Digital Commons Network^™

Effect Of Multiuser Interference On Subscriber Location In Cdma Networks, Rohit Sharma

LSU Master's Theses

The last few years have witnessed an ever growing interest in the field of mobile location systems for cellular systems. The motivation is the series of regulations passed by Federal Communications Commission, requiring that wireless service providers support a mobile telephone callback feature and cell site location mechanism. A further application of the location technology is in the rapidly emerging field of intelligent transportation systems, which are intended to enhance highway safety, location based billing etc. Many of the existing location technologies use GPS and its derivatives which require a specialized subscriber equipment. This is not feasible for popular use, …

Knowledge-Based Fault Detection Using Time-Frequency Analysis, Venkata S. Vongala

LSU Master's Theses

This work studies a fault detection method which analyzes sensor data for changes in their characteristics to detect the occurrence of faults in a dynamic system. The test system considered in this research is a Boeing-747 aircraft system and the faults considered are the actuator faults in the aircraft. The method is an alternative to conventional fault detection method and does not rely on analytical mathematical models but acquires knowledge about the system through experiments. In this work, we test the concept that the energy distribution of resolution than the windowed Fourier transform. Verification of the proposed methodology is carried …

Performance Based Switching Control For Single Input Linear Time Invariant Systems, Lalitha Srigouri Devarakonda

LSU Master's Theses

In the present research, we propose a new control strategy to improve the performance of a linear time invariant single input system. We consider a performance index that is dependent only on the controlled variable and try to improve it over that obtained when using a stable state feedback control. Since the control law depends on the performance of the controlled variable, we call it Performance Based Switching Control (PBSC). Switching between two state feedbacks is used to achieve this improvement in performance. The switching strategy combines the best features of both strategies. The switching surface is actually composed of …

New Optimal High Efficiency Dsp-Based Digital Controller Design For Super High-Speed Permanent Magnet Synchronous Motor, Limei Zhao

Electronic Theses and Dissertations

This dissertation investigates digital controller and switch mode power supply design for super high-speed permanent magnet synchronous motors (PMSM). The PMSMs are a key component for the miniaturic cryocooler that is currently under development at the University of Central Florida with support from NASA Kennedy Space Center and the Florida Solar Energy Center. Advanced motor design methods, control strategies, and rapid progress in semiconductor technology enables production of a highly efficient digital controller. However, there are still challenges for such super high-speed controller design because of its stability, high-speed, variable speed operation, and required efficiency over a wide speed range. …

The Effects Of Electrode Geometry On Current Pulse Caused By Electrical Discharge Over An Ultra-Fast Laser Filament, Matthew Bubelnik

Electronic Theses and Dissertations

The time-resolved electrical conductivity of a short-pulse generated plasma filament in air was studied. Close-coupled metal electrodes were used to discharge the stored energy of a high-voltage capacitor and the resulting microsecond-scale electrical discharge was measured using fast current sensors. Significant differences in the time dependence of the current were seen with the two electrode geometries used. Using sharp-tipped electrodes additional peaks in the time-resolved conductivity were seen, relative to the single peak seen with spherical electrodes. We attribute these additional features to secondary electron collisional ionization brought about by field enhancement at the tips. Additional discrepancies in the currents …

A New Hybrid Diffractive Photo-Mask Technology, Jin Won Sung

Electronic Theses and Dissertations

In the field of photolithography for micro-chip manufacturing, the photo-mask is used to print desired patterns on a proper photo-resist on wafer. The most common type of photo-mask is binary amplitude mask made an opaque layer of chrome. The principle and potential application of hybrid photo-mask with diffractive phase element and binary amplitude is presented in this dissertation paper from both numerical modeling and experimental research. The first important application is the characterization of aberration in the stepper system using hybrid diffractive photo-mask. By utilizing multiple diffractive illumination conditions, it is possible to characterize Zernike wave front aberration coefficients up …

