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Articles 301 - 330 of 452
Full-Text Articles in Mechanical Engineering
Design And Realization Of An Electrophoretron Cycler, Celine Raymonde Ramet
Design And Realization Of An Electrophoretron Cycler, Celine Raymonde Ramet
LSU Master's Theses
Polymerase Chain Reaction (PCR) is a powerful enzymatic reaction commonly used to amplify specific sequences of Deoxyribo Nucleic Acid (DNA). Since the introduction of the lab on a chip concept, numerous Continuous Flow PCR cyclers were realized with success at the micro scale. As reducing the reactor size and improving thermal management led to reduced sample volumes, results could be achieved much faster with these CF-PCR cyclers than with common commercial cycler. Furthermore, most of these demonstrated CF-PCRs are nowadays evolving towards high-throughput systems. However, most CF-PCR cyclers require complex manipulations and are not flexible (e.g. fixed number of cycles, …
High Strain Rate Characteristics Of Rubber Modified Syntactic Foams, Paul Wehmer
High Strain Rate Characteristics Of Rubber Modified Syntactic Foams, Paul Wehmer
LSU Master's Theses
This thesis deals with the characterization of hybrid syntactic foams under high strain rates (HSR) ranging from 450/s to 1000/s. The foams studied are comprised of epoxy resin matrix filled with 63% volume fraction glass microspheres and 2% volume fraction of ground rubber fragments. The focus of this study is to compare the strength, ultimate strain, and modulus of these composite materials at high strain rates and quasi-static conditions and to find out the effects of HSR on the failure mode and fracture behavior of these materials. Split Hopkinson Pressure Bar (SHPB) apparatus is used for the HSR testing. Foams …
Experimental And Numerical Investigation Of Fluid Flow And Heat Transfer In Microchannels, Wynn Allen Phillips
Experimental And Numerical Investigation Of Fluid Flow And Heat Transfer In Microchannels, Wynn Allen Phillips
LSU Master's Theses
Microchannels are of current interest for use in heat exchangers where very high heat transfer performance is desired. Microchannels provide very high heat transfer coefficients because of their small hydraulic diameters. In this study, an investigation of fluid flow and heat transfer in microchannels is conducted. A review of the literature published regarding fluid flow and heat transfer in microchannels is provided in this study. A thorough background on the theory of internal convective heat transfer is provided as well. A critical analysis of some of the published heat transfer experiments on microchannels is also given. It was found that …
Nanoclay Syntactic Foam Composites, Sameer Leo Peter
Nanoclay Syntactic Foam Composites, Sameer Leo Peter
LSU Master's Theses
Syntactic foams are composite materials in which the matrix phase is reinforced with hollow particles called microballoons. They possess low moisture absorption, low thermal conductivity and high damage tolerance because of their compositions. Traditionally, syntactic foams are used in many high strength applications such as in aerospace and marine industries, thus there is a need to achieve both high compressive strength and high fracture strain with minimal increase in density. This research studies the effect of nanoclay on the high strain rate mechanical properties of syntactic foams. Nanoclay reinforced syntactic foams are fabricated by adding 1, 2 and 5% volume …
Design, Fabrication, And Testing Of A Micro Fuel Injection Swirler For Lean Premixed Combustion In Gas Turbine Engines, Anthony Louis Giglio
Design, Fabrication, And Testing Of A Micro Fuel Injection Swirler For Lean Premixed Combustion In Gas Turbine Engines, Anthony Louis Giglio
LSU Master's Theses
Due to growing energy demands and the need for increased fuel consumption efficiency, environmental protection agencies are imposing more stringent emissions regulations on gas turbine combustion systems with emphasis on NOx emissions reduction. Emerging technological combustion schemes to reduce NOx commonly employ lean premixed combustion. Decreases in NOx are globally obtained by flame temperature decrease and locally improved by homogeneity of the reacting mixture. A new micro fuel injection swirler, capable of providing efficient and rapid mixing over a short distance, is presented in this thesis. The conception of the Micro Fuel Injection Swirler (MFIS) was motivated by the need …
