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See detailTemporal Evolution of the High-energy Irradiation and Water Content of TRAPPIST-1 Exoplanets
Bourrier, V.; de Wit, J.; Bolmont, E. et al

in Astronomical Journal (The) (2017), 154

The ultracool dwarf star TRAPPIST-1 hosts seven Earth-size transiting planets, some of which could harbor liquid water on their surfaces. Ultraviolet observations are essential to measuring their high ... [more ▼]

The ultracool dwarf star TRAPPIST-1 hosts seven Earth-size transiting planets, some of which could harbor liquid water on their surfaces. Ultraviolet observations are essential to measuring their high-energy irradiation and searching for photodissociated water escaping from their putative atmospheres. Our new observations of the TRAPPIST-1 Lyα line during the transit of TRAPPIST-1c show an evolution of the star emission over three months, preventing us from assessing the presence of an extended hydrogen exosphere. Based on the current knowledge of the stellar irradiation, we investigated the likely history of water loss in the system. Planets b to d might still be in a runaway phase, and planets within the orbit of TRAPPIST-1g could have lost more than 20 Earth oceans after 8 Gyr of hydrodynamic escape. However, TRAPPIST-1e to h might have lost less than three Earth oceans if hydrodynamic escape stopped once they entered the habitable zone (HZ). We caution that these estimates remain limited by the large uncertainty on the planet masses. They likely represent upper limits on the actual water loss because our assumptions maximize the X-rays to ultraviolet-driven escape, while photodissociation in the upper atmospheres should be the limiting process. Late-stage outgassing could also have contributed significant amounts of water for the outer, more massive planets after they entered the HZ. While our results suggest that the outer planets are the best candidates to search for water with the JWST, they also highlight the need for theoretical studies and complementary observations in all wavelength domains to determine the nature of the TRAPPIST-1 planets and their potential habitability. [less ▲]

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See detailImproving pedestrian detection using motion-guided filtering
Wang, Yi; Pierard, Sébastien ULiege; Su, Song-Zhi et al

in Pattern Recognition Letters (2017), 96

In this letter, we show how a simple motion-guided nonlinear filter can drastically improve the accuracy of several pedestrian detectors. More specifically, we address the problem of how to pre-filter an ... [more ▼]

In this letter, we show how a simple motion-guided nonlinear filter can drastically improve the accuracy of several pedestrian detectors. More specifically, we address the problem of how to pre-filter an image so almost any pedestrian detector will see its false detection rate decrease. First, we roughly identify moving pixels by cumulating their temporal gradient into a motion history image (MHI). The MHI is then used in conjunction with a nonlinear filter to filter out background details while leaving untouched foreground moving objects. We also show how a feedback loop as well as a merging procedure between the filtered and the unfiltered frames can further improve results. We tested our method on 26 videos from 6 categories. The results show that for a given miss rate, filtering out background details reduces the false detection rate by a factor of up to 69.6 times. Our method is simple, computationally light, and can be implemented with any pedestrian detector. Code is made publicly available at: https://bitbucket.org/wany1601/pedestriandetection. [less ▲]

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See detailMAVEN IUVS Observations of the Aftermath of the Comet Siding Spring Meteor Shower on Mars
Schneider, N. M.; Crismani, M.; Deighan, J. I. et al

Conference (2017, September 01)

A comet's close passage by Mars deposited an unprecedented amount of vaporized dust whose elements were detected by the MAVEN spacecraft.

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See detailUnveiling Mars nightside mesosphere dynamics by IUVS/MAVEN global images of NO nightglow
Stiepen, Arnaud ULiege; Jain, S. K.; Schneider, N. M. et al

Conference (2017, September 01)

We analyze the morphology of the ultraviolet nightglow in the Martian upper atmosphere through Nitric Oxide (NO) δ and γ bands emissions observed by the Imaging Ultraviolet Spectrograph instrument on the ... [more ▼]

We analyze the morphology of the ultraviolet nightglow in the Martian upper atmosphere through Nitric Oxide (NO) δ and γ bands emissions observed by the Imaging Ultraviolet Spectrograph instrument on the Mars Atmosphere and Volatile EvolutioN spacecraft. The seasonal dynamics of the Martian thermosphere-mesosphere can be constrained based on the distribution of these emissions. We show evidence for local (emission streaks and splotches) and global (longitudinal and seasonal) variability in brightness of the emission and provide quantitative comparisons to GCM simulations. [less ▲]

