That flow is the common feature of substance flow and fluid flow is the viewpoint emphasized in the paper. Some notes on fluid mechanics, including the two approaches of fluid flow description, were given. The concept...That flow is the common feature of substance flow and fluid flow is the viewpoint emphasized in the paper. Some notes on fluid mechanics, including the two approaches of fluid flow description, were given. The concepts of the chain and the chain group of product life cycles, which are essential for understanding the specific features of substance flow, were advanced. Taking the specific feature of substance flow into consideration, on the analogy of the two approaches in fluid mechanics, two approaches of substance flow analysis, i.e. L method and E model, were formulated. Illustrative models of steady and unsteady substance flow were sketched by both methods, and comparison between them was made in general.展开更多
For too long,China,the sleeping giant,was left unnoticed by the rest of the sport world.The giant,however,awoke from the slumber and has risen to the top of the world of sports since the 1980s.Throughout the monumenta...For too long,China,the sleeping giant,was left unnoticed by the rest of the sport world.The giant,however,awoke from the slumber and has risen to the top of the world of sports since the 1980s.Throughout the monumental Beijing 2008 Summer Olympic Games,the world took notice at the outstanding performances of the Chinese athletes who took 51 gold medals, surpassing the superpowers USA and Russia,and made China the country winning the most gold medals.China’s strong presence at the Olympic Games,as commented by展开更多
In this study,an excellent polarization optical crystal LiNa_(5)Mo_(9)O_(30) with wide transmission range and high laser damage threshold was researched in detail.The laser damage threshold of the LiNa_(5)Mo_(9)O_(30)...In this study,an excellent polarization optical crystal LiNa_(5)Mo_(9)O_(30) with wide transmission range and high laser damage threshold was researched in detail.The laser damage threshold of the LiNa_(5)Mo_(9)O_(30) crystal was measured to be 2.64GW/cm^(2),which was the highest among polarized optical crystals.The birefringence in the range of 0.435-5μm was larger than 0.14,while the wedge angle between 31.94°and 32.12°would satisfy the application in this waveband.The extinction ratio of the fabricated prism with the wedge angel of 31.09°was larger than 15,000:1.The results show that the LiNa_(5)Mo_(9)O_(30) prism is an excellent polarization device,especially in the mid-infrared range and high-power applications.展开更多
Based on the Lagrangian change equation of vertical vorticity deduced from the equation of three-dimensional Ertel potential vorticity （PVe）, the development and movement of vortex are investigated from the view of ...Based on the Lagrangian change equation of vertical vorticity deduced from the equation of three-dimensional Ertel potential vorticity （PVe）, the development and movement of vortex are investigated from the view of potential vorticity and diabatic heating （PV Q）. It is demonstrated that the asymmetric dis-tribution in the vortex of the non-uniform diabatic heating in both vertical and horizontal can lead to the vortex＇s development and movement. The theoretical results are used to analyze the development and move-ment of a Tibetan Plateau （TP） vortex （TPV）, which appeared over the TP, then slid down and moved eastward in late July 2008, resulting in heavy rainfall in Sichuan Province and along the middle and lower reaches of the Yangtze River. The relative contributions to the vertical vorticity development of the TPV are decomposed into three parts： the diabatic heating, the change in horizontal component of PVe （defined as PV2）, and the change in static stability θz. The results show that in most cases, diabatic heating plays a leading role, followed by the change in PV2, while the change of θz usually has a negative impact in a stable atmosphere when the atmosphere becomes more stable, and has a positive contribution when the atmosphere approaches neutral stratification. The intensification of the TPV from 0600 to 1200 UTC 22 July 2008 is mainly due to the diabatic heating associated with the precipitation on the eastern side of the TPV when it uplifted on the up-slope of the northeastern edge of the Sichuan basin. The vertical gradient of diabatic heating makes positive （negative） PVe generation below （above） the maximum of diabatic heating; the positive PVe generation not only intensifies the low-level vortex but also enhances the vertical extent of the vortex as it uplifts. The change in PVe due to the horizontal gradient of diabatic heating depends on the vertical shear of horizontal wind that passes through the center of diabatic heating. The horizontal gradient of diabatic heating makes positive （negative） PVe generation on the right （left） side of the vertical shear of horizontal wind. The positive PVe generation on the right side of the vertical shear of horizontal wind not only intensifies the local vertical vorticity but also affects direction of movement of the TPV. These diagnostic results are in good agreement with the theoretic results developed from the PV-Q view.展开更多
文摘That flow is the common feature of substance flow and fluid flow is the viewpoint emphasized in the paper. Some notes on fluid mechanics, including the two approaches of fluid flow description, were given. The concepts of the chain and the chain group of product life cycles, which are essential for understanding the specific features of substance flow, were advanced. Taking the specific feature of substance flow into consideration, on the analogy of the two approaches in fluid mechanics, two approaches of substance flow analysis, i.e. L method and E model, were formulated. Illustrative models of steady and unsteady substance flow were sketched by both methods, and comparison between them was made in general.
