Engineering Commons^™

Development Of 200～500 W Portable Proton Exchange Membrane Fuel Cell Power System, Li-Qing Hu, Li-Rong Zhou, Zheng Li, Jian-Wei Xia, Ming-Zhu Fu, Xin Wu, Yun Zhu

Journal of Electrochemistry

The Properties of the Portable PEM Fuel Cell Power Source are very unique compared with the common primary or rechargeable electro-chemical battery. This paper describes the In this work, of the 200～500 W portable PEM fuel cell power system, was developed. The system mainly composed of four subsystem: 1)Fuel cell stack; 2)Air delivery; 3)Hydrogen source; 4)Heat dissipation and system control.

An Investigation On Sr-Doped Spinel Phase-LisrXMn2-XO4, Hui Zhan, Yun-Hong Zhou

Journal of Electrochemistry

Sr-doped spinel phase-LiSr_xMn_2-xO₄ was successfully prepared by solid-state method. Structural and electrochemical characterizations were carried out. Although Sr²⁺ has a large ion radius-1.12 , the spinel structure can be well maintained for LiSr_xMn_2-xO₄ sample as far as the x value doesn't surpass 0.05. Electrochemical study presents supporting evidence that doping the stoichiometric LiSr_xMn_2-xO₄ phase with Sr is an effective way to improve the cycleability of LiSr_xMn_2-xO₄ spinel material. A remarkable enhancement of the cycleability with retention of the initial …

Electrosynthesis Of Glyoxylic Acid In A Cooled Cathode Reactor, Jin-Hong Fan, Jun Li, Xue-Yun Chen, Wei Li, Hao-Qi Gao

Journal of Electrochemistry

Glyoxylic acid was produced by electroreduction of oxalic acid in a well designed cooled cathode reactor. The cathodic and anodic electrolytes were super-saturated oxalic acid and hydrochloric acid aqueous solutions separated by a super-acid ion-exchange membrane. The current efficiency and time-space yield of glyoxylic acid were studied under different temperatures of cathode and electrolyte, current densities, materials of cathode. With the cooled cathode reactor, the energy consumption was reduced and higher oxalic acid concentration was available in solution, so that current efficiency was improved. The results indicated that the average time-space yield of glyoxylic acid was about 0.032 kg·dm^{-3 …}

Electrocatalytic Oxidation Of Formaldehyde On The Proline Film Modified Electrode, Yu-Rong Ma, Qiu-Xia Yang, Guo-Bao Li, Zheng-Kai Xi, Xue-Lin Wang

Journal of Electrochemistry

The proline film modified electrode and its electrochemical behavior was studied by cyclic voltammetry and spectroelectrochemistry. After incorporation of Ni(Ⅱ), the cyclic voltammograms of the proline Ni(Ⅱ) film electrode exhibited a typical redox peak, which appeared at potential of 0.52 V anodic and 0.44 V cathodic in NaOH. The formal potentials E' were linearly dependent on the pH, and the peak currents ip were linearly dependent on the square root of the scan rates, thus charge transfer in the film was controlled by diffusion. The diffusion coefficient is figured out to be 2×10^_-10 cm²·s^-1. The …

Preparation,Structure And Properties Of Electrochromic Rhodium Oxide Films, Hai-Hong Wang, Tao Wang, Man-Ming Yan, Zhi-Yu Jiang

Journal of Electrochemistry

Electrochromic rhodium oxide films were prepared on ITO substrate by sol-gel method. The films exhibited reversible two-color (bright yellow at reduction and dark green at oxidation) electrochromic behavior in alkaline solution with good cycle stability. In-situ XRD, TGA-DTA, IR, XPS methods were used for studying the structure and chemical process of the films. The diffusion coefficient during the electrochromic process was measured by electrochemical impedance spectra method. It was found that the rhodium oxide films may be suitable for the use in electrochromic devices.

