60,942 research outputs found

    Atmospheric composition affects heat- and mass-transfer processes

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    For environmental control system functions sensitive to atmospheric composition, components are test-operated in helium-oxygen and nitrogen-oxygen mixtures, pure oxygen, and air. Transient heat- and mass-transfer tests are conducted for carbon dioxide adsorption on molecular sieve and for water vapor adsorption on silica gel

    On the Evolution, Numbers, and Characteristics of Close-Binary Supersoft Sources

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    The ability to perform detailed evolutionary calculations is essential to the development of a well-defined and testable binary model. Unfortunately, traditional evolutionary calculations cannot be used to follow a significant fraction of possible close-binary supersoft sources (CBSSs). It is therefore important to examine the input physics carefully, to be sure that all relevant and potentially important physical processes are included. In this paper we continue a line of research begun last year, and explore the role that winds are expected to play in the evolution of CBSSs. We find that at least a subset of the systems that seemed to be candidates for common envelope evolution may survive, if radiation emitted by white dwarf drives winds from the system. We study the effects of winds on the binary evolution of CBSSs, and compute the number and characteristics of CBSSs expected to be presently active in galaxies such as our own or M31.Comment: 13 pages; figures included in 0.33 M postscript file; in Supersoft X-ray Sources, ed. J. Greiner (Springer-Verlag: Berlin) (1996

    Development of deployable structures for large space platform systems, volume 2

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    Ground test article design, deployable volumes concept development, habitat and hangar conceptual designs, and deployable volumes analyses are addressed

    Development of deployable structures for large space platform systems. Volume 1: Executive summary

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    Candidate deployable linear platform system concepts suitable for development to technology readiness by 1986 are reviewed. The systems concepts were based on trades of alternate deployable/retractable structure concepts, integration of utilities, and interface approaches for docking and assembly of payloads and subsystems. The deployable volume studies involved generation of concepts for deployable volumes which could be used as unpressurized or pressurized hangars, habitats and interconnecting tunnels. Concept generation emphasized using flexible materials and deployable truss structure technology

    Development of deployable structures for large space platform systems, part 1

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    Eight deployable platform design objectives were established: autodeploy/retract; fully integrated utilities; configuration variability; versatile payload and subsystem interfaces; structural and packing efficiency; 1986 technology readiness; minimum EVA/RMS; and Shuttle operational compatibility

    Profits and balance sheet developments at U.S. commercial banks in 1996

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    U.S. commercial banks had another very good year in 1996. Profits posted strong growth, preserving the high levels of return on equity and return on assets that have prevailed over the past four years. Helping to boost profits were continued strong growth of interest-earning assets, a slight widening of the net interest margin, significant gains in noninterest income, and continued containment of noninterest expenses. Return on assets edged up despite a slight increase in provisioning for loan and lease losses relative to assets. Delinquency and charge-off rates stayed low for business loans but climbed throughout the year for consumer loans.Bank assets ; Banks and banking

    Localization transitions in non-Hermitian quantum mechanics

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    We study the localization transitions which arise in both one and two dimensions when quantum mechanical particles described by a random Schr\"odinger equation are subjected to a constant imaginary vector potential. A path-integral formulation relates the transition to flux lines depinned from columnar defects by a transverse magnetic field in superconductors. The theory predicts that the transverse Meissner effect is accompanied by stretched exponential relaxation of the field into the bulk and a diverging penetration depth at the transition.Comment: 4 pages (latex) with 3 figures (epsf) embedded in the text using the style file epsf.st

    Firm Capabilities, Competition and Industrial Policies in a History-Friendly Model of the Computer Industry

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    In this paper, we explore some problems that industrial policy faces in industries characterized by dynamic increasing returns on the basis of a 'history friendly model' of the evolution of the computer industry. How does policy affect industry structure over the course of industry evolution? Is the timing of the intervention important? Do policy interventions have indirect and perhaps unintended consequences on different markets at different times? We focus on two sets of policies: antitrust and interventions aiming at supporting the entry of new forms in the industry. The results of our simulations show that, if strong dynamic increasing returns are operative, both through technological capabilities and through customer tendency to stick with a brand, there is little that antitrust and entry policy could have done to avert the rise of a dominant firm in mainframes. On the other hand, if the customer lock in effect had been smaller, either by chance or through policies that discouraged efforts of firms to lock in their customers, the situation might have been somewhat different. In the first place, even in the absence of antitrust or entry encouraging policies, market concentration would have been lower, albeit a dominant firm would emerge anyhow. Second, antitrust and entry encouraging policies would have been more effective in assuring that concentration would decrease. The leading firm would continue to dominate the market, but its relative power would be reduced. © Elsevier Science B.V

    Long range order in the classical kagome antiferromagnet: effective Hamiltonian approach

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    Following Huse and Rutenberg [Phys. Rev. B 45, 7536 (1992)], I argue the classical Heisenberg antiferromagnet on the kagom\'e lattice has long-range spin order of the 3×3\sqrt{3}\times\sqrt{3} type (modulo gradual orientation fluctuations of the spins' plane). I start from the effective quartic Hamiltonian for the soft (out of plane) spin fluctuation modes, and treat as a perturbation those terms which depend on the discrete coplanar state. Soft mode correlations, which become the coefficients of a discrete effective Hamiltonian, are estimated analytically.Comment: 4pp, no figures. Converted to PRB format, extensive revisions/some reorderings to improve clarity; some cut
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