Computer Engineering Commons^™

System And Method For Improving Data Acquisistion Capability In Spectroscopic Rotatable Element, Rotating Element, Modulation Element, And Other Ellipsometer And Polarimeter And The Like Systems, Steven E. Green, Craig M. Heringer, Blaine D. Johs, John A. Woollam, Stephen P. Ducharme

Department of Electrical and Computer Engineering: Faculty Publications

Disclosed is a System and method for controlling polarization State determining parameters of a polarized beam of light in an ellipSometer or polarimeter and the like System, (e.g. a modulation element ellipsometer System), So that they are in ranges wherein the Sensitivity, (of a Sample system characterizing PSI and DELTA value monitoring detector used to measure changes in Said polarization State resulting from interaction with a “composite Sample System,” comprised of a Sample System per Se.. and a beam polarization State determining variable retarder, to noise and measurement errors etc. therein), is reduced. The present invention allows determining Sample System …

Implementation And Performance Of Error Correction Codes For High-Speed Computer Networks, Jochen Spengler

Dissertations and Theses

During the transmission of data there is always a possibility that errors occur and some pieces are modified. If the receiver detects an error it either sends a request for retransmission or, like in networks using Ethernet, it does not send an acknowledgment for the erroneous frame. In this case the sender waits a certain time and retransmits the frame. With the development of faster computer networking hardware and the need for more real-time applications, these errors have become a major concern. Long retransmission latencies and the need for large memories for buffering drive the development of more reliable network …

Guest Editorial: Special Section On Acousto-Optic Devices And Optical Information Processing: Research And Developments, Partha P. Banerjee, Ting-Chung Poon

Electrical and Computer Engineering Faculty Publications

This guest editorial provides an overview of the topical area and an introduction to the articles featured in the special section.

Laser Beam Profile Deformation Effect During Bragg Acousto-Optic Interaction: A Non-Paraxial Approximation, Ray S. Huang, Chen-Wen Tarn, Partha P. Banerjee, Doungchin Cao

Electrical and Computer Engineering Faculty Publications

It is commonly known that the spatial profiles of the diffracted light beams during Bragg acousto-optic interaction are distorted due to the Bragg angle selection mechanism. All the conventional studies on this effect use the paraxial approximation. But this approximation should be amended when the incident angle of the light is large enough that the diffracted light waves do not propagate closely along the optic axis of the acousto-optic diffraction system. By using a spatial Fourier transform approach, we rigorously study the light beam profile deformation effect of the diffracted light during the Bragg acousto-optic interaction beyond the paraxial approximation. …

Examination Of Beam Propagation In Misaligned Holographic Gratings And Comparison With The Acousto-Optic Transfer Function Model For Profiled Beams, Monish Ranjan Chatterjee, David D. Reagan

Electrical and Computer Engineering Faculty Publications

A transfer function formalism developed earlier for the propagation of profiled optical beams through acousto-optic Bragg cells is revisited and applied to a thick holographic grating. The results based on the holographic coupled wave model and the acousto-optic multiple scattering model are shown to be compatible, and equivalent parameters such as the Q and grating strength are defined for the two systems. Results for a Gaussian spatial profile are numerically computed and compared. For the holographic grating, a profiled beam may be interpreted as an angular misalignment or Bragg-angle mismatch problem. The case of Bragg-wavelength mismatch is also investigated for …

An Analytical Approximation For The Excess Noise Factor Of Avalanche Photodiodes With Dead Space, Majeed M. Hayat, Zikuan Chen, Mohammad Rezaul Karim

Electrical and Computer Engineering Faculty Research and Publications

Approximate analytical expressions are derived for the mean gain and the excess noise factor of avalanche photodiodes including the effect of dead space. The analysis is based on undertaking a characteristic-equation approach to obtain an approximate analytical solution to the existing system of recurrence equations which characterize the statistics of the random multiplication gain. The analytical expressions for the excess noise factor and the mean gain are shown to be in good agreement with the exact results obtained from numerical solutions of the recurrence equations for values of the dead space reaching up to 20% of the width of the …

