Electrical and Computer Engineering Commons^™

Enhanced Luminescence In Ingan Multiple Quantum Wells With Quaternary Alingan Barriers, Jianping Zhang, J. Yang, Grigory Simin, M. Shatalov, M. Asif Khan, M. S. Shur, R. Gaska

Faculty Publications

We report on the comparative photoluminescence studies of AlGaN/GaN, GaN/InGaN, and AlInGaN/InGaN multiple quantum well(MQW) structures. The study clearly shows the improvement in materials quality with the introduction of indium. Our results point out the localized state emission mechanism for GaN/InGaN structures and the quantum well emission mechanism for AlInGaN/InGaN structures. The introduction of indium is the dominant factor responsible for the observed differences in the photoluminescence spectra of these MQW structures.

A Multidisciplinary Polymer Electronics Laborary, David Braun, Kevin Kingsbury, Linda Vanasupa

Electrical Engineering

Semiconducting polymers blend several attractive features that enable inexpensive and unique applications. Forming the subjects of numerous research and development projects, semiconducting polymers also make excellent teaching tools. Since the materials and their applications benefit from intrinsically multidisciplinary approaches, polymer electronics exposes both students and faculty to fruitful interdisciplinary collaboration. This paper introduces semiconducting polymers, tours the Cal Poly polymer electronics lab facility, and summarizes lab projects and course modules completed to date.

High Electron Mobility In Algan/Gan Heterostructures Grown On Bulk Gan Substrates, E. Frayssinet, W. Knap, P. Lorenzini, N. Grandjean, J. Massies, C. Skierbiszewski, T. Suski, I. Grzegory, S. Porowski, Grigory Simin, X. Hu, M. Asif Khan, M. S. Shur, R. Gaska, D. Maude

Faculty Publications

Dislocation-free high-quality AlGaN/GaN heterostructures have been grown by molecular-beam epitaxy on semi-insulating bulk GaN substrates. Hall measurements performed in the 300 K–50 mK range show a low-temperature electron mobility exceeding 60 000 cm²/V s for an electron sheet density of 2.4×10¹²cm⁻². Magnetotransport experiments performed up to 15 T exhibit well-defined quantum Hall-effect features. The structures corresponding to the cyclotron and spin splitting were clearly resolved. From an analysis of the Shubnikov de Hass oscillations and the low-temperature mobility we found the quantum and transport scattering times to be 0.4 and 8.2 ps, respectively. The …

Output Current Ripple Factor Performance Of Half-Wave Rectifier With And Without Freewheeling Diode, Taufik, Ali O. Shaban, Ahmad Nafisi

Electrical Engineering

The objective of this work is to investigate the ripple factor of half-wave rectifier circuits. The ripple factor is one of the important characteristics necessary when designing a power electronic converter. The ripple factor measures how much deviation the converter output parameter has, such as the output current, from its nominal designed value. In this paper the ripple factor of the output current of half-wave rectifiers is investigated. More specifically, the ripple factor of output current from more practical half-wave rectifiers that include inductive load with or without a freewheeling diode are analyzed and then compared to that of the …

A Protocol Language Approach To Generating Client-Server Software, Philip K. Chan, Melvin A.L. Douglas

Electrical Engineering and Computer Science Faculty Publications

Client-server software is becoming more common as the Internet grows. To ease the burden of repeatedly writing low-level communication and protocol code, we seek to design a protocol language, My Simple Protocol Language (MSPL), that produces the corresponding communication functions. The programmer then supplies the rest of the application-specific code but never modifies the generated code. Besides saving development time, this approach also reduces programming errors. The potential to develop more efficient code also exists once the technique of generating code is mastered. The main contribution, however, is that unlike RPC, Corba or RMI, we provide the user with not …

Optical Bandgap Formation In Alingan Alloys, G. Tamulaitis, K. Kazlauskas, S. Juršėnas, A. Žukauskas, M. A. Khan, J. W. Yang, J. Zhang, Grigory Simin, M. S. Shur, R. Gaska

Faculty Publications

We report on the spectral dynamics of the reflectivity, site-selectively excited photoluminescence,photoluminescence excitation, and time-resolved luminescence in quaternary AlInGaN epitaxial layers grown on GaN templates. The incorporation of a few percents of In into AlGaN causes significant smoothening of the band-bottom potential profile in AlInGaN layers owing to improved crystal quality. An abrupt optical bandgap indicates that a nearly lattice-matched AlInGaN/GaN heterostructure with large energy band offsets can be grown for high-efficiency light-emitting devices.

