Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
See detailGeomorphology of streams and rivers
Bravard, J. P.; Petit, François ULg

in Encyclopedia of Inland Waters (2009)

Detailed reference viewed: 70 (18 ULg)
Full Text
Peer Reviewed
See detailLa géophilosophie de Deleuze et Guattari
Krtolica, Igor ULg

in Carbone, Mauro; Broggi, Paride; Turarbek, Laura (Eds.) La géophilosophie de Gilles Deleuze. Entre esthétiques et politiques (2012)

Dans cet article, nous avons ressaisi ce que nous estimons être l’enjeu final de l’œuvre deleuzienne : le rapport paradoxal que la philosophie entretient avec les formations sociales qui la conditionnent ... [more ▼]

Dans cet article, nous avons ressaisi ce que nous estimons être l’enjeu final de l’œuvre deleuzienne : le rapport paradoxal que la philosophie entretient avec les formations sociales qui la conditionnent historiquement. Ce rapport est paradoxal, car il est à la fois de dépendance et d’excès : de dépendance (précepte matérialiste), car la pensée philosophique suppose des conditions sociohistoriques particulières pour pouvoir apparaître et s’épanouir (ainsi, les rapports d’association et de rivalité dans la cité grecque ou les rapports capitalistes dans l’Europe moderne) ; d’excès cependant (précepte spiritualiste), car la pensée philosophique n’est pas le reflet des conditions matérielles et idéologiques qui constituent le milieu favorable à son exercice, mais déborde les limites imposées par ce milieu social (l’histoire de la philosophie n’est pas une histoire des mentalités). Nous croyons que Deleuze et Guattari fournissent ainsi dans Qu’est-ce que la philosophie ? la raison du rapport essentiellement conflictuel que le philosophe entretient, au moins virtuellement, à la cité ou à l’État qui l’accueille, aux membres qui les peuplent et aux opinions qui leur correspondent (comme l’avaient montré en leur temps Platon dans l’Apologie de Socrate, Spinoza dans le chapitre XX du Traité théologico-politique, Nietzsche dans la Troisième considération inactuelle, ou encore Foucault dans ses derniers cours au Collège de France). Nous montrons que c’est du point de vue de ce rapport de dépendance et d’excès, suivant lequel la pensée philosophique naît et se nourrit de la société des amis (grecque ou capitaliste) pour viser des fins qui la dépassent, que l’on doit considérer la puissance politique de la philosophie dans l’histoire. Dans cet article, nous avons ainsi proposé une première esquisse de ce qui constitue l’horizon général de notre projet de recherche sur Deleuze : la convergence, à la fin des années 1980, du questionnement sur la nature de la pensée philosophique entamé dans les années 1950-1960 et de la philosophie politique élaborée avec Guattari dans les années 1970. [less ▲]

Detailed reference viewed: 44 (1 ULg)
Peer Reviewed
See detailGeophysical characterisation of a former waste disposal site in the context of landfill mining
Dumont, Gaël ULg; Robert, Tanguy ULg; Pilawski, Tamara et al

in EarthDoc - Near Surface Geoscience 2013 – 19th European Meeting of Environmental and Engineering Geophysics (2013, September 11)

Detailed reference viewed: 53 (19 ULg)
Full Text
See detailGeophysical identification, characterization, and monitoring of preferential groundwater flow paths in fractured media
Robert, Tanguy ULg

Doctoral thesis (2012)

This thesis investigates fractured zones leading to preferential groundwater flow paths. In this context, we used the electrical resistivity tomography (ERT) and the self-potential (SP) methods to ... [more ▼]

