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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 ▲]

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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 ▲]

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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)

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See detailThe geophysical prospecting methods applied in engineering geology
Dassargues, Alain ULg

Scientific conference (1989, October)

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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)

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See detailGEOPHYSICAL SEARCHES FOR THREE NEUTRINO OSCILLATIONS
Cudell, Jean-René ULg; Gaisser, T. K.

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

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See detailGeophysical validation of MIPAS-ENVISAT operational ozone data
Cortesi, U.; Lambert, J. C.; De Clercq, C. et al

in Atmospheric Chemistry and Physics (2007), 7(18), 4807-4867

The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), on-board the European ENVIronmental SATellite (ENVISAT) launched on 1 March 2002, is a middle infrared Fourier Transform spectrometer ... [more ▼]

The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), on-board the European ENVIronmental SATellite (ENVISAT) launched on 1 March 2002, is a middle infrared Fourier Transform spectrometer measuring the atmospheric emission spectrum in limb sounding geometry. The instrument is capable to retrieve the vertical distribution of temperature and trace gases, aiming at the study of climate and atmospheric chemistry and dynamics, and at applications to data assimilation and weather forecasting. MIPAS operated in its standard observation mode for approximately two years, from July 2002 to March 2004, with scans performed at nominal spectral resolution of 0.025 cm(-1) and covering the altitude range from the mesosphere to the upper troposphere with relatively high vertical resolution (about 3 km in the stratosphere). Only reduced spectral resolution measurements have been performed subsequently. MIPAS data were re-processed by ESA using updated versions of the Instrument Processing Facility (IPF v4.61 and v4.62) and provided a complete set of level-2 operational products (geo-located vertical profiles of temperature and volume mixing ratio of H2O, O-3, HNO3, CH4, N2O and NO2) with quasi continuous and global coverage in the period of MIPAS full spectral resolution mission. In this paper, we report a detailed description of the validation of MIPAS-ENVISAT operational ozone data, that was based on the comparison between MIPAS v4.61 (and, to a lesser extent, v4.62) O-3 VMR profiles and a comprehensive set of correlative data, including observations from ozone sondes, ground-based lidar, FTIR and microwave radiometers, remote-sensing and in situ instruments on-board stratospheric aircraft and balloons, concurrent satellite sensors and ozone fields assimilated by the European Center for Medium-range Weather Forecasting. A coordinated effort was carried out, using common criteria for the selection of individual validation data sets, and similar methods for the comparisons. This enabled merging the individual results from a variety of independent reference measurements of proven quality (i.e. well characterized error budget) into an overall evaluation of MIPAS O-3 data quality, having both statistical strength and the widest spatial and temporal coverage. Collocated measurements from ozone sondes and ground-based lidar and microwave radiometers of the Network for the Detection Atmospheric Composition Change (NDACC) were selected to carry out comparisons with time series of MIPAS O-3 partial columns and to identify groups of stations and time periods with a uniform pattern of ozone differences, that were subsequently used for a vertically resolved statistical analysis. The results of the comparison are classified according to synoptic and regional systems and to altitude intervals, showing a generally good agreement within the comparison error bars in the upper and middle stratosphere. Significant differences emerge in the lower stratosphere and are only partly explained by the larger contributions of horizontal and vertical smoothing differences and of collocation errors to the total uncertainty. Further results obtained from a purely statistical analysis of the same data set from NDACC ground-based lidar stations, as well as from additional ozone soundings at middle latitudes and from NDACC ground-based FTIR measurements, confirm the validity of MIPAS O-3 profiles down to the lower stratosphere, with evidence of larger discrepancies at the lowest altitudes. The validation against O-3 VMR profiles using collocated observations performed by other satellite sensors (SAGE II, POAM III, ODIN-SMR, ACE-FTS, HALOE, GOME) and ECMWF assimilated ozone fields leads to consistent results, that are to a great extent compatible with those obtained from the comparison with ground-based measurements. Excellent agreement in the full vertical range of the comparison is shown with respect to collocated ozone data from stratospheric aircraft and balloon instruments, that was mostly obtained in very good spatial and temporal coincidence with MIPAS scans. This might suggest that the larger differences observed in the upper troposphere and lowermost stratosphere with respect to collocated ground-based and satellite O-3 data are only partly due to a degradation of MIPAS data quality. They should be rather largely ascribed to the natural variability of these altitude regions and to other components of the comparison errors. By combining the results of this large number of validation data sets we derived a general assessment of MIPAS v4.61 and v4.62 ozone data quality. A clear indication of the validity of MIPAS O-3 vertical profiles is obtained for most of the stratosphere, where the mean relative difference with the individual correlative data sets is always lower than +/- 10%. Furthermore, these differences always fall within the combined systematic error (from 1 hPa to 50 hPa) and the standard deviation is fully consistent with the random error of the comparison (from 1 hPa to similar to 30-40 hPa). A degradation in the quality of the agreement is generally observed in the lower stratosphere and upper troposphere, with biases up to 25% at 100 hPa and standard deviation of the global mean differences up to three times larger than the combined random error in the range 50-100 hPa. The larger differences observed at the bottom end of MIPAS retrieved profiles can be associated, as already noticed, to the effects of stronger atmospheric gradients in the UTLS that are perceived differently by the various measurement techniques. However, further components that may degrade the results of the comparison at lower altitudes can be identified as potentially including cloud contamination, which is likely not to have been fully filtered using the current settings of the MIPAS cloud detection algorithm, and in the linear approximation of the forward model that was used for the a priori estimate of systematic error components. The latter, when affecting systematic contributions with a random variability over the spatial and temporal scales of global averages, might result in an underestimation of the random error of the comparison and add up to other error sources, such as the possible underestimates of the p and T error propagation based on the assumption of a 1 K and 2% uncertainties, respectively, on MIPAS temperature and pressure retrievals. At pressure lower than 1 hPa, only a small fraction of the selected validation data set provides correlative ozone data of adequate quality and it is difficult to derive quantitative conclusions about the performance of MIPAS O-3 retrieval for the topmost layers. [less ▲]

