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张俊  独知行  杜宁  张显云 《大地测量与地球动力学》2015,35(1):122-125

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The Asymmetry of Subsurface Temperature Anomalies Associated with ENSO in the Equatorial Western Pacific          下载免费PDF全文

HUA Li-Juan  YU Yong-Qiang 《大气和海洋科学快报》2015,8(1):23-28

The phenomenon of ENSO asymmetry has been recognized for many years, but most studies have focused on the asymmetry of surface temperature anomalies in the equatorial eastern Pacific. Here, the authors investigate the temperature asymmetry associated with ENSO in the subsurface of the western Pacific through analysis of observations and numerical experiments with an ocean GCM. Both the observation and simulation exhibit significant ENSO asymmetry, characterized by negative temperature skewness in the equatorial western Pacific and positive skewness in the eastern Pacific. Heat budget analysis reveals that nonlinear dynamical heating results in the positive temperature asymmetry in the equatorial eastern Pacific, but tends to weaken the negative temperature asymmetry in the equatorial western Pacific. The climatological meridional current transports the temperature anomalies and corresponding negative asymmetry from the off-equator region to the equator in the subsurface of the western Pacific. Through a sensitivity experiment with reversed wind stress forcing, the authors suggest that the skewness of the wind stress anomalies does not contribute to the negative temperature asymmetry in the western Pacific in the first-order approximation, while the internal nonlinear dynamics does play a key role. The study suggests that, as a result of nonlinear processes, the oceanic responses to anomalous wind stress are nonlinear and asymmetric in the tropical Pacific.  相似文献   

基于半数值方法的限弯器剪弯刚度分析     

丁乐声  陈金龙  陈潇  郭豪  张聪 《海洋工程》2022,40(6):152-159

柔性管缆限弯器存在接触非线性导致剪弯刚度分析困难。为此先基于悬臂梁方程建立剪弯刚度理论模型;然后构建考虑接触边界的锁合结构数值模型,得到其扭转刚度曲线;最后结合理论分析和数值计算求得考虑接触非线性的限弯器剪弯刚度曲线,并同传统的整体数值方法相比较,验证该半数值分析方法的有效性。对比发现基于半数值方法的限弯器剪弯计算效率远高于传统数值方法,其结果误差也满足工程需求;并且限弯器锁合结构处受接触边界影响有明显的非线性;限弯器子梁这一短梁结构基于Timoshenko梁理论计算的结果精度更高也更保守。相较于传统数值方法,该半数值方法用方程直接表达部分参数与剪弯刚度关系,并可以高效地分析限弯器剪弯刚度,使设计工作更加高效。  相似文献   

热源强迫的非线性惯性重力内波及其应用     

吴俞  李国平 《成都信息工程学院学报》2006,21(Z1):7-11

利用动力学分析中的相平面方法,由z坐标系下的非绝热大气运动方程组导出了与非线性惯性重力内波有关的KdV方程,然后利用直接积分法得到两类有天气意义的孤立波解.初步建立了孤立波解与高原低涡的联系,进一步从理论上论证了高原低涡具有与热带气旋类低涡类似的涡眼和暖心结构的特征.  相似文献   

淮河流域水文非线性多水源时变增益模型研究与应用          下载免费PDF全文

万蕙  夏军  张利平  宋霁云  佘敦先 《水文》2015,35(3):14-19

基于传统时变增益模型(TVGM),进一步考虑地下径流退水,在传统TVGM只考虑单一地表水源的基础上,添加地下水源模块,对地表地下径流分别进行产、汇流计算,改进并提出了多水源TVGM,并将其应用于淮河流域蚌埠闸以上13个水文站控制的代表性子流域。结果表明:多水源TVGM既继承了传统TVGM以简单结构描述复杂水文非线性系统关系的优点,同时通过增加地下水源模块,大大提高了洪水预报的精度。13个子流域参数率定期和模型验证期中,传统TVGM分别有9个和7个子流域达到乙级洪水预报标准,而多水源TVGM分别提高到12个和8个,其中以大型流域和大水年改进效果尤佳。传统TVGM水量平衡系数为0.88,多水源TVGM提高到0.95,平均提高了7%。洪峰模拟相对误差也由传统TVGM的50%达标率提高到多水源TVGM的92.3%,整体提高了42.3%。因此,多水源TVGM能更好的应用于淮河流域洪水预报工作。  相似文献   

