Based on the engineering background of double-unit face mining under complicated geological conditions and the lagging fully-mechanized face surpassing the fore mechanized face of double-unit face in Zhou Yuanshan coa...Based on the engineering background of double-unit face mining under complicated geological conditions and the lagging fully-mechanized face surpassing the fore mechanized face of double-unit face in Zhou Yuanshan coal mine, strata-pressure behavior in the process was analyzed based on FLAC3D and on-site measurement. The results show that the stress concentration factor of superposition abutment pressure and the alternate distance of double-unit face are meeting gauss function, the relationship between the depth of stress concentration point and alternate distance also meets gaussian function. When the alternate distance is larger than 24 m, the superimposition of pilot support pressure in the double-unit face is weak. When the alternate distance is more than 12-15 m, the changes of the roof subsidence coefficient and the depth of stress con- centration point are stabilized; when the alternate distance is 3-6 m, the fore working face end is in the greatest impact area of superposition abutment pressure, this area should be avoided in determining the reasonable alternate distance.展开更多
Mg-x(Ti0.9 Zr0.2 Mn1.5 Cr0.3)(x=20%,30%,40%) (mass fraction) composite powders were prepared by reactive ball milling with hydrogen and their hydrogen storage properties and microstructure were investigated by XRD,SEM...Mg-x(Ti0.9 Zr0.2 Mn1.5 Cr0.3)(x=20%,30%,40%) (mass fraction) composite powders were prepared by reactive ball milling with hydrogen and their hydrogen storage properties and microstructure were investigated by XRD,SEM and pressure-composition-temperature measurement.The results show that the composites have 3.83%-5.07%hydrogen capacity at 553 K and good hydrogenation kinetics,even at room temperature.Among them,the milled Mg-30%(Ti0.9Zr0.2Mn1.5Cr0.3)composite has the highest hydrogenation kinetics as it can quickly absorb 2.1%hydrogen at 373 K,3.5%in 2 000 s at 473 K,even 3.26%in 60 s at 553 K under 3 MPa hydrogen pressure.The improved hydrogenation properties come from the catalytic effect of Ti0.9 Zr0.2 Mn1.5 Cr0.3 particles dispersed uniformly on the surface of Mg particles.展开更多
This paper is to study the two-dimensional stress distribution of a finite functionally graded material (FGM) plate with a circular hole under arbitrary constant loads. Using the method of piece-wise homogeneous layer...This paper is to study the two-dimensional stress distribution of a finite functionally graded material (FGM) plate with a circular hole under arbitrary constant loads. Using the method of piece-wise homogeneous layers, the stress analysis of the finite FGM plate having radial arbitrary elastic properties is made based on the complex variable method combined with the least square boundary collocation technique. Numerical results of stress distribution around the hole are then presented for different loading conditions, different material properties and different plate sizes, respectively. It is shown that the stress concentration in the finite plate is generally enhanced compared with the case of an infinite plate, but it can be significantly reduced by choosing proper change ways of the radial elastic modulus.展开更多
Based on the theory of the complex variable functions, the analysis of non-axisymmetric thermal stresses in a finite matrix containing a circular inclusion with functionally graded interphase is presented by means of ...Based on the theory of the complex variable functions, the analysis of non-axisymmetric thermal stresses in a finite matrix containing a circular inclusion with functionally graded interphase is presented by means of the least square boundary collocation technique. The distribution of thermal stress for the functionally graded interphase layer with arbitrary radial material parameters is derived by using the method of piece-wise homogeneous layers when the finite matrix is subjected to uniform heat flow. The effects of matrix size, interphase thickness and compositional gradient on the interfacial thermal stress are discussed in detail. Numerical results show that the magnitude and distribution of interfacial thermal stress in the inclusion and matrix can be designed properly by controlling these parameters.展开更多
基金Supported by the National Natural Science Foundation of China （50974059）
文摘Based on the engineering background of double-unit face mining under complicated geological conditions and the lagging fully-mechanized face surpassing the fore mechanized face of double-unit face in Zhou Yuanshan coal mine, strata-pressure behavior in the process was analyzed based on FLAC3D and on-site measurement. The results show that the stress concentration factor of superposition abutment pressure and the alternate distance of double-unit face are meeting gauss function, the relationship between the depth of stress concentration point and alternate distance also meets gaussian function. When the alternate distance is larger than 24 m, the superimposition of pilot support pressure in the double-unit face is weak. When the alternate distance is more than 12-15 m, the changes of the roof subsidence coefficient and the depth of stress con- centration point are stabilized; when the alternate distance is 3-6 m, the fore working face end is in the greatest impact area of superposition abutment pressure, this area should be avoided in determining the reasonable alternate distance.
