Mechanical Engineering Commons^™

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

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

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 …

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 …

Novel Conceptual Design And Anlysis Of Polymer Derived Ceramic Mems Sensors For Gas Turbine Environment, Narasimha Nagaiah

Electronic Theses and Dissertations

Technical challenges for developing micro sensors for Ultra High Temperature and turbine applications lie in that the sensors have to survive extremely harsh working conditions that exist when converting fuel to energy. These conditions include high temperatures (500-1500°C), elevated pressures (200-400 psi), pressure oscillations, corrosive environments (oxidizing conditions, gaseous alkali, and water vapors), surface coating or fouling, and high particulate loading. Several technologies are currently underdeveloped for measuring these parameters in turbine engines. One of them is an optical-based non-contact technology. However, these nondirective measuring technologies lack the necessary accuracy, at least at present state. An alternative way to measure …

Design And Implementation Of An Emission Spectroscopy Diagnostic In A High-Pressure Strand Burner For The Study Of Solid Propell, Jason Arvanetes

Electronic Theses and Dissertations

The application of emission spectroscopy to monitor combustion products of solid rocket propellant combustion can potentially yield valuable data about reactions occurring within the volatile environment of a strand burner. This information can be applied in the solid rocket propellant industry. The current study details the implementation of a compact spectrometer and fiber optic cable to investigate the visible emission generated from three variations of solid propellants. The grating was blazed for a wavelength range from 200 to 800 nm, and the spectrometer system provides time resolutions on the order of 1 millisecond. One propellant formula contained a fine aluminum …

Energy Efficient Transportation For Florida, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

Nearly 30% of energy used in Florida is consumed by our 13 million personal automobiles. Annual gasoline consumption in Florida is about 7.5 billion gallons. Florida also has more registered cars per capita than any other state in the U.S. - nearly one car for each person. The average Florida automobile is driven over 10,000 miles a year burning about 550 gallons of gasoline and costing its owner about $1,500 in fuel costs alone (not to mention payments, insurance, service, repairs, tires, tags, license etc.). Based on a comprehensive analysis, total automobile operating costs average over $850 per month.

Technical Support For Development Of An Attic Simulation Model For The California Energy Commission, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

The California Energy Commission (CEC) is developing a new attic simulation model for assessing residential energy performance within its Title 24 residential compliance methodology. Within this project, we are providing technical support to assist Bruce Wilcox and CEC in development of the model based on Florida Solar Energy Center (FSEC) experience with similar models. We assisted the effort by using data from FSEC instrumented facilities to help verify the eventual simulation. We also outlined critical issues for modeling with the development of the simulation. Given the importance of attic ventilation, we are also conducting new studies of varied ventilation rates …

Showering In The Sun, Florida Solar Energy Center, James Haggard

FSEC Energy Research Center®

For thousands of years, man has used energy from the sun to heat water. Today, the typical way of obtaining hot water for a shower is through a residential or commercial thermal system installed on a building. This type of shower is too big and heavy to use outdoors, although camping facilities and parks may have such systems for their patrons. Original outdoor showers that were developed for use in remote locations were bulky and not particularly portable. Today's solar shower is designed to be practical for camping, recreational and marine use. New products are made of plastic for lighter …

Disasters: Photovoltaics For Special Needs, Florida Solar Energy Center, William Young

FSEC Energy Research Center®

The National Hurricane Center tracks the path of a hurricane to determine where it will make landfall. People in harm's way are informed of its approach and the need to evaluate options to prevent injury and protect lives. One of the many groups of people at high risk is those with special needs. They have health conditions that require special care. Before a disaster, these individuals live in hospitals, care facilities and homes. During and following a disaster, many would be moved, along with their supplies, equipment and a caretaker, to a special needs shelter. Others would stay with relatives …

Renewable Energy And Disaster-Resistant Buildings, Florida Solar Energy Center, William Young

FSEC Energy Research Center®

Hurricanes, floods, tornados and earthquakes create natural disasters that can destroy homes, businesses and the natural environment. Such disasters can happen with little or no warning, leaving hundreds or even thousands of people without medical services, potable water, sanitation, communications and electrical services for up to several weeks. The 2004 hurricane season ravaged the State of Florida, U.S.A., with four major hurricanes within a 6-week timeframe. Over nine million people evacuated their homes and damage to property was extensive.

One proactive strategy to minimize this type of destruction and disruption to lives is the implementation of disaster-resistant buildings that are …

Flexible Roofing Facility: 2004 Summer Test Results, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

The Flexible Roof Facility (FRF) is a test facility in Cocoa, Florida designed to evaluate five roofing systems at a time against a control roof with black shingles and vented attic (Figure E-1). Since 1989 the testing has evaluated how roofing systems impact summer residential cooling energy use and peak demand. In the summer of 2004, the following roofing systems were tested. Materials tested were: Galvalume® unfinished (unpainted) 5-vee metal with vented attic (3rd year of exposure), galvanized unfinished 5-vee metal with vented attic (3rd year of exposure, black shingles with standard attic ventilation (Control Test Cell), white standing seam …

Development Of High Efficiency Air Conditioner Condenser Fans, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

With sponsorship from the U.S. Department of Energy, a research project has designed, fabricated and tested improvements to an air conditioner outdoor unit fan system. The primary objective was to improve condenser fan performance while reducing motor power. We also examined potential changes to the condenser exhaust configuration to enhance air moving efficiency performance. A secondary objective was to provide sound reductions as lower noise AC equipment is important to consumers.

Within conducted tests, an improved high efficiency fan design and advanced exhaust diffuser section reduced fan motor power requirements by approximately 49 W (26%) while providing superior air flow. …

Literature Review Of The Impact And Need For Attic Ventilation In Florida Homes, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

The Florida Department of Community Affairs (DCA) is seeking to examine the impact and necessity of residential attic ventilation in Florida homes. Here, we provide technical support by examining existing data sources on the impacts of attic ventilation both on cooling and heating energy use as well as to attic and home moisture levels. In particular we evaluate the issues with sealed attic construction where the attic is unvented and expanded foam insulation is applied directly to the underside of the roof decking.

We also report the data from Florida Solar Energy Center (FSEC) instrumented facilities to add unique information …

Theoretical Evaluation Of The Nightcool Nocturnal Radiation Cooling Concept, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

An evaluation has been conducted of the potential of a night sky cooling system to substantially reduce space cooling needs in homes in North American climates. The report describes the innovative residential cooling system which uses nocturnal night sky radiation from a roof integrated radiator. The system uses a sealed attic covered by a highly conductive metal roof which is selectively linked by air flow to the main zone with the attic zone to provide cooling- largely during nighttime hours. Available house mass is used to store sensible cooling. Additional dehumidification is done during the evening hours as warranted by …

Executive Summary: Evaluation Of The Impact Of Vacant Home Space Conditioning Strategies On Summer Relative Humidity, Energy, And Peak Load, Florida Solar Energy Center, Charles Withers, Jr.

FSEC Energy Research Center®

The Vacant Home Space Conditioning Study was sponsored by Florida Power & Light (FPL) as part of its Conservation R&D Program and carried out by the Florida Solar Energy Center (FSEC). In the US, about one in four retiree "snowbirds" make Florida their destination to escape the northern cold. Snowbird residents number more than 900,000 in Florida during the winter. In some counties of FPL's territory these seasonal residents compose up to 15% of the population (Shih, 1981). This pattern of seasonal occupancy creates a need for space conditioning guidelines for vacant homes to avoid mold problems while minimizing both …

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

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

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 …

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

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

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

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

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

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

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

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

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 …

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 …

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 …