Geography in a restructuring world?     

R. J. Johnston 《GeoJournal》1997,42(1):9-16

In those parts of their discipline which can be categorised as spatial analysis, geographers have focused attention on distance as a key variable, and have paid little attention to bounded spaces and territoriality strategies. In a rapidly restructuring world, in which distance is becoming increasingly irrelevant as an influence on many forms of behaviour, territoriality remains an important aspect of the manipulation of space for economic, social, political and cultural purposes: in the terminology of Hagerstrands classic model, while the coupling and capability constraints on interaction are weakening, the authority constraint remains strong.  相似文献   

地缘经济关系测度与分析的理论方法探讨--以云南省为例   总被引：12，自引：0，他引：12  

张学波  武友德  骆华松 《地域研究与开发》2006,25(4):34-39

文章首先简要分析了地缘经济学的发展进程和研究内容，提出以保护国家利益增强综合国力为主要研究目的的地缘经济理论在一定程度上可以指导不同级别区域经济合作策略的制定。然后在探究了地缘经济关系涵义的前提下，设计了地缘经济关系的测度体系，并用该方法对云南省地缘经济关系进行了数量测度和类型判别，进而对该省地缘经济关系进行了分析和评价，对经济发展提出了建议。  相似文献   

Verification of the motion fields over Southeast Asia by the Florida State University (FSU) superensemble forecast     

Mastura Mahmud  Robert S. Ross 《Singapore journal of tropical geography》2006,27(2):176-190

The Florida State University (FSU) multimodel superensemble forecast is evaluated against several other operational weather models for the Southeast Asia region. The superensemble technique has demonstrated its exceptional skills in forecasting precipitation, motion and mass fields compared to either individual global operational or ensemble mean forecasts. The motion field investigation for the season of 2001 reveals that the superensemble forecasts are closer to the observed data compared to the other global member operational models through its low systematic errors at the 850 hPa level. The FSU multimodel superensemble forecasts exhibit the lowest root mean square errors (RSMEs), the highest correlation against the best observed data and the lowest systematic errors compared to the other operational model members. These forecasts have the potential to provide better daily weather predictions over the Southeast Asia region, particularly during the early northeast monsoon that often causes heavy rainfall in the equatorial part of the Southeast Asia region.  相似文献   

煤与瓦斯突出预报的理想灰贴近函数聚类关联分析     

秦书玉  徐世国  孙平 《中国地质灾害与防治学报》2005,16(1):89-92

从预报煤与瓦斯突出所获取的数据信息知，其信息多数为灰色特征。为突出其灰色特性，本文采用理想灰贴近函数聚类关联分析预测预报煤与瓦斯突出的危险程度，并将此方法同模糊聚类预测预报法和模糊聚类关联分析预报法及模糊聚类相似分析预报法进行了对比分析。由对比分析可知，采用4种数学方法预测预报煤与瓦斯是否突出，给出的结论是一致的，只是预测预报是否发生的可能程度略有差别。其中关联分析比相似分析计算过程较简单，且相似分析在确定编号时，有时受截值λ取值影响。尽管如此，但不影响预测预报结果。所以，不论是采用模糊聚类，还是灰色聚类数学方法预报煤与瓦斯突出均是可行的，可在实践中应用。  相似文献   

等距等高电磁波测距三角高程测量及精度分析   总被引：7，自引：0，他引：7  

张正禄  黎明  邓勇  罗长林  张松林 《现代测绘》2005,28(1):3-4,19

介绍了等距等高电磁波测距三角高程测量的原理，详细深入地分析了这种高程测量方法的精度，通过计算和作图表示，可直观地反映在不同条件下的精度变化情况，讨论了代替国家等级水准测量的范围和条件，可供生产实际和进一步研究参考。  相似文献   

ARTIFICIAL NEURAL NETWORK CORRECTION OF ROUGH ERRORS OF OBSERVATIONS   总被引：1，自引：0，他引：1       下载免费PDF全文

蒋国荣  张韧  沙文钰  阎俊岳  姚华栋 《Acta Meteorologica Sinica》2002,(1)

