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Articles 661 - 690 of 953

Full-Text Articles in Aerospace Engineering

Numerical Study Of Incompressible Fluid Flow In A Vertically Dropping Pool With And Without End Sill, Vimal Ramanuj Jan 2013

Numerical Study Of Incompressible Fluid Flow In A Vertically Dropping Pool With And Without End Sill, Vimal Ramanuj

Mechanical and Aerospace Engineering Theses - Archive

The study involves numerical analysis of flow field for three different flow regimes taking place in a vertically dropping pool. In general, a vertically dropping flow generates a skimming flow regime with one recirculation zone along with a developing shear layer. The presence of an obstacle (end sill) results in the formation of another recirculation zone downstream of the impinging jet. Based on the nature of these zones, the flow is categorized as napped, periodically oscillatory and skimming. The type of flow regime depends on the flow parameters like velocity and depth of flow which are controlled by Froude number. …


3-D Fracture Study Of The Beol Cu/Low-K Stack To Assess And Mitigate The Cpi Risk During The Reflow Process, Zaeem Baig Jan 2013

3-D Fracture Study Of The Beol Cu/Low-K Stack To Assess And Mitigate The Cpi Risk During The Reflow Process, Zaeem Baig

Mechanical and Aerospace Engineering Theses - Archive

As scaling of components continues, using SiO2 as a dielectric in the Back-End-Of-Line (BEoL) is no longer a viable option and can be replaced with low-k and ultralow-k (ULK) dielectric materials for advanced integrated circuits (IC) packaging solutions. The low-k materials improve performance by reducing parasitic capacitance and crosstalk between adjacent metal lines. However, low-k dielectrics have lower modulus, lower fracture toughness, higher coefficient of thermal expansion (CTE), and poor adhesion as compared to SiO2. Thus, low-k dielectric integration in the contemporary IC packages poses a significant reliability challenge. Delamination along the metal-dielectric interfaces and crack propagation in the dielectric …


A Novel Approach For Two-Dimensional Inclusion/Hole Problems Using The Airy Stress Function Method, Manikandan Madhavan Jan 2013

A Novel Approach For Two-Dimensional Inclusion/Hole Problems Using The Airy Stress Function Method, Manikandan Madhavan

Mechanical and Aerospace Engineering Theses - Archive

This thesis demonstrates the application of the Airy stress function in solving plane elasticity problems. An Airy stress function is determined for two-dimensional infinite plates containing a circular inclusion embedded with a circular hole subjected to tensile loading and the traction and displacement functions for various boundary conditions satisfy the equilibrium and continuity conditions. Mathematica was useful for solving the complex expressions and to calculate the elastic fields for a variety of elastic problems in this study.


Modeling The Dynamic Behavior Of Estrogen Docking Into Its Receptor Using The Multiscale Analysis, Anudeep Palanki Jan 2013

Modeling The Dynamic Behavior Of Estrogen Docking Into Its Receptor Using The Multiscale Analysis, Anudeep Palanki

Mechanical and Aerospace Engineering Theses - Archive

This work models the dynamic behavior of Estrogen docking into its receptor. It lays the foundation for the development of a new theoretical screening technique to identify carcinogens. It is predicted that this year, more than 1 million Americans and more than 10 million people worldwide will be diagnosed with cancer. Only 5 to 10 percent of all cancer cases can be attributed to genetic defects, whereas the remaining 90 to 95 percent have their roots in the environment. It has been suggested that some chemical compounds have a similar structure and properties as natural hormones produced by the human …


Utilization Of Microencapsulated Phase Change Material For The Optimization Of Evaporative Cooling Technology, Jeet Shah Jan 2013

Utilization Of Microencapsulated Phase Change Material For The Optimization Of Evaporative Cooling Technology, Jeet Shah

