摘要:

The electrical forming phenomena on the etched surfaces ofn‐type Ge crystals by ac voltages were studied thermoelectrically. Remarkable improvements in the i‐v characteristics were obtained by applying appropriate forming voltages. The thermoelectric current observed on the etched surface showedn‐type direction but it was converted top‐type by the forming. It has also been found out that the thermo‐emf depends sensitively on the pressure of the whisker contact after the forming (and on the polished surface), while the dependence is small before the forming on the etched surface.Experimental results seem to show that some substance of relatively high resistivity and ofp‐type thermo‐emf is produced by the forming between the whisker metal and the Ge surface.

ISSN:0021-8979    

DOI:10.1063/1.1721232

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

Three uses for the Hall effect in germanium crystals are described. These are (1) use of Hall effect probes in measuring magnetic flux, (2) use of Hall effect in crystals to produce a pure product modulator, and (3) use of Hall effect in germanium crystals to produce a nonreciprocal transmission. If the resistances are shunted around such gyrators, the transmission can be made zero in one direction and finite in the other. In all these applications, use is made of a crystal orientation for which the cross magneto‐resistance effects are zero and the Hall effect constant does not vary with field by more than 2 percent out to a flux density of 20 000 gausses. This orientation was located by making a phenomenological study of the magneto‐resistance and Hall effect corrections for a cubic crystal and evaluating constants experimentally. Correction terms to fourth and fifth powers of the magnetic field have been obtained.

ISSN:0021-8979    

DOI:10.1063/1.1721233

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

In connection with Galt and Herring's observation on thin whiskers of tin, the properties of a screw dislocation in a cylinder are worked out. When all boundary conditions are taken into account, the image force tends to keep the dislocation along the axis. Only when it is displaced about half‐way to the surface does the image force tend to pull it out of the rod. Generators of the cylindrical rod become helices when the dislocation is introduced. The dislocation can be ejected from the rod by twisting or bending it suitably.

ISSN:0021-8979    

DOI:10.1063/1.1721234

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

By the use of the reversion method certain types of ordinary nonlinear differential equations can be reduced to a set of ordinary linear differential equations which may conveniently be solved by the Laplace transform. The expression for the general member of the linear set is developed and written out in detail for certain illustrative terms. The method is applied to two simple problems for which the answers are exactly known so that some idea may be obtained as to the excellence of the approximations supplied by this method.

ISSN:0021-8979    

DOI:10.1063/1.1721235

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

This paper deals with resonance effects in circularly cylindrical solid bodies of high‐&egr; dielectrics such as titanates, these bodies being either not metallized or partly or fully metallized by fired‐on silver. The high dielectric constant has two pronounced effects:(a) Miniaturization, a linear reduction in size in the order of magnitude of 1/100, and(b) Realization of boundary conditions approaching infinite wave impedance.All four combinations of radial and axial wave impedance being zero (metallized) or infinite (interface dielectric/air) are investigated mathematically and experimentally. Special consideration is given to degenerated modes; that is, modes for which the axial dimensions of the cavity do not contribute to the resonance wavelength. Because of the inherent magnetic leakage through the dielectric, this is only conditionally true. These modes are therefore termed quasi‐degenerated.In contrast to conventional cavity theory dealing only with metallic boundaries, quasi‐degeneratedTEmodes are realizable; namely, if the faces of the cylindrical cavities are not metallized. These cavities can be tuned by introducing magnetic rods into them or by application of conductive disks outside of them in the proper position.A novel type of antenna can be evolved from theTE010∞∞mode, comprising a dielectric spiral encircling a magnetic rod.In many cases the relatively high temperature coefficient, dissipation factor, and noise level prevent for the time being the potential application of these high‐&egr; dielectrics.

ISSN:0021-8979    

DOI:10.1063/1.1721236

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

A bubble in a liquid pulsates and generates a changing pressure field. This reacts with a submerged flexible solid and induces elastic motions. Equations are derived which show how the vibration modes and frequencies of the solid are modified by the presence of the water, and how each mode is excited by the bubble pulsation. The generalized force for each mode is proportional to the volume acceleration of the bubble. The initial analysis presupposes incompressive flow, but it is shown that the results remain applicable if the duration of any compressive phase is small compared to the pulsation period of the bubble and the vibration period of the solid.

ISSN:0021-8979    

DOI:10.1063/1.1721237

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

Forced oscillations with nonlinear restoring force are studied in transient states as well as in steady states. The original differential equation characterized by a nonlinear term is transformed under certain restrictions to the following differential equation of the first order:dy/dx=Y(x,y)/X(x,y).Following Poincare´ and Bendixson, the singularities and the integral curves of the above equation are discussed, the former being correlated with the periodic states of oscillations, the latter with the transient states of oscillations. The stability of the periodic solutions is determined in accordance with that of the singular points,viz., according to the roots of the characteristic equation. The integral curves yield the relationship between the given initial conditions and the periodic solutions. Thus, once the initial conditions are prescribed, we can foresee the final periodic states which are started with those conditions.With this method of investigation, we have first studied the harmonic oscillations presented in Part I and then the subharmonic oscillation of order ⅓ given in Part II. In both cases the theoretical results are compared with the experimental measurements carried out for an electric circuit containing a saturable iron core, and the satisfactory agreement is found between them.

ISSN:0021-8979    

DOI:10.1063/1.1721238

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

A procedure for the synthesis of generalRCtransfer functions by means of unbalanced networks is described. The transfer function need not be minimum phase but may have zeros anywhere in the complex plane except on the positive real axis. Use is made of the technique of zero shifting as in the Guillemin procedure; but the additional use of a network theorem divides the desired network into two parts, with a consequent reduction of the problem to two simpler problems. Zero shifting can now be performedin two directions from within the total network. The theorem plus a method of using fewer paralleled ladders yield a final network with fewer ladders and fewer elements than that given by the Guillemin procedure. In the illustrative example given, twenty‐six elements are used, whereas the Guillemin procedure would use sixty‐six.

ISSN:0021-8979    

DOI:10.1063/1.1721239

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

1. Assuming that the elementary molecular deformation process conforms to the Maxwell model, and that the molecular elastic forceGiand viscous force &eegr;iare functions (of unspecified forms) of the free energy of activationF*, the following expressions for the dynamic modulusGdand dynamic viscosity (internal friction) &eegr;dare obtained:Gd=1A0∞&ohgr;2&tgr;i2Gi&phgr;(F*)&ohgr;2&tgr;i2+1dF*,and&eegr;d=1A0∞&eegr;i&phgr;(F*)&ohgr;2&tgr;i2+1dF*,whereA=area of sample, &tgr;i=Gi/&eegr;i, &ohgr;=vibration frequency, and &phgr;(F*)dF*=thenumberof elementary processes having activation energies lying betweenF* andF*+dF*.2. By employing an expression relating the relaxation time &tgr;iwithF* for the elementary process, and adopting the so‐called ``box'' distribution of relaxation times, the following explicit form for the distribution of activation energies is deduced:&phgr;=const(1/kTF*−1/F*2),wherek=Boltzmann's constant andT=absolute temperature. When the box distribution, as represented by this explicit form for &phgr;, is introduced into the foregoing expressions forGdand &eegr;d, the integrated results are found to predict temperature and frequency dependencies which are in gratifying agreement with experiment.

ISSN:0021-8979    

DOI:10.1063/1.1721240

出版商:AIP    

年代:1953

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1721242

出版商:AIP    

年代:1953

数据来源: AIP