Spectral Signature Modification By Application Of Infrared Frequency-Selective Surfaces, Brian Monacelli

Electronic Theses and Dissertations

It is desirable to modify the spectral signature of a surface, particularly in the infrared (IR) region of the electromagnetic spectrum. To alter the surface signature in the IR, two methods are investigated: thin film application and antenna array application. The former approach is a common and straightforward incorporation of optically-thin film coatings on the surface designated for signature modification. The latter technique requires the complex design of a periodic array of passive microantenna elements to cover the surface in order to modify its signature. This technology is known as frequency selective surface (FSS) technology and is established in the …

Liquid Crystal Optics For Communications, Signal Processing And 3-D Microscopic Imaging, Sajjad Khan

Electronic Theses and Dissertations

This dissertation proposes, studies and experimentally demonstrates novel liquid crystal (LC) optics to solve challenging problems in RF and photonic signal processing, freespace and fiber optic communications and microscopic imaging. These include free-space optical scanners for military and optical wireless applications, variable fiber-optic attenuators for optical communications, photonic control techniques for phased array antennas and radar, and 3-D microscopic imaging. At the heart of the applications demonstrated in this thesis are LC devices that are non-pixelated and can be controlled either electrically or optically. Instead of the typical pixel-by-pixel control as is custom in LC devices, the phase profile across …

Characterisation, Modelling And Performance Evaluation Of Cmos Integrated Rf-Mems Multielectrode Tunable Capacitor, Zbigniew Olszewski

Theses

The circuits used in telecommunications are made of two types of components; active integrated circuits that have continuously been improved together with the evolution of the Si technology and off-chip and on-chip passive components. The latter did not profit from much development and now constitute the bottleneck for further integration of RF (Radio Frequency) integrated circuits. MicroElectroMechanical Systems (MEMS) is rapidly emerging as an enabling technology to yield a new generation of high performance components to replace off-chip (not integrated) and on-chip (poor performance) counterparts. The RF components (RF-MEMS) that can be fabricated with MEMS technology are mainly the resonator, …

Robust Colour Segmentation Under Dynamic Lighting Conditions, Noreen Mary Looney

Theses

Traditionally, the issue of colour constancy has limited the success of colour image segmentation algorithms. Numerous methods exist to achieve colour constancy for different applications. The principal contribution of this thesis is the investigation of a suitable technique for the problem of robust colour based object detection.

Appropriate colour models are investigated and analysed in order to assess their ability to enhance the isolation process. Models that possess suitable colour constancy characteristics are chosen for use with image segmentation algorithms. Reviews of existing sur\'eys of image segmentation algorithms are appraised for the emergence of a suitable colour image segmentation technique. …

An Optimum Hardware Detector For Constant Envelope Quadrature-Quadrature Phase Shift Keying (Ceq2osk), Kenneth V. Cartwright, Edit J. Kaminsky

Electrical Engineering Faculty Publications

A hardware detector for constant envelope quadrature- quadrature phase-shift keying (CEQ2PSK) is proposed. It uses appropriate hard decisions; yet, it achieves optimum probability of bit error performance, unlike the suboptimum detector of Saha and Birdsall. This optimum performance is verified through Monte Carlo computer simulations. Additionally, a more correct expression is given for the probability of bit error performance for CEQ2PSK, which gives the gain over nonconstant Q2PSK as 1.44 dB, rather than the previously published value of 1.76 dB.

