Stock-dependent Demand Research Articles

Two warehouse inventory models of breakable items with stock dependent demand under trade credit policy with respect to both supplier and retailer

Two warehouse inventory models of breakable items with stock dependent demand under trade credit policy with respect to both supplier and retailer

Two warehouse inventory models of breakable items with stock dependent demand under trade credit policy with respect to both supplier and retailer

For the first time, this study deals with a nonlinear form of breakability in two-warehouse inventory control for stock dependent demand. Moreover, this paper relates to two warehouse inventory policies with continuous release patterns along with two-level credit periods with respect to both supplier and retailer. Since per unit selling price is greater than that of purchasing cost, a new approach is introduced for payment to the wholesaler for the amount remaining after the credit period. Here, the retailer earns the required amount before the end of the business period and clears his due as soon as it is available. The sales and interest for the remaining period are deposited for maximising profit and consequently minimising the total inventory cost. Here, the decision variables are business periods for rented and market warehouse. The model has been developed as a cost minimisation problem with respect to the retailer and wholesaler and optimised using the nonlinear optimisation technique - generalised reduced gradient method (LINGO 13.0). The optimal solution has been exemplified numerically and graphically in this study of approach.

A fuzzy inventory model for deteriorating items with stock dependent demand rate

The present paper proposes a fuzzy economic order quantity (EOQ) model for deteriorating items with stock dependent demand rate where shortages are not allowed. The cycle time is divided into two parts. The first interval demand is considered as stock dependent and the second part is assumed to be constant. We first develop a crisp model. Since most of the parameters of the inventory model are uncertain, we consider the demand, holding cost, deterioration cost and deterioration rate as triangular fuzzy numbers. Graded mean representation, signed distance method and centroid method are used to defuzzify the total cost function. The results obtained by these methods are compared with the help of a numerical example. Sensitivity analysis is also carried out to explore the effect of changes in the values of the system parameters.

Integrated supply chain model for deteriorating items with linear stock dependent demand under imprecise and inflationary environment

In this paper, we develop an integrated supply chain model for deteriorating item, with linear stock dependent demand, taking into account the views of both the vendor and the multi-buyer under imprecise and inflationary environment. We have used the implicit cost in this model and use function principle to calculate the fuzzy total supply chain cost and graded mean integration representation method is used to defuzzify the fuzzy total supply chain costs.

Quantity discount for integrated supply chain model with back order and controllable deterioration rate

Due to uncertainty in economy, business players examine different ways to ensure the survival and growth in the competitive atmosphere. In this scenario, the use of effective promotional tool and co-ordination among players enhance supply chain profit. The proposed model deals with the effect of quantity discount on an integrated inventory system for constantly deteriorating items with fix life time. We use advertisement and quantity discount to accelerate stock dependent demand and further, the offered preservation technology for controlling deterioration rate. The model is validated numerically, and the sensitivity analysis for critical supply chain parameters is carried out. The results can be used in the decision making process of the supply chains associated with the supply of cosmetic, tinned food, drugs, and other FMCGs.

Integrated supply chain model for deteriorating items with linear stock dependent demand under imprecise and inflationary environment

Integrated supply chain model for deteriorating items with linear stock dependent demand under imprecise and inflationary environment

A fuzzy inventory model for deteriorating items with stock dependent demand rate

The present paper proposes a fuzzy economic order quantity (EOQ) model for deteriorating items with stock dependent demand rate where shortages are not allowed. The cycle time is divided into two parts. The first interval demand is considered as stock dependent and the second part is assumed to be constant. We first develop a crisp model. Since most of the parameters of the inventory model are uncertain, we consider the demand, holding cost, deterioration cost and deterioration rate as triangular fuzzy numbers. Graded mean representation, signed distance method and centroid method are used to defuzzify the total cost function. The results obtained by these methods are compared with the help of a numerical example. Sensitivity analysis is also carried out to explore the effect of changes in the values of the system parameters.

