海底、海面对水下航行体阻力影响的模型试验研究

文章针对水下航行体开展了不同距离的近海底、近海面的模型阻力试验研究,建立了模型试验及分析方法,获得了海底和海面对阻力的影响规律。模型试验表明:采用低速浅浸深试验方法完全可以达到分离近海面、近海底影响的试验目的;仅有自由表面影响存在时,当水下航行体航行在大于其艇长1/3的深度上时,在实际中可认为没有兴波阻力;仅考虑海底壁面影响,当水下航行体航行在距海底超过其1/4倍艇长的距离时就可以不再考虑海底的影响;同时存在自由表面和海底壁面影响时,要完全避免限制水域的干扰需要水下航行体潜深超过1/3倍艇长的同时,水下航行体距海底的距离不宜小于1/2倍的艇长。     

动态载荷作用下焊接点线弹性裂纹的弯曲扩展路径的预测(英文)

利用二阶摄动方法研究了动态载荷作用下结构线弹性断裂裂纹的弯曲延伸扩展问题并求解了动态应力强度因子。利用二阶摄动方法研究了动载荷作用下裂纹路径预测时的应力准则与能量准则之间的关系。就均匀物质而言,在二阶摄动分析理论的框架内,两种准则指明了相同的动态裂纹路径。但在具有非均匀断裂韧度的物质中,能量准则优越于应力准则。作为二阶摄动方法的实际运用,研究了焊接结构中动态线弹性裂纹的形态特征和弯曲扩展路径问题,综合考虑了诸如远场动态作用应力、焊接残余应力、局部物质衰变以及不同尺寸的缺陷的存在等因素,绘制出动态载荷作用下退化区域中裂纹弯曲扩展的临界轨迹曲线。     

液压系统噪音分析与降噪措施研究

噪音问题不仅影响着液压系统的工作性能与使用寿命,还会威胁到舰船的隐蔽性和安全性。文章从液压系统设计的角度,分析了液压系统产生噪音的原因,提出了相应的降噪措施,对几种常见的降噪方法进行了对比分析,为研究液压系统降噪问题提供参考依据。     

基于网络分析法的舰舰导弹性能评估方法研究

舰舰导弹是水面舰艇攻击敌方舰船的主要武器,是舰船论证初期需要考虑的重要武器装备。文章建立了舰舰导弹作战性能评估指标体系,并使用超级决策软件进行建模;提出了基于网络分析法（analytic network process）的反馈结构评估框架来解决评估指标之间的非独立性和相互依赖关系。在对舰舰导弹三种方案的评估算例中,采用了问卷调查法对指标进行了成对比较,并通过计算极限超矩阵得出不同方案的性能理想化优势度值,为舰舰导弹的方案选型提供了一种可靠的方法。     

The impact of outcome framing and psychological distance of air pollution consequences on transportation mode choice

Recent years, air pollution phenomenon has become one of the crucial problems of Tehran, Iran. Due to main political and economic role of Tehran, population of this metropolis is high and increasing. Urban transportation of this highly populated city contributes more than 70% of air pollution problem in this city. Although a number of urban transport developments, policy measures and regulations have been employed, Tehran’s air pollution has remained crucial thus far. Finding ways to encourage individuals to behave more sustainable can be considered as a substantial approach of tackling environmental problems such as air pollution, since it can be highly cost-effective and fast. This research attempt to evaluate the impacts of two factors of outcome framing and psychological distance of air pollution on citizen’s willingness to behave environmental friendly, particularly to change the travel mode choice. Results illustrate that communicating the consequences of air pollution can provoke individuals’ to act more environment friendly or in particular to change their intention for using more sustainable mode of transportation. Framing the positive consequences of mitigating air pollution take precedence over framing the negative consequences. Moreover the gains of mitigating air pollution have an impact on the willingness to use of bicycle and bus. Results also show that decreasing the psychological distance of air pollution in order to make manipulated frame more personally relevant has no significant impact on respondents.     

海上保险“仓至仓”责任期间的思考

文中就海上保险“仓至仓”责任期间的起点和终点进行了分析，笔者认为，在海上货物运输保险中，一切险的保险人“仓至仓”责任期间，应起始于被保险货物运离保险单所栽明的起运地仓库或储存处所开始运输之时，而非海运的前一段陆路运输开始之际；终止于货物到达保险单所载明目的地被保险人在桌一处所实际分配、分派货物之时，而非终止于货物到达该处所之际。     

Real option analysis for environmental compliance: LNG and emission control areas

A wide array of technical and operational solutions is available to shipowners in order to comply with existing and upcoming environmental regulation within Emission Control Areas (ECAs). Liquefied Natural Gas (LNG) is a promising alternative since it offers potential cost savings in addition to ensuring compliance with ECA regulation. But investment to retrofit existing vessels to be able to use LNG carries significant upfront costs, and a high degree of uncertainty remains on the differential between the prices of LNG and conventional maritime fuels, as well as on the availability of LNG and the reliability of its supply chain. New technologies such as LNG inherently carry substantial risk and an ill-chosen investment strategy may have irreversible consequences that could jeopardise the future of the shipping company. One important question is whether interested owners should invest in LNG now to comply with ECA rules in 2015 and reap the benefits of lower LNG prices, or whether it would be advisable to wait until some of the uncertainty is resolved.While traditional discounted cash flow techniques are unable to account for the value of managerial flexibility linked, for example, to the possibility of deferring an investment, real option analysis can be used to analyse such cases. The paper discusses the optimal time for investment in LNG retrofit and takes specific account of the value of an investment deferral strategy versus the advantages obtainable from the immediate exploitation of fuel price differentials. Through the use of a real option model the paper shows that there is a trade-off between low fuel prices and capital expenses for investment in LNG retrofit. The development in LNG is critically dependent on its future price as well as the reduction in capital costs and ship retrofitting costs. In this respect, policy makers can play a critical role in providing support to advance technical knowledge, maintain LNG prices at favourable levels and in avoiding ambiguity on regulation.     

基于三相-单相变换器的牵引供电系统及并网控制

为了解决过分相给牵引供电系统带来的问题,研究了三电平三相-单相二极管箝位变换器,把三电平三相-单相变换器用作牵引变电所核心设备,搭建了基于此变换器的贯通式牵引供电系统。分析了三相变换器数学模型,设计了变换器控制系统,研究了单相变换器在贯通式牵引供电系统中的并网控制。利用Matlab／Simulink建立了三变电所贯通式牵引供电系统,仿真验证了该系统架构以及三相-单相变换器的控制性能和并网性能,证明了该系统的可行性。     

桥梁活载内力分析可视化研究初步

可视化方法可有效处理数值分析的结果。提出了两种利用可视化方法分析桥梁活载内力的可行方式，完成了其中一种的程序实现，并结合实例介绍了其工程应用。     

我国未来民法典限制政府官员隐私权的宪政意义

限制政府官员的隐私权，意味着媒体权力在其私域可以得到相应的扩张。这在选任、监督以及激励政府官员上，对于人民具有重大意义；对于政府官员而言，其也并非百无一利。故人民即便是在对政府官员因其隐私权受限而可能遭受的利益减损进行相应补偿后，也仍可从中获取较大利益。我国于即将制定的民法典中规定限制政府官员隐私权的条款具有重大的宪政意义。