Aerospace Engineering Commons^™

Optimal Attitude Control Of Agile Spacecraft Using Combined Reaction Wheel And Control Moment Gyroscope Arrays, Cole C. Doupe

Theses and Dissertations

This dissertation explores the benefits of combined control moment gyroscope (CMG) and reaction wheel array (RWA) actuation for agile spacecraft. Agile spacecraft are capable of slewing to multiple targets in minimum time. CMGs provide the largest torque capability of current momentum exchange actuation devices but also introduce singularity events in operation. RWAs produce less torque capability than CMGs but can achieve greater pointing accuracy. In this research, a combined RWA and CMG (RWCMG) system is evaluated using analytical simulations and hardware experiments. A closed-loop control scheme is developed which takes advantage of the strengths of each actuator set.The CMGs perform …

Optimal Uas Assignments And Trajectories For Persistent Surveillance And Data Collection From A Wireless Sensor Network, Nidal M. Jodeh

Theses and Dissertations

This research developed a method for multiple Unmanned Aircraft Systems (UAS) to efficiently collect data from a Wireless Sensor Networks (WSN). WSN are composed of any number of fixed, ground-based sensors that collect and upload local environmental data to over flying UAS. The three-step method first uniquely assigns aircraft to specific sensors on the ground. Second, an efficient flight path is calculated to minimize the aircraft flight time required to verify their assigned sensors. Finally, sensors reporting relatively higher rates of local environmental activity are re-assigned to dedicated aircraft tasked with concentrating on only those sensors. This work was sponsored …

Creep Of Hi-Nicalon™ S Ceramic Fiber Tows At 800°C In Air And In Silicic Acid-Saturated Steam, Scott J. Robertson

Theses and Dissertations

A facility was demonstrated that successfully resolved problems highlighted by previous attempts to study SiC fibers in steam. Monotonic tension and creep tests were conducted to characterize the fibers. The tensile strength of the fibers showed little dependence on applied stress rate, indicating a resistance to environmentally assisted crack growth. Climb-controlled diffusion in air and grain boundary sliding in silicic acid-saturated steam were the dominant damage mechanisms. Silicic acid-saturated steam had a degrading effect on the mechanical performance of the fibers, but much less than unsaturated steam environments. The Monkman-Grant relationship was demonstrated for Hi-NicalonTM S fibers and may be …

120 Seconds, Kari Sandouka

Faculty Work Comprehensive List

Posting about living with impact from In All Things - an online hub committed to the claim that the life, death, and resurrection of Jesus Christ has implications for the entire world.

http://inallthings.org/120-seconds/

Momentum Of Particles From Time-Of-Flight Measurements, Joseph Best

Senior Theses

In order to find the momentum of particles from time of flight measurements, I used a program called Geant4 to simulate experiments. I made a simple two detector setup, and I recreated a real world experiment. I spent a lot of time learning to code in C++ so I could use Geant4 correctly. I simulated these experiments shooting electrons, muons, and pions through the geometry and measured the time at two points in their flight. Subtracting the second time from the first gave me the time of flight distribution for each particle. I used ROOT to draw histograms of the …

Drones In Logistics: A Feasible Future Or A Waste Of Effort, Andrew Lotz

Honors Projects

On December 1^st, 2013 news around the world was filled with headlines about E- Commerce website Amazon.com. CEO of Amazon Jeff Bezos announced to the world that Amazon was designing a drone delivery program called Amazon Air that could deliver packages to customers in just 30 minutes. Consumers were all too excited for the program to launch while many business and air traffic savvy people were highly skeptical. Now two years later research to look back at the feasibility of drone flight and whether investment into the technology is worth it for small deliveries straight to customers is …

Dielectric Characteristics Of Microstructural Changes And Property Evolution In Engineered Materials, Jallisa Janet Clifford

Theses and Dissertations

Heterogeneous materials are increasingly used in a wide range of applications such as aerospace, civil infrastructure, fuel cells and many others. The ability to take properties from two or more materials to create a material with properties engineered to specific needs is always very attractive. Hence engineered materials are evolving into more complex formulations or heterogeneities in multiple disciplines. Design of microstructure at multiple scales controls the global functional properties of these materials and their structures. However, local microstructural changes do not directly cause a proportional change to the global properties (such as strength and stiffness). Instead, local changes follow …

