北斗三号卫星导航信号接收机端伪距偏差建模与验证

接收机端伪距偏差是指非理想的卫星导航信号在接收机前端带宽和相关器间隔不同时产生的伪距测量系统性偏差.研究表明,北斗二号、GPS和Galileo系统均存在与接收机类型相关的伪距偏差,影响基于混合类型接收机站网的精密数据处理.本文基于iGMAS网和MGEX网观测数据,采用MW组合、伪距残差和伪距无几何距离无电离层组合3种方...     

有机岩石学在油气勘探中应用的现状和发展

本文评述了有机岩石学在研究有机成熟度、有机质类型、生烃组分和成烃作用、烃类排出运移和聚集等方面的现状和发展方向。有机成熟度评价中镜质体反射率抑制、固体沥青反射率所反映的热成熟度等问题已基本解决，难点在于下古生界高过成熟烃源岩成熟度评价。沉积有机质显微组分类已基本统一。尚未有明确认识的关键问题是无定形有机质和矿物沥青基质特征和分类，这影响到有机质类型有机岩石学评价准确性。我国石油部门一直采用透射光干酪根显微组分定量评价有机质类型，建立反光下全岩和干酪根光片显微组分鉴定和类型评价标准显得十分迫切。烃源岩生烃组分和成烃作用有机岩石学剖析为沉积盆地有机质演化和烃类形成提供了最直观和准确的认识。对烃类流体包裹体和固体沥青显微特征的分析为油气藏形成演化史提供了重要信息。     

A review on evapotranspiration data assimilation based on hydrological models

Accurate estimation of evapotranspiration (ET), especially at the regional scale, is an extensively investigated topic in the field of water science. The ability to obtain a continuous time series of highly precise ET values is necessary for improving our knowledge of fundamental hydrological processes and for addressing various problems regarding the use of water. This objective can be achieved by means of ET data assimilation based on hydrological modeling. In this paper, a comprehensive review of ET data assimilation based on hydrological modeling is provided. The difficulties and bottlenecks of using ET, being a non-state variable, to construct data assimilation relationships are elaborated upon, with a discussion and analysis of the feasibility of assimilating ET into various hydrological models. Based on this, a new easy-to-operate ET assimilation scheme that includes a water circulation physical mechanism is proposed. The scheme was developed with an improved data assimilation system that uses a distributed time-variant gain model (DTVGM), and the ET-soil humidity nonlinear time response relationship of this model. Moreover, the ET mechanism in the DTVGM was improved to perfect the ET data assimilation system. The new scheme may provide the best spatial and temporal characteristics for hydrological states, and may be referenced for accurate estimation of regional evapotranspiration.