Time-Resolved Photoluminescence Of Quaternary Alingan-Based Multiple Quantum Wells, Mee-Yi Ryu, C. Q. Chen, E. Kuokstis, J. W. Yang, Grigory Simin, M. Asif Khan, G. G. Sim, P. W. Yu

Faculty Publications

Time-resolvedphotoluminescence(PL)dynamics has been studied in AlInGaN/AlInGaN multiple quantum wells(MQWs) grown by a pulsed metalorganic chemical vapor deposition (PMOCVD) procedure. The PL decay kinetics was found to be sensitive to the emission energy and temperature. The PL decay time increases with decreasing emission energy, which is a characteristic of localized carrier/exciton recombination due to alloy fluctuations. Its temperature dependence shows radiative recombination to be the dominant process at low temperatures, indicating a high quality of PMOCVD grown quaternary AlInGaN MQWs and establishing them as promising structures for the active region of deep ultraviolet light emitting diodes.

Complex Low-Pass Filters, Peter Kiss, Vladimir I. Prodanov, Jack Glas

Electrical Engineering

Quadrature zero-if transceivers suffer from the imbalance of the I and Q paths. By using a complex low-pass filter topology instead of a conventional pair of real low-pass filters, this imperfection can be reduced. Both analytical and numerical analysis show that the proposed technique is significantly more robust to circuit imperfections than the traditional architecture.

Luminescence Mechanisms In Quaternary AlXInYGa1-X-YN Materials, Mee-Yi Ryu, C. Q. Chen, E. Kuokstis, J. W. Yang, Grigory Simin, M. Asif Khan

Faculty Publications

Low-temperature photoluminescence investigations have been carried out in the quaternary AlInGaN epilayers and AlInGaN/AlInGaN multiple quantum wells (MQWs) grown by pulsedmetalorganic chemical-vapor deposition (PMOCVD). With increasing excitation power density, the emission peaks in both AlInGaN epilayers and MQWs show a strong blueshift and theirlinewidths increase. The luminescence of the samples grown by PMOCVD is attributed to recombination of carriers/excitons localized at band-tail states. We also demonstrate theluminescence properties of AlInGaN and AlGaN materials grown by a pulsed atomic-layerepitaxy and conventional MOCVD, respectively.

Automatic Speechreading With Application To Speaker Verification, Charles C. Broun, Xiaozheng Zhang, Russell M. Mersereau, Mark A. Clements

Electrical Engineering

Speech not only conveys the linguistic information, but also characterizes the talker's identify and therefore can be used in personal authentication. While most of the speech information is contained in the acoustic channel, the lip movement during speech production also provides useful information. In this paper we investigate the effectiveness of visual speech features in a speaker veri pound sterling cation task. We pound sterling rst present the visual front-end of the automatic speechreading system. We then develop a recognition engine to train and recognize sequences of visual parameters. The experimental results based on the XM2VTS database [1] demonstrate that …

Visual Speech Feature Extraction For Improved Speech Recognition, Xiaozheng Zhang, Russell M. Mersereau, Mark A. Clements, Charles C. Broun

Electrical Engineering

Mainstream automatic speech recognition has focused almost exclusively on the acoustic signal. The performance of these systems degrades considerably in the real world in the presence of noise. On the other hand, most human listeners, both hearing-impaired and normal hearing, make use of visual information to improve speech perception in acoustically hostile environments. Motivated by humans' ability to lipread, the visual component is considered to yield information that is not always present in the acoustic signal and enables improved accuracy over totally acoustic systems, especially in noisy environments. In this paper, we investigate the usefulness of visual information in speech …

Crack-Free Thick Algan Grown On Sapphire Using Aln/Algan Superlattices For Strain Management, J. P. Zhang, H. M. Wang, M. E. Gaevski, C. Q. Chen, Q. Fareed, J. W. Yang, Grigory Simin, M. Asif Khan

Faculty Publications

We report on an AlN/AlGaN superlattice approach to grow high-Al-content thick n⁺-AlGaNlayers over c-plane sapphire substrates. Insertion of a set of AlN/AlGaN superlattices is shown to significantly reduce the biaxial tensile strain, thereby resulting in 3-μm-thick, crack-free Al_0.2Ga_0.8N layers. These high-quality, low-sheet-resistive layers are of key importance to avoid current crowding in quaternary AlInGaN multiple-quantum-well deep-ultraviolet light-emitting diodes over sapphire substrates.

