International Journal of Inventory Research (11 papers in press)
An optimal policy for an integrated vendor-buyer model with two warehouses under vendor's capacity constraint
by Bibhas C. Giri, Ayan Chakraborty
Abstract: The paper considers an integrated single-vendor single-buyer supply chain model in which the vendor is assumed to be capacity constrained. The vendor can keep the excess units beyond the capacity of its own warehouse(OW) in a rented warehouse (RW) whose holding cost is higher than that of the own warehouse. The vendor delivers the buyer's order quantity in a number of equal shipments. The proposed integrated model is formulated and some of its characteristics are studied analytically. Considering the vendor's capacity as a control variable, the optimal decisions of the model are obtained for a numerical example. Sensitivity analysis is also carried out to measure the impact of key model-parameters on the outcome of the model.
Keywords: Supply chain; vendor-buyer integrated model; rented warehouse; capacity constraint.
On Inventory Control with Reference Prices
by Yigal Gerchak
Abstract: A retailer sets prices, as well as, simultaneously, selects quantities to order from a supplier. We consider a two periods setting where the second period\'s demand depends on the first period\'s (\"reference\") price, as well as on the second period price. We consider a linear-additive demand function as well as a novel iso-elastic multiplicative model.
Keywords: reference price; pricing newsvendor; additive noise; multiplicative noise.
Inventory model for non-instantaneous deteriorating item with random pre-deterioration period
by Manisha Pal, Anwesha Samanta
Abstract: The paper studies an inventory model for non-instantaneous deteriorating item where the deterioration of the item is initiated at a random time point. It is assumed that no shortages are allowed and demand occurs uniformly but at different rates during pre- and post- deterioration periods. The optimum order quantity and reorder intervals are determined so as to minimize the total expected cost per unit length of an inventory cycle. Numerical examples are cited and a sensitivity analysis is carried out to study the effect of model parameters on the optimum policy.
Keywords: Inventory control; periodic review model; non- instantaneous deteriorating item; random pre-deterioration period; deterioration dependent demand rate.
Coordinating replenishment and marketing policies for non-instantaneous deteriorating items with imprecise deterioration free time and general deterioration and holding cost rates
by Amirhosein Patoghi, Mostafa Setak
Abstract: In this paper an inventory system for non-instantaneous deteriorating items with imprecise deterioration free time is developed. We adopt a price and advertisement frequency dependent demand function, and in order to reach a general framework, arbitrary functions of deterioration and holding cost rates are hired. The major objective is to determine the optimal selling price, the optimal replenishment cycle and the optimal frequency of advertisement such that, the total profit is maximized. In order to determine the optimal solution several theoretical results are derived which indicate existence and uniqueness of the optimal solution. Thereafter, based on these theoretical results an iterative solution is developed. Finally, numerical examples are provided to demonstrate solution procedure, then sensitivity analysis is performed, it is shown that optimal policy under uncertain environment and crisp environment are identical and finally some managerial insights are proposed.
Keywords: Inventory; imprecise deterioration free time; arbitrary deterioration and holding cost rates; price and advertisement dependent demand.
Inventory model for non-instantaneous deterioration and price-sensitive trended demand with learning effects
by Nita Shah, Monika Naik
Abstract: This paper addresses a working model for non-instantaneous deteriorating items including the learning effect on various costs and the preservation technology investment to reduce the deterioration rate. The system includes time and price sensitive demand. The objective is to maximize the total profit per unit time by finding optimal joint selling price, replenishment cycle time, the preservation technology investment per unit time, ordering quantity and the shortage period. A numerical example is presented to validate the policy investigated in this paper. Further, the sensitivity analysis about the key parameters is conducted to obtain the managerial insights.
Keywords: Non-instantaneous deterioration of items; Time-price dependent demand; Learning effect; Preservation Technology.
Inventory Models with Stock-Dependent Demand: A Comprehensive Review and Its Linkage with Waste Management
by Neeta Sharma, Prem Vrat
Abstract: This paper presents a review of the advances in stock-dependent demand inventory literature for the last three decades. The available relevant models have been classified into a number of categories and their principal features have been discussed in brief to bring out more pertinent information regarding model development. An extensive analysis of the literature is presented to identify the future research scope and the factors which are responsible for the poor applicability of these models. Moreover, a very important and missing link between the stock-dependent demand phenomenon and waste has been recognized as a potential field for exploration in materials management as well as in our day-to-day consumption pattern. It has been emphasized that many socio-economic problems which have a root cause in wasteful resource consumption can be solved by incorporating the phenomenon in our waste management practices.
Keywords: Inventory models; stock-dependent demand; stock-induced consumption; stock-induced waste; waste management.
