我国2000年干旱情况分析及发展趋势展望   总被引：2，自引：0，他引：2  

干旱分析小组 《气象》2000,26(10):3-9

重点分析了２０００年２￣７月份我国北方高温少雨的时空分布特征,并与国外及我国历史上的干旱特征进行了对比;从大气环流、海洋、天气气候及全球变化的角度初步探讨了干旱的成因;回顾了今年春、夏季北方少雨（干旱）的预报服务情况,并初步展望了未来秋、冬、春季降水趋势;建议在制订相应应急政策、加强保护生态环境及水资源的同时,加强气象部门对人工影响天气、干旱预警系统及干旱机理等方面的业务建设和科学研究。  相似文献   

MATHEMATICAL MODELS FOR LIQUID-SOLID TWO-PHASE FLOW   总被引：2，自引：0，他引：2  

Weiming Wu  Sam S.Y. Wang National Center for Computational Hydroscience  Engineering  The University of Mississippi  MS  U.S.A. 《国际泥沙研究》2000,(3)

I INTRODUCTIONTurbulence models for single-phase fluid flows have been developed and widely applied in mechanical,aeronautical, environmental and hydraulic engineering, and other fields. The closure techniques for theReynolds-averaged Navier-Stokes equations for various levels of models including the simple turbulencemodel, one-equation turbulence model, k-s turbulence model and turbulence stress/flux model have beenverified to be physically reasonable and have acceptable accuracy in app…  相似文献   

Review of Global Ocean Intermediate Water Masses: 1.Part A, the Neutral Density Surface (the ‘McDougall Surface’) as a Study Frame for Water-Mass Analysis     

Yuzhu You )  )  * ) The University of Sydney Institute of Marine Science 《中国海洋大学学报(英文版)》2006,(3)

1Preface Todescribeoceanicintermediatewatermasses,itis necessarytohaveawell definedstudyframeorsurfacebecauseofthefluctuationnatureofintermediatewa ters.Itiswellunderstoodthatoceanicwater mass mixingdoesnotalignwitheitheraconstantgeopoten tialdepthorapropertysurfacesuchastemperature,salinity,pressureanddensitysurfacesbutfollowsa neutraldensitysurface.Thisisbecauseawaterparcelmovesasmalldistanceisentropicallyandadiabaticallyontheneutraldensitysurfacewithoutdoingworka gainstabuoyantrestoringforc…  相似文献   

太阳物理学中的分形和混沌   总被引：1，自引：0，他引：1  

环遵祥  吴铭蟾 《天文学进展》1996,14(4):286-296

对非线性科学的两个重要分支；分形和混沌在太阳物理学中的应用情况作了综述信要内容包括；太阳活动混沌性的揭示；对太阳活动混沌性的可能解释－太阳非线性发电机理论；一些太阳现象的分形描述；耀斑的自组织临界行为研究，最后给出了作者对这一领域工作前景的展望。  相似文献   

Combining satellite and seismic images to analyse the shallow structure of the Dead Sea Transform near the DESERT transect     

D. Kesten  M. Weber  Ch. Haberland  Ch. Janssen  A. Agnon  Y. Bartov  I. Rabba  The DESERT Group 《International Journal of Earth Sciences》2008,97(1):153-169

The left-lateral Dead Sea Transform (DST) in the Middle East is one of the largest continental strike-slip faults of the world. The southern segment of the DST in the Arava/Araba Valley between the Dead Sea and the Red Sea, called Arava/Araba Fault (AF), has been studied in detail in the multidisciplinary DESERT (DEad SEa Rift Transect) project. Based on these results, here, the interpretations of multi-spectral (ASTER) satellite images and seismic reflection studies have been combined to analyse geologic structures. Whereas satellite images reveal neotectonic activity in shallow young sediments, reflection seismic image deep faults that are possibly inactive at present. The combination of the two methods allows putting some age constraint on the activity of individual fault strands. Although the AF is clearly the main active fault segment of the southern DST, we propose that it has accommodated only a limited (up to 60 km) part of the overall 105 km of sinistral plate motion since Miocene times. There is evidence for sinistral displacement along other faults, based on geological studies, including satellite image interpretation. Furthermore, a subsurface fault is revealed ≈4 km west of the AF on two ≈E–W running seismic reflection profiles. Whereas these seismic data show a flower structure typical for strike-slip faults, on the satellite image this fault is not expressed in the post-Miocene sediments, implying that it has been inactive for the last few million years. About 1 km to the east of the AF another, now buried fault, was detected in seismic, magnetotelluric and gravity studies of DESERT. Taking together various evidences, we suggest that at the beginning of transform motion deformation occurred in a rather wide belt, possibly with the reactivation of older ≈N–S striking structures. Later, deformation became concentrated in the region of today’s Arava Valley. Till ≈5 Ma ago there might have been other, now inactive fault traces in the vicinity of the present day AF that took up lateral motion. Together with a rearrangement of plates ≈5 Ma ago, the main fault trace shifted then to the position of today’s AF.  相似文献   

