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LSU Master's Theses

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Articles 151 - 180 of 255

Full-Text Articles in Mechanical Engineering

Manufacturing And Characterization Of High-Aspect-Ratio Diffusive Micro-Mixers, Vamsidhar Palaparthy Jan 2007

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 Jan 2007

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 Jan 2007

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 Jan 2007

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 Jan 2007

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 Jan 2007

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 …


Studies On The Heat/Mass Transfer Characteristics And Fluid Structure In A Square Internal Cooling Channel With Dimpled Surfaces, Fuguo Zhou Jan 2007

Studies On The Heat/Mass Transfer Characteristics And Fluid Structure In A Square Internal Cooling Channel With Dimpled Surfaces, Fuguo Zhou

LSU Master's Theses

Experimental and numerical studies of heat/mass transfer on the dimpled surfaces in square channels are performed. The naphthalene sublimation method is employed in the experimental study. First, in a two-passage rotating channel, circle dimple matrices are cast on the leading and trailing walls in both the inlet and outlet of the serpentine channel. The experiments are carried out with Reynolds number of 7,000 and 21,000, and with Rotation number of 0 and 0.2. The dimpled walls lead to heat/mass transfer enhancements over smooth surfaces both in the stationary case and in the rotating case. In the stationary case, the dimple …


Passive Alignment Of Micro-Fluidic Chips Using The Principle Of Elastic Averaging, Sitanshu Gurung Jan 2007

Passive Alignment Of Micro-Fluidic Chips Using The Principle Of Elastic Averaging, Sitanshu Gurung

LSU Master's Theses

This thesis presents a novel design for a passive alignment feature for vertically stacking chips in a micro fluidic device. Each chip is the size of a standard microscopic slide (75mm—25mm) and is a highly specialized functional unit designed and fabricated to process fluidic samples. The fluidic samples in the device flows from one chip to another using inter connecting holes 500μm-100μm in diameter. Hence an alignment of better than 100μm between chips is necessary to allow for the interconnecting holes to overlap so as to provide with a path for the fluid to flow. The feature to be used …


Measuring Skeletal Kinematics With Accelerometers On The Skin Surface, Kevin Curtis Ayer Jan 2007

Measuring Skeletal Kinematics With Accelerometers On The Skin Surface, Kevin Curtis Ayer

LSU Master's Theses

The most common motion analysis method uses cameras to track the position of markers on bodily surfaces over time. Although each species has a common skeletal frame to reference recorded motions, the soft tissue covering each is not rigid. Markers, therefore, experience motion relative to the bone and do not accurately portray underlying bone activity. This limits clinical use of motion studies and the understanding of joint motion. Use of MEMS accelerometers for removing soft tissue artifact, motion relative to the bone, from surface measurements and determining the position of the underlying bone was investigated. An animal limb was modeled …


Jet Impingement Cooling Configurations For Gas Turbine Combustion, Eric Ian Esposito Jan 2006

Jet Impingement Cooling Configurations For Gas Turbine Combustion, Eric Ian Esposito

LSU Master's Theses

Impinging jets are commonly used to enhance heat transfer in modern gas turbine engines. Impinging jets used in turbine blade cooling typically operate at lower Reynolds numbers in the range of 10,000 to 20,000. In combustor liner cooling, the Reynolds numbers of the jets can be as high as 60,000. The present study is aimed at experimentally testing two different styles of jet impingement geometries to be used in backside combustor cooling. The higher jet Reynolds numbers lead to increased overall heat transfer characteristics, but also an increase in crossflow caused from spent air. The crossflow air has the effect …


Numerical Solution Of Flow Resistance In Outflow Pathway And Intravitreal Drug Delivery In Vitrectomised Eyes, Jyoti Gururaj Kathawate Jan 2006

Numerical Solution Of Flow Resistance In Outflow Pathway And Intravitreal Drug Delivery In Vitrectomised Eyes, Jyoti Gururaj Kathawate

