摘要:

It is well known that the small‐signal behavior of long electron beams may be analyzed in terms of propagating space‐charge waves, suggesting an equivalence between such beams and longitudinally moving transmission lines. This in turn suggests the analysis of such electronic devices as the traveling‐wave amplifier, double‐stream or electron‐wave amplifier, and multicavity magnetron, in terms of coupled distributed‐parameter transmission lines moving relative to each other. It is shown that this approach is equivalent to a rigorous field‐theory analysis in certain cases of particular interest, and the procedure for calculating the significant distributed parameters is indicated. Final results for the idealized helix and thin cylindrical electron beam are presented.

ISSN:0021-8979    

DOI:10.1063/1.1699947

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

The theory of flexural motions of elastic plates, including the effects of rotatory inertia and shear, is extended to crystal plates. The equations are solved approximately for the case of rectangular plates excited by thickness‐shear deformation parallel to one edge. Results of computations of resonant frequencies of rectangular,AT‐cut, quartz plates are shown and compared with experimental data. Simple algebraic formulas are obtained relating frequency, dimensions, and crystal properties for resonances of special interest in design.

ISSN:0021-8979    

DOI:10.1063/1.1699948

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

The resistance to accelerating movement of objects in a fluid is normally evaluated with a mass term in the equation of motion that is greater than the actual mass of the object by an added mass described as a constant times the displaced mass of fluid. This added mass has been evaluated by numerous investigators for different body shapes from potential flow considerations. Published experimental results, mostly with oscillating systems with small amplitudes of motion, show an added mass constant that is higher than that derived from potential flow with values that are dependent upon the fluid and the object size. A few previous experiments on resistance in unidirectional accelerated motion indicate that the added mass is variable and depends upon the state of motion.The present investigation includes a development from model law considerations that results in a resistance equation of the formF=C12&rgr;V2S. This is identical with the normal resistance equation for steady state except for the coefficientCwhich, in addition to being a function of Reynolds' modulus, Froude's modulus, and the geometry, is also a function of a modulus,AL/V2, whereAis the acceleration,Lis a characteristic length, andVis the velocity.Experiments with circular disks moving perpendicular to the plane of the disk under the action of approximate constant driving forces show this resistance coefficient to be correlated by the modulusAL/V2.

ISSN:0021-8979    

DOI:10.1063/1.1699949

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

Equations for the modes and eigenvalues of two‐dielectric layered rectangular wave guides with cross sections as in Fig. 1(a), (b), and (c) are derived. From these equations are plotted graphs of cut‐off frequency over a range of geometric and dielectric parameters sufficiently wide to cover most requirements of design.

ISSN:0021-8979    

DOI:10.1063/1.1699950

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

In an enclosure at constant temperature, the radiation is that of a ``blackbody,'' and the demon cannot see the molecules. Hence, he cannot operate the trap door and is unable to violate the second principle. If we introduce a source of light, the demon can see the molecules, but the over‐all balance of entropy is positive. This leads to the consideration of a cycleNegentropy→Information→Negentropyfor Maxwell's demon as well as for the scientist in his laboratory. Boltzmann's constantkis shown to represent the smallest possible amount of negative entropy required in an observation.

ISSN:0021-8979    

DOI:10.1063/1.1699951

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

The laws of statistical thermodynamics are used for the definition of entropy, and it is shown that the definition of information can be reduced to a problem of Fermi‐Dirac statistics or to a generalized Fermi statistics. With these definitions, the entropy of a certain message can be defined, and the information contained in the message can be directly connected with the decrease of entropy in the system.This definition leads directly to the formulas proposed by C. E. Shannon for the measure of information, and shows that Shannon's ``entropy of information'' corresponds to an equal amount of negative entropy in the physical system. The physical background of the whole method is discussed and found in agreement with previous discussions.

ISSN:0021-8979    

DOI:10.1063/1.1699952

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

By sintering wires to flat metallic blocks, diffusion interfaces were obtained between the following pairs of metals: Cu‐Ni, Au‐Ag, Cu‐Ag, Cu‐Fe, Fe‐Ni, Cu‐Zn, Ni‐Zn, and 70/30 brass‐Cu. The interfaces were subsequently investigated metallographically. Grooves were observed in the lower melting point component in the vicinity of the sintered interfaces. This is attributed to the faster diffusion rate in the lower melting point metal.

ISSN:0021-8979    

DOI:10.1063/1.1699953

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

A formulation is presented of the scattering and absorption of gamma‐rays in different materials. The range of gamma‐ray energies considered is from 1 to 10mc2. Results are given for the transmission of gamma‐rays through air and lead.

ISSN:0021-8979    

DOI:10.1063/1.1699954

出版商:AIP    

年代:1951

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1699956

出版商:AIP    

年代:1951

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1699957

出版商:AIP    

年代:1951

数据来源: AIP