Flexible Multiobjective Control Of Power Converter In Active Hybrid Fuel Cell/Battery Power Sources, Zhenhua Jiang, Lijun Gao, Roger A. Dougal

Faculty Publications

Hybrid power sources composed of fuel cells and secondary batteries can combine the high energy density of fuel cells with the high power density of batteries. A dc/dc power converter can be placed between the fuel cell and the battery to balance the power flow and greatly augment the peak output power. This paper presents a novel, flexible strategy for multiobjective control of the power converter in the hybrid power source. The control strategy is able to regulate the output current of the fuel cell and the charging current or voltage of the battery while limiting the discharging current of …

Design And Assessment Of Compact Optical Systems Towards Special Effects Imaging, Vesselin Chaoulov

Electronic Theses and Dissertations

A main challenge in the field of special effects is to create special effects in real time in a way that the user can preview the effect before taking the actual picture or movie sequence. There are many techniques currently used to create computer-simulated special effects, however current techniques in computer graphics do not provide the option for the creation of real-time texture synthesis. Thus, while computer graphics is a powerful tool in the field of special effects, it is neither portable nor does it provide work in real-time capabilities. Real-time special effects may, however, be created optically. Such approach …

Tunable Liquid Crystal Photonic Devices, Yun-Hsing Fan

Electronic Theses and Dissertations

Liquid crystal (LC)-based adaptive optics are important for information processing, optical interconnections, photonics, integrated optics, and optical communications due to their tunable optical properties. In this dissertation, we describe novel liquid crystal photonic devices and their fabrication methods. The devices presented include inhomogeneous polymer-dispersed liquid crystal (PDLC), polymer network liquid crystals (PNLC) and phase-separated composite film (PSCOF). Liquid crystal/polymer composites could exist in different forms depending on the fabrication conditions. In Chap. 3, we demonstrate a novel nanoscale PDLC device that has inhomogeneous droplet size distribution. In such a PDLC, the inhomogeneous droplet size distribution is obtained by exposing the …

System Design And Optimization Of Optical Coherence Tomography, Avni Ceyhun Akcay

Electronic Theses and Dissertations

Optical coherence imaging, including tomography (OCT) and microscopy (OCM), has been a growing research field in biomedical optical imaging in the last decade. In this imaging modality, a broadband light source, thus of short temporal coherence length, is used to perform imaging via interferometry. A challenge in optical coherence imaging, as in any imaging system towards biomedical diagnosis, is the quantification of image quality and optimization of the system components, both a primary focus of this research. We concentrated our efforts on the optimization of the imaging system from two main standpoints: axial point spread function (PSF) and practical steps …

Interferometry-Based Free Space Communication And Information Processing, Muzamil Arshad Arain

Electronic Theses and Dissertations

This dissertation studies, analyzes, and experimentally demonstrates the innovative use of interference phenomenon in the field of opto-electronic information processing and optical communications. A number of optical systems using interferometric techniques both in the optical and the electronic domains has been demonstrated in the filed of signal transmission and processing, optical metrology, defense, and physical sensors. Specifically it has been shown that the interference of waves in the form of holography can be exploited to realize a novel optical scanner called Code Multiplexed Optical Scanner (C-MOS). The C-MOS features large aperture, wide scan angles, 3-D beam control, no moving parts, …

Optical Wave Propagation In Discrete Waveguide Arrays, Jared Hudock

Electronic Theses and Dissertations

The propagation dynamics of light in optical waveguide arrays is characteristic of that encountered in discrete systems. As a result, it is possible to engineer the diffraction properties of such structures, which leads to the ability to control the flow of light in ways that are impossible in continuous media. In this work, a detailed theoretical investigation of both linear and nonlinear optical wave propagation in one- and two-dimensional waveguide lattices is presented. The ability to completely overcome the effects of discrete diffraction through the mutual trapping of two orthogonally polarized coherent beams interacting in Kerr nonlinear arrays of birefringent …

High Gain / Broadband Oxide Glasses For Next Generation Raman Amplifiers, Clara Rivero

Electronic Theses and Dissertations

Interest in Raman amplification has undergone a revival due to the rapidly increasing bandwidth requirements for communications transmission, both for long haul and local area networks, and recent developments in the telecom fiber industry and diode laser technology. In contrast to rare earth doped fiber amplifiers, for which the range of wavelengths is fixed and limited, Raman gain bandwidths are larger and the operating wavelength is fixed only by the pump wavelength and the bandwidth of the Raman active medium. In this context, glasses are the material of choice for this application due to their relatively broad spectral response, and …