An integrated inventory model with variable holding cost under two levels of trade-credit policy

This paper presents an integrated vendor-buyer model for deteriorating items. We assume that the deterioration follows a constant rate with respect to time. The vendor allows a certain credit period to buyer in order to promote the market competition. Keeping in mind the competition of modern age, the stock-dependent demand rate is included in the formulated model which is a new policy to attract more customers. Shortages are allowed for the model to give the model more realistic sense. Partial backordering is offered for the interested customers, and there is a lost-sale cost during the shortage interval. The traditional parameter of holding cost is considered here as time-dependent. Henceforth, an easy solution procedure to find the optimal order quantity is presented so that the total relevant cost per unit time will be minimized. The mathematical formation is explored by numerical examples to validate the proposed model. A sensitivity analysis of the optimal solution for important parameters is also carried out to modify the result of the model.

Inventory models for stock-dependent demand and time varying holding cost under different trade credits

Deterioration, a continuous process of all items, may be low or high for different items. This paper develops an inventory model for stock-dependent demand and time varying holding cost under different trade credits, considering four different situations. The second order approximations are used for exponential terms. Optimal solutions are obtained using Mathematica 9.0 software. Numerical examples and sensitivity analysis are provided to illustrate the proposed model.

Two warehouses Inventory Model with Stock-dependent demand and Maximum life time

Two warehouses Inventory Model with Stock-dependent demand and Maximum life time

Production Inventory Model for Deteriorating Items with Different Deterioration Rates under Stock and Price Dependent Demand and Shortages

Production Inventory Model for Deteriorating Items with Different Deterioration Rates under Stock and Price Dependent Demand and Shortages

Inventory of complementary products with stock dependent demand under vendor managed inventory with consignment policy

This paper proposes an integrated two-stage model, which consists of one vendor and one buyer for two complementary products. The vendor produces two types of products and delivers them to the buyer in distinct batches. Buyer stocks items in the warehouse and on the shelf. The demand for each product is sensitive to stock levels of both products. A vendor managed inventory with consignment stock policy is considered. The number of shipments and replenishment lot sizes are jointly determined as decision variables in such a way that total profit is maximized. The numerical study shows that as complementary rate increases, the quantity of transfers and demand of both products increase. Hence, ignoring the complementation between products leads to some customers lost.

A two-warehouse inventory model for non-instantaneous deteriorating items with interval-valued inventory costs and stock-dependent demand under inflationary conditions

This research work develops a two-warehouse inventory model for non-instantaneous deteriorating items with interval-valued inventory costs and stock-dependent demand under inflationary conditions. The proposed inventory model permits shortages, and the backlogging rate is variable and dependent on the waiting time for the next order, and inventory parameters are interval-valued. The main aim of this research is to obtain the retailer’s optimal replenishment policy that minimizes the present worth of total cost per unit time. The optimization problems of the inventory model have been formulated and solved using two variants of particle swarm optimization (PSO) and interval order relations. The efficiency and effectiveness of the inventory model are validated with numerical examples and a sensitivity analysis. The proposed inventory model can assist a decision maker in making important replenishment decisions.

Expected Value of Exponential Fuzzy Number and Its Application to Multi-item Deterministic Inventory Model for Deteriorating Items

Possibility, necessity, and credibility measures play a significant role to measure the chances of occurrence of fuzzy events. In this paper, possibility, necessity, and credibility measures of exponential fuzzy number, and its expected value has been derived. A multi-item two-warehouse deterministic inventory model for deteriorating items with stock-dependent demand has been developed. For the proposed inventory model, the different costs and other parameters are considered in exponential fuzzy nature. Solution methodology of this model using expected value has been discussed. A numerical example is considered to illustrate the multi-item two-warehouse deterministic inventory model. Finally, few sensitivity analyses are presented under different rates of deterioration to check the validity of the proposed model.

A computational approach to economic production quantity model for perishable products with backordering shortage and stock-dependent demand

This paper deals with an Economic Production Quantity (EPQ) model to determine production-inventory policies for perishable products. Shortage is permitted and fully backordered. The demand rate is stochastic- and stock-dependent. Since the problem is mathematically challenging and intractable via analytical approaches, this paper designs a simulation-based optimization algorithm by combining a grid search and a simulation model to solve the problem. The grid search plays the role of optimizer to determine the model variables, and the simulation model is utilized to evaluate the quality of solutions obtained by the optimizer through an iterative procedure. Eventually, a numerical example is discussed to illustrate how the solution procedure works, and a comparison study is carried out to demonstrate the superiority of suggested approach.Moreover, a comprehensive sensitivity analysis with respect to the problem parameters is performed.

