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Full-Text Articles in Physics
Gravity-Assist Trajectories To Venus, Mars, And The Ice Giants: Mission Design With Human And Robotic Applications, Kyle M. Hughes
Gravity-Assist Trajectories To Venus, Mars, And The Ice Giants: Mission Design With Human And Robotic Applications, Kyle M. Hughes
Open Access Dissertations
Gravity-assist trajectories to Uranus and Neptune are found (with the allowance of impulsive maneuvers using chemical propulsion) for launch dates ranging from 2024 to 2038 for Uranus and 2020 to 2070 for Neptune. Solutions are found using a patched conic model with analytical ephemeris via the Satellite Tour Design Program (STOUR), originally developed at the Jet Propulsion Laboratory (JPL). Delivered payload mass is computed for all solutions for select launch vehicles, and attractive solutions are identified as those that deliver a specified amount of payload mass into orbit at the target body in minimum time. The best cases for each …
Particle Modeling Of Non-Equilibrium Field Emission Driven Rf Microplasmas, Siva Sashank Tholeti
Particle Modeling Of Non-Equilibrium Field Emission Driven Rf Microplasmas, Siva Sashank Tholeti
Open Access Dissertations
Non-equilibrium microplasmas at atmospheric pressures have been investigated for active flow control, micropropulsion and electronic display applications to name a few. The operational voltages for these microplasmas are on the order of kilovolts. When the electric field at the electrodes reaches GV/m or tens of GV/m either due to reduced interelectrode spacing and surface irregularities or due to carefully designed nanostructures on the electrodes, quantum processes such as field emission and field ionization come into effect. These can potentially reduce the operational voltages of microplasma devices by an order of magnitude. Due to the rarefied and non-equilibrium nature of these …
Feasibility Analysis Of Large Length-Scale Thermocapillary Flow Experiment For The International Space Station, Samantha Jean Alberts
Feasibility Analysis Of Large Length-Scale Thermocapillary Flow Experiment For The International Space Station, Samantha Jean Alberts
Open Access Theses
The investigation of microgravity fluid dynamics emerged out of necessity with the advent of space exploration. In particular, capillary research took a leap forward in the 1960s with regards to liquid settling and interfacial dynamics. Due to inherent temperature variations in large spacecraft liquid systems, such as fuel tanks, forces develop on gas-liquid interfaces which induce thermocapillary flows. To date, thermocapillary flows have been studied in small, idealized research geometries usually under terrestrial conditions. The 1 to 3m lengths in current and future large tanks and hardware are designed based on hardware rather than research, which leaves spaceflight systems designers …
Applicability Of Continuum Fracture Mechanics In Atomistic Systems, Shao-Huan Cheng
Applicability Of Continuum Fracture Mechanics In Atomistic Systems, Shao-Huan Cheng
Open Access Dissertations
By quantitating the amplitude of the unbounded stress, the continuum fracture mechanics defines the stress intensity factor K to characterize the stress and displacement fields in the vicinity of the crack tip, thereby developing the relation between the stress singularity and surface energy (energy release rate G). This G-K relation, assigning physical meaning to the stress intensity factor, makes these two fracture parameters widely used in predicting the onset of crack propagation. However, due to the discrete nature of the atomistic structures without stress singularity, there might be discrepancy between the failure prediction and the reality of nanostructured materials. Defining …