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Articles 2611 - 2640 of 3391
Full-Text Articles in Engineering
Intracellular Signaling Networks In The Immune Response: Pathways Activated By Interleukin-2 And-4 Receptors And Their Roles In T Cell Proliferation, Kristen K. Comfort
Intracellular Signaling Networks In The Immune Response: Pathways Activated By Interleukin-2 And-4 Receptors And Their Roles In T Cell Proliferation, Kristen K. Comfort
Chemical and Materials Engineering Faculty Publications
Cells sense and respond to chemical and physical stimuli through signal transduction pathways, which mediate cell proliferation, differentiation, migration, and survival. The cytokines interleukin-2 (IL-2) and interleukin-4 (IL-4) are key regulators of the adaptive immune system, particularly influencing the clonal expansion and differentiation of T cells. At least in culture, both synergistic and antagonistic effects of IL-2 and -4 co-stimulation have been reported; the antagonism, when observed, is thought to arise from the utilization of a common subunit shared by IL-2 and IL-4 receptors. We have sought to characterize IL-2 and IL-4 signaling at the level of intracellular pathways activated …
Control Of Plasma Flux Composition Incident On Tin Films During Reactive Magnetron Sputtering And The Effect On Film Microstructure, Christopher Muratore, Scott G. Walton, Darrin Leonhardt, Richard F. Fernsler
Control Of Plasma Flux Composition Incident On Tin Films During Reactive Magnetron Sputtering And The Effect On Film Microstructure, Christopher Muratore, Scott G. Walton, Darrin Leonhardt, Richard F. Fernsler
Chemical and Materials Engineering Faculty Publications
A hybrid plasma enhanced physical vapor deposition (PEPVD) system consisting of an unbalanced dc magnetron and a pulsed electron beam-produced plasma was used to deposit reactively sputtered titanium nitride thin films. The system allowed for control of the magnitudes of the ion and neutral flux, in addition to the type of nitrogen ions (atomic or molecular) that comprised the flux. For all deposition experiments, the magnitude of the ion flux incident on the substrate was held constant, but the composition of the total flux was varied. X-ray diffraction and atomic force microscopy showed that crystallographic texture and surface morphology of …
การปรับปรุงกระบวนงานของสำหนังานประกันสังคมโดยใช้แนวทาง ลีน ซิกซ์ ซิกมา, กาญจน์ สุนทราภา
การปรับปรุงกระบวนงานของสำหนังานประกันสังคมโดยใช้แนวทาง ลีน ซิกซ์ ซิกมา, กาญจน์ สุนทราภา
Chulalongkorn University Theses and Dissertations (Chula ETD)
งานวิจัยฉบับนี้มีวัตถุประสงค์เพื่อปรับปรุงการกระบวนงานให้บริการของสำนักงานประกันสังคมเขต 6 โดยการหาแนวทางเพื่อลดจำนวนขั้นตอนและระยะเวลาที่ผู้ประกันตนใช้ในการรับบริการในกระบวนงานขอรับประโยชน์ทดแทนจากกองทุนประกันสังคมจำนวน 5 ประเภทงาน โดยงานวิจัยนี้ใช้แนวคิดและขั้นตอนของ ลีน ซิกซ์ ซิกมา ซึ่งประกอบด้วย การนิยามปัญหา การวัดและเก็บข้อมูลเกี่ยวกับสภาพปัญหา การวิเคราะห์หาสาเหตุของปัญหา การหาแนวทางปรับปรุงแก้ไข และการควบคุมและปรับปรุงอย่างต่อเนื่อง จากการวิเคราะห์ระบบการให้บริการพบว่าสาเหตุหลักของปัญหาเกิดจากการกำหนดขั้นตอนการให้บริการและการจัดสรรเจ้าหน้าที่ไม่เหมาะสม ดังนั้นจึงกำหนดแนวทางในการปรับปรุงระบบการให้บริการตามแนวทางลีน ซิกซ์ ซิกมาโดย 1) ออกแบบผังที่นั่งทำงานของเจ้าหน้าที่ใหม่ 2) ปรับลดและรวมขั้นตอนการทำงาน 3) ปรับปรุงการจัดการการไหลของงานเอกสาร 