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Articles 1 - 15 of 15
Full-Text Articles in Mechanical Engineering
Mapping Of Pressure Losses Through Microchannels With Sweeping-Bends Of Various Angle And Radii, Chase Hansel
Mapping Of Pressure Losses Through Microchannels With Sweeping-Bends Of Various Angle And Radii, Chase Hansel
Electronic Theses and Dissertations
MEMS (Micro Electro Mechanical Systems) have received a great deal of attention in both the research and industrial sectors in recent decades. The broad MEMS category, microfluidics, the study of fluid flow through channels measured on the micrometer scale, plays an important role in devices such as compact heat exchangers, chemical and biological sensors, and lab-on-a-chip devices. Most of the research has been focused on how entire systems operate, both experimentally and through simulation. This paper strives, systematically, to map them through experimentation of the previous to untested realm of pressure loss through laminar square-profile sweeping-bend microchannels. Channels were fabricated …
Pressure Losses Experienced By Liquid Flow Through Pdms Microchannels With Abrupt Area Changes, Jonathan Wehking
Pressure Losses Experienced By Liquid Flow Through Pdms Microchannels With Abrupt Area Changes, Jonathan Wehking
Electronic Theses and Dissertations
Given the surmounting disagreement amongst researchers in the area of liquid flow behavior at the microscale for the past thirty years, this work presents a fundamental approach to analyzing the pressure losses experienced by the laminar flow of water (Re = 7 to Re = 130) through both rectangular straight duct microchannels (of widths ranging from 50 to 130 micrometers), and microchannels with sudden expansions and contractions (with area ratios ranging from 0.4 to 1.0) all with a constant depth of 104 micrometers. The simplified Bernoulli equations for uniform, steady, incompressible, internal duct flow were used to compare flow through …
User-Defined Patterning Of Neural Progenitor Cells On 3d Micropillar Arrays Using Round Cross-Sectional Geometry, Specific Dimen, Andrea Wesser
User-Defined Patterning Of Neural Progenitor Cells On 3d Micropillar Arrays Using Round Cross-Sectional Geometry, Specific Dimen, Andrea Wesser
Electronic Theses and Dissertations
The ability to control stem cell functions, particularly neuronal progenitors, has long since been believed to be the key to successful treatment of neurodegenerative disorders such as Alzheimer's, Parkinson's and accidents involving head trauma. The neurology field calls for many new solutions to address the controlled neural stem cell seeding and placement of cells for neural tissue regeneration. Self-assembled monolayers (SAM) from the alkanethiol group provide a straightforward applicable, reliable treatment for cell adhesion. An ODT/gold treatment was used to adhere the cells to patterned areas, due mainly to a high confluence of cells attracted to it, as well as …
Low Reynolds Number Water Flow Characteristics Through Rectangular Micro Diffusers/Nozzles With A Primary Focus On Major/Minor P, Kyle Hallenbeck
Low Reynolds Number Water Flow Characteristics Through Rectangular Micro Diffusers/Nozzles With A Primary Focus On Major/Minor P, Kyle Hallenbeck
Electronic Theses and Dissertations
The field of microfluidics has recently been gathering a lot of attention due to the enormous demand for devices that work in the micro scale. The problem facing many researchers and designers is the uncertainty in using macro scaled theory, as it seems in some situations they are incorrect. The general idea of this work was to decide whether or not the flow through micro diffusers and nozzles follow the same trends seen in macro scale theory. Four testing wafers were fabricated using PDMS soft lithography including 38 diffuser/nozzle channels a piece. Each nozzle and diffuser consisted of a throat …
Fundamental Study Of Fc-72 Pool Boiling Surface Temperature Fluctuations And Bubble Behavior, Alison Griffin
Fundamental Study Of Fc-72 Pool Boiling Surface Temperature Fluctuations And Bubble Behavior, Alison Griffin
Electronic Theses and Dissertations
A heater designed to monitor surface temperature fluctuations during pool boiling experiments while the bubbles were simultaneously being observed has been fabricated and tested. The heat source was a transparent indium tin oxide (ITO) layer commercially deposited on a fused quartz substrate. Four copper-nickel thin film thermocouples (TFTCs) on the heater surface measured the surface temperature, while a thin layer of sapphire or fused silica provided electrical insulation between the TFTCs and the ITO. The TFTCs were micro-fabricated using the liftoff process to deposit the nickel and copper metal films. The TFTC elements were 50 microns wide and overlapped to …
