Showing papers on "Obstacle published in 1973"
01 May 1973
TL;DR: In this article, the experimental and theoretical work at Queen's University on surface-wave devices and their application to obstacle detection are reviewed in detail, concluding that there is considerable promise in these techniques and that obstacle detection, in particular, deserves much more attention than it appears to have received.
Abstract: Electromagnetic open-guiding structures, or surface waveguides, for continuous-access guided communication (CAGC) and obstacle detection ("guided radar"), are described for use in ground transportation, such as railways, highways, and more advanced guided systems. The experimental and theoretical work at Queen's University on surface-wave devices and their application to obstacle detection are reviewed in detail. It is concluded that there is considerable promise in these techniques and that obstacle detection, in particular, deserves much more attention than it appears to have received.
36 citations
TL;DR: In this article, it was shown that the function of least area among all functions defined in a convex domain, vanishing on its boundary, and constrained to lie above a concave analytic obstacle leaves the obstacle along an analytic curve.
Abstract: We announce that the function of least area among all functions defined in a convex domain, vanishing on its boundary, and constrained to lie above a concave analytic obstacle leaves the obstacle along an analytic curve. We announce a result about the curve of separation determined by the solution to a variational inequality. A strictly convex domain Q with smooth boundary <3Q is given in the z = xx + ix2 plane together with a smooth function \\j/(z) which assumes a positive maximum in Q and is negative on 3Q. Let K denote the closed convex set of Lipschitz functions v satisfying v ^ i// in Q and v = 0 on <9Q. Let us denote by u the function of K which minimizes area among all functions of K\\ that is (1) ueK: (\\ _L \\u | 2 \\ l /2 n (I + \\ux\\ ) (v — u)x dx ^ 0, v e K. The existence of such w, actually satisfying ueH(Q) n C(Q), 1 ^ q < oo, 0 < A < 1, was shown in the work of H. Lewy and G. Stampacchia [7] and also in M. Giaquinta and L. Pepe [1]. For u there is a set of coincidence / consisting of the points zeQ where u(z) = il/(z). Let us call (2) r(u) = r = {(xi,X2,x3):x3 = u(z) = \\\\j{z\\zedl} the \"curve\" of separation. Up to this time it has only been known that when i// is smooth and strictly concave, T is a Jordan curve [2], On the other hand, the corresponding problem for the ueK minimizing the Dirichlet integral has been thoroughly studied by H. Lewy and G. Stampacchia [6]. We wish to announce here the THEOREM. Let ij/ be analytic and strictly concave. Let u be the solution of(\\). Then F(u) is an analytic Jordan curve (as a function of its arc length parameter). The demonstration relies on the resolution of a system of differential equations and the utilization of the system to extend analytically a conAMS 1970 subject classifications. Primary 35J20; Secondary 53A10.
25 citations
TL;DR: In this article, the instructional priorities and impediments in open area physical plants were contrasted with those in quasi-open area and traditional schools, and a questionnaire was administered to 212 teachers from 14 elementary schools in the Calgary Public School System.
Abstract: Authorities have suggested that the open plan school may be the first widely-adopted innovation in education not subjected to much apparent evaluation. This study was conducted to provide base-line information. The instructional priorities and impediments in open area physical plants were contrasted with those in quasi-open area and traditional schools. A questionnaire was administered to 212 teachers from 14 elementary schools in the Calgary Public School System. The 14 schools included five schools of open area design, four quasi-open area, and five traditional schools. Rank orderings and “T” tests were performed comparing each school type with its counterpart on all items related to instructional objectives and impediments. Results are indicated.
2 citations