Engineering Commons^™

Manufacture Of 1 Kw Molten Carbonate Fuel Cell Stack, Sheng Sui, Xin-Jian Zhu, Zheng-Yu Fan, Cao Guang-Yi And

Journal of Electrochemistry

A molten carbonate fuel cell stack with an active area of 240 mm×140 mm consisted of 30 cells.The gas feed system works via interior manifolds,and the stack placed in a couple of self-chest,coupled with a heater at the bottom and other fours surrounded,to keep uniformity of temperature.Under ambient pressure and 650 ℃,fed with hydrogen and air as anode and cathode gases respectively,the stack gave a current density of 150 mA/cm 2 at an average cell voltage of 0.7 V.The peak output of the stack was 1.06 kW during its performance of 300 h.

Lithium Intercalation Performance Of P-Doped Phenolic Resin Pyrolysis Carbon, Bao-Hua Li, Kai-Xi Li, Yonggen Lv, Chun-Xiang Lv, Dong Wu, Li-Cheng Ling

Journal of Electrochemistry

Phosphorus-doped phenolic resin carbon was prepared by low temperature(700 ℃)pyrolysis of thermoplastic phenolic resin containing different amounts of phosphorus pentoxide after curing. X-ray diffraction pattern and the constang-current charge-discharge properties of phenolic resin carbon were studied. The results showed that the phenolic resin carbon microstructure became out of order with increasing of content phosphorus pentoxide,otherwise,the first discharge reversible capacities increased firstly and then decreased. The first discharge reversible capacity of phenolic resin carbon containing 9wt% phosphorus pentoxide was 528 mA·h·g -1 which was higher than that of non-phosphorus doped phenolic resin carbon(230 mA·h·g -1 ) did.

Properties Of Domestic Natural Graphite Used For Li-Ion Batteries, Cui-Wei Du, Yu-Juan Zhao, Gang Zhang, Yin-Shun Wu, Qing-Guo Liu

Journal of Electrochemistry

The structure, physical characteristics and electrochemical properties of the natural graphite produced in Shandong province have been studied. The result of X-ray diffraction showed that the graphite consisted of hexagonal structure and rhombic structure (30% rhombic structure). It was fine crystal graphite. Used as a negative material of Lithium ion battery, the natural graphite showed excellent voltage and high energy capacity, but poor compatibility with electrolyte solution containing propylene carbonate (PC) for its own structure limitation.

Steady State Simulation Of Ysz Intermediate-Temperature Fuel Cell, Zi-Jing Lin, Ye Gu, Xiao-Hua Zhang

Journal of Electrochemistry

With a coupled 2D electrochemical and thermal modeling software, the characteristics of the steady state operation of the intermediate-temperature fuel cell with thin yttria-stabilized zirconia(YSZ) electrolyte was analyzed. The parameters of I-V equation were obtained from fitting the experiment results and the choice of grid points was determined by balancing the accuracy requirement and computational efficiency. The temperature fields at different operation circumstances such as flow designs, material choices for interconnect, were examined. The dependences of the output power and cell efficiency on the operating voltage at different temperatures were studied. Based upon the analysis of the temperature profile, it …

Polarization Effects In Photoluminescence Of C- And M-Plane Gan/Algan Multiple Quantum Wells, E. Kuokstis, C. Q. Chen, M. E. Gaevski, W. H. Sun, J. W. Yang, Grigory Simin, M. Asif Khan, H. P. Maruska, D. W. Hill, M. C. Chou, J. J. Gallagher, B. Chai

Faculty Publications

Polarizationeffects have been studied in GaN/AlGaN multiple quantum wells(MQWs) with different c-axis orientation by means of excitation-dependent photoluminescence(PL) analysis. Quantum structures were grown on [0001]-oriented sapphire substrates (C plane) and single-crystalline [11̄00]-oriented freestanding GaN (M plane) using the metalorganic chemical vapor deposition technique. Strong PL spectrum line blueshifts (up to 140 meV) which are correlated with the excitation intensity have been obtained for C-plane MQWs, whereas no shift has been observed for M-plane MQWs.Theoretical calculations and comparison with the PL data confirm that the built-in electric field for C-plane structures is much stronger than the field present for M-plane MQWs. …

