Determination of the foaming parameters of polyurethane compositions from the velocity of longitudinal ultrasonic waves

1979 ◽  
Vol 15 (3) ◽  
pp. 316-317 ◽  
Author(s):  
V. M. Mel'nikov ◽  
�. A. Putnin'sh ◽  
V. O. Putninya ◽  
V. P. Karlivan
Keyword(s):  
Ultrasonic Waves ◽  
Longitudinal Ultrasonic Waves

scholarly journals Ultrasonic attenuation in lead

1963 ◽  
Vol 271 (1344) ◽  
pp. 88-104 ◽  
Keyword(s):  
Magnetic Field ◽  
Ultrasonic Attenuation ◽  
Absolute Magnitude ◽  
Transverse Magnetic ◽  
Ultrasonic Waves ◽  
Acoustic Oscillations ◽  
Connected Surface ◽  
Sample Orientation ◽  
Longitudinal Ultrasonic Waves

The absorption of longitudinal ultrasonic waves has been studied as a function of transverse magnetic field in pure single crystals of lead at 1.2 °K. The results were found to be generally consistent with the Fermi surface of lead suggested by Gold. In particular a detailed study of the magneto-acoustic oscillations, as a function of sample orientation and field direction, allowed the determination of some of the dimensions of the hole surface in the second Brillouin zone and revealed a number of new electronic orbits on the multiply-connected surface in the third zone. The absolute magnitude of the attenuation and its dependence on propagation direction and on magnetic field was studied and the results interpreted in terms of the general theory of ultrasonic absorption.

Attenuation and Velocity of Ultrasonic Waves in Amorphous Selenium in the Vicinity of the Glass Transition

1977 ◽  
Vol 32 (9) ◽  
pp. 946-951
Author(s):  
Erwin Kittinger
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Ultrasonic Waves ◽  
Amorphous Selenium ◽  
Approximate Determination ◽  
Stabilization Process ◽  
Nonequilibrium States ◽  
Longitudinal Ultrasonic Waves

AbstractAttenuation and velocity of longitudinal ultrasonic waves have been measured in a-Se in the vicinity of the glass transition. Both quantities are shown to be affected significantly by the stabilization process below the glass transition temperature Tg. Equilibrium values of sound velocity are also reported for the range 25 °C to 45 °C. The decrease (increase) of attenuation (velocity) during stabilization is reversed at higher temperatures. The connection of both quantities is discussed in terms of an effective temperature which allows the approximate determination of equilibrium values of attenuation (and possibly of other structure related properties) from measurements performed in nonequilibrium states.

scholarly journals A New Method of Predicting the Structural and Mechanical Change of Materials during Extrusion by the Method of Multiple Plastic Deformations

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2594
Author(s):  
Marta Harničárová ◽  
Jan Valíček ◽  
Milena Kušnerová ◽  
Zuzana Palková ◽  
Ivan Kopal ◽  
...  
Keyword(s):  
Grain Size ◽  
Close Correlation ◽  
Ultrasonic Waves ◽  
Technological Parameters ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
New Equation ◽  
Mechanical Change ◽  
Longitudinal Ultrasonic Waves

The formulation of the Hall–Petch relationship in the early 1950s has raised immense interest in studying the influence of the grain size of solid materials on their properties. Grain refinement can be achieved through extreme deformation. In the presented study, Equal-Channel Angular Pressing (ECAP) was successfully applied to produce an ultrafine-grained microstructure in a pure commercial Cu of 99.9 wt%. Samples were processed by ECAP at 21 °C for six passes via route A. A new equation of equilibrium that allows the exact determination of the number of extrusions and other technological parameters required to achieve the desired final grain size has been developed. The presented research also deals, in a relatively detailed and comparative way, with the use of ultrasound. In this context, a very close correlation between the process functions of extrusion and the speed of longitudinal ultrasonic waves was confirmed.