Performance Analysis Of Tcp Enhancements In Satellite Data Networks, Ren H. Broyles

Theses and Dissertations

This research examines two proposed enhancements to the well-known Transport Control Protocol (TCP) in the presence of noisy communication links. The Multiple Pipes protocol is an application-level adaptation of the standard TCP protocol, where several TCP links cooperate to transfer data. The Space Communication Protocol Standard - Transport Protocol (SCPS-TP) modifies TCP to optimize performance in a satellite environment. While SCPS-TP has inherent advantages that allow it to deliver data more rapidly than Multiple Pipes, the protocol, when optimized for operation in a high-error environment, is not compatible with legacy TCP systems, and requires changes to the TCP specification. This …

Constructive Induction Machines For Data Mining, Marek Perkowski, Stanislaw Grygiel, Qihong Chen, Dave Mattson

Electrical and Computer Engineering Faculty Publications and Presentations

"Learning Hardware" approach involves creating a computational network based on feedback from the environment (for instance, positive and negative examples from the trainer), and realizing this network in an array of Field Programmable Gate Arrays (FPGAs). Computational networks can be built based on incremental supervised learning (Neural Net training) or global construction (Decision Tree design). Here we advocate the approach to Learning Hardware based on Constructive Induction methods of Machine Learning (ML) using multivalued functions. This is contrasted with the Evolvable Hardware (EHW) approach in which learning/evolution is based on the genetic algorithm only.

Combining Wavelets And Hotelling Transforms In Image Query, Sol Neeman Ph.D.

Engineering Studies Faculty Publications and Creative Works

In the "content based" image query, also referred to as "query by example," "similarity retrieval" or "sketch retrieval," the query image is provided by the user either as a sketch of the object, as the output of a scanner or a video camera. Some of the difficulties associated with content based image query are described in [1], e.g. significant difference between the "query image" and the "target image," artifacts and poor resolution of the query image make a straightforward comparison of images using L1 and l2 metrics not effective.

In [2] a new strategy is suggested based on wavelet decomposition …

On The Global Stabilization Of Nonlinear Systems Via Switching Manifolds, Stephen P. Banks, Meti̇n U. Salamci, M. Kemal Özgören

Turkish Journal of Electrical Engineering and Computer Sciences

The global stabilization of nonlinear systems is investigated by using switching surfaces. The nonlinear system is forced to a lower order switching manifold, which is designed to be stable by construction. Thus, the stability of the reduced-order system is guaranteed and parameter selection for the switching surface is avoided. The method is extended to a class of uncertain nonlinear systems and exemplified with some fictitious dynamic models.

A Simple Formula Obtained Using Tabu Search Algorithm For The Radiation Efficiency Of A Resonant Rectangular Microstrip Antenna, Dervi̇ş Karaboğa, Keri̇m Güney

Turkish Journal of Electrical Engineering and Computer Sciences

A new simple formula for the radiation efficiency of a resonant rectangular microstrip patch antenna is presented. The formula is obtained by using a tabu search algorithm, which is a quite new optimization technique based on the principles of intelligent problem solving. The formula is valid for substrates with relative permittivities between 1 and 12.8 and for the complete range of thicknesses normally used. The results obtained by using this new simple formula are in conformity with those reported elsewhere. The formula can also be used in the calculation of the radiation efficiency of dipoles.

Effects Of Parasitic Elements On Oscillation Frequency Of Ota-C Sinusoidal Oscillators, Ari̇f Nacaroğlu, Ergun Erçelebi̇

Turkish Journal of Electrical Engineering and Computer Sciences

An oscillator circuit which incorporates Operational Transconductance Amplifiers is presented. The circuit is designed using three OTAs and two grounded capacitors. The frequency of oscillation is tunable over a wide frequency range. The effects of the parasitic elements on the oscillation frequency and the oscillation condition are studied. The theoretical results are compared with the experimental results for a practical oscillator circuit.

