Top hat stiffeners: A study on keel failures

The need to assess the structural capability of curved marine composite structures that support the keel of high performance yachts has increased due to the rise in the number of accidents and human casualties. The top hat stiffener is the basic structural member of the yacht to sustain the tensile and bending load of the keel. This paper characterises the mechanical strength of E-glass/vinylester composite top hat stiffeners subjected to transverse loading. The out-of-plane load transfer was studied and failure modes were identified for the three different composite layups which were tested to failure. Experimental results obtained from mechanical testing were compared with FEA predictions, based on the quadratic interlaminar stress criterion. Secondary reserve strength from the unidirectional fibres was identified and the potential to use this secondary strength was further investigated.     

高岭土对聚丙烯酰胺静吸附与动滞留的影响

在三次采油领域里,吸附滞留量是影响化学剂驱油效果的关键因素之一。结合现场实施注聚采油工艺出现的各种问题,在基础理论的指导下,通过室内模拟实验45℃条件下,利用淀粉-碘化镉比色法研究了聚丙烯酰胺水溶液在不含油石英砂中的静态吸附及人造均质岩心中的动态滞留规律,并考察了高岭土对其滞留量产生的影响。实验结果表明,吸附等温线基本符合S型,溶液浓度在1 200 mg/L附近达饱和吸附;高岭土的存在使聚合物在石英砂中的吸附量及岩心中的滞留量增加,随着高岭土含量的增加,吸附滞留量由0.353 mg/g增加到0.794 mg/g。相同实验条件下,吸附量要远远多于滞留量。     

万能体积公式

证明并验证了由数值积分的辛普松（Ｓｉｍｐｓｏｎ） 公式直接导出的公式（２） 可以求柱、锥、台球等基本几何体积公式,所以将其称作万能体积公式     

1990-2019年咸海水量平衡及其影响因素分析

咸海地处中亚,气候和人类的双重影响下湖面急剧萎缩引发区域生态危机,定量解析其水量平衡互动关系及影响因素对咸海地区水资源管理和生态保护有重要意义.基于1990-2019年密集时序Landsat影像、T/P卫星、Jason1/2测高卫星及咸海数字测深模型(DBM),提取近30年咸海面积、水位变化信息,重建咸海水位-面积-库...     

印尼贯穿流与南海贯穿流的年代际变化特征及机制

通过绕岛环流理论和SODA(Simple Ocean Data Assimilation)数据对印尼贯穿流(ITF)和南海贯穿流(即吕宋海峡水交换,LST)在1976年气候突变前后的特征进行分析。结果表明,1976年后吕宋海峡水交换体积输送(LSTT)异常增大,而印尼贯穿流体积输送(ITFT)异常减少。吕宋海峡东部东风分量和南海内部的北风分量的局地驱动是导致LSTT在1976年后增加的主要因素,南海内部异常北风分量对LSTT增加的贡献能够达到53%;而赤道太平洋的西风分量则是导致ITFT在1976年后减少的主要因素,其贡献大约为61%。1976年后15°N左右的NEC(North Equatorial Current)体积输送异常增强,但总NEC体积输送异常减弱。KC(Kuroshio Current)体积输送异常增强,而MC(Mindanao Current)、NECC(North Equatorial Countercurrent)、SEC(South EquatorialCurrent)体积输送异常减弱。赤道西太平洋由风场变化通过Sverdrup动力过程产生的异常气旋性环流阻碍了太平洋水体向印度洋的输入。     

利用ADCP和LISST-100仪观测悬浮物浓度的研究

利用黄河口海床基声学多普勒流速剖面仪(ADCP)的周日观测资料对悬浮物浓度进行了反演,反演过程中综合考虑了球面扩散、声学近场的非球面扩散、海水和悬浮颗粒的吸收衰减以及其他因素对回声信号的影响,结果表明在粒径保持相对稳定的情况下,利用ADCP仪回声强度反演悬浮物浓度具有较高的精度.结合现场激光粒度仪(LISST-100)测得的粒径分布信息在反演过程中考虑了粒径修正,重点讨论了观测区域粒径变化对结果的影响,结果表明粒径的剧烈变化会降低体积后向散射强度与悬浮物浓度之间的相关性.大颗粒物质的存在使计算得到的悬浮物浓度偏高,粒径修正虽然在一定程度上消除了这种影响,但线性拟合的相关性并未提高.     

