Grenoble Institute of Technology

About: Grenoble Institute of Technology is a education organization based out in Grenoble, France. It is known for research contribution in the topics: Hyperspectral imaging & Geology. The organization has 3427 authors who have published 5345 publications receiving 137158 citations. The organization is also known as: Grenoble INP.

Lattice stability and formation energies of intrinsic defects in Mg2Si and Mg2Ge via first principles simulations

Abstract: We report an ab initio study of the semiconducting Mg2X (with X = Si, Ge) compounds and in particular we analyze the formation energies of the different point defects with the aim of understanding the intrinsic doping mechanisms. We find that the formation energy of Mg2Ge is 50% larger than that of Mg2Si, in agreement with the experimental tendency. From a study of the stability and the electronic properties of the most stable defects, taking into account the growth conditions, we show that the main cause of the n doping in these materials comes from interstitial magnesium defects. Conversely, since other defects acting like acceptors such as Mg vacancies or multivacancies are more stable in Mg2Ge than in Mg2Si, this explains why Mg2Ge can be of n or p type, in contrast to Mg2Si. The finding that the most stable defects are different in Mg2Si and Mg2Ge and depend on the growth conditions is important and must be taken into account in the search for the optimal doping to improve the thermoelectric properties of these materials.

Quality of service and mobility for the wireless internet

Abstract: Our paper explores the issue of how to provide appropriate quality of Service mechanisms closely integrated with flexible mobility management in wireless local area networks. We consider them as access networks of choice for the high performance Wireless Mobile Internet. We present a hierarchical QoS architecture that extends Differentiated Services (DiffServ) to mobile hosts in a wireless environment. Our approach is based on controlling several parameters of a wiireless LAN cell: the limited geographicaL span to ensure the same high bit rate for all hosts, the constrained rate of traffic sources to limit the use of the channel in function of the required QoS and the limited number of active hosts to keep the load sufficiently low. The QoS management is coupled with mobility management at the IP level. We use a micro-mobility scheme implemented in the IPv6 layer with fast hand-offs between adjacent cells. Micro-mobility avoids address translation, traffic tunnelling, and enables fast hand-offs. We give some details of experiments to show the quality of service diffferentiation over the 802.11b network.

Impact of Plug-in Hybrid Electric Vehicles (PHEVs) on the French electric grid

Abstract: Currently the automotive sector is undergoing a major change. During the next years it is expected that there will be a considerable increase in the numbers of Plug-in Hybrid Electric Vehicles (PHEVs). Based on different charging scenarios, this paper investigates the impact of PHEVs on the French electric grid. Solutions are proposed to increase the maximum penetration rate. Hence we estimate that the French electric grid can accommodate 72% of PHEVs in 2015. This makes it possible to reduce oil imports for France by 22.5% and CO2 emissions due to road transport by 18%.