Future developments in transportation

Nearly all prognostigators, from the fellow who buys a $2 ticket on Blue Boy to the financial policy-makers of government and business, base their final conclusions upon past experience. Properly tempered (and herein lies the success or failure of the prophet), this is a completely logical procedure, and is especially applicable to engineering trends, for most of our technical progress has been achieved through a process of evolution.Thus, one of the best ways to gain an insight as to the direction in which we're going is to note our present position and to review how we reached it.In the preceding discussion, I have tried to cover a few specific phases of our transportation future in just this fashion, in order to emphasize that we can expect tomorrow further applications and extensions of the things we are working with today.     

The slow neutron-induced radioactivities of nuclear explosions

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.     

Dimensions of R&D location in the United States

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.     

Controllability and extensions

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, (t_a,x_a) and (t_b,x_b) 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.