Freezing Processes In Cell Suspensions Evaluated Using Cryomicroscopy, Tathagata Acharya
Freezing Processes In Cell Suspensions Evaluated Using Cryomicroscopy, Tathagata Acharya
LSU Master's Theses
This thesis aims at evaluating the freezing response of three different cell types, Pacific Oyster embryos, Jurkats and Helas, using the technique of cryomicroscopy. The choice of cells was primarily based on supporting ongoing research work at the Bioengineering Laboratory, Department of Mechanical Engineering at Louisiana State University in Baton Rouge. On a secondary basis, the cells were chosen based on their contrasting nature. While Pacific Oyster being a favorite food in USA calls for successful techniques of cryopreservation of their embryos in order to keep up with the growing demand, Jurkat and HeLa are undesired malignant human cells that …
Quasi-Static And Impact Characterization Of Sandwich Structures With An Iso-Grid Stiffened Syntactic Foam Core, Venkata Sandeep Chakka
Quasi-Static And Impact Characterization Of Sandwich Structures With An Iso-Grid Stiffened Syntactic Foam Core, Venkata Sandeep Chakka
LSU Master's Theses
In this study, a novel hybrid sandwich structure with an integrated, iso-grid stiffened syntactic foam core was fabricated and evaluated by impact test and static test. Sandwich beams with different grid cell areas were prepared using a pin-guided dry weaving process. Low velocity impact test on different locations (rib, node, and bay) was conducted with varying hammer weight and impact velocities by an instrumented impact testing machine. Ultrasonic C-scan was utilized before and after impact to identify the damage induced by impact. Scanning Electron Microscopy observation was also implemented to visualize the impact damage at micro- length scale. Compressions after …
Microassembly Technology For Modular, Polymer Microfluidic Devices, Byoung Hee You
Microassembly Technology For Modular, Polymer Microfluidic Devices, Byoung Hee You
LSU Doctoral Dissertations
Assembly of modular, polymer microfluidic devices with different functions to obtain more capable instruments may significantly expand the options available for detection and diagnosis of disease through DNA analysis and proteomics. For connecting modular devices, precise, passive alignment structures can be used to prevent infinitesimal motions between the devices and minimize misalignment. The motion and constraint of passive alignment structures were analyzed using screw theory. A combination of three v-groove and hemisphere-tipped post joints constrained all degrees of freedom of the two mating modules without overconstraint. Simulations and experiments were performed to assess the predictability of dimensional and location variations …
Parametric Study Of A Pulsed Vertical Jet In Cross-Flow, Guillaume Francois Bidan
Parametric Study Of A Pulsed Vertical Jet In Cross-Flow, Guillaume Francois Bidan
LSU Master's Theses
The potential of pulsed vertical jet in cross-flow for film cooling purposes was experimentally studied and is discussed in this Thesis. A single vertical jet placed in laminar cross-flow conditions was first characterized in steady state at relatively low blowing ratios ranging from 0.150 to 0.600, using Mie scattering visualization methods and hot-wire measurements. Wavelet spectral analysis and image quantification algorithms were applied to the velocity records and averaged visualizations to obtain quantitative data on the jet characteristic frequencies, penetration and coverage. Two different regimes characterized by different structures are identified and adapted scaling variables are provided. Trends in the …
An Investigation Into Fuel Cells And Flow Cytometers Optimal Design, Etim Sunday Udoetok
An Investigation Into Fuel Cells And Flow Cytometers Optimal Design, Etim Sunday Udoetok
LSU Doctoral Dissertations
The aim of the fuel cells part of this project was to investigate the performance of Proton Exchange Membrane Fuel Cells and closely related fuel cell types like the Alkaline Fuel Cells and Phosphoric Acid Fuel Cells. The investigation involved understanding the performance of fuel cells, addressing the shortcomings of currently used designs, and finding new methods for improving the performance of fuel cells. CFD was used to study flow channels and information learned from the study was used to design a new and improved flow channel. A prototype of the new design was fabricated, tested and found to perform …
