Experimental Study Of Separated Ramp-Induced Shock/Boundary-Layer Interaction With Upstream Micro-Vortex Generator At Mach 2.5,
2014
University of Texas at Arlington
Experimental Study Of Separated Ramp-Induced Shock/Boundary-Layer Interaction With Upstream Micro-Vortex Generator At Mach 2.5, Yusi Shih
Mechanical and Aerospace Engineering Dissertations - Archive
Shock wave/boundary layer interactions (SBLIs) are important issues for high-speed vehicles. SBLIs reduce the performance of aerodynamic surfaces and engine inlets, amongst a number of adverse effects. Micro-vortex generators (MVGs) are a flow control method with strong potential to mitigate the effects of SBLI by energizing the boundary layer through momentum transfers from the freestream. They have been implemented in actual configurations at low speeds. The present research includes a combined experimental and theoretical analysis of the evolution of the perturbation downstream the MVG, the formation of vortices, and their interaction with the shock front. Experiments were performed with a …
Analytical Solutions Of Steady-State Heat Conduction In Multi-Layer Stack Packaging,
2014
University of Texas at Arlington
Analytical Solutions Of Steady-State Heat Conduction In Multi-Layer Stack Packaging, Saeed Ghalambor
Mechanical and Aerospace Engineering Dissertations - Archive
Analytical models that can be utilized in modeling the steady-state temperature solutions of planar and 3D packaged integrated circuits are discussed. This mathematically-driven model will include solutions for uniform and non-uniform footprint die stack systems as well as planar flip chip packages. These analytically obtained temperature solutions will include the contribution of thermal resistance for both cases as well as perfect contact scenarios. The acquired solution will accommodate any kind of boundary conditions (first, second and third kind) on the top and bottom surfaces of the stack system with the sides being adiabatic. Furthermore, the algorithm developed will consider volumetric …
Computational Analysis Of Nanostructures Formed In Molten Salt Nanofluids,
2014
University of Texas at Arlington
Computational Analysis Of Nanostructures Formed In Molten Salt Nanofluids, Vidula B. Pawar
Mechanical and Aerospace Engineering Theses - Archive
Meeting the continuously increasing demand of `clean' energy is the biggest challenge of the energy research field. Amongst the many renewable sources of energy, energy from the Sun is one of the biggest sources in the form of light and heat. Photovoltaic cells and concentrated solar power are few of the solar energy harnessing technologies. Photovoltaic cells use semiconductor materials to directly convert energy from sun into electricity. CSP uses a combination of solar receivers (mirrors or lenses) to concentrate the solar thermal energy which is further converted into electricity using the common thermodynamic cycle. One of the Photovoltaic (PV) …
Computational Fluid Dynamics Simulation Of United Launch Alliance Delta Iv Hydrogen Plume Mitigation Strategies,
2014
University of Central Florida
Computational Fluid Dynamics Simulation Of United Launch Alliance Delta Iv Hydrogen Plume Mitigation Strategies, Stephen Guimond
Electronic Theses and Dissertations
During the launch sequence of the United Launch Alliance Delta IV launch vehicle, large amounts of pure hydrogen are introduced into the launch table and ignited by Radial-Outward-Firing-Igniters (ROFIs). This ignition results in a significant flame, or plume, that rises upwards out of the launch table due to buoyancy. The presence of the plume causes increased and unwanted heat loads on the surface of the vehicle. A proposed solution is to add a series of fans and structures to the existing launch table configuration that are designed to inject ambient air in the immediate vicinity of the launch vehicle's nozzles …
Thermal Conductivity Of Alumina And Silica Nanofluids,
2014
Minnesota State University - Mankato
Thermal Conductivity Of Alumina And Silica Nanofluids, Julian Bernal Castellanos
All Graduate Theses, Dissertations, and Other Capstone Projects