In the context of tower measured radiation datasets.following the correction principle meetinga diagnostic equation in data quality control and in terms of a technique for model construction ondata and ANN(artificial neural network)retrieval for BP correction of radiation measurementswith rough errors available,a BP model is presented.Evidence suggests that the developed modelworks well and is superior to a convenient multivariate linear regression model,indicating its wideapplications.  相似文献   

GPS进行长边控制测量分析     

王兴国 《福建地质》2002,21(2):119-121

采用基准和基准转换模型的不同会导致GPS观测边长与坐标计算边长不一致。因此由GPS测量的WGS－84坐标系向我国的北京54坐标系转换计算时，应尽可能选择参考点作对比分析。若满足精度要求，可采用全国精密参数作转换计算，若不能满足精度要求或达不到实测点的定位精度，可先将边长作高程异常改正，再对起算点作方位改正。  相似文献   

Analysis of Post-Failure Slope Movements within the Framework of Hazard and Risk Analysis     

Vaunat  Jean  Leroueil  Serge 《Natural Hazards》2002,26(1):81-107

The paper first recalls briefly a methodological framework to assess landslide hazard and risk analysis in terms of predisposition, triggering andrevealing factors. This framework, that reflects the mechanisms involved in the landslide, is based on the Geotechnical Characterisation of slope movements proposed by Vaunat et al. (1994) and Leroueil et al. (1996). The Geotechnical Characterisation can be schematized by a 3-D matrix having the following axes: types of movement; types ofmaterial; and the four stages of movement: pre-failure, failure, post-failure andreactivation. For each relevant element of this 3-D matrix, there is a characterisationsheet including: the controlling laws and parameters, the predisposition factors, thetriggering or aggravating factors, the revealing factors and the consequences of the movement. The paper focuses afterwards on the post-failure stage, which generallyis the most destructive, and on the mobility index. It is shown that this laterindex can be described as the product of sub-indices associated with failure, brittlenessof the material, ability of the soil to develop pore pressures, geometry of the moving soil mass and characteristics of the terrain. It is also shown how these aspectscan be incorporated into the Geotechnical characterisation of slope movements. This seems to provide a rational basis for examining slope movements at the post-failure stage and assessing associated risks.  相似文献   

Simulation of individual particle movement in a gravel streambed     

J. Mikael Malmaeus  Marwan A. Hassan 《地球表面变化过程与地形》2002,27(1):81-97

A two‐dimensional simulation model of travel distances of individual particles in a gravel‐bed river is presented. The model is based on a number of rules, which include particle size, entrainment, trajectory, distance of movement and entrapment. Particle interactions are controlled by resistance fields defined about each obstacle and critical elevation defined in the model. Resistance fields, particle dropping and critical elevation rules control particle interactions. The interaction rules cause the particles to develop pebble clusters, stone cells and transverse structures (transverse ribs). The simulated travel distances of individual particles are consistent with reported field results. Individual particle travel distances were simulated using two different models; one without interactions between the individual particles and the stationary bed and one with interactions. The case without interactions demonstrates the random nature of sediment transport, and narrow ranges of travel distances. Wider ranges of travel distances, similar to those for natural situations, were obtained for the cases with interactions. The more intense the interaction between the mobile stones and the stationary ones, the wider the range of distances of travel for a given particle size. Modelling the mean travel distance yielded a result similar to that published previously, which was based on empirical data. Well developed bed‐surface structures were obtained for relatively poorly sorted sediment with intense interactions between particles. Transverse structures developed when relatively large particles were allowed to move. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

ARTIFICIAL NEURAL NETWORK CORRECTION OF ROUGH ERRORS OF OBSERVATIONS^*          下载免费PDF全文

JIANG Guorong  ZHANG Ren  SHA Wenyu  YAN Junyue  YAO Huadong 《Acta Meteorologica Sinica》2002,16(1):123-132

In the context of tower measured radiation datasets.following the correction principle meeting a diagnostic equation in data quality control and in terms of a technique for model construction on data and ANN (artificial neural network) retrieval for BP correction of radiation measurements with rough errors available,a BP model is presented.Evidence suggests that the developed model works well and is superior to a convenient multivariate linear regression model,indicating its wide applications.  相似文献