Éditeur(s) : HAL CCSD IGI Global
Résumé : International audience
Graph Theoretic Approaches for Analyzing Large-Scale Social Networks

hal-01637538
https://hal.archives-ouvertes.fr/hal-01637538

Éditeur(s) : HAL CCSD
Résumé : 6 pages, 4 figures. In ICML 2013 Workshop on Machine Learning for Bioacoustics
International audience
The work presented in this paper is part of a global framework which long term goal is to design a wireless sensor network able to support the observation of a population of endangered birds. We present the first stage for which we have conducted a knowledge discovery approach on a sample of acoustical data. We use MFCC features extracted from bird songs and we exploit two knowledge discovery techniques. One that relies on clustering-based approaches, that highlights the homogeneity in the songs of the species. The other, based on predictive modeling, that demonstrates the good performances of various machine learning techniques for the identification process. The knowledge elicited provides promising results to consider a widespread study and to elicit guidelines for designing a first version of the automatic approach for data collection based on acoustic sensors.
ICML 2013 Workshop on Machine Learning for Bioacoustics
Atlanta, United States

hal-00840741
https://hal.archives-ouvertes.fr/hal-00840741
ARXIV : 1306.5349

Éditeur(s) : HAL CCSD
Résumé : International audience
Human spatial motions determine geographic social contacts that influence the way an information is spread on a population or a community. As mobility is a transverse dimension to social practices it is important to better understand its role. With the Eternal-Return model we propose, we simulate an artificial world populated by heterogeneous agents who differ in their mobility. We have chosen a multi-agent framework perspective for this simulation. We endow the agents with simple rules on how to move around the space and how to establish proximity-contacts. This allows to distinguish different kinds of mobile agents, from sedentary ones to travelers. To summarize the dynamics induced by mobility over time, we define the mobility-based Social Proximity Network as being the network of all distinct contacts between agents. Its properties give insight in the process of information spreading. We conduct simulations to understand how an information can be broadcast when agent-nodes are in motion.
IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining
Niagara falls, Canada

hal-00874344
https://hal.archives-ouvertes.fr/hal-00874344

Éditeur(s) : HAL CCSD
Résumé : International audience
In this paper, we focus on the very specificity of rumors as pieces of information for modeling their process of propagation. We consider a population of pedestrians walking in a city and we assume that a rumor is transmitted by word of mouth from one to another. Although the diffusion of a rumor is of course a multi-dimensional process driven by sociological, economical and psychological elements, in this first step, we emphasize one main dimension of this complex phenomenon only. This dimension is the neighborhood of individuals likely to spread the information. With a confrontation of two antagonistic properties of the neighborhood that are profusion and scarcity of spreaders, we highlight specific characteristics of rumors. This study could lead to the psychological mechanism involved in the decision for a person to become or not a spreader himself/herself. In summary, we study if scarcity could be the silver bullet explaining how a rumor spreads.
ASONAM 2015 : IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining
Paris, France

hal-01252936
https://hal.archives-ouvertes.fr/hal-01252936
DOI : 10.1145/2808797.2809299

Éditeur(s) : HAL CCSD
Résumé : International audience
More and more animal species are endangered. In order to study and protect them, several measures have been taken, which now seem to show their limit. This work focuses on the counting process, a key issue for any project that aims to protect animals. Indeed, this paper proposes an algorithm for automatic counting of singing birds in their habitat by using wireless sensors fitted with microphone. Sensors are used to record audio samples of bird songs. These samples are used to extract some kinds of song fingerprint that are thereafter used to recognize the bird species, through a classification process. Afterwards, by analyzing data which have been collected by a central base, the network structure derived from detection fields of sensors, allows our algorithm to propose an estimate of singing birds in the habitat. This paper details the counting algorithm which uses graph theory and audio inputs comparison. Finally, we demonstrate our scheme efficiency through experimentations.
Local Computer Networks (LCN)
Clearwater, United States

hal-00786165
https://hal.archives-ouvertes.fr/hal-00786165
DOI : 10.1109/LCNW.2012.6424060

