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This report deals with an experimental investigation on the drawing method of the molten polymer of P. P. by means of an air jet nozzle. Fig. 1 is a structural diagram of the air jet nozzle, which was designed in such a way that the jet air may reach the sonic velocity at nozzle pressures above 2.18kg/cm2. The air flow below the outlet of the jet nozzle was observed by schlieren method in the form of shock waves as shown in Fig. 2. In the drawing process, considering the force balance on the running yarn at the point of jet nozzle, the fineness of the yarn should possess a limiting value. Fig. 9 shows the calculated values of the limiting fineness at various positions of the jet nozzle from the spinneret and at various air pressures in the nozzle. Fig. 10 shows the results obtained from the experimental values. These values are compared in Table 1. The load-elongation curves of the yarns are shown in Figs. 13-16, and their birefringenes (Δn) in Figs. 17 and 18.

Axial sound speed and depths of the SOFAR channels in the North and South Atlantic have been estimated and the seasonal variations that affect SOFAR propagation examined. The estimates are derived from applying averaging techniques to archived oceanographic data. The computed values appear to agree within one part in a 1000 with the measured data from long-range propagation experiments. A more accurate sound speed mapping method is recommended, as is the incorporation of measured values of speed and depth in any SOFAR computer program. (Author)

An exact integral expression is given for the velocity potential produced by a harmonic point source located in a semi‐infinite isovelocity space. A transition layer separates the source region from a second constant‐velocity layer. A depth‐dependent sound speed with two adjustable parameters is employed for the transition region. The velocity potential for the lateral wave is obtained using the method of steepest descent. The results are in agreement with those for the special case of the linear transition layer.

Fluctuation phenomena occurring in a system of 216 water molecules, studied by molecular dynamics at 1 g ${\mathrm{cm}}^{\ensuremath{-}3}$ and 10 \ifmmode^\circ\else\textdegree\fi{}C, indicate that (i) transverse currents persist in the form of propagating collective coordinates even for a wavelength of about 20 \AA{}, with indications that the same will happen for much longer wavelengths. The velocity of propagation is 1.05 \ifmmode\times\else\texttimes\fi{} ${10}^{5}$ cm ${\mathrm{sec}}^{\ensuremath{-}1}$. In the region of 20 \AA{} the lifetime of the fluctuation appears to increase linearly with increasing wavelength. (ii) Density fluctuations at 20 \AA{} are found to be propagating but only marginally; the corresponding velocity of sound is 1.8 \ifmmode\times\else\texttimes\fi{} ${10}^{5}$ cm ${\mathrm{sec}}^{\ensuremath{-}1}$. (iii) The spectrum of density fluctuations exhibits a secondary maximum at a much higher frequency than the normal frequency of sound propagation and it is suggested that experiments should be directed to the region of this "high-frequency sound."

High-porosity graphite contains two regions in which the speed of the USO varies with the pore size. When the pores are small relative to the ultrasonic wavelength, the USO speed increases within increase in the pore diameter to about 400μ (ratio of the USO wavelength to the mean pore diameterλ/¯D=3–4) and then decreases. The experimental results do not conflict with the analytically predicted relations between the USO speed on the one hand and the overall porosity, pore diameter variance, and Poisson's ratio for the intervening material on the other. The theoretical relation was calculated on the basis of MacKenzie's model of a porous material from the equations of the effective elastic moduli. An analysis was made of the relation between the resistivity of the specimens and the size of the pores. The resistivity data obtained confirms, together with the known thermal conductivity data, the validity of the above hypothesis about the variation of the speed of the USO. The results of this investigation can be used for a more precise determination of variations in the density and strength of graphite products.

A study of the influence of fluid motion on the emission of higher‐order acoustic modes from a stationary source in a duct is presented. In particular, the ratio between the upstream and downstream higher‐order mode amplitudes is calculated. This ratio has been measured for the (1,0) mode in a rectangular duct at flow velocities from zero to 0.25 times the sound speed. The frequency dependence has also been measured at a fixed flow Mach number of 0.1.

In the northern Sargasso Sea, recent continuous vertical profiles horizontal velocity and sound speed have revealed strong current shears of large horizontal extent and of inertial frequency in regions of low sound‐speed gradient. The influence of shear on ray paths is particularly evident in restricted regions in which the sound‐speed‐gradient is smaller than the current shear. Stability considerations pertaining to stratified shear flow suggest that shear refraction is most likely to be of importance when the ratio of the vertical gradient of sound speed (CZ) and the Brunt‐Vaisala frequency (N) is of order one. A simple model illustrates that rays emitted or vertexing within a layer of large shear, but small sound‐speed gradient, will be significantly refracted. Moreover, since the interaction is not isotropic, the reciprocity theorem does not apply and the effects of shear on ray paths are dependent on the direction of the ray with respect to the current.

