Landslides not only cause property losses,but also kill and injure large numbers of people every year in the mountainous areas. These losses and casualties may be avoided to some extent by early warning systems for la...Landslides not only cause property losses,but also kill and injure large numbers of people every year in the mountainous areas. These losses and casualties may be avoided to some extent by early warning systems for landslides. In this paper, a realtime monitoring network and a computer-aided automatic early warning system(EWS) are presented with details of their design and an example of application in the Longjingwan landslide, Kaiyang County, Guizhou Province. Then, according to principle simple method of landslide prediction, the setting of alarm levels and the design of appropriate counter-measures are presented. A four-level early warning system(Zero, Outlook, Attention and Warning) has been adopted, and the velocity threshold was selected as the main warning threshold for the landslide occurrence, but expert judgment is included in the EWS to avoid false alarms. A case study shows the applicability and reliability for landslide risk management, and recommendations are presented for other similar projects.展开更多
This paper has two purposes. One is to evaluate the ability of an atmospheric general circulation model (IAP9L-AGCM) to predict summer rainfall over China one season in advance. The other is to propose a new approach ...This paper has two purposes. One is to evaluate the ability of an atmospheric general circulation model (IAP9L-AGCM) to predict summer rainfall over China one season in advance. The other is to propose a new approach to improve the predictions made by the model. First, a set of hindcast experiments for summer climate over China during 1982-2010 are performed from the perspective of real-time prediction with the IAP9L-AGCM model and the IAP ENSO prediction system. Then a new approach that effectively combines the hind-cast with its correction is proposed to further improve the model's predictive ability. A systematic evaluation reveals that the model's real-time predictions for 41 stations across China show significant improvement using this new approach, especially in the lower reaches between the Yellow River and Yangtze River valleys.展开更多
When voyaging,ships are subject to inevitable hull deformations caused by the changes in the environmental temperature and external stress.These are a crucial source of errors when measuring data using a spacecraft tr...When voyaging,ships are subject to inevitable hull deformations caused by the changes in the environmental temperature and external stress.These are a crucial source of errors when measuring data using a spacecraft tracking,telemetry,and control(TT&C) ship.A prototype system based on photogrammetry was developed for the real-time measurement of a spacecraft TT&C ship's hull deformation.This system has high accuracy,a simple structure,and convenient maintenance,and requires few changes to the ship's structures.To improve its performance,an estimation approach is proposed for hull deformation angles.With the proposed approach,the central positions of cross spots in successive frames can be predicted based on the prediction of the camera's attitude,and their extract locations can be found by defining a series of small windows around each predictive location.Then,the optimal estimate of the camera's attitude is updated by the designed extended Kalman filter using the extracted cross spots and their corresponding local coordinates,with which the hull deformation angles can be found.To verify the proposed measurement approach,its performance was tested during the normal sailing,floating,and rocking on the sea of a spacecraft TT&C ship.The experimental testing results demonstrated that the proposed approach performs well in terms of accuracy and robustness.It can satisfy the hull deformation measurement requirement for a spacecraft TT&C ship in real time.展开更多
基金financially supported by the State Key Laboratory of Geo-hazard Prevention and Geo-environment Protection (Chengdu University of Technology) (Grant No. SKLGP2013Z007)the National Natural Science Foundation of China (Grant No. 41302242)
文摘Landslides not only cause property losses,but also kill and injure large numbers of people every year in the mountainous areas. These losses and casualties may be avoided to some extent by early warning systems for landslides. In this paper, a realtime monitoring network and a computer-aided automatic early warning system(EWS) are presented with details of their design and an example of application in the Longjingwan landslide, Kaiyang County, Guizhou Province. Then, according to principle simple method of landslide prediction, the setting of alarm levels and the design of appropriate counter-measures are presented. A four-level early warning system(Zero, Outlook, Attention and Warning) has been adopted, and the velocity threshold was selected as the main warning threshold for the landslide occurrence, but expert judgment is included in the EWS to avoid false alarms. A case study shows the applicability and reliability for landslide risk management, and recommendations are presented for other similar projects.
基金jointly supported by the Special Fund for Meteorological Scientific Research in the Public Interest of China Meteorological Administration(GYHY201006022)the National Key Technologies R&D Program of China(2009BAC51B02)the National Basic Research Program of China(2010CB950304)
文摘This paper has two purposes. One is to evaluate the ability of an atmospheric general circulation model (IAP9L-AGCM) to predict summer rainfall over China one season in advance. The other is to propose a new approach to improve the predictions made by the model. First, a set of hindcast experiments for summer climate over China during 1982-2010 are performed from the perspective of real-time prediction with the IAP9L-AGCM model and the IAP ENSO prediction system. Then a new approach that effectively combines the hind-cast with its correction is proposed to further improve the model's predictive ability. A systematic evaluation reveals that the model's real-time predictions for 41 stations across China show significant improvement using this new approach, especially in the lower reaches between the Yellow River and Yangtze River valleys.
基金supported by the National Natural Science Foundation of China(Grant No.11272347)
文摘When voyaging,ships are subject to inevitable hull deformations caused by the changes in the environmental temperature and external stress.These are a crucial source of errors when measuring data using a spacecraft tracking,telemetry,and control(TT&C) ship.A prototype system based on photogrammetry was developed for the real-time measurement of a spacecraft TT&C ship's hull deformation.This system has high accuracy,a simple structure,and convenient maintenance,and requires few changes to the ship's structures.To improve its performance,an estimation approach is proposed for hull deformation angles.With the proposed approach,the central positions of cross spots in successive frames can be predicted based on the prediction of the camera's attitude,and their extract locations can be found by defining a series of small windows around each predictive location.Then,the optimal estimate of the camera's attitude is updated by the designed extended Kalman filter using the extracted cross spots and their corresponding local coordinates,with which the hull deformation angles can be found.To verify the proposed measurement approach,its performance was tested during the normal sailing,floating,and rocking on the sea of a spacecraft TT&C ship.The experimental testing results demonstrated that the proposed approach performs well in terms of accuracy and robustness.It can satisfy the hull deformation measurement requirement for a spacecraft TT&C ship in real time.
