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631.
在高精度建模方法越来越丰富的背景下,三维城市场景往往具有较大的场景规模和较高的复杂性,因此,当单台计算机难以满足实时绘制的需求时,多采用更加适合超高分辨率大屏幕显示的Sort-First方式进行并行绘制。针对现有研究性能量化分析的缺乏,及自适应负载平衡方法的缺陷,本文通过Sort-First并行绘制系统的加速比模型,分析绘制节点数、显示分辨率、网络传输速度、任务划分等因素对系统性能的影响,以及将绘制时间和传输时间的和作为反馈,对现有负载平衡策略进行了改进。本文给出了系统达到最高加速比,即负载完全均衡理想情况下的一个量化的必要条件。最后,基于Sort-First的并行绘制实验验证上述分析。实验结果表明:本文的改进加强了各节点的负载平衡性,在一定程度上提高了性能。 相似文献
632.
Impacts of the Lowest Model Level Height on Tropical Cyclone Intensity and Structure简 总被引:1,自引:0,他引:1
Variable thicknesses in the lowest half-ηmodel level (LML) are often used in atmospheric models to compute surface diagnostic fields such as surface latent and sensible heat fluxes.The effects of the LML on simulated tropical cyclone (TC)evolution were investigated in this study using the Weather Research and Forecasting (WRF) model.The results demonstrated notable influences of the LML on TC evolution when the LML was placed below 12 m.The TC intensification rate decreased progressively with a lowering of the LML,but its ultimate intensity change was relatively small.The maximum 10-m winds showed different behavior to minimum sea level pressure and azimuthally-averaged tangential winds,and thus the windpressure relationship was changed accordingly by varying the LML.The TC circulation was more contracted in association with a higher LML.Surface latent heat fluxes were enhanced greatly by elevating the LML,wherein the wind speed at the LML played a dominant role.The changes in the wind speed at the LML were dependent not only on their profile differences,but also the different heights they were taken from.Due to the enhanced surface heat fluxes,more intense latent heat release occurred in the eyewall,which boosted the storm's intensification.A higher LML tended to produce a stronger storm,and therefore the surface friction was reinforced,which in turn induced stronger boundary layer inflow together with increased diabatic heating. 相似文献
633.
Observed hiatus or accelerated warming phenomena are compared with numerical simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5) archives,and the associated physical mechanisms are explored based on the CMIP5 models.Decadal trends in total ocean heat content (OHC) are strongly constrained by net top-of-atmosphere (TOA) radiation.During hiatus decades,most CMIP5 models exhibit a significant decrease in the SST and upper OHC and a significant increase of heat penetrating into the subsurface or deep ocean,opposite to the accelerated warming decades.The shallow meridional overturning of the Pacific subtropical cell experiences a significant strengthening (slowdown) for the hiatus (accelerated warming) decades associated with the strengthened (weakened) trade winds over the tropical Pacific.Both surface heating and ocean dynamics contribute to the decadal changes in SST over the Indian Ocean,and the Indonesian Throughflow has a close relationship with the changes of subsurface temperature in the Indian Ocean.The Atlantic Meridional Overturing Circulation (Antarctic Bottom Water) tends to weaken (strengthen) during hiatus decades,opposite to the accelerated warming decades.In short,the results highlight the important roles of air-sea interactions and ocean circulations for modulation of surface and subsurface temperature. 相似文献
634.
稳恒水波的Fourier近似解研究 总被引:1,自引:0,他引:1
A computational method for steady water waves is presented on the basis of potential theory in the physical plane with spatial variables as independent quantities. The finite Fourier series are applied to approximating the free surface and potential function. A set of nonlinear algebraic equations for the Fourier coefficients are derived from the free surface kinetic and dynamic boundary conditions. These algebraic equations are numerically solved through Newton's iterative method, and the iterative stability is further improved by a relaxation technology. The integral properties of steady water waves are numerically analyzed, showing that (1) the set-up and the set-down are both non-monotonic quantities with the wave steepness, and (2) the Fourier spectrum of the free surface is broader than that of the potential function. The latter further leads us to explore a modification for the present method by approximating the free surface and potential function through different Fourier series, with the truncation of the former higher than that of the latter. Numerical tests show that this modification is effective, and can notably reduce the errors of the free surface boundary conditions. 相似文献
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636.
不透水地表作为城市土地覆盖类型的重要组分,其分布格局与密度大小对城市生态系统服务功能会产生相反且决定性的作用,其中对地表的增温效应是城市热岛问题关注的核心内容。本研究通过线性光谱混合分解模型提取城市不透水地表,基于Landsat TM6热红外波段数据的单窗算法反演地表温度,并进行两者的关系研究。结果表明:城市不透水地表与地温空间分布格局呈现高度相似性,其数值都随距城市中心距离增加而逐渐减小,定量分析表明两者具有明显的指数相关关系。 相似文献
637.
基于地图标注数据和技术开发研究了海量地图标注分类查询和电子地图表面注记交互式查询。设计高性能的数据组织与存储方案,研究客户端快速显示技术和服务器端高并发访问技术,实现了电子地图海量标注与表面注记交互式查询,提高海量地图标注查询效率,改善电子地图查询与显示的用户体验,增强用户使用网站的粘性。 相似文献
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640.
针对当前地图网络传输和地图网络制图的发展态势,开展了地图符号系统数据结构方面的研究,描述了绘图系统的类层次结构,建立了简单的交互式地图绘制系统;探讨了地图符号的串行化和反串行化问题,并针对SVG的特性及语法,研究了SVG格式地图文档的生成。 相似文献