针对北斗卫星导航系统(BeiDou Navigation Satellite System,BDS)精密单点定位(precise point positioning,PPP)服务PPP-B2b在同一时刻可用于PPP的卫星数量有限,以及其实时钟差解算评估研究较少的问题,本文提出了一种基于BDS PPP-B2b与G...针对北斗卫星导航系统(BeiDou Navigation Satellite System,BDS)精密单点定位(precise point positioning,PPP)服务PPP-B2b在同一时刻可用于PPP的卫星数量有限,以及其实时钟差解算评估研究较少的问题,本文提出了一种基于BDS PPP-B2b与Galileo高精度服务(high accuracy service,HAS)融合的改进方案,并对其实时钟差解算性能进行了系统性评估.该方法利用两个卫星系统的PPP服务改正数进行融合,显著提升了同一时刻内可用卫星数量.相较于单一PPP-B2b服务方案,在钟差解算的精度和稳定性方面具有明显提升.同时,实验结果表明,该方法在经过一定时间的收敛后,其性能优于德国波兹坦地学研究中心(German Research Centre for Geosciences,GFZ)提供的超快速(UTL)产品.因此,本文不仅为提高PPP-B2b服务的实际应用能力提供了有效途径,也为多系统融合下的实时时间解算方法设计与性能优化提供了新的思路和实验验证.展开更多
Rainfall-induced landslides have occurred frequently in Southwestern China since the Wenchuan earthquake,resulting in massive loss of people’s life and property.Fortunately,landslide early-warning is one of the most ...Rainfall-induced landslides have occurred frequently in Southwestern China since the Wenchuan earthquake,resulting in massive loss of people’s life and property.Fortunately,landslide early-warning is one of the most important tools for landslide hazard prevention and mitigation.However,the accumulation of historical data of the landslides induced by rainfall is limited in many remote mountain areas and the stability of the slope is easily affected by human engineering activities and environmental changes,leading to difficulties to accurately realize early warning of landslide hazards by statistical methods.The proposed warning method is divided into rainfall warning component and deformation warning component because the deformation induced by rainfall has the characteristic of hysteretic nature.Rainfall,tilted angle and crack width are chosen as monitoring indexes.Rainfall grade level that contains rainfall intensity and duration information is graded according to the variation of the safety factor calculated by 3-D finite difference numerical simulation method,and then is applied using the strength reduction method and unascertained information theory to obtain the deformation grade level of several monitored points.Finally,based on the system reliability theory,we establish a comprehensive landslide warning level method that provides four early warning levels to reflect the safety factor reductions during and post rainfall events.The application of this method at a landslide site yield generally satisfactory results and provide a new method for performing multi-index and multi-level landslide early warnings.展开更多
文摘针对北斗卫星导航系统(BeiDou Navigation Satellite System,BDS)精密单点定位(precise point positioning,PPP)服务PPP-B2b在同一时刻可用于PPP的卫星数量有限,以及其实时钟差解算评估研究较少的问题,本文提出了一种基于BDS PPP-B2b与Galileo高精度服务(high accuracy service,HAS)融合的改进方案,并对其实时钟差解算性能进行了系统性评估.该方法利用两个卫星系统的PPP服务改正数进行融合,显著提升了同一时刻内可用卫星数量.相较于单一PPP-B2b服务方案,在钟差解算的精度和稳定性方面具有明显提升.同时,实验结果表明,该方法在经过一定时间的收敛后,其性能优于德国波兹坦地学研究中心(German Research Centre for Geosciences,GFZ)提供的超快速(UTL)产品.因此,本文不仅为提高PPP-B2b服务的实际应用能力提供了有效途径,也为多系统融合下的实时时间解算方法设计与性能优化提供了新的思路和实验验证.
基金sponsored by National KeyResearch and Development Program(2018YFC0809400)"Safety Guarantee Technology of Power Grid Facilities in Large Region under Extreme Conditions"and Scientific Program of State Grid Corporation of China(GCB17201800051)"Research for application of geological hazard analysis technology on strategic transmission channel of Sichuan-Tibet Plateau based on synthetic aperture radar"。
文摘Rainfall-induced landslides have occurred frequently in Southwestern China since the Wenchuan earthquake,resulting in massive loss of people’s life and property.Fortunately,landslide early-warning is one of the most important tools for landslide hazard prevention and mitigation.However,the accumulation of historical data of the landslides induced by rainfall is limited in many remote mountain areas and the stability of the slope is easily affected by human engineering activities and environmental changes,leading to difficulties to accurately realize early warning of landslide hazards by statistical methods.The proposed warning method is divided into rainfall warning component and deformation warning component because the deformation induced by rainfall has the characteristic of hysteretic nature.Rainfall,tilted angle and crack width are chosen as monitoring indexes.Rainfall grade level that contains rainfall intensity and duration information is graded according to the variation of the safety factor calculated by 3-D finite difference numerical simulation method,and then is applied using the strength reduction method and unascertained information theory to obtain the deformation grade level of several monitored points.Finally,based on the system reliability theory,we establish a comprehensive landslide warning level method that provides four early warning levels to reflect the safety factor reductions during and post rainfall events.The application of this method at a landslide site yield generally satisfactory results and provide a new method for performing multi-index and multi-level landslide early warnings.