中国地震局代表团访问智利     

中国地震局赴智利代表团 《国际地震动态》2001,(6):15-16

应智利国家科学技术委员会 (CONICYT)邀请 ,以中国地震局刘玉辰副局长为团长的中国地震局代表团一行 5人 ,于 2 0 0 1年 3月 12～ 19日对智利进行了访问。智利是一个地震多发国家 ,2 0世纪在该国曾发生过一次 8.9级巨大地震 ,这是人类历史上迄今为止记录到的最大地震。智利地域狭长 ,地震多发生在北部和中部地区。目前 ,智利全国共有 5 0多个地震台 ,使用的绝大部分是短周期、单分向地震计 ,仅有 3个宽频带数字地震台装有 STS-2型地震计。其中 13个台采用无线电短波进行实时传输。智利大学等已经与法国、美国开展了合作研究 ,其中与美国…  相似文献   

GIS APPLICATION IN RESEARCH OF WILDLIFE HABITAT CHANGE——A case study of the Giant Panda in Wolong Nature Reserve   总被引：2，自引：0，他引：2  

Liu Xuehua Institute of Geography  CAS  Beijing People''s Republic of China M.C. Bronsveld A.G. Toxopeus M.S. Kreijns International Institute for Aerospace Survey  Earth Sciences The Netherlands 《地理学报(英文版)》1997,(4)

Ｉ.ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅＧｉａｎｔＰａｎｄａ(Ａｉｌｕｒｏｐｏｄａｍｅｌａｎｏｌｅｕｅａ)ｉｓａｎｅｎｄａｎｇｅｒｅｄａｎｉｍａｌｓｐｅｃｉｅｓｉｎｔｈｅｗｏｒｌｄ.Ｔｈｅｒｅａｒｅａｂｏｕｔ1000ｉｎｄｉｖｉｄｕａｌｓｌｅｆｔａｎｄｃｏｎｆｉｎｅｄｉｎｔｈｅｉｓｏｌａｔｅｄｍｏｕｎｔａｉｎａｒｅａｓｉｎｔｈｅｓｏｕｔｈｗｅｓｔｅｒｎｐａｒｔｏｆＣｈｉｎａ.Ｉｔｓｒｅｍａｉｎｉｎｇｈａｂｉｔａｔｃｏｖｅｒｓａｂｏｕｔ29,500ｋｍ2[2,6,11].Ｈｕｍａｎｅｎｃｒｏａｃｈｍｅｎｔｉｓｃｏｎｓｉｄｅｒｅ…  相似文献   

地震短临预报动态跟踪技术决策     

全莹道 《东北地震研究》1992,(4)

本文根据震例所提供的短临异常的整体行为,归纳出地震短临预报动态跟踪技术决策,提出短临阶段的标志、预期异常、跟踪方法和内容等。考虑到决策的完整性,增加了中期异常的再审查和认定、行政干预等部分。  相似文献   

MODELING SEDIMENT PROCESSES ON SMALL WATERSHEDS:A CONCEPTUAL FRAMEWORK Ⅰ. BROAD SHALLOW FLOW PROCESSE     

Vicente L. LOPES Assistant Professor  School of Renewable Natural Resources  The University of Arizona  Tucson  Arizona  Peter F. FFOLLIOTT Professor  School of Renewable Natural Resources  The University of Arizona 《国际泥沙研究》1992,(3)

A conceptual modeling framework for developing process-based mathematical models of sediment generation, transport, and deposition on broad shallow flow areas is presented. The governing equations relevant to process-based modeling of broad shallow flow sediment processes on small watersheds are presented and the effects of space and time averaging on the predictive equations are described. Starting from the most general one-dimensional, unsteady model of sediment processes, simpler model structures are obtained and the successive simplifications made on the governing equations in order to obtain simpler and less detailed formulations are described. Specific model formulations are given for illustrative purposes and applications of these models to erosion and sediment yield prediction from broad shallow flow areas are shown using sediment data from rainfall simulator plots. In spite of some progress made in the development of process-based erosion and sediment yield models from broad shallow flow areas, further developmental modeling efforts must be based on a clear separation between hydrologic and hydraulic processes, and the soil properties which are significant for each.  相似文献   

SIMPLE VALIDATORY TOOLS FOR JUDGING THE PREDICTIVE PERFORMANCE OF PARAFAC AND THREE-WAY PLS     

AGEK.SMILDE  DURKA.DOORNBOS 《地理学报(英文版)》1992,(1)

The methods PARAFAC and three-way PLS are compared with respect to their ability to predictreversed-phase retention values.Special attention is paid to simple validatory tools,the meaning and useof which are explained.The simple validatory tools consist of percentages of explained variation in the training set and thosethat can be calculated with the use of markers.These markers are special(reference)solutes,the retentionvalues of which are used to gain information about a new object for which predictions are wanted.Different validatory tools can be calculated with the use of these marker retention values:percentagesof used variation and mean sum of squared residuals after applying the model to these marker retentionvalues.The validatory tools are evaluated on their power to estimate their test set counterparts:thepercentages of explained variation in the test set and mean sum of squared prediction errors in the test set.Two different data sets from reversed-phase chromatography are used to evaluate the validatory tools.The first data set has a high signal-to-noise ratio and is measured under the same measurementconditions.The second data set has a low signal-to-noise ratio and is measured under differentmeasurement conditions.Some of the simple validatory tools seem to have relevance to their test setcounterparts,even in the case of the second data set.  相似文献