Electrical and Computer Engineering Commons^™

Real-Time Model Predictive Control Of Quasi-Keyhole Pipe Welding, Kun Qian

University of Kentucky Doctoral Dissertations

Quasi-keyhole, including plasma keyhole and double-sided welding, is a novel approach proposed to operate the keyhole arc welding process. It can result in a high quality weld, but also raise higher demand of the operator. A computer control system to detect the keyhole and control the arc current can improve the performance of the welding process. To this effect, developing automatic pipe welding, instead of manual welding, is a hot research topic in the welding field.

The objective of this research is to design an automatic quasi-keyhole pipe welding system that can monitor the keyhole and control its establishment time …

Near-Field Radiative Transfer: Thermal Radiation, Thermophotovoltaic Power Generation And Optical Characterization, Mathieu Francoeur

University of Kentucky Doctoral Dissertations

This dissertation focuses on near-field radiative transfer, which can be defined as the discipline concerned with energy transfer via electromagnetic waves at sub-wavelength distances. Three specific subjects related to this discipline are investigated, namely nearfield thermal radiation, nanoscale-gap thermophotovoltaic (nano-TPV) power generation and optical characterization. An algorithm for the solution of near-field thermal radiation problems in one-dimensional layered media is developed, and several tests are performed showing the accuracy, consistency and versatility of the procedure. The possibility of tuning near-field radiative heat transfer via thin films supporting surface phononpolaritons (SPhPs) in the infrared is afterwards investigated via the computation of …

Extraction And Prediction Of System Properties Using Variable-N-Gram Modeling And Compressive Hashing, Muthulakshmi Muthukumarasamy

University of Kentucky Doctoral Dissertations

In modern computer systems, memory accesses and power management are the two major performance limiting factors. Accesses to main memory are very slow when compared to operations within a processor chip. Hardware write buffers, caches, out-of-order execution, and prefetch logic, are commonly used to reduce the time spent waiting for main memory accesses. Compiler loop interchange and data layout transformations also can help. Unfortunately, large data structures often have access patterns for which none of the standard approaches are useful. Using smaller data structures can significantly improve performance by allowing the data to reside in higher levels of the memory …

Carbon Nanotube Interconnect Modeling For Very Large Scale Integrated Circuits, Yao Xu

LSU Doctoral Dissertations

In this research, we have studied and analyzed the physical and electrical properties of carbon nanotubes. Based on the reported models for current transport behavior in non-ballistic CNT-FETs, we have built a dynamic model for non-ballistic CNT-FETs. We have also extended the surface potential model of a non-ballistic CNT-FET to a ballistic CNT-FET and developed a current transport model for ballistic CNT-FETs. We have studied the current transport in metallic carbon nanotubes. By considering the electron-electron interactions, we have modified two-dimensional fluid model for electron transport to build a semi-classical one-dimensional fluid model to describe the electron transport in carbon …

Modeling And Analysis Of Radial Flux Toroidally Wound Twin Rotor Permanent Magnet Motor, Ravi Kishore Pratapa

LSU Master's Theses

The main objective of current thesis is the study of Radial Flux Twin Rotor Permanent Magnet (RFTWTRPM) motor. The tasks were to review the literature about RFTWTPM motors and model the motor using Finite Element Method Magnetics (FEMM 4.0). Later the performance of RFTWTRPM motor as a brushless dc motor was analyzed by using MATLAB/SIMULINK package. To find the electrical and mechanical parameters of the RFTWTRPM motor, the rotor and stator dimensions of the motor were firstly optimized using linear FEMM model of the motor. The optimized dimensions were used to construct the cylindrical FEMM model. This model was later …

Wireless Sensor Network Radio Power Management And Simulation Models, Michael I. Brownfield, Theresa Nelson, Scott Midkiff, Nathaniel J. Davis Iv

Faculty Publications

Wireless sensor networks (WSNs) create a new frontier in collecting and processing data from remote locations. The IEEE 802.15.4 wireless personal area network-low rate (WPAN-LR) WSNs rely on hardware simplicity to make sensor field deployments both affordable and long-lasting without maintenance support. WSN designers strive to extend network lifetimes while meeting application-specific throughput and latency requirements. Effective power management places sensor nodes (or motes) into one of the available energy-saving modes based upon the sleep period duration and the current state of the radio. The newest generation of WPAN-LR-based sensor platform radios operates at a 250 kbps data rate and …

Finite Element Analysis Of Ring-Shaped Emission Profile In Plasma Bullet, Yukinori Sakiyama, David B. Graves, Julien Jarrige, Mounir Laroussi

Electrical & Computer Engineering Faculty Publications

Using a one-way coupled model of neutral gas flow and plasma dynamics we report a mechanism to explain the ring-shaped emission pattern that has been observed experimentally in plasma bullets at atmospheric pressure. We solve a fluid model with the local field approximation in one-dimensional cylindrical coordinates, corresponding to a cross-section of a plasma bullet. Pulselike uniform electric field is assumed to be applied perpendicular to the simulation domain. Time and spatially resolved spectroscopic measurements support the simulation results.

