The behavior of single bubble rising in quiescent shear-thinning tlmds was lnvestlgateO numerically by level set metnoa. number of bubbles in a large range of Reynolds number and Eotvos number were investigated includ...The behavior of single bubble rising in quiescent shear-thinning tlmds was lnvestlgateO numerically by level set metnoa. number of bubbles in a large range of Reynolds number and Eotvos number were investigated including spherical, oblate and spherical. The bubble shape and drag coefficient were compared with experimental results. It is observed that the simulated results show good conformity to experimental results over a wide range of Reynolds number. In addition, the detailed flow field based on the reference coordinate system moving with the bubble is obtained, and the relationship among flow field, bubble shape and velocity is discussed.展开更多
In this study,the effects of surfactants on the hydrodynamic characteristics of bubbles in shear-thinning fluids at low Reynolds number(Re<50)are investigated.The bubble terminal velocity and drag coefficient of bu...In this study,the effects of surfactants on the hydrodynamic characteristics of bubbles in shear-thinning fluids at low Reynolds number(Re<50)are investigated.The bubble terminal velocity and drag coefficient of bubble in clean and contaminated carboxymethylcellulose(CMC)solutions are obtained using a high-speed camera for examining differences.The results show that the existence of surfactant could reduce the terminal velocity of bubble at small volume(0.25wt%CMC:<100 mm3;0.50wt%CMC:<110 mm3),attributed to stiffening the bubble interface.However,this negative effect decreases and finally disappears with increasing bubble volume.The drag coefficient curves of the bubble in contaminated CMC solution exhibit behavior similar to that exhibited by a solid sphere at Re<10,indicating that internal circulation flow is absent at the bubble interface as compared to that in clean CMC solution.However,for 10<Re<40,a transition of drag curve from 24/Re to 16/Re in contaminated CMC solution is observed,which is easy at low SDS concentrations and high CMC concentrations.展开更多
As one of the most distinct tectonic blocks on the Earth’s surface, Tibetan Plateau draw great attention of the geoscientists from the world. Many authors have proposed various kinds of the mechanism to try to clarif...As one of the most distinct tectonic blocks on the Earth’s surface, Tibetan Plateau draw great attention of the geoscientists from the world. Many authors have proposed various kinds of the mechanism to try to clarify the evolution of the plateau. While many studies are often restricted to crustal units, the important role of the mantle part of the lithosphere (mantle lithosphere) during and after the collision process has not been appreciated widely. The purpose of the paper is to investigate the dynamic process of the thinning (delamination and convective removal) of the thickened lithosphere and its influence upon the uplift of the plateau.1\ Thickened lithosphere root\;Parsons and McKenzie (1978) proposed that the continental lithosphere could be thought of as consisting of two distinct parts: the mechanical and thermal boundary layers. The lower, and hotter, part is the thermal boundary layer. Its viscosity is sufficiently low that the force of gravity acting on density contrasts between the thermal boundary layer and the underlying mantle lead to the episodic sinking of the thermal boundary layer and its replacement by hot asthenosphere. When continental crust shortens and thickens, the mantle directly beneath it must also be displaced downward. In other words, mountain building process shortens horizontally and thickens vertically the mechanical boundary layer, and presumably the thermal boundary layer. And the process stretches the isotherms vertically, thus reducing the geothermal gradient. Houseman’s numerical experiments (1981) show that thickening of the thermal boundary layer enhances the density contrasts between it and the underlying asthenosphere, and so leads to its removal and replacement with hot asthenosphere. This phenomenon is called the instability of the thickened lithosphere.展开更多
The tree crown shape and the tree crown analytical characteristics of Larix ol-gensis in a plantation were studied.It was found that the photosynthetic capability of the tree crown declined gradually from the top part...The tree crown shape and the tree crown analytical characteristics of Larix ol-gensis in a plantation were studied.It was found that the photosynthetic capability of the tree crown declined gradually from the top parts of the crown to the lower parts. The crown could be obviously divided into two parts, the efficient crown and the inefficient crown. Tree growth was influenced by the structure of the efficient crown. The size and the leaf biomass of the efficient crown could be described by its radius. The height from ground to the bottom of the efficient crown of trees in the same stand was nearly the same. The crown of a tree with high potential volume growth efficiency was exposed. Based on the study of the crown structure, the conditions that should be satisfied for proper thinning of Larix olgensis plantation were suggested.展开更多