Éditeur(s) : HAL CCSD Springer
Résumé : International audience
The study of information dissemination in social networks is of particular importance in many areas as marketing, politics and security for example. Various strategies are being developed to disseminate information, those aimed at disseminating information widely and those aimed at disseminating information in a more confidential manner to make it scarce. In this paper, we adapt a model dedicated to spreading rumours by word of mouth in a physical space to the context of social networks. We compare two modes of dissemination based on profusion or scarcity and study the impact of the choice of the initial node. The results obtained show to what extent each mode exploits the social network topology and especially the influence of hubs.
International Conference on Complex Networks and Their Applications (COMPLEX NETWORK)
Lyon, France

hal-01637573
https://hal.archives-ouvertes.fr/hal-01637573

Éditeur(s) : HAL CCSD
Résumé : International audience
In real world situations, each person is generally in contact with only a small fraction of the entire population and exchange information through these interactions. Their number and their frequency vary from one to another individual and may be much depending on mobility of individuals. The objective of this article is to better understand how human mobility may have an impact on mobile social networking systems. This should help to answer a question as: "How might an information, a rumor, a pathogen, etc., driven by physical proximity, spread through a population?". We present a first stage of our work in which we focus on percolation processes as information flow mechanisms. We propose a synthetic mobility model and we define an artificial world populated by heterogeneous agents who differ in their mobility. Simulations are conducted on a multi-agent programmable environment. Our experimental results clearly demonstrate positive correlations between agent mobility factors and percolation thresholds.
Procedia CS

hal-00767043
https://hal.archives-ouvertes.fr/hal-00767043
DOI : 10.1016/j.procs.2012.06.007

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
High spatial and temporal variability of mesoscale moisture fields is still a challenge for quantitative precipitation forecast within numerical weather prediction (NWP) models especially over ocean regions where observations are lacking. This study presents the comparison between integrated water vapor over the Mediterranean Sea determined from shipborne GPS, the NWP ALADIN/Météo-France model and MODIS retrieval during a 4-month campaign (autumn 2008). While moisture prediction of the NWP remains accurate during most of the observation period, there are significant periods with offsets between GPS data and model predictions. We analyze such events and discuss the associated meteorological situation. Copyright © 2012 Royal Meteorological Society
ISSN: 1530-261X

hal-00757776
https://hal.archives-ouvertes.fr/hal-00757776
DOI : 10.1002/asl.391

Éditeur(s) : HAL CCSD
Résumé : International audience
The general context of this paper is the Bass model which presented a theory of the adoption of new products. We propose an agent based modelling to allow to model the respective grow of competing products. We assume that there is competition for the same market among two trademarks: each one has its own rate of spontaneous innovation and its own rate of imitation. This paper deals with the relative weight of these competing behaviors on the global dynamics; in particular, we ask the question of the equivalence between mass media influence and word-of-mouth effect.
IEEE RCIS 2014 Eighth International Conference on Research Challenges in Information Science
Marrakech, Morocco

hal-01288467
https://hal.archives-ouvertes.fr/hal-01288467
https://hal.archives-ouvertes.fr/hal-01288467/document
https://hal.archives-ouvertes.fr/hal-01288467/file/poster.pdf

Éditeur(s) : HAL CCSD
Résumé : International audience
More and more animal species are endangered every day on earth. In order to study their adaptation to world and climate change and their chances of survival, numerous initiatives have been taken that mostly need human intrusion into animal communities. Today mobile devices enable researchers to go beyond this limit. In this paper, we propose an original solution that consists on a new framework for detecting individual songs in a bird population and identifying remotely by this way their collective behavior in movements without human interaction. Movement patterns are elicited by analyzing data collected via wireless sensors fitted with microphone. Whereas similar methods use mobile devices fitted on some specimens, we rather propose fixed sensors. We demonstrate that this solution provides a good answer to technical constraints assessed by the context and we discuss results of experimental simulations that allow to define optimized parameters for the architecture to be set up on the ground. Experimental results are provided and show the relative impact of different parameters such as the number of sensors or the population size on the detection rate.
Proceedings of the 8th International Conference on Advances in Mobile Computing and Multimedia (MOMM 2010)

