| 摘要: | 飛航排程及班次表之優劣影響快遞業者之服務品質及營運績效甚鉅，其結果不但攸關業者設備之使用效率與人員之調度，更重要的，將進而直接影響業者之獲利能力、服務水準與市場之競爭能力等。以往飛航排程之研究多著重於客運方面，但航空客運與國際快遞貨運兩者特性並不相同。在客運方面，旅次需求之時間敏感度較高，若轉運次數過多，則易使旅客流失。對國際快遞貨物而言，只要能準時送達，貨主較不在乎貨物被多次轉運。在網路結構方面，國際快遞業多採用軸輻式網路(Hub-and-spoke network)，亦有別於一般航空客運的網路型態。另外，由於各場站的作業時效性的考量，快遞業對貨物之運送多存有時窗之限制。在此時窗限制下，各場站及空運中心貨物的作業成本與處理時間兩者存有負相關的關係。因此業者必須考慮各場站之作業成本，安排適當的航班到離時間，以降低其營運成本。近來雖有研究針對航空貨物之特性，發展一短期貨運機隊排程暨班次表規劃模式，但未針對國際快遞特性發展。 因此，本研究針對國際快遞運輸，以業者為立場，考量其相關營運限制，以營運成本最小化為目標，建構一短期國際快遞飛航排程及班次表建立之模式。此模式於未來實務的應用上，提供業者一有效工具，以規劃出合適之短期飛航排程與班次表。本研究利用網路流動技巧構建模式，模式中包含多重機流時空網路，用以定式機隊在時空中的流動。在網路設計上，針對各航次加入替代航次節線，利用系統化方式考量各場站貨物處理時間與作業成本的關係，以決定各航次於場站間最佳之飛抵時間。此模式可定式為一整數多重貨物網路流動問題，屬NP-hard問題。本研究利用C電腦程式語言配合數學規劃軟體，進行求解，並以一國際快遞公司之亞太地區航線的營運資料進行模式之測試，模式之測試結果良好，顯示模式具實用價值，能於未來實務應用上提供業者作為有效改善贏用績效之輔助規劃工具。 Fleet routing and flight scheduling are important in carrier’s levels of services and operational performance. They always affect the usage efficiency of facilities and crew scheduling. As a result, they are essential to carriers’ profitability, level of service and competitive capability in the market. In the past, most research on airline scheduling was mainly focused on passenger transportation, which is fundamentally different from express package delivery. In passenger transportation, passengers are more sensitive to time than express cargos. Too many transfers in a transport service may result in a significant loss of passengers. However, in air express service, as long as the package arrives on time, the customer would not care how it is routed. Currently, the hub-and-spoke network is mostly adopted by express cargo carriers, which is different from general passenger air transportation networks. Besides, due to the consideration of timelines operations at each station, there are usually time window constraints for express cargo delivery. Because of the time window constraints, the operating costs of cargos at each airport and the hub are negatively related to their handling times. Therefore, considering the operating cost at each airport, carriers must arrange suitable flight arrival/departure times in order to lower operating costs. Although there was a scheduling model recently developed for general air cargo transportation, it was not developed on the characteristics of express package delivery. Therefore, on the basis of the carrier’s perspective, this research develops a short-term scheduling model for international express package delivery, with the objective of minimizing the operating cost, subject to the related operating constraints. The model is expected to be a useful planning tool for air express carriers to determine a suitable fleet routing and timetables in their short-term operations. We will employ network flow techniques to construct the model, which will include multiple fleet time-space networks in order to formulate the fleet flows in the dimensions of time and space. We consider the relation between the handling time and the operating cost at each airport and introduce the alternative flight arcs into the time-space networks to decide on the best flight departure/arrival times. The model is expectedly formulated as a integer multiple commodity network flow problem that is characterized as an NP-hard problem. We use C computer language and a mathematical programming solver to develop an efficient algorithm to solve the problem. Finally, to evaluate the model and the solution algorithm, we perform a case study by using the real operating data from a major international air express carrier. The results indicate that the model works well and is useful in actual operations. |
