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Articles 1 - 27 of 27
Full-Text Articles in Mechanical Engineering
Autonomous Control And Automotive Simulator Based Driver Training Methodologies For Vehicle Run-Off-Road And Recovery Events, Paul Freeman
Autonomous Control And Automotive Simulator Based Driver Training Methodologies For Vehicle Run-Off-Road And Recovery Events, Paul Freeman
All Dissertations
Traffic fatalities and injuries continue to demand the attention of researchers and governments across the world as they remain significant factors in public health and safety. Enhanced legislature along with vehicle and roadway technology has helped to reduce the impact of traffic crashes in many scenarios. However, one specifically troublesome area of traffic safety, which persists, is run-off-road (ROR) where a vehicle's wheels leave the paved portion of the roadway and begin traveling on the shoulder or side of the road. Large percentages of fatal and injury traffic crashes are attributable to ROR. One of the most critical reasons why …
Particle Scavenging By Water Drops In An Ultrasonic Standing Wave Field, Weiyu Ran
Particle Scavenging By Water Drops In An Ultrasonic Standing Wave Field, Weiyu Ran
All Dissertations
Currently the backbone of the world's energy supply is composed of fossil fuels. However, the combustion of fossil fuels results in the production of enormous quantities of particulate pollutants. The smog resulting from these particulate pollutants causes significant health problem for city dwellers. Wet scrubbers, which use a water spray to scavenge airborne particles, is one of the most widely used devices to control particulate pollutants. Typical wet scrubbers can scavenge particles with diameters bigger than 10 um, but it is inefficient in scavenging particles with diameters on the order of 1 um. Unfortunately these fine particles are more dangerous …
Numerical Simulation Of The Heat Leakage At The Gasket Region Of Domestic Refrigerators, Feng Gao
Numerical Simulation Of The Heat Leakage At The Gasket Region Of Domestic Refrigerators, Feng Gao
All Theses
Computational Fluid Dynamics (CFD) simulations are performed to investigate the heat loss at the gasket of a standard over/under domestic refrigerator. The study numerically simulates a unique experimental test cell with only the gasket region exposed to the ambient environment and other parts protected by insulation (see picture below). The test cell is cubic with an interior cavity having dimensions 2' x 2' x 2' within which a heating element is placed to create a specified temperature difference. A matching set of door and side panels exposes a 2' width of the gasket region to heat transfer with the surroundings. …
Thermo-Physical Property Models And Effect On Heat Pipe Modelling, Devakar Dhingra
Thermo-Physical Property Models And Effect On Heat Pipe Modelling, Devakar Dhingra
All Theses
Heat transfer devices find applications in various aspects of life. Be it residential, commercial or industrial application, efficient heat transfer is a challenge to all. Other than geometric design considerations and wick selection, the optimization of heat transfer in the heat pipe also depends on fluid selection. Heat pipe technology has proven to work efficiently with properly selected thermal fluid, from cryogenic temperatures to very high temperatures. Higher heat transfer ability through small temperature differences makes the heat pipe an efficient technology. Hence, it can be stated that selecting a proper working fluid enhances the heat transfer performance of a …
Design, Analysis And Implementation Of An Experimental System To Harvest Energy From Atmospheric Temperature Variations Using Ethyl Chloride Filled Bellows, Gibran Ali
All Theses
The increase in global warming and the dwindling supplies of fossil fuels have shifted the focus from traditional to alternate sources of energy. This has resulted in a concerted effort towards finding new energy sources as well as better understanding traditional renewable energy sources such as wind and solar power. In addition to the shift in focus towards alternate energy, the last two decades have offered a dramatic rise in the use of digital technologies such as wireless sensor networks that require small but isolated power supplies. Energy harvesting, a method to gather energy from ambient sources including sunlight, vibrations, …
Investigation Of Subgrid-Scale Mixing In Turbulent Plane Jets And Turbulent Jet Flames, Shuaishuai Liu
Investigation Of Subgrid-Scale Mixing In Turbulent Plane Jets And Turbulent Jet Flames, Shuaishuai Liu
All Dissertations
