Abstracts of Papers by Bell System Authors Published in Other Journals (01 September 1976)

Algorithm generates optimal object code for a machine with N ^ 1 registers and unlimited memory capacity when the dag is a binary tree. We define a subclass of dags, the 1-load binary dags, employing a tree-like grammar, and modify the Sethi-Ullman algorithm to include this subclass when N = 2 registers. The proof of optimality relies on the use of syntax directed translation schemas. ELECTRICAL AND ELECTRONIC ENGINEERING Asymptotic Theory of Scattering by a Rough Surface Progressing Over an Inhomogeneous Ocean. F. M. Labianca and E. Y. Harper, J. Acoust. Soc. Amer., 59 (April 1976), pp. 799-812. 

A general asymptotic theory of scattering by a moving rough surface is presented. The theory is valid for a slowly varying refractive index, and for ocean-surface wave heights that are small compared with the acoustic wavelength and the ocean-surface correlation length. In contrast with the Kirchhoff or physical optics approximation, this theory is valid when the acoustic wavelength and ocean-surface correlation length are of the same order. Differential Addressing of Clusters of Changed Picture Elements for Interframe Coding of Videotelephone Signals. B. G. Haskell, I E E E Trans. Commun., 2U (January 1976), pp. 140-144. 

In a conditional replenishment coder for videotelephony only those picture elements (pels) which have changed significantly since the previous frame are transmitted. Increased addressing efficiency for videotelephony results if clusters or changed pels are positioned not with respect to the beginning of the line, bat with respect to another cluster in the previous line or previous frame which has already been transmitted.