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Dynamic effects of high-pressure pulsed water jet in low-permeability coal seams

Journal of Coal Science & engineering(China) 2009年第3期15卷 284-288页

作者： LI Xiao-hong ZHOU Dong-ping LU Yi-yu KANG Yong ZHAO Yu WANG Xiao-chuan Key Lab for the Exploitation of Southwestern Resources ＆ Environmental Disaster Control Engineering Chongqing University Chongqing 400030 China

Mine gas extraction in China is difficult due to the characteristics such as micro-porosity,low-permeability and high adsorption of coal *** pulsed mechanismof a high-pressure pulsed water jet was studied through theoretical analysis,experimentand field *** results show that high-pressure pulsed water jet has threedynamic ***'s more,the three dynamic effects can be found in low-permeabilitycoal seams.A new pulsed water jet with 200-1 000 Hz oscillation frequency andpeak pressure 2.5 times than average pressure was *** bubble collapsing,sound vibration and instantaneous high pressures over 100 MPa enhanced the cuttingability of the high-pressure *** high-pressure pulsed water jet drilling and slotting,the exposure area of coal bodies was greatly enlarged and pressure of the coal seamsrapidly ***,the permeability of coal seams was improved and gas absorptionrate also *** results show that gas adsorption rate decreasedby 30%-40%and the penetrability coefficient increased 100 *** proves that high-pressurepulsed water is more efficient than other conventional methods.

关键词： high-pressure pulsed water jet gas desorption penetrability dynamic effects

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Analysis of optical transmission characteristics in the waveguide of side polished fiber

Analysis of optical transmission characteristics in the wave...

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2009 International Conference on Optical Instruments and Technology, OIT'09

作者： Zhe, Chen Zuping, He Fei, Cui Yating, Xiao Jun, Zhang Key Laboratory of Disaster Forecast and Control in Engineering Ministry of Education Jinan University 510632 China Key Lab. of Optoelectron. Info. and Sensing Technologies of Guangdong Higher Educational Institutes Jinan University Guangzhou 510632 China Department of Optoelectronic Engineering Jinan University Guangzhou510632 China

ISBN: (纸本)9780819478948

According to the experimental results of side polished fiber (SPF), a three dimensional optical waveguide model with longitudinal side polished transition zones is built. Based on the model, characteristics of optical transmission are calculated and analyzed by three dimensional finite differential beam propagation method. The model describes the optical transmission characteristics because the calculation based on the model is fitted well with the experiments. The calculation shows that the length of side polished area affects the optical attenuation of optical fiber, but the attenuation does not increased monotonically with the length when the length is less than certain value. The relationship between optical attenuation of SPF and the thickness of residual side polished cladding is not a monotonie one as well. The refractive index of overly on the side polished area has much more effect on the optical attenuation. Both width and thickness of overlay on the side polished area cause the oscillated change of optical power attenuation in the fiber core. © 2009 SPIE.

关键词： Light transmission

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Scattering of SH-wave by a shallow U-shaped tunnel

Scattering of SH-wave by a shallow U-shaped tunnel

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Joint Conference of the 2009 Symposium on Piezoelectricity, Acoustic Waves, and Device Applications, SPAWDA 2009 and 2009 China Symposium on Frequency control Technology

作者： Chen, Zhi-Gang Key Lab. of Disaster Forecast and Control in Engineering Department of Mechanics and Civil Engineering Jinan University Guangzhou 510632 China

ISBN: (纸本)9781424449507

In general, analytical solution for the scattering problem of SH plane wave by a cavity in half-space primarily focused on the circular structure case. However, the case for U-shaped cavities, which are similar to the cross-section of the tunnels, was seldom mentioned in former references. The analytical solution for U-shaped cavity in elastic half space is gained by the multi-polar coordinate system and conformal mapping method. A scattering wave function satisfying zero-stress condition on horizontal surface is constructed in the complex plane, the problem can be inverted into a set of algebraic equations to solve coefficients of the scattering wave by least square method. The numerical examples of the dynamic stress concentration around U-shaped cavities and ground motion on subsurface U-shaped cavity impacted by SH-wave are given. The influences of the incident wave number, angle and depth are discussed. The research indicates that the shallow U-shaped tunnel has significant impact on wave propagation, and interaction between the U-shaped tunnel and the horizontal surface will complicate characteristics of ground motion, and will bring about great increase on dynamic stress around cavity. In this situation, enough attention should be paid on the interaction between the subsurface cavity and the horizontal surface in the seismic design of ground and underground structures. © 2009 IEEE.

