Stock-dependent Demand Research Articles

Two-Warehouse Inventory Control for Deteriorating Items Using Hybrid and Stock-Dependent Demand with Partial Backlogging

Two-Warehouse Inventory Control for Deteriorating Items Using Hybrid and Stock-Dependent Demand with Partial Backlogging

A sustainable inventory model for a two-echelon cold chain with green technology investments and stock-dependent demand under carbon emissions tax regulation

Cold chains are specialised supply chains that make use of refrigerated storage facilities and distribution nodes. Products that have to be stored and distributed via cold chains are temperature-sensitive items such as perishable food or vaccines. If these products are not maintained at the correct temperatures, their safety and quality may be comprised with dire consequences for end-users. Operating refrigerated storage units consumes a lot of energy and the majority of transportation trucks used for distribution are powered by fossil fuels and therefore, cold chains are a major source of carbon emissions. With this in mind, this paper proposes a sustainable inventory model for a two-echelon cold chain with stock-dependent demand and green technology investments under a carbon emissions tax regulation. The carbon tax is imposed by policy makers to encourage the cold chain to reduce its emissions whereas, the green technology investment is a voluntary measure taken by the cold chain to reduce its carbon emissions. Based on the results, a carbon tax regulation is about 3% more effective than a green technology investment in terms of profit maximisation potential. Moreover, when it comes to investing in green technologies, there is an optimal investment amount above which increasing the investment results in decreased profits and increased emissions. Other avenues that the cold chain can explore in effort to improve profitability include increasing the potential market size, displaying higher volumes of stocks, using larger capacity transportation trucks and filling the trucks to capacity.

Note on “Joint dynamic pricing and freshness-keeping effort strategy for perishable products with price-, freshness-, and stock-dependent demand”

Note on “Joint dynamic pricing and freshness-keeping effort strategy for perishable products with price-, freshness-, and stock-dependent demand”

Two-Warehouse Inventory Model: Interval Valued Costs, Advanced Payment, Stock-Dependent Demand, and Partial Backlogging

A great deal of inventory costs are typically unpredictable because of the unpredictability of a competitive market. The fluctating demand from customer's and the unpredictability of the market economy make it difficult for researchers and operation research practitioners to appropriately replicate an inventory problem. In order to prevail this type of unpredictability circumstances, in this paper, we have represented the inventory parameters as interval. Using this concept, we progressed a two-warehouse inventory model for deteriorating items with a fixed Shelf life, partially backlogging shortages and interval-valued deterioration rate. In addition to this the parameters like ordering cost, purchase cost, shortage cost, deterioration cost for both the rented and owned warehouse except the backlogging parameter have been considered as interval-valued. The uncertainty in the inventory parameters motivated us to view them as interval-valued in the present research. Based on the assumptions, the cost function of this problem is a highly nonlinear constraint optimization problem. Mathematica is used to tackle this nonlinear optimization problem. A numerical example has been presented to demonstrate the computational result. Then, a sensitivity analysis has been performed to study the effect of changes of different parameters of the model on the optimal policy.

Optimization Problem for Deteriorating Items Model with Stock Dependent Demand and Controllable Deterioration Under Two Warehouse Storage Facility

Optimization Problem for Deteriorating Items Model with Stock Dependent Demand and Controllable Deterioration Under Two Warehouse Storage Facility

An Inventory Model for Deteriorating Items with Stock-Dependent Demand under Fuzzy Lead Time and Partial Backlogging

For inventory management purposes, lead time refers to the amount of time it takes for a purchase order to be completed. Its effect is an important phenomenon in inventory management system. It also plays a significant role when lead time unknown to the decision makers. This paper deals with an inventory model for deteriorating items under fuzzy lead time. The stock dependent demand with partially backlogged shortages are considered in the proposed model. The total inventory costs for both crisp model and fuzzy model are derived. The fuzzy lead time is assumed to be triangular and trapezoidal numbers. The signed distance methods (SD) is used for defuzzification purpose. The developed model is validated with the help of numerical illustration under both crisp and fuzzy scenario. A pictorial presentation is furnished to explain the behaviour of the total inventory costs towards lead-crisp, lead-triangular and lead-trapezoidal values. Lastly a sensitivity analysis is performed to judge the sensitive behaviour of the total cost towards changes of the cost parameters.