LSU Master's Theses

In this study, numerical computations of the ocular fluid dynamics in a human eye are presented with a perspective of understanding the mechanisms of increased flow resistance. In the present study, the TM is represented as a multilayered-graded porous structure with specific pore size and void fraction. The flow patterns and pressure distribution in anterior chamber are analyzed to delineate key flow mechanism; the shear stresses on the lens, iris and IW of SC are also examined to locate the maximum values. Inside the human eye, the largest pressure drop occurs across JCT and IW of SC. The highest pressure …


Pulsed Vertical Jet In Cross Flow At Mean Blowing Ratios 0.35 And 0.45, Pierre-Emmanuel Jacques Joseph Bouladoux Jan 2006

Pulsed Vertical Jet In Cross Flow At Mean Blowing Ratios 0.35 And 0.45, Pierre-Emmanuel Jacques Joseph Bouladoux

LSU Master's Theses

This thesis deals with a pulsed vertical jet transverse to a cross flow (U=1.6m/s) at mean blowing ratios 0.35 and 0.45. First the reasons of this study are explained and the previous work in the field is described. Then the experimental setup, the experimental procedures and the data processing are detailed. The system (wind tunnel and jet) is characterized before studying the Jet in Cross Flow (JICF). The JICF is explored under unforced and forced conditions through LASER sheet visualizations and constant temperature anemometry (CTA) measurements using hot-wire sensors. Blowing ratios ranging from 0.150 to 0.600 are studied …


Two-Phase Flow In High Aspect Ratio, Polymer Microchannels For Reagent Delivery Applications, Estelle Evans Jan 2006

Two-Phase Flow In High Aspect Ratio, Polymer Microchannels For Reagent Delivery Applications, Estelle Evans

LSU Master's Theses

Multiphase flow in microfluidics is an increasingly growing field, especially in biotechnology. For instance, a steady-state slug flow would benefit lab-on-a-chip drug delivery methods. This flow would not only use minute amounts of reagents, but it would also decrease the sample processing time. Thus, researching a steady-state plug flow in a microchannel is beneficial to the drug delivery field. Five PMMA, directly-milled microchannels [2: Aspect Ratio 1 (with and without pressure ports, 2): Aspect ratio 2 (with and without pressure ports), and 1: Aspect Ratio 3 (without pressure ports)] were manufactured. These channels were then cleaned, and a PMMA cover …


Simulations Of A Modified Micro-Scale Electrophoretron, Nada Elmajdoub Jan 2006

Simulations Of A Modified Micro-Scale Electrophoretron, Nada Elmajdoub

LSU Master's Theses

This paper presents theoretical analysis and numerical simulations of a modified micro-scale electrophoretron adapted for cycling reaction applications (PCR, LDR...). The electrophoretron consists of a closed-loop microchannel. If one part of the length of the channel has an electroosmotic mobility of an opposite sign than the remaining part, a continuous cyclic motion of the fluid can be sustained if a potential difference is applied on two electrodes strategically placed along the channel. Conservation of mass leads to the formation of a pressure gradient and a related hydrodynamic flow. Under appropriate combination of design parameters, the combined Electroosmotic -hydrodynamic flow contributes …


Modeling Fabrication And Characterization Of A Bio-Micro Thermoelectric Device For Highly Localized Temperature Control, Aparna Prabhakar Jan 2006

Modeling Fabrication And Characterization Of A Bio-Micro Thermoelectric Device For Highly Localized Temperature Control, Aparna Prabhakar

LSU Master's Theses

There is an ever expanding interaction between the fields of micro-electromechanical systems (MEMS) and biology to develop devices to monitor, control and act on living systems. Particularly in the field of cryobiology, there is a need to monitor and control temperature at the cellular level. An important step towards achieving this aim is to fabricate an array of microscale thermoelectric actuators. As a first step for towards achieving such localized control of temperatures in cells and tissues, an array of individually addressable micro-thermoelectric coolers (µTECs) were modeled, characterized, and fabricated. Prefabrication experimentation and modeling were carried out to understand the …


Modeling Of Fiber Reinforced Polymer Confined Concrete Cylinders, Indrani V. Volety Jan 2006

