Libration-point staging concepts for Earth-Mars transportation

The use of libration points as transfer nodes for an Earth-Mars transportation system is briefly described. It is assumed that a reusable Interplanetary Shuttle Vehicle (ISV) operates between the libration point and Mars orbit. Propellant for the round-trip journey to Mars and other supplies would be carried from low Earth orbit (LEO) to the ISV by additional shuttle vehicles. Different types of trajectories between LEO and libration points are presented, and approximate delta-V estimates for these transfers are given. The possible use of lunar gravity-assist maneuvers is also discussed

Unsteady fluid mechanics of annular swirling shear layers

The vast majority of gas turbine combustor systems employ swirl injectors to produce a central toroidal recirculation zone (CTRZ) which entrains and recirculates a portion of the hot combustion gases to provide continuous ignition to the incoming air-fuel mix. In addition to these primary functions, swirl injectors often generate multiple aerodynamic instability modes which are helical in nature with characteristic frequencies that can differ by many orders of magnitude. If any of these frequencies are consistent with prevalent acoustic modes within the combustor there is a potential for flow-acoustic coupling which may reinforce acoustic oscillations and drive combustion instabilities via the Rayleigh criterion. The aerodynamic performance of the swirl injector is thus of great practical importance to the design and development of combustion systems and there is a strong desire within industry for reliable computational methods that can predict this highly unsteady behaviour. This assessment can be made under isothermal conditions which avoids the complex interactions that occur in reacting flow. The goal of the present work was to compare and contrast the performance of Unsteady Reynolds- Averaged Navier-Stokes (URANS) and Large-Eddy Simulation (LES) CFD methodologies for a combustion system equipped with a derivative of an industrial Turbomeca swirl injector as this exhibits similar unsteady aerodynamic behaviour under reacting and isothermal conditions. (Continues...)

Combining asteroid models derived by lightcurve inversion with asteroidal occultation silhouettes

Asteroid sizes can be directly measured by observing occultations of stars by asteroids. When there are enough observations across the path of the shadow, the asteroid's projected silhouette can be reconstructed. Asteroid shape models derived from photometry by the lightcurve inversion method enable us to predict the orientation of an asteroid for the time of occultation. By scaling the shape model to fit the occultation chords, we can determine the asteroid size with a relative accuracy of typically ~ 10%. We combine shape and spin state models of 44 asteroids (14 of them are new or updated models) with the available occultation data to derive asteroid effective diameters. In many cases, occultations allow us to reject one of two possible pole solutions that were derived from photometry. We show that by combining results obtained from lightcurve inversion with occultation timings, we can obtain unique physical models of asteroids.Comment: 33 pages, 45 figures, 4 tables, accepted for publication in Icaru

Transitory Effects of Dimethyl Sulfoxide on the Electrical Properties of Isolated Frog Skin

The experiments indicate that when DMSO-Ringer\u27s solutions are applied to the outside of the frog skin, the electrical potential difference across the skin decreases while the short circuiting current increases slightly. Ringer\u27s solutions containing DMSO applied to the inside of the skin caused both the short circuiting current and the potential difference across the skin to decrease. These observations appear to be directly related to the concentration of DMSO-Ringer\u27s applied. The observed effects are discussed with respect to possible changes in the skin brought about by the DMSO and the relationships of these phenomena to active transport functions of the skin

Subtask 5.3 - Water and Energy Sustainability and Technology

The overall goal of this Energy & Environmental Research Center project was to evaluate water capture technologies in a carbon capture and sequestration system and perform a complete systems analysis of the process to determine potential water minimization opportunities within the entire system. To achieve that goal, a pilot-scale liquid desiccant dehumidification system (LDDS) was fabricated and tested in conjunction with a coal-fired combustion test furnace outfitted with CO{sub 2} mitigation technologies, including the options of oxy-fired operation and postcombustion CO{sub 2} capture using an amine scrubber. The process gas stream for these tests was a coal-derived flue gas that had undergone conventional pollutant control (particulates, SO{sub 2}) and CO{sub 2} capture with an amine-based scrubber. The water balance data from the pilot-scale tests show that the packed-bed absorber design was very effective at capturing moisture down to levels that approach equilibrium conditions