Drewniak, Yang Fan

Electrical and Computer Engineering Faculty Research & Creative Works

A numerical technique to analyze shielding effectiveness of sandwiched FSS-composite structures is proposed. This technique is based on using a dispersive FDTD method in conjuncture with a novel periodic boundary condition to model sandwiched FSS-composite elements. Results show that by inserting single or multilayered FSS elements into composite materials, better shielding effectiveness can be achieved. © 2006 IEEE.

Integral Equation Solvers For Real World Applications -Some Challenge Problems, W. C. Chew, I. T. Chiang, C. P. Davis, A. Hesford, M. K. Li, Y. Liu, Z. G. Qian, M. Saville, L. Sun, M. S. Tong, J. Xiong, L. (Lijun) J. Jiang, H. Y. Chao, Y. H. Chu

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

The Use Of Fast Integral Equations Solvers For Practical Package And Interconnect Analysis, J. D. Morsey, B. J. Rubin, L. (Lijun) Jiang, L. Shan, L. B. Eisenberg, D. Becker, M. Arseneault

Electrical and Computer Engineering Faculty Research & Creative Works

Fast integral equation methods are now being applied to packaging and other such "low frequency" problems. This paper explores some of the issues surrounding such an application to real, product level packaging and interconnect type structures. Discussed are issues such as low frequency breakdown, mesh aspect ratios, and solver convergence. Finally, integral equation solver examples are presented using the IBM internally developed pre-corrected FFT (PFFT) solver labeled EMSurf[l]. ©2006 IEEE.

Oct-Based Elastography For Large And Small Deformations, Donald D. Duncan, Sean J. Kirkpatrick, Ruikang K. Wang

Electrical and Computer Engineering Faculty Publications and Presentations

We present two approaches to speckle tracking for optical coherence tomography (OCT)-based elastography, one appropriate for small speckle motions and the other for large, rapid speckle motions. Both approaches have certain advantages over traditional cross-correlation based motion algorithms. We apply our algorithms to quantifying the strain response of a mechanically inhomogeneous, bi-layered polyvinyl alcohol tissue phantom that is subjected to either small or large dynamic compressive forces while being imaged with a spectral domain OCT system. In both the small and large deformation scenarios, the algorithms performed well, clearly identifying the two mechanically disparate regions of the phantom. The stiffness …

Krf Excimer Laser-Assisted Combustion-Flame Deposition Of Diamond Films, Y. X. Han, Hao Ling, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

Cobalt (Co) composition has detrimental effects on the deposition of diamond films on cemented tungsten carbide (WC-Co) substrates. It decreases adhesion of the deposited films to the substrates and causes a transformation of sp³-bonded diamond to sp²-bonded graphite. In this study, a KrF excimer laser with a wavelength of 248 nm, a pulse width of 23 ns, and a pulse energy range of 84–450 mJ was used in the combustion-flame method to improve the quality of the deposited diamond films. Scanning electron microscopy, energy dispersive x-ray analysis, and Raman spectroscopy of the deposited films showed that …

Predicting On-Orbit Static Single Event Upset Rates In Xilinx Virtex Fpgas, Joshua Engel, Keith S. Morgan, Michael J. Wirthlin, Paul S. Graham

Faculty Publications

Sponsorship: Department of Energy, Los Alamos National Laboratory. This document describes the methodology used to predict single-event upset rates for Xilinx Virtex FPGAs based on the CREME96 orbit modeling tool. Using this methodology, SEU upset rates are obtained for several Xilinx Virtex FPGAs including Virtex, Virtex-II, and Virtex-4. Further, SEU upset rates are obtained for a variety of orbits for each of these FPGAs.

Bright Contrast Imaging Of Carbon Nanofiber-Substrate Interface, Makoto Suzuki, Hirohiko Kitsuki, Quoc Ngo, Cary Y. Yang

Electrical and Computer Engineering

We present the contrast mechanisms of scanning electron microscopy (SEM) for visualizing the interface between carbon nanofibers (CNFs) and the underlying substrate. SEM imaging with electron beam energies higher than a certain threshold provides different image contrasts depending on whether CNFs are in contact with the substrate or suspended above the substrate. CNFs with diameters ranging from 25to250nm are examined with various electron beam energies. It is found that the threshold energy corresponds to the energy required to penetrate the CNF and its dependence on CNF diameter can be understood using the theory of electron range. This knowledge will be …

Negative Conductance Power Amplifier, Vladimir I. Prodanov

Electrical Engineering

Power amplifiers are disclosed that demonstrate improved linearity and efficiency in applications requiring significant peak-to-average ratios (PAR). A power amplifier in accordance with the present invention comprises a first transistor in an input stage that converts DC power into AC power; and a second transistor in a negative conductance stage that has a current-voltage characteristic with at least two slopes. The at least two slopes of the current-voltage characteristic are separated by a break point that may be controlled. The power amplifier may also include a non-dissipative two-port device that has two AC ports. The non-dissipative two-port device has a …

Signal Processing And Information Fusing Algorithms For The Synthesis Of An Alternative Electromyogram/Eye Gaze Tracking Computer Cursor Control System, Craig Anthony Chin

FIU Electronic Theses and Dissertations

This research pursued the conceptualization and real-time verification of a system that allows a computer user to control the cursor of a computer interface without using his/her hands. The target user groups for this system are individuals who are unable to use their hands due to spinal dysfunction or other afflictions, and individuals who must use their hands for higher priority tasks while still requiring interaction with a computer.