Differentiating Type Of Muscle Movement Via Ar Modeling And Neural Network Classification, Beki̇r Karlik

Turkish Journal of Electrical Engineering and Computer Sciences

The aim of this study is to classify electromyogram (EMG) signals for controlling multifunction proshetic devices. An artificial neural network (ANN) implementation was used for this purpose. Autoregressive (AR) parameters of $a_1, a_2, a_3, a_4$ and their signal power obtained from different arm muscle motions were applied to the input of ANN, which is a multilayer perceptron. At the output layer, for 5000 iterations, six movements were distinguished at a high accuracy of 97.6%.

Exclusive Disjunctions In Indefinite And Maybe Information In Relational Databases, Taflan İ. Gündem

Turkish Journal of Electrical Engineering and Computer Sciences

Incorporating indefinite information into databases has been studied extensively. In this paper, we propose a structure called an E-table to represent maybe information and inclusive and exclusive disjunctions. We define the type of redundancies in E-tables and show how to eliminate them. Also we present an extended relational algebra to operate on E-tables. In this paper we expand the concepts and operations defined by Lin and Sunderraman [1] in order to accommodate exclusive disjunctions in relational databases.

Complete Maps Of The Aspect Sensitivity Of Vhf Atmospheric Radar Echoes, R. M. Worthington, R. D. Palmer, S. Fukao

Department of Electrical and Computer Engineering: Faculty Publications

Using the MU radar at Shigaraki, Japan (34.85°N, 136.10°E), we measure the power distribution pattern of VHF radar echoes from the mid-troposphere. The large number of radar beam-pointing directions (320) allows the mapping of echo power from 0° to 40° from zenith, and also the dependence on azimuth, which has not been achieved before at VHF wavelengths. The results show how vertical shear of the horizontal wind is associated with a definite skewing of the VHF echo power distribution, for beam angles as far as 30° or more from zenith, so that aspect sensitivity cannot be assumed negligible at any …

Reduction Of Quantum Noise In Transmittance Estimation Using Photonecorrelated Beams, Majeed M. Hayat, Adel Joobeur, Bahaa E.A. Saleh

Electrical and Computer Engineering Faculty Research and Publications

The accuracy of optical measurements at low light levels is limited by the quantum noise of the source and by the random nature of the interaction with the measured object. The source noise may be reduced by use of nonclassical photon-number squeezed light. This paper considers the use of two photon-correlated beams (generated, for example, by spontaneous parametric downconversion) to measure the optical transmittance of an object. The photons of each beam obey a random Poisson process, but are synchronized in time. One beam is used to probe the object while the other is used as a reference providing information …

Self-Enhancement Of Dynamic Gratings In Photogalvanic Crystals, Nickolai Kukhtarev, Sergei F. Lyuksyutov, Preben Buchhave, Tatiana Kukhtareva, K. Sayano, Partha P. Banerjee

Electrical and Computer Engineering Faculty Publications

We have developed a compact closed-form solution of the band transport model for high-contrast gratings in photogalvanic crystals. Our solution predicts the effect of the photoconductivity and the electric field grating enhancement due to the photogalvanic effect. We predict a pronounced dependence of the steady-state photogalvanic current on the contrast of the interference pattern and an increase of holographic storage time due to the enhancement of the photoconductivity grating contrast. In the high contrast limit and a large photogalvanic effect the refractive index grating will be shifted from the position of the intensity modulation pattern, contrary to the usually adopted …

Experimental Investigations Of Wavelength And Angular Errors In Holographic Gratings With Non-Bragg-Matched Read Beams, Monish Ranjan Chatterjee, Vivek Ray

Electrical and Computer Engineering Faculty Publications

Perfect Bragg matching is generally desirable for accurate optical interconnections with holographic gratings. In reality, however, gratings may be illuminated by READ beams with non-Bragg-matched angles, or wavelengths, or both. In such cases, the scattered beams are generally misdirected, and may suffer loss of efficiency and possibly more serious errors such as crosstalk noise or missed connections. A conventional wave-vector triad method of analyzing the scattered beam errors leads readily to near-Bragg estimates of the output angular misalignment. However, the READ wave-vector triads appear to indicate a possible wavelength shift in the output beam even with a Bragg-matched READ wavelength, …

