In order to investigate the aerodynamic behavior of the Sutong bridge over Yangtze River during erection, a 1：50 sectional model of the bridge deck, a 1： 100 full aeroelastic model of the free standing pylon and a 1...In order to investigate the aerodynamic behavior of the Sutong bridge over Yangtze River during erection, a 1：50 sectional model of the bridge deck, a 1： 100 full aeroelastic model of the free standing pylon and a 1： 125 full aeroelastic model for the maxim cantilever configuration were built. The test results show that there was no serious vortex-induced vibration at the bridge deck, and that the free standing tower, the model scale and the turbulence intensity influenced static loading. The buffeting responses during the maximum cantilever configuration did not affect the safety of the bridge under construction.展开更多
An accurate and convenient method is essential for measuring the terminal velocity of seeds dispersed by wind.Systematic and random errors produced by existing methods lower the accuracy and convenience in determining...An accurate and convenient method is essential for measuring the terminal velocity of seeds dispersed by wind.Systematic and random errors produced by existing methods lower the accuracy and convenience in determining seed terminal velocity.In this study,a video camera was used to record the falling process of forty-one species of wind-borne seed with eight appendage structures and seven aerodynamic behaviors in a settling tower at a speed of 50 frames per second(fps).The videos were analyzed by Quick Time Player to determine seed acceleration height,acceleration time,and terminal velocity.The results showed that acceleration height and time,terminal velocity,and the diff erence between terminal velocity and descent velocity(DTD)increased with wing loading.Compared with dropping methods,the camera recording method eliminated the eff ect of acceleration and corrected seed terminal velocity.Based on wing loading,release heights were determined for accurate measurement of terminal velocity of diff erent seeds.This method,due to its inexpensive equipment,high accuracy,easy observation and operation,can be applied to measure the terminal velocity of wind dispersed seeds,and provides a promising method in exploring the dispersal process of seeds.展开更多
基金The National Natural Science Foundation of China(Nos.50808148 and 90815016)
文摘In order to investigate the aerodynamic behavior of the Sutong bridge over Yangtze River during erection, a 1：50 sectional model of the bridge deck, a 1： 100 full aeroelastic model of the free standing pylon and a 1： 125 full aeroelastic model for the maxim cantilever configuration were built. The test results show that there was no serious vortex-induced vibration at the bridge deck, and that the free standing tower, the model scale and the turbulence intensity influenced static loading. The buffeting responses during the maximum cantilever configuration did not affect the safety of the bridge under construction.
基金the National Natural Science Foundation of China(41571270).
文摘An accurate and convenient method is essential for measuring the terminal velocity of seeds dispersed by wind.Systematic and random errors produced by existing methods lower the accuracy and convenience in determining seed terminal velocity.In this study,a video camera was used to record the falling process of forty-one species of wind-borne seed with eight appendage structures and seven aerodynamic behaviors in a settling tower at a speed of 50 frames per second(fps).The videos were analyzed by Quick Time Player to determine seed acceleration height,acceleration time,and terminal velocity.The results showed that acceleration height and time,terminal velocity,and the diff erence between terminal velocity and descent velocity(DTD)increased with wing loading.Compared with dropping methods,the camera recording method eliminated the eff ect of acceleration and corrected seed terminal velocity.Based on wing loading,release heights were determined for accurate measurement of terminal velocity of diff erent seeds.This method,due to its inexpensive equipment,high accuracy,easy observation and operation,can be applied to measure the terminal velocity of wind dispersed seeds,and provides a promising method in exploring the dispersal process of seeds.
