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See detailSurface circulation in the Western Mediterranean shown by a synergy of satellite-derived datasets
Karimova, Svetlana ULiege

in Proc. SPIE 10422, Remote Sensing of the Ocean, Sea Ice, Coastal Waters, and Large Water Regions 2017 (2017, October 03)

The present study is aimed at bringing together the benefits of different approaches for extracting information on surface currents from satellite-derived datasets and ocean data reanalysis. As a region ... [more ▼]

The present study is aimed at bringing together the benefits of different approaches for extracting information on surface currents from satellite-derived datasets and ocean data reanalysis. As a region of interest, we use the Western Mediterranean, which is having a peculiar pattern of surface circulation, due to the inflow of Atlantic water through the Strait of Gibraltar. Among the data analysed in this study, there are fields of sea surface temperature (SST) as well as different datasets on surface currents retrieved from satellite altimetry data, satellite imagery and their synergy. In particular, we analyse (i) fields of geostrophic currents retrieved from a gridded sea level anomaly (SLA) data product, (ii) the data on total surface currents derived in the framework of the GlobCurrent project, and (iii) the data provided by reanalysis. Special attention is being paid to the performance of different datasets in manifesting largest mesoscale eddies of the region of interest. As a result of the comparison performed, the general scheme of surface circulation in the region of interest was updated. Main novelties proposed by the renewed scheme concerns the number of cyclonic gyres presenting in the field of surface currents. [less ▲]

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See detailGenealogie der Autorschaft: Elfriede Jelinek, die 1968-er Generation und das literarische Feld Österreichs
Neelsen, Sarah ULiege

in Klein, Delphine; Vennemann, Aline (Eds.) „MACHEN SIE WAS SIE WOLLEN!“ AUTORITÄT DURCHSETZEN, ABSETZEN UND UMSETZEN. (2017, October)

La question de l’autorité de l’auteur est abordée à l’aide de deux concepts clés de la théorie du champ de Pierre Bourdieu: „la relation“ et „la position“. Ainsi Elfriede Jelinek n’est plus perçue comme ... [more ▼]

La question de l’autorité de l’auteur est abordée à l’aide de deux concepts clés de la théorie du champ de Pierre Bourdieu: „la relation“ et „la position“. Ainsi Elfriede Jelinek n’est plus perçue comme un phénomène isolé, mais comme un acteur du champ littéraire, dans lequel elle est reliée à d’autres positions (écrivains, institutions) et où l’autorité est conférée, disputée voire retirée. L’article essaie de mettre en évidence la construction de l’autorité en l’historicisant. Trois phases de la trajectoire d’Elfriede Jelinek sont présentées : ses débuts lors de la Semaine culturelle pour la jeunesse) Innsbruck, son ascension dans la presse et finalement son internationalisation. Ainsi le rôle des champs voisins, tels que les médias et les institutions culturelles, dans le processus d’autorisation d’un auteur se trouve pris en compte. Des contributions d’Elfriede Jelinek dans la presse germanophone, peu analysées jusqu’ici, servent d’illustrations à l’argumentation. [less ▲]

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See detailin and out-of sequence event stratigraphy across the Devonian-Carboniferous Boundary - a view from the shelf in S Belgium
Denayer, Julien ULiege; Mottequin, Bernard; Prestianni, Cyrille et al

in 33rd International Meeting of Sedimentology - 16ème Congrès français de sédimentologie : Abstract book (2017, October)

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See detailDevelopment and decease of the so-called Frasnian reefs in the Frasnian of Belgium
Poty, Edouard; Denayer, Julien ULiege; Mottequin, Bernard

in 33rd International Meeting of Sedimentology - 16ème Congrès français de sédimentologie : Abstrcat Book (2017, October)

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See detailInsuffisance ovarienne prématurée chez une femme symphalangie : études biologiques et génétiques
VALDES SOCIN, Hernan Gonzalo ULiege; Desir, J; LIBIOULLE, Cécile ULiege et al

in Annales d'Endocrinologie - Abstract book (2017, October)

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See detailCYCLOSTRATIGRAPHIC ANALYSIS OF THE LOWER CRETACEOUS TERRESTRIAL SONGLIAO BASIN, NORTHEAST CHINA
Liu, Wei; Wu, Huaichum; Hinnov, Linda et al

in 33 rd INTERNATIONAL MEETING OF SEDIMENTOLOGY, 16ème CONGRÈS FRANÇAIS DE SÉDIMENTOLOGIE (2017, October)

Recent exploration of the Songliao Basin, NE China, which is one of the largest and longlived Cretaceous continental basins in the world with a continuous 10-km-thick sequence of strata, provides new ... [more ▼]

Recent exploration of the Songliao Basin, NE China, which is one of the largest and longlived Cretaceous continental basins in the world with a continuous 10-km-thick sequence of strata, provides new opportunities to study terrestrial climate change and to improve the Early Cretaceous time scale. Understanding the evolution of the basin, including the climatic and environmental changes that affected sediment deposition, is key to identifying the forces that led to enhanced carbon burial and preservation, leading to today’s oil and gas reserves in the basin. In this study, we conduct cyclostratigraphic analysis on natural gamma-ray logs from extended boreholes in the Songliao Basin. The target is the Lower Cretaceous Shahezi Formation (K1S), a 836-m-thick succession with black and dark grey mudstone, siltstone, fine grained sandstone, gravel-bearing sandstone and conglomerate, together with meter-scale black coal units distributed throughout the upper part of the formation. The mudstones have the highest gamma-ray values and the conglomerates the lowest gammaray values. Time series analysis of the gamma-ray logs from selected boreholes reveals power spectra that are consistent with Earth’s astronomical frequencies of precession, obliquity and orbital eccentricity, providing strong evidence for astronomically driven climate change. The results also indicate that black coal coincides with short eccentricity minima that exceed a threshold. We conclude that the age of K1S is from early Valanginian to late Hauterivian with a duration of approximately 11 million years by calculating cycle number and matching with the La2004 theoretical astronomical model. The formation may also reflect the well-known transient cooling Weissert Event in the mid-Valanginian as evidenced by marine glendonites at Svalbard Island. The cyclic evolution of the formation’s lithology indicates a paleo-lake and surrounding environment that expanded and contracted repeatedly. Astronomical forcing influenced paleo-lake level: climate was warm and humid with high orbital eccentricity, and cold and dry with low orbital eccentricity. Sedimentation rates significantly decreased from lower to upper K1 S as the basin evolved from synrift to post-rift conditions. [less ▲]

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See detailLes interactions enseignant/enfants comme soutien au développement langagier des enfants en classe maternelle
Leroy, Sandrine ULiege; Bergeron-Morin, Lisandre ULiege; Desmottes, Lise ULiege et al

in Les entretiens de Bichat : les entretiens d'orthophonie 2017 : Les pathologies du langage chez l'enfant de moins de 6 ans: facteurs de risque (FR), facteurs de protection (FP) (2017, September 22)

L'école maternelle constitue un contexte privilégié pour soutenir le développement du langage et de la communication des enfants. La qualité des interactions entre l’enseignant et les enfants de sa classe ... [more ▼]

