ISSN:0021-8979    

DOI:10.1063/1.1714865

出版商:AIP    

年代:1942

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1714866

出版商:AIP    

年代:1942

数据来源: AIP

摘要:

THIS chapter deals with: (1) mechanical processes involving viscosity, particularly (a) impregnation, (b) breathing, (c) oil migration with respect to high voltage cables; (2) chemical processes involving viscosity, such as (a) Voltol process, (b) wax formation in cables, (c) polymerization of styrene; (3) electrical conductivity. With regard to the latter, the fundamental quantities, besides viscosity, that determine the conductivity are discussed, together with the various experimental methods whose interpretation allows the quantities in question to be computed.

ISSN:0021-8979    

DOI:10.1063/1.1714867

出版商:AIP    

年代:1942

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1714868

出版商:AIP    

年代:1942

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1714869

出版商:AIP    

年代:1942

数据来源: AIP

摘要:

The view is now generally held that in bars containing circular holes or other discontinuities the state of stress ceases to be two‐dimensional when the ratio of the radius of the holerto the thickness of the bartis less than unity. It is further believed that the factor of stress concentration in thick bars is materially smaller than in thin bars. This view also forms the basis for the doubts which have arisen regarding the reliability of certain theoretical work on stress concentrations produced by very small holes. In this paper results are reported from a photoelastic investigation using both elastic and frozen (see reference 4, Chapter 10) stress patterns and showing that the present point of view is erroneous. Experimental results show that no deviation from a state of plane stress can be found in bars with central circular holes whenr/tis of the order of magnitude of about ¼ instead of unity. Experiments further show that the factors of stress concentration remain essentially the same in thick as in thin bars. The present work may also be taken as experimental corroboration of the theoretical value for the factor of stress concentration obtained by Neuber for a very small hole in a bar in tension or compression.

ISSN:0021-8979    

DOI:10.1063/1.1714870

出版商:AIP    

年代:1942

数据来源: AIP

摘要:

Previous investigations on the variation with frequency of the initial inner permeability &mgr;Lof iron reveals great disparity of results. In this experiment certain refinements of technique and of analysis have been introduced which make the accuracy adequate for comparison with theory. The method used was to determine the change in resonant frequency of a coil and condenser combination caused by insertion of a permeable sample in the field of the coil. This change in frequency is interpreted as being caused by change of flux through the coil. The same iron wire had been measured previously over a different frequency range by other men working in this laboratory. The value of &mgr;Lwas found to be ∼60 over the frequency range from 30 kc to 40 mc showing no dispersion region between these limits. Results of this method are compared with those of other methods.

ISSN:0021-8979    

DOI:10.1063/1.1714872

出版商:AIP    

年代:1942

数据来源: AIP

摘要:

A chart is constructed for converting the apparent magnetic permeability to the true permeability of cylinders of any given ratio of length to diameter. The curves are based on previous calculations in which account was taken of the variation of the demagnetizing factorNwith permeability, but in which the permeability was assumed constant over any one cylinder. The flux distribution has been determined experimentally in several cylinders, and as the field acting on the specimen is increased from zero, the positions of the effective poles have been found to move toward the middle of the rod until (if the permeability is sufficiently high) they are located about 0.7 of the distance from the middle to the ends, and then to move toward and approach the ends as limits as the permeability declines in high fields.

ISSN:0021-8979    

DOI:10.1063/1.1714873

出版商:AIP    

年代:1942

数据来源: AIP

摘要:

The forced oscillations of a perfectly‐conducting prolate spheroid of eccentricity nearly unity are shown to be decomposable into ``harmonics'' corresponding to different modes of vibration, each harmonic being quantitatively connected with a certain portion of the impressed electric field which drives the antenna. The harmonics contribute additively to the current and field of the spheroid; each offers a characteristic impedance to the driving field, and the properties of the antenna are a composite depending upon the proportions of the various harmonics present. The behavior of the harmonics with frequency is discussed qualitatatively; analytical expressions obtained are useful chiefly at the resonant frequencies of the antenna, where the most important harmonic becomes sinusoidal in character.

ISSN:0021-8979    

DOI:10.1063/1.1714874

出版商:AIP    

年代:1942

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1714875

出版商:AIP    

年代:1942

数据来源: AIP