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Stress distribution and surrounding rock control of mining near to the overlying coal pillar in the working face

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International Journal of Mining Science and Technology 2019年第6期29卷 881-887页

作者： Rui Gao Bin Yu Xiangbin Meng Key Laboratory of Deep Coal Resource Mining School of MinesMinistry of Education of ChinaChina University of Mining&TechnologyXuzhou 221116China Datong Coal Mine Group Co.Ltd. Datong 037000China

The occurrence of overlying coal pillar(OCP)exerts a strong effect on the stress and strain distribution of the surrounding rock in the *** this paper,the stress distribution characteristics are analyzed via the numerical calculation with the account of OCP presence or *** addition,this study revealed the joint effect of side pressure relief area of the goaf and stress concentration in OCP on the final stress ***,the rules of abutment stress distribution affected by three influencing factors,namely horizontal-vertical distances between OCP and working face and buried depth of OCP,are *** functional model linking the peak stress of surrounding rock with the above influencing factors is *** field application of the above results proved that the rib spalling and deformation of a 2.95 m-high and 5.66 m-wide roadway could be efficiently controlled by rationally adjusting working states of the support,and adopting the hydraulic prop coordinated with the p type metal beam and anchor cable to strengthen the surrounding rock of working face and roadway,*** proposed measures are considered appropriate to satisfy the safe operation requirements.

关键词： Overlying coal pillar(OCP) Stress distribution Influencing factors Surrounding rock control

Dorroh extensions of algebras and coalgebras

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Frontiers of Mathematics in China 2021年第3期16卷 857-888页

作者： Lan YOU Huixiang CHEN School of Mathematical Science Yangzhou UniversityYangzhou225002China School of Mathematics and Physics Yancheng Institute of TechnologyYancheng224051China

We study Dorroh extensions of algebras and Dorroh extensions of *** structures are *** properties of these extensions are *** also introduce the finite duals of algebras and modules which are not necessarily *** these... 详细信息

关键词： Dorroh extension of algebra Dorroh extension of coalgebra Dorroh pair of coalgebras finite dual

Preparation, Characterization and Catalytic Performance of La-SO_4^(2-)/SBA-15 in Esterification of Acetic Acid with n-Butanol

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Chemical research in Chinese Universities 2008年第3期24卷 357-361页

作者： TIAN Zhi-ming DENG Qi-gang SUN Hui ZHAO De-feng State Key Laboratory of Fine Chemicals Dalian University of Technology Dalian 116012 P. R. China College of Chemistry and Chemical Engineering of Qiqihar University Qiqihar 161006 P. R. China

La-SO42-/SBA-15 was synthesized with various amounts of lanthanum via incipient-wetness impregnation. Characterization was done by X-ray diffraction（XRD）, transmission electron micrographs（TEM）, nitrogen adsorption, FTIR spectroscopic analysis, thermogravimetric analysis, and the total amount of acidity of catalyst was estimated by TPD of NH3. The results indicate that lanthanum has been incorporated into SBA-15 molecular sieve. The prepared materials（La-SO42-/SBA-15） keep the highly ordered mesoporous two-dimensional hexagonal structure and do not change the mesoporous channel structure of the support SBA-15. The catalyst showed best catalytic activity in the synthesis of n-butyl acetate. The optimum conditions of the esterification by orthogonal experiments were studied： the molar ratio of n-butanol to acetic acid 1：1.2, the amount of catalyst 7.5%, reaction time 80 min. The yield of n-butyl acetate could reach 93.2% under the optimum conditions. The catalyst was recyclable, cost effective and environmental friendly.

关键词： SBA-15 molecular sieve La-SO462-/SBA-15 Catalysis n-Butyl acetate Esterification

Risk analysis for a cascade reservoir system using the brittle risk entropy method

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Science China(Technological Sciences) 2016年第6期59卷 882-887页

作者： YANG Yin REN Qing Wen TIAN Ying XIONG Yao College of Hydraulic Conservation and Hydropower Engineering Hohai University Department of Engineering Mechanics Hohai University

The principal means of conserving water and utilizing hydropower in China is to exploit the use of a series of reservoirs in a cascade. This method and its inherent engineering safety problems are receiving increasing attention nowadays. In the field of engineering safety analysis, much work has focused on single reservoir projects in the past few years, but there is little research available on the safety risk analysis of cascade reservoirs, either within China or internationally. Therefore, a framework for risk analysis on the cascade reservoir system based on the theory of system engineering is constructed in this article. A cascading failure model is established and the connection degree factor discussed. In addition, the importance degree of the subsystem, which can be calculated by combining the analytical hierarchy process and the entropy weight method, is explained. According to brittleness theory of a complex system, brittle risk entropy is proposed as a performance index for measuring the collapse uncertainty of the cascade reservoir system. In addition, the brittle risk of the cascade reservoir system is predicted, which provides a reference for safety analysis in water conservation and hydropower construction projects in China.