This thesis investigates fractured zones leading to preferential groundwater flow paths. In this context, we used the electrical resistivity tomography (ERT) and the self-potential (SP) methods to identify, characterize, monitor, and finally model preferential flow in hydraulically-active fractured zones at a scale representative of real world applications. From an experimental point of view, we first identified the magnitude of self-potential signature, a -15 mV anomaly that could be associated with preferential groundwater flow in a shallow quartzite aquitard whereas the streaming potential theory was originally developed for porous media. This signature was confirmed experimentally in limestone aquifers at greater depths. The joint use of surface ERT and SP allowed the identification of water-bearing fractured areas which were electrically more conductive, presenting contrasts from 1 to 10 and which were hydraulically-active presenting negative SP anomalies ranging from -10 to -30 mV. We were also able to correlate hydraulic heads and SP gradients during a low and a high groundwater level period leading to interesting perspectives in understanding the dynamics of complex groundwater flow systems. Finally, a preferential flow and rapid transport path, over 10 m/h, was highlighted in a 20 m deep fractured and karstified limestone valley by monitoring a salt tracer test with only surface ERT. This methodology was being mostly used for relatively shallow and homogeneous aquifers up to now. Such information is crucial to set up new monitoring wells or to define the sampling rates of classic tracer test. From a methodological point of view, we quantitatively assessed the efficiency of blocky and minimum-gradient-support regularizations in electrical imaging to recover sharp interfaces on numerical benchmarks and with field data. The usefulness of resolution indicators such as the cumulative sensitivity matrix and the resolution matrix were also assessed in this context. We demonstrated that noise characterization is crucial in time-lapse inversion and may supplant the choice of the time-lapse inversion scheme, calling for a systematic analysis of reciprocal measurements (or a subset of them). We also showed that, when using data differences in an inversion scheme, the data error, as estimated by time-lapse reciprocal measurements, depends on the mean measured resistance. These error characterization studies should always be performed if one wants to avoid wrong interpretations about the hydrodynamics. We further showed that focused inversion techniques (blocky inversion, minimum-gradient-support) may offer great perspectives when recovering model changes in time-lapse inversion. Finally, ERT and SP were jointly used to conceptualize a physically-based and spatially distributed hydrogeological model, in particular to characterize the preferential flow paths. Predicted hydraulic heads and SP-derived hydraulic heads using the water table model showed a clear correlation, leading to perspectives in terms of hydrogeological model calibration. Further experiments are however needed to fully estimate the streaming potential apparent coupling coefficient, but the use of the full SP signals for hydrogeological model calibration is a clear perspective to this work. [less ▲]

Detailed reference viewed: 198 (53 ULg)
Full Text
Peer Reviewed
See detailGeophysical investigation and numerical modelling of unstable slopes: case-study of Kainama (Kyrgyzstan)
Danneels, Gaëlle ULg; Bourdeau, Céline ULg; Torgoev, I. et al

in Geophysical Journal International (2008), 175

The presence of massive Quaternary loess units at the eastern border of the Fergana Basin (Kyrgyzstan, Central Asia) makes this area particularly prone to the development of catastrophic loess earthflows ... [more ▼]

The presence of massive Quaternary loess units at the eastern border of the Fergana Basin (Kyrgyzstan, Central Asia) makes this area particularly prone to the development of catastrophic loess earthflows, causing damages and injuries almost every year. Efficient disaster management requires a good understanding of the main causes of these mass movements, that is, increased groundwater pressure and seismic shaking. This paper focuses on the Kainama earthflow, mainly composed of loess, which occurred in 2004 April. Its high velocity and the long run-out zone caused the destruction of 12 houses and the death of 33 people. In summer 2005, a field survey consisting of geophysical and seismological measurements was carried out along the adjacent slope. By combination and geostatistical analysis of these data, a reliable 3-D model of the geometry and properties of the subsurface layers, as shown in the first part of the paper, was created. The analysis of the seismological data allowed us to point out a correlation between the thickness of the loess cover and the measured resonance frequencies and associated amplification potential. The second part of this paper is focused on the study of the seismic response of the slope by numerical simulations, using a 2-D finite difference code named FLAC.Modelling of the seismic amplification potential along the slope confirmed the results obtained from the seismological survey—strong amplifications at the crest and bottom of the slope where there is a thick loess cover and almost no amplification in the middle part of the slope. Furthermore, dynamic slope stability analyses were conducted to assess the influence of local amplifications and increased groundwater pressures on the slope failure. The results of the dynamic modelling, although preliminary, show that a combination of seismic and hydrologic origin (pore pressure build-up during the seismic shaking) is the most probable scenario responsible for the 2004 failure. [less ▲]