This paper describes a technique for measuring the speed of sound in molten salts employing a pulse method. The signal coming from the sample is made to coincide with that coming from a delay line of a variable length of water. The intervening parts between the emitting and receiving crystals are made of sintered alumina. The calculation of corrections due to the intervening parts and the calculation of error are given in detail. The technique is applied to measure the speed of sound in potassium bromide, alkali sulphates and the chromate, molybdate and tungsten of sodium. [Journal translation]

A dynamic and mechanical study was made of relaxation effects in two types of polyimide at temperatures of — 180–420°. It was shown that in polyimide prepared from diphenyloxide tetracarboxylic acid and diaminodiphenyl ether (DPE) at a temperature lower than 235° an unusual relation is observed between acoustic parameters and crystallinity: with an increase in crystallinity, the velocity of sound and the dynamic modulus decrease. Above 235° the conventional relation is observed between the velocity of sound, elasticity modulus and crystallinity. It was concluded from acoustic investigations that there is a difference in supermolecular organization of polyimides of DPE and polyimide prepared from benzophenone tetracarboxylic acid and diaminodiphenyl ether.

The properties and structure of natural cellulosic fibers were investigated by sonic velocify, visible dichroism and x-ray diffraction methods. The following results were obtained: (1) There is a good agreement between the orientation factor determined from the x-ray diffraction method and the visible dichroism of dyestuffs. (2) A linear relation exists between the sonic velocity (C) and the orientation factor from x-ray diffraction (fx); C=8.54fx-0.72(km/sec)for0.6

Recent measurements of the heat capacity at constant pressure Cp for lead from 300 to 850°K have shown that Cp for liquid lead decreases continuously from the melting point to 850°K. Using data in the literature of density and velocity of sound, the dilation correction has been applied to Cp to obtain the heat capacity at constant volume Cv for liquid lead. Application of the dilation correction to solid lead gives a Cv curve which uncreases only about one joule/gm-atom-°K from 300 to 600°K, whereas the Cv curve for liquid lead decreases almost 5 joules/gm-atom-°K from 600 to 850°K. A careful assessment of the uncertainty in the quantities used in the dilation correction leads to an uncertainty in Cv of ± 2.5% (about one joule/gm-atom-°K), and thus the decrease in Cv for liquid lead is quite real.

The results from the literature on acoustics in suspensions, excluding the phenomena of relaxation, have been applied to study the effects of red‐cell and plasma densities, compressibilities, viscosities,thermal conductivities, and surface tension on the propagation of sound in blood. For the calculations of the viscous and the thermal absorptions and of the velocity of sound in blood, the red cell may be treated as a rigid spherical particle containing the same volume. For the calculation of the thermal absorption, the erythrocyte may be treated as a spherical particle of finite thermal conductivity at all frequencies; but for the calculation of the velocity of sound, the effect of heat conduction can be ignored above 1 MHz and Wood's soundvelocity formula may be used. The calculated sound absorption due to shear viscosity and thermal conduction in whole blood constitutes a significant portion (about 60% or more) of the measured value of the total absorption toward the lower‐frequency range (1 MHz or less) and a negligible portion (about 15% or less) of the total absorption toward the higher‐frequency range (10 MHz or more).

When solids are subjected to high-pressure shock-wave loading, multiple stress waves propagate with velocities dependent upon the elastic and inelastic compressibilities of the solid. The present paper shows that the inelastic or plastic waves in cubic and hexagonal single crystals do not necessarily propagate with the bulk sound speed as they do in isotropic elastic-plastic solids. This result is a consequence of anisotropy in the plastic deformation which depends on the slip plane orientation in the crystal and has important consequences with regard to the determination of compressibilities from shock-wave data. In particular, for wave propagation in the directions of cubic crystals the departure from the bulk velocity can be significant (5–25 per cent). For wave propagation normal to the c -axis in hexagonal crystals, the plastic wave velocity also differs from the bulk sound speed (10–25 per cent). Plastic wave velocities are tabulated for a number of cubic crystals on the basis of the various slip systems common to these materials. The calculated velocities are then compared with experimental data on shock-loaded single-crystal aluminum and sodium chloride.