The system receives two forms of input from the user: Electromyogram (EMG) signals from muscles in the face and point-of-gaze coordinates produced by an Eye Gaze Tracking (EGT) system. In order …

Experimental Investigation On Voip Performance And The Resource Utilization In 802.11b Wlans, Miroslaw Narbutt, Mark Davis

Conference papers

In a shared medium network like the 802.11b WLAN, predicting the quality of VoIP calls from the resource usage of the wireless medium is highly desirable. Analyzing the bandwidth usage at the L2/MAC layer may be especially useful for potential QoS provisioning and call admission schemes. This paper experimentally investigates the relationship between resource utilization in WLANS and the quality of VoIP calls transmitted over wireless medium. Specifically we evaluate how the amount of free bandwidth influences transmission impairments (i.e. delay, loss and jitter) and thus call quality. Resource utilization (under the MAC bandwidth components framework) is calculated by a …

Weak-Group Unitary Space-Time Codes, Adam Panagos, Kurt Louis Kosbar, Asif Iqbal Mohammad

Electrical and Computer Engineering Faculty Research & Creative Works

We propose a construction technique for unitary space-time codes that use Givens rotation matrices. These constellations have a desirable weak group property that leads to reduced construction and decoding complexity. The newly constructed constellations have the best known diversity product and diversity sum for a wide range of constellation sizes and number of transmit antennas.

Optimal Placement And Control Of Unified Power Flow Control Devices Using Evolutionary Computing And Sequential Quadratic Programming, Radha P. Kalyani, Mariesa Crow, Daniel R. Tauritz

Electrical and Computer Engineering Faculty Research & Creative Works

A crucial factor effecting modern power systems today is power flow control. An effective means for controlling and improving power flow is by installing fast reacting devices such as a unified power flow controller (UPFC). For maximum positive impact of this device on the power grid, it should be installed at an optimal location and employ an optimal realtime control algorithm. This paper proposes the combination of an evolutionary algorithm (EA) to find the optimal location and sequential quadratic programming (SQP) to optimize the UPFC control settings. Simulations are conducted using the classic IEEE 118 bus test system. For comparison …

Time-Varying Mimo Channels: Measurement, Analysis, And Modeling, Michael A. Jensen, Jon W. Wallace

Faculty Publications

communication nodes is analyzed. A wide-band 8 times 8 sounder is employed to measure the response of indoor and outdoor channels at 2.55 and 5.2 GHz. The rate of channel temporal variation is then quantified in terms of information theoretic metrics that indicate the loss in channel quality as transmit and receive channel state information becomes increasingly outdated. Finally, these metrics are used to investigate the ability of two different modeling strategies-a random matrix model and a physical time-varying cluster model-to capture the channel temporal variation.

Detection And Identification Of Vehicles Based On Their Unintended Electromagnetic Emissions, Xiaopeng Dong, Haixiao Weng, Daryl G. Beetner, Todd H. Hubing, Donald C. Wunsch, Michael Noll, Huseyin Goksu, Benjamin Moss

Electrical and Computer Engineering Faculty Research & Creative Works

When running, vehicles with internal combustion engines radiate electromagnetic emissions that are characteristic of the vehicle. Emissions depend on the electronics, harness wiring, body type, and many other features. Since emissions are unique to each vehicle, these may be used for identification purposes. This paper investigates a procedure for detecting and identifying vehicles based on their RF emissions. Parameters like the average magnitude or standard deviation of magnitude within a frequency band were extracted from measured emission data. These parameters were used as inputs to an artificial neural network (ANN) that was trained to identify the vehicle that produced the …

Anisotropic High Aspect Ratio Etch Development For Fluorinated Polymers With Stress Relief Technique, S. Kim, Gregory P. Nordin, N. Rahmanian

Faculty Publications

The authors have developed an anisotropic, high aspect ratio (18:1) etch for perfluorocyclobutyl (PFCB) polymers with trenches as narrow as 800 nm using a CO/O2 etch chemistry in an inductively coupled plasma reactive ion etcher. Anisotropy is achieved by carbon sidewall passivation. The motivation for this etch development is to use the air trenches as very compact waveguide splitters [S. Kim et al., Opt. Eng. 45, 054602 (2006)] The authors report a new trench widening mechanism due to tensile stress of the PFCB films and a method of avoiding this widening through the use of additional stress relief trenches on …

Using Coupled Eulerian And Lagrangian Grids To Model Explosive Interactions With Buildings, Braden Lusk, William P. Schonberg, Jason Baird, Robert S. Woodley, Warren Noll