Detailed reference viewed: 45 (3 ULg)
See detailGeophysical investigation of the Hockai Fault Zone, Eastern Belgium
Havenith, Hans-Balder ULg; Nguyen, Frédéric ULg; Halleux, Lucien ULg et al

in EGU General Assembly Conference Abstracts (2015)

In the frame of a regional project evaluating the geothermal potential of the Wallonian Region of Belgium, the Hockai Fault Zone has been identified as one of the most interesting targets. It is a ... [more ▼]

In the frame of a regional project evaluating the geothermal potential of the Wallonian Region of Belgium, the Hockai Fault Zone has been identified as one of the most interesting targets. It is a seismically active fault zone that hosted the largest historical earthquake in Northwestern Europe, the M6-6.5 Verviers event in 1692 as well as a swarm of small earthquakes that was recorded in 1989-90. On the surface, the presence of the fault zones is marked by a series of geomorphic features, such as several landslides near the borders in the northern part, repeated NW-SE oriented scarps all along the Eastern border (over a distance of 40 km), river diversions and captures with formation of paleo-valleys.... [less ▲]

Detailed reference viewed: 50 (5 ULg)
Full Text
See detailGeophysical Investigation of the Pb-Zn deposit of Lontzen, Belgium
Evrard, Maxime ULg

Conference (2016, March 22)

Detailed reference viewed: 8 (1 ULg)
Full Text
See detailGeophysical Investigation of the Pb-Zn deposit of Lontzen-Popplsberg, Belgium
Evrard, Maxime ULg

Conference (2015, August 26)

Detailed reference viewed: 40 (4 ULg)
Full Text
See detailGeophysical Investigation of the Pb-Zn deposit of Plombières, Belgium
Evrard, Maxime ULg; Pirard, Eric ULg; Nguyen, Frédéric ULg

in André-mayer, anne-Sylvie; Cathelineau, Michel; Muchez, Philippe (Eds.) et al Mineral resources in a sustainable worl, proceeding, volume 5 (2015, August)

Detailed reference viewed: 38 (6 ULg)
Full Text
Peer Reviewed
See detailGEOPHYSICAL INVESTIGATIONS OF SEISMICALLY INDUCED SURFACE EFFECTS: CASE STUDY OF A LANDSLIDE IN THE SUUSAMYR VALLEY, KYRGYZSTAN
Havenith, Hans-Balder ULg; Jongmans, D.; Abdrakhmatov, K. et al

in Surveys in Geophysics (2000), 21

In summer 1998, a geophysical survey including seismic profiles and electrical tomography has been carried out in the Suusamyr valley, Kyrgyzstan. The scope was to investigate surface effects induced by ... [more ▼]

In summer 1998, a geophysical survey including seismic profiles and electrical tomography has been carried out in the Suusamyr valley, Kyrgyzstan. The scope was to investigate surface effects induced by the Ms = 7.3 Suusamyr earthquake, the 19th of August, 1992. In this paper, special attention is paid to the case study of a debris slide triggered by the earthquake. Seismic data are analysed by P-wave refraction technique and by surface wave inversion. Electrical tomographic profiles are processed by 2D-inversion. Using geotechnical and geological information, P-velocity models and resistivity sections are interpreted in terms of geological materials, in order to build a geological 3D model. On the basis of the latter, we carried out static finite element computations as well as static and pseudo-static calculations with Janbu’s method. Newmark displacement was computed, considering or not the influence of the shallow soft deposits. The results are compared to the real displacement observed in the field and conclusions are drawn about the mechanism of the landslide. [less ▲]

Detailed reference viewed: 38 (2 ULg)
Full Text
Peer Reviewed
See detailGeophysical Methods for Monitoring Temperature Changes in Shallow Low Enthalpy Geothermal Systems
Hermans, Thomas ULg; Nguyen, Frédéric ULg; Robert, Tanguy et al

in Energies (2014), 7

Low enthalpy geothermal systems exploited with ground source heat pumps or groundwater heat pumps present many advantages within the context of sustainable energy use. Designing, monitoring and ... [more ▼]