Age-Dependent Acoustic and Microelastic Properties of Red Blood Cells Determined by Vector Contrast Acoustic Microscopy

2012 ◽  
Vol 18 (3) ◽  
pp. 436-444 ◽  
Author(s):  
Esam T. Ahmed Mohamed ◽  
Albert E. Kamanyi ◽  
Mieczysław Pluta ◽  
Wolfgang Grill
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Mass Density ◽  
Healthy Person ◽  
Ultrasonic Waves ◽  
Acoustic Microscopy ◽  
Cell Parameters ◽  
Different Ages ◽  
The Individual

AbstractVariations of the mechanical properties of red blood cells that occur during their life span have long been an intriguing task for investigations. The research presented is based on noninvasive monitoring of red blood cells of different ages performed by scanning acoustic microscopy with magnitude and phase contrast. The characteristic signature of fixed cells from groups of three different ages fractionated according to mass density is obtained from the acoustic microscope images, with the data represented in polar graphs. The analysis of these data enables the determination of averaged values for the velocities of ultrasound propagating in the cells from the different groups ranging from (1,681 ± 16) m s−1in the youngest to (1,986 ± 20) m s−1in the oldest group. The determined bulk modulus varies with age from (3.04 ± 0.05) GPa to (4.34 ± 0.08) GPa. An approach to determine for an age-mixed population of red blood cells, collected from a healthy person, the age of the individual cells and the age dependence of the cell parameters including density, velocity, and attenuation of longitudinal polarized ultrasonic waves traveling in the cells is demonstrated.

The relation between the velocity of longitudinal ultrasonic waves and the strengths of rocks and ores in the sheregesh deposit (Gornaya Shoriya)

1966 ◽  
Vol 2 (4) ◽  
pp. 425-427
Author(s):  
V. V. Andrievich ◽  
S. E. Mogilevskaya ◽  
S. T. Nakhrov ◽  
G. P. Starkov
Keyword(s):  
Ultrasonic Waves ◽  
Longitudinal Ultrasonic Waves

The Effect of Hydrostatic Pressure on Physical Properties and Microstructure of Spruce and Cherry

Holzforschung ◽  
2000 ◽  
Vol 54 (1) ◽  
pp. 83-92 ◽  
Author(s):  
Voichita Bucur ◽  
Simone Garros ◽  
Claire Y. Barlow
Keyword(s):  
Hydrostatic Pressure ◽  
Structural Damage ◽  
Untreated Wood ◽  
Average Density ◽  
Ultrasonic Waves ◽  
Ultrasonic Velocities ◽  
Main Effect ◽  
Natural Wood ◽  
Effect Of Hydrostatic Pressure ◽  
Longitudinal Ultrasonic Waves

Summary The effect of hydrostatic pressure on the density, the ultrasonic velocities and the microstructure of spruce and cherry wood has been studied. Generally speaking, under hydrostatic pressure wood becomes less heterogeneous and less anisotropic than natural wood. In spruce, crushing and buckling of the thin-walled cells in the earlywood takes place. This also has the effect of disrupting the medullary rays, which assume a zig-zag path through the structure. Cherry has a much more homogeneous structure, and the main effect of the hydrostatic pressure is compaction of the vessels by buckling of the walls. The fibres are scarcely affected by the treatment. The width of the earlywood zone decreased after the application of pressure by 26% in spruce, and by 11% in cherry. The average density was increased by the hydrostatic pressure by 26% for spruce and by 46% for cherry. The densitometric profile of spruce demonstrates significant changes following the pressure treatment, with the minimum density DMin increasing and the maximum density DMax decreasing. For cherry, the densitometric profile is shifted rather uniformly towards higher densities, and the annual ring profile is spatially slightly compacted but otherwise similar to that of untreated wood. The anisotropy of wood (expressed by the ratio of acoustic invariants) decreased by 56% for spruce and by 33% for cherry. The structural damage in spruce is predominantly found in the radial (R) direction, and this corresponds to a reduction of 73% in the velocity of the longitudinal ultrasonic waves in the radial direction, VRR. In cherry, the structural damage is mainly in the transverse, T direction. The velocity of the longitudinal ultrasonic waves in the transverse direction, VTT is reduced by 44%. The medullary rays in cherry seem to be the most important anatomical feature influencing the propagation of ultrasonic waves.

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