Four different fruit thinning severities were tested.The thinning treatments were carried out in October before the occurrence of physiological fruit drop.Different parameters were measured(both qualitative and quanti...Four different fruit thinning severities were tested.The thinning treatments were carried out in October before the occurrence of physiological fruit drop.Different parameters were measured(both qualitative and quantitative)and the results compared among treatments as well as to that of the control.The results showed that where fruit on‘Sensation’mango pani-cles were thinned to two fruit per panicle,a significant difference was obtained for most of the quantitative parameters.The fruits of the treatment where one fruit per panicle was retained and50%panicles removed,produced the best results for most of the qualitative parameters.展开更多
Acidic deposition,which is mainly caused by atmospheric pollution,is one of the global environmental problems.Thinning is an effective management to improve the tree productivity,reduce the wildfire risk and maintain ...Acidic deposition,which is mainly caused by atmospheric pollution,is one of the global environmental problems.Thinning is an effective management to improve the tree productivity,reduce the wildfire risk and maintain a healthy forest.Since thinning may reduce the effect of acidic deposition,the effect of thinning on acidic deposition was estimated.The biomass,soil properties,pH value of runoff and groundwater in both unthinned and thinned Chinese fir plantations were measured and compared over a 5-year period(2-6 years after thinning).The results indicated that acidic deposition in the Huitong State Ecosystem Research Station was serious,and it got worse with time.Forest thinning resulted in a huge change in biomass and soil properties.During the 5-year monitoring period,biomasses of understory and litter,plant species richness,coverage of undergrowth plant layer were significantly higher in thinned site than in unthinned site.Moreover,higher soil fertility as well as lower amounts of runoff and groundwater were found in thinned site.It was suggested that thinning could improve the structure of forest,leading to restoring the effluent(runoff and groundwater) pH to the normal value.展开更多
基金Project(21406141)supported by the National Natural Science Foundation of ChinaProject(20141078)supported by the Scientific Research Starting Foundation for Doctors of Liaoning Province,China+1 种基金Project(L2014060)supported by the Foundation of Department of Education of Liaoning Province,ChinaProject(157B21)supported by the Scientific Research Starting Foundation for Doctors of Shenyang Aerospace University,China
文摘The behavior of single bubble rising in quiescent shear-thinning tlmds was lnvestlgateO numerically by level set metnoa. number of bubbles in a large range of Reynolds number and Eotvos number were investigated including spherical, oblate and spherical. The bubble shape and drag coefficient were compared with experimental results. It is observed that the simulated results show good conformity to experimental results over a wide range of Reynolds number. In addition, the detailed flow field based on the reference coordinate system moving with the bubble is obtained, and the relationship among flow field, bubble shape and velocity is discussed.
基金Project(21406141)supported by the National Natural Science Foundation of ChinaProject(20141078)supported by the National Basic Research Program,ChinaProject(L201733)supported by the Research Foundation of Education Bureau of Liaoning Province,China
文摘In this study,the effects of surfactants on the hydrodynamic characteristics of bubbles in shear-thinning fluids at low Reynolds number(Re<50)are investigated.The bubble terminal velocity and drag coefficient of bubble in clean and contaminated carboxymethylcellulose(CMC)solutions are obtained using a high-speed camera for examining differences.The results show that the existence of surfactant could reduce the terminal velocity of bubble at small volume(0.25wt%CMC:<100 mm3;0.50wt%CMC:<110 mm3),attributed to stiffening the bubble interface.However,this negative effect decreases and finally disappears with increasing bubble volume.The drag coefficient curves of the bubble in contaminated CMC solution exhibit behavior similar to that exhibited by a solid sphere at Re<10,indicating that internal circulation flow is absent at the bubble interface as compared to that in clean CMC solution.However,for 10<Re<40,a transition of drag curve from 24/Re to 16/Re in contaminated CMC solution is observed,which is easy at low SDS concentrations and high CMC concentrations.