Numerical Simulations Of Flow And Mass Transport In Micro-Fluidic Components For Modular Bio-Analytic Chip Applications, Sudheer D. Rani
Numerical Simulations Of Flow And Mass Transport In Micro-Fluidic Components For Modular Bio-Analytic Chip Applications, Sudheer D. Rani
LSU Doctoral Dissertations
Microfluidics has received a great deal of attention in the past decade. The ability of modular microfluidic chips to miniaturize integrate chemical and biological systems (µTAS) can be greatly productive in terms of cost and efficiency. During the design of these modular devices, misalignment of materials, geometrical or both is one of the most common problems. These misalignments can have adverse effect in both pressure driven and electrokinetically driven flows. In the present work, Numerical Simulations have been performed to study the effect of material and geometrical mismatch on the flow behavior and species progression in microfluidic interconnects. In the …
Thermomechanical Interaction Analysis Of Bodies Subjected To Oscillatory Heat Source, Jun Wen
Thermomechanical Interaction Analysis Of Bodies Subjected To Oscillatory Heat Source, Jun Wen
LSU Doctoral Dissertations
Surface heating by application of a moving heat source is a common problem in most manufacturing processes as well as in many tribological applications. The existing literature on studies of moving heat source problems primarily concentrates on unidirectional moving heat sources. Yet, a more complete analysis requires understanding of thermal behavior of bodies in relative sliding contacts subjected to oscillatory heat sources and thermomechanical interaction. In this dissertation, two analytical models are developed for rapid evaluation of the transient temperature in solids undergoing oscillatory heat source. In the first model, an analytical technique is presented to treat oscillatory heat source …
Fabrication Of Micro Bumps For Micro Scale Thermal Management, Ajay Ashok Kardak
Fabrication Of Micro Bumps For Micro Scale Thermal Management, Ajay Ashok Kardak
LSU Master's Theses
Cryopreservation is storage of biological systems at ultra low temperatures for a prolonged duration; such that they can be thawed and restored to the same living state. It is important to understand the behavior of cells when they are subjected to subzero temperatures. Research in this area has shown the occurrence of two main biophysical events; cellular dehydration and intracellular ice formation. Current techniques for characterizing the dehydration in cells as part of a tissue are not adequate for studying intracellular ice formation in tissues. An integrated device consisting of an array of thermal sensors (microthermocouples) and actuators (microthermoelectric coolers) …
Magnetic Field Effects On Diffusion Flames, Diego F. Gonzalez
Magnetic Field Effects On Diffusion Flames, Diego F. Gonzalez
LSU Master's Theses
Magnetic field effects in combustion is an area of study that has previously been overlooked. The influence of magnetic fields on flames has only recently been explored and is of interest both from a scientific and a practical standpoint. This study provides theoretical, numerical and experimental evidence that combustion can be affected with the use of suitable magnetic fields. This thesis focuses on four different types of magnetic field: homogeneous, gradient, oscillating and pre-combustion. For the homogeneous field case, the Gibbs Free Energy method was used to determine the mole fraction of product species. It was found that homogeneous fields …
Flow Field And Heat Transfer Analyses Of Mechanical Seals, Zhaogao Luan
Flow Field And Heat Transfer Analyses Of Mechanical Seals, Zhaogao Luan
LSU Doctoral Dissertations
Mechanical seals are widely used in rotating equipment such as pumps, turbines and agitators to prevent leakage. One crucial factor for keeping seals reliable is the thermal behavior of the seal rings. The existing literature on thermal effects in seals primarily concentrates on the conduction of heat into the rings. Yet, a more complete analysis requires understanding of the flow field around the rings. In this dissertation, both the laminar and turbulent flows within the seal chamber are studied and their effects on the heat transfer in the seal rings are evaluated. Based on extensive sets of numerical simulations, heat …
