330 research outputs found

    VANET Coverage Analysis for GPS Augmentation Data in Rural Area

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    The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Enhanced position accuracy is key for modern navigation systems, location based services and applications based on Inter-Vehicle Communication (IVC). Position data are the foundation for deriving vehicle trajectories used for assessing a situation's criticality in vehicle safety. Thus, especially Advanced Driver Assistance Systems (ADASs) and integral safety applications bene t from nearby vehicles spreading their positions periodically with high accuracy. Positioning based on Global Navigation Satellite System (GNSS) measurements can be enhanced by established Cooperative Positioning (CP) methods like Real-Time Kinematic (RTK) and Di fferential GNSS (DGNSS). Conventional CP relies on positioning correction data from a third party, whereas this paper introduces a self-su fficient CP system based on Precise Point Positioning (PPP) and Vehicular Ad-Hoc Network (VANET) technology requiring no infrastructure. Furthermore, the data dissemination process and achievable coverage are analysed by a simulation study for a rural area in Bavaria, Germany. For this purpose, the simulation employs the European IVC protocol stack ITS-G5. While the general feasibility of this CP approach could be assured, some remaining issues regarding employed network protocols were discovered as well

    Pseudovector vs. pseudoscalar coupling in one-boson exchange NN potentials

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    We examine the effects of pseudoscalar and pseudovector coupling of the pi and eta mesons in one-boson exchange models of the NN interaction using two approaches: time-ordered perturbation theory unitarized with the relativistic Lippmann-Schwinger equation, and a reduced Bethe-Salpeter equation approach using the Thompson equation. Contact terms in the one-boson exchange amplitudes in time-ordered perturbation theory lead naturally to the introduction of s-channel nucleonic cutoffs for the interaction, which strongly suppresses the far off-shell behavior of the amplitudes in both approaches. Differences between the resulting NN predictions of the various models are found to be small, and particularly so when coupling constants of the other mesons are readjusted within reasonable limits.Comment: 24 pages, 4 figure

    Robustness assessment of the ‘cooperation under resource pressure’ (CURP) model: Insights on resource availability and sharing practices among hunter-gatherers

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    A well-known challenge in archaeological research is the exploration of the social mechanisms that hunter-gatherers may have implemented throughout history to deal with changes in resource availability. The agent-based model (ABM) ‘cooperation under resource pressure’ (CURP) was conceived to explore food stress episodes in societies lacking a food preservation technology. It was particularly aimed at understanding how cooperative behaviours in the form of food sharing practices emerge, increase and may become the prevailing strategy in relation to changes in resource availability and expectancy of reciprocity. CURP’s main outcome is the identification of three regimes of behaviour depending on the stress level. In this work, the model’s robustness to the original selection mechanism (random tournament) is assessed, as different dynamics can lead to different persistent regimes. For that purpose, three other selection mechanisms are implemented and evaluated, to identify the prevailing states of the system. Results show that the three regimes are robust irrespective of the analysed dynamics. We consequently examine in more detail the long-term archaeological implications that these results may have.Spanish Ministry of Economy and Competitiveness (former Ministry of Science and Innovation): SimulPast Project (CSD2010- 00034 CONSOLIDER-INGENIO 2010), HAR2009-06996 and CULM Project (HAR2016- 77672-P); from the Argentine National Scientific and Technical Research Council (CONICET): Project PIP-0706; from the Wenner-Gren Foundation for Anthropological Research: Project GR7846; from the project H2020 FET OPEN RIA IBSEN/662725 and from the European Social Fund as one of the authors is the recipient of a predoctoral grant from the Department of Education of Junta de Castilla y León (Spain)
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