Electrical and Computer Engineering Commons^™

Blind Phase Recovery In Cross Qam Communication Systems With The Reduced Constellation Eigth-Order Estimator (Rceoe), Kenneth V. Cartwright, Edit J. Kaminsky

Electrical Engineering Faculty Publications

The eighth-order (EOE) phase estimator [4] is modified to work for an eight-symbol symmetrical constellation, so that the large signal-to-noise (SNR) performance is not limited by self-noise. By using only the eight highest energy points of cross- QAM constellations, a reduced constellation eighth-order estimator (RCEOE) is proposed. Computer simulations for 128-QAM show that this new method performs substantially better than the recently introduced APP phase estimator of Wang et al. [8]. However, simulations with 32-QAM show little performance advantage of the RCEOE over the APP estimator, for SNR values normally of interest, whereas for low SNR, the improvement is significant. …

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.

Asymptotic Performance Of The Pth Power-Law Phase Estimator, Kenneth V. Cartwright, Edit J. Kaminsky

Electrical Engineering Faculty Publications

An expression for the true variance of the Pth powerlaw phase estimator, as the number of samples approaches infinity, is given. This expression is an extension to the linear approximation of Moeneclaey and de Jonghe [1] which is known to be inadequate in some practical systems. Our new expression covers general 2π/P-rotationally symmetric constellations that include those of PAM, QAM, PSK, Star M-QAM, MR-DPSK, and others. This expression also generalizes the known expressions for QAM and PSK. Additionally, our expression reduces to the Cramer-Rao bound given by Steendam and Moeneclaey [9], as SNR goes to zero. Monte Carlo simulations provide …

Effects Of A Smaller Unit Cell Planar Ebg Structure On The Mutual Coupling Of A Printed Dipole Array, M. Faisal Abedin, Mohammod Ali

Faculty Publications

A new smaller unit-cell planar electromagnetic bandgap (EBG) structure is proposed on low dielectric constant low-cost substrate (TMM: epsilon(r) = 4.5, thickness = 25 mils) that has a stopband frequency at around 4 GHz. The proposed structure when placed in between a two-element printed dipole array results in over 13-dB reduction in mutual coupling and a significant improvement in antenna return loss bandwidth and gain pattern.

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 …

Crystal Growth, Characterization And Anisotropic Electrical Properties Of Gase Single Crystals For Thz Source And Radiation Detector Applications, K. C. Mandal, C. Noblitt, M. Choi, A. Smirnov, R. D. Rauh

Faculty Publications

The single crystal growth of large semi‐insulating GaSe by the vertical Bridgman technique using zone‐refined selenium (Se) and HP gallium (Ga) is described. The grown crystals (up to 10 cm long and 2.5 cm diameter) have been characterized thoroughly by X‐ray diffraction (XRD), energy dispersive analysis by x‐rays (EDAX), optical absorption/transmission, X‐ray photoelectron spectroscopy (XPS), charge carrier electrical property measurements, second harmonic test, and radiation detection measurements.

Editorial, Robert W. Stewart, Michael W. Hoffman, Stephan Weiss

Department of Electrical and Computer Engineering: Faculty Publications

In the past years, digital signal processing (DSP) algorithms and architectures for baseband communication systems have fuelled the delivery of applications such as 3G mobile communications and wireless LAN to mass markets. This was made possible by a tremendous growth in the performance of computational devices such as digital signal processors and FPGAs, as well as an increase in sampling rates of conversion devices to potentially several 100 MHz. While the development of both computational devices and ADCs/DACs continues, thus permitting DSP to be applied at IF sampling rates and possibly beyond, the opportunities for further enhancing radio devices by …

Comparison Of Antenna Array Systems Using Ofdm For Software Radio Via The Sibic Model, Khoi D. Le, Michael W. Hoffman, Robert D. Palmer

Department of Electrical and Computer Engineering: Faculty Publications

This paper investigates the performance of two candidates for software radio WLAN, reconfigurable OFDM modulation and antenna diversity, in an indoor environment. The scenario considered is a 20m × 10m × 3m room with two base units and one mobile unit. The two base units use omnidirectional antennas to transmit and the mobile unit uses either a single antenna with equalizer, a fixed beamformer with equalizer, or an adaptive beamformer with equalizer to receive. The modulation constellation of the data is QPSK and 16-QAM. The response of the channel at the mobile unit is simulated using a three-dimensional indoor WLAN …

A Novel Role For Gadd45Β As A Mediator Of Mmp-13 Gene Expression During Chondrocyte Terminal Differentiation, Kosei Ijiri, Luiz F. Zerbini, Haibing Peng, Ricardo G. Correa, Binfeng Lu, Nicole Walsh, Yani Zhao, Noboru Taniguchi, Xu-Ling Huang, Hasan H. Otu, Hong Wang, Jian Fei Wang, Setsuro Komiya, Patricia Ducy, Mahboob U. Rahman, Richard A. Flavell, Ellen M. Gravallese, Peter Oettgen, Towia A. Libermann, Mary B. Goldring

