Aerospace Engineering Commons^™

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

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

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 …

Mechanical Properties And Thermal Residual Stresses Of Zrb2-Sic Ceramic Composites For Hypersonic Vehicle Applications, Richard Stadelmann

Electronic Theses and Dissertations

Ultra High Temperature Ceramic (UHTC) ZrB2- 10, 20, 30wt%SiC composites are of high interest for use in hypersonic air-breathing vehicles. In this work, ZrB2- 10, 20, 30wt%SiC UHTC composites were produced by the Spark Plasma Sintering (SPS) technique. After sintering, almost dense ceramics with ~ 5-8% porosity were produced. Their mechanical properties, such as Young’s, shear, and bulk moduli, along with Poisson’s ratio, 4-point bending strength, and single edge V-notched beam (SEVNB) fracture toughness were measured. In addition, in-situ bending experiments under a Raman microscope were performed to determine the piezo-spectroscopic coefficients of SiC Raman active peaks for calculation of …

Materials Selection And Processing Techniques For Small Spacecraft Solar Cell Arrays, Naseem M. Torabi

Theses and Dissertations--Electrical and Computer Engineering

Body mounted germanium substrate solar cell arrays form the faces of many small satellite designs to provide the primary power source on orbit. High efficiency solar cells are made affordable for university satellite programs as triangular devices trimmed from wafer scale solar cells. The smaller cells allow array designs to pack tightly around antenna mounts and payload instruments, giving the board design flexibility. One objective of this work is to investigate the reliability of solar cells attached to FR-4 printed circuit boards. FR-4 circuit boards have significantly higher thermal expansion coefficients and lower thermal conductivities than germanium. This thermal expansion …

Prediction Of Foreign Object Debris/Damage Fod Type Based In Human Factors For Aeronautics Using Logistic Regression Model, David Ricardo Romo

Open Access Theses & Dissertations

Foreign Object Debris/Damage (FOD) has been an issue for military and commercial aircraft manufacturers since the early ages of aviation and aerospace. Currently, aerospace is growing rapidly and the chances of FOD presence are growing as well. One of the principal causes in manufacturing is the human error. The cost associated with human error in commercial and military aircrafts is approximately accountable for 4 billion dollars per year. This problem is currently addressed with prevention programs, elimination techniques, and designation of FOD areas, controlled access, restrictions of personal items entering designated areas, tool accountability, and the use of technology such …

Development And Testing Of An Ignition Physics Test Facility And An Oxygen/Methane Swirl Torch Igniter, Jesus Roberto Flores

Open Access Theses & Dissertations

There are many advantages to LOX/methane propulsion, such as in-situ resource utilization from Mars and the Moon, and simplicity of ground operations due to its non-toxic nature. There exists a lack of fundamental understanding of the ignition physics, and flame characteristics of these propellants when related to rocket propulsion, which has created undesirably long design cycles and flight hardware that is not optimized. Motivated by these issues, a study of the ignition physics of a shear coaxial injector is proposed, in which the flow field dynamics and ignition transients will be observed through a visually accessible combustion chamber. The main …

Trajectory Generation For Stair Ascent Walking Using Rayleigh Oscillator, T. Afzal, Andrew B. Wright, Kamran Iqbal

Journal of the Arkansas Academy of Science

This paper describes a trajectory generation technique for stair-ascent walking. The knee, hip and ankle joint trajectory during stair ascent are generated using mutually coupled, nonlinear oscillators. The parameters of the oscillators are tuned using the harmonic balance method, which converts the nonlinear differential equations to a set of algebraic equations. Fourier analysis of data generated by stair-ascent walking is performed to extract the amplitude and the phase of the dominant frequency components for each joint trajectory. The solution for the oscillator is assumed to be a sinusoidal wave and then by harmonic balance method the parameters of the oscillator …

The Effect Of Sensor Mass, Sensor Location, And Delamination Location Of Different Composite Structures Under Dynamic Loading, Albert Darien Liu

