屈曲利用因子约束下船体板架结构优化设计方法     

韩涛  汪俊泽  王元  易家祥  吴嘉蒙  程远胜  刘均 《海洋工程》2021,39(3):42-50,134

船体板架结构在屈曲约束下的优化问题具有变量多和约束多的特点,且屈曲计算需借助有限元分析,属于大规模耗时优化问题,运用常规优化方法求解需要较高的计算成本。这里提出一种适用于屈曲约束下船体板架快速优化方法,该方法利用板格屈曲利用因子具有局部性的特点,对板格厚度自变量空间进行降维处理;利用板格屈曲利用因子对板格厚度具有单调性的特点,采用牛顿迭代方法求解其达到目标值的板格厚度;同时比较板格在相同重量增量下,加筋叠加板厚与仅加板厚对屈曲利用因子改善程度的大小决定是否加筋;通过两阶段的迭代寻优,快速获得最优的板厚以及防屈曲筋布置方案。某油船双层底优化结果显示,该方法能够在30步之内完成优化计算,优化效率高;优化方案相比原始方案减重达17.63%,绝大部分板格屈曲利用因子取值在0.9～1.0之间,材料得到充分利用。  相似文献   

Experimental and analytical investigations of steel panel dampers for seismic applications in steel moment frames     

《地震工程与结构动力学》2018,47(6):1416-1439

A ductile Vierendeel frame can be constructed by incorporating steel panel dampers (SPDs) into a moment‐resisting frame (MRF). Thus, the stiffness, strength, and ductility of the lateral force–resisting system can be enhanced. The proposed 3‐segment SPD possesses a center inelastic core (IC) and top and bottom elastic joints. This paper discusses the mechanical properties, capacity design method, and buckling‐delaying stiffeners for the SPDs through the use of cyclic loading tests on 2 specimens. Tests confirm that SPDs' cyclic force vs deformation relationships can be accurately predicted using either the Abaqus or PISA3D model analyses. The paper also presents the capacity design method for boundary beams connected to the SPDs of a typical SPD‐MRF. The seismic performance of an example 6‐story SPD‐MRF is evaluated using nonlinear response history analysis procedures and 240 ground accelerations at 3 hazard levels. Results indicate that under 80 maximum considered earthquake ground accelerations, the mean‐plus‐one standard deviation of the shear deformation of the ICs in the SPDs is 0.055 rad, substantially less than the 0.11 rad deformational capacity observed from the SPD specimens. The experimental cumulative plastic deformation of the proposed SPD is 242 times the yield deformation and is capable of sustaining a maximum considered earthquake at least 8 times before failure. This paper introduces the method of using one equivalent beam‐column element for effective modeling of the 3‐segment SPD. The effects of the IC's relative height and stiffness on the overall SPD's elastic and postelastic stiffness, elastic deformation limits, and inelastic deformational demands are discussed.  相似文献   

Propulsive performance of a tanker hull form in damaged conditions     

Jiman Yang  Hyochul Kim 《Ocean Engineering》2009,36(2):133-144

Many disastrous oil spill accidents from damaged vessels become worse especially when the early treatment is not prompt enough. To properly handle this type of accidents and prevent further disasters, International Maritime Organization establishes and imposes various rules and regulations. Better understanding of the propulsive performance of damaged vessels is important for containing the oil spill while the vessels are being towed or self-propelled. In the present study, both experimental and computational methods were used to investigate the flow phenomena around the hull and the hydrodynamic performances of a VLCC in various damaged conditions. From the resistance and self-propulsion test results, it is found that higher power is required to propel the ship especially with the bow trim. Wake measurement data provide physical insight into the factors to be considered for the propeller operation in damaged conditions.  相似文献   

中国与OECD在非援助国别分配的空间关系研究     

邵静  王茂军 《地理科学进展》2020,39(5):766-778

中国在非援助规模持续扩大,在打破原有援助格局的同时,其援助行为日益受到国际社会的关注,但现有研究较少关注中国和经济合作与发展组织(Organization for Economic Co-operation and Development,OECD)之间的空间关系。论文利用2000—2012年中国对非援助(Aid)与OECD对非援助(ODA)在非洲44个国家的数据,对比分析了二者的时间推移及国别分配特征,构建Aid和ODA静态面板模型,定量识别了二者的空间趋同关系。主要结论如下：① 援助金额大幅增加,时序相关性明显,受援国规模位序升降趋同,时间推移上呈同步性;② 地理匹配度高,重点援助国高度雷同,空间分布上呈同质性;③ Aid与ODA间存在稳健、显著的正向关系,响应方式具有一致性,但Aid对ODA响应程度更为敏感、强烈;④ 人均GDP和营养不良发生率是影响援助的2个强有力的因素,影响机制具有相似性。  相似文献   

