Overlapping Multi-hop Clustering for Wireless Sensor Networks

Clustering is a standard approach for achieving efficient and scalable performance in wireless sensor networks. Traditionally, clustering algorithms aim at generating a number of disjoint clusters that satisfy some criteria. In this paper, we formulate a novel clustering problem that aims at generating overlapping multi-hop clusters. Overlapping clusters are useful in many sensor network applications, including inter-cluster routing, node localization, and time synchronization protocols. We also propose a randomized, distributed multi-hop clustering algorithm (KOCA) for solving the overlapping clustering problem. KOCA aims at generating connected overlapping clusters that cover the entire sensor network with a specific average overlapping degree. Through analysis and simulation experiments we show how to select the different values of the parameters to achieve the clustering process objectives. Moreover, the results show that KOCA produces approximately equal-sized clusters, which allows distributing the load evenly over different clusters. In addition, KOCA is scalable; the clustering formation terminates in a constant time regardless of the network size

ICT contribution to growth; the case of tunisia

The aim of this paper is to examine the impact of Information and Communication Technologies (ICT) on the growth of developping countries and especially on the Tunisian economy. The first part of the article summerizes the relationship between growth, productivity and ICT. We show that under some necessary conditions ICT may boost the growth in the developping countries. In the second part of the article, we estimate the contribution of ICT to the growth of Tunisia due to ICT diffusion and adoption. We compare our econometric estimation to the results obtained in France and United States.croissance économique, TIC, productivité, développement économique, Tunisie.

Energy Consumption, Economic Growth and CO2 Emissions in Middle East and North African Countries

This article extends the recent findings of Liu (2005), Ang (2007), Apergis et al. (2009) and Payne (2010) by implementing recent bootstrap panel unit root tests and cointegration techniques to investigate the relationship between carbon dioxide emissions, energy consumption, and real GDP for 12 Middle East and North African Countries (MENA) over the period 1981–2005. Our results show that in the long-run energy consumption has a positive significant impact on CO2 emissions. More interestingly, we show that real GDP exhibits a quadratic relationship with CO2 emissions for the region as a whole. However, although the estimated long-run coefficients of income and its square satisfy the EKC hypothesis in most studied countries, the turning points are very low in some cases and very high in other cases, hence providing poor evidence in support of the EKC hypothesis. Thus, our findings suggest that not all MENA countries need to sacrifice economic growth to decrease their emission levels as they may achieve CO2 emissions reduction via energy conservation without negative long-run effects on economic growth.Environmental Kuznets Curve, carbon dioxide emissions, energy consumption, growth

The complementarities between Infomation and Communication Technologies Use, New Organizational Practices and Employee's Contextual Performance: Evidence from Europe in 2005 and 2010

International audienceThis article investigates the relationship between Information Technologies (IT), new organizational practices and workers' contextual performance in the European context. Our empirical results are based on data about more than 11000 employees from 16 European countries in 2005 and more than 16000 in 2010. First, we find asymmetric effects of IT use. Internet use is, indeed, positively related to all aspects of contextual performance in 2010, while computer use has been positively associated with contextual performance in 2005 but not in 2010. Second, we find that most of the considered new organizational practices have a positive relationship with employees' contextual performance.Cet article analyse les relations entre les Technologies de l'Information (TI), les nouvelles pratiques organisationnelles et la performance contextuelle des employés dans le contexte européen. Nos résultats empiriques sont basés sur des bases de données concernant plus de 11 000 employés de 16 pays européens en 2005 et plus de 16 000 en 2010. Premièrement, nos résultats soulignent des effets asymétriques de l'usage des TI. L'usage d'Internet est, en effet, positivement lié à tous les aspects de la performance contextuelle en 2010, tandis que l'usage de l'informatique est associé positivement seulement à la performance contextuelle interpersonnelle en 2005. Deuxièmement, nous constatons que la plupart des nouvelles pratiques organisationnelles considérées ont une relation positive avec la performance contextuelle des employés

Bridging the Learning Gap in the Marketfor Higher Education: E‐learning and Public Subsidies

This article aims at analyzing the adoption patterns which apply on the market for higher education when two types of learning organizations – namely, traditional learning and e‐learning organizations – provide educational programs. We focus on the impact of public subsidies to e‐learning providers in order to evaluate the conditions under which the learning gap is bridged. A welfare analysis is introduced to estimate the relevance of such ‘pro e‐learning’ public policies. Our first results show that public subsidies enable the e‐learning organization to provide quality‐based and pricing strategies that tend to be similar to those of the brick’n mortar organization. Besides, we find that such short‐term policies positively impact on the global level of quality which is provided by both providers. Nevertheless, our welfare analysis underlines contrasted results about the relevance of such short‐term public policies

A Survey of Active Networks

Active networks represent a significant step in the evolution of packet-switched networks, from traditional packet-forwarding engines to more general functionality supporting dynamic control and modification of network behavior. However, the phrase ^\active network^] means different things to different people. This survey introduces a model and nomenclature for talking about active networks, describes some possible approaches in terms of that nomenclature, and presents various aspects of the architecture being developed in the DARPA-funded active networks program. Also, a snapshot of the current research issues and activities of different institutions is provided. Potential applications of active networks are highlighted, along with some of the challenges that must be overcome to make them reality

Regional disparities and ICTs diffusion in Tunisia

The aim of this article consists in showing in what the emergence of new generation of information and communication technologies can be a worsening factor of imbalances between urban zones and rural zones and contribute to a thickening of the urban zones. Contrary to presupposed theoretical praising the capacity of these technologies to rebalance the development and to reverse the location of economic agents with their location. We will show in what these technologies could lead to a greater urban concentration in the less developed Countries (LDC’s). Indeed, four complementary explanatory factors are explained and illustrated in the case of Tunisia. The territorial dynamics engaged by the concentration of industries in the cities finds a second breath with the ICT.disparités spatiales, fracture numérique, Technologies de l’information et de la communication, Exode rural, localisation spatiale.