Determination Of Whole-Body Specific Absorption Rate (Sar) And Characterization Of Ferris Wheel Radio Frequency (Rf) Exposure System Using Calorimetric Techniques, Subbarao V. Chebrolu

FIU Electronic Theses and Dissertations

The "Ferris Wheel" RE Exposure System was designed by Motorola Inc. to study the long-term biological effects due to RE exposure [3]. The main goal of this research project was to characterize the "Ferris Wheel" to know how efficient and symmetrical was the exposure system in distributing the RE power among its loads. The characterization of the system was done in terms of power efficiency, SAR, Whole-Body SAR and Localized SAR.

Exposure to RF sources is quantified in terms of SAR which defines the rate of electromagnetic deposition per unit mass. Determination of Whole-Body averaged SAR requires to have the …

Illuminating Electronics Problem Solving With The Cal Poly Mohat Technique, David Braun, Fred W. Depiero, Michael Borland

Electrical Engineering

This paper describes a Cal Poly version of circuit analysis to assist both students and instructors. The primary focus of the technique is helping students perform hand analysis, particularly the type of hand analysis that clarifies the student’s understanding of circuit operation in a manner that can benefit subsequent design decisions. The technique nicely complements graphical solution techniques such as load-line analyses and computer aided circuit simulation. MoHAT, an abbreviation of Model-Hypothesize-Analyze-Test, provides students with a roadmap to use, when analyzing even relatively complex circuits containing diodes and transistors. This paper emphasizes the pedagogy of MoHAT and describes a web-based …

Source Localization In A Time-Varying Ocean Waveguide, Cristiano Soares, Martin Siderius, Sérgio M. Jesus

Electrical and Computer Engineering Faculty Publications and Presentations

One of the most stringent impairments in matched-field processing is the impact of missing or erroneous environmental information on the final source location estimate. This problem is known in the literature as model mismatch and is strongly frequency dependent. Another unavoidable factor that contributes to model mismatch is the natural time and spatial variability of the ocean waveguide. As a consequence, most of the experimental results obtained to date focus on short source-receiver ranges (usually <5 >km), stationary sources, reduced time windows and frequencies generally below 600 Hz. This paper shows that MFP source localization can be made robust to time–space …

Numerical Simulation Of Partial Discharge Propagation In Cable Joints Using The Finite Difference Time Domain Method, David Pommerenke, R. Jobava, R. Heinrich

Electrical and Computer Engineering Faculty Research & Creative Works

In this second of a series of three papers, the authors investigate partial discharge (PD) detection and propagation in cable joints. The complex nature of cable joints leads to errors when PD analysis is carried out using conventional equivalent circuits. The authors use the finite difference time domain method to determine the transient electromagnetic fields caused by simulated PD in model cable joints.

Electromagnetic Scattering From A Gap In A Magneto-Dielectric Coating On An Infinite Ground Plane, George R. Simpson

Theses and Dissertations

The electromagnetic scattering from a gap in a magneto-dielectric coating on an infinite ground plane is analyzed. In this context, the gap forms a break only in the magneto-dielectric slab coating while the ground plane is continuous and unbroken. Volume equivalence is used to convert the gap region to one containing unknown volumetric equivalent electric and magnetic currents. The equivalent problem then is one of these currents radiating in the presence of an unbroken grounded magneto-dielectric slab. A Green's function for this geometry is developed consisting of two terms: a direct coupling term and correction term to account for the …

Delivering On The 256 Qam Promise, Ron D. Katznelson

Ron D. Katznelson

The accumulation of degradation factors in the downstream channels is reviewed with focus on headend/hub transmission-related noise aggregation due to a plurality of downstream Quadrature Amplitude Modulation (QAM) transmitters and upconverters. Substantial increase in the number of QAM transmitters based on frequency agile upconverters is expected. Unlike fixed channel upconverters, these do not have narrow band filters at their output, consequently imparting appreciable levels of broadband noise on the network when several such units are combined. Based on these factors and other noise contributions, it is shown that additional impairments due to fluctuations associated with composite distortion terms on the …

