Diet of albacore Thunnus alalunga from the waters of Mauritius (western Indian Ocean) inferred from stomach contents and fatty acid analysis

The diet of albacore Thunnus alalunga from their spawning ground in the waters of Mauritius was investigated. The stomach contents of 249 albacore individuals, caught by industrial longliners and artisanal fishers, was analysed, and the dominant prey taxa were selected for lipid and fatty acid (FA) analysis. The FA profiles of prey were compared with those of liver tissue of spawning-capable and post-spawning female albacore, using multivariate analysis. Whereas stomach content analysis identified cephalopods and crustaceans as the dominant prey items in number, FA-profile analysis identified crustaceans and fishes as the most-frequently consumed prey of post-spawning female albacore. In contrast, the FA profiles of spawning-capable albacore and those of prey showed very low similarity. Analysis of the prey suggests that although cephalopods, crustaceans and fishes could all provide albacore with the required lipids and FAs, cephalopod prey seem to be less desirable owing to their lower energy content (i.e. low in total lipid, triacylglycerol, 16:0, 18:0 and 18:1ω9). Instead, the most beneficial food appeared to be locally available fishes, which are more energy-rich and have a higher docosahexaenoic acid/ eicosapentaenoic acid ratio. These results provide new information on the trophic ecology of albacore, promote our understanding of the importance of prey type for successful reproduction of albacore, and highlight the advantages of FA profiling to study diet.     

Distribution characteristics of zooplankton biomass in the East China Sea

On the basis of the data of oceanographic survey in the East China Sea in four seasons during 1997-2000 (23°30'~33°00'N, 118°30'-128°E), the variation of total biomass and diet biomass of zooplankton and their spatial-temporal distribution and relationship with the fishing ground of Engraulis japonicus are approached and analyzed. The results show that the average biomass is 65.32 mg/m3 in four seasons, autumn (86.18 mg/m3) being greater than summer (69.18 mg/m3) greater than spring (55.67 mg/m3) greater than winter (50.33 mg/m3). The average value of diet zooplankton biomass is 40.9 mg/m3. The trends of horizontal distribution both in the total biomass and the diet biomass of zooplankton are similar. The high biomass region (250-500 mg/m3) is very limited, only accounting for 1% of the investigation area. Seasonal variation of the biomass is very remarkable in the west and north parts of East China Sea coastal waters ( 29°30'N,125°E). The horizontal distribution of diet zooplankton depends on the     

高速摄影对散体振动的研究

以现代高速摄影技术和图像分析以及数据处理方法，针对高效振动磨机中弹性散体工质（如钢棒、球体等）的振动力学进行了深入的探讨和分析，为研究散体动力学和振动超细粉碎过程中的能量分布和传递规律以及能量与物质的相互转换机理奠定了基础，也为相关学科的发展提供了一种可以借鉴的方法。     

东海西北部水团分析及与渔场的关系

作者用聚类分析法划分浅海水团,目的在于克服大洋水团分析法进行分析所遇到的一些困难,它在根据不同海区特点确定临界值与检验值时有较大的灵活性。本文讨论了浅海变性水团与中心渔场的关系。结果表明,东海底层冷水、东海表层水和大陆沿岸水对渔业生产有重要影响。     

Analytic Solution of Interaction Between Surface Waves and Floating Elastic Plates with Elastic End-Restraints

Based on the dynamic theories of water waves and Mindlin plates,the analytic solution of interaction between surface waves and two-dimensional floating elastic plates with edge-restraint is constructed by use of the Wiener-Hopf technique.Firstly,without regard for elastic edge restraint,the wave-induced responses of elastic floating plate analyzed by the present method are in good agreement with the results from literature and experimental results.Therefore,it can be shown that the present method is valid.Secondly,three end-restraint cases(i.e.,the left-end elastic restraints,the both-end elastic restraints,and the right-end elastic restraints)are proposed to reduce the vibration of floating plates,in which the spring is used to connect the sea bottom and the floating plate's left(or right)edge.The relations between the spring stiffness and the parameters of wave-induced responses of floating plates are discussed.Moreover,the effective method to reduce the vibration of floating elastic plates can be obtained through comparison.     

东白令海的刺黄盖鲽渔场海洋学与渔业生物学特征

本文概述了东白令海形成刺黄盖鲽渔场的海洋学特征,并结合现场调查的标样侧重分析了刺黄盖鲽的渔业生物学特征,本文还概略地讨论了该鱼与渔业资源的关系。     

Action mechanism of geotextile-reinforced cushion under breakwater on soft ground

Various measures including material experiments, centrifuge modeling tests and FEM numerical analyses were performed to study systematically the action mechanism of the geotextile-reinforced cushion under breakwater on soft ground and the effects of the strata characterization and the reinforcement condition on the stability of the breakwater-ground system. In the aspect of controlling the deformation, the geotextile-reinforced cushion under breakwater constrains the lateral displacement of both the embankment and the ground. From the viewpoint of stress, the reinforcement suppressed the range of high stress level in the system. In general, the weaker the ground is and the greater the modulus of the geotextile is, the more effective the reinforcement is. The tensile force in the geotextile is greater in the range of the main part of the embankment.     

The Effect of Internal Fluid on the Response of Vortex-Induced Vibration of Marine Risers

Based on Iwan‘s wake oseillator model developed with the classical van der Pol equalion, the differential equation for the response of the vortex-induced vihration (VIV) of the riser considering the effect of the internal flowing fluid and the external marine environmental condition is derived. The effect of the intermal flowing fluid on the response of VIV of the riser is studied by means of the Finite Element Method. The results show that the effect of the internal fluid velocity on the VIV of the riser is strong when the natural frequency of the riser is close to the vortex shedding frequency. In addition, the increase of the top tension can decrease the sensitivity of the riser to the internal fluid velocity.     

软土海岸地区测量控制点标志的设立

分析了软土、湿地、滩涂地区特殊地理环境对测量控制点的影响;主要探讨了此类地区控制点标志的设计、施工。借助于建筑桩基技术和道桥施工方法,首次成功实现了某三角洲湿地滩涂地区统一布网。几年来,结合滩涂湿地测量、海岸防护和滩涂开发工程对部分控制点进行了初步检测,给出了部分检测数据。应用和检测均表明:桩基标石可较好地解决软土、湿地、滩涂地区控制点布设难题,显著提高软土海岸地区测量控制点标志的稳固性,从而延长控制网的可使用期。