Rarefied-flow aerodynamics

Means for relatively simple and quick procedures are examined for estimating aerodynamic coefficients of lifting reentry vehicles. The methods developed allow aerospace designers not only to evaluate the aerodynamics of specific shapes but also to optimize shapes under given constraints. The analysis was also studied of the effect of thermomolecular flow on pressures measured by an orifice near the nose of a Space Shuttle Orbiter at altitudes above 75 km. It was shown that pressures corrected for thermomolecular flow effect are in good agreement with values predicted by independent theoretical methods. An incidental product was the insight gained about the free molecular thermal accommodation coefficient applicable under 'real' conditions of high speed flow in the Earth's atmosphere. The results are presented as abstracts of referenced papers. One reference paper is presented in its entirety

Commentary on the 1985 NASA/Vanderbilt Symposium on Future Hypervelocity Flight Requirements

The discussion, started in Semiannual Status Report Number 1, on aerothermal problems of hypervelocity flight and experiments that may lead to significant improvements in analytical/computational predictive methods, continues. The commentary is based on presentations made by speakers at a symposium on this subject held in December 1985. Symposium participants focused on the serious deficiencies that exist in knowledge of real-gas, nonequilibrium thermochemical-kinetic processes, catalytic processes, surface and shock slip, gas/surface interaction, boundary layer transition, and vortical leeside flows under hypervelocity conditions. Programs of laboratory research and computations leading toward in-flight experiments were recommended. Feasibility of appropriate measurement techniques for the flight environment was assessed and problems for study in that area identified. A synopsis of the oral presentations is given

Uncovering the physics behind the blazar sequence using a realistic model for jet emission

Blazar spectra are one of the most important windows into the physical processes occurring along jets. The spectrum, composed from the different emitting regions along the jet, allows us to constrain the physical conditions in the jet. I present my work modelling blazar spectra using an extended inhomogeneous jet model with an accelerating, magnetically dominated, parabolic base transitioning to a slowly decelerating, conical section motivated by observations, simulations and theory. We set the inner geometry of our multi-zone model using observations of the jet in M87 which transitions from parabolic to conical at 10^5 Schwarzschild radii. This model is able to reproduce quiescent blazar spectra very well across all wavelengths (including radio observations) for a sample of 42 BL Lacs and FSRQs. Using this inhomogeneous model we are able to constrain the location at which the synchrotron emission is brightest in these jets by fitting to the optically thick to thin synchrotron break. We find that the radius of the jet at which the synchrotron emission is brightest (where the jet first approaches equipartition) scales approximately linearly with the jet power. We also find a correlation between the length of the accelerating, parabolic section of the jet and the maximum bulk Lorentz factor. In agreement with previous work we find that BL Lacs are low power blazars whereas FSRQs are high power blazars. Together with our simple jet power-radius relation this leads us to a deeper understanding of the physics underlying the blazar sequence.Comment: 5 pages, 5 figures, to appear in "The Innermost Regions of Relativistic Jets and Their Magnetic Fields" conference proceedings; includes minor change

A simulation study of Large Area Crop Inventory Experiment (LACIE) technology

The author has identified the following significant results. The LACIE performance predictor (LPP) was used to replicate LACIE phase 2 for a 15 year period, using accuracy assessment results for phase 2 error components. Results indicated that the (LPP) simulated the LACIE phase 2 procedures reasonably well. For the 15 year simulation, only 7 of the 15 production estimates were within 10 percent of the true production. The simulations indicated that the acreage estimator, based on CAMS phase 2 procedures, has a negative bias. This bias was too large to support the 90/90 criterion with the CV observed and simulated for the phase 2 production estimator. Results of this simulation study validate the theory that the acreage variance estimator in LACIE was conservative

Institutional Title IX Requirements for Researchers Conducting Human Subjects Research on Sexual Violence and other Forms of Interpersonal Violence

The purpose of this white paper is to provide guidance on how university and college Institutional Review Boards (IRBs) and IRB administrators can oversee, and researchers can conduct, research investigating the different aspects of Sexual Violence and other forms of Interpersonal Violence

Aerodynamic calculations related to tethered sub-satellite experiments

The results are presented of four aerodynamic studies that were in support of a broader, preliminary inquiry concerning the potential use of downward-deployed tethered sub-satellites for in-flight aerothermodynamic research. There are a multitude of questions regarding the general tethered satellite concept and the present report addresses only a few of these. A method for estimating drag and local surface pressure and shear on orbiting or re-entereing bodies is described, and examples based on the planned TSS-2 (Tethered Satellite System) are given. The problem of pressure measurement are explored, taking into account thermal transpiration, lag time, and the disturbed flow field created by the satellite body. The performance of an aerodynamic stabilizer, a ring-tail design, is calculated and its influence on satellite motion is illustrated. A method for optimizing future satellite shapes for desired aerodynamic properties is transitional rarefied flow with given geometric constraints is proposed and examples are shown

Implications of HGV charging for the UK

Road transport taxation in Europe is undergoing a major and radical shift away from fixed charges and fuel duties towards pricing according to distance travelled and externalities produced. Implementation is underway in some states, change being led by national schemes for the freight sector only. The UK is considering such a system for implementation by 2008, to use global positioning system technology. The paper reviews the current developments and considers charging scenarios, including a scenario for covering the full external costs of the UK freight industry. Implications for taxation policy are considered, including whether the doctrine of revenue neutrality is consistent with 'sustainable mobility'. Consideration is given to a transition strategy which could bridge between the current level and structure of prices and a future, more economically efficient approach