L'école maternelle constitue un contexte privilégié pour soutenir le développement du langage et de la communication des enfants. La qualité des interactions entre l’enseignant et les enfants de sa classe est reconnue comme étant l’aspect le plus déterminant de la qualité éducative, notamment en ce qui concerne le développement langagier. Cet article a pour objectif de faire un survol de la littérature sur le développement du langage des enfants en contexte préscolaire, sur le rôle que peut y jouer l’enseignant, ce qui ouvre des perspectives quant aux modalités de développement professionnel des enseignants en maternelle. [less ▲]

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See detailPerformance-based fire design and the U.S. prescriptive guidelines: A comparative study
Elhami Khorasani, Negar; Fang, Chenyang; Gernay, Thomas ULiege

in Proceedings of the 39th IABSE Symposium (2017, September 21)

Current codes and standards for fire design of structures in the United States are mainly based on design at the component level using prescriptive approaches, while performance-based design for fire can ... [more ▼]

Current codes and standards for fire design of structures in the United States are mainly based on design at the component level using prescriptive approaches, while performance-based design for fire can be used to address the needs for designing modern buildings with cost-effective solutions. Previous research shows that, when system-level performance is considered, fire protection on secondary beam elements in composite steel-concrete floor systems is not necessary due to the development of a membrane action in the concrete slab during fire. This study compares the fire design of a 9-story office building using prescriptive and performance-based designs. The safety levels of the two designs are investigated and compared. It is shown that performance-based design can be used to achieve the required level of safety currently enforced in the U.S. prescriptive guidelines, while providing an opportunity for cost reduction in fire protection material. [less ▲]

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See detail1. Implantation des cultures
Eylenbosch, Damien ULiege; Meza Morales, Walter ULiege; Monfort, Bruno et al

in Bodson, Bernard; Watillon, Bernard (Eds.) Livre Blanc Céréales (2017, September 14)

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See detail2. Variétés
Meza Morales, Walter ULiege; Jacquemin, Guillaume; Dumont, Benjamin ULiege et al

in Bodson, Bernard; Watillon, Bernard (Eds.) Livre Blanc Céréales (2017, September 14)

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See detail5. Froment 2017: une récolte hâtive et étalée avec une qualité moyenne
Sinnaeve, Georges; Gofflot, Sébastien; Chandelier, Anne et al

in Bodson, Bernard; Watillon, Bernard (Eds.) Livre Blanc Céréales (2017, September 14)

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See detailInfluences of feeding behaviour and forage quality on diurnal methane emission dynamics of grazing cows
Blaise, Yannick ULiege; Andriamandroso, Andriamasinoro ULiege; Heinesch, Bernard ULiege et al

in Berckmans, Daniel; Keita, Keita (Eds.) Precision Livestock Farming ‘17 (2017, September 12)

This study aimed to evaluate diurnal methane (CH4) emission dynamics of grazing cattle and highlight their relationships with biotic factors such as the feeding behaviour as well as seasonal changes in ... [more ▼]

This study aimed to evaluate diurnal methane (CH4) emission dynamics of grazing cattle and highlight their relationships with biotic factors such as the feeding behaviour as well as seasonal changes in pasture characteristics. Existing methods to assess grazing ruminants’ daily CH4 emissions provide useful insights to investigate mitigation strategies relying on feeding and genetic selection. Nonetheless such methods based on tracer gases (SF6) or feeding bins equipped with sniffers (e.g. GreenFeed) can hardly cover diurnal CH4 emission fluctuations which can influence the accuracy of total CH4 production estimations. Previous studies in barns showed that emission dynamics strongly vary during post feeding time, leading to a possible bias in estimates of daily CH4 emissions as high as 100%. To investigate whether such fluctuations are also taking place on pasture, a portable device was designed with infrared CH4 and CO2 sensors measuring concentrations in the exhaled air at a high sampling rate (4 Hz). Six grazing dry red-pied cows were equipped with the device and motion sensors during runs of 24h to monitor CH4 and CO2 emissions and detect their feeding behaviours (grazing, rumination and other behaviours), respectively. This experiment was performed in summer and fall in order to cover seasonal changes in pasture forage quality. Methane emission was estimated from the CH4:CO2 concentration ratio and the metabolic CO2 production of the cows. As for barn studies, variations were observed in total daily CH4 emission due to the seasons and diurnal variations were also observed due to animal behaviours. Relationships between animal feeding behaviour and CH4 emissions patterns on pasture were also unravelled. [less ▲]

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See detailBuckling of steel plates at elevated temperatures: Theory of perfect plates vs finite element analysis
Maraveas, Chrysanthos ULiege; Gernay, Thomas ULiege; Franssen, Jean-Marc ULiege

in Proceedings of CONFAB'17 Conference (2017, September 11)

The local buckling capacity of fire exposed thin-walled steel cross sections is affected by the reduction in strength and stiffness due to elevated temperatures and the amplitude of the initial local ... [more ▼]

The local buckling capacity of fire exposed thin-walled steel cross sections is affected by the reduction in strength and stiffness due to elevated temperatures and the amplitude of the initial local imperfections. Several researchers have proposed design methods to calculate the capacity of the plates (i.e. web and flanges) that compose these steel members at elevated temperatures, but they used different shapes of steel plates (sides ratio a/b) and different amplitudes of local imperfections. This variability in hypotheses happens because there is no clear provision defining the numerical modeling procedure for fire design of steel plates in the codes (European or US). According to the theory of perfect plates, the critical load depends of the shape of the rectangular plate (e.g. the sides ratio a/b) and the corresponding buckling mode (number of half waves), the boundary and the loading conditions. This paper reviews the existing code provisions and compares the existing design models and their assumptions for thin-walled steel cross sections. Elements of the theory of perfect plates are presented. Parametric finite element analyses are then conducted on isolated steel plates at elevated temperatures to investigate the effect of the plate shape (a/b ratio) and imperfections (amplitude and number of half wave lengths). From the analysis, the governing parameter will be estimated (a/b vs imperfections) for simulation of isolated flanges and webs. Finally, recommendations for the numerical modeling of steel plates at elevated temperatures are proposed. [less ▲]

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See detailA method for hybrid fire testing: Development, implementation and numerical application
Sauca, Ana ULiege; Mergny, Elke ULiege; Gernay, Thomas ULiege et al

in Gillie, Martin; Wang, Yong (Eds.) Proceedings of ASFE 2017 Conference (2017, September 08)

Hybrid Fire Testing (HFT) is a technique that allows assessing experimentally the fire performance of a structural element under real boundary conditions that capture the effect of the surrounding ... [more ▼]

Hybrid Fire Testing (HFT) is a technique that allows assessing experimentally the fire performance of a structural element under real boundary conditions that capture the effect of the surrounding structure. To enable HFT, there is a need for a method that is unconditionally stable, ensures equilibrium and compatibility at the interface and captures the global behaviour of the analysed structure. A few attempts at conducting HFT have been described in the literature, but it can be shown, based on the analytical study of a simple one degree-of-freedom elastic system, that the considered method was fundamentally unstable in certain configurations which depend on the relative stiffness between the two substructures, but which cannot be easily predicted in advance. In this paper, a new method is introduced to overcome the stability problem and it is shown through analytical developments and applicative examples that the stability of the new method does not depend on the stiffness ratio between the two substructures. The new method is applied in a virtual hybrid test on a 2D reinforced concrete beam part of a moment resisting frame, showing that stability, equilibrium and compatibility are ensured on the considered multiple degree-of-freedom system. Besides, the virtual HFT succeeds in reproducing the global behaviour of the analysed structure. The method development and implementation in a virtual (numerical) setting is described, the next step being its implementation in a real (laboratory) hybrid test. [less ▲]

