Abstracts of Bell System Technical Papers Not Published in This Journal (01 October 1951)

Natl. Electronics Conference, Proc.. v. 6, pp. 441 - 442 , 1950 . ABSTRACT--The carbon film type of resistor is particularly useful at high frequencies, for not only can it be made to have small reactance but it is, in effect, all skin so that there is no increase in resistance at high frequencies due to skin effect. The film is also well cooled through its intimate contact with the core and this makes possible the dissipation of large amounts of power per unit area. While primarily developed for high frequency applications in this country, the pyrolytic carbon resistor possesses other 1 * A reprint of this article may be obtained on request. 

Bell Tel. Labs. 1244 ABSTRACTS OF TECHNICAL ARTICLES 1245 characteristics which have led and are leading to greatly expanded fields of application. Principal among these are the tolerances of one per cent or better attainable in production, the stability in use, the relatively small and predictable temperature coefficient of resistance, and the low noise level. These properties result in large part from the ultimate crystalline structure of the carbon films. Some Methods of Solving Hyperbolic and Parabolic Partial Differential Equations. R. W. HAMMING.' International Business Machines Corp. Computation seminar. 

Proceedings, Dec., 1949, Ed. by C. C. Hurd. N. V., I.B.M., pp. 14-23, 1951. ABSTRACT--The main purpose of this paper is to present a broad, nonmathematical introduction to the general field of computing the solutions of partial differential equations of the hyperbolic and parabolic types, as well as some related classes of equations.