Arrival Rate Identification For A Class Of Traffic Signal Control Problem, Xiao-Hua Yu, Allen R. Stubberud

Electrical Engineering

Setting signals at traffic intersections to reduce congestion is one of the most challenging problems in traffic management. To find the optimal control strategy, specific information of the traffic flows passing through intersections must be provided in advance. It has been shown that the Markovian decision control theory can be successfully applied to solve traffic signal control problems, when both the state transition probabilities and the one-step reward function are known. In this paper, an online parameter identification algorithm is investigated for adaptive Markovian decision control at an isolated traffic intersection with unknown vehicle arrival rates. The authors give a …

The Pci Compatible Junction Temperature Monitor, Adrian L. Marshall

Electronic Dissertations and Theses

The purpose of this research project is to give a precise temperature reading of various semiconductor devices. An accurate junction temperature measurement could allow you to eliminate heat sinks and fans if they are not needed or it could prevent your system from going down on a hot day. Nearly all integrated circuits contain input protection diodes to protect against static electricity. These diodes can be used to make the measurement process simple. The only procedure that is required is to disconnect one wire leading to the device to be tested. The junction temperature monitor is then connected to the …

Estimating The Noise Mitigation Effect Of Local Decoupling In Printed Circuit Boards, Jun Fan, Wei Cui, James L. Drewniak, Thomas Van Doren, James L. Knighten

Electrical and Computer Engineering Faculty Research & Creative Works

Local decoupling, i.e., placing decoupling capacitors sufficiently close to device power/ground pins in order to decrease the impedance of power bus at frequencies higher than the series resonant frequency, has been studied using a modeling approach, a hybrid lumped/distributed circuit model established and an expression to quantify the benefits of power bus noise mitigation due to local decoupling developed. In this work, a test board with a local decoupling capacitor was studied and the noise mitigation effect due to the capacitor placed adjacent to an input test port was measured. Closed-form expressions for self and mutual inductances of vias are …

Extracting Cad Models For Quantifying Noise Coupling Between Vias In Pcb Layouts, Shaofeng Luan, Jun Fan, W. Liu, Fengchao Xiao, James L. Knighten, Norman W. Smith, Ray Alexander, Jim Nadolny, Yoshio Kami, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

A method to extract a lumped element prototype SPICE model is used to study noise coupling between non-parallel traces on a PCB. The parameters in this model are extracted using a PEEC-like approach, a Circuit Extraction approach based on a Mixed-Potential Integral Equation formulation (CEMPIE). Without large numbers of unknowns, the SPICE model saves computation time. Also, it is easy to incorporate into system SPICE net list to acquire the system simulation result considering the coupling between traces on the printed circuit board (PCB). A representative case is studied, and the comparison of measurements, CEMPIE simulation, and SPICE modeling are …

Oxygen Plasma Effects On Optical Properties Of Znse Films, Li Yan, John A. Woollam, Eva Franke

Department of Electrical and Computer Engineering: Faculty Publications

Zinc selenide is an infrared transparent semiconductor material being considered for use in space as an infrared optical coating. In this work, zinc selenide thin films of different thicknesses were exposed to an electron cyclotron resonance generated oxygen plasma, often used to ‘‘simulate’’ the low earth orbital environment. The maximum fluence used in our experiments was equivalent to ~16 years in the low earth orbital environment. ZnSe thin film optical constants (both before and after oxygen plasma exposure) were determined using variable angle spectroscopic ellipsometry from the vacuum ultraviolet at 146 nm through the middle infrared to 40 μm. A …

A Model Of Plasma Frequency Probes Utilizing Plasma Fluid Equations And Finite Difference Time Domain (Fdtd) Theory, Jeffrey D. Ward

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

As man continues to search the unknown, additional tools are needed to develop and analyze new probes. This thesis will present a full wave Finite Difference Time Domain model that is capable of analyzing radio frequency probes immersed in realistic ionospheric plasma. The five moment approximations, Maxwell's equations and the plasma fluid equations, are discretized using a finite difference time domain method. Balmain's and Adachi theories are used to validate the simulation at the gyro and hybrid resonance points. Finally, with the model developed, the simulation is used to analyze a microstrip patch plasma impedance probe immersed in hot collisional …

