دانلود رایگان مقاله مدیریت زمان واقعی اختلالات حمل و نقل در جنگلداری

Abstract

In this paper, we present a mathematical programming model based on a timespace network representation for solving real-time transportation problems in forestry. We cover a wide range of unforeseen events that may disrupt the planned transportation operations (e.g., delays, changes in the demand and changes in the topology of the transportation network). Although each of these events has different impacts on the initial transportation plan, one key characteristic of the proposed model is that it remains valid for dealing with all the unforeseen events, regardless of their nature. Indeed, the impacts of such events are reflected in a time-space network and in the input parameters rather than in the model itself. The empirical evaluation of the proposed approach is based on data provided by Canadian forestry companies and tested under generated disruption scenarios. The test sets have been successfully solved to optimality in short computational times and demonstrate the potential improvement of transportation operations incurred by this approach.

5. Conclusion

We have introduced a new approach to re-optimize the log-truck transportation plans in real-time when an unforeseen event is revealed. This approach uses a time-space network to represent the evolution of the transportation network over time and the changes it undergoes following a disruption. The allowed trips and loading/unloading operations are used as an input for the mathematical model. The latter is solved to obtain a new transportation plan. Ease of deployment of this new plan is taken into account through ensuring the continuity of trips that are in progress when the disruption is revealed unless they are directly impacted by the disruption. A simulation procedure was developed to generate the unforeseen events for real applications provided by FPInnovations. Compared to a complete information scenario where disruptions are assumed to be known in advance, the proposed approach produces very good results. Also, the mathematical model was solved in a few seconds and is thus well suited for a real-time context.