Liner ship route schedule design with port time windows

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.     

二层线性规划的模糊数学解法(Ⅱ)

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。     

基于R树面向对象的航海资料数据模型

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。     

Containership scheduling with transit-time-sensitive container shipment demand

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.     

Cost-time Minimization in a Transportation Problem with Fuzzy Parameters: A Case Study

In real world applications the supply, the demand and the transportation cost per unit of the quantities in a transportation problem are hardly specified precisely because of the changing economic and environmental conditions. It is also important that the time required for transportation should be minimum. In this paper a method has been proposed for the minimization of transportation cost as well as time of transportation when the demand, supply and transportation cost per unit of the quantities are fuzzy. The problem is modeled as multi objective linear programming problem with imprecise parameters. Fuzzy parametric programming has been used to handle impreciseness and the resulting multi objective problem has been solved by prioritized goal programming approach. A case study has been made using the proposed approach.     

基于蚁群算法的舰船避险航路规划

采用蚁群算法研究舰船避险航路规划问题,利用栅格法将航行海区进行细分,建立舰船避险航路模型,进而求算优化解。仿真结果表明,蚁群算法求解舰船优化航路具有较强的稳定性和鲁棒性。     

路网车流径路选择随机相关机会规划模型及其混合遗传算法

研究随机环境下车流径路的选择问题,首先给出路网车流径路方案可靠性的定义,并在此基础上建立随机环境下车流径路选择问题的随机相关机会多目标规划模型。模型考虑了车流具有不同权重的情况,目标为极大化车流径路方案的可靠性及极小化期望总费用。用C＋＋语言编写K短路算法,并在Visual Studio 6.0上基于该算法开发了软件,用于计算网络上任意两点之间的K短路。以该软件计算出的K短路作为节点间的可选径路集,提出一种基于随机模拟的混合遗传算法。算例表明,在不同交叉和变异概率的条件下算法均可在给定进化代数内收敛至相同的最优解,有较强的适应性。     

动力定位船舶桨-桨干扰处理策略研究

本文针对动力定位船舶在推力分配中桨-桨之间的水动力干扰问题,基于二次规划算法提出了一种改进的避免桨-桨干扰的策略。以一艘海洋平台供应船模型为研究对象,通过仿真验证了该算法可以有效地降低推进器的推力损失,提高船舶的定位精度,降低推进系统的能耗。     

汽车风窗玻璃电动刮水器耐久试验台设计

介绍长城汽车股份有限公司试验中心自制电动刮水器耐久试验台的构成和功能,论述其硬件水循环系统及控制程序的工作原理。     

平曲线超高和加宽施工验算的可视化程序设计

按照公路等级、设计时速、平曲线参数,确定公路超高过渡段的旋转方式以及公路加宽过渡段的计算方式,选择Visual Foxpro 9.0作为开发工具,结合VBA命令,在Microsoft Word平台上进行二次开发,以数据录入模块、平曲线超高及加宽计算模块、结果打印输出模块作为系统的三大功能部分,实现公路平曲线超高和加宽的计算机辅助计算,为公路设计和施工提供方便。