4) จัดสรรจำนวนเจ้าหน้าที่ให้เหมาะสมและสมดุลในแต่ละขั้นตอนการทำงาน 5) จัดการฝึกอบรมให้เจ้าหน้าที่สามารถทำงานได้หลายหน้าที่ ทั้งนี้ในขั้นตอนการจัดรูปแบบของระบบการให้บริการ และจัดจำนวนเจ้าหน้าที่ให้เหมาะสมได้ใช้วิธีการเขียนแบบจำลองเข้ามาช่วย ซึ่งพบว่าหลังจากปรับปรุงระบบการให้บริการสามารถลดจำนวนเจ้าหน้าที่ในระบบให้บริการลงได้ อีกทั้งค่าเฉลี่ยของระยะเวลาที่ผู้ประกันตนอยู่ในระบบของทั้ง 5 ประเภทงานมีค่าลดลง คือ ก่อนปรับปรุงมีค่าเฉลี่ยอยู่ในช่วง 35-45 นาทีได้ลดลงจนมีค่าเฉลี่ยอยู่ในช่วง 30.9-35.1 นาที และร้อยละของผู้ประกันตนที่ใช้เวลาในระบบเกิน 40 นาทีได้ลดลงจากร้อยละ 19-90 เหลือร้อยละ 0.71-4.9
Statistical Analysis Of Indiana Rainfall Data, A. Ramachandra Rao, Shih-Chieh Kao
Statistical Analysis Of Indiana Rainfall Data, A. Ramachandra Rao, Shih-Chieh Kao
JTRP Technical Reports
The basic objectives of research presented in this report are characterizing and modeling short time increment (hourly) rainfall data from Indiana. Characteristics of hourly rainfall data from Indiana were investigated. Data from 74 stations were used in the study.
The homogeneity of Indiana hourly rainfall data was tested as a part of the study. Indiana hourly rainfall data is found to be statistically homogeneous. Several probability distributions were evaluated. Surprisingly, both the type I extreme value as well as the generalized extreme value distributions were found to be acceptable to characterize Indiana hourly rainfall data. The generalized extreme value distribution …
Test 1871: John Deere 5203 Diesel 9-Speed, Nebraska Tractor Test Lab
Test 1871: John Deere 5203 Diesel 9-Speed, Nebraska Tractor Test Lab
Nebraska Tractor Tests
ABOUT THE TEST REPORT AND USE OF THE DATA
The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data.
EXPLANATION OF THE TEST PROCEDURES
Purpose
The purpose of …
Test 1870: John Deere 5103 Diesel 9-Speed, Nebraska Tractor Test Lab
Test 1870: John Deere 5103 Diesel 9-Speed, Nebraska Tractor Test Lab
Nebraska Tractor Tests
ABOUT THE TEST REPORT AND USE OF THE DATA
The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data.
EXPLANATION OF THE TEST PROCEDURES
Purpose
The purpose of …
Test 1884: John Deere 8130 Diesel 16-Speed, Nebraska Tractor Test Lab
Test 1884: John Deere 8130 Diesel 16-Speed, Nebraska Tractor Test Lab
Nebraska Tractor Tests
ABOUT THE TEST REPORT AND USE OF THE DATA
The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data.
EXPLANATION OF THE TEST PROCEDURES
Purpose
The purpose of …
Test 1888: John Deere 8330t Diesel 16-Speed, Nebraska Tractor Test Lab
Test 1888: John Deere 8330t Diesel 16-Speed, Nebraska Tractor Test Lab
Nebraska Tractor Tests
ABOUT THE TEST REPORT AND USE OF THE DATA
The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data.
EXPLANATION OF THE TEST PROCEDURES
Purpose
The purpose of …
Test 1887: John Deere 8330 Diesel 16-Speed, Nebraska Tractor Test Lab
Test 1887: John Deere 8330 Diesel 16-Speed, Nebraska Tractor Test Lab
Nebraska Tractor Tests
ABOUT THE TEST REPORT AND USE OF THE DATA
The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data.
EXPLANATION OF THE TEST PROCEDURES
Purpose
The purpose of …
Test 1885: John Deere 8230 Diesel 16-Speed, Nebraska Tractor Test Lab
Test 1885: John Deere 8230 Diesel 16-Speed, Nebraska Tractor Test Lab
Nebraska Tractor Tests
ABOUT THE TEST REPORT AND USE OF THE DATA
The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data.
