1,143 research outputs found
Simulation Platform for Wireless Sensor Networks Based on Impulse Radio Ultra Wide Band
Impulse Radio Ultra Wide Band (IR-UWB) is a promising technology to address
Wireless Sensor Network (WSN) constraints. However, existing network simulation
tools do not provide a complete WSN simulation architecture, with the IR-UWB
specificities at the PHYsical (PHY) and the Medium Access Control (MAC) layers.
In this paper, we propose a WSN simulation architecture based on the IR-UWB
technique. At the PHY layer, we take into account the pulse collision by
dealing with the pulse propagation delay. We also modelled MAC protocols
specific to IRUWB, for WSN applications. To completely fit the WSN simulation
requirements, we propose a generic and reusable sensor and sensing channel
model. Most of the WSN application performances can be evaluated thanks to the
proposed simulation architecture. The proposed models are implemented on a
scalable and well known network simulator: Global Mobile Information System
Simulator (GloMoSim). However, they can be reused for all other packet based
simulation platforms
Medium Access Control for Wireless Sensor Networks based on Impulse Radio Ultra Wideband
This paper describes a detailed performance evaluation of distributed Medium
Access Control (MAC) protocols for Wireless Sensor Networks based on Impulse
Radio Ultra Wideband (IR-UWB) Physical layer (PHY). Two main classes of Medium
Access Control protocol have been considered: Slotted and UnSlotted with
reliability. The reliability is based on Automatic Repeat ReQuest (ARQ). The
performance evaluation is performed using a complete Wireless Sensor Networks
(WSN) simulator built on the Global Mobile Information System Simulator
(GloMoSim). The optimal operating parameters are first discussed for IR-UWB in
terms of slot size, retransmission delay and the number of retransmission, then
a comparison between IR-UWB and other transmission techniques in terms of
reliability latency and power efficiency
George Sand et le Théâtre de Nohant
C'est dans sa propre demeure que Sand monte une salle de théâtre qui sert de lieu de formation pour ses deux enfants et ses amis intimes. Passionnée par l'histoire de la commedia dell'arte et par son évolution à son époque, l'auteur explore cette forme de théâtre en famille avec un public réduit. Cet intérêt inspire ses écrits théoriques et son œuvre théâtrale ; en fait elle emploie la scène de Nohant comme lieu d'essai pour ses pièces jouées à Paris. On pourra constater que cette démarche permet à George Sand de sonder le succès de son œuvre théâtrale
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Depth dependence of westward-propagating North Atlantic features diagnosed from altimetry and a numerical 1/6° model
International audienceA 1/6° numerical simulation is used to investigate the vertical structure of westward propagation between 1993 and 2000 in the North Atlantic ocean. The realism of the simulated westward propagating signals, interpreted principally as the signature of first-mode baroclinic Rossby waves (RW), is first assessed by comparing the simulated amplitude and zonal phase speeds of Sea Level Anomalies (SLA) against TOPEX/Poseidon-ERS satellite altimeter data. Then, the (unobserved) subsurface signature of RW phase speeds is investigated from model outputs by means of the Radon Transform which was specifically adapted to focus on first-mode baroclinic RW. The analysis is performed on observed and simulated SLA and along 9 simulated isopycnal displacements spanning the 0-3250 m depth range. Simulated RW phase speeds agree well with their observed counterparts at the surface, although with a slight slow bias. Below the surface, the simulated phase speeds exhibit a systematic deceleration with increasing depth, by a factor that appears to vary geographically. Thus, while the reduction factor is about 15-18% on average at 3250 m over the region considered, it appears to be much weaker (about 5-8%) in the eddy-active Azores Current, where westward propagating structures might be more coherent in the vertical. In the context of linear theories, these results question the often-made normal mode assumption of many WKB-based theories that the phase speed is independent of depth. Alternatively, these results could also suggest that the vertical structure of westward propagating signals may significantly depend on their degree of nonlinearity, with the degree of vertical coherence possibly increasing with the degree of nonlinearity
The effects of window display construal on internal reactions and behavioral intentions
The objective of the study presented in this paper is to examine the effects of window-display construal on cognitive and affective responses as well as on behavioral intentions. A high-construal vs. low-construal design was carried out in a laboratory experiment over the period of one month. The findings suggest positive effects of construal level on behavioral intentions and negative mediation effects of cognition on subsequent responses
Does crisis affect credit risk in developing countries? The case of the Jordanian market
At the core of the recent global financial and economic crisis marked by its magnitude, credit risk turned out to be a powerful catalyst. The objective of this paper is mainly to follow up on the evolution of credit risk on the Jordanian market during the recent economic and financial international crisis. Based on the linear discriminant Z-Score model and KMV structural model, we recognize the increase in credit risk during the crisis period. On the whole, the confrontation between models highlights the robust correlation between the accounting results of a company and its market value and therefore indicates the need to consider the macroeconomic context in an open economy for the evaluation of the risk of credit.
JEL codes: E551, G3, C
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