Mechanical and Aerospace Engineering Theses - Archive

IT equipments are the essential facet of most institutional operations of the advanced world. Modern IT equipments are far more vigorous than older equipments. With increasing density of array of servers and growth of computing power, assessing the cooling requirements has emerged as an aspect of prime importance. Evaporative cooling is a very common cooling technology used in cooling of data centers due to low installation and power costs and simple operation. Phase change materials have been investigated over the years as thermal energy storage for cooling and heating applications. These researches have also investigated encapsulated PCM in different sizes …


Structural Analysis At Aircraft Conceptual Design Stage, Reza Mansouri Jan 2013

Structural Analysis At Aircraft Conceptual Design Stage, Reza Mansouri

Mechanical and Aerospace Engineering Theses - Archive

In the past 50 years, computers have helped by augmenting human efforts with tremendous pace. The aircraft industry is not an exception. Aircraft industry is more than ever dependent on computing because of a high level of complexity and the increasing need for excellence to survive a highly competitive marketplace. Designers choose computers to perform almost every analysis task. But while doing so, existing effective, accurate and easy to use classical analytical methods are often forgotten, which can be very useful especially in the early phases of the aircraft design where concept generation and evaluation demands physical visibility of design …


Numerical Simulations Of Transonic Wingtip, Suparat Chanrith Jan 2013

Numerical Simulations Of Transonic Wingtip, Suparat Chanrith

Mechanical and Aerospace Engineering Theses - Archive

This report presents numerical simulations using ANSYS FLUENT for a NACA 0012 wing both in two- and three-dimensional cases to compare with an experimental data. This comparison also allowed for any wall interference in wind tunnels to be examined. Moreover, the report also presents numerical simulation of a NACA 0012 wingtip. The simulations were conducted at Mach 0.5, 0.7, 0.75, and 0.8 at various chord Reynolds number and the angle of attack of 0, 2, 4, and 5. The numerical andexperimental data were in good agreement for the full wing and the wingtip cases.


Experimental Study On The Effects Of Gaseous Contamination On It Equipment, Rahul Srinivas Raghunathan Jan 2013

Experimental Study On The Effects Of Gaseous Contamination On It Equipment, Rahul Srinivas Raghunathan

Mechanical and Aerospace Engineering Theses - Archive

Every company is trying to reduce their carbon footprint in today's world. The data center industry is no different. To reduce the cooling costs and increase the efficiency, air -side economizers are used. Air-side economizers bring in outside ambient cold air to cool the data center equipment. Through this, we can save on cooling costs. The problem relating to air-side economization is that we have no control over the humidity and contamination. Humidity and contamination go hand in hand, as one influence the other. In the past filters have been used to combat contamination but it has proved to be …


Development Of Foil Thrust Bearing Test Rig, Rohit Harishchandra Yadav Jan 2013

Development Of Foil Thrust Bearing Test Rig, Rohit Harishchandra Yadav

Mechanical and Aerospace Engineering Theses - Archive

Oil lubricated bearings have been widely used in variety of turbo machinery, though it has its own limitations such as thermal degradation of oil over temperature, complicated oil lubrication system and their maintenance. Commercial application of the air foil bearing (AFB) in Microturbomachinery have been acknowledged. Microturbomachinery term is used in applications with shaft power less than 1000KW and shaft diameter less than 100mm. Microturbomachinery has demanded light weighted, compact, extreme temperature and high speed operation. DN number for oil lubricated bearings and rolling element bearings is very less when compared to foil bearings. Absence of external pressurizing and lubricating …


Point Measurement Of Detonation Wave Propagation Using Ion Guage, Nitesh Karpakala Manjunatha Gupta Jan 2013

Point Measurement Of Detonation Wave Propagation Using Ion Guage, Nitesh Karpakala Manjunatha Gupta

