Assessment Of The Mechanical Integrity Of Cu/Low-K Dielectric In A Flip Chip Package,
2012
University of Texas at Arlington
Assessment Of The Mechanical Integrity Of Cu/Low-K Dielectric In A Flip Chip Package, Thiagarajan Raman
Mechanical and Aerospace Engineering Theses - Archive
Miniaturization and more recently convergence have been driving the industry since the invention of the transistor and integrated circuit (IC). Though the gate delay has decreased with transistor scaling, the increase in the resistive capacitive (RC) interconnect delay due to shrinking interconnect dimensions has become a serious concern for the development of future-generation electronics. To reduce the delay due to resistance R, a major technology change was the replacement of Aluminum (Al) with Copper (Cu) interconnect layers in the BEoL (Back-end-of-line). Recently, some investigators have suggested using low-k dielectric (having dielectric constant less than 4) instead of SiO2 (k= 3.9) …
Numerical Study Of Sidewall Filling For Gas-Fed Pulse Detonation Engines,
2012
University of Texas at Arlington
Numerical Study Of Sidewall Filling For Gas-Fed Pulse Detonation Engines, Wunnarat Rongrat
Mechanical and Aerospace Engineering Theses - Archive
Pulse detonation engines for aerospace propulsion are required to operate at 50-100 Hz meaning that each pulse is 10-20 ms long. Filling of the engine and the related purging process become dominant due to their long duration compared to ignition and detonation wave propagation. This study uses ANSYS FLUENT to investigate the filling of a 1 m long tube with an internal diameter of 100 mm. Six different configurations were investigated with an endwall port and various sidewall arrangements, including stagger and inclination. A stoichiometric mixture of gaseous octane and air at STP was used to ll the tube at …
Thermal Analysis Of High End Servers Based On Development Of Detail Model And Experiments,
2012
University of Texas at Arlington
Thermal Analysis Of High End Servers Based On Development Of Detail Model And Experiments, Shreyas Sampath
Mechanical and Aerospace Engineering Theses - Archive
Thermal management of an efficient data center can be primarily dictated by efficient servers. Continued increase in power density and power dissipation of high end processors, thermal analysis and management has made it strategically important in the challenge of advanced thermal solutions. Present day CFD software provides powerful tools to create very accurate fluid and heat transfer solutions. Validation of a detailed model of a server in CFD corresponds to accurate flow and temperature models and these detailed server models are the foundational blocks for accurate data center thermal management solutions. In this research, an experimental study of the thermal …
New Detonation Concepts For Propulsion And Power Generation,
2012
University of Texas at Arlington
New Detonation Concepts For Propulsion And Power Generation, Eric Braun
Mechanical and Aerospace Engineering Dissertations - Archive
A series of related analytical and experimental studies are focused on utilizing detonations for emerging propulsion and power generation devices. An understanding of the physical and thermodynamic processes for this unsteady thermodynamic cycle has taken over 100 years to develop. An overview of the thermodynamic processes and development history is provided.Thermodynamic cycle analysis of detonation-based systems has often been studied using surrogate models. A real gas model is used for a thermal efficiency prediction of a detonation wave based on the work and heat specified by process path diagrams and a control volume analysis. A combined first and second law …
Hygrothermally Stable Laminated Composites For Optimal Extension Twist Coupling In Closed Cell Configuration,
2012
University of Texas at Arlington
Hygrothermally Stable Laminated Composites For Optimal Extension Twist Coupling In Closed Cell Configuration, Sean Muder
Mechanical and Aerospace Engineering Theses - Archive
An optimization routine utilizing the sequential quadratic programming method is used to develop laminates that are hygrothermally stable in flat-strip configuration and are optimal for extension twist coupling in closed cell configuration. The performance of the laminates obtained from the optimization in terms of the level of extension twist coupling and hygrothermal stability are evaluated and compared to laminates from a previous routine. A parametric study is conducted to illustrate the relationships between the geometric dimensions of a representative closed cell section and the level of extension twist coupling. Results from the parametric study suggested a more practical optimization approach …
Design, Calibration And Testing Of A Force Balance For A Hypersonic Shock Tunnel,
