Engineering Commons^™

การพัฒนาเครื่องพลาสมาเย็นแบบเจ็ตที่ความดันบรรยากาศสำหรับการทำให้เลือดแข็งตัว, ณัฐนพิญช์ จรูญศักดิ์

Chulalongkorn University Theses and Dissertations (Chula ETD)

งานวิจัยนี้เป็นการพัฒนาเครื่องพลาสมาเย็นแบบเจ็ตที่ความดันบรรยากาศสำหรับการทำให้เลือดแข็งตัวที่ประกอบด้วย 2 ส่วนหลักคือ แหล่งจ่ายไฟฟ้าแรงดันสูงความถี่สูงชนิดกระแสสลับ แบบฟลายแบค (Fly back) ที่ควบคุมการทำงานด้วยไมโครคอนโทรลเลอร์และพลาสมาโปรบด้วยวัสดุอุปกรณ์ที่หาได้ในประเทศ โดยออกแบบให้สามารถปรับตั้งค่าความถี่และดิวตี้ไซเคิลผ่านระบบไมโครคอนโทรลเลอร์ได้ที่ความถี่ 30 35 และ 40 kHz และเปอร์เซ็นต์ดิวตี้ไซเคิล 30 40 50 และ 70 % ตามลำดับ ส่วนการปรับตั้งค่าของไฟฟ้าแรงดันสูงเป็นการปรับด้วยมือได้ตั้งแต่ 0.1 ถึง 15 kVrms จากผลการทดลองพบว่า แหล่งจ่ายไฟฟ้าแรงดันสูงความถี่สูงชนิดกระแสสลับที่พัฒนาขึ้นมีประสิทธิภาพการทำงานเท่ากับ 74.28 % การศึกษาผลกระทบของตัวแปรต่างๆต่อความยาวและอุณหภูมิของพลาสมาเจ็ต พบว่าค่าไฟฟ้าแรงดันสูง ความถี่ เปอร์เซ็นต์ดิวตี้ไซเคิล และอัตราการไหลของก๊าซอาร์กอน เป็นตัวแปรสำคัญที่ส่งผลต่อความสม่ำเสมอของเปลวพลาสมา ผลการวิเคราะห์คุณสมบัติของพลาสมาด้วยเครื่อง Optical Emission Spectroscopy (OES) พบว่า มีอุณหภูมิของอิเล็กตรอนที่ความถี่ต่างๆและที่อัตราการไหลต่างๆที่มีค่าเท่ากับ 0.43 eV และความหนาแน่นของอิเล็กตรอนของพลาสมาอยู่ในช่วง 5.46x109 – 1.74x1012 cm-3 ซึ่งสามารถระบุได้ว่าพลาสมาแบบเจ็ตที่พัฒนาขึ้นเป็นพลาสมาเย็น จากผลทดสอบการแข็งตัวของเลือดด้วยเครื่องพลาสมาเย็นแบบเจ็ตที่พัฒนาขึ้น พบว่า ที่ระยะห่างระหว่างปลายโปรบกับกระจกสไลด์ 1 เซนติเมตร พลาสมาเย็นแบบเจ็ตที่พัฒนาขึ้นสามารถทำให้เลือดที่ผสมสารต้านการแข็งตัวของเลือด EDTA ปริมาณ 2.5 µL. ให้แข็งตัวภายในเวลาประมาณ 20 วินาที ได้เร็วกว่าเลือดผสมสาร EDTA ที่ไม่ผ่านการฉายด้วยพลาสมาและเลือดผสมสาร EDTA ที่ผ่านการเป่าด้วยก๊าซอาร์กอนที่อัตราการไหลของก๊าซอาร์กอน 5 L/min

Analysis Of Mechanical Properties Of Alternative Timber Beams For A Native American Earth Lodge, Freddy E. Moran

