the inventory routing problem (irp) arises in the context of vendor-managed systems. this problem addresses jointly solving an inventory management problem and a vehicle routing problem. in this paper, we consider a multi-depot multi-vehicle inventory routing problem in which suppliers produce one type of product to be delivered to customers during a finite time horizon. we propose a two-phase ...

We address multi-item inventory systems with random and seasonally fluctuating, and possibly correlated, demands. The items are produced in two stages, each with its own lead-time; in the first stage a common intermediate product is manufactured. The production volumes in the first stage are bounded by given capacity limits. We develop an accurate lower bound and close-to-optimal heuristic stra...

This research presents an alternative heuristic algorithm to solve the vendor management inventory system with multi-product and multi-constraint based on EOQ with backorders considering two classical backorders costs: linear and fixed. For this type of inventory system, the optimization problem is a nonlinear integer programming (NLIP). Several numerical examples are given to demonstrate that ...

This study extends a mathematical model that integrates the location, allocation, inventory replenishment and routing decisions simultaneously. To cope with inherent uncertainty of parameters, we implement a continuous-time Markov process and derive the performance measures of the system. Using the obtained results, the problem is formulated as a mixed integer nonlinear programing model (MINLP)...

The aim of lot sizing problems is to determine the periods where production takes place and the quantities to be produced in order to satisfy the customer demand while minimizing the total cost. Due to its importance on the efficiency of the production and inventory systems, Lot sizing problems are one of the most challenging production planning problems and have been studied for many years wit...

In this paper we consider a single-item inventory systemwith lost sales and fixed order cost. We numerically illustrate the lack of a clear structure in optimal replenishment policies for such systems. However, policies with a simple structure are preferred in practical settings. Examples of replenishment policies with a simple parametric description are the (s, S) policy and the (s,nQ) policy....

The multi-item single level capacitated dynamic lot-sizing problem consists of scheduling N items over a horizon of T periods. The objective is to minimize the sum of setup and inventory holding costs over the horizon subject to a constraint on total capacity in each period. No backlogging is allowed. Only one machine is available with a fixed capacity in each period. In case of a single item p...

We developed a mixed integer linear programming model for an integrated decision problem of production, inventory, and transportation planning. Our model combines the direct shipment into the production, inventory, and distribution planning. The objective was to minimize the total operation cost which is comprised of production setup cost, inventory holding cost, transportation cost, and reorde...

We consider a single warehouse where spare parts of multiple stock-keeping units are kept on stock to serve customers with (close-to-)identical machines. Customers are divided into multiple customer classes, and a target aggregate fill rate is set per class. In order to get differentiated service levels, critical level policies are assumed. We formulate a multi-item, single-stage spare parts in...

In this research, an integrated inventory problem is formulated for a single-vendor multiple-retailer supply chain that works according to the vendor managed inventory policy. The model is derived based on the economic order quantity in which shortages with penalty costs at the retailers` level is permitted. As predicting customer demand is the most important problem in inventory systems and th...