排序方式: 共有13条查询结果,搜索用时 31 毫秒
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对ZZ580-LH-340型水轮机顶盖结构在两种工况下的应力分布和轴向变形进行分析,建立了优化设计模型并得出优化结果。 相似文献
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Precursory SST anomalies associated with the convection over the western Pacific warm pool 总被引:3,自引:0,他引:3
Riyu Lu 《科学通报(英文版)》2002,47(8):696-699
The convection over the tropical western Pacific warm pool influences significantly the atmospheric circulation and climate
in East Asia. Thus, the precursory signals of the convection may be used in the forecast of summer climate in China. According
to the present results, the June-July-August (JJA) mean convection intensity over the warm pool is significantly related to
the precursory positive and negative sea surface temperatures (SSTs) in the warm pool and in the equatorial central and eastern
Pacific, respectively. It is also related to the simultaneous negative surface temperatures west to the Philippines. The analysis
on the SSTs associated with the convection over the warm pool in individual month of summer shows that for the convection
in June and July, there are precursory SST signals in the warm pool and the equatorial central and eastern Pacific. Therefore,
this study shows that only the convection in June and July, rather than that in August, has precursory SST signals, despite
the existence of the precursory signals of the JJA mean convection. Accordingly, it is implied that the interaction among
the warm pool, equatorial central and eastern Pacific, and the region west to the Philippines may exhibit distinct features
in the precursory period (preceding winter and spring) and in the simultaneous period. 相似文献
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针对三支点双悬臂、三支点单悬臂及二支点双悬臂水轮机主轴,分别建立了相应的有限元振动分析模型,导出了相应的振动分析方程,并采用逆迭代法求解主轴的第一阶自振频率。本方法已在计算机上实现。计算结果表明,本文方法精度高,程序运行可靠。 相似文献
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Interannual variation of North China rainfall in rainy season and SSTs in the equatorial eastern Pacific 总被引:4,自引:2,他引:4
LU Riyu 《科学通报(英文版)》2005,50(18):2069-2073
The rainfall in North China during rainy season (July and August (JA)) exhibits a strong interannual variability. In this study, the atmospheric circulation and SST anomalies associated with the interannual variation of JA North China rainfall are examined. It is found that on the interannual timescale, the JA North China rainfall is associated with significant SST anomalies in the equatorial eastern Pacific, and the North China rainfall and SST anomaly in the equatorial eastern Pacific correspond to the similar variation of the upper-level westerly jet stream over East Asia. A possible mechanism is proposed for the influence of the SST anomalies in the equatorial eastern Pacific on the North China rainfall. 相似文献
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Linear relationship between the interdecadal and interannual variabilities of North China rainfall in rainy season 总被引:9,自引:2,他引:7
LURiyu 《科学通报(英文版)》2003,48(10):1040-1044
Interdecadai and interannuai timescales are dominant in the North China rainfall in rainy season (July and August). On the interdecadai timescale, the North China rainfall exhibited an abrupt decrease at the end of 1970s. In this study, we examined the effect of this abrupt rainfall decrease on the association between rainfall and circulation on the interannuai timescale, and found that the interdecadal variation does not change the physical mechanism responsible for the interannuai variation of North China rainfall.There is a linear relationship between the interdecadai and interannuai variabilities of North China rainfall in rainy season. 相似文献
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The zonal displacement of the western Pacific subtropical high remarkably influences the climate anomalies in China. In this paper, a new zonal index of the subtropical high is defined by modifying previous indices, and is used to investigate the relationship between the zonal displacement of the subtropical high and the dominant modes of 850-hPa circulations. It is found that the zonal displacement of the subtropical high is significantly correlated with the first two leading modes of circulations. In particular, the correlation coefficient between the index and the time series associated with the second mode is as high as 0.78 in 1958-2003 (46 years). Since the second mode is not associated with significant anomalies of sea surface temperatures, the above results imply the difficulty in seasonal forecasting of the zonal displacement of the subtropical high. In addition, the interannual variability in the zonal displacement of the subtropical high has been considerably enhanced since 1978, due to the effects of both dominant modes, especially the second mode. This is likely to account for the frequent occurrence of anomalous climate in China during the recent two decades. 相似文献