Showing papers on "Network theory published in 1971"

Analysis of Simulatenous Faults by Two-Port Network Theory

Abstract: Simultaneous faults of common configuration may be described mathematically in terms of two-port network theory with one port for terminating the network at each fault point. Combining the sequence networks, with appropriate phase shifts, will then permit-direct solution of the network voltages and currents in a general way. This approach to solving for simultaneous fault quantities is very orderly and makes solution by hand computation or by computer more straightforward than previous methods.

Network analysis in geography - haggett,p and chorley,rj

Abstract: BOOK REVIEWS Network Analysis in Geography, by Peter Haggett and Richard J. Chorley New York: St. Martin's Press, London: Edward Arnold, 1969, xii + 348 pages. It is now more than a quarter of a century ago that the first fundamental con~ tributions to network analysis were published: among others, Koenig's [3] book on graphs, Horton's [2] work on the development of drainage patterns, and Hitchcock's [1] papers on transportation. flows. They initiated a startling growth of network theory which today occupies a solid position in research (operations research, geology, gTaph theory and others) as well as in urban and regional planning.· Even geography has begun to utilize at least part of the body of theory now available, and come up with some theoretical contributions on its own. Ample evidence is provided by the more than 400 items listed in the bibliography of Network Analysis in Geography, some 40 percent of which are publications by geographers or in geographic journals. A vast variety of spatial phenomena can formally be described by patterns of interconnected lines: pipelines, subways, rails, roads, drainage systems, political districts, economic regions, among others. The first chapter of the book treats these networks as graphs and provides elementary concepts and measures to study their topological structure: connectivity matrix, stream number and order, bifurcation ratio, various network jndices, the generation of shortest path matrices and com- binatorial cell arrangement~. Chapter two extends the graph theoretical approach by introducing metric concepts like length, shape, area, density, circuitry and sinu- osity. Obviously, the definition of network concepts cannot be a purpose in itself; they must be related to and interpreted in terms of other (geographic) variables. That this can and has been done is demonstrated through several examples of ap- plications. In a scientific context, however, the definition of concepts serves the con- struction of theory, and the few examples given in the book are essentially restricted t-0 Horton's various laws for stream networks and Shreve's corresponding deductions assuming randomness as the principal force. The subject of chapters three and four is the evaluation of network structures. The section on the efficiency of transportation networks in terms of the flow pattern they carry is short and disappointing in view of the existing literature. It includes the comparison of several alternative network designs with regard to the resulting flow distribution; some simulation results are reported. The following section re-