Spar平台垂荡板水动力系数计算与分析     

滕斌  郑苗子  姜胜超  勾莹  吕林 《海洋工程》2010,28(3)

Spar平台带有厚度很薄的垂荡板,使用边界元方法计算时存在着准奇异积分的数值计算问题。采用自适应高斯积分法对其准奇异积分问题进行处理,较少单元即可达到很高精度。在势流理论下对Spar平台垂荡板的水动力系数进行了计算,并与实验结果进行了对比,发现真实流体中垂荡板的附加质量约为势流理论下附加质量计算结果的1.1倍,而辐射阻尼在总阻尼中所占的百分比很小,此时粘性阻尼成为垂荡板的主要阻尼来源,在工程设计中不可忽略。  相似文献   

水系划分的剖面相似系数聚类法          下载免费PDF全文

潘长明  高飞  袁延茂  王本洪 《海洋测绘》2014,(1):43-46

提出一种基于温度剖面相似系数的水系划分方法。基本思想是:将各温度剖面视为独立样本,各深度数据为样本变量,先基于划分区域水文特征选取合理数量的水系中心剖面,再利用各样本与各中心剖面相似系数大小进行聚类,得到各水系划分数据集合;利用几何平均求得各水系集合新的中心剖面,重复剖面相似系数聚类过程,直至中心剖面不再变化为止。最后利用国家海洋信息中心发布的中国近海CTD温、盐产品对该方法进行试验,并对聚类得到的各类温度剖面展开讨论。结果较好的反应出各区域温度剖面特征,综合体现出东海各区域温度大小、海流、水团和水深特性。  相似文献   

双淹没矩形体的透反射特性分析   总被引：1，自引：0，他引：1  

刘鹏飞  游亚戈  胡城 《海洋学报》2007,29(1):133-138

采用解析方法研究了斜向入射波作用下双淹没矩形体的透反射系数特性.首先利用特征函数展开法导出了绕射势函数的分析解并进一步得到透反射系数的计算公式,然后利用边界元方法验证了解析解.与单个的淹没矩形体相比,双淹没矩形体在一定范围内有较高的反射系数.最后利用解析解分析了若干工况下的双淹没矩形体的透反射特性,给出了影响透反射系数的几何因素.  相似文献   

气象基础设施云平台关键设计与实现     

韩同欣  何文春  吴鹏  李江涛 《气象科技》2022,50(2):290-296

为适配气象业务科研应用对算力、存储资源的需求特点,采用分布式计算、分布式存储、虚拟化技术搭建气象基础设施云平台,并根据不同的业务类别、网络区域、资源服务对象针对性地设计云平台资源分区,以及每个分区需具备的云资源及功能。设计的云平台涵盖IaaS层、PaaS层功能,通过软件定义方式池化硬件资源,形成具备云计算、大数据支撑特征的资源池,为众多气象应用端部署、气象大数据业务提供虚拟主机、物理算力、数据存储资源。实际运行效果表明设计的气象基础设施云平台能够适应数据处理规模与时效性要求不断提升的业务发展需求。  相似文献   

The Relationship between Normalized Difference Vegetation Index （NDVI） and Climate Factors in the Semiarid Region： A Case Study in Yalu Tsangpo River Basin of Qinghai-Tibet Plateau   总被引：1，自引：0，他引：1  

GUO Bing  ;ZHOU Yi  ;WANG Shi-xin  ;TAO He-ping 《山地科学学报》2014,11(4):926-940

The Yalu Tsangpo River basin is a typical semi-arid and cold region in the Qinghai-Tibet Plateau, where significant climate change has been detected in the past decades. The objective of this paper is to demonstrate how the regional vegetation, especially the typical plant types, responds to the climate changes. In this study, the model of gravity center has been firstly introduced to analyze the spatial-temporal relationship between NDVI and climate factors considering the time-lag effect. The results show that the vegetation grown has been positively influenced by the rainfall and precipitation both in moving tracks of gravity center and time-lag effect especially for the growing season during the past thirteen years. The herbs and shrubs are inclined to be influenced by the change of rainfall and temperature, which is indicated by larger positive correlation coefficients at the 0.05 confidence level and shorter lagging time. For the soil moisture, the significantly negative relationship of NDV-PDI indicates that the growth and productivity of the vegetation are closely related to the short-term soil water, with the correlation coefficients reaching the maximum value of o.81 at Lag 0-1. Among the typicalvegetation types of plateau, the shrubs of low mountain, steppe and meadow are more sensitive to the change of soil moisture with coefficients of -0.95, -0.93, -0.92, respectively. These findings reveal that the spatial and temporal heterogeneity between NDVI and climatic factors are of great ecological significance and practical value for the protection of eco-environment in Qinghai-Tibet Plateau.  相似文献   

基于频域Rankine面元法的船舶耐波性计算和分析          下载免费PDF全文

吕向琪  张志恒  张新曙  宋兴宇 《海洋工程》2023,41(1):68-81

在频域中分别使用Rankine面元法和去奇点Rankine面元法（desingularized-Rankine panel method，简称DRPM）快速求解有航速船舶耐波性问题。使用两种不同的线性化方式：叠模流线性化法（double-body flow，简称DB）和均匀流线性化方法（Neumann-Kelvin，简称NK）计算了Wigley I、Wigley III和S175在有航速时船舶的水动力系数、波浪激励力和运动响应。两种线性化方法的计算结果与试验结果进行了比较，研究表明：使用Rankine面元法和去奇点Rankine面元法计算的结果相差不大，且与NK法相比使用DB法计算的结果和试验值更吻合，尤其是非对角线上交叉耦合水动力系数A35,B35,A53,B53的计算结果。运动响应对于边界条件线性化方式比较敏感，尤其是垂荡运动，在船共振频率附近，运动受到的影响最明显。  相似文献   

