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在桁架式深吃水立柱式平台(Truss Spar)运输作业的浮卸过程中,半潜驳船不断压载下潜直到Truss Spar平台自浮后拖离驳船。针对浮卸作业的双浮体状态,提出Truss Spar平台在与半潜驳船发生接触情况下的载荷计算方案并进行结构应力水平评估。基于三维势流理论及SESAM软件,考虑平台及半潜驳船双浮体之间的水动力相互影响,首先对双浮体系统进行频域下求解,得到波浪诱导载荷;然后在时域下求解波浪中双浮体的运动方程及产生的接触力;最后将这两种载荷下的结构强度分析结果进行线性叠加,得到Truss Spar平台在波浪诱导载荷及接触力联合作用下结构应力水平。对比不同波浪方向及周期下的接触力结果,研究Spar平台结构整体应力水平及高应力区域位置特点,对总体强度水平进行评估。 相似文献
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In this paper, an explosive cyclone (EC) that occurred over Northeast China in the spring of 2016 is studied by using 6.7 μm FY satellite water vapor (WV) imagery and NCEP (1°×1°) reanalysis data. Moreover, the evolutions of the upper-level jet stream (ULJ), the vertical motions, and the potential vorticity (PV) are analyzed in detail. Results show that different shapes of the WV image dark zones could reflect different stages of the EC. At the pre-explosion stage, a small dark zone and an S-shaped baroclinic leaf cloud can be found on the WV imagery. Then the dark zone expands and the leaf cloud grows into a comma-shaped cloud at the explosively developing stage. At the post-explosion stage, the dark zone brightens, and the spiral cloud forms. The whole process can be well described by the WV imagery. The dynamic dry band associated with the sinking motion and the ULJ can develop into the dry intrusion later, which is an important signal in forecasting the EC and should be paid attention to when analyzing the WV imagery. Furthermore, the mechanism is also analyzed in detail in this article. EC usually occurs in the left-exit region of the 200-hPa jet and the region ahead of the 500-hPa trough where there is significant positive vorticity advection (PVA). When the EC moves onto the sea surface, the decreased friction would favour the development of the EC. The upper-level PVA, the strong convergence at low level, and the divergence at high levels can maintain the strong updraft. Meanwhile, the high PV zone from the upper levels extends downward, approaching the cyclone. Together, they keep the cyclone deepening continuously. 相似文献
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利用冬奥张家口赛〖JP3〗区云顶和古杨树两个赛场的地面加密站网观测资料和高空探测资料、ERA5的0.25°×0.25°〖JP〗高分辨率再分析资料,从降雪时空分布特征、高低空环流形势配置等对2019年和2020年冬季(11月至次年2月)张家口赛区的降雪过程进行天气学统计分析。结果表明:降雪天气的环流背景主要归纳为3个类型,分别是低涡气旋型、冷锋型和西北气流型。不同天气模型下降雪量时空分布具有典型特点,低涡气旋型过程平均降雪量最大,降雪持续时间长,云顶赛场比古杨树赛场降雪量多16.9%;冷锋型过程平均降雪量次之,云顶赛场比古杨树赛场降雪量多44.4%;西北气流型过程平均降雪量最少,持续时间短,但是两个赛场差异最大,云顶赛场比古杨树赛场降雪量多140%。 相似文献
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