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海冰是冬季影响港口作业、海上运输、船舶安全的重要因素,作者介绍了海冰的类型及特点、中国海域海冰发展周期及冰情特征,最后就船舶在冰区航行的准备工作及注意事项加以总结,以期对冬季船舶防冰、抗冰工作提供帮助和参考。 相似文献
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海冰是渤海和黄海北部海区的自然灾害之一,由于冷冬气候影响,流冰非常严重,其会对港口水域助航设施及船舶航行安全造成严重危害,给海上救助工作增加相当大的难度。 相似文献
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在深入调查研究海事主管部门和港航企业对海冰预警产品需求的基础上,根据自然灾害风险模糊综合评价理论和技术,建立可用于中国北方海域冰区航行船舶的风险预评估模型。使用ENVI软件对NASA的海冰卫星遥感实况和国家海洋局发布的海冰预报信息进行再处理,提取有关海冰密集度和厚度信息作为风险评估的背景场,进而提出冰区航行船舶风险状况动态评估预警系统的设计方案。仿真实例分析结果表明,该系统可动态、直观、有效地给出我国北方海域冰区航行船舶未来的风险状况,可作为保障船舶冰区航行安全的辅助决策产品,供海事主管部门、航运企业和港口生产调度部门使用。 相似文献
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分析渤黄海海冰的特点和影响,结合我国港口和海上交通运输的特点,提出应对措施和建议:编制海冰灾害应急预案,科学应对自然灾害;健全海冰预报体系;适当增强抗冰能力;关注船舶航行安全;构建应急物流。 相似文献
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结合“埃德蒙顿”号在白令海冰困遇难的教训,建议船舶应谨慎进入冰区;同时对从事冰区航行的船舶应做的准备、冰区航行的方法以及冰困后的救助措施进行了论述。 相似文献
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Characteristics and potential impacts of under-ice river plumes in the seasonally ice-covered Bothnian Bay (Baltic Sea) 总被引:4,自引:0,他引:4
The northernmost basin of the Baltic Sea, the Bothnian Bay, is ice-covered for about half the year. During this time, distinct under-ice river plumes develop, even seaward of the smallest rivers, that are substantially thicker and larger in extent than during the summer months. Wind mixing is negligible, and during late spring in April or May, the highest annual discharge occur while the sea is ice covered, thus providing conditions for the formation of extensive under-ice plumes. These plumes are characterised by high levels of trace elements (e.g., Al, Fe and Zn), organic matter (TOC and dissolved organic carbon [DOC]), nutrients and also optically active substances (colored dissolved organic matter, CDOM). The under-ice plumes provide an important pathway for undiluted transport of land-derived substances to the pelagic waters of the basin, affecting the salinity, chemistry and optical properties of coastal waters. Freshwater ice growth on the underside of an existing sea ice sheet also restricts the buildup of sea ice and under-ice algal communities, potentially in large areas along the coasts. Plume water influences the optical characteristics of coastal waters for a period of time after ice break-up, potentially affecting primary production in these areas. Furthermore, the formation of under-ice plumes potentially has a positive feedback on the ice season length due to freshening of the coastal waters (earlier freeze-up) and restricted oceanic heat flux (slower melting). 相似文献
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The trend towards global warming and the rapid decline in the extent of summer Arctic sea ice over recent years has increased the feasibility of international Arctic shipping. In this study we propose a seasonal NSR (North Sea Route)/SCR (Suez Canal Route)-combined shipping service linking Shanghai and Rotterdam, using the Northern Sea Route during the economical navigable window but using the traditional Suez Canal Route at other times. Different from the previous literatures, this paper dynamically considers the sea ice extent in the model, which is more reasonable for the assessment of Arctic container shipping, because fuel consumption is highly related to ship speed, while ship speed is determined by the relative distances of ice-covered and ice-free route stages. A new approach is developed to predict the time points at which the ship enters and exits the ice-covered stage, given that both the ship position and the extent of sea ice are constantly changing. The results show that the NSR/SCR-combined Arctic container service can be more economical than the SCR, given lower NSR tariffs. 相似文献
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基于我国第七次北极科学考察获得的夏季北极海冰空间分布情况,模拟真实碎冰分布,采用LS-DYNA软件中的流固耦合方法,研究在船舶航速、碎冰尺度、碎冰厚度及碎冰密集度等因素影响下船舶-碎冰碰撞的船体结构响应。结合试验数据得到船体结构的应力、吸能和碰撞力。结果表明:船舶-碎冰的主要碰撞区域为艏部及舷侧的水线附近;在船舶航行于碎冰域时,船体结构的应力、吸能和碰撞力的峰值随碎冰域的船舶航速、碎冰尺度、碎冰厚度及碎冰密集度的增加而增加,但分布情况不同。研究结果为船舶在极地冰区航行提供一定的安全性参考。 相似文献