EXPLANATION OF THE TEST PROCEDURES
Purpose
The purpose of …
Osteonal Effects On Elastic Modulus And Fatigue Life In Equine Bone, V. A. Gibson, S. M. Stover, J. C. Gibeling, S. J. Hazelwood, R. B. Martin
Osteonal Effects On Elastic Modulus And Fatigue Life In Equine Bone, V. A. Gibson, S. M. Stover, J. C. Gibeling, S. J. Hazelwood, R. B. Martin
Biomedical Engineering
We hypothesized that recently formed, incompletely mineralized, and thus, relatively deformable osteons in the equine third metacarpus enhance in vitro load-controlled fatigue life in two ways. Macroscopically, there is a compliance effect, because reduced tissue elastic modulus diminishes the stress required to reach a given strain. Microscopically, there is a cement line effect, in which new osteons and their cement lines more effectively serve as barriers to crack propagation. We studied 18 4×10×100 mm beams from the medial, lateral, and dorsal cortices of metacarpal bones from 6 thoroughbred racehorses. Following load-controlled fatigue testing to fracture in 4 point bending, a …
Radiation Studies Of The Tin-Doped Microscopic Droplet Laser Plasma Light Source Specific To Euv Lithography, Chiew-Seng Koay
Radiation Studies Of The Tin-Doped Microscopic Droplet Laser Plasma Light Source Specific To Euv Lithography, Chiew-Seng Koay
Electronic Theses and Dissertations
Extreme ultraviolet lithography(EUVL) is being developed worldwide as the next generation technology to be inserted in ~ 2009 for the mass production of IC chips with feature sizes <35 nm. One major challenge to its implementation is the development of a 13.5 nm EUV source of radiation that meets the requirements of current roadmap designs of the source of illumination in commercial EUVL scanners. The light source must be debris-free, in a free-space environment with the imaging EUV optics that must provide sufficient, narrow spectral band EUV power to print 100 wafers/hr. To meet this need, extensive studies on emission from a laser plasma source utilizing tin-doped droplet target was conducted. Presented in this work, are the many optical techniques such as spectroscopy, radiometry, and imaging, that were employed to characterize and optimize emission from the laser plasma source State of the art EUV spectrographs were employed to observe the source's spectrum under various laser irradiation conditions. Comparing the experimental spectra to those from theory, has allowed the determination of the Sn ion stages responsible for emitting into the useful EUV bandwidth. Experimental results were compared to spectral simulations obtained using Collisional-Radiative Equilibrium (CRE) model, as well. Moreover, extensive measurements surveying source emission from 2 nm to 30 nm, which is the region of the electromagnetic spectrum defined as EUV, was accomplished. Absolutely calibrated metrology was employed with the Flying Circus instrument from which the source's conversion efficiency (CE)--from laser to the useful EUV energy--was characterized under various laser irradiation conditions. Hydrodynamic simulations of the plasma expansion together with the CRE model predicted the condition at which optimum conversion could be attained. The condition was demonstrated experimentally, with the highest CE to be slightly above 2%, which is the highest value among all EUV source contenders. In addition to laser intensity, the CE was found to depend on the laser wavelength. For better understanding, this observation is compared to results from simulations. Through a novel approach in imaging, the size of the plasma was characterized by recording images of the plasma within a narrow band, around 13.5 nm. The size, approximately 100 ìm, is safely within the etendue limit set by the optical elements in the EUV scanner. Finally, the notion of irradiating the target with multiple laser beams was explored for the possibility of improving the source's conversion efficiency.