Statcom Control For Power System Voltage Control Applications, Pranesh Rao, Zhiping Yang, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

A static compensator (STATCOM) is a device that can provide reactive support to a bus. It consists of voltage sourced converters connected to an energy storage device on one side and to the power system on the other. In this paper the conventional method of PI control is compared and contrasted with various feedback control strategies. A linear optimal control based on LQR control is shown to be superior in terms of response profile and control effort required. These methodologies are applied to an example power system

Dc Power Bus Design With Fdtd Modeling Including A Dispersive Media, Xiaoning Ye, Jun Fan, Marina Koledintseva, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

DC power-bus modeling in high-speed digital design using the FDTD method is reported here. The dispersive medium is approximated by a Debye model to account for the loss. A wide band frequency response (100 MHz-5 GHz) is obtained through a single FDTD simulation. Favorable agreement is achieved between the modeled and measured results for a typical DC power-bus structure with multiple SMT decoupling capacitors mounted on the board. The FDTD tool is then applied to investigate the effects of local decoupling on a DC power-bus. The modeled results agree with the results from another modeling tool, the CEMPIE (a circuit …

Laboratories Teaching Concepts In Microcontrollers And Hardware-Software Co-Design, Daryl G. Beetner, Hardy J. Pottinger, Kyle Mitchell

Electrical and Computer Engineering Faculty Research & Creative Works

Hardware software co-design is becoming increasingly important to the embedded systems industry. It will soon be fundamental to digital systems design. As such, students in electrical and computer engineering and in computer science should be introduced to hardware-software co-design early in their undergraduate education.

We are designing laboratory modules which introduce concepts of hardware-software co-design in an undergraduate's first course on microcontrollers and digital systems design. Students use design automation tools to develop FPGA-based hardware for use with an 8051-microcontroller and use common software development tools to develop microcontroller software in C or assembly language. Co-simulation of hardware and software …

Dc Power Bus Modeling Using A Circuit Extraction Approach Based On A Mixed-Potential Integral Equation Formulation And An Iterative Equation Solver, Jun Fan, James L. Drewniak, James L. Knighten

Electrical and Computer Engineering Faculty Research & Creative Works

A quick and simple approach is developed to perform circuit simulations for an equivalent circuit extracted from a first principles formulation for DC power bus structures. The simulations are done by solving the system equation using an iterative method. Good agreement between modeling and measurements demonstrate the effectiveness of the method, which is very suitable and computationally efficient for frequency-domain DC power modeling.

Fabrication And Characterization Of Silicon Field Emitter Arrays, Aaron M. Brock

Electrical & Computer Engineering Theses & Dissertations

Field emission is a process through which the application of a large electric field to the surface of a material causes electron emission into vacuum. The electron emission current is a strong function of the geometry of the emitting material. The focus of this thesis is to investigate the effect of geometry on the emission current. Specifically, silicon field emitter arrays were fabricated using two separate fabrication processes termed the standard process and the new process. The uniformity of the arrays was measured experimentally. The arrays were used in field emission tests from which parameters controlling field emission were extracted. …

Studies Related To The Design And Implementation Of A Magnetic Suspension And Balance System, Syed Adeel Akhtar Jafri

Electrical & Computer Engineering Theses & Dissertations

This thesis presents studies related to the magnetic suspension and balance system (MSBS) of the Princeton/ONR High Reynolds Number Testing Facility (HRTF). The main motivation for developing the MSBS is to provide interference free aero/hydrodynamic testing of submersible models, which will lead to more accurate measurements. From the controls point of view, the main specification of the MSBS is to robustly control the position of a submersible model in five degrees of freedom (DOF), including three translational as well as pitching and yawing positions. The MSBS should not only regulate the submersible model's position but should also allow for small …

Design And Rule Base Reduction Of A Fuzzy Filter For The Estimation Of Motor Currents, Daniel J. Simon