We have demonstrated that stimulated Brillouin scattering can be used to measure the velocity of sound in shock‐compressed fluids with 1% precision. We have constructed a ruby laser which can be triggered by a Pockels cell as the shock wave reaches a predetermined point in the sample. The primary limit of accuracy is the lack of precise data for the refractive index at higher pressure. We have also measured the shock velocity U s in terms of the material velocity U p. The data have been fitted to the relation Us=1.4932+1.9615Up+0.0750Up2 km/sec for water below 15‐kbar shock stress.

As a continuation of a previous paper [Japan. J. appl. Phys. 6 (1967) 1351], this paper describes an improved apparatus for measuring the absorption coefficient and velocity of sound in liquids at frequencies from 10 kHz to 700 kHz. The principle of the method consists of measuring the resonance frequency fR and decay-rate D of acoustic energy in a spherical vessel filled with a liquid. The velocity and absorption coefficient of a test liquid are evaluated by comparing fR and D between the test liquid and the reference liquid of a known velocity and absorption coefficient. The electronic circuits have been considerably improved compared to the previous apparatus and as a result, the stability, sensitivity, and ease of operation of the apparatus have been increased. Data for MgSO4 solutions are presented as examples.

Within several meters of the ocean surface there are enough ambient bubbles to create a distinctive microstructure with a dispersive acoustic index of refraction. In this region, the variation of total bubble‐volume fraction produces fluctuations of the sound speed for frequencies less than about 25 kHz; the frequency spectra of these speed fluctuations are near Gaussian. However, perturbation of resonance frequencies of predominant bubble populations is the principal cause of fluctuations of the speed between 25 and 100 kHz; these fluctuations have frequency spectra that are imitations of the spectrum of the sea surface height which creates them.

The effects of an assumed Rossby wave on density, pressure, current, and sound speed are examined and analyzed. It is shown that the zeroth‐mode wave solution has only slight effect on sound speed, while the first‐mode solution is significant. A dispersion relation is developed, having as one solution an east‐west wavelength of 210 nautical miles and a period of 114 days, for parameters consistent with the Sargasso Sea area. This first‐mode solution predicts the gross behavior of observed sound speed versus depth variations, and provides striking agreement with measured curves of constant sound speed. The addition of a second‐mode solution to the first leads to a crossover of sound‐speed profiles in qualitative agreement with observations.

The dependence of bulk sound speed Vφ upon mean atomic weight m and density ρ can be expressed in a single equation: V φ =Bρ λ ( m 0 m [ 1 2 +λ(1−c)] ( km/sec ) Here B is an empirically determined “universal” parameter equal to 1.42, m 0 = 20.2 , a reference mean atomic weight for which well-determined elastic properties exist, and λ = 1.25 is a semi empirical parameter equal to γ − 1 3 where γ is a Gruneisen parameter. The constant c = (∂ ln VM/∂ ln m ) X , where VM is molar volume, is in general different for different crystal structure series and different cation substitutions. However, it is possible to use cFe = 0.14 for Fe2+Mg2+ and GeSi substitutions and cCa ≅ 1.3 for CaMg substitutional series. With these values it is pos to deduce from the above equation Birch's law, its modifications introduced by Simmons to account for Ca-bearing minerals, variations in the seismic equation of state observed by D.L. Anderson, and the apparent proportionality of bulk modulus K to VM−4.

An experimental program to compress liquid deuterium with a two-stage gun is described. A xenon standard was used to check the adequacy of the EOS of the Dural container in the 7000 (1.7 Mbar) to 3000° K (0.0 Mbar) range. The agreement is reasonable. Further work on this standard is in progress to improve the accuracy. The target design parameters were checked with some sound speed measurements which confirm the liquid-like behavior of Dural at the temperatures, pressures, and strain rates of these experiments. The uncertainties of the results are analyzed and tabulated with the data. Comparison between the molecular and the metallic equations of state indicates a small volume change on metallization due to the high compressibility of the molecular phase vis-a-vis the metallic phase.

Lighthill's acoustic analogy is used to study the sound radiated from free flows without dissipation, in the limit as the sound speed tends to infinity. If the flow is of non-uniform density, the most efficient source is not the velocity quadrupole term discussed by Lighthill, but a dipole-order term whose radiated intensity scales on the sixth power of velocity. The physical mechanism is the same as that described by Rayleigh, in his work on sound scattering.