Master's Theses

This study investigated the effect of sensor mass, sensor location, and delamination location of different composite structures under dynamic loading. The study pertains to research of the use of accelerometers and dynamic response as a cost-effective and reliable method of structural health monitoring in composite structures. The composite structures in this research included carbon fiber plates, carbon fiber-foam sandwich panels, and carbon-fiber honeycomb sandwich panels. The composite structures were manufactured with the use of a Tetrahedron MTP-8 heat press. All work was conducted in the Cal Poly Aerospace Structures/Composites Laboratory. Initial delaminations were placed at several locations along the specimen, …

Assessing Safety Culture Within A Flight Training Organization, David Freiwald, Carolina Lenz-Anderson, Erik Baker

Applied Aviation Sciences - Daytona Beach

This study was prompted by a string of aircraft hull losses experienced by a multinational, multi-campus flight training organization. A mixed methods study was conducted to study the attitudes and perceptions of the operations and management staff at this flight training organization through the use of a survey instrument previously existing and adapted, in order to ensure validity, and interviews with key staff members. Confirmatory factor analysis was performed to identify underlying constructs in the perceptions and attitudes of the staff in order to identify beliefs that may signify a flight training organization is at risk. An analysis was conducted …

Efficient Uncertainty Quantification In Aerospace Analysis And Design, Yi Zhang

Doctoral Dissertations

"The main purpose of this study is to apply a computationally efficient uncertainty quantification approach, Non-Intrusive Polynomial Chaos (NIPC) based stochastic expansions, to robust aerospace analysis and design under mixed (aleatory and epistemic) uncertainties and demonstrate this technique on model problems and robust aerodynamic optimization. The proposed optimization approach utilizes stochastic response surfaces obtained with NIPC methods to approximate the objective function and the constraints in the optimization formulation. The objective function includes the stochastic measures which are minimized simultaneously to ensure the robustness of the final design to both aleatory and epistemic uncertainties. For model problems with mixed uncertainties, …

Development Of A Master Of Software Assurance Reference Curriculum, Andrew J. Kornecki, James Mcdonald, Julia H. Allen, Mark Ardis, Nancy Mead, Richard Linger, Thomas B. Hilburn

Department of Electrical Engineering and Computer Science - Daytona Beach

The Next Generation Air Traffic Management system (NextGen) is a blueprint of the future National Airspace System. Supporting NextGen is a nation-wide Aviation Simulation Network (ASN), which allows integration of a variety of real-time simulations to facilitate development and validation of the NextGen software by simulating a wide range of operational scenarios. The ASN system is an environment, including both simulated and human-in-the-loop real-life components (pilots and air traffic controllers).Real Time Distributed Simulation (RTDS) developed at Embry-Riddle Aeronautical University, a suite of applications providing low and medium fidelity en-route simulation capabilities, is one of the simulations contributing to the ASN. …

Fault Tree Analysis For Safety/Security Verification In Aviation Software, Andrew J. Kornecki, Mingye Liu

Department of Electrical Engineering and Computer Science - Daytona Beach

The Next Generation Air Traffic Management system (NextGen) is a blueprint of the future National Airspace System. Supporting NextGen is a nation-wide Aviation Simulation Network (ASN), which allows integration of a variety of real-time simulations to facilitate development and validation of the NextGen software by simulating a wide range of operational scenarios. The ASN system is an environment, including both simulated and human-in-the-loop real-life components (pilots and air traffic controllers).Real Time Distributed Simulation (RTDS) developed at Embry-Riddle Aeronautical University, a suite of applications providing low and medium fidelity en-route simulation capabilities, is one of the simulations contributing to the ASN. …

A Pulsed Jet For Generation Of Turbulent Spots In A Mach 6 Boundary Layer, Andrew Daniel Abney

Open Access Theses

Hypersonic vehicles operate in an environment with a high level of boundary-layer pressure fluctuations. The largest of these fluctuations are due to the intermittent passage of turbulent spots within the transition region, and can be sufficiently large to affect internal components of the vehicle. In order to better predict these flow variations, a turbulent spot model could be used. The boundary layer on the Boeing/ AFOSR Mach 6 Quiet Tunnel nozzle-wall provided a convenient location for studying the statistical properties of turbulent spots in a hypersonic boundary layer, including growth rates, convection velocities, and pressure-fluctuation intensities. A valve system was …

