150,268 research outputs found

    Models of Income Determination

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    NASA-ARC 91.5-cm airborne infrared telescope

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    A 91.5 cm aperture telescope installed aboard NASA-Lockheed C-141A aircraft for the performance of infrared astronomy is described. A unique feature of the telescope is that its entire structure is supported by a 41 cm spherical air bearing which effectively uncouples it from aircraft angular motion, and with inertial stabilization and star tracking, limits tracking errors to less than 1 arc second in most applications. A general description of the system, a summary of its performance, and a detailed description of an offset tracking mechanism is presented

    Computer program for analysis of split-Stirling-cycle cryogenic coolers

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    A computer program for predicting the detailed thermodynamic performance of split-Stirling-cycle refrigerators has been developed. The mathematical model includes the refrigerator cold head, free-displacer/regenerator, gas transfer line, and provision for modeling a mechanical or thermal compressor. To allow for dynamic processes (such as aerodynamic friction and heat transfer) temperature, pressure, and mass flow rate are varied by sub-dividing the refrigerator into an appropriate number of fluid and structural control volumes. Of special importance to modeling of cryogenic coolers is the inclusion of real gas properties, and allowance for variation of thermo-physical properties such as thermal conductivities, specific heats and viscosities, with temperature and/or pressure. The resulting model, therefore, comprehensively simulates the split-cycle cooler both spatially and temporally by reflecting the effects of dynamic processes and real material properties

    New effective interaction for pfpf-shell nuclei and its implications for the stability of the NN=ZZ=28 closed core

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    The effective interaction GXPF1 for shell-model calculations in the full pfpf shell is tested in detail from various viewpoints such as binding energies, electro-magnetic moments and transitions, and excitation spectra. The semi-magic structure is successfully described for NN or Z=28 nuclei, 53^{53}Mn, 54^{54}Fe, 55^{55}Co and 56,57,58,59^{56,57,58,59}Ni, suggesting the existence of significant core-excitations in low-lying non-yrast states as well as in high-spin yrast states. The results of N=ZN=Z odd-odd nuclei, 54^{54}Co and 58^{58}Cu, also confirm the reliability of GXPF1 interaction in the isospin dependent properties. Studies of shape coexistence suggest an advantage of Monte Carlo Shell Model over conventional calculations in cases where full-space calculations still remain too large to be practical.Comment: 29pages, 26figures, to be published in Physical Review

    A covariant and gauge invariant formulation of the cosmological "backreaction"

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    Using our recent proposal for defining gauge invariant averages we give a general-covariant formulation of the so-called cosmological "backreaction". Our effective covariant equations allow us to describe in explicitly gauge invariant form the way classical or quantum inhomogeneities affect the average evolution of our Universe.Comment: 12 pages, no figures. Typos corrected, matches version to appear in JCA
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