Sand cay is a special kind of islet formed by coral detritus and bioclast, which is common in Nansha Islands of China. Some sand cays play an important role in ocean strategy and economy, but surprisingly we know litt...Sand cay is a special kind of islet formed by coral detritus and bioclast, which is common in Nansha Islands of China. Some sand cays play an important role in ocean strategy and economy, but surprisingly we know little about them, especially those recently formed sand cays. In this research, we monitor migration of a new sand cay in Nanxun Jiao（Gaven Reef） using a series of Quick Bird and World View-2 satellite images between June 2006 and August 2013. We conduct a regression between migration distance and wind observational data to examine the migration patterns of the new sand cay. The migration distance is calculated based on the sand cay locations extracted based on Normalized Difference Water Index（NDWI）. The wind observational data downloaded from NOAA are reformed into four wind direction vectors. Based on the results of regression, we concluded that the migration of the new sand cay on Nanxun Jiao was significantly associated with the east, west and north wind.East wind was the main influence factor of the migration; its impact strength was almost twice as the west and north wind. The south wind has little effect on the migration of the sand cay, which is partly blocked by the artificial structure in the south.展开更多
One way to solve the problem of measurement precision caused by deformity for thermal expansion, friction and load etc is to use an inertial sensor to measure a change in the length of the rod on a parallel machine. H...One way to solve the problem of measurement precision caused by deformity for thermal expansion, friction and load etc is to use an inertial sensor to measure a change in the length of the rod on a parallel machine. However, the characteristic of dynamic measurement in the inertial sensing system and the effects of the machine＇s working environment, bias error, misalignment and wide band random noise in inertial measurement data results in the in-accuracy of system measurement. Therefore, on the basis of the measurement system a new inertial sensing system is proposed; the drifting of error is restrained with a method of inertial error correction and the system＇s position and the velocity state variables are predicted by the data fusion. After measuring the whole 300mm movement in an experiment, the analyses of the experimental result showed that the application of the new inertial sensing system can improve the positional accuracy about 61% and the movement precision more than 20%. Measurement results also showed that the application of the new inertial sensing system for dynamic measurement was a feasible method to improve the machine＇s dynamic positioning precision. And with the further improvement of the low-cost solid-stateacceleramenter technology, the application of the machine can take a higher position and make the speed dynamic accuracy possible.展开更多
基金National Sea Islands Protection and Management Programme
文摘Sand cay is a special kind of islet formed by coral detritus and bioclast, which is common in Nansha Islands of China. Some sand cays play an important role in ocean strategy and economy, but surprisingly we know little about them, especially those recently formed sand cays. In this research, we monitor migration of a new sand cay in Nanxun Jiao（Gaven Reef） using a series of Quick Bird and World View-2 satellite images between June 2006 and August 2013. We conduct a regression between migration distance and wind observational data to examine the migration patterns of the new sand cay. The migration distance is calculated based on the sand cay locations extracted based on Normalized Difference Water Index（NDWI）. The wind observational data downloaded from NOAA are reformed into four wind direction vectors. Based on the results of regression, we concluded that the migration of the new sand cay on Nanxun Jiao was significantly associated with the east, west and north wind.East wind was the main influence factor of the migration; its impact strength was almost twice as the west and north wind. The south wind has little effect on the migration of the sand cay, which is partly blocked by the artificial structure in the south.
基金supported by the Natural Sciences Foundation of China under Grant No.50772095Jiangsu Provincial Education Bureau under Grant No.JK0310066
文摘One way to solve the problem of measurement precision caused by deformity for thermal expansion, friction and load etc is to use an inertial sensor to measure a change in the length of the rod on a parallel machine. However, the characteristic of dynamic measurement in the inertial sensing system and the effects of the machine＇s working environment, bias error, misalignment and wide band random noise in inertial measurement data results in the in-accuracy of system measurement. Therefore, on the basis of the measurement system a new inertial sensing system is proposed; the drifting of error is restrained with a method of inertial error correction and the system＇s position and the velocity state variables are predicted by the data fusion. After measuring the whole 300mm movement in an experiment, the analyses of the experimental result showed that the application of the new inertial sensing system can improve the positional accuracy about 61% and the movement precision more than 20%. Measurement results also showed that the application of the new inertial sensing system for dynamic measurement was a feasible method to improve the machine＇s dynamic positioning precision. And with the further improvement of the low-cost solid-stateacceleramenter technology, the application of the machine can take a higher position and make the speed dynamic accuracy possible.
