我国花岗岩研究的回顾与展望   总被引：67，自引：13，他引：54  

王德滋  周金城 《岩石学报》1999,15(2):161-169

本文中回顾了８０年代以来国内花岗岩研究的概况。阐述了造山带花岗岩的形成和演化,次火山花岗岩的特征,Ａ－型花岗岩的成因,花岗岩形成过程中的岩浆混合作用、玄武岩浆底侵作用与花岗岩形成的联系以及花岗岩的实验岩石学研究方面的问题。展望了下一世纪花岗岩研究的某些趋向。  相似文献   

Unmanned aerial systems for photogrammetry and remote sensing: A review     

《ISPRS Journal of Photogrammetry and Remote Sensing》2014

We discuss the evolution and state-of-the-art of the use of Unmanned Aerial Systems (UAS) in the field of Photogrammetry and Remote Sensing (PaRS). UAS, Remotely-Piloted Aerial Systems, Unmanned Aerial Vehicles or simply, drones are a hot topic comprising a diverse array of aspects including technology, privacy rights, safety and regulations, and even war and peace. Modern photogrammetry and remote sensing identified the potential of UAS-sourced imagery more than thirty years ago. In the last five years, these two sister disciplines have developed technology and methods that challenge the current aeronautical regulatory framework and their own traditional acquisition and processing methods. Navety and ingenuity have combined off-the-shelf, low-cost equipment with sophisticated computer vision, robotics and geomatic engineering. The results are cm-level resolution and accuracy products that can be generated even with cameras costing a few-hundred euros. In this review article, following a brief historic background and regulatory status analysis, we review the recent unmanned aircraft, sensing, navigation, orientation and general data processing developments for UAS photogrammetry and remote sensing with emphasis on the nano-micro-mini UAS segment.  相似文献   

中国地震标准体系进展综述     

晁洪太  关友义  刘敏  杨勇  徐凯  刘洋 《中国地震》2021,37(1):1-14

中国地震标准体系由国家标准、行业标准、地方标准、团体标准和企业标准构成。目前,我国正在实施的地震标准共计756项,其中,国家标准129项,行业标准299项,地方标准160项,团体标准23项,企业标准145项。从技术角度分类,这些地震标准可以划分为地震基本概念与规定类、地震监(观)测类、建设工程抗震设防类、地震应急救援与灾情调查类、地震勘探类、通用设备抗震(振)类以及地震信息服务与科普类等7个类别。本文利用文献调研方法,总结了我国地震标准体系的进展,并对未来地震标准化工作提出了一些建议。  相似文献   

大同－阳高中强震群前短临预报的回顾与展望     

曹刚 《山西地震》1995,(1)

大同－阳高中强震群是华北地区近２０年来最引人注目的地震事件。本文通过系统总结反思这一地震事件，就其震群自身的重要性以及未来华北北部地区短临预报的问题进行了研究，给出一种可能的解释。  相似文献   

热带气旋眼墙非对称结构的研究综述   总被引：2，自引：0，他引：2  

费建芳  刘磊  黄小刚  程小平 《气象学报》2013,71(5):987-995

热带气旋的眼墙非对称结构与其发展过程密切相关。在热带气旋移动过程中,非对称风场伴随着边界层内非对称摩擦而引起的辐合,影响着热带气旋眼墙内的对流分布。此外,风垂直切变作为影响热带气旋强度的重要因子,将上层暖心吹离表层环流,引起眼墙垂直运动的非对称,导致云、降水在方位角方向的非均匀分布。当存在平均涡度的径向梯度时,罗斯贝类型的波动可以存在于涡旋内核区域,影响眼墙非对称结构。海洋为热带气旋提供潜热和感热形式的能量,是热带气旋发展的重要能量来源,关于海洋如何影响热带气旋眼墙非对称结构的相关研究较少。文中着重回顾了热带气旋与海洋相互作用的研究成果,并提出海洋影响热带气旋眼墙非对称结构的机制。海洋对热带气旋最显著的响应特征是冷尾效应,该效应通过降低海表温度,减少海洋向大气输送的潜热和感热,从而影响热带气旋眼墙非对称结构。此外,海浪改变海表粗糙度,通过边界层影响移动热带气旋的眼墙结构。  相似文献   

2005年度地理学基金项目评审及成果分析     

宋长青  冷疏影  张立新  刘黎明  黄永梅  高红山 《地球科学进展》2005,20(12):1337-1342

介绍了国家自然科学基金2005年度地理学项目受理、评审与资助的总体情况;分析了2005年在研的地理学基金项目执行情况,着重剖析了2002年批准项目的成果产出数量与水平;阐述了2004年底结题的地理学基金项目取得的突出进展。  相似文献   