关键词： cascading failure model safety analysis risk assessment complex system brittle risk entropy

Effect of distance between heat sources on droplet transfer behavior and weld formation of AH36 during laser and CWW GMAW arc hybrid welding

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Journal of Iron and Steel research International 2024年第12期31卷 3069-3079页

作者： Yun-tao Chen Zhi-dong Yang Zheng-xuan Ni Jiang-min Xu Shan-wen Dong Guo-xiang Xu Shu-jin Chen College of Materials Science and Engineering Jiangsu University of Science and TechnologyZhenjiang212100JiangsuChina Marine Equipment research Institute Jiangsu University of Science and TechnologyZhenjiang212100JiangsuChina College of Mechanical Engineering Yancheng Institute of TechnologyZhenjiang224051JiangsuChina

In order to analyze the influence of the distance between heat sources(D_(LA))on the welding process,the effects of D_(LA)on the droplet transfer behavior,weld formation characteristics and weld formation mechanism of AH36 in laser and cable-type welding wire gas metal arc welding arc hybrid welding were ***-time photography was conducted using a high-speed camera to determine the droplet transfer and arc behaviors;the surface morphology and macroscopic cross-section of the weld obtained from the experiment were observed and *** arc height decreases with the increase in the DLA,the arc width shows the opposite change,and the welding current *** allure of the laser to the arc increases with the increase in the D_(LA).The frequency of droplet transfer increases with the increase in the D_(LA),but the growth rate *** continuous increase in the D_(LA)leads to the tendency of the droplet size to decrease first and then increase,and the minimum value is obtained when the D_(LA)is 4 *** D_(LA)has obvious influence on the weld *** weld penetration and reinforcement change similarly,increasing first and then decreasing as the D_(LA)increases,and the laser area of the weld also increases first and then decreases.

关键词： Laser-arc hybrid welding Cable-type welding wire Distance between heat sources Droplet transfer behavior Weld formation

Damage identification method of girder bridges based on finite element model updating and modal strain energy

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Science China(Technological Sciences) 2015年第4期58卷 701-711页

作者： NIU Jie ZONG Zhou Hong CHU Fu Peng School of Civil Engineering Southeast University Vibration Engineering Section College of Engineering Mathematics and Physical Sciences University of Exeter Fujian Academy of Building research

A timely and accurate damage identification for bridge structures is essential to prevent sudden failures/collapses and other catastrophic *** on response surface model(RSM)updating and element modal strain energy(EMSE)damage index,this paper proposes a novel damage identification method for girder bridge *** effectiveness of the proposed damage identification method is investigated using experiments on four simply supported steel *** Xiabaishi Bridge,a prestressed continuous rigid frame bridge with large span,as the engineering background,the proposed damage identification method is validated by using numerical simulation to generate different bearing damage ***,the efficiency of the method is justified by considering its application to identifying cracking damage for a real continuous beam bridge called Xinyihe *** is concluded that the EMSE damage index is sensitive to the cracking damage and the bearing *** locations and levels of multiple cracking damages and bearing damages can be also *** results illuminate a great potential of the proposed method in identifying damages of real bridge structures.