The subgrid-scale (SGS) mixing of mixture fraction, temperature, and species mass fraction in turbulent partially premixed (Sandia) flames is studied. We focus on the effects of the SGS mixing regimes and the spatial relationships among the scalars on the SGS mixing of the species mass fractions. High resolution lines images are used to obtain the scalar filtered mass density function and the conditionally filtered diffusion. The results show that for small SGS variance the scalar fields have a relatively simple structure. For large SGS variance the structure is more complex. The spatial relationships among the scalars result in different SGS …
Thermo-Mechanical Characterization Of Glass And Its Effect On Predictions Of Stress State, Birefringence And Fracture In Precision Glass Molded Lenses, Dhananjay Joshi
Thermo-Mechanical Characterization Of Glass And Its Effect On Predictions Of Stress State, Birefringence And Fracture In Precision Glass Molded Lenses, Dhananjay Joshi
All Dissertations
The Precision Glass Molding (PGM) process was established as an economical and sustainable option for the production of aspherical glass optics to satisfy the increased industrial demand. Applications of precision molded aspherical lenses range from consumer electronics products such as cell phone cameras to defense and medical systems. An aspherical lens can eliminate the spherical and optical aberrations as compared to a spherical lens thus making the lens system more compact and lighter. In spite of being a clean and environmentally friendly process, the lens molding operation suffers from a few drawbacks such as lens profile deviation, stress birefringence/refractive index …
A Model Of The Diurnal Variation In Lake Surface Temperature, Jonathan L. Hodges
A Model Of The Diurnal Variation In Lake Surface Temperature, Jonathan L. Hodges
All Theses
Satellite measurements of water surface temperature can benefit several environmental ap-plications such as predictions of lake evaporation, meteorological forecasts, and predictions of lake overturning events, among others. However, limitations on the temporal resolution of satellite mea-surements restrict these improvements. A model of the diurnal variation in lake surface temperature could potentially increase the effective temporal resolution of satellite measurements of surface tem-perature, thereby enhancing the utility of these measurements in the above applications. Herein, a one-dimensional transient thermal model of a lake is used in combination with surface tempera-ture measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard the …
Microfluidic Particle And Cell Manipulation Using Reservoir-Based Dielectrophoresis, Saurin Patel
Microfluidic Particle And Cell Manipulation Using Reservoir-Based Dielectrophoresis, Saurin Patel
All Dissertations
Controlled manipulation of synthetic particles and biological cells from a complex mixture is important to a wide range of applications in biology, environmental monitoring, and pharmaceutical industry. In the past two decades microfluidics has evolved to be a very useful tool for particle and cell manipulations in miniaturized devices. A variety of force fields have been demonstrated to control particle and cell motions in microfluidic devices, among which electrokinetic techniques are most often used. However, to date, studies of electrokinetic transport phenomena have been primarily confined within the area of microchannels. Very few works have addressed the electrokinetic particle motion …
Equilibrium And Dynamic Charge Storage In Nanopores With Room Temperature Ionic Liquids, Peng Wu
Equilibrium And Dynamic Charge Storage In Nanopores With Room Temperature Ionic Liquids, Peng Wu
All Dissertations
Electrochemical capacitors store electrical energy physically in the electrical double layers at the electrode/electrolyte interfaces. In spite of their high power density and extraordinary cyclability, the widespread deployment of electrochemical capacitors is limited by their moderate energy density. The current surge in interest in electrochemical capacitors is driven by recent breakthroughs in developing novel electrode and electrolyte materials. In particular, electrodes featuring sub-nanometer pores and room-temperature ionic liquids are promising materials for next-generation electrochemical capacitors. To realize the full potential of these materials, a basic understanding of the charge storage mechanisms in them is essential. In this Dissertation, using atomistic …
Fatigue-Induced Failure In Horizontal-Axis Wind-Turbine (Hawt) Blades And Hawt Drivetrain Gears, Varun Chenna
Fatigue-Induced Failure In Horizontal-Axis Wind-Turbine (Hawt) Blades And Hawt Drivetrain Gears, Varun Chenna
All Theses
Wind energy is one of the most promising and the fastest growing installed alternative-energy production technologies. In fact, it is anticipated that by 2030, at least 20% of the U.S. energy needs will be met by various onshore and offshore wind-farms [a collection of wind-turbines (converters of wind energy into electrical energy) at the same location]. A majority of wind turbines nowadays fall into the class of the so-called Horizontal Axis Wind Turbines (HAWTs). Turbine blades and the gearbox are perhaps the most critical components/subsystems in the present designs of HAWTs. The combination of high failure rates (particularly those associated …
