Generalized poisson brackets and nonlinear Liapunov stability application to reduces mhd

A method is presented for obtaining Liapunov functionals (LF) and proving nonlinear stability. The method uses the generalized Poisson bracket (GPB) formulation of Hamiltonian dynamics. As an illustration, certain stationary solutions of ideal reduced MHD (RMHD) are shown to be nonlinearly stable. This includes Grad-Shafranov and Alfven solutions

The effects of environmental exposure on reusable surface insulation for space shuttle

Coated specimens of reusable surface insulation (RSI) were exposed to alternate radiant heating and atmospheric exposure cycles to study the effects of surface contamination on the RSI coating. Different methods of heating were employed on clean and artificially contaminated specimens to determine the contributions of heating conditions to coating devitrification

Air traffic control surveillance accuracy and update rate study

The results of an air traffic control surveillance accuracy and update rate study are presented. The objective of the study was to establish quantitative relationships between the surveillance accuracies, update rates, and the communication load associated with the tactical control of aircraft for conflict resolution. The relationships are established for typical types of aircraft, phases of flight, and types of airspace. Specific cases are analyzed to determine the surveillance accuracies and update rates required to prevent two aircraft from approaching each other too closely

Temperature distribution in a stellar atmosphere diagnostic basis

A stellar chromosphere is considered a region where the temperature increases outward and where the temperature structure of the gas controls the shape of the spectral lines. It is shown that lines which have collision-dominated source sink terms, like the Ca(+) and Mg(+) H and K lines, can be used to obtain the distribution of temperature with height from observed line profiles. Intrinsic emission lines and geometrical emission lines are found in spectral regions where the continuum is depressed. In visual regions, where the continuum is not depressed, emission core in absorption lines are attributed to reflections of intrinsic emission lines

Hamiltonian approach to hybrid plasma models

The Hamiltonian structures of several hybrid kinetic-fluid models are identified explicitly, upon considering collisionless Vlasov dynamics for the hot particles interacting with a bulk fluid. After presenting different pressure-coupling schemes for an ordinary fluid interacting with a hot gas, the paper extends the treatment to account for a fluid plasma interacting with an energetic ion species. Both current-coupling and pressure-coupling MHD schemes are treated extensively. In particular, pressure-coupling schemes are shown to require a transport-like term in the Vlasov kinetic equation, in order for the Hamiltonian structure to be preserved. The last part of the paper is devoted to studying the more general case of an energetic ion species interacting with a neutralizing electron background (hybrid Hall-MHD). Circulation laws and Casimir functionals are presented explicitly in each case.Comment: 27 pages, no figures. To appear in J. Phys.

Environmental effects on space shuttle reusable surface insulation coated with reaction cured glass

Sample titles of the space shuttle reusable surface insulation was subjected alternately to simulated mission heating and either real or simulated environmental exposure for up to 34 cycles. The coating cracked as a result of exposure to high temperature and moisture conditions, and insulation with cracked coatings absorbed significant quantities of water in the launch-pad environment. Cracking was a complex function of time, temperature, and moisture exposure. Cracked coatings remained adherent to the insulation for up to 24 cycles past initial cracking