ABSTRACT

In this paper, we investigate a new variant of the multi-commodity network flow problem, taking into consideration multiple transport lines and time windows. This variant arises in a city logistics environment, more specifically in a long-haul passenger transport system that is also used to transport urban freight. We propose two mixed integer programming models for two objective functions: minimization of network operational costs and minimization of travel times. Since the problems under study are NP-hard, we propose three size reduction heuristics. In order to assess the performance of the proposed algorithms, we carried out computational experiments on a set of synthetic problem instances. We use the relative percentage deviation as performance criterion. For the cost objective function, a LP-and-Fix algorithm outperforms other methods in most tested instances, but for the travel time, a hybrid method (size reduction with LP-and-Fix algorithm) is, in general, better than other approaches.

摘要

在本文中，我们研究了多商品网络流问题的一个新变体，同时考虑了多条运输线路和时间窗。这种变体出现在城市物流环境中，更具体地说，出现在也用于运输城市货物的长途客运系统中。我们为两个目标函数提出了两个混合整数规划模型：网络运营成本最小化和旅行时间最小化。由于正在研究的问题是 NP-hard，我们提出了三种尺寸缩减启发式方法。为了评估所提出算法的性能，我们对一组合成问题实例进行了计算实验。我们使用相对百分比偏差作为性能标准。对于成本目标函数，