Effect Of Pressure Gradient And Wake On Endwall Film Cooling Effectiveness, Sylvette Rodriguez
Effect Of Pressure Gradient And Wake On Endwall Film Cooling Effectiveness, Sylvette Rodriguez
Electronic Theses and Dissertations
Endwall film cooling is a necessity in modern gas turbines for safe and reliable operation. Performance of endwall film cooling is strongly influenced by the hot gas flow field, among other factors. For example, aerodynamic design determines secondary flow vortices such as passage vortices and corner vortices in the endwall region. Moreover blockage presented by the leading edge of the airfoil subjects the incoming flow to a stagnating pressure gradient leading to roll-up of the approaching boundary layer and horseshoe vortices. In addition, for a number of heavy frame power generation gas turbines that use cannular combustors, the hot and …
Design And Fabrication Of Chemiresistor Typemicro/Nano Hydrogen Gas Sensors Usinginterdigitated Electrodes, Peng Zhang
Design And Fabrication Of Chemiresistor Typemicro/Nano Hydrogen Gas Sensors Usinginterdigitated Electrodes, Peng Zhang
Electronic Theses and Dissertations
Hydrogen sensors have obtained increased interest with the widened application of hydrogen energy in recent years. Among them, various chemiresistor based hydrogen sensors have been studied due to their relatively simple structure and well-established detection mechanism. The recent progress in micro/nanotechnology has accelerated the development of small-scale chemical sensors. In this work, MEMS (Micro-Electro-Mechanical Systems) sensor platforms with interdigitated electrodes have been designed and fabricated. Integrating indium doped tin dioxide nanoparticles, these hydrogen sensors showed improved sensor characteristics such as sensitivity, response and selectivity at room temperature. Design parameters of interdigitated electrodes have been studied in association with sensor characteristics. …
Meshless Hemodynamics Modeling And Evolutionary Shape Optimization Of Bypass Grafts Anastomoses, Zaher El Zahab
Meshless Hemodynamics Modeling And Evolutionary Shape Optimization Of Bypass Grafts Anastomoses, Zaher El Zahab
Electronic Theses and Dissertations
Objectives: The main objective of the current dissertation is to establish a formal shape optimization procedure for a given bypass grafts end-to-side distal anastomosis (ETSDA). The motivation behind this dissertation is that most of the previous ETSDA shape optimization research activities cited in the literature relied on direct optimization approaches that do not guaranty accurate optimization results. Three different ETSDA models are considered herein: The conventional, the Miller cuff, and the hood models. Materials and Methods: The ETSDA shape optimization is driven by three computational objects: a localized collocation meshless method (LCMM) solver, an automated geometry pre-processor, and a genetic-algorithm-based …
Thermal Modeling And Laser Beam Shaping For Microvias Drilling In High Density Packaging, Chong Zhang
Thermal Modeling And Laser Beam Shaping For Microvias Drilling In High Density Packaging, Chong Zhang
Electronic Theses and Dissertations
Laser drilling of microvias for organic packaging applications is studied in present research. Thermal model is essential to understand the laser-materials interactions and to control laser drilling of blind micro holes through polymeric dielectrics in multilayer electronic substrates. In order to understand the profile of the drilling front irradiated with different laser beam profiles, a transient heat conduction model including vaporization parameters is constructed. The absorption length in the dielectric is also considered in this model. Therefore, the volumetric heating source criteria are applied in the model and the equations are solved analytically. The microvia drilling speed, temperature distribution in …
Methane And Dimethyl Ether Oxidation At Elevated Temperatures And Pressure, Christopher Zinner
Methane And Dimethyl Ether Oxidation At Elevated Temperatures And Pressure, Christopher Zinner
Electronic Theses and Dissertations
Autoignition and oxidation of two Methane (CH4) and Dimethyl Ether (CH3OCH3 or DME) mixtures in air were studied in shock tubes over a wide range of equivalence ratios at elevated temperatures and pressures. These experiments were conducted in the reflected shock region with pressures ranging from 0.8 to 35.7 atmospheres, temperatures ranging from 913 to 1650 K, and equivalence ratios of 2.0, 1.0, 0.5, and 0.3. Ignition delay times were obtained from shock-tube endwall pressure traces for fuel mixtures of CH4/CH3OCH3 in ratios of 80/20 percent volume and 60/40 percent volume, respectively. Close examination of the data revealed that energy …
