Gauss-Markov模型的岭型GM估计     

马朝忠  张磊  归庆明  杜院录  韩松辉 《测绘学院学报》2007,(1)

针对目前文献中提出的各种抗差有偏估计没有对设计空间的粗差进行控制的问题,将岭估计与GM估计结合起来提出了一种新的抗差有偏估计———岭型GM估计,理论分析和计算结果均表明岭型GM估计不仅能消除法矩阵病态性的不良影响,而且能同时具有观测空间和设计空间的抗差性,是一种性能良好的估计。  相似文献   

Where are Germany’s gains from Kyoto? Estimating the effects of global warming on agriculture     

Günter Lang 《Climatic change》2007,84(3-4):423-439

Motivated by the high abatement costs of the Kyoto Protocol for Germany, this paper is estimating the economic impact of global warming on agriculture in that country. The hedonic approach is used as theoretical background. Stating that land prices are – among others – determined by climatic factors, this approach can consequently be used to value global warming. To avoid a priori restrictions stemming from functional forms, the land price function is modeled as quadratic Box–Cox function that nests a wide range of specifications. In a second step, the estimated results are used to forecast the impact of climate change. The results indicate that German farmers will be winners of climate change in the short run, with maximum gains occurring at a temperature increase of +0.6°C against current levels. In the long run, there may be losses from global warming. However, the net present value from climate change is under the most probable scenarios positive.  相似文献   

基于FME的空间数据处理实现   总被引：2，自引：0，他引：2  

熊登亮  贵仁义  赵俊三  潘邦龙 《四川测绘》2007,30(3):118-121,129

本文提出了空间数据处理的几个关键点,引入了Feature Manipulation Engine(以下简称FME)基于语义的数据转换处理软件,通过应用实例,介绍了如何在FME中实现各种空间数据处理,利用FMEPlug-in(SDK)开发新的数据格式插件,及利用FMEObject调用管道来开发集成的数据批处理程序,为空间数据处理提供了一个很好的思路。  相似文献   

多途径解决我国钾盐资源紧缺的对策探讨   总被引：6，自引：0，他引：6  

宋新宇  郎一环 《地质与勘探》1998,34(6):10-13

探讨了钾盐矿产的应用,钾盐矿产在世界及我国的分布状况,提出了解决我国钾盐矿产资源紧缺问题的途径。  相似文献   

Structure,diversity and stability of two oligochaete communities according to sedimentary inputs in Lake Geneva (Switzerland)   总被引：3，自引：1，他引：3  

Dr. Claude Lang  Pierre Hutter 《Aquatic Sciences - Research Across Boundaries》1981,43(2):265-276

Two oligochaete communities were sampled monthly during one year in two 35 m deep locations of Lake Geneva (Switzerland). Organic sedimentation was lower and less variable in station 1 than in station 2 (157 versus 214 g C m⁻²yr⁻¹). The oligochaete community in station 1 was more diverse and more stable (persistent over time) than in station 2, as long as the organic sedimentation was low. Diversity and stability decreased in station 1 when the organic sedimentation increased, and during anOscillatoria bloom. The less diverse community in station 2 was more resistent to these changes. Diversity was associated with environmental stability, but resistance to perturbation was greater in the simpler community which is adapted to changing environmental conditions. The value of oligochaete communities as an indicator of the level of eutrophication was reassessed according to our present data. Changes in the structure of oligochaete communities were related to changes in sedimentation processes.  相似文献   

Locational components of urban and regional public policy in postwar Vietnam: The case of Ho Chi Minh city (Saigon)     

Michael H. Lang Dr.  Barry Kolb 《GeoJournal》1980,4(1):13-18

Ho Chi Minh city is a primate city in which wartime dislocations have resulted in severely overcrowded conditions as well as a shrunken economic base. The new government has opted for a policy based on the rapid decanting of a large proportion of the urban population by encouraging internal migration to New Economic Zones in the hinterlands. This policy is based on a hierarchial administrative structure with agricultural productivity as its prime goal. A Green Belt policy has been articulated that uses the New Economic Zones as building blocks. The Green Belts constrain urban growth as well as provide foodstuff for the remaining urban residents. The ultimate objective of the overall policy is a balanced urban and regional environment that is in tune with Vietnam's agricultural economy.  相似文献   

