Cislunar Trajectory Generation With Sun-Exclusion Zone Constraints Using A Genetic Algorithm And Direct Method Hybridization,
2019
Air Force Institute of Technology
Cislunar Trajectory Generation With Sun-Exclusion Zone Constraints Using A Genetic Algorithm And Direct Method Hybridization, Joshua A. Ostman
Theses and Dissertations
Space missions to the Moon have received renewed interest in recent decades. Science missions continue to be sent to the Moon, and several space agencies have aspirations of establishing a human presence on the Moon. With the increased number of artificial objects in cislunar space, the problem of tracking these objects arises. Optical sensors are able to track these objects in deep space. However, optical sensors cannot track objects that are close to the Sun as viewed from the observer. This unobservable region is the Sun-exclusion zone (SEZ). This research attempts to create optimal Moon-Earth transfers which are completely in …
Optimization Of The Dedicated Corridor System Connecting Bohai Rim Gateways,
2019
World Maritime University
Optimization Of The Dedicated Corridor System Connecting Bohai Rim Gateways, Xinyi Shi
World Maritime University Dissertations
No abstract provided.
Research On Double-Stack Container Transport Organization In International Multimodal Transport,
2019
World Maritime University
Research On Double-Stack Container Transport Organization In International Multimodal Transport, Xi Zhu
World Maritime University Dissertations
No abstract provided.
Lifestyle And Solutions: An Investigation Of Fatigue In Collegiate Aviation,
2019
Purdue University
Lifestyle And Solutions: An Investigation Of Fatigue In Collegiate Aviation, Aaron Teo, Erik Levin
The Journal of Purdue Undergraduate Research
No abstract provided.
Micrometeoroid Impacts On Periodic Spacecraft Structures,
2019
Purdue University
Micrometeoroid Impacts On Periodic Spacecraft Structures, Victoria West, Luis Buades, Hanson-Lee Harjono
The Journal of Purdue Undergraduate Research
No abstract provided.
Origins Of Space Food From Mercury To Apollo,
2019
Purdue University
Origins Of Space Food From Mercury To Apollo, Celine Chang
The Journal of Purdue Undergraduate Research
No abstract provided.
Simplified 2d Skin Lattice Models For Multi-Axial Camber Morphing Wing Aircraft,
2019
Tennessee State University
Simplified 2d Skin Lattice Models For Multi-Axial Camber Morphing Wing Aircraft, Bashir Alsaidi, Woong Yeol Joe, Muhammad Akbar
Mechanical and Manufacturing Engineering Faculty Research
Conventional fixed wing aircraft require a selection of certain thickness of skin material that guarantees structural strength for aerodynamic loadings in various flight modes. However, skin structures of morphing wings are expected to be flexible as well as stiff to structural and coupled aerodynamic loadings from geometry change. Many works in the design of skin structures for morphing wings consider only geometric compliance. Among many morphing classifications, we consider camber rate change as airfoil morphing that changes its rate of the airfoil that induces warping, twisting, and bending in multi-axial directions, which makes compliant skin design for morphing a challenging …
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 …