This thesis studies the effects of the base fluid, particle type/size, and volumetric concentration on the thermal conductivity of Alumina and Silica nanofluids. The effects of base fluid were observed by preparing samples using ethylene glycol (EG), water, and mixtures of EG/water as the base fluid and Al2O3 (10 nm) nanoparticles. The particles type/size and volumetric concentration effects were tested by preparing samples of nanofluids using Al2O3 (10nm), Al2O3 (150nm), SiO2 (15 nm), and SiO2 (80 nm) nanoparticles and ionized water as base fluid at different volumetric concentrations. All samples were mixed using a sonicator for 30 minutes and a …
Thermo-Mechanical Feasibility Study Of Copper And Gold Wirebonds In 3d Electronic Package,
2014
University of Texas at Arlington
Thermo-Mechanical Feasibility Study Of Copper And Gold Wirebonds In 3d Electronic Package, Gaurang Naware
Mechanical and Aerospace Engineering Theses - Archive
3 Dimensional (3D) Electronics Packaging has emerged as a revolutionary trend in the micro-electronics industry. It has made possible cost-effective system integration and size scaling while reducing the interconnect delay. The ever increasing demand for better mechanical, thermal, electrical performance, improved reliability and cost effective semiconductor manufacturing technology has encouraged the engineers to replace Gold (Au) by Copper (Cu). In a survey conducted by Semiconductor Equipment and Materials International, to study the industry mood related to wirebond technology, it was observed that 72% of the leading semiconductor companies are considering switching to Cu [1]. The only major concern regarding the …
Fabrication Of Superhydrophobic Polystyrene Surfaces With Tunable Adhesion By Modulating Strain Recovery Temperature,
2014
University of Texas at Arlington
Fabrication Of Superhydrophobic Polystyrene Surfaces With Tunable Adhesion By Modulating Strain Recovery Temperature, Prasha Sarwate
Mechanical and Aerospace Engineering Theses - Archive
In this work, different superhydrophobic structures were fabricated on the surfaces of polystyrene (PS) blocks, using oxygen reactive ion etch (ORIE) and controllable strain recovery. The PS used here is a thermal shape memory polymer (SMP). Microhills are first generated on the surface of a PS block by ORIE. The PS block is then heated up, which triggers the strain recovery. During this process of recovering its original shape, the PS block gradually reduces its lateral dimensions, while increasing its thickness. Using different recovery temperatures, the surface morphologies can be controlled, which provides an approach to adjust surface wetting properties, …
Electric Vehicle Sales And Future Projections,
2014
Florida Solar Energy Center
Electric Vehicle Sales And Future Projections, Florida Solar Energy Center, David L. Block
FSEC Energy Research Center®
The objective of this research is to evaluate historical vehicle sales as a basis to determine future projections of electric vehicles sales and cumulative values within the U.S. and by selected states. The results for the U.S. show that the cumulative sales of electric vehicles through 2013 is 167,600 vehicles with 96, 700 sold in 2013 or that 58% of total vehicles were sold in 2013. Depending upon the escalation rate selected, the 10 year future U.S. cumulative sales (2023) are predicted to be from 1.8 to 7.3 million vehicles. Future predictions were also done for the states of Florida, …
Piezospectroscopic Calibration Of Alumina-Nanocomposites For The Development Of Stress-Sensing Structures,
2014
University of Central Florida
Piezospectroscopic Calibration Of Alumina-Nanocomposites For The Development Of Stress-Sensing Structures, Daniela Fugon-Dessources
Electronic Theses and Dissertations
Alpha-alumina is known to exhibit photo-luminescent (PL) properties, mainly characteristic R-lines that shift according to applied stress. In addition to showing excellent PL properties, polymers with embedded alumina nanoparticles have been shown to improve the overall composite mechanical properties. While the use of the PL properties to develop stress-sensing materials using an alumina-epoxy material has been success- fully shown in compression, the properties have not been developed for tension. In this study, the PL response of variable volume fraction alumina-epoxy composites will be determined under tensile conditions. It is expected that increasing the volume fraction of alumina nanoparticles will increase …
Response Of Electrified Micro-Jets To Electrohydrodynamic Perturbations,
2014
University of Central Florida
Response Of Electrified Micro-Jets To Electrohydrodynamic Perturbations, Weiwei Yang
Electronic Theses and Dissertations