Composite Sandwich Structure With Grid Stiffened Core, Venkata Dinesh Muthyala
Composite Sandwich Structure With Grid Stiffened Core, Venkata Dinesh Muthyala
LSU Master's Theses
Composite sandwich structures have been widely used in aerospace structures, ship building, infrastructure, etc. due to their light weight and high strength to weight ratio. Traditionally, light-weight core materials such as foam core, truss core, honeycomb core have been used in fabricating sandwich structures with limited success. In this study, a new composite sandwich structure with a hybrid core was proposed, fabricated, tested, and modeled. The hybrid core consists of a fiber reinforced polymer grid skeleton that is filled in by extremely light-weight syntactic foam in the bay areas. The new sandwich structure was manufactured using a new manufacturing process. …
Measurements And Computations Of The Flow In Full-Scale Sugar Evaporative-Crystallizers And In Lab-Scale Models, Luis Fernando Echeverri
Measurements And Computations Of The Flow In Full-Scale Sugar Evaporative-Crystallizers And In Lab-Scale Models, Luis Fernando Echeverri
LSU Doctoral Dissertations
The circulation of massecuite is a key factor in achieving efficient heat transfer and crystallization in sugar evaporative crystallizers, and should be as high as practically possible for recovery, quality, and capacity reasons. This research report presents results on the circulation obtained applying modern experimental and numerical techniques. The main goals are contributing to expand the understanding of the process in sugar crystallizers; developing realistic models for the simulation of the circulation; and studying the effect of different design parameters. The circulation of massecuite is driven by buoyancy force due to density difference between the vapor generated and the surrounding …
Development Of Micropump For Microfluidic Applications, Dong Eun Lee
Development Of Micropump For Microfluidic Applications, Dong Eun Lee
LSU Doctoral Dissertations
This dissertation covers the research work on two types of micropumps, one is based on magnetohydrodynamic (MHD) principle that utilizes Lorentz force for actuation, and the other is based on electrochemical actuation. The AC-type MHD micropump was designed and analyzed as a solution to the bubble formation problem encountered in DC-type MHD micropump. A UV-LIGA process using thick layer of SU-8 negative photoresist was successfully developed to microfabricate the AC MHD micropump. Preliminary studies and tests of the AC MHD micropumps demonstrate that bubble formation was significantly reduced to permit the proper function of the micropump. A continuous flow was …
Micro Injection Fuel/Air Premixer/Combustion, Jian Zhang
Micro Injection Fuel/Air Premixer/Combustion, Jian Zhang
LSU Doctoral Dissertations
Lean premixed (LP) combustion has become the dominant industrial approach to reduce NOx emissions. Homogeneous mixing of lean fuel and air mixtures prevents the presence of undesirable localized regions of near-stoichiometric fuel/air mixtures, thereby allowing a reduction in thermal NOx. A new concept, a multi-point micro injection premixer, is presented in this dissertation. The multi-point micro injection premixer is a porous plate that provides a simple but extremely effective method to mix air and fuel. An array of fuel jets is injected in a direction perpendicular to the plane of the premixer plate into an oncoming counterflow stream of air. …
Design, Fabricaton, And Testing Of A Compact Quasi-Isothermal Prox Reactor Using Micro Heat Exchangers, Curtis Maurice Hebert
Design, Fabricaton, And Testing Of A Compact Quasi-Isothermal Prox Reactor Using Micro Heat Exchangers, Curtis Maurice Hebert
LSU Master's Theses
A two stage PROX reactor with micro heat exchangers was designed, built, and tested to demonstrate the ability to control the temperature in the reactor and improve PROX performance in terms of CO conversion and selectivity. The gas stream was composed of 40% H2, 1% CO, 9% CO2, 0.5% O2, and 49.5% Ar. Metal foams were used to support a 5 wt% Pt/0.5 wt% Fe/γ-Al2O3 catalyst. Two sections of foam catalyst were used with heat exchangers positioned before and after each section. The resulting axial temperature profile of the gas stream …