Mining Engineering Faculty Research & Creative Works

This paper presents the development of a computational model that can be used to study the interactions between structures and detonating explosives contained within them. This model was developed as part of an effort to develop a rubble characterization model for use in AmmoSIM, an agent based urban tactical decision aid (UTDA) software for weapon-target pairing. The rubble pile created following the collapse of a building in a combat situation can significantly impact mission accomplishment, particularly in the area of movement and maneuver. The information provided by AmmoSIM will enable both platoon level and command center staff to make informed …

Cancellation Predictive Control For Three-Phase Pwm Rectifiers Under Harmonic And Unbalanced Input Conditions, Peng Xiao, Keith Corzine, Ganesh K. Venayagamoorthy

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents an intuitive and simple-to-implement control scheme to improve the performance of three-phase boost-type PWM rectifiers under harmonic and unbalanced input conditions. Unlike most other control strategies, the proposed method does not need to extract either the harmonic or the negative-sequence components in the supply voltages and currents. A near-synchronous reference frame is used to determine the positive-sequence fundamental-frequency component in the input voltages. Utilizing only the extracted component, the DC-link voltage control and power factor control are implemented independently to determine the phase angle and magnitude of the PWM reference voltage. The commanded rectifier voltage adjustments are …

Dynamic Programming-Based Energy-Efficient Rate Adaptation For Wireless Ad Hoc Networks, Maciej Jan Zawodniok, Jagannathan Sarangapani

Electrical and Computer Engineering Faculty Research & Creative Works

Resource constraints require that ad hoc wireless networks are energy efficient during transmission and rate adaptation. In this paper we propose a novel cross-layer energy-efficient rate adaptation scheme that employs dynamic programming (DP) principle to analytically select the modulation scheme online. The scheme uses channel state information from the physical layer and congestion information from the scheduling layer to select a modulation rate. This online selection maximizes throughput while saving energy and preventing congestion. The simulation results indicate that an increase in throughput by 96% and energy-efficiency by 131% is observed when compared to the Receiver Based AutoRate (RBAR) protocol.

Synchronous Reference Frame Based Active Filter Current Reference Generation Using Neural Networks, Joy Mazumdar, Ronald G. Harley, Ganesh K. Venayagamoorthy

Electrical and Computer Engineering Faculty Research & Creative Works

The increased use of nonlinear devices in industry has resulted in direct increase of harmonic distortion in the industrial power system in recent years. The significant harmonics are almost always 5th, 7th, 11th and the 13th with the 5th harmonic being the largest in most instances. Active filter systems have been proposed to mitigate harmonic currents of the industrial loads. The most important requirement for any active filter is the precise detection of the individual harmonic component's amplitude and phase. Fourier transform based techniques provide an excellent method for individual harmonic isolation, but it requires a minimum of two cycles …

A Novel Seven-Level Shunt Active Filter For High-Power Drive Systems, Xiao Peng, Keith Corzine, Ganesh K. Venayagamoorthy

Electrical and Computer Engineering Faculty Research & Creative Works

In high-power adjustable speed motor drives, such as those used in electric ship propulsion systems, active filters provide a viable solution to mitigating harmonic related issues caused by diode or thyristor rectifier front-ends. To handle the large compensation currents and provide better thermal management, two or more paralleled semiconductor switching devices are often used. In this paper, a novel topology is proposed where two active filter inverters are connected with tapped reactors to share the compensation currents. The proposed active filter topology can also produce seven voltage levels, which significantly reduces the switching current ripple and the size of ripple …

Power Electronic Courses That Work, Taufik

Electrical Engineering

This paper presents approaches that have been implemented in power electronic courses to be more appealing to electrical engineering students and hence increase their enrollments. The approaches entail redesigning the structure and content of the courses along with developing new laboratory experiments to better align the lab with the lecture portion of the courses and to reflect recent practical issues in power electronics. In addition to lab experiments, the redesigned courses provide students with an opportunity to apply their knowledge in assigned hardware projects that illustrated many of the points learned in the lecture portion of the course with increasing …

Electromagnetic Crosstalk Penalty In 2.5gb/S And 10gb/S Serial Optical Modules, Xiaomin Jin, Fei Wang, Keith D. Lystad, Musoke H. Sendaula

Electrical Engineering

Electromagnetic crosstalk poses a serious problem in advanced serial communication modules. This paper focuses on the primary sources of crosstalk penalty in a 2.5 Gb/s optic transceiver and a 1OGb/s optic transponder. A novel method to quantify the crosstalk penalty by observing a receiver's bit-error-ratio (BER) versus transmitter to receiver signal phase is proposed. A coupled microstrip transmission line model is also explored to demonstrate inductive crosstalk coupling.

Characterization Of Error-Tolerant Applications When Protecting Control Data, Darshan D. Thaker, Diana Franklin, John Y. Oliver, Susmit Biswas, Derek Lockhart, Tzvetan Metodi, Frederic T. Chong

Electrical Engineering

Soft errors have become a significant concern and recent studies have measured the "architectural vulnerability factor" of systems to such errors, or conversely, the potential that a soft error is masked by latches or other system behavior. We take soft-error tolerance one step further and examine when an application can tolerate errors that are not masked. For example, a video decoder or approximation algorithm can tolerate errors if the user is willing to accept degraded output. The key observation is that while the decoder can tolerate error in its data, it can not tolerate error in its control. We first …