Barotropic local instability and severe storm process     

Dasheng Yang  Lan Sun 《中国科学D辑(英文版)》1997,40(3):259-268

By means of barotropic model, the characteristic and initial value problems are investigated to reveal the local two-dimensional barotropic instability of the nonuniform current to the dynamic mechanism of the formation of the Yangtze-Huaihe River severe storm in July 1991. Analytical theory and numerical experiment show that (i) the unstable developing modes are chiefly the two periods of about 44 d and 10 d, which are fundamentally consistent with that of the precipitation change of the Yangtze-Huaihe River. (ii) The growth rate of the local perturbation is dominated by the meridional wave numbern = 1–5 and zonal wave numberk = 1–12, i.e. the severe storm over the Yangtze-Huaihe River results from the interaction of the systems at different latitudes and waves of different scales, (iii) The perturbation over the Yangtze-Huaihe River possesses the property of local intensification, which slowly migrates westward over the lower and middle reaches of the Yangtze-Huaihe River. (iv) The growth rate of the instability, especially the propagation velocity of the perturbation, is sensitive to the external parameters ū and α. Project supported by the National Natural Science Foundation of China.  相似文献   

美国长期生态研究计划：背景、进展和前景   总被引：1，自引：3，他引：1  

赵士洞 《地球科学进展》2004,19(5):840-844

由美国国家科学基金会支持的长期生态研究计划于1980年启动，至今在理论研究、开发技术和服务社会方面都取得了举世瞩目的成就。该计划的发展分为 3个阶段，每一阶段大约为10年。在其发展的第一个阶段，是以研究站所代表的生态系统为研究对象，主要开展了生态系统的过程与格局方面的研究并系统采集和存贮了有关数据；在1990 -2000年的第二个发展阶段中，其研究工作的重点是开展跨站的网络研究和人类活动对生态系统的影响，以揭示生态系统的过程与格局在较大空间尺度上的特征；按照规划，美国长期生态研究计划的发展进入到第三个阶段后，其工作的重点是开展综合研究、进行生态预测和更好地为社会发展服务，同时加强生物多样性的研究和信息学的发展。  相似文献   

关于当前我国战略性矿产勘查工作几个问题的思考     

王瑞江 《地质通报》2004,23(11):1074-1077

战略性矿产勘查是近几年根据中国地勘管理体制的新变化和国家对矿产勘查工作的新要求提出的概念。本文从战略性矿产的基本内涵、战略性矿产资源勘查工作的性质与任务、战略性矿产资源勘查工作与传统矿产勘查工作的差异、战略性矿产资源勘查工作的管理体制与运行机制等几个方面进行了初步探讨，旨在明确其性质定位和目标任务，逐步建立国家出资的公益性地质工作与后续商业性矿产勘查工作良性互动、有机结合的有效机制，促进中国矿产勘查业全面、健康地发展。  相似文献   

花岗岩研究进展 ———ISMA花岗岩类分类综述   总被引：4，自引：0，他引：4       下载免费PDF全文

陈建林  郭原生  付善明 《甘肃地质》2004,13(1):67-72

本文在论述花岗岩主要分类的基础上论述了ISMA花岗岩类的基本含义,讨论了人们在以后应用和推广ISMA这类花岗岩分类方案时存在的一些问题,指出了ISMA花岗岩类本身在分类过程中存在的一些基本问题。  相似文献   

渭干河-库车河三角洲绿洲50 a来农业开发及所引发的生态问题探析   总被引：6，自引：5，他引：6  

满苏尔·沙比提  海鹰  帕尔哈提·艾孜木 《中国沙漠》2004,24(3):349-354

从渭干河-库车河三角洲绿洲50a来农业开发与生态建设的过程看，人工绿洲耕作农业的生产力水平有较显著的提高，人工绿洲生态也得到了改善。主要表现是单位面积生产力水平提高，农田防护林体系初步建立，水利工程建设得到加强，生活能源的短缺得到改进。但从流域的绿洲农业经济发展与生态环境建设仍存在一些不协调的问题。主要是农田施肥重化肥轻有机肥，土壤肥力不高；灌区中游重灌轻排，灌排不协调，盐渍化面积有所扩大；流域下游由于缺水和人为等因素使天然绿洲的稳定性受到威胁，天然林的绿色屏障作用大为削弱等。对此必须引起足够重视，逐步加以协调，才能实现绿洲农业经济的可持续发展。  相似文献   