The breakup of liquid jets is ubiquitous with rich underpinning physics and widespread applications. The natural breakup of liquid jets originates from small ambient perturbations, which can grow exponentially until the amplitude as large as the jet radius is reached. For unelectrified inviscid jets, surface energy analysis shows that only the axisymmetric perturbation is possibly unstable, and this mode is referred as varicose instability. For electrified jets, the presence of surface charge enables additional unstable modes, among which the most common one is the whipping (or kink) instability that bends and stretches the charged jet that is responsible for the …
A Study Of Compressive Sensing For Application To Structural Health Monitoring,
2014
University of Central Florida
A Study Of Compressive Sensing For Application To Structural Health Monitoring, Vaahini Ganesan
Electronic Theses and Dissertations
One of the key areas that have attracted attention in the construction industry today is Structural Health Monitoring, more commonly known as SHM. It is a concept developed to monitor the quality and longevity of various engineering structures. The incorporation of such a system would help to continuously track health of the structure, indicate the occurrence/presence of any damage in real time and give us an idea of the number of useful years for the same. Being a recently conceived idea, the state of the art technique in the field is straight forward - populating a given structure with sensors …
Mechanical And Thermal Characterization Of Continuous Fiber-Reinforced Pyrolysis-Derived Carbon-Matrix Composites,
2014
University of Central Florida
Mechanical And Thermal Characterization Of Continuous Fiber-Reinforced Pyrolysis-Derived Carbon-Matrix Composites, Donovan Lui
Electronic Theses and Dissertations
Maturity of high-temperature polymer-reinforced composites defer to conventionally expensive and intensive methods in both material and manufacturing aspects. Even traditional carbon-carbon, aerogel, and ceramic approaches are highly limited by difficult manufacturing techniques and are subject to sensitive handling throughout their processing and lifetime. Despite their utility in extreme environments, the high costs of existing high-temperature composites find limited practical applicability under high-performance applications. The development of continuous fiber-reinforced pyrolysis-derived carbon-matrix composites aim to circumvent the issues surrounding the manufacturing and handling of conventional high-temperature composites. Polymer matrix composites (PMCs) have a number of attractive properties including light weight, high stiffness-to-weight …
Assessment Of Corn Stover Torrefaction For On-Farm Biochar Production,
2014
South Dakota State University
Assessment Of Corn Stover Torrefaction For On-Farm Biochar Production, Christina M. Gerometta
Electronic Theses and Dissertations
Torrefaction is a thermochemical pretreatment process that is typically achieved by slowly heating biomass (<50°C/min) within the temperature range of 200 – 300°C under an inert atmosphere. This process yields a storable solid product with enhanced fuel characteristics that are influenced by the ligno-cellulosic composition of the original feedstock and the imposed torrefaction conditions (time and temperature). This study is an assessment of corn stover properties that are relevant for designing an on-farm torrefaction system. The first portion of this study compared the thermal decomposition behaviors of corn stover fractions (leaf, stalk, cob) to the respective ligno-cellulosic composition using thermo-gravimetric analysis. It was found that the thermal decomposition pattern correlates to the structure and ratio of ligno-cellulosic polymers and provides design guidelines for an on-farm torrefaction system capable of handling large quantities of mixed fraction stover. The second part of this study investigated the effects of torrefaction time and temperature on the mass and energy yield of mixed fraction corn stover using a 46.3 L batch style reactor. It was found that longer reaction times and higher temperatures were required to obtain mass and energy yields similar to those found using lab-scale reactors and finely milled samples. Non-uniform torrefaction occurred between fractions due to chemical composition of each fraction and proximity to the heating elements.
