Utilization Of Molten Nitrate Salt Nanomaterials For Heat Capacity Enhancement In Solar Power Applications,
2013
University of Texas at Arlington
Utilization Of Molten Nitrate Salt Nanomaterials For Heat Capacity Enhancement In Solar Power Applications, Ramaprasath Devaradjane
Mechanical and Aerospace Engineering Theses - Archive
Concentrated solar power (CSP) system use general thermodynamic cycle to produce electricity and thus the system efficiency is mainly determined by the working temperature of heat transfer fluid (HTF). Organic-based HTFs (e.g., mineral oil, ethylene glycol, etc.) were firstly used for this application. However, this has limited the working temperature of CSP around 300 °C since these organic material starts to decompose below 400 °C. Typical liquid salts are thermally stable to high temperatures (500~600 °C). Using these salts as HTF can significantly increase the working temperature and as a result the system efficiency can also be highly enhanced. For …
Design And Analysis Of A Compression Molded Carbon Composite Wheel Center,
2013
University of Texas at Arlington
Design And Analysis Of A Compression Molded Carbon Composite Wheel Center, Vinoth Kumar Dhananjayan
Mechanical and Aerospace Engineering Theses - Archive
Importance of closed mold and short fibers in the manufacture of carbon composite parts was realized based on a study of existing manufacturing processes for thermoset resins as these can improve production volumes, cost reduction of the part, production of near net shape parts eliminating secondary operations and production of parts with near isotropic properties due to random fiber orientation. Compression molding process is the most preferred process as this addresses the problems of fiber damage effectively because of the minimal flow in the material. A brief study was done on the compression molded carbon composite parts in the industry. …
Integrated Modeling Approach For Solid Oxide Fuel Cell-Based Power Generating System,
2013
University of Texas at Arlington
Integrated Modeling Approach For Solid Oxide Fuel Cell-Based Power Generating System, Jeongpill Ki
Mechanical and Aerospace Engineering Dissertations - Archive
Solid oxide fuel cell (SOFC) systems have been recognized as the most advanced power generation system with the highest thermal efficiency with a compatibility with a wide variety of hydrocarbon fuels, synthetic gas from coal, hydrogen, etc. As a result of research focused on numerical studies for a tubular type- or a planar type-SOFC, fuel flexibility, design aspects of SOFC, materials, start-up process, and so on, SOFC technologies are remarkably being developed.Currently, most research activities are limited to a component level characterization of single fuel cell stack or material research for catalyst, electrolyte, sealing process, etc. In other words, approaches …
Development Of Computational Fluid Dynamics (Cfd) Based Erosion Models For Oil And Gas Industry Applications,
2013
University of Texas at Arlington
Development Of Computational Fluid Dynamics (Cfd) Based Erosion Models For Oil And Gas Industry Applications, Deval Pandya
Mechanical and Aerospace Engineering Dissertations - Archive
Erosion prediction plays a critical role in different oil and gas industry segments including drill bit manufacturing, measurement & logging while drilling (M&LWD), and reservoir engineering/completions tools. Recently, Computational Fluid Dynamics (CFD) is used to predict erosion due to multiphase flows in complex geometries. Currently used CFD-based erosion models are able to predict erosion regions fairly accurately in various applications but they are highly inaccurate when it comes topredictions of quantities like erosion rate. Predicted quantities within an order of magnitude of the measured values are common and may be considered acceptable for many applications in the industry simply because …
Advanced Materials Characterization Based On Full Field Deformation Measurements,
2013
University of Texas at Arlington
Advanced Materials Characterization Based On Full Field Deformation Measurements, A Paige Carpentier
Mechanical and Aerospace Engineering Dissertations - Archive
Accurate stress-strain constitutive properties are essential for understanding the complex deformation and failure mechanisms for materials with highly anisotropic mechanical properties. Among such materials, glass-fiber- and carbon-fiber-reinforced polymer-matrix composites play a critical role in advanced structural designs. The large number of different methods and specimen types currently required to generate three-dimensional allowables for structural design slows down the material characterization. Also, some of the material constitutive properties are never measured due to the prohibitive cost of the specimens needed. This work shows that simple short-beam shear (SBS) specimens are well-suited for measurement of multiple constitutive properties for composite materials and …