滑坡监测预警国内外研究现状及评述   总被引：11，自引：0，他引：11  

唐亚明  张茂省  薛强  毕俊擘 《地质论评》2012,58(3):533-541

本文从降雨临界值研究、监测技术方法、区域性监测预警系统三个方面对滑坡监测预警的国内外研究现状进行了回顾和总结。首先归纳了国内外28个国家或地区的滑坡降雨临界值及统计方法,三个模型——日降雨量模型、前期降雨量模型和前期土体含水状态模型,基本概括了当前降雨诱发滑坡临界值的确定方法;但由于降雨入渗触发滑坡的复杂性,不同机理的滑坡"需要"不同的降雨临界值;目前的研究趋势是对雨量雨强雨时—土体渗流场动态变化—土体抗剪强度变化的耦合关系进行研究。按监测对象的不同,滑坡监测可分为四大类,即位移监测、物理场监测、地下水监测和外部诱发因素监测;按监测手段的不同,则可分为人工监测、简易监测、专业监测三大类;目前国内外在滑坡监测技术、方法、手段上并无太大差距,专业仪器已成为常规设备,只是由于价格因素得不到普及;一些新技术如InSAR、三维激光扫描等能很快应用到滑坡监测领域;监测数据的采集和传输也都实现了自动化和远程化;监测和预警系统有向Web—GIS发展的趋势。利用一个地区的滑坡易发区划或危险区划,结合降雨临界值,可以设定不同的预警级别,在区内布设一定数量的雨量站,监测雨量加上预报雨量,就可进行滑坡预警预报,国内外的区域性降雨型滑坡监测预警大体都是这个思路和做法,该方法在对公众进行警示方面起到了良好效果,但由于预警的范围太大,在具体的单点防治上,难以做到有效。我国在近10年开展了大量的监测预警工作,并取得了丰硕的成果,但根据统计数据,其成功预警率却并不理想,这一方面表现在成功预警实例中专业预警所占比例过低,另一方面同时表现在发生的大量的地质灾害在已有的预警点之外。制约目前工作有效性的主要问题是滑坡隐患点的排查和识别问题,因为只有识别出了隐患点才能进行下一步的监测和预警,它是一切工作的基础。而解决这一问题的重要途径是分析区域上的滑坡发育规律,找到有效的隐患点识别技术方法,以及引进风险管理的概念,进行监测资源的合理分配和有效预警。  相似文献   

Review of Digital Elevation Model （DEM） Based Research on China Loess Plateau     

Tang Guo＇an Ge Shanshan Li Fayuan Zhou Jieyu 《山地科学学报》2005,2(3):265-270

Introduction The Loess Plateau is located in the upper and middle reaches of the Yellow River, among the western Taihang Mt, eastern Riyue-Helan Mt, northern Qinling Mt, and southern Yinsan Mt (from 100°54′to 114°33′E and 33°43′to 41°31′N; Figure 1). It covers a total area of 624,000 km2. The Loess Plateau of China has drawnworldwide attention in geographical research for its unique morphological features, abundant nature resources, most serious soil erosion, as well as its pot…  相似文献   

Towards end-to-end models for investigating the effects of climate and fishing in marine ecosystems   总被引：2，自引：0，他引：2  

M. Travers  Y.-J. Shin  S. Jennings  P. Cury 《Progress in Oceanography》2007,75(4):751-770

End-to-end models that represent ecosystem components from primary producers to top predators, linked through trophic interactions and affected by the abiotic environment, are expected to provide valuable tools for assessing the effects of climate change and fishing on ecosystem dynamics. Here, we review the main process-based approaches used for marine ecosystem modelling, focusing on the extent of the food web modelled, the forcing factors considered, the trophic processes represented, as well as the potential use and further development of the models. We consider models of a subset of the food web, models which represent the first attempts to couple low and high trophic levels, integrated models of the whole ecosystem, and size spectrum models. Comparisons within and among these groups of models highlight the preferential use of functional groups at low trophic levels and species at higher trophic levels and the different ways in which the models account for abiotic processes. The model comparisons also highlight the importance of choosing an appropriate spatial dimension for representing organism dynamics. Many of the reviewed models could be extended by adding components and by ensuring that the full life cycles of species components are represented, but end-to-end models should provide full coverage of ecosystem components, the integration of physical and biological processes at different scales and two-way interactions between ecosystem components. We suggest that this is best achieved by coupling models, but there are very few existing cases where the coupling supports true two-way interaction. The advantages of coupling models are that the extent of discretization and representation can be targeted to the part of the food web being considered, making their development time- and cost-effective. Processes such as predation can be coupled to allow the propagation of forcing factors effects up and down the food web. However, there needs to be a stronger focus on enabling two-way interaction, carefully selecting the key functional groups and species, reconciling different time and space scales and the methods of converting between energy, nutrients and mass.  相似文献   

Geographical and temporal variation in levels of organochlorine contaminants in marine mammals   总被引：1，自引：0，他引：1  

Aguilar A  Borrell A  Reijnders PJ 《Marine environmental research》2002,53(5):425-452

The interpretation of the spatial and temporal patterns of variation in organochlorine concentrations in marine mammal populations is complex because of the lack of wide-scale, long-term surveys. Therefore the results from several surveys must be combined and this causes undesired heterogeneity due to differences in the sampling and analytical techniques used and in the biological characteristics of the individuals sampled. Moreover, information is not homogeneously distributed in either space or in time. Most research is concentrated in western Europe, northern America and certain areas of Asia, while it is extremely limited or non-existent in Africa and most regions of the southern hemisphere. Marine mammals from the temperate fringe of the northern hemisphere, particularly fish-eating species which inhabit the mid-latitudes of Europe and North America, show the greatest organochlorine loads; noteworthy are the extremely high levels found in the Mediterranean Sea and certain locations on the western coasts of the United States. Concentrations in the tropical and equatorial fringe of the northern hemisphere and throughout the southern hemisphere are low or extremely low. The polar regions of both hemispheres showed the lowest concentrations of DDTs and PCBs, although levels of HCHs, chlordanes and HCB were moderate to high in the cold waters of the North Pacific. During recent decades, concentrations have tended to decrease in the regions where pollution was initially high but they have increased in regions located far from the pollution source as a consequence of atmospheric transport and redistribution. It is expected that the Arctic and, to a lesser extent, the Antarctic, will become major sinks for organochlorines in the future; this process may already be significant for some compounds such as HCB and HCHs. Effort should be devoted to both assessment of organochlorine trends in the now highly polluted populations of the temperate fringe of the northern hemisphere and to the implementation of long-term monitoring of marine mammal populations inhabiting polar regions.  相似文献