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Electronic Theses and Dissertations

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Full-Text Articles in Mechanical Engineering

Design Optimization Of Solid Rocket Motor Grains For Internal Ballistic Performance, Roger Hainline Jan 2006

Design Optimization Of Solid Rocket Motor Grains For Internal Ballistic Performance, Roger Hainline

Electronic Theses and Dissertations

The work presented in this thesis deals with the application of optimization tools to the design of solid rocket motor grains per internal ballistic requirements. Research concentrated on the development of an optimization strategy capable of efficiently and consistently optimizing virtually an unlimited range of radial burning solid rocket motor grain geometries. Optimization tools were applied to the design process of solid rocket motor grains through an optimization framework developed to interface optimization tools with the solid rocket motor design system. This was done within a programming architecture common to the grain design system, AML. This commonality in conjunction with …


Driver-Gas Tailoring For Test-Time Extension Using Unconventional Driver Mixtures, Anthony Amadio Jan 2006

Driver-Gas Tailoring For Test-Time Extension Using Unconventional Driver Mixtures, Anthony Amadio

Electronic Theses and Dissertations

To study combustion chemistry at low temperatures in a shock tube, it is of great importance to increase experimental test times, and this can be done by tailoring the interface between the driver and driven gases. Using unconventional driver-gas tailoring with the assistance of tailoring curves, shock-tube test times were increased from 1 to 15 ms for reflected-shock temperatures below 1000 K. Provided in this thesis is the introduction of tailoring curves, produced from a 1-D perfect gas model for a wide range of driver gases and the production and demonstration of successful driver mixtures containing helium combined with either …


Study Of Low Speed Transitional Regime Gas Flows In Microchannels Using Information Preservation (Ip) Method, Umit Kursun Jan 2006

Study Of Low Speed Transitional Regime Gas Flows In Microchannels Using Information Preservation (Ip) Method, Umit Kursun

Electronic Theses and Dissertations

Proper design of thermal management solutions for future nano-scale electronics or photonics will require knowledge of flow and transport through micron-scale ducts. As in the macro-scale conventional counterparts, such micron-scale flow systems would require robust simulation tools for early-stage design iterations. It can be envisioned that an ideal Nanoscale thermal management (NSTM) solution will involve two-phase flow, liquid flow and gas flow. This study focuses on numerical simulation gas flow in microchannels as a fundamental thermal management technique in any future NSTM solution. A wellknown particle-based method, Direct Simulation Monte Carlo (DSMC) is selected as the simulation tool. Unlike continuum …


Rapid Prototyping Of Microfluidic Packages, Michael Pepper Jan 2006

Rapid Prototyping Of Microfluidic Packages, Michael Pepper

Electronic Theses and Dissertations

In the area of MEMS there exists a tremendous need for communication between the micro-device and the macro world. A standard protocol or at least multiple standards would be of great use. Electrical connections have been standardized for many uses and configurations by the integrated circuit industry. Standardization in the IC industry has created a marketplace for digital devices unprecedented. In addition to the number of "off the shelf" products available, there exists the possibility for consumers to mix and match many devices from many different manufacturers. This research proposes some similar solutions as those for integrated circuits for fluid …


Study Of Heat Transfer Characteristics Of Impinging Air Jet Using Pressure Andn Temperature Sensitive Luminescent Paint, Quan Liu Jan 2006

Study Of Heat Transfer Characteristics Of Impinging Air Jet Using Pressure Andn Temperature Sensitive Luminescent Paint, Quan Liu

Electronic Theses and Dissertations

Luminescent coating measurement system is a relatively new technology for quantitative pressure and temperature measurement. Usually referred to as Pressure Sensitive Paint (PSP) and Temperature Sensitive Paint (TSP), luminescent coatings contain sensor molecules, which undergoes a luminescent transition when excited with light of proper wavelength. The reaction is pressure and/or temperature sensitive. The image of TSP or PSP coated model surface can be captured with a scientific grade camera and then processed to obtain full field temperature and pressure distribution with very high fidelity. The preparation time of the technique is short. The measurement system offers an economic alternative to …


Preliminary Study On The Impact Of Impingement On The Effectiveness Of Film Cooling In The Presence Of Gas Path Pressure Gradient, Anil Peravali Jan 2006

