Electrical and Computer Engineering Commons^™

Comparative Study On Various Dielectric Barriers And Their Effect On Breakdown Voltage, Elham Foruzan, Amir A. S. Akmal, Kaveh Niayesh, Jeremy Lin, Desh Deepak Sharma

Department of Electrical and Computer Engineering: Faculty Publications

Non-pressurised air is extensively used as basic insulation medium in high-voltage equipment. Unfortunately, an inherent property of air-insulated design is that the system tends to become physically large. On the other hand, the application of dielectric barriers can increase the breakdown voltage and therefore decrease the size of the equipment. In this study, the impact of dielectric barriers on breakdown voltage enhancement is investigated under both direct current (dc) and alternating current (ac) applied voltages. For this purpose, three kinds of dielectric barriers in two different high-voltage electrode structures are investigated. In the first structure, several experiments are carried out …

Method Ofobtaining Micrographs Of Transparent Or Semi-Transparent Specimens Using Anisotropic Contrast, Tino Hofmann, Mathias M. Schubert, Tadas Kasputis, Angela K. Pannier, Craig M. Herzinger, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

Anisotropic contrast methodology in combination with use of sample investigating polarized electromagnetic radiation to provide Jones or Mueller Matrix imaging data corresponding to areas on samples.

Elevated Temperature Dependence Of The Anisotropic Visible-To-Ultraviolet Dielectric Function Of Monoclinic Β-Ga2o3, Alyssa Mock, Jeremy Vanderslice, Rafal Korlacki, John A. Woollam, Mathias Schubert

Department of Electrical and Computer Engineering: Faculty Publications

We report on the temperature dependence of the dielectric tensor elements of n-type conductive β-Ga2O3 from 22 °C to 550 °C in the spectral range of 1.5 eV–6.4 eV. We present the temperature dependence of the excitonic and band-to-band transition energy parameters using a previously described eigendielectric summation approach [A. Mock et al., Phys. Rev. B 96, 245205 (2017)]. We utilize a Bose-Einstein analysis of the temperature dependence of the observed transition energies and reveal electron coupling with average phonon temperature in excellent agreement with the average over all longitudinal phonon plasmon coupled modes reported previously [M. …

ประสิทธิภาพเชิงนิเวศเศรษฐกิจของโรงไฟฟ้าพลังความร้อนร่วมก๊าซธรรมชาติ, สิริลักษณ์ โรคารักษ์

Chulalongkorn University Theses and Dissertations (Chula ETD)

งานวิจัยฉบับนี้มีจุดประสงค์เพื่อศึกษาประสิทธิภาพเชิงนิเวศเศรษฐกิจของโรงไฟฟ้าพลังความร้อนร่วมก๊าซธรรมชาติแห่งหนึ่ง ในภาคตะวันออกของประเทศไทย โดยใช้การศึกษาการประเมินต้นทุนตลอดวัฏจักรชีวิตผลิตภัณฑ์ควบคู่กับการประเมินวัฏจักรชีวิตผลิตภัณฑ์ไฟฟ้า ซึ่งเป็นเครื่องมือที่ช่วยในการตัดสินใจทั้งด้านสิ่งแวดล้อมและเศรษฐศาสตร์ ผลการประเมินวัฏจักรชีวิตผลิตภัณฑ์ไฟฟ้า พบว่า ขั้นตอนการผลิตไฟฟ้า ก่อให้เกิดผลกระทบด้านการใช้พลังงานที่ใช้แล้วหมดไปมากที่สุด รองลงมาคือ ผลกระทบด้านการเกิดภาวะโลกร้อน ในขณะที่การประเมินต้นทุนตลอดวัฏจักรชีวิตผลิตภัณฑ์ พบว่า มูลค่าปัจจุบันของต้นทุนโครงการ เท่ากับ 283,536 ล้านบาท และต้นทุนการผลิตไฟฟ้าต่อหน่วยของโครงการจะเท่ากับ 1.95 บาทต่อกิโลวัตต์ชั่วโมง ทั้งนี้ต้นทุนค่าเชื้อเพลิงก๊าซธรรมชาติส่งผลต่อต้นทุนการผลิตไฟฟ้ามากที่สุด คิดเป็นร้อยละ 89 ของต้นทุนทั้งหมด เนื่องจากความผันผวนของราคาก๊าซธรรมชาติในตลาดโลก ผลการศึกษาประสิทธิภาพเชิงนิเวศเศรษฐกิจด้านการใช้พลังงานที่ใช้แล้วหมดไป และด้านการเกิดภาวะโลกร้อนของโรงไฟฟ้าพลังความร้อนร่วมก๊าซธรรมชาติอยู่ในระดับที่ค่อนข้างดี เมื่อเทียบกับผลการศึกษาอื่น และแนวทางในการลดผลกระทบด้านสิ่งแวดล้อม และเพิ่มประสิทธิภาพการผลิต รวมทั้งลดต้นทุนของการผลิตไฟฟ้าของพลังความร้อนร่วมก๊าซธรรมชาติ ควรให้ความสำคัญกับกระบวนการเผาไหม้เชื้อเพลิง เช่น การเพิ่มประสิทธิภาพของกังหันก๊าซ การลดอากาศขาเข้าเครื่องอัดอากาศ และการทำความสะอาดส่วนอัดอากาศ เป็นต้น

