Some recent results of the CODALEMA experiment

Codalema is one of the experiments devoted to the detection of ultra high energy cosmic rays by the radio method. The main objective is to study the features of the radio signal induced by the development in the atmosphere of extensive air showers (EAS) generated by cosmic rays in the energy range of 10 PeV-1 EeV . After a brief presentation of the detector features, the main results obtained are reported (emission mechanism, lateral distribution of the electric field, energy calibration, etc.). The first studies of the radio wave front curvature are discussed as new preliminary results.Comment: Proc. of the annual meeting of the French Society of Astronomy & Astrophysics SF2A, Paris, June 2011, G. Alecian, K. Belkacem, R. Samadi and D. Valls-Gabaud (eds

A Dynamic Multimedia User-Weight Classification Scheme for IEEE_802.11 WLANs

In this paper we expose a dynamic traffic-classification scheme to support multimedia applications such as voice and broadband video transmissions over IEEE 802.11 Wireless Local Area Networks (WLANs). Obviously, over a Wi-Fi link and to better serve these applications - which normally have strict bounded transmission delay or minimum link rate requirement - a service differentiation technique can be applied to the media traffic transmitted by the same mobile node using the well-known 802.11e Enhanced Distributed Channel Access (EDCA) protocol. However, the given EDCA mode does not offer user differentiation, which can be viewed as a deficiency in multi-access wireless networks. Accordingly, we propose a new inter-node priority access scheme for IEEE 802.11e networks which is compatible with the EDCA scheme. The proposed scheme joins a dynamic user-weight to each mobile station depending on its outgoing data, and therefore deploys inter-node priority for the channel access to complement the existing EDCA inter-frame priority. This provides efficient quality of service control across multiple users within the same coverage area of an access point. We provide performance evaluations to compare the proposed access model with the basic EDCA 802.11 MAC protocol mode to elucidate the quality improvement achieved for multimedia communication over 802.11 WLANs.Comment: 15 pages, 8 figures, 3 tables, International Journal of Computer Networks & Communications (IJCNC

MEASURING THE EFFICIENCY OF EUROPEAN BANKS: A DIRECTIONAL DISTANCE FUNCTION APPROACH.

The aim of this paper was to estimate the technical efficiency of 423 European banks during the period 2013?2015 while simultaneously dealing with discretionary, non-discretionary, desirable, and undesirable factors. The author used the Directional Distance Function approach. Particularly, he considered the fixed assets as a non-discretionary input and the non-performing loans as an undesirable output. The empirical results revealed significant effects on inefficiency measures in comparison to those obtained when excluding undesirable outputs. Moreover, the outcomes showed an increasing level of the average inefficiency for most European countries. These outcomes confirmed the persistence of the negative impact of the financial crises and the inability of the European banking system to really recover from these crises

An estimate of maintenance efficiency in Brown-Proschan imperfect repair model with bathtub failure intensity

Purpose: Estimate the maintenance efficiency in the Brown-Proschan model with the bathtub failure intensity. Design/methodology/approach: Empirical research through which we propose a framework to establish the characteristics of failure process and its influence on maintenance process. Findings: The main contribution of the present study is the reformulation of the Brown and Proschan model using the bathtub failure intensity Practical implications: Our model is defined by BP reformulation one using bathtub failure intensity. This form of intensity is presented like superposition of two NHPP and Homogeneous Poisson one. Originality/value: This is the follow on research on the study that employed the power-law-process type of failure intensity.Peer Reviewe

A Bi-Level Multi-Objective Approach for Web Service Design Defects Detection

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152453/1/JSS_WSBi_Level__Copy_fv.pd

An Adaptive Multimedia-Oriented Handoff Scheme for IEEE 802.11 WLANs

Previous studies have shown that the actual handoff schemes employed in the IEEE 802.11 Wireless LANs (WLANs) do not meet the strict delay constraints placed by many multimedia applications like Voice over IP. Both the active and the passive supported scan modes in the standard handoff procedure have important delay that affects the Quality of Service (QoS) required by the real-time communications over 802.11 networks. In addition, the problem is further compounded by the fact that limited coverage areas of Access Points (APs) occupied in 802.11 infrastructure WLANs create frequent handoffs. We propose a new optimized and fast handoff scheme that decrease both handoff latency and occurrence by performing a seamless prevent scan process and an effective next-AP selection. Through simulations and performance evaluation, we show the effectiveness of the new adaptive handoff that reduces the process latency and adds new context-based parameters. The Results illustrate a QoS delay-respect required by applications and an optimized AP-choice that eliminates handoff events that are not beneficial.Comment: 20 pages, 14 figures, 4 table