丙溴磷对二种海洋微藻的GPx活性及GSH、CAR含量的影响

实验以三角褐指藻和青岛大扁藻为材料 ,进行了丙溴磷农药对海洋微藻的抗氧化防御系统成份— GPx(glutatione Peroxidase)活性和 GSH(glutathione)、CAR(carotinoid)含量的影响研究 ,结果表明 ,在丙溴磷胁迫下 ,微藻的 GPx活性呈现下降趋势 ,GSH和 CAR含量也表现为下降趋势 ,并且胁迫的时间越长、胁迫的强度越大它们下降的幅度也越大。因此微藻细胞对抗氧化防御系统的能力被削弱 ,从而可能导致活性氧在体内的过量产生与积累 ,进而对藻细胞造成更大的伤害。     

Water wave interaction with a floating porous cylinder

The interaction of water waves with a freely floating circular cylinder possessing a side-wall that is porous over a portion of its draft is investigated theoretically. The porous side-wall region is bounded top and bottom by impermeable end caps thereby resulting in an enclosed fluid region within the structure. The problem is formulated based on potential flow and linear wave theory and assuming small-amplitude structural oscillations. An eigenfunction expansion approach is then used to obtain semi-analytical expressions for the hydrodynamic excitation and reaction loads on the structure. Numerical results are presented which illustrate the effects of the various wave and structural parameters on these quantities. It is found that the permeability, size and location of the porous region may have a significant influence on the horizontal components of the hydrodynamic excitation and reaction loads, while its influence on the vertical components in most cases is relatively minor.     

养殖水体营养状态及自净能力的分析

本文根据１９９７年２～１２月间对对虾 养殖水全的监测结果,应用营养指数法进行养殖水体的营养水平评价,结合自养指数对水体的自净能力进行分析。结果表明,养殖水体内具有较高的ＤＩＰ和ＣＯＤ是造成水体富营养化的主要因素。较高的Ｃｈｌ－ａ含量则是富营养化水体的表现。养殖池内水质状况同养殖周期和季节变更密切相关。养殖水体浮游值物和微生物的代谢偶联,是反映水体自净能力,保持水体稳定的基础。     

Effect of time step size and turbulence model on the open water hydrodynamic performance prediction of contra-rotating propellers

A growing interest has been devoted to the contra-rotating propellers (CRPs) due to their high propulsive efficiency, torque balance, low fuel consumption, low cavitations, low noise performance and low hull vibration. Compared with the single-screw system, it is more difficult for the open water performance prediction because forward and aft propellers interact with each other and generate a more complicated flow field around the CRPs system. The current work focuses on the open water performance prediction of contra-rotating propellers by RANS and sliding mesh method considering the effect of computational time step size and turbulence model. The validation study has been performed on two sets of contra-rotating propellers developed by David W Taylor Naval Ship R & D center. Compared with the experimental data, it shows that RANS with sliding mesh method and SST k-ω turbulence model has a good precision in the open water performance prediction of contra-rotating propellers, and small time step size can improve the level of accuracy for CRPs with the same blade number of forward and aft propellers, while a relatively large time step size is a better choice for CRPs with different blade numbers.     

Influence of the nodal tide on the morphological response of estuaries

The nodal tide causes a periodic variation in the mean tidal range, with a period of 18.6 years and amplitude of about 4% of the mean range. As the cross-sectional area of the channel in an estuary has been observed to be related to the tidal prism, such a variation of the tidal range can significantly influence the morphological development of tide-dominated estuaries. Field observations from the Humber Estuary in England confirm that there is indeed an 18.6 year cycle in the total water volume of the estuary. In this estuary, with a relatively small morphological time scale, the response to the nodal tide variation appears to dominate the long-term large-scale sediment budget changes of the estuary. The semi-empirical model ESTMORF was able to reproduce these observations, in terms of the observed amplitude and phase lag (relative to the variation of the tidal amplitude) of the morphological response. It also showed good agreement with the along estuary variation in both the magnitude and phase of the response. To examine the character of the response in more detail, a simplified analytical solution has been derived from the governing non-linear equations. This has been investigated in terms of the sensitivity of the model to the various model parameters and by comparison with the historic data. The results demonstrate how the system response is strongly dependent on the morphological time scale of the estuary. Furthermore, the response is not uniform but varies along the length of the estuary, being most marked at the mouth and decaying up estuary. When examining changes in geomorphological features, such as the intertidal area, an appreciation of the role of the nodal tide is shown to be essential if historic data are to be properly interpreted.     