Genetic Algorithm Based Coding For High Efficiency Video Coding, Ei Ei Tun

Chulalongkorn University Theses and Dissertations (Chula ETD)

High efficiency video coding (HEVC) is the newest video coding standard to greatly increase the coding efficiency of its ancestor H.264/AVC with the aids of its new features such as the quadtree-based coding unit (CU) partitioning, a simple deblocking filter, and other advanced coding techniques. However, HEVC delivers a highly increased computation complexity, which is mainly due to the exhaustive rate distortion optimization search of quadtree-based CU partitioning. Firstly, a feature reduction approach is proposed on a fuzzy support vector machine (SVM) based CU size decision method. The proposed feature reduction approach with rate control (RC) can reduce computational complexity …

Effects Of Protein-Coated Nanofibers On Conformation Of Gingival Fibroblast Spheroids: Potential Utility For Connective Tissue Regeneration, Gili Kaufman, Ryan A. Whitescarver, Laiz Nunes, Xavier-Lewis Palmer, Drago Skrtic, Wojtek Tutak

Engineering Technology Faculty Publications

Deep wounds in the gingiva caused bytrauma or surgery require a rapid and robust healing of connective tissues. Wepropose utilizing gas-brushed nanofibers coated with collagen and fibrin for that purpose. Our hypotheses are that protein-coated nanofibers will: (i) attract and mobilize cells in various spatial orientations, and (ii) regulate the expression levels ofspecific extracellular matrix (ECM)-associated proteins, determining the initial conformational nature ofdense and soft connective tissues. Gingival fibroblast monolayers and3D spheroids were cultured onECMsubstrate and covered with gas-blown poly-(DL-lactide-co-glycolide)(PLGA) nanofibers (uncoated/coated with collagen and fibrin). Cell attraction and rearrangement was followed byF-actin staining and confocal microscopy. Thicknesses ofthe cell …

Collaborated Efforts In Ti Arm M4/32bits Microcontroller Curricula Developments And Assessments, Steve C. Hsiung, Feng Jao, Lijian Xu, Marjaneh Issapour

Engineering Technology Faculty Publications

The disappearing and lack technical supports in hardware and software of 68XXX and 80XXX microcontrollers have made the finding of the replacement an urgent issue in the academic communities. There are many new comers such as Microchip PIC, Arduino ATMEL, and Texas Instruments ARM M series to choose from, but obstacles and learning curve for the faculty to adopt the new environment with these new microcontrollers have issues to slow the process. There were efforts made with grant supports to disseminate the curricula development on PIC and Arduino microcontrollers. But, industries have suggested and expressed the needs and desire of …

