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Validation of a hybrid optimal interpolation and Kalman filter scheme for sea surface temperature assimilation 总被引:1,自引:0,他引:1
A hybrid data assimilation scheme designed for operational assimilation of satellite sea surface temperatures (SST) into an ocean model has been developed and validated against in-situ observations. The scheme consists of an optimal interpolation (OI) part and a greatly simplified Kalman filter (KF) part.The OI is performed only in the longitudinal and latitudinal directions. A climatological field is used as a background field for the interpolation. It is constructed by fitting daily averages of satellite SST to the annual mean, annual, and semiannual harmonics in a 20 km by 20 km grid. The background error covariance is approximated by a spatially varying two-dimensional exponential covariance model. The parameters of the covariance model are fitted to the deviations of the satellite data from the background field using data from a full year.The simplified KF uses ocean model forecasts as a background field. It is based on the assumption that it is possible to neglect horizontal SST covariances in the filter and that the typical time scale for vertical mixing in the mixed layer is much shorter than the average time between observations. We therefore assume that the error variance in a column of water is evenly spread out throughout the mixed layer. The result of these simplifications is a computationally very efficient KF.A one year validation of the scheme is performed for year 2001 using an operational eddy resolving ocean model covering the North Sea and the Baltic Sea. It is found that assimilation of sea surface temperature data reduces the model root mean square error from 1.13 °C to 0.70 °C. The hybrid scheme is found to reduce the root mean square error slightly more than the simplified KF without OI to 0.66 °C. The inclusion of spatially varying satellite error variances does not improve the performance of the scheme significantly. 相似文献
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工程项目成本控制 总被引:2,自引:0,他引:2
佘国斌 《铁路工程造价管理》2003,18(6):27-29
工程项目成本控制是企业加强工程项目管理的重要内容,此对工程项目成本控制的原则和途径作了初步的阐述。 相似文献
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沥青路面压实度变异性分析及施工控制措施 总被引:3,自引:0,他引:3
根据理论分析和工程实测数据,分析了压实度变异的主要影响因素,提出了减小压实度变异性的施工控制措施。 相似文献
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结合南京长江隧道盾构工作井超深地下连续墙施工,介绍施工阶段监理的工作中预控、过程控制、验收三个环节地下连续墙的质量控制要点,详细说明了预控中设计审查,过程控制中成槽、钢筋笼和混凝土浇筑各工艺控制要点,以及验收阶段的监理重点,以供类似工程参考。 相似文献
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高层体系结构作为一门在计算机、网络和仿真技术的基础上发展起来的新技术,它一出现就立即受到军事训练和模拟作战等领域的广泛重视.对MakRTI和VR—Link环境下基于HLA标准的海洋环境作战模拟系统的开发方法进行了研究,并结合MultiGen Creator/Vega和VC++的虚拟现实平台实现了系统的三维视景仿真驱动.仿真程序运行良好,画面流畅. 相似文献
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为解决既有隧道衬砌结构病害威胁交通安全、影响交通质量和使用寿命等问题,从工程施工、自然环境和工程地质3方面共13个独立的既有隧道衬砌结构病害影响因素入手。首先,采用层次分析法(AHP)建立既有隧道衬砌结构病害形成因素指标体系,提出基于层次-可拓(AHP Extenics)模型的既有隧道衬砌结构病害评价方法; 然后,结合工程实际和专家打分确定病害评价指标权重,进而利用相关函数对病害评价指标和权重进行可拓运算;
最后,得出既有隧道衬砌结构病害评价等级。该方法采用形式化的可拓综合评价模型替代传统的模糊综合评价法,以定量的形式给出定性分析结果,使计算结果更加客观,为既有隧道衬砌结构的病害评价提供了一种新方法。 相似文献
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为了进行海下平台拖缆系统的设计,根据虚拟样机技术原理,采用Adams和AMESim分别建立了海下平台拖缆系统的动力学模型和控制系统模型,通过联合仿真分析验证了其结果与理论计算相似,实现了拖缆系统的恒张力控制和协同作业,表明了该方法的可行性和可靠性. 相似文献
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