Experimental Investigation Of Heat Transfer Rate In Micro-Channels, Pritish Ranjan Parida
Experimental Investigation Of Heat Transfer Rate In Micro-Channels, Pritish Ranjan Parida
LSU Master's Theses
Metal-based MHEs are of current interest due to the combination of high heat transfer performance and improved mechanical integrity. Efficient methods for fabrication and assembly of functional metal-based MHEs are essential to ensure the economic viability of such devices. The present study focuses on the results of heat transfer testing of assembled Cu- and Al- based microchannel heat exchanger (MHE) prototypes. Efficient fabrication of Cu- and Al- based high-aspect-ratio microscale structures (HARMS) have been achieved through molding replication using surface engineered, metallic mold inserts. Replicated metallic HARMS were assembled through eutectic bonding to form entirely Cu- and Al- based MHE …
Film Cooling From A Row Of Holes Supplemented With Anti Vortex Holes, Alok Dhungel
Film Cooling From A Row Of Holes Supplemented With Anti Vortex Holes, Alok Dhungel
LSU Master's Theses
Film cooling is a technique employed to protect the external surface of gas turbine blades from the hot mainstream gas by ejecting the internal coolant air through discrete holes or slots at several locations on the blade exterior surface. Passing the coolant through conventional cylindrical holes causes a pair of vortices to form which lifts off the coolant jet instead of letting it adhere to the surface. The present study aims at investigating the enhanced cooling performance caused by addition of anti-vortex holes to the main cylindrical film cooling holes. Both heat transfer coefficient and film cooling effectiveness are determined …
Fabrication Of Perforated Polymer Membranes Using Imprinting Technology, Anish Roychowdhury
Fabrication Of Perforated Polymer Membranes Using Imprinting Technology, Anish Roychowdhury
LSU Master's Theses
The goal of the present study was to fabricate perforated membrane structures in polymers with the pore diameter ranging from 10 ìm down to the sub ìm scale. The perforated membrane structure plays an important role in many biological systems. Thus the ability to reproduce such architecture will help with the study of biological systems by mimicking biological cell membrane-like structures and open new vistas in the study of transport behavior in cell biology and the separation of biological vesicles. Such structures also have potential uses as components in polymer optics and modular micro/nanofluidic devices. Use of polymer substrates is …
Manufacturing And Characterization Of High-Aspect-Ratio Diffusive Micro-Mixers, Vamsidhar Palaparthy
Manufacturing And Characterization Of High-Aspect-Ratio Diffusive Micro-Mixers, Vamsidhar Palaparthy
LSU Master's Theses
In the Ligase Detection Reaction (LDR) technique different chemical reagents of varying concentration are mixed with the by-products of the polymerase chain reaction (PCR) for the detection of low abundant cancer diagnostic markers [1]. An effective micro-mixer which is cheap, durable over a relatively broad range of flows with easy manufacturing is required in this process. This work is aimed at manufacturing mixers according to the required specifications with metrology at every manufacturing process to estimate the limits and tolerances during manufacturing and analyzing their efficiency both numerically and experimentally. An optimum mixer design developed earlier by Maha et.al [2] …
Reactive Multilayer Foils And Their Applications In Joining, Xiaotun Qiu
Reactive Multilayer Foils And Their Applications In Joining, Xiaotun Qiu
LSU Master's Theses
In this study, Ni/Al multilayer foils were fabricated by a cold rolling method. A two-stage reaction process was observed in the reaction-ignition experiment. The phase formation process in the cold rolled foils was studied. The first reaction stage with a slow reaction velocity was the lateral growth of Al3Ni phase at isolated nucleation sites and the subsequent coalescence into a continuous layer. The second reaction stage with a fast reaction velocity was the growth of the Al3Ni layers in the direction normal to the Ni/Al interface until all Al was consumed. Afterwards, Al3Ni reacted with the remaining Ni to form …
Study Of Demolding Process In Thermal Imprint Lithography Via Numerical Simulation And Experimental Approaches, Zhichao Song