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See detailComparative fire analysis of steel-concrete composite buildings designed following performance-based and U.S. prescriptive approaches
Elhami Khorasani, Negar; Fang, Chenyang; Gernay, Thomas ULiege

in Gillie, Martin; Wang, Yong (Eds.) Proceedings of ASFE 2017 Conference (2017, September 08)

Performance-based structural fire design provides a rational methodology for designing modern buildings with cost-effective solutions. However, in the United States, fire design still largely relies on ... [more ▼]

Performance-based structural fire design provides a rational methodology for designing modern buildings with cost-effective solutions. However, in the United States, fire design still largely relies on design at the component level using prescriptive approaches. With performance-based approaches, there is an opportunity to benefit from increased flexibility and reduced cost in the design, but these advantages need to be explicitly described and disseminated to promote this shift in paradigm. In this paper, a comparative analysis is conducted on multi-story steel-concrete buildings designed following performance-based and U.S. prescriptive approaches. The steel-concrete composite structure allows taking advantage of tensile membrane action in the slab during fire, and therefore removing the fire protection on secondary beam elements. The nonlinear finite element software SAFIR is used to model the behavior of the buildings under the standard ASTM fire and a natural fire determined using the two-zone fire model CFAST. The numerical simulations show that performance-based design can be used to achieve the required level of safety currently enforced in the U.S. prescriptive guidelines, while providing an opportunity for cost reduction in fire protection material. [less ▲]

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See detailSensitivity of elevated temperature load carrying capacity of thin-walled steel members to local imperfections
Maraveas, Chrysanthos ULiege; Gernay, Thomas ULiege; Franssen, Jean-Marc ULiege

in Gillie, Martin; Wang, Yong (Eds.) Proceedings of ASFE 2017 Conference (2017, September 07)

The local buckling capacity of fire exposed thin-walled steel cross sections is affected by the reduction in strength and stiffness due to elevated temperatures and by the amplitude of the initial local ... [more ▼]

The local buckling capacity of fire exposed thin-walled steel cross sections is affected by the reduction in strength and stiffness due to elevated temperatures and by the amplitude of the initial local imperfections. Several researchers have proposed design methods to calculate the capacity of these steel members at elevated temperatures, but they used different methodologies and different amplitude of local imperfections in the extensive numerical analyses that are typically at the base of these methods. This variability in hypotheses happens because there is no clear provision defining the local imperfection amplitude for fire design in the codes (European or US). EN 1993-1-5 proposes amplitude values of local imperfections for ambient temperature design, while EN 1090-2 defines a -different- maximum allowed size of fabrication tolerance during production. Meanwhile, other sizes of local imperfections have also been proposed in the literature, with values different than those from EN 1993-1-5 and EN 1090-2. This paper reviews the existing code provisions and compares the existing design models and their assumptions for thin-walled steel cross sections. Finite element analyses are then conducted on isolated steel plates at elevated temperatures to investigate the effect of local imperfections. Finally, specific amplitude of local imperfections is proposed for fire design of thin-walled steel members. [less ▲]

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See detailEffect of upgrading concrete strength class on fire performance of reinforced concrete columns
Gernay, Thomas ULiege; Peric, Vlado; Mihaylov, Boyan ULiege et al

in Gillie, Martin; Wang, Yong (Eds.) Proceedings of ASFE 2017 Conference (2017, September 07)

High strength concrete (HSC) provides several advantages over normal strength concrete (NSC) and is being used in multi-story buildings for reducing the dimensions of the columns sections and increasing ... [more ▼]

High strength concrete (HSC) provides several advantages over normal strength concrete (NSC) and is being used in multi-story buildings for reducing the dimensions of the columns sections and increasing the net marketable area. However, upgrading of concrete strength class in a building may affect the fire performance, due to higher rates of strength loss with temperature and higher susceptibility to spalling of HSC compared with NSC. Reduction of columns sections also leads to increased member slenderness and faster temperature increase in the section core. These detrimental effects are well known, but their impact on fire performance of structures has not been established in terms of comparative advantage between NSC and HSC. In other words, it is not clear whether the consideration of fire resistance limits the opportunities for use of HSC for reducing the dimensions of columns sections in multi-story buildings. This research aims to address this question by comparing the fire behaviour of reinforced concrete columns made of NSC and HSC using nonlinear finite element modelling. The evolution of load bearing capacity of the columns is established as a function of the fire exposure duration. A 15-story car park structure is adopted as a case study with alternative designs for the columns based on strength classes ranging from C30 to C90. Results show that, although the replacement of NSC by HSC accelerates the reduction rate of columns capacity under fire, the columns generally have significant reserves in resistance leading to sufficient fire resistance. This study gives an insight into the impact of replacing stocky sections in NSC by more slender sections in HSC on fire resistance rating for multi-story structures. [less ▲]

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See detailSpatio-temporal Monitoring of Heat Storage in a Shallow Aquifer Using Electrical Resistivity 4D Imagery and DTS
Lesparre, Nolwenn ULiege; Hermans, Thomas ULiege; Nguyen, Frédéric ULiege et al

in EarthDoc (2017, September 06)

The design of groundwater heat pumps requires a good understanding of the aquifer and heat flow conditions. Issues of short-circuit or recycling between cold and hot wells have to be carefully considered ... [more ▼]

The design of groundwater heat pumps requires a good understanding of the aquifer and heat flow conditions. Issues of short-circuit or recycling between cold and hot wells have to be carefully considered. Surface geophysical methods allow monitoring subsurface processes without additional perturbations of the medium. Within available methods, the electrical resistivity imagery (ERI) applied in time-lapse (TL) is appropriate. Here, we monitored with ERI and distributed temperature sensors (DTS) a heat plume propagation during an experiment of hot water injection in a shallow aquifer. DTS and TL ERI measurements acquired from two boreholes provide a local estimate of the heat propagation through the medium. TL ERI were also performed from a grid at surface to follow the 3D plume shape formation and evolution through time. The different complementary data validate the potential of surface TL ERI for monitoring in 3D the behavior of shallow heat plumes. ERI highlight the heterogeneity of the aquifer by distinguishing regions with higher or lower hydraulic conductivity. In the higher hydraulic conductivity zone, the heat might be evacuated through water flow, while in the lower hydraulic conductivity area heat storage is achievable. Thus, in that last region the plume temperature decreases progressively with time. [less ▲]

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See detailUsing Geophysical Hard Data to Enhance the Reliability of Hydrological Models
De Schepper, Guillaume; Paulus, Claire; Molron, J. et al

in EarthDoc (2017, September 06)

Appropriate design of geophysical experiments combined with common hydrological measurements offer opportunities to use geophysical data as hard data in hydrological models, regarding their ... [more ▼]