Coherence Properties Of Optical Near-Fields, Adela Apostol

Electronic Theses and Dissertations

Next generation photonics-based technologies will ultimately rely on novel materials and devices. For this purpose, phenomena at subwavelength scales are being studied to advance both fundamental knowledge and experimental capabilities. In this dissertation, concepts specific to near-field optics and experimental capabilities specific to near-field microscopy are used to investigate various aspects of the statistical properties of random electromagnetic fields in the vicinity of optically inhomogeneous media which emit or scatter radiation. The properties of such fields are being characterized within the frame of the coherence theory. While successful in describing the far-field properties of optical fields, the fundamental results of …

Liquid Crystal Materials And Tunable Devices For Optical Communications, Fang Du

Electronic Theses and Dissertations

In this dissertation, liquid crystal materials and devices are investigated in meeting the challenges for photonics and communications applications. The first part deals with polymer-stabilized liquid crystal (PSLC) materials and devices. Three polymer-stabilized liquid crystal systems are developed for optical communications. The second part reports the experimental investigation of a novel liquid-crystal-infiltrated photonic crystal fiber (PCF) and explores its applications in fiber-optic communications. The curing temperature is found to have significant effects on the PSLC performance. The electro-optic properties of nematic polymer network liquid crystal (PNLC) at different curing temperatures are investigated experimentally. At high curing temperature, a high contrast, …

Control Algorithms For Large Scale Adaptive Optics, Piotr Piatrou

Dissertations, Master's Theses and Master's Reports - Open

In this dissertation, the problem of creating effective large scale Adaptive Optics (AO) systems control algorithms for the new generation of giant optical telescopes is addressed. The effectiveness of AO control algorithms is evaluated in several respects, such as computational complexity, compensation error rejection and robustness, i.e. reasonable insensitivity to the system imperfections. The results of this research are summarized as follows:

1. Robustness study of Sparse Minimum Variance Pseudo Open Loop Controller (POLC) for multi-conjugate adaptive optics (MCAO). The AO system model that accounts for various system errors has been developed and applied to check the stability and performance …

A Realization Of Sc-Cnn-Based Circuit Using Ftfn, Eni̇s Günay, Esma Uzunhi̇sarcikli, Recai̇ Kiliç, Mustafa Alçi

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a realization of the State Controlled Cellular Neural Network (SC-CNN)-based circuit using Four Terminal Floating Nullor (FTFN) as active element is presented. In this realization, a new version of autonomous Chua's circuit has been considered using FTFN realization of SC-CNN-based circuit. The performance of the proposed SC-CNN-based circuit is demonstrated by PSpice simulations.

Prior Knowledge Input Method In Device Modeling, Serdar Heki̇mhan, Serdar Menekay, N. Serap Şengör

Turkish Journal of Electrical Engineering and Computer Sciences

The artificial neural networks are being used in modelling electronic elements and devices especially at microwave frequencies where non-linearity and dependence on frequency cannot be neglected. In this paper, instead of using artificial neural networks as a unique modelling device prior knowledge input method based on feed-forward artificial neural network structures as multi-layer perceptrons and wavelet-based neural networks is investigated. The benefits of prior knowledge input method over plain usage of artificial neural networks in modelling BJT is explored by comparing models obtained with and without prior knowledge input. The novelty of the paper is utilizing wavelet-based neural networks as …

Transformer Protection Using The Wavelet Transform, Okan Özgönenel, Güven Önbi̇lgi̇n, Çağri Kocaman

Turkish Journal of Electrical Engineering and Computer Sciences

This paper introduces a novel approach for power transformer protection algorithm. Power system signals such as current and voltage have traditionally been analysed by the Fast Fourier Transform. This paper aims to prove that the Wavelet Transform is a reliable and computationally efficient tool for distinguishing between the inrush currents and fault currents. The simulated results presented clearly show that the proposed technique for power transformer protection facilitates the accurate discrimination between magnetizing inrush and fault currents in transformer protection.

