Ultrasonic dispersion in organic vapours

1950 ◽  
Vol 204 (1078) ◽  
pp. 424-434 ◽  
Keyword(s):  
Molecular Structure ◽  
High Temperatures ◽  
Diethyl Ether ◽  
Methyl Alcohol ◽  
Vibrational Energy ◽  
Low Frequency ◽  
Polyatomic Molecules ◽  
Ultrasonic Waves ◽  
Ultrasonic Dispersion ◽  
Internal Rotations

The velocity of ultrasonic waves has been measured in a series of organic vapours at frequencies 566, 1192 and 4000 kc./sec., temperatures 20 and 100° C, and pressures ranging from 0.25 to 4 atm. Ultrasonic dispersion was found with benzene, cyclopropane and ethane. No dispersion was found with propane, n -hexane, cyclohexane, cyclohexene, ethylchloride, chloroform, acetonitrile, acetaldehyde, acetone, diethyl ether and methyl alcohol. The mechanism and rate of the activation of vibrational energy by intermolecular collisions are discussed in relation to molecular structure. It is concluded that, for polyatomic molecules in general, there is little hindrance to the interconversion of translational and vibrational energy, especially at high temperatures. Slow interconversion, leading to ultrasonic dispersion, only occurs with small or rigid molecules, where internal rotations or vibrations of low frequency are absent. Interchange of vibrational energy between the different modes within the molecule is usually very rapid.

Ultrasonic dispersion in halo-methane vapours

1953 ◽  
Vol 219 (1139) ◽  
pp. 490-499 ◽  
Keyword(s):  
Virial Coefficient ◽  
Vibrational Energy ◽  
Second Virial Coefficient ◽  
Functional Relation ◽  
Ultrasonic Waves ◽  
Ultrasonic Dispersion ◽  
Carbon Tetrafluoride ◽  
Single Relaxation Time ◽  
Theoretical Significance ◽  
Dispersion Zone

The velocity of ultrasonic waves has been measured in the vapours of methyl fluoride, chloride, bromide and iodide, methylene fluoride and chloride, fluoroform and chloroform, carbon tetrafluoride and carbon tetrachloride, at frequencies 200, 566, 1192 and 4000 kc/s, pressures ranging from 0·25 to 2 atm, and temperature 100°C. Dispersion, or incipient dispersion, occurs in all cases. Each dispersion zone observed corresponds to a single relaxation time, involving disappearance of the whole of the molecular vibrational energy. On the assumption that vibrational energy is taken up via the mode of lowest frequency, a simple functional relation is found to exist between the frequency of this mode and the probability of vibrational energy being acquired in collision. The theoretical significance of this is discussed. The paper includes second virial coefficient data for all the vapours investigated.

Ultrasonic dispersion in halo-ethylene vapours

1955 ◽  
Vol 232 (1191) ◽  
pp. 537-547 ◽  
Keyword(s):  
Virial Coefficient ◽  
Vinylidene Fluoride ◽  
Vibrational Energy ◽  
Relaxation Times ◽  
Second Virial Coefficient ◽  
Ultrasonic Waves ◽  
Ultrasonic Dispersion ◽  
Infra Red ◽  
Acoustic Interferometer ◽  
Inactive Mode

The velocity and absorption of ultrasonic waves have been measured by acoustic interferometer in the vapours of vinyl fluoride, chloride, bromide and iodide, vinylidene fluoride, cis -dichloro-ethylene, trans -dichloro-ethylene, trichloro-ethylene and tetrafluoro-ethylene at 100° C and for values of f|p ranging from 100 kc s -1 atm -1 to 15 Mc s ~1 atm~1. All show dispersion or incipient dispersion, and single relaxation times appear to control the whole of the molecular vibrational energy in each case. The results are correlated with previous results for halo-methane vapours and for other polyatomic molecules. The conclusion is drawn that vibrational activation enters a molecule via the mode of lowest frequency. The probability of excitation of that mode in collision is a function both of its frequency and of the intensity of its infra-red activity. In most cases a strongly infra-red active mode is very much more easily excited by collision than an inactive mode of the same frequency. The paper includes second virial coefficient data for all the vapours investigated.