Appropriate design of geophysical experiments combined with common hydrological measurements offer opportunities to use geophysical data as hard data in hydrological models, regarding their conceptualisation or their calibration. Two study sites located in Wallonia, Belgium, were investigated. In the first case (fractured limestone aquifer), streaming potentials were linked to piezometric measurements, allowing us to better conceptualise the local groundwater flow model and calibrate it. In the second example (alluvial sandy aquifer), the use of 4D electrical resistivity tomography and temperature measurements appeared to be a reliable methodology to predict heat storage and recovery cycles in hydrological models with a better constrained calibration process. [less ▲]

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See detailQuantification of Temperature with Time-lapse electrical resistivity using the prediction-focused approach-A field case
Hermans, Thomas ULiege; Nguyen, Frédéric ULiege; Caers, Jef

in EarthDoc (2017, September 06)

Standard inversion of time-lapse geophysical suffers from spatially and temporally varying resolution due to the regularization procedure used during the inversion process. In this study, we apply the ... [more ▼]

Standard inversion of time-lapse geophysical suffers from spatially and temporally varying resolution due to the regularization procedure used during the inversion process. In this study, we apply the recently developed prediction-focused approach (PFA) to directly estimate temperature with electrical resistance data, without classic tomographic inversions. PFA is based on a set of prior subsurface models coherent with our prior knowledge of the site. From this set of models, we generate a prior set of temperature distribution and resistance data mimicking the field experiment. Then, we use dimension-reduction techniques to derive a direct relationship between the data and the desired prediction. The use of canonical correlation analysis linearize the relationship and allows using Gaussian regression to sample the posterior. In this paper, we demonstrate the ability of PFA to process time-lapse ERT data during a field experiment. We propose an analysis of time-lapse reciprocals to derive an error model and generate the posterior distribution of temperature. We validate the results using direct measurements in the aquifer. This successful application opens new ways to process and integrate geophysical data in hydrogeological model. [less ▲]

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See detailA First Look at the Prevalence and Persistence of Middleboxes in the Wild
Edeline, Korian ULiege; Donnet, Benoît ULiege

in International Teletraffic Congress (2017, September)

Recent years have seen an uprise in the development of middleboxes functionalities (CGNATs, proxies, accelerators, etc), participating so in the ossification of the Internet. In parallel, various ... [more ▼]

Recent years have seen an uprise in the development of middleboxes functionalities (CGNATs, proxies, accelerators, etc), participating so in the ossification of the Internet. In parallel, various solutions have been developed to detect or circumvent unwanted middleboxes interferences such as UDP-based middlebox-proof transports (Google's QUIC, PLUS), middlebox-proof extensions to TCP (HICCUPS, TCPcrypt), and middlebox traversal mechanisms (STUN, ICE, PLUS). All those solutions make the assumption of ubiquitous middleboxes. However, a view of their actual deployment in the wild, in IPv4 wired networks, is missing. In particular, knowing how autonomous systems (ASes) deploy middleboxes in terms of prevalence and persistence would provide additional relevant information to Internet topology models. In this paper, we aim at filling this gap. Based on a large-scale measurement campaign, we highlight different characteristics of middlebox deployment within ASes to elicit middleboxes profiles. [less ▲]

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See detailSemantic Background Subtraction
Braham, Marc ULiege; Pierard, Sébastien ULiege; Van Droogenbroeck, Marc ULiege

in IEEE International Conference on Image Processing (ICIP), Beijing 17-20 September 2017 (2017, September)

We introduce the notion of semantic background subtraction, a novel framework for motion detection in video sequences. The key innovation consists to leverage object-level semantics to address the variety ... [more ▼]

We introduce the notion of semantic background subtraction, a novel framework for motion detection in video sequences. The key innovation consists to leverage object-level semantics to address the variety of challenging scenarios for background subtraction. Our framework combines the information of a semantic segmentation algorithm, expressed by a probability for each pixel, with the output of any background subtraction algorithm to reduce false positive detections produced by illumination changes, dynamic backgrounds, strong shadows, and ghosts. In addition, it maintains a fully semantic background model to improve the detection of camouflaged foreground objects. Experiments led on the CDNet dataset show that we managed to improve, significantly, almost all background subtraction algorithms of the CDNet leaderboard, and reduce the mean overall error rate of all the 34 algorithms (resp. of the best 5 algorithms) by roughly 50% (resp. 20%). Note that a C++ implementation of the framework is available at http://www.telecom.ulg.ac.be/semantic. [less ▲]

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See detailThe impact of Paul Philippot on the theory and history of conservation/restoration
Stoner, Joyce; Verbeeck, Muriel ULiege

in Bridgland, Janet (Ed.) Linking Past and Future (2017, September)

Paul Philippot (1925–2016) was an influential conservation theoretician and author in addi- tion to serving as an important leader or col- laborator with major conservation institutions in Europe (ICR ... [more ▼]

Paul Philippot (1925–2016) was an influential conservation theoretician and author in addi- tion to serving as an important leader or col- laborator with major conservation institutions in Europe (ICR, ICCROM, IIC, UNESCO, ICOM, etc.). He was an art historian born into a Belgian fam- ily of conservator-restorers. The authors were privileged to interview him in 1997, 2009 and 2015. Verbeeck discusses Philippot’s relation to and reinterpretation of the philosophy of Cesare Brandi, his definition of restoration as both an intellectual judgment and a critical act, and his influence on the establishment of an interdis- ciplinary curriculum for pioneer training pro- grams. Stoner describes Philippot’s emphasis on the impact of language on communication of philosophical concepts in his 1997 interview in addition to key points in his publications once they were available in English, especially his de- scription of patina as the normal effect that time has on material and the search for equilibrium in cleaning paintings. [less ▲]

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See detailComparaison entre infiltrations de plasma riche en plaquettes et d’acide hyaluronique pour le traitement des tendinopathies patellaires
Kaux, Jean-François ULiege; Roberjot, Mathieu; Samson, Antoine

in 10ème Congrès Commun SFMES-SFTS (2017, September)

Introduction : Le traitement des tendinopathies patellaires reste difficile. C’est la raison pour laquelle de nouveaux traitements ont été développés, parmi lesquels les injections de plasma riche en ... [more ▼]