2012
University of Texas at Arlington
Design, Calibration And Testing Of A Force Balance For A Hypersonic Shock Tunnel, Pravin Vadassery
Mechanical and Aerospace Engineering Theses - Archive
The forces acting on a flight vehicle are critical for determining its performance. Of particular interest is the hypersonic regime. Force measurements are much more complex in hypersonic flows, where those speeds are simulated in shock tunnels. A force balance for such facilities contains sensitive gages that measure stress waves and ultimately determine the different components of force acting on the model. An external force balance was designed and fabricated for the UTA Hypersonic shock tunnel to measure drag at Mach 10. Static and dynamic calibrations were performed to find the transfer function of the system. Forces were recovered using …
Guidance And Control Of Unmanned Airships For Waypoint Navigation In The Presence Of Wind,
2012
University of Texas at Arlington
Guidance And Control Of Unmanned Airships For Waypoint Navigation In The Presence Of Wind, Ghassan M. Atmeh
Mechanical and Aerospace Engineering Theses - Archive
Airships are a specific class of Lighter-Than-Air (LTA) vehicles. These vehicles achieve lift mainly through buoyancy; the usually ellipsoidal shaped hull contains a lifting gas such as helium, which produces the required lift though air displacement. Due to this method of operation an airship has the ability to conduct low-power hover, which makes it ideal for applications requiring hovering over long periods of time such as surveillance, terrain mapping, meteorology and GPS. In such applications the conventional fixed wing unmanned aircraft is less suitable. The work presented in this thesis deals with designing a controller that is capable of navigating …
Heat Transfer Enhancement In A Rectangular Channel Using Vortex Generator In A Laminar Flow,
2012
University of Texas at Arlington
Heat Transfer Enhancement In A Rectangular Channel Using Vortex Generator In A Laminar Flow, Ninad C. Maniar
Mechanical and Aerospace Engineering Theses - Archive
Enhancement of heat transfer through various means has been an intense area of research for many years. There are numerous applications where high performance heat exchange is desired. The cooling of electronics, such as microprocessors, is one example. The recent rise in the studies of heat exchange enhancement techniques has also lead to efficient and compact heat exchangers. This research involves the numerical analysis of heat exchange enhancement in a rectangular channel using different types of longitudinal vortex generators (LVG) for a laminar flow. A computational fluid dynamics software package was used to compute the 3-D steady viscous flows with …
Cfd Analysis Of Direct Evaporative Cooling Zone Of Air-Side Economizer For Containerized Data Center,
2012
University of Texas at Arlington
Cfd Analysis Of Direct Evaporative Cooling Zone Of Air-Side Economizer For Containerized Data Center, Niket Shah
Mechanical and Aerospace Engineering Theses - Archive
Conventional data centers are extremely large buildings that have complex power distribution and cooling systems. These traditional brick and mortar data centers employ relatively expensive cooling systems and are inefficient. It has in turn led to an increase in construction and operational costs. Jonathan Koomey, Ph.D. of Lawrence Berkeley National Laboratory estimated that worldwide data center power consumption was 152.5 Billion kWh in 2005. In 2007, the US EPA estimated that servers and data centers, “consumed about 61 billion kilowatt-hours (kWh) in 2006 (1.5 percent of total U.S. electricity consumption) for a total electricity cost of about $4.5 billion. These …
Surface Measurements And Predictions Of Full-Coverage Film Cooling,
2012
University of Central Florida
Surface Measurements And Predictions Of Full-Coverage Film Cooling, Gregory Natsui
Electronic Theses and Dissertations
Full-coverage film cooling is investigated both experimentally and numerically. First, surface measurements local of adiabatic film cooling effectiveness and heat transfer augmentation for four different arrays are described. Reported next is a comparison between two very common turbulence models, Realizable k-ε and SST k-ω, and their ability to predict local film cooling effectiveness throughout a full-coverage array. The objective of the experimental study is the quantification of local heat transfer augmentation and adiabatic film cooling effectiveness for four surfaces cooled by large, both in hole count and in non-dimensional spacing, arrays of film cooling holes. The four arrays are of …
Agglomeration, Evaporation And Morphological Changes In Droplets With Nanosilica And Nanoalumina Suspensions In An Acoustic Field,
