一次局地暴雨过程的多普勒雷达特征分析

利用库尔勒多普勒天气雷达资料,对2008年5月发生在新疆巴州焉耆盆地的一次局地暴雨过程的回波特征进行分析。降水过程中,在库尔勒到焉耆盆地一带先后有两次飑线发展东移,是造成局地暴雨的中小尺度系统。径向速度所反映的在库尔勒到焉耆盆地一带低空存在明显的垂直风切变,雷达西南方向长时间维持西南气流,为暴雨提供了水汽辐合及垂直向上输送的动力条件。     

长度检定场设计及控制测量

长度检定场是电磁波测距仪量值传递的主要标准,主要用于各等级电磁波测距仪的常数测定,本文根据相关的测量规范,就建场设计及其控制测量中一些技术问题作了一些分析和探讨.     

浮基多体系统自激运动响应的时域分析方法

浮基多体系统上部机构作业时不仅存在多体系统内部各物体间的耦合作用 ,还存在浮基与流场间的耦合作用。本文将浮基在流场中引起的辐射势表示为浮基加速度与时域规范化速度势乘积的卷积形式 ,导出流体动压力及静水系泊恢复力与浮基运动的关系。使用多刚体力学的凯恩方法得到系统的动力学方程。最后给出了在时域中数值求解系统运动响应的具体步骤     

空间决策支持系统及其支撑软件的设计与应用

本文讨论了SDSS的概念和基本理论,以决策支持为目标,面向半结构化和非结构化问题,用模型驱动的SDSS,是GIS未来的发展方向。在技术上用C语言实现了SDSS支撑软件的设计,并应用于国家科技攻关课题“三川河流域区域治理与开发信息系统”,取得了良好效果;同时对SDSS开发中存在问题作了讨论。     

Anthropogenic relief changes in a long-lasting lignite mining area (‘Ville’, Germany) derived from historic maps and digital elevation models

Humans constitute one of the main geomorphological agents in modern times. As an example, post-mining regions represent a typical landscape of the Anthropocene. Strong relief modifications are particularly obvious with open pit mining. However, many existing mining areas are lacking detailed pre-mining information for the quantification of anthropogenic relief changes, which is a considerable challenge in regions with historic mining activities. Here, the Ville (Rhenish lignite district, Germany) is used to quantify surface mining induced relief changes in one of the oldest and currently largest lignite districts in Europe. Historical maps from first geodetic mapping in 1893 enabled construction of a historic digital elevation model to quantify the relief changes in comparison to elevation data from 2000 and 2015. The vertical accuracy of the historic data is remarkably high, with relief differences < 2 m in areas not affected by mining. In total, 49.2% of the investigated area (184 km²) shows a relief deficit and 14.5% has positive relief differences. Absolute changes account for more than 80 m heightening (dumpsites of overburden) and lowering of the natural relief (pits). Besides these altitudinal changes, overall steeper slopes are significant for the new topography, but levelling exists likewise. The spatial variabilities are discussed in the context of the regional geology and the mining techniques. Undoubtedly, such large-scale anthropogenic relief changes persist for a very long time and will last as a human legacy far into the future. Only the detailed reconstruction of the pre-mining relief offers the ability to clarify the dimension of humans as geomorphological agents and to understand landscape perception. Due to the fact that the impact of open pit mining has such a large vertical and horizontal extension, their consideration as part of anthropogeomorphology can significantly contribute to support future Critical Zone research in the Anthropocene.     

农用地定级专家信息系统的研发

农用地定级专家信息系统是我国现阶段土地管理实践和社会经济发展的必然要求。本文分析了开发农用地定级专家信息系统的可行性。通过VC++6.0嵌入GIS控件(MO2.0)开发了以系数修正法为例的农用地定级专家信息系统,实现了农用地的自动定级,相关数据的存贮、查询检索、统计分析,为用户提供农用地的各种数据、图件等信息产品。     

Tectonic cycles of the New England Orogen,eastern Australia: A Review

The New England Orogen (NEO), the youngest of the orogens of the Tasmanides of eastern Australia, is defined by two main cycles of compression–extension. The compression component involves thrust tectonics and advance of the arc towards the continental plate, while extension is characterised by rifting, basin formation, thermal relaxation and retreat of the arc towards the oceanic plate. A compilation of 623 records of U–Pb zircon geochronology rock ages from Geoscience Australia, the geological surveys of Queensland and New South Wales and other published research throughout the orogen, has helped to clarify its complex tectonic history. This contribution focuses on the entire NEO and is aimed at those who are unfamiliar with the details of the orogen and who could benefit from a summary of current knowledge. It aims to fill a gap in recent literature between broad-scale overviews of the orogen incorporated as part of wider research on the Tasmanides and detailed studies usually specific to either the northern or southern parts of the orogen. Within the two main cycles of compression–extension, six accepted and distinct tectonic phases are defined and reviewed. Maps of geological processes active during each phase reveal the centres of activity during each tectonic phase, and the range in U–Pb zircon ages highlights the degree of diachronicity along the length of the NEO. In addition, remnants of the early Permian offshore arc formed during extensive slab rollback, are identified by the available geochronology. Estimates of the beginning of the Hunter-Bowen phase of compression, generally thought to commence around 265?Ma are complicated by the presence of extensional-type magmatism in eastern Queensland that occurred between 270 and 260?Ma.     

