In this study, the shallow dish cross-section roadside ditch was designed, based on highway 304 line from Yanchi to Hongjing of Ningxia Province. The hy- draulic calculation of the shallow ditch obtained the correspon...In this study, the shallow dish cross-section roadside ditch was designed, based on highway 304 line from Yanchi to Hongjing of Ningxia Province. The hy- draulic calculation of the shallow ditch obtained the corresponding water outlet dis- tance of the ditch with the width of 1.5 m or 2 m suitable for local use under dif- ferent groove longitudinal slope conditions. And the key roadside ditch construction techniques and suitable grass species were introduced.展开更多
In this work the authors present a calculation process of the blades for wind turbine with horizontal axis. It is about a blade discretized by the finite element method （FEM） in order to determine the gyroscopic eff...In this work the authors present a calculation process of the blades for wind turbine with horizontal axis. It is about a blade discretized by the finite element method （FEM） in order to determine the gyroscopic effect during its rotation at a high speed. A blade must have the maximum output and resist to aerodynamic loads distributed over its length, which are related to its geometrical characteristics and the speed of the wind. For that, the authors wrote the relations whom determine these loads according to the flow speed of the wind, then, the authors integrated them in the laws of structure mechanics to obtain the motion equations of the blade. This process was applied to a twisted blade with a length of 1.9 m, built out of pressed aluminum sheet with a profile of the type NACA; this profile gives the best aerodynamic output. This blade is an element of a three-bladed propeller for wind turbine of maximum power 5 kW. Finally, we visualized its deformations and then the authors checked its holding in service.展开更多
Marine gas hydrates accumulate primarily in coarse-grained, high-permeability layers; however, highly saturated natural gas hydrates have been discovered in the fine-grained sediments of Shenhu area, South China Sea(S...Marine gas hydrates accumulate primarily in coarse-grained, high-permeability layers; however, highly saturated natural gas hydrates have been discovered in the fine-grained sediments of Shenhu area, South China Sea(SCS). This may be explained by key factors, such as the great abundance of foraminifera shells. In this paper, by analyzing the SCS foraminifera structure and performing hydrate formation experiments in the foraminifera shells, the contribution of foraminifera to hydrate accumulation in the SCS was investigated from a microscopic point of view. Simulations of hydrate formation were carried out in both pure SCS foraminifera shells and the host sediments. Pore structures in typical foraminifera were studied by use of micro-focus X-ray computed tomography(CT) and scanning electron microscopy(SEM). Hydrate growth and occurrence characteristics in the foraminifera shells were observed in-situ. The results showed that the presence of foraminifera significantly enhanced the effective porosity of the SCS sediments. Moreover, while the hydrates grew preferentially in the chambers of the coarse-grained foraminifera by adhering to the inner walls of the foraminifera shells, no apparent hydrate accumulation was observed in the fine-grained or argillaceous matrix. These findings provide a basis for further studies on the accumulation mechanism of hydrates and physical properties of hydrate reservoir in the South China Sea.展开更多
基金Supported by the Science and Technology Project of the Communication and Transportation Construction~~
文摘In this study, the shallow dish cross-section roadside ditch was designed, based on highway 304 line from Yanchi to Hongjing of Ningxia Province. The hy- draulic calculation of the shallow ditch obtained the corresponding water outlet dis- tance of the ditch with the width of 1.5 m or 2 m suitable for local use under dif- ferent groove longitudinal slope conditions. And the key roadside ditch construction techniques and suitable grass species were introduced.
文摘In this work the authors present a calculation process of the blades for wind turbine with horizontal axis. It is about a blade discretized by the finite element method （FEM） in order to determine the gyroscopic effect during its rotation at a high speed. A blade must have the maximum output and resist to aerodynamic loads distributed over its length, which are related to its geometrical characteristics and the speed of the wind. For that, the authors wrote the relations whom determine these loads according to the flow speed of the wind, then, the authors integrated them in the laws of structure mechanics to obtain the motion equations of the blade. This process was applied to a twisted blade with a length of 1.9 m, built out of pressed aluminum sheet with a profile of the type NACA; this profile gives the best aerodynamic output. This blade is an element of a three-bladed propeller for wind turbine of maximum power 5 kW. Finally, we visualized its deformations and then the authors checked its holding in service.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41506082, 41474119, 41376078, 41306065 & 41306062)the Scientific and Technological Innovation Project Financially Supported by Qingdao National Laboratory for Marine Science and Technology (Grant No. 2015ASKJ03)
文摘Marine gas hydrates accumulate primarily in coarse-grained, high-permeability layers; however, highly saturated natural gas hydrates have been discovered in the fine-grained sediments of Shenhu area, South China Sea(SCS). This may be explained by key factors, such as the great abundance of foraminifera shells. In this paper, by analyzing the SCS foraminifera structure and performing hydrate formation experiments in the foraminifera shells, the contribution of foraminifera to hydrate accumulation in the SCS was investigated from a microscopic point of view. Simulations of hydrate formation were carried out in both pure SCS foraminifera shells and the host sediments. Pore structures in typical foraminifera were studied by use of micro-focus X-ray computed tomography(CT) and scanning electron microscopy(SEM). Hydrate growth and occurrence characteristics in the foraminifera shells were observed in-situ. The results showed that the presence of foraminifera significantly enhanced the effective porosity of the SCS sediments. Moreover, while the hydrates grew preferentially in the chambers of the coarse-grained foraminifera by adhering to the inner walls of the foraminifera shells, no apparent hydrate accumulation was observed in the fine-grained or argillaceous matrix. These findings provide a basis for further studies on the accumulation mechanism of hydrates and physical properties of hydrate reservoir in the South China Sea.
