共查询到20条相似文献,搜索用时 78 毫秒
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This article introduces the most advanced form of electronic chart display and information systems (ECDIS) which complies with the performance standards for ECDIS established by the International Maritime Organization (IMO) and International Hydrographic Organization (IHO). It also describes the key features and the important functions of ECDIS, which we developed. This system is different from the productions developed by C-map, Seven-cs, offshore, and others. It is more suitable for China Marine Safety Administration Bureau to manage the navigation marks real-time. Using this system charts were located and accessed rapidly, and displayed smoothly. This article also discusses in ECDIS application system how to dynamically access and desert charts data in a limited memory (limited computer memory and resource). We constructed a tridimensional structure to manage a large amount of charts data. Vertically, according to the scale range, all charts were divided into eight levels, and a data structure called as “Multiple Scale Quad-tree” was constructed. And horizontally, a grid (every unit has a fixed size) was given to a certain scale level. We call this data structure a “Regular Page.” We explore the implementation of such a structure on the worldwide charts management utilizing quad-trees. Then we discuss the future development of ECDIS and its application system in marine agencies in China. 相似文献
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This article introduces the most advanced form of electronic chart display and information systems (ECDIS) which complies with the performance standards for ECDIS established by the International Maritime Organization (IMO) and International Hydrographic Organization (IHO). It also describes the key features and the important functions of ECDIS, which we developed. This system is different from the productions developed by C-map, Seven-cs, offshore, and others. It is more suitable for China Marine Safety Administration Bureau to manage the navigation marks real-time. Using this system charts were located and accessed rapidly, and displayed smoothly. This article also discusses in ECDIS application system how to dynamically access and desert charts data in a limited memory (limited computer memory and resource). We constructed a tridimensional structure to manage a large amount of charts data. Vertically, according to the scale range, all charts were divided into eight levels, and a data structure called as “Multiple Scale Quad-tree” was constructed. And horizontally, a grid (every unit has a fixed size) was given to a certain scale level. We call this data structure a “Regular Page.” We explore the implementation of such a structure on the worldwide charts management utilizing quad-trees. Then we discuss the future development of ECDIS and its application system in marine agencies in China. 相似文献
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This paper treats the problem of how to transform from global datum, for example, from the International Terrestrial Reference System (ITRS), to a local datum, for example, regional or national, for the practical case of the Lambert projection of the sphere or the ellipsoid-of-revolution to the cone. We design the two projection constants n(ϕ1, ϕ2) and m(ϕ1) for the Universal Lambert Conic projection of the ellipsoid-of-revolution. The task to transform from a global datum with respect to the ellipsoid-of-revolution EA,B2 to local datum with respect to the alternative ellipsoid-of-revolution Ea,b2, without local ellipsoidal height, is solved by an extended numerical example. Ideas in this paper could be of interest to those working with maps and coordinates transformation from global geodetic datum to local geodetic datum and vice versa, under the Universal Lambert Conic projection, and applicable to precise positioning and navigation, boundary demarcation and determination in the marine environment. 相似文献
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Isobathymetric Line Simplification with Conflict Removal Based on a B-spline Snake Model 总被引:1,自引:0,他引:1
This paper introduces a new method for the smoothing of isobathymetric lines for marine chart construction. Specific constraints have to be observed as the chart must be legible and safe for navigation. The method, based on a snake model, respects these constraints of legibility and safety which impose a direction for curve deformation. Conflicts such as self-intersections are also considered. These two points are the main contributions of the paper as current methods cannot deal with such constraints. Several case studies are presented and results obtained on real data are discussed. 相似文献
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This paper introduces a new method for the smoothing of isobathymetric lines for marine chart construction. Specific constraints have to be observed as the chart must be legible and safe for navigation. The method, based on a snake model, respects these constraints of legibility and safety which impose a direction for curve deformation. Conflicts such as self-intersections are also considered. These two points are the main contributions of the paper as current methods cannot deal with such constraints. Several case studies are presented and results obtained on real data are discussed. 相似文献