Experimental Studies On The Plasma Bullet Propagation And Its Inhibition, Erdinc Karakas, Mounir Laroussi

Electrical & Computer Engineering Faculty Publications

Plasma bullets generated by atmospheric pressure low temperature plasma jets have recently been an active research topic due to their unique properties and their enhanced plasma chemistry. In this paper, experimental insights into the plasma bullet lifetime and its velocity are reported. Data obtained from intensified charge-coupled device camera and time-resolved optical emission spectroscopy (OES) elucidated the existence of a weakly ionized channel between the plasma bullet and its source (such as the plasma pencil). Factors responsible for the inhibition of the propagation of the bullet, such as low helium mole fraction, the magnitude of the applied voltage, and the …

Spheroid Detection In 2d Images Using Circular Hough Transform, Priyanka Chaudhary

University of Kentucky Master's Theses

Three-dimensional endothelial cell sprouting assay (3D-ECSA) exhibits differentiation of endothelial cells into sprouting structures inside a 3D matrix of collagen I. It is a screening tool to study endothelial cell behavior and identification of angiogenesis inhibitors. The shape and size of an EC spheroid (aggregation of ~ 750 cells) is important with respect to its growth performance in presence of angiogenic stimulators. Apparently, tubules formed on malformed spheroids lack homogeneity in terms of density and length. This requires segregation of well formed spheroids from malformed ones to obtain better performance metrics. We aim to develop and validate an automated imaging …

Fpga Based Parallel Implementation Of Stacked Error Diffusion Algorithm, Rishvanth Kora Venugopal

University of Kentucky Master's Theses

Digital halftoning is a crucial technique used in digital printers to convert a continuoustone image into a pattern of black and white dots. Halftoning is used since printers have a limited availability of inks and cannot reproduce all the color intensities in a continuous image. Error Diffusion is an algorithm in halftoning that iteratively quantizes pixels in a neighborhood dependent fashion. This thesis focuses on the development and design of a parallel scalable hardware architecture for high performance implementation of a high quality Stacked Error Diffusion algorithm. The algorithm is described in ‘C’ and requires a significant processing time when …

Statistical Models For Constant False-Alarm Rate Threshold Estimation In Sound Source Detection Systems, Sayed Mahdi Saghaian Nejad Esfahani

University of Kentucky Master's Theses

Constant False Alarm Rate (CFAR) Processors are important for applications where thousands of detection tests are made per second, such as in radar. This thesis introduces a new method for CFAR threshold estimation that is particularly applicable to sound source detection with distributed microphone systems. The novel CFAR Processor exploits the near symmetry about 0 for the acoustic pixel values created by steered-response coherent power in conjunction with a partial whitening preprocessor to estimate thresholds for positive values, which represent potential targets.

To remove the low frequency components responsible for degrading CFAR performance, fixed and adaptive high-pass filters are applied. …

Design And Implementation Of The Instruction Set Architecture For Data Lars, Kalyan Ponnala

University of Kentucky Master's Theses

The ideal memory system assumed by most programmers is one which has high capacity, yet allows any word to be accessed instantaneously. To make the hardware approximate this performance, an increasingly complex memory hierarchy, using caches and techniques like automatic prefetch, has evolved. However, as the gap between processor and memory speeds continues to widen, these programmer-visible mechanisms are becoming inadequate.

Part of the recent increase in processor performance has been due to the introduction of programmer/compiler-visible SWAR (SIMD Within A Register) parallel processing on increasingly wide DATA LARs (Line Associative Registers) as a way to both improve data access …

Design And Simulation Of Silica-On-Silicon Pump/Signal Multiplexer For Hybrid Passive-Active Optical Devices., Alvin Law Wen Pin

Student Works (2010-2019)

This dissertation describes the design and simulation of silica-on-silicon pump/signal multiplexer for hybrid passive-active optical devices. Uniform symmetric directional couplers and planar Bragg gratings were utilized in this work, forming the essential building blocks in a waveguide amplifier. Several designs in relation to the multiplexers are presented in this work, with the simplest application for the directional coupler as a pump/signal multiplexer. A 980/1550 nm and an 800/1310 nm pump/signal multiplexers for erbium doped and bismuth doped waveguide amplifier, respectively were modeled. These couplers were designed and simulated in Rsoft BeamPROP environment, utilizing 3D Finite Difference Beam Propagation Method (FD-BPM) …

Nonlinear Fiber Lasers Using Bismuth Based Erbium Doper Fiber Amplifier., Sharifeh Shahi

Student Works (2010-2019)

A thorough study on Bismuth-based Erbium-doped fiber (Bi-EDF) is presented for wide-band amplifiers and multi-wavelength fiber laser applications. This fiber allows high Erbium ions concentration to be doped without a significant concentration quenching effect. The high refractive index characteristic in the Bi-EDF has broadened the emission spectrum of Erbium ions to achieve a broader gain spectrum up to extended L-band region compared to normal silica-based Erbium-doped fiber (EDF). The Bi-EDFA performances have been investigated in terms of power conversion efficiency (PCE), quantum conversion efficiency (QCE), gain and noise figure. The highest QCE and PCE for a 215 cm long of …