Mechanical and Aerospace Engineering Theses - Archive

Accurate measurement of detonation wave velocity is important in the study of detonations. Detonation wave velocity is calculated by the ratio of distance between two transducers which the wave front travels over the propagation time. Conventional methods included transducers placed a few cm apart thereby yielding an average velocity of the wave. A gauge was developed in which the transducers were placed a few mm apart so that an effective point measurement of velocity can be determined. Different types of sensors used in determining the detonation wave velocity included pressure, flame and ion. Of the three, the ion sensor was …


Effect Of Nanoparticle Dispersions In A Binary Nitrate Salt As Thermal Energy Storage Material In Concentrated Solar Power Applications, Bharath Dudda Jan 2013

Effect Of Nanoparticle Dispersions In A Binary Nitrate Salt As Thermal Energy Storage Material In Concentrated Solar Power Applications, Bharath Dudda

Mechanical and Aerospace Engineering Theses - Archive

Despite the huge improvements in the field of solar energy to produce electricity, the high cost of production has been one of the major problems in this field. Concentrated solar power (CSP) uses a number of mirrors to concentrate solar radiant energy onto a single focal point. Electrical power is produced when the concentrated light is converted to heat, which drives a heat engine connected to an electrical power generator. This heat is first stored in a thermal energy storage (TES) and transferred to a heat engine to be converted to electricity and thus TES can provide heat even after …


Utilization Of Molten Nitrate Salt Nanomaterials For Heat Capacity Enhancement In Solar Power Applications, Ramaprasath Devaradjane Jan 2013

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, Vinoth Kumar Dhananjayan Jan 2013

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, Jeongpill Ki Jan 2013

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, Deval Pandya Jan 2013

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, A Paige Carpentier Jan 2013

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, Hardik Parekh Jan 2013

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, Zachary Govier Brush Jan 2013

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, Pawarat Bootpakdeetam Jan 2013

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, Shivakumar Samala Jan 2013

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, Jagath B. Yaddessalage Jan 2013

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, Hakki Erhan Sevil Jan 2013

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, Thanuuj S. Pathapallli Jan 2013

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, …


Thermo-Mechanical Analysis Of Nano-Imprint Lithography, Bhavik C. Patel Jan 2013

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, Marie F.C. Denison Jan 2013

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, Sandesh Gudemane Jan 2013

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, Bharath Nagendran Jan 2013

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, Kasturi Rangan Rajagopalan Jan 2013

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 …


Real Time Temperature Prediction In A Data Center Environment Using An Adaptive Algorithm, Vishok Amar Kumar Jan 2013

Real Time Temperature Prediction In A Data Center Environment Using An Adaptive Algorithm, Vishok Amar Kumar

Mechanical and Aerospace Engineering Theses - Archive

Most organizations around the world rely on information systems to run their operations. Data centers are hence a crucial aspect of most organizational operations to ensure business continuity. Disruption in the working of a system can impair the business largely and hence optimizing the environment in which the servers and storage devises of a data center are housed becomes extremely challenging. Most industries design the data center infrastructure to handle peak load conditions thus ensuring a continual functionality of its hosted environment. However, the cost of maintaining such a system is very high. This gives rise to the need of …


A Computational Model To Characterize Different Flow Regimes For Microscale Re-Entry Satellites, Sudharsan Thiruvenkadam Jan 2013

A Computational Model To Characterize Different Flow Regimes For Microscale Re-Entry Satellites, Sudharsan Thiruvenkadam

Mechanical and Aerospace Engineering Theses - Archive

Atmospheric re-entry vehicles experience different flow regimes during flight due to the change in atmospheric density along the re-entry trajectory. This change in density creates non-equilibrium regions on the order of mean free path, called Knudsen layer. In the design of atmospheric re-entry vehicles, the flux variations near the wall of the re-entry vehicles are of critical importance. Traditional CFD simulations that use Navier-Stokes equations fail to predict the flow in the Knudsen layer. The Direct Simulation Monte Carlo (DSMC) method is accurate for all flow regimes, and correctly models the Knudsen layer but is computationally expensive. The computational cost …