hal-00601641
https://hal.archives-ouvertes.fr/hal-00601641

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
We present the 1998-2009 GPS-derived velocity field for the Armenia region based on a survey-mode observation network of 31 GPS sites.We combine our results with previous GPS studies of the region to better assess the deformation of the Lesser Caucasus and Kura basin region. The results show that the Kura basin and the Lesser Caucasus regions are two different blocks, and that the main fault (Pambak-Sevan-Sunik) between these two regions has a right-lateral slip rate of 2±1 mm/yr. This is consistentwithmorphotectonic estimates and suggests a fairly constant slip rate over the last 120-300 ka. The right-lateral slip rate on one of the southern branch of the Pambak-Sevan-Sunik fault is lower than 1 mm/yr and the good agreementwith a geologically estimated slip rate suggests a constant slip rate over the last 1.4 Myr. The Sardarapat and Akhurian faults experience some shortening. This shortening is consistentwith someindependent geological estimates and shows the Arabian push.However, NNW-SSE-orientated faults have an extensional fault normal component instead of the expected shortening due to the Arabia-Eurasia convergence. This substantial extensive strain, and the sharp azimuth change of the velocity vectors between the Arabia promontory and the Lesser Caucasus suggest that processes other than "extrusion", possibly related to old subduction or delamination, contribute to the geodynamics of the region.
ISSN: 0040-1951

hal-00812623
https://hal.archives-ouvertes.fr/hal-00812623
DOI : 10.1016/j.tecto.2013.02.002

Éditeur(s) : HAL CCSD Geological Society of America
Résumé : International audience
We present the first recorded global positioning system (GPS) data from Myanmar measured at the northern tip of the Sagaing fault. This area is in a very complex geodynamic context, where rigid and semirigid plates interact. The 12 GPS sites measured in 2005 and 2008 in northern Myanmar show that the slip rate is 18 mm/yr and is localized along a single active narrow fault trace (<20 km wide). The same rate was previously demonstrated and remeasured, 500 km southward, in central Myanmar. Despite the geodynamic regional complexity induced by interaction between the Sunda and India plates, the Burma microplate, and the highly deformable eastern Himalayan syntaxis, the slip rate remains surprisingly constant along this fault. However, the modeled locking depth varies from 20 km in central Myanmar to 5 km in the north.
ISSN: 0091-7613

hal-00673712
https://hal.archives-ouvertes.fr/hal-00673712
DOI : 10.1130/G30872.1

Éditeur(s) : HAL CCSD Elsevier
Résumé : This paper is the first presentation of a project called GHYRAF (Gravity and Hydrology in Africa) devoted to the detailed comparison between models and multidisciplinary observations (ground and satellite gravity, geodesy, hydrology, meteorology) of the variations of water storage in Africa from the Sahara and part to the monsoon equatorial part. We describe the various actions planned in this project. We first detail the actions planned in gravimetry which consist in two main surface gravity experiments: on the one hand the periodic repetition of absolute gravity measurements along a north-south monsoonal gradient of rainfall in West Africa, going from Tamanrasset (20 mm/year) in southern Algeria to Djougou (1200 mm/year) in central Benin; on the other hand the continuous measurements at Djougou (Benin) with a superconducting gravimeter to monitor with a higher sampling rate the gravity changes related to an extreme hydrological cycle. Another section describes the actions planned in GPS which will maintain and develop the present-day existing network in West Africa. The third type of actions deals with hydrology and we review the three sites that will be investigated in this joint hydrogeophysics project namely Wankama (near Niamey) and Bagara (near Diffa) in the Niger Sahelian zone and Nalohou (near Djougou) in the Benin monsoon zone. We also address the question of the ground truth of satellite-derived missions: in this context the GHYRAF project will lead to test the hydrology models by comparison both with in situ and satellite data such as GRACE, as well as to an important increase of our knowledge of the seasonal water cycle in Africa. We finally present preliminary results in GPS based on the analysis of the vertical motion of the Djougou site. The resulting absolute gravity changes related to the 2008 monsoon are finally given.
ISSN: 0264-3707

hal-00475660
https://hal.archives-ouvertes.fr/hal-00475660
DOI : 10.1016/j.jog.2009.09.014