The Cluster Multipole Algorithm For Far-Field Computations, Rakesh R. Patel

Electrical & Computer Engineering Theses & Dissertations

Computer simulations of N-body systems are beneficial to study the overall behavior of a number of physical systems in fields such as astrophysics, molecular dynamics, and computational fluid dynamics. A new approach for computer simulations of N-body systems is proposed in this research. The new algorithm is called the Cluster Multipole Algorithm (CMA). The goals of the new algorithm are to improve the applicability to non-point sources and to provide more control on the accuracy over current algorithms. The algorithm is targeted to applications that do not require rebuilding the data structure about the system every time step due to …

System And Method For Performing Optical Code Division Multiple Access Communication Using Bipolar Codes, James F. Young, Benhaam Aazhnag, Lim Nguyen

Department of Electrical and Computer Engineering: Faculty Publications

An optical encoding and decoding system which performs code-division multiple access (CDMA) communication in the incoherent, or direct detection, optical domain using bipolar +1/-1 codes. The present invention uses code modu lation and detection principles that permit all-optical imple mentation of the bipolar. +1/-1. code and correlation detec tion that have been developed for the radio frequency (RF) systems. This is possible in spite of the non-negative, or unipolar, +1/0, nature of the incoherent optical system that only detects and processes the signal intensity. The unipolar optical system of the present invention is equivalent to the bipolar RF system in …

Joint Wavelet Transform Correlation With Separated Target And Reference Planes, Boon Yi Soon, Mohammad A. Karim, Russell C. Hardie, Mohammad S. Alam

Electrical and Computer Engineering Faculty Publications

In recent years, we realize the usefulness of feature extraction for optical correlator and hereby, we investigate the capability of Laplace operator in feature extraction of multiple targets. The first-order terms and the false alarm terms in the correlation output would be removed using electronic power spectrum subtraction technique. Most importantly, the entire magneto-optic SLM is completely utilized for displaying only targets in the input scene. A new cost efficient hardware implementation is proposed and aforementioned result of the proposed system is evaluated through computer simulation.

Design, Performance, And Applications Of A Coherent Ultra-Wideband Random Noise Radar, Ram M. Narayanan, Yi Xu, Paul D. Hoffmeyer, John O. Curtis

Department of Electrical and Computer Engineering: Faculty Publications

A novel coherent ultra-wideband radar system operating in the 1- to 2-GHz frequency range has been developed recently at the University of Nebraska. The radar system transmits white Gaussian noise. Detection and localization of buried objects is accomplished by correlating the reflected waveform with a time-delayed replica of the transmitted waveform. Broadband dual-polarized log-periodic antennas are used for transmission and reception. A unique signal-processing scheme is used to inject coherence into the system by frequency translation of the ultrawideband signal by a coherent 160-MHz phase-locked source prior to performing heterodyne correlation. The system coherence allows the extraction of a target’s …

Electromagneticbeamdirecting Means-Sampleanalyss System Stage, And Method Of Use, Daniel W. Thompson, 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 reflectometers, 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 of extensive 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.

Apparatus And Method For Detection And Concentration Measurement Of Trace Metals Using Laser Induced Breakdown Spectroscopy, Dennis R. Alexander

Department of Electrical and Computer Engineering: Faculty Publications

A method and apparatus for in situ detection and concentration measurement of trace elements in an analysis Sample is disclosed. The invention uses laser induced breakdown spectroscopy (LIBS) wherein femtosecond pulsed laser energy is employed to produce the plasma. The femtosecond pulsed laser energy is focused on the analysis Sample to produce the plasma and the resulting emission is delivered for spectral analysis. Because the method and apparatus of the present invention allow breakdown of the analysis Sample without propagation of energy to the Sample-air interface, a plasma is produced that consists essentially of Sample materials without being contaminated by …

Attitude Measurement, Mark A. Stedham, Partha P. Banerjee, Seiji Nishifuji, Shogo Tanaka

Electrical and Computer Engineering Faculty Publications

In many practical situations, it is important to determine and measure the attitude of a particular vehicle, such as a ship, an airplane, a piece of mechanical equipment such as a, crane lifter, or a spacecraft. For this reason, many attitude sensors have been developed with advanced computer and semiconductor technologies. This section first introduces the various attitude sensors with an explanation of their operating principles and then presents several methodologies for attitude measurement and determination, including ships and crane lifters, aircraft, and spacecraft applications.

