Engineering Commons^™

Electromagnetic Scattering From Coated Strips Utilizing The Adaptive Multiscale Moment Method, C. Shu, T. K. Sarkar

Electrical Engineering and Computer Science - All Scholarship

The aim of this paper is to consider the problem of electromagnetic scattering from perfectly conducting strips coated with thin dielectric material by use of the adaptive multiscale moment method (AMMM). In the next section, the basic formulation is presented for analysis of scattering from coated conducting strips on the basis of a coupled system of electric- and magnetic-field integral equations. Section 3 outlines the computational methodology of the multiscale basis by use of the moment method. Section 4 presents AMMM to solve the coupled EM integral equations. Section 5 presents a variety of numerical examples for different coating strips …

My Methanol Motorcycle, Art Maccarley

Electrical Engineering

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Square Spiral Conformal Microstrip Antennas For Space Vehicles, Nahid Dehestani

HIM 1990-2015

The research deals with the experimental study of square spiral microstrip antennas over the 5 to 12 GHz range. Square spiral microstrip antennas can provide a wideband reception at frequencies of several gigaHertz. They can, like other microstrip antennas be made conformal and are compact and light weight. Consequently, they are very suitable for use on aircraft and spacecraft. These antennas can be flush mounted to the existing surfaces, and their shape makes them easier to fabricate, and can be mass-produced. The square spiral microstrip antenna is a recent development and has been investigated theoretically through the use of the …

The Design Of Cube Calculus Machine Using Sram-Based Fpga Reconfigurable Hardware Dec’S Perle-1 Board, Qihong Chen

Dissertations and Theses

Presented in this thesis are new approaches to column compatibility checking and column-based input/output encoding for Curtis decompositions of switching functions. These approaches can be used in Curtis-type functional decomposition programs for applications in several scientific disciplines. Examples of applications are: minimization of combinational and sequential logic) mapping of logic functions to programmable logic devices such as CPLDs, MPGAs, and FPGAs, data encryption, data compression, pattern recognition) and image refinement. Presently, Curtis-type functional decomposition programs are used primarily for experimental purposes due to performance, quality, and compatibility issues. However) in the past few years a renewal of interest in the …

Object-Oriented Computer Simulations Of Physical Systems Using Dual Reciprocity Boundary Element Methodology, J. Friedrich

Turkish Journal of Electrical Engineering and Computer Sciences

Models of physical systems are essential in every engineering field. This work deals with computer simulations of physical systems that can be mathematically modelled by differential equations together with sufficient boundary conditions. The computer simulations are based on object-oriented technology and the dual reciprocity boundary element method which is a universal solution scheme for various types of partial differential equations (e.g. Laplace, Poisson, diffusion, convection-diffusion, and steady Navier-Stokes equation). This technique fulfills efficiency criteria like precision, robustness, versatility, programmability, user-friendliness, need of computational time and computer memory to a very high degree. This is demonstrated by three examples: Laplace's solution …

Distribution System Planning Usign Mixed Integer Programming, Belgin Türkay

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents an improved mathematical model to optimise the size and locations of substations and the network routing problem. The model was formulated to minimise the total cost of the network by determining the optima of the substation locations and power, the load transfers between the demand centers, the feeder routes and the load flow in the network subject to a set of constraints. The computational results of a devised sample problem indicate that the developed optimisation model and its code are adequate for computer aided planning of distribution systems.

Analysis Of Nonlinear Sustained Oscillations In Discrete Systems With Backlash And Resolution By Using A Discretization-Oriented Describing Function, M. De La Sen, A. Pena, J. Esnaola

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a discretization-oriented describing function is derived for nonlinear devices combining backlash and quantization (resolution) while being subject to discretization through a sampler and zero-order hold. Such a describing function is frequency-dependent so that the overall nonlinearity, which includes both resolution and backlash, is interpreted as possessing nonlinear inertia. That nonlinear inertia is generated by the sampling process, since it does not appear if the system is continuous. The presence of nonlinear sustained oscillations (limit cycles) is investigated through simulations.