The phenomenological approach has been used to study analytically the acoustic wave second harmonic generation in piezoelectric semiconductors in the presence of the d.c. electric and an oscillating electromagnetic field (OEF). It has been suggested that the second harmonic acoustic flux (SHAF) can be enhanced considerably by the application of an OEF polarized in the direction of the propagating acoustic wave. The SHAF exhibits a maximum at Ω = ω, where Ω is the frequency of the OEF and ω is the frequency of the acoustic wave. The SHAF also shows a maximum at d.c. electric fields for which the average drift velocity of the carriers is equal to the velocity of sound. It is found that for a typical case of n -type nondegenerate InSb (77°K, n = 2·5 × 10 14 cm −3 ) that the SHAF is enhanced by a factor of 10 3 over its value in the absence of OEF. The present analysis is valid in the low frequency region only (i.e. ql ≪ 1).

The information presented in this paper is directed to those industrialists and researchers interested in molecule and near micron and submicron particle sampling by a convenient, inexpensive, and sufficiently accurate method. The use of two sonic flow impingers in series is predicted to collect 98-99% of a phosphoric acid aerosol having a mass median diameter of 0.7 p. The first impinger of a new design is shown, in field sampling, to collect simultaneously 90-98% of the aerosol and 95% of molecular fluoride compounds. On the same aerosol, the standard Greenburg-Smith impinger shows a low collection performance, less than 50% at 1 cfm and 65% at sonic velocity. The use of a first impinger at sonic flow greatly simplifies sampling procedures by eliminating the need for a test meter and associated pressure and temperature measurements. Also, for small particle sizes isokinetic sampling is not necessary and sampling line losses by deposition are shown to be less than 1%. The low initial cost of the sampling...

Zn and Sn have been deformed plastically by an ultrasonic system operating at 22.5 kHz. The amplitude dependence of the internal friction was correlated with the presence or absence of twins. Friedel's relation between the dimensions of a twin formed in a burst from a single source was found to hold for Zn but not for Sn. Assuming that each twin forms during a single stress pulse, the rate of operation of a Frank‐Read source is found to be physically reasonable for Zn, with a dislocation velocity approaching the speed of sound, but too high for Sn. We conclude that the assumption that twins form in a single burst is justified for Zn, giving a linear growth rate ≳3×102 m/sec, but not for Sn, implying a slower growth rate.

A simplified analysis of the dependence of the elastic properties and electrical conductivity of a carbon fiber on its orientation index is presented. The experimentally confirmed inverse correlation between the electrical resistivity and the speed of sound makes it possible to calculate the modulus of elasticity of carbon fibers from data on the bulk resistivity.

Measurements of the velocity of sound in saturated and compressed fluid methane are reported. Measurements were made on the saturated liquid from 91 K to 186 K and on the compressed fluid along selected isotherms from 100 K to 300 K at pressures to about 35 MN m −2 . Data were combined with newly available PϱT data to obtain the isentropic compressibility and the ratio of the specific heats. Measurements along the higher temperature isotherm were limited to densities greater than about 10 mole l −1 at 300 K increasing to about 14 mole l −1 at 210 K due to the large low pressure sound attenuation in methane.

Simultaneous velocity and attenuation measurements are reported for the [111] and [010] open orbits in copper using 52-MHz compressional waves propagating in the [\ifmmode\bar\else\textasciimacron\fi{}101] direction. The two-phase continuous-wave resonance technique applied to a sharp open-orbit resonance is shown to be useful for measuring one of the physical constants $\frac{e}{\mathrm{ch}}$, the lattice constant, or the velocity of sound if the other two are well known. The behavior of the dispersion near the [111] open-orbit resonance seems to imply that the effective force on the lattice is different for electrons drifting parallel and antiparallel to $\stackrel{\ensuremath{\rightarrow}}{\mathrm{q}}$.

Stress-corrosion crack propagation in U-4 1/2 wt%Nb has been monitored with crack-opening displacement and acoustic-emission techniques. Excellent correlation was obtained between the direct crack-velocity measurements and the emission count rate at all stress intensities. The data also show that, as the cracking velocity increases, the counts per unit area of new crack surface increase. The results of the investigation show the feasibility of acousticemission detection techniques as a useful stress-corrosion testing tool.

Techniques are developed for computing ray‐acoustic intensity in a horizontally stratified moving medium. Under the assumptions that the speed of sound and the components of the wind vector are piecewise linear functions, it is shown that an exact expression for the intensity can be obtained by patching together functions with the aid of a table of integrals. For the general horizontally stratified moving medium, the ray paths and the intensity can often be approximated by numerically solving a system of ordinary differential equations.