Assessing Variability In Microstructural Influence On Fatigue Crack Growth Behavior, Matthew James Durbin

Open Access Theses

The effect of microstructural variability has long been recognized as a major contributing factor in the scatter of published fatigue data. It is also acknowledged that these effects are generally more prevalent for short cracks and in the threshold region. A number of models exist to explain individual microstructural effects such as grain boundary influence, grain cluster, average grain size, porosity etc. It is the aim of the Aeronautics and Astronautics Fatigue Lab to develop an encompassing model that accurately predicts these effects.

In order to develop this model a range of material data will be required to inform and …

Size And Rate Effects On Mechanical Behavior Of Ultra High Performance Concrete, Boon Him Lim

Open Access Theses

Cor-Tuf, broadly characterize as a reactive powder concrete is a type of cementitious material. Cementitious materials have been observed to exhibit a strain-rate dependent mechanical behavior. The mechanical behavior of cementitious materials can also depend significantly on specimen sizes. Therefore it is crucial to determine the behavior of Cor-Tuf with different specimen sizes for high-rate applications. For this purpose, split Hopkinson pressure bar (SHPB), also known as Kolsky bar was utilized to determine the dynamic behavior of Cor-Tuf for different specimen sizes under uniaxial dynamic compression loading at different strain rates. It was observed that as strain rate increases the …

Platform Design For Fleet-Level Efficiency Under Uncertain Demand: Application For Military Cargo Aircraft And Fleet, Jung Hoon Choi

Open Access Theses

The aircraft system's role in the United Stated Air Force is crucial. For the U.S. Air Force to maintain its air superiority in the world, the constant maintenance, upgrade, and acquisition of the systems must follow. As the cost of fuel rises and with the recent budget situation, the emphasis is on both running the Air Force fleet more efficiently and acquiring the platform that can reduce the fleet level operating cost and the fuel usage and yet brings same capabilities. The approach presented in the thesis combines approaches from multidisciplinary design optimization and operations research to improve energy efficiency-related …

International Standardization Compliance In Aviation, Tyler Brogden Spence

Open Access Theses

The commercial aviation industry is global in the sense that passengers travel around the world from destination to destination. It is also global in that the states of the world (countries) regulate the industry domestically and internationally. There is a unique stage where the world comes together to promote aviation, discuss ideas and establish international standards. This stage is the International Civil Aviation Organization (ICAO). The 191 current member states signed treaties acknowledging their commitment to abiding by the standards and practices established by ICAO. No state is 100 percent compliant with international standards, however, and the purpose of this …

Adaptive Nonlinear Control For Autonomous Ground Vehicles, William Spencer Black

Open Access Theses

We present the background and motivation for ground vehicle autonomy, and focus on uses for space-exploration. Using a simple design example of an autonomous ground vehicle we derive the equations of motion. After providing the mathematical background for nonlinear systems and control we present two common methods for exactly linearizing nonlinear systems, feedback linearization and backstepping. We use these in combination with three adaptive control methods: model reference adaptive control, adaptive sliding mode control, and extremum-seeking model reference adaptive control. We show the performances of each combination through several simulation results. We then consider disturbances in the system, and design …

Development And Benefit Analysis Of A Sector Design Algorithm For Terminal Dynamic Airspace Configuration, Vincent Joseph Sciandra

Open Access Theses

The National Airspace System (NAS) is the vast network of systems enabling safe and efficient air travel in the United States. It consists of a set of static sectors, each controlled by one or more air traffic controllers. Air traffic control is tasked with ensuring that all flights can depart and arrive on time and in a safe and efficient matter. However, skyrocketing demand will only increase the stress on an already inefficient system, causing massive delays. The current, static configuration of the NAS cannot possibly handle the future demand on the system safely and efficiently, especially since it is …