Multi-Objective Design Optimization Of Beol/Fbeol Region During Chip Attachment To Substrate,
2013
University of Texas at Arlington
Multi-Objective Design Optimization Of Beol/Fbeol Region During Chip Attachment To Substrate, Hardik Parekh
Mechanical and Aerospace Engineering Theses - Archive
Semiconductor industry has recognized the need to replace traditional Al/SiO2 interconnects with Cu/Low-k interconnects in the mainstream electronics devices following the latter's impact on power, RC delay, and cross-talk reduction. However due to lower elastic modulus, strength, and poor adhesion characteristic, reliability of the Cu/Low-k interconnects turns out to be a concern for its integration in the back-end-of-line (BEoL). Flip-chip attachment process (cooling from ~200C to room) can result in critical damage in nano-scale Cu/Low-k interconnects. The objective of this study is to improve the reliability of Cu/Low-k interconnects during die attach reflow process for a specific die to substrate …
Design And Control Of A Smart Bed For Pressure Ulcer Prevention,
2013
University of Texas at Arlington
Design And Control Of A Smart Bed For Pressure Ulcer Prevention, Zachary Govier Brush
Mechanical and Aerospace Engineering Theses - Archive
This work details the design, simulation, and experimental testing of a mechanically actuated smart hospital bed for the prevention of pressure ulcers in hospital patients. The smart hospital bed, or Smartbed, is designed to improve the “turning” process currently performed by health care workers, ensuring that patients are turned consistently and decreasing the labor requirement for caregivers. The mechanical structure of the bed is described, along with its advantages over current Smartbed products. Next, dynamic models of the Smartbed actuating systems are discussed along with descriptions of the devised single-unit and overall bed control systems. The control equations determined in …
Design And Evaluation Of A Chemical Reactor For The Pyrolysis Wood Pellets,
2013
University of Texas at Arlington
Design And Evaluation Of A Chemical Reactor For The Pyrolysis Wood Pellets, Pawarat Bootpakdeetam
Mechanical and Aerospace Engineering Theses - Archive
Currently there is interest in converting waste biomass into valuable products, such as fuels and specialty chemicals. However, the product composition, yield, the energy required to run the reaction, and the required residence time are all factors influence the economics of the process. Estimate of these factors at the laboratory scale is important for evaluating whether a pilot or demonstration scale study is warranted. In this work, a bench-scale chemical reactor was designed and constructed to conduct the batch pyrolysis of pelletized biomass. The reactor was tested using pine wood pellets as the feedstock. The feedstock weight to reactor volume …
Optimal Design Of Beams,
2013
University of Texas at Arlington
Optimal Design Of Beams, Shivakumar Samala
Mechanical and Aerospace Engineering Theses - Archive
Beams are basic structural components that are capable of withstanding load primarily by resisting bending. Unlike Euler-Bernoulli beams, Timoshenko beams undergo both shear deformation and rotational effects, making it suitable for analyzing the behavior of thick or short beams, composite beams and beams that are subjected to high frequency excitation when their wave length becomes shorter. This thesis work focuses on optimal design of straight and tapered Timoshenko beams under static and dynamic constraints for rectangular and circular cross sections. In this work Timoshenko beam static and dynamic equations were studied. The finite element method was used for static and …
Study Of The Capabilities Of Electrowetting On Dielectric Digital Microfluidics (Ewod Dmf) Towards The High Efficient Thin-Film Evaporative Cooling Platform,
2013
University of Texas at Arlington
Study Of The Capabilities Of Electrowetting On Dielectric Digital Microfluidics (Ewod Dmf) Towards The High Efficient Thin-Film Evaporative Cooling Platform, Jagath B. Yaddessalage
Mechanical and Aerospace Engineering Dissertations - Archive
With the current technological advancement, the size of the electronic components is being reduced to smaller and compact sizes. In the meantime, the packaging density and power consumption is ever increasing. To tackle this challenge, an efficient cooling technology is required.Thin-film evaporation is a very efficient cooling technology. A practical application using thin-film evaporation is a spray cooling which is known as the cooling method that can handle very high heat flux. However, a random spray of coolant cannot guarantee a thin coolant film, therefore either local dry-out or flooding may occur, which hampers cooling efficiency significantly. Moreover, bulky spraying …
