scholarly journals Comparative analysis of acoustic and electromagnetic emissions of rocks

2021 ◽  
Vol 929 (1) ◽  
pp. 012013
Author(s):  
V N Klyuchkin ◽  
V A Novikov ◽  
V I Okunev ◽  
V A Zeigarnik
Keyword(s):  
Comparative Analysis ◽  
Uniaxial Compression ◽  
High Stress ◽  
Electromagnetic Emission ◽  
Rock Failure ◽  
Dynamic Rupture ◽  
Block Model ◽  
Rock Samples ◽  
Electromagnetic Emissions ◽  
Electromagnetic Signals

Abstract Comparative analysis of acoustic and electromagnetic emissions recorded during the intact rock samples deformation and dynamic rupture of simulated crustal fault is presented. Specialized machines for uniaxial compression and shear tests of rock samples with identical data acquisition systems for both test cases were employed. Increase of acoustic emission was observed accompanied by significant rise of intensity and amplitude of electromagnetic signals at high stress of the rock samples under the uniaxial compression or dynamic failure in the spring-block model. Such correlation is consistent with the previous conclusions that an increase of electromagnetic emission may be considered as a rock failure precursor. Any specific characteristics of the detected electromagnetic signals to be used for prediction of impending rock failure or the earthquake fault rupture were not found. The similarity of electromagnetic signals and their spectra obtained at the press equipment and the spring-block model suggests that in both cases, the signals observed are generated by the crack formations and shear. The electromagnetic emission appeared only in dry samples. The samples saturated by water with the salinity of over 0.1% demonstrated no electromagnetic emission.

scholarly journals The results of experimental studies of VLF–ULF electromagnetic emission by rock samples due to mechanical action

2014 ◽  
Vol 14 (6) ◽  
pp. 1383-1389 ◽  
Author(s):  
A. A. Panfilov
Keyword(s):  
Laboratory Experiments ◽  
Experimental Studies ◽  
Electromagnetic Emission ◽  
Mechanical Action ◽  
Impact Action ◽  
Rock Samples ◽  
Electric Component ◽  
Electromagnetic Emissions ◽  
Electromagnetic Signals ◽  
The Impact

Abstract. The paper presents the results of laboratory experiments on electromagnetic emissions excitation (the electric component of electromagnetic fields) by rock samples due to different forms of mechanical stress applications. It was shown that samples generate electric impulses with different spectra when the impact action, gradual loading or dynamic friction is applied. It was ascertained that level and spectral compositions of signals, generated by rock samples, change with an increasing number of hits. It was found that strong electromagnetic signals, generated while rock samples were fracturing, were accompanied by repetitive weak but perceptible variations in the electric field intensity in short frequency ranges.

scholarly journals Investigation of VLF and HF waves showing seismo-ionospheric anomalies induced by the 29 September 2009 Samoa earthquake (<i>M</i><sub>w</sub>=8.1)

2010 ◽  
Vol 10 (5) ◽  
pp. 1061-1067 ◽  
Author(s):  
M. Akhoondzadeh ◽  
M. Parrot ◽  
M. R. Saradjian
Keyword(s):  
Comparative Analysis ◽  
Langmuir Probe ◽  
Plasma Waves ◽  
The Other ◽  
Electron Content ◽  
Total Electron ◽  
Total Electron Content Data ◽  
Electromagnetic Emissions ◽  
Electromagnetic Signals ◽  
Geomagnetic Activities

Abstract. In Samoa Islands, a powerful earthquake took place at 17:48:10.99 UTC (06:48:10.99 LT) on 29 September 2009 with a magnitude Mw=8.1. Using ICE (Instrument Champ Electrique) and IMSC (Instrument Magnetic Search Coil) experiments onboard the DEMETER (Detection of Electromagnetic Emissions Transmitted from Earthquake Regions) satellite we have surveyed possible variations in electromagnetic signals transmitted by the ground-based VLF transmitter NPM in Hawaii and in HF plasma waves close to the Samoa earthquake during the seismic activity. The indices Dst and Kp were used to distinguish pre-earthquake anomalies from the other anomalies related to the geomagnetic activities. In a previous study we have shown that anomalies in IAP (plasma analyzer) and ISL (Langmuir probe) experiments onboard the DEMETER and also TEC (Total Electron Content) data appear 1 to 5 days before the Samoa earthquake. In this paper we show that the anomalies in the VLF transmitter signal and in the HF range appear with the same time scale. The lack of significant geomagnetic activities indicates that these anomalous behaviors could be regarded as seismo-ionospheric precursors. It is also shown that comparative analysis is more effective in seismo-ionospheric studies.

scholarly journals The results of experimental studies of VLF–ULF electromagnetic emission by rock samples due to mechanical action

2013 ◽  
Vol 1 (6) ◽  
pp. 7821-7842
Author(s):  
A. A. Panfilov
Keyword(s):  
Laboratory Experiments ◽  
Experimental Studies ◽  
Electromagnetic Emission ◽  
Mechanical Action ◽  
Frequency Range ◽  
Impact Action ◽  
Rock Samples ◽  
Electric Component ◽  
Electromagnetic Signals ◽  
The Impact

Abstract. The paper presents the results of laboratory experiments on electromagnetic emission excitation (electric component of electromagnetic field) by rock samples due to different forms of mechanical stress applications. It was shown that samples generate electric impulses with different spectra when the impact action, gradual loading or dynamic friction is applied. It was ascertained that level and spectral compositions of signals, generated by rock samples, change with increasing quantity of hits. It was found that strong electromagnetic signals, generated while rock samples were fracturing, were accompanied by repetitive weak, but perceptible variations of the electric field intensity in short frequency range.