西南三江碰撞造山带沉积岩容矿Pb-Zn-Ag-Cu贱金属复合成矿与深部过程

西南三江特提斯造山带中新生代沉积盆地中(沱沱河、玉树、昌都和兰坪-思茅地区)发育包括金顶超大型铅锌矿床在内的一系列以沉积岩容矿的Pb-Zn-Ag-Cu贱金属矿床,构成长达千余千米的青藏高原东缘贱金属成矿带。作为大陆碰撞环境成矿谱系的重要矿床类型,加强这些矿床的理论研究对提高和完善大陆碰撞造山成矿理论和指导找矿勘查等具有重要意义。已有研究表明这些Pb-Zn-Ag-Cu矿床的分布受盆地形成后新生代大型逆冲推覆-走滑构造控制,其容矿岩石和成矿作用特征与SEDEX和MVT矿床存在明显的差异,矿床成矿流体表现出多来源混合的特征,成矿与深部过程密切相关。尽管取得重要进展,但由于缺乏高精度年代学数据制约,成矿动力学背景及其与碰撞造山的时空联系存在较大争议。一些矿床的研究显示复合成矿迹象,但是复合成矿过程与深部驱动等问题仍不清楚。近年来我们以兰坪和昌都盆地的Pb-Zn-Ag多金属矿床和Cu多金属矿床为重点研究对象,系统开展了成矿年代学、成矿流体源-运-储系统和复合成矿机制以及深部过程对成矿制约等方面研究。结果表明,兰坪盆地西缘Cu(Mo)多金属矿床主要形成于48～58Ma,兰坪和昌都盆地Pb-Zn-Ag多金属矿床主要形成于27～33Ma。成矿流体表现出明显的多来源混合的特征,主要存在三种类型:1)变质流体与盆地卤水或大气降水复合成矿,以金满-连城Cu矿床为代表; 2)盆地卤水与大气降水复合成矿,以金顶Pb-Zn矿床为代表; 3)盆地卤水和岩浆流体复合成矿,以拉诺玛Pb-Zn-Sb矿床为代表。兰坪盆地西缘Cu矿床主要形成于新生代印度-欧亚大陆主碰撞挤压阶段,与成矿密切相关的变质流体可能来源于陆-陆碰撞俯冲引起的高压变质。Pb-Zn矿床主要形成于印度-欧亚大陆晚碰撞构造转换环境,构造挤压和造山隆起驱动盆地流体迁移,同期的岩浆活动主要为成矿提供热驱动力或成矿物质。     

科马提岩与苦橄岩的区别及对若干晚古生代“科马提岩”的质疑

以往学术界更多的关注科马提岩和苦橄岩的相似性,忽略其差异。通过全数据模式,采集数据库内全球的太古宙科马提岩、后太古宙低/高钛苦橄岩数据,对比三者之间的差异发现,科马提岩更富MgO、Cr、Ni、Cs、Pb、Co和Zn,其次为低钛苦橄岩(除Co和Zn),其余主量、微量元素的含量由高至低依次为高钛苦橄岩、低钛苦橄岩、科马提岩。依据元素间的差异(如Cr/Ga、MgO/Ga、MnO/Zr、Cr/Zr等),采用密度分布函数(Density Distribution)在Matlab软件中绘制出可有效区分3类岩石的等密度判别图,并用该图对若干晚古生代"科马提岩"的岩性重新厘定。结合岩相学和地球化学特征研究表明,晚古生代"科马提岩"中,印度东部为高钛苦橄岩,越南为化学成分与科马提岩类似的低钛苦橄岩,印度拉达克地区为低钛苦橄岩。     

Characterization of sudden and sustained base flow jump hydrologic behaviour in the humid seasonal tropics of the Panama Canal Watershed

Base flows are important for tropical regions with pronounced dry seasons, which are facing increasing water demands. Base flow generation, however, is one of the most challenging hydrological processes to characterize in the tropics. In many years during the May–December wet season in the Panama Canal Watershed (PCW), base flows in rivers abruptly increase. This increase persists until the start of the December–April dry season. Understanding this unusual base flow jump (BFJ) behaviour is critical to improve water provisioning in the seasonal tropics, especially during droughts and extended dry seasons. This study developed an integrated approach combining piecewise regression on cumulative average base flow and sensitivity analysis to calculate the timing and magnitude of BFJ. Rainfall, forest cover, mean land surface slope, catchment area, and estimated subsurface storage were tested as predictors for the occurrence and magnitude of the BFJs in seven subcatchments of the PCW. Sensitivity analysis on correlated predictors allowed ranking of predictor contributions due to isolated and cross-correlation effects. Correlations between observed BFJs and BFJs predicted by watershed and rainfall-related predictors were 0.92 and 0.65 for BFJ timing and magnitude, respectively. Forest cover was the second most significant predictor after cumulative rainfall for jump magnitude, owing to larger subsurface storage and groundwater recharge in forests than pastures. Catchments in the mountainous eastern PCW always generated larger jumps due to their higher rainfall and greater forest cover than the western PCW catchments. The cross-correlations between predictors contributed to more than 50% of the jump variances. The results demonstrate the importance of rainfall gradient and catchment characteristics in affecting the sudden and sustained BFJs, which can help inform land management decisions intended to enhance water supplies in the tropics. This study underscores the need for more research to further understand the hydrological processes involved in the BFJ phenomenon, including better BFJ models and field characterizations, to help improve tropical ecosystem services under a changing environment.