新型干树式半潜平台浮体结构设计研究     

李建勋  凌进  王仁军  郁芳  刘木南  唐修俊  王中念 《海洋工程》2019,37(1):12-19

为适应中国南海深水区域的油气田开发,研发出了一种具有渐变式立柱的深吃水干树式半潜钻井/生产平台(TCDDSemi)。平台的浮体采用了深吃水、变截面长立柱构型,即向底部逐渐扩大的渐变截面形式。结合干树式深吃水半潜平台的研发过程,通过采用压缩空气压载系统、全注水下浮体、压缩空气水密检测以及水密面板的三级正交加强筋设计等新兴技术,极大地提高了钢材的利用效率,达到了节省材料、减轻浮体自重的目的。对浮体的有限元(FEM)整体分析结果表明,浮体结构设计满足各工况强度要求。  相似文献   

基于DEA-Malmquist-Tobit模型的中国海洋渔业补贴财政效率及影响因素研究     

郑慧  高凡  赵昕 《海洋通报》2020,39(1):61-69

作为世界上最大的渔业生产国和贸易国,中国渔业补贴政策的制定和实施对国计民生具有重大意义,也是推进海洋强国战略建设的题中应有之义。本文选取基于规模报酬可变假设的DEA模型测算了中国海洋渔业补贴的效率水平,进一步利用Malmquist指数对补贴效率的动态变化进行分解,探究效率变化的内在驱动因素,然后建立分析补贴效率影响因素的面板Tobit模型,对补贴投入和环境变量对补贴效率的影响进行分析,结果表明,当前我国海洋渔业补贴效率整体较低,且全要素生产率呈下降趋势,最后基于实证结果从改善补贴规模和调整产业结构等方面提出改善渔业补贴效率的对策建议。  相似文献   

A Framework for Teaching,Learning, and Assessing Environmental Issues     

《The Journal of geography》2012,111(4-5):161-166

Abstract

A twelve-question framework for teaching, learning, and assessing environmental issues was created through analysis of environmental textbooks and interviews with professors and researchers who specialize in the environment. Concepts in the framework include: causes, scale, spatial distribution, longevity, consequences, risks, economic implications, solutions, obstacles, social values, stakeholders, political status, behavior changes, and personal actions. The twelve-question framework was submitted to a validity panel of geographers. Statistical analysis of responses from the panel indicates that the framework is valid.  相似文献   

The mechanism of pollution-intensive industry relocation in Guangdong Province,2000～2009     

《地理研究》2012,31(2)

全球化背景下污染密集型产业的跨国和跨地区转移成为研究的热点问题。本文采用2000～2009年广东省21个地级市的统计数据,发现其污染密集型产业其呈现＂S＂型的时间发展特征和＂分散-集中-分散＂的空间发展特征,说明广东省污染密集型产业存在空间转移的现象。建立面板数据模型分析产业空间转移的影响机制,得出如下结论：一是国际产业转移主要采取污染密集型产业出口的形式,而非FDI;二是环境管制是促进污染密集型产业由珠三角地区向非珠三角地区转移的重要驱动因素;三是影响污染密集型产业转移的主要机制是地方政府的管制,如迁入地地方政府的基础设施条件、服务水平和优惠政策等;四是低人力资本不是影响污染密集型产业转移的影响因子。最后,本研究也说明广东省仍然是国际污染密集型产业的＂污染避难所＂,而非珠三角地区正在成为珠三角地区的＂污染避难所＂,因此要加大产业转移中的环境监管。  相似文献   

Prediction of Non-Cavitation Propeller Noise in Time Domain     

叶金铭  熊鹰  肖昌润  毕毅 《中国海洋工程》2011,(3)

The blade frequency noise of non-cavitation propeller in a uniform flow is analyzed in time domain. The unsteady loading (dipole source) on the blade surface is calculated by a potential-based surface panel method. Then the time- dependent pressure data is used as the input for Ffowcs Williams-Hawkings formulation to predict the acoustics pressure. The integration of noise source is performed over the true blade surface rather than the nothickness blade surface, and the effect of hub can be considered. The ...  相似文献   

蒙阴县京沪高速公路沿线破损山体治理方法探讨     

王元波  姚春梅  张莉莉  张永伟  王一建 《山东地质》2011,(3):27-29

蒙阴县以科学发展观为指导,结合当地实际,积极探索破损山体治理模式,对京沪高速公路沿线破损山体进行了综合治理,取得了较好的治理效果。该文详细介绍了植生穴绿化技术、植生盆绿化技术和雕刻美化治理技术在蒙阴县京沪高速公路沿线破损山体治理中的应用,以及生态修复技术在日后养护中的注意事项,并探讨了治理工程产生的环境效益和社会效益。  相似文献