ISSN:0021-8979    

DOI:10.1063/1.1707629

出版商:AIP    

年代:1946

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1707631

出版商:AIP    

年代:1946

数据来源: AIP

摘要:

Relations between various parameters are obtained which describe the behavior of an accelerated electron beam which is caused to traverse an alternating electric field. In particular, a mechanicographical means for obtaining the gain or loss of energy is described. It is shown that under the most favorable conditions a maximum of 17 percent of the energy in the accelerated beam may be transferred to the alternating field. Application of these principles to a type of ultra‐high frequency oscillator is treated.

ISSN:0021-8979    

DOI:10.1063/1.1707635

出版商:AIP    

年代:1946

数据来源: AIP

摘要:

An electron optical system is described in which it is possible to obtain (1) high resolution electron diffraction patterns, (2) shadow electron microscope images, and (3) electron diffraction patterns of selected variable areas of the specimen. The change in mode of operation of the system is accomplished by electrical adjustments without changing the specimen position in any way. A number of phenomena related to the attainment of high resolution diffraction patterns are described. Pertinent details of the experimental apparatus are discussed and some representative results are shown.

ISSN:0021-8979    

DOI:10.1063/1.1707628

出版商:AIP    

年代:1946

数据来源: AIP

摘要:

The factors which determine image contrast in optical and electron micrographs are discussed in relation to a new metal shadow‐casting technique whereby the contrast of images is greatly increased by depositing obliquely a thin film of metal on the microscope preparations. Further advantages of the use of shadow‐casting are described, and an estimate is made of the lower limit of size of objects which should be observable by shadow‐casting. Examples are given and illustrations are shown of the applications of this technique to the electron micrography of particles of macromolecular dimensions, of replicas of such particles, and of surface replicas prepared in several ways.

ISSN:0021-8979    

DOI:10.1063/1.1707630

出版商:AIP    

年代:1946

数据来源: AIP

摘要:

The ratio of a.c. to d.c. resistances of iron wires and permalloy strips has been measured in the frequency range 1.5–6.0 megacycles per sec. Empirical equations obtained are compared with existing theoretical equations derived on the assumption of constant permeability.

ISSN:0021-8979    

DOI:10.1063/1.1707632

出版商:AIP    

年代:1946

数据来源: AIP

摘要:

A theory of the dynamics of capillary rise is developed by making certain assumptions as to the nature of the motion of the liquid in the tube. The most important assumptions are that the same forces act on the liquid when it is in an accelerated state of motion as when it is in a steady state, that the surface tension is constant, that the angle of contact between the meniscus of the liquid and the tube wall is constant, and that the wetting of the tube is not a rate‐determining factor of the motion. This theory leads to a second‐order non‐linear differential equation, the solution of which represents the motion of the liquid in the tube. A formal solution of the differential equation is obtained in the form of a double Dirichlet series. Approximations to the series are compared with experimental data, and it is concluded that the agreement between theory and experiment is satisfactory.

ISSN:0021-8979    

DOI:10.1063/1.1707633

出版商:AIP    

年代:1946

数据来源: AIP

摘要:

The problem of using shunt and series sections of transmission line as matching devices is here investigated mathematically. By making use of hyperbolic functions the condition of match for both cases can be expressed in a very simple way. Both devices when used alone have a limited range with regard to the impedance to be matched. The exact range within which matching is possible is shown graphically. By using one additional matching network each device can be designed to match impedance of any value. The complete systems still preserve their simplicity in structure.

ISSN:0021-8979    

DOI:10.1063/1.1707634

出版商:AIP    

年代:1946

数据来源: AIP

摘要:

Determinations of the tension‐temperature relation of stretched vulcanized rubber can provide us with data about the proportion of crystalline and amorphous components. The amount of crystalline material appears to be 30–32 percent at 600 percent elongation and at 20°C. An expression is derived relating percentage crystalline material and temperature. The results are in close agreement to those of x‐ray measurements carried out by Goppel but diverge largely from those obtained by Field. The cause of this difference is not yet quite clear. Stretched vulcanized rubber consists of a predominating amorphous phase with crystallites embedded in it. On stretching orientation occurs and a systematical addition of secondary valency forces is possible. This is the main cause of the existence of a certain tensile strength. Crystallization, though important as an indication on orientation, is more or less an incidental phenomenon. The distance function of the secondary forces may be of equal importance with the orientation.

ISSN:0021-8979    

DOI:10.1063/1.1707636

出版商:AIP    

年代:1946

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1707637

出版商:AIP    

年代:1946

数据来源: AIP