Signal Injection With Perceptual Criteria, T. Engi̇n Tuncer

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a novel method for increasing the coding performance and information transmission capacity is presented. This method is mainly based on perceptual modelling of input signal such as speech or audio. Presented approach may be seen as an alternative to transforms which dynamically change analysis window for better energy compaction. A perceptual model is established in order to obtain a global masking threshold in frequency below which sounds become inaudible. Certain criteria are developed for identifying the signal injection bands. A new multiband filter design method which is a generalization of windowing method is used to separate the …

State Of Art In Realistic Head Modeling For Electro-Magnetic Source Imaging Of The Human Brain, Nevzat G. Gençer, İ. Oğuz Tanzer, M. Kemal Özdemi̇r, Can E. Acar, Mert Sungur

Turkish Journal of Electrical Engineering and Computer Sciences

Electric currents produced by the neural activity in the brain create electric potentials on the scalp and magnetic field distribution outside the scalp. Measuring electric and magnetic fields provides a means to understand the spatio-temporal distribution of the neural activity. The representations of the intracellular electric current of active cell populations based on bimodal data are called electro-magnetic source image (EMSI). With the recent development of large arrays of magnetic sensors, and systems for measuring scalp voltages at more than 100 locations, it is now feasible to implement computational methods that employ numerical models which incorporate the correct geometry and …

A Comparison Of Some Low Cost Laminates For Antennas Operating In The 2.45 Ghz Ism Band, Max Ammann

Conference papers

An evaluation of some low-cost laminates suitable for microstrip patch antennas is presented. Criteria for the selection of substrates for antenna fabrication are given careful consideration. A coaxial-probe fed linearly-polarized rectangular microstrip patch operating at a frequency of 2.45 GHz was fabricated on four different low cost laminates. The substrates used were polyester, epoxy glass (FR-4), a ceramic filled PTFE composite and a woven glass-reinforced hydrocarbon and ceramic thermoset material. Material properties are discussed and the antenna performances are evaluated and compared to one fabricated on a thick glass-loaded microfiber PTFE substrate. An evaluation of some inexpensive microstrip antenna CAD …

Microwave Filtering Of Unwanted Oscillations On Base Of Hexagonal Ferrite Composite Thick Films, Marina Koledintseva, Alexander A. Kitaytsev, Andrey A. Shinkov

Electrical and Computer Engineering Faculty Research & Creative Works

The paper is aimed at the design of waveguide filters of lower frequencies using composite thick films (CTF) made of high-anisotropy polycrystalline hexagonal ferrite powders. Theoretical and experimental results describing the possibility of forming the desired frequency characteristic of the filters are presented

Dsp Implementation Of A Quadrature Phase Shift Keying Transmitter, Andrew Phoon

Theses : Honours

The aim of this project is to develop a DSP implementation of a QPSK transmitter. This transmitter is to process digital signals in real-time and modulate it with sinusoidal and cosinusoidal signals to produce the required QPSK waveform. This thesis is mainly divided into three sections. The first section deals with the theory of modulation. Phase shift keying, in particular binary phase shift keying, is explained in some detail, with references to the generation of quadrature phase shift keying. In the second section, a brief overview of the SIMULINK package from MATLAB is given, as simulations of ideal and nonideal …

Surface Morphology Of Laser-Superheated Pb(111) And Pb(100), Z. H. Zhang, Bo Lin, X. L. Zeng, H. E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

The surface step density on the vicinal Pb(111) and the surface vacancy density on Pb(100) after laser superheating and melting are investigated using reflection high-energy electron diffraction. With ∼100-ps laser pulses, Pb(111) surface superheating does not significantly change the density of the steps and step-edge roughness. However, after laser surface melting, the average terrace width and the string length at the step edge become as large as those at room temperature. The average terrace width at 573 K changes from 38±15 to 64±19 Å after laser surface melting, while the average string length at the step edge changes from 90±14 …

Femtosecond Photoemission Study Of Ultrafast Electron Dynamics In Single-Crystal Au(111) Films, J. Cao, Y. Gao, H. E. Elsayed-Ali, R. J. D. Miller, D. A. Mantell

Electrical & Computer Engineering Faculty Publications

The energy-dependent relaxation of photoexcited electrons has been measured by time-resolved two-photon photoemission spectroscopy on single-crystal Au(111) films with thickness ranging from 150 to 3000 Å. It is found that the energy-dependent relaxation does not show any significant thickness dependence, which indicates that electron transport is a much slower dynamical process in the near-surface region than expected from bulk properties. Furthermore, lifetimes of the photoexcited electrons can be fitted well by the Fermi-liquid theory with a scaling factor plus an effective upper lifetime. This observation enables separation of electron-electron scattering, and to a lesser extent electron-phonon scattering, processes from electron-transport …

Modeling Electromagnetic Disturbances In Closed-Loop Computer Controlled Flight Systems, W. Steven Gray, Oscar R. Gonzalez

Electrical & Computer Engineering Faculty Publications

High intensity electromagnetic radiation has been demonstrated to be a source of computer upsets in commercially available digital flight control systems. In this paper we introduce an electromagnetic disturbance model which can be used for stability analysis and augmentation of any such digitally implemented control law. The model is composed of a Markovian exosystem supplying radiation events to a discrete-time jump linear system which models how the radiation interferes with the nominal operation of the closed-loop system. We discuss how this model can be used to characterize stability and how it can be parametrized and validated in an experimental setting.

