In recent years,China’s society and economy has been developing very rapidly,and various industries are showing a trend of vigorous development.The importance of control and management of project cost in highway proj...In recent years,China’s society and economy has been developing very rapidly,and various industries are showing a trend of vigorous development.The importance of control and management of project cost in highway project management is becoming more and more prominent.PPP model has been widely used in the control and management of highway project cost with its own unique advantages.The author analyzes the important advantages of the PPP model and the existing problems in the cost control and management of highway projects,and puts forward effective measures for the cost control and management of highway projects using the PPP model,in hope of helping with the smooth implementation of the work.展开更多
针对北斗三号卫星导航系统(BeiDou-3 Navigation Satellite System,BDS-3)非组合精密单点定位(uncombined precise point positioning,UPPP)解算过程中,接收机天线相位中心变化(phase center variations,PCV)对UPPP解算参数的影响进行...针对北斗三号卫星导航系统(BeiDou-3 Navigation Satellite System,BDS-3)非组合精密单点定位(uncombined precise point positioning,UPPP)解算过程中,接收机天线相位中心变化(phase center variations,PCV)对UPPP解算参数的影响进行了研究.选择武汉大学IGS数据中心最终产品,以BRUX测站为例分析了2024年年积日第90~96天共1周数据解算的坐标精度、天顶对流层延迟(zenith tropospheric delay,ZTD)精度、接收机钟差精度以及斜向电离层电子总量(slant total electron content,STEC)并进行实验对比.结果表明:毫米级PCV误差对高程方向影响较大,对水平方向影响较小;PCV对钟差结果影响较大,有无PCV误差改正,其结果相差约2 ns(约0.6 m);PCV误差对ZTD影响较大,未校正PCV误差ZTD精度为15.7 mm,进行PCV误差校正后ZTD精度为7.6 mm,精度提升两倍左右;PCV误差在UPPP收敛阶段对STEC影响较大,可达0.3 TECU(约0.047 m),收敛后对STEC影响基本可以忽略.展开更多
随着GNSS的不断发展,基于精密单点定位(precise point positioning,PPP)技术的高精度时间传递研究已成为时频领域的关键技术之一.本文以北斗三号系统解算接收机钟差为研究对象,分析了无电离层(ionospheric-free,IF)组合和非组合(uncombi...随着GNSS的不断发展,基于精密单点定位(precise point positioning,PPP)技术的高精度时间传递研究已成为时频领域的关键技术之一.本文以北斗三号系统解算接收机钟差为研究对象,分析了无电离层(ionospheric-free,IF)组合和非组合(uncombined,UC)PPP模型对时间传递的影响.首先推导了两种PPP数学模型差异,选取2024年年积日第79~81天的BRUX和USN7两个外接氢原子钟测站观测数据进行分析.结果表明:两种PPP模型解算的接收机钟差差值在0.15 ns内波动,修正的Allan方差数值接近;对BRUX-USN7时间链路对比分析,3天内时间传递结果均在0.8 ns内波动,两种模型解算钟差修正的Allan方差数值近似.综上,两种PPP模型虽然钟差数值解算的理论模型不同,但在钟差解算和时间传递方面无明显差异,非组合模型可以用来进行时间传递且在保留电离层信息方面更具有优势.展开更多
文摘In recent years,China’s society and economy has been developing very rapidly,and various industries are showing a trend of vigorous development.The importance of control and management of project cost in highway project management is becoming more and more prominent.PPP model has been widely used in the control and management of highway project cost with its own unique advantages.The author analyzes the important advantages of the PPP model and the existing problems in the cost control and management of highway projects,and puts forward effective measures for the cost control and management of highway projects using the PPP model,in hope of helping with the smooth implementation of the work.
文摘针对北斗三号卫星导航系统(BeiDou-3 Navigation Satellite System,BDS-3)非组合精密单点定位(uncombined precise point positioning,UPPP)解算过程中,接收机天线相位中心变化(phase center variations,PCV)对UPPP解算参数的影响进行了研究.选择武汉大学IGS数据中心最终产品,以BRUX测站为例分析了2024年年积日第90~96天共1周数据解算的坐标精度、天顶对流层延迟(zenith tropospheric delay,ZTD)精度、接收机钟差精度以及斜向电离层电子总量(slant total electron content,STEC)并进行实验对比.结果表明:毫米级PCV误差对高程方向影响较大,对水平方向影响较小;PCV对钟差结果影响较大,有无PCV误差改正,其结果相差约2 ns(约0.6 m);PCV误差对ZTD影响较大,未校正PCV误差ZTD精度为15.7 mm,进行PCV误差校正后ZTD精度为7.6 mm,精度提升两倍左右;PCV误差在UPPP收敛阶段对STEC影响较大,可达0.3 TECU(约0.047 m),收敛后对STEC影响基本可以忽略.
文摘随着GNSS的不断发展,基于精密单点定位(precise point positioning,PPP)技术的高精度时间传递研究已成为时频领域的关键技术之一.本文以北斗三号系统解算接收机钟差为研究对象,分析了无电离层(ionospheric-free,IF)组合和非组合(uncombined,UC)PPP模型对时间传递的影响.首先推导了两种PPP数学模型差异,选取2024年年积日第79~81天的BRUX和USN7两个外接氢原子钟测站观测数据进行分析.结果表明:两种PPP模型解算的接收机钟差差值在0.15 ns内波动,修正的Allan方差数值接近;对BRUX-USN7时间链路对比分析,3天内时间传递结果均在0.8 ns内波动,两种模型解算钟差修正的Allan方差数值近似.综上,两种PPP模型虽然钟差数值解算的理论模型不同,但在钟差解算和时间传递方面无明显差异,非组合模型可以用来进行时间传递且在保留电离层信息方面更具有优势.
