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See detailLes eaux minérales et thermales en Wallonie : les eaux minérales de Valvert
Bouezmarni, Mohamed ULg; Debbaut, Vincent ULg; Naa, Paul

in Dassargues, Alain; Walraevens, Kristine (Eds.) Watervoerende lagen & grondwater in België - Aquifères & eaux souterraines (2014)

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See detailComparison of centralized, distributed and hierarchical model predictive control schemes for electromechanical oscillations damping in large-scale power systems
Wang, Da ULg; Glavic, Mevludin ULg; Wehenkel, Louis ULg

in International Journal of Electrical Power & Energy Systems (2014), 58

The paper investigates the feasibility of applying Model Predictive Control (MPC) as a viable strategy to damp wide-area electromechanical oscillations in large-scale power systems. First a fully ... [more ▼]

The paper investigates the feasibility of applying Model Predictive Control (MPC) as a viable strategy to damp wide-area electromechanical oscillations in large-scale power systems. First a fully centralized MPC scheme is considered, and its performances are evaluated first in ideal conditions and then by considering state estimation errors and communication delays. This scheme is further extended into a distributed scheme with the aim of making it more viable for very large-scale or multi-area systems. Finally, a robust hierarchical multi-area MPC scheme is proposed, introducing a second layer of MPC based controllers at the level of individual power plants and transmission lines. Simulations are carried out using a 70-bus test system. The results reveal all three MPC schemes as viable solutions to supplement existing controllers in order to improve the system performance in terms of damping. The hierarchical scheme is the one combining the best performances in nominal conditions and the best robustness with respect to partial component failures and various modeling and measurement errors. [less ▲]

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See detailOn the Quality of BGP Route Collectors for iBGP Policy Inference
Cittadini, Luca; Vissicchio, Stefano; Donnet, Benoît ULg

in IFIP Networking (2014, June)

A significant portion of what is known about Internet routing stems out from public BGP datasets. For this reason, numerous research efforts were devoted to (i) assessing the (in)completeness of the ... [more ▼]

A significant portion of what is known about Internet routing stems out from public BGP datasets. For this reason, numerous research efforts were devoted to (i) assessing the (in)completeness of the datasets, (ii) identifying biases in the dataset, and (iii) augmenting data quality by optimally placing new collectors. However, those studies focused on techniques to extract information about the AS-level Internet topology. In this paper, we show that considering different metrics influences the conclusions about biases and collector placement. Namely, we compare AS-level topology discovery with \iac inference. We find that the same datasets exhibit significantly diverse biases for these two metrics. For example, the sensitivity to the number and position of collectors is noticeably different. Moreover, for both metrics, the marginal utility of adding a new collector is strongly localized with respect to the proximity of the collector. Our results suggest that the ``optimal'' position for new collectors can only be defined with respect to a specific metric, hence posing a fundamental trade-off for maximizing the utility of extensions to the BGP data collection infrastructure. [less ▲]

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See detailOn the Performance of the LISP Beta Network
Coras, Florin; Saucez, Damien; Iannone, Luigi et al

in IFIP Networking (2014, June)

The future Internet has been a hot topic during the past decade and many approaches towards this future Internet, ranging from incremental evolution to complete clean slate ones, have been proposed. One ... [more ▼]

The future Internet has been a hot topic during the past decade and many approaches towards this future Internet, ranging from incremental evolution to complete clean slate ones, have been proposed. One of the proposition, LISP, advocates for the separation of the identifier and the locator roles of IP addresses to reduce BGP churn and BGP table size. Up to now, however, most studies concerning LISP have been theoretical and, in fact, little is known about the actual LISP deployment performance. In this paper, we fill this gap through measurement campaigns carried out on the LISP Beta Network. More precisely, we evaluate the performance of the two key components of the infrastructure: the control plane (i.e., the mapping system) and the interworking mechanism (i.e., communication between LISP and non-LISP sites). Our measurements highlight that performance offered by the LISP interworking infrastructure is strongly dependent on BGP routing policies. If we exclude misconfigured nodes, the mapping system typically provides reliable performance and relatively low median mapping resolution delays. Although the bias is not very important, control plane performance favors USA sites as a result of its larger LISP user base but also because European infrastructure appears to be less reliable. [less ▲]

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See detailCombined uses of supervised classification and Normalized Difference Vegetation Index techniques to monitor land degradation in the Saloum saline estuary system
Dieng, Ndeye Maguette ULg; Dinis, Joel; Faye, Serigne et al

in Diop, Salif; Barusseau, Jean-Paul; Descamp, Cyr (Eds.) The Land/Ocean Interactions in the Coastal Zone of West and Central Africa, Estuaries of the World (2014)

