License To Launch: The Regulatory Future Of Commercial Ballistic Travel,
2019
University of Minnesota Law School
License To Launch: The Regulatory Future Of Commercial Ballistic Travel, Jacob Weindling
Minnesota Journal of Law, Science & Technology
No abstract provided.
Gaussian Conditionally Markov Sequences: Theory With Application,
2019
University of New Orleans
Gaussian Conditionally Markov Sequences: Theory With Application, Reza Rezaie
LSU New Orleans Theses and Dissertations
Markov processes have been widely studied and used for modeling problems. A Markov process has two main components (i.e., an evolution law and an initial distribution). Markov processes are not suitable for modeling some problems, for example, the problem of predicting a trajectory with a known destination. Such a problem has three main components: an origin, an evolution law, and a destination. The conditionally Markov (CM) process is a powerful mathematical tool for generalizing the Markov process. One class of CM processes, called $CM_L$, fits the above components of trajectories with a destination. The CM process combines the Markov property …
Stability Of Supersonic Flow With Injection,
2019
Case Western Reserve University
Stability Of Supersonic Flow With Injection, Bryan E. Schmidt
Faculty Scholarship
Gas injection into supersonic flow past a 5-degree half-angle cone is studied with three injected gases: helium, nitrogen, and RC318. Experiments are performed in a Mach 4 Ludwieg tube with nitrogen as the free stream gas. The injector section is shaped to admit a "tuned" injection rate where the displacement created by injection counteracts the effects created by the injector geometry. A high-speed schlieren imaging system with a framing rate of 290 kHz is used to study the instability in the region of flow downstream of injection, referred to as the injection layer. Measurements of wavelength, convective speed, and frequency …
Secondary Electron Yield Measurements Of Carbon Nanotube Forests: Dependence On Morphology And Substrate,
2019
Utah State University
Secondary Electron Yield Measurements Of Carbon Nanotube Forests: Dependence On Morphology And Substrate, Brian Wood, Jordan Lee, Gregory Wilson, T. -C. Shen, Jr Dennison
Journal Articles
Total, secondary, and backscatter electron yield data were taken with beam energies between 15 eV and 30 keV, in conjunction with energy emission data, to determine the extent of suppression of yield caused by carbon nanotube (CNT) forest coatings on substrates. CNT forests can potentially lower substrate yield due to both its inherently low-yield, low-atomic number (Z) carbon composition, and its bundled, high-aspect ratio structure. Rough surfaces, and in particular, surfaces with deep high-aspect-ratio voids, can suppress yields, as the electrons emitted from lower lying surfaces are recaptured by surface protrusions rather than escaping the near-surface region. Yields of multilayered …
Nonlinear Control Of Unmanned Aerial Vehicles With Cable Suspended Payloads,
2019
University of Texas at Arlington
Nonlinear Control Of Unmanned Aerial Vehicles With Cable Suspended Payloads, Ameya Godbole
Mechanical and Aerospace Engineering Dissertations - Archive
The research focuses on the mathematical modeling and control of an unmanned aerial vehicle with cable suspended payload. A comprehensive mathematical model is derived for a quadcopter with a cable suspended payload using the Newton-Euler method and the Euler-Lagrange formulation. These methods assume that the cable is massless and always taut and cannot be used to simulate the cases when the cable is flexible. Hence, an alternative approach to model the flexibility of the cable is presented using Lagrangian mechanics by approximating the cable to be a chain of serially connected links. The motion of the payload induces disturbances on …
Modeling And Simulation Of Contact And Impact Dynamics In Multibody Systems,
2019
University of Texas at Arlington
Modeling And Simulation Of Contact And Impact Dynamics In Multibody Systems, Abhishek Chatterjee
Mechanical and Aerospace Engineering Dissertations - Archive
Contact and impact analyses are an essential part of multibody dynamic simulations. Modeling of contact and impact problems have applications in a wide variety of areas including robotics, earthquake engineering, computer graphics, and manufacturing. Collisions between objects typically take place over surfaces that are represented by a set of points in the operation space, thereby requiring multi-point contact and impact analysis. Analysis of multi-point contact and impact may lead to indeterminate (underdetermined) problems with more number of unknowns (contact forces) than equations. This work pertains to the problem of resolving multi-point contact and impact problems in multibody systems consisting of …
