摘要:

A cavity resonator with input and output couplings represents a two‐terminal‐pair network with an infinite number of natural modes of oscillation. In some cavities of special shape, a number of degenerate modes with identical natural frequencies can be found. In a single cavity, various numbers of these degenerate modes can be coupled together to form a chain of coupled circuits by perturbing the otherwise ideal geometrical configuration of the cavity. The filter behavior is prescribed, and the two‐terminal‐pair network realizing this is obtained by a process of synthesis.

ISSN:0021-8979    

DOI:10.1063/1.1700114

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

The electric potential across a metallic pipe is investigated when current enters and leaves through two diametrically opposite points and the pipe is either empty, filled with a conducting fluid, or lined with a thin film of the fluid.

ISSN:0021-8979    

DOI:10.1063/1.1700091

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

The increase &Dgr;Tin average gas temperature for ac and dc has been determined from measurements of the increase in pressure. A small McLeod gauge was used. Wall temperature was regulated. Corrections for end effects were made by comparing results for long and short tubes of 3.6 cm diameter. Assuming the radial variation of heat input to be parabolic, the temperature distribution was calculated using published values of heat conductivityK. From the results the heat inputPmper centimeter length was calculated. This value was compared with the elastic lossPccomputed from electron temperatureTeand number of electronsNeper centimeter column, taking into account the variation of mean free path with electron velocity. Good agreement was obtained for mercury pressures ranging from 1 to 25 microns, with the arc current 0.2–0.6 ampere and the argon filling pressure 3.5 mm (Hg).

ISSN:0021-8979    

DOI:10.1063/1.1700092

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

A new experimental technique is presented for studying rate processes in solids. The method, termed ``pulse‐annealing,'' involves direct heating of a very small sample to a chosen annealing temperature for a short period, followed by rapid cooling to some fixed temperature for an in‐place physical property measurement. The method is a very flexible one, as the above cycle may be repeated to obtain any desired time‐temperature history. General experimental techniques are described and specific application to graphite and metals noted.The annealing process is examined theoretically. A method is described for deriving the activation energy of the fundamental relaxation process from the isothermal annealing curves of a physical property, the physical property being used as an index of the annealing process. It is shown that the activation energy is derivable without knowledge of the relation between the measured physical property and the fundamental kinetic variable. For further kinetic analysis (determination of rate constants and orders of reaction), however, it is necessary to know this relation. The analysis of isothermal and tempering experiments is compared.

ISSN:0021-8979    

DOI:10.1063/1.1700093

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

The kinetics of ordering in AuCu has been studied using electrical resistivity as the index of order. A purely phenomenological analysis of isothermal resistivity‐time curves showed that ordering in this alloy is a process characterized by a single constant activation energy of 29 kcal. For further kinetic analysis, it is necessary to transform the raw data into isothermal order parameter‐time curves. This was accomplished via Muto's theoretical relation between resistivity and the Bragg‐Williams order parameter,S.A consistent kinetic picture was obtained in terms ofS, with the ordering process accurately described by a simple third‐order rate equation with all the kinetic constants fully evaluated. The usual ln (rate constant)versus1/Tplot gave an activation energy of 28.5 kcal in excellent agreement with the phenomenological activation energy. Further experiments showed that the proposed kinetics predicts correctly the response to complex time temperature sequences.

ISSN:0021-8979    

DOI:10.1063/1.1700094

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

This paper presents a brief theoretical review of the viscous and free molecular flow phenomena. The equations which describe these two types of flow are applied to flow through porous media and are combined to yield a semi‐empirical equation which may be used not only for the viscous and free molecular flow, but also for the transition region between these. Experimentally determined limiting values of the ratio of molecular mean free path to pore diameter are reported. These ratios may be used to indicate the nature of flow in a porous media provided the pore size is known, or they may be used to determine pore size experimentally.

ISSN:0021-8979    

DOI:10.1063/1.1700095

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

It is shown that the Walther and Andrade equations, while very satisfactory for moderate ranges of temperature, are not adequate to define the dependence of the viscosity of liquid normal paraffins on temperature over extended ranges. One method of developing a viscosity‐temperature relationship is presented that gives equations defining this dependence with satisfactory validity. The purpose of this paper is to show that the precise dependence of the viscosity of liquids on temperature is complicated. This is in contrast to the relatively simple relation for the precise dependence of the viscosity of liquids on free‐space which will be presented in subsequent papers.

ISSN:0021-8979    

DOI:10.1063/1.1700096

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

The previous theory of linear reversible creep is extended and permanent (plastic) deformations are taken into consideration. General relations are established between the distribution functions of relaxation times of stress, and retardation times of strain. A particular type of distribution function is considered in detail and it is discussed in a qualitative way how the existence of a plastic component in creep affects the distribution function of relaxation times.

ISSN:0021-8979    

DOI:10.1063/1.1700097

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

The possibility of using a ferroelectric substance (barium titanate) as a medium for storing information is described. Preliminary experiments were performed to determine the necessary conditions for inscribing and erasing electrostatic preorientation in barium titanate ceramics at a temperature somewhat below the Curie point. The results suggest the possibility of a memory device that can be operated in the range of audio‐frequencies or higher.

ISSN:0021-8979    

DOI:10.1063/1.1700098

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

An exact solution in closed form is presented for the displacements, stresses and total elastic energy for the problem of an ellipsoidal isotropic inclusion bonded to an isotropic body of infinite extent when the inclusion and the infinite solid have uniformly distributed changes in their stress‐free specific volumes. The physically important details of the dependence of the total strain energy of the two materials upon the shape and volume of the inclusion, the elastic moduli of the two isotropic materials and the changes of specific volume, are included. The solution is indicated for the stresses and displacements for the case where the material at infinity is, in addition to the above condition, in a homogeneous state of stress whose principal directions are parallel to the axes of the cavity.

ISSN:0021-8979    

DOI:10.1063/1.1700099

出版商:AIP    

年代:1951

数据来源: AIP