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See detailReconstruction of spatiotemporal capture data by means of orthogonal functions: the case of skipjack tuna (Katsuwonus pelamis) in the Central-east Atlantic
Ganzedo, Unai; Erdaide, Oihane; Trujillo-Santana, Aaron et al

in Scientia Marina (2013), 77(4), 575-584

The information provided by the International Commission for the Conservation of Atlantic Tunas (ICCAT) about captures of skipjack tuna (Katsuwonus pelamis) in the Central-east Atlantic has a number of ... [more ▼]

The information provided by the International Commission for the Conservation of Atlantic Tunas (ICCAT) about captures of skipjack tuna (Katsuwonus pelamis) in the Central-east Atlantic has a number of limitations, such as gaps in the statistics for certain fleets or the level of spatiotemporal detail at which catches are reported. As a result, the quality of such data and their effectiveness for providing management advice is limited. In order to reconstruct missing spatial-temporal data of catches, the present study uses Data INterpolating Empirical Orthogonal Functions (DINEOF), a technique for missing data reconstruction applied here for first time to fisheries data. DINEOF is based on an Empirical Orthogonal Functions (EOF) decomposition performed with a Lanczos method. DINEOF was tested with different amounts of missing data, intentionally removing values from 3.4% to 95.2% of data loss, and then compared to the same data set with no missing data. These validation analyses show that DINEOF is a reliable methodological approach of data reconstruction for the purposes of fishery management advice, even when the amount of missing data is very high. [less ▲]

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See detailReconstruction of sub-wavelength fractures and physical properties of masonry media using full-waveform inversion of proximal penetrating radar
Patriarca, C.; Lambot, S.; Mahmoudzadeh, M. R. et al

in Journal of Applied Geophysics (2011), 74(1)

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See detailReconstruction of the 1979-2005 Greenland ice sheet surface mass balance using satellite data and the regional climate model MAR
Fettweis, Xavier ULg

Doctoral thesis (2006)

In order to improve our knowledge on the current state and variability of the Greenland ice sheet surface mass balance (SMB), a 27-year simulation (1979-2005) has been performed with the coupled ... [more ▼]

In order to improve our knowledge on the current state and variability of the Greenland ice sheet surface mass balance (SMB), a 27-year simulation (1979-2005) has been performed with the coupled atmosphere-snow regional model MAR. This simulation reveals an increase in the main factors of the SMB which are, on the one hand, the snowfall (+ 1.6 ± 1.8 km3 yr-1) in winter and on the other hand, the run-off (+ 4.2 ± 1.9 km3 yr-1) in summer. The net effect of these two competing factors leads to a SMB loss rate of – 2.7 ± 3.0 km3 yr-1, which has a significance of 87%. The melt extent derived from the passive microwave satellite data since 1979 also shows this trend. The melt water supply has increased because the Greenland ice sheet has been warming up by + 0.09 ± 0.04 °C yr-1 since 1979. This warming comes from a uniform increase of downward infra-red radiation which can not be explained by the natural variability. These changes result very likely from the global warming induced by human activities. As a result, it seems that: i) increased melting dominates over increased accumulation in a warming scenario, ii) the Greenland ice sheet has been significantly losing mass since the beginning of the 1980's by an increasing melt water run-off as well as by a probable increase of iceberg discharge into the ocean due to the "Zwally effect" (the melt water-induced ice sheet flow acceleration) and iii) the Greenland ice sheet is projected to continue to lose mass in the future. The Greenland ice sheet melting could have an effect on the stability of the thermohaline circulation (THC) and the global sea level rise. On the one hand, increases in the freshwater flux from the Greenland ice sheet (glacier discharge and run-off) could perturb the THC by reducing the density contrast driving it. On the other hand, the melting of the whole Greenland ice sheet would account for a global mean sea level rise of 7.4 m. [less ▲]

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See detailReconstruction of the 1979-2005 Greenland ice sheet surface mass balance using satellite data and the regional climate model MAR
Fettweis, Xavier ULg

Conference (2007, April 17)

In order to improve our knowledge on the current state and variability of the Greenland ice sheet surface mass balance (SMB), a 27-year simulation (1979-2005) has been performed with the coupled ... [more ▼]

In order to improve our knowledge on the current state and variability of the Greenland ice sheet surface mass balance (SMB), a 27-year simulation (1979-2005) has been performed with the coupled atmosphere-snow regional model MAR. This simulation reveals an increase in the main factors of the SMB which are, on the one hand, the snowfall (+ 1.0 ± 1.5 km^3 yr^-2, not significant) in winter and on the other hand, the run-off of the melt water (+ 5.3 ± 3.0 km^3 yr^-2, significant) in summer. The net effect of these two competing factors leads to a SMB loss rate of – 4.1 ± 4.1 km^3 yr^-2, which has a significance of 95%. The melt extent derived from the passive microwave satellite data since 1979 also shows the acceleration of the surface melt. The contribution of changes in the net water vapour fluxes to the SMB variability is negligible. The melt water supply has increased because the Greenland ice sheet has been warming up by + 0.08 ± 0.04 °C yr^-1 since 1979. Latent heat flux, sensible heat flux and net solar radiation have not varied significantly over the last three decades. However, the simulated summer downward infra-red flux has increased by 7.1 W m^-2 since 1979. The natural climate variability (e.g. the North Atlantic Oscillation) does not fully explain these changes on the Greenland ice sheet. These changes result very likely from the global warming induced by human activities. The increase of +137 km^3 in the melt water run-off in the period 1979-2005 suggests that the overall ice sheet mass balance has been increasingly negative, given the observed melt-induced outlet glacier acceleration. [less ▲]

