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871.
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Friedrich Edding G. W. Parkyn Renzo Titone Oskar Anweiler Frederic Lilge John Vaizey Werner Levi B. Magierska Walter Schultze Mary Ewen Ulich Ben Morris Ignacy SzAniawski G. de Landsheere M. L. Kellmer Pringle W. Lenz Rudolf Haas John Bradley Josip Lukatela M. J. Langeveld S. Wiegersma H. H. Stern H. P. Rickman 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1963,8(3-4):471-498
874.
R. P. Clark Einar Lilja Eve Malmqvist Louis Arnaud Reid Edmund King John Downing C. M. Fleming Arnould Clausse G. de Landsheere Vernon Mallinson Paul Nash Tomio Goto M. A. Brimer Rudolf Cohen Gerhard Pause M. J. Langeveld W. E. Vliegenthart Emile Planchard 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1963,9(3):351-382
875.
876.
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
877.
The case is considered in which, during the operation of an optimal control system, the optimizer, in addition to applying his usual control, may switch structures. Necessary and sufficient conditions are derived and emphasis is placed on the special characteristics of this problem. Continuous and discrete time set-ups are considered and the separation principle is shown not to hold for the linear quadratic case in the presence of noise. 相似文献
878.
The graph-theoretic field model— II. application of multi-terminal representations to field problems
This paper is a sequel to a paper entitled “The Graph-Theoretic Field Model—I: Modelling and Formulations” (1). Herein, the Theory of Multi-Terminal Representations is applied to the Graph-Theoretic Field Model to provide mathematical models of finite elements. The element models are obtained solely from the algebraic building blocks of the Graph-Theoretic Field Model, without recourse to any functional mathematics. The theory of Multi-Terminal Representations is developed for both linear and non-linear problems. Examples of the application of the theory to one- and two-dimensional field problems are presented from heat conduction and electrostatics. 相似文献
879.
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
880.
J.M. Bowsher 《Endeavour》1980,4(1):20-25
The design of musical instruments owes more to art than to science and assessment of their quality is essentially subjective. Nevertheless, the physical principles of their operation are very interesting and may be of practical importance. This article reviews the acoustics of brass wind instruments, regarding the player and his instrument as an entity, and compares experimental and theoretical results. 相似文献