Study Of Demolding Process In Thermal Imprint Lithography Via Numerical Simulation And Experimental Approaches, Zhichao Song
LSU Master's Theses
The objective of present study was to analyze the mechanical behavior of polymer resist during the demolding process, such as stress distribution and evolution; distortion and tilt of microstructures in thermal imprint lithography, a new emerging technique in mass production of micro/nanoscale patterns. One of the most challenging technical issues for thermal imprint lithography is the structural damages during demolding process. Thermal stress, adhesion force and friction force all play important roles in determination of the success of demolding and it is crucial to understand the underlying physics in order to optimize the structure and process design. In present study, …
Transcendental Eigenvalue Problems Associated With Vibration, Buckling And Control, Jayaram Subramanian
Transcendental Eigenvalue Problems Associated With Vibration, Buckling And Control, Jayaram Subramanian
LSU Master's Theses
The static and dynamic analysis of structures requires us to obtain solutions of their espective governing differential equations subject to appropriate boundary conditions. The dynamic analysis of non-uniform continuous structures is of primary interest, as most traditional methods take the help of discrete models to analyze them. Well established discrete model methods lead to an algebraic eigenvalue problem, the characteristic equation associated with which is a polynomial. The spectral characteristics of a continuous system nevertheless are represented by transcendental functions and cannot be approximated by polynomials efficiently. Hence finite dimensional discrete models are not capable of predicting the response of …
On The Stress Analysis Of Bimetallic Packing Rings, Eric Richard Lewis
On The Stress Analysis Of Bimetallic Packing Rings, Eric Richard Lewis
LSU Master's Theses
The purpose of this research is to try and understand hypercompressor packing ring failures better with a view of ultimately reducing or even eliminating their occurrences. In order to gain further understanding of packing ring failures, we seek to obtain an appreciation of the stresses they experience during operation. First we consider a conventional simulation of an axisymmetric packing ring and cup subjected to the typical pressure loading conditions experienced by these components when installed in a hypercompressor cylinder. The key locations of interest are along the bimaterial interface, and in particular at the ends of the interface. These ends …
Manufacturing, Testing And Modeling Of Advanced Filament Wound Grid Stiffened Composite Cylinders, Ravi Chaitanya Velamarthy
Manufacturing, Testing And Modeling Of Advanced Filament Wound Grid Stiffened Composite Cylinders, Ravi Chaitanya Velamarthy
LSU Master's Theses
Advanced Grid Stiffened (AGS) structures are a kind of FRP composites that are being extensively used in many engineering fields because of their inherent advantages. Hence it is of utmost importance to understand the basic mechanism of these structures in order to develop better models and to find ways to improve their efficiency. This thesis discusses the manufacturing technology used viz. the filament winding technique to fabricate grid stiffened composite cylinders. A step by step procedure of the fabrication process of grid cylinders is explained. The confinement effectiveness of the AGS cylinders is evaluated by filling them with concrete and …
Granular Contact Lubrication: Theory And Experiment, Karim El Kholy
Granular Contact Lubrication: Theory And Experiment, Karim El Kholy
LSU Doctoral Dissertations
This dissertation is devoted to a theoretical and experimental study of the granular contact lubrication, both. The theory is based on the kinetic of the granular material where the granules interact with each other and with the boundary surfaces through instantaneous, binary collisions, characterized by a constant coefficient of restitution. Specifically this study focuses on granular lubrication in Couette flows. A series of simulations is reported and the results show good agreement with several published papers. Also, a theory that ties the true temperature to the grain mobility is developed. The true temperature of a granular material depends on the …