Zoucheng, China
Zoucheng, China

Time filter

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Zhou H.,CAS Wuhan Institute of Rock and Soil Mechanics | Li Z.,CAS Wuhan Institute of Rock and Soil Mechanics | Li Z.,Henan Polytechnic University | Zhu G.-J.,Power China Kunming Engineering Corporation Ltd | And 3 more authors.
Yantu Lixue/Rock and Soil Mechanics | Year: 2016

In order to accurately and conveniently determine the mechanical behavior of hard rock in deep engineering structures, the following works have been conducted in this paper: according to the similar mechanism of damage and plastic, determination scheme of initial yield is assumed to be used for the damage threshold. Unified energy yield criterion of rock is adopted as the decision criterion of damage threshold. Based on the definition of damage variable by Rabotnov and hypothesis of Lemaitre strain equivalence, a simplified damage constitutive law is formulated by assuming the stress- strain relation of undamaged portion to conform Hooke's law. Aimed at expressing brittle-ductile transition of hard rock under the condition from low confining pressure to high confining pressure, a modified Mazars damage evolution equation is proposed. Damage model parameters are determined based on conventional triaxial compressive test of T2b marble. The proposed model is contrasted with the model based on Mazars damage evolution and damage threshold criterion used by Mohr-Coulomb criterion respectively. It is suggested that the damage model can express brittle-ductile transition and simulate damage evolution after damage threshold in an accurate way, which has some reference for engineering calculation of brittle hard rock. © 2016, Academia Sinica. All right reserved.


Sai Y.,Shandong University | Jiang M.,Shandong University | Jiang M.,Yanzhou Coal Mining Group | Sui Q.,Shandong University | And 2 more authors.
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2014

For the problems of complicated structure, difficults to networking and low accuracy of traditional acoustic emission localization system, an acoustic emission localization based on fiber Bragg grating (FBG) sensor network and time reversal focusing imaging technology is designed. Based on the analysis of the principle of time reversal focusing, positioning system by four FBG sensors is built and narrow band laser edge filter technology is used to realize signal demodulation. Morlet wavelet transform is used to extract specific frequency component signal, and calculate the modulus value and time lag. Through the establishment of time reversal focusing model, acoustic emission location is realized. The localization method is verified in the aluminum alloy plate. The experimental result shows that this method can effectively realize localization and imaging of acoustic emission source, and localization error is less than 20 mm, and time consumption is less than 2 s. A new method is provided for acoustic emission detection and localization.


Sai Y.-Z.,Shandong University | Jiang M.-S.,Shandong University | Jiang M.-S.,Yanzhou Coal Mining Group | Sui Q.-M.,Shandong University | And 2 more authors.
Guangdianzi Jiguang/Journal of Optoelectronics Laser | Year: 2014

In order to deal with the problem of multi-impact sources localization, difficulty of networking and low accuracy of traditional impact source localization system, A impact source method is designed based on fiber Bragg grating (FBG) sensor network and time reversal focusing imaging technology. The principle of time reversal focusing is analyzed in this paper. The monitoring system is established by four FBG sensors, and the narrow band laser edge filter technology is used to demodulate signal. The Shannon wavelet transform is used to extract narrow band signal, and the modulus value and velocity are calculated. Multi-impact sources localization is realized by establishing time reversal focusing search model, and the method is verified in impact experiment of the aviation aluminum alloy plate. The results show that this method can effectively localize multi-impact sources, and the localization error is less than 1.5 cm. A high-accuracy method is provided for multi-impact sources detection and localization.


Mu Z.-L.,China University of Mining and Technology | Mu Z.-L.,Yanzhou Coal Mining Group | Wang H.,China University of Mining and Technology | Peng P.,Yanzhou Coal Mining Group | And 2 more authors.
Caikuang yu Anquan Gongcheng Xuebao/Journal of Mining and Safety Engineering | Year: 2013

