对于打印机来说,衡量其好坏的参数也是五花八门,常让用户一头雾水。下面是整理的一些常见的英文字母缩写的含义,介绍如下: CPI:Characters Per Inch的缩写。每英寸内所含的字符数,用来表示字符的大小、间距。也就是说在一英寸那么大的地...对于打印机来说,衡量其好坏的参数也是五花八门,常让用户一头雾水。下面是整理的一些常见的英文字母缩写的含义,介绍如下: CPI:Characters Per Inch的缩写。每英寸内所含的字符数,用来表示字符的大小、间距。也就是说在一英寸那么大的地方,如果你写大字,可以写多少;如果是小字又可以写多少。 CPL:Characters Per Line的缩写。每行中所含的字符个数,用来在横向方向表示字符的宽度、间距。打个比方,如果在一张纸上,一行写上20个字和一行写上30个字。展开更多
The transverse permeability of unidirectional fiber tows is calculated using homogenization method.Each fiber tow consisting of 21 filaments is arranged in uniform square packing.Stokes governing equation is analogize...The transverse permeability of unidirectional fiber tows is calculated using homogenization method.Each fiber tow consisting of 21 filaments is arranged in uniform square packing.Stokes governing equation is analogized with Lame equation used in the linear elasticity problem and is solved by the finite element code ANSYS.The prediction for transverse permeability of unidirectional fiber obtained by the homogenization approach is compared with other analytical methods.The result shows a good agreement with Kozeny-Carman equation and Gebart square packing model.A model for nonuniform fiber distribution and measurement technology are proposed.It can be found that the experimental result is in excellent agreement with predicted permeability in the nonuniform distribution model.展开更多
It is difficult for normal moveout(NMO)correction of shallow long offset of vertical transversely isotropic medium,as seismic event after conventional NMO correction experienced strong stretching and distortion due to...It is difficult for normal moveout(NMO)correction of shallow long offset of vertical transversely isotropic medium,as seismic event after conventional NMO correction experienced strong stretching and distortion due to interleaving of signal.Even using higher order non-hyperbolic NMO correction,it still cannot get the right results.This paper aims to improve the accuracy of NMO correction.Based on the analysis of conventional NMO correction method and previous optimization move-out equation,we use longitudinal optimization method to correct seismic event.The results of the theoretical model and the real data show that our method can completely remove NMO stretching and greatly improve correction accuracy.展开更多
It is known from our former theoretical analysis that the single-inclined welding surface which is inclined towards the transverse direction of the rail can only eliminate vertical bumping, and the single-inclined wel...It is known from our former theoretical analysis that the single-inclined welding surface which is inclined towards the transverse direction of the rail can only eliminate vertical bumping, and the single-inclined welding surface which is inclined towards the vertical direction of the rail can only eliminate lateral vibration. In this paper, we put forward a welding structure of double-inclined welding surface to eliminate the vertical bumping and lateral vibration at the same time, and analyze the stress state of continuous welded rail (CWR) by combining geometrical azimuth. Furthermore, the increase of bearing capacity of CWR with the double-inclined welding surface is theoretically analyzed.展开更多
To enhance the oil and gas recovery rate, hydraulic fracturing techniques have been widely adopted for stimulation of low-permeability reservoirs. Pioneering work indicates that hydraulic perforation and layout could ...To enhance the oil and gas recovery rate, hydraulic fracturing techniques have been widely adopted for stimulation of low-permeability reservoirs. Pioneering work indicates that hydraulic perforation and layout could significantly affect fracture initiation and propagation in low-permeability reservoir rocks subjected to complex in-situ stresses. This paper reports on a novel numerical method that incorporates fracture mechanics principles and the numerical tools FRANC3D and ANSYS to investigate the three-dimensional initiation and propagation behavior of hydro-fracturing cracks in shale rock. Considering the transverse isotropic property of shale rocks, the mechanical parameters of reservoir rocks attained from laboratory tests were adopted in the simulation. The influence of perforation layouts on the 3D initiation of hydro-fracturing fractures in reservoir rocks under geo-stresses was quantitatively illuminated. The propagation and growth of fractures in three dimensions in different perforating azimuth values were illustrated. The results indicate that： 1） the optimal perforation direction should be parallel to the maximum horizontal principal stress, 2） the crack plane gradually turns toward the direction of the maximum horizontal principal stress when they are not in parallel, 3） compared with the linear and symmetric pattern, the staggered perforation is the optimal one, 4） the proper perforation density is four to six holes per meter, 5） the optimal perforation diameter in this model is 30 ram, and 6） the influence of the perforation depth on the fracture initiation pressure is low.展开更多