基金Projects(20833009,20873148,U0734005) supported by the National Natural Science Foundation of ChinaProject(2010CB631303) supported by the National Basic Research Program of China+2 种基金Project(2009A11GX052) supported by Dalian Science and Technology Foundation,ChinaProject(KFJJ10-1Z) supported by the State Key Laboratory of Explosion Science and Technology,Beijing Institute of Technology,ChinaProject(Y4090507) supported by the Zhejiang Basic Research Program of China
文摘Mg-x(Ti0.9 Zr0.2 Mn1.5 Cr0.3)(x=20%,30%,40%) (mass fraction) composite powders were prepared by reactive ball milling with hydrogen and their hydrogen storage properties and microstructure were investigated by XRD,SEM and pressure-composition-temperature measurement.The results show that the composites have 3.83%-5.07%hydrogen capacity at 553 K and good hydrogenation kinetics,even at room temperature.Among them,the milled Mg-30%(Ti0.9Zr0.2Mn1.5Cr0.3)composite has the highest hydrogenation kinetics as it can quickly absorb 2.1%hydrogen at 373 K,3.5%in 2 000 s at 473 K,even 3.26%in 60 s at 553 K under 3 MPa hydrogen pressure.The improved hydrogenation properties come from the catalytic effect of Ti0.9 Zr0.2 Mn1.5 Cr0.3 particles dispersed uniformly on the surface of Mg particles.
基金supported by the National Natural Science Foundation of China (Grant No. 10972103)the Ph.D. Programs Foundation of Ministry of Education of China (Grant No. 20093218110004)+1 种基金the Funding of Jiangsu Innovation Program for Graduate Education (Grant No.CXZZ11_0191)Funding for Outstanding Doctoral Dissertation in NUAA (Grant No. BCXJ11-03)
文摘This paper is to study the two-dimensional stress distribution of a finite functionally graded material (FGM) plate with a circular hole under arbitrary constant loads. Using the method of piece-wise homogeneous layers, the stress analysis of the finite FGM plate having radial arbitrary elastic properties is made based on the complex variable method combined with the least square boundary collocation technique. Numerical results of stress distribution around the hole are then presented for different loading conditions, different material properties and different plate sizes, respectively. It is shown that the stress concentration in the finite plate is generally enhanced compared with the case of an infinite plate, but it can be significantly reduced by choosing proper change ways of the radial elastic modulus.
基金supported by the National Natural Science Foundation of China(Grant No.11232007)the Funding for Outstanding Doctoral Dissertation in Nanjing University of Aeronautics and Astronautics(Grant No.BCXJ11-03)Funding of Jiangsu Innovation Program for Graduate Education(Grant No.CXZZ11_0191)
文摘Based on the theory of the complex variable functions, the analysis of non-axisymmetric thermal stresses in a finite matrix containing a circular inclusion with functionally graded interphase is presented by means of the least square boundary collocation technique. The distribution of thermal stress for the functionally graded interphase layer with arbitrary radial material parameters is derived by using the method of piece-wise homogeneous layers when the finite matrix is subjected to uniform heat flow. The effects of matrix size, interphase thickness and compositional gradient on the interfacial thermal stress are discussed in detail. Numerical results show that the magnitude and distribution of interfacial thermal stress in the inclusion and matrix can be designed properly by controlling these parameters.