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See detailFirst-principles study of tungsten trioxide: Structural properties and polaron formation
Hamdi, Hanen ULiege

Doctoral thesis (2017)

Using first-principles calculations, we analyze the structural properties of tungsten trioxide WO3. Our calculations rely on density functional theory and the use of the B1-WC hybrid functional, which ... [more ▼]

Using first-principles calculations, we analyze the structural properties of tungsten trioxide WO3. Our calculations rely on density functional theory and the use of the B1-WC hybrid functional, which provides very good agreement with experimental data. We show that the hypothetical high-symmetry cubic reference structure combines several ferroelectric and antiferrodistortive (antipolar cation motions, rotations and tilts of oxygen octahedra) structural instabilities. Although the ferroelectric instability is the largest, the instability related to antipolar W motions combines with those associated to oxygen rotations and tilts to produce the biggest energy reduction, yielding a P2_1/c ground state. This non-polar P2_1/c phase is only different from the experimentally reported Pc ground state by the absence of a very tiny additional ferroelectric distortion. The calculations performed on a stoichiometric compound so suggest that the low temperature phase of WO3 is not intrinsically ferroelectric and that the {experimentally observed} ferroelectric character might arise from extrinsic defects such as oxygen vacancies. Independently, we also identify never observed R3m and R3c ferroelectric metastable phases with large polarizations and low energies close to the P21/c ground state, which makes WO3 a potential antiferroelectric material. The relative stability of various phases is discussed in terms of the anharmonic couplings between different structural distortions, highlighting a very complex interplay. On the second hand, the addition of a single electron to the largest supercell of the monoclinic P21/c ground state of WO3 causes the development of a medium polaron inside of this material. We then study and characterize a medium polaron formation in WO3 from first-principles calculation. We show how the medium polaron in the supercell of WO3 can change its structural, electronic and dynamical properties. [less ▲]

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See detailPolitique de la fonction publique
Grandjean, Geoffrey ULiege

Learning material (2017)

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See detailStories from the lab, stories from the field
Vanderschuren, Hervé ULiege

Speech/Talk (2017)

NA

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See detailMunicipalities’ understanding and importance of the concept of Smart Cities: an exploratory analysis in Belgium
Desdemoustier, Jonathan ULiege; Crutzen, Nathalie ULiege; Giffinger, Rudolf

Conference (2017, September 01)

Even if an increasing number of scientific publications are dealing with it, the concept of “smart city” is not yet well defined and it is not fully understood (Anthopoulos and Vakali 2012; Caragliu,Bo ... [more ▼]

Even if an increasing number of scientific publications are dealing with it, the concept of “smart city” is not yet well defined and it is not fully understood (Anthopoulos and Vakali 2012; Caragliu,Bo, and Nijkamp 2009; Lazaroiu and Roscia 2012). Due to the lack of a proper conceptualization, defined method or credentials for smart cities (Angelidou 2015; Nam and Pardo 2011), cities across the geographical spectrum claim themselves 'smart' with self-congratulatory note (Hollands 2008). Despite this increasing popularity of smart cities, there are few critical discourse and rigorous analytical or statistical analyses of the concept and its application on urban territories (Caragliu, Bo, and Nijkamp 2009; R G Hollands 2015; Kitchin 2015; Vanolo 2014). This paper aims at understanding where Belgian municipalities stand in the field of smart city in 2016. How Belgian municipalities approach the phenomenon smart city? Which focus in smart city -sustainable, technologic, creative and human-do attract Belgian municipalities? The paper answers to these questions thanks to a comprehensive territorial analysis of the country, a presentation of current trends on smart cities in the three Belgian regions, and the construction of a typology of municipalities’ understandings of the phenomenon. It also analyses how these understandings impact priorities and smart city developments of Belgian municipalities. It investigates how they affect municipal priorities in the six dimensions of the smart city and their state of development in some key smart city fields. Finally, it examines how do this typology is related to the municipal perception of difficulty to set up smart city projects and the relevance of the concept for their territories. The data used comes from the results of a quantitative research amongst Belgian municipalities carried out in 2016 by the Smart City Institute. The research points out key statistical observations around the smart city phenomenon in Belgium. A typology with four different understandings (technological, holistic, specialized and inexistent) emerged from the analyses. [less ▲]

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See detailNew constraints on quasar broad absorption and emission line regions from gravitational microlensing
Hutsemekers, Damien ULiege; Braibant, Lorraine ULiege; Sluse, Dominique ULiege et al

in Frontiers in Astronomy and Space Sciences (2017), 4

Gravitational microlensing is a powerful tool allowing one to probe the structure of quasars on sub-parsec scale. We report recent results, focusing on the broad absorption and emission line regions. In ... [more ▼]

