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A half-space containing horizontally multilayered regions of different transversely isotropic elastic materials as well as a homogeneous half-space as the lowest layer is considered such that the axes of material symmetries of different layers and the lowest half-space to be as depth-wise. A rigid circular disc rested on the free surface of the whole half-space is considered to be under a forced either vertical or horizontal vibration of constant amplitudes. Because of the involved integral transforms, the mixed boundary value problems due to mixed condition at the surface of the half-space are changed to some dual integral equations, which are reduced to Fredholm integral equations of second kind. With the help of contour integration, the governing Fredholm integral equations are numerically solved. Some numerical evaluations are given for different combinations of transversely isotropic layers to show the effect of degree of anisotropy of different layers on the response of the inhomogeneous half-space. 相似文献
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本文基于动力调整方法,利用客观分析海气通量（OAFlux）资料研究了1958～2016年全球海洋蒸发量变化及其动力作用和辐射强迫分量的变化,发现海洋蒸发量及其动力作用分量具有一致性年代际变化特征,特别是在20世纪70年代及90年代末期存在明显的年代际转折。进一步分析发现:主要动力因子有太平洋—北美遥相关型（PNA）、北极涛动（AO）、北大西洋涛动（NAO）、厄尔尼诺—南方涛动（ENSO）和阿留申低压（AL）,并受到太平洋年代际振荡（PDO）的影响,其中,1970年代末期的转折与PNA、PDO、ENSO和AL密切相关,而1990年代末期的转折还与NAO变化有关。动力作用分量的前六个模态解释方差达到67.5%,其中,低纬北太平洋和印度洋蒸发异常主要与海表温度（SST）及其引起的环流异常有关,南太平洋、中纬北太平洋和北大西洋蒸发异常与环流异常直接相关。ENSO与PDO在全球海洋蒸发量上的影响要大于NAO。单因子相关分析发现南方涛动指数（SOI）、NAO和PDO与海洋蒸发年代际变化密切相关。总体来说,动力作用分量在海洋蒸发的年代际变化中起主导作用,其中,以ENSO、NAO和PDO的影响最大。 相似文献
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对FY-3A气象卫星大气温度湿度廓线资料进行夜间大雾低能见度分布反演计算,并运用美国LAPS(Local Analysis and Prediction System)局地分析与预报系统,与FNL再分析资料多要素反演数据进行多源要素融合分析。FY-3A卫星反演得到的大雾低能见度分布,经与Micaps(Meteorological Information Comprehensive Analysis and Process System)系统地面天气图, FY-2E地球同步卫星红外云图,要素统计气象年鉴记录等对比检验,显示反演的低能见度区范围及强度合理。尤其是对海上缺乏常规观测资料网的海域,提供了夜间海上能见度分布信息。进一步地通过LAPS系统对比卫星资料、再分析资料、以及卫星与再分析资料融合的3种方案结果,显示将卫星监测资料与FNL再分析资料的融合效果,对单来源资料反演的大雾低能见度分布有较好的改善。融合后对卫星资料而言,卫星轨道盲区已经弥合,其次,获得了海上低能见度区分布的信息,对海上和沿海雾区能见度的强度得到合理改善。对于FNL再分析资料,原有的各项要素强梯度被合理平滑。低能见度范围也有调整改善。重要的是海上大雾低能见度区的分布,得到FY-3A卫星信息和数值模拟信息的互相验证与信息综合,可信度增强。 相似文献
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Zhang Shiqing 《Celestial Mechanics and Dynamical Astronomy》2004,89(2):141-144
For planar Newtonian 8-body problems with equal masses, we prove the existence of the new non-collision periodic solution
such that two pair bodies move clockwise and the other two pairs counter-clockwise.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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For Newtonian 3-body problems in ℝ2, we prove the existence of new symmetric noncollision periodic solutions with some fixed winding numbers and masses. 相似文献
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The daily maximum/minimum temperature data at 740 stations in China from 1960 to 2005 were ana-lyzed to reveal the statistical characteristics of record-breaking（RB）daily extreme temperature events in the past 46 yr.It is verified that the observational daily extreme temperatures obey the Gaussian distribution. The expected values of RB extreme temperatures were obtained based on both the Gaussian distribution model and the initial condition of observed historical RB high/low temperature events after tedious the-oretical derivation.The results were then compared with those obtained by the iteration computation of the pure theoretical model.The comparison suggests that the results from the former are more consistent with the observations than those from the latter.Based on the above analyses,prediction of future possible RB high/low temperature events is made,and the spatial distributions of maximum/minimum theoretical values of their intensities are also given.It is indicated that the change amplitudes of future extreme temperatures differ evidently from place to place,showing a remarkable regional feature：the future extremely high temperature events will have a strong rising intensity in Southwest China,and a relatively weak rising intensity in western China;while the largest decrease of the future extremely low temperature events will appear in Northeast China and the north of Northwest China,and the decrease will be maintained relatively stable in space in Central China and Southwest China,in comparison with the historical low temperature pattern.Features in the occurrence time of the future RB temperature events are also illustrated. 相似文献
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《Progress in Oceanography》2007,72(2-3):151-163
Information on the metabolism rates of Centropages typicus and congeneric species (C. hamatus, C. furcatus, C. brachiatus and C. abdominalis) in neritic areas of the Mediterranean Sea, the North Atlantic Ocean and the Pacific Ocean are reported here. Respiration rates and excretion rates are strongly influenced by abiotic (i.e. temperature, salinity) and biotic factors (i.e. food availability and composition). Differences in the response of respiratory rates to temperature of acclimated, acclimatized and adapted individuals are clearly observed among regions of the Mediterranean Sea and the West and East shores of the Atlantic Ocean. Food supply also strongly affects respiration and excretion rates, as well as the size, sex and stage development of the individuals. The co-measurement of these two rates allows confirmation of the omnivory or carnivory oriented feeding habits of these species. The role of this neritic genus in coastal environment is also discussed. 相似文献
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《Atmospheric Research》2010,95(4):694-703
The German Weather Service (DWD) has two non-hydrostatic operational weather prediction models with different spatial resolution and precipitation parametrisations. The coarser COSMO-EU model has a spatial resolution of 7 km, whereas the higher-resolution COSMO-DE model has a gridspace of 2.8 km and explicitly resolves deep convection. To improve the numerical weather prediction (NWP) models it is necessary to understand precipitation processes. A central goal is the statistical evaluation of precipitation forecasts with dynamic parameters. Here, the Dynamic State Index (DSI) is used as a dynamic threshold parameter. The DSI theoretically describes the change of atmospheric flow fields as deviations from a stationary adiabatic solution of the primitive equations (Névir, 2004). For seasonal area means the DSI shows a remarkably high correlation with the precipitation forecasts provided by the COSMO-DE model. This is especially the case for the summer of 2007. The same analysis has been performed with the COSMO-EU forecast data and the results were compared with those from the COSMO-DE model. Moreover, an independent precipitation analysis, with a resolution corresponding to 7 km and 2.8 km, has been compared with respect to modelled precipitation and the DSI. In addition, correlations between the DSI and modelled as well as observed precipitation as a function of the forecast time for the different grid resolutions are also presented. The results show, that after 12 h, the correlation of the persistence forecast with the DSI reaches two thirds of the initial value. Thus, the DSI offers itself as a new dynamic forecast tool for precipitation events. 相似文献