ISSN:0021-8979    

DOI:10.1063/1.1707390

出版商:AIP    

年代:1944

数据来源: AIP

摘要:

Vaporization of pure liquids is reviewed as a problem of heat transfer and the rate of vapor bubble creation. Applying an idea of Gibbs, the influence upon the activation energy of nucleus formation exerted by the contact angle at the vapor/liquid/solid phase boundaries as well as by the shape and size of submerged solids is quantitatively expressed by the reduction in the volume requirement of the nucleus. Possible effects of solutes in superheated liquids upon steam bubble creation and growth are discussed. The stabilization of foam in boiling electrolyte solutions is explained by the thermoelectric potential differences originating from the temperature gradient around growing bubbles. The effect of foam inhibiting agents (e.g., castor oil) is interpreted as a change in the rate of bubble creation caused by surface conditioning of heating elements and suspended particles.

ISSN:0021-8979    

DOI:10.1063/1.1707391

出版商:AIP    

年代:1944

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1707393

出版商:AIP    

年代:1944

数据来源: AIP

摘要:

An essential step in the making of a silica replica by the Heidenreich technique consists in the evaporation of silica in a high vacuum. An alternate method for depositing silica has been investigated and is discussed in this paper. This method consists in the chemical deposition of silica from the compound SiCl4.

ISSN:0021-8979    

DOI:10.1063/1.1707394

出版商:AIP    

年代:1944

数据来源: AIP

摘要:

X‐ray diffraction theory is developed for the evaluation of long range order and short range order in the alloy Cu3Au, and experiments are described whereby each type of order was measured. Values of the long range order parameterSwere found to be 0.86 for 250°C, 0.81 for 370°C, and 0.79 for 380°C, the samples being held at elevated temperatures during the x‐ray exposures. At the critical temperatureTc=388°C,Ssuddenly dropped to zero. AboveTcshort range order was found to exist, the amount present being specified by a set of parameters &sgr;iwhich are associated with the interatomic distancesri. The dominant short range order parameter &sgr;1, referring to nearest neighbors, was evaluated as 0.50 for 540°C and 0.25 for 750°C.

ISSN:0021-8979    

DOI:10.1063/1.1707395

出版商:AIP    

年代:1944

数据来源: AIP

摘要:

A description is given of apparatus for measuring the relative ability of rubbed‐down monolayers of polar lubricants to maintain low friction under test conditions which do not permit replacement of the lubricant. This quality of a lubricant is called its ``durability.'' The clean polished rim of a slowly rotating steel wheel rubs on the monolayer deposited on a polished steel flat. An account is given of the preparation of the surfaces and films. It was not found possible to prepare reproducible test surface‐monolayer combinations, hence it was necessary to compare each lubricant with a standard deposited on a separate area of the same surface. Significant differences are found in the relative durabilities of a number of polar compounds. For the monocarboxylic acids tested, the values are found to increase with the number of carbon atoms per molecule. An investigation of the stability of rubbed‐down monolayers on polished stainless steel shows that aging in a desiccator causes a continuous decrease in durability, and also a decrease in molecular orientation as shown by electron diffraction. Similar reduction of durability and orientation results when the film is flushed with a fine stream of benzene. On chromium also the orientation is destroyed by the solvent, but the durability is not changed.

ISSN:0021-8979    

DOI:10.1063/1.1707396

出版商:AIP    

年代:1944

数据来源: AIP

摘要:

The theory of the symmetrical multivibrator has been developed in a form which makes possible the computation of the period and the currents in the tubes in a relatively simple manner. The method is largely graphical. The behavior of the corresponding Eccles‐Jordan trigger circuit is first determined and a ``trigger'' characteristic constructed, giving the values of the grid voltages of each tube when triggering takes place and the corresponding values of the currents in the tubes before and after triggering. From this characteristic, with slight changes, the operating conditions and the period of the multivibrator circuit are determined. It is found that the grid currents play an important part in determining these conditions and the period. The method was applied to an actual circuit and the computed values agreed well with the experimental results. The effect on the period and operating conditions of varying the parameters is discussed theoretically and the conclusions are compared with experiment.

ISSN:0021-8979    

DOI:10.1063/1.1707397

出版商:AIP    

年代:1944

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1707398

出版商:AIP    

年代:1944

数据来源: AIP

摘要:

A certain type of definite integrals occurring often in the evaluation of mutual impedance of antennas is solved by the use of differential equations.

ISSN:0021-8979    

DOI:10.1063/1.1707399

出版商:AIP    

年代:1944

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1707400

出版商:AIP    

年代:1944

数据来源: AIP