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941.
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以国家气象中心T42产品资料作为环境的初始场,采用P-σ混合坐标的有限区域细网格模式,对9406号台风暴雨过程进行24、48小时数值预报模拟试验并取得较好效果。 相似文献
943.
A study on quality of aquatic environment in Tumen River Area 总被引:3,自引:0,他引:3
ASTUDYONQUALITYOFAQUATICENVIRONMENTINTUMENRIVERAREA①ZhuYanming(朱颜明)ChangchunInstituteofGeography,theChineseAcademyofSciences,... 相似文献
944.
旅游产品及其市场营销的若干问题 总被引:12,自引:1,他引:11
提出了旅游资源与旅游产品的概念,阐述了与分析了旅游产品的特性、整体旅游产品的三个层次、旅游产品的价值与定价原则、旅游产品的促销等问题。 相似文献
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Earthquake safety assessment of concrete arch and gravity dams 总被引:9,自引:1,他引:8
Based on research studies currently being carried out at Dalian University of Technology, some important aspects for the earthquake safety assessment of concrete dams are reviewed and discussed. First, the rate-dependent behavior of concrete subjected to earthquake loading is examined, emphasizing the properties of concrete under cyclic and biaxial loading conditions. Second, a modified four-parameter Hsieh-Ting-Chen viscoplastic consistency model is developed to simulate the rate-dependent behavior of concrete. The earthquake response of a 278m high arch dam is analyzed, and the results show that the strain-rate effects become noticeable in the inelastic range. Third, a more accurate non-smooth Newton algorithm for the solution of three-dimensional frictional contact problems is developed to study the joint opening effects of arch dams during strong earthquakes. Such effects on two nearly 300m high arch dams have been studied. It was found that the canyon shape has great influence on the magnitude and distribution of the joint opening along the dam axis. Fourth, the scaled boundary finite element method presented by Song and Wolf is employed to study the dam-reservoir-foundation interaction effects of concrete dams. Particular emphases were placed on the variation of foundation stiffness and the anisotropic behavior of the foundation material on the dynamic response of concrete dams. Finally, nonlinear modeling of concrete to study the damage evolution of concrete dams during strong earthquakes is discussed. An elastic-damage mechanics approach for damage prediction of concrete gravity dams is described as an example. These findings are helpful in understanding the dynamic behavior of concrete dams and promoting the improvement of seismic safety assessment methods. 相似文献
947.
Zhang Ji-shi Zhang Yong-qiu Pu Rui-feng Chen Ren-sheng Cheng Zhong-shan Wang Ming-quan 《中国地理科学(英文版)》2005,15(3):238-244
The research on the present situation of soil and water development and utilization in Shiyang River Basin shows that water
resources and eco-environment situation in this area are near the edge of collapse. Since the water crises occurred in the
1970s, problems caused by continuous decrease of water resources have been becoming serious year by year and eco-environment
crisis occurred as a consequence. Up to now, 10 380ha of irrigated lands have been abandoned due to sand coverage and water
shortage in the basin. Ground water was over exploded in Wuwei and Minqin because of water shortage. Ground water table in
many places dropped under 5m (which is the ecology water table level), thus about 3000ha of Elaeagnus angustifolia forest come to dead and another 5800ha become feeble, and wind-drift sand near the oasis become alive. According to the current
situation, if water utilization scope was not enlarged, a water transfer volume of 600×106m3/a from other areas will be suitable to keep water resources and eco-environment safety in the basin, and also 70×106m3/a will be left as spare water. Under this condition the water resources and eco-environment of the basin can reach the critical
safety line of 2.032×109m3/a; or if 180×106m3 of water can be transferred from other areas, the water resources can reach the safety warning line of 1.732×109m3/a.
Foundation item: Under the auspices of the National Natural Science Foundation of China (No. 40235053) and Lanzhou Jiaotong
University "Qinglan" Foundation
Biography: ZHANG Ji-shi (1963-), male, a native of Tongwei of Gansu Province, senior engineer, specialized in water resources
and climate change in Northwest China. E-mail: zjs1963@yahoo.com.cn; hangjs@mail.lzjtu.cn 相似文献
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