It is generally thought that the influence of comparable track typhoons is approximately similar, but in fact their wind and especially their rainstorm distribution are often very different. Therefore, a contrastive a...It is generally thought that the influence of comparable track typhoons is approximately similar, but in fact their wind and especially their rainstorm distribution are often very different. Therefore, a contrastive analysis of rainstorms by tropical cyclones (TCs) Haitang (0505) and Bilis (0604), which are of a similar track, is designed to help understand the mechanism of the TC rainstorm and to improve forecasting skills. The daily rainfall of TC Haitang (0505) and Bilis (0604) is diagnosed and compared. The result indicates that these two TCs have similar precipitation distribution before landfall but different precipitation characteristics after landfall. Using NCEP/GFS analysis data, the synoptic situation is analyzed; water vapor transportation is discussed regarding the calculated water vapor flux and divergence. The results show that the heavy rainfall in the Zhejiang and Fujian Provinces associated with Haitang (0505) and Bilis (0604) before landfall results from a peripheral easterly wind, a combination of the tropical cyclone and the terrain. After landfall and moving far inland of the storm, the precipitation of Haitang is caused by water vapor convergence carried by its own circulation; it is much weaker than that in the coastal area. One of the important contributing factors to heavy rainstorms in southeast Zhejiang is a southeast jet stream, which is maintained over the southeast coast. In contrast, the South China Sea monsoon circulation transports large amounts of water vapor into Bilis – when a water-vapor transport belt south of the tropical cyclone significantly strengthens – which strengthens the transport. Then, it causes water vapor flux to converge on the south side of Bilis and diverge on the north side. Precipitation is much stronger on the south side than that on the north side. After Bilis travels far inland, the cold air guided by a north trough travels into the TC and remarkably enhances precipitation. In summary, combining vertical wind shear with water vapor transportation is a good way to predict rainstorms associated with landing tropical cyclones.展开更多
A novel dominant correlogram based particle filter was proposed for an object tracking in visual surveillance. Particle filter outperforms the Kalman filter in non-linear and non-Gaussian estimation problem. This pape...A novel dominant correlogram based particle filter was proposed for an object tracking in visual surveillance. Particle filter outperforms the Kalman filter in non-linear and non-Gaussian estimation problem. This paper proposed incorporating spatial information into visual feature, and yields a reliable likelihood description of the observation and prediction. A similarity-ratio is defined to evaluate the effectivity of different similarity measurements in weighing samples. The experimental results demonstrate the effective and robust performance compared with the histogram based tracking in traffic scenes.展开更多
Inspired by human behaviors, a robot object tracking model is proposed on the basis of visual attention mechanism, which is fit for the theory of topological perception. The model integrates the image-driven, bottom-u...Inspired by human behaviors, a robot object tracking model is proposed on the basis of visual attention mechanism, which is fit for the theory of topological perception. The model integrates the image-driven, bottom-up attention and the object-driven, top-down attention, whereas the previous attention model has mostly focused on either the bottom-up or top-down attention. By the bottom-up component, the whole scene is segmented into the ground region and the salient regions. Guided by top-down strategy which is achieved by a topological graph, the object regions are separated from the salient regions. The salient regions except the object regions are the barrier regions. In order to estimate the model, a mobile robot platform is developed, on which some experiments are implemented. The experimental results indicate that processing an image with a resolution of 752 × 480 pixels takes less than 200 ms and the object regions are unabridged. The analysis obtained by comparing the proposed model with the existing model demonstrates that the proposed model has some advantages in robot object tracking in terms of speed and efficiency.展开更多
基金Plan Project of Wenzhou Science and Technology (S20080030)Open Study Special Project of Meteorological Science and Technology of Zhejiang Province (KF2008004)+1 种基金Cultivation Fund of the Key Scientific and Technical Innovation Project, Ministry of Education of China (708051)Natural Science Foundation of China (40875068)
文摘It is generally thought that the influence of comparable track typhoons is approximately similar, but in fact their wind and especially their rainstorm distribution are often very different. Therefore, a contrastive analysis of rainstorms by tropical cyclones (TCs) Haitang (0505) and Bilis (0604), which are of a similar track, is designed to help understand the mechanism of the TC rainstorm and to improve forecasting skills. The daily rainfall of TC Haitang (0505) and Bilis (0604) is diagnosed and compared. The result indicates that these two TCs have similar precipitation distribution before landfall but different precipitation characteristics after landfall. Using NCEP/GFS analysis data, the synoptic situation is analyzed; water vapor transportation is discussed regarding the calculated water vapor flux and divergence. The results show that the heavy rainfall in the Zhejiang and Fujian Provinces associated with Haitang (0505) and Bilis (0604) before landfall results from a peripheral easterly wind, a combination of the tropical cyclone and the terrain. After landfall and moving far inland of the storm, the precipitation of Haitang is caused by water vapor convergence carried by its own circulation; it is much weaker than that in the coastal area. One of the important contributing factors to heavy rainstorms in southeast Zhejiang is a southeast jet stream, which is maintained over the southeast coast. In contrast, the South China Sea monsoon circulation transports large amounts of water vapor into Bilis – when a water-vapor transport belt south of the tropical cyclone significantly strengthens – which strengthens the transport. Then, it causes water vapor flux to converge on the south side of Bilis and diverge on the north side. Precipitation is much stronger on the south side than that on the north side. After Bilis travels far inland, the cold air guided by a north trough travels into the TC and remarkably enhances precipitation. In summary, combining vertical wind shear with water vapor transportation is a good way to predict rainstorms associated with landing tropical cyclones.
文摘A novel dominant correlogram based particle filter was proposed for an object tracking in visual surveillance. Particle filter outperforms the Kalman filter in non-linear and non-Gaussian estimation problem. This paper proposed incorporating spatial information into visual feature, and yields a reliable likelihood description of the observation and prediction. A similarity-ratio is defined to evaluate the effectivity of different similarity measurements in weighing samples. The experimental results demonstrate the effective and robust performance compared with the histogram based tracking in traffic scenes.
基金supported by National Basic Research Program of China (973 Program) (No. 2006CB300407)National Natural Science Foundation of China (No. 50775017)
文摘Inspired by human behaviors, a robot object tracking model is proposed on the basis of visual attention mechanism, which is fit for the theory of topological perception. The model integrates the image-driven, bottom-up attention and the object-driven, top-down attention, whereas the previous attention model has mostly focused on either the bottom-up or top-down attention. By the bottom-up component, the whole scene is segmented into the ground region and the salient regions. Guided by top-down strategy which is achieved by a topological graph, the object regions are separated from the salient regions. The salient regions except the object regions are the barrier regions. In order to estimate the model, a mobile robot platform is developed, on which some experiments are implemented. The experimental results indicate that processing an image with a resolution of 752 × 480 pixels takes less than 200 ms and the object regions are unabridged. The analysis obtained by comparing the proposed model with the existing model demonstrates that the proposed model has some advantages in robot object tracking in terms of speed and efficiency.
文摘为了解决基于区域的平面物体跟踪方法容易陷入局部最优的问题,提出一种基于快速顶点漂移的平面物体跟踪方法.首先,构造包含不同尺度下的图像和物体区域采样点集合的金字塔结构;其次,在不同尺度下使用快速顶点漂移方法,利用全局的相似性度量函数迭代求解最优的顶点偏移,得到跟踪结果.在平面物体跟踪数据集POT上的实验结果表明,该方法在不同场景下平均跟踪准确率可达49.65%,平均高出其他参与测试的基于区域的方法31.87个百分点,平均每帧跟踪时间为0.12 s.
