According to the recently developed single-trough floating machine with the world's largest volume(inflatable mechanical agitation flotation machine with volume of 320 m3) in China, the gas-fluid two-phase flow in...According to the recently developed single-trough floating machine with the world's largest volume(inflatable mechanical agitation flotation machine with volume of 320 m3) in China, the gas-fluid two-phase flow in flotation cell was simulated using computational fluid dynamics method. It is shown that hexahedral mesh scheme is more suitable for the complex structure of the flotation cell than tetrahedral mesh scheme, and a mesh quality ranging from 0.7 to 1.0 is obtained. Comparative studies of the standard k-ε, k-ω and realizable k-ε turbulence models were carried out. It is indicated that the standard k-ε turbulence model could give a result relatively close to the practice and the liquid phase flow field is well characterized. In addition, two obvious recirculation zones are formed in the mixing zones, and the pressure on the rotor and stator is well characterized. Furthermore, the simulation results using improved standard k-ε turbulence model show that surface tension coefficient of 0.072, drag model of Grace and coefficient of 4, and lift coefficient of 0.001 can be achieved. The research results suggest that gas-fluid two-phase flow in large flotation cell can be well simulated using computational fluid dynamics method.展开更多
In response to horror stories throughout the country concerning childhood deaths from sniffing model airplane glue, organizations around Louisiana would begin lobbying for legislation to criminalize the practice in 19...In response to horror stories throughout the country concerning childhood deaths from sniffing model airplane glue, organizations around Louisiana would begin lobbying for legislation to criminalize the practice in 1966. State lawmakers spent much of that summer crafting an anti-glue-sniffing measure for the state. The debates that resulted from the attempt, however, never really focused on the sustainability or practical use of such a law, but instead on the kind of law it would ultimately be -- whether, for example, retailers would be liable for selling glue to minors, even though model airplanes and other kits and toys required such items. Or whether the ingredients in model airplane glue could be classed as schedule one narcotics. Such questions ultimately framed a debate about the fundamental nature of the offense being committed. Ultimately, （unlike other Deep South states） Louisiana decided that sniffing glue was not a drug crime. Instead, it was a problem that affected ＂the health and morals of minors＂.展开更多
Because of the success of the discrete vortex method for the simulation of large-scale vortex structure, many researchers extend this method to two-phase flow simulations, especially, to the simulation of particle dis...Because of the success of the discrete vortex method for the simulation of large-scale vortex structure, many researchers extend this method to two-phase flow simulations, especially, to the simulation of particle dispersion in mixing layer, which is characterized by large-scale vortex structure. But the previous work is limited to one-way coupling, which neglects the effect of particles on fluid flow. In this paper, a discrete vortex method involving two-way coupling for two-phase flows is first proposed and then used in numerical simulation of two-dimensional gas-particle mixing layers. The numerical results show that the introduction of particles into the mixing layer has significant effects on the creation, development and merging process of large-scale vortex structures. It makes the mean size of large-scale vortex structure larger and the distance needed for development of large-scale vortex structure shorter.展开更多
The idea of abolishing the death penalty is increasingly accepted as a goal by scholars in the field of criminal law, who have put aside all consideration of national realities and the crime situation. Among the facto...The idea of abolishing the death penalty is increasingly accepted as a goal by scholars in the field of criminal law, who have put aside all consideration of national realities and the crime situation. Among the factors that have brought about this theoretical consensus is a very important one： statistical data on those counlries that have abolished capital punishment, together with the assumption these figures promote： the fiction that ＂abolition of the death penalty is a world trend.＂ Looking objectively at the number of countries that have abolished the death penalty, reflecting upon the unscientific nature of the statistics that scholars have swallowed whole, and exploring the current international situation are all valuable activities that may significantly assist our thinking on this issue in the context of Chinese realities and help us avoid the pitfalls and blandishments of figures in academic research. China＇s stage of historical development and overall situation mean that this is not the time for the immediate abolition of the death penalty.展开更多
基金Project(51074027)supported by the National Natural Science Foundation of China
文摘According to the recently developed single-trough floating machine with the world's largest volume(inflatable mechanical agitation flotation machine with volume of 320 m3) in China, the gas-fluid two-phase flow in flotation cell was simulated using computational fluid dynamics method. It is shown that hexahedral mesh scheme is more suitable for the complex structure of the flotation cell than tetrahedral mesh scheme, and a mesh quality ranging from 0.7 to 1.0 is obtained. Comparative studies of the standard k-ε, k-ω and realizable k-ε turbulence models were carried out. It is indicated that the standard k-ε turbulence model could give a result relatively close to the practice and the liquid phase flow field is well characterized. In addition, two obvious recirculation zones are formed in the mixing zones, and the pressure on the rotor and stator is well characterized. Furthermore, the simulation results using improved standard k-ε turbulence model show that surface tension coefficient of 0.072, drag model of Grace and coefficient of 4, and lift coefficient of 0.001 can be achieved. The research results suggest that gas-fluid two-phase flow in large flotation cell can be well simulated using computational fluid dynamics method.
文摘In response to horror stories throughout the country concerning childhood deaths from sniffing model airplane glue, organizations around Louisiana would begin lobbying for legislation to criminalize the practice in 1966. State lawmakers spent much of that summer crafting an anti-glue-sniffing measure for the state. The debates that resulted from the attempt, however, never really focused on the sustainability or practical use of such a law, but instead on the kind of law it would ultimately be -- whether, for example, retailers would be liable for selling glue to minors, even though model airplanes and other kits and toys required such items. Or whether the ingredients in model airplane glue could be classed as schedule one narcotics. Such questions ultimately framed a debate about the fundamental nature of the offense being committed. Ultimately, （unlike other Deep South states） Louisiana decided that sniffing glue was not a drug crime. Instead, it was a problem that affected ＂the health and morals of minors＂.
文摘Because of the success of the discrete vortex method for the simulation of large-scale vortex structure, many researchers extend this method to two-phase flow simulations, especially, to the simulation of particle dispersion in mixing layer, which is characterized by large-scale vortex structure. But the previous work is limited to one-way coupling, which neglects the effect of particles on fluid flow. In this paper, a discrete vortex method involving two-way coupling for two-phase flows is first proposed and then used in numerical simulation of two-dimensional gas-particle mixing layers. The numerical results show that the introduction of particles into the mixing layer has significant effects on the creation, development and merging process of large-scale vortex structures. It makes the mean size of large-scale vortex structure larger and the distance needed for development of large-scale vortex structure shorter.
文摘The idea of abolishing the death penalty is increasingly accepted as a goal by scholars in the field of criminal law, who have put aside all consideration of national realities and the crime situation. Among the factors that have brought about this theoretical consensus is a very important one： statistical data on those counlries that have abolished capital punishment, together with the assumption these figures promote： the fiction that ＂abolition of the death penalty is a world trend.＂ Looking objectively at the number of countries that have abolished the death penalty, reflecting upon the unscientific nature of the statistics that scholars have swallowed whole, and exploring the current international situation are all valuable activities that may significantly assist our thinking on this issue in the context of Chinese realities and help us avoid the pitfalls and blandishments of figures in academic research. China＇s stage of historical development and overall situation mean that this is not the time for the immediate abolition of the death penalty.