Modeling Of Fiber Reinforced Polymer Confined Concrete Cylinders, Indrani V. Volety

LSU Master's Theses

Fiber Reinforced Polymer (FRP) confined concrete columns have been developed for new construction and rebuilding of concrete piers/piles in engineering structures. Design of these FRP confined concrete columns requires an accurate estimate of the performance enhancement due to the confinement mechanism. Therefore, the key is to develop a confinement model, a model that relates the confined concrete strength with the unconfined concrete strength and the confining pressure provided by the FRP. Due to its closed-form expression and ease of application, design-oriented confinement models predominate in designing FRP confined concrete columns. Design oriented models are directly based on the interpretation of …


Molecular Dynamics Simulation Study Of Grain Boundary Migration In Nanocrystalline Pd, Shengyu Wang Jan 2006

Molecular Dynamics Simulation Study Of Grain Boundary Migration In Nanocrystalline Pd, Shengyu Wang

LSU Master's Theses

We present a new methodology for measuring the grain boundary mobility for curved boundaries using molecular-dynamics simulation of grain growth in a small, specifically tailored Pd nanocrystalline structure. In the model system, the boundaries move under the forces provided by their curvature and in the presence of the triple junctions. As a consequence of grain boundary migration the boundary area per unit volume is reduced and the mean grain size of grains increases with time. Our investigation shows that at elevated temperatures the activation energy for grain growth in this specifically tailored microstructure is very close to that of grain …


A New Method To Determine Radiative Properties Of Rough Solid Surfaces, Raghu Nandan Mutukulla Jan 2006

A New Method To Determine Radiative Properties Of Rough Solid Surfaces, Raghu Nandan Mutukulla

LSU Master's Theses

The radiative properties of the rough surfaces are important both from fundamental and practical standpoint. Thus, there is a need to determine the effect of roughness on radiative properties of materials accurately, as these properties effect the performance of electronic devices, communication devices, optical sensors, and furnaces, amongst others. The effects of roughness are assessed by measuring the reflection coefficients from the carbon rod surfaces and steel 1086 samples over the range of angles 25 to 75 in the visible range and near infrared region. Different levels of roughness are induced on the surfaces by utilizing different grid size sand-paper …


Heat Transfer And Flow Characteristics Inside A Gas Turbine Combustor, Yap-Sheng Goh Jan 2006

Heat Transfer And Flow Characteristics Inside A Gas Turbine Combustor, Yap-Sheng Goh

LSU Master's Theses

Heat transfer and flow characteristics inside a typical can-annulus gas turbine combustor are investigated. This is the first study in a public domain to focus on the convective heat loads to combustor liner due to swirling flow generated by swirler nozzles. The objectives of this study are to physically design an experimental combustor test model, to perform local accurate heat transfer and flow measurements, and to better understand the fundamental thermo-fluid dynamic effects inside a combustor equipped with a swirler nozzle provided by Solar Turbines Inc. The local temperature and heat transfer distribution were determined to locate the heat transfer …


Thermal Management Of Micro Gas Chromatographs, Chetan Ramesh Jan 2006

Thermal Management Of Micro Gas Chromatographs, Chetan Ramesh

LSU Master's Theses

Gas chromatography is an analytical technique for separating and analyzing individual components in a gas mixture. Applications of gas chromatographs (GCs) include chemical analysis, environmental maintenance, green house gases monitoring, and forensic analysis when used in conjunction with mass spectrometry. There has been a tremendous interest in miniaturization of gas chromatograph systems because of significantly reduced size, portability, fast response times, low power consumption and low cost. Isothermal analysis is a chromatographic analysis at one column temperature. In temperature programming, a linear increase of column temperature with time is used during the course of the analysis. Temperature programming facilitates separation …


Experimental Analysis Of Mechanical Seal Design With Enhanced Thermal Performance, Ainsworth Gidden Jan 2006

Experimental Analysis Of Mechanical Seal Design With Enhanced Thermal Performance, Ainsworth Gidden

