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41.
Ship operation and ice loading in floe ice fields have received considerable interest during recent years. There have been several numerical simulators developed by different institutes which can simulate ship navigation through floe ice fields and estimate ship performance and local ice loads. However, public data obtained from full-scale measurement covering comprehensively ship performance and ice loads under various ice thicknesses, concentrations and floe sizes are rare. The 2018/19 Antarctic voyage of the Polar Supply and Research Vessel (PSRV) S.A. Agulhas II gathered considerable data of the ship in floe ice fields under various thicknesses, concentrations, and floe sizes. The aim of this paper is to carry out statistical analysis to seek suitable probability distributions which adequately fit the measured ice load and therefore suitable to be used as parent distributions for long-term estimation. For this aim, three categories of probability distributions, namely standard distributions, truncated distributions and mixture distributions are tested. It is found that truncated distributions can fit the load data better than standard distributions bounded at the threshold. In addition, mixture distributions are shown to have promising features, which fit the data well and are able to separate distribution components. Subsequentially, the well-performed distributions are used as parent distributions to make long-term load estimations. The estimation results demonstrate that long-term estimations are sensitive to the selection of parent distribution, which addresses the importance of finding correct distribution to model short-term ice loads. The data of ten selected cases will be published for the use of other researchers. 相似文献
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贺利工 《城市轨道交通研究》2015,18(1):101-103
以某城市地铁地下站为例,从水系统的流程、与用户的连接方式、系统配置等方面分析了车站采用冰蓄冷的方案。采用该地下站的冷负荷数据,对车站冰蓄冷系统和常规制冷系统方案进行了技术经济比较,得到结论:由于该城市峰谷电价差超过3.5倍,采用冰蓄冷是可行的,但优势不突出。冰蓄冷方式利用电价差达到总费用最小,省钱但不省电。 相似文献
44.
顾津申 《铁道标准设计通讯》2014,(3):63-66
以哈尔滨至齐齐哈尔客运专线松花江特大桥主桥桥墩为例,详细论述四线铁路桥墩的设计思路与设计方法,给出四线铁路桥墩设计时应重点关注的荷载组合工况;通过对冰压力荷载的分析,提出高纬度严寒地区桥墩的设计建议,对相同类型的工程具有一定的参考和借鉴意义。 相似文献
45.
船冰碰撞载荷下船舶结构加强方案研究 总被引:3,自引:0,他引:3
为了探究水介质对船—冰碰撞结构响应的影响,文章首次对考虑水介质中的船—冰碰撞问题进行了研究。模拟了船舶与冰体在水介质中的碰撞场景,研究船—水—冰三者共同耦合作用对船—冰碰撞的影响。将该计算方法应用于船—冰碰撞的多种工况计算,对比分析了增加外板厚度、横隔板厚度以及肋骨间距等多种加强方案对船体结构响应的差异。揭示了碰撞区域的损伤变形、碰撞力、结构吸能随外板厚度、横隔板厚度和肋骨间距的变化而变化的规律,分析了船舶肩部各主要构件对于抵抗冰载荷作用的能力及贡献。所得结论对于进行冰区船舶结构设计具有参考作用。 相似文献
46.
A transport assessment of particle-bound and dissolved artificial radionuclides (137Cs and 239,240Pu) by sea-ice and dense-water formed in western Kara Sea flaw leads close to the Novaya Zemlya dumping sites is presented in this study. We both performed a “best estimate” based on available data, and a “maximum assessment” relying on simulated constant releases of 1 TBq 137Cs and 239,240Pu from individual dumping bays. The estimates are based on a combination of (i) the content of particulate matter in sea-ice; (ii) analytical data and numerical simulations of radionuclide concentrations in shelf surface deposits, suspended particulate matter (SPM), and the dissolved phase; and (iii) estimates of lead-ice and dense-water formation rates as well as modeling results of local ice drift pathways. In the “best estimate” case, 2.90 GBq 137Cs and 0.51 GBq 239,240Pu attached to sea-ice sediments can be exported from the lead areas toward the central Arctic basin. The radionuclide burden of the annually formed dense lead water in the “best estimate” amounts to 4.68 TBq 137Cs and 0.014 TBq 239,240Pu. In the “maximum assessment”, potential export-rates of ice-particle bound 137Cs and 239,240Pu toward the central Arctic would amount to 0.64 and 0.16 TBq, respectively. As much as ≈900 TBq 137Cs and ≈6.75 TBq 239,240Pu could be annually taken up by 34.75 dense-water rejected in the lead area. Assuming the (unlikely) instantaneous release of the total 137Cs and 239,240Pu inventories (≈1 PBq and 10 TBq, respectively) from the Novaya Zemlya dumping sites into the dissolved phase, the dense lead water locally formed during one winter season could take up ≈90% of the Cs and ≈68% of the Pu released. 相似文献
47.
利用元胞自动机,建立了冰雪条件下城市道路单车道和双车道交通流微观模型.针对冰雪条件下驾驶员出于安全考虑降低车速、保持较大车间距的现象,细化了元胞尺寸,引入反映不同冰雪条件的速度因子参数和间距因子参数.通过数值模拟,得出了正常天气和冰雪天气下的车辆速度、密度、流量间的关系曲线,并分析了不同冰雪条件对交通流的影响.研究发现,中雪条件下的车速波动程度及范围最大;基本图显示冰雪条件对于临界密度、最大流量等参数影响较大;冰雪条件下的亚稳回滞现象不明显,未出现换道频率局部最大值. 相似文献
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根据地铁车站的特点,通过全面的技术经济分析,认为在地铁中采用大温差供水和低温送风的冰蓄冷空调是可行的,可以节省初期投资和运行电费。 相似文献
50.