Ultrasonic dispersion in gaseous sulphur dioxide

1957 ◽  
Vol 243 (1232) ◽  
pp. 78-83 ◽  
Keyword(s):  
Relaxation Time ◽  
Sulphur Dioxide ◽  
Major Part ◽  
Vibrational Energy ◽  
Vibrational Mode ◽  
Relaxation Times ◽  
Ultrasonic Waves ◽  
Ultrasonic Frequency ◽  
Ultrasonic Dispersion ◽  
Dispersion Zone

The velocity of ultrasonic waves has been measured in gaseous sulphur dioxide at 20, 102 and 200° C for values of f/p ranging from 200 kcs -1 atm -1 to 7 Mcs -1 atm -1 . ( f is the ultrasonic frequency, p the pressure.) Dispersion involving the major part of the vibrational specific heat was found at all temperatures. Each dispersion zone corresponds to two distinct relaxation times differing by a factor of ten. The lower relaxation time corresponds with activation of the lowest (519 cm -1 ) vibrational mode, the higher to activation of the remainder of the vibrational energy. The conditions giving rise to a double relaxation process are discussed.

scholarly journals Vibrational band-structures caused by internal rotations of the boron Wankel rotor B11−

RSC Advances ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 3613-3621
Author(s):  
Yonghong Xu ◽  
Huihui Wang ◽  
Yonggang Yang ◽  
Changyong Li ◽  
Liantuan Xiao ◽  
...  
Keyword(s):  
Vibrational Energy ◽  
Energy Levels ◽  
Vibrational Band ◽  
Spectral Broadening ◽  
Band Structures ◽  
Internal Rotations ◽  
Vibrational Energy Levels

The band structures of the vibrational energy levels of B11− lead to corresponding spectral broadening. The vibrational band-structures of planar boron rotors are caused by internal rotations.

scholarly journals Ultra-Low Frequency Eccentric Pendulum-Based Electromagnetic Vibrational Energy Harvester

Micromachines ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1009
Author(s):  
Mingxue Li ◽  
Huichao Deng ◽  
Yufeng Zhang ◽  
Kexin Li ◽  
Shijie Huang ◽  
...  
Keyword(s):  
Low Power ◽  
Energy Harvester ◽  
Vibrational Energy ◽  
Low Frequency ◽  
Sensor Nodes ◽  
Wireless Sensor ◽  
Center Frequency ◽  
Vibration Energy ◽  
Outer Side ◽  
Working Frequency

With the development of low-power technology in electronic devices, the wireless sensor network shows great potential in applications in health tracing and ocean monitoring. These scenarios usually contain abundant low-frequency vibration energy, which can be collected through appropriate energy conversion architecture; thus, the common issue of limited battery life in wireless sensor devices could be solved. Traditional energy-converting structures such as the cantilever-beam type or spring-mass type have the problem of high working frequency. In this work, an eccentric pendulum-based electromagnetic vibration energy harvester is designed, analyzed, and verified with the finite element analysis method. The pendulum that contains alternative distributed magnets in the outer side works as a rotor and has the advantages of a simple structure and low center frequency. The structure size is well scalable, and the optimal output performance can be obtained by optimizing the coil thickness and width for a given diameter of the energy harvester. The simulation results show that the energy harvester could work in ultra-low frequencies of 0.2–3.0 Hz. A full-scale prototype of the energy harvester is manufactured and tested. The center working frequency is 2.0 Hz with an average output power of 8.37 mW, which has potential for application in driving low-power wireless sensor nodes.

scholarly journals Diagnostics of concrete plate in bending with ultrasonic waves modulated by low frequency oscillations

2013 ◽  
Vol 12 (1) ◽  
pp. 243-250
Author(s):  
Błażej Meronk ◽  
Krzysztof Wilde
Keyword(s):  
Experimental Study ◽  
Low Frequency ◽  
Ultrasonic Waves ◽  
Modulation Method ◽  
Frequency Spectra ◽  
Concrete Plate ◽  
Low Frequency Oscillations ◽  
Damaged Zone ◽  
Nonlinear Acoustic ◽  
Concrete Elements

The paper presents the experimental study on the inter-modulation method for the diagnostics of concrete elements. The tests were conducted on a concrete plate subjected to ultrasonic waves and low frequency vibrations. The nonlinear acoustic effects, recorded in the experiments, made it possible to detect the presence of damaged zones. Further studies are necessary to establish the relation between the sidebanes of frequency spectra and the size of the damaged zone.

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