Electrical and Computer Engineering Faculty Publications

Fuzzy systems have been used extensively and successfully in control systems over the past few decades, but have been applied much less often to filtering problems. This is somewhat surprising in view of the dual relationship between control and estimation. This paper discusses and demonstrates the application of fuzzy filtering to motor winding current estimation in permanent magnet synchronous motors. Motor winding current estimation is an important problem because in order to implement effective closed-loop control, a good estimation of the current is needed. Motor winding currents are notoriously noisy because of electrical noise in the motor drive. We use …

Lip Feature Extraction Towards An Automatic Speechreading System, Xiaozheng Zhang, Russell M. Mersereau

Electrical Engineering

The use of color information can significantly improve efficiency and robustness of lip feature extraction capability over purely grayscale-based methods. Edge information provides another useful tool in characterizing lip boundaries. In this paper we present a method of integrating both types of information to address the problem of lip feature extraction for the purpose of speechreading. We first examine various color models and view hue as an effective descriptor to characterize the lips due to its invariance to luminance and human skin color, and its discriminative properties. We use prominent red hue as an indicator to locate the position of …

Dielectric Tensor For Interfaces And Individual Layers In Magnetic Multilayer Structures, Xiang Gao, Michael J. Devries, Daniel W. Thompson, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

The magneto-optical Kerr response of metallic magnetic multilayers has been studied by determining the dielectric tensors (dielectric functions) for individual layers, including the magnetic and nonmagnetic interfacial layers. The diagonal components of these tensors were determined using in situ ellipsometric analysis, where the ellipsometric data were taken in real time during multilayer deposition. The off-diagonal components were determined by regression fitting magneto-optic polar Kerr rotation and ellipticity data to models supported by electromagnetic theory. The Voigt parameters (ratio between off-diagonal and diagonal components of dielectric tensors) were determined from these model fits. Higher magnitudes for the Voigt parameters were found …

Performance Monitoring In Umr's Solar Car, Louis Mccarthy, Josh Pieper, Aaron Rues, Cheng-Hsiao Wu

Electrical and Computer Engineering Faculty Research & Creative Works

We describe the instrumentation in UMR's solar car. Accurate knowledge of the operating parameters inside the solar car is shown to be crucial to maintaining high efficiency and reliability. The power trackers keep the solar array operating at its highest efficiency by conditioning the input and maintaining the maximum power point of the solar cells.

Multiresolution Gradient-Based Edge Detection In Noisy Images Using Wavelet Domain Filters, Yunwoo Lee, Samuel Peter Kozaitis

Electrical Engineering and Computer Science Faculty Publications

We detected edges in noisy images using multiresolution analysis with the wavelet transform. Products of wavelet coefficients at several scales were used to identify and locate edges. We found that it was important to consider the changes in edge position at different scales to detect edges in noisy imagery. We analyzed one-dimensional edges and compared the results of our approach with the first derivative of the signal. In addition, we compared the results of noisy images with another wavelet-based edge detection method. Our results led to improved edge detection in noisy images.

Self-Organization In Porous 6h–Sic, S. Zangooie, John A. Woollam, H. Arwin

Department of Electrical and Computer Engineering: Faculty Publications

Pores in porous 6H–SiC were found to propagate first nearly parallel with the basal plane and gradually change direction and align with the c axis. As a consequence, well-defined columnar pores were formed. It was shown that the rate of change of propagation directions was influenced by the etching parameters, such as hydrofluoric acid concentration and current density. Larger currents resulted in formation of larger pores. Pore sizes were found to increase with depth due to a decrease of the acid concentration. In addition, due to chemical etching effects, larger pore sizes were obtained close to the sample surface.

Reduction Of Peak To Average Power Ratio In Ofdm And Ofdm-Cdma System, Jie Cheng

Theses

High Peak to Average Power Ratio is a main problem in Orthogonal Frequency Division Multiplexing(OFDM) system and Orthogonal Frequency Division Multiplexing -Code Division Multiple Access (OFDM-CDMA) system. Considering a compensated High Power Amplifier(HPA), in order to keep linearity for amplification, Input Back-Off(IBO) of the HP-A, has to be increased for handling a high PAPR. Higher 1130 will make HPA less efficient. Additionally, a signal with high PAPR will suffer clipping when PAPR is larger than 1130 of the HPA. Clipping can cause the distortion of the signal and deteriorate the performance of the system. Reduction of PAPR is a main …

