CSI Flight Computer System and experimental test results

This paper describes the CSI Computer System (CCS) and the experimental tests performed to validate its functionality. This system is comprised of two major components: the space flight qualified Excitation and Damping Subsystem (EDS) which performs controls calculations; and the Remote Interface Unit (RIU) which is used for data acquisition, transmission, and filtering. The flight-like RIU is the interface between the EDS and the sensors and actuators positioned on the particular structure under control. The EDS and RIU communicate over the MIL-STD-1553B, a space flight qualified bus. To test the CCS under realistic conditions, it was connected to the Phase-0 CSI Evolutionary Model (CEM) at NASA Langley Research Center. The following schematic shows how the CCS is connected to the CEM. Various tests were performed which validated the ability of the system to perform control/structures experiments

Design, development, and fabrication of a prototype ice pack heat sink subsystem. Flight experiment physical phenomena experiment chest

The concept of a flight experiment physical phenomena experiment chest, to be used eventually for investigating and demonstrating ice pack heat sink subsystem physical phenomena during a zero gravity flight experiment, is described

Charged Particle Motion in a Highly Ionized Plasma

A recently introduced method utilizing dimensional continuation is employed to compute the energy loss rate for a non-relativistic particle moving through a highly ionized plasma. No restriction is made on the charge, mass, or speed of this particle. It is, however, assumed that the plasma is not strongly coupled in the sense that the dimensionless plasma coupling parameter g=e^2\kappa_D/ 4\pi T is small, where \kappa_D is the Debye wave number of the plasma. To leading and next-to-leading order in this coupling, dE/dx is of the generic form g^2 \ln[C g^2]. The precise numerical coefficient out in front of the logarithm is well known. We compute the constant C under the logarithm exactly for arbitrary particle speeds. Our exact results differ from approximations given in the literature. The differences are in the range of 20% for cases relevant to inertial confinement fusion experiments. The same method is also employed to compute the rate of momentum loss for a projectile moving in a plasma, and the rate at which two plasmas at different temperatures come into thermal equilibrium. Again these calculations are done precisely to the order given above. The loss rates of energy and momentum uniquely define a Fokker-Planck equation that describes particle motion in the plasma. The coefficients determined in this way are thus well-defined, contain no arbitrary parameters or cutoffs, and are accurate to the order described. This Fokker-Planck equation describes the longitudinal straggling and the transverse diffusion of a beam of particles. It should be emphasized that our work does not involve a model, but rather it is a precisely defined evaluation of the leading terms in a well-defined perturbation theory.Comment: Comments: Published in Phys. Rep. 410/4 (2005) 237; RevTeX, 111 Pages, 17 Figures; Transcription error corrected in temperature equilibration rate (3.61) and (12.44) which replaces \gamma-2 by \gamma-

Wisdom, Constitutionality, and Nuclear Weapons Policy

In a well-known passage in his famous dissent in the flag-salute case of 1943, Justice Felix Frankfurter wrote: Our constant preoccupation with the constitutionality of legislation rather than with its wisdom tends to preoccupation of the American mind with a false value. The tendency of focussing attention on constitutionality is to make constitutionality synonymous with wisdom, to regard a law as all right if it is constitutional. Such an attitude is a great enemy of liberalism. . . . Reliance for the most precious interests of civilization, therefore, must be found outside of their vindication in courts of law

Fishes of Bayou Meto and Wattensaw Bayou, Two Lowland Streams in East Central Arkansas

Bayou Meto is a low-gradient, highly turbid, warm-water stream that originates in the foothills of the Interior Highlands of central Arkansas and flows southeastward 290 km to the Arkansas River. In the 1970\u27s, Bayou Meto was contaminated with dioxins from a point source (Vertac Corp.) now recognized as a USEPA Superfund site. The present study was initiated to investigate the impact of dioxin on the fish community of Bayou Meto. Fishes were collected by backpack-electrofishing, boat-electrofishing, seines, hoopnets, minnow traps, and trot lines, at 14 sampling stations. Diversity indices (Shannon and Margalef) were used to compare diversity among sample sites. A total of 73 fish species was collected from Bayou Meto and Wattensaw Bayou (a reference stream) between May, 1991 and September, 1992. A total of 79 species had been reported from these drainages. I collected 64 species from Bayou Meto and 48 species from Wattensaw Bayou. Of the 79 species historically reported from these drainages, 17 were not collected during this study. However, of the 73 species collected, 11 (15% of the entire collection) had not been previously recorded from these drainages. There was 57% overlap in species between Bayou Meto and Wattensaw Bayou. Differences in collected species from the two drainages mostly involved rare species i.e., those species in low abundance according to the literature and/or difficult to collect. Centrarchids and castostomids dominated the fish communities of both streams. Percids were also well represented, but 50% were not previously reported from these drainages. Cyprinidae numbers were low and distributions spotty. Diversity varied among sites and was related to impacts and stream order. Diversity was highest at less impacted locations and downstream sites