Macrofaune des fonds de cailloux du Léman     

Dr Claude Lang 《Aquatic Sciences - Research Across Boundaries》1974,36(2):301-350

In Lake Geneva (Switzerland), the macrofauna of the stony lake bottom was studied in seven stations from 1969 to 1971. The modifications in animal communities since the beginning of the century can be attributed partly to the increasing eutrophication of the lake and partly to the introduction of new species. The stations are classified according to the structure of their animal communities, which enables us to deduce the degree of eutrophication of each station. The analysis of factors which influence the animals' microdistribution on lakebottom stones reveals many complicated interactions. As a result of this complexity, further research projects were concentrated on leeches (Hirudinea) which colonize artificial substrates in imitation of the underface of stones.Helobdella stagnalis, Erpobdella octoculata andGlossiphonia complanata form the major part of collected fauna. Density fluctuations, population structures (age groups) and quantitative relations between these three species as well as their vertical and horizontal distribution patterns were examined in great detail.   相似文献   

Seven-frequency VLBI Observations of the GHz-Peaked-Spectrum Source OQ 208     

Wen-Feng Luo Jun Yang Lang Cui Xiang Liu Zhi-Qiang Shen 《中国天文和天体物理学报》2007,7(5):611-619

We present quasi-simultaneous VLBI images of the GHz-Peaked-Spectrum radio source OQ 208 obtained with the Very Long Baseline Array at 1.4,1.7,2.3,5.0,8.4,15.4GHz and the European VLBI Network at 6.7 GHz.The low frequency(1.4,1.7 and 2.3GHz)ob- servations reveal a weak and extended steep-spectrum component at about 30mas away at position angle-110°,which may be a remnant emission.The radio structure of OQ 208 con- sists of two mini-lobes at 5.0,6.7,8.4 and 15.4 GHz.Our spectral analysis further confirms that the southwest lobe undergoes free-free absorption and finds that the free-free absorption is stronger in the inner region.By fitting the 8.4 GHz images from 1994 to 2005,we obtain a separation speed of 0.031±0.006 mas yr~(-1)between the two mini-lobes.This indicates a jet proper motion of 0.105±0.020 c and a kinematic age of 219±42 yr for the radio source.  相似文献   

赤道中太平洋对流活动与西太平洋副高西伸的时延相关分析     

余丹丹  张韧  洪梅  刘科峰  王辉赞  桂祁军 《海洋科学进展》2008,26(3)

采用交叉小波与相干小波变换方法,利用NCEP/NCAR再分析资料和 NOAA卫星观测的外逸长波辐射(OLR)资料,在多年平均资料分析的基础上,选择2005和2006年夏季西太平洋副高的西伸过程进行了诊断分析,重点讨论了赤道中太平洋地区的对流活动对西太平洋副高西伸与维持的影响与关联.结果表明,7月中旬到8月中旬间,赤道中太平洋地区的对流活动通常表现出半月左右的准周期振荡,与副高活动具有相似的时频结构和周期特征,且前者对后者存在着约一个周期的超前影响,两者的这种时延相关性表现出较好的预报意义;运用大气视热源和全型垂直涡度方程,讨论了赤道中太平洋地区对流活动引起的经向加热异常对副高西伸的影响,指出由于异常的非绝热加热在副高西伸区域产生异常的反气旋性涡度输送,进而影响和制约副高形态和位置的变异.  相似文献   

基于ArcGIS的洪水淹没分析模拟及可视化   总被引：2，自引：0，他引：2  

祝红英  顾华奇  桂新  朱朝炬 《测绘通报》2009,(5)

基于数字高程模型(DEM)格网模型,通过改进迭代种子蔓延算法,实现给定水深情况下洪水淹没区的讣算模型,讨论洪水淹没演进过程可视化实现的关键技术,并使用ArcEngine开发包进行二次开发,以二维和二三维两种可视化方式,动态而形象地模拟在指定洪水水位下的洪水淹没演进过程.试验证明,所提出的实现方法切实有效,便于推广应用,为快速、准确及科学地进行洪灾评估洪水风险图的制作提供良好的基础,对洪涝灾害进行评估和预测分析具有重要意义.  相似文献