基于线性叠加的智能船舶经济性评估模型构建

经济性是智能船舶能否实现推广应用的关键,目前国内外有关智能船舶经济性分析的研究较少。本文通过对传统船舶经济性分析方法进行修正优化,提出智能船舶经济性分析计算模型,并根据理论推导结果,得出智能船舶经济性分析的线性叠加简化模型,并利用40万吨级VLOC实际运营数据进行科学性检验。本文提出的模型与方法适用于各类智能模块加装情况下的经济性核算,为相关单位开展智能船舶经济性快速分析提供了理论支持和解决方案。     

Widening the Panama Canal and U.S. ports: historical and economic impact analyses

ABSTRACT

The economic history of the U.S. illustrates how the role of many cities has been changed by being seaports or located on navigable rivers or lakes. Based on the widening of the Panama Canal in 2016, the West Coast ports that include the west coast seaports of California, Oregon, and Washington were expected to become less important, while the freight shares of the East Coast and Gulf ports would increase. By how much it has been not easy to measure or predict so far, but this study attempted to define some of the key parameters in the measurement. As well as several relevant background topics, both the demand- and supply-side versions of the National Interstate Economic Model, have been applied for the measurement of economic impacts. U.S. port authorities and policy makers at the local and national levels who respond and develop plans for coping with the new realities of the Panama Canal are able to understand the extent to which changes in shippers’ and land-mode transporters’ behaviors would undermine the logistics and the costs of their activities. Therefore, this study is important for a diverse spectrum of port development strategies in the U.S. to respond to the Canal expansion.     

粘弹性人工边界在地下结构抗震分析中的应用

地下结构地震反应分析需考虑结构-地基的动力相互作用,其中场地土层的自由场反应分析是确定地震输入的关键问题。以往地下工程实例表明,在结构动力时程计算中,能否有效模拟无限地基边界对结构抗震分析有很大的影响。基于某地下综合体项目进行抗震评估,采用黏弹性人工边界模拟自由场震动响应,克服工程中传统分析里不能模拟场地无限域的缺点。为地下结构的动力时程分析提供可靠数值依据。     

感应充电路面技术研究现状与展望

以感应充电技术(Inductive Power Transfer,IPT)为主要特征的充电路面(Electrified Road,e-Road)近年来发展迅速，其可为行进中的电动汽车进行动态无线充电，有效解决电动汽车充电时间过长、续航里程不足等问题，是支撑未来公路交通电气化发展的重要储备技术。详细介绍了IPT系统的工作原理和性能特点，并总结了已有e-Road试验段的充电性能参数和技术就绪度水平。在此基础上，进一步从基础设施角度剖析了e-Road目前存在的主要工程问题及相关研究进展，内容包括：①深入分析了IPT系统工作时因高频磁场通过介电性路面材料所引起的电磁损耗对IPT系统充电效率的影响，并提出了可能的解决方法；②针对充电模块与普通沥青路面存在的力学兼容性问题，从结构受力原理、材料损伤特性等方面总结了e-Road复合结构产生力学损伤加剧效应的原因，并提出了耐久性优化措施；③针对e-Road环境可持续方面存在的不确定性，评估并对比了e-Road与传统道路的全生命周期环境效益，指出了e-Road环境性能研究对电动汽车全生命周期综合效益估算的重要性。此外，还从政策支持、安全性、价格因素等角度对e-Road进行了综合可行性评估，并对充电路面基础设施的未来发展进行了智能化展望，提出了e-Road与其他新型智能道路技术进行有机融合的可能途径。     

考虑拥堵空间排队与溢出的道路网静态交通流分配

为刻画拥堵空间排队与溢出现象对交通流分配的影响，提出考虑拥堵空间排队与溢出的道路网静态交通流分配问题，并构建相关的求解算法，用于描述交通需求在起讫点移动过程中路网整体的宏观运行状态。首先，丰富和完善考虑拥堵空间排队与溢出的静态交通流分配的相关假设，提出次生瓶颈、拥堵干扰与渗透和分段化路段阻抗等基本概念和理论，来刻画拥堵交通瓶颈、拥堵空间排队等交通现象；其次，建立网络瓶颈识别算法和空间排队回溯算法，基于此构建考虑拥堵空间排队和溢出的增量分配算法，用于求解交通流分配的结果；最后，通过使用一个具有说明型的算例进行对比分析。研究结果表明：建立的瓶颈识别、排队回溯和增量分配算法可以识别路网中的瓶颈位置及其拥堵排队区域，并可计算得到各路段上的分段分配流量；与点排队只影响瓶颈路段的运行状况和均一的路段分配结果相比，可有效描述路网整体的宏观运行状态以及由于拥堵空间排队所导致的拥堵干扰与渗透现象；不同于“时间片”的伪动态交通流分配模型，新建算法的分配结果是“全时段”与“整体性”的路网宏观运行状态，包含了拥堵瓶颈的具体位置和空间排队的干扰与渗透情况；一般拥堵点排队模型和基于“时间片”的拥堵空间排队模型难以刻画拥堵干扰与渗透现象以及路网整体的宏观运行状态，故所建立的分配方法是对传统拥堵交通流分配的丰富和发展。     