Electronic Theses and Dissertations

To fill a gap in the literature, this thesis explored the mechanical properties for alternative roof beams of a historic Native American Hidatsa earth lodge. The research demonstrates that in those alternative beams, when Moisture Content (MC) increases, Modulus of Elasticity (E) decreases and deflection increases. The procedure included obtaining dimensions for alternative beams from scaled sketches created by ethnographers and informants who recorded an actual Hidatsa earth lodge in the early 1800s (confirmed by other sources) although no material properties studies have resulted. After calculating loads, the variations in the E were determined using an equation. Using linear analysis, …

Research Area 1: Vehicle Lightweight Design And Safety, Vlsj Lab, Mechanical Engineering Department, Georgia Southern University

VLSJ Lab: Research Areas (Archived)

No abstract provided.

Biphasic Cellulose Acetate/Rtil Membranes And Functionalized Graphene Adsorbents For Natural Gas Processing: Experimental And Molecular Simulation Studies, Amir Khakpay

Electronic Theses and Dissertations

In this dissertation, gas separation using membranes is investigated for natural gas upgrading. The main objectives of this study are separation of high value hydrocarbons such as propane (c3h8) from natural gas and carbon dioxide (co2) separation from light gases such as nitrogen (n2) and methane (ch4). To achieve these goals, supported ionic liquid membranes (silms), biphasic membranes, and nanoporous graphene (npg) and graphene oxide (npgo) membranes are studied. Biphasic membranes are proposed to overcome silms issues for gas separation. The major issues with silms are low room temperature ionic liquid (rtil) content and instability at high cross-membrane pressure. For …

Designing Framework For The Computer Aided Design Of Silicon Carbide Jfet Circuits In Bleo Environments, Venkata Vinay Naidugari

Electronic Theses and Dissertations

Abstract: circuit design and testing are two essential processes to synthesis of an efficient and reliable circuit. Real-time testing of a circuit through circuit fabrication and development is an expensive and a risky procedure whereas testing the circuit by modelling and simulating is more efficient and inexpensive. Silicon-based semiconductors are the basic components of any modern day electronic devices, and their usage has dominated the marketplace. But these conventional cmos devices cannot exist in an environment consisting of harsh radiation, high temperature and many other environmental conditions, such as venus or mars. However, 6h-sic jfets, which are basic logic gate …

Comparing The Depositional Environment Of The Upper Smackover Formation In Southwestern Clarke County, Mississippi And Brooklyn/ Little Cedar Creek Field, Alabama, Elsie Ekene Okoye

Electronic Theses and Dissertations

This research evaluated the depositional settings of the upper Smackover formation in southwestern Clarke County (scc), Mississippi and compared its facies to those of the Brooklyn and little cedar creek fields (bf/lcc) in Conecuh and Escambia Counties, Alabama. The Smackover formation has been a prolific oil producing formation in the Gulf of Mexico since its discovery in Union County, Arkansas in 1937. The discovery of the lcc in 1994 and the bf in 2007 has generated additional interest in the Smackover. The bf/ lcc occur near the updip limit of the upper Jurassic (Oxfordian) Smackover formation. These fields produce from …

Graphene Nano-Composites For Hypervelocity Impact Applications, Alharith Manasrah

Electronic Theses and Dissertations

The Low Earth Orbit (LEO) is a harsh environment cluttered with natural meteoroids and man-made debris, which can travel at velocities approaching 15 km/s. Most space activities within the LEO will encounter this environment. Thus, the spacecraft and its hardware must be designed to survive debris impact. This research introduces new procedures to produce a nano-composite material with mortar-brick nano-structure inspired from nacre. Nacre-like composites were successfully manufactured, based on three host polymers, with a wide range of graphene concentrations. The manufactured exfoliated graphene nano-platelet, embedded in a host polymer, provided good potential for enhancement of the hypervelocity impact (HVI) …

Mechanical And Computational Evaluation Of Cementitious Materials With Hollow Glass Microsphere Inclusions, Zachary J. Wallace