Gan Homoepitaxy On Freestanding (11̄00) Oriented Gan Substrates, C. Q. Chen, M. E. Gaevski, W. H. Sun, E. Kuokstis, J. P. Zhang, R. S. Q. Fareed, H. M. Wang, J. W. Yang, Grigory Simin, M. A. Khan, Herbert-Paul Maruska, David W. Hill, Mitch M. C. Chou, Bruce Chai

Faculty Publications

We report homoepitaxialGaNgrowth on freestanding (11̄00) oriented (M-plane GaN) substrates using low-pressure metalorganic chemical vapor deposition.Scanning electron microscopy,atomic-force microscopy, and photoluminescence were used to study the influence of growth conditions such as the V/III molar ratio and temperature on the surface morphology and optical properties of the epilayers. Optimized growth conditions led to high quality (11̄00) oriented GaN epilayers with a smooth surface morphology and strong band-edge emission. These layers also exhibited strong room temperature stimulated emission under high intensity pulsed optical pumping. Since for III-N materials the (11̄00) crystal orientation is free from piezoelectric or spontaneous polarization electric fields, …

Optical Constants And Roughness Study Of Dc Magnetron Sputtered Iridium Films, Li Yan, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

Extremely smooth thin films of iridium have been deposited onto superpolished fused silica substrates using dc magnetron sputtering in an argon plasma. The influence of deposition process parameters on film microroughness has been investigated. In addition, film optical constants have been determined using variable angle spectroscopic ellipsometry, over the spectral range from vacuum ultraviolet to middle infrared (140 nm–35 μm). Because the Ir films were optically thick and the surface roughnesses were measured by atomic force microscopy then accounted for in the optical model, the as-determined film optical constants are expected to be the best available for Ir bulk metals, …

Low-Temperature Operation Of Alfan Single-Quantum-Well Light-Emitting Diodes With Deep Ultraviolet Emission At 285 Nm, A. Chitnis, R. Pachipulusu, V. Mandavilli, M. Shatalov, E. Kuokstis, J. P. Zhang, V. Adivarahan, S. Wu, Grigory Simin, M. Asif Khan

Faculty Publications

We present a study of the electrical and optical characteristics of 285 nm emission deep ultraviolet light-emitting diodes(LED) at temperatures from 10 to 300 K. At low bias, our data show the tunneling carrier transport to be the dominant conduction mechanism. The room-temperature performance is shown to be limited mostly by poor electron confinement in the active region and a pronounced deep level assisted recombination but not by the hole injection into the active region. At temperatures below 100 K, the electroluminescence peak intensity increases by more than one order of magnitude indicating that with a proper device design and …

Learning Implicit User Interest Hierarchy For Context In Personalization, Philip K. Chan, Hyoung-Rae Kim

Electrical Engineering and Computer Science Faculty Publications

To provide a more robust context for personalization, we desire to extract a continuum of general (long-term) to specific (short-term) interests of a user. Our proposed approach is to learn a user interest hierarchy (UIH) from a set of web pages visited by a user. We devise a divisive hierarchical clustering (DHC) algorithm to group words (topics) into a hierarchy where more general interests are represented by a larger set of words. Each web page can then be assigned to nodes in the hierarchy for further processing in learning and predicting interests. This approach is analogous to building a subject …

"Estimación De Variables De Estado De Órbita Satelital Con Filtro De Kalman Extendido", Fabricio I. Salgado, E. Amthauer

Fabricio I. Salgado MSc.

Abstract: this paper presents the formulation of Extended Kalman Filter, Continuous-Discreet case (C-D EKF) and his application to the determination of state of satelite orbit, verifies the performance of the algorithm when it exists a good model for the process and measurement. It is observed the influence of the passage of integration in the estimation and importance that gives to the algorithm to the predictions and measurements.