Preliminary Study On The Impact Of Impingement On The Effectiveness Of Film Cooling In The Presence Of Gas Path Pressure Gradient, Anil Peravali

Electronic Theses and Dissertations

Impingement is the most commonly used method of cooling in the hot stages of gas turbines. This is often combined with film cooling to further increase the cooling performance. The mainstream flow where in the coolant films discharge often has large stream wise pressure variations. All existing studies on coupled film and impingement cooling concentrated on the effect of the film depletion on the impingement heat transfer. This study investigates the impact of impingement on film cooling, where the jets impinging on a flat plate are depleted through arrays of film cooling holes in the presence of pressure gradient in …


A Fluid Structure Interaction Model Of Intracoronary Atherosclerotic Plaque Rupture, Eric Teuma-Melago Jan 2006

A Fluid Structure Interaction Model Of Intracoronary Atherosclerotic Plaque Rupture, Eric Teuma-Melago

Electronic Theses and Dissertations

Plaque rupture with superimposed thrombosis is the primary cause of acute coronary syndromes of unstable angina, myocardial infarction and sudden death. Although intensive studies in the past decade have shed light on the mechanism that causes unstable atheroma, none has directly addressed the clinical observation that most myocardial infarction (MI) patients have moderate stenoses (less than 50%). Considering the important role the arterial wall compliance and pulsitile blood flow play in atheroma rupture, fluid-structure interaction (FSI) phenomenon has been of interest in recent studies. In this thesis, the impact is investigated numerically of coupled blood flow and structural dynamics on …


Experiments In Pool Boiling Heat Transfer And Nucleationdynamics Of High Pressure Refrigerants, Daniel Joo Jan 2006

Experiments In Pool Boiling Heat Transfer And Nucleationdynamics Of High Pressure Refrigerants, Daniel Joo

Electronic Theses and Dissertations

A high pressure pool boiling experiment of pressurized R134a is designed and built, utilizing thermochromatic liquid crystal techniques. Liquid crystals thermo-chromatography uses encapsulated liquid crystals that are sensitive to temperature. When exposed to hot temperatures the crystal reflect a blue/violet color, and when exposed to cooler temperatures it reflects a red/orange color. The color value or hue is proportional to its temperature. Using this technique this experiment is capable of studying the physics and thermodynamics of refrigerants under nucleate pool boiling. The main objective of this experiment was the design of the experimental setup. Various designs were tested and validated, …


Design And Performance Evaluation Of An Integrated Miniature Single Stage Centrifugal Compressor And Permanent Magnet Synchronous Motor, Dipjyoti Acharya Jan 2006

Design And Performance Evaluation Of An Integrated Miniature Single Stage Centrifugal Compressor And Permanent Magnet Synchronous Motor, Dipjyoti Acharya

Electronic Theses and Dissertations

An attempt has been made in this present work to design, fabricate and performance evaluate an integrated single stage centrifugal compressor and permanent magnet synchronous motor which is a key component of the reverse brayton cycle cryocooler. An off the shelf compressor – the driven and electric motor – the driver was not available commercially to suffice the requirements of the reverse brayton cryocooler. The integrated compressor-motor system was designed and tested with air as the working fluid at mass flow rate of 7.3 grams per sec, with a compression ratio of 1.58 and driven by a 2 KW permanent …


Commissioning Of A Dynamic Mechanical Analyzerfor The Characterization Of Low Temperature Nitife Shape Memory Alloys, Maruthi Diwakar Nandiraju Jan 2006

Commissioning Of A Dynamic Mechanical Analyzerfor The Characterization Of Low Temperature Nitife Shape Memory Alloys, Maruthi Diwakar Nandiraju

Electronic Theses and Dissertations

NiTiFe shape memory alloys can undergo transformations between cubic, trigonal and monoclinic phases at low temperatures. The low hysteresis associated with the trigonal R-phase transformation make them candidates for actuator applications at low temperatures. However, the literature available on these alloys is limited and there is a need to establish processing structure-property correlations. This study was undertaken with the objective of determining and understanding such correlations in a Ni46.8Ti50Fe3.2 alloy. First, a dynamic mechanical analyzer (DMA) was successfully commissioned to facilitate mechanical testing between -150 and 600ºC. The experiments performed over selected ranges of stress and temperature probed a range …