Gravitational microlensing is a powerful tool allowing one to probe the structure of quasars on sub-parsec scale. We report recent results, focusing on the broad absorption and emission line regions. In particular microlensing reveals the intrinsic absorption hidden in the P Cygni-type line profiles observed in the broad absorption line quasar H1413+117, as well as the existence of an extended continuum source. In addition, polarization microlensing provides constraints on the scattering region. In the quasar Q2237+030, microlensing differently distorts the Hα and CIV broad emission line profiles, indicating that the low- and high-ionization broad emission lines must originate from regions with distinct kinematical properties. We also present simulations of the effect of microlensing on line profiles considering simple but representative models of the broad emission line region. Comparison of observations to simulations allows us to conclude that the Hα emitting region in Q2237+030 is best represented by a Keplerian disk. [less ▲]

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See detailSex and gender in family business succession research: A review and forward agenda from a social construction perspective
Nelson, Teresa; Constantinidis, Christina ULiege

in Family Business Review (2017), 30(3), 219-241

This article focuses on how family business succession research has engaged and may be further enriched by application of a gender lens as socially constructed. We analyze the succession literature ... [more ▼]

This article focuses on how family business succession research has engaged and may be further enriched by application of a gender lens as socially constructed. We analyze the succession literature developing a gender terms vocabulary and five themes of historical engagement. Finding a lack of theoretical grounding, we apply the construct of gender, through expectation states theory, revising the Sharma and Irving model of successor commitment to examine how a socially constructed view of gender shifts and opens up points of view. We then present a forward looking agenda to motivate future scholarship. [less ▲]

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See detailLe service minimum à l'aune de la Convention européenne des droits de l'homme : interdiction, possibilité ou obligation pour le législateur belge?
Bouhon, Frédéric ULiege; Vandenbosch, Sofia ULiege

in Revue de Droit Social = Tijdschrift voor Sociaal Recht (2017), 3(2017), 585-612

The implementation of minimum service, which aims at guaranteeing continuity of some activities despite a strike, constitutes an interference with the right to strike. Considered under article 11 of the ... [more ▼]

The implementation of minimum service, which aims at guaranteeing continuity of some activities despite a strike, constitutes an interference with the right to strike. Considered under article 11 of the European Convention on Human Rights, this implementation appears to be, depending on the situation, either a legally forbidden measure, or an option open to the authorities or an adequate mean to fulfil a positive obligation. This legal context circumscribes the margin of appreciation of the Belgian legislator in this field. [less ▲]

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See detailPromoting "health literacy friendly" healthcare institutions
Henrard, Gilles ULiege

Poster (2017, September)

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See detailA two-step methodology for human pose estimation increasing the accuracy and reducing the amount of learning samples dramatically
Azrour, Samir ULiege; Pierard, Sébastien ULiege; Geurts, Pierre ULiege et al

in Advanced Concepts for Intelligent Vision Systems (2017, September)

In this paper, we present a two-step methodology to improve existing human pose estimation methods from a single depth image. Instead of learning the direct mapping from the depth image to the 3D pose, we ... [more ▼]

In this paper, we present a two-step methodology to improve existing human pose estimation methods from a single depth image. Instead of learning the direct mapping from the depth image to the 3D pose, we first estimate the orientation of the standing person seen by the camera and then use this information to dynamically select a pose estimation model suited for this particular orientation. We evaluated our method on a public dataset of realistic depth images with precise ground truth joints location. Our experiments show that our method decreases the error of a state-of-the-art pose estimation method by 30%, or reduces the size of the needed learning set by a factor larger than 10. [less ▲]

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See detailMethis (7): Agir dans la ville.
Hamers, Jérémy ULiege; Darcis, Damien ULiege

Book published by Editions de l’Université de Liège (2017)

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See detailSMART RIVERS 2017
Rigo, Philippe ULiege; MUSKATIROVIC, JASNA; JAIMURZINA, AZHAR et al

in SMART RIVERS 2017, Pittsburgh (PIANC) (2017, September)

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See detailModelle zur Untersuchung von Massenbewegungen und Hangstabilität in seismischen Regionen
Mreyen, Anne-Sophie ULiege; Anja, Dufresne; Havenith, Hans-Balder ULiege

in Fachsektionstage Geotechnik - Interdisziplinäres Forum (2017, September)