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The ice resistance on ships in escort operations in level ice are investigated using the discrete element method (DEM). A dilated polyhedron—generated by the Minkowski sum of a sphere and a polyhedron—is employed in the DEM; this dilated polyhedron-based DEM (DPDEM) is adopted to simulate the ship–ice interaction, wherein the contact force and bond-failure criterion are considered for the collision and fracture of sea ice, respectively. A three-point bending test was simulated with DPDEM, and a field test was conducted in the Bohai Sea to validate the DEM results. Further, a parametric analysis of flexural strength was conducted to identify the parameters involved in the bond-failure criterion. The ice resistance on icebreakers and cargo ships in level ice are simulated using DPDEM. The simulated ice resistances are compared with the Lindqvist and Riska formulas and the model test, which proves the validity of the DEM simulation. The interaction between ships and level ice is simulated parametrically to investigate the ice resistance on cargo ships with and without the icebreaker escort. Influencing factors such as ship speed, ice thickness, and ship breadth were examined to investigate the ice resistance on the escorted cargo ship. Analysis and change rules of the ice resistance on cargos affected by those factors were given. 相似文献
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在冰区油气开发中,锥体结构可以有效降低冰力,避免强烈的冰激振动,是目前渤海油气平台的主要结构形式。为研究海冰与锥体结构的相互作用过程,文章建立了适用于模拟海冰破碎特性的离散单元模型。该模型将海冰离散为若干个具有粘接-破碎功能的颗粒单元,并通过海冰弯曲试验确定了单元间的粘接强度;然后对海冰与锥体结构的作用过程进行了数值计算,获得了相应的动冰荷载及冰振响应;在此基础上讨论了不同锥角影响下冰荷载及结构振动响应的变化规律。结果表明,水平方向冰荷载及结构冰振响应随锥角的增加明显增加,而竖直方向冰荷载则显著降低。该离散单元模型还可进一步应用于不同类型抗冰结构的冰荷载分析,有助于解决冰区结构物的抗冰结构设计和冰致疲劳分析。 相似文献
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Protist abundance and taxonomic composition were determined in four development stages of newly formed sea ice (new ice, nilas, young ice and thin first-year ice) and in the underlying surface waters of the Canadian Beaufort Sea from 30 September to 19 November 2003. Pico- and nanoalgae were counted by flow cytometry whereas photosynthetic and heterotrophic protists ≥ 4 µm were identified and counted by inverted microscopy. Protists were always present in sea ice and surface water samples throughout the study period. The most abundant protists in sea ice and surface waters were cells < 4 µm. They were less abundant in sea ice (418–3051 × 103 cells L− 1) than in surface waters (1393–5373 × 103 cells L− 1). In contrast, larger protists (≥ 4 µm) were more abundant in sea ice (59–821 × 103 cells L− 1) than in surface waters (22–256 × 103 cells L− 1). These results suggest a selective incorporation of larger cells into sea ice. The ≥ 4 µm protist assemblage was composed of a total number of 73 taxa, including 12 centric diatom species, 7 pennate diatoms, 11 dinoflagellates and 16 flagellates. The taxonomic composition in the early stage of ice formation (i.e., new ice) was very similar to that observed in surface waters and was composed of a mixed population of nanoflagellates (Prasinophyceae and Prymnesiophyceae), diatoms (mainly Chaetoceros species) and dinoflagellates. In older stages of sea ice (i.e., young ice and thin first-year ice), the taxonomic composition became markedly different from that of the surface waters. These older ice samples contained relatively fewer Prasinophyceae and more unidentified nanoflagellates than the younger ice. Diatom resting spores and dinoflagellate cysts were generally more abundant in sea ice than in surface waters. However, further studies are needed to determine the importance of this winter survival strategy in Arctic sea ice. This study clearly shows the selective incorporation of large cells (≥ 4 µm) in newly formed sea ice and the change in the taxonomic composition of protists between sea ice and surface waters as the fall season progresses. 相似文献
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船舶在冰区航行时的冰阻力性能一直是国内外关注和研究的重点。冰阻力的研究主要集中在经验方法、数值模拟和实验研究三个方面。同时,由于冰区船舶在航行过程中频繁地与冰层或浮冰产生碰撞,海冰的材料结构和力学性质对冰阻力的研究有重要影响。文章从冰的物理力学特性出发,简要回顾几种重要的冰本构关系模型及其适用性;并从经验方法及试验与数值模拟相结合两个角度,回顾和讨论浮冰区和平整冰区中船舶的冰阻力性能研究进展;最后,基于研究现状提出尚需进一步解决的问题。文章旨在介绍冰区船舶冰阻力性能的研究进展,望能为后续冰阻力研究提供参考。 相似文献