On The Feasibility Of Utilizing Commercial 4g Lte Systems For Misson-Critical Iot Applications, Alfred Rezk

Dissertations and Theses

Emerging Internet of Things (IoT) applications and services including e-healthcare, intelligent transportation systems, smart grid, and smart homes to smart cities to smart workplace, are poised to become part of every aspect of our daily lives. The IoT will enable billions of sensors, actuators, and smart devices to be interconnected and managed remotely via the Internet. Cellular-based Machine-to-Machine (M2M) communications is one of the key IoT enabling technologies with huge market potential for cellular service providers deploying Long Term Evolution (LTE) networks. There is an emerging consensus that Fourth Generation (4G) and 5G cellular technologies will enable and support these …

A Quantification Analysis On Potential Use Of Recuperated Regenerative Braking Energy From Nyct Subways Into Charging Electric Buses, Ahmed S. Rahman

Dissertations and Theses

The New York Metropolitan Transportation Authority (MTA) is one of the biggest consumers of electricity in east coast of the United States. According to a report published by Dayton T. Brown in 2013, MTA consumes approximately 2150 GWh electrical energy per year for traction power, where the New York City Transit (NYCT) alone is a consumer of about 80% of the total annual MTA energy consumption. This continuous high demand for electricity from a single organization opens research opportunities to search for alternative ways to reduce the needs. NYCT Subways has an existing total rolling stock of 6,418 train cars …

Analysis Of The Benefits Of Regenerative Braking In Urban Railway Traction System, Khan M. Adnan

Dissertations and Theses

Increasing environmental awareness and the requirement for lower project costs is forcing transit system suppliers to think more innovatively and engineer more accurately to strengthen their competitive edge. Of late, clients more often desire a system that is optimized to minimize the energy consumed during operation; a requirement that is often imposed upon transit system suppliers through financially binding energy commitments.

Electric rail transit systems are large consumers of energy. In trains with regenerative braking capability, a fraction of the energy used to power a train is regenerated during braking. This regenerated energy, if recuperated and reused, can result in …

A Case Study On Grid Impacts Of Electric Vehicles On New York City Power Grid, Amir Abbas Rizvi

Dissertations and Theses

The U.S. electric power industry is anticipating a huge increase in electricity demand in the future due to reformation of the transportation industry. In this work, we focus on electric cars and their impact on the transportation industry as well as the electric grid. The increase in number of electric cars over the years and their growing number indicates that in the future, transportation means are going to largely depend upon electricity to achieve cost and environmental benefits. In other words, in future, the transportation will be impacting the electric grid and vice versa.

The surge in electric vehicles on …

Fossil Fuel Impact Of Buildings Electrification In New York City, Mattia Sartori

Dissertations and Theses

New York City's commitment to reduce Greenhouse Gases (GHG) emissions 80% by 2050 (80X50) requires a deep citywide conversion from fuel combustion systems to more efficient technologies, such as air-source heat pumps. Moreover, this challenging goal relies also on a much cleaner grid with the majority of electrical generation being provided by renewable sources, such as solar and wind. In this regard, building electrification is being considered as a possible solution in order to reduce emissions and maximize the efficiency of the energy utilization as well as improve the comfort of the indoor environment.

Under the assumption of a cleaner …

Toward Biologically-Inspired Self-Healing, Resilient Architectures For Digital Instrumentation And Control Systems And Embedded Devices, Shawkat Sabah Khairullah

Theses and Dissertations

Digital Instrumentation and Control (I&C) systems in safety-related applications of next generation industrial automation systems require high levels of resilience against different fault classes. One of the more essential concepts for achieving this goal is the notion of resilient and survivable digital I&C systems. In recent years, self-healing concepts based on biological physiology have received attention for the design of robust digital systems. However, many of these approaches have not been architected from the outset with safety in mind, nor have they been targeted for the automation community where a significant need exists. This dissertation presents a new self-healing digital …

