Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- Applied sciences (5)
- Pure sciences (4)
- Acoustic scattering prediction methods (1)
- Aeroacoustics of jet noise (1)
- Astrodynamics (1)
-
- Atomistic systems (1)
- Continuum fracture mechanics (1)
- Data compression (1)
- Dielectric-barrier discharge (1)
- Earth-Mars cyclers (1)
- Equivalent source method (1)
- Ffowcs-Williams Hawkings method (1)
- Field emission (1)
- Field ionization (1)
- Flow actuation (1)
- G1a pressure gradient formulation (1)
- Information theory (1)
- Inspiration Mars (1)
- Literature review of acoustic scattering methods (1)
- Microchannel flow (1)
- Microplasma (1)
- Neptune (1)
- Neural networks (1)
- Nonlinear estimation (1)
- Orbit determination (1)
- Orbital mechanics (1)
- Stress intensity fracture (1)
- Time-domain boundary element method (1)
- Trajectory design (1)
- Uranus (1)
Articles 1 - 7 of 7
Full-Text Articles in Physical Sciences and Mathematics
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 …
Implementing And Testing A Panel-Based Method For Modeling Acoustic Scattering From Cfd Input, S. Hales Swift
Implementing And Testing A Panel-Based Method For Modeling Acoustic Scattering From Cfd Input, S. Hales Swift
Open Access Dissertations
Exposure of sailors to high levels of noise in the aircraft carrier deck environment is a problem that has serious human and economic consequences. A variety of approaches to quieting exhausting jets from high-performance aircraft are undergoing development. However, testing of noise abatement solutions at full-scale may be prohibitively costly when many possible nozzle treatments are under consideration. A relatively efficient and accurate means of predicting the noise levels resulting from engine-quieting technologies at personnel locations is needed. This is complicated by the need to model both the direct and the scattered sound field in order to determine the resultant …
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 …
Assessment Of High-Fidelity Collision Models In The Direct Simulation Monte Carlo Method, Andrew Brian Weaver
Assessment Of High-Fidelity Collision Models In The Direct Simulation Monte Carlo Method, Andrew Brian Weaver
Open Access Dissertations
Advances in computer technology over the decades has allowed for more complex physics to be modeled in the DSMC method. Beginning with the first paper on DSMC in 1963, 30,000 collision events per hour were simulated using a simple hard sphere model. Today, more than 10 billion collision events can be simulated per hour for the same problem. Many new and more physically realistic collision models such as the Lennard-Jones potential and the forced harmonic oscillator model have been introduced into DSMC. However, the fact that computer resources are more readily available and higher-fidelity models have been developed does not …
Applications Of Femtosecond Coherent Anti-Stokes Raman Scattering In Combustion, Claresta Nicole Dennis
Applications Of Femtosecond Coherent Anti-Stokes Raman Scattering In Combustion, Claresta Nicole Dennis
Open Access Dissertations
The dissertation deals with the further development of chirped-probe-pulse femtosecond coherent anti-Stokes Raman spectroscopy (CPP fs-CARS) for applications of gas phase thermometry and extension to methane concentration measurements. The main effort has been to assess the usefulness and robustness of the technique in turbulent combustors of practical interest. A primary aim has been to evaluate the use of CPP fs-CARS for vibrational N2 thermometry in a highly turbulent environment. It has been suggested that due to the laser beam temporal overlap required for fs-CARS signal generation, the technique would be unsuccessful due to beam propagation retardation effects from density …
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 …
Information Measures For Statistical Orbit Determination, Alinda Kenyana Mashiku
Information Measures For Statistical Orbit Determination, Alinda Kenyana Mashiku
Open Access Dissertations
The current Situational Space Awareness (SSA) is faced with a huge task of tracking the increasing number of space objects. The tracking of space objects requires frequent and accurate monitoring for orbit maintenance and collision avoidance using methods for statistical orbit determination. Statistical orbit determination enables us to obtain estimates of the state and the statistical information of its region of uncertainty given by the probability density function (PDF). As even collision events with very low probability are important, accurate prediction of collisions require the representation of the full PDF of the random orbit state. Through representing the full PDF …