An operational activity-based method to estimate CO2 emissions from container shipping considering empty container repositioning

This paper develops an operational activity-based method to estimate CO₂ emissions from container shipping in contrasts to the traditional aggregated activity-based method. Two case studies investigate the impacts of empty container repositioning policies and port handling capacity on CO₂ emission index. The results show that the aggregated method could well overestimate CO₂ emissions and the operational activity-based method is more appropriate. The paper also demonstrates that high port-handling capacity and efficient empty container repositioning could reduce CO₂ emissions in seaborne container transportation.     

LNG储罐罐壁工程质量缺陷及控制措施

LNG储罐是LNG接收站中关键的设备之一,其工程质量非常重要。为使罐壁施工质量达到良好状态,可事先采用施工用的混凝土、钢筋和DOKA模板等施工材料建造小段试验墙,根据这段试验墙可以提前发现工程可能出现的缺陷,这些缺陷包括模板错缝、预埋件凹陷、混凝土表面局部气孔麻面、墙体裂缝、漏浆及混凝土表面色差等,对这些缺陷产生的原因进行分析并采取相应的控制措施,以确保罐壁施工顺利且高质量进行。     

低温储罐失效分析及预防措施

文中对低温设备温差应力循环所产生的疲劳失效事故进行了分析,目的是防止低温储罐在使用中出现疲劳破坏。文中通过对失效低温设备断口形貌特征的勘察,采用断口分析、焊接缺陷分析、温差应力循环与疲劳载荷分析的方法,得出了低温液体储罐设备在使用中易出现疲劳失效模式的结论。同时,从设计结构、施焊控制、安全泄放装置维护等方面,对低温液体储罐疲劳失效提出了预防措施。     

液化天然气B型独立液货舱结构低周疲劳研究

基于某B型独立液货舱为研究对象,开展液化天然气(LNG)船码头装卸货工况下的结构应力和温度场热应力分析,重点针对液货舱水平强框处连接节点计算其因装卸货受力和温度变化所引起的疲劳累积损伤。研究结果表明,部分研究疲劳节点由装卸货产生的低周疲劳损伤在整个结构疲劳累积损伤中的占比较大,对结构疲劳损伤起主导作用,需要在液货舱疲劳强度分析中予以重点关注。因此,对此类B型独立液货舱进行结构设计必须考虑低周疲劳的影响。     

Property Evolution of Sulphoaluminate Grouting Material under Pressure Circulation北大核心CSCD

Water-sealed underground oil tank projects are quite different from traditional underground projects since the water-sealing conditions are very strict and the difficulties caused by the geological specificity, structural specificity and construction specificity are key factors affecting the project. In light of the significant early initial setting time and rapid temperature increase of sulphoaluminate cement-based grouting material for a large domestic water-sealed underground oil tank with pressurized cyclic grouting, a laboratory grouting simulation is conducted. It is found that the properties of the sulphoaluminate cement-based grouting material are quite different under different pressure cycles, the hydration exothermic peak time gets shorter with an increase of circulation time, the compressive strength decreases with an increase of circulation time, and the longer the circulation time the more obvious the de-crease of compressive strength. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

液氨储罐角焊缝在线相控阵检验技术

文中针对液氨储罐定期检验不开罐的特点,通过对相控阵超声成像检测技术的研究,设计了4块角焊缝试板,共8处裂纹缺陷,通过设定检测参数,确定了实验参数和检测方案,检测出了预制的8处裂纹,并与DR检测成像进了比对,得到了较好的检测效果,对于将超声相控阵检验技术用于实际检测具有借鉴意义。     

Asymmetry in transport fuel demand: Evidence from household level data

Models for gasoline demand for transportation activities generally assume that demand is perfectly reversible with respect to gasoline price (and income). The small literature which relaxes the reversibility assumption in gasoline demand argues technological fixation leads to this asymmetry and utilizes aggregate time-series model to find evidence in favour of asymmetry. In this research it is suggested that there could also be behavioural factors behind this asymmetric response, possibly due to the loss aversion nature of human beings as described in the prospect theory. For the first time, household level data was used to understand asymmetry in gasoline demand in response to changes in gasoline price and income. There was statistical evidence that gasoline price and income both can induce asymmetric changes in gasoline demand among households. Specifically, elasticity with respect to rising prices and falling income is larger than the elasticity with respect to falling prices and rising income respectively, which is consistent with loss aversion in gasoline purchase behaviour. There was also some evidence of heterogeneity in the asymmetric responses between urban and rural households. The results have implications for transport-related energy tax policies or subsidies, while the method can be applied directly for non-energy goods as well.     

计及弹性支撑效应的独立液舱晃荡数值分析研究

文章针对弹性支撑结构作用下的液舱晃荡问题,采用基于Hilber-Hughes-Taylor(HHT)格式的隐式直接积分法求解液舱运动,应用VOF法求解流体晃荡,并结合部分单元参数的概念处理棱形液舱边界,建立了液舱运动与流体晃荡双向耦合迭代算法。以独立液舱为研究对象,通过耦合求解弹性支撑液舱晃荡,并与非弹性支撑液舱晃荡进行比较,分析了在不同刚度的弹性支撑结构作用下液舱液体运动及晃荡载荷的变化规律。该文建立的分析方法为含弹性支撑的独立液舱晃荡载荷预报提供了一种快速、有效的分析手段。     

景洪水力式升船机机械系统设计

结合景洪升船机的设计,对水力式升船机机械系统各子系统及部件的功能进行论述,对其结构和设计参数进行研究,并给出水力式升船机卷筒及同步系统、浮筒及动滑轮装置、钢丝绳组件和下水式承船厢的主要结构和设计参数。对水力式升船机浮筒的配重进行探讨,特别针对无间隙同步系统、承船厢充压对接密封装置提出新颖的结构,为同类工程设计提供参考。     

基于PSO-BP神经网络的油船中部结构优化

以舱段质量为目标函数,以相关规范要求的板厚及应力为约束条件,通过灵敏度分析确定设计变量,对油船中部结构优化。构建基于粒子群优化的BP神经网络模型,并代替有限元分析确定应力与设计变量之间关系,从而对舱段进行结构优化。优化后舱段质量降低了4.2%,优化后的有限元分析结果表明满足规范要求,PSOBP神经网络模型在船舶结构优化设计中具有可行性。