Introduction : Le traitement des tendinopathies patellaires reste difficile. C’est la raison pour laquelle de nouveaux traitements ont été développés, parmi lesquels les injections de plasma riche en plaquettes (PRP) ou d’acide hyaluronique (AH). Certaines séries cliniques ont précédemment évalué l’effet du PRP dans le traitement des tendinopathies patellaires proximales. Une revue systématique récente a conclu que les PRP pouvait être recommandé comme traitement dans cette indication. Récemment, l’AH en injection a été proposé comme traitement des tendinopathies. Certaines études fondamentales montrent des résultats encourageants sur la capacité de l’AH à promouvoir le glissement du tendon, de réduire les adhérences et améliorer son organisation architecturale. Quelques observations cliniques confirment également son impact sur la douleur et la fonction de patients avec tendinopathies. Méthodes : Trente-trois sportifs avec tendinopathies patellaires proximales non soulagés après plus de trois mois de traitements rééducatif classique ont été inclus dans l’étude. Dix-huit d'entre eux (groupe 1) ont reçu une injection de PRP pauvre en leucocytes (obtenu à l’aide d’un appareil d’aphérèse) et 15 autres sujets (groupe 2) ont bénéficié de 2 injections d’AH à 1 semaine d’intervalle; les 2 groupes ont bénéficié d’une rééducation standardisée post-infiltration. Concernant le suivi de la pathologie, une évaluation de la douleur par une échelle visuelle analogique (EVA), des scores algo-fonctionnels (IKDC, VISA-P), un algomètre de pression, un test isocinétique (associé à une EVA)) ainsi qu’une échographie du tendon patellaire (US) ont été réalisés à 3 reprises (avant injection, après 6 semaines, 3 mois après les injections). Résultats : Les résultats de l’EVA (p < 0,01), de l’algomètre de pression (p < 0,01), les scores IKDC (p < 0,01) et VISA-P (p < 0,01) montrent une amélioration significative dans les deux groupes, mais pas pour les résultats US. Pour le groupe 1, les tests isocinétiques montrent des résultats significatifs pour les ischio-jambiers à C60 °/ s, avec une amélioration de son couple de pointe maximale (p = 0, 01) pour le membre pathologique et une amélioration des différences bilatérales (p = 0,0002). Pour le groupe 2, l’amélioration du couple de pointe maximale du quadriceps à C240 ° /s est significative (p < 0,01) pour le genou pathologique après les injections après 6 semaines seulement. L’EVA associé aux tests isocinétiques diminue considérablement pour tous les modes de contraction au terme des trois mois d’études. Conclusions : Les infiltrations de PRP et d’HA peuvent toutes les 2 améliorer les symptômes de tendinopathie patellaire proximale, même si les résultats sont légèrement meilleurs au sein du groupe PRP. [less ▲]

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See detailVisco-plastic Chaboche model for nickel-based alloys under anisothermal cyclic loading
Morch, Hélène ULiege; Duchene, Laurent ULiege; Habraken, Anne ULiege

in Proceedings of the XIV International Conference on Computational Plasticity (2017, September)

The mechanical behavior of visco-plastic materials such as nickel-based alloys is highly dependent on temperature. Some characteristics such as viscosity, hardening, static recovery, dynamic recovery have ... [more ▼]

The mechanical behavior of visco-plastic materials such as nickel-based alloys is highly dependent on temperature. Some characteristics such as viscosity, hardening, static recovery, dynamic recovery have more or less influence on the overall behavior depending on the considered temperature. The unified constitutive model developed by Chaboche [1] is very efficient in representing this complexity as it is very adaptable and can contain many features. A basic Chaboche model contains a viscosity law and one or several hardening equations. Within these hardening equations, it is possible to add several features that will represent the complex behavior of the material. The aim of this study is to understand the role of the different parameters and the influence of the different features in an advanced Chaboche model adapted to cyclic anisothermal loading. This specific model was also developed in [2],[3]. However, part of this study is based on particular cases where different features of the model are analyzed [4]–[6]. [less ▲]

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See detailDamage Detection in Structures Based on Principal Component Analysis of Forced Harmonic Responses
Golinval, Jean-Claude ULiege

in Procedia Engineering (2017, September)

An approach based on principal component analysis (PCA) is considered here to tackle the problem of structural damage detection. The key idea of PCA is to reduce a large number of measured data to a much ... [more ▼]

An approach based on principal component analysis (PCA) is considered here to tackle the problem of structural damage detection. The key idea of PCA is to reduce a large number of measured data to a much smaller number of uncorrelated variables while retaining as much as possible of the variation in the original data. PCA is applied here to the problem of damage detection in structures submitted to harmonic excitation. When processing vibration measurements, it can be shown that the basis of eigenvectors (called the proper orthogonal modes) span the same subspace as the mode-shape vectors of the monitored structure. Thus the damage detection problem may be solved using the concept of subspace angle between a reference subspace spanned by the eigenvectors of the initial (undamaged) structure and the subspace spanned by the eigenvectors of the current (possibly damaged) structure. The method is illustrated on the example of a real truss structure for damage detection and is combined to a model updating technique for damage localization. [less ▲]

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See detailNumerical analysis of the fire resistance of high-strength steel circular columns
Tondini, Nicolas; Demonceau, Jean-François ULiege

in Proceeding of Eurosteel 2017 conference (2017, September)

High strength steels (HSS) have specific chemical compositions, which primarily depend on rolling tempering techniques, element thickness and the producer. Nonetheless, EN1993-1-12 related to HSS up to ... [more ▼]

High strength steels (HSS) have specific chemical compositions, which primarily depend on rolling tempering techniques, element thickness and the producer. Nonetheless, EN1993-1-12 related to HSS up to S700 grade does not provide any additional note on the design of steel structures subjected to fire and the designer is referred to EN1993-1-2 valid up to S460 grade. This paper presents the results of a numerical analysis on the behaviour at elevated temperature of Circular Hollow Sections (CHS) columns made of HSS. In details, three full-scale HSS CHS columns with average measured yield strength of 822 MPa and 3.15 m long were tested under the standard ISO fire with constant eccentric compression load. Two members were made of a cross section 323.9 mm x 10 mm and one of a cross section 355.6 mm x 12 mm. The constant applied loads during the tests were respectively equal to 10%, 14% and 19% of the axial capacity of the columns at ambient temperature. Then, a nonlinear thermomechanical finite element model made of solid elements was developed by means of ABAQUS. A fully-coupled analysis using Geometrically and Materially Nonlinear Imperfect Analysis (GMNIA) was employed meaning that the temperature field was determined together with the stress-displacement fields. The calibration of the numerical model was carried out against experimental data by exploiting the thermal and the mechanical properties of steel provided in EN1993-1-2. A sensitivity analysis was performed to highlight the main parameters that affect the simulation results, i.e. mesh size, residual stresses, geometrical imperfections etc. The calibration process showed a good agreement between the numerical results and the experimental outcomes both in terms of failure temperature and of failure mode. With the calibrated model, it was finally possible to perform a preliminary parametric analysis by varying the applied load and the column relative slenderness to assess the appropriateness of the buckling curve included in EN1993 -1-2 to predict the fire resistance of HSS CHS columns. [less ▲]

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See detailInfluence of beam-to-column joints on the robustness of earthquake-resistant moment-resistant frames
Francavilla, Antonella; Latour, Massimo; Rizzano, Gianvittorio et al

in Proceeding of Eurosteel 2017 conference (2017, September)

Robustness of Moment Resistant Frames (MRFs) designed according to current seismic codes and subjected to a loss-of-column scenario is strictly linked to the deformation capacity of beam-to-column ... [more ▼]

Robustness of Moment Resistant Frames (MRFs) designed according to current seismic codes and subjected to a loss-of-column scenario is strictly linked to the deformation capacity of beam-to-column connections, which are usually subjected to combined axial and bending loads. In the seismic design of steel frames, once avoided the yielding of columns, a global dissipative collapse mechanism has to be ensured by imposing the formation of plastic hinges at the ends of the beams or in the connections and guarantying, provided that the elements involved in plastic range have an adequate energy dissipation capacity. Within this framework, the aim of this paper is to analyse the influence of the response of the connections designed for seismic application on the global behaviour of MRFs under a loss-of-column scenario providing an accurate modelling of connections subjected to combined axial and bending loads. To this scope four different beam-to-column joints designed for seismic actions, previously tested under cyclic load history at the STRENGTH laboratory of Salerno University, have been modelled and introduced in a case-study structure, whose response has been assessed by means of push-down analyses. The performances of the analysed frames have been analysed and is compared using the Residual Reserve Strength Ratio (RRSR) index combined with the energy balance method. [less ▲]

