Accession Number : AD0684151

Title :   ESTIMATING THE PARAMETERS OF AN INHOMOGENEOUS MEDIUM BY PROBING WITH RAYS,

Corporate Author : RAND CORP SANTA MONICA CALIF

Personal Author(s) : Casti,J. ; Detchmendy,D. ; Kagiwada,H. ; Kalaba,R.

Report Date : FEB 1969

Pagination or Media Count : 20

Abstract : A computationally efficient technique using ray tracing and successive approximation to estimate the index of refraction of an inhomogeneous medium from the times of arrival of a transmitted signal at various receivers. The ray treatment can cope with a medium whose properties vary in two or three dimensions. The inverse problem can be solved iteratively by a search procedure, by a gradient procedure, or by quadratic convergence. Algorithms for computer solution are presented for quadratic convergence. To conserve high-speed storage, one ray at a time is evaluated until all the rays are considered at each iteration. In a numerical example using fourth-order Adams-Moulton integration with a step size of 0.1, computing time on the IBM 7044 was about half a minute. The initial approximation was a homogeneous medium but the estmate was refined in three iterations. First experiments indicate that the method is feasible even with noisy data. (Author)

Descriptors :   (*WAVE PROPAGATION, NUMERICAL ANALYSIS), (*REFRACTIVE INDEX, NUMERICAL ANALYSIS), ALGORITHMS, CONVERGENCE, APPROXIMATION(MATHEMATICS), FEASIBILITY STUDIES, NOISE(RADIO), PROPAGATION, SOUND, ELECTROMAGNETIC RADIATION

Subject Categories : Acoustics
      Optics
      Radiofrequency Wave Propagation

Distribution Statement : APPROVED FOR PUBLIC RELEASE