Éditeur(s) : HAL CCSD
Résumé : J'étais à l'époque dans le laboratoire I3S de Sophia-Antipolis. Je suis dorénavant au laboratoire GRIMAAG en Guadeloupe.
We focused on the communication problem within multi-agents systems, inspirited by nature and more precisely by the ants that are a perfect example of living integrating learning (ontogenesis) to genetic inheritance (phylogenesis): the Baldwin Effect.
We worked with agents represented by classifiers systems using genetic algorithm. We introduced a new fixed knowledge based classifiers system, the simplified Pittsburgh classifier system, which we studied in a spontaneous coordination multi-agents problem. Then, we successfully allowed “homogeneous” agents to communicate their “knowledge” using distributed elitism.
Finally, “heterogeneous” agents efficiently exchanged information thanks to a minimal communication model we defined, bound to reality and extended.
Nous nous sommes intéressés à la problématique de la communication au sein des systèmes multi-agents en nous inspirant de la nature et plus particulièrement des fourmis qui sont un parfait exemple de l'intégration de l'apprentissage du vivant (ontogenèse) au capital génétique de celui-ci (phylogénie) : l'effet Baldwin.
Nous avons choisi de travailler avec des systèmes de classeurs à algorithme génétique pour représenter les agents. Nous avons introduit un nouveau type de système de classeurs à base de connaissance de taille fixe, les systèmes de classeurs de type Pittsburgh simplifié, dont nous avons étudié les propriétés dans un contexte multi-agents de coordination spontanée.
Nous avons ensuite proposé avec succès aux agents "homogènes" de communiquer pour échanger leur "connaissance" à l'aide de l'élitisme distribué.
Enfin, les agents "hétérogènes" ont échangé efficacement des informations grâce à un modèle minimal de communication que nous avons ancré dans la réalité puis étendu.
https://tel.archives-ouvertes.fr/tel-00192372

tel-00192372
https://tel.archives-ouvertes.fr/tel-00192372
https://tel.archives-ouvertes.fr/tel-00192372/document
https://tel.archives-ouvertes.fr/tel-00192372/file/These.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
A dense, local network of 30 geodetic markers covering a 50 × 60 km2 area in the southwestern European Alps (Briançon region) has been temporarily surveyed in 1996, 2006 and 2011 by GPS. The aim is to measure the current deformation in this seismically active area. The study zone is characterized by a majority of extensional and dextral focal mechanisms, along north–south to N160 oriented faults. The combined analysis of the three measurement campaigns over 15 years and up to 16 years of permanent GPS data from the French RENAG network now enables to assess horizontal velocities below 1 mm/year within the local network. The long observation interval and the redundancy of the dense campaign network measurement help to constrain a significant local deformation pattern in the Briançon region, yielding an average E–W extension of 16 ± 11 nanostrain/year. We compare the geodetic deformation field to the seismic deformation rate cumulated over 37 years, and obtain good coherencies both in amplitude and direction. Moreover, the horizontal deformation localized in the Briançon region represents a major part of the Adriatic-European relative plate motion. However, the average uplift of the network in an extensional setting needs the presence of buoyancy forces in addition to plate tectonics.
ISSN: 0264-3707

hal-01119724
https://hal.archives-ouvertes.fr/hal-01119724
DOI : 10.1016/j.jog.2015.02.001

Éditeur(s) : HAL CCSD
Résumé : International audience
A key issue for any project that aims to study endangered animals is the counting process. In this work, we propose an algorithm for automatic counting of singing birds in their habitat by using wireless sensors fitted with microphone. Sensors are used to record audio samples of bird songs and samples are analyzed to extract fingerprints that permit to recognize bird species. This paper details the counting algorithm that uses graph theory and audio inputs comparison. Finally, we demonstrate our scheme efficiency through experimentations.
International Symposium on a World of Wireless, Mobile and Multimedia Networks
Lucca, Italy

hal-00618563
https://hal.archives-ouvertes.fr/hal-00618563
DOI : 10.1109/WoWMoM.2011.5986215

Éditeur(s) : HAL CCSD European Geosciences Union
Résumé : International audience
The Mediterranean hydrometeorological observatory Cévennes-Vivarais (OHM-CV) coordinates hydrometeorological observations (radars, rain gauges, water level stations) on a regional scale in southeastern France. In the framework of OHM-CV, temporary GPS measurements have been carried out for 2 months in autumn 2002, when the heaviest rainfall are expected. These measurements increase the spatial density of the existing permanent GPS network, by adding three more receivers between the Mediterranean coast and the Cévennes-Vivarais range to monitor maritime source of water vapour flow feeding the precipitating systems over the Cévennes-Vivarais region. In addition, a local network of 18 receivers covered an area of 30 by 30 km within the field of view of the meteorological radar. These regional and local networks of permanent and temporary stations are used to monitor the precipitable water vapour (PWV) with high temporal resolution (15 min). Also, the dense local network provided data which have been inverted using tomographic techniques to obtain the 3-D field of tropospheric water vapour content. This study presents methodological tests for retrieving GPS tropospheric observations from dense networks, with the aim of assessing the uncertainties of GPS retrievals. Using optimal tropospheric GPS retrieval methods, high resolution measurements of PWV on a local scale (a few kilometres) are discussed for rain events. Finally, the results of 3-D fields of water vapour densities from GPS tomography are analysed with respect to precipitation fields derived from a meteorological radar, showing a good correlation between precipitation and water vapour depletion areas.
ISSN: 1867-1381

hal-01022833
https://hal.archives-ouvertes.fr/hal-01022833
https://hal.archives-ouvertes.fr/hal-01022833/document
https://hal.archives-ouvertes.fr/hal-01022833/file/amt-7-553-2014.pdf
DOI : 10.5194/amt-7-553-2014

