scholarly journals Immersion ultrasonic transducers

2021 ◽  
pp. 25-29
Author(s):  
Ortagoli Khakimov
Keyword(s):  
Attenuation Coefficient ◽  
High Temperatures ◽  
Ultrasonic Waves ◽  
Ultrasonic Transducers ◽  
Standard Measurement ◽  
Base Distance ◽  
Velocity Of Propagation ◽  
Measurement Uncertainties ◽  
The Difference ◽  
Controlled Object

The principles of operation and design of immersion ultrasonic transducers developed by the authors for excitation and reception of elastic vibrations in moving filament-like and plane-parallel materials, in particular, polymer fibbers and films, with an adjustable angle of input (reception) of probing signals into moving controlled object – polymer fibbers and films at normal and high temperatures. The technical characteristics of the installation are given in which the converters developed by us are used, namely, sounding base (distance from the emitter to the receivers), the duration of the probing pulses, the frequency of filling and the duration of the probing pulses, the speed of the controlled object, the combined standard measurement uncertainties of the difference Δt of the propagation times of ultrasonic waves from the emitter to the first and second signal receivers, relative combined standard uncertainties of measurements of attenuation coefficient and velocity of propagation of ultrasonic waves.

Ultrasonic relaxation processes in liquid triethylamine

1956 ◽  
Vol 237 (1209) ◽  
pp. 233-244 ◽  
Keyword(s):  
Activation Energy ◽  
Energy Barrier ◽  
Ultrasonic Waves ◽  
Relaxation Processes ◽  
Activation Energy Barrier ◽  
Temperature Range ◽  
Rotational Isomers ◽  
Velocity Of Propagation ◽  
Ultrasonic Relaxation ◽  
The Difference

Measurements have been made of the velocity of propagation and the absorption of ultrasonic waves in liquid triethylamine over the temperature range 25 to 70° C and at frequencies of approximately 23, 66, 107, 148 and 192 Mc/s. The absorption results demonstrate the existence of a relaxation process which is attributed to the perturbation by the sound wave of an equilibrium between rotational isomers. The activation energy barrier and the difference in energy between the states are evaluated from an analysis of the results. The calculated dispersion of velocity is less than 1%. Values of the specific heat of triethvlamine are required in the analysis and are given in the paper for the temperature range 25 to 60°C. The results are discussed in the light of other measurements concerned with rotational isomers.

Rectification of Acoustic Waves

1974 ◽  
Vol 52 (17) ◽  
pp. 1726-1730 ◽  
Author(s):  
S. S. Mathur ◽  
M. S. Sagoo
Keyword(s):  
Energy Density ◽  
Acoustic Wave ◽  
Acoustic Waves ◽  
Ultrasonic Waves ◽  
Pressure Amplitude ◽  
The Difference

The difference in the behavior of the denser and the rarer regions of a longitudinal travelling acoustic wave is utilized to produce the phenomenon of rectification of ultrasonic waves. It has been shown that, under appropriate conditions, the energy density of sound in the regions of rarefaction can be increased while in the regions of compression the energy density is decreased. It is found that under suitable conditions, the pressure amplitude in the rarer regions is about 4% larger than that in the denser regions. The measurement of this difference in amplitude can be used to determine the parameter of nonlinearity.

scholarly journals Estimating the Uplift Bearing Capacity of Belled Piers Adjacent to Sloping Ground by Numerical Modeling Based on Field Tests

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Yangchun Han ◽  
Jiulong Cheng ◽  
Weifeng Zheng ◽  
Shijun Ding
Keyword(s):  
Numerical Modeling ◽  
Bearing Capacity ◽  
Attenuation Coefficient ◽  
Slope Angle ◽  
Field Tests ◽  
Embedment Depth ◽  
Sloping Ground ◽  
Foundation Model ◽  
The Difference ◽  
The Impact

In order to evaluate the uplift bearing capacity of belled piers beside slopes, a series of numerical simulations are carried out based on field tests data. First, a number of uplift loading tests of full-scale belled piers are carried out on the project site of transmission line in Anhui Province, China. Second, a slope-foundation model for numerical modeling is proposed and calibrated based on field tests data. The behavior of belled piers adjacent to slopes subject to uplift load is studied by numerical modeling. The impact of three parameters, including distance (a) from the belled pier to the crest of the slope, slope angle (β), and embedment depth (h) of the belled pier, has been investigated on the uplift capacity of the belled pier. Based on the simulation results, an attenuation coefficient (ω) is put forward for evaluating the reduction of uplift bearing capacity of the belled pier. The results show that the coefficient ω is negatively correlated with distance a and depth h, and the influence of distance a is greater than that of depth h according to the results of variance analysis, but the difference is not significant by F test. Moreover, the empirical equation between attenuation coefficient ω and three key factors a, β, and h had been presented by a series of fitting.

scholarly journals The mechanism of the initiation and propagation of detonation in solid explosives

1932 ◽  
Vol 138 (834) ◽  
pp. 92-116 ◽  
Keyword(s):  
High Explosive ◽  
A Priori ◽  
Small Samples ◽  
Weight Of Evidence ◽  
Theoretical Treatment ◽  
Mechanical Shock ◽  
Initiation And Propagation ◽  
Solid Explosives ◽  
Velocity Of Propagation ◽  
The Difference

