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991.
Impact of the eastern water diversion from the south to the north project on the saltwater intrusion in the Changjiang Estuary in China 总被引:3,自引:0,他引:3
The south to the north project(WDP) on the saltwater intrusion in the Changjiang Estuary is studied by the improved three-dimensional(3D) numerical model.The net unit width flux in the Changjiang Estuary as well as the sectional salt flux is calculated in the North Branch(NB),the South Branch(SB),the North Channel(NC),the South Channel(SC),the North Passage(NP) and the South Passage(SP),respectively.The net seaward water flux in the SB is reduced,and the net water flux spilling over from the NB to the SB is enhanced after the eastern WDP.Under the mean river discharge condition in the dry season,the net salt flux spilling over from the NB to the SB is increased by 2.09 t/s and 0.52 t/s during the spring and neap tides,respectively,due to the eastern WDP.The saltwater intrusion in the Changjiang Estuary is enhanced by the eastern WDP.Compared with that during the spring tide,the net water diversion ratio during the neap tide in the NC is smaller,and thus the enhancement of the saltwater intrusion by the eastern WDP is smaller in the NC,and larger in the NP and the SP.The tidally averaged surface salinity at the water intakes of the Dongfengxisha Reservoir,the Chenhang Reservoir and the Qingcaosha Reservoir rises both during the spring and neap tides. 相似文献
992.
从地球重力场测量要素出发,按照局部重力场模型、区域重力场模型、全球重力场模型求解的发展思路,分析了对地球重力场测量技术手段的要求。根据高-低卫星跟踪卫星的距离和距离变率开展定轨研究的概念,梳理了卫星跟踪卫星重力测量系统的发展。针对卫星跟踪卫星重力测量技术的内涵,分析了高-低卫星跟踪卫星测量模式(SST-hl)和高-低低卫星跟踪卫星测量模式(SST—hll)的地球重力场测量本质。 相似文献
993.
The seismic capacity of beam‐to‐column connections in steel high‐rise frames is a matter of concern, particularly when they are subjected to long‐period ground motions. A previous full‐scale shaking table test conducted at the E‐Defense National Research Institute for Earth Science and Disaster Prevention in Japan disclosed cracks and fractures in such beam‐to‐column connections. This paper examines the effects of three types of beam‐to‐column connection retrofit: supplemental welds, wing plates, and a haunch. Quasi‐static member tests and a series of shaking table tests applied to a full‐scale specimen are conducted to quantify the respective performances of the retrofit schemes. The performance of a total of 28 connections tested by the member and shaking table tests is evaluated together with that of an additional 12 unretrofitted connections tested in the previous test. When the supplemental welds are applied only to the shear tab to the web, the connection fractures at the same instant as the connection without retrofit. The corresponding cumulative plastic rotation is not improved. When the supplement welds are further applied to the web‐to‐column connection, strain concentration at the bottom flange, primarily promoted by the presence of the RC floor slab, is significantly reduced, and the cumulative plastic rotation capacity is increased to eight times that of the connection without retrofit. For the wing plate connection and haunch connection, the critical section is moved from the beam end to the beam cross‐section corresponding to the tip of the wing plates or haunch, resulting in an improvement of ductility by eight times that of the unretrofitted connection. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
994.
995.
主题性旅游协作联盟及其构建——以运河文化主题协作联盟为例 总被引:5,自引:1,他引:4
主题性旅游协作联盟是一种新型的旅游合作战略模式,其协作基础为相似的空间认知要素、现代化的信息技术支撑和物态化的整合营销品牌。在分析国内外20多个旅游协作联盟的基础上,从地域联系、主题类型、空间结构和组织形式等4个视角,总结了主题性旅游协作联盟的12种基本类型,指出协作的基础理论是注意力经济学、协作网络共生理论和旅游产业集群理论。选取江苏扬州至山东济宁段运河为研究区域,分析其文化资源和旅游发展状况,提出"千年运河,世纪风情"的运河文化主题,从组织体系、品牌营销、产品体系、保障机制、信息平台等5个方面进行主题性旅游协作联盟的构建。 相似文献
996.
