American poet, Walt Whitman and Harold Hart Crane both write poems about the place connecting Brooklyn and Manhattan, in Crossing Brooklyn Ferry and To Brooklyn Bridge respectively. By comparing the similarities of th...American poet, Walt Whitman and Harold Hart Crane both write poems about the place connecting Brooklyn and Manhattan, in Crossing Brooklyn Ferry and To Brooklyn Bridge respectively. By comparing the similarities of these two poems, this paper analyses the two poets’ attitudes towards the development of modern society, finding that both poets not only show admiration for modern society but also doubt about the fast development. It aims to reveal the influence of fast development of modern society on people’s mentality.展开更多
In the continuous development of the modern highway and bridge engineering industry,the reasonable selection of mega highway bridges and their design is crucial.Based on this,this paper takes the actual bridge project...In the continuous development of the modern highway and bridge engineering industry,the reasonable selection of mega highway bridges and their design is crucial.Based on this,this paper takes the actual bridge project as an example,and analyses the overall selection design of such highway bridges,including the basic overview of the project,the basic selection principle of mega highway bridge project structure and its design strategy,etc.,to provide scientific reference for its selection design.展开更多
In order to describe an investigation of the flow around high-speed train on a bridge under cross winds using detached-eddy simulation(DES), a 1/8th scale model of a three-car high-speed train and a typical bridge mod...In order to describe an investigation of the flow around high-speed train on a bridge under cross winds using detached-eddy simulation(DES), a 1/8th scale model of a three-car high-speed train and a typical bridge model are employed, Numerical wind tunnel technology based on computational fluid dynamics(CFD) is used, and the CFD models are set as stationary models. The Reynolds number of the flow, based on the inflow velocity and the height of the vehicle, is 1.9×10~6. The computations are conducted under three cases, train on the windward track on the bridge(WWC), train on the leeward track on the bridge(LWC) and train on the flat ground(FGC). Commercial software FLUENT is used and the mesh sensitivity research is carried out by three different grids: coarse, medium and fine. Results show that compared with FGC case, the side force coefficients of the head cars for the WWC and LWC cases increases by 14% and 29%, respectively; the coefficients of middle cars for the WWC and LWC increase by 32% and 10%, respectively; and that of the tail car increases by 45% for the WWC whereas decreases by 2% for the LWC case. The most notable thing is that the side force and the rolling moment of the head car are greater for the LWC, while the side force and the rolling moment of the middle car and the tail car are greater for the WWC. Comparing the velocity profiles at different locations, the flow is significantly influenced by the bridge-train system when the air is close to it. For the three cases(WWC, LWC and FGC), the pressure on the windward side of train is mostly positive while that of the leeward side is negative. The discrepancy of train's aerodynamic force is due to the different surface area of positive pressure and negative pressure zone. Many vortices are born on the leeward edge of the roofs. Theses vortices develop downstream, detach and dissipate into the wake region. The eddies develop irregularly, leading to a noticeably turbulent flow at leeward side of train.展开更多
In this paper, the climbing obstacle capability of the previous special cable inspection robot （ Model Number： XS1T-1） is analyzed. Static equations are established to analyze the relationships between the external...In this paper, the climbing obstacle capability of the previous special cable inspection robot （ Model Number： XS1T-1） is analyzed. Static equations are established to analyze the relationships between the external forces and the maximum height of an obstacle. Parameters affecting the obstacle crossing ability are obtained. According to the analysis results, an innovated small volume, simple structure and light weight climbing mechanism is proposed （Model Number： XS1T-2）. A simplified kinematics model of the mechanism is established. With two powered wheels, the obstacle crossing ability of the XSIT-2 is improved apparently. For the robot moving without deflection, the relationships of two powered input torques are deduced. The comparison of the simulation results clearly shows that the climbing ability of XS1T-2 is obviously improved, and it can meet the demands of inspection.展开更多
To determine the optimal length of the cross-bay bridge at the Tieshan Port and the impact of the bridge on the hydrological environment, a 2-D numerical model is adopted to calculate the variation of tidal level, tid...To determine the optimal length of the cross-bay bridge at the Tieshan Port and the impact of the bridge on the hydrological environment, a 2-D numerical model is adopted to calculate the variation of tidal level, tidal current field and tidal discharge caused by different lengths of the bridge.展开更多
文摘American poet, Walt Whitman and Harold Hart Crane both write poems about the place connecting Brooklyn and Manhattan, in Crossing Brooklyn Ferry and To Brooklyn Bridge respectively. By comparing the similarities of these two poems, this paper analyses the two poets’ attitudes towards the development of modern society, finding that both poets not only show admiration for modern society but also doubt about the fast development. It aims to reveal the influence of fast development of modern society on people’s mentality.