文摘As one of the most distinct tectonic blocks on the Earth’s surface, Tibetan Plateau draw great attention of the geoscientists from the world. Many authors have proposed various kinds of the mechanism to try to clarify the evolution of the plateau. While many studies are often restricted to crustal units, the important role of the mantle part of the lithosphere (mantle lithosphere) during and after the collision process has not been appreciated widely. The purpose of the paper is to investigate the dynamic process of the thinning (delamination and convective removal) of the thickened lithosphere and its influence upon the uplift of the plateau.1\ Thickened lithosphere root\;Parsons and McKenzie (1978) proposed that the continental lithosphere could be thought of as consisting of two distinct parts: the mechanical and thermal boundary layers. The lower, and hotter, part is the thermal boundary layer. Its viscosity is sufficiently low that the force of gravity acting on density contrasts between the thermal boundary layer and the underlying mantle lead to the episodic sinking of the thermal boundary layer and its replacement by hot asthenosphere. When continental crust shortens and thickens, the mantle directly beneath it must also be displaced downward. In other words, mountain building process shortens horizontally and thickens vertically the mechanical boundary layer, and presumably the thermal boundary layer. And the process stretches the isotherms vertically, thus reducing the geothermal gradient. Houseman’s numerical experiments (1981) show that thickening of the thermal boundary layer enhances the density contrasts between it and the underlying asthenosphere, and so leads to its removal and replacement with hot asthenosphere. This phenomenon is called the instability of the thickened lithosphere.
文摘The tree crown shape and the tree crown analytical characteristics of Larix ol-gensis in a plantation were studied.It was found that the photosynthetic capability of the tree crown declined gradually from the top parts of the crown to the lower parts. The crown could be obviously divided into two parts, the efficient crown and the inefficient crown. Tree growth was influenced by the structure of the efficient crown. The size and the leaf biomass of the efficient crown could be described by its radius. The height from ground to the bottom of the efficient crown of trees in the same stand was nearly the same. The crown of a tree with high potential volume growth efficiency was exposed. Based on the study of the crown structure, the conditions that should be satisfied for proper thinning of Larix olgensis plantation were suggested.
文摘Four different fruit thinning severities were tested.The thinning treatments were carried out in October before the occurrence of physiological fruit drop.Different parameters were measured(both qualitative and quantitative)and the results compared among treatments as well as to that of the control.The results showed that where fruit on‘Sensation’mango pani-cles were thinned to two fruit per panicle,a significant difference was obtained for most of the quantitative parameters.The fruits of the treatment where one fruit per panicle was retained and50%panicles removed,produced the best results for most of the qualitative parameters.
基金Project(41271332)supported by the National Natural Science Foundation of ChinaProject(11JJ2031)supported by the Natural Science Foundation of Hunan Province,China
文摘Acidic deposition,which is mainly caused by atmospheric pollution,is one of the global environmental problems.Thinning is an effective management to improve the tree productivity,reduce the wildfire risk and maintain a healthy forest.Since thinning may reduce the effect of acidic deposition,the effect of thinning on acidic deposition was estimated.The biomass,soil properties,pH value of runoff and groundwater in both unthinned and thinned Chinese fir plantations were measured and compared over a 5-year period(2-6 years after thinning).The results indicated that acidic deposition in the Huitong State Ecosystem Research Station was serious,and it got worse with time.Forest thinning resulted in a huge change in biomass and soil properties.During the 5-year monitoring period,biomasses of understory and litter,plant species richness,coverage of undergrowth plant layer were significantly higher in thinned site than in unthinned site.Moreover,higher soil fertility as well as lower amounts of runoff and groundwater were found in thinned site.It was suggested that thinning could improve the structure of forest,leading to restoring the effluent(runoff and groundwater) pH to the normal value.