Radial And Longitudinal Motion Of The Arterial Wall: Their Relation To Pulsatile Pressure And Flow In The Artery, Dan Wang, Linda Vahala, Zhili Hao

Mechanical & Aerospace Engineering Faculty Publications

The aim of this paper is to analyze the radial and longitudinal motion of the arterial wall in the context of pulsatile pressure and flow, and to understand their physiological implications for the cardiovascular system. A reexamination of the well-established one-dimensional governing equations for axial blood flow in the artery and the constitutive equation for the radial dilation of the arterial wall shows that two waves—a pulsatile pressure wave in the artery and a radial displacement wave in the arterial wall—propagate simultaneously along the arterial tree with the same propagation velocity, explaining why this velocity combines the physical properties and …

A Scale Space Local Binary Pattern (Sslbp) – Based Feature Extraction Framework To Detect Bones From Knee Mri Scans, Jinyeong Mun

Electronic Theses and Dissertations

The medical industry is currently working on a fully autonomous surgical system, which is considered a novel modality to go beyond technical limitations of conventional surgery. In order to apply an autonomous surgical system to knees, one of the primarily responsible areas for supporting the total weight of human body, accurate segmentation of bones from knee Magnetic Resonance Imaging (MRI) scans plays a crucial role. In this paper, we propose employing the Scale Space Local Binary Pattern (SSLBP) feature extraction, a variant of local binary pattern extractions, for detecting bones from knee images. The proposed methods consist of two phases. …

Thickness Dependence Of Electrical Conductivity In A Thin Film Thermoelectric Composite, David Zagaceta, William Rogers, Andres Breucop, Brian Herrera

Math 365 Class Projects

In this work we utilize the Van Der Pauw method for measuring and calculating the electrical conductivity of a composite material in relation to its thickness.

Study On Electrolyte-Gated Graphene Nanoelectronic Biosensors For Biomarker Detection, Jianbo Sun

Graduate Theses, Dissertations, and Problem Reports (ETD)

Biosensors are called upon to provide valuable benefits for human society in vital fields such as disease diagnosis, food inspection, environment monitoring, etc. Among the various biosensor architectures, the field effect transistor (FET) biosensors are promising as the next generation nanoelectronic biosensors, particularly attractive for point-of-care biomedical applications. The FET biosensors typically operate by measuring the conductance change of the semiconducting channel induced by the adsorption of the target biomolecules on it. The superior properties of graphene, including the unique electronic characteristics, facile functionalization and good biocompatibility, etc., make it an ideal building block for the FET biosensors. In this …

Steady-State And Small-Signal Modeling Of A-Source Converter, Agasthya Ayachit

Browse all Theses and Dissertations

As the trend towards vehicle electrification, renewable energy, smart systems is increasing, the key enabling technology such as power electronics are becoming ever more important. Power electronics is the vital component of many applications in automotive, computer, data-centers, medical, aerospace, communication, green-energy, and manufacturing sectors. Major advancements in high efficiency, high power density, high voltage conversion ratio, and fast dynamic response power-electronic converters is evident both in research and industry, particularly at the topology level. A major contribution of this dissertation is the analysis, design, development, and dynamic modeling of a novel impedance-source topology termed as A-source converter, which potentially …

Characterization And Design Of Voltage-Mode Controlled Full-Bridge Dc/Dc Converter With Current Limit, Nathaniel R. Smith

Browse all Theses and Dissertations

Advancements in Direct Current (DC) electrical power systems have enabled new functionality in many, varied applications. Discrete power semiconductor devices are increasing in efficiency, switching frequency, and power density, resulting in greater usage of DC power management and distribution methods, including DC/DC conversion. DC distribution lacks inherent capability to safely and effectively break fault current, particularly in mobile solutions, where larger and slower electromechanical switching devices are not optimal or feasible. One solution is to design a low-energy breaking point into a switching power supply. Simpler converter designs, with a lower number of switching devices, have been modeled and can …