Saltwater contamination constitutes a serious problem in Saloumestuary, due to the intermittent and reverse tide flows of the Saloum River. This phenomenon is caused by the runoff deficit, which forces ... [more ▼]

Saltwater contamination constitutes a serious problem in Saloumestuary, due to the intermittent and reverse tide flows of the Saloum River. This phenomenon is caused by the runoff deficit, which forces the advance of saltwater 60 km upstream, contaminating surface water and thus causing the degradation of biodiversity and large areas of agricultural soils in this region. The present study aims to evaluate the consequences of saltwater contamination in the last three decades in this estuary by assessing the land-cover dynamics. Thus, latter consists of tracking the landscape-changing process over time to identify land-cover transitions. These transitions are closely related to the ecosystem-setting condition and can be used to assess the combined impacts of both natural and human-induced phenomena over a given period of time. In this study, special attention was given to mangrove degradation and to temporal progression of the salty barren soils locally called ‘‘tan’’. The loss of mangrove areas to tan and the general increase in salty barren soil areas can reflect the increase in the level of salinization in the study area over the time period under consideration. To fulfill this objective, four Landsat satellite images from the same season in the years 1984, 1992, 1999, and 2010 were used to infer time series land-use and land-cover maps of the Saloumestuary area. In addition to satellite imagery, rainfall records were used to evaluate climatic variation in terms of high-to-low precipitation during the time span considered. Spectral analysis indicated that from 1984 to 2010, mangroves and savanna/ rain-fed agriculture are converted to ‘‘tan’’ (denuded and salty soils). In addition, these results showed that significant changes in land use/land cover occur within the whole estuary system and reflecting therefore environmental degradation, such as land desertification and salinization, and vegetation degradation which reflect the advanced of salinity [less ▲]

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See detailIn situ FTIR micro-spectroscopy to investigate polymeric fibers under supercritical carbon dioxide: CO2 sorption and swelling measurements
Champeau, Mathilde; Thomassin, Jean-Michel ULg; Jérôme, Christine ULg et al

in Journal of Supercritical Fluids (2014), 90

An original experimental set-up combining a FTIR (Fourier Transformed InfraRed) microscope with a high pressure cell has been built in order to analyze in situ and simultaneously the CO2 sorption and the ... [more ▼]

An original experimental set-up combining a FTIR (Fourier Transformed InfraRed) microscope with a high pressure cell has been built in order to analyze in situ and simultaneously the CO2 sorption and the polymer swelling of microscopic polymer samples, such as fibers, subjected to supercritical carbon dioxide. Thanks to this experimental set-up, we have determined as a function of the CO2 pressure (from 2 to 15 MPa) the CO2 sorption and the polymer swelling at T = 40 °C of four polymer samples, namely PEO (polyethylene oxide), PLLA (poly-l-lactide acid), PET (polyethylene terephtalate) and PP (polypropylene). The quantity of CO2 sorbed in all the studied polymers increases with pressure. PEO and PLLA display a significant level of CO2 sorption (20 and 25% respectively, at P = 15 MPa). However, we observe that a lower quantity of CO2 can be sorbed into PP and PET (7 and 8% respectively, at P = 15 MPa). Comparing their thermodynamic behaviors and their intrinsic properties, we emphasize that a high CO2 sorption can be reach if on one hand, the polymer is able to form specific interaction with CO2 in order to thermodynamically favor the presence of CO2 molecules inside the polymer and on the other, displays high chains mobility in the amorphous region. PLLA and PEO fulfilled these two requirements whereas only one property is fulfilled by PET (specific interaction with CO2) and PP (high chains mobility). Finally, we have found that for a given CO2 sorption, the resulting swelling of the polymer depends mainly on its crystallinity. [less ▲]

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See detailEffect of task demands on phonological acquisition : the acquisition of phonemes in French speaking children aged 30 to 53 months in four different contexts.
Maillart, Christelle ULg; Vaucel, Cécile; Macleod, Andrea

Poster (2014, June)

When children first begin to produce the phonemes of their language, their productions are characterized by a high degree of variability (e.g., Ferguson & Farwell, 1975) and are influenced by task demands ... [more ▼]