Hydroelastic optimisation of a composite marine propeller in a non-uniform wake

The purpose of this paper is to optimise the hydroelastic performance of a composite marine propeller to reduce vibration and dynamic stress. A hydroelasticity method based on the finite element method (FEM) coupled with computational fluid dynamics (CFD) is used to simulate the composite marine propeller in a non-uniform wake. Composite blades can be considered as a cantilever-like laminated structure experiencing an unsteady hydrodynamic load and centrifugal force. The objective of the improved design is to minimise the vibratory hub loads. The ply angle and stacking sequence are considered as the design variables. The nonlinear periodic transient responses and vibration hub loads of the composite blade are obtained by solving coupled equations using the Newton–Raphson numerical procedure. Compared to the starting design of the propeller, the optimum solution results in a 49.6–70.6% reduction of the 7/rev hub loads.     

Bearing capacity of offshore umbrella suction anchor foundation in silty soil under varying loading modes

Considering the current disadvantages of present offshore wind turbine foundations, a novel anchor foundation with skirt and branches is proposed, called offshore umbrella suction anchor foundation (USAF). A series of experiments and numerical simulations were performed to explore the bearing capacity of the USAF under various kinds of loading modes. The bearing characteristics and the anchor–soil interactions are described in detail for horizontal static loading, horizontal cyclic loading, and an antidrawing (pullout) test in silty soil. In the static loading test, the load–deflection of the anchor under step loading was analyzed and the normalized curve of the load–deflection was obtained to determine the ultimate horizontal bearing capacity of the anchor under normal working conditions. Under horizontal cyclic loading, the relationship between the plastic cumulative deformation and cyclic number was determined. In addition, the responses of USAF were investigated for a low wave frequency and storm surges. In the drawing test, it was found that a “segmentation phenomenon” occurred during the test. Moreover, a method to identify the maximum antidrawing load of USAF was provided based on dynamic mechanics. The numerical results show that the use of anchor branches and skirt can enhance the bearing performance of USAF to a certain degree. However, the anchor branch has a slight positive influence on the bearing performance improvement. The USAF is not only similar to a stiff short pile, but a rotation occurs. The failure envelope under composite loading (V-M) was obtained and the changes associated with changes in the aspect ratio of the internal compartment were clarified.     

临清坳陷东部三叠系沉积岩地球化学特征及构造意义

碎屑沉积岩的物质组成对其形成的构造背景具有重要的指示作用。通过对临清坳陷东部三叠系碎屑沉积岩样品地球化学主量和微量元素分析表明：三叠系岩石样品主要为成熟度较低的杂砂岩和长石砂岩;碎屑沉积岩的母岩总体上与大陆地壳组成基本一致,原岩以沉积岩和花岗岩为主;临清坳陷东部中生代早—中三叠世处于靠近大陆岛弧的活动大陆边缘构造环境,其动力学机制与早期秦岭洋壳向华北板块俯冲、晚期扬子板块和华北板块碰撞作用有关。研究结果为确定三叠纪时期华北东部南侧的构造环境提供了地球化学方面的证据。     

CMIP5模式对中国近海海表温度的模拟及预估

基于观测和再分析资料;利用多种指标和方法评估了国际耦合模式比较计划（CMIP5）中21个模式对中国近海海温的月、季节和年际变化模拟能力。多模式集合能够再现气候平均意义下近海海温的空间分布特征;但量值上存在一定的低估。在渤海和黄海;集合平均与观测差别比较明显。在年际尺度上;与观测数据对比;模式模拟海温与Niño3指数相关性较小。中国近海海表面温度在1960-2002年有明显的升高趋势;从2003年开始增温趋缓。评估结果表明;ACCESS1.0、BCC-CSM1.1、HadGEM2-ES、IPSL-CM5A-MR、CMCC-CM、FGOALS-g2、CNRM-CM5-2、INMCM4八个模式对中国近海海温的变化有较好的模拟能力。利用ACCESS1.0、INMCM4、BCC-CSM1.1、IPSL-CM5A-MR、CMCC-CM这5个模式结果对中国近海海温未来的变化进行了预估。在RCP4.5、RCP8.5情景下;未来近100年中国近海海温有明显升高趋势;最优模式多模式集合平均增温分别可达到1.5℃、3.3℃;净热通量变化和平流变化共同促进了东海升温。