Thin-Film Lithium Niobate Photonics For Electro-Optics, Nonlinear Optics, And Quantum Optics On Silicon, Ashutosh Rao

Electronic Theses and Dissertations

Ion-sliced thin-film lithium niobate (LN) compact waveguide technology has facilitated the resurgence of integrated photonics based on lithium niobate. These thin-film LN waveguides offer over an order of magnitude improvement in optical confinement, and about two orders of magnitude reduction in waveguide bending radius, compared to conventional LN waveguides. Harnessing the improved confinement, a variety of miniaturized and efficient photonic devices are demonstrated in this work. First, two types of compact electrooptic modulators are presented – microring modulators, and Mach-Zehnder modulators. Next, two distinct approaches to nonlinear optical frequency converters are implemented – periodically poled lithium niobate, and mode shape …

Mode-Locked Laser Based On Large Core Yb3+-Doped Fiber, Fei Jia

Electronic Theses and Dissertations

The thesis reviews principle of laser cavity and gives a general introduction to modelocked laser (MLL). By using Yb3+-doped fiber as gain medium, passive MLL cavity is developed in experiment, aiming to obtain femtosecond pulses with high pump power from 25W to 35W. The gain medium fiber with 65µm core diameter is cleaved with one flat end and another angled. Pump laser with 976nm wavelength is coupled into Yb3+ -doped fiber to excite signal from 1020nm to 1040nm in the core. 9W is threshold for laser setup. After locking all modes, picosecond pulses are output from laser cavity and coupled …

Analysis And Design Of Non-Hermitian Optical Systems, Ali Kazemi Jahromi

Electronic Theses and Dissertations

From a very general perspective, optical devices can be viewed as constructions based on the spatial engineering of the optical index of refraction. Sculpting the real part of the refractive index produces the wide variety of known passive optical devices, such as waveguides, resonators, gratings, among a plethora of other possibilities for managing the transport of light. Less attention has been directed to engineering the imaginary part of the refractive index – that is responsible for optical gain and absorption – in conjunction with the real part of the refractive index. Optical gain is the building block of amplifiers and …

Nonlinear Dynamics In Multimode Optical Fibers, Mohammad Amin Eftekhar

Electronic Theses and Dissertations

Multimode optical fibers have recently reemerged as a viable platform for addressing a number of long-standing issues associated with information bandwidth requirements and power-handling capabilities. The complex nature of heavily multimoded systems can be effectively exploited to observe altogether novel physical effects arising from spatiotemporal and intermodal linear and nonlinear processes. Here, we have studied nonlinear dynamics in multimode optical fibers (MMFs) in both the normal and anomalous dispersion regimes. In the anomalous dispersion regime, the nonlinearity leads to a formation of spatiotemporal 3-D solitons. Unlike in single-mode fibers, these solitons are not unique and their properties can be modified …

Single Mode Wavelength-Tunable Thulium Fiber, Dong Jin Shin

Electronic Theses and Dissertations

Thulium fiber lasers have the broadest emission wavelength bandwidth out of any rare-earth doped fiber lasers. The emission wavelength starts from 1.75μm and ends at around 2.15μm, covering a vast swath of the eye safe wavelength region and intersecting with a large portion of mid-infrared atmospheric transmission window. Also, thulium fiber lasers provide the highest average output power of any other rare-earth doped fiber lasers in these wavelength regimes, making them uniquely suited for applications such as remote sensing. At the moment, high power beam propagation of continuous wave laser through the atmosphere in the mid-infrared range is yet to …

2 Micron Fiber Lasers: Power Scaling Concepts And Limitations, Alex Sincore

Electronic Theses and Dissertations

Thulium- and holmium-doped fiber lasers (TDF and HDF) emitting at 2 micron offer unique benefits and applications compared to common ytterbium-doped 1 micron lasers. This dissertation details the concepts, limitations, design, and performance of four 2 micron fiber laser systems. While these lasers were developed for various end-uses, they also provide further insight into two major power scaling limitations. The first limitation is optical nonlinearities: specifically stimulated Brillouin scattering (SBS) and modulation instability (MI). The second limitation is thermal failure due to inefficient pump conversion. First, a 21.5 W single-frequency, single-mode laser with adjustable output from continuous-wave to nanosecond pulses …

