Improving the prediction of extreme FPSO hawser tension,using another highly correlated hawser tension with a longer time record     

《Applied Ocean Research》2019

The floating production storage and offloading unit (FPSO) is an offshore vessel that produces and stores crude oil prior to tanker transport. Robust prediction of extreme hawser tensions during the FPSO offloading operation is an important safety concern. Excessive hawser tension may occur during certain sea conditions, posing an operational risk. In this paper, the finite element method (FEM) software ANSYS AQWA has been employed to analyze vessel response due to hydrodynamic wave loads, acting on a specific FPSO vessel under actual sea conditions.In some practical situations, it would be useful to improve the accuracy of some statistical predictions based on a certain stochastic random process, given another synchronous highly correlated stochastic process that has been measured for a longer time, than the process of interest. In this paper, the issue of improving extreme value prediction has been addressed. In other words, an efficient transfer of information is necessary between two synchronous, highly correlated stochastic processes. Two such highly correlated FPSO hawser tension processes were simulated in order to test the efficiency of the proposed technique.  相似文献   

浮游植物metacaspase的分布、结构及其功能特性     

苏金净  蔡伟聪  李桂玲  李健  曾珺  刘静雯 《海洋与湖沼》2019,50(5):1059-1069

精氨酸/赖氨酸特异性半胱氨酸蛋白酶(Metacaspase)在浮游植物程序性细胞死亡(programmed cell death.PCD)过程中起着关键作用。本文利用生物信息学方法分析metacaspase基因在浮游植物中的分布,并以海洋球石藻(Emilianiahuxleyi)metacaspases(EhMCs)为代表分析其结构和功能,依据Uniprot和String数据库挖掘与metacaspase功能相关并参与浮游植物PCD过程的互作蛋白。结果发现:共计29条、四种类型的metacaspases分布于11种浮游植物中,它们的metacaspase蛋白一级结构存在明显差异,但位于p20的组氨酸和半胱氨酸活性位点均具有高度的保守性;EhMCs三级结构与酵母的metacaspase十分相似,暗示它们具有类似的功能;浮游植物metacaspases与多种蛋白存在直接或间接的互作关系,在细胞PCD过程、响应环境胁迫和能量代谢等方面发挥重要作用。另外.metacaspase的磷酸化修饰可能在浮游植物PCD信号转导过程中起调节作用。  相似文献   

国土空间规划中水源涵养功能生态保护红线备选区的识别     

李萌  王传胜  张雪飞 《地理研究》2019,38(10):2447-2457

水源涵养功能重要性是生态保护红线划分工作中重要的评价指标之一。通过对以往生态系统水源涵养功能区划分的指标及其区域导向的系统梳理,在进一步明晰国土空间规划中水源涵养功能生态保护红线区域指向的基础上,按照国土空间规划关于“三区三线”自下而上试划的要求,探讨了水源涵养重要性生态保护红线划分及其评价的改进方法。选取中国典型喀斯特区域六盘水市作为研究案例区,分别用环保部2015版与2017版《生态保护红线划定技术指南》中的模型法、NPP法以及本研究提出的改进方法,对六盘水市水源涵养功能生态保护红线进行了试划。对比三种方法的划定结果可以看出,改进方法因评价数据精度的提高减少了《生态保护红线划定技术指南》方法的区域损失,提高了区域判别的精准性,可望为国土空间规划中生态保护红线的划定提供科学依据。  相似文献   

Dynamic response of a pile considering the interaction of pile variable cross section with the surrounding layered soil          下载免费PDF全文

Liu Gao  Kuihua Wang  Si Xiao  Wenbing Wu 《国际地质力学数值与分析法杂志》2017,41(9):1196-1214

Assuming that the pile variable cross section interacts with the surrounding soil in the same way as the pile toe does with the bearing stratus, the interaction of pile variable cross section with the surrounding soil is represented by a Voigt model, which consists of a spring and a damper connected in parallel, and the spring constant and damper coefficient are derived. Thus, a more rigid pile–soil interaction model is proposed. The surrounding soil layers are modeled as axisymmetric continuum in which its vertical displacements are taken into account and the pile is assumed to be a Rayleigh–Love rod with material damping. Allowing for soil properties and pile defects, the pile–soil system is divided into several layers. By means of Laplace transform, the governing equations of soil layers are solved in frequency domain, and a new relationship linking the impedance functions at the variable‐section interface between the adjacent pile segments is derived using a Heaviside step function, which is called amended impedance function transfer method. On this basis, the impedance function at pile top is derived by amended impedance function transfer method proposed in this paper. Then, the velocity response at pile top can be obtained by means of inverse Fourier transform and convolution theorem. The effects of pile–soil system parameters are studied, and some conclusions are proposed. Then, an engineering example is given to confirm the rationality of the solution proposed in this paper. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

