Characterisation of the seismological pattern in a slowly deforming intraplate region: Central and western France

Tectonophysics, v. 409, n. 1-4, p. 175-192, 2005. http://dx.doi.org/10.1016/j.tecto.2005.08.021International audienc

A MIN-MAX PATH APPROACH FOR BALANCING ROBOTIC ASSEMBLY LINES WITH SEQUENCE-DEPENDENT SETUP TIMES

International audienceWe deal in this paper with SDRALBP-2, namely the Sequence-Dependent Robotic Assembly Line Balancing Problem of type 2. The problem is of industrial relevance due to the growing robotization of the assembly lines in the new Industry 4.0 era. Given a set of operations that are necessary to assembly a product and a set of robot types with different performances, the problem is concerned with addressing three decision problems simultaneously while minimizing a given objective. The first decision is to assign the operations to a given set of stations placed in a straight line [Balancing decision], the second decision is to sequence the operations in each station due the sequence-dependent setup times [Sequencing decision] and the third decision is to assign a robot to each station [Equipment selection decision]. We consider the objective of minimizing the cycle time, which is the maximum duration spent by a product in some station. We propose in this paper a method of type Sequence-First Balance-And-Select-Second. The proposed method embeds a dynamic programming algorithm (that solves a polynomial case) in a metaheuristic. Benchmark instances are used to evaluate the proposed method

Dimensionnement et pilotage d'une flotte d'AGVs dans un atelier flexible

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Building a natural-hazard-resilient high-quality seismic network: How WI network sustained hurricanes maria and irma

Between 2008 and 2014, the Institut de Physique du Globe de Paris (IPGP) and the University of the West Indies, Seismic Research Centre (UWI-SRC) designed and built a regional seismic network across the Lesser Antilles. One of the goals of the network is to provide real-time seismic data to the tsunami warning centers in the framework of the Intergovernmental Coordination Group working toward the establishment of a tsunami and other coastal hazards early warning system (ICG-CARIBE-EWS) for the Caribbean and adjacent regions (McNamara et al., 2016). In an area prone to hurricanes, earthquakes, tsunamis, and volcanic eruptions, we chose different techniques and technologies to ensure that our cooperated network could survive and keep providing data in case of major natural hazards. The Nanometrics very small aperture terminal (VSAT) technology is at the heart of the system. It allows for duplicated data collection at the three observatories (Trinidad, Martinique, and Guadeloupe; Anglade et al., 2015). In 2017, the network design and implementation were put to the test with Saffir-Simpson category 5 hurricanes Irma and Maria that went, respectively, through the north and central portion of the Lesser Antilles, mainly impacting the sites operated by volcanological and seismological observatories of IPGP in Martinique (Observatoire Volcanologique et Sismologique de Martinique [OVSM]) and in Guadeloupe (Observatoire Volcanologique et Sismologique de Guadeloupe [OVSG]). Our concepts proved to be valid with a major data shortage of less than 12 hr and only two stations having sustained heavy damage. In this article, we review the strengths and weaknesses of the initial design and discuss various steps that can be taken to enhance the ability of our cooperated network to provide timely real-time seismic data to tsunami warning centers under any circumstances

A multi-decadal view of the heat and mass budget of a volcano in unrest: La Soufrière de Guadeloupe (French West Indies)

Particularly in the presence of a hydrothermal system, many volcanoes output large quantities of heat through the transport of water from deep within the edifice to the surface. Thus, heat flux is a prime tool for evaluating volcanic activity and unrest. We review the volcanic unrest at La Soufrière de Guadeloupe (French West Indies) using an airborne thermal camera survey and in situ measurements of temperature and flow rate through temperature probes, Pitot-tube and MultiGAS measurements. We deduce mass and heat fluxes for the fumarolic, ground and thermal spring outputs and follow these over a period spanning 2000–2020. Our results are compared with published data and we performed a retrospective analysis of the temporal variations in heat flux over this period using the literature data. We find that the heat emitted by the volcano is 36.5 ± 7.9MW, of which the fumarolic heat flux is dominant at 28.3 ± 6.8 MW. Given a total heated area of 26 270 m2, this equates to a total heat flux density of 1366 ± 82 W/m2, which is amongst the highest established for worldwide volcanoes with hydrothermal systems, particularly for dome volcanoes. A major change at La Soufrière de Guadeloupe, however, is the development of a widespread region of ground heating at the summit where heat output has increased from 0.2 ± 1 MW in 2010 to 5.7 ± 0.9 MW in 2020. This change is concurrent with accelerating unrest at the volcano and the emergence of two new high-flux fumaroles in recent years. Our findings highlight the importance of continued and enhanced surveillance and research strategies at La Soufrière de Guadeloupe, the results of which can be used to better understand hydrothermal volcanic systems the world over

Les risques volcaniques au XXIe siècle : surveiller et prévoir ; l’exemple de l’OVSG

L’unrest volcanique est une déviation du niveaud’activité d’un volcan par rapport à son comportementde base, ce qui est préoccupant à court terme (quelquesheures à quelques mois), car il pourrait être le préluded’une éruption. L’unrest volcanique est un phénomènecomplexe comportant plusieurs aléas. Le fait que l’unrestpuisse conduire à une éruption imminente contribue àgénérer une incertitude importante pour l’évaluation, àcourt terme, des dangers de l’activité volcanique. Bienqu’il soit raisonnable de supposer que toutes les érup-tions sont associées à une activité précurseure, la connais-sance des liens de causalité entre les processus souter-rains, les signaux d’unrest qui en résultent et l’éruptionimminente est aujourd’hui encore insuffisante. Cela résul-te principalement des incertitudes liées à l’identificationdes processus causatifs de l’unrest et, par conséquent, dela prévision de leur évolution à court terme. Cependant,la clé pour une atténuation et une gestion efficace desrisques lors de l’unrest est l’identification précoce et fiabledes changements dans la dynamique souterraine d’unvolcan et de leur évaluation en tant que précurseurs d’uneéruption imminent

A seafloor experiment to monitor vertical deformation at the Lucky Strike volcano, Mid-Atlantic Ridge

International audienceDecades of cruise-based exploration have provided excellent snapshots of the structure of mid-ocean ridges and have revealed that accretion is a mixture of steady-state and quantum events. Observatory-type studies are now needed to quantify the temporal evolution of these systems. A multi-disciplinary seafloor observatory site is currently being set up at the Lucky Strike volcano, in the axial valley of the slow spreading Mid-Atlantic ridge as a part of the MoMAR (monitoring of the Mid-Atlantic Ridge) initiative. The aim of this observatory is to better understand the dynamics of the volcano and the hydrothermal vents hosted at its summit as well as their plumbing systems. In August 2006, the GRAVILUCK cruise initiated an experiment to monitor the deformation of Lucky Strike volcano. A geodetic network was installed, and seafloor pressure, gravity and magnetic data were collected. In this paper, we present the method used to monitor volcanic deformation, which involves measuring relative depth difference between points within a seafloor geodesy network. We show that, taking into account oceanographic variability and measurement noise, the network should be able to detect vertical deformations of the order of 1 cm