Zwei von Erdrutschen betroffene Regionen in NW- und Mitteleuropa werden mittels Hangstabilitätsanalysen in Form von 3D-Geo-Modellen und numerischer 2D-Modellierung untersucht: (1) die Hockai-Störungszone ... [more ▼]

Zwei von Erdrutschen betroffene Regionen in NW- und Mitteleuropa werden mittels Hangstabilitätsanalysen in Form von 3D-Geo-Modellen und numerischer 2D-Modellierung untersucht: (1) die Hockai-Störungszone (HFZ – Hockai Fault Zone) in Ostbelgien und (2) die seismische Region Vrancea in den rumänischen Karpaten. Die Untersuchungsgebiete unterscheiden sich hinsichtlich ihrer klimatischen und seismo-tektonischen Bedingungen, sind jedoch beide von tiefsitzenden Hangbewegungen entlang aktiver bzw. inaktiver Störungszonen betroffen. Obwohl es zurzeit keinerlei eindeutige Belege massiver co-seismischer Erdrutsche in NW Europa gibt, ist die seismisch aktive HFZ in Belgien (bekannt durch das M~6-6.3 Verviers Ereignis in 1692) durch größere Massenbewegungen mit wahrscheinlichem seismischen Ursprung gekennzeichnet. Die Region Vrancea in Rumänien dagegen ist von kleineren (< 1 Mio. m³) bekannten seismischen Massenbewegungen geprägt (ausgelöst durch Erdbeben in 1940 und 1977). In solchen Regionen müssen dynamische Stabilitätsanalysen potentielles Bodenversagen durch Erdbeben berücksichtigen. Um die Massenbewegungen beider Regionen aufzuschließen, wurden verschiedene Methoden angewandt. Zu den Erkundungsmethoden zählen geotechnische, geologische und geomorphologische Untersuchungen, wie auch geophysikalische Methoden: ERT (electrical resistivity tomography), mikroseismische Bodenunruhe-Messungen (H/V-Methode), sowie SRT (seismic refraction tomography) samt Analyse seismischer Oberflächenwellen. Insbesondere die H/V-Methode ist eine zunehmend gebräuchliche Methode zur Erkundung von Hangrutschungen (1D-Abschätzung von Lockersedimentschichten, d.h. in diesem Fall von gestörten Bodenschichten). Geomechanische Eigenschaften des Hangmaterials wurden mithilfe von kleinen geotechnischen Studien (Erkundungsbohrungen, Schmidt Hammer, Strukturanalysen) und seismischen Parametern ermittelt. 3D-Geo-Modelle ermöglichen die Integration der gemessenen Daten durch Datenfusion und geostatistische Techniken. Dabei wird die Modelloberfläche anhand hochauflösender Fernerkundungsdaten (1 m LiDAR – Light Detection and Ranging) abgebildet, der Untergrund des Untersuchungsgebiets hingegen durch die Modellierung geologischer Trennflächen und Volumina. Die Geo-Modelle dienen als Basis zur Übertragung der ermittelten Daten in 2D numerische Modelle. Eine dynamische back-analysis der Untersuchungsgebiete ermöglicht die numerische Berechnung seismischer Auswirkungen auf die rutschungsanfälligen Hänge. [less ▲]

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See detailLes dispositifs de test et de filtre des étudiants dans l’enseignement supérieur
Detroz, Pascal ULiege; Dehon, Catherine; Romainville, Marc et al

Report (2017)

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See detailBrentano, la théorie des catégories et la définition de la substance
Boccaccini, Federico ULiege

in Etudes Philosophiques (2017)

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See detailComposantes météorologiques de la base de données océanographique RACE de STARESO (Baie de Calvi – Corse)
Binard, Marc ULiege

in Bulletin de la Société Géographique de Liège (2017), 68

Since the creation of the Calvi oceanographic station (STARESO) in the early 1970s, a great deal of data has been acquired by ULg researchers. In 2005 it was decided to create the RACE database in order ... [more ▼]

Since the creation of the Calvi oceanographic station (STARESO) in the early 1970s, a great deal of data has been acquired by ULg researchers. In 2005 it was decided to create the RACE database in order not only to preserve the old and current measures but also to promote their dissemination and exploitation. In this article, particular attention is paid to the acquisition and exploitation of the meteorological data of the RACE database and also the CalviOnLine database updated every 20 minutes by the on line reception of the new climatological data from a meteorological station located close to the oceanographic station. [less ▲]

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