Experimental investigation on time‐frequency evolution characteristics of electromagnetic radiation below ULF reflecting the damage performance of coal or rock materials

2021 ◽  
Author(s):  
Wei Yang ◽  
Xunchang Li ◽  
Rui Xu ◽  
Chengwu Li ◽  
Yaqian Wang ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Electromagnetic Radiation ◽  
Time Frequency ◽  
Rock Materials ◽  
Evolution Characteristics

scholarly journals Experimental investigation of accuracy time-frequency synchronization by using digital television signals

2014 ◽  
Vol 1 (9(67)) ◽  
pp. 24
Author(s):  
Александр Алексеевич Костыря ◽  
Сергей Александрович Плехно ◽  
Виталий Николаевич Науменко ◽  
Сергей Иванович Ушаков
Keyword(s):  
Experimental Investigation ◽  
Digital Television ◽  
Frequency Synchronization ◽  
Time Frequency

scholarly journals Experimental Investigation on Time-Frequency Characteristics of Microseismic Signals in the Damage Evolution Process of Coal and Rock

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 809
Author(s):  
Wei Yang ◽  
Chengwu Li ◽  
Rui Xu ◽  
Xunchang Li
Keyword(s):  
Damage Evolution ◽  
Resonance Effect ◽  
Low Frequency ◽  
Dominant Frequency ◽  
Frequency Characteristics ◽  
Evolution Process ◽  
Deformation And Failure ◽  
Time Frequency ◽  
Rock Materials ◽  
Damage Degree

The deformation and failure of coal and rock materials is the primary cause of many engineering disasters. How to accurately and effectively monitor and forecast the damage evolution process of coal and rock mass, and form a set of prediction methods and prediction indicators is an urgent engineering problems to be solved in the field of rock mechanics and engineering. As a form of energy dissipation in the deformation process of coal and rock, microseismic (MS) can indirectly reflect the damage of coal and rock. In order to analyze the relationship between the damage degree of coal and rock and time-frequency characteristics of MS, the deformation and fracture process of coal and rock materials under different loading modes was tested. The time-frequency characteristics and generation mechanism of MS were analyzed under different loading stages. Meanwhile, the influences of properties of coal and rock materials on MS signals were studied. Results show that there is an evident mode cutoff point between high-frequency and low-frequency MS signals. The properties of coal and rock, such as the development degree of the original fracture, particle size and dense degree have a decisive influence on the amplitude, frequency, energy and other characteristic parameters of MS signals. The change of MS parameters is closely related to material damage, but has no strong relation with the loading rate. The richness of MS signals before the main fracture depends on the homogeneity of materials. With the increase of damage, the energy release rate increases, which can lead to the widening of MS signals spectrum. The stiffness and natural frequency of specimens decreases correspondingly. Meanwhile, the main reason that the dominant frequency of MS detected by sensors installed on the surface of coal and rock materials is mainly low-frequency is friction loss and the resonance effect. In addition, the spectrum and energy evolution of MS can be used as a characterization method of the damage degree of coal and rock materials. Furthermore, the results can provide important reference for prediction and early warning of some rock engineering disasters.

Development of Methods and Algorithms to Identify Real-Time Features of the Time-Frequency Characteristics of Electromagnetic Radiation in the Digital Data Radio Receiver

2015 ◽  
Vol 775 ◽  
pp. 441-445
Author(s):  
Anatoly Kalyaev ◽  
Iakov Korovin ◽  
Maxim Khisamutdinov ◽  
Igor Kalyaev
Keyword(s):  
Electromagnetic Radiation ◽  
Real Time ◽  
Frequency Characteristics ◽  
Digital Data ◽  
Radio Receiver ◽  
Time Frequency

The main objective of the work is the development of methods, algorithms and software to identify real-time features of the time-frequency characteristics of electromagnetic radiation in the digital data radio receiver different wavelength ranges.

scholarly journals The Evolution Characteristics of Different Deformation Modes of Shear Slip Surface Based on Acoustic Emission Measurements

2021 ◽  
Author(s):  
Qiang Xie ◽  
zhihui wu ◽  
Yuxin Ban ◽  
Xiang Fu ◽  
Zhilin Cao ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
High Frequency ◽  
Surface Deformation ◽  
Deformation Mode ◽  
High Energy ◽  
Correlation Diagram ◽  
Small Scale ◽  
Progressive Deformation ◽  
Time Frequency ◽  
Evolution Characteristics

Abstract To investigate the acoustic emission (AE) precursor detection of landslide failures, a model test aiming at reproducing the typical shear surface deformation of different landslide modes was designed. The evolution characteristics of the AE signals were analyzed in terms of AE count, cumulative AE count, AE correlation diagrams, and corresponding time-frequency properties. The test results show that for the progressive deformation mode, the AE count experiences a low-level period, an active period and a rapid increase period, and the distribution of correlation diagram hits concentrates in a relatively small scale and then gradually scatters. There is low frequency signals firstly and then high frequency signals, and the energy proportion of the high-frequency signals shows an increasing tendency. For the sudden deformation mode, the magnitude of AE count increases sharply, leading to the cumulative AE count curve rises steeply, and correlation diagram hits distribution turns into relatively scattering rapidly. Furthermore, the high frequency signals and high energy proportion appear much earlier than that of the progressive deformation mode. For steady deformation mode, however, the acoustic emission activity is quite active in the initial stage, the cumulative AE count curve rises sharply and then maintains relatively flat trend, and correlation diagram hits distribution scatters firstly, then the signal hits distribution begins to concentrate in a relatively small scale. There are intensive high-frequency hits and high energy proportion earlier, and later they tend to decay in response to smaller magnitudes of movement. Comprehensive use of multiple features can help identify landslide deformation patterns more accurately under complex natural conditions, which may provide a promising reference for the field warning monitoring of the diverse landslide failures.

Time-frequency evolution law and generation mechanism of electromagnetic radiation in coal friction process

2021 ◽  
pp. 106377
Author(s):  
Shan Yin ◽  
Dazhao Song ◽  
Xueqiu He ◽  
Liming Qiu ◽  
Menghan Wei ◽  
...  
Keyword(s):  
Electromagnetic Radiation ◽  
Generation Mechanism ◽  
Friction Process ◽  
Evolution Law ◽  
Time Frequency

Effect of water on the time-frequency characteristics of electromagnetic radiation during sandstone deformation and fracturing

2020 ◽  
Vol 265 ◽  
pp. 105451 ◽  
Author(s):  
Hongru Li ◽  
Rongxi Shen ◽  
Enyuan Wang ◽  
Dexing Li ◽  
Taixun Li ◽  
...  
Keyword(s):  
Electromagnetic Radiation ◽  
Frequency Characteristics ◽  
Time Frequency ◽  
Effect Of Water
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