Lattice Vibration Study Of Silica Nanoparticle In Suspension, Parveen Sachdeva Jan 2006

Lattice Vibration Study Of Silica Nanoparticle In Suspension, Parveen Sachdeva

Electronic Theses and Dissertations

In recent years considerable research has been done in the area of "nanofluids". Nanofluids are colloidal suspensions of nanometer size metallic or oxide particles in a base fluid such as water, ethylene glycol. Nanofluids show enhanced heat transfer characteristics compared to the base fluid. The thermal transport properties of nanofluids depend on various parameters e.g. interfacial resistance, Brownian motion of particles, liquid layering at the solid-liquid interface and clustering of nanoparticles. In this work atomic scale simulation has been used to study possible mechanisms affecting the heat transfer characteristics of nanofluids. Molecular dynamics simulation for a single silica nanoparticle surrounded …


Oscillatory Flow As A Means Of Enhanced Species Separation: A Three Dimensional Time-Accurate Cfd Analysis, Jennifer Crain Jan 2006

Oscillatory Flow As A Means Of Enhanced Species Separation: A Three Dimensional Time-Accurate Cfd Analysis, Jennifer Crain

Electronic Theses and Dissertations

A fluid that contains species in the presence of a concentration gradient generates unusual phenomena when it is forced into pulsatile motion. For example, each species in the fluid has an enhanced mass transport due to pure molecular diffusion. This enhancement takes place even if there is no net total flow over a cycle of the pulsatile motion. When more than one species in dilute amounts is present in an otherwise pure fluid, called a carrier, each species is transported at a different rate thereby causing a partial separation of the species. This idea traces back to hyperventilation studies done …


System Identification And Fault Detection Of Complex Systems, Dapeng Luo Jan 2006

System Identification And Fault Detection Of Complex Systems, Dapeng Luo

Electronic Theses and Dissertations

The proposed research is devoted to devising system identification and fault detection approaches and algorithms for a system characterized by nonlinear dynamics. Mathematical models of dynamical systems and fault models are built based on observed data from systems. In particular, we will focus on statistical subspace instrumental variable methods which allow the consideration of an appealing mathematical model in many control applications consisting of a nonlinear feedback system with nonlinearities at both inputs and outputs. Different solutions within the proposed framework are presented to solve the system identification and fault detection problems. Specifically, Augmented Subspace Instrumental Variable Identification (ASIVID) approaches …


Design And Development Of A Mems-Based Capacitive Bending Strain Sensor And A Biocompatible Housing For A Telemetric Strain Monitoring System., Julia Marie Weyer Aebersold 1969- May 2005

Design And Development Of A Mems-Based Capacitive Bending Strain Sensor And A Biocompatible Housing For A Telemetric Strain Monitoring System., Julia Marie Weyer Aebersold 1969-

Electronic Theses and Dissertations

Lumbar arthrodesis or spinal fusion is usually performed to relieve back pain and regain functionality from ruptured discs, disc degenerative disease, trauma and scoliosis. Metal rods are often fixed to the spine with screws or hooks, while fusion develops on the affected vertebrae. Fusion is determined by visual examination of radiographic images (X-ray), computed tomography (CT) scans or magnetic resonance imaging (MRI), yet these inspection procedures are subjective methods of review. They do not objectively confirm the presence of spinal fusion, which can lead to exploratory surgery to determine if fusion has occurred. Therefore, a need has arisen to develop …


An Optimized Kinetics Model For Oh Chemiluminescence At High Temperatures And Atmospheric Pressures, Joel Hall Jan 2005

An Optimized Kinetics Model For Oh Chemiluminescence At High Temperatures And Atmospheric Pressures, Joel Hall

Electronic Theses and Dissertations

Chemiluminescence from the OH(A-X) transition near 307 nm is a commonly used diagnostic in combustion applications such as flame chemistry, shock-tube experiments, and reacting-flow visualization. Measurements of the chemiluminescent intensity provide a simple, cost-effective, non-intrusive look at the combustion environment. The presence of the ultra-violet emission is often used as an indicator of the flame zone in practical combustion systems, and its intensity may be correlated to the temperature distribution or other parameters of interest. While absolute measurements of the ground-state OH(X) concentrations are well-defined, there is no elementary relation between emission from the electronically excited state (OH*) and its …


