Abstract— Clustering schemes offer a practical way of providing scalability when dealing with large and dense Mobile Ad hoc Networks (MANETs). The feasibility of a clustering method can be primarily determined by the complexity of the cluster head selection. Optimizing the cluster head selection allows for the network to be more efficient by minimizing the signaling overhead while ensuring that the network connectivity is maintained despite topology changes. In this paper, we investigate the problems of cluster head selection for large and dense MANETs. Two variants of the cluster head selection are examined: (1) the distance-constrained selection where every node in the network must be located within a certain distance to the nearest cluster head; and (2) the size-constrained selection where each cluster is only allowed to have a limited number of members. We show that the problem of minimizing the set of cluster heads is NP-hard for both variants. We propose two distributed selection algorithms, each having logarithmic approximation ratio, for these variants. We also discuss, using simulations, the resulting cluster size distribution and cluster head density, which impact the efficient operation of the network.

Abstract— Wireless ad-hoc networking has become an irreplaceable technology in modern communication system where communication infrastructure is insufficient or unavailable. Ad-hoc network is a collection of self-organizing nodes that are rapidly deployable and adaptable to frequent topology changes. The evolution of the Multimedia Technology & the Commercial Interest of Companies to reach civilian applications has made QoS in MANETs an unavoidable task. Resource limitations and variations add to the need for QoS provisioning. Use of MANETs in critical and delay sensitive applications demands service differentiation. Maintaining appropriate Quality of Service (QoS) for MANETs is a complex task due to the dynamic behavior of the network topology. The goal of QoS provisioning is to achieve network behaviors that are deterministic, so that information carried by the network can be better delivered and network resources can be better utilized. In this paper, we are going to analyze the multiparametric approach to perform QoS analysis of mobile ad-hoc network.

Abstract— Nowadays, fingerprint recognisation used in many real applications. However, recognizing fingerprints in poor quality images is still a very complex problem. In recent years, many algorithms, models… are given to improve the accuracy of recognition system. This paper discusses on the standardized fingerprint model which is used to synthesize the template of fingerprints. In this model, after pre-processing step, we find the transformation between templates, adjust parameters, synthesize fingerprint, and reduce noises.