Dual-Stub Ka-Band Vivaldi Antenna With Integrated Bandpass Filter, Kansheng Yang, Manh-Ha Hoang, Xiulong Bao, Patrick Mcevoy, Max Ammann

Articles

A dual-stub coplanar Vivaldi antenna with a parasitic element is presented. The dual-stub is coupled between the parasitic element and two tapered slots. The parasitic element shape and size is optimised. The use of slits on the outer edge of the ground plane is shown to provide control of beamwidth and maximum gain. A bandpass filter is used for performance control and sub-harmonic suppression.

Video Quality Prediction Under Time-Varying Loads, Obinna Izima, Ruairí De Fréin, Mark Davis

Conference papers

We are on the cusp of an era where we can responsively and adaptively predict future network performance from network device statistics in the Cloud. To make this happen, regression-based models have been applied to learn mappings between the kernel metrics of a machine in a service cluster and service quality metrics on a client machine. The path ahead requires the ability to adaptively parametrize learning algorithms for arbitrary problems and to increase computation speed. We consider methods to adaptively parametrize regularization penalties, coupled with methods for compensating for the effects of the time-varying loads present in the system, namely …

The Silver Lining: A Novel, Inkjet-Printed Mesh Coplanar-Slot Antenna For The Uhf Band, Anastasios C. Karles

Undergraduate Research Posters

The Federal Communications Commission (FCC) is opening up frequencies within the television range (400MHz to 700MHz) of the Ultra High Frequency (UHF) band for use in emerging technologies, such as cognitive radio networks and machine-to-machine communication. In order for manufacturers to produce affordable antennas that can be used in these emerging technologies, inexpensive antennas are required that meet these new spectrum needs. This paper presents a mesh coplanar-slot bowtie patch antenna fabricated using commercially available inkjet-printing technology. Two antennas were fabricated: a 27x21cm copper FR4 antenna with .25mm lines and a 27x21cm silver antenna with 2mm lines fabricated using inkjet-printing. …

How Children With Autism Spectrum Disorder Recognize Facial Expressions Displayed By A Rear-Projection Humanoid Robot, Farzaneh Askari, Huanghao Feng, Anibal Gutierrez, Timothy Sweeny, Mohammad H. Mahoor

Electrical and Computer Engineering: Graduate Student Scholarship

Background: Children with Autism Spectrum Disorder (ASD) experience reduced ability to perceive crucial nonverbal communication cues such as eye gaze, gestures, and facial expressions. Recent studies suggest that social robots can be used as effective tools to improve communication and social skills in children with ASD. One explanation has been put forward by several studies that children with ASD feel more contented and motivated in systemized and predictable environment, like interacting with robots.

Objectives: There have been few research studies evaluating how children with ASD perceive facial expression in humanoid robots but no research evaluating facial expression perception …

A Pilot Study On Facial Expression Recognition Ability Of Autistic Children Using Ryan, A Rear-Projected Humanoid Robot, Farzaneh Askari, Huanghao Feng, Timothy D. Sweeny, Mohammad H. Mahoor

Electrical and Computer Engineering: Graduate Student Scholarship

Rear-projected robots use computer graphics technology to create facial animations and project them on a mask to show the robot’s facial cues and expressions. These types of robots are becoming commercially available, though more research is required to understand how they can be effectively used as a socially assistive robotic agent. This paper presents the results of a pilot study on comparing the facial expression recognition abilities of children with Autism Spectrum Disorder (ASD) with typically developing (TD) children using a rear-projected humanoid robot called Ryan. Six children with ASD and six TD children participated in this research, where Ryan …