文摘对于打印机来说,衡量其好坏的参数也是五花八门,常让用户一头雾水。下面是整理的一些常见的英文字母缩写的含义,介绍如下: CPI:Characters Per Inch的缩写。每英寸内所含的字符数,用来表示字符的大小、间距。也就是说在一英寸那么大的地方,如果你写大字,可以写多少;如果是小字又可以写多少。 CPL:Characters Per Line的缩写。每行中所含的字符个数,用来在横向方向表示字符的宽度、间距。打个比方,如果在一张纸上,一行写上20个字和一行写上30个字。
基金Tianjin Natural Science Foundation, China (No.06YFJ MJC03100,013604311)
文摘The transverse permeability of unidirectional fiber tows is calculated using homogenization method.Each fiber tow consisting of 21 filaments is arranged in uniform square packing.Stokes governing equation is analogized with Lame equation used in the linear elasticity problem and is solved by the finite element code ANSYS.The prediction for transverse permeability of unidirectional fiber obtained by the homogenization approach is compared with other analytical methods.The result shows a good agreement with Kozeny-Carman equation and Gebart square packing model.A model for nonuniform fiber distribution and measurement technology are proposed.It can be found that the experimental result is in excellent agreement with predicted permeability in the nonuniform distribution model.
文摘It is difficult for normal moveout(NMO)correction of shallow long offset of vertical transversely isotropic medium,as seismic event after conventional NMO correction experienced strong stretching and distortion due to interleaving of signal.Even using higher order non-hyperbolic NMO correction,it still cannot get the right results.This paper aims to improve the accuracy of NMO correction.Based on the analysis of conventional NMO correction method and previous optimization move-out equation,we use longitudinal optimization method to correct seismic event.The results of the theoretical model and the real data show that our method can completely remove NMO stretching and greatly improve correction accuracy.
基金supported by the Major Research Project of Ministry of Railway of China (Grant No. 2010G006-H)
文摘It is known from our former theoretical analysis that the single-inclined welding surface which is inclined towards the transverse direction of the rail can only eliminate vertical bumping, and the single-inclined welding surface which is inclined towards the vertical direction of the rail can only eliminate lateral vibration. In this paper, we put forward a welding structure of double-inclined welding surface to eliminate the vertical bumping and lateral vibration at the same time, and analyze the stress state of continuous welded rail (CWR) by combining geometrical azimuth. Furthermore, the increase of bearing capacity of CWR with the double-inclined welding surface is theoretically analyzed.
基金supported by the National Natural Science Foundation for Distinguished Young Scholars of China(Grant No.51125017)the National Natural Science Foundation of China(Grant No.51374213)+2 种基金the Fund for Creative Research and Development Group Program of Jiangsu Province(2014)the Science Fund for Creative Research Groups of the National Natural Science Foundation of China(Grant No.51421003)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘To enhance the oil and gas recovery rate, hydraulic fracturing techniques have been widely adopted for stimulation of low-permeability reservoirs. Pioneering work indicates that hydraulic perforation and layout could significantly affect fracture initiation and propagation in low-permeability reservoir rocks subjected to complex in-situ stresses. This paper reports on a novel numerical method that incorporates fracture mechanics principles and the numerical tools FRANC3D and ANSYS to investigate the three-dimensional initiation and propagation behavior of hydro-fracturing cracks in shale rock. Considering the transverse isotropic property of shale rocks, the mechanical parameters of reservoir rocks attained from laboratory tests were adopted in the simulation. The influence of perforation layouts on the 3D initiation of hydro-fracturing fractures in reservoir rocks under geo-stresses was quantitatively illuminated. The propagation and growth of fractures in three dimensions in different perforating azimuth values were illustrated. The results indicate that： 1） the optimal perforation direction should be parallel to the maximum horizontal principal stress, 2） the crack plane gradually turns toward the direction of the maximum horizontal principal stress when they are not in parallel, 3） compared with the linear and symmetric pattern, the staggered perforation is the optimal one, 4） the proper perforation density is four to six holes per meter, 5） the optimal perforation diameter in this model is 30 ram, and 6） the influence of the perforation depth on the fracture initiation pressure is low.