Functional Radionuclide Imaging Algorithm Based On The Appended Curve Deconvolution Technique And Its Use In The Diagnosis Of Renovascular Hypertension, İrfan Karagöz, Hi̇kmet Bayhan

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, a new method called the pixel basis functional radionuclide imaging (PBFRI) algorithm based on the appended curve deconvolution technique, in order to be able to increase the medical diagnostic capability of a conventional gamma camera, is presented together with the clinical results. In the PBFRI method, retention function of each pixel is obtained from the renograms and cardiac curves generated by processing the filtered segments of the kidney and heart, using a special deconvolution method. The deconvolution operation is done by using the Fourier transform technique. High frequency artifacts presented by the Fourier transform are removed by …

Genetic Approach For The Determination Of Object Parameters From X Ray Projections, Tayfun Günel, Sedef Kent

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, a new method is presented, based on genetic algorithms for determining object parameters such as radii and/or attenuation coefficients with some assumptions and estimating a cross-sectional image of an object from its projections obtained by X ray illumination. After it was tested for projections degraded by different random noise levels, it was observed that the genetic and fuzzy genetic algorithms improved the signal to noise ratio of the projections. The fuzzy genetic algorithm gave better results than the genetic algorithm.

An Interoperability Infrastructure For Developing Multidatabase Systems, Asuman Doğac, Gökhan Özhan, Ebru Kılıç, Fatma Özcan, Sena Nural, Sema Mancuhan, Cevdet Dengi, Pınar Köksal, Uğur Halıcı, Budak Arpınar, Cem Evrendilek, Vahid Sadjadi

Turkish Journal of Electrical Engineering and Computer Sciences

A multidatabase system (MDBS) allows the users to simultaneously access autonomous, heterogeneous databases using a single data model and a query language. This provides for achieving interoperability among heterogeneous, federated DBMSs. In this paper, we describe the interoperability infrastructure of a multidatabase system, namely METU Interoperable DBMS (MIND). The architecture of MIND is based on OMG distributed object management model. It is implemented on top of a CORBA compliant ORB, namely, ObjectBroker. The interface of the generic database object is defined in CORBA IDL and multiple implementations of this interface, one for each component DBMSs, namely, Oracle 7, Sybase, Adabas …

Performance Of Prefiltered Model-Based Frequency Estimators, Mustafa A. Altınkaya, Bülent Sankur, Emin Anarım

Turkish Journal of Electrical Engineering and Computer Sciences

In this work, the performance improvement due to prefiltering of inputs in model-based frequency estimators is investigated based on simulation experiments. Initial estimates on the tone frequency locations, which are obtained via DFT peak picking type preanalysis, are used to design a prefilter to remove noise and interference. The simulations indicate that prefiltering can improve the accuracy of Pisarenko and AR frequency estimators and MUSIC and KT frequency estimators with low subspace order significantly. The SNR thresholds of model-based frequency estimators are lowered by prefiltering. Additionally, interesting trade-offs between prefiltering gain and the gain due to subspace noise filtering have …

Analysis Of Images Of Cells With Neurites, Florence Cloppet, Georges Stamon

Turkish Journal of Electrical Engineering and Computer Sciences

This study is concerned with the segmentation of cytological images and extraction of cellular entities in order to provide quantitative data about the number of cells in culture (statistical tests, morphology, model of evolution, etc). This quantitative supply is useful in biology to evaluate the consequences of the application of active substances on morphological changes and cellular viability. It is related to the conception of a system dedicated to automatic analysis of cell images, in order to evaluate the effects of drugs on the morphology of neuronal cells. We use a cooperative region / contour segmentation, which gives closed polygonal …