Phase Tunability In A Conductor Backed Coplanar Waveguide Patch Antenna, Idan Mandelbaum

Theses

Traditionally beam steering in phase array antenna systems is achieved using tunable phase shifters or switched feed networks. Here, a tunable patch antenna element is suggested as a novel alternative to a combination of a radiating element and a phase shifter. A conductor backed coplanar waveguide patch antenna is chosen due to its suitability to mounted external tuning elements, using varactor diodes. Limited types of lumped tuning circuits, using varactor diodes, have been tested, though a lumped as well as distributed tuning is feasible in the chosen antenna configuration. Approximate analytical models for coplanar waveguide patch antennas with finite ground …

Relative Intensity Noise Characteristics Of Injection-Locked Semiconductor Lasers, Xiaomin Jin, Shun-Lien Chuang

Electrical Engineering

An experimental and theoretical study of relative intensity noise (RIN) spectra of side-mode injection-locked Fabry–Perot semiconductor lasers is reported. It is shown that the injection-locking technique effectively increases the relaxation oscillation frequency from 4.5 GHz (free-running mode) to 12 GHz (injection-locked mode) and enhances relaxation peaks of the slave laser RIN spectra. Results from our theoretical model, which include the key parameters for semiconductor quantum-well lasers, such as the linewidth enhancement factor, the nonlinear gain saturation coefficients, and optical confinement factor, show good agreement with our experimental results.

Cathodic Indirect Oxidation Of Organic Compounds(Ⅱ)——Cathodic Indirect Epoxidation Of Olefine, Xue-Ying Zhang, Bao-Qiu Cui, Deng-Ping Gu, Wei Li

Journal of Electrochemistry

We described a novel cathodic indirect epoxidation system in which O₂ was first cathodically reduced to H₂O₂. Then VO(acac)₂ was oxidized by H₂O₂ homogeneously to VO(acac)₂OOH which was used to epoxidize some olefine such as maleic, fumaric and crotonic acids. Many affecting factors on the current efficiency were optimized. The research will contribute to the developments of organic electrosynthesis.

A Study On The Cylindrical Zinc-Air Battery, Sheng-Sian Li, Gui-Mao Zhou, Xin-Ping Ai, Han-Xi Yang

Journal of Electrochemistry

The zinc air battery has advantages of high specific energies and low cost, therefore attracts much interests. However, its application is limited only in prismatic and button type.This paper reported a novel design of cylindrical zinc air batteries and the performances of the batteries tested at various conditions. The results showed that when discharged at the current of 40 mA at 20 °C, the capacity of AA size and AAA size batteries reached 4000mAh and 1400mAh respectively, corresponding to the energy densities 280 Wh/kg and 200 Wh/kg. The effects of the discharge current, temperature and humidity on the performances of …

Algan/Gan Metal-Oxide-Semiconductor Heterostructure Field-Effect Transistors On Sic Substrates, M. Asif Khan, X. Hu, A. Tarakji, Grigory Simin, J. Yang, R. Gaska, M. S. Shur

Faculty Publications

We report on AlGaN/GaN metal–oxide–semiconductor heterostructurefield-effect transistors (MOS-HFETs) grown over insulating 4H–SiC substrates. We demonstrate that the dc and microwave performance of the MOS-HFETs is superior to that of conventional AlGaN/GaN HFETs, which points to the high quality of SiO₂/AlGaNheterointerface. The MOS-HFETs could operate at positive gate biases as high as +10 V that doubles the channel current as compared to conventional AlGaN/GaN HFETs of a similar design. The gate leakage current was more than six orders of magnitude smaller than that for the conventional AlGaN/GaN HFETs. The MOS-HFETs exhibited stable operation at elevated temperatures up to 300 …

Studies Of The LialYNi1-YO2 As Cathode Materials For Rechargeable Lithium Ion Batteries, Xiao-Gan Li, Wei-Hua Qiu, Chuan-Gang Lin, Qing-Guo Liu

