سیستم حمل و نقل، موجودی گنجانده شده با دو نوع از مشتریان برای کالاهای فاسد شدنی چندگانه

Perishable goods comprehend a large space daily marketing of goods. These kinds of goods ask a strict inventory control. Due to fast movement of these goods from distributer to retailer, it is necessary to have a command over the transportation system to maximize the profit. In this research, the transportation model has been mapped with the inventory model with time varying demand and two types of customers for different perishable goods to simultaneously maximize the revenue and minimize transportation and inventory cost, and hence maximizing the net profit. The model assumes fixed shortage, handling and outdating cost and selling price of goods decreases with time. An illustrative example is provided at the end to reveal the application of proposed methodology on a given system. Insight gained would be of much interest to the distributers of perishable goods in managing the inventory and transportation for same.

The minimization of the supply-chain inventory and transportation cost has been the premier area of researchers since long. Many literatures can be found out in the same field considering different real world situations. In the literature several models are presented in which it is assumed that the product can be stored in the inventory for infinite time to meet the future demand and there are infinite numbers of vehicles available for transportation of goods. However in reality, many items cannot remain in inventory for infinite time, they are perishable in nature. Perishability refers to the property of an item to deteriorate after a particular period of time, which is a consequence of variations in demand and speculative ordering policies. Fruits, vegetables, meat, foodstuffs, perfumes, alcohol, gasoline, photographic films, etc., are some examples where deterioration may typically occur during their normal storage period. Stashing of perishable item is a complicated task. If the deterioration rate of the product is significant, its impact on inventory transport system cannot be ignored (Zanoni and Zavanella, 2007). If the fluctuation in demand is high then it becomes more difficult to handle the inventory of perishable goods, because there will be a large amount of outdating of the goods. Inventory and transportation of perishable goods is now becoming a field of prime interest of researchers. As stated by Zanoni and Zavanella (2007), perishable goods can be divided into two sub-groups: I. products with fixed life span, when products maintain their usefulness for a fixed period of time and then must be deemed useless; and II. products with a variable life span, if their usefulness diminishes over time, according to the product age. Various literatures can be found out in the field of inventory and transportation of perishable goods with a fixed life span, however a little has been done for the variable life time. For perishable goods having a variable life time, its usefulness diminishes over time and consequently its cost reduces with usefulness. This paper uses the model proposed by Ishii (1993). However the model in the referred research is simple and deals with only inventory and shortage cost and profit functions for a single perishable item with variable life span whose cost decreases with time. The model assumes there are two types of customers one who buys only fresh goods and demand due to these kinds of customers it has been called as high priority demand, and the second type of customer who buys both fresh and old goods but with relaxations in price and this demand has been called as low priority demand. The model has been extended in this research by integrating transportation model with the referred model for multiple perishable items ( Fig. 1). The transportation model proposed is a limited capacity transportation model having variable cost in accordance with the type of carrier used for transportation. The excess quantity is assumed to be transported by calling external service provider at cost higher than self transport system. Full-size image (21 K) Fig. 1. The proposed inventory-transportation model. Figure options The overall approach of this research and relation between different models i.e. the initial model, the transportation model and the integrated model has been briefly portrayed in Fig. 2. Full-size image (51 K) Fig. 2. Relationship between different models. Figure options The remainder of this paper is structured as follows: Section 2 consists of theoretical background and relevant research in this area. Section 3 deals with model formulation for different costs and revenue associated with inventory and transportation of perishable goods. An illustrative example has been worked out in Section 4 where demand for 5 different perishable goods is considered and optimal number and capacity of vehicles has been reckoned. Lastly, the conclusion and recommendations for future work is portrayed in Section 5.

In order to maximize profit while dealing with perishable goods it is necessary to simultaneously maximize revenue and minimize cost. While maximizing profit function, first optimal ordering quantity of each item is found that is followed by minimization of transportation cost. To minimize transportation cost an optimal combination of number of vehicles and their carrying capacity is found. This research provides a precursor for future research in field of managing inventory and transportation of multiple perishable goods. There are many ways of extending this research to further improve results. In this research simple demand and cost functions has been assumed. While in reality demand functions are much more complex, therefore more accurate and realistic insights can be gained using this research by taking real demand and cost functions into action. Further, here transportation cost has been taken for a fixed distance, hence this work can be extended in future considering distance in the transportation cost function to improve the model. Another expansion of this study can be carried as the inventory routing problem by combining inventory transport systems with vehicle routing problem.