Local Oceanic Vertical Deflection Determination with Gravity Data Along a Profile     

Jianbo Wang  Xin Liu  Yi Shen  Qiaoli Kong 《Marine Geodesy》2018,41(1):24-43

Deflections of the vertical (DOVs) over oceans cannot be directly measured, which restricts their applications. A local covariance function of anomalous potential is put forward in this paper in conjunction with the least-squares collocation (LSC) method to compute the oceanic DOVs utilization of oceanic gravity data along a profile. The covariance functions of gravity field quantities have been derived directly as functions of x, y and z without the need to introduce coordinate transformations corresponding to along- or cross-profile components. In the proposed methodology, gravity data along a profile were used to calculate the residual gravity anomaly using the remove-compute-restore technique. The residual gravity anomaly was used to calculate the parameters of the proposed covariance function of the local anomalous gravity field, which was used in the LSC to compute the residual DOVs along the profile. The residual DOVs added model DOVs to recover the DOVs along the profile. The results of a simulation experiment prove that the proposed methodology is feasible and effective.  相似文献   

基于核函数NPSSB模型的HY-2A卫星雷达高度计海况偏差研究     

张洁  田杰  王兆徽 《海洋预报》2020,37(1):1-10

利用机器学习的方法,对14个周期HY-2A卫星高度计数据:风速、有效波高和海面高度差值进行训练,探究海况偏差和风速、有效波高之间的关系,创建海况偏差核函数非参数模型(NPSSB),并与参数模型中具有代表性的BM3、BM4模型进行对比。研究表明:(1)核函数NPSSB模型能够很好的反映SSB与U、SWH之间的关系,SSB与U呈二次函数关系,SSB与SWH呈反比例函数关系;(2)核函数NPSSB模型对SSB的模拟能力与训练数据集相关,数据量越多,模拟能力越好;(3)核函数NPSSB模型与BM3、BM4模型都存在0^-0.03 m的差值,随着风速和有效波高的增加,差值的绝对值越大。  相似文献   

Linking tracers,water age and conceptual models to identify dominant runoff processes in a sparsely monitored humid tropical catchment          下载免费PDF全文

Christian Birkel  Chris Soulsby 《水文研究》2016,30(24):4477-4493

Assessing catchment runoff response remains a key research frontier because of limitations in current observational techniques to fully characterize water source areas and transit times in diverse geographical environments. Here, we report a study that combines empirical data with modelling to identify dominant runoff processes in a sparsely monitored humid tropical catchment. The analysis integrated isotope tracers into conceptual rainfall–runoff models of varying complexity (from 5 to 11 calibrated parameters) that are able to simulate discharge and tracer concentrations and track the evolving age of stream water exiting the catchment. The model structures can be seen as competing hypotheses of catchment functioning and were simultaneously calibrated against uncertain streamflow gaugings and a 2‐year daily isotope rainfall–runoff record. Comparison of the models was facilitated using global parameter sensitivity analysis and the resulting effect on calibration. We show that a variety of tested model structures reproduced water and tracer dynamics in stream, but the simpler models failed to adequately reproduce both. The resulting water age distributions of the tested models varied significantly with little similarity between the stream water age and stored water age distributions. The sensitivity analysis revealed that only some of the more complex models (from eight parameters) could be better constrained to infer more plausible water age distributions and catchment storage estimates. These models indicated that the age of water stored in the catchment is generally older compared with the age of water fluxes, with evapotranspiration age being younger compared with streamflow. However, the water age distributions followed a similar temporal behaviour dominated by climatic seasonality. Stream water ages increased during the dry season (greater than 1 year) and decreased with increased streamflow (a few weeks old) during the wet season. We further show that the ratios of the streamwater age to stored water age distribution and the water age distribution of actual evapotranspiration to the stored water age distribution from constrained models could potentially serve as useful hydrological indicators of catchment functioning. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Displacement analytical prediction of shallow tunnel based on unified displacement function under slope boundary     