Finite volume approach for finite strain consolidation

The paper presents the finite volume formulation and numerical solution of finite strain one‐dimensional consolidation equation. The equation used in this study utilises a nonlinear continuum representation of consolidation with varying compressibility and hydraulic conductivity and thus inherits the material and geometric nonlinearity. Time‐marching explicit scheme has been used to achieve transient solutions. The nonlinear terms have been evaluated with the known previous time step value of the independent variable, that is, void ratio. Three‐point quadratic interpolation function of Lagrangian family has been used to evaluate the face values at discrete control volumes. It has been shown that the numerical solution is stable and convergent for the general practical cases of consolidation. Performance of the numerical scheme has been evaluated by comparing the results with an analytical solution and with the piecewise piecewise‐linear finite difference numerical model. The approach seems to work well and offers excellent potential for simulating finite strain consolidation. Further, the parametric study has been performed on soft organic clays, and the influence of various parameters on the time ate consolidation characteristics of the soil is shown. Copyright © 2015 John Wiley & Sons, Ltd.     

A moving‐mesh finite‐volume method to solve free‐surface seepage problem in arbitrary geometries

The main objective of this work is to develop a novel moving‐mesh finite‐volume method capable of solving the seepage problem in domains with arbitrary geometries. One major difficulty in analysing the seepage problem is the position of phreatic boundary which is unknown at the beginning of solution. In the current algorithm, we first choose an arbitrary solution domain with a hypothetical phreatic boundary and distribute the finite volumes therein. Then, we derive the conservative statement on a curvilinear co‐ordinate system for each cell and implement the known boundary conditions all over the solution domain. Defining a consistency factor, the inconsistency between the hypothesis boundary and the known boundary conditions is measured at the phreatic boundary. Subsequently, the preceding mesh is suitably deformed so that its upper boundary matches the new location of the phreatic surface. This tactic results in a moving‐mesh procedure which is continued until the nonlinear boundary conditions are fully satisfied at the phreatic boundary. To validate the developed algorithm, a number of seepage models, which have been previously targeted by the other investigators, are solved. Comparisons between the current results and those of other numerical methods as well as the experimental data show that the current moving‐grid finite‐volume method is highly robust and it provides sufficient accuracy and reliability. Copyright © 2007 John Wiley & Sons, Ltd.     

A HOMOGENEOUS MODEL OF UPPER LAYER CIRCULATION IN INDO-PACIFIC REGION

ImODUcrIONTheIndo-PadricregionbeweenMindanao,NewGuinea,andtheIndonesianArchipelagoistheonlydeeppassagefromthePadricOceantotheIndiandrincyig.l),Fig.lMapoftheIndoThdficopon(Internalframeisthemodeldomain)andobendupper1aperimtSthereinsmrandhasareivedconsiderableattentionhauseofitSlocationbetweretheIn.TheIndonesianThappearstobepotentiallyboortantintheevoluhonsofthewesternboundaryatandthewarmpoolinthewesternPadric,andplaysacrudelroleinthehcatandsaltbalanceoftheworkl'soasnoprdon,l986).Nume…     

气象服务市场问题研究

本文从社会主义市场经济要求出发,以气象科技成果商品化、产业化为背景,以气象服务市场的培育为经纬,对气象服务市场的特性、作用、现状、发育条件等方面进行若干理论分析,进而提出加快培育我国气象服务市场战略的对策性思考。