元胞空间分区及其对GeoCA模型模拟精度的影响   总被引：1，自引：0，他引：1  

柯新利  邓祥征  陈勇 《遥感学报》2011,15(3):512-523

采用双约束空间聚类方法对元胞空间进行分区,在此基础上对不同的分区分别求取元胞转换规则,从而提高 元胞自动机的模拟精度。以杭州市土地利用变化为例,采用本文提出的基于双约束空间聚类的分区元胞自动机模型对 研究区域2000年—2005年的土地利用变化进行模拟,并利用逐点对比法和Moran I指数对模拟结果进行精度评估。结果 表明：(1)采用双约束空间聚类算法对元胞空间进行分区,可以保证同一分区内的元胞既在空间上邻近,又具有相对一 致的非空间属性信息,分区效果较好;(2)与不分区元胞自动机模型和基于空间聚类的分区元胞自动机模型相比,双约 束空间聚类元胞自动机模型具有较高的模拟精度,尤其是在空间形态和整体结构上具有较好的模拟效果。  相似文献   

Significance of selective crystal entrainment and differential crystal-melt separation in petrogenesis of granites from the Tongbai orogen     

Qiang-Qiang Zhang  Xiao-Ying Gao  Yong-Fei Zheng 《Journal of Metamorphic Geology》2023,41(1):143-179

Partial melting has been shown to be an important mechanism for intracrustal differentiation and granite petrogenesis. However, a series of compositional differences between granitic melt from experiments and natural granites indicate that the processes of crustal differentiation are complex. To shed light on factors that control the processes of crustal differentiation, and then the compositions of granitic magma, a combined study of petrology and geochemistry was carried out for granites (in the forms of granitic veins and parautochthonous granite) from a granulite terrane in the Tongbai orogen, China. These granites are characterized by high SiO₂ (>72 wt%) and low FeO and MgO (<4 wt%) with low Na₂O/K₂O ratios (<0.7). Minerals in these granites show variable microstructures and compositions. Phase equilibrium modelling using P–T pseudosections shows that neither anatectic melts nor fractionated melts match the compositions of the target granites, challenging the conventional paradigm that granites are the crystallized product of pure granitic melts. Based on the microstructural features of minerals in the granites, and a comparison of their compositions with crystallized minerals from anatectic melts and minerals in granulites, the minerals in these granitoids are considered to have three origins. The first is entrained garnets, which show comparable compositions with those in host granulites. The second is early crystallized mineral from melts, which include large plagioclase and K-feldspar (with high Ca contents) crystals as well as a part of biotite whose compositions can be reproduced by crystallization of the anatectic melts. The compositions of other minerals such as small grained plagioclase, K-feldspar and anorthoclase in the granites with low Ca contents are not well reconstructed, so they are considered as the third origin of crystallized products of fractionated melts. The results of mass balance calculation show that the compositions of these granites can be produced by mixing between different proportions of crystallized minerals and fractionated melts with variable amounts of entrained minerals. However, the calculated modal proportions of different crystallized minerals (plagioclase, K-feldspar, biotite and quartz) in the granites are significantly different from those predicted by melt crystallization modelling. Specifically, some rocks have lower modes of biotite and plagioclase, whereas others show lower K-feldspar modes than those produced by melt crystallization. This indicates that the crystallized minerals would be differentially separated from the primary magmas to form the evolved magmas that produce these granites. Therefore, the crystal entrainment and differential melt-crystal separation make important contributions to the composition of the target granites. Compared with leucogranites worldwide, the target granites show comparable compositions. As such, the leucogranites may form through the crystal fractionation of primary granitic magmas at different extents in addition to variable degrees of partial melting.  相似文献   

西太平洋暖池区的海气通量及整体交换系数   总被引：3，自引：1，他引：2  

徐静琦  魏皓  顾海涛  武建平 《气象学报》1997,55(6):703-713

根据西太平洋海域弱风、高温、潮湿的大气状态特征,提出了在光滑面存在粘性副层气流中的廓线的层结订正方案。用此模式对西太平洋暖池区ＴＯＧＡＣＯＡＲＥＩＯＰ期间,在向阳红５号船（２°Ｓ,１５４°Ｅ）获取的海面风、温、湿梯度资料进行了处理。计算结果显示西太平洋暖池区贴水层气流中不稳定层结占５０％－８０％,其中很不稳定的占１０．３％;该海区海气通量和整体交换系数受层结影响远大于受风速的影响;海气通量和整体交换系数随不稳定程度增加而增大,在相同风速下量值可相差４倍以上;其变化范围为０．３×１０－３—３．２×１０－３。由此可见,层结的影响使它们的变化大于其它海区的结果。在ｕ１０＝０－１０ｍ／ｓ范围内,中性化整体交换系数平均为ＣＤＮ＝１．２×１０－３,ＣＨＮ＝１．１４×１０－３,ＣＥＮ＝１．１９×１０－３,与Ｌａｒｇｅ和Ｐｏｎｄ（１９８１,１９８２）不稳定条件的研究结果相差无几。  相似文献