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See detailReconstruction of the 1979–2006 Greenland ice sheet surface mass balance using the regional climate model MAR
Fettweis, Xavier ULg

in The Cryosphere [=TC] (2007), 1

Results from a 28-year simulation (1979–2006) over the Greenland ice sheet (GrIS) reveal an increase of solid precipitation (+0.4±2.5 km3 yr−2) and run-off (+7.9±3.3 km3 yr−2) of surface meltwater. The ... [more ▼]

Results from a 28-year simulation (1979–2006) over the Greenland ice sheet (GrIS) reveal an increase of solid precipitation (+0.4±2.5 km3 yr−2) and run-off (+7.9±3.3 km3 yr−2) of surface meltwater. The net effect of these competing factors is a significant Surface Mass Balance (SMB) loss of −7.2±5.1 km3 yr−2. The contribution of changes in the net water vapour flux (+0.02±0.09 km3 yr−2) and rainfall (+0.2±0.2 km3 yr−2) to the SMB variability is negligible. The meltwater supply has increased because the GrIS surface has been warming up +2.4°C since 1979. Sensible heat flux, latent heat flux and net solar radiation have not varied significantly over the last three decades. However, the simulated downward infrared flux has increased by 9.3 W m−2 since 1979. The natural climate variability (e.g. the North Atlantic Oscillation) does not explain these changes. The recent global warming, due to the greenhouse gas concentration increase induced by human activities, could be a cause of these changes. The doubling of surface meltwater flux into the ocean over the period 1979–2006 suggests that the overall ice sheet mass balance has been increasingly negative, given the likely meltwater-induced acceleration of outlet glaciers. This study suggests that increased melting overshadows over an increased accumulation in a warming scenario and that the GrIS is likely to keep losing mass in the future. An enduring GrIS melting will probably affect in the future an certain effect on the stability of the thermohaline circulation and the global sea level rise. [less ▲]

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See detailReconstruction of the long-term satellite-derived sea surface temperature in the South China Sea
Huynh, Thi Hong Ngu ULg; Alvera Azcarate, Aïda ULg; Barth, Alexander ULg et al

Poster (2012, February 24)

The AVHRR (Advanced Very High Resolution Radiometer) sea surface temperature is very useful for researches in oceanography because of its high resolution. An AVHRR limitation is the high missing data ... [more ▼]

The AVHRR (Advanced Very High Resolution Radiometer) sea surface temperature is very useful for researches in oceanography because of its high resolution. An AVHRR limitation is the high missing data percentage due to cloud coverage. In the South China Sea, the average missing data is usually more than 80%, especially more than 95% in the region near the Borneo Island. In this study, we use DINEOF tool to reconstruct a daily night-time AVHRR data set with horizontal resolution of 4km spanning from 1989 to 2009. Besides, a comparison between the results and in situ data is shown. The EOF analysis shows that the first three modes explain about 95% of seasonal variability. [less ▲]

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See detailReconstruction of Total Suspended Matter data over the North Sea using DINEOF: use of the Gaussian anamorphosis transformation
Alvera Azcarate, Aïda ULg; Neukermans, Griet; Barth, Alexander ULg et al

Conference (2012, May 10)

Total Suspended Matter (TSM) from the SEVIRI sensor in the North Sea will be analysed using DINEOF (Data INterpolating Empirical Orthogonal Functions), an EOFbased technique to reconstruct missing data ... [more ▼]

Total Suspended Matter (TSM) from the SEVIRI sensor in the North Sea will be analysed using DINEOF (Data INterpolating Empirical Orthogonal Functions), an EOFbased technique to reconstruct missing data. The information needed to reconstruct the missing data is computed internally based on a truncated EOF basis, so no assumptions about the statistics of the data have to be made. DINEOF uses the mean and covariance of the original data to calculate the EOF basis. If the data are normally distributed, then the probability density distribution can be completely described by their mean and the eigenvectors of the covariance matrix (the EOFs). Variables such as TSM, however, do not have a Gaussian distribution, since TSM is never smaller than zero. DINEOF typically does not take this into account. To overcome this, a logarithmic transformation is usually performed to non-Gaussian variables, although the exponential transformation needed to retrieve the original variable units after using DINEOF leads sometimes to unrealistic high values in the reconstruction. An empirical transformation, which allows to obtain a normally distributed variable based solely on the data themselves, will be applied. This procedure, called Gaussian anamorphosis, is sometimes used in data assimilation. A Gaussian anamorphosis transformation will be applied to the TSM data of the North Sea prior to their reconstruction. The high spatial and temporal dynamics of the gapfree geostationary TSM data set will be analysed, focusing on tidal dynamics and sub-daily variability. [less ▲]