Variation Of Geotechnical Strength Properties With Age Of Landfills Accepting Biosolids, Kishore Pinapati
Variation Of Geotechnical Strength Properties With Age Of Landfills Accepting Biosolids, Kishore Pinapati
Electronic Theses and Dissertations
The solid portion of waste disposal, known as Municipal Solid Waste (MSW) can be landfilled. Landfilling has proved to be a safe, sanitary and economical method of disposal. A by-product from wastewater treatment plants called biosolids is sometimes co-disposed along with MSW in landfills. Recent work at the University of Central Florida has focused on the behavior of the mixture of MSW and biosolids. As an increased amount of waste accumulates in these landfills, it creates a new problem the geotechnical stability of landfills. In current literature, classical geotechnical testing methods have been followed to find the strength properties …
Study Of Heat Transfer Characteristics Of Impinging Air Jet Using Pressure Andn Temperature Sensitive Luminescent Paint, Quan Liu
Electronic Theses and Dissertations
Luminescent coating measurement system is a relatively new technology for quantitative pressure and temperature measurement. Usually referred to as Pressure Sensitive Paint (PSP) and Temperature Sensitive Paint (TSP), luminescent coatings contain sensor molecules, which undergoes a luminescent transition when excited with light of proper wavelength. The reaction is pressure and/or temperature sensitive. The image of TSP or PSP coated model surface can be captured with a scientific grade camera and then processed to obtain full field temperature and pressure distribution with very high fidelity. The preparation time of the technique is short. The measurement system offers an economic alternative to …
Fast Response Liquid Crystal Devices, Yung-Hsun Wu
Fast Response Liquid Crystal Devices, Yung-Hsun Wu
Electronic Theses and Dissertations
Liquid crystal (LC) has been widely used for displays, spatial light modulators, variable optical attenuators (VOAs) and other tunable photonic devices. The response time of these devices is mainly determined by the employed liquid crystal material. How to obtain fast response for the LC devices is a fundamentally important and technically challenging task. In this dissertation, we investigate several methods to improve liquid crystal response time, for examples, using dual-frequency liquid crystals, polymer stabilized liquid crystals, and sheared polymer network liquid crystals. We discover a new class of material, denoted as sheared polymer network liquid crystal (SPNLC) which exhibits a …
Integrated Wavelength Stabilization Of Broad Area Semiconductor Lasers Using A Dual Grating Reflector, Jason O'Daniel
Integrated Wavelength Stabilization Of Broad Area Semiconductor Lasers Using A Dual Grating Reflector, Jason O'Daniel
Electronic Theses and Dissertations
A new fully integrated wavelength stabilization scheme based on grating-coupled surface-emitting lasers is explored. This wavelength stabilization scheme relies on two gratings. The first grating is fabricated on the p-side of the semiconductor laser in close proximity to the laser waveguide such that it couples light out of the guided mode of the waveguide into a propagating mode in the substrate; this grating is known as the grating coupler. The second grating is fabricated on the n-side of the substrate such that for the stabilization wavelength, this second grating operates in the Littrow condition and is known as the feedback …
Polarization-Independent Liquid Crystal Devices, Yi-Hsin Lin
Polarization-Independent Liquid Crystal Devices, Yi-Hsin Lin
Electronic Theses and Dissertations
Liquid crystal (LC) devices can be operated as amplitude modulators and phase modulators. LC amplitude modulation is commonly used in liquid crystal display (LCD) while phase-only modulation is useful for laser beam steering, tunable grating, prism, lens, and other photonic devices. Most LC devices are polarization dependent and require at least one polarizer. As a result, the optical efficiency is low. To enhance display brightness, a power hungry backlight has to be used leading to a high power consumption and short battery life. In a LC phase modulator, the polarization dependent property complicates the laser beam steering system. It is …
Propagation Effect In Inhomogeneous Media, Including Media With Light-Induced And Fixed Gratings, Chang-Ching Tsai
Propagation Effect In Inhomogeneous Media, Including Media With Light-Induced And Fixed Gratings, Chang-Ching Tsai
Electronic Theses and Dissertations
Optical waves propagation in various types of volume gratings, materials with constant impendence and optical fibers are studied. Instability of crossphase modulation and of Energy transfer via GRON-type (Grating-type Orientational Nonlinearity in Liquid Crystal) Stimulated Scattering is numerically observed. Two diffractive optical elements made of volume gratings are suggested and analyzed. A transmission hologram based on the analogy with Stimulated Raman Adiabatic Passage (STIRAP) in nonlinear optics is proposed. This transmission hologram demonstrates high diffraction efficiency and low sensitivity to polarization and hologram strength. The other is a reflection hologram with two crossed-gratings. It features good angular selectivity in comparison …
All-Semiconductor High Power Mode-Locked Laser System, Kyungbum Kim