Alternative Foam Treatments For The Space Shuttle's External Tank, Kirsten Dreggors Jan 2005

Alternative Foam Treatments For The Space Shuttle's External Tank, Kirsten Dreggors

Electronic Theses and Dissertations

The Space Shuttle Columbia accident and the recent excitement surrounding Discovery's return to space brought excessive media attention to the foam products used on the External Tank (ET). In both cases, videos showed chunks of foam or ablative material falling away from the ET during lift off. This led to several years of investigation and research into the exact cause of the accident and potential solutions to avoid the problem in the future. Several design changes were made prior to the return to flight this year, but the ET still shed foam during lift off. Since the Columbia accident, the …


Investigations On Rf Sputter Deposited Sicn Thin Films For Mems Applications, Ravi Todi Jan 2005

Investigations On Rf Sputter Deposited Sicn Thin Films For Mems Applications, Ravi Todi

Electronic Theses and Dissertations

With the rapid increase in miniaturization of mechanical components, the need for a hard, protective coatings is of great importance. In this study we investigate some of the mechanical, chemical and physical properties of the SiCN thin films. Thin films of amorphous silicon carbide nitride (a-SiCxNy) were deposited in a RF magnetron sputtering system using a powder pressed SiC target. Films with various compositions were deposited on to silicon substrate by changing the N2/Ar gas ratios during sputtering. Nano-indentation studies were performed to investigate the mechanical properties such as hardness and reduced modulus of the SiCN films. Surface morphology of …


Mechanical Properties Of The Intervertebral Disc As An Estimator Of Postmortem Interval, Jennifer Noelle Jackson Jan 2005

Mechanical Properties Of The Intervertebral Disc As An Estimator Of Postmortem Interval, Jennifer Noelle Jackson

Electronic Theses and Dissertations

Currently, forensic scientists are only able to determine time since death (or postmortem interval) up to the first 60 hours. This is based largely on insect activity. Herein, it is proposed to use the degradation of the intervertebral disc (IVD) after death to determine a relationship between the mechanical properties of cadaveric tissue and time since death in order to extend the 60-hour window. To that end, 1 fresh human spine and 6 pig spines were each separated into sections (6 human and 48 pig), with each section having one intact disc. The sections were buried, unearthed, and cleaned, leaving …


Correlation Of Acoustic Emission Parameters With Weight And Velocity Of Moving Vehicles, Amar Kolgaonkar Jan 2005

Correlation Of Acoustic Emission Parameters With Weight And Velocity Of Moving Vehicles, Amar Kolgaonkar

Electronic Theses and Dissertations

The thesis is motivated by the goal of doing initial investigation and experimentation for the development of Weigh-in-Motion (WIM) system using acoustic emission phenomenon. A great deal of research is going on for measuring the weight of moving vehicles. Weigh-in-motion of commercial vehicles is essential for management of freight traffic, highway infrastructure design and maintenance, and monitoring of heavy weight vehicles. The research work presents a methodology for correlating the weight of a moving vehicle with acoustic emission parameters (such as counts and energy). Furthermore, the correlation between the speed of vehicle with the acoustic emission parameters is developed. Preliminary …


Uv-Liga Compatible Electroformed Nano-Structured Materials For Micro Mechanical Systems, Bo Li Jan 2005

Uv-Liga Compatible Electroformed Nano-Structured Materials For Micro Mechanical Systems, Bo Li

Electronic Theses and Dissertations

UV-LIGA is a microfabrication process realzed by material deposition through microfabricated molds. UV photolithography is conducted to pattern precise thick micro molds using UV light sensitive materials, mostly SU-8, and electroforming is performed to fabricate micro metallic structures defined by the micro molds. Therefore, UV-LIGA is a bottom-up in situ material-addition process. UV-LIGA has received broad attention recently than LIGA – a micro molding fabrication process using X-ray to pattern the micro molds. LIGA is an expansive and is limited in access. In comparing to LIGA, the UV-LIGA is a cost effective process, and is widely accessible and safe. Therefore, …