澜沧江流域退耕还林农户土地利用变化及其原因分析——以云县晓街乡为例 总被引:2,自引:1,他引:1
从退耕还林工程的实施将改变云南省生态环境的大背景出发,采用对比研究的方法对澜沧江流域退耕还林前后农户对土地资源的利用方式、利用强度及空间分布3个方面进行定性研究,探讨了退耕还林工程对项目区土地利用的影响,并得出如下结论:(1)退耕后农户对土地资源的利用变得更为复杂,主要表现在:土地利用面积增减、利用类型变更、空间分布变化及土地利用组合方式变化;(2)退耕还林工程如果只是将当地原有的生产、生活体系打破而又没有建立起合适的替代体系的话,其综合效益的发挥将受到严重影响。建议提高农户对土地资源的利用效率是当前切实发挥和巩固退耕还林工程综合效益的关键;减少农户生产、生活对土地的依赖才是长远之策。 相似文献
997.
改革开放以来,内蒙古经济获得快速发展,取得可喜成就。但是.各地区的经济发展非常不平衡,地区经济差距显著。本文首先揭示了地区经济差距的现状,然后详细地分析各地区对外开放的差异及对地区经济的影响,并运用数学的回归分析法,进行了相关性分析,结果显示二者之间呈现密切的相关关系。 相似文献
998.
Mapping spectral tropicality in The Maid and Return to Pontianak 总被引:1,自引:1,他引:0
Sophia Siddique Harvey 《Singapore journal of tropical geography》2008,29(1):24-33
Contemporary, postcolonial Singapore has tamed, managed, and essentially disavowed its tropicality, aptly captured symbolically as the 'air-conditioned nation'. This essay traces how two recent Singapore horror films, The Maid (2005) and Return to Pontianak (2001), evoke the 'return of the repressed' as a form of haunting that I call 'spectral tropicality'. The films image and imagine this spectral return through unruly bodies (citizen subjects, female domestic workers, ghosts and vampire-ghosts) and uncanny landscapes (the jungle and city). In particular, the films and this analysis examine two sociocultural spectres lurking beneath Singapore as a tropical urban city-nation: the female domestic worker ( The Maid ) and ethnoracial folk beliefs ( The Maid and Return to Pontianak ). The Maid features the Hungry Ghosts Festival in the Chinese religious calendar, ghost marriages and an engagement with yin and yang energies, while Return to Pontianak deals with Malay folk beliefs of semangat ('life force'), and the pontianak, a female vampire-ghost. The Maid attempts to integrate Chinese folk beliefs into contemporary Singapore's cityscape, particularly the architecturally conserved Chinatown shophouses, while Return to Pontianak displaces Malay folk beliefs onto the tropical forest, which is mapped as a threatening other(ed) space and serves as Singapore's tropical doppelganger. Both films suggest that these folk beliefs have an unruly presence within the state's seemingly harmonious and meritocratic ethnoracial ideologies. 相似文献
999.
Joseph E. Mbaiwa Barbara N. Ngwenya Donald L. Kgathi 《Singapore journal of tropical geography》2008,29(2):155-172
This paper reviews how state policy and regulatory instruments, including protected area alienations and concessions, have altered or denied the access to land and natural livelihood resources of the indigenous Basarwa and minority subsistence-oriented communities in the Okavango Delta (OD) in Botswana. Drawing on field research and guided by a sustainable rural livelihoods framework, the paper provides an overview of key institutional interventions – in particular the setting up of the Moremi Game Reserve, Wildlife Conservation Policy, Tourism Policy, Agricultural Development Policy and the erection of veterinary fences – that have served to privilege a foreign-owned and dominated commercialized wildlife and nature tourism sector and the export-oriented beef industry in the OD. The officially sanctioned barriers to customary and usufructory rights and access, and the non-recognition of historically embedded traditional land uses have decimated already marginalized resource-based subsistence livelihoods, and precipitated intergroup conflicts over preferential rights and access to resources and opportunities, notably wildlife, non-timber veld products, agriculture and community-based tourism schemes. Such outcomes, moreover, will have consequences for the longer-term sustainability of the OD both as a socioeconomic resource base and as a natural ecosystem. 相似文献
1000.
提取精密控制震源信号的自适应加权匹配滤波方法 总被引:1,自引:0,他引:1
为克服短时突发噪声对提取精密控制震源信号的影响, 本文研究并提出了加权匹配滤波方法。 通过评估记录中的噪声时间分布取得相对应的信号段的权重, 对噪声水平高的时段分配较小的权重, 噪声水平较低的时段分配较大的权重, 进行加权匹配滤波, 达到降低短时突发噪声的影响、 有效提高输出信号信噪比的目的。 相似文献