Advanced Extravehicular Protective Systems (AEPS) study

A description is given of life support subsystem concepts for advanced extravehicular protective systems (AEPS) intended for use on future orbital, lunar surface, and Mars surface missions in the late 1970's and 1980's. Primary interest was centered around the thermal control and carbon dioxide control subsystems because they offer the greatest potential for total weight savings. Emphasis was placed on the generation of regenerable subsystem concepts; however, partially regenerable and expendable concepts were also considered. Previously conceived and developed subsystem concepts were included in the study. Concepts were evaluated on the basis of subsystem weight and volume, and subsystem contribution to parent vehicle weight and volume, which included spares, regeneration equipment, expendables, expandables storage penalty, power penalty, and process heating or cooling penalty. Results are presented showing total weight and volume penalty as a function of total mission extravehicular activity (EVA) hours, and showing EVA weight and volume as a function of EVA duration. Subsystem concepts are recommended for each life support function, and secondary concepts which should be developed are also identified

Regenerable thermal control and carbon dioxide control techniques for use in advanced extravehicular protective systems

The most promising closed CO2 control concept identified by this study is the solid pellet, Mg(OH2)2 system. Two promising approaches to closed thermal control were identified. The AHS system uses modular fusible heat sinks, with a contingency evaporative mode, to allow maximum EVA mobility. The AHS/refrigerator top-off subsystem requires an umbilical to minimize expendables, but less EVA time is used to operate the system, since there is no requirement to change modules. Both of these subsystems are thought to be practical solutions to the problem of providing closed heat rejection for an EVA system

Computer simulation of radiation damage in gallium arsenide

A version of the binary-collision simulation code MARLOWE was used to study the spatial characteristics of radiation damage in proton and electron irradiated gallium arsenide. Comparisons made with the experimental results proved to be encouraging

Research approaches to alleviation of airport-community noise

Airport-community noise reduction problem

The Isometries of Low-Energy Heterotic M-Theory

We study the effective D=4, N=1 supergravity description of five-dimensional heterotic M-theory in the presence of an M5 brane, and derive the Killing vectors and isometry group for the Kahler moduli-space metric. The group is found to be a non-semisimple maximal parabolic subgroup of Sp(4,R), containing a non-trivial SL(2,R) factor. The underlying moduli-space is then naturally realised as the group space Sp(4,R)/U(2), but equipped with a nonhomogeneous metric that is invariant only under that maximal parabolic group. This nonhomogeneous metric space can also be derived via field truncations and identifications performed on Sp(8,R)/U(4) with its standard homogeneous metric. In a companion paper we use these symmetries to derive new cosmological solutions from known ones.Comment: 11 pages, 1 table; two foonotes added, minor corrections to conten

Expanded mixed multiscale finite element methods and their applications for flows in porous media

We develop a family of expanded mixed Multiscale Finite Element Methods (MsFEMs) and their hybridizations for second-order elliptic equations. This formulation expands the standard mixed Multiscale Finite Element formulation in the sense that four unknowns (hybrid formulation) are solved simultaneously: pressure, gradient of pressure, velocity and Lagrange multipliers. We use multiscale basis functions for the both velocity and gradient of pressure. In the expanded mixed MsFEM framework, we consider both cases of separable-scale and non-separable spatial scales. We specifically analyze the methods in three categories: periodic separable scales, $G$- convergence separable scales, and continuum scales. When there is no scale separation, using some global information can improve accuracy for the expanded mixed MsFEMs. We present rigorous convergence analysis for expanded mixed MsFEMs. The analysis includes both conforming and nonconforming expanded mixed MsFEM. Numerical results are presented for various multiscale models and flows in porous media with shales to illustrate the efficiency of the expanded mixed MsFEMs.Comment: 33 page

Noise study of single stage compressor rotor-stator interaction

Study made of noise radiation from rotor-stator interaction in axial-flow compressors. The collected data were reduced to the form of radiation patterns and frequency spectra. These data show how the radiation patterns are affected by the relative number of rotor blades and stator vanes

Cosmological perturbation spectra from SL(4,R)-invariant effective actions

We investigate four-dimensional cosmological vacuum solutions derived from an effective action invariant under global SL(n,R) transformations. We find the general solutions for linear axion field perturbations about homogeneous dilaton-moduli-vacuum solutions for an SL(4,R)-invariant action and find the spectrum of super-horizon perturbations resulting from vacuum fluctuations in a pre big bang scenario. We show that for SL(n,R)-invariant actions with n>3 there exists a regime of parameter space of non-zero measure where all the axion field spectra have positive spectral tilt, as required if light axion fields are to provide a seed for anisotropies in the microwave background and large-scale structure in the universe.Comment: 8 pages, 3 figures, revtex plus epsf, minor typos corrected, version to appear in Physical Review

On the reliability of inflaton potential reconstruction

If primordial scalar and tensor perturbation spectra can be inferred from observations of the cosmic background radiation and large-scale structure, then one might hope to reconstruct a unique single-field inflaton potential capable of generating the observed spectra. In this paper we examine conditions under which such a potential can be reliably reconstructed. For it to be possible at all, the spectra must be well fit by a Taylor series expansion. A complete reconstruction requires a statistically-significant tensor mode to be measured in the microwave background. We find that the observational uncertainties dominate the theoretical error from use of the slow-roll approximation, and conclude that the reconstruction procedure will never insidiously lead to an irrelevant potential.Comment: 16 page LaTeX file with eight postscript figures embedded with epsf; no special macros neede

Protective Behavioral Strategies Underutilization Mediates Effect of a Brief Motivational Intervention among Socially Anxious Undergraduate Drinkers

Social anxiety (SA) is implicated in problematic undergraduate drinking. Brief motivational interventions (BMIs) reduce problematic undergraduate drinking. However, not all students benefit. Identification of vulnerable subgroups is an important next step. The current study examined the role of SA and protective behavioral strategies (PBS) on BMI outcomes. We reanalyzed a subset of data (53.3%; N = 120; 62.5% male) from a randomized trial in which heavy drinking undergraduates were randomized to a BMI or control. SA, past-month typical drinks, peak drinks, weekly quantity, alcohol problems, and PBS were assessed at baseline and 6-weeks. Main effects and interaction among the intervention condition (BMI vs. control) and SA group (low vs. high) were tested on alcohol outcomes and PBS. High SA undergraduates reported greater baseline drinking, more alcohol problems, and lower PBS. Post-BMI, high SA drinkers continued to report greater peak drinks, typical drinks, alcohol problems, and lower PBS use, controlling for baseline use. Among the BMI condition, parallel multiple mediation analyses revealed the PBS subscale Manner of Drinking uniquely mediated the relationship between SA and heavier post-BMI drinking. The PBS Manner of Drinking and Serious Harm Reduction subscales jointly mediated the relationship between SA and greater post-BMI alcohol problems. BMIs may need to be refined to improve outcomes for socially anxious drinkers. Increasing PBS utilization post-BMI may help improve BMI efficacy in this vulnerable group. Clinical implications are discussed