Gaas Implementation Of Fir Filter, Anup Savla

Theses : Honours

This thesis discusses the findings of the final year project involving Gallium Arsenide implementation of a triangular FIR filter to perform discrete wavelet transforms. The overall characteristics of Gallium Arsenide technology- its construction, behaviour and electrical charactersitics as they apply to VLSI technology - were investigated in this project. In depth understanding of its architecture is required to be able to understand the various design techniques employed. A comparison of Silicon and GaAs performance and other characteristics has also been made to fully justify the choice of this material for system implementation. A lot of research and active interest has …

Electromagnetic Beam Directing Means-Sample Analysis System Stage, And Method Of Use, Daniel W. Thomspon, Darin W. Glenn, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

Disclosed is an electromagnetic beam directing means for use with sample analysis systems, such as relfectometers, ellipsometers and polarimeters and the like, use of which facilitates investigation of sample systems which are not mounted to a sample analysis system sample system supporting stage. The present invention eliminates the requirement os extensice sample analysis system component realignment when alternatingly performing analysis of sample systems mounted upon, and mounted other than upon, a sample analysis system sample system supporting stage.

Performance And Robustness Issues In The Compensation Of Folpd Processes With Pi And Pid Controllers, Aidan O'Dwyer

Conference papers

This paper will discuss the compensation of first order lag plus time delay (FOLPD) processes using PI and PID controllers whose parameters are specified using appropriate tuning rules. The gain margin, phase margin and maximum sensitivity of the compensated system as the ratio of time delay to time constant of the process varies, are used as ways of judging the performance and robustness of the system.

The Gain Scheduled Piece-Wise Adaptive Digital Control Of A Ph Process, Eugene O'Shaughnessy, Aidan O'Dwyer

Conference papers

The compensation of a pH process is complicated by the non-linear nature of the process titration curve and the significant time delays that typically exist in such processes. This paper will propose the use of a gain scheduled piecewise adaptive PI controller to compensate the process. A pilot plant is controlled, with the control algorithm implemented on a programmable controller. SCADA software displays and trends the plant and controller signals.

Excitation Of The Whispering-Gallery-Modes At The Shielded Hemispherical Dielectric Resonator, Sergey Kharkovsky, V. V. Kutuzov, A. E. Kogut, V. A. Solodovnik

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

Voice Recognition Using Neural Networks, Ganesh K. Venayagamoorthy, Viresh Moonasar, K. Sandrasegaran

Electrical and Computer Engineering Faculty Research & Creative Works

One solution to the crime and illegal immigration problem in South Africa may be the use of biometric techniques and technology. Biometrics are methods for recognizing a user based on unique physiological and/or behavioural characteristics of the user. This paper presents the results of ongoing work into using neural networks for voice recognition

A Novel Thin Film Transistor Using Double Amorphous Silicon Active Layer, Jong Hyuni Choi, Chang-Soo Kim, Byung Cheon Lim, Jin Jang

Electrical and Computer Engineering Faculty Research & Creative Works

We have fabricated a novel low off-state leakage current thin-film transistor (TFT) using a chlorine incorporated amorphous silicon [a-Si:H(:Cl)] and amorphous silicon (a-Si:H) stacked active layer, in which conduction channel is formed in a-Si:H and a-Si:H(:Cl) is photo-insensitive material. The off-state photo-leakage current of the a-Si:H(:Cl)/a-Si:H TFT is much lower than that a conventional a-Si:H TFT.

An Improved Method For Incorporating Magnetic Saturation In The Q-D Synchronous Machine Model, Keith Corzine, Brian T. Kuhn, S. D. Sudhoff, H. J. Hegner

Electrical and Computer Engineering Faculty Research & Creative Works

An improved technique for incorporating saturation into the q-d axis model (Park''s model) of a synchronous machine is proposed. By choosing magnetizing flux linkage as a state variable, iterative procedures required by traditional methods are avoided. The saturation function is represented by an arctangent function which has some distinct advantages over polynomial representations and look-up tables. In particular, the parameters of the proposed function all have physical significance and the proposed function is defined over an infinite range of flux linkage. The model is verified for steady-state and transient conditions using a laboratory synchronous machine-rectifier system similar to those commonly …

Formulation Of The Boltzmann Equation As A Multi-Mode Drift-Diffusion Equation, Kausar Banoo, Farzin Assad, Mark S. Lundstrom

Department of Electrical and Computer Engineering Faculty Publications

We present a multi-mode drift-diffusion equation as reformulation of the Boltzmann equation in the discrete momentum space. This is shown to be similar to the conventional drift-diffusion equation except that it is a more rigorous solution to the Boltzmann equation because the current and carrier densities are resolved into M x 1 vectors, where M is the number of modes in the discrete momentum space. The mobility and diffusion coefficient become M M matrices which connect the M momentum space modes. This approach is demonstrated by simulating electron transport in bulk silicon.