Department of Electrical and Computer Engineering: Faculty Publications

The growth arrest and DNA damage-inducible 45β (GADD45β) gene product has been implicated in the stress response, cell cycle arrest, and apoptosis. Here we demonstrated the unexpected expression of GADD45β in the embryonic growth plate and uncovered its novel role as an essential mediator of matrix metalloproteinase-13 (MMP-13) expression during terminal chondrocyte differentiation. We identified GADD45β as a prominent early response gene induced by bone morphogenetic protein-2 (BMP-2) through a Smad1/Runx2-dependent pathway. Because this pathway is involved in skeletal development, we examined mouse embryonic growth plates, and we observed expression of Gadd45β mRNA coincident with Runx2 protein …

Range Imaging Observations Of Pmse Using The Eiscat Vhf Radar: Phase Calibration And First Results, J. R. Fernandez, R. D. Palmer, P. B. Chilson, I. Haggstrom, M. T. Rietveld

Department of Electrical and Computer Engineering: Faculty Publications

A novel phase calibration technique for use with the multiple-frequency Range IMaging (RIM) technique is introduced based on genetic algorithms. The method is used on data collected with the European Incoherent SCATter (EISCAT) VHF radar during a 2002 experiment with the goal of characterizing the vertical structure of Polar Mesosphere Summer Echoes (PMSE) over northern Norway. For typical Doppler measurements, the initial phases of the transmitter and receiver are not required to be the same. The EISCAT receiver systems exploit this fact, allowing a multistatic configuration. However, the RIM method relies on the small phase differences between closely spaced frequencies. …

Phased-Array Design For Biological Clutter Rejection: Simulation And Experimental Validation, B.L. Cheong, Michael Hoffman, R.D. Palmer, Stephen J. Frasier, F.J. Lopez-Dekker

Department of Electrical and Computer Engineering: Faculty Publications

This paper highlights recent results obtained with the Turbulent Eddy Profiler (TEP), which was devel- oped by the University of Massachusetts. This unique 915-MHz radar has up to 64 spatially separated receiving elements, each with an independent receiver. The calibrated raw data provided by this array could be processed using sophisticated imaging algorithms to resolve the horizontal structures within each range gate. After collecting all of the closely spaced horizontal slices, the TEP radar can produce three- dimensional images of echo power, radial velocity, and spectral width. From the radial velocity measure- ments, it is possible to estimate the three-dimensional …

Tunable Multiferroic Properties In Nanocomposite Pbtio3-Cofe2O4 Epitaxial Thin Films, M. Murakami, K.-S. Chang, M. A. Aronova, C.-L. Lin, Ming H. Yu, Jason R. Hattrick-Simpers, M. Wuttig, I. Takeuchi, C. Gao, B. Hu, S. E. Lofland, L. A. Knauss, L. A. Bendersky

Faculty Publications

We report on the synthesis of PbTiO₃–CoFe₂O₄ multiferroic nanocomposites and continuous tuning of their ferroelectric and magnetic properties as a function of the average composition on thin-film composition spreads. The highest dielectric constant and nonlinear dielectric signal was observed at (PbTiO₃)₈₅–(CoFe₂O₄)₁₅, where robust magnetism was also observed. Transmission electron microscopy revealed a pancake-shaped epitaxial nanostructure of PbTiO₃ on the order of 30 nm embedded in the matrix of CoFe₂O₄ at this composition. Composition dependent ferroics properties observed here indicate that there …

Solar-Based Single-Stage High-Efficiency Grid-Connected Inverter, Feng Tian

Electronic Theses and Dissertations

Renewable energy source plays an important role in the energy cogeneration and distribution. Traditional solar-based inverter system is two stages in cascaded, which has a simpler controller but low efficiency. A new solar-based single-stage grid-connected inverter system can achieve higher efficiency by reducing the power semiconductor switching loss and output stable and synchronized sinusoid current into the utility grid. Controlled by the digital signal processor, the inverter can also draw maximum power from the solar array, thereby maximizing the utilization of the solar array. In Chapter 1, a comparison between the traditional two-stage inverter and the single-stage inverter is made. …

Solution Of Electromagnetic Scattering Parameters And Radiation Patterns Of Arbitrary Body Of Revolution Radiators, Wendell Brokaw

Electronic Theses and Dissertations

A novel full wave analysis method to determine the scattering parameters and the radiation field intensities of arbitrary Body of Revolution (BOR) radiators consisting of impenetrable media is explored through derived components of modal analysis and the method of moments (MoM). Modal excitation is utilized to excite the structural feed; allowing for a more accurate measure of the scattering parameters of the total structure as opposed to the use of external excitation sources. The derivation of the mode matching method introduces a novel approach to achieving a frequency independent coupling matrix that will reduce the computational requirements for iterations utilized …

Modeling, Fabrication, And Optimization Of Niobium Cavities, Robert A. Schill Jr., Mohamed Trabia, William Culbreth

Transmutation Sciences Materials (TRP)

One of the key technologies for the deployment of accelerator driven transmutation systems is the accelerator itself. Elliptical superconducting niobium cavities are used to increase the efficiency of the high-power accelerators needed to support the transmutation mission.