Pattern Recognition For Electric Power System Protection, Yong Sheng

Doctoral Dissertations

The objective of this research is to demonstrate pattern recognition tools such as decision trees (DTs) and neural networks that will improve and automate the design of relay protection functions in electric power systems. Protection functions that will benefit from the research include relay algorithms for high voltage transformer protection (TP) and for high impedance fault (HIF) detection. A methodology, which uses DTs and wavelet analysis to distinguish transformer internal faults from other conditions that are easily mistaken for internal faults, has been developed. Also, a DT based solution is proposed to discriminate HIFs from normal operations that may confuse …

Training Radial Basis Neural Networks With The Extended Kalman Filter, Daniel J. Simon

Electrical and Computer Engineering Faculty Publications

Radial basis function (RBF) neural networks provide attractive possibilities for solving signal processing and pattern classification problems. Several algorithms have been proposed for choosing the RBF prototypes and training the network. The selection of the RBF prototypes and the network weights can be viewed as a system identification problem. As such, this paper proposes the use of the extended Kalman filter for the learning procedure. After the user chooses how many prototypes to include in the network, the Kalman filter simultaneously solves for the prototype vectors and the weight matrix. A decoupled extended Kalman filter is then proposed in order …

Range-Dependent Seabed Characterization By Inversion Of Acoustic Data From A Towed Receiver Array, Martin Siderius, Peter L. Nielsen, Peter Gerstoft

Electrical and Computer Engineering Faculty Publications and Presentations

The MAPEX2000 experiments were conducted in the Mediterranean Sea in March, 2000 to determine seabed properties using a towed acoustic source and receiver array. Towed systems are advantageous because they are easy to deploy from a ship and the moving platform offers the possibility for estimating spatially variable (range-dependent) seabed properties. In this paper, seabed parameters are determined using a matched-field geoacoustic inversion approach with measured, towed array data. Previous research has successfully applied matched-field geoacoustic inversion techniques to measured acoustic data. However, in nearly all cases the inverted data were collected on moored, vertical receiver arrays. Results here show …

Metrics-Based Framework For Decision Making In Cots-Based Software Systems, Sahra Sedigh, Arif Ghafoor, Raymond A. Paul

Electrical and Computer Engineering Faculty Research & Creative Works

The growing reliance on Commercial-Off-The-Shelf (COTS) components for developing large-scale projects introduces a new paradigm in software Engineering; which requires the design of new software development and business processes. Large scale component reuse leads to savings in development resources, enabling these resources to be applied to areas such as quality improvement. These savings come at the price of integration difficulties, performance constraints, and incompatibility of components from multiple vendors. Relying on COTS components also increases the system's vulnerability to risks arising from third-party development, which can negatively affect the quality of the system, as well as causing expenses not incurred …

Application Of Maxwell Solvers To Pd Propagation. I. Concepts And Codes, David Pommerenke, S. Sakaguchi

Electrical and Computer Engineering Faculty Research & Creative Works

This article reviews the basic approaches to solving electromagnetic propagation in the context of PD detection. It also investigates available commercial software, introduces the steps required to obtain trustworthy computational results, and gives an example of detailed analysis of PD propagation.

Recurring Beams In Hollow Metal Waveguides: Paraxial Approximation, Lee W. Casperson

Electrical and Computer Engineering Faculty Publications and Presentations

For optical and near-optical applications in electromagnetics, the directed propagation of waves in free space and in lenslike media is often in the Cartesian form of Gaussian or more general Hermite-sinusoidal-Gaussian beams. It has been shown that recurring (rather than continuing) forms of such beams are possible in the paraxial approximation for certain hollow metal waveguides, in which multiple reflections from the waveguide walls may occur. Limitations on this recurrence behavior implicit in use of the paraxial approximation are considered here, and estimates are obtained for the maximum propagation distance before the onset of significant distortion of the recurring beams.

Near-Band-Edge Photoluminescence Of Wurtzite-Type Aln, E. Kuokstis, J. Zhang, Q. Fareed, J. W. Yang, Grigory Simin, M. Asif Khan, R. Gaska, M. Shur, C. Rojo, L. Schowalter

Faculty Publications

Temperature-dependentphotoluminescence(PL)measurements were performed for A-plane and C-plane bulk AlN single crystals and epitaxial layers on sapphire. A strong near-band-edge (NBE) emission and deep-level luminescence were observed. At low excitations, the emission spectra are dominated by free and bound excitonic transitions and their LO-phonon replicas. At high excitations, the broadening and redshift of the NBE band is attributed to dense electron–hole plasma formation. The PL spectra differences of bulk single crystals and epilayers is explained by the electron–hole plasma expansion peculiarities.

