Nonflammable potting-encapsulating and conformal coating compounds

Two fluorosilicone rubber formulations have been produced which are nonflammable or self-extinguishing. Extensive report was prepared which includes information on testing and describes many alternate formulations

Production development of organic nonflammable spacecraft potting, encapsulating and conformal coating compounds. Volume 4: Executive summary

The necessity of having nonflammable versions of potting and encapsulating compounds and conformal coatings for space vehicles is discussed. The formulation, EPOCAST 87517 A/B, was found to have the best balance of thermal, electrical, mechanical, physical, and chemical properties of those evaluated. The requirements which this formulation did not meet are listed, and other formulations which were evaluated are summarized. Recommendations for improving EPOCAST 87517 A/B are included

Shock Diffraction by Convex Cornered Wedges for the Nonlinear Wave System

We are concerned with rigorous mathematical analysis of shock diffraction by two-dimensional convex cornered wedges in compressible fluid flow governed by the nonlinear wave system. This shock diffraction problem can be formulated as a boundary value problem for second-order nonlinear partial differential equations of mixed elliptic-hyperbolic type in an unbounded domain. It can be further reformulated as a free boundary problem for nonlinear degenerate elliptic equations of second order. We establish a first global theory of existence and regularity for this shock diffraction problem. In particular, we establish that the optimal regularity for the solution is $C^{0,1}$ across the degenerate sonic boundary. To achieve this, we develop several mathematical ideas and techniques, which are also useful for other related problems involving similar analytical difficulties.Comment: 50 pages;7 figure

Thermal design study of an air-cooled plug-nozzle system for a supersonic cruise aircraft

A heat-transfer design analysis has been made of an air-cooled plug-nozzle system for a supersonic-cruise aircraft engine. The proposed 10deg half-angle conical plug is sting supported from the turbine frame. Plug cooling is accomplished by convection and film cooling. The flight profile studied includes maximum afterburning from takeoff to Mach 2.7 and supersonic cruise at Mach 2.7 with a low afterburner setting. The calculations indicate that, for maximum afterburning, about 2 percent of the engine primary flow, removed after the second stage of the nine-stage compressor, will adequately cool the plug and sting support. Ram air may be used for cooling during supersonic-cruise operations, however. Therefore, the cycle efficiency penalty paid for air cooling the plug and sting support should be low

Space diplomacy and the International Space Station

Debates regarding spacepower, and within this, what is meant by space diplomacy, are in their infancy. This article seeks to contribute to these academic discussions and reflects on the role of the International Space Station (ISS) as an asset of space diplomacy. Although it has been showcased as a successful venture of multilateral science diplomacy, US structural power has ensured that it has first and foremost been a means to project US power and reward strategic partners. As the deadline for decommissioning looms, we argue that now is the time to consider the contributions the ISS has made to space diplomacy and reflect on what will be lost when its life ends

Wildlife Exploitation

The commercial trade threatens species worldwid

Adaptive Radiations in the Context of Macroevolutionary Theory: A Paleontological Perspective

This is the author's accepted manuscript, the published version can be found here http://dx.doi.org/10.1007/s11692-012-9165-8.Adaptive radiations are often invoked anytime clades show significant bursts of diversification, but it is important to not simply assume that any radiating clade constitutes an adaptive radiation. In addition, several highly relevant macroevolutionary concepts including the Turnover Pulse Hypothesis, the Effect Hypothesis, exaptation, and species selection, have not been considered in the adaptive radiations literature. Here, these concepts are integrated into the theory of evolutionary radiations in general, and adaptive radiations in particular, and different types of evolutionary radiations are identified, including geographic radiations. Special emphasis is placed on considering the role that abiotic as opposed to biotic factors may play in motivating diversification during evolutionary radiations. Further, recent paleontological data suggesting that rather than organismal adaptation it may be principally abiotic factors, such as climate change and a taxon’s presence in a geographically complex region, that cause clades to diversify will be described. The fossil record, the source of the initial hallmark examples of adaptive radiation, now appears to show little concrete support for this phenomenon