文摘For too long,China,the sleeping giant,was left unnoticed by the rest of the sport world.The giant,however,awoke from the slumber and has risen to the top of the world of sports since the 1980s.Throughout the monumental Beijing 2008 Summer Olympic Games,the world took notice at the outstanding performances of the Chinese athletes who took 51 gold medals, surpassing the superpowers USA and Russia,and made China the country winning the most gold medals.China’s strong presence at the Olympic Games,as commented by
基金This work was supported by the National Natural Science Foundation of China(Nos.51021062,62175129,50990061,and 50802054)973 Program of China(No.2010CB630702)+1 种基金China Postdoctoral Science Foundation(No.20110491600)Program of Introducing Talents of Disciplines to Universities in China(111 Program)(No.b06017).
文摘In this study,an excellent polarization optical crystal LiNa_(5)Mo_(9)O_(30) with wide transmission range and high laser damage threshold was researched in detail.The laser damage threshold of the LiNa_(5)Mo_(9)O_(30) crystal was measured to be 2.64GW/cm^(2),which was the highest among polarized optical crystals.The birefringence in the range of 0.435-5μm was larger than 0.14,while the wedge angle between 31.94°and 32.12°would satisfy the application in this waveband.The extinction ratio of the fabricated prism with the wedge angel of 31.09°was larger than 15,000:1.The results show that the LiNa_(5)Mo_(9)O_(30) prism is an excellent polarization device,especially in the mid-infrared range and high-power applications.
基金Supported by the National Basic Research and Development(973)Program of China(2012CB417203 and 2010CB950403)National Natural Science Foundation of China(40875034 and 40925015)
文摘Based on the Lagrangian change equation of vertical vorticity deduced from the equation of three-dimensional Ertel potential vorticity （PVe）, the development and movement of vortex are investigated from the view of potential vorticity and diabatic heating （PV Q）. It is demonstrated that the asymmetric dis-tribution in the vortex of the non-uniform diabatic heating in both vertical and horizontal can lead to the vortex＇s development and movement. The theoretical results are used to analyze the development and move-ment of a Tibetan Plateau （TP） vortex （TPV）, which appeared over the TP, then slid down and moved eastward in late July 2008, resulting in heavy rainfall in Sichuan Province and along the middle and lower reaches of the Yangtze River. The relative contributions to the vertical vorticity development of the TPV are decomposed into three parts： the diabatic heating, the change in horizontal component of PVe （defined as PV2）, and the change in static stability θz. The results show that in most cases, diabatic heating plays a leading role, followed by the change in PV2, while the change of θz usually has a negative impact in a stable atmosphere when the atmosphere becomes more stable, and has a positive contribution when the atmosphere approaches neutral stratification. The intensification of the TPV from 0600 to 1200 UTC 22 July 2008 is mainly due to the diabatic heating associated with the precipitation on the eastern side of the TPV when it uplifted on the up-slope of the northeastern edge of the Sichuan basin. The vertical gradient of diabatic heating makes positive （negative） PVe generation below （above） the maximum of diabatic heating; the positive PVe generation not only intensifies the low-level vortex but also enhances the vertical extent of the vortex as it uplifts. The change in PVe due to the horizontal gradient of diabatic heating depends on the vertical shear of horizontal wind that passes through the center of diabatic heating. The horizontal gradient of diabatic heating makes positive （negative） PVe generation on the right （left） side of the vertical shear of horizontal wind. The positive PVe generation on the right side of the vertical shear of horizontal wind not only intensifies the local vertical vorticity but also affects direction of movement of the TPV. These diagnostic results are in good agreement with the theoretic results developed from the PV-Q view.
