scholarly journals The new model of erosion destroying

2019 ◽  
Vol 489 (6) ◽  
pp. 581-584
Author(s):  
V. T. Kuzavov
Keyword(s):  
Shock Waves ◽  
Experimental Model ◽  
Solid Surface ◽  
High Frequency ◽  
Acoustic Energy ◽  
Erosion Damage ◽  
New Model ◽  
Cavitation Effect ◽  
Cumulative Jets ◽  
Spiral Structures

A new physical (experimental) model of cavitation destruction of the studied materials is proposed. In the mo-dern model of the cavitation effect, the destruction of materials is associated with the impacts of cumulative jets, which are formed during the asymmetric slamming of cavitation bubbles near the solid surface and the shock waves that occur during their compression. In the new model, erosion damage is explained by the formation of cavitation tubes (с-tubes) with a spiral high-frequency structure in the materials under study that were previously unknown in the literature. The destruction of materials is associated with the focusing of acoustic energy along the axis of the spiral structures. When focusing energy, there is a significant increase in pressure and temperature along the axis of the spiral structures, which leads to the destruction of the materials under study.

scholarly journals Detecting gas leakage using high-frequency signals generated by air-gun arrays

Geophysics ◽  
2017 ◽  
Vol 82 (2) ◽  
pp. A7-A12 ◽  
Author(s):  
Martin Landrø ◽  
Fredrik Hansteen ◽  
Lasse Amundsen
Keyword(s):  
High Frequency ◽  
Field Experiments ◽  
Water Layer ◽  
Sampling Interval ◽  
Acoustic Energy ◽  
Storage Site ◽  
High Frequency Signal ◽  
Gas Leakage ◽  
Temporal Sampling ◽  
Air Gun

Recent field experiments have demonstrated that marine air-gun arrays create acoustic energy greater than 1 kHz. We have suggested to use the high-frequency signal as a source to look for gas leakage at, for instance, a producing hydrocarbon field, or a [Formula: see text] storage site in which the field is covered by permanent acoustic sensors at the seabed, often referred to as a permanent reservoir monitoring field. The only needed modification is that the temporal sampling interval for the receivers is decreased to 0.1 ms (in contrast to the normal sampling interval of 1 or 2 ms), to ensure that the system is capable of recording signals up to 5 kHz. We suggest using numerous fixed receivers at the seabed to detect a gas chimney by simple high-pass filtering and subsequent transmission type analysis of the recorded signals. We think this method might serve as an elegant, precise, and very cost-effective way to detect gas leakage into the water layer.

scholarly journals May 24, 1968 at Inangahua Junction

1969 ◽  
Vol 2 (1) ◽  
pp. 37-38
Author(s):  
T. Hogue
Keyword(s):  
Shock Waves ◽  
High Frequency ◽  
Initial Displacement ◽  
North East ◽  
The North ◽  
Upward Displacement ◽  
The Town

The twin communities of Inangahua Camp and Inangahua Junction were rudely awakened at approximately 5.25 a.m.by a severe earthquake. About a minute before the quake all the birdlife suddenly stopped their noisy callingand an uncanny stillness settled over the area. The first movement of the earthquake was an upward displacement although a few argue that the initial displacement was to the north east. No longer than two seconds later the high frequency vibrating and confusion of noise enveloped the town, then came the jolting of no discriminate pattern as shock-waves started to rebound through the region. During the peak of the earthquake most people who. were by now fully awakened thought that "this was the end", any dissenters from this view acknowledged that it was "at least a beaut”.

The Effect of Different Doses of Extracorporeal Shock Waves on Experimental Model Mandibular Distraction

2018 ◽  
Vol 29 (6) ◽  
pp. 1666-1670 ◽  
Author(s):  
Cihan Bereket ◽  
Nilüfer Çakir-Özkan ◽  
Mehmet Emin Önger ◽  
Selim Arici
Keyword(s):  
Shock Waves ◽  
Experimental Model ◽  
Mandibular Distraction ◽  
Extracorporeal Shock Waves ◽  
Different Doses

scholarly journals New experimental model for training in videosurgery

2012 ◽  
Vol 27 (10) ◽  
pp. 741-745 ◽  
Author(s):  
Danilo Malta Batista ◽  
Victor Araujo Felzemburgh ◽  
Ediriomar Peixoto Matos
Keyword(s):  
Public Health ◽  
Experimental Model ◽  
Operative Technique ◽  
Lower Cost ◽  
Low Cost ◽  
Full Professor ◽  
Experimental Surgery ◽  
New Model ◽  
School Of Medicine ◽  
The Subject