2012
University of Central Florida
Agglomeration, Evaporation And Morphological Changes In Droplets With Nanosilica And Nanoalumina Suspensions In An Acoustic Field, Erick Tijerino
Electronic Theses and Dissertations
Acoustic levitation permits the study of droplet dynamics without the effects of surface interactions present in other techniques such as pendant droplet methods. Despite the complexities of the interactions of the acoustic field with the suspended droplet, acoustic levitation provides distinct advantages of controlling morphology of droplets with nanosuspensions post precipitation. Droplet morphology is controlled by vaporization, deformation and agglomeration of nanoparticles, and therefore their respective timescales are important to control the final shape. The balance of forces acting on the droplet, such as the acoustic pressure and surface tension, determine the geometry of the levitated droplet. Thus, the morphology …
Investigation Of Instabilities Affecting Detonations: Improving The Resolution Using Block-Structured Adaptive Mesh Refinement,
2012
University of Texas at Arlington
Investigation Of Instabilities Affecting Detonations: Improving The Resolution Using Block-Structured Adaptive Mesh Refinement, Prashaanth Ravindran
Mechanical and Aerospace Engineering Dissertations - Archive
The unstable nature of detonation waves is a result of the critical relationship between the hydrodynamic shock and the chemical reactions sustaining the shock. A perturbative analysis of the critical point is quite challenging due to the multiple spatio-temporal scales involved along with the non-linear nature of the shock-reaction mechanism. The author's research attempts to provide detailed resolution of the instabilities at the shock front. Another key aspect of the present research is to develop an understanding of the causality between the non-linear dynamics of the front and the eventual breakdown of the sub-structures. An accurate numerical simulation of detonation …
Thrust Vector Control Of An Upper-Stage Rocket With Multiple Propellant Slosh Modes,
2012
Embry-Riddle Aeronautical University - Daytona Beach
Thrust Vector Control Of An Upper-Stage Rocket With Multiple Propellant Slosh Modes, Mahmut Reyhanoglu, Jaime Rubio Hervas
Physical Sciences - Daytona Beach
“The thrust vector control problem for an upper-stage rocket with propellant slosh dynamics is considered. The control inputs are defined by the gimbal deflection angle of a main engine and a pitching moment about the center of mass of the spacecraft. The rocket acceleration due to the main engine thrust is assumed to be large enough so that surface tension forces do not significantly affect the propellant motion during main engine burns. A multi-mass-spring model of the sloshing fuel is introduced to represent the prominent sloshing modes. A nonlinear feedback controller is designed to control the translational velocity vector and …
Experimental Investigation Of Transonic Shock Oscillations On Naca 0018 At Incidence,
2012
University of Mississippi
Experimental Investigation Of Transonic Shock Oscillations On Naca 0018 At Incidence, Christopher Allen Farrell
Electronic Theses and Dissertations
A NACA 0018 airfoil model with a 3-inch chord was mounted into the trisonic wind tunnel at the National Center for Physical Acoustics at the University of Mississippi. Tunnel runs were conducted with the angle of incidence increasing from 0 degrees to 6 degrees at 1 degree increments, while the Mach number was held steady at 0.73. High-speed schlieren images were recorded at a sample rate of 4,000 Hz. A Matlab code was developed to display the spatial power spectral density distribution in the region of the shock. This code calculated the frequency spectrum at regular points along the range …
Evaluation Of Niobium As Candidate Electrode Material For Dc High Voltage Photoelectron Guns,
2012
Old Dominion University
Evaluation Of Niobium As Candidate Electrode Material For Dc High Voltage Photoelectron Guns, Mahzad Bastaninejad, Md. Abdulla Mohamed, Abdelmageed Elmustafa, P. Adderley, J. Clark, S. Covert, J. Hansknecht, C. Hernandez-Garcia, M. Poelker, R. Mammei, K. Surles-Law, P. Williams
Mechanical & Aerospace Engineering Faculty Publications
The field emission characteristics of niobium electrodes were compared to those of stainless steel electrodes using a DC high voltage field emission test apparatus. A total of eight electrodes were evaluated: two 304 stainless steel electrodes polished to mirrorlike finish with diamond grit and six niobium electrodes (two single-crystal, two large-grain, and two fine-grain) that were chemically polished using a buffered-chemical acid solution. Upon the first application of high voltage, the best large-grain and single-crystal niobium electrodes performed better than the best stainless steel electrodes, exhibiting less field emission at comparable voltage and field strength. In all cases, field emission …