Low enthalpy geothermal systems exploited with ground source heat pumps or groundwater heat pumps present many advantages within the context of sustainable energy use. Designing, monitoring and controlling such systems requires the measurement of spatially distributed temperature fields and the knowledge of the parameters governing groundwater flow (permeability and specific storage) and heat transport (thermal conductivity and volumetric thermal capacity). Such data are often scarce or not available. In recent years, the ability of electrical resistivity tomography (ERT), self-potential method (SP) and distributed temperature sensing (DTS) to monitor spatially and temporally temperature changes in the subsurface has been investigated. We review the recent advances in using these three methods for this type of shallow applications. A special focus is made regarding the petrophysical relationships and on underlying assumptions generally needed for a quantitative interpretation of these geophysical data. We show that those geophysical methods are mature to be used within the context of temperature monitoring and that a combination of them may be the best choice regarding control and validation issues. [less ▲]

Detailed reference viewed: 122 (32 ULg)
See detailGeophysical monitoring of a thermal response test
Daoudi, Moubarak; Hermans, Thomas ULg; Vandenbohede, Alexander et al

Conference (2011, October 20)

Geothermal energy systems efficiency relies on the quantification of the thermal properties of the ground. The estimation of those properties can be done by means of thermal response tests (TRT) or thanks ... [more ▼]

Geothermal energy systems efficiency relies on the quantification of the thermal properties of the ground. The estimation of those properties can be done by means of thermal response tests (TRT) or thanks to values found in literature tables; the first approach provides relatively limited information since the measures are done in boreholes and the values from general tables can present a lack of accuracy. Geophysical methods might be useful in order to yield additional information for thermal properties estimation on higher investigation scales. In this study, electrical resistivity tomography (ERT) is used to monitor the evolution of heated water injected into an unconfined aquifer. Both heat injection and storage were monitored during a total period of 17 days. The principal conclusion is that the use of ERT is efficient to monitor the progressive temperature increase and decrease in the aquifer due to the presence of the heated plume. The resistivity distributions calculated by inversion were compared with electromagnetic borehole measurements and were consistent in the case of the storage phase, whereas a higher gap remained between measured and calculated resistivities for the injection phase. A conversion of the calculated resistivities into temperature values enabled a validation with temperature logs for the storage phase, while the temperature deduced for the injection profiles were too low. Those differences are justified by the fact that different error models were used to proceed to the imaging of the heat injection and storage. This work demonstrates the ability of ERT to monitor geothermal experiment in shallow aquifer. Keywords: geothermal energy, electrical resistivity, electromagnetic method, heat transfer, inversion process, thermal response test. [less ▲]

Detailed reference viewed: 83 (6 ULg)
Peer Reviewed
See detailGeophysical Monitoring of Artificial Landslide Dam of Kambarata Hydro Power Plant-2 (Kyrgyzstan)
Torgoev, Isakbek; Havenith, Hans-Balder ULg; Torgoev, Almaz

in Landslide Science for a Safer Geoenvironment (2014, January 01)

Detailed reference viewed: 19 (0 ULg)
See detailThe geophysical prospecting methods applied in engineering geology
Dassargues, Alain ULg

Scientific conference (1989, October)

Detailed reference viewed: 20 (0 ULg)
See detailGeophysical records in recent (Cenozoic) and ancient (Devonian – Palaeozoic) carbonate mound systems.
Foubert, Aneleen; Da Silva, Anne-Christine ULg; De MolB, Ben et al

in Book of Abstracts - 18th ISC Congress (2010, October 28)

Detailed reference viewed: 15 (0 ULg)
Full Text
See detailGEOPHYSICAL SEARCHES FOR THREE NEUTRINO OSCILLATIONS
Cudell, Jean-René ULg; Gaisser, T. K.

in 19th Int. Cosmic Ray Conf. (1985)

Detailed reference viewed: 12 (6 ULg)