PURPOSE: To develop a new experimental model of lower cost for training in videosurgery. METHODS: This project was performed at the Nucleus of Experimental Surgery of the Bahiana School of Medicine and Public Health, based on previous models described in the literature and under the supervision of the full professor of Operative Technique and Experimental Surgery II. It was made a model cube-shaped, made of wood, with holes distributed in various locations, rubber stoppers for the holes and lined externally with carpet, and internally with laminate. RESULTS: The new experimental model is of low cost and reproduces quite faithfully several videosurgical procedures. CONCLUSION: Medical schools interested in the subject may adopt the new model for training in videosurgery without the need of high costs for making and using these models.

On the effectiveness of ventilation to mitigate the damage of spherical membrane vessels subjected to internal detonations

2020 ◽  
Vol 11 (3) ◽  
pp. 319-339
Author(s):  
Francisco Hernandez ◽  
Xihong Zhang ◽  
Hong Hao
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
High Frequency ◽  
Arrival Time ◽  
Time Lag ◽  
Reflected Shock Wave ◽  
High Explosives ◽  
Element Analysis ◽  
Blast Overpressure ◽  
Reflected Shock

This article conducts a comparative study on the effectiveness of ventilation to mitigate blasting effects on spherical chambers subjected to internal detonations of high explosives through finite element analysis using the software package AUTODYN. Numerical simulations show that ventilation is ineffective in mitigating the damage of spherical chambers subjected to internal high explosives explosions because the chamber response is mainly described by high-frequency membrane modes. Openings do not reduce the chamber response despite they can reduce the blast overpressure after the chamber reaches its peak response. Worse still, openings lead to stress concentration, which weakens the structure. Therefore, small openings may reduce the capacity of the chamber to resist internal explosions. In addition, because large shock waves impose the chamber to respond to a reverberation frequency associated with the re-reflected shock wave pulses, secondary re-reflected shock waves can govern the chamber response, and plastic/elastic resonance can occur to the chamber. Simulations show that the time lag between the first and the second shock wave ranges from 3 to 7 times the arrival time of the first shock wave, implying that the current simplified design approach should be revised. The response of chambers subjected to eccentric detonations is also studied. Results show that due to asymmetric explosions, other membrane modes may govern the chamber response and causes localized damage, implying that ventilation is also ineffective to mitigate the damage of spherical chambers subjected to eccentric detonations.

New acoustical technology of sound absorption based on reverse horn

2016 ◽  
Vol 30 (34) ◽  
pp. 1650403 ◽  
Author(s):  
Yong Yan Zhang ◽  
Jiu Hui Wu ◽  
Song Hua Cao ◽  
Pei Cao ◽  
Zi Ting Zhao
Keyword(s):  
High Frequency ◽  
Sound Absorption ◽  
Mechanical Energy ◽  
Low Frequency ◽  
Acoustic Energy ◽  
Absorption Mechanism ◽  
Structure Changes ◽  
Potential Applications ◽  
Energy Focusing ◽  
The One

In this paper, a novel reverse horn’s sound-absorption mechanism and acoustic energy focusing mechanism for low-frequency broadband are presented. Due to the alternation of the reverse horn’s thickness, the amplitude of the acoustic pressure propagated in the structure changes, which results in growing energy focused in the edge and in the reverse horn’s tip when the characteristic length is equal to or less than a wavelength and the incident wave is compressed. There are two kinds of methods adopted to realize energy dissipation. On the one hand, sound-absorbing materials are added in incident direction in order to overcome the badness of the reverse horn’s absorption in high frequency and improve the overall high-frequency and low-frequency sound-absorption coefficients; on the other hand, adding mass and film in its tip could result in mechanical energy converting into heat energy due to the coupled vibration of mass and the film. Thus, the reverse horn with film in the tip could realize better sound absorption for low-frequency broadband. These excellent properties could have potential applications in the one-dimensional absorption wedge and for the control of acoustic wave.

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