Non-Silicon Microfabricated Nanostructured Chemical Sensors For Electric Nose Application, Jianwei Gong Jan 2005

Non-Silicon Microfabricated Nanostructured Chemical Sensors For Electric Nose Application, Jianwei Gong

Electronic Theses and Dissertations

A systematic investigation has been performed for "Electric Nose", a system that can identify gas samples and detect their concentrations by combining sensor array and data processing technologies. Non-silicon based microfabricatition has been developed for micro-electro-mechanical-system (MEMS) based gas sensors. Novel sensors have been designed, fabricated and tested. Nanocrystalline semiconductor metal oxide (SMO) materials include SnO2, WO3 and In2O3 have been studied for gas sensing applications. Different doping material such as copper, silver, platinum and indium are studied in order to achieve better selectivity for different targeting toxic gases including hydrogen, carbon monoxide, hydrogen sulfide etc. Fundamental issues like sensitivity, …


Numerical Study Of A High-Speed Miniature Centrifugal Compressor, Xiaoyi Li Jan 2005

Numerical Study Of A High-Speed Miniature Centrifugal Compressor, Xiaoyi Li

Electronic Theses and Dissertations

A miniature centrifugal compressor is a key component of a reverse Brayton cycle cryogenic cooling system. The system is commonly used to generate a low cryogenic temperature environment for electronics to increase their efficiency, or generate, store and transport cryogenic liquids, such as liquid hydrogen and oxygen, where space limit is also an issue. Because of space limitation, the compressor is composed of a radial inlet guide vane, a radial impeller and an axial-direction diffuser (which reduces the radial size because of smaller diameter). As a result of reduction in size, in order to obtain the required static pressure ratio/rise, …


Estimation Of Tangential Momentum Accommodation Coefficient Using Molecular Dynamics Simulation, George Finger Jan 2005

Estimation Of Tangential Momentum Accommodation Coefficient Using Molecular Dynamics Simulation, George Finger

Electronic Theses and Dissertations

The Tangential Momentum Accommodation Coefficient (TMAC) is used to improve the accuracy of fluid flow calculations in the slip flow regime. Under such conditions (indicated by Knudsen number greater than 0.001), the continuum assumption that a fluid velocity at a solid surface is equal to the surface velocity is inaccurate because relatively significant fluid "slip" occurs at the surface. Prior work has not led to a method to quickly estimate a value for TMAC - it is frequently assumed. In this work, Molecular Dynamics techniques are used to study the impacts of individual gas atoms upon solid surfaces to understand …


Finite Element Simulation Of Repair Of Delaminated Composite Structures Using Piezoelectric Layers, Kunal Navale Jan 2005

Finite Element Simulation Of Repair Of Delaminated Composite Structures Using Piezoelectric Layers, Kunal Navale

Electronic Theses and Dissertations

Damage in composite material fabricated aerospace, aeronautical, mechanical, civil and offshore structures often results from factors such as fatigue, corrosion and accidents. Such damage when left unattended can grow at an alarming rate due to the singularity of the stress and strain in the vicinity of the damage. It can lead to increase in the vibration level, reduction in the load carrying capacity, deterioration in the normal performance of the component and even catastrophic failure. In most conditions, the service life of damaged components is extended with repair instead of immediate replacement. Effective repair of structural damage is therefore an …


Vibration Analysis Of Carbon Nanotube Using Continuum Model And Finite Element Model, Hari Subramaniam Jan 2005

Vibration Analysis Of Carbon Nanotube Using Continuum Model And Finite Element Model, Hari Subramaniam

Electronic Theses and Dissertations

The main objective of the thesis is to propose the methods of determining vibration behavior of carbon nanotubes (CNTs) using continuum models and finite element models. Secondary objective is to find the effect of van der Waals force on vibration of multiwalled carbon nanotubes . The study of vibration behavior of CNTs is important because of their potential engineering applications such as nano-mechanical resonators and tips of scanning probe instruments where they are subjected to mechanical vibrations. Continuum modeling is based on an elastic beam model. The interlayer van der Waals interactions are represented by Lennard-Jones potential. In finite element …