关键词： Wave propagation

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Scattering of SH-wave by a shallow U-shaped tunnel

Scattering of SH-wave by a shallow U-shaped tunnel

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SPAWDA Symposium on Piezoelectricity, Acoustic Waves, and Device Applications

作者： Zhi-gang Chen Key Lab of Disaster Forecast and Control in Engineering Ministry of Education Department of Mechanics and Civil Engineering Jinan University Guangzhou China

Summary form only given. In general, analytical solution for the scattering problem of SH plane wave by a cavity in half-space primarily focused on the circular structure case. However, the case for U-shaped cavities, which are similar to the cross-section of the tunnels, was seldom mentioned in former references. The analytical solution for U-shaped cavity in elastic half space is gained by the multi-polar coordinate system and conformal mapping method. A scattering wave function satisfying zero-stress condition on horizontal surface is constructed in the complex plane, the problem can be inverted into a set of algebraic equations to solve coefficients of the scattering wave by least square method. The numerical examples of the dynamic stress concentration around U-shaped cavities and ground motion on subsurface U-shaped cavity impacted by SH-wave are given. The influences of the incident wave number, angle and depth are discussed. The research indicates that the shallow U-shaped tunnel has significant impact on wave propagation, and interaction between the U-shaped tunnel and the horizontal surface will complicate characteristics of ground motion, and will bring about great increase on dynamic stress around cavity. In this situation, enough attention should be paid on the interaction between the subsurface cavity and the horizontal surface in the seismic design of ground and underground structures.

关键词： Scattering Stress Surface waves control engineering education Civil engineering Conformal mapping Wave functions Equations Least squares methods

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Wavelength tuning of fiber Bragg grating based on fiber side polishing

Wavelength tuning of fiber Bragg grating based on fiber side...

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International Conference on Optical Instruments and Technology - Advanced Sensor Technologies and Applications

作者： Chen Zhe Liu Linhe Jinan Univ Key Lab Disaster Forecast & Control Engn Minist Educ Peoples Republ China Guangzhou 510632 Guangdong Peoples R China Jinan Univ Dept Optoelect Engn Guangzhou 510632 Guangdong Peoples R China

ISBN: (纸本)9780819474018

Side polished fiber Bragg grating (SPFBG) is made as a side of cladding of a FBG is polished just to remain several micrometers by the a side polishing method, such as a method with a motor-driven polishing wheel. The response of Bragg wavelength of SPFBG to the refractive index of material overlaid on the polished area of SPFBG was investigated by both theoretical calculation and experiments. Both calculation and experiments showed that the Bragg wavelength of side polished FBG would shift to the longer as the refractive index of the overlaid material increased. The sensitivity of SPFBG to the refractive index of material overlaid on the side polished area could be used for wavelength tuning of FBG or as refractive index sensor.

关键词： wavelength tuning side polished fiber fiber Bragg grating beam propagation method refractive index

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Outburst orientation of sandstone under gravitational field

Beijing Keji Daxue Xuebao/Journal of University of Science a...

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Beijing Keji Daxue Xuebao/Journal of University of Science and Technology Beijing 2009年第12期31卷 1487-1491+1502页

作者： Guo, Chen-Ye Xian, Xue-Fu Li, Xiao-Hong Yao, Wei-Jing Jiang, Yong-Dong Key Lab. for Exploitation of Southwestern Resources and Environmental Disaster Control Engineering Chongqing University Chongqing 400030 China

The characters of outburst sandstone in rocks from Yongchuan Coal Mine were studied on the base of experimental investigation on its physical and mechanical properties. The outburst orientation of sandstone at the -350 m horizontal in this coal was analyzed and the criterion of outburst orientation was proposed. The results show that outburst sandstone has the physical characteristics of big porosity and big blowhole volume, and the mechanical characteristics of low Young's modulus, low strength, and not easy to produce plastic deformation. The launch process of rocks and gas outburst has uniformity with the rockburst characteristic, and the rockburst theory can be used to study the outburst orientation of sandstone, which depends on many kinds of factors. In these factors the mechanical factor is primary. The assessment method of outburst orientation of sandstone was established based on the energy criterion, strength criterion, and impact orientation criterion.