Electronic Theses and Dissertations

The effect of volumetric replacement of cementitious materials by an inert filler known as hollow glass microspheres on elastic properties is evaluated in this study through a combined computational and experimental approach. This approach considered the variation in properties of type I Portland cement for 0, 5, 10, and 15% volume fractions of two kind of glass microspheres; one was high density with high crushing strength, and the other with a relative lower density. Using a suite of software called Virtual Cement and Concrete Testing Laboratory (VCCTL), the microstructural details were determined for 80% degree of hydration of the cement …

Phase Stability In Cobalt-Based L12 Quaternary Intermetallics From Density Functional Theory, William Earwood

Electronic Theses and Dissertations

The effects of higher order alloying additions (Mo, Ti, Ta, Hf, Fe, V) on the phase stability of L12 (γ’) intermetallics have been studied via first-principles. A 32 atom special-quasi-random structure was used to mimic the experimentally observed solid solution sublattice. Density of states distributions were generated in order to directly observe the impact of alloying additions on the position of the pseudogap and number of states at the Fermi level. Charge density differences across the supercell were visualized to analyze changes in bonding behavior. The results indicate that substitutions of Ti, Ta, and Hf in place of the central …

Band Gap Engineering Of Titania Systems Purposed For Photocatalytic Activity, Cameron Robert Thurston

Electronic Theses and Dissertations

Ab initio computer aided design drastically increases candidate population for highly specified material discovery and selection. These simulations, carried out through a first-principles computational approach, accurately extrapolate material properties and behavior. Titanium dioxide (tio2) is one such material that stands to gain a great deal from the use of these simulations. In its anatase form, titania (tio2) has been found to exhibit a band gap nearing 3.2 ev. If titania is to become a viable alternative to other contemporary photoactive materials exhibiting band gaps better suited for the solar spectrum, then the band gap must be subsequently reduced. To lower …

Lessons Learned From A 10-Year Collaboration Between Biomedical Engineering And Industrial Design Students In Capstone Design Projects, Jay R. Goldberg, Pascal Malassigné

Biomedical Engineering Faculty Research and Publications

Engineers and industrial designers have different approaches to problem solving. Both place heavy emphasis on identification of customer needs, manufacturing methods, and prototyping. Industrial designers focus on aesthetics, ergonomics, ease of use, manufacturing methods, and the user’s experience. They tend to be more visual and more concerned with the interaction between users and products. Engineers focus on functionality, performance requirements, analytical modeling, and design verification and validation. They tend to be more analytical and more concerned with the design of internal components and product performance. Engineers and industrial designers often work together on project teams in industry. Collaboration between the …

Mechanical Characterization And Non-Destructive Evaluation Of Sicf-Sicm Composite Tubing With The Impulse Excitation Technique, Nathaniel Truesdale

Theses and Dissertations

With growing interest on ceramic fiber reinforced ceramic matrix composites (CMC) for accident tolerant fuel, the need for mechanical characterization of ceramic composite arises. It has been of particular interest to non-destructively evaluate the mechanical performance of these composites. Impulse excitation (IE) is a well-established method for non-destructive mechanical characterization of homogeneous isotropic material of well-defined shapes. In this thesis, impulse excitation technique was applied for non-destructive characterization of composite tube for the first time as far as we know. CMC, when stressed beyond its damage threshold, will experience various forms of structural damage, such as matrix micro-cracking, fiber-matrix debonding, …

Growth And Characterization Of Anisotropic Gase Semiconductor For Radiation Detection And Thz Applications, Haseeb Nazir

Theses and Dissertations

Anisotropic wide-bandgap gallium selenide (GaSe) crystals were grown using high purity (7N) Ga and zone refined (ZR) Se precursor materials. The crystal growth was performed using a modified vertical Bridgman method (VBM) with a slow crystallization from the melt and with a pre-determined temperature profile. The structure, surface morphology, and the composition of the grown crystals were characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive analysis by x-rays (EDAX), respectively. Optical absorption and transmission properties were characterized and optical bandgap was determined. Electrical resistivity has been determined using current-voltage (I V) measurements using van der Pauw …

Autonomous Driving Platform Performance Analysis, Charles R. Rickarby

Honors Theses and Capstones

Through data analysis of various plots and figures it will be possible to determine the best control parameters to get the best performance out of the autonomous driving platform. This data, presented in this thesis, will show quantitatively what the best control strategies are through comparison of different versions of the platform.