Journal of Electrochemistry

In this paper, we have synthesized series of single-phase LiAl_yNi_1-yO₂ (differentive in value-y) by solid reaction. Through examining their electrothemical properties, found that, under a proper sintering condition, Li_xAl_0.25Ni_0.75O₂ solution for cathode materials of rechargeable lithium ion batteries showed more pleasing properties in overcharge-resist and cycling life (vs LiNiO₂). When x>1, the capacity can be kept 125mAh/g after 30 cycles under higher charged/discharged voltages ranging from 3.0 V to 4.8 V, whereas that of pure LiNiO₂ has only 61 nAh/g after 25 cycles. The …

The Study On Lithiated Titanium Composite Oxides As Negative Electrode For Lithium-Ion Battery, Xiao-Yan Yang, Shou-Nan Hua, Shu-Yong Zhang

Journal of Electrochemistry

Lithiated titanium composite oxides Li₄Ti₅O₁₂ were prepared from Li₂CO₃ and TiO₂. The XRD results of this composite oxides indicated that the compound had a spinel structure. The electrochemical behavior of lithiated titanium composite oxides was examined. The results showed that this material had an excellent cyclic capability and reversibility for lithium insertion, and had high specific capacity: the initial discharge capacity was 300 mAh·g^-1 , and the reversible capacity was 100 mAh·g^-1 . The discharge plateau (about 1.5 V) and the charge plateau (about 1.6 V) were very …

The Effect Of Cerium On The Anodic Behavior Of Pb-Ca-Sn Alloy In Sulfuric Acid Solution, Hou-Tian Liu, Jiong Yang, Hai-He Liang, Ji-Hua Zhuang, Wei-Fang Zhou

Journal of Electrochemistry

The cyclic voltammograms for Pb - 0.5 at% Ca - 1.5 at% Sn and Pb - 0.5 at% Ca - 1.5 at% Sn containing a certain amount of cerium in 4.5 mol·dm^-3 H₂SO₄ at 20℃ were measured between 0.6 V and 1.4 V(vs. Hg/Hg₂SO₄). The growth rate of the anodic Pb(Ⅱ) films formed on the mentioned alloy electrodes at 0.9 V in the same sulfuric acid medium was investigated using the Linear Sweep Voltammetry. The variation with electrode potential of the real part of the impedence (Z’) for the anodic Pb(Ⅱ) films …

The Electro-Catalytic Oxidation Of Hcooh On Electrodeposited Pd Electrode, Quan Zhou, Cun-Zhong Zhang, Xiao-Lin Lu, Zhong-Da Wu

Journal of Electrochemistry

The coherent electroplates were prepared by electro depositing Pd on supporting materials glassy carbon. The surface morphology of the electrodes was examined by SEM. The electro oxidation of HCOOH in HClO₄ solution was investigated by using cyclic voltammetry. The results show that the deposited conditions in the preparation of electrodes by electro depositing Pd affect the electrodes electro catalytic activity to the oxidation of HCOOH. The platinized Pd electrode on GC substrates using large current density is of higher catalytic activity to the oxidation of HCOOH than Pd electrode. The electro catalytic activity of PdO formed on the Pd …

A Study On Stochastic Resonance For The Process Of Active-Passive Transition Of Iron In Sulfuric Acid, Hong-Bo Ding, Bao-Yun Xia, Chun-Sheng Yin, Zhong-Xiao Pan, Renato Seeber

Journal of Electrochemistry

The bistable characteristics of the process of active passive transition of iron in sulfuric acid was described and the stochastic resonance phenomenon in the process was simulated.

Synthesis Of Li1+XMn2O4 Cathode Material For Lithium-Ion Batteries With Solution Method, Pei-Song Liu, Sing-Quarn Liu, Qing Li, Zhao-Yong Chen, Bai-Lan Zhang, Zuo-Long Yu

Journal of Electrochemistry

The cathode materials Li_1+xMn₂O₄ were prepared with citric acid complexing and solution impregnating methods. Structure characterization and specific surface area test were performed by means of XRD, BET methods, the influences of calcination temperature, Li/Mn molar ratio and raw materials on the structure and electrochemical capacity of samples have beem examined. The results showed that the Li/Mn molar ratio and calcimation temperature were the key factors affecting the electrochemical capacity of cathode materias. The optimum conditions for synthesis of  Li_1+xMn₂O₄ cathode material were 0≤x≤0.05 and calcined at 750°C. The initial …