关键词： Sandstone

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Design of electrode for thermooptic variable optical attenuator based on side polished fiber

Design of electrode for thermooptic variable optical attenua...

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International Conference on Optical Instruments and Technology - Advanced Sensor Technologies and Applications

作者： Chen Zhe Zeng Yingxin Jinan Univ Minist Educ Peoples Republ China Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China Jinggangshan Univ Dept Optoelect Engn Guangzhou 510632 Peoples R China South China Agr Univ Dept Phys Guangzhou 510642 Peoples R China

ISBN: (纸本)9780819474018

Base on the heat transfer theory, the thermal models of thermooptic variable optical attenuator based on side-polished fiber surrounded by thermooptic polymer with electrode inside were built. The finite element method has been used to compute and analyze thermal distributions of the thermooptic models. The thermal distributions of both the models with single stick electrode or helical electrode were analyzed in three directions. According to the analysis, the helical electrode is a suitable electrode structure for thermooptic variable optical attenuator based on side-polished fiber.

关键词： side-polished fiber thermooptic polymer electrode thermal distribution finite element method

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Notice of Retraction: The Numerical Simulation of Crack Propagation without Re-Meshing

Notice of Retraction: The Numerical Simulation of Crack Prop...

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International Conference on Information engineering and Computer Science (ICIECS)

作者： Shuai Yang Hong Wang Xiao-zhou Xia Hong Yuan Coll. of Civil & Transp. Eng. GDUT Guangzhou China Key Lab. of Disaster Forecast & Control in Eng. Inst. of Appl. Mech. Guangzhou China

This article has been retracted by the publisher.

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Method of Green’s function of nonlinear vibration of corrugated shallow shells

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Science China(Physics,Mechanics & Astronomy) 2008年第6期51卷 678-686页

作者： YUAN Hong key laboratory of disaster forecast and control in engineering, Ministry of Education of China, Institute of Applied Mechanics, Jinan University, Guangzhou 510632, China 1. Key Laboratory of Disaster Forecast and Control in Engineering Ministry of Education of China Institute of Applied Mechanics Jinan University Guangzhou 510632 China

Based on the dynamic equations of nonlinear large deflection of axisymmetric shallow shells of revolution, the nonlinear free vibration and forced vibration of a corrugated shallow shell under concentrated load acting at the center have been investigated. The nonlinear partial differential equations of shallow shell were re-duced to the nonlinear integral-differential equations by using the method of Green’s function. To solve the integral-differential equations, the expansion method was used to obtain Green’s function. Then the integral-differential equations were reduced to the form with a degenerate core by expanding Green’s function as a series of characteristic function. Therefore, the integral-differential equations be-came nonlinear ordinary differential equations with regard to time. The ampli-tude-frequency relation, with respect to the natural frequency of the lowest order and the amplitude-frequency response under harmonic force, were obtained by considering single mode vibration. As a numerical example, nonlinear free and forced vibration phenomena of shallow spherical shells with sinusoidal corrugation were studied. The obtained solutions are available for reference to the design of corrugated shells.

关键词： corrugated shells spherical shells Green’s function integral equation nonlinear vibration

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Effect of Overlaid Material on Optical Transmission of Side-Polished Fiber Made by Wheel Side Polishing

Effect of Overlaid Material on Optical Transmission of Side-...

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1st Asia-Pacific Optical Fiber Sensors Conference

作者： Chen, Zhe Bai, Chunhe Jinan Univ Key Lab Disaster Forecast & Control Engn Minist Educ Peoples Republ China Guangzhou Guangdong Peoples R China

ISBN: (纸本)9781424421312

The performance of optical power transmission through a side polished fiber manufactured by wheel polishing method were investigated, in which materials of different refractive indices were overlaid on the polished surface. The experiments showed that the transmitted optical power through the side-polished fiber varied with the refractive index of the overlaid material. The result of our experiments fitted well the theoretical calculation. Side-polished fiber manufactured by wheel polishing method can not only be used to control optical power transmission through the fiber core but also be used as a refractive index sensor.

关键词： side polished fiber optical fiber optical power refractive index optical transmission

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