Multilayer Capacitor Model Of The Earth's Upper Crust, Berk Üstündağ, Özcan Kalenderli̇, Haluk Eyi̇doğan

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, an equivalent electric circuit model of Earth's upper crust is proposed to explain the behavior of measurement patterns acquired from network of the earthquake forecast project. A multi-layer capacitor model having active components that couples with the monopolar probe close to the surface is used to determine earthquake precursory patterns due to structural changes in time. Equivalent circuit model was developed for a) dilatency process that is assumed to be a stress weakening reason and b) external force source that increases shear stress over the fault until sudden decrement before the earthquake. A data acquisition system consisting …

A Robustness Analysis Procedure For Realistic Missiles, Reşat Özgür Doruk, Erol Kocaoğlan

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a robustness analysis procedure for short range realistic missile autopilots. The sensitivity of the autopilots to the aerodynamic parameter uncertainties is investigated through the structured singular value theory where the results are verified through nonlinear simulations. Different types of perturbations are implemented in order to measure the complete performance of the missile.

Implementation Of A New Self-Tuning Fuzzy Pid Controller On Plc, Onur Karasakal, Engi̇n Yeşi̇l, Müjde Güzelkaya, İbrahi̇m Eksi̇n

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, the self-tuning method for fuzzy PID controllers that has been developed in a previous study of the authors is implemented on PLC in order to control some standard processes formed on FEEDBACK PCS 327 Process Control Simulator. In this tuning method, the input scaling factor corresponding to the derivative coefficient and the output scaling factor corresponding to the integral coefficient of the fuzzy PID controller are adjusted using a fuzzy inference mechanism with a new input called ``normalized acceleration''. The results of the implementation have been compared with those of the classical fuzzy PID controller without a …

A Survey On The H.264/Avc Standard, Nükhet Özbek, Turhan Tunali

Turkish Journal of Electrical Engineering and Computer Sciences

H.264/AVC is a recently completed video compression standard jointly developed by ITU-T VCEG and ISO/IEC MPEG standards committees. The standard is becoming more popular as it promises much higher compression than that possible with earlier standards. The standard provides flexibilities in coding and organization of data which enable efficient error resilience. The increased coding efficiency offers new application areas and business opportunities. As might be expected, the increases in compression efficiency and flexibility come at the expense of increase in complexity, which is a fact that must be overcome. This paper provides an overview of the technical features of H.264 …

Control Charts Approach For Scenario Recognition In Video Sequences, Ersi̇n Elbaşi, Long Zuo, Kishan Mehrotra, Chilukuri Mohan, Pramod Varshney

Turkish Journal of Electrical Engineering and Computer Sciences

A new approach, based on control charts, is presented for the task of recognition of events and scenarios in video image sequences. For each image in the sequence, low level image processing and feature extraction steps result in feature descriptors for objects of interest detected in the images. Control charts analysis is then explored to classify the nature of the activity depicted by the temporal changes in these features over the image sequence. Scenario recognition with higher accuracy is achieved using this simple approach.

A Model For User Profiling Systems With Interacting Agents, Sanem Sariel, Tevfi̇k Akgün

Turkish Journal of Electrical Engineering and Computer Sciences

Service systems according to users' personal demands and preferences are on their way to provide required services in many application domains. Emulation of interactive model of human societies produces valuable outcomes for such systems. In this work, a system model with interactive agents for multi user service systems is proposed. A novel social interactive agent model using different interaction forms is also included in this proposal. In this model, agents decide how to serve to their users by considering their users' profiles and information from other agents. User clusters are formed by clustering techniques. The Q-learning algorithm is used for …