Airdata Sensor Based Position Estimation And Fault Diagnosis In Aerial Refueling,
2013
University of Texas at Arlington
Airdata Sensor Based Position Estimation And Fault Diagnosis In Aerial Refueling, Hakki Erhan Sevil
Mechanical and Aerospace Engineering Dissertations - Archive
Aerial refueling is the process of transferring fuel from one aircraft (the tanker) to another (the receiver) during flight. In aerial refueling operations, the receiver aircraft is exposed to nonuniform wind field induced by tanker aircraft, and this nonuniform wind field leads to differences in readings of airdata sensors placed at different locations on the receiver aircraft. There are advantages and disadvantages of this phenomenon. As an advantage, it is used as a mechanism to estimate relative position of the receiver aircraft inside the nonuniform wind field behind the tanker. Using the difference in the measurements from multiple identical sensors, …
A Semi-Analytical Approach To Obtain Physical Fields In Heterogeneous Materials,
2013
University of Texas at Arlington
A Semi-Analytical Approach To Obtain Physical Fields In Heterogeneous Materials, Thanuuj S. Pathapallli
Mechanical and Aerospace Engineering Dissertations - Archive
Predicting the macroscopic response of heterogeneous materials has been the subject of extensive research in the engineering community, even more so, in the composites guild. With analytical solutions being almost impossible to obtain for such open ended problems, and numerical techniques being computationally expensive, semi-analytical methods are highly sought after. This dissertation is one such effort aimed at presenting a semi-analytical approach that serves as a confluence of effective analytical and numerical techniques, to solve for engineering fields in a heterogeneous material characterized by inclusions embedded in a matrix medium. The approach essentially involves the analytical derivation of permissible functions, …
Physically Representative Atomistic Modeling Of Atomic-Scale Friction,
2013
The University of Akron, Main Campus
Physically Representative Atomistic Modeling Of Atomic-Scale Friction, Yalin Dong
Mechanical Engineering Faculty Research
Nanotribology is a research field to study friction, adhesion, wear and lubrication occurred between two sliding interfaces at nano scale. This study is motivated by the demanding need of miniaturization mechanical components in Micro Electro Mechanical Systems (MEMS), improvement of durability in magnetic storage system, and other industrial applications. Overcoming tribological failure and finding ways to control friction at small scale have become keys to commercialize MEMS with sliding components as well as to stimulate the technological innovation associated with the development of MEMS. In addition to the industrial applications, such research is also scientifically fascinating because it opens a …
Low Strain Rate Studies Of Alumina Epoxy Composites Using Piezospectroscopy,
2013
University of Central Florida
Low Strain Rate Studies Of Alumina Epoxy Composites Using Piezospectroscopy, Ashley Jones
Electronic Theses and Dissertations
Particulate composites are widely used in many aerospace and military applications as energetic materials, armor materials or coatings and their behavior under dynamic loads have gained increasing significance. The addition of modifiers such as alumina nanoparticles generally facilitates the improvement of the mechanical strength to density ratio due to high specific area and particle rigidity. This allows for sufficient particlematrix bonding and therefore improved stiffness and load transfer in the composite. Photo-luminescent α-alumina nanoparticles when embedded in an epoxy matrix allow for the added benefit of in situ measurements at low strain rates to provide stress-sensitive information using the particle …
Electrohydrodynamic Manipulation Of Liquid Droplet Emulsions In A Microfluidic Channel,
2013
University of Central Florida
Electrohydrodynamic Manipulation Of Liquid Droplet Emulsions In A Microfluidic Channel, Jonathan Wehking
Electronic Theses and Dissertations
This work specifically aims to provide a fundamental framework, with some experimental validation, for understanding droplet emulsion dynamics in a microfluidic channel with an applied electric field. Electrification of fluids can result in several different modes of electrohydrodynamics (EHD). Several studies to date have provided theoretical, experimental, and numerical results for stationary droplet deformations and some flowing droplet configurations, but none have reported a method by which droplets of different diameters can be separated, binned and routed through the use of electric fields. It is therefore the goal of this work to fill that void and report a comprehensive understanding …
Thermo-Mechanical Analysis Of Nano-Imprint Lithography,