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See detailBeam-to-column joints, column bases and joint components under impact loading
Demonceau, Jean-François ULiege; Vanvinckenroye, Hélène ULiege; D'Antimo, Marina ULiege et al

in Proceeding of Eurosteel 2017 conference (2017, September)

Recent events such as natural catastrophes or terrorist attacks have highlighted the necessity to ensure the structural integrity of buildings under exceptional events. For more than 10 years, the ... [more ▼]

Recent events such as natural catastrophes or terrorist attacks have highlighted the necessity to ensure the structural integrity of buildings under exceptional events. For more than 10 years, the University of Liege is strongly involved in researches on the response of structures further to such exceptional events through participations to national or European research projects. In particular, the University of Liege has contributed very recently to a European research project entitled ROBUSTIMPACT investigating the behaviour of steel or steel-concrete composite building structures subjected to impact loading and proposing simplified procedures to predict the response of such structures under the considered scenario. As a contribution to this research project, an experimental test campaign was realised in Liège; the objective was to study the behaviour of beam-to-column joints, of column bases and of most of their constitutive components under impact loading and, in particular, to highlight the influence of the strain rate effects on the response of the studied joints and components. The proposed paper first describes the conducted test campaign with all the required details about the tested specimens and the testing setup; then the analysis of the so-obtained experimental results is presented. Finally authors’ views on how to account for the strain rate effects in analytical approaches for joint design is briefly expressed. [less ▲]

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See detailHow to encourage conservators to produce knowledge. The CeROArt ‘lab’: Looking back at ten years of experience
Verbeeck, Muriel ULiege

in Bridgland, Janet (Ed.) Linking Past and Future (2017, September)

Knowledge transmission through a scientific publication is something that can be taught and learned. The CeROArt journal started a project that it has supported and developed over the past ten years to ... [more ▼]

Knowledge transmission through a scientific publication is something that can be taught and learned. The CeROArt journal started a project that it has supported and developed over the past ten years to provide educational support to first-time authors who have graduated in conservation, to encourage them to publish their work. This experience, conducted in Open Access with the support of several European training courses, highlights the skills acquired at the end of their studies in terms of scientific communication. It can also be used to consider several avenues for stimulating knowledge pro- duction outside the academic environment. [less ▲]

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See detailTraduction et validation du "Exercise-Induced Leg Pain Questionnaire" pour les patients francophones
Kaux, Jean-François ULiege; Hagelstein, Thibaut; Van Beveren, Julien et al

in 10ème Congrès Commun SFMES-SFTS (2017, September)

Contexte : L’EILP-G a été développé afin d’évaluer la sévérité des symptômes affectant la fonction physique et les capacités sportives chez des patients présentant des douleurs de jambe à l’effort. Le ... [more ▼]

Contexte : L’EILP-G a été développé afin d’évaluer la sévérité des symptômes affectant la fonction physique et les capacités sportives chez des patients présentant des douleurs de jambe à l’effort. Le questionnaire a déjà été traduit en anglais et en grec. Objectifs : Le but de cette étude est de traduire et de réaliser une adaptation interculturelle du questionnaire EILP-G en français ainsi que d’en évaluer ses propriétés psychométriques. Matériel et Méthode : Le processus de traduction et d’adaptation interculturelle de l’exercise-induced leg pain questionnaire for German-speaking patients (EILP-G) a été guidé par les recommandations internationales d’adaptation interculturelle de questionnaires mesurant l’état de santé. Six étapes ont été respectées : (1) traduction française initiale, (2) synthèse de traduction française, (3) traduction inverse allemande, (4) comité d’expert, (5) test de la version pré-finale, (6) approbation du comité d’expert. 84 sujets furent recrutés et répartis en 3 groupes afin de tester l’EILP-FR : un groupe de sujets pathologiques (n=28), des sportifs à risque de développer ce type de pathologie (n=28) et des étudiants en sciences de la motricité asymptomatiques (n=28). Tous les sujets (n=84) ont rempli le questionnaire français à deux reprises avec un intervalle de 7 à 10 jours, parallèlement au Short Form Health Survey (SF-36) afin de pouvoir évaluer la fiabilité et la validité de l’EILP-FR. Résultats : L’EILP-FR indique une fidélité test-retest très bonne concernant le score total (ICC 0,96). Il en va de même pour le score total de chaque sous-groupe (ICC 0,88-0,94) ainsi que pour chaque item (0,75-0,92). Le questionnaire français présente une cohérence interne élevée (0,93). La corrélation entre l’EILP-FR et le SF-36 est modérée pour le score total (0,51;p<0.001). Une corrélation forte se présente entre le questionnaire et une partie des sous-échelles convergentes du SF-36 (PF, RP et BP ; chaque p<0.001). Les sous-échelles divergentes évaluant les propriétés psychologiques du SF-36 présentent toutes une corrélation faible et statistiquement non-significatives (RE, SF, VT), excepté MH (p<0.05). Aucun effet plancher ou plafond n’a été détecté. Conclusion : La version française, adaptée de la version originale EILP-G, a été traduite et adaptée interculturellement avec succès. L’EILP-FR est un questionnaire fiable et valide pour évaluer les patients francophones souffrant de douleurs chroniques de jambe à l’effort. [less ▲]

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See detailAdaptation interculturelle du questionnaire"Kujala Anterior Knee Pain Scale » pour les patients francophones
Buckinx, Fanny ULiege; Remy, Gaël; Bornheim, Stephen ULiege et al

in 10ème Congrès Commun SFMES-SFTS (2017, September)

Introduction : Le syndrome fémoro-patellaire est l'un des problèmes du genou les plus fréquemment rencontrés. Il se caractérise par une douleur antérieure du genou dans les activités mettant en charge l ... [more ▼]

Introduction : Le syndrome fémoro-patellaire est l'un des problèmes du genou les plus fréquemment rencontrés. Il se caractérise par une douleur antérieure du genou dans les activités mettant en charge l'articulation fémoro-patellaire. Le Kujala Anterior Knee Pain Scale (Kujala AKPS) est un questionnaire utilisé pour évaluer les symptômes subjectifs, telles que les limitations fonctionnelles et la douleur antérieure du genou. Le questionnaire a déjà été traduit et validé en turc, en portugais brésilien, en persan, en chinois, et en néerlandais. Le but de cette étude est de traduire ce questionnaire en français afin d'en évaluer sa fiabilité et sa validité. Matériel et méthode : La traduction et l’adaptation interculturelle du questionnaire ont été réalisées selon les recommandations internationales comprenant 6 étapes : traduction initiale, synthèse des traductions, traduction de retour vers la langue d’origine, comité d'experts, test de la version pré-finale et approbation du comité d'experts. Une fois la version française obtenue, les participants (n=101) ont rempli 2 fois le Kujula AKPS à un intervalle de 7 jours, et le Short Form Health Survey (SF-36) afin d'en évaluer les propriétés psychométriques (la cohérence interne, la fidélité test-retest et la validité de construit). Résultats : Le Kujula AKPS montre une fidélité test-retest élevée pour le score total (ICC 0,97). La traduction française possède une cohérence interne élevée (0,87). Le Kujula AKPS possède une corrélation forte avec une partie des sous-échelles convergentes du SF-36 (PF, RP et BP). Il y a une corrélation faible ou modérée avec les sous-échelles divergentes du SF-36 (MH, SF et VT). Il n’y a pas d’effet plancher et plafond. Conclusion : La version française du questionnaire Kujula AKPS étant facilement compréhensible, elle semble avoir une bonne adaptation interculturelle. Cette étude a démontré que le Kujula AKPSF est fiable et valide pour les patients francophones souffrant d'un syndrome rotulien. [less ▲]