Электромагнитные методы контроля изменений напряженно-деформированного состояния диэлектрических материалов

2021 ◽  
pp. 44-53
Author(s):  
А.А. Беспалько ◽  
Д.Д. Данн ◽  
М.В. Петров ◽  
Е.К. Помишин ◽  
Г.Е. Уцын ◽  
...  
Keyword(s):  
Strain State ◽  
Experimental Studies ◽  
Electromagnetic Emission ◽  
Acoustic Excitation ◽  
Acoustic Sounding ◽  
Rock Samples ◽  
Electromagnetic Responses ◽  
Electromagnetic Signals ◽  
Complex Methods ◽  
Sample Axis

Mechanical-electrical and acoustic-electrical complex methods of testing cracking while changing the stress-strain state in dielectrics are discussed on the example of rock samples. The paper discusses the results of numerical and experimental studies of changes in the electromagnetic responses parameters under the pulse deterministic acoustic excitation of rock samples with different composition and texture. Also the results of mathematical calculations of the stress concentration on cracks located along the sample axis are presented, perpendicular to which deterministic acoustic pulses were introduced. The experimental studies results of sample electromagnetic emission with containing calcite and magnetite under uniaxial compression to fracture are shown. Regularities in the electromagnetic signals amplitudes changes during acoustic sounding in the process of «stepwise» uniaxial loading by compression to destruction are given.

scholarly journals A Survey of Electromagnetic Influence on UAVs from an EHV Power Converter Stations and Possible Countermeasures

Electronics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 701
Author(s):  
Yanchu Li ◽  
Qingqing Ding ◽  
Keyue Li ◽  
Stanimir Valtchev ◽  
Shufang Li ◽  
...  
Keyword(s):  
Electromagnetic Interference ◽  
Wide Spectrum ◽  
Electromagnetic Emission ◽  
Power Converter ◽  
Electromagnetic Environment ◽  
Communication Circuits ◽  
Electromagnetic Emissions ◽  
Surrounding Space ◽  
Extra High Voltage ◽  
The Impact

It is inevitable that high-intensity, wide-spectrum electromagnetic emissions are generated by the power electronic equipment of the Extra High Voltage (EHV) power converter station. The surveillance flight of Unmanned Aerial Vehicles (UAVs) is thus, situated in a complex electromagnetic environment. The ubiquitous electromagnetic interference demands higher electromagnetic protection requirements from the UAV construction and operation. This article is related to the UAVs patrol inspections of the power line in the vicinity of the EHV converter station. The article analyzes the electromagnetic interference characteristics of the converter station equipment in the surrounding space and the impact of the electromagnetic emission on the communication circuits of the UAV. The anti-electromagnetic interference countermeasures strive to eliminate or reduce the threats of electromagnetic emissions on the UAV’s hardware and its communication network.

Transient electric signals prior to rock failure under uniaxial compression

1994 ◽  
Vol 21 (16) ◽  
pp. 1687-1690 ◽  
Author(s):  
V. Hadjicontis ◽  
C. Mavromatou
Keyword(s):  
Uniaxial Compression ◽  
Rock Failure ◽  
Electric Signals

The Propagation of Plasticity in Uniaxial Compression

1948 ◽  
Vol 15 (3) ◽  
pp. 256-260 ◽  
Author(s):  
M. P. White ◽  
LeVan Griffis
Keyword(s):  
Uniaxial Compression ◽  
Thin Sheet ◽  
High Stress ◽  
Stress And Strain ◽  
Velocity Range ◽  
Plastic Materials ◽  
The Face ◽  
Elastic Plastic Materials ◽  
The Impact ◽  
Type Of Behavior

Abstract A theoretical investigation of the mechanism of uniaxial compression impact on elastic-plastic materials is described in this paper. The method of analysis is similar in some respects to that previously given for tension impact on such materials. It is concluded that four different kinds of behavior can occur, depending upon the impact velocity. In the lowest velocity range the behavior in compression is similar to that found in tension. In this case stress and strain are propagated from the point of impact as a zone or wave front of ever-increasing length. This type of behavior ends at a velocity corresponding to the “critical” velocity found in tension impact. Within the next higher velocity range, stress and strain are propagated as a shock-type wave, or wave of very small length in which the transition from low to high stress and strain is very abrupt. At still higher impact velocities, there occurs “flowing deformation” in which the material is too weak to maintain coherency. Here there is a steady flow of the material toward and against the hammer, after which it flows in a thin sheet radially outward over the face of the hammer. The final possible state occurs at impact velocities greater than the speed of an elastic wave, so that no disturbance can escape from the hammer into the medium. Here the behavior is essentially that of a fluid, impact force being independent of strength of material.

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