Modeling The Indoor Mimo Wireless Channel, Michael A. Jensen, Jon W. Wallace

Faculty Publications

This paper demonstrates the ability of a physically based statistical multipath propagation model to match capacity statistics and pairwise magnitude and phase distributions of measured 4 x 4 and 10 x 10 narrow-band multiple-input multiple-output data (MIMO) at 2.4 GHz. The model is compared to simpler statistical models based on the multivariate complex normal distribution with either complex envelope or power correlation. The comparison is facilitated by computing channel element covariance matrices for fixed sets of multipath statistics. Multipolarization data is used to demonstrate a simple method for modeling dual-polarization arrays.

Fdtd Modeling Of Skin Effect, Chen Wang, James L. Drewniak, Min Li, Jun Fan, James L. Knighten, Norman W. Smith, Ray Alexander, Jingyu Huang

Electrical and Computer Engineering Faculty Research & Creative Works

The data rates and clock speeds of current highspeed signals are increasing rapidly, consequently, not only the lossy nature of FR-4 but also the lossy nature of good conductors, such as copper, need to be taken into account in high-speed signal designs. In order to well predict the loss caused by both dielectric loss and skin effect loss, a suitable simulation tool is needed. A surface impedance boundary condition (SIBC) algorithm was implemented in FDTD modeling herein to accommodate the skin effect loss due to finite conductivity of good conductors. Good agreement between the FDTD result and the measurements as …

Cancellation Of Mri Motion Artifact In Image Plane, Eung-Kyeu Kim, Nohpill Park, Minsu Choi, S. Tamura

Electrical and Computer Engineering Faculty Research & Creative Works

In this study, a new algorithm for canceling a MRI artifact due to the translational motion in image plane is described. Unlike the conventional iterative phase retrieval algorithm, in which there is no guarantee for the convergence, a direct method for estimating the motion is presented. In previous approaches, the motions in the x(read out) direction and the y(phase encoding) direction were estimated simultaneously. However, the feature of x and y directional motions are different from each other. By analyzing their features, each x and y directional motion is canceled by the different algorithms in two steps. First, it is …

Comparision Of Measured Convection Velocities With Calcuulations Based On Electric Potential Model, Daniel E. Britton

Honors Capstone Projects and Theses

No abstract provided.

Le Bio Wall : Un Tissue Informatique Pour Le Prototypage De Systèmes Bio-Inspirés, Andre Stauffer, Daniel Mange, Gianluca Tempesti, Christof Teuscher

Electrical and Computer Engineering Faculty Publications and Presentations

Dans cet article, nous décrivons le BioWall, un tissu informatique reconfigurable géant développé dans le but d’y implémenter des machines mettant en oeuvre les principes de notre projet Embryonique. Bien que ses dimensions et ses caractéristiques en font d’abord un objet de démonstration publique, le BioWall constitue également un outil de recherche précieux, du fait que sa faculté de reprogrammation et sa structure cellulaire s’adaptent parfaitement à l’implémentation de toutes sortes de systèmes bioinspirés. Pour illustrer ces capacités, nous décrivons un ensemble d’applications qui reflètent différentes sources d’inspiration biologique allant des systèmes biologiques ontogénétiques aux dispositifs évolutifs phylogénétiques, en passant …

Learning Nonstationary Models Of Normal Network Traffic For Detecting Novel Attacks, Philip K. Chan, Matthew V. Mahoney

Electrical Engineering and Computer Science Faculty Publications

Traditional intrusion detection systems (IDS) detect attacks by comparing current behavior to signatures of known attacks. One main drawback is the inability of detecting new attacks which do not have known signatures. In this paper we propose a learning algorithm that constructs models of normal behavior from attack-free network traffic. Behavior that deviates from the learned normal model signals possible novel attacks. Our IDS is unique in two respects. First, it is nonstationary, modeling probabilities based on the time since the last event rather than on average rate. This prevents alarm floods. Second, the IDS learns protocol vocabularies (at the …

Maximum Current In Nitride-Based Heterostructure Field-Effect Transistors, A. Koudymov, H. Fatima, Grigory Simin, J. Yang, M. Asif Khan, A. Tarakji, X. Hu, M. S. Shur, R. Gaska

