摘要:

The theory presented in this article was developed in an attempt to describe the observed motion and plastic deformation of clamped metal diaphragms used in certain underwater explosion experiments and in certain mechanical gauges. The theoretical attack on this problem enables one to set up certain equations of motion, which may be solved in finite form under certain conditions. The solutions enable one to specify, for instance, the final deformed diaphragm profile, the distribution of thickness after deformation, the swing‐time, which is the total time for deformation to take place, and many other quantities.The simplest case, termed the ``elementary approximation,'' turns out, except for relatively minor details, to describe adequately for many purposes the motion and final shape of the diaphragm; it is found that the deformed diaphragm shape is conical, the thickness distribution shows a marked dimpling at the center of the diaphragm, and the swing‐timetsis, to this order of approximationtS=a/c, whereais the radius of the diaphragm, andcis the square root of the ratio of the ``yield stress'' to the density. These results are all in good agreement with experimental facts.

ISSN:0021-8979    

DOI:10.1063/1.1699815

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

The article shows how lines of force of various magnetic fields can be visually depicted in three dimensions by means of a gas discharge. The method is illustrated by several photographs proving especially its applicability when investigating fields of small geometrical dimensions.

ISSN:0021-8979    

DOI:10.1063/1.1699812

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

A theoretical examination is made of the problem of the electromagnetic fields of electric dipoles in the presence of an infinitely long, perfectly conducting cylinder. Application of the Green's function method to this problem yields expressions for the fields in terms of an integration in the complex plane. Simplified expressions for far zone fields are obtained through the known result of the complex integration for the far zone conditions. Results are given for both circular and elliptic cylinders. In the latter case, it is possible to treat the problem of dipoles in the presence of a ground plane which is finite in one dimension and infinite in the other, since this is equivalent to an elliptic cylinder with a vanishing minor axis. Polar diagrams of calculated far zone fields are included for a number of cases.

ISSN:0021-8979    

DOI:10.1063/1.1699813

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

The polynomial formulation of the linear array problem introduced by Schelkunoff is studied from the point of view of potential theory. An electrical analogy results which is not only very helpful in qualitative thinking about the problem, but which also makes possible the construction of an analog computer for the synthesis of arrays to produce a desired radiation pattern, and for the evaluation of existing arrays. Such a computer has been built, and tested on known patterns with remarkable success.Several theorems concerning the effect of the roots of the polynomial on the magnitude and phase of the space factor of an array are given. Some of the most important consequences of these are the lack of uniqueness in the array synthesis problem, and the evaluation of known methods of synthesis which consider only constant‐phase patterns.A method of analysis is sketched which in principle does the same thing as the computer, and the difficulties in applying this are described. It is concluded that the computer would be preferable for a wide range of practical problems.

ISSN:0021-8979    

DOI:10.1063/1.1699814

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

The circular diffraction antenna consists of a coaxial wave guide fitted with an infinite‐plane conducting baffle, and open to free space. An equivalent circuit description, appropriate to principal‐mode propagation in the coaxial region, is investigated theoretically. Variational expressions for the circuit parameters are derived, and used for accurate numerical evaluation.

ISSN:0021-8979    

DOI:10.1063/1.1699816

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

Present digital storage devices use two space coordinates or time and one space coordinate for selection switching, resulting in bulky construction or long access time. Three‐dimensional arrays with efficient high speed selection appear possible after continued development of rectangular‐hysteresis magnetic materials. An operating mode is suggested which depends on ability of the magnetic material to discriminate between two values of magnetizing force which differ by a 2:1 ratio. Only one magnetic core per binary digit is required. Tests show that most existing metallic magnetic materials switch in 20 to 10,000 microseconds and are too slow. Nonmetallic magnetic materials can now approach the required magnetic behavior; they switch in less than a microsecond.

ISSN:0021-8979    

DOI:10.1063/1.1699817

出版商:AIP    

年代:1951

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1699818

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

This paper outlines a theory of excitation of oscillations under the rather slow variations of a parameter on which a system depends. The basic equation is a Mathieu equation. The basic method consists in reducing the system to polar coordinates and applying perturbations.

ISSN:0021-8979    

DOI:10.1063/1.1699819

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

The geometrical optical arguments underlying the equivalent earth's radius approximation are extended to non‐horizontal rays. The appropriate wave equation for a non‐uniform, but spherically symmetric, region is derived in a natural way. The notion of a ``primary field'' with the formeikR/Rat the source is dropped in favor of a solution to the wave equation in terms of a Green's Function. The formal solution thus obtained is seen to contain the known solutions for a uniform medium. For the non‐uniform case, the solutions to the radial equation are found by a technique due to Langer. These functions account for the index variation near the earth without making unwarranted assumptions about the behavior at greater heights. The formal series obtained is summed by the Watson technique. The first term in this series (lowest mode) alone determines the field at large distances and indicates that one may account for standard atmospheric refraction by using an effective earth's radius.

ISSN:0021-8979    

DOI:10.1063/1.1699820

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

The experimental pressure distribution data from low speed wind tunnel tests at zero angle of attack on two different conical noses attached to a cylindrical after‐body are compared with theory. The simplified theoretical equation used is a higher order approximation valid up to the orderr4lnr. It is shown that the conical nose with a vertex angle of 20 degrees is in agreement but the larger cone with a vertex angle of 30 degrees shows a discrepancy between the measured pressures and the approximate theory. In both cases, however, the theory is in excellent agreement with the surface pressures on the cylindrical after‐body.

ISSN:0021-8979    

DOI:10.1063/1.1699821

出版商:AIP    

年代:1951

数据来源: AIP