In order to effectively use a ray tracing model it is advisable to determine its sensitivity to small perturbations in the velocity of sound. A model to compute transmission loss based on ray theory and using cubic splines for the sound velocity profile is presented and its sensitivity is examined. The sound velocity profile is perturbed randomly and the mean and standard deviation of the transmission loss is computed.

In an unbounded medium with a bilinear sound‐speed profile composed of two constant‐gradient layers separated by an interface at the depth of minimum sound speed, SOFAR rays are generated which are continuously refracted towards the channel axis. The existence conditions for real roots of the acquiring‐ray cubic and quartic equations treated herein facilitate the determination of the caustic equations. When the condition is imposed that the discriminant of the cubic or quartic equation be zero valued, the caustic equation emerges as the boundary line along which repeated roots occur. Two general cases are examined: (a) receiver and source in same layer, and (b) receiver and source in different layers. Explicit, closed‐form solutions are obtained for most of the caustics by exploitation of reciprocity considerations and by reduction‐to‐single reflection or crossing arguments. Only rays which cross the interface without undergoing either a surface or bottom reflection are treated.

Experiments were performed to obtain information concerning the action of high velocity liquid jets impacting at velocities that erode the target surface (1000–4000 fps, 305–1200 mps). Nozzle pressure, impact force and target temperature data were obtained using a quasisteady flow system at pressures up to 146,000 psi (1007 MN/m2). Under no-flow conditions, the system was used to determine liquid compressibility for a diester synthetic hydraulic fluid. The jet flow data are compared to results from a calculational model for quasisteady flow.

We study spherical waves in a linear viscoalastic solid,r 0

We study spherical waves which are produced by a weak spherical explosion in a linear viscoelastic solid. The wave front, final displacement, and stress fields, and the large time velocity and stress signals are examined. It is shown that the large time velocity and stress signals are dominated by a wave which has the character of a diffuse N wave propagating with the equilibrium speed of sound and decaying inversely as the square of the radial distance.

Physical properties of materials of interest in fast reactor safety are presented. These include enthalpy and heat capacity, vapor pressure, density, surface tension, speed of sound, viscosity, and thermal conductivity. The emphasis is on saturated fuel materials and coolant. Much of the data is the result of direct experimental measurement while the remainder was obtained by extrapolative techniques from data at lower temperatures.

The velocity of sound, W, in liquid argon has been measured with an estimated accuracy of 0.2% at temperatures from 90 to 160 K, and at pressures up to 3400 atm, using a double-transducer acoustic interferometer operating in the frequency range 1.1 to 7.3 MHz. The WPT results, which are in good agreement with previously published data (P < 500 atm), have been used with the PVT equation of state to calculate adiabatic compressibilities for the liquid up to the melting curve. A corresponding-state comparison of the WPT equations of state of liquid argon and liquid krpton (P < 680 atm) shows that with the proper choice of only two independent scale factors, the reduced sound velocities agree to within the experimental accuracy of the measurements.

Explosive sound sources were detonated at shallow depths in two long‐range deep ocean experiments. Signals were recorded from a shallow hydrophone in the first experiment (May 1967) and from a SOFAR channel hydrophone in the second (May 1969). The propagation was strongly influenced by subsurface sound channels. The shot arrival patterns were analyzed by a graphical method to determine the convergence zone locations and the average sound speed in the subsurface channel. In the first experiment the bottom was flat and the medium could be characterized by a single velocity profile having a weak subsurface channel. Numerous bottom reflections were observed. In the second experiment the bottom was rough. Two profiles were required to characterize the medium, one of which exhibited a strong subsurface channel. Bottom reflections were not in evidence. Energy was detected which traveled more than 800 km entirely within the subsurface channel.

We have applied the strong coupling polaron theory to the piezoelectric polaron. We obtain an energy-momentum relation which is quadratic at small $P$, and approaches a straight line with slope equal to the speed of sound at large $P$.

Both the intermediate-coupling theory and a strong-coupling theory appropriate for a moving polaron give an anomalous energy-momentum relation, $E(P)$, for the piezoelectric polaron. This relation starts out quadratic at small $P$, but at large $P$ it asymptotes to a straight line with slope equal to the speed of sound $s$. It is shown that the states represented by this anomalous $E$ vs. $P$ relation are such that the electron is clothed by its concomitant lattice distortion and that this lattice distortion becomes larger as the polaron velocity $v\ensuremath{\rightarrow}s$. This indicates that in this limit an increasing number of phonons are gathering in the "phonon cloud" around the electron. In both theories the constant lattice-potential surfaces become flattened in the forward and backward directions as the polaron starts to move.