Integrated models of land use and transportation for the autonomous vehicle revolution

ABSTRACT

The advent of the autonomous vehicle (AV) will affect not only the transportation system, but also future patterns of land development. Integrated land use and transportation models will be critical tools in assessing the path forward with this technology. Key questions with respect to land use impacts of AVs arise from potential changes in sensitivity to travel and reduced demand for parking. It is an open question whether AVs will induce urban sprawl, or whether spatial economies of agglomeration will mitigate any reductions in travel time sensitivity. The deployment of shared fleets of AVs would likely reduce parking demand, producing yet to be explored impacts on property development within existing urban footprints. We perform a critical assessment of currently operational models and their ability to represent the adoption of AVs. We identify the representation of time in such models as a vital component requiring additional development to model this new technology. Existing model applications have focused on the discrete addition of new infrastructure or policy at a fixed point in time, whereas AV adoption will occur incrementally through time. Stated adaptation surveys are recommended as tools to quantify preferences and develop relevant model inputs. It is argued that existing models that assume comparatively static equilibrium have been convenient in the past, but are insufficient to model technology adoption. In contrast, dynamic model frameworks lack sufficient structure to maintain reasonability under large perturbations from base conditions. The ongoing advancement of computing has allowed models to move away from being mechanistic aggregate tools, towards behaviourally rich depictions of individual persons and firms. However, much work remains to move from projections of existing conditions into the future, to the evolution of the spatial economy as it evolves through time in response to new technologies and exogenous stresses. Principles from complex and evolutionary systems theory will be important in the development of models with the capacity to consider such dynamics.     

Online channel strategies under different offline channel power structures for the Belt and Road of China

ABSTRACT

This paper explores the online channel strategies adopted by Chinese manufacturers with regard to the Belt and Road. It also investigates the effect of offline channel power structures and maritime transportation costs on online channel mode selection and pricing strategies. The offline channel power structures are classified into three types, namely, Chinese manufacturer Stackelberg (MS) structure, vertical Nash (VN) structure, and foreign retailer Stackelberg (RS) structure. Furthermore, a game model is developed among the Chinese manufacturer, foreign retailer, and cross-border e-tailer to investigate the interactions among offline channel power structures, maritime transportation costs, and Chinese manufacturers’ online channel mode selection. The results show that Chinese manufacturers’ preferences for the online agency selling mode increases correspondingly with the decrease in their market position and bargaining power. Moreover, foreign retailers can obtain higher profits in the online agency selling mode under the VN structure. However, the level of profit for foreign retailers depends on the intensity of their competition with cross-border e-tailers under the MS and RS structures. Finally, consumers in countries along the Belt and Road can obtain a higher surplus in the online agency selling mode under all of the structures.     

大型船舶钨极氩弧重熔工艺应用

疲劳破坏是船体结构的主要破坏形式之一。改进结构节点的设计和施工工艺,可保证船体结构中受交变载荷作用的构件有足够的疲劳寿命。钨极氩弧(Tungsten Inert Gas, TIG)重熔是改善结构节点焊后疲劳强度的有效方法。与目前船上常用的几种改善疲劳强度的方法进行分析对比,对TIG重熔工艺的重要性进行充分论证,获得实施TIG重熔工艺的技术标准和操作要点。TIG重熔工艺不仅改善结构节点疲劳强度,而且为建造具有较长疲劳寿命的大型船舶找到一个行之有效的方法,可产生良好的经济和社会效益。     

造船经济论证方法的探讨

船舶经济分析是船舶技术经济论证的主要环节之一,但传统的造船经济论证方法存在着一定的缺陷。为此,充分考虑各个因素的不确定性,考虑经营的风险性,对传统的造船经济论证方法加以综合改进,形成新的造船论证方法——计算机模拟方法。与传统方法相比,计算机模拟的方法在最终结果的处理上更有现实意义。     

基于B/S结构的机车售后服务管理系统

文章简述了ActiveX组件模型结合ASP技术在Internet环境下实现基于Browser/Server结构的机车售后服务管理系统。该系统在ActiveX技术基础上通过ADO编程实现数据传输和访问,结合ASP和ActiveX控件技术实现动态发布和在线管理。