摘要:

High vacuum incandescent lamp bulbs have been used as sensitive elements in stabilizing systems for ac power sources. Such a lamp is a nonlinear element and accordingly introduces distortion components into the stabilizer circuit. An analysis of the operation of the lamp is given, based on rather simple assumptions. This analysis allows the prediction of the distortion for given operating conditions and shows the effects of changes in frequency and current.

ISSN:0021-8979    

DOI:10.1063/1.1702274

出版商:AIP    

年代:1952

数据来源: AIP

摘要:

It is shown in this paper that exact expressions may be derived for the absorption factor for the intensity of Bragg reflection by a small euhedral crystal completely bathed in a parallel x‐ray beam. The expression is a sum of terms evaluated for subdivisions of the crystal determined according to discontinuities in boundary conditions imposed by the distribution of edges between the plane faces of the crystal. For a prismatic crystal of constant cross section, general expressions are derived for five general types of subdivisions in terms of the linear absorption coefficient and certain linear dimensions. Other expressions are also given for other types of subdivisions which arise in certain cases. The application of the method, including corrections for secondary extinction, is illustrated by calculations on tetragonal barium titanate.

ISSN:0021-8979    

DOI:10.1063/1.1702275

出版商:AIP    

年代:1952

数据来源: AIP

摘要:

The activity of this barium‐on‐tungsten cathode is maintained by dispensing barium from a pellet of barium compound. The dispensing mechanism is shown to be controlled by surface diffusion of barium over tungsten. Despite incomplete coverage of the emitting surface with barium, and almost complete absence of streaming of active material out through pores in the surface material, evaporation of barium is sufficient to be of concern in certain applications.

ISSN:0021-8979    

DOI:10.1063/1.1702276

出版商:AIP    

年代:1952

数据来源: AIP

摘要:

Existing information on the reduction of spurious signals from instrument cables is reviewed. A tentative theory is formulated to account for the known data. Subsequent experiments confirm this theory and allow the formulation of a detailed mechanism of noise generation in cables. The noise may be eliminated for practical purposes (reduced by a factor of 500 or more in some cases) by having continuous electrical conduction between both surfaces of the insulating dielectric and the adjacent conductors. A simple procedure is outlined to make short lengths of this cable for laboratory use, and an industrially applicable method is suggested. There appears to be no limit on how small the diameter of such cables could be made.

ISSN:0021-8979    

DOI:10.1063/1.1702277

出版商:AIP    

年代:1952

数据来源: AIP

摘要:

The solution of the problem of determining the permeabilities of petroleum reservoir rocks from measurements employing the flow of a gas through large cylindrical cores, transverse to the axis of the cores, is presented. This solution is obtained by solving the corresponding problem in potential theory, the method of conformal transformations of complex variables being employed. An electrolytic model study of this problem is described and a comparison of the theoretical and experimental solutions presented.

ISSN:0021-8979    

DOI:10.1063/1.1702278

出版商:AIP    

年代:1952

数据来源: AIP

摘要:

Conical surfaces of fracture generated in thick‐walled cylinders that were asymmetrically and impulsively loaded through the use of internal explosive charges are presented. It is deduced from qualitative considerations that the conical fractures result from the interaction between transient tensile stress waves. The two tensile stress waves that are responsible for the fracture arise from a single compressional stress wave that is reflected from two inclined free surfaces. The angle of fracture associated with these conical surfaces has been used to measure the velocity of propagation of the stress waves in low‐carbon steel, brass, copper, lead, and 24ST aluminum alloy.

ISSN:0021-8979    

DOI:10.1063/1.1702279

出版商:AIP    

年代:1952

数据来源: AIP

摘要:

Radiation characteristics are established for a turnstile antenna in a cylindrical shield. The antenna consists of perpendicularly crossed wires driven by a sinusoidal current distribution, harmonic in time, and differing in phase by 90° between members of the cross. The shield is assumed to be a perfectly conducting cylindrical can open at one end and its diameter is taken to be of the order of a fraction of the driving wavelength. The axis of the shield is perpendicular to the plane of the antenna, passing through its center. The excitation of an infinitely long circular wave guide by the above current distribution is considered first, and conditions under which only the dominant (TE11) mode is important are determined. The essential radiation problem can then be regarded as one in which a semi‐infinite circular guide, excited by aTE11mode, radiates into free space. This problem has been formally solved by Levine and Schwinger and, using their results, values of the reflection coefficient and gain function have been computed by the National Bureau of Standards, Institute for Numerical Analysis, University of California, Los Angeles. The results of this theory are compared with experiment and with the Kirchhoff method.

ISSN:0021-8979    

DOI:10.1063/1.1702280

出版商:AIP    

年代:1952

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1702282

出版商:AIP    

年代:1952

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1702284

出版商:AIP    

年代:1952

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1702285

出版商:AIP    

年代:1952

数据来源: AIP