Effects Of Transport Properties And Flame Unsteadiness On Nitrogen Oxides Emissions From Laminar Hydrogen Jet Diffusion Flames, Doyoub Park Jan 2005

Effects Of Transport Properties And Flame Unsteadiness On Nitrogen Oxides Emissions From Laminar Hydrogen Jet Diffusion Flames, Doyoub Park

Electronic Theses and Dissertations

Experimental studies on the coupled effects of transport properties and unsteady fluid dynamics have been conducted on laminar, acoustically forced, hydrogen jet diffusion flames diluted by argon and helium. The primary purpose of this research is to determine how the fuel Lewis number and the flow unsteadiness play a combined role in maximum flame temperature and affect NOx emission from jet diffusion flame. The fuel Lewis number is varied by increasing/decreasing the mole fraction of diluents in the fuel stream. Therefore, maximum flame temperatures and then NOx emission levels were expected to differ for Ar- and He-diluted flames. In an …


Advances In The Opto-Mechanical Design And Alignment Of The Hehsi Imaging Spectrometer Based On A Sagnac Interferometer, Michael Stuart Schreiber Jan 2005

Advances In The Opto-Mechanical Design And Alignment Of The Hehsi Imaging Spectrometer Based On A Sagnac Interferometer, Michael Stuart Schreiber

Electronic Theses and Dissertations

The High Efficiency HyperSpectral Imager (HEHSI) is a Fourier Transform hyperspectral imager based on a Sagnac interferometer. This thesis research concentrates on the design upgrade and calibration of HEHSI from a proof of concept instrument to a prototype field instrument. Stability is enhanced by removing degrees of freedom and alignment is enhanced by providing for in-situ adjustments. The use of off the shelf components allows for reduced development time and cost constraints. HEHSI is capable of multiple configurations to accommodate sensors and optics with specialized capabilities for multiple wavelength ranges and viewing conditions. With a spectral response of 400 to …


Spray Cooling For Land, Sea, Air And Space Based Applications, A Fluid Managment System For Multiple Nozzle Spray Cooling And A Guide To High Heat Flux Heater Design, Brian Glassman Jan 2005

Spray Cooling For Land, Sea, Air And Space Based Applications, A Fluid Managment System For Multiple Nozzle Spray Cooling And A Guide To High Heat Flux Heater Design, Brian Glassman

Electronic Theses and Dissertations

This thesis is divided into four distinct chapters all linked by the topic of spray cooling. Chapter one gives a detailed categorization of future and current spray cooling applications, and reviews the major advantages and disadvantages that spray cooling has over other high heat flux cooling techniques. Chapter two outlines the developmental goals of spray cooling, which are to increase the output of a current system and to enable new technologies to be technically feasible. Furthermore, this chapter outlines in detail the impact that land, air, sea, and space environments have on the cooling system and what technologies could be …


Automatic Particle Counting Using An Acoustic Transducer, George Haddad Jan 2005

Automatic Particle Counting Using An Acoustic Transducer, George Haddad

Electronic Theses and Dissertations

Aerosol particle detection and determination finds important applications in the commercial, military and aerospace sectors. Monitoring of clean room environments, and spacecraft integration and check out facilities are some of the most important aplications. In the early days test filters were examined with a microscope to determine the number and size of particles that were being removed from air. Today, most of the commercially available clean room airborne particle counters work on a light scattering principle. They are referred to as Optical Particle Counter or OPC. Essentially, they utilize a very bright laser light source to illuminate the particles. The …


A Dynamic Model Of The Human/Cooling System/Clothing/Environment System, Zhengxiang Pu Jan 2005

A Dynamic Model Of The Human/Cooling System/Clothing/Environment System, Zhengxiang Pu

Electronic Theses and Dissertations

The human body compensates well for moderate climatic heat stress, but artificial environments often block or overwhelm physiological defense mechanism. Personal protective equipment (PPE) is one of sources of heat stress. It protects individual from chemical, physical, or biological hazards, but the high thermal insulation and low vapor permeability of PPE may also lead to substantial heat stress. Personal cooling is widely used to alleviate heat stress, especially for those situations where ambient environmental cooling is not economically viable or feasible. It is important to predict the physiological responses of a person wearing PPE with personal cooling to make sure …