貨櫃儲存場堆積策略模擬與儲位指派模式構建

Abstract

摘要 貨櫃儲位指派係貨櫃進存前預先將貨櫃指定存放於特定儲位，為貨櫃進存前的先期計劃。由於貨櫃進存量及貨櫃屬性未能於事前精確預知，因此目前多由人工依經驗法則進行指派工作。此種指派方式之結果並不能保證能對儲區作最有效之運用，亦造成貨櫃存取時不必要的翻櫃作業，導致作業成本上昇。 本研究首先對貨櫃堆積策略進行探討，將作業時間區分為機具移動時間、存取貨櫃時間及翻櫃時間三部分，以平均每櫃作業時間最短為目標，針對跨載機、貨櫃堆積機及高架換載機等三種不同機具作業，依貨櫃屬性取得與否，區分為「進存時未知提領日期」及「進存時已知提領日期」兩大類，分別比較堆積策略之優勢順位。研究結果發現，不同的作業機具，其堆積策略各異，而機具移動時間對堆積策略之影響極微，翻櫃時間成為決定各堆積策略優勢順位之關鍵因素。 針對單儲區與雙儲區兩種儲區規劃及順序堆置與隨機堆置兩種法則，進行儲位指派模擬及參數變化之敏感度分析，發現儲位選擇自由度較高之單儲區規劃與隨機堆置法則，可得到較佳之指派結果。經分析貨櫃儲位指派問題特性可知，當以最小翻櫃次數為目標構建貨櫃儲位指派整數規劃模式時，由於翻櫃動作係產生在同一疊貨櫃上下層貨櫃之間，因此可將行與列之差異忽略，而降低儲位指派問題的維度。本研究所構建之貨櫃儲位指派模式可以LINGO軟體求解小規模之簡例，驗證本研究所構建之貨櫃儲位指派模式之有效性。

Abstract Container slot assignment is to allocate container boxes to certain slots in advance. It is a preplanning procedure for container stowage. Because the information of all of container attributes are not precisely known in advance, the operators of container yards normally assign the boxes into slots by experience. This often causes inefficient usage of slot capacities with unproductive moves of containers, which represents an increase in operation cost. This study develops six container stacking strategies and compares their moving efficiency. The attributes of containers are divided into two categories--attributes that are known and unknown in advance. The moves of containers utilize such equipment as straddle carrier, forklift, and transtainer. The operation time is composed of equipment moving, loading/unloading, and restowage time. By comparing the average operation times of various stacking strategies, we find that equipment moving time has little effect on strategies rankings, while restowage time dominates. In addition, this study also compares the numbers of unproductive moves in single and twin areas under ordered- and random-stacking strategies. It is found that single area random-stacking strategy is more efficient than twin areas ordered-stacking. This implies that a decrease of the freedom of container slots selection will lead to less efficiency of slot assignment. Since shifting moves occur only at the same row and column in different layers, the interrelationship between row and column of container slot assignment can be ignored; therefore, this study formulates the container slot assignment problem as an integer programming model to minimize the number of unproductive moves. The model can be easily solved by LINGO package and the solutions have been validated with some simplified examples.