Self-Assembled Networks With Neural Computing Attributes, Supriyo Bandyopadhyay, L. Menon, N. Kouklin, P. F. Williams, Natale J. Ianno

P. F. (Paul Frazer) Williams Publications

Two-dimensional arrays of vertical quantum wire Esaki tunnel diodes, laterally connected to their nearest neighbors by resistive/capacitive connections, constitute a powerful and versatile neuromorphic architecture that can function as classical Boolean logic circuits, associative memory, image processors, and combinatorial optimizers. In this paper, we discuss the basic philosophy behind adopting this architecture for nanoelectronic circuits and report on our experimental progress towards synthesizing this system.

An Algorithm Applicable To Clearing Combinatorial Exchanges, Marius Silaghi

Electrical Engineering and Computer Science Faculty Publications

It is important to approach negotiations in a way that ensures privacy. So far, research has focused on securely solving restricted classes of negotiation techniques, mainly the (M+1)-st-price auctions. Here we show how these results can be adapted to more general problems. This paper extends our previous results on how distributed finite discrete problems can be solved securely. Such problems can model larger classes of negotiation problems, .e.g. Combinatorial Exchanges [Sil02]. In Finite Discrete Maximization, each tuple in the problem space is associated with an integer value in a predefined interval and we search for a maximizing input. Values from …

Performance Analysis Of A Maximum-Likelihood Speckle Motion Estimator, Donald D. Duncan, Sean J. Kirkpatrick

Electrical and Computer Engineering Faculty Publications and Presentations

Presented herein is a performance analysis of a maximum likelihood estimator for calculating small speckle motions. Such estimators are important in a variety of speckle techniques used in non-destructive evaluation. The analysis characterizes the performance (bias and RMS deviation) of the estimator as a function of the signal-to-noise ratio. This SNR parameter is a convenient surrogate for decorrelation of sequential speckle patterns such as are seen in biological tissues. Although the particular estimator is predicated on speckle motions that are a small fraction of a pixel, accurate performance is demonstrated for instantaneous motions of up to ±0.8 pixel/record. Beyond this …

Network Traffic Anomaly Detection Based On Packet Bytes, Philip K. Chan, Matthew V. Mahoney

Electrical Engineering and Computer Science Faculty Publications

Hostile network traffic is often "different" from benign traffic in ways that can be distinguished without knowing the nature of the attack. We describe a two-stage anomaly detection system for identifying suspicious traffic. First, we filter traffic to pass only the packets of most interest, e.g., the first few packets of incoming server requests. Second, we model the most common protocols (IP, TCP, telnet, FTP, SMTP, HTTP) at the packet byte level to flag events (byte values) that have not been observed for a long time. This simple system detects 132 of 185 attacks in the 1999 DARPA IDS evaluation …

Shared-Data Or Message Passing Computing Models – A Human Factor In Technical Choices, Angela Sodan, Luiz Fernando Capretz

Electrical and Computer Engineering Publications

No abstract provided.

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

Transmutation Sciences Materials (TRP)

Multipacting is one of the major loss mechanisms in rf superconductivity cavities for accelerators. This loss mechanism limits the maximum amount of energy/power supported by the cavities. Optimal designs have been identified in others’ studies. In practice, these designs are not easily manufactured. Chemical etching processes used to polish the cavity walls result in a nonuniform surface etch. A nonuniform surface etch will leave some unclean areas with contaminants and micron size particles. These significantly affect mutipacting. Further, a nonuniform etch will leave areas with damaged grain structure, which is not good for superconducting properties. Typically, the depth of chemical …

Comparison Of Open- And Closed-Loop Process Identification Techniques In The Time-Domain, Tony Kealy, Aidan O'Dwyer

Conference papers

Abstract: This paper describes seven methods to identify a mathematical model for a real process with a time delay. The process is the Process Trainer, PT326 from Feedback Instruments Limited. Six of the methods use the step response data and one of the methods uses the impulse response data for identification.