Electrokinetic Instabilities In Ferrofluid Microflows, Dhileep Thanjavur Kumar
Electrokinetic Instabilities In Ferrofluid Microflows, Dhileep Thanjavur Kumar
All Theses
Lab-on-a-chip devices have been increasingly used in the past two decades for chemical and biomedical analysis. These devices employ the concepts of microfluidics and offer the promise of incorporating multiple laboratory processes onto a single portable chip. Electric field has been often employed in microfluidic devices for the ease of fluid and sample control as well as the convenience of chip integration and interfacing. Flow instabilities can take place when two fluids of unequal electrical properties are pumped through a microchannel under the application of an adequately strong electric field. The study of these electrokinetic instabilities in microfluidic devices is …
A Verification Of Steady State Discontinuous Solutions Using The Method Of Manufactured Solutions For Finite Volume Computational Fluid Dynamic Codes, Benjamin Grier
All Dissertations
When applying the method of manufactured solutions (MMS) on computational fluid dynamic (CFD) software, it is traditionally a requirement that all solutions be continuous on the computational domain. This stipulation is limiting for the verification and validation of CFD solutions where discontinuities are frequent. This work details the development of a discontinuous MMS method for finite volume codes. The CFD code used throughout this research is a cell centered, finite volume, 1st order, Eulerian scheme within the software AVUS (Air Vehicles Unstructured Solver) which is combined with uniform structured grids. This code is used as a representative testing platform with …
Investigation Of Concurrent Energy Harvesting From Ambient Vibrations And Wind, Amin Bibo
Investigation Of Concurrent Energy Harvesting From Ambient Vibrations And Wind, Amin Bibo
All Dissertations
In recent years, many new concepts for micro-power generation have been introduced to harness wasted energy from the environment and maintain low-power electronics including wireless sensors, data transmitters, controllers, and medical implants. Generally, such systems aim to provide a cheap and compact alternative energy source for applications where battery charging or replacement is expensive, time consuming, and/or cumbersome. Within the vast field of micro-power generation, utilizing the piezoelectric effect to generate an electric potential in response to mechanical stimuli has recently flourished as a major thrust area. Based on the nature of the ambient excitation, piezoelectric energy harvesters are divided …
Advanced Bulk Processing Of Lightweight Materials For Utilization In The Transportation Sector, Justin Milner
Advanced Bulk Processing Of Lightweight Materials For Utilization In The Transportation Sector, Justin Milner
All Dissertations
The overall objective of this research is to develop the microstructure of metallic lightweight materials via multiple advanced processing techniques with potentials for industrial utilization on a large scale to meet the demands of the aerospace and automotive sectors. This work focused on (i) refining the grain structure to increase the strength, (ii) controlling the texture to increase formability and (iii) directly reducing processing/production cost of lightweight material components. Advanced processing is conducted on a bulk scale by several severe plastic deformation techniques including: accumulative roll bonding, isolated shear rolling and friction stir processing to achieve the multiple targets of …
Finite Element Beam Model For Piezoelectric Energy Harvesting Using Higher Order Shear Deformation Theory, Akhilesh Surabhi
Finite Element Beam Model For Piezoelectric Energy Harvesting Using Higher Order Shear Deformation Theory, Akhilesh Surabhi
All Theses
Piezoelectric energy harvesting devices convert mechanical energy to usable electrical energy, which can be used to power other electronic devices and sensors. Typical piezoelectric harvesters are unimorph cantilever composite beams, which have a single active piezoceramic layer and a passive substrate or a bimorph that has a passive substrate sandwiched between two piezoceramic layers. Power is captured across a coupled load resistor circuit in either a series or parallel connection. The mathematical modeling approaches for piezoelectric beam harvesters present in literature range from analytical distributed parameter modeling, to approximate distributed parameter, Rayleigh- Ritz global discretization or finite element local discretization. …
Acoustic Scattering And Radiation Response Of Circular Hexagonal And Auxetic Honeycomb Shell Structures, Vaibhav Iyer
Acoustic Scattering And Radiation Response Of Circular Hexagonal And Auxetic Honeycomb Shell Structures, Vaibhav Iyer