Reflective And Beam-Through Types Of Fiber Optic Sensor For Displacement Measurement., Walaa Fawzi Al–Masri

Student Works (2010-2019)

This dissertation proposes and demonstrates fiber-optic displacement sensor (FODS) theoretically and experimentally using the intensity modulation technique to measure a displacement from a probe and target. The sensor uses a multimode plastic bundled fiber as a probe and He-Ne laser as a source. The performance of the sensor is compared for different type of probe and target. For a pair type bundled fiber, both the experimental and theoretical results exhibit the same type of characteristic features. The front slope sensitivities are obtained at 1.71 and 1.0 mW/μm for the theoretical and experimental approaches respectively, while the back slope sensitivities are …

Production Of Multiwall Carbon Nanotube For Alcohol Sensor Application., Ebtehal Saleh Alshaqaq

Student Works (2010-2019)

Multiwall carbon nanotube/polyethylene oxide (PEO), multiwall carbon nanoube/polyvinyl alcohol(PVA) and multiwall carbon nanotube/ polyvinyl alcohol(PVA)/zinc oxide(ZnO) have been tested as chemical sensors and detailed study on the effect of different gas concentration and material properties on gas sensitivity is presented. Initial composites were prepared by a simple solution casting and characterized by x-ray diffraction for ZnO, Fourier transform infra-red spectroscopy (FTIR) and scanning electron microscopy (SEM) to demonstrate crystallite size of ZnO, the morphology and surface area respectively. On the other hand, MWCNT/PEO , MWCNT/PVA , MWCNT/PVA/ZnO were prepared with different loading MWCNT and ZnO. The chemical sensing properties of …

Low Impedance Restricted Earth Fault Algorithms In Numerical Relays., Babak Nim Taj

Student Works (2010-2019)

Low impedance restricted earth fault protection is one of the protection function to protect the transformer winding with earthed neutral point. The purpose of this study is to investigate low impedance restricted earth fault algorithm in numerical relays. Five restricted earth fault numerical algorithms from ABB, AREVA T&D, SIEMENS, SCHNEIDER ELECTRIC and GENERAL ELECTRIC are employed for restricted earth fault algorithms assessment.This dissertation is to find out advantages and disadvantages of selected algorithms. Moreover, this dissertation is to compare each algorithm with the other algorithms. Also, magnetizing inrush current, over excitation and CT saturation impression on restricted earth fault operation …

Harvesting Single Ferroelectric Domain Stressed Nanoparticles For Optical And Ferroic Applications, Gary Cook, J. L. Barnes, S. A. Basun, Dean R. Evans, Ron F. Ziolo, Arturo Ponce, Victor Yu. Reshetnyak, Anatoliy Glushchenko, Partha P. Banerjee

Electrical and Computer Engineering Faculty Publications

We describe techniques to selectively harvest single ferroelectric domain nanoparticles of BaTiO3 as small as 9 nm from a plethora of nanoparticles produced by mechanical grinding. High resolution transmission electron microscopy imaging shows the unidomain atomic structure of the nanoparticles and reveals compressive and tensile surface strains which are attributed to the preservation of ferroelectric behavior in these particles.

We demonstrate the positive benefits of using harvested nanoparticles in disparate liquid crystal systems.

Characterization Of Atmospheric Turbulence Effects Over 149 Km Propagation Path Using Multi-Wavelength Laser Beacons, Mikhail Vorontsov, Gary W. Carhart, Venkata S. Rao Gudimetla, Thomas Weyrauch, Eric Stevenson, Svetlana Lachinova, Leonid A. Beresnev, Jony Jiang Liu, Karl Rehder, Jim F. Riker

Electrical and Computer Engineering Faculty Publications

We describe preliminary results of a set of laser beam propagation experiments performed over a long (149 km) near-horizontal propagation path between Mauna Loa (Hawaii Island) and Haleakala (Island of Maui) mountains in February 2010. The distinctive feature of the experimental campaign referred to here as the Coherent Multi-Beam Atmospheric Transceiver (COMBAT) experiments is that the measurements of the atmospheric-turbulence induced laser beam intensity scintillations at the receiver telescope aperture were obtained simultaneously using three laser sources (laser beacons) with different wavelengths (λ1 = 0.53 μm, λ2 = 1.06 μm, and λ3 = 1.55 μm). The presented experimental results on …

Control And Design Considerations In Electric-Drive Vehicles, Shweta Neglur

Masters Theses

"Electric-drive vehicles have been identified as one of the promising technologies of the future. Electric-drive vehicles including fuel cell, hybrid electric, and plug-in hybrid electric vehicles have the potential to improve the fuel economy and reduce gas emissions when compared to conventional vehicles. One of the important challenges in the advancement of the electric-drive vehicles is to develop a control strategy which meets the power requirements of the vehicles. The control strategy is an algorithm designed to command the battery and the internal combustion engine of the vehicle for specific power demands. In this thesis, load follower and thermostat control …