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PDF, Engelska, 20131 416 kr
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Sects. 12, 13. 89 sequence and that subgiant and fainter stars in globular clusters have ultraviolet excesses. When dealing with stars whose physical properties are imperfectly under stood, such as in globular cluster stars, we cannot rely too heavily on the empiri cal calibration by the kinds of stars used to define Fig. 5, to determine their true, unreddened U-B, B-V curve. But if by a combination of arguments, principally the reddening in the region of the stars we do known about, we can assign a fairly probable unreddened U-B, B-V curve to a group of stars about which we know little, the argument may be turned around. In this case some information may be gained about the energy envelope of the stars by examining the differences between the normal two-color index curves for the unknown group of stars compared to the known. In general there seem to be two possible causes for different stars defining different normal sequences in the U-B, B-V plane. One, the relative energy distribution in the continuum in the U, B and V photometry bands are different. An example of this is the effect of the Balmer depression in supergiants. This, of course, requires deviation from black body radiation curves for one or both groups of stars. This cause seems to be the dominant effect for very blue, hot stars where the depression of the continuum by absorption lines is at a minimum.
Häftad, Engelska, 2012
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Sects. 12, 13. 89 sequence and that subgiant and fainter stars in globular clusters have ultraviolet excesses. When dealing with stars whose physical properties are imperfectly under stood, such as in globular cluster stars, we cannot rely too heavily on the empiri cal calibration by the kinds of stars used to define Fig. 5, to determine their true, unreddened U-B, B-V curve. But if by a combination of arguments, principally the reddening in the region of the stars we do known about, we can assign a fairly probable unreddened U-B, B-V curve to a group of stars about which we know little, the argument may be turned around. In this case some information may be gained about the energy envelope of the stars by examining the differences between the normal two-color index curves for the unknown group of stars compared to the known. In general there seem to be two possible causes for different stars defining different normal sequences in the U-B, B-V plane. One, the relative energy distribution in the continuum in the U, B and V photometry bands are different. An example of this is the effect of the Balmer depression in supergiants. This, of course, requires deviation from black body radiation curves for one or both groups of stars. This cause seems to be the dominant effect for very blue, hot stars where the depression of the continuum by absorption lines is at a minimum.
E-bok
PDF, Engelska, 20121 416 kr
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Häftad, Engelska, 2012
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E-bok
PDF, Engelska, 20121 408 kr
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Sponsored by the Office for Industrial Associates of the California Institute of Technology and the Society for Morphological Research, Pasadena, California, May 22-24, 1967
Häftad, Engelska, 2012
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10 Definitions Operations research, first called operational re- search by P. M. S. Blackett (1) in Britain about 1938, has a broad zneaning illustrated by several exaznples in this section. Briefly, it znay be defined as the study of znan- znachine systezns that have a purpose. In znore descriptive terzns, operations research involves the application of physical, biological, and social sciences in the znost quanti- tative way possible. It thus draws on the disciplines of znedicine, psychology, and all forzns of engineering (2). As the following historical exaznples will show, an essential step in every 0 - R study is recognition of the purpose of an ope ration, an organiz ation, or a systezn. This often leads to a zneasure of znerit or a value parazneter by which operational results can be coznpared; for exaznple, the fraction of approaching aircraft shot down by an air-defense systezn, or annual sales of products by an industrial con- cern, or gross national product of a country. Predictions of such operational results, and quanti- tative coznparisons between different systezns, require znatheznatical znodels of each systezn and its operation.In sozne cases--such as the accuracy of anti-aircraft fire, or the cost of producing a znachined product, or transportation costs of delivery--the znodel can be znatheznatically precise or deterzninistic. More generally, operational results are probabalistic and require a stochastic znodel.