All Theses
Sandwich panels with honeycomb cores are used in many engineering applications because of their high strength to weight ratio, vibration isolation and sound transmission loss characteristics. Previous studies indicate that such sandwich structures with auxetic honeycomb cores (negative in-plane Poisson's ratio) can have a higher sound transmission loss compared to a regular hexagonal honeycomb core structure. In this study, sound scattering and acoustic radiation characteristics of sandwich structures with hexagonal and auxetic cores arranged in a circular pattern interacting with exterior acoustic domains of both air and water have been investigated using finite element analysis. A novel in-plane honeycomb geometry …
Modeling And Design Strategy Of Online Advertising Ecosystem, Qiuchen Wang
Modeling And Design Strategy Of Online Advertising Ecosystem, Qiuchen Wang
All Theses
Internet has undoubtedly become a major and effective medium for advertising, and it will soon replace traditional advertising media. Online advertising ecosystem is consisted of thousands of agents, which can be divided into three types: users, advertisers and publishers. Each type of the agents plays an important role in the ecosystem. However, it is generally very difficult to model such a complex and large-scale system, not to mention the design of suitable strategies for the ecosystem. On the other side, replicator-mutator (RM) dynamics combine tools from evolutionary dynamics of populations, complex networks, and control theory to study evolution of behavior …
Development Of An In Vitro System For Evaluation Of Prosthetic Vein Valves, Ross Gorman
Development Of An In Vitro System For Evaluation Of Prosthetic Vein Valves, Ross Gorman
All Theses
Chronic venous insufficiency is a chronic disorder where venous pressure is not reduced during exercise. In a healthy individual, the vein valves and muscle pumps of the extremities combine to allow for a reduction in venous pressure during exercise. Consistent high pressure in the leg can lead to disability, pain, and ulcer formation. Typical causes of chronic venous insufficiency are venous reflux and acute venous obstruction. Research is under way to develop a prosthetic vein valve that can easily be implanted with a minimally invasive catheter procedure which addresses chronic venous insufficiency. This thesis discusses development of an in vitro …
Theoretical And Computational Design Analysis Of A Harmonica Type Aeroelastic Energy Harvester, Songkai Wang
Theoretical And Computational Design Analysis Of A Harmonica Type Aeroelastic Energy Harvester, Songkai Wang
All Theses
A wind energy harvester inspired by music playing harmonicas was proposed for micro-power generation. The energy harvester utilizes flow-excited self-sustained oscillations of a piezoelectric cantilever beam mounted in a wind pipe to generate electric power. The dependence of the energy harvester's power generation performance on a set of the design parameters such as the chamber volume, aperture width and beam dimensions has been studied previously. However, the performance of the nonlinear multi-physics system with two-way fluid structure coupling also depends on other design parameters such as the geometry of the oscillatory beam, the beam mounting configuration and the geometry of …
Numerical Analysis Of The Extrusion Of Fiber Optic And Photonic Crystal Fiber Preforms Near The Glass Transition Temperature, Mohamed Trabelssi
Numerical Analysis Of The Extrusion Of Fiber Optic And Photonic Crystal Fiber Preforms Near The Glass Transition Temperature, Mohamed Trabelssi
All Dissertations
Conventional clad core fiber optic technology has relied on a concentric structure of glass of different refraction indices. These conventional fibers suffer from constraints and limitations related to thermal expansion compatibility between the core and the glass. The new fiber technology broadly characterized as Microstructured Optic Fibers (MOFs) is intended to lift the limitations of conventional clad core fibers and also extend the range of application of fiber optics. Photonic Cristal Fibers(PCFs) are a special family of Microstructured Optic Fibers characterized by the presence of holes in the cross section of the fiber that are organized in a hexagonal pattern. …
Design Of A Custom Software Application To Monitor And Communicate Cnc Machining Process Information To Aid In Chatter Identification, Valerie Pezzullo
Design Of A Custom Software Application To Monitor And Communicate Cnc Machining Process Information To Aid In Chatter Identification, Valerie Pezzullo
All Theses
