Ultralight vector dark matter search using data from the KAGRA O3GK run

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM

A Handover Optimisation Scheme in Cellular Networks

National audienc

Taxonomy of energy efficiency methods for cloud data centers

National audienceDatacenters and Cloud computing technologies are now in their growth stage with the generalization of Information Technologies. As useful as they may seem, their operation causes many problems among which energy consumption is one of the most worrying. Several techniques have been developed to reduce energy consumption in Datacenter environments. They differs by the methods used to analyze consumer trends, energy reduction mechanisms as well as assessment tools. Their results depend on the study contexts and are generally adapted to similar environments. In this work, we aim to present a state of art and a classification of the most important techniques of energy reduction in the virtualized environment of the Cloud. This classification, the first one at our knowledge, represent a basic framework for others enhancements of energy efficiency methods in Datacenters

State of the art on data flow prediction methods in computers networks.

National audienceDuring last decade, data processing has rapidly shifted from corporate computing system to big virtualized datacenters. To cope with this change, computer and network resource management has completely changed in terms of offers, access and integration of QoS. To cope to this new difficulties and make the right decisions at the right time, administrators and engineers need to have a better visibility on incoming traffic. In recent years, many researchers worked on traffic prediction methods that can help achieving these goals. In this paper, we provide an overview of these mecanismes

Biodegradables composites : prepration and characterization

This study focuses on the polystyrene matrix composites and micro loads of vegetable origin: spruce sawdust and celelulose microcrystal. The latter are obtained by extracting the cellulose from flour spruce. The composite samples were prepared by injection. The particle size analysis made it possible to determine the size of the charges and to highlight the effectiveness of treatment extraction. Analysis of microstructural changes was followed by Fourier transform inefrared spectroscopy and morphology by scanning electron microscopy. The mechanical behaviour and tensile strength were studied before and after hydrothermal agin

Fault-Tolerant Mechanism for Multimedia Transmission in Wireless Sensor Networks

International audienc