Fanchao Kong  Dechun Lu  Xiuli Du  Chenpeng Shen 《国际地质力学数值与分析法杂志》2019,43(1):183-211

For slope condition of ground surface, the asymmetrical deformation about the vertical center line and the horizontal center line of the tunnel cross section can be formed. A unified displacement function expressed by the Fourier series is presented to express the asymmetrical deformation of the tunnel cross section. Five basic deformation modes corresponding to the expansion order 2 are a complete deformation mode to reflect deformation behaviors of the tunnel cross section under slope boundary. Such this complete displacement mode is implemented into the complex variable solution for analytically predicting tunneling-induced ground deformation under slope boundary. All of these analytical solutions are verified by good agreements of the comparison between the analytical solutions and finite element method results. A parameter study is carried out to investigate the influence of deformation modes of the tunnel cross section, geometrical conditions of the tunnel and the slope angle, and “Buoyancy effect” on the displacement field. Finally, the proposed method is consistent with measured data of the Hejie tunnel in China qualitatively. The presented solution can provide a simplified indication for evaluating the ground deformation under slope condition of ground surface.  相似文献   

海洋脊椎动物甲状腺系统的研究与应用     

杨皓月  邢荣娥  刘松  于华华  李鹏程 《海洋科学》2020,44(8):118-129

甲状腺（Glandula thyreoidea）是海洋脊椎动物体内重要的内分泌腺，从海洋脊椎动物开始，才有了独立的甲状腺结构。海洋脊椎动物的甲状腺一般为实质性的组织。实质由甲状腺滤泡组成，构成滤泡的上皮细胞合成、贮存和分泌的甲状腺激素是调节机体生长发育的关键激素。从海洋脊椎动物开始才有了独立的甲状腺结构。对于动物甲状腺的研究多集中在甲状腺形态及甲状腺与生长发育关系方面，而对海洋脊椎动物的甲状腺的研究则越来越多的集中于环境因素所引起的甲状腺病变方面，环境因素对甲状腺功能的影响也逐渐成为科学研究的重点。海洋水体污染导致的甲状腺机能受损，使海洋脊椎动物不能正常生长发育，数目与种类骤减之时，我们不得不重视对海洋脊椎动物甲状腺的研究。  相似文献   

国土空间规划的海洋分区研究   总被引：2，自引：0，他引：2  

周鑫  陈培雄  黄杰  王权明 《海洋通报》2020,39(4):408-415

国土空间分区作为国土空间规划编制和自然资源统一管理的基础，对整个规划体系具有重要的支撑作用。在统一的国土空间规划体系下，用海分区既有其独立性与特殊性，也面临着陆海统筹、生态文明建设、海洋高质量发展等政策提出的 新要求。文章系统梳理了 1983 年以来海洋功能分区体系 4 次演变历程，结合国土空间规划改革对分区体系的内在需求，指出海洋功能分区体系存在未覆盖海域全域，分区层级的尺度、分工、内容和结构与国土空间规划的要求不一致，分区方案未考虑用途管制的需求，以及陆海统筹不足等问题。在剖析现有各类规划政策分区、管制分区和功能分区在国土空间规划体系中的定位和作用的基础上，提出以海洋主体功能区为基础，海洋生态红线为底线，以原海洋功能区划分区为主体，将无居民海岛纳入规划范围，并在生态、农业、城镇空间的大框架下统筹协调海陆分区，形成国土空间规划中的海洋分区体系。全国和省级国土空间规划统筹海陆主体功能，划定主体功能区，并建立海洋产业保障区名录、无居民海岛保护与利用名录和海洋自然保护地名录。市县级国土空间规划划定“功能+管制”的利用分区，共划分出海洋保护区、海洋发展区和海洋保留3个一级分区以及核心保护区、一般控制区、海水增养殖区等 12 个二级分区。  相似文献