In any manufacturing environment, it is important to be able to monitor the Computer Numerical Control (CNC) machining process so that high quality parts can be produced in the least amount of time in order to be profitable. This involves acquiring the proper parameters needed from the machine's controller, which can prove to be difficult with proprietary machine tools that tend to limit access to the internal data collected by the controller. This closed approach to controller design also means that many technological advances that have recently become prevalent in society are not being adopted in the manufacturing industry, preventing …
Adaptive And Robust Braking-Traction Control Systems, John Adcox
Adaptive And Robust Braking-Traction Control Systems, John Adcox
All Dissertations
The designs of commercial Anti-Lock Braking Systems often rely on assumptions of a torsionally rigid tire-wheel system and heavily rely on hub-mounted wheel speed sensors to manage tire-road slip conditions. However, advancements in high-bandwidth braking systems, in-wheel motors, variations in tire/wheel designs, and loss of inflation pressure, have produced scenarios where the tire's torsional dynamics could be easily excited by the braking system actuator. In these scenarios, the slip conditions for the tire-belt/ring will be dynamically different from what can be inferred from the wheel speed sensors. This dissertation investigates the interaction of tire torsional dynamics with ABS & traction …
Inkjet Printing Of Three-Dimensional Vascular-Like Constructs From Cell Suspensions, Changxue Xu
Inkjet Printing Of Three-Dimensional Vascular-Like Constructs From Cell Suspensions, Changxue Xu
All Dissertations
Inkjet printing has found an increasing number of biofabrication applications, specifically organ printing, which has been emerging as a promising solution to the organ donor shortage. While some studies have been conducted to investigate various engineering problems associated with DOD inkjet printing of biological material-based fluids, the pinch-off, the cell-laden droplet formation, the effects of electric field on droplet formation, and challenges in 3D vascular-like construct fabrication haven't been systematically investigated. The objective of this study is to investigate the pinch-off, the cell-laden droplet formation, the effects of electric field on droplet formation, and manufacturing challenges during fabrication using DOD …
Electrokinetic Particle Manipulations In Spiral Microchannels, John Dubose
Electrokinetic Particle Manipulations In Spiral Microchannels, John Dubose
All Theses
Recent developments in the field of microfluidics have created a multitude of new useful techniques for practical particle and cellular assays. Among them is the use of dielectrophoretic forces in 'lab-on-a-chip' devices. This sub-domain of electrokinetic flow is particularly popular due to its advantages in simplicity and versatility. This thesis makes use of dielectrophoretic particle manipulations in three distinct spiral microchannels. In the first of these experiments, we demonstrate the utility of a novel single-spiral curved microchannel with a single inlet reservoir and a single outlet reservoir for the continuous focusing and filtration of particles. The insulator-based negative-dielectrophoretic (repulsive) force …
A Comparative Study: Structural Complexity Metrics Applied Against Function And Assembly Product Graphs In Predicting Market Price And Assembly Time, Sri Ram Mohinder Cherkadu Vasala
A Comparative Study: Structural Complexity Metrics Applied Against Function And Assembly Product Graphs In Predicting Market Price And Assembly Time, Sri Ram Mohinder Cherkadu Vasala
All Theses
The overarching objective of this research is to investigate the measurement and use of complexity in the prediction of product performance metrics (assembly time and market cost) for two model graph types (assembly models and function structures). This research focusses on analyzing how accurate the prediction of performance metrics are based on these graph types. This research focuses on developing four prediction models: Function Structures to predict Market Price (FS-MP), Assembly Models to predict Assembly Time (AM-AT), Function Structures to predict Assembly Time (FS-AT), and Assembly Models to predict Market Price (AM-MP). These assembly models and function structures are analyzed …
Identifying Target Properties For The Design Of Meta-Material Tank Track Pads, Venkata Sampath Dangeti
Identifying Target Properties For The Design Of Meta-Material Tank Track Pads, Venkata Sampath Dangeti
All Theses
On track vehicle systems, track pads are designed to provide traction and support the weight of the vehicle, they have limited service life due to common failure by blowout. According to the literature, blowout is a failure mode caused by overheating due to hysteresis in elastomeric materials during high speed operations. Elastomers are used primarily for their high compliance, which is essential to protect the suspension components and maintain structural integrity of the track pad. The objective of the work is to explore the use of linear elastic meta-materials with optimized topology to replace elastomers and reduce or eliminate the …