A Lot Sizing Model for a Deteriorating Product with Shifting Production Rates, Freshness, Price, and Stock-Dependent Demand with Price Discounting

A Lot Sizing Model for a Deteriorating Product with Shifting Production Rates, Freshness, Price, and Stock-Dependent Demand with Price Discounting

An inventory model with price- and stock-dependent demand and time- and stock quantity-dependent holding cost under profitability maximization

This paper focuses on inventory models with a broad framework for the storage cost and the demand rate. The cumulative storage cost is modelled with a power function, depending on both time and stock quantity, by using two elasticity coefficients. Similarly, the demand rate has an isoelastic dependence on sale price and stock quantity, modelled with another two elasticity coefficients. These four elasticity coefficients allow many real practical situations to be modelled. A reference price is used to measure the effect of the sale price on the demand rate. The goal is to maximize the income expense ratio (IER), and the sale price, the order level and the reorder point are the decision variables. The operating expense ratio (OER) of the system, defined as the quotient cost/income, is used to solve the problem. The optimum values are obtained with explicit expressions, which is an interesting result for inventory managers. Under the optimum policy, the reorder point is always equal to zero and the order quantity depends on the replenishing cost, the purchase price and the four elasticity coefficients. However, the optimum ordering policy does not depend on the scale parameters of the storage cost and the demand rate. A complete sensitivity analysis for most of the model parameters is performed. A numerical example is used to compare the optimum policies for the maximum income expense ratio and the maximum profit per unit time. Finally, some managerial insights derived from the results are given.

Inventory models for deteriorative items with price dependent demand integrated with stock dependent demand

Inventory models for deteriorative items with price dependent demand integrated with stock dependent demand

Fuzzy optimisation for economic ordered quantity model with stock-dependent demand and nonlinear holding cost

Fuzzy optimisation for economic ordered quantity model with stock-dependent demand and nonlinear holding cost

Optimal ordering policies for stock-dependent demand under partial linked-to-order credit period

Optimal ordering policies for stock-dependent demand under partial linked-to-order credit period

Production System for Delayed Deterioration Inventories with Two-Level Production Rate, Stock-Dependent Demand Rate and Linear Holding Cost Under Trade Credit Policy

This paper introduces an optimized total variable cost model for a production inventory system dealing with delayed deteriorating items. The model incorporates a two-level production rate and a stock-dependent demand rate, all operating under a trade credit policy. The demand rate remains constant during the inventory build-up period, but post-production, before deterioration, it varies based on product availability and nature. The inventory depletes to zero in the model’s final stage due to the combined impact of constant demand and deterioration rates. To characterize the optimality of the analytical results, the paper utilizes theorems and lemmas. The model’s dynamics are described by differential equations, which are solved using MATLAB. A numerical experiment is conducted to demonstrate the practicality of the developed models. Additionally, a sensitivity analysis is performed to illustrate how changes in selected system parameters affect the total variable costs determined in the numerical example. The paper concludes with suggestions and recommendations aimed at reducing the total variable cost. Ultimately, it is demonstrated that the developed model surpasses the one presented in the working paper. The proposed model could be used in inventory management and control of items that exhibit delayed in deterioration to minimises the total variable cost when sudden distraction of production process occurred as revealed by the the result presented.

Effect of Rented Warehouses for Deteriorating Items Under Stock Dependent Demand, Partial Backlogging

In the area of two warehouse-based inventory models, various studies have been carried out, and the authors presented their models under different parameters and environmental conditions. In most of the study, it can be seen that one warehouse was assumed to be its own warehouse and other was assumed to be rented. Due to different facilities and conditions, both warehouses have different rates of demand and deterioration, along with different storage capacities. A study has already been done by considering both warehouses as ranted. It was also assumed in the study that both warehouses had the same capacity. In addition, it has also been assumed that the items in the second ranted warehouse start decaying after some time, whereas the items in the first warehouse were used first to meet the demand of the customers. After critically reviewing the model published on two ranted warehouses, it can be observed that the storage techniques of items need to be further explored, as the model used the items from the first warehouse to satisfy the demand of the customers, while the items whose deterioration was about to start were stored in the second warehouse. This concept of storage has to change, as items in the second warehouse totally deteriorate until their turn comes up. Keeping this fact in mind, we have developed an inventory model based on two different warehouses for deteriorated items whose rate of deterioration is not so high, but after a very short period of time, these items start decaying. According to the current model, the demand of the customers has been satisfied in the first warehouse; to avoid deterioration in the second warehouse, as a result, transfer such items whose deterioration is about to start from the second warehouse to the first warehouse so that deterioration of the items must be minimize. In the current model, it has been assumed both warehouses are rented, which is suitable for the manufacturer whose product demand is very high and space is not enough. It is obvious that the demand for the items in the stock increases due to the stock reaching a certain level. In the model, the demand for the first warehouse is assumed to be stock-dependent. When, there is extra stock, the second warehouse is used for the products, and author also assumed that the demand has become constant. The model is also instigated under sensitivity analysis, and a brief numerical example with real data has been illustrated.