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See detailReconstruction OSEM de tomoscintigraphies acquises avec un collimateur sténopé et une trajectoire non-circulaire.
Seret, Alain ULg; Flérès, David; Defrise, Michel

in Médecine Nucléaire : Imagerie Fonctionnelle et Métabolique (2003), 27

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See detailReconstruire la nature. Le cas de la nouvelle frayère de Lanaye.
Keulen, Christine; Loneux, Michèle ULg; Poncin, Pascal ULg et al

Book published by J.C. Ruwet - Les Cahiers d'Ethologie appliquée (1996)

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See detailReconstruire la ville sur la ville
Halleux, Jean-Marie ULg; Lambotte, Jean-Marc ULg

Conference given outside the academic context (2006)

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See detailReconstruire la ville sur la ville
Ozer, Pierre ULg

Article for general public (2009)

Nous vivons une époque formidable ! Notre planète, cernée par des centaines de satellites d’observation de la Terre, est sous monitoring constant. Le développement extraordinaire des technologies de ... [more ▼]

Nous vivons une époque formidable ! Notre planète, cernée par des centaines de satellites d’observation de la Terre, est sous monitoring constant. Le développement extraordinaire des technologies de traitement de l’information nous permet de suivre, en direct, l’évolution de l’état de santé de l’environnement de notre village planétaire. Et, dans le domaine des constats, il n’y a plus de place au doute. Ainsi, nous savons que la biodiversité disparaît ici et ailleurs. Nous savons que les forêts, essentiellement dans les pays en développement, se contractent inexorablement. Nous savons que le réchauffement du système climatique est sans équivoque et que son origine anthropique est établie. Nous savons aussi qu’il va fragiliser nos économies en impactant les ressources en eau, les écosystèmes, les zones littorales, la souveraineté alimentaire de larges régions, la santé publique, et les plus vulnérables d’entre nous en accroissant les inégalités sociales ici et ailleurs (réfugiés climatiques) en fonction du degré d’adaptation à ces nouvelles contraintes inéluctables. [...] [less ▲]

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See detailReconstruire la ville sur la ville - Recyclage des espaces dégradés
De Keersmaecker, M.-L.; Gérard, S.; Harou, R. et al

Report (2005)

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See detailReconstruire la ville sur la ville - Recyclage des espaces dégradés
Govaerts, P.; Timmermans, A.; Vanloqueren, T. et al

Report (2003)

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See detailReconstruire la ville sur la ville - Recyclage des espaces dégradés
De Keersmaecker, M.-L.; Govaerts, P.; Gérard, S. et al

Report (2004)

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See detailReconstruire la ville sur la ville - Recyclage des espaces dégradés
Govearts, Pierre; Timmermans, Anne; Vanloquerena, Tanguy et al

Report (2003)

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See detailReconstruire la ville sur la ville - Recyclage des espaces dégradés
De Keersmaecker, M.-L.; Barthe-Bastalle, Hélène; Gérard, Sabine et al

Report (2004)

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See detailReconstruire la ville sur la ville - Recyclage des espaces dégradés
De Keersmaecker, M.-L.; Denef, Julie; Harou, Raphaëlle et al

Report (2005)

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See detailReconstruire la ville sur la ville - Recyclage des espaces dégradés. Etat d'avancement
De Keermaecker, M.-L.; Gérard, S.; Harou, R. et al

Report (2005)

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See detailReconstruire la ville sur la ville. Le recyclage et le renouvellement des espaces dégradés
Halleux, Jean-Marie ULg; Lambotte, Jean-Marc ULg

in Territoire(s) Wallon(s) (2008), (2), 7-22

L’article porte sur les mécanismes immobiliers qui favorisent le déclin des villes wallonnes et entravent leur recyclage morphologique. Les recherches qui y sont synthétisées portent tant sur l’action des ... [more ▼]

L’article porte sur les mécanismes immobiliers qui favorisent le déclin des villes wallonnes et entravent leur recyclage morphologique. Les recherches qui y sont synthétisées portent tant sur l’action des particuliers en matière de réhabilitation et de marché locatif que sur les stratégies des promoteurs immobiliers. Ces stratégies sont appréhendées à travers le sujet des blocages du recyclage, c’est-à-dire les différentes raisons qui poussent les opérateurs immobiliers à orienter leurs investissements vers les périphéries plutôt que vers les tissus urbains. L’article porte également sur une analyse évaluée de mesures visant à soutenir le recyclage des villes wallonnes. Trois sujets y sont particulièrement développés : les aides aux particuliers en vue de réhabiliter le parc locatif, les dispositifs de partenariat susceptibles d’orienter les promoteurs vers le milieu urbain et, enfin, les modalités susceptibles de mieux inscrire l’action publique dans une stratégie à long terme de renouvellement urbain. [less ▲]

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