船舶在狭窄水域下水应对措施

滩涂造船因投资少、见效快,发展速度较快,但存在着较大的安全隐患。如在船舶下水过程中缺少科学知识,措施不力,极易造成船舶下水事故。针对这一情况,本文对下水过程运动状况、特点作了分析,只要利用有用力,控制不利力,才能避免船舶下水事故的发生。     

海上交通巡逻和救助船舶配置规模研究

为适应海上交通安全管理需要,确定巡逻和救助船舶配置规模,根据船舶使用水域和功能定位,将巡逻和救助船舶划分3种类型和7个系列,基于巡逻船雷达基本探测原理和巡逻路径,计算巡逻船有效监管距离和面积,基于海上交通应急到达时间要求和救助路径,计算救助船有效救助距离和面积,根据离岸不同距离水域面积和岸线长度,确定巡逻和救助船舶配置规模,提高巡逻和救助船舶布局规划的科学性。     

渡运水域船舶航行安全隐患的思考及预防对策

文中从航经渡运水域的船舶角度出发,着重对船舶航经渡运水域的安全隐患进行分析,并提出相应的预防对策,供有关方面人士参考.     

三峡库区桥区河段船舶运动模型与仿真研究

三峡成库后,库区在建跨河桥梁日渐增多,为避免或减少船桥碰撞事故,从船舶驾驶与避碰的角度,以石忠高速公路忠县长江大桥为研究对象,运用船舶操纵理论,建立船舶在桥区水域受风、流影响偏航数学模型,并通过仿真技术模拟船舶在桥区河段运动航迹,显示船舶通过大桥上下行三维视景,为研究三峡库区跨河桥梁主动防撞提供理论依据。     

中国海事水上巡航现状及发展趋势

对中国法律法规对中国海事水上巡航的要求以及中国海事水上巡航的现状和巡航模式作较全面的总结和分析,剖析存在的主要不足,综合考虑发展需求,指出中国海事水上巡航的发展趋势并提出相关建议。     

船舶遮蔽航区变更为沿海航区的检验要点

船舶如何从遮蔽航区升级改造为沿海航区是近期的热点话题。文章结合辖区内一艘自卸运砂船的航区变更检验工作,阐述自卸运砂船从遮蔽变更为沿海航区应重点考虑的问题以及检验要点,对船舶的航区变更检验工作有所帮助。     

Mortality through ontogeny of soft-bottom marine invertebrates with planktonic larvae

The present survey covers one spawning season of marine benthic invertebrates in a large geographical area, the inner Danish waters, and includes a wide range of habitats with steep salinity and nutrient load gradients. The loss ratios of soft-bottom marine invertebrates from one development stage to the next is calculated based on average abundances of pelagic larvae, benthic post-larvae and adults of Bivalvia, Gastropoda, Polychaeta and Echinodermata, with planktonic development. This gives a rough estimate of the larval and post-larval mortality. Loss ratios between post-larvae stage and adult stage (post-larval mortality) varies from 3:1 to 7:1 (71.2–84.9%) and loss ratios between larvae and post-larvae (larval mortality) and between larvae and adult, ranging from 7:1 to 42:1 (85.2–97.6%) and from 45:1 to 210:1 (97.8–99.5%), respectively. The results show a remarkable unity in loss ratios (mortality) between the mollusc taxa (Bivalvia and Gastropoda) at the phylum/class level. This similarity in loss ratios among the mollusc taxa exhibiting the same developmental pathways suggests that the mortality is governed by the same biotic and abiotic factors. Larval mortality is estimated to range from 0.10 d^− 1 to 0.32 d^− 1 for Bivalvia and ranging from 0.09 d^− 1 to 0.23 d^− 1 for Polychaeta. The species loss ratios combined with specific knowledge of the reproduction cycles give estimated loss ratios (mortality) between the post-larvae and the adult stage of 25:1 and 14:1 for the bivalves Abra spp. and Mysella bidentata. For the polychaete Pygospio elegans the loss ratio (larval mortality) between the larvae and the post-larval stage is 154:1 and between the post-larvae and the adult stage 41:1. For Pholoe inornata the loss ratio between post-larvae and adults is 7:1. The present results confirm that the larval stage, metamorphosis and settlement are the critical phase in terms of mortality in the life cycle for Bivalvia. Assuming steady state based on actual measurements of pelagic larval densities an estimated input to the water column of pelagic bivalve larvae is ranging from 10,930 to 17,157 larvae m^− 2 d^− 1 and for Polychaeta between 2544 and 3994 larvae m^− 2 d^− 1. These estimates seem to correspond to the reproductive capacity of the observed adult densities using life-table values from the literature.The potential settlement of post-larvae is 43 post-larvae m^− 2 d^− 1 for Bivalvia and 56 post-larvae m^− 2 d^− 1 for Polychaeta. The adult turnover time for Bivalvia is estimated to be 1.5 years and 2.1 years for Polychaeta. This exemplifies that species with short generation times may dominate in very dynamic transitional zones with a high frequency of catastrophic events like the frequent incidents of hypoxia in the inner Danish waters.     

