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461.
厄尔尼诺和反厄尔尼诺事件与西北太平洋台风活动 总被引:42,自引:12,他引:42
用统计相关和典型年合成方法分析了厄尔尼诺和反厄尔尼诺事件与西北太平洋台风活动的关系,指出厄尔尼诺年台风活动减少,反厄尔尼诺年台风活动增加,而且台风活动与厄尔尼诺、反厄尔尼诺事件起始和终止时间、强度、台风生成区域有关。利用厄尔尼诺和反厄尔尼诺年台风活动频数的统计特征,及台风频数与海温等要素的时滞相关关系,为台风频数的预测提供了有益的信息。还应用奇异值分解方法,分析了高度场和海温场的相关关系。结果表明,厄尔尼诺年海气耦合作用将造成不利于台风发展的环流条件,因此台风偏少,反厄尔尼诺年则出现相反的情况。 相似文献
462.
To study the application of the TOPMODEL and the Xin’anjiang model to rainfall runoff simulation in semi-humid regions, the Holtan excess infiltration runoff module was added to the TOPMODEL structure. The basin of the Heihe Jinpen Reservoir in Shaanxi Province, China, was selected as the study area. Rainfall and runoff data and digital elevation models were collected. The watershed topographic parameters and 21 floods that occurred from 2005 to 2013 were obtained to simulate rainfall runoff. Results show that the improved TOPMODEL and the Xin’anjiang model can effectively stimulate rainfall runoff. The average values of their Nash coefficient are 0.84 and 0.83, respectively, upon calibration, and 0.78 and 0.80, respectively, upon validation. The Xin’anjiang model performs slightly better than the improved TOPMODEL. The results of large flood peaks are better than those of ordinary floods. Both results can be used to simulate the rainfall runoff of a watershed. 相似文献
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基于压缩感知稀疏信号采样与重构理论,利用AVO反演方法将传统的L2范数改变为L1范数,反演地下地层在L1范数下的稀疏脉冲反射系数。反演得到的稀疏尖峰将局部地下结构通过有限数量的层状结构的叠加来表示,能够提高纵向精度,与传统的AVO反演算法相比提高了薄层的反演效果且具有一定的抗噪性。数值模型及实际数据的结果表明,基于压缩感知原理的L1范数AVO反演方法更加准确、分辨率更高。 相似文献
465.
INTR0DUCnONErhailake,thesecondlargestlakeintheYUnnanPlateauinS0uthWstChina,islo-catedinDaliDefecthe25035'to25"58'N,looo05't0l(X)o07'E(Fig.l)-The40kInlong3-9kInwidelakeisnaInedafteritsearlikeshape.ItsbasicchimteristicsaregiveninTablel.EtheibeeisampicalriftlakeintheDalibasinwhichdeveloPedalongtheYuaniangHongheThewestsideofthebasinisformedbytheDiancangMountainwhichconsists0frock(PrecaInbrianschistandgneissandMiocenemetaInrphiclimestone).TheseisndcallystillactivemoUntainrangrisab0ut… 相似文献
466.
Do collective behaviors of the daily routine of a city's inhabitants form the periodical cycling of human activity at the city level (here termed the “city's diurnal rhythm”)? If the answer is yes, do there exist geographical patterns in the city's diurnal rhythm? Using a nationwide dataset of observed uses of location‐aware services in the largest Chinese social media platform, we first confirm the significant periodicity in city‐level human activity from the perspective of the aggregate degree of social media uses over a day. We then investigate geographical changes in the diurnal rhythm of human activity and its local variations in different parts of the city, and between weekdays and weekend days, over 340 Chinese cities. Our results show that a city's diurnal rhythm across the whole country exhibits both regular, nationally conspicuous shifts along geographical gradients and locally distinct spatiotemporal changes within the city. Our findings could provide insights into the characterization of the daily routine of city‐level human activity and its geographical patterns, and have potential for several issues in terms of planning, management, and decision‐making related to human population dynamics. 相似文献
467.
Song Weibo 《海洋学报(英文版)》1996,15(1):93-99
MorphogeneticstudiesonUronychiauncinata(Protozoa,Ciliophora)duringitsasexualdivision¥SongWeibo(ReceivedAugust28,1995;accepted... 相似文献
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Bivariate Gaussian mixture–based equivalent linearization method for stochastic seismic analysis of nonlinear structures 下载免费PDF全文
To address challenges in stochastic seismic analysis of nonlinear structures, this paper further develops a recently proposed Gaussian mixture–based equivalent linearization method (GM‐ELM). The GM‐ELM uses a Gaussian mixture distribution model to approximate the probabilistic distribution of a nonlinear system response. Using properties of the Gaussian mixture model, GM‐ELM can decompose the non‐Gaussian response of a nonlinear system into multiple Gaussian responses of linear single–degree of freedom oscillators. With the set of the equivalent linear systems identified by GM‐ELM, response statistics as crossing rate and first‐passage probability can be computed conveniently using theories of linear random vibration analysis. However, the original version of GM‐ELM may lead to an inaccurate estimate because of the heuristic parameters of the linear system introduced to supplement insufficient information. To overcome this limitation and define unique equivalent linear systems, this paper proposes a further developed version of GM‐ELM, which uses a mixture of bivariate Gaussian densities instead of univariate models. Moreover, to facilitate the use of elastic response spectra for estimating the mean peak responses of a nonlinear structure, a new response spectrum combination rule is proposed for GM‐ELM. Two numerical examples of hysteretic structural systems are presented in this paper to illustrate the application of the bivariate GM‐ELM to nonlinear stochastic seismic analysis. The analysis results obtained by the bivariate GM‐ELM are compared with those obtained by the univariate GM‐ELM, the conventional equivalent linearization method, the tail equivalent linearization method, and Monte Carlo simulation. The supporting source code and data are available for download at https://github.com/yisangri/GitHub‐bGM‐ELM‐code.git 相似文献
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