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北极拥有其独特的地理位置和战略价值,同时也是全球变暖最关键的敏感区,世界各国针对北极地区制定了一系列政策计划,并开展了多年的北极海洋科学研究。基于Web of Science数据库收录的1998~2017年SCIE文章,采用文献计量与引文分析的方法与工具,分析了13784篇北极海洋科学研究的整体态势与热点前沿,结果表明:①全球北极海洋科学研究呈现出加快增长趋势,近5年的发文已经翻了一番,年均发文在689篇以上; ②环北极八国是该领域研究的主要力量,美国遥遥领先其他国家,挪威、丹麦研究基底深厚但近年发展稍缓,英国、德国是主要的非北极研究国,瑞典、法国的论文质量均衡,中国、波兰、格陵兰和荷兰则是该领域的后起之秀; ③俄罗斯科学院在本领域发文最多但文章质量良莠不齐,德国极地与海洋研究所、丹麦&格陵兰地质调查机构与挪威海洋研究所的第一作者与通讯作者研究占比高,哥本哈根大学、德国极地与海洋研究所、华盛顿大学在该领域科研影响力较大; ④全球海洋科学研究主要涉及地质学、海洋学、环境生态学、自然地理学、地球化学与地球物理学以及气象学与大气科学等领域,研究热点包括北极气候变化与极端天气、冰川消融与海平面上升、北极生态系统特征结构、北极海洋酸化与污染防治等方面。随着“一带一路”、“冰上丝绸之路”和《中国的北极政策》白皮书的发布,建议我国针对本国情况制定综合性北极科研计划,并注重科研机构间跨部门、跨领域的研究合作,加强与环北极国家和“一带一路”国家的合作,加大科研投入并开展国际规模的科学考察活动。 相似文献
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本文利用ERA5再分析数据和我国北极科学考察期间获取的走航气象观测数据,分析了夏季影响船舶通航北极航道的关键近地面气象要素的时空变化特征。结果表明,7–8月的天气条件最适宜船舶在北极航道航行,9月低温、大风和大浪天气显著增多,对船舶航行影响较大,10月的天气更加恶劣,对船舶航行的挑战更大。低温天气主要出现在各航道的中段,大风和大浪天气集中在航道两端的海域。除北极中心区和10月的挪威海和巴伦支海以外,其余时间的海域出现大风和大浪天气的概率以增加趋势为主,但具有较大的年际变化。根据现有北极航道气象观测数据分析发现,东北航道能见度最差,西北航道能见度最好,中央航道居中。 相似文献
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北极海冰密集度预报对大气强迫敏感性的个例研究 总被引:3,自引:0,他引:3
YANG Qinghu LIU Jiping ZHANG Zhanhai SUI Cuijuan XING Jianyong LI Ming LI Chunhu ZHAO Jiechen ZHANG Lin 《海洋学报(英文版)》2014,33(12):15-23
A regional Arctic configuration of the Massachusetts Institute of Technology general circulation model (MIT-gcm) is used as the coupled ice-ocean model for forecasting sea ice conditions in the Arctic Ocean at the Na-tional Marine Environmental Forecasting Center of China (NMEFC), and the numerical weather prediction from the National Center for Environmental Prediction Global Forecast System (NCEP GFS) is used as the atmospheric forcing. To improve the sea ice forecasting, a recently developed Polar Weather Research and Forecasting model (Polar WRF) model prediction is also tested as the atmospheric forcing. Their forecasting performances are evaluated with two different satellite-derived sea ice concentration products as initializa-tions: (1) the Special Sensor Microwave Imager/Sounder (SSMIS) and (2) the Advanced Microwave Scanning Radiometer for EOS (AMSR-E). Three synoptic cases, which represent the typical atmospheric circulations over the Arctic Ocean in summer 2010, are selected to carry out the Arctic sea ice numerical forecasting experiments. The evaluations suggest that the forecasts of sea ice concentrations using the Polar WRF atmo-spheric forcing show some improvements as compared with that of the NCEP GFS. 相似文献
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Ice, harsh weather, severe cold, and remoteness increase the risks of navigating the Arctic. Robust ships and shipboard systems to support routine operations and effectively respond to accidents and emergency situations are necessary. In spite of these challenges, the cruise ship industry is reportedly preparing to expand its passenger capacity, destinations, and operating season in the Arctic. An examination of the Arctic cruise ship fleet shows that the most capable ships are approaching the end of their service lives and may be replaced during the next decade. A window of opportunity is open for the international community to act on concerns about the safety of cruise ships in Polar Regions by codifying and making mandatory the International Maritime Organization's Guidelines for ships operating in Polar waters. A mandatory code would provide regulatory guidance to ship-builders at a critical point in the process of procuring new Arctic cruise ships and ensure that suitably constructed and outfitted ships would serve Arctic cruisers. 相似文献
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Short-lived halocarbons were measured in Arctic sea–ice brine, seawater and air above the Greenland and Norwegian seas (~81°N, 2–5°E) in mid-summer, from a melting ice floe at the edge of the ice pack. In the ice floe, concentrations of C2H5I, 2-C3H7I and CH2Br2 showed significant enhancement in the sea ice brine, of average factors of 1.7, 1.4 and 2.5 times respectively, compared to the water underneath and after normalising to brine volume. Concentrations of mono-iodocarbons in air are the highest ever reported, and our calculations suggest increased fluxes of halocarbons to the atmosphere may result from their sea–ice enhancement. Some halocarbons were also measured in ice of the sub-Arctic in Hudson Bay (~55°N, 77°W) in early spring, ice that was thicker, colder and less porous than the Arctic ice in summer, and in which the halocarbons were concentrated to values over 10 times larger than in the Arctic ice when normalised to brine volume. Concentrations in the Arctic ice were similar to those in Antarctic sea ice that was similarly warm and porous. As climate warms and Arctic sea ice becomes more like that of the Antarctic, our results lead us to expect the production of iodocarbons and so of reactive iodine gases to increase. 相似文献