文摘In the continuous development of the modern highway and bridge engineering industry,the reasonable selection of mega highway bridges and their design is crucial.Based on this,this paper takes the actual bridge project as an example,and analyses the overall selection design of such highway bridges,including the basic overview of the project,the basic selection principle of mega highway bridge project structure and its design strategy,etc.,to provide scientific reference for its selection design.
基金Project(U1534210)supported by the National Natural Science Foundation of ChinaProject(14JJ1003)supported by the Natural Science Foundation of Hunan Province,China+2 种基金Project(2015CX003)supported by the Project of Innovation-driven Plan in Central South University,ChinaProject(14JC1003)supported by the Natural Science Foundation of Hunan Province,ChinaProject(2015T002-A)supported by the Technological Research and Development program of China Railways Cooperation
文摘In order to describe an investigation of the flow around high-speed train on a bridge under cross winds using detached-eddy simulation(DES), a 1/8th scale model of a three-car high-speed train and a typical bridge model are employed, Numerical wind tunnel technology based on computational fluid dynamics(CFD) is used, and the CFD models are set as stationary models. The Reynolds number of the flow, based on the inflow velocity and the height of the vehicle, is 1.9×10~6. The computations are conducted under three cases, train on the windward track on the bridge(WWC), train on the leeward track on the bridge(LWC) and train on the flat ground(FGC). Commercial software FLUENT is used and the mesh sensitivity research is carried out by three different grids: coarse, medium and fine. Results show that compared with FGC case, the side force coefficients of the head cars for the WWC and LWC cases increases by 14% and 29%, respectively; the coefficients of middle cars for the WWC and LWC increase by 32% and 10%, respectively; and that of the tail car increases by 45% for the WWC whereas decreases by 2% for the LWC case. The most notable thing is that the side force and the rolling moment of the head car are greater for the LWC, while the side force and the rolling moment of the middle car and the tail car are greater for the WWC. Comparing the velocity profiles at different locations, the flow is significantly influenced by the bridge-train system when the air is close to it. For the three cases(WWC, LWC and FGC), the pressure on the windward side of train is mostly positive while that of the leeward side is negative. The discrepancy of train's aerodynamic force is due to the different surface area of positive pressure and negative pressure zone. Many vortices are born on the leeward edge of the roofs. Theses vortices develop downstream, detach and dissipate into the wake region. The eddies develop irregularly, leading to a noticeably turbulent flow at leeward side of train.
基金Supported by the National High Technology Research and Development Programene of China （No. 2006AA04Z234） and China Postdoctoral Science Foundation （No. 2.009（061051 ）.
文摘In this paper, the climbing obstacle capability of the previous special cable inspection robot （ Model Number： XS1T-1） is analyzed. Static equations are established to analyze the relationships between the external forces and the maximum height of an obstacle. Parameters affecting the obstacle crossing ability are obtained. According to the analysis results, an innovated small volume, simple structure and light weight climbing mechanism is proposed （Model Number： XS1T-2）. A simplified kinematics model of the mechanism is established. With two powered wheels, the obstacle crossing ability of the XSIT-2 is improved apparently. For the robot moving without deflection, the relationships of two powered input torques are deduced. The comparison of the simulation results clearly shows that the climbing ability of XS1T-2 is obviously improved, and it can meet the demands of inspection.
文摘To determine the optimal length of the cross-bay bridge at the Tieshan Port and the impact of the bridge on the hydrological environment, a 2-D numerical model is adopted to calculate the variation of tidal level, tidal current field and tidal discharge caused by different lengths of the bridge.