All-Semiconductor High Power Mode-Locked Laser System, Kyungbum Kim
Electronic Theses and Dissertations
All-optical synchronization and its application in advanced optical communications have been investigated in this dissertation. Dynamics of all-optical timing synchronization (clock recovery) using multi-section gain-coupled distributed-feedback (MS-GC DFB) lasers are discussed. A record speed of 180-GHz timing synchronization has been demonstrated using this device. An all-optical carrier synchronization (phase and polarization recovery) scheme from PSK (phase shift keying) data is proposed and demonstrated for the first time. As an application of all-optical synchronization, the characterization of advanced modulation formats using a linear optical sampling technique was studied. The full characterization of 10-Gb/s RZ-BPSK (return-to-zero binary PSK) data has been demonstrated. …
Effect Of Operator Control Configuration On Unmanned Aerial System Trainability, John Neumann
Effect Of Operator Control Configuration On Unmanned Aerial System Trainability, John Neumann
Electronic Theses and Dissertations
Unmanned aerial systems (UAS) carry no pilot on board, yet they still require live operators to handle critical functions such as mission planning and execution. Humans also interpret the sensor information provided by these platforms. This applies to all classes of unmanned aerial vehicles (UAV's), including the smaller portable systems used for gathering real-time reconnaissance during military operations in urban terrain. The need to quickly and reliably train soldiers to control small UAS operations demands that the human-system interface be intuitive and easy to master. In this study, participants completed a series of tests of spatial ability and were then …
Preliminary Study On The Impact Of Impingement On The Effectiveness Of Film Cooling In The Presence Of Gas Path Pressure Gradient, Anil Peravali
Preliminary Study On The Impact Of Impingement On The Effectiveness Of Film Cooling In The Presence Of Gas Path Pressure Gradient, Anil Peravali
Electronic Theses and Dissertations
Impingement is the most commonly used method of cooling in the hot stages of gas turbines. This is often combined with film cooling to further increase the cooling performance. The mainstream flow where in the coolant films discharge often has large stream wise pressure variations. All existing studies on coupled film and impingement cooling concentrated on the effect of the film depletion on the impingement heat transfer. This study investigates the impact of impingement on film cooling, where the jets impinging on a flat plate are depleted through arrays of film cooling holes in the presence of pressure gradient in …
A Three-Dimensional Bay/Estuary Model To Simulate Water Quality Transport, Jing Yu
A Three-Dimensional Bay/Estuary Model To Simulate Water Quality Transport, Jing Yu
Electronic Theses and Dissertations
This thesis presents the development of a numerical water quality model using a general paradigm of reaction-based approaches. In a reaction-based approach, all conceptualized biogeochemical processes are transformed into a reaction network. Through the decomposition of species governing equations via Gauss-Jordan column reduction of the reaction network, (1) redundant fast reactions and irrelevant kinetic reactions are removed from the system, which alleviates the problem of unnecessary and erroneous formulation and parameterization of these reactions, and (2) fast reactions and slow reactions are decoupled, which enables robust numerical integrations. The system of species transport equations is transformed to reaction-extent transport equations, …
On The Use Of Variable Coherence In Inverse Scattering Problems, Erwan Baleine
On The Use Of Variable Coherence In Inverse Scattering Problems, Erwan Baleine
Electronic Theses and Dissertations
Even though most of the properties of optical fields, such as wavelength, polarization, wavefront curvature or angular spectrum, have been commonly manipulated in a variety of remote sensing procedures, controlling the degree of coherence of light did not find wide applications until recently. Since the emergence of optical coherence tomography, a growing number of scattering techniques have relied on temporal coherence gating which provides efficient target selectivity in a way achieved only by bulky short pulse measurements. The spatial counterpart of temporal coherence, however, has barely been exploited in sensing applications. This dissertation examines, in different scattering regimes, a variety …
Driving Simulator Validation And Rear-End Crash Risk Analysis At A Signalised Intersection, Praveen Chilakapati
Driving Simulator Validation And Rear-End Crash Risk Analysis At A Signalised Intersection, Praveen Chilakapati
Electronic Theses and Dissertations
In recent years the use of advanced driving simulators has increased in the transportation engineering field especially in evaluating safety countermeasures. The driving simulator at UCF is a high fidelity simulator with six degrees of freedom. This research aims at validating the simulator in terms of speed and safety with the intention of using it as a test bed for high risk locations and to use it in developing traffic safety countermeasures. The Simulator replicates a real world signalized intersection (Alafaya trail (SR-434) and Colonial Drive (SR-50)). A total of sixty one subjects of age ranging from sixteen to sixty …
