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Ensuring a fleet of green aircraft is a basic step in mitigating aviation pollution issues that are expected to be worsen in the coming years due to rapid air traffic growth. This study proposed a novel methodology in green fleet planning in which both profit and green performance of airline are considered simultaneously and explicitly. To do this, a Green Fleet Index (GFI) is derived as an indicator to quantify the green performance of airline’s fleet. It measures the degree of airline compliance with a standard requirement in terms of emission, noise, and fuel consumption. A bi-objective dynamic programming model is then formulated to find optimal aircraft acquisition (lease or purchase) decision by minimizing GFI and maximizing profit. Several interesting results are obtained: (1) considering environmental issue as secondary objective yields a greener fleet; (2) airline’s profit is affected, but could be recovered from environmental cost savings; (3) increasing load factor is an effective operational improvement strategy to enhance airline’s green performance and raise profit level. It is anticipated that the framework developed in this study could assist airlines to make a smart decision when considering the need to be green. 相似文献
113.
This paper examines a practical tactical liner ship route schedule design problem, which is the determination of the arrival and departure time at each port of call on the ship route. When designing the schedule, the availability of each port in a week, i.e., port time window, is incorporated. As a result, the designed schedule can be applied in practice without or with only minimum revisions. This problem is formulated as a mixed-integer nonlinear nonconvex optimization model. In view of the problem structure, an efficient holistic solution approach is proposed to obtain global optimal solution. The proposed solution method is applied to a trans-Atlantic ship route. The results demonstrate that the port time windows, port handling efficiency, bunker price and unit inventory cost all affect the total cost of a ship route, the optimal number of ships to deploy, and the optimal schedule. 相似文献
114.
针对上层有约束条件、下层有N个独立的决策单元的二层线性规划问题,提出了一种模糊数学解法。首先,把这种规划分解为若干单层规划;然后引入隶属函数,用3个定理对各单层规划的解进行讨论,最终把这种二层线性规划转化为求解一个单层线必规划问题。使问题得到了简化。 相似文献
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曾辉 《变流技术与电力牵引》2008,(4):51-53
直线电机轮轨交通系统因其工程造价低、线路适应性强等优势,被认为是资源节约型城市轨道交通先进模式。分析了日本、加拿大等直线电机地铁车辆的转向架、牵引和制动等技术的特点和性能,探讨了直线电机在城市轨道交通应用中的经济性和适用性。 相似文献
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基于R树面向对象的航海资料数据模型 总被引:2,自引:0,他引:2
提出了基于面向对象技术和R树索引结构的航海资料数据模型。它通过面向对象技术的继承性有效地解决了信息存储的冗余问题,体现了航海资料的自然层次结构,与航海人员的思维定式相吻合。同时,通过R树建立了航海资料二维动态索引,实现了航海信息快速的查询。 相似文献
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This paper examines the optimal containership schedule with transit-time-sensitive demand that is assumed to be a decreasing continuous function of transit time. A mixed-integer nonlinear non-convex optimization model is first formulated to maximize the total profit of a ship route. In view of the problem structure, a branch-and-bound based holistic solution method is developed. It is rigorously demonstrated that this solution method can obtain an ε-optimal solution in a finite number of iterations for general forms of transit-time-sensitive demand. Computational results based on a trans-Pacific liner ship route demonstrate the applicability and efficiency of the solution method. 相似文献
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