年代际气候变率问题的研究   总被引：7，自引：3，他引：7  

徐建军  朱乾根 《南京气象学院学报》1996,19(4):488-495

对年代际气候变率的研究工作和主要结果作了综合评述，并对该领域的研究前景作了一定的阐述。  相似文献   

我国国家重力网的系统转换     

丁行斌  陆仲连  孙风华  陈春旺 《测绘学院学报》1996,(4)

本文分析了我国１９５７年国家重力网的精度和问题，探讨了国家重力网的系统转换模式，利用现有的新旧重力网的重合点实际数据进行了回归分析、方差分析和系统误差检验，结果表明在“５７网”与“８５网”之间，除了—１３．５８ｍｇａｌ的平均基准差之外，并不存在其它明显的系统误差，特别是看不出有尺度系统差的影响，也不存在差值随纬度变化的任何规律。因此认为将“５７网”系统转换成“８５网”系统时，可以不必加“尺度系统差改正”，更不用考虑“非线性系统差改正”，建议一律只加一项“基准系统差改正”，其数值应该采用—１３．５８ｍｇａｌ。  相似文献   

钙质土力学性质研究现状与进展   总被引：4，自引：8，他引：4  

刘崇权  杨志强 《岩土力学》1995,16(4):74-84

概述了钙质土的成因，在世界范围内的分布及一般性质，综述了国内外对钙质土静、动力学性质研究持现状与进展，得到有关结论并提出今后应加强研究的方向。  相似文献   

Big spatial data for urban and environmental sustainability     

Bo Huang  Jionghua Wang 《地球空间信息科学学报》2020,23(2):125-140

ABSTRACT

Eighty percent of big data are associated with spatial information, and thus are Big Spatial Data (BSD). BSD provides new and great opportunities to rework problems in urban and environmental sustainability with advanced BSD analytics. To fully leverage the advantages of BSD, it is integrated with conventional data (e.g. remote sensing images) and improved methods are developed. This paper introduces four case studies: (1) Detection of polycentric urban structures; (2) Evaluation of urban vibrancy; (3) Estimation of population exposure to PM2.5; and (4) Urban land-use classification via deep learning. The results provide evidence that integrated methods can harness the advantages of both traditional data and BSD. Meanwhile, they can also improve the effectiveness of big data itself. Finally, this study makes three key recommendations for the development of BSD with regards to data fusion, data and predicting analytics, and theoretical modeling.  相似文献   

水文科技发展回顾及思考   总被引：5，自引：0，他引：5  

张建云  章树安 《水文》2006,26(3):13-17

水文科技是水文工作和水利科技一个重要组成部分,长期以来水文科学技术对我国水文与水利事业的发展和国民经济建设起到了巨大的推动作用,我国水文科学技术发展随着水文、水利与国民经济的发展和科学技术的进步取得了巨大成就,有些技术达到获接近国际先进水平。本文对我国水文科技取得的主要成就进行了总结,对目前水文科技存在主要问题进行了分析;结合水资源可持续利用支持社会经济可持续发展的需求,对水文科技发展的重点和策略进行了分析和探讨。  相似文献   

湿地水文研究进展综述   总被引：15，自引：0，他引：15  

王兴菊  许士国  张奇 《水文》2006,26(4):1-5,9

湿地是地球上一种重要的生态系统,具有巨大的环境功能和环境效益。水文是湿地中最重要的过程,是决定产生和维持湿地典型类型和湿地过程的重要因素。因此,湿地水文过程的研究是湿地研究的核心内容,是当前国内外湿地研究的热点。本文介绍了湿地水文及其对湿地功能等的重要性,综述了当前国内外在湿地水文状态与生态环境的关系、水流运动、水文模型与水文观测等方面的研究进展,并提出了今后我国亟待加强的湿地水文研究领域。  相似文献   

Uncertainty in GPS Networks due to Remaining Systematic Errors: The Interval Approach     

S. Schön  H. Kutterer 《Journal of Geodesy》2006,80(3):150-162

A realistic assessment of the total uncertainty budget of Global Positioning System (GPS) observations and its adequate mathematical treatment is a basic requirement for all analysis and interpretation of GPS-derived point positions, in particular GPS heights, and their respective changes. This implies not only the random variability but also the remaining systematic errors. At present in geodesy, the main focus is on stochastic approaches in which errors are modeled by means of random variables. Here, an alternative approach based on interval mathematics is presented. It allows us to model and to quantify the impact of remaining systematic errors in GPS carrier-phase observations on the final results using deterministic error bands. In this paper, emphasis is given to the derivation of the observation intervals based on influence parameters and to the study of the complex linear transfer of this type of uncertainty to estimated point positions yielding zonotopes. From the presented simulation studies of GPS baselines, it turns out that the uncertainty due to remaining systematic effects dominates the total uncertainty budget for baselines longer than 200 km.  相似文献   

土-结构动力相互作用研究综述   总被引：5，自引：0，他引：5  

方志  陆浩亮  王龙 《世界地震工程》2006,22(1):57-63

土与结构动力相互作用是当代力学领域的前沿性研究课题,具有很强的实践性。对土与结构动力相互作用的研究历史与现状进行了介绍,简要综述了当前土与结构动力相互作用的研究方法,重点介绍了目前关于土与结构动力相互作用问题中从无限域转化成有限域的人工边界研究进展问题,并对该领域今后的研究工作提出了建议。  相似文献   

隧道超前地质灾害预报综述   总被引：2，自引：0，他引：2  

毛正君  倪万魁  付晓刚 《中国地质灾害与防治学报》2007,18(4):79-81,87

隧道超前地质灾害预报在隧道施工中是十分重要的环节。文章对隧道超前地质灾害预报内容、原则、形式、方法、流程方面的研究现状进行了论述。着重对隧道超前地质灾害预报的各种方法进行了分析对比。隧道超前地质灾害预报的方法各有优缺点和局限性,应该取长补短,综合分析,根据实际情况确定应该采取的方法及其组合。在隧道超前地质灾害预报工作中,必须处理好与施工单位的关系。  相似文献   

Affine distortion of small GPS networks with large height differences     

Steffen Schön 《GPS Solutions》2007,11(2):107-117

GPS is a promising tool for real-time monitoring of deformations of slopes or large structures. However, remaining systematic effects in GPS phase observations after double differencing and application of a priori models affect the resulting coordinates. They complicate the proper separation of the actual deformations from pseudo-deformations induced by the systematic effects. This paper shows that for small monitoring networks (baseline lengths <5 km) only affine distortions of the network geometry are generated by the remaining distance dependent systematic effects, e.g. unmodelled tropospheric and ionospheric propagation effects, or satellite orbit errors. Hence, a generic correction model is given by a three-dimensional affine transformation involving a maximum of 12 transformation parameters. For the determination of these parameters, four high quality GPS stations are necessary which are not affected by the actual deformations to be monitored. Based on the analysis of network geometries of synthetic GPS networks with large height differences and considering the physics of the GPS observations it is shown, however, that less than 12 parameters are sufficient for the computation of the corrections. The proposed 8 parameter model was applied to the GPS monitoring network of the Gradenbach landslide. For this small network with large height differences, it was shown that the distortions can be reduced by about 75%.  相似文献