关键词： damage identification response surface model finite element model updating element modal strain energy damage index girder bridge

Changes in soil temperature and water content under mobile soil steam disinfection

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International Journal of Agricultural and Biological Engineering 2021年第3期14卷 140-147页

作者： Zhenjie Yang Xiaochan Wang Muhammad Ameen College of Engineering Nanjing Agricultural UniversityNanjing 210031China College of Mechanical and Electrical Engineering Yunnan Agricultural UniversityKunming 650201China

The soil steam injection method is one of the most effective disinfection methods,and the determination of the steam pipe structure parameters is very *** steam capillary diameter(SCD)affects the steam flow field in each pipe,which in turn affects the steam changes in the soil flow range and soil temperature(ST).Larger SCD would make lower ST in clay loam,silt loam,and sandy clay *** effectiveness of an SCD of 10 mm was verified by a mobile disinfection test at walking speeds of 10 cm/min and 30 cm/min under soil water content(SWC)of 15%and 35%,*** results showed that when the walking speed was 10 cm/min,the initial SWC was proportional to the ***,when the walking speed was 30 cm/min,the law was exactly the opposite;that is,the initial water content is inversely proportional to the *** research can provide a theoretical research foundation for increasing soil temperature for efficient soil steam disinfection.

关键词： soil steam disinfection steam capillary diameter steam capillary vent soil temperature soil water content

Optical performance study of Sr_2ZnSi_2O_7:Eu^(2+),Dy^(3+), SrAl_2O_4:Eu^(2+),Dy^(3+) and Y_2O_2S:Eu^(3+),Mg^(2+),Ti^(4+) ternary luminous fiber

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Journal of Rare Earths 2016年第12期34卷 1206-1212页

作者：晋阳龙啸云朱亚楠葛明桥 School of Textile and Clothing Jiangnan University

In this study, down-conversion fluorescent powder of Sr2ZnSi2O7：Eu-（2＋）,Dy-（3＋）, SrAl2O4：Eu-（2＋）,Dy-（3＋） and Y2O2S：Eu-（3＋）,Mg-（2＋）,Ti-（4＋）, which were the common three primary colors materials with long afterglow, were synthesized by high temperature solid state method. The blends of rare earth（RE） luminescent materials have been of interest to reinvest the luminescent characteristics of polyethylene terephtahalate（PET） luminous fiber. The scanning electron microscopy（SEM） and an inversion fluorescence microscope were used to characterize the surface morphology and the dispersion of inclusion. Through analysis of microcosmic morphology, three typical dispersions of luminescent particles were summarized. The X-ray diffraction indicated that the phase structure of fiber samples and crystal structure of luminescence materials kept complete after prilling and spinning. From the fluorescence spectra and CIE 1931 coordinates, it could be found that different combinations of luminous fibers were desired to obtain divers colors emission luminous fiber. And the fiber samples were a light sensation which could induct different excitation wavelengths and convert it down to different colors. The afterglow decay curve and its differential curve were summarized indicating the three decay stages. The decay curve and decay rate curve showed that the contents of Sr2ZnSi2O7：Eu-（2＋）,Dy-（3＋）, SrAl2O4：Eu-（2＋）,Dy-（3＋） and Y2O2S：Eu-（3＋）,Mg-（2＋）,Ti-（4＋） had obvious influence on the afterglow of fiber samples.

关键词： luminous fiber Sr_2ZnSi_2O_7:Eu^2+ Dy^3+ SrAl_2O_4:Eu^2+ Dy^3+ Y_2O_2S:Eu^3+ Mg^2+ Ti^4+ down-conversion light sensation rare earths

Substructuring Technique for Dynamics Analysis of Flexible Beams with Large Deformation

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Journal of Shanghai Jiaotong university(Science) 2017年第5期22卷 562-569页

作者：张建书芮筱亭刘飞飞周秦渤顾利琳 Institute of Launch Dynamics Nanjing University of Science&TechnologyNanjing 210094China

In this paper, the substructuring technique is extended for the dynamics simulation of flexible beams with large deformation. The dynamics equation of a spatial straight beam undergoing large displacement and small deformation is deduced by using the Jourdain variation principle and the model synthesis method. The longitudinal shortening effect due to the transversal deformation is taken into consideration in the dynamics equation. In this way, the geometric stiffening effect, which is also called stress stiffening effect, is accounted for in the dynamics equation. The transfer equation of the flexible beam is obtained by assembling the dynamics equation and the kinematic relationship between the two connection points of the flexible beam. Treating a flexible beam with small deformation as a substructure, one can solve the dynamics of a flexible beam with large deformation by using the substructuring technique and the transfer matrix method. The dynamics simulation of a flexible beam with large deformation is carried out by using the proposed approach and the results are verified by comparing with those obtained from Abaqus software.

关键词： flexible beam large deformation substructure model synthesis