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991.
C.E. Mandeville 《Journal of The Franklin Institute》1951,252(4):297-308
The slow neutron-induced radioactivities of nuclear explosions have been evaluated for infinite media of filtered Schuylkill water and the earth's crust. The magnitudes of these effects are compared with the activity of the fission fragments, and the conditions under which they may be of importance are considered.It has been assumed that a gram-molecule of neutrons is liberated in the blast. 相似文献
992.
993.
994.
E.J. Malecki 《Research Policy》1980,9(1):2-22
R&D activities in the United States, as in other advanced economies, are geographically concentrated in certain types of locations. This study presents data on the location of four dimensions of R&D in the U.S.: industrial R&D laboratories, scientists and engineers engaged in R&D, scientists and engineers employed by the federal government, and research universities. Industrial R&D is much more concentrated in large urban areas than the other dimensions, and appears to locate more in response to the location of manufacturing activity than to the location of research universities and federal research facilities. The location of R&D employment, which includes government university, and industrial employees, is associated with facilities for all three types of R&D. Because of these factors, R&D in the U.S. is found on a significant per capita basis in 44 of 177 urban areas, most of them in the northeastern portion of the country. When two dimensions, industrial R&D laboratories and R&D employees, are combined as a measure of R&D concentration, the locational pattern is less clustered regionally. Ten urban areas in all regions of the U.S. are identified as important complexes of R&D. Since the location of R&D is a major indicator of comparative advantage for technological activities and the economic potential of urban regions, only a few areas of the U.S. are likely to remain important in the generation of innovations. 相似文献
995.
J.E. Rubio 《Journal of The Franklin Institute》1980,309(5):301-308
Control problems in Hilbert spaces are treated in a measure-theoretical framework; instead of dealing with a set of admissible trajectory-control pairs, a set of measures defined by the boundary conditions and the differential equations of the problem are considered. The concept of weak controllability is introduced; a system has this property if every pair of initial and final points, (ta,xa) and (tb,xb) can be weakly joined; this is possible if a set of linear equalities involving measures has a solution. In turn, this is shown to be equivalent to the possibility of extending a linear functional in a positive manner. Necessary and sufficient conditions for controllability are derived, and applied to the study of a finite-dimensional system with the control appearing linearly. 相似文献
996.
N.W Pirie 《Endeavour》1980,4(2):74-77
Victualling in space differs fundamentally from victualling on land or at sea because there is little chance of foraging or of finding local sources of oxygen and water, and all metabolic products have to be carefully collected even if they will ultimately be jettisoned. The need for a deliberate policy for coping with carbon dioxide, faeces, and urine leads naturally, to schemes for recycling. Entropy is increased when food is metabolised: energy will have to be expended for even partial restoration of the status quo. 相似文献
997.
998.
999.
W. Frank Hull IV Walter H. Lemke Jr. 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1978,24(1):53-64
While off-campus educational programs grow in number and in importance in American higher education, little systematic research has been conducted concerning their effectiveness and intellectual and developmental impact. The project described here compared students in three categories: those studying abroad; those studying off-campus in this country; and those who remained on their home campus. The implications of the findings of the research suggest that a rethinking of existing programs is appropriate, if off-campus educational programs are to realize their full potential. The authors offer concrete suggestions toward restructuring these programs.
Zusammenfassung Obwohl Bildungsprogramme ausserhalb der Universität in der amerikanischen Hochschulbildung an Anzahl und Bedeutung zunehmen, wurde deren Fruchtbarkeit und geistige und entwicklungsmässige Auswirkung kaum systematisch untersucht. Das hier geschilderte Projekt vergleicht Studenten dreier Kategorien: im Ausland studierende, im Lande ausserhalb der Universität studierende und solche, die in ihrem heimischen Universitätsbetrieb geblieben sind. Die Ergebnisse der Untersuchung legen die Folgerung nahe, es sei angebracht, bei eingeführten Programmen zu überdenken, ob die Bildungsprogramme ausserhalb der Universität ihre Möglichkeiten voll ausschöpfen sollen. Die Verfasser machen konkrete Vorschläge für eine Neugestaltung dieser Programme.
Résumé Tandis que l'importance et le nombre des programmes d'éducation en dehors des universités s'accroît dans l'enseignement supérieur aux Etats-Unis, peu de recherche systématique a été effetué en ce qui concerne leur efficacité et leur impact intellectuel et de développement. Le projet décrit ici a comparé des étudiants de trois catégories: ceux qui étudient à l'étranger, ceux qui étudient hors des universités à l'intérieur du pays et ceux qui sont restés dans leurs universités d'origine. Les implications des conclusions de la recherche suggèrent qu'il convient de repenser les programmes existants, si les programmes d'éducation hors des universités doivent réaliser tout leur potentiel. Les auteurs présentent des suggestions concrètes quant à la restructuration de ces programmes.相似文献
1000.
Jerome E. Schnee 《Research Policy》1978,7(1):3-24
The research reported in this article was carried out as part of a larger prefect investigating the impact of the US Space Program on the American economy. The author describes the influence of governmental programs in space and defense on the growth of the computer and semiconductor industries. Three types of economic impacts are analyzed: the role of the federal government in financing research and development; the importance of the government as a market, particularly in the early stages of an industry's growth; and the extent to which government policy encouraged the entrance of new firms and permitted the survival of companies that might otherwise have failed. The paper also deals with the contribution of Defense and NASA to the acceleration of technological changes and the development of specialized manpower on which the progress of the industry largely depended.The author concludes that large government programs can play an essential role in the growth of high technology industries. The significance of space-defense programs for US semiconductor and computer firms can only be perceived by reviewing each type of impact-economic, technological and manpower. The government's early R & D support, assured demand during startup periods, encouragement of competition, acceleration of technological progress and its facilitating of professional mobility, are the separate impacts which together greatly aided US firms in their rise to a dominant position in the world semiconductor and computer industries. 相似文献