Determination Of Head Kinematics From Impact Acceleration Test Data Using Neural Networks, Edit J. Kaminsky, Anwer Bashi

Electrical Engineering Faculty Publications

This paper presents a study of feed-forward neural network (NN) systems developed to determine the head kinematics of subjects who are exposed to impact accelerations. The neural networks process accelerometer data collected during short-duration impact acceleration tests conducted at the National Biodynamcis Laboratory of the University of New Orleans. During an impact acceleration experiment, the subject sits on the sled chair and a piston gives impetus to the sled to travel down a track. Head data is gathered by an array of nine accelerometers. Two more accelerometers are mounted on the sled.

The neural processing systems produce the history of …

A New Radiosonde System For Profiling The Lower Troposphere, Brian R Corner, Robert D. Palmer

Department of Electrical and Computer Engineering: Faculty Publications

A new, inexpensive radiosonde transmitter and receiver system has been developed for measuring wind field inhomogeneities in the planetary boundary layer using multiple simultaneously launched balloons. The radio- sondes use a narrowband-frequency-modulated carrier signal to transmit atmospheric pressure and temperature information to a surface receiver. The pressure and temperature data transmitted by the radiosondes allow their height above the surface to be ascertained. In addition, the radiosondes can be tracked with a photographic camera system to provide the azimuth and elevation angles of the radiosondes during their ascent, so that their three-dimensional horizontal position can be determined. By tracking the …

Optical Determination Of Shallow Carrier Profiles Using Fourier Transform Infrared Ellipsometry, Thomas E. Tiwald, John A. Woollam, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

Dopant profiles were determined by ex situ Fourier transform infrared variable-angle spectroscopic ellipsometry. The technique exploits carrier absorption in the mid-infrared spectral range and combines the sensitivity of ellipsometry with a simple Drude free carrier absorption model to determine the carrier profile. The noncontact, nondestructive nature of the measurement suggests both ex situ and in situ monitoring and control applications. In this study, the carrier profiles were modeled as graded multilayers that can be constrained to a given functional form (Gaussian, erfc, etc.) when desired. Boron and arsenic implanted silicon wafers that were rapid thermal anneal and furnace annealed were …

Data Logging Multiple Aviation Sensors Using A Motorala [Sic] Hc11 Microcontroller, Andrew James Wooding

Theses : Honours

This project is part of the research and development of a microprocessor based integrated instrumentation system for light aircraft. It involves interfacing a Motorola HC 11 microcontroller with several sensor inputs. The project system is designed to data log battery voltage, cylinder head temperature, ambient temperature and engine RPM.

A Study Of Transconductance Degradation In Hemt Using A Self-Consistent Boltzmann-Poisson-Schrodinger Solver, Rahim Khoie

Electrical & Computer Engineering Faculty Research

A self-consistent Boltzmann-Poisson-Schrödinger Solver is used to study the transconductance degradation in high electron mobility transistor (HEMT), which has extensively been reported by both experimental [1]-[8] and computational [9]-[ 13] researchers. As the gate voltage of a HEMT device is increased, its transconductance increases until it reaches a peak value, beyond which, the transconductance is degraded rather sharply with further increase in applied gate bias. We previously reported a two-subband self-consistent Boltzmann-Poisson- Schrödinger Solver for HEMT. [14] We further incorporated an additional self-consistency by calculating field-dependent, energy-dependent intersubband and intrasubband scattering rates due to ionized impurities and polar optical phonons.[15] …

Adaptive Shape From Shading, Ati̇lla Gülteki̇n, Muhi̇tti̇n Gökmen

Turkish Journal of Electrical Engineering and Computer Sciences

Extracting surface orientation and surface depth from one or more images is one of the classic problems in computer vision. Shape-from-shading (SFS) deals with the recovery of 3-D shape from a single shaded image. The shape is recovered by minimizing an energy functional involving constraints such as smoothness. In this constrained problem, although the smoothness constraint helps to stabilize the minimization process, it pushes the reconstruction toward a smooth surface. In this paper, we present a new adaptive shape-from-shading method which reduces this oversmoothing by controlling the smoothness spatially over the image space. In order to improve the quality of …