Wireless sensors networks are used in several fields of application, in most applications, knowing the location of the sensors nodes is necessary. According to the distribution of the calculations on sensors nodes, the localization techniques are classified into two techniques: centralized and decentralized (distributed). Distributed localization techniques can be classified into two categories: range free and range based. DV-HOP is a range free simple localization algorithm, but it has low localization accuracy, despite the improvements of the proposed DV-Hop algorithms. Maintaining a balance between a high location accuracy and good stability and simplicity is always a challenge. In this article, we have focused our study on the localization algorithm range free DV-HOP, the study is based on the accuracy error which is the most important factor in the localization. To better study the DV-HOP algorithm, we implemented DV-HOP using MATLAB. The purpose of this article is to present Range Free localization techniques and open up a perspective of proposing new localization techniques in wireless sensors networks.
This study addresses the problem of inventory management in a multi-level retailers' network of the company Lit Mag that manufactures and distributes mattresses. Its distribution network constitutes a central warehouse and several distribution centers located in Algerian cities, and each center delivers vendors to the area and each vendor is connected to set of customers. The network studied is composed of several levels: the starting point is the warehouse, the first level of the distributors, the second level for sellers and the last level for customers. each retailer in the network handles its order locally and independently of other retailers. In this work, we propose a collaboration between the different actors of the same level, by the exchange of products between them, in order to satisfy the demand of a seller by the residual stock of another neighbor seller and this is applied to all stages of the network. The purpose of this study in to see the impact of product exchanges in the distribution networks and their influence on the total costs of the logistics chain from the central warehouse to the final customer