The 121 mining method of longwall mining first proposed in England has been widely used around the world.This method requires excavation of two mining roadways and reservation of one coal pillar to mine one working fa...The 121 mining method of longwall mining first proposed in England has been widely used around the world.This method requires excavation of two mining roadways and reservation of one coal pillar to mine one working face.Due to considerable excavation of roadway,the mining roadway is generally destroyed during coal mining.The stress concentration in the coal pillar can cause large deformation of surrounding rocks,rockbursts and other disasters,and subsequently a large volume of coal pillar resources will be wasted.To improve the coal recovery rate and reduce excavation of the mining roadway,the 111 mining method of longwall mining was proposed in the former Soviet Union based on the 121 mining method.The 111 mining method requires excavation of one mining roadway and setting one filling body to replace the coal pillar while maintaining another mining roadway to mine one working face.However,because the stress transfer structure of roadway and working face roof has not changed,the problem of stress concentration in the surrounding rocks of roadway has not been well solved.To solve the above problems,the conventional concept utilizing high-strength support to resist the mining pressure for the 121 and 111 mining methods should be updated.The idea is to utilize mining pressure and expansion characteristics of the collapsed rock mass in the goaf to automatically form roadways,avoiding roadway excavation and waste of coal pillar.Based on the basic principles of mining rock mechanics,the“equilibrium mining”theory and the“short cantilever beam”mechanical model are proposed.Key technologies,such as roof directional presplitting technology,negative Poisson’s ratio(NPR)high-prestress constant-resistance support technology,and gangue blocking support technology,are developed following the“equilibrium mining”theory.Accordingly,the 110 and N00 mining methods of an automatically formed roadway(AFR)by roof cutting and pressure releasing without pillars are proposed.The mining methods have been applied to a large nu展开更多
This paper mainly discusses fractional differential approach to detecting textural features of digital image and its fractional differential filter. Firstly, both the geo- metric meaning and the kinetic physical meani...This paper mainly discusses fractional differential approach to detecting textural features of digital image and its fractional differential filter. Firstly, both the geo- metric meaning and the kinetic physical meaning of fractional differential are clearly explained in view of information theory and kinetics, respectively. Secondly, it puts forward and discusses the definitions and theories of fractional stationary point, fractional equilibrium coefficient, fractional stable coefficient, and fractional grayscale co-occurrence matrix. At the same time, it particularly discusses frac- tional grayscale co-occurrence matrix approach to detecting textural features of digital image. Thirdly, it discusses in detail the structures and parameters of nxn any order fractional differential mask on negative x-coordinate, positive x-coordi- nate, negative y-coordinate, positive y-coordinate, left downward diagonal, left upward diagonal, right downward diagonal, and right upward diagonal, respectively. Furthermore, it discusses the numerical implementation algorithms of fractional differential mask for digital image. Lastly, based on the above-mentioned discus- sion, it puts forward and discusses the theory and implementation of fractional differential filter for digital image. Experiments show that the fractional differential-based image operator has excellent feedback for enhancing the textural details of rich-grained digital images.展开更多
基金This work was supported by the Natural Science Foundation of China(Grant Nos.52074164 and 42077267)the Major Scientific and Technological Innovation Project of Shandong Province,China(Grant No.2019SDZY04)。
文摘The 121 mining method of longwall mining first proposed in England has been widely used around the world.This method requires excavation of two mining roadways and reservation of one coal pillar to mine one working face.Due to considerable excavation of roadway,the mining roadway is generally destroyed during coal mining.The stress concentration in the coal pillar can cause large deformation of surrounding rocks,rockbursts and other disasters,and subsequently a large volume of coal pillar resources will be wasted.To improve the coal recovery rate and reduce excavation of the mining roadway,the 111 mining method of longwall mining was proposed in the former Soviet Union based on the 121 mining method.The 111 mining method requires excavation of one mining roadway and setting one filling body to replace the coal pillar while maintaining another mining roadway to mine one working face.However,because the stress transfer structure of roadway and working face roof has not changed,the problem of stress concentration in the surrounding rocks of roadway has not been well solved.To solve the above problems,the conventional concept utilizing high-strength support to resist the mining pressure for the 121 and 111 mining methods should be updated.The idea is to utilize mining pressure and expansion characteristics of the collapsed rock mass in the goaf to automatically form roadways,avoiding roadway excavation and waste of coal pillar.Based on the basic principles of mining rock mechanics,the“equilibrium mining”theory and the“short cantilever beam”mechanical model are proposed.Key technologies,such as roof directional presplitting technology,negative Poisson’s ratio(NPR)high-prestress constant-resistance support technology,and gangue blocking support technology,are developed following the“equilibrium mining”theory.Accordingly,the 110 and N00 mining methods of an automatically formed roadway(AFR)by roof cutting and pressure releasing without pillars are proposed.The mining methods have been applied to a large nu
基金Supported by China Postdoctoral Science Foundation (Grant No. 20060401016), Fondation Franco-Chinoise Pour La Science Et Ses Applications (FFCSA)the National Natural Science Foundation of China (Grant No. 60572033)the Doctor Foundation of China National Education Department (Grant No. 20060610021)
文摘This paper mainly discusses fractional differential approach to detecting textural features of digital image and its fractional differential filter. Firstly, both the geo- metric meaning and the kinetic physical meaning of fractional differential are clearly explained in view of information theory and kinetics, respectively. Secondly, it puts forward and discusses the definitions and theories of fractional stationary point, fractional equilibrium coefficient, fractional stable coefficient, and fractional grayscale co-occurrence matrix. At the same time, it particularly discusses frac- tional grayscale co-occurrence matrix approach to detecting textural features of digital image. Thirdly, it discusses in detail the structures and parameters of nxn any order fractional differential mask on negative x-coordinate, positive x-coordi- nate, negative y-coordinate, positive y-coordinate, left downward diagonal, left upward diagonal, right downward diagonal, and right upward diagonal, respectively. Furthermore, it discusses the numerical implementation algorithms of fractional differential mask for digital image. Lastly, based on the above-mentioned discus- sion, it puts forward and discusses the theory and implementation of fractional differential filter for digital image. Experiments show that the fractional differential-based image operator has excellent feedback for enhancing the textural details of rich-grained digital images.