Synthesis Of Copper Oxide Nanoparticles In Droplet Flow Reactors, Christopher Reilly

Honors Theses and Capstones

Synthesis of metal oxide nanoparticles within droplet flow reactors is advantageous over batch synthesis due to the elimination of concentration and temperature gradients inside the reactor and prevention of reactor fouling. We present results on the synthesis of copper oxide nanoparticles using aqueous droplets of copper acetate and acetic acid inside a bulk stream of sodium hydroxide in 1-octanol. Varying the copper acetate, acetic acid, and sodium hydroxide concentration resulted in needle-like and plate-like nanoparticles of varying sizes. The rate of mass transfer from the bulk to the droplet phase was found to increase with flow rate and addition of …

Three Segment Adaptive Power Electronic Compensator For Non-Periodic Currents, Amin Ghaderi

Theses and Dissertations

In this dissertation, a new technique is proposed for the compensation of nonperiodic load current. The method provides control references for three co-located devices, each corresponding to one moving calculation window and one decomposed part of the compensated current. They are slow compensator with high power rating, large calculation window, and low switching frequency; fast compensator with lower power rating, shorter calculation window, and higher switching frequency; and the reactive compensator which is an ordinary static VAR compensator (SVC). To improve the flexibility of the technique, a fuzzy based adaptive window is proposed for the slow compensator to find the …

Wideband Low Side Lobe Aperture Coupled Patch Phased Array Antennas, Dhruva Poduval

Theses and Dissertations

Low profile printed antenna arrays with wide bandwidth, high gain, and low Side Lobe Level (SLL) are in great demand for current and future commercial and military communication systems and radar. Aperture coupled patch antennas have been proposed to obtain wide impedance bandwidths in the past. Aperture coupling is preferred particularly for phased arrays because of their advantage of integration to other active devices and circuits, e.g. phase shifters, power amplifiers, low noise amplifiers, mixers etc. However, when designing such arrays, the interplay between array performance characteristics, such as gain, side lobe level, back lobe level, mutual coupling etc. must …

An Application Of Dempster-Shafer Fusion Theory To Lithium-Ion Battery Prognostics And Health Management, John Weddington

Theses and Dissertations

Prognostics and Health Management (PHM) is the discipline involving diagnostics and prognostics of components or systems, with the primary objective of increasing the overall reliability and safety of these components or systems. PHM systems convert raw sensor data into features, and utilize state observers to estimate the current damage state online. Popular state observers are the traditional Kalman filter, along with its non-linear extensions, and the particle filter. Each technique has differing advantages. This thesis investigates the fusion of results from different techniques in order to achieve a more trustworthy probability of detection (PoD) during diagnosis and a more reliable …

Promotional Effect Of Molten Carbonates On Proton Conductivity And Oxygen Reduction Reaction – An Experimental And Computational Study, Xiaolei Xiong

Theses and Dissertations

Recent research of Solid oxide fuel cells (SOFCs) is aimed to lower the operating temperature to an intermediate temperature (IT) range of 500 to 700^oC, while maintaining a proper performance. This Ph.D. research project investigates the promotional effects of alkaline carbonate eutectics on the proton conductivity of proton conducting electrolytes and cathodic ORR reactivity in SOFCs by both experimental and computational methods. The ionic conductivity of the MC-BZY composite above 500^oC increases with the higher loading of MC. The sample exhibited nearly a factor of two higher conductivity in H₂-containing atmosphere than in air. …