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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 detailVariétés - 1. Froment d'hiver
Meza Morales, Walter ULiege; Dumont, Benjamin ULiege; Jacquemin, Guillaume et al

in Watillon, Bernard; Bodson, Bernard (Eds.) Livre Blanc Céréales (2017, September)

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See detailDifferentiating pre- and post-grazing pasture heights using a 3D camera: a prospective approach
Andriamandroso, Andriamasinoro ULiege; Castro Muñoz, Eloy ULiege; Blaise, Yannick ULiege et al

in Berckmans, Daniel; Keita, Alassane (Eds.) Precision Livestock Farming ‘17 (2017, September)

Grasslands management involves the monitoring of both animal and plant components. Recent precision livestock farming developments have focused on high-rate monitoring of grazing animals to enhance ... [more ▼]

Grasslands management involves the monitoring of both animal and plant components. Recent precision livestock farming developments have focused on high-rate monitoring of grazing animals to enhance livestock productivity and welfare. The evolution of grass resource during the grazing process is not being overlooked by graziers and researchers, but grass characteristics, such as height, dry matter content, productivity or density, are still measured using low frequency and sometimes destructive and time-consuming methods; such as quadrat, sward-sticks, rising plate meters. This study investigated the potential of using 3D cameras to assess sward physical characteristics. Main objectives were: (1) to define the correct way to capture images, particularly the camera position above the ground and, (2) to assess if differences in sward height were detectable. Couples of images differing in grass height were captured on the same spot with a 3D camera at different above-ground heights (30, 40, 50 cm) on a ryegrass-white clover pasture. Pregrazing height was 15cm and post-grazing sward was simulated by cutting at 2 cm. Histograms of intensity performed on greyscale images showed differences between pre- and post-grazing sward. As expected, overall darker pixels were observed for pre-grazing images (p<0.01) and whiter pixels for post-grazing images (p<0.01), indicating longer distances consistent with lower forage biomass. Images taken at a distance of 30 and 40 cm could identify these differences. Further developments require improving the calibration of the camera and developing image analysis method to estimate more plant characteristics such as density or dry matter content. [less ▲]

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See detailPRELIMINARY STUDY ON BEAM-TO-COLUMN JOINTS UNDER IMPACT LOADING
D'Antimo, Marina ULiege; Latour, Massimo; Rizzano, Gianvittorio et al

in Proceedings CTA 2017 (2017, September)

Recent catastrophic events have pointed out the necessity of ensuring the integrity for structures under “exceptional” events. Since many years, the University of Liège is involved in different activities ... [more ▼]

Recent catastrophic events have pointed out the necessity of ensuring the integrity for structures under “exceptional” events. Since many years, the University of Liège is involved in different activities and projects mainly related to the robustness assessment of structures. The robustness of a structure is the capacity of the system to remain globally stable after events not directly ac- counted for in the design, like impact, fire or consequences of a human error, leading to a reason- able damage when compared to the original cause. Particular attention has been dedicated to the loss of column scenario with analytical and numerical investigations. As a contribution to differ- ent European projects (FREEDAM and ROBUSTIMPACT), experimental campaigns have been carried out or are currently undergoing, with the aim of understanding the behaviour of different joint typologies under impact loads. The experimental campaigns have the goal to underline the influence of the strain-rate of the joint components on the behaviour of the tested connections. In the present paper, an overview on the design criteria for the ongoing experimental campaign, on the preliminary results and findings is given and critically analysed. Particularly, an application in the field of the FREEDAM project is presented. [less ▲]

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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 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 detailIs a Memoryless Motion Detection Truly Relevant for Background Generation with LaBGen?
Laugraud, Benjamin ULiege; Van Droogenbroeck, Marc ULiege

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

The stationary background generation problem consists in generating a unique image representing the stationary background of a given video sequence. The LaBGen background generation method combines a ... [more ▼]

The stationary background generation problem consists in generating a unique image representing the stationary background of a given video sequence. The LaBGen background generation method combines a pixel-wise median filter and a patch selection mechanism based on a motion detection performed by a background subtraction algorithm. In our previous works related to LaBGen, we have shown that, surprisingly, the frame difference algorithm provides the most effective motion detection on average. Compared to other background subtraction algorithms, it detects motion between two frames without relying on additional past frames, and is therefore memoryless. In this paper, we experimentally check whether the memoryless property is truly relevant for LaBGen, and whether the effective motion detection provided by the frame difference is not an isolated case. For this purpose, we introduce LaBGen-OF, a variant of LaBGen leverages memoryless dense optical flow algorithms for motion detection. Our experiments show that using a memoryless motion detector is an adequate choice for our background generation framework, and that LaBGen-OF outperforms LaBGen on the SBMnet dataset. We further provide an open-source C++ implementation of both methods at http://www.telecom.ulg.ac.be/labgen. [less ▲]

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See detailCerebrospinal uid sampling at C1–C2
Busoni, Valeria ULiege

in BEVA Proceedings (2017, September)

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See detailEmerging methods using ultrasound for detection of soft tissue musculoskeletal disease
Busoni, Valeria ULiege

in BEVA Proceedings (2017, September)

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See detailTheorising constructions of employability and processes of social disqualification towards children and parents in poverty situations, An exploration of the work of Robert Castel and Serge Paugam
Jacquet, Nicolas ULiege

in Book of abstracts 15th Annual TiSSA Conference 2017 - Olsztyn (Poland) Social Work as a Space for Dialogue, Cooperation and Diversity (2017, August 30)

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See detailSense-Making in Cyber Security - Examining Responder Behaviors in Cyber-Attacks
Tapanainen, Tommi ULiege

in Proceedings of the Americas Conference on Information Systems (AMCIS) (2017, August 12)

Our understanding of the defense mechanisms against cyber-attacks is, to a great extent, based on preparation and deterrence. There is limited understanding, and in particular, limited evidence on how ... [more ▼]

Our understanding of the defense mechanisms against cyber-attacks is, to a great extent, based on preparation and deterrence. There is limited understanding, and in particular, limited evidence on how cyber security responders act to contain and recover from a cyber-attack. The actions of responders, including IT experts, corporate communications staff, and selected managers are critical. To address this gap, this research proposes applying the concept of sense-making, which has been extensively used to analyze human crisis behaviors. In this emerging research, we conduct an investigation into a cyber-attack case to shed light on the contextual and collective activities taken by responders in coping with cyber-attack response. We expect the results to validate or challenge theorizations of cyber security training and competencies from the communication and collaboration perspective. In a practical sense, our research can stimulate organizations to reflect on their own cyber security preparedness from the human perspective. [less ▲]