A new economic order quantity model for deteriorated items under the joint effects of stock dependent demand and inflation

In the present market scenario, it is seen that commodity is attracted by the stock of the items. Considering this fact in this present work, the demand for the item is considered as stock dependent in an inventory control system, where the items are deteriorating in nature. When the number of items in the stock increases, the number of deteriorations also increases. Also, this is important to know for a retailer that when an order will be placed and when the order will be received from the supplier. So, the lead time has an important role in the inventory control system in this stock-dependent demand inventory model. Also, it is seen that the market price of any item may increase gradually with time. Considering this phenomena, the inflation has been incorporated in this work. Here, the proposed model has been analyzed in a finite time horizon. From our analysis, the optimal profit has been calculated for optimal replenishment period of each cycle. Also, depending on the changes in the parameters such as demand, stock, and deterioration, the changes in optimal profit have been analyzed numerically and graphically in the numerical section and the effects of inflation also has been analyzed in this section. As the parameters associated with the system are not always deterministic, so uncertainty arises in the model. To remove this uncertainty, the model has been extended to a fuzzy model considering the q-fuzzy membership function. The fuzzy model has been defuzzified using the Center of Gravity (COG) method and fuzzy extension principle. Also, the fuzzy model has been analyzed by numerical illustration and some sensitivity analysis have been shown corresponding to different values of q and different membership values of the fuzzy parameters.

TWO WAREHOUSES PRODUCTION INVENTORY MODEL FOR DETERIORATING ITEMS WITH STOCK-DEPENDENT DEMAND UNDER PRESERVATION TECHNOLOGY USING MODIFIED GENETIC ALGORITHM

This paper considers two warehouses production inventory model for deteriorating items with stock-dependent demand and completely backlogged shortages under preservation technology. For display and storage of inventory, one warehouse of finite capacity is located at the main market, called primary warehouse (PW) and another warehouse with large capacity at a small distance from the main market, called secondary warehouse (SW). Here we consider items are transported from SW to PW in continuous release pattern and the transportation cost is negligible. The aim of this study is to obtain the optimal cycle length for maximum average profit through a modified genetic algorithm (MGA). Finally the model is illustrated using a numerical example. A sensitivity analysis of the optimal solution with respect to the parameters of the system is carried out.

AN OPTIMAL DECISION MODEL FOR AMELIORATING INVENTORY ITEMS WITH STOCK DEPENDENT DEMAND

In marketplace, it is normally observed that the utility of some items increases with time. For instance, in breweries, the value of some stocked wine increases with time. In farms, the quantity or weight of fish, fast growing animals including broilers, sheep, and so on, increase with time. These phenomena are termed amelioration. In this paper therefore, we study an inventory model that determines the optimal replenishment decision for ameliorating items with stock dependent demand where the holding cost and the rate of amelioration are considered constants. The concept of differential and integral calculus was used to optimize the cost function to obtain numerical examples that illustrate the effects of parameter changes on the decision variables and to find the optimum number of replenishments. The model could be used by the organizations that deal with the relevant items.

Effect of stock-dependent demand in EOQ models for deteriorative items under linear, quadratic and exponential holding cost

Inventory models for deteriorative items with stock-dependent demand for deteriorative items in linear, quadratic and exponential time dependent holding cost are considered in this study. To wit, no study exists that uses effect of stock-dependent demand for deteriorative items in linear, quadratic and exponential time dependent holding cost. Four models are developed: the first model uses stock-dependent demand with constant holding cost; the second model uses stock-dependent demand in linear holding cost; the third model uses stock-dependent demand in quadratic holding cost; and the fourth model uses stock-dependent demand with exponential holding cost. Mathematical models are delineated for each model and relevant examples are provided to elucidate the proposed procedure. The objective herein is to obtain optimum order quantities and order intervals with respect to overall cost. Numerical examples are provided for all four cases to validate the proposed model. Sensitivity analysis is provided for each of the four models. The necessary data was generated using visual basic 6.0.

Optimal ordering policy for deteriorating items with stock dependent demand, partial backlogging and trade credit period

In this paper, policies of optimal ordering has been focused on economic order quantity (EOQ) model, where we considered deteriorated as well as non-instantaneous nature items. In this inventory model, we are also assuming there is a stock-dependent demand and constant holding cost. Occurrence of shortage was assumed during the complete process of the system, taking into consideration with partial backlogging where deterioration of items follows the Weibull distribution. In the present study, it is considered that the supplier's proposed lucrative trade credit offers to the retailers to buy more to generate more revenue. Numerical examples parallel to the present inventory model gives an optimal result. Lastly, sensitivity analysis applied to different parameters and graphical representations have shown to validate the model.

Analysing the Imperfect Production Model for Decaying Products with Advertisement and stock dependent demand

Analysing the Imperfect Production Model for Decaying Products with Advertisement and stock dependent demand

Analysing the imperfect production model for decaying products with advertisement and stock dependent demand

Analysing the imperfect production model for decaying products with advertisement and stock dependent demand