Although half a century has elapsed since the publication of the classical treatise of Berthelot upon explosives, the detailed mechanism of the initiation and propagation of detonation in liquid and solid explosives is still obscure. Detonation is a phenomenon exhibiting a number of specific characteristics which differentiate it quite definitely from the explosive combustions of such substances as gunpowder and cordite. It is well known that the latter are governed by laws relating the rate of reaction to the surface area, the temperature and pressure of the surrounding gases, etc., and that heat is the chief medium of initiation and propagation, whereas in the case of detonation, the reaction wave-front travels directly through the explosive medium in the same sense as does a sound wave, and the velocity of propagation is a very definite characteristic of the phenomenon. This stability of the detonation velocity is well demonstrated for solid explosives by the photographs in a recent paper by E. Jones ; the speeds are usually much greater than any exhibited by explosive combustions, and range from 1500 to 10,000 metres per second. Finally, the initiation and propagation of detonation appear to be associated much more intimately with mechanical shock than with flame. The weight of evidence strongly indicates that the difference between detonation and explosive combustion is fundamental and not merely of degree, and the term “high explosive” is reserved for substances capable of the former property. The theoretical treatment of detonation as a shock wave traversing the medium and maintained by the accompanying chemical reactions has been developed by several investigators. These writers have built up a quantitative theory from thermodynamical reasoning and have been able to calculate velocities of propagation, which in some cases are correct, but in practice it has been found that the thermodynamical conditions, while necessary, are not sufficient. Thus, a great number of compositions possessing all the thermodynamical qualifications of a high explosive cannot be made to detonate; others permit detonation to be initiated successfully but without propagation, and the reaction degenerates into a mere deflagration, or even dies out completely. It is indeed very difficult to judge whether a particular composition is a true detonating explosive without the opportunity to test the sample in reasonable quantity. The violent decompositions of small samples or single crystals furnishes no a priori evidence of detonation, and innumerable examples may be quoted of such material in bulk being unable to propagate the local and violent initial activity.

The Velocity of Propagation of Ultrasonic Waves and the Form of the Molecules of High Polymers

1950 ◽  
Vol 23 (1) ◽  
pp. 151-162
Author(s):  
Giulio Natta ◽  
Mario Baccaredda
Keyword(s):  
Molecular Weight ◽  
Form Factor ◽  
Experimental Error ◽  
Ultrasonic Waves ◽  
Low Molecular Weight ◽  
Side Chains ◽  
Polyethylene Oxides ◽  
Velocity Of Propagation ◽  
Secondary Side ◽  
Linear Macromolecules

Abstract The velocity of propagation of ultrasonic waves in numerous substances of high molecular weight was determined. For substances not fusible at temperatures below 100° C, this velocity was determined by extrapolation from solutions considered ideal. For linear macromolecules without side chains, the ultrasonic velocity appears to be practically equal, within the limits of experimental error, to that calculated by the formula of Rao and on a basis of the additive values of the bond velocity of Lagemann and Corry. For molecules which have many side chains, the velocity is lower than the calculated value, whereas for compounds of low molecular weight this deviation is relatively small, viz., less than 10 per cent; it becomes much higher, viz., almost up to 40 per cent, for macromolecules. The form factor is defined as the ratio of the velocity determined experimentally to the velocity calculated by the formula of Rao. This form factor is equal to 1 for polymers without side chains or with very few side chains, such as paraffins, polyethylenes, Nylon, polyethylene oxides, and polyoxymethylenes; is only 0.89–0.90 for natural rubber; only 0.82–0.84 for Buna and for hydrogenated Buna, poly-α-butylenes, and polystyrenes; only 0.79–0.80 for polyisobutylenes; only 0.89 for polymethacrylates; only 0.78 for polyvinylisobutyl ethers; only 0.65 for Butyl rubber; and only 0.63 for polymethyl methacrylates. The form factor is thus affected by the frequency and length of the side chains, and by any secondary side chains which may be present.

scholarly journals XX. On new compounds of carbon and hydrogen, and on certain other products obtained during the decomposition of oil by heat

1825 ◽  
Vol 115 ◽  
pp. 440-466 ◽  
Keyword(s):  
High Temperatures ◽  
Liquid State ◽  
Royal Society ◽  
The Subject ◽  
The Difference ◽  
New Compounds ◽  
Oil Gas

The object of the paper which I have the honour of sub­mitting at this time to the attention of the Royal Society, is to describe particularly two new compounds of carbon and hydrogen, and generally, other products obtained during the decomposition of oil by heat. My attention was first called to the substances formed in oil at moderate and at high temperatures, in the year 1820; and since then I have endea­voured to lay hold of every opportunity for obtaining information on the subject. A particularly favourable one has been afforded me lately through the kindness of Mr. Gordon, who has furnished me with considerable quantities of a fluid obtained during the compression of oil gas, of which I had some years since possessed small portions, sufficient to excite great interest, but not to satisfy it. It is now generally known, that in the operations of the Portable Gas Company, when the oil gas used is compressed in the vessels, a fluid is deposited, which may be drawn off and preserved in the liquid state., The pressure applied amounts to 30 atmospheres; and in the operation, the gas previously contained in a gasometer over water, first passes into a large strong receiver, and from it, by pipes, into the portable vessels. It is in the receiver that the condensation principally takes place; and it is from that vessel that the liquid I have worked with has been taken. The fluid is drawn off at the bottom by opening a conical valve: at first a portion of water generally comes out, and then the liquid. It effervesces as it issues forth; and by the difference of re-­fractive power it may be seen, that a dense transparent vapour is descending through the air from the aperture. The effervescence immediately ceases; and the liquid may be readily retained in ordinary stoppered, or even corked bottles; a thin phial being sufficiently strong to confine it. I understand that 1000 cubical feet of good gas yield nearly one gallon of the fluid.

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