最小二乘法的改进算法辨识棱镜摄谱仪定标多项式     

王淑青  王慧  陈春雷 《广东海洋大学学报》2006,26(1):62-66

提出了采用最小二乘法的改进算法拟和一元非线性函数,并用该算法辨识棱镜摄谱仪的定标多项式,数值计算结果表明:采用改进的算法,非常显著地降低了求解定标多项式系数方程组的系数矩阵的条件数,定标多项式能更精确地反映谱平面坐标和谱线波长的定量关系。  相似文献   

Nonlinear Dynamic Response of HDRB and Hybrid HDRB-Friction Sliders Base Isolation Systems     

Franco?Braga  Marco?Faggella  Rosario?Gigliotti  Michelangelo?LaterzaEmail author 《Bulletin of Earthquake Engineering》2005,3(3):333-353

The isolation systems are usually made of rubber bearings that are sometimes coupled in hybrid combination with frictional devices; this is the case of an in-site experimental campaign, performed on a base isolated apartment building in Rapolla (south of Italy). Several dropout tests at initial displacements up to 17cm allowed to obtain in-site information on the true dynamic response of the isolation system (building and isolators). The tests carried out allow a comparison between the free vibration responses of a building, isolated by using a 28 HDRB isolation system only, or an HDRB-Friction Sliders Hybrid one. The paper highlights the main differences of the response in the superstructure (the structure over the isolation system) obtained by using only HDRB isolation system, or the Hybrid one (HDRB and Friction Sliders in parallel system). Analysis and comparisons of experimental data, show the influence of nonlinearities on structural higher modes amplification, especially observed by using the higher nonlinear Hybrid isolation system. Tests results confirm that, in the case of a regular superstructure, like the Rapolla building, the isolation system nonlinearities influence the structural response.  相似文献   

CO2 Flux Estimation by Different Regression Methods from an Alpine Meadow on the Qinghai-Tibetan Plateau     

JIANG Chunming  YU Guirui  CAO Guangmin  LI Yingnian  ZHANG Shichun  FANG Huajun 《大气科学进展》2010,27(6):1372-1379

CO2 efflux was estimated using different regression methods in static chamber observation from an alpine meadow on the Qinghai-Tibetan Plateau. The CO2 efflux showed a seasonal pattern, with the maximun flux occurring in the middle of July. The temperature sensitivity of CO2 efflux (Q10> was 3.9, which was at the high end of the range of global values. CO2 emissions calculated by linear and nonlinear regression were significantly different (p<0.05). Compared with the linear regression, CO2 emissions calculated by exponential regression and quadratic regression were 12.7% and 11.2% larger, respectively. However, there were no significant differences in temperature sensitivity values estimated by the three methods. In the entire growing season, the CO2 efflux estimated by linear regression may be underestimated by up to 25% compared to the real CO2 efflux. Consequently, great caution should be taken when using published flux data obtained by linear regression of static chamber observations to estimate the regional CO2 flux in alpine meadows on the Qinghai-Tibetan Plateau.  相似文献   

Sensitivity of Nonlinearity on the ENSO Cycle in a Simple Air-sea Coupled Model          下载免费PDF全文

LIN Wan-Tao 《大气和海洋科学快报》2009,2(1):1-6

In this paper,the influence of the El NioSouthern Oscillation (ENSO) cycle on the sensitivity of nonlinear factors in the numerical simulation is investigated by conducting numerical experiments in a simple air-sea coupled model for ENSO prediction.Two sets of experiments are conducted in which zonal nonlinear factors,meridional nonlinear factors,or both are incorporated into the governing equations for the atmosphere or ocean.The results suggest that the ENSO cycle is very sensitive to the nonlinear factor of the governing equation for the atmosphere or ocean.Thus,incorporating nonlinearity into air-sea coupled models is of exclusive importance for improving ENSO simulation.  相似文献   

Factors affecting site response to multi-directional earthquake loading     

J. Yang  X.R. Yan 《Engineering Geology》2009,107(3-4):77-87

This paper presents an investigation into various factors that may affect the ground response to multi-directional earthquake loading, focusing mainly on the behavior of vertical ground motion and its relation with the horizontal counterpart. The factors investigated herein include the intensity of input motion and the associated soil nonlinearity, the location of input motion (rock outcrop versus bedrock), the variation of water table, and the damping property of soil. Influence of these factors is studied on the characteristics of site amplification in both vertical and horizontal directions, the response spectra of vertical and horizontal ground surface motions, the spectral ratio between the two components (V/H) at the ground surface, and the distributions of stresses and strains in the ground. One of the main results is that varying water table can bring about a significant impact on vertical motion and the relationship between vertical and horizontal motions. The surface response spectral ratio (V/H) can largely exceed the rule-of-thumb value of 2/3 at low periods with lowering the water table, but does not appear to be substantially affected at long periods.  相似文献