Faculty Publications

We present experimental and modeling results on the gate-length dependence of the maximum current that can be achieved in GaN-based heterostructurefield-effect transistors(HFETs) and metal–oxide–semiconductor HFETs (MOSHFETs). Our results show that the factor limiting the maximum current in the HFETs is the forward gate leakage current. In the MOSHFETs, the gate leakage current is suppressed and the overflow of the two dimensional electron gas into the AlGaN barrier region becomes the most important factor limiting the maximum current. Therefore, the maximum current is substantially higher in MOSHFETs than in HFETs. The measured maximum current increases with a decrease in the gate …

Implementation Of Viterbi Decoder On Xilinx Xc4005xl Fpga, Nabil Abu-Khader

Wayne State University Theses

The Viterbi decoding algorithm is used to decode convolutional codes and is found in many systems that receive digital data that might contain errors. The use of error-correcting codes has proven tobe an effective way to overcome data corruption in digital communication channels. In previous works, researchers describe the Viterbi Algorithm, but the accuracy does not exceed 10% of data points. Also, a lot of previous works do not follow IEEE 802.16 new specifications. Viterbi decoders are generally implemented using programmable digital signal processors (DSPs) or special purpose chip sets and application-specific integrated circuits (ASICs). Here, we aim to implement …

Modeling, Fabrication, And Optimization Of Niobium Cavities: Phase Ii, Robert A. Schill Jr., Mohamed Trabia

Transmutation Sciences Materials (TRP)

Niobium cavities are important parts of the integrated NC/SC high-power linacs. Over the years, researchers in several countries have tested various cavity shapes. They concluded that elliptically shaped cells are the most appropriate shape for superconducting cavities. The need for very clean surfaces led to the use of a buffered chemical polishing procedure for surface cleaning to get good performance of the cavities. This proposal discusses the second phase of research in the second year of the project.

The first phase (starting Summer 2001) has resulted in improving the basic understanding of multipacting and the process of chemical etching. Based …

Establishing A Lan Network For Designing And Analyzing Of Manufacturing Products, Yuqiu You

Morehead State Theses and Dissertations

A thesis presented to the faculty of the College of Science & Technology at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Science by Yuqiu You in Spring of 2002.

Integrating Passenger And Modulo As Learning Tools For Collaborative Engineering Education, Kalamullah Ramli, Frank Schwarz, Stefan Werner, A Halim Shamsuddin, Axel Hunger

Makara Journal of Technology

The University of Indonesia (UI), Gerhard Mercator University (GMU), the Universiti Kebangsaan Malaysia (UKM) have agreed to cooperate as partners to develop a joint bachelor (3+1) and masters (1+1) degree, and collaborate in the research fi elds of multimedia- and internet-based learning and application level active networks. This paper describes the introduction of the Offshore Project and the extending of information technology applications to the partner institutions in this international cooperation which would very much enhance the operations of the new initiative in engineering education, which could provide students in far distance with more fl exible learning environment.

Study Effect Of Salt Washing Process On Content And Iodium Stability Of Salt, Nelson Saksono

Makara Journal of Technology

Effect of Salt Washing Process on Content and Iodium Stability of Salt. Salt washing process should increase the salt quality. It should clean the salt from sludge or clay and also reduce the impurity compound such as Mg, Ca and the reductor content. The objective of these reseach is to assess the effect of washing process on the content og hygroscopic impurities compound (Ca and Mg), and reductor content of salt. The research also investigate the water absorbing, pH, KIO3 content as function of time to obtain effect of washing process on KIO3 stability in salt. The experiment result shows …

Object Classfification In Computer Vision With Discriminant Analysis, Amir Hamzahan

Makara Journal of Technology

A robotic sensor system is always supported by a computer system called ‘computer vision’. The important concept of computer vision is object classfifi cation. In this study two algorithms for object classifi cation in this system will be compared. Firstly, A simple method that do not need complex computation and that considered as an informal method is called binary tree decision structure. This method is based on modest caracteristic decriptors of an object such as vertical line, horizontal line or ellipse line. Unfortunately this method has weakness in recognize an image that contaminated by a noise. Secondly, a more formal …