References of "Francis, Olivier 50001803"
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See detailContinuous gravimetric monitoring as an integrative tool for exploring hydrological processes in the Lomme Karst System (Belgium)
Watlet, A.; Van Camp, M. J.; Poulain, A. et al

Scientific Conference (2016)

Karst systems are highly heterogeneous which makes their hydrology difficult to understand. Geophysical techniques offer non-invasive and integrative methods that help interpreting such systems as a whole ... [more ▼]

Karst systems are highly heterogeneous which makes their hydrology difficult to understand. Geophysical techniques offer non-invasive and integrative methods that help interpreting such systems as a whole. Among these techniques, gravimetry has been increasingly used in the last decade to characterize the hydrological behavior of complex systems, e.g. karst environments or volcanoes. We present a continuous microgravimetric monitoring of 3 years in the karstic area of Rochefort (Belgium), that shows multiple occurrences of caves and karstic features. The gravity record includes measurements of a GWR superconducting gravimeter, a Micro-g LaCoste gPhone and an absolute FG5 gravimeter. Together with meteorological measurements and a surface/in-cave hydrogeological monitoring, we were able to improve the knowledge of hydrological processes. On the one hand, the data allowed identifying seasonal groundwater content changes in the unsaturated zone of the karst area, most likely to be linked to temporary groundwater storage occurring in the most karstified layers closed to the surface. Combined with additional geological information, modelling of the gravity signal based on the vertical potential of the gravitational attraction was then particularly useful to estimate the seasonal recharge leading to the temporary subsurface groundwater storage. On the other hand, the gravity monitoring of flash floods occurring in deeper layers after intense rainfall events informed on the effective porosity gradient of the limestones. Modelling was then helpful to identify the hydrogeological role played by the cave galleries with respect to the hosting limestones during flash floods. These results are also compared with measurements of an in-cave gravimetric monitoring performed with a gPhone spring gravimeter. An Electrical Resistivity Tomography monitoring is also conducted at site and brings additional information useful to verify the interpretation made with the gravimetric monitoring [less ▲]

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See detailGroundwater Storage in a Karst Vadose Zone Evidenced Using Gravimetric and Surface-to-borehole ERT Monitoring Systems
Watlet, A.; Kaufmann, O.; Francis, Olivier UL et al

Poster (2015, September 06)

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See detailBilateral comparison between the FG5X-216 and FG5-242
Francis, Olivier UL; Ullrich, Christian

Report (2015)

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See detailRelative gravity measurements in Ilulissat in July 2013
Francis, Olivier UL

Report (2015)

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See detailAnalysis of 4-year observations of the gPhone#59 in Tahiti
Francis, Olivier UL; Barriot, Jean-Pierre; Reymond, Dominique

in Marées Terrestres Bulletin d'Informations (2015), 149

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See detailCCM.G-K2 key comparison
Francis, Olivier UL; Baumann, Henri; Ullrich, Christian et al

in Metrologia (2015), 52(1A), 07009

In November 2013 an International Key Comparison, CCM.G-K2, was organized in the Underground Laboratory for Geodynamics in Walferdange. The comparison has assembled 25 participants coming from 19 ... [more ▼]

In November 2013 an International Key Comparison, CCM.G-K2, was organized in the Underground Laboratory for Geodynamics in Walferdange. The comparison has assembled 25 participants coming from 19 countries and four different continents. The comparison was divided into two parts: the key comparison that included 10 NMIs or DIs, and the pilot study including all participants. The global result given by the pilot study confirms that all instruments are absolutely coherent to each other. The results obtained for the key comparison confirm a good agreement between the NMI instruments. Main text. To reach the main text of this paper, click on Final Report [http://www.bipm.org/utils/common/pdf/final_reports/M/G-K2/CCM.G-K2.pdf] . Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/ [http://kcdb.bipm.org/] . The final report has been peer-reviewed and approved for publication by CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA). [less ▲]

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See detailHydrogeophysical Tools for Investigating Groundwater Storage in the Subsurface of a Karst System
Watlet, Arnaud; Van Noten, K.; Lecocq, T. et al

Poster (2014, September 14)

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See detailAbsolute gravity measurements at the Conrad Observatory by the University of Luxembourg
Francis, Olivier UL

Article for general public (2014)

