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1980年代以来英美城市社会极化问题及其研究 总被引:2,自引:0,他引:2
城市社会极化,是一种复杂的社会经济现象,是举世瞩目的现代社会问题。社会学家和地理学家从经济转变、种族、职业收入、财富分配、家庭结构和教育等多个角度对此进行了大量研究。本文着重介绍1980年代以来英美学者对社会极化问题的解释与论证,主要包括对城市社会极化的认识、新城市贫困(尤其是大城市中心区)的成因、种族隔离对少数民族(特别是黑人)的影响等方面。 相似文献
874.
S. Oldfield 《GeoJournal》2002,57(1-2):29-37
This paper analyzes processes of state restructuring at the scale of the local state and the city, exploring the social and
political relationships generated through processes of reconstruction specifically in Elsies River, a formerly segregated
`coloured' neighborhood in Cape Town. While the relationship between Elsies River residents and the local state has been characterized
by an obsessive focus on housing debt, I examine the ways in which antagonism over housing problems overlie a broader relational
disjuncture between neighborhood and state political and social networks. The specificity of this case provides a lens onto
the ways in which processes of state restructuring both contest and reinforce racial, economic, and place-based inequalities
in South African cities. The paper concludes by using the complexities of local state-neighborhood relationships in the South
African case to reflect on geographical theories of state-society relations on a conceptual level.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
875.
Review On The Calculation Of Surface Electric And Magnetic Fields And Of Geomagnetically Induced Currents In Ground-Based Technological Systems 总被引:2,自引:0,他引:2
Risto Pirjola 《Surveys in Geophysics》2002,23(1):71-90
Space weather is a popular and important research topic today. Its origin isin the Sun. Space weather effects extend to the surface of the Earth where theyare usually called GIC referring to geomagnetically induced currents intechnological systems such as electric power transmission grids, oil and gaspipelines, telecommunication cables and railway equipment. GIC are a possiblesource of problems within such systems, and observations have been made sincethe first telegraph systems in the 1800's. This paper is a summary and reviewof present knowledge and of possibilities of modelling GIC in a system.Modelling efforts require a determination of the electric field occurring inconnection with a magnetic storm at the Earth's surface and a calculation ofthe resulting GIC. Different modelling techniques of the electric and magneticfields are evaluated in this paper, and special attention is paid to thecomplex image method (CIM) which is suitable for time-critical purposes likeforecasting of GIC. A discretely-earthed power system and a buried pipelineneed different calculation methods of GIC. The former can be treated by amatrix formalism while the distributed-source transmission line (DSTL) theoryis applicable to the latter. 相似文献
876.
马德荣 《沙漠与绿洲气象(新疆气象)》2002,25(1):19-20
从雪对电磁波的散射和衰减入手,定性分析了714C天气雷达的测雪能力,以2000年冬季测雪实践为例,总结了乌鲜果昌机场714C天气雷达测雪的一般特点。 相似文献
877.
根据神威集合数值天气预报的运行特点, 针对其运行过程中可能遇到的问题, 介绍了自主研制的可视化实时监控系统的解决方案。 相似文献
878.
Results from One-Year Continuous Operation of a Large Aperture Scintillometer over a Heterogeneous Land Surface 总被引:8,自引:0,他引:8
F. Beyrich H. A. R. De Bruin W. M. L. Meijninger J. W. Schipper H. Lohse 《Boundary-Layer Meteorology》2002,105(1):85-97
A large-aperture scintillometer (LAS) was operated continuouslyduring a period of more than one year over a heterogeneous land surface in Central Europeat the transition between marine and continental climates. The LAS measurements of the refractiveindex structure parameter, CN
2, were used to estimate the sensible heat flux. Thiswas possible for about 60to 80% of the time under daytime conditions during thesummer, with lower values obtained for the cold season (October to March). Using datafrom a three-week long field experiment, the LAS-based heat flux was compared with a weighedaverage of local heat flux measurements over the main land use classes (forest, agriculture,water) in the area, resulting in reasonable agreement. LAS-based heat fluxes were then used forcomparison with the heat flux values of a numerical weather prediction model. An over-predictionof the model heat flux was found in summer but the modelled values were lower than the LASderived data during the cold season. 相似文献
879.
红富士苹果优质是当前果树生产的重要研究项目之一。通过近年来对山西吉县异常天气的分析调查及对苹果生产的影响,提出了相应的生产管理措施,对红富士苹果优质生产具有一定的指导意义。 相似文献
880.