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See detailGeophysical Validation of SCIAMACHY NO2 Vertical Columns: Overview of Early 2004 Results
Lambert, Jean-Christopher; Blumenstock, Thomas; Boersma, F. et al

in Proceedings of the Second Workshop on the Atmospheric Chemistry Validation of ENVISAT (ACVE-2), ESA-ESRIN, Frascati, Italy, 3-7 May 2004 (ESA SP-562, August 2004) ESC01JL1 (2004, August)

Following the recommendations drawn after the Commissioning Phase of the ENVISAT satellite in 2002, SCIAMACHY near real time data processors were upgraded to version 5.01 in early 2004. Before public ... [more ▼]

Following the recommendations drawn after the Commissioning Phase of the ENVISAT satellite in 2002, SCIAMACHY near real time data processors were upgraded to version 5.01 in early 2004. Before public release of the new SCIAMACHY nitrogen dioxide (NO2) vertical column data product, several validation teams investigated its improvement and assessed its geophysical consistency by means of correlative studies involving NDSC-affiliated ground-based networks of DOAS UV-visible and FTIR spectrometers and the ERS-2 GOME satellite. In parallel, preliminary SCIAMACHY NO2 column data products generated by research processors under development at scientific institutes were also tested, using the same correlative data and validation procedures. Digesting the results obtained by a list of validation teams and SCIAMACHY data processing teams, this overview paper draws a preliminary quality assessment of the SCIAMACHY NO2 column data sets available in spring 2004. [less ▲]

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See detailGéopolitique du Changement Climatique
Gemenne, François ULg

Book published by Armand Colin (2009)

LE CHANGEMENT CLIMATIQUE EST AUJOURD’HUI DEVENU UN SUJET DE POLITIQUE INTERNATIONALE dont les enjeux dépassent largement la seule question écologique pour englober l’ensemble des équilibres mondiaux, et ... [more ▼]

LE CHANGEMENT CLIMATIQUE EST AUJOURD’HUI DEVENU UN SUJET DE POLITIQUE INTERNATIONALE dont les enjeux dépassent largement la seule question écologique pour englober l’ensemble des équilibres mondiaux, et notamment des rapports Nord-Sud. Le présent ouvrage, solidement référencé et assorti d’une dizaine de cartes en couleurs, examine cette dimension géopolitique du réchauffement global. Quels sont les pays responsables ou réputés tels, quels sont ceux qui en subiront l’impact le plus fortement ? Quels sont les déplacements de populations engagés ou à prévoir ? Les risques pour la sécurité internationale ? L’auteur présente également les différents mécanismes de coopération internationale mis en place, et fait le point sur l’état actuel des négociations. Nous sommes en train d’entrer dans la phase véritablement critique, voire potentiellement dramatique de la question. Ce livre permet à chacun d’en comprendre les clés et les ressorts. [less ▲]

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See detailGeorges ADINS His Story and Series
Sacré, Robert ULg

Article for general public (1983)

Detailed reference viewed: 29 (3 ULg)
See detailGEORGES SIMENON - Comprendre et ne pas juger
Sacré, Robert ULg

in Télé Moustique (1983)

Detailed reference viewed: 81 (0 ULg)
See detailGEORGES ADINS - roadrunner van de Blues
Sacré, Robert ULg

in BLOCK (1984), (49), 17-23

Interview Georges Adins + Photos ( G. Adins)