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See detailAccurate Gravimetry at the BIPM Watt Balance Site
Jiang, Z.; Palinkas, V.; Francis, Olivier UL et al

in Rizos, C.; Willis, P. (Eds.) Earth on the Edge: Science for a Sustanaible Planet (2014)

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See detailThe quest for a consistent signal in ground and GRACE gravity time series
Van Camp, Michel; de Viron, Olivier; Métivier, Laurent et al

in Geophysical Journal International (2014), 197

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See detailMeasurement of the speed-of-light perturbation of free-fall absolute gravimeters
Rothleitner, Christian UL; Niebauer, Tim; Francis, Olivier UL

in Metrologia (2014), 51(3), 9

We report on a direct measurement of the relativistic Doppler shift with a commercial free-fall absolute gravimeter of the type FG5X. The observed Doppler shift, which is commonly called speed-of-light ... [more ▼]

We report on a direct measurement of the relativistic Doppler shift with a commercial free-fall absolute gravimeter of the type FG5X. The observed Doppler shift, which is commonly called speed-of-light perturbation, can be well described by the relativistic Doppler formula, where the constant object velocity is replaced by a time-dependent velocity with constant acceleration. The observed speed-of-light perturbation stands in contrast to other publications, which predict a higher frequency shift. It has been measured with a relative uncertainty of 1.1 × 10 −3 . [less ▲]

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See detailTidal gravity measurements in Southeast Asia revisited
Francis, Olivier UL; van Dam, Tonie UL

in Sun, Heping (Ed.) Progress on Geodesy and Geodynamics (2014)

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See detailHigh tilt susceptibility of the Scintrex CG-5 relative gravimeters
Reudink, R.; Klees, R.; Francis, Olivier UL et al

in Journal of Geodesy (2014), 88(6), 617-622

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See detailDétermination de l'accélération de la pesanteur pour la balance du watt du LNE
Merlet, Sébastien; Gillot, Pierre; Farah, Tristan et al

in Revue Française de Métrologie (2014), 36(2014-4), 11-27

The “watt balance” project aims at linking the kilogram definition to the Planck constant. The weighing of the mass involved requires a determination of the acceleration g with an uncertainty better than ... [more ▼]

The “watt balance” project aims at linking the kilogram definition to the Planck constant. The weighing of the mass involved requires a determination of the acceleration g with an uncertainty better than 10-8. This work aims at determining g with an atomic gravimeter and a dedicated gravimetric site. [less ▲]

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See detailReply to Comment on: ‘The quest for a consistent signal in ground and GRACE gravity time series’
Van Camp, Michel; de Viron, Olivier; Métivier, Laurent et al

in Geophysical Journal International (2014), 199(3), 1818-1822

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See detailFuture and development of the European Combined Geodetic Network ECGN
Poutanen, Markku; Ihdes, Johannes; Bruyninx, Carine et al

in Rizos, C.; Willis, Pascal (Eds.) Earth on the Edge: Science for a Sustanaible Planet (2014)

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See detailAccurate Determination of the Earth Tidal Parameters at the BIPM to Support the Watt Balance Project
Francis, Olivier UL; Rothleitner, Christian UL; Jiang, Z.

in Rizos, C.; Willis, P. (Eds.) Earth on the Edge: Science for a Sustanaible Planet (2014)

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See detailStability comparison of two absolute gravimeters: optical versus atomic interferometers
Gillot, P.; Francis, Olivier UL; Landragin, A. et al

in Metrologia (2014), 51(5), 15-17

We report the direct comparison between the stabilities of two mobile absolute gravimeters of different technology: the LNE-SYRTE Cold Atom Gravimeter (CAG) and FG5X#216 of the Université du Luxembourg ... [more ▼]

We report the direct comparison between the stabilities of two mobile absolute gravimeters of different technology: the LNE-SYRTE Cold Atom Gravimeter (CAG) and FG5X#216 of the Université du Luxembourg. These instruments rely on two different principles of operation: atomic and optical interferometry. The comparison took place in the Walferdange Underground Laboratory for Geodynamics in Luxembourg, at the beginning of the last International Comparison of Absolute Gravimeters, ICAG-2013. We analyse a 2h10 duration common measurement, and find that the CAG shows better immunity with respect to changes in the level of vibration noise, as well as a slightly better short term stability. [less ▲]

Detailed reference viewed: 93 (7 UL)