High Quality Low Offcut 4h-Sic Epitaxy And Integrated Growth Of Epitaxial Graphene For Hybrid Graphene/Sic Devices, Anusha Balachandran

Theses and Dissertations

Power electronic semiconductor devices are critical components in next-generation power systems such as hybrid electric vehicles and smart grid power controls enabling reduction in system size, weight, and cost. Wide bandgap materials such as SiC, GaN, and diamond have been investigated to replace silicon, due to their superior material properties. Of these, 4H-SiC is considered the most viable candidate beyond 3kV due to its technological maturity, its wide band gap (3.23 eV), high breakdown field (4×106 V/cm), high thermal conductivity (5 W/cm/K) and, more importantly, its indirect bandgap.

The main contribution of my research relates to the development and investigating …

Reducing Model Selection Computational Cost By Metamodeling The Evidence, Ramin Madarshahian

Theses and Dissertations

Modeling is an abstraction of reality that lets a designer or engineer perform simulations with a “real” object or structure without testing it physically. However, the result of simulations is as good as their models. Selecting the best model among many candidates is another challenge.

Complex models could translate into more accurate predictions, but they also require larger computational effort. The Bayes factor is often used to compare different models considering the data and analyst’s experience. To obtain the Bayes factor, the Bayesian model evidence is calculated; however, calculating the Bayesian model evidence of computationally expensive models is not a …

Investigating The Feedstock Properties And Process Conditions Influencing The Characteristics Of Products Generated From The Hydrothermal Carbonization Of Organic Feedstocks, Liang Li

Theses and Dissertations

Hydrothermal carbonization (HTC) is a novel environmentally beneficial thermal conversion process for the transformation of organic feedstocks to value-added products. However, little is known about the role of feedstock properties and/or process conditions during carbonization. This study was conducted to determine the parameters most influential during the HTC of organic feedstocks. Experiments and statistical analyses were conducted to: (1) determine the effect of specific feedstocks, feedstock interactions, and process conditions on carbonization product characteristics; (2) understand how initial liquid characteristics influence product characteristics and evaluate the significance of these initial liquid characteristics in predicting product characteristics; and (3) develop statistical …

Study Of Mos2 And Graphene-Based Heterojunctions For Electronic And Sensing Applications, Ifat Jahangir

Theses and Dissertations

Since the discovery of graphene, there has been an increase in two-dimensional (2D) materials research for their scalability down to atomic dimensions. Among the analogs of graphene, transition metal dichalcogenides (TMDs) are attractive due to their exceptional electronic and optoelectronic properties. MoS2, a TMD, has several advantages over graphene and the industry workhorse Si, and has been reported to demonstrate excellent transistor performances. The key obstacle in the commercialization of MoS2 technology is low carrier mobility over large areas for top-down devices. Although there were several early reports on synthesis of atomically thin MoS2 with moderate mobility, transferring large area …

Distributed Optimization Method For Intelligent Control Of Dc Microgrids, Yuanyuan Fan

Theses and Dissertations

Most of the distributed energy resources, loads and energy storage systems in a DC microgrid are equipped with power electronic converters. With the integration of advanced power electronics devices, a microgrid is able to utilize a broader range of technologies in its design and operation. A key feature of power electronic converter based systems is the ability to direct energy flow within a system with their coordinated operation. A system level control is needed for coordination where converters execute reference points dictated by a system-level control in order to achieve system level goals. System goals can be expressed as a …

A Lebesgue Sampling Based Diagnosis And Prognosis Methodology With Application To Lithium-Ion Batteries, Wuzhao Yan

Theses and Dissertations

Fault diagnosis and prognosis (FDP) plays an important role in the modern complex industrial systems to maintain their reliability, safety, and availability. Diagnosis aims to monitor the fault state of the component or the system in real-time. Prognosis refers to the generation of long-term predictions that describe the evolution of a fault and the estimation of the remaining useful life (RUL) of a failing component or subsystem.

