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杨德荣 《交通运输工程与信息学报》2007,5(2):17-23
目前,关于集装箱的各种装箱算法都是针对多种规格待装物体的,不适合单一规格物体的装箱优化计算.本文专门讨论单一规格物体装箱问题,给出优化算法.首先针对给定的待布空间,计算装箱后可能得到的物体组合在三个坐标方向的最优高度和层的分布,把三维布局变为二维布局问题;然后通过优化计算和镜向复制方法,使每一个可能存在的物体层都得到最优结果;最后,研究三个坐标方向的优化趋势,选定最优坐标方向的最优物体层装箱.如此循环,最后得出集装箱的优化装箱结果.计算表明,算法优化效果显著,过程简单. 相似文献
865.
Rail-rail transshipment yards act as central hub nodes within a railway network and enable a rapid consolidation of containers between different freight trains. To avoid an excessive movement of gantry cranes when transferring a container from one train to another, modern yards apply sorting systems where shuttle cars move containers horizontally along the spread of the yard. This paper compares four elementary sorting systems. Specifically, we compare rubber-tired and rail-mounted shuttles and differentiate whether a pure shuttle system or a lift & shuttle system is applied. In pure shuttle systems, a shuttle receives a container from a crane and transports it towards the destination crane, where it serves as a storage device until being unloaded. A lift & shuttle system applies shuttles with an integrated lifting platform, so that they are able to autonomously store and receive containers from a separate storage rack. Both alternatives exist in rubber-tired and rail-mounted versions. As the shuttles are the main driver of the investment costs, we compare the required fleet size for timely supplying given gantry crane schedules within all four systems. For this purpose, we derive suited scheduling procedures. This way, decision support for yard managers having to identify a suited sorting system and to layout a new terminal is provided. 相似文献
866.
To ensure hull structural strength of container ships in association with their increase in size, it is very important to grasp the hull stress histories all over the hull structure in actual sea state. However, ordinary hull stress monitoring systems are insufficient for this purpose because of the small number of stress sensors actually practicable. Therefore, in this paper, we discuss an approach to reproduce the hull stress responses which are not measured based on the estimated wave spectrum from the limited measurement data. To achieve this, we introduce a new model to estimate directional wave spectra based on measured ship stress responses and ship response functions, and further we estimate other ship responses using the model. To model an arbitrarily shaped directional wave distribution, the 360° direction is discretized into 36 directions of 10-degree intervals instead of using a directional distribution function, and in each direction, the wave spectrum is represented using the Ochi (3P) spectrum with three parameters (average wave period, significant wave height, and kurtosis). The authors discuss the evaluation results based on two stress response combinations, and a comparison is made between the sea state estimates made by the proposed method and the ocean wave hindcast database (JWA). Furthermore, by comparing the significant values and the spectra of the measured response of the ship with the estimated response based on both the estimated sea state by the proposed method and the hindcast sea state, the accuracies of the proposed method and the hindcast method are discussed in terms of ship stress estimation at non-instrumented locations. 相似文献
867.
Container liner shipping companies only partially alter their shipping networks to cope with the changing demand, rather than entirely redesign and change the network. In view of the practice, this paper proposes an optimal container liner shipping network alteration problem based on an interesting idea of segment, which is a sequence of legs from a head port to a tail port that are visited by the same type of ship more than once in the existing shipping network. In segment-based network alteration, the segments are intact and each port is visited by the same type of ship and from the same previous ports. As a result, the designed network needs minimum modification before implementation. A mixed-integer linear programming model with a polynomial number of variables is developed for the proposed segmented-based liner shipping network alternation problem. The developed model is applied to an Asia–Europe–Oceania liner shipping network with a total of 46 ports and 11 ship routes. Results demonstrate that the problem could be solved efficiently and the optimized network reduces the total cost of the initial network considerably. 相似文献
868.
Miluše Tichavska 《运输评论》2017,37(3):383-402
The accurate calculation of external costs from vessel emissions and shipping (as it happens with transport) strongly depends on parameters such as location, the time of the day and vessel operative. Thus, the use of a full bottom-up approach and granular traffic details is suggested. The latter may represent a substantial improvement in the resolution of shipping activity, energy demand, emissions and cost data being the latter essential for better regulations. The revised work identifies the Impact Pathway Approach (IPA) as the best-practice bottom-up methodology for calculating site-specific external costs derived from shipping air emissions. It has been widely adopted, among others, over major European studies (CAFE, BeTa, NEEDS and HEATCO). Also, it shows that due to costly and complex requirements of creating a shipping and harbour-specific bottom-up approach, external cost calculation based on tonne per euro factors obtained from European Studies (top-down approach) has been widely accepted. Moreover, methodological improvements and the possible achievement of refined estimations (IPA) dedicated to ports and shipping are strongly suggested, as these may improve information quality used for environmental policy and measures that contribute to the internalisation of externality costs. 相似文献
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