Applications Of Linear And Nonlinear Optical Effects In Liquid Crystals, Hakob Sarkissian
Applications Of Linear And Nonlinear Optical Effects In Liquid Crystals, Hakob Sarkissian
Electronic Theses and Dissertations
Liquid crystals have been a major subject of research for the past decades. Aside from the variety of structures they can form, they exhibit a vast range of optical phenomena. Many of these phenomena found applications in technology and became an essential part of it. In this dissertation thesis we continue the line to propose a number of new applications of optical effects in liquid crystals and develop their theoretical framework. One such application is the possibility of beam combining using Orientational Stimulated Scattering in a nematic liquid crystal cell. Our numerical study of the OSS process shows that normally …
A Fluid Structure Interaction Model Of Intracoronary Atherosclerotic Plaque Rupture, Eric Teuma-Melago
A Fluid Structure Interaction Model Of Intracoronary Atherosclerotic Plaque Rupture, Eric Teuma-Melago
Electronic Theses and Dissertations
Plaque rupture with superimposed thrombosis is the primary cause of acute coronary syndromes of unstable angina, myocardial infarction and sudden death. Although intensive studies in the past decade have shed light on the mechanism that causes unstable atheroma, none has directly addressed the clinical observation that most myocardial infarction (MI) patients have moderate stenoses (less than 50%). Considering the important role the arterial wall compliance and pulsitile blood flow play in atheroma rupture, fluid-structure interaction (FSI) phenomenon has been of interest in recent studies. In this thesis, the impact is investigated numerically of coupled blood flow and structural dynamics on …
Image-Based Material Editing, Erum Khan
Image-Based Material Editing, Erum Khan
Electronic Theses and Dissertations
Photo editing software allows digital images to be blurred, warped or re-colored at the touch of a button. However, it is not currently possible to change the material appearance of an object except by painstakingly painting over the appropriate pixels. Here we present a set of methods for automatically replacing one material with another, completely different material, starting with only a single high dynamic range image, and an alpha matte specifying the object. Our approach exploits the fact that human vision is surprisingly tolerant of certain (sometimes enormous) physical inaccuracies. Thus, it may be possible to produce a visually compelling …
Experiments In Pool Boiling Heat Transfer And Nucleationdynamics Of High Pressure Refrigerants, Daniel Joo
Experiments In Pool Boiling Heat Transfer And Nucleationdynamics Of High Pressure Refrigerants, Daniel Joo
Electronic Theses and Dissertations
A high pressure pool boiling experiment of pressurized R134a is designed and built, utilizing thermochromatic liquid crystal techniques. Liquid crystals thermo-chromatography uses encapsulated liquid crystals that are sensitive to temperature. When exposed to hot temperatures the crystal reflect a blue/violet color, and when exposed to cooler temperatures it reflects a red/orange color. The color value or hue is proportional to its temperature. Using this technique this experiment is capable of studying the physics and thermodynamics of refrigerants under nucleate pool boiling. The main objective of this experiment was the design of the experimental setup. Various designs were tested and validated, …
Reduction Of Vortex-Driven Oscillations In A Solid Rocket Motor Cold Flow Simulation Through Active Control, Jami Ward
Electronic Theses and Dissertations
Control of vortex-driven instabilities was demonstrated via a scaled-down, cold-flow simulation that modeled closed-end acoustics. When vortex shedding frequencies couple with the natural acoustic modes of a choked chamber, potentially damaging low-frequency instabilities may arise. Although passive solutions can be effective, an active control solution is preferable. An experiment was performed to demonstrate an active control scheme for the reduction of vortex-driven oscillations. A non-reacting experiment using a primary flow of air, where both the duct exit and inlet are choked, simulated the closed-end acoustics. Two plates, separated by 1.27 cm, produced the vortex shedding phenomenon at the chamber's first …
Electrical Properties Of Reactive Magnetron Sputtered Vanadium Oxide Thin Films, Vu Huynh Lam
Electrical Properties Of Reactive Magnetron Sputtered Vanadium Oxide Thin Films, Vu Huynh Lam
Electronic Theses and Dissertations
It is well known that vanadium oxide can take many different forms. However for this study, only the amorphous phase was investigated. Amorphous vanadium oxide (VOx) thin films were deposited on thermally grown silicon dioxide by DC magnetron sputtering using a vanadium metal target in an argon / oxygen atmosphere. The driving force of this study was to investigate the temperature coefficient of resistance (TCR) and low resistivity in the amorphous films. Sheet resistance is very sensitive to small changes in temperature, making amorphous VOx very attractive to thermal sensor applications such as infrared detectors. To form the vanadium oxide, …