LSU Master's Theses

For industries that use pumps and mixers in their process operations, it is of paramount importance to control the leakage from these equipments. The leakage presents safety hazards and economic loss. It is widely believed that the majority of downtime associated with a pump or a mixer is the result of a mechanical seal failure. Therefore, it is important for these industries to have a mechanical seal that is a reliable performer and enables a longer operational life than what exist in the market at present. The aim of this research was to design and test a mating ring with …


A Thermodynamic Model For Wear In Sliding Contact, Susheel Brahmeshwarkar Jan 2006

A Thermodynamic Model For Wear In Sliding Contact, Susheel Brahmeshwarkar

LSU Master's Theses

Consideration of wear, an irreversible phenomenon, is a very important criterion in design. The knowledge of wear and its behavior enables one to make major considerations to conceptualize and design efficient machinery components with enhanced performance and reliability. The present work deals with the introduction of a novel approach of correlating wear with the thermodynamic properties of the system. The approach involves relating wear to thermodynamic entropy flow in the system using the laws of thermodynamics. This relation is verified experimentally and theoretically by considering a sliding contact in a disk-on-disk configuration for two sets of contacting materials namely Bronze …


Mesoscale Simulation Of Grain Boundary Diffusion Creep In The Presence Of Grain Growth, Lucian Zigoneanu Jan 2006

Mesoscale Simulation Of Grain Boundary Diffusion Creep In The Presence Of Grain Growth, Lucian Zigoneanu

LSU Master's Theses

Grain-boundary (GB) diffusion creep (Coble creep) is the dominant deformation mechanism for the fine-grained materials under low stress and at elevated temperature. During creep deformation the grains become elongated in the tensile direction because of atoms diffusion along GBs from places in compression to those in tension. Consequently, the GB diffusion rate depends on the normal stress gradient along the boundaries. It is widely accepted that the GB migration generally plays two important roles during Coble creep: one leading to the decrease of the creep rate due to the increase of the grain size by GB migration mediated grain growth …


Mesoscale Predictions For The Dynamic Compaction Of Explosively-Coated Aluminum Micro-Particles, Michael Wayne Crochet Jan 2006

Mesoscale Predictions For The Dynamic Compaction Of Explosively-Coated Aluminum Micro-Particles, Michael Wayne Crochet

LSU Master's Theses

Conventional granular explosives are widely used in aerospace and defense-related industries. Powdered metals are often mixed with high explosives to enhance detonation. The effectiveness of these mixtures is limited by the slow burning of the metal relative to the explosive and their sensitivity to mechanical loading. Granular energetic composites, composed of an aluminum core coated with a layer of the high explosive RDX (C3H6N6O6), may be a high-performance alternative to conventional explosives because of a higher metal combustion rate and lower impact sensitivity. Though the technology required to manufacture granular energetic composites …


Accelerating Micro-Scale Pcr (Polymerase Chain Reactor) For Modular Lab-On-A-Chip System, Pin-Chuan Chen Jan 2006

Accelerating Micro-Scale Pcr (Polymerase Chain Reactor) For Modular Lab-On-A-Chip System, Pin-Chuan Chen

LSU Master's Theses

The polymerase chain reaction (PCR) is a powerful technique used to exponentially amplify specific DNA sequences of interest through repetitive temperature cycling. The temperatures used in PCR are typically 90°C - 94°C for denaturation, 50°C - 70°C for renaturation, and 70°C - 75°C for extension. The double-stranded helix of nucleotides, carrying the genetic information, is separated during denaturation, reacts with chemical primers during renaturation, and becomes a complete, replica, double-stranded DNA helix structure during extension. The primary drawback of current commercial benchtop PCR machine is its cycle time due to its large thermal capacitance, and micro PCR is under developing …


Study Of Particle Growth And Breakdown In Single Size Gamma Prime Distribution And High Temperature Creep In In738lc Nickel Superalloy, Arvind Kumar Dwarapureddy Jan 2006

Study Of Particle Growth And Breakdown In Single Size Gamma Prime Distribution And High Temperature Creep In In738lc Nickel Superalloy, Arvind Kumar Dwarapureddy