矢量地形图拓扑等问题的研究与实践     

赵明  王庆  陈昕  鞠建荣  张凤梅 《现代测绘》2004,27(5):44-45,48

对矢量地图生产过程中常见的图形拓扑、数据冗余问题进行分析和研究；在此基础上结合生产实践，提出了相应的解决办法。研制了基于AutoCAD2000平台的相关程序。  相似文献   

南方NGS200应用实践中的若干问题     

李玉宝 《四川测绘》2004,27(1):39-41

对南方NGS200在工程控制测量领域应用实践中的一些问题作了阐述，提出了一些见解和措施。  相似文献   

东北地区矿业开发态势与矿山环境地质问题综合研究   总被引：1，自引：0，他引：1  

金洪涛  贾伟光  邸志强 《华南地质与矿产》2005,(3):50-54

在论述东北地区矿业开发态势的同时,阐述了区内能源矿产、金属矿产及非金属矿产开采引发的主要环境地质问题,针对区内复杂的矿山环境地质问题现状,提出了开展东北地区矿山环境地质综合研究问题的工作思路.  相似文献   

Research relevance, 'knowledge transfer' and the geographies of CASE studentship collaboration   总被引：1，自引：0，他引：1  

David Demeritt  Loretta Lees 《Area》2005,37(2):127-137

The Co-operative Awards in Science and Engineering (CASE) studentship programme of the UK Research Councils provide one example of wider efforts internationally to encourage so-called 'knowledge transfer' and thereby harness publicly supported university research more closely to the goals of national competitiveness, regional economic development and local regeneration. In this paper we describe the implications of how the various UK research councils have interpreted the objectives and beneficiaries of 'knowledge transfer', both for the relative opportunities available to human and physical geographers for collaboration through CASE and for the sorts of values that their research must serve. Then, we draw on unpublished data from the Economic and Social Research Council (ESRC) to explore the geographies of CASE studentship allocation and participation. The broad regional and institutional patterns of participation we describe have important implications for ongoing debates in the UK about research selectivity and the role of the university as an engine of local development, while the striking disciplinary patterns of CASE participation, and in particular the overwhelming success of geographers in this competitive programme, provide an opportunity to reassess claims about whether and for whom geographical research is relevant.  相似文献   

Microcrack networks in granite affected by a fault zone: Visualization by confocal laser scanning microscopy     

Celia T. Onishi  Ichiko Shimizu   《Journal of Structural Geology》2005,27(12):170

Microcracks in the Cretaceous Ryoke-type granite in Japan were investigated by using deep drilling core samples collected in the Mizunami Underground Research Project of the Japan Nuclear Cycle Development Institute (JNC). The granite body suffered brittle deformation associated with Tertiary thrust movement. Based on core-scale and microscopic deformation features, the drill core from a depth of 300 to 700 m is divided into four domains, i.e. (A) undeformed granite, (B) granite intruded by cataclastic seams, (C) fractured granite in the fault damage zone, and (D) foliated cataclasite at the fault center. To characterize microcrack geometries in each domain, we employed the impregnation method using a low-viscous acrylic resin doped with fluorescent agents and captured the microcrack images by confocal laser scanning microscopy (CLSM). The CLSM image in the fault damage zone revealed anisotropic development of microcrack networks related to the fault movement. Both CLSM observation and porosity measurements reveal a drastic increase of micro-pores in the foliated cataclasite, possibly caused by fragmentation, and granulation and crack sealing in the fault zone.  相似文献