摘要:

A numerical method is described which enables the effect of thin wires upon a given electrostatic field to be calculated, in the case when the wires are straight and of uniform circular cross section. A brief description is given of a problem to which the method has been applied, and of the results obtained.

ISSN:0021-8979    

DOI:10.1063/1.1722942

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

The initial waves created by the sudden release of a spherical volume of compressed air in a limitless environment of air at constant state are predicted analytically using an iterative method of solution by characteristics for the case of a specific weak blast. Pressure‐time records have been obtained within the compressed air and in the immediate environment of the spherical blast during its early stages using a pyramidal shock tube. The experimental results corroborate the existence and position in time and space of the inner and reflected shock waves predicted analytically. The present results for a weak spherical blast are in substantial agreement with the analytical and experimental results obtained previously by other investigators for a considerably more powerful blast. The shock tube, in pyramidal or conical form, appears to offer considerable promise for further research on spherical blast phenomena.

ISSN:0021-8979    

DOI:10.1063/1.1722943

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

Measurements are presented of (a) the emission density from clean and oxygen covered molybdenum surfaces as a function of the arrival rate of Ba or of Ba+BaO and of (b) the migration length of Ba and of Ba+BaO over oxygen covered molybdenum surfaces. The emission density is comparable to that obtained from similarly activated tungsten surfaces, but the minimum arrival rate of total barium required for complete surface coverage is much higher than for the tungsten case. The migration length is also comparable for the two systems.

ISSN:0021-8979    

DOI:10.1063/1.1722944

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

Equations have been developed for the transparency factor applicable to the intensity of x‐rays scattered from very weakly absorbing materials in the standard diffractometric technique. The expressions differ from the standard absorption correction because of the variation of effective scattering volume with angle. Both equations and illustrative curves are presented.

ISSN:0021-8979    

DOI:10.1063/1.1722945

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

Measurements are reported of the magnetic susceptibility of neutron irradiated quartz as a function of irradiation time. The results are interpreted in terms of the density of centers produced by the irradiation and are compared with optical and x‐ray studies of neutron damaged quartz.

ISSN:0021-8979    

DOI:10.1063/1.1722946

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A method is described for measuring saturation magnetization in a ring sample. This permits the measurement of saturation and of low‐field magnetic properties in the same sample. The method consists of saturating the sample in a strong field directed perpendicular to the plane of the ring, changing the direction of the magnetization slightly with a circumferential field, and measuring the resultant flux change in the ring. The procedure also gives an accurate value for the cross‐sectional area of the secondary winding on the specimen.

ISSN:0021-8979    

DOI:10.1063/1.1722947

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

When certain restrictions are applied to the radial component of flow it is possible to obtain an exact solution to the Navier‐Stokes equations describing the steady‐state flow of an incompressible fluid in an annulus having porous walls. The effects of such restricted radial flows on the characteristics of the flow field have been examined.

ISSN:0021-8979    

DOI:10.1063/1.1722948

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

When the dc conductivity of the material is not negligible, the low‐frequency part of the Cole‐Cole plot loses its distinctive shape. A complementary representation in terms of complex conductivity is proposed, in which a simple Debye mechanism again results in a semicircle. However, a nonzero value of dc conductivity does not cause this representation to lose its distinctive shape in the low‐frequency range. Examples of the utility of this representation are given.

ISSN:0021-8979    

DOI:10.1063/1.1722949

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

An experiment is described in which the growth of vapor bubbles at a surface is followed in detail. Growth curves are obtained and shown to agree, within experimental error, with current theories of growth under idealized conditions, provided an average superheat present at the initiation of growth is used in the calculation. A criterion is proposed to permit an estimate of a delay time for vapor formation. The estimated delays are found to be in qualitative agreement with those measured.

ISSN:0021-8979    

DOI:10.1063/1.1722950

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A mathematical study has been carried out on the discriminatory properties of an array of photoconducting receivers subjected to an influx of photons. Those photons not absorbed by the first receiver pass on to the second receiver and so on until all the initial photons are absorbed. The capture of a photon is indicated by an increase in receiver conductance. Analysis of the problem reveals that if the receiver thicknesses are permitted to vary in a prescribed way interesting response differences result for photons having different energies. Under certain conditions, these response differences can be used to resolve two classes of photons differing in energy into a spectrum.

ISSN:0021-8979    

DOI:10.1063/1.1722951

出版商:AIP    

年代:1958

数据来源: AIP