摘要:

A homogeneous sphere is surrounded by an infinite homogeneous medium. Heat is generated inside the sphere at a prescribed rate. The temperature distribution inside and outside the sphere is computed.

ISSN:0021-8979    

DOI:10.1063/1.1721398

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

A general method is developed for designing networks with arbitrary loss functions based on the potential analogy. An appropriate potential problem is formed on the basis of the given loss function by introducing continuous charge distribution on the complex frequency plane. After the potential problem is solved, the technique of quantization of charge is used to find the natural modes of the network function.

ISSN:0021-8979    

DOI:10.1063/1.1721399

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

This paper presents a method for the solution of a class of linear, second‐order differential equations with periodic coefficients of the Mathieu‐Hill type. The method is based on a procedure involving powers of matrices and is adequate for the study of a large class of physical problems. The stability of the solution is considered and the general method is illustrated by its application to typical special cases.

ISSN:0021-8979    

DOI:10.1063/1.1721400

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

The steady flow viscosity of a sample of polyisobutylene of viscosity‐average molecular weight 1.35 million, distributed by the National Bureau of Standards, has been measured from 15° to 100°C. Its logarithm is a linear function of 1/T2. Application of the method of reduced variables to dynamic mechanical data from −45° to 100°, previously reported for this polyisobutylene, yields composite curves reduced to 25°C for the real and imaginary parts of the complex compliance and complex shear modulus; the real part of the complex dynamic viscosity; and the mechanical loss tangent. The latter exhibits a broad and peculiarly asymmetric maximum. The reduced time scale extends from 1 to 10−9sec. The reduction factorsaTobtained in this way are slightly higher than those derived either from the viscosity or from stress relaxation measurements of Tobolsky and associates. The distribution functions of relaxation and retardation times have been calculated by second approximation methods and their detailed shapes are defined in the transition region between rubber‐like and glass‐like behavior. The relaxation distribution function is compared with the idealized distribution of Tobolsky.

ISSN:0021-8979    

DOI:10.1063/1.1721401

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

Impedance measurements made on a tape helix with an electron beam are described. Curves showing the measured impedances of the fundamental and first backward space‐harmonic components of the mode commonly used in traveling‐wave tubes are presented for values ofka(circumference to free‐space wave‐length ratio) ranging from 0.15 to 0.6. The impedance of the fundamental is found to be less than that calculated from the sheath model by a factor ranging from 0.8 to 0.3. Phase velocities of other modes and components were observed forkafrom 0.1 to 1.1; these agree with an analysis by Sensiper which predicts that certain values of the phase constant are not allowed for a single wire helix. A relationship for the impedance of one space‐harmonic component in terms of the impedance of its fundamental is presented in approximate agreement with the experimental data. In addition to providing impedance data over a wide frequency range, the helix tester performed as a continuously voltage tunable backward‐wave oscillator from 1500 to 4300 mc at a beam current of 1 ma.

ISSN:0021-8979    

DOI:10.1063/1.1721402

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

Response of pore pressure meter on variations in loading conditions of surrounding soil is retarded by the necessity that pore water has to enter the instrument. This property is introduced as an instruments coefficient influencing the boundary conditions. With regard to the surface of the instrument, two types are considered: a rigid type and a cavernous type. Att=0 for unit step loading, consolidation has not yet started and the response of the instrument depends on shear modulus of soil only. Calculation of response as a function of time involves three‐dimensional consolidation theory and is established with the aid of spherical solutions for simple harmonic and unit step loading conditions.

ISSN:0021-8979    

DOI:10.1063/1.1721403

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

When the temperature of the ocean changes with depth within a horizontal layer, it is accompanied by a change in the velocity of sound. The reflection of sound from such a transition layer depends on the incident angle and wavelength of the sound, the thickness of the layer, the manner in which the velocity changes, and the total amount of the change. The usual formula for reflection assumes a transition layer of negligible thickness. The reflection coefficient then depends only on the incident angle and the total velocity change. This case is treated and numerical values are given for the reflection coefficient under conditions of practical interest. It is then shown that for a gradual velocity change which corresponds to certain temperature data, the reflection coefficient for small glancing angles of incidence changes gradually with increasing layer thickness and may be approximated very closely by the usual formula. Quantitative comparison of the cases is made and the general applicability of the approximation is discussed.

ISSN:0021-8979    

DOI:10.1063/1.1721404

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

A method is outlined for estimating the probability of detection for a pulsed radar, assuming a randomly modulated carrier. For a square law detector closed forms for the moments of the distribution of the envelope are presented in terms of three different choices of the distribution of carrier amplitude, thus leading to an Edgeworth series representation of the desired probability. At least one choice of distribution of the carrier amplitude leads to closed forms for the moments for the case of a linear detector. Curves of probability of detectionvssignal‐to‐noise power ratio are constructed and cross checked by a method of numerical integration.

ISSN:0021-8979    

DOI:10.1063/1.1721405

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

A new continuous ultrasonic viscometer employing a pulsed resonant exponentially damped magnetostrictive strip is described and treated theoretically. Properties of viscoelastic materials affecting the propagation of transverse elastic waves are derived and are related to the response of the viscometer. Typical applications of the use of the ultrasonic viscometer are presented.

ISSN:0021-8979    

DOI:10.1063/1.1721406

出版商:AIP    

年代:1953

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1721408

出版商:AIP    

年代:1953

数据来源: AIP