Numerical Simulation Of Biodiesel Synthesis In A Continuous Flow Microreactor And A Porous Media Reactor,
2019
University of Texas at Arlington
Numerical Simulation Of Biodiesel Synthesis In A Continuous Flow Microreactor And A Porous Media Reactor, Terdsak Neadkratoke
Mechanical and Aerospace Engineering Dissertations - Archive
Biodiesel has become an increasingly popular fossil fuel substitute in recent years. Constant attempts are being made to develop new technology that increases the efficiency and yield of biodiesel production units. Numerical simulation can play an integral role in evaluating new reactor designs or optimizing existing ones. Various attempts have been made to develop an accurate computational model that represents biodiesel production. Many computational models for transesterification are based on simplified kinetic models that do not include the effect of saponification. Furthermore, many models assume isothermal conditions and uniform spatial concentrations. Therefore, these models would not be appropriate for evaluating …
Predicting Crack Initiation And Early Crack Growth Behavior Of Pure Nickel Using Surface Topography Analysis,
2019
University of Texas at Arlington
Predicting Crack Initiation And Early Crack Growth Behavior Of Pure Nickel Using Surface Topography Analysis, Jalal Fathi Sola
Mechanical and Aerospace Engineering Dissertations - Archive
Fatigue has long been studied as the most critical loading mode for man-made structures. Despite the advances in material behavior characterization and numerical calculation, many structures unexpectedly fail before their designed life. Most of the studies in crack initiation are solely for describing the material and failure behavior and are not capable of predicting the failure before it starts. In addition, most of the fatigue crack growth models are based on the Paris Model with some modifications, which their application is limited to long crack. This implies that finding new methods which can reliably predict material failure is very important. …
A Numerical Study Of Cavitating Flows Based On Plic-Vof Method For Arbitrary Unstructured Meshes,
2019
University of Texas at Arlington
A Numerical Study Of Cavitating Flows Based On Plic-Vof Method For Arbitrary Unstructured Meshes, Dezhi Dai
Mechanical and Aerospace Engineering Dissertations - Archive
Cavitation appears when local static pressure drops below the water vapor pressure and causes significant impacts on marine propeller blades. The Volume of Fluid (VOF) method, which is also referred to as the Transport Equation-based Model (TEM), has been extensively adopted in the cavitating flow simulations. Piecewise Linear Interface Calculation (PLIC) schemes have been extensively employed in the VOF method for interface capturing in numerical simulations of multiphase flows. Polyhedral unstructured meshes are often adopted due to their geometric flexibility and superiority in gradient calculation. Four analytical interface reconstruction algorithms in the PLIC-VOF method for arbitrary convex polyhedral cells have …
The Effect Of Controlled Nanomaterial Deposition Towards Electrodes For Microbial Fuel Cells And Electrolysis Cells,
2019
University of Texas at Arlington
The Effect Of Controlled Nanomaterial Deposition Towards Electrodes For Microbial Fuel Cells And Electrolysis Cells, Bryan Dennis Steinhoff
Mechanical and Aerospace Engineering Dissertations - Archive
Microbial fuel cells (MFCs) and microbial electrolysis cells (MECs) are relatively new energy harvesting technologies that utilize the bacteria in wastewater or other organic-rich aqueous media to produce either electricity or hydrogen gas, respectively. Given that MFCs and MECs are newer technologies, there has been many works over the past two decades that have provided understanding into how modifying electrode surface chemistry can improve these cells. It has been widely known that increasing the surface functional groups of MFC anodes, either chemically or thermally, causes the cell power density to increase dramatically. Since MFCs and MECs use the same anodes, …
Multi-Variable Optimization To Improve Temperature Uniformity In Burn-In Applications Subjected To Significant Thermal Shadowing,
2019
University of Texas at Arlington
Multi-Variable Optimization To Improve Temperature Uniformity In Burn-In Applications Subjected To Significant Thermal Shadowing, Ajinkya Suhas Mahajan
Mechanical and Aerospace Engineering Theses - Archive