Unsteady Incompressible Navier-Stokes Simulations On Deforming Domains, Atefeh Shadpour
Unsteady Incompressible Navier-Stokes Simulations On Deforming Domains, Atefeh Shadpour
Electronic Theses and Dissertations
Mesh generation has been an important topic of research for the past four decades, primarily because it is one of the critical elements in the numerical simulation of fluid flows. One of the main current issues in this regard is mesh generation and flow solution on domains with moving boundaries. In this research, a novel scheme has been proposed for mesh generation on domains with moving boundaries, with the location of boundary nodes known at any particular time. A new set of linearized equations is derived based on a full nonlinear elliptic grid generation system. The basic assumption in deriving …
Water Footprint Of Aviation Fuel Synthesis By The Fischer Tropsch Process Using Sugar Cane Waste & Landfill Gas As Feedstocks, Slim Menzli
Electronic Theses and Dissertations
The recent spikes in oil prices have spurred an already bullish demand on biofuels as a source of alternative energy. However, the unprecedented price records set simultaneously by staple food have raised high concerns about potential impacts of biofuels on the global agricultural landscape as fuel and food markets are being inextricably coupled. The revival of interest in the Fischer-Tropsch (FT) process comes into full force since it offers a promising way to produce carbon-neutral liquid fuels which are readily usable with today's existing infrastructure. The FT synthesis offers the possibility of using crop waste as feedstock instead of the …
Design And Experimental Study Of An Integrated Vapor Chamber -" Thermal Energy Storage System, Krishna Kota
Design And Experimental Study Of An Integrated Vapor Chamber -" Thermal Energy Storage System, Krishna Kota
Electronic Theses and Dissertations
Future defense, aerospace and automotive technologies involve electronic systems that release high pulsed waste heat like during high power microwave and laser diode applications in tactical and combat aircraft, and electrical and electronic systems in hybrid electric vehicles, which will require the development of an efficient thermal management system. A key design issue is the need for fast charging so as not to overheat the key components. The goal of this work is to study the fabrication and technology implementation feasibility of a novel high energy storage, high heat flux passive heat sink. Key focus is to verify by theory …
A Customer Programmable Microfluidic System, Miao Liu
A Customer Programmable Microfluidic System, Miao Liu
Electronic Theses and Dissertations
Microfluidics is both a science and a technology offering great and perhaps even revolutionary capabilities to impact the society in the future. However, due to the scaling effects there are unknown phenomena and technology barriers about fluidics in microchannel, material properties in microscale and interactions with fluids are still missing. A systematic investigation has been performed aiming to develop "A Customer Programmable Microfluidic System". This innovative Polydimethylsiloxane (PDMS)-based microfluidic system provides a bio-compatible platform for bio-analysis systems such as Lab-on-a-chip, micro-total-analysis system and biosensors as well as the applications such as micromirrors. The system consists of an array of microfluidic …
An Improved Thermoregulatory Model For Cooling Garment Applications With Transient Metabolic Rates, Johan Westin
An Improved Thermoregulatory Model For Cooling Garment Applications With Transient Metabolic Rates, Johan Westin
Electronic Theses and Dissertations
Current state-of-the-art thermoregulatory models do not predict body temperatures with the accuracies that are required for the development of automatic cooling control in liquid cooling garment (LCG) systems. Automatic cooling control would be beneficial in a variety of space, aviation, military, and industrial environments for optimizing cooling efficiency, for making LCGs as portable and practical as possible, for alleviating the individual from manual cooling control, and for improving thermal comfort and cognitive performance. In this study, we adopt the Fiala thermoregulatory model, which has previously demonstrated state-of-the-art predictive abilities in air environments, for use in LCG environments. We validate the …