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41.
Simon J. Walker Thomas A. Schlacher & Monika A. Schlacher-Hoenlinger 《Marine Ecology》2007,28(4):435-445
Artificial reefs are spatially complex habitats and serve as good model systems to study patterns of community succession and the response of epibiota to environmental clines over small spatial scales. Here, we quantified spatial heterogeneity in community composition and diversity of fouling communities across a number of environmental gradients that included water depth, surface orientation of habitats, exposure to currents, and shelter. Assemblage structure was quantified by spatially replicated photo transects on a recently scuttled large navy ship off the East Australian coast, lying in 27 m of water. A rich assemblage of epifauna had colonized the wreck within a year, dominated by barnacles, sponges and bryozoans. Community structure varied significantly over small spatial scales of meters to tens of meters. Depth, surface orientation and exposure were the major environmental drivers. Assemblages were substantially less diverse and abundant on the deepest (23 m near the seafloor) part of the hull with residual antifouling paint, on sheltered surfaces inside the wreck, and on the sediment‐laden horizontal surfaces. Overall, the wrecks’ habitat complexity corresponds with small‐scale heterogeneity in the fouling communities. This study supports the notion that wrecks enhance local diversity and biomass within the habitat mosaic of their location, and habitat complexity may be an important mechanism for this, as demonstrated by the large spatial variability in the assemblages documented here. 相似文献
42.
以实际环境荷载作用下的实际海洋导管架平台结构为对象,研究了海洋平台结构在风,流,海冰等多荷载模式和多荷载工况下的优化设计的理论方法和应用技术,建立了结构尺寸优化,形状优化和拓扑优化问题的统一模型。计算结果反映出形状优化比尺寸优化所得设计更优,而拓扑优化的设计效果最好。不同的荷载工况对应的最优拓扑形式不同,因此在实际设计中应考虑实际的荷载工况,选取不同的拓扑形式。 相似文献
43.
Microbial Biomass Dynamics Along a Trophic Gradient at the Atlantic Barrier Reef off Belize (Central America) 总被引:2,自引:0,他引:2
Abstract. Recent findings indicate that heterotrophic bacteria and not phytoplankton are the most numerous biomass components even in the euphotic zone of oligotrophic, open oceans. In this study it was hypothesized that the microbial biomass components change within a few hundred meters as oligotrophic water flows across the reef and becomes enriched with nutrients. Along a trophic gradient, four stations at the Atlantic Barrier Reef off Belize (Central America) were sampled for microbial biomass components. Phytoplankton biomass (measured as chlorophyll a) ranged from the most oligotrophic station (St. 1) to the most eutrophic station (St. 4) from 6.9–415.5 μg CI"' (assuming a C:chl a ratio of 30): heterotrophic bacterial biomass increased 4-fold (from 10.1–46.4μg C 1-1 ), heterotrophic nanoflagellate (HNAN) biomass increased from 4.6-19ug C 1-1 , and cyanobacteria from 0.9-4.5 μg C-1-1 . Production estimates derived from seawater cultures revealed a 5-fold increase in bacterial production from the oligotrophic station (3.7 ug C 1-1 d-1 ) to the eutrophic St. 4 (17.8ug C-1-d1-1 )- Cyanobacterial production rose from 1.1–3.5ug C-1–d-1 and HNAN production from 0.65-1.13 μg C-1-1 -d-1 . While cyanobacteria contributed between 13 and 20% to the autotrophic plankton component in the oligotrophic waters, their contribution dropped to about 1 % at the eutrophic stations. 相似文献
44.
1 .IntroductionNowadays tremendous efforts have been devotedtothe analysis of randomseismic responses .Forexample ,American PetroleumInstitute (API) has declared that the analysis of randomseismic re-sponsesis a useful tool for safety inspection. Owing to the complexity of platformand randomness ofload,it is difficult to carry out the randomresponse analysis of a jacket platform. The conventionalrandomvibration methods ,such as square root of the sumof squares (SRSS) and complete quadratic… 相似文献
45.
46.
地震作用下的导管架海洋平台结构动力优化设计研究 总被引:3,自引:1,他引:3
把导管架海洋平台看作钢框架结构,并把优化方法用于结构的抗震设计中;以结构的总重量最小为优化目标,导管的平均直径和壁厚作为设计变量,考虑强度、刚度和稳定等约束条件。通过渤海BZ28—1油田储油平台为例进行了计算,计算结果表明,此方法对海洋平台的设计具有一定的参考意义。 相似文献
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48.
S型海洋重力仪是目前海洋重力测量中较为常用的一种仪器,其产品性能也逐步得到提高。介绍了进行全自动化控制升级后,最新引进的SⅡ型海洋重力仪使用中出现的稳定平台颤动故障现象及排除办法。 相似文献
49.
Xie Simei Hao Chunjiang Zou Bin Jing Qiyi Liao Xiaohong Sheng Xiaowen Zhang Canrong 《海洋学报(英文版)》2000,19(1):35-46
INTRODUCTIONTheSMSRPSisstalledontheshipnavigatingovertheseaandreceivessatellitecloudmapsatanytimetoprovidereliablereal-timedataofmeteorologyandocean.Itisanimportantequipmentforsafeguardofshipnavigation.Chinahasthousandsofoceanicships.Butalmostallships,withonlyveryfewexception,arenotstalledbySMSRPS.Thecausesareasfollows:1.Thetechniqueisverycomplicated.2.Thedevelopmentcostisveryhigh.3.Ifweintroduceforeignequipment,thecostistooexpensive.4.Foreignequipmentanditssoftwarearecompletelyclo… 相似文献
50.
A numerical procedure is described for predicting the motion and structural responses of tension leg platforms (TLPs) in waves. The developed numerical approach, in a TLP is assumed to be flexible instead of rigid, is based on a combination of the three dimensional source distribution method and the finite-element method. The hydrodynamic interactions among TLP members, such as columns and pontoons, are included in the motion and structural response analysis. Numerical results are compared with the experimental and numerical ones. The results of comparison confirmed the validity of the proposed approach. 相似文献