Burn-in test typically employs voltage and/or temperature to accelerate the appearance of latent reliability defects in semiconductor devices. As a result, burn-in becomes a critical step in the parts screening process and is the primary technique to eliminate defective parts in the early phase of the product life. Thermal control in burn-in processes is generally achieved by either active or passive thermal controlling. In an active thermal control, each device has an individual temperature monitoring system to maintain a specific temperature in which the cooling/heating of each socket is controlled by an individual fan or heater. Whereas in passive thermal …
An Exploratory Study On Continuous Wave Laser And High-Speed Camera Combination In Planar Particle Image Velocimetry For Low Speed Flows,
2019
University of Texas at Arlington
An Exploratory Study On Continuous Wave Laser And High-Speed Camera Combination In Planar Particle Image Velocimetry For Low Speed Flows, Bunyamin Gencler
Mechanical and Aerospace Engineering Theses - Archive
This study investigates the feasibility of using continuous wave lasers and high-speed CMOS cameras together in 2D particle image velocimetry (PIV) which is a widely-used non-intrusive method in experimental aerodynamics. In order to validate the setup, laminar and turbulent boundary layers over a flat plate with elliptical leading edge are examined in a low-speed wind tunnel. Before the experiments, the suitability of the elliptical-nose flat plate is determined (i.e. pressure gradient over the surface and separation), and the free-stream conditions (flow velocity and test section turbulence) are measured. To strengthen the validation of the setup, numerical simulations are added to …
Effect Of Sulfur - Porous Carbon Cathode Morphology On The Discharge Process In Lithium-Sulfur Battery,
2019
University of Texas at Arlington
Effect Of Sulfur - Porous Carbon Cathode Morphology On The Discharge Process In Lithium-Sulfur Battery, Sabarinathan Pushparajsubramaniyan
Mechanical and Aerospace Engineering Theses - Archive
In the present era, Lithium-ion (Li-ion) batteries are most commonly used in all electronic devices, but the demand for alternative energy increases rapidly due to the catastrophic climate caused by excess use of fossil fuels in automobiles. Li-ion batteries cannot fully satisfy the need as its theoretical capacity is low, and the cathode cost is high. On the other hand, Lithium-Sulfur (Li-S) battery meets the requirement with the highest theoretical capacity of Sulfur 1672 mAh/g. Lithium anode and Sulfur cathode together form to be having the highest energy density. The highest energy capacity of Sulfur is achieved by the conversion …
Comparative Cfd Analysis Of The Effect Of Air And Liquid Cooling On The Form Factor Of Gpu Server,
2019
University of Texas at Arlington
Comparative Cfd Analysis Of The Effect Of Air And Liquid Cooling On The Form Factor Of Gpu Server, Ankit Bharatkumar Sutaria
Mechanical and Aerospace Engineering Theses - Archive
Artificial intelligence (AI) has becoming an important area which may significantly impact everyone’s daily life. This means a lot of high-performance chips such as high-performance CPU, GPU, FPGA (Field-programmable gate array), ASIC (application specific integrated circuit) devices may need. The thermal design power (TDP) of these chips are high, and now it is very common to see a processor TDP reaches as high as 300Watts[1]. When these high-power density processors are packaged together, the power density of the servers and compute boxes are significantly high. Traditional air-cooling is approaching its cooling capability limitation, especially when a cluster of racks is …
Design And Optimization Of Additively Manufactured Heat Sink And Heat Spreader For Microelectronics Cooling,
2019
University of Texas at Arlington
Design And Optimization Of Additively Manufactured Heat Sink And Heat Spreader For Microelectronics Cooling, Aditya Krishna Ganesh Ram
Mechanical and Aerospace Engineering Theses - Archive
High performance cooling is a critical requirement for modern microprocessors that generate large amounts of non-uniformly distributed heat. Metal heat spreaders and heat sinks have been traditionally used for thermal management. While the design of these components has traditionallly been restricted by manufacturability, in recent years, additive manufacturing has offered the capability to manufacture almost any design. This work analyzes and optimizes the performance of an additively manufactured heat sink and heat spreader. Computational heat transfer simulations were carried out to understand the variation of chip temperature and pressure drop for various designs. Discussion of key findings include the thermal …
Molecular Dynamics (Md) Thermal Simulations Of Molecular Bridging Across The Cathode-Separator Interface In Li-Ion Cell,