Using Acoustic Emission Monitoring For Energy-Based Fatigue Life Prediction,
2014
South Dakota State University
Using Acoustic Emission Monitoring For Energy-Based Fatigue Life Prediction, Sepehr Nesaei
Electronic Theses and Dissertations
The study of fatigue and fracture mechanics is crucial to the health monitoring and overall safety of aerospace and civil structures. The materials used to manufacture these industry parts have inherent anomalies that eventually grow under cyclic loadings during regular operation. The ASTM and/or military testing guidelines used to analyze and qualify structures and materials for use are costly and time consuming. Therefore, any additional methods or knowledge that can be used to reduce the number of tests will be useful to the industry to avoid unnecessary costs. Acoustic emission (AE) monitoring is currently used in many applications to assess …
Semiactive Virtual Control Method For Robots With Regenerative Energy-Storing Joints,
2014
Cleveland State University
Semiactive Virtual Control Method For Robots With Regenerative Energy-Storing Joints, Hanz Richter, Daniel J. Simon, Antonie J. Van Den Bogert
Mechanical Engineering Faculty Publications
A framework for modeling and control is introduced for robotic manipulators with a number of energetically self-contained semiactive joints. The control approach consists of three steps. First, a virtual control design is conducted by any suitable means, assuming a fully-actuated system. Then, virtual control inputs are matched by a parameter modulation law. Finally, the storage dynamics are shaped using design parameters. Storage dynamics coincide with the system's internal dynamics under exact virtual control matching. An internal energy balance equation and associated self-powered operation condition are given for the semiactive joints. This condition is a structural characteristic of the system and …
Dynamic Fracture Analysis Of Polycarbonate By The Optical Method
Of Caustics,
2014
Peking University
Dynamic Fracture Analysis Of Polycarbonate By The Optical Method Of Caustics, Guiyun Gao, Zheng Li, Mehrdad Negahban
Department of Mechanical and Materials Engineering: Faculty Publications
Glassy polycarbonate (PC) is a widely used engineering material in industries, since it has high strength and toughness as well as good transparency. However, these advantages of PC can be suppressed by physical aging, especially its dynamic fracture toughness. In addition, the material properties of PC can be changed dramatically after large plastic compressive deformation, and it can show obvious orthotropic behavior. Here, the combined effect of aging and plastic compressive deformation on dynamic facture of PC was investigated by the optical method of caustics. The dynamic reflective method of caustics for orthotropic materials was developed here to study the …
Performance Evaluation Of Polyurethane Composites Using Vacuum Infusion Process,
2014
Missouri University of Science and Technology
Performance Evaluation Of Polyurethane Composites Using Vacuum Infusion Process, Mohaned M. Mohamed
Doctoral Dissertations
"Glass fiber-reinforced polymer composites have promising applications in infrastructures due to their low cost, high specific stiffness/strength, and corrosion resistance. The pultrusion process is often used to manufacture glass fiber-reinforced polyurethane (PU) composite. The objective of this study is to use thermoset PU resin to manufacture high quality composites for infrastructure applications using vacuum assisted resin transfer molding (VARTM) process. Using VARTM to fabricate PU resins presents unique challenges. Several modifications however have helped with overcoming these problems. In part I of the research, the mechanical performance of two different PU resin not only evaluated but also compared to one …
Modeling And Simulation Of Hydrokinetic Composite Turbine System,
2014
Missouri University of Science and Technology
Modeling And Simulation Of Hydrokinetic Composite Turbine System, Haifeng Li
Doctoral Dissertations
"The utilization of kinetic energy from the river is promising as an attractive alternative to other available renewable energy resources. Hydrokinetic turbine systems are advantageous over traditional dam based hydropower systems due to "zero-head" and mobility. The objective of this study is to design and analyze hydrokinetic composite turbine system in operation. Fatigue study and structural optimization of composite turbine blades were conducted. System level performance of the composite hydrokinetic turbine was evaluated. A fully-coupled blade element momentum-finite element method algorithm has been developed to compute the stress response of the turbine blade subjected to hydrodynamic and buoyancy loadings during …
Integration Of A Pulsating Heat Pipe In A Flat Plate Heat Sink,
2014
South Dakota State University
Integration Of A Pulsating Heat Pipe In A Flat Plate Heat Sink, Mitchell Hoesing
The Journal of Undergraduate Research
The ongoing development of faster and smaller electronic components has led to a need for new technologies to effectively dissipate waste thermal energy. The pulsating heat pipe (PHP) shows potential to meet this need, due to its high heat flux capacity, simplicity, and low cost. A flat plate PHP was integrated into an aluminum flat plate heat sink with a simulated electronic load. The PHP heat sink used water as the working fluid and had 20 parallel channels with dimensions 2 mm × 2 mm × 119 mm. Experiments were run under various operating conditions, and the thermal resistance of …
Vibrations Analysis On Tennis Racket String,
2014
South Dakota State University
Vibrations Analysis On Tennis Racket String, Jenny Blackburne
The Journal of Undergraduate Research
The purpose of this project was to investigate and analyse the vibration of a tennis racket string when a ball is hit. This was done using concepts of mechanical vibrations and modelled using Microsoft Excel. The displacement of the tennis string over time was graphed for two different positions on the racket and two different relative speeds of the tennis ball. It was found that the position of the tennis ball on the racket has very little effect on the displacement of the strings. If the ball or racket is moving faster when the ball is hit, then the displacement …