Tool Material Degradation Due To Friction Stir Welding Of Aluminum Alloys, Corbin T. Collier

Theses and Dissertations

The purpose of this study is to investigate the friction stir welding (FSW) tool material degradation factors due variation in tool material properties and the effect of an aluminum diffusion wear mechanism on three different FSW tool material when exposed to various welding temperatures and times. The degradation factors are essential to FSW tool design due to the effect of the tool pin and shoulders on the heat generation and material flow which directly correlated to the weld quality created during the FSW process. For this investigation the three materials used are H13, TSP1, and MP159. To determine degradation factors …

Multi-Rotor Unmanned Aerial Vehicle, Jacob Dean, James Mixter, Jordan Barr

Honors Theses

An open-source Unmanned Aerial Vehicle (UAV) capable of performing at the same capacity as many top commercially available multi-rotor vehicles is developed. The system allows users unfamiliar with multi-rotor vehicles to achieve flight and land safely, while also serving as a flexible foundation for other UAV projects and opening the door to features that are not currently available. Applications of drone technology are explored.

The Development Of An Autonomous Proximity Operations Demonstration System, Spencer Watza

Honors Theses

An Autonomous Proximity Operations Demonstration System is being developed to evaluate low cost hardware for aerial robotics and proximity operations in a GPS denied environment. This report highlights the design work and initial prototypes that have been finished along the project goals. The preliminary and detailed design of the vehicle has been completed and initial prototypes constructed. The demonstration system is a multirotor flight vehicle using a hex configuration (6 rotors). The vehicle carries onboard sensing and computational equipment to perform the mission weighing in at 28 pounds. The primary sensor chosen is the Microsoft Kinect™ to perform visual sensing …

The Aerodynamic And Dynamic Loading Of A Slender Structure By An Impacting Tornado-Like Vortex: The Influence Of Relative Vortex-To-Structure Size On Structural Loading, Matthew Nicholas Strasser

Graduate Theses and Dissertations

Structural loading produced by an impacting vortex is a hazardous phenomenon that is encountered in numerous applications ranging from the destruction of residences by tornados to the chopping of tip vortices by rotors. Adequate design of structures to resist vortex-induced structural loading necessitates study of the phenomenon that control the structural loading produced by an impacting vortex. This body of work extends the current knowledge base of vortex-structure interaction by evaluating the influence of the relative vortex-to-structure size on the structural loading that the vortex produces. A computer model is utilized to directly simulate the two-dimensional impact of an impinging …

Energy And Water Impacts Of Data Center Cooling Systems: A Triple Bottom Line Assessment For Facility Design, Marianna Louisa Vallejo

Mechanical and Aerospace Engineering Dissertations - Archive

Increasingly, society is being transferred to a dependence upon electronic technologies and networked systems, usually accessed via the internet. Physically, these systems reside within clusters of servers and storage banks which are collectively housed and maintained in data center facilities. In order for a data center to function properly, the environment must be tightly controlled to ensure maximum reliability of the electronic hardware components. Any method of controlling the environment has a cost, either in capital or in resources, and therefore becomes an issue for the sustainability of a building or complex. Currently data centers are one of the largest …

Material Changes Of Bone Following Ishcemia Of The Immature Femoral Head, Olumide O. Aruwajoye

Mechanical and Aerospace Engineering Dissertations - Archive

Legg-Calvé-Perthes disease (LCPD) is a childhood hip disorder resulting from the loss of blood flow to the femoral head. In severe cases of the disease, the femoral head can develop a flattening deformity; additionally, if the disease is diagnosed at a later stage, it leaves most patients to develop early osteoarthritis of the hip. Due to a lack of pathological specimen from patients, an experimental piglet model of femoral head ischemia was developed. The model closely follows the radiographic changes seen in LCPD patients, where there is subchondral fracture, resorption, and a flattening deformity of the femoral head. After ischemia, …

Development Of A Methodology And Sample Preparation To Evaluate Reliability Of Oil Cooled Data Center, Venkata Naga Indu Sravani Kota