When children first begin to produce the phonemes of their language, their productions are characterized by a high degree of variability (e.g., Ferguson & Farwell, 1975) and are influenced by task demands (Khami, Catts, & Davis, 1984). As children’s phonological representations become more defined, their productions become more stable and less influenced by the task demands. Despite the clinical significance of phonological variability, there exists no normative data that can be used to objectively describe this variability in French. The goal of the present study was to describe variability and consistency among French-speaking children between the ages of 30 and 53 months, according to task demands. A total of 153 children participated in the present study and were equally distributed in four groups (aged 30-35, 36-41, 42-47, and 48-53 months). We created a picture identification task with 65 target words, which contained the consonants of French in word initial, medial and final position. The children were asked to produce these words in four different contexts : 1) picture naming ; 2) word repetition ; 3) sentence repetition ; 4) spontaneous language. Two measures of consistency were used. (1) A consonant level analysis that investigated the stability of phonological accuracy. (2) A word level analysis that investigated the consistency of productions across the four tasks. We predict that younger children will be more influenced by changes in task complexity than older children. [less ▲]

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See detailAnalyse du métier de facilitateur et de son rôle dans la diffusion de normes d’emploi : le cas d’un bureau de chômage belge
Orianne, Jean-François ULg; Beuker, Laura ULg

Conference (2014, June)

En 2004, suite aux injonctions européennes en matière d’activation impulsées par les lignes directrices de 2003-2005, la Belgique met en place le PAC (ou Plan d’Accompagnement des chômeurs). Cette ... [more ▼]

En 2004, suite aux injonctions européennes en matière d’activation impulsées par les lignes directrices de 2003-2005, la Belgique met en place le PAC (ou Plan d’Accompagnement des chômeurs). Cette importante réforme prévoit – notamment – la mise en place de la procédure d’activation du comportement de recherche d’emploi par l’Office National de l’Emploi (Ou l’ONEm). Désormais, des agents sont spécifiquement dédiés à l’évaluation des efforts menés par les demandeurs d’emploi (ou DE) pour s’insérer sur le marché du travail : ce sont les facilitateurs. Si la procédure d’évaluation est officiellement définie, la décision, quant à elle, est bel et bien fonction de l’agent, qui doit interpréter le cadre réglementaire général à l’aune de la situation singulière du demandeur d’emploi. À l’aide d’une étude de cas réalisée au sein d’un bureau de chômage situé en Belgique francophone, nous allons tenter d’ouvrir la « boîte noire » du jugement des facilitateurs. À partir d’une approche qualitative cumulant des entretiens semi-directifs et de l’observation d’interactions entre facilitateurs et demandeurs d’emploi, nous montrerons que la décision des facilitateurs n’est ni arbitraire, ni déterminée. Elle est, au contraire, le fruit de la mobilisation d’une multitude d’appuis conventionnels dans l’action (Dodier, 1993). En outre, dans la lignée des travaux de Benarrosh (2000 ; 2006 ; 2012) nous démontrerons que ces agents sont des « pourvoyeurs » de normes institutionnelles précises à destination des demandeurs d’emploi. [less ▲]

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See detailConcrete Surface Engineering for Cultural Heritage
Courard, Luc ULg

Scientific conference (2014, June)

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See detailLes eaux minérales et thermales de Chaudfontaine
Ruthy, Ingrid ULg; Cornet, Jean-Louis

in Dassargues, Alain; Walraevens, Kristine (Eds.) Watervoerende lagen & grondwater in België - Aquifères & eaux souterraines en Belgique (2014)

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See detailCalcaires et grès des bassins de la Vesdre et de la Gueule
Ruthy, Ingrid ULg; Biron, Jean-Paul; Dassargues, Alain ULg

in Dassargues, Alain; Walraevens, Kristine (Eds.) Watervoerende lagen & grondwater in België - Aquifères & eaux souterraines en Belgique (2014)

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See detailAquifères des formations du jurassique et du trias en Lorraine belge.
Debbaut, Vincent ULg; Bouezmarni, Mohamed ULg

in Dassargues, Alain; Walraevens, Kristine (Eds.) Watervoerende lagen & grondwater in België - Aquifères & eaux souterraines (2014)

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See detailQu'est-ce que l'entrepreneuriat social ? Origines et singularités
Dufays, Frédéric ULg

Article for general public (2014)

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See detailCalcaires et grès du Synclinorium de Dinant
Gesels, Julie ULg; Nogarède, Pierre; Hallet, Vincent et al

in Dassargues, Alain; Walraevens, Kristine (Eds.) Watervoerende lagen en grondwater in Belgïe - Aquifères et eaux souterraines en Belgique (2014)

Detailed reference viewed: 9 (4 ULg)