摘要:

The object of this paper is to derive a general correlation theorem for a class of complex stochastic processes of a real argument. By means of this theorem, the correlation functions and the time‐power spectral densities, which are defined by averaging the realizations of the processes and their running spectra, respectively, are related to each other by a pair of one‐dimensional integral transformations. This theorem is reduced to corresponding theorems for other classes of stochastic processes which form subsets of the set of processes under consideration. The properties of the correlation functions and time‐power spectral densities along with questions concerning conditions for the existence and usefulness of these concepts in scientific and engineering applications occupy a good portion of this paper.

ISSN:0021-8979    

DOI:10.1063/1.1659664

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

This paper describes how to couple equations describing pressure and shear waves of elastic materials with equations describing pressure waves in fluids. The media treated are homogeneous and occupy doubly infinite slabs of finite thickness. As a result, the transmission and reflection coefficients for a baffle composed of a finite number of slabs of elastic and fluid materials are obtained. These concepts are useful in the determination of transmission and reflection of sonar baffles, ocean bottom, etc. Limits can be taken, letting the thickness of a fluid layer go to zero, to see the effects of lubricated boundaries in baffles, etc.

ISSN:0021-8979    

DOI:10.1063/1.1659665

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

The diffraction pattern produced by reflection of monochromatic light from an ultrasonic surface wave composed of a fundamental and higher harmonic frequencies is calculated for a Gaussian and a uniform light surface illumination. The diffraction pattern is found to be asymmetric with respect to the central order. This asymmetry is calculated from available diffraction data on LiNbO3.

ISSN:0021-8979    

DOI:10.1063/1.1659666

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

A new glass, composed of TeO2, was found to be well suited to acousto‐optical devices. It exhibits a high figure of merit: Me(p2n6/&rgr;v3) = 23.9×10−18sec3/g and has very good optical qualities with regard to visible light.

ISSN:0021-8979    

DOI:10.1063/1.1659667

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

The pressure dependence of the long‐wavelength transverse‐optic‐phonon frequency of KI and RbI was determined by infrared transmission measurements. The mode Gru¨neisen parameters thus obtained compared well with those calculated from a rigid ion model using Born‐Mayer‐type potentials. The phase transition to CsCl structure at appropriate pressures was noted for both crystals, accompanied by a lowering of thek→≃0TO phonon frequency. Infrared transmission measurement and its pressure dependence confirms that the mixed‐crystal system K1−xRbxI forms an intermediate class of mixed‐crystal system ``half‐way'' between the ``two‐mode''‐ and ``one‐mode''‐type mixed crystals.

ISSN:0021-8979    

DOI:10.1063/1.1659668

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

The greatest difficulty in measuring magnetic field generated by the heart's electrical activity is in eliminating noise from other sources. The common mode portion of the noise was rejected by using a magnetometer with a pair of differentially connected superconducting flux transformers. The high sensitivity associated with the two Josephson junction quantum interference device permitted highly resolved magnetiocardiograms of quality comparable to the normal electrocardiogram, without the use of shielded enclosures or signal averaging.

ISSN:0021-8979    

DOI:10.1063/1.1659669

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

In well‐made polycrystalline alumina ceramics subjected to external forces, fracture originates at surface flaws. In this investigation, compressive surface layers were formed by quenching both glazed and unglazed alumina rods in various quenching media. Improvements in flexural strength, tensile strength, thermal shock resistance, and impact resistance were observed. The strength increases with increasing compressive surface force as indicated by rod tests. Therefore, in quenched alumina compressive surface layers prevent surface flaws from acting to cause failure.

ISSN:0021-8979    

DOI:10.1063/1.1659670

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

Ultrasonic pulse echo measurements on alumina bodies of porosities ranging from 1 to 40% show linear relationships between both the shear and longitudinal velocities and the total porosity. A quadratic relationship is deduced for the dependence of Young's and shear moduli on porosity. The values extrapolated to zero porosity agree reasonably well with results of other works. Poisson's ratio is constant within the limits of the experimental errors. The attenuation of the echoes increases substantially with increasing porosity. When the experimental results are compared with various theoretical models, it is clear that the ``dilute‐suspension'' models are incapable of fitting the observations. Among the ``elastic‐bound'' models, a cylindrical pore model seems to fit the data much better than a spherical model.

ISSN:0021-8979    

DOI:10.1063/1.1659671

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

The theory of steady‐state evaporation, which produces a vapor having the same composition as the alloy to be evaporated, is given. Equations are derived showing the composition of the evaporant, which is physically separated from the alloy feed, during the approach to steady state. The general case ofNcomponents is treated, and closed solutions are given for various special cases involving two, three, andNcomponents with different vapor pressures. Illustrative numerical examples are given.

ISSN:0021-8979    

DOI:10.1063/1.1659672

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

BaO displays a reversible phase transformation in the pressure range between approximately 110 and 180 kbar at room temperature. The high‐pressure modification is the first high‐pressure polymorph of an alkaline‐earth oxide to be observed directly. The x‐ray diffraction pattern of the high‐pressure from at about 180 kbar can be satisfactorily indexed as tetragonal witha= 4.397 ± 0.007 Å andc= 3.196 ± 0.005 Å. Although there are intensity discrepancies, the high‐pressure polymorph of BaO appears to have the structure of phosphonium iodide PH4I (SGP4/nmm), which is a distorted CsCl‐type structure, and contains 2 molecule per unit cell. A transformation to this structure results in a volume decrease about 11–14% at the phase transformation. This study has also been carried out up to pressures of about 290 kbar, no further phase change was observed and the axial ratioc/aappears independent of pressure within experimental error.

ISSN:0021-8979    

DOI:10.1063/1.1659673

出版商:AIP    

年代:1971

数据来源: AIP