Perishable inventory model with Markovian arrival process (MAP), retrial demands and multiple working vacations
by Vijaya Laxmi Pikkala, Soujanya M.L.
Abstract: In this paper, we consider a continuous review perishable inventory systemrnin which two types of customers, positive and negative, arrive according torna Markovian arrival process. The life time of an item and the lead time ofrnreorder are exponentially distributed. Demands that occur during stock outrnperiod or busy period either enter an orbit of size $N$ or are lost. Thernorbital demands compete their service with an exponential rate dependingrnon the number of demands in the orbit. The waiting demands in the orbit mayrnrenege the system after an exponentially distributed amount of time. The serverrntakes multiple working vacations at zero inventory. The steady staternjoint probability distribution of the number of customers in the orbit andrnthe inventory level is obtained. Various performance measures and cost analysisrnare shown with numerical results.
Keywords: Markovian arrival process; (s,S) policy; Replenishment time; Negative customers;rnMultiple working vacations; Matrix analytic method; Perishable items; Retrial demands.
Special Issue on: Sustainable Inventory Management
Closed-loop supply chain simulation with disruption considerations: A case-study on Tesla
by Pietro Gianesello, Dmitry Ivanov, Daria Battini
Abstract: Performance impact of severe disruptions in the reverse part of an automotive closed-loop supply chain is studied with the use of a discrete-event simulation model implemented in anyLogistix software. A hybrid case study-simulation methodology is applied in this research to analyze the six-echelon closed-loop supply chain of Tesla from positions of resilience. Based on the secondary data, an example for the German market has been created and investigated. More specifically, the results help to show how a disruption in the reverse supply chain may affect the financial and operational performances of the company. Different recovery policies have been simulated in order to analyse how each might recover the supply chain from disruption and restore its operation and performance.
Keywords: closed-loop supply chain; resilience; simulation; anyLogistix; disruption; case-study; performance; e-mobility; reverse logistics.
Dynamic Pricing and Profit Maximization: A Simulation based approach for Agri-fresh Products Retailing in India
by Lamay Bin Sabir, Jamal Ahmad Farooquie
Abstract: Fresh agri-food products, like fruits and vegetables (F&V), are perishable products having a very short shelf life. They are different from non-perishables in managing their inventories as customers are more concerned about the nutritious value and shelf life. Customers are becoming strategic and planning their purchase based on the markdown and other promotional activities. Retailers are finding it difficult to a trade-off between the prices and remaining shelf life for offering markdown. Therefore decisions depending upon the value and timing of such markdowns for not so fresh F&V are important. This paper attempts to address these issues based on previously published studies which suggested a simple procedure to identify the quantum and time of markdowns for perishable products inside a retail store. Extending the approach, monte-carlo simulation is applied in order to generate randomness in the probability of sales and demand for F&V. A questionnaire is used in order to get the primary data from 89 retailers from Delhi/NCR, India. Organized retail of F&V is still at starting stage in India and no such study has been attempted before.
Keywords: Perishable; Inventory; Profit; Simulation; Retail; Agri-fresh; Dynamic Pricing.
DETERMINISTIC INVENTORY MODEL FOR ITEMS WITH LINEAR DEMAND, VARIABLE DETERIORATION AND PARTIAL BACKLOGGING
by SAURABH SRIVASTAVA
Abstract: A deterministic inventory model is developed for a deteriorating item having linear demand and variable deterioration rate. Shortages are allowed and partially backlogged. In developing the model we have assumed that the rate of backlogging is variable and dependent on the waiting time for the next replenishment. The objective of the model is to develop an optimal policy that minimizes the total average cost. Suitable numerical example has been discussed to understand the problem. Sensitivity analysis has been carried out to show the effect of changes in the parameter on the optimum total average cost.
Keywords: Inventory; Deteriorating Item; Linear Demand; Shortages; Partial Backlogging; Variable Deteriorating Rate.
Single-vendor multi-buyer game theoretic model under multi-factor dependent demand
by Rekha Guchhait, Mitali Sarkar, Biswajit Sarkar, Sarla Pareek
Abstract: Market demand for any single-type of products depends upon multi-factors. Demand is
increasing day-by-day due to the globalization of products, customer's choice and finally, priorities are now changing according to these factors. In this scenario this paper deals with a single-vendor multiple-buyer supply chain model with imperfect production dependent-demand. This model has been solved by using decentralized and centralized policy and Stackelberg game approach is used to find optimum prot individually in decentralized case. Total prot has been maximized when
multi-factor dependent demand is considered in a single-vendor multi-buyer sustainable supply chain model. Numerical examples and managerial insights are delivered to illustrate the model numerically.
Keywords: Supply chain; imperfect production; variable demand; single-vendor multi-buyers; game theory.