LSU Master's Theses

IN738LC, a nickel based superalloy has wide applications in the gas turbine engines because of its ability to retain its strength at high temperatures involved. The stability of the γ' Ni3Al (Ti, Nb) precipitate microstructure which gives the alloy its strength is very important. After an initial annealing at 1200°C for 4 hours and water quenching, a uniform distribution of single size (70nm) γ' fine precipitates is obtained. Growth of the γ' particles, their size and distribution are studied after subsequent annealing heat treatments, conducted at different temperatures for different time periods. The average precipitate size data of …


Effect Of Bulk Flow Modulations On A Normal Jet In Crossflow At A Mean Blowing Ratio Of 0.25, Jeremiah Oertling Jan 2006

Effect Of Bulk Flow Modulations On A Normal Jet In Crossflow At A Mean Blowing Ratio Of 0.25, Jeremiah Oertling

LSU Master's Theses

An experimental wind tunnel has been designed, built, outfitted with automated hot wire anemometry and laser sheet imagery systems methods of instrumentation and tested with the purpose of performing scientific research on the control and stabilization of a jet issuing 90 degrees into a crossflow. After the design and system characterizations were performed, the system was employed as a experimental platform to conduct an investigation of bulk flow modulation of a jet in crossflow. The Mean Blowing ratio investigated was set at 0.25, and the effect of duty cycle, peak to peak blowing ratio and frequency of excitation are investigated. …


Characterization And Tribological Behavior Of Diamond-Like Carbon And Nitrogen-Doped Diamond-Like Carbon Thin Films, Krishna Chaitanya Kadiyala Jan 2006

Characterization And Tribological Behavior Of Diamond-Like Carbon And Nitrogen-Doped Diamond-Like Carbon Thin Films, Krishna Chaitanya Kadiyala

LSU Master's Theses

Diamond-like carbon (DLC) films have been extensively studied for more than two decades due to their highly attractive properties. These films exhibit unique mechanical, electrical and tribological behavior and thus, possess great potential for applications in tribology. However, the high level of internal stress developed and low thermal stability are the main drawbacks. Synthesis of nitrogen-doped DLC (N-DLC) offers the possibility of overcoming these drawbacks. In the present study, DLC and N-DLC films (with low N content) were deposited on Si substrates using a hybrid plasma-assisted CVD/PVD process. Film characterization in terms of microstructure, composition and chemical state of components …


Modeling And Fabrication Of A Microthermocouple Array, Adam Cygan Jan 2006

Modeling And Fabrication Of A Microthermocouple Array, Adam Cygan

LSU Master's Theses

Cryobiology is the study of how living cells and tissues respond to freezing and exposure to subzero temperatures. Studies in this field are aimed toward improving methods of cryosurgery as well as the storage of cells and tissues. For example, one area of research is to link the biophysical cellular dehydration and intracellular ice formation in cells during tissue freezing to cell viability and mechanical properties after thawing. There is currently a method for measuring dehydration in cells as part of a tissue, but not an adequate method for measuring intracellular ice formation in tissues. A prototype device that would …


Heat/Mass Transfer In Rotating, Smooth, High Aspect-Ratio (4:1) Coolant Channels With Curved Walls, Eashwar Sethuraman Jan 2006

Heat/Mass Transfer In Rotating, Smooth, High Aspect-Ratio (4:1) Coolant Channels With Curved Walls, Eashwar Sethuraman

LSU Master's Theses

The thesis presents an experimental study of heat/mass transfer coefficient in 4:1 aspect ratio smooth channels with non-uniform cross-sections. Curved leading and trailing edges are studied, for two curvatures of 9.06 m-1 (0.23 in-1) and 15.11 m-1 (0.384 in-1) and for two different curvature configurations. One configuration has curved walls with curvature corresponding to the blade profile (positive curvature on both leading and trailing walls), and the other configuration has leading and trailing walls that curve inwards into the coolant passage (negative curvature on the leading surface and positive curvature on the trailing surface). The experiments are conducted in a …