Traditional Riemann sampling-based FDP (RS-FDP) takes samples and executes algorithms in periodic time intervals and, in most cases, requires significant computational resources. This makes it difficult or even impossible to implement RS-FDP algorithms …

Atherosclerotic Plaque Adhesion Strength And Its Role In Plaque Rupture, Bilal Merei

Theses and Dissertations

Cardiovascular diseases are disorders affecting the blood vessels and the heart. According to the World Health Organization, cardiovascular diseases are one of the leading causes of death worldwide. They are responsible for over 17.1 million deaths per year worldwide, representing 31.5% of deaths 1, 2. Atherosclerosis, a chronic inflammatory disorder affecting large arteries, is the underlying cause of many cardiovascular diseases. Plaque rupture is a serious complication of advanced atherosclerosis, often leading to life-threatening clinical consequences such as myocardial infarction (heart attack) or stroke. 75% of newly developed myocardial infarction cases are caused by atherosclerotic plaque rupture. It affects approximately …

Ultrathin Graphene Oxide Membranes For Water Purification: Fundamentals & Potential Applications, Weiwei Xu

Theses and Dissertations

To develop ultrathin GO membranes with both high permeation rate and excellent selectivity, it is essential to understand the interlayer nanostructure and its influence on water purification performance. We purposely deposited GO at a fast rate and at a rate ~12 times slower to control the interlayer nanostructure of the resulting membranes. The d-spacing difference between proposed thermodynamically favored interlayer structure which formed at slow deposition rate and another relative randomly packed interlayer structure formed at fast deposition rate were corroborated by XRD, organic vapor deposition, and AFM. Molecular dynamics simulations further confirmed that, in type I structure, functionalized patches …

Pollutant Formation In Oxy-Coal Combustion, Nujhat Choudhury

Theses and Dissertations

With the increasing levels of carbon dioxide (CO2) in the atmosphere, researchers are driven to seek cleaner combustion techniques to burn coal for power generation. Oxy-coal combustion is a promising technique to cut down CO2 emissions. This technology requires the introduction of a pure oxygen (O2) stream and a recycled flue gas stream into the boiler instead of air. Flue gas stream generated from the system will be low in volume and highly concentrated in CO2. Thus, the capture and sequestration process will be facilitated. But, one of the concerns of adopting this technology is the altered chemistry of pollutants …

Non-Destructive Evaluation Of Composites: Predictive Ultrasonic Guided-Waves Modeling, Non-Destructive Material Characterization, And The Application To Aerospace Structures, Darun Barazanchy

Theses and Dissertations

To predict guided wave dispersion curves, it is common to use different solution approaches depending on the material type (isotropic or anisotropic) of the medium in which the wave propagates. The two different solution methods are defined in different domains, frequency-phase velocity domain for isotropic materials and wavenumber-phase velocity domain for anisotropic materials. This may lead to difficulties and unsatisfying results when predicting the dispersion curves for hybrid laminates which contain both isotropic and anisotropic materials. Therefore, a unified formulation defined in the wavenumber-phase velocity domain to accomodate both isotropic and anisotropic materials, as well as hybrid combinations, is desired. …

Confluence Of Density Currents Produced By Lock-Exchange, Hassan Ismail

Theses and Dissertations

Density currents represent a broad classification of flows driven by the force of gravity acting on a fluid with variable density. With examples of density currents including turbidity currents, sand storms, salt wedges in tidal rivers, and oil spills, a great deal of attention has been previously given to understanding the underlying mechanisms of such flows and implications of those flows on fluid, species, and sediment transport. Although documented confluences occur naturally in terrestrial and submarine settings,little attention has been given to understanding the confluence of two density currents.

This study furthers the state of knowledge on density current confluences …