Based on cutting principle and technology development of vertical blasthole cutby stage and deck in vertical shaft excavation, combined with the merits of middle spacecharging and toe space charging, the reinforced cu...Based on cutting principle and technology development of vertical blasthole cutby stage and deck in vertical shaft excavation, combined with the merits of middle spacecharging and toe space charging, the reinforced cutting effect of central large-diameterblasthole and the method of cutting blast by stage and deck toe space charging for thevertical large-diameter blastholes was put forward and analyzed theoretically.This new cutblasting method is provided with the advantages of high blasthole using ratio, big cavitybulk, low rate of chunk, even lumpiness, and relatively high energy using ratio.The parameterchoices and practical effects of this cutting method were discussed after in situexperiment.It shows that the decked delay time of 75～100 ms is applicable.展开更多
Mixing problems are most likely encountered and sometimes can be severe in scaling-up projects. Micro-mixing is an important aspect for fast or quasi-instantaneous reactions. Poor micro-mixing might produce more undes...Mixing problems are most likely encountered and sometimes can be severe in scaling-up projects. Micro-mixing is an important aspect for fast or quasi-instantaneous reactions. Poor micro-mixing might produce more undesired by-products, leading to higher purification costs. This paper gives an extensive review and analysis of micro-mixing studies in single- and multi phase stirred tanks. The relevant experiment techniques, micro-mixing models and nurherical approaches are critically reviewed and analyzed with remarks and perspectives. The reported studies on two-phase micro-mixing experiments and on the impact of the presence of the dispersed phases on turbulence have been limited to a narrow range of conditions. More importantly, disparities widely exist among different reports. Both Lagrangian and Eulerian models are based on oversimplified assumptions, which may lead to uncertainties or even unrealistic results. A heuristic model, which is from the perspective of CFD （computational fluid dynamics） and can cover the whole spectrum of scales and also focus on every subrocess, is desired in the future.展开更多
This paper discusses the methodological specialty of the theoretical investigation in the nanotechnology. In the nanotechnoscience, on the one hand, similar with the classical natural science are created explanatory s...This paper discusses the methodological specialty of the theoretical investigation in the nanotechnology. In the nanotechnoscience, on the one hand, similar with the classical natural science are created explanatory schemes of the natural phenomena and formulated predictions of the course of the definite natural events on the basis of mathematics and experimental data, and on the other, as in the engineering sciences are constructed not only the projects of the new experimental situations but also structural schemes of the new nanosystem unknown in nature and technology. The operation of nanotheory is realized by the iteration method. At first a special engineering problem is formulated. Then it is represented in the form of the structural scheme of the nanosystem which is transformed into the idea about the natural process reflecting its performance. To calculate and mathematically model this process a functional scheme is constructed. Consequently, the engineering problem is reformulated into a scientific one and then into a mathematical problem solved by the deductive method. This path from the bottom to the top represents the analysis of schemes （the bottom up approach）. The way in the opposite direction--the synthesis of schemes （the top down approach）--makes it possible to synthesize the ideal model of a new nanosystem from idealized structural elements, according to the appropriate rules of deductive transformation, to calculate basic parameters of the nanosystem and simulate its function. Nanotechnology is at the same time a field of scientific knowledge and a sphere of engineering activity, in other words--nanotechnoscience--similar with systems engineering as the analysis and design of large-scale, complex, man-machine systems, but now as micro- and nanosystems. Scanning tunneling microscope in the nanoexperiment is not only an arrangement of scientific investigation but also at the same time a facility to fabricate the electrically conducting bridges between an electrode and the selected nanotubes and computer modeling and the design of different artifacts.展开更多
基金Supported by the National Natural Science Foundation of China(50764001)Ministry of Education"Chunhui Program",Guizhou Outstanding Young Talents Foundation(200705)Scientific and Technological Tack-ling Project of Guizhou Province(20073015)
文摘Based on cutting principle and technology development of vertical blasthole cutby stage and deck in vertical shaft excavation, combined with the merits of middle spacecharging and toe space charging, the reinforced cutting effect of central large-diameterblasthole and the method of cutting blast by stage and deck toe space charging for thevertical large-diameter blastholes was put forward and analyzed theoretically.This new cutblasting method is provided with the advantages of high blasthole using ratio, big cavitybulk, low rate of chunk, even lumpiness, and relatively high energy using ratio.The parameterchoices and practical effects of this cutting method were discussed after in situexperiment.It shows that the decked delay time of 75～100 ms is applicable.
基金Supported by the State Key Development Program for Basic Research of China (2010CB630904)the National Natural Science Fund for Distinguished Young Scholars (21025627)+2 种基金the National Natural Science Foundation of China (21106154,20990224)the National High Technology Research and Development Program of China (2011AA060704)the Beijing Natural Science Foundation (2112038) and Jiangsu Province Project (BY2009133)
文摘Mixing problems are most likely encountered and sometimes can be severe in scaling-up projects. Micro-mixing is an important aspect for fast or quasi-instantaneous reactions. Poor micro-mixing might produce more undesired by-products, leading to higher purification costs. This paper gives an extensive review and analysis of micro-mixing studies in single- and multi phase stirred tanks. The relevant experiment techniques, micro-mixing models and nurherical approaches are critically reviewed and analyzed with remarks and perspectives. The reported studies on two-phase micro-mixing experiments and on the impact of the presence of the dispersed phases on turbulence have been limited to a narrow range of conditions. More importantly, disparities widely exist among different reports. Both Lagrangian and Eulerian models are based on oversimplified assumptions, which may lead to uncertainties or even unrealistic results. A heuristic model, which is from the perspective of CFD （computational fluid dynamics） and can cover the whole spectrum of scales and also focus on every subrocess, is desired in the future.
文摘This paper discusses the methodological specialty of the theoretical investigation in the nanotechnology. In the nanotechnoscience, on the one hand, similar with the classical natural science are created explanatory schemes of the natural phenomena and formulated predictions of the course of the definite natural events on the basis of mathematics and experimental data, and on the other, as in the engineering sciences are constructed not only the projects of the new experimental situations but also structural schemes of the new nanosystem unknown in nature and technology. The operation of nanotheory is realized by the iteration method. At first a special engineering problem is formulated. Then it is represented in the form of the structural scheme of the nanosystem which is transformed into the idea about the natural process reflecting its performance. To calculate and mathematically model this process a functional scheme is constructed. Consequently, the engineering problem is reformulated into a scientific one and then into a mathematical problem solved by the deductive method. This path from the bottom to the top represents the analysis of schemes （the bottom up approach）. The way in the opposite direction--the synthesis of schemes （the top down approach）--makes it possible to synthesize the ideal model of a new nanosystem from idealized structural elements, according to the appropriate rules of deductive transformation, to calculate basic parameters of the nanosystem and simulate its function. Nanotechnology is at the same time a field of scientific knowledge and a sphere of engineering activity, in other words--nanotechnoscience--similar with systems engineering as the analysis and design of large-scale, complex, man-machine systems, but now as micro- and nanosystems. Scanning tunneling microscope in the nanoexperiment is not only an arrangement of scientific investigation but also at the same time a facility to fabricate the electrically conducting bridges between an electrode and the selected nanotubes and computer modeling and the design of different artifacts.