Design And Development Of Ionic Liquid Dual-Mode Spacecraft Propellants,
2012
Missouri University of Science and Technology
Design And Development Of Ionic Liquid Dual-Mode Spacecraft Propellants, Steven P. Berg
Masters Theses
"Energetic ionic liquids capable of dual-mode chemical monopropellant or bipropellant and electric electrospray rocket propulsion are investigated. Following an extensive literature review, ionic liquids [Bmim][dca], [Bmim][NO₃], and [Emim][EtSO₄] are selected for study since their physical properties align well with the current state-of-the-art in chemical and electrospray propellants. Simulations show that these liquids will not be useful for monopropellant propulsion due to the prediction of solid carbon formation in the exhaust and performance 13-23% below that of hydrazine. Considering these ionic liquids as a fuel component in a binary monopropellant mixture with hydroxyl ammonium nitrate shows 1-4% improved specific impulse over …
Numerical Investigation Of Second-Law Characteristics Of Ramjet Throttling,
2012
Missouri University of Science and Technology
Numerical Investigation Of Second-Law Characteristics Of Ramjet Throttling, Jonathan Albert Sheldon
Masters Theses
"A numerical study of a generic axisymmetric ramjet operating at conditions corresponding to flight Mach 3.0 and a standard altitude of 10 km is presented. The study includes both modeling of steady-state flowfields in the ramjet as well as transient throttling maneuvers in which the throttle is decreased or increased from maximum or minimum throttle positions. The results presented here focus on entropy generation and performance characteristics. Combustion-generated exothermic heat release is modeled using simple volumetric energy addition to the flow within a defined heat release zone. The study utilizes two levels of wall boundary modeling, corresponding respectively to inviscid …
Analysis Of Optimal Control Derivations For Aerial Defense,
2012
Missouri University of Science and Technology
Analysis Of Optimal Control Derivations For Aerial Defense, Andrew John Friedrichs
Masters Theses
"Optimal control will be used to derive four guidance laws for the purpose of defending an aircraft from incoming missiles. The dynamics of the defending missile, and the overall engagement are used in these derivations. They are evaluated first in two degrees of freedom, then in six degrees. The guidance objective is to move a defending missile between the aircraft and the attacker. Optimal control is used to derive different commanded accelerations. Utilizing small changes in the cost functions, four applications will be derived. Triangle Guidance is used for inspiration, and initially a direct approach is attempted. In the course …
A Study Of The Integration Of An Inlet Noise Radiation Code With The Aircraft Noise Prediction Program,
2012
Missouri University of Science and Technology
A Study Of The Integration Of An Inlet Noise Radiation Code With The Aircraft Noise Prediction Program, Devin Kyle Boyle
Masters Theses
"A numerical method has been developed in order to study the effect of turbofan inlet acoustic treatment on the resulting cumulative noise heard by observers on the ground. The approach to creating the tool was to combine the capabilities of the NASA-developed Aircraft Noise Prediction Program (ANOPP) with the fan noise propagation and radiation code developed at Missouri University of Science and Technology. ANOPP can be used to predict the noise metrics resulting from a typical commercial aircraft with turbofan engines on several different flight profiles, including takeoff, approach/landing and a steady (constant altitude/airspeed) flyover. These capabilities are valuable for …
Studies Of Inductive Plasmas And Their Application To Theta-Pinch Devices Via Numerical Modeling,
2012
Missouri University of Science and Technology
Studies Of Inductive Plasmas And Their Application To Theta-Pinch Devices Via Numerical Modeling, Warner C. Meeks
Masters Theses
"First, a globally-averaged RF plasma model is used to investigate exit conditions immediately following a RF pre-ionization stage. Analysis shows that reducing pulse duration from 10⁻⁶ to 10⁻⁷ seconds increases peak ion energy fraction by 17% (from 16 to 33%) and doubles final conductivity. Pulse waveforms are square in nature, and ion energy fraction is defined in this work as the percentage of total input energy entrained in ions. Increasing total energy deposition from 5 to 160 mJ increases ion energy fraction from 33% to 58% at a 200 ns pulse duration. This increase is not linear however, showing instead …