2013
University of Texas at Arlington
Thermo-Mechanical Analysis Of Nano-Imprint Lithography, Bhavik C. Patel
Mechanical and Aerospace Engineering Theses - Archive
Nanoimprint Lithography is being explored by the semiconductor industries for future high volume fabrication of silicon chips, memory devices and patterned media. Nanolithography and Microlithography has played pivotal role in the field of manufacturing microchips and integrated circuits in semiconductor devices. There is an urge to investigate Nanoimprint lithography, a high-throughput, low-cost and nonconventional lithographic method. Thermal management is a critical area that is necessary to be administrated. As recent advancements are being observed in the field of electronic packaging for thermal optimization, likewise steps are also important in this fabrication process. This process involves a heat that is generated …
Compressibility Effects On The Non-Linear Receptivity Of Boundary Layers To Dielectric Barrier Discharges,
2013
University of Texas at Arlington
Compressibility Effects On The Non-Linear Receptivity Of Boundary Layers To Dielectric Barrier Discharges, Marie F.C. Denison
Mechanical and Aerospace Engineering Theses - Archive
The reduction of drag and aerodynamic heating caused by boundary layer transition is of central interest for the development of hypersonic vehicles. Receptivity to flow perturbation in the form of Tollmien-Schlichting (TS) wave growth often determines the first stage of the transition process, which can be delayed by depositing specific excitations into the boundary layer. Weakly ionized Dielectric Barrier Discharge (DBD) actuators are being investigated as possible sources of such excitations, but little is known today about their interaction with high-speed flows. In this framework, the first part of the thesis is dedicated to a receptivity study of laminar compressible …
Rotordynamic Performance Of A Rotor Supported By Three Pad Hybird Foil Bearings With Controlled Air Injection,
2013
University of Texas at Arlington
Rotordynamic Performance Of A Rotor Supported By Three Pad Hybird Foil Bearings With Controlled Air Injection, Sandesh Gudemane
Mechanical and Aerospace Engineering Theses - Archive
Air Foil Bearings have found their place in the commercial applications of turbo machinery. They are cleaner and more reliable at high speeds than their conventional counterparts (Rolling Element Bearings). Low drag friction and apparently no contact during the operation results in a better service life and superior rotor-dynamic performance of the air foil bearings (AFBs). With these advantages AFB has proved to be a suitable option for oil-free turbo-machinery. Further development in AFBs suggest that pressurizing these bearings externally results in remarkably better load carrying capacity, heat dissipation and a more stable rotor. These externally air pressurized bearings which …
Improving Cooling Efficiency Of Servers By Replacing Smaller Chassis Enclosed Fans With Larger Rack-Mount Fans,
2013
University of Texas at Arlington
Improving Cooling Efficiency Of Servers By Replacing Smaller Chassis Enclosed Fans With Larger Rack-Mount Fans, Bharath Nagendran
Mechanical and Aerospace Engineering Theses - Archive
As a common practice in the data center industry, chassis fans are used to direct air flow independent from neighboring servers. However, these fans are less efficient compared to larger rack level counterparts and also operate at higher sound levels. In this study, a novel approach is proposed whereby the smaller chassis enclosed fans are replaced with an array of larger fans, installed behind the stacked servers that share air flow. As a baseline study for comparison of the current scenario, a CPU dominated 1.5U Open Compute server, with four 60mm fans installed within the server, is characterized experimentally for …
Comparative Analysis Of Widely Used Air Containment Systems In Commercial Data Centers For Maximum Cooling Performance,
2013
University of Texas at Arlington
Comparative Analysis Of Widely Used Air Containment Systems In Commercial Data Centers For Maximum Cooling Performance, Kasturi Rangan Rajagopalan
Mechanical and Aerospace Engineering Theses - Archive
Many data centers implement containment systems to improve cooling system performance. Literature review shows that Hot Aisle Containment System (HACS) have higher supply air temperature set point than Cold Aisle Containment Systems (CACS) [1]. CACS in data centers have claims to support higher density loads when compared to HACS systems [2]. Data center owners suggest that containment of a group of racks can be a very effective technique to improve cooling performance. On the other hand, others suggest that fewer area for containment is better than no containment in data centers that favours the partially contained architectures of HACS and …