A two-warehouse integrated inventory model with imperfect production process under stock-dependent demand and quantity discount offer

ABSTRACTThis paper presents a single-vendor single-buyer integrated inventory model with an imperfect production process of the vendor. The demand at the buyer is dependent on the on-hand stock (both at the own and rented warehouses) and the vendor offers a quantity discount to motivate the buyer to buy more quantities. The buyer's own warehouse has a limited capacity but, if needed, he can use rented warehouse of unlimited capacity. The vendor fulfils the buyer's order quantity in multiple equal-sized shipments. The objective is to determine the vendor's shipment scheme in response to the buyer's order quantity so that the average total cost of the integrated system is minimised. For a numerical example, the optimal solution of the integrated inventory model is obtained and effects of key model-parameters on the optimal solution are examined.

An economic production model for deteriorating items and time dependent demand with rework and multiple production setups

Recently, much emphasis has given to study the control and maintenance of production inventories of the deteriorating items. Rework is one of the main issues in reverse logistic and green supply chain, since it can reduce production cost and the environmental problem. Many researchers have focused on developing rework model, but few of them have developed model for deteriorating items. Due to this fact, we take up productivity and rework with deterioration as the major concern in this paper. In this paper, a production-inventory model with deteriorative items in which one cycle has n production setups and one rework setup (n, 1) policy is considered for deteriorating items with stock-dependent demand in case 1 and exponential demand in case 2. An effective iterative solution procedure is developed to achieve optimal time, so that the total cost of the system is minimized. Numerical and sensitivity analyses are discussed to examine the outcome of the proposed solution procedure presented in this research.

Comprehensive solution procedure for optimizing replenishment policies of instantaneous deteriorating items with stock-dependent demand under partial trade credit linked to order quantity

Trade credit financing is widely accepted as an inevitable strategy to increase profitability in inventory management. We assume that the supplier offers the retailer a fully permissible delay of M periods if the retailer orders more than or equal to a predetermined order quantity w. We revisit an economic order quantity model for instantaneous deteriorating commodities with inventory level dependent demand rate in a supply chain environment by allowing shortages which are partially backlogged. This model also incorporates aspects such as complete and no backlogging. The necessary and sufficient conditions for the existence and uniqueness of this model using the lemmas are investigated. An effective algorithm is proposed to obtain the optimal replenishment policies of this model using SCILAB 5.5.0 to resolve the problem. Finally, we solve numerical examples to substantiate the theoretical results of the underlying model and obtain some managerial insights.

Two-warehouse inventory model for non-instantaneous deteriorating items with stock-dependent demand and inflation using particle swarm optimization

We investigate a two-warehouse inventory model for non-instantaneous deteriorating items with partial backlogging and stock-dependent demand under inflationary conditions. Shortages are allowed. The backlogging rate is variable and depends on the waiting time for the next replenishment. This paper seeks to determine an optimal replenishment policy that minimizes the present value of the total cost per unit time. The necessary and sufficient conditions for the existence and uniqueness of the optimal solution are found. The corresponding problems are formulated and solved with particle swarm optimization. Numerical experimentation and post-optimality analysis are conducted.

Supply Chain Model with Two Storage Facility for Stock Dependent Demand Incorporating Learning and Inflationary Effect under Crisp and Fuzzy Environment

In this paper, a supply chain model with power form stock-dependent demand rate is developed, incorporating the effect of learning and inflationary environment. In order to bring their research closer to reality, all the cost parameters involved in the model are considered fuzzy in nature. The demand rate is assumed to be a polynomial form of current inventory level in Own-warehouse. To display the items, retailer has one warehouse of finite capacity, treated as own warehouse (OW) and may hire another warehouse of large capacity, treated as rented warehouse (RW) to storage the excess inventory. Learning effect is incorporated on retailer's selling price, purchasing cost, part of holding cost, deterioration cost and ordering cost. Proposed model is illustrated with some numerical example along with sensitivity analysis of parameters.