In order to determine the bursting danger of mining zone, and to solve the limitation of coal and rock's bursting liability evaluation criterion, the stiffness values of coal's post-peak and rock's unloading process are used to evaluate the steady and unsteady failure of rock-coal-rock sample based on the analysis of deformation, acceleration, stiffness and energy variation. The research results indicate that rock-coal-rock sample's failure state is determined by the contrast relation of coal's post-peak stiffness and rock's stiffness. There is a point S on the coal's stress-strain curve during the unloading process where the stiffness changing ratio satisfies the relation of λ'>k1k2m̈/ [(k1+k2)u̇2, after which the rock-coal-rock sample's shall not keep the balance state, and the sample's failure will convert from stable to instable state. The parameter α which is the ratio of the energy that roof and floor releases to that of coal releases is used as the index of bursting liability of rock-coal-rock sample. The results of seven sites' samples from 2 mines indicate that there are 2 samples' bursting liability is under the influence of roof and floor attribution. The model of rock-coal-rock sample can reflect the bursting liability of in-situ surrounding rock more accurately than that of only coal.


Wen Y.-Y.,China University of Mining and Technology | Mu Z.-L.,China University of Mining and Technology | Mu Z.-L.,Yanzhou Coal Mining Group | Yi E.-B.,China University of Mining and Technology | And 2 more authors.
Caikuang yu Anquan Gongcheng Xuebao/Journal of Mining and Safety Engineering | Year: 2013

In order to study the influence principles of dynamic disturbance on roadway surrounding rock in different hardness coal seams, the paper numerically analyses the stress response of roadway surrounding rock under dynamic disturbance. The results demonstrate that the average period that the dynamic disturbance has effect on the steady of rock is 0.4 s. The soft coal's is more serious than the hard coal's when compared with the horizontal stress amplitude of roof rock and the deformation of roof and side roadway. How-ever, the hard coal's is more serious than soft coal's when compared with the vertical stress amplitude of side roadway, the horizontal stress amplitude of floor rock, the deformation of floor rock and the plasticity zone of floor and side roadway. The deformation of roof rock is more serious than that of floor and side roadway in two kinds of coal seam, and in soft coal seam the defor-mation of side roadway is more serious than that of floor rock. During the in-creasing period of roadway deformation, the rate of rise is different in side roadway and floor roadway, but is same in roof rock.


Jiang M.-S.,Shandong University | Jiang M.-S.,Yanzhou Coal Mining Group | Meng L.,Shandong University | Sui Q.-M.,Shandong University | And 3 more authors.
Guangdianzi Jiguang/Journal of Optoelectronics Laser | Year: 2011

A tunable L-band ring Er3+-doped fiber laser (EDFL) with a temperature control Cu-coated long-period fiber grating (LPFG) is reported. The coated LPFG is used as a band-prevented filter. The resonant wavelength of LPFG can be adjusted by changing its environment temperature using the const-current source. The coated LPFG, which is inserted into the fiber ring cave, will tune the highest gain point of the fiber laser ring. Furthermore the fiber laser wavelength is also tuned. In the temperature range of 20-180°C, the optical fiber laser wavelength-tunable range of 20.72 nm (1560.35-1581.07 nm) is achieved. The fiber laser's 3 dB line-width is less than 0.02 nm and the 20 dB line-width is less than 0.06 nm. The side mode suppression ratio (SMSR) is more than 38 dB. Output power stability of laser wavelength is better than 0.02 dBm. Experimental results show that the tunable EDFL has the advantages of easy tunablity, narrow line-width and stable performance.


Jiang M.-S.,Shandong University | Jiang M.-S.,Yanzhou Coal Mining Group | Sui Q.-M.,Shandong University | Jia L.,Shandong University | Peng P.,Yanzhou Coal Mining Group
Guangdianzi Jiguang/Journal of Optoelectronics Laser | Year: 2012

Temperature, strain and bending characteristics of a long period fiber grating (LPFG) written in a grapefruit-type photonic crystal fiber (PCF) are investigated experimentally. By using high-frequency CO 2 laser, the LPFG written on PCF (PCF-LPFG) is achieved. The temperature sensitivity and strain sensitivity of PCF-LPFG resonant wavelength are 0.002 nm/°C and 0.0018 nm/με, respectively. The PCF-LPFG resonant peak is insensitive to temperature or strain. The bending characteristics are directly related to curvature and bending direction. A direction with high sensitivity is chosen for further study. In a certain range of curvature, the bending sensitivity at PCF-LPFG resonant wavelength is -5.45 nm/m -1 and that at the resonant peak is 3.32 dB/m -1. Based on the special characteristics of PCF-LPFG, the paper provides new methods for fabricating temperature-insensitive strain and bending sensors.

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