2019
University of Texas at Arlington
Molecular Dynamics (Md) Thermal Simulations Of Molecular Bridging Across The Cathode-Separator Interface In Li-Ion Cell, Abhijeet Sundarrao Dhakane
Mechanical and Aerospace Engineering Theses - Archive
While Li-ion cells show outstanding electrochemical performance, their poor thermal transport characteristics results in reduced performance as well as significant safety concerns. The heterogeneous interface between cathode and separator plays a vital role in the dissipation of heat within a Li-ion cell. Previous studies showed that the cathode-separator interfacial thermal resistance contributes around 88% of total thermal resistance within the cell. In this research, thermal conductance across the cathode-separator interface is calculated using molecular dynamics simulations. Thermal transport in a pristine heterogeneous interface as well as interfaces functionalized with monolayers of APTES, nBTMS and MPTMS molecules is studied. The impact …
Constellation Planning Methods For Sequential Spacecraft Rendezvous Using Multi-Agent Scheduling,
2019
Space Dynamics Laboratory
Constellation Planning Methods For Sequential Spacecraft Rendezvous Using Multi-Agent Scheduling, Skylar A. Cox, Nathan B. Stastny, Greg Droge, David K. Geller
Space Dynamics Laboratory Publications
This paper addresses the RPO constellation assignment problem by developing a responsive utility function for tasking a constellation of LEO satellites to several spacecraft servicing tasks. The paper develops the utility function that considers both value of servicing RSO spacecraft in conjunction with the associated ΔV cost. A highly-capable and operationally-relevant task allocation method, called the consensus-based bundle algorithm (CBBA), is leveraged for distributed processing and task allocation. This paper demonstrates that this methodology provides a robust technique for RPO constellation management.
Wireless Antenna Detection Of Electrostatic Discharge Events,
2019
Utah State University
Wireless Antenna Detection Of Electrostatic Discharge Events, Allen Andersen, Jr Dennison
Journal Articles
Wireless intraspacecraft communication technology is being developed for signal transfer on space missions to save weight and simplify the design. One consideration for this new technology is its interaction with space environmentinduced electrostatic discharges (ESDs). The short time scales of spacecraft ESD events result in broad frequency band signals that can interact with high-frequency wireless antennas. These interactions present a source of signal noise. However, they also present a possibility of in-flight wireless ESD monitoring. We present laboratory measurements of arcing on common spacecraft insulators using commercially available single-band 2.4-GHz and dual-band 2.4-/5.8-GHz Wi-Fi antennas. These wireless detections are shown …
Comparative Rack Level Cfd Analysis Of Air To Hybrid Cooling Data Center,
2019
University of Texas at Arlington
Comparative Rack Level Cfd Analysis Of Air To Hybrid Cooling Data Center, Jay Umeshkumar Parekh
Mechanical and Aerospace Engineering Theses - Archive
The demand of data storage in the world is increasing, with this increase, demand for large data centers is growing. In response, we need to look for energy-efficient solutions to reduce the energy consumptions of the data centers. We want to reduce the energy used for cooling while keeping the data center equipment temperature in allowable range in high power density data center. The liquid or hybrid cooled servers are the alternatives that may be used instead of traditional air-cooled servers at Rack Level for the cooling power - different inlet temperatures and different percentage of hybrid cooling. This will …
Computational Fluid Dynamics Analysis Of Inverted, Multi-Element Airfoils In Ground Effect,
2019
Washington University in St. Louis
Computational Fluid Dynamics Analysis Of Inverted, Multi-Element Airfoils In Ground Effect, Michael Grabis, Ramesh K. Agarwal
McKelvey School of Engineering Graduate Student Theses & Dissertations
Formula SAE cars are formula-styled race cars designed to race on an autocross circuit. The autocross circuit is mostly comprised of turning sections as well as a limited amount of straight sections for passing other cars. Highly competitive cars in the competition implement aerodynamic devices to generate negative lift for the race car. This negative lift, or downforce, increases the amount of traction between the race car’s tires and the ground ultimately allowing the drivers to turn at faster speeds. Commonly used aerodynamic devices are a front and rear wing; the wing cross sections are defined by configurations of multiple …