浅析长江干线桥区水域安全管理

桥区水域,因其通航环境的特殊性、复杂性,被各海事机构作为安全管理的重点,尽管如此,仍然是事故易发或多发地。2007年“6·15”广东九江大桥事故产生的严重后果,给桥区安全管理敲响了警钟。文中结合实际工作针对长江干线桥区水域安全存在的问题进行了分析,提出了相应的安全对策和桥区安全管理重点的建议。     

世界钻井船市场发展现状

从钻井船的船龄结构、建造年份、船东、运营商、建造商,设计型式、作业水域、工作水深、钻井深度等方面论述了钻井船市场现状,展望了钻井船市场的未来发展。指出虽然在未来一两年内世界钻井船新船订造市场仍可能较为谨慎,但由于未来世界深海油气的开采对于钻井船的大量需求,钻井船建造市场的长期走势仍值得期待。     

Intrusions of eastern North Atlantic central waters and phytoplankton in the north and northwestern Iberian shelf during spring

The influence of intrusions of eastern North Atlantic central water (ENACW) in the north and northwestern Iberian shelf on phytoplankton composition and abundance and on particle-size distributions of seston was analyzed using data collected on three extensive cruises during spring 1991 and 1992. Water with temperature and salinity values between 12.20 and 13.86 °C and between 35.66 and 35.98 psu, respectively, characteristics of the subtropical type of ENACW (ENACW_t), was detected in the upper 100 m of the water-column in all cruises, but particularly in the western coast in 1992. The highest salinity values of this water were found near the surface (0–100-m depth) and in early spring 1992, while minimum salinity values, and also minimum geographical extension, were found in late spring in both years. Phytoplankton blooms concentrated in frontal areas between different water types, with maximum intensity and extension in early spring.Using temperature and salinity characteristics, samples were classified in four groups corresponding to the major water types found in the region: Bay of Biscay central water (BBCW), two segments of ENACW of different salinity and surface water influenced by continental runoff. This classification was significantly confirmed by three independent discriminant analyses using hydrographic and chemical (dissolved nutrients and chlorophyll) variables, phytoplankton species abundance variables and particle-size concentration of seston variables. Phytoplankton blooms related to the presence of saline waters were characterized by the dominance of either chain-forming diatoms or a mixture of diatoms and phytoflagellates and high concentrations of seston. The diatom species dominating in saline waters were typical of upwelling-induced blooms occurring generally during summer. Blooms occurring in waters influenced by runoff also contained diatoms but in lower numbers than those of saline waters. Nutrients were not exhausted in the region, suggesting that phytoplankton populations were still in active growth. These results are interpreted taking into account the known variability in water-mass formation and in the poleward current driving ENACW_t along the shelf, and indicate that saline intrusions are a major feature affecting the distribution and composition of plankton in the spring in the southern Bay of Biscay, thus enlarging to a wider spatial scale their reported influence on the pelagic ecosystem.