Mechanical and Aerospace Engineering Theses - Archive

Liquid immersion cooling is not a new concept which is slowly emerging as an alternative solution to conventional chilled air cooling systems for data centers. The main idea is to build a body of knowledge to help industry make more informed regarding mechanical reliability of IT equipment in mineral oil immersed systems. The goal is to develop a testing procedure for evaluating the reliability of electronic packages and components when immersed in mineral oil. PCB’s, chip packages, passive components like capacitors, inductors, resistors, diodes, cables and wiring form the most important parts of a server used in data centers. The …

Neural Network Modeling And Control Of Data Center, Nachiket Rajendra Kansara

Mechanical and Aerospace Engineering Theses - Archive

Data Center has become a definitive element of Modern IT infrastructure. With the development of high performance computing architectures and equipment, data centers consume large amount of electricity. Due to low Demand/Supply ratio of electricity production there is need to develop ways to reduce power footprint. Many researchers are working on approaches to resolve problems related to en- ergy usage of Data Center. One of these approaches is to develop a model-based control system that would control data centers in efficient way to reduce power footprint. Computational Fluid Dynamic (CFD) has been used to model the dynamic and complex environment …

Impact Of Layer Thickness Of Qfn Package Mounted Printed Circuit Boards During Drop Testing, Sayalee Pradeep Sabne

Mechanical and Aerospace Engineering Theses - Archive

In past studies, it was established that board level reliability of the packages depends mainly upon the design of the package and the soldering technology used for mounting the components. There are many methods to test the reliability, such as temperature cycling test, bend test, power cycling, etc. which have been studied and practiced. We need to consider the failure rate and failure mechanism both, to understand how specific loading conditions affect the failure of an assembly. In this study, PCB’s with variable thicknesses and QFN package mountings are subjected to drop test. It has been observed previously that the …

Fabrication And Characterization Of Low-Density Polymeric Materials With 3d Microstructures, Hakan Arslan

Mechanical and Aerospace Engineering Theses - Archive

Low-density polymeric materials with octet-truss and quad-truss 3D microstructures were studied. The materials with 3D microstructures were created using digital light processing technology with polyethylene glycol (PEG). The mechanical properties of the materials with different relative densities were characterized in air and water. The experimental results were also compared and analyzed with the results from simulation studies. This work reveals that the material with octet-truss microstructures stand at least three times higher deformation than the materials with quad-truss microstructures. The polymeric material with internal 3D microstructures also shows a higher water absorption rate than the same material without internal microstructures.

Non Thermal Reliability Considerations For Oil Cooled Data Centers And Its Serviceability, Sahithi Reddy Nagilla

Mechanical and Aerospace Engineering Theses - Archive

The interest in Oil immersion cooling is increasing day by day which can be attributed to the recent research that shows the potential of its performance when compared to other techniques that add a little more expenses to the organization. Even though the performance of oil immersion cooling has its own capabilities and advantages, this technique is not widely adopted and there is limited published information regarding the important aspects of the design of the system. This paper presents the non-thermal aspects of oil immersion cooling and explains the chemistry of mineral oil and the factors that affect its performance. …

Quantitative Evaluation Of A Thrust Vector Controlled Transport At The Conceptual Design Phase, Vincent Patrick Ricketts

Mechanical and Aerospace Engineering Theses - Archive

The impetus to innovate, to push the bounds and break the molds of evolutionary design trends, often comes from competition but sometimes requires catalytic political legislature. For this research endeavor, the ‘catalyzing legislation’ comes in response to the rise in cost of fossil fuels and the request put forth by NASA on aircraft manufacturers to show reduced aircraft fuel consumption of +60% within 30 years. This necessitates that novel technologies be considered to achieve these values of improved performance. One such technology is thrust vector control (TVC). The beneficial characteristic of thrust vector control technology applied to the traditional tail-aft …

Thermal Analysis Of Disk Brake In Order To Study The Brake Fluid Vaporization Phenomenon Of A Formula Sae Car, Anurag Dey

Mechanical and Aerospace Engineering Theses - Archive

The brake system is inarguable one of the most critical aspect of a vehicle safety. It has always been the major concern for design engineers to develop a system that gives a steady performance with respect to time. In order to achieve that feat, one of the most common problems that arises in maintaining a brake is the problem of brake fluid vaporization. Brake fluids, being hygroscopic in nature, absorb moisture over a period of time. It is one of the prime reasons for reducing the longevity of brake fluid volume inside the brake caliper as the boiling point of …