Detailed reference viewed: 14 (1 ULg)
See detailGeorges Antoine : Lettres de la Grande-Guerre
Pirenne, Christophe ULg; Cagnati, Fabienne

Book published by Société liégeoise de Musicologie (2004)

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See detailGeorges Didi-Huberman
Hagelstein, Maud ULg

in Universalia 2012 (2012)

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See detailGeorges Didi-Huberman : une esthétique du symptôme
Hagelstein, Maud ULg

in Daimon : Revista de Filosofia (2005), 34

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See detailGeorges Didi-Huberman : vers une intentionnalité inversée ?
Hagelstein, Maud ULg

Scientific conference (2006, February 15)

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See detailGeorges Didi-Huberman. Une esthétique du symptôme
Hagelstein, Maud ULg

Master's dissertation (2003)

L’œuvre importante de Georges Didi-Huberman, qui débute en 1982 par une thèse pour l’EHESS sur l’Invention de l’hystérie, comprend aujourd’hui une vingtaine d’ouvrages. Cette œuvre, il est vrai très ... [more ▼]

L’œuvre importante de Georges Didi-Huberman, qui débute en 1982 par une thèse pour l’EHESS sur l’Invention de l’hystérie, comprend aujourd’hui une vingtaine d’ouvrages. Cette œuvre, il est vrai très récente, n’a pas encore été commentée. A Robert Maggiori, qui lui demandait s’il y a dans son travail un « fil directeur » lui permettant de traiter de sujets aussi apparemment hétéroclites que l’hystérie, Fra Angelico, les phasmes ou le minimalisme, Didi-Huberman répondit : « Il n’y a pas un fil. Ou alors, le fil est en pelote : chaque image pose un nœud de problèmes, chaque problème traverse une multitude d’images ». Il nous fallait pourtant aborder cette œuvre foisonnante à partir d’un thème conducteur, même « en pelote ». Nous avons choisi de traiter la question du symptôme dans les œuvres d’art, et d’interroger la possibilité de ce que Didi-Huberman appelle lui-même une « esthétique du symptôme ». Ainsi, les questions qui nous préoccuperont dans ce travail peuvent s’énoncer comme suit : Qu’est-ce que Didi-Huberman entend par « esthétique du symptôme » ? Quels sont les enjeux d’un tel projet ? Comment peut-il fonctionner ? [less ▲]

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See detailGeorges Didi-Huberman: vers une intentionnalité inversée ?
Hagelstein, Maud ULg

in La part de l'oeil (2006), 21-22

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See detailGeorges Ier d'Amboise (1460-1510). Une figure plurielle de la Renaissance
Dumont, Jonathan ULg; Fagnart, Laure ULg

Book published by Presses universitaires de Rennes (2013)

Archevêque de Rouen, cardinal, légat a latere, Georges Ier d’Amboise (1460–1510) est l’une des personnalités les plus fascinantes de la première Modernité européenne. Le prélat ne s’est toutefois pas ... [more ▼]

Archevêque de Rouen, cardinal, légat a latere, Georges Ier d’Amboise (1460–1510) est l’une des personnalités les plus fascinantes de la première Modernité européenne. Le prélat ne s’est toutefois pas contenté de cumuler les fonctions ecclésiastiques les plus prestigieuses. Pendant une dizaine d’années, en qualité de principal conseiller de Louis XII, il fut l’artisan de la politique royale, tant en France qu’à l’étranger. Son action concerne également les arts. Que ce soit en tant que bâtisseur et amateur averti d’architecture – comme en témoigne le château de Gaillon – ou que bibliophile et collectionneur, Georges Ier d’Amboise participe résolument à la diffusion des idées et des formes venues d’Italie. Les 2 et 3 décembre 2010 – à l’occasion du 500e anniversaire de la mort du cardinal –, un colloque international a été organisé à l’Université de Liège avec le soutien de "Transitions. Département de recherches sur le Moyen Âge tardif & la première Modernité". Les actes du colloque "Georges Ier d’Amboise (1460–1510). Une figure plurielle de la Renaissance", dirigés par Jonathan Dumont et Laure Fagnart, rassemblent la plupart des contributions présentées à ce colloque et se proposent, de la sorte, de traiter les aspects politiques, religieux et culturels de la vie du prélat, ambitionnant ainsi de faire le point sur l’état de nos connaissances, tout en dégageant de nouvelles pistes de recherches. [less ▲]

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See detailGeorges Kellens, de la tradition à l'innovation
Kefer, Fabienne ULg

in Kefer, Fabienne; Born, Michel; Lemaître, André (Eds.) Une criminologie de la tradition à l'innovation, En hommage à Georges Kellens (2006)

Detailed reference viewed: 43 (0 ULg)