One of the major sources of energy loss from a superconducting accelerator cavity is a process known as multiple impacting (or “multipacting”) of electrons. This phenomenon limits the maximum amount of energy and power that the niobium cavity can store. As a result, the maximum power available for accelerating the desired charge, as well as the overall performance of the accelerator is reduced. …

Multi-Channel Audio Time-Scale Modification, David Dorran, Robert Lawlor, Eugene Coyle

Conference papers

Phase vecoder based approaches to audio time-scale modification introduce a reverberant artefact into the time scaled output. Recent techniques have been developed to reduce the presence of this artefact; however, these techniques have the effect of introducing additional issues relating to their application to multi-channel recordings. This paper addresses these issues by collectively analysing all channels prior to time-scaling each individual channel.

Design Of A Satellite Cluster System In Distributed Simulation, Jong Sik Lee, Thong Luu, Vijaya K. Konangi

Electrical and Computer Engineering Faculty Publications

This article presents the design and development of a satellite cluster system that supports an interfederation communication in High Level Architecture (HLA)-compliant distributed simulation. The interfederation communication enables the execution of a complex, large-scale cluster system of distributed satellites that share the dispersed data assets among satellite components collaboratively. After a brief review of the HLA bridge for interfederation communication, the authors discuss the design issues related to a satellite cluster system that provides cluster management, interfederation communication, and communication data management. They analyze system performance and scalability for centralized and decentralized configurations. The empirical results on the heterogeneous …

Unification Of Transactions And Replication In Three-Tier Architectures Based On Corba, Wenbing Zhao, Louise E. Moser, P. Michael Melliar-Smith

Electrical and Computer Engineering Faculty Publications

In this paper, we describe a software infrastructure that unifies transactions and replication in three-tier architectures and provides data consistency and high availability for enterprise applications. The infrastructure uses transactions based on the CORBA object transaction service to protect the application data in databases on stable storage, using a roll-backward recovery strategy, and replication based on the fault tolerant CORBA standard to protect the middle-tier servers, using a roll-forward recovery strategy. The infrastructure replicates the middle-tier servers to protect the application business logic processing. In addition, it replicates the transaction coordinator, which renders the two-phase commit protocol nonblocking and, thus, …

Power Analysis And Optimization Techniques For Energy Efficient Computer Systems, Wissam Chedid, Chansu Yu, Ben Lee

Electrical and Computer Engineering Faculty Publications

Reducing power consumption has become a major challenge in the design and operation of to-day’s computer systems. This chapter describes different techniques addressing this challenge at different levels of system hardware, such as CPU, memory, and internal interconnection network, as well as at different levels of software components, such as compiler, operating system and user applications. These techniques can be broadly categorized into two types: Design time power analysis versus run-time dynamic power management. Mechanisms in the first category use ana-lytical energy models that are integrated into existing simulators to measure the system’s power consumption and thus help engineers to …

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 …

Modeling And Simulation Of Long Term Degradation And Lifetime Of Deep-Submicron Mos Device And Circuit, Zhi Cui

Electronic Theses and Dissertations

Long-term hot-carrier induced degradation of MOS devices has become more severe as the device size continues to scale down to submicron range. In our work, a simple yet effective method has been developed to provide the degradation laws with a better predictability. The method can be easily augmented into any of the existing degradation laws without requiring additional algorithm. With more accurate extrapolation method, we present a direct and accurate approach to modeling empirically the 0.18-ìm MOS reliability, which can predict the MOS lifetime as a function of drain voltage and channel length. With the further study on physical mechanism …

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 …

Low Dielectric Constant Fluorocarbon Films Containing Silicon By Plasma Enhanced Chemical Vapor Deposition, Yoonyoung Jin

LSU Doctoral Dissertations

Use of low relative dielectric constant (low-k) material as an interlayer dielectric is among important approaches to reduce the RC time delay in high performance ultra-large-scale integrated circuits. Copper metallization is another approach besides the use of low-k material, in reducing the RC delay time, because of its well-known characteristics of low resistivity and high electromigration resistance. Fluorocarbon films containing silicon (SiCF) have been developed in this work for low-k interlayer dielectric applications below 50 nm linewidth technology. The films were prepared by plasma enhanced chemical vapor deposition (PECVD) using gas precursors of tetrafluoromethane as the source of active species …