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991.
河口大型滩涂演化关系到航运通畅、生态保护以及近岸工程的安全性,也是地貌学和工程界关注的热点。本文选择横沙东滩围垦区前沿5 m等深线包络区域作为研究区,2011–2017年间利用单波束测深系统对研究区进行持续性高精度监测,并结合近年来流域来沙、河口工程的建设和极端气候变化等影响因素分析其冲淤格局。结果表明:(1)近年来横沙东滩基本呈中间淤涨、周围冲刷的态势,整体由工程前“长大不长高”转化为工程后的“长高不长大”的演化格局;(2)海域来沙是此区域淤积的主要物源,研究区两侧涨落潮流路分异引起的环流是导致此区域淤积的主要动力;(3)深水航道堤坝工程、横沙东滩围垦工程等是导致研究区中间淤涨的原因;(4)人类活动可以直接影响滩槽的演化格局,工程建设的固定制约了河槽和滩涂的摆动,但也加剧了研究区局部的冲刷,未来应注意其内部串沟的发展,防止其连通威胁堤坝和滩涂的稳定。 相似文献
992.
Spatial interaction and network structure evolvement of cities in terms of China’s rail passenger flows 总被引:3,自引:1,他引:3
Cities separated in space are connected together by spatial interaction (SI) between them. But the studies focusing on the SI are relatively few in China mainly because of the scarcity of data. This paper deals with the SI in terms of rail passenger flows, which is an important aspect of the network structure of urban agglomeration. By using a data set consisting of rail O-D (origin-destination) passenger flows among nearly 200 cities, inter-city rail distance O-D matrixes, and some other indices, it is found that the attenuating tendency of rail passenger is obvious. And by the analysis on dominant flows and spatial structure of flows, we find that passenger flows have a trend of polarizing to hubs while the linkages between hubs upgrade. However, the gravity model reveals an overall picture of convergence process over time which is not in our expectation of integration process in the framework of globalization and eco- nomic integration. Some driven factors for the re-organization process of the structure of urban agglomeration, such as technique advance, globalization, etc. are discussed further based on the results we obtained. 相似文献
993.
数据库中间件技术探讨 总被引:1,自引:1,他引:1
描述了数据库中间件技术的来源、工作原理以及主要功能,着重探讨了当前主要的数据库中间件技术:ODBC、OLEDB、JDBC、ADO、ADO NET的体系结构、原理以及运作情况,并比较了它们之间的不同。 相似文献
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995.
永登5.8级地震和天祝—古浪5.4级地震前S波分裂特征 总被引:1,自引:0,他引:1
应用CDSN台网兰州数字台的记录和中法合作建立的朗索数字台的记录,研究了1995年7月22日甘肃永登5.8级地震和1996年6月1日天祝-古浪5.4级地震前台剪切波分裂的特征。结果表明,在永登地震前大约1年的时间延迟和偏振方向很快恢复。因此,可以认为,此次地震前NW向,地震后剪切波分裂时间延迟和偏振方向很快恢复。因此,可以认为,此次地震前S波分裂方向的前兆特征是明显的。对于天祝-古浪5.4级地震, 相似文献
996.
江汉盆地印支期以来区域构造特征探讨 总被引:21,自引:1,他引:21
印支期以来,江汉盆地在特定的大地构造背景、特殊的边界条件等内外因素制约下,形成了多种特定的构造型式,如挤压、推覆条件下的大型褶皱、逆冲推覆;引张条件下的断块,以及构造叠加复合条件下的时间、空间域的转换构造等,同时还有对前印支期构造的明显改造。 相似文献
997.
C. Dai X. H. Cai Y. P. Cai Q. Huo Y. Lv G. H. Huang 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(2):167-187
In this research, approaches of interval mathematical programming, two-stage stochastic programming and conditional value-at-risk (CVaR) are incorporated within a general modeling framework, leading to an interval-parameter mean-CVaR two-stage stochastic programming (IMTSP). The developed method has several advantages: (i) it can be used to deal with uncertainties presented as interval numbers and probability distributions, (ii) its objective function simultaneously takes expected cost and system risk into consideration, thus, it is useful for helping decision makers analyze the trade-offs between cost and risk, and (iii) it can be used for supporting quantitatively evaluating the right tail of distributions of waste generation rate, which can better quantify the system risk. The IMTSP model is applied to the long-term planning of municipal solid waste management system in the City of Regina, Canada. The results indicate that IMTSP performs better in its capability of generating a series of waste management patterns under different risk-aversion levels, and also providing supports for decision makers in identifying desired waste flow strategies, considering balance between system economy and environmental quality. 相似文献
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1000.
S.-B. Qian L.-Y. Zhu L. Liu Z.-B. Dai J.-J. He W.-P. Liao E.-G. Zhao S. Zola E. Kuligowska M. Winiarski 《Astrophysics and Space Science》2010,328(1-2):113-117
Analysis of over 15 years of V-band and Wing three filter near-IR photometry of the bright M5Ib-II supergiant has been carried out. Wavelet analysis of these data reveals that the star pulsates with several complicated oscillation modes. Different time scales of variability are identified, and with the aid of discrete Fourier analysis, depending on the filter, up to seven significant pulsation modes are identified and their frequencies and amplitudes extracted. The Long Secondary Period (LSP) with a mean period of ~1343 d has been identified, as well as other periods of the order of ~125 d. The longer period appears to be attributed to the radial pulsational mode, while the various peaks near ~125 d appear to arise from stochastically excited p-modes. After removing the light contribution of the 5th magnitude binary companion and calibrating the intermediate-band photometry to the Wing photometric system, TiO (719 nm) and near-IR (B-C) Wing color indices were formed. These indices have been calibrated with T eff, while the Wing-C bandpass (1025 nm) serves as a proxy for bolometric magnitude and was transformed to approximate m bol. Finally, the derivation of the variations in the star’s temperature, luminosity and radius is straightforward. 相似文献