Éditeur(s) : HAL CCSD
Résumé : International audience
This paper investigates an application of wireless sensor networks to highlight existing communities within bird populations by collecting and analyzing behavioral and social data. We propose a solution based on fixed sensors fitted with microphone, a method more suited to the context of birds. This kind of sensor provides a good mean to enable the automatic detection of bird songs and thus to elicit social interactions between individuals by analyzing the occurrence and location of songs into given regions. The underlying sensor network architecture we propose allows each item to capture individual and collective patterns, by measuring the frequency of interactions among birds and between birds and regions. In this paper, we discuss our motivation to design a new architecture, and advantages and limitations of the proposed method. We demonstrate the efficiency of our solution by experimentations conducted by our simulation tool called Lypus.
IEEE 36th Conference on Local Computer Networks (LCN)
Bonn, Germany

hal-00656113
https://hal.archives-ouvertes.fr/hal-00656113
DOI : 10.1109/LCN.2011.6115565

Éditeur(s) : HAL CCSD Presses polytechniques et universitaires romandes, Publisher of the EPFL Press
Résumé : Chacun peut observer dans le monde réel l’omniprésence de systèmes complexes constitués de nombreux éléments en interaction et dont les caractéristiques globales ne peuvent se réduire à celles de leurs composants : ce sont par exemple les cellules d’un organisme vivant, les colonies de fourmis, les écosystèmes, ou encore les systèmes économiques, l’Internet et les réseaux sociaux. Dans le futur, nos sociétés devront relever l’immense défi scientifique et technologique qui consiste à comprendre ces systèmes pour les adapter, les contrôler et les modéliser. Au travers d’exemples choisis sans complication inutile, les auteurs proposent une introduction par la pratique aux systèmes complexes. Leur méthode repose sur la conviction que toute compréhension suppose un acte d’expérience; l’ouvrage est composé d’ateliers où il s’agit de simuler une dynamique collective à partir de sa modélisation orientée-agent. Les étudiants, les enseignants, les créateurs et plus largement toute personne avide de développer sa culture et d’actualiser ses connaissances tireront parti de cet ouvrage pluridisciplinaire accessible à un large public.
https://hal.archives-ouvertes.fr/hal-01284628

ISBN : 978-2-88074-991-0
hal-01284628
https://hal.archives-ouvertes.fr/hal-01284628

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
The impact of stratospheric ozone on the tropospheric general circulation of theSouthern Hemisphere (SH) is examined with a set of chemistry‐climate models participatingin the Stratospheric Processes and their Role in Climate (SPARC)/Chemistry‐ClimateModel Validation project phase 2 (CCMVal‐2). Model integrations of both the past andfuture climates reveal the crucial role of stratospheric ozone in driving SH circulationchange: stronger ozone depletion in late spring generally leads to greater polewarddisplacement and intensification of the tropospheric midlatitude jet, and greater expansion ofthe SH Hadley cell in the summer. These circulation changes are systematic as polewarddisplacement of the jet is typically accompanied by intensification of the jet and expansion ofthe Hadley cell. Overall results are compared with coupled models participating in theIntergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4), andpossible mechanisms are discussed. While the tropospheric circulation response appearsquasi‐linearly related to stratospheric ozone changes, the quantitative response to a givenforcing varies considerably from one model to another. This scatter partly results fromdifferences in model climatology. It is shown that poleward intensification of the westerly jetis generally stronger in models whose climatological jet is biased toward lower latitudes.This result is discussed in the context of quasi‐geostrophic zonal mean dynamics.
ISSN: 2169-897X

hal-00337060
https://hal.archives-ouvertes.fr/hal-00337060
https://hal.archives-ouvertes.fr/hal-00337060/document
https://hal.archives-ouvertes.fr/hal-00337060/file/Bock_et_al-2008-Journalsur Geophysical_Research__Solid_Earth_%281978-2012%29.pdf
DOI : 10.1029/2008JD010327