Perishable Inventory Problem as a Stochastıc Model: A Literature Review

Envanter yönetimi, müşteri talebinin en düşük maliyetlerle zamanında karşılanmasını sağlar. Bu nedenle envanter yönetiminin doğru yapılması, işletmelere rekabet ortamında üstünlük sağlayacağı gibi, maliyetlerini de azaltacaktır. Envanter kuramı literatüründeki klasik modellerin çoğu, ürünlerin süre kısıtlaması olmadan stoklanabileceğinden hareketle geliştirilmiştir. Oysa sağlık, gıda gibi birçok alanda karşılaştığımız raf ömrü olan ürünlerin envanter kontrolü, dayanıklı ürünlerin envanter kontrolünden farklıdır ve önemli bir problemdir. Bu çalışmada bozulabilir envanter probleminin genel yapısı ve dinamikleri kısaca açıklanmış, problemin hangi yönleri ile farklılık göstereceği incelenmiştir. Ayrıca bozulabilir envanter probleminin çözümüne önemli katkılar yapmış olan çalışmalar araştırılmış, uygun bir sınıflamaya göre bu çalışmalar kısaca sunulmuştur Inventory management allows satisfying customer demand on time with minimum cost. Hence, accurate management of inventory not only allows for superiority to companies in the competitive environment but also minimize the inventory costs, as well. Most of the classical models in inventory theory literature are developed for the products that can be stored without time limitation. However, the inventory management of some products which have a lifetime such as the products that are used in health or food industry is different from the classical models and has been an important problem recently. In this study, the general structure and dynamics of the perishable inventory have been explained briefly and the aspects that differs the perishable problem from each other have been examined. Moreover, the literature those make considerable contributions on the inventory management of perishable products have been studied and presented briefly with respect to the appropriate classificatio

A Perishable Inventory System with Postponed Demands and Multiple Server Vacations

A mathematical modelling of a continuous review stochastic inventory system with a single server is carried out in this work. We assume that demand time points form a Poisson process. The life time of each item is assumed to have exponential distribution. We assume (s,S) ordering policy to replenish stock with random lead time. The server goes for a vacation of an exponentially distributed duration at the time of stock depletion and may take subsequent vacation depending on the stock position. The customer who arrives during the stock-out period or during the server vacation is offered a choice of joining a pool which is of finite capacity or leaving the system. The demands in the pool are selected one by one by the server only when the inventory level is above s, with interval time between any two successive selections distributed as exponential with parameter depending on the number of customers in the pool. The joint probability distribution of the inventory level and the number of customers in the pool is obtained in the steady-state case. Various system performance measures in the steady state are derived, and the long-run total expected cost rate is calculated

Grocery omnichannel perishable inventories: performance measures and influencing factors

Purpose- Perishable inventory management for the grocery sector has become more challenging with extended omnichannel activities and emerging consumer expectations. This paper aims to identify and formalize key performance measures of omnichannel perishable inventory management (OCPI) and explore the influence of operational and market-related factors on these measures. Design/methodology/approach- The inductive approach of this research synthesizes three performance measures (product waste, lost sales and freshness) and four influencing factors (channel effect, demand variability, product perishability and shelf life visibility) for OCPI, through industry investigation, expert interviews and a systematic literature review. Treating OCPI as a complex adaptive system and considering its transaction costs, this paper formalizes the OCPI performance measures and their influencing factors in two statements and four propositions, which are then tested through numerical analysis with simulation. Findings- Product waste, lost sales and freshness are identified as distinctive OCPI performance measures, which are influenced by product perishability, shelf life visibility, demand variability and channel effects. The OCPI sensitivity to those influencing factors is diverse, whereas those factors are found to moderate each other's effects. Practical implications- To manage perishables more effectively, with less waste and lost sales for the business and fresher products for the consumer, omnichannel firms need to consider store and online channel requirements and strive to reduce demand variability, extend product shelf life and facilitate item-level shelf life visibility. While flexible logistics capacity and dynamic pricing can mitigate demand variability, the product shelf life extension needs modifications in product design, production, or storage conditions. OCPI executives can also increase the product shelf life visibility through advanced stock monitoring/tracking technologies (e.g. smart tags or more comprehensive barcodes), particularly for the online channel which demands fresher products. Originality/value- This paper provides a novel theoretical view on perishables in omnichannel systems. It specifies the OCPI performance, beyond typical inventory policies for cost minimization, while discussing its sensitivity to operations and market factors