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See detailThe quest for magnetic massive stars in the Magellanic Clouds
Nazé, Yaël ULiege; Bagnulo, S.; Walborn, N. R. et al

in The Lives and Death-Throes of Massive Stars (2017, August 01)

The Of?p category was introduced more than 40 years ago to gather several Galactic stars with some odd properties. Since 2000, spectropolarimetry, high-resolution spectroscopy, long-term photometry, and X ... [more ▼]

The Of?p category was introduced more than 40 years ago to gather several Galactic stars with some odd properties. Since 2000, spectropolarimetry, high-resolution spectroscopy, long-term photometry, and X-ray observations have revealed their nature: magnetic oblique rotators - they all have magnetic fields that confine their winds. Several Of?p stars have now been detected in the Magellanic Clouds, likely the prototypes of magnetic massive stars at low metallicity. This contribution will present the most recent photometric, spectroscopic, and spectropolarimetric data, along with the first modeling of these objects. [less ▲]

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See detailTowards a more automated mineralogy
Pirard, Eric ULiege

in Proceedings SGA2017 (2017, August)

Automated mineralogy has been around for more than thirty years as the reference technique to support process mineralogy and geometallurgical studies. Pioneering techniques such as the QEM-SEM have been ... [more ▼]

Automated mineralogy has been around for more than thirty years as the reference technique to support process mineralogy and geometallurgical studies. Pioneering techniques such as the QEM-SEM have been further improved to benefit from the latest hardware developments in terms of stable, sensitive and efficient imaging. FEG sources, solid state x-ray detectors and almost real-time signal processing have made the most significant contributions in the last decade. A quick overview of existing technologies reveals that further improvement could be gained by merging different imaging modes and using more advanced classification algorithms such as those well known in machine learning and remote sensing. If such algorithms were complemented with hierarchical databases wherein only important economic minerals are listed with their associated probabilities of occurrences, significant improvements could be gained in automated mineral identification. This paper contributes to demonstrate that a real “mineral intelligence” of ores and materials is now within reach [less ▲]

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See detailApplication of Mid-infrared Reflectance Spectroscopy for the Identification of Minerals Present in Oil & Gas/Mining Exploration
Joassin, Marjorie; Pirard, Eric ULiege; Germay, Christophe

in Proceedings SGA2017 (2017, August)

This work aims to develop a new core logging technique based on reflectance spectroscopy in the mid-infrared domain (2.08 to 25 μm). This technique is suitable to analyse the mineralogy of rough surfaces ... [more ▼]

This work aims to develop a new core logging technique based on reflectance spectroscopy in the mid-infrared domain (2.08 to 25 μm). This technique is suitable to analyse the mineralogy of rough surfaces and will be adapted on a rock strength testing machine that scratches the core surface. The FT-IR spectrometer used in this work was tested on a list of minerals which are important in oil & gas and mining exploration. The list contains species of carbonates, halides, phosphates, sulphates, sulphides, tectosilicates and phyllosilicates. Then, a semi-automatic method was developed for mineral identification, mapping and quantification on the rough surfaces. It will be demonstrated that this process is powerful for the estimation of the mineral distribution at the exploration stage. Moreover, as it is non-destructive, low cost and quite fast, it will thus be helpful to extract additional data from the cores in a profitable way. This is critical to improve the resource efficiency, to reduce operational risks and to optimise the production in a sustainable way. These knowledges are the basis of the geometallurgical concept [less ▲]

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See detailInfluence of urban patterns on flooding
Bruwier, Martin ULiege; Mustafa, Ahmed; Aliaga, Daniel et al

in E-proceedings of the 37th IAHR World Congress (2017, August)

The goal of this paper is to identify the respective influence of different characteristics of urban patterns on urban flooding. A set of 2,290 alternate urban patterns was generated randomly using an ... [more ▼]

The goal of this paper is to identify the respective influence of different characteristics of urban patterns on urban flooding. A set of 2,290 alternate urban patterns was generated randomly using an urban generator tool providing the geometry of buildings and their relative location to the ground, over a square area of 1 km². Steady 2-D hydraulic computations were performed for these 2,290 different urban patterns with identical hydraulic boundary conditions. The computational time was reduced by using an anisotropic porosity model. This model uses relatively coarse computational cells; but preserves information from the detailed topographic data through the use of porosity parameters. Based on the computed maps of waterdepths for the 2,290 urban patterns, a sensitivity analysis based on a multiple linear regression was performed to outline the most influential urban characteristics. [less ▲]

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See detailNUMERICAL STUDY OF TURBULENT OSCILLATIONS AROUND A CYLINDER: RANS CAPABILITIES AND SENSITIVITY ANALYSIS
Valero Huerta, Daniel ULiege; Bung, Daniel B.; Erpicum, Sébastien ULiege et al

in Proceedings of the 37th IAHR World Congress (2017, August)

Numerical modelling is commonly used in a large range of environmental fluid mechanics applications. It has become widely accepted and, with increasing computer power, the employed models are increasing ... [more ▼]

Numerical modelling is commonly used in a large range of environmental fluid mechanics applications. It has become widely accepted and, with increasing computer power, the employed models are increasing also in complexity. Reynolds Averaged Navier-Stokes (RANS) equations are the preferred approach for 3D problems, being especially suited for the computation of the mean flow. However, little is known about RANS performance for the fluctuating quantities; being reasonable to expect an impairment in the accuracy. In this study, a simple geometry (cylindrical pier) is subject to different numerical settings in order to assess their effect on the development of the physically based flow instabilities. Mesh refinement has shown to enhance the perturbation growth rate while maximum CFL value has not produced any effect. RNG k-ϵ and k-ω have shown to be more dissipative than k-ϵ. Some advection schemes seem to increase the spurious perturbation converging to the physically based ones. Finally, introducing an experimentally based perturbation at the inlet has proven to speed up the process. [less ▲]

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See detailFLOWCV - AN OPEN-SOURCE TOOLBOX FOR COMPUTER VISION APPLICATIONS IN TURBULENT FLOWS
Bung, Daniel B.; Valero Huerta, Daniel ULiege

in Proceedings of the 37th IAHR World Congress (2017, August)

Despite the continuous advances in numerical modeling methods and the continuous increase of computer power and storage capacities in the last decades, physical modeling remains a common technique for ... [more ▼]

Despite the continuous advances in numerical modeling methods and the continuous increase of computer power and storage capacities in the last decades, physical modeling remains a common technique for evaluation of flow processes. One major advantage of this classical approach is given by the transparency of experiments as the flow can be easily observed in the laboratory and effects of changing boundary conditions may be better understood. Nowadays, the flow is commonly captured in most experiments with means of digital cameras or high-speed cameras to get a better insight and for further analyses after the model test. Besides some well-known techniques, such Particle Image Velocimetry, some new methods can be found in Computer Vision disciplines allowing for more detailed investigation of the images. This paper presents two modules of the new open-source toolbox FlowCV which has been developed to be applied in hydraulic laboratories. The first module is given by a synthetic particle image generator which provides the user with particle images of a predefined motion and turbulence. The second module implements different Optical Flow methods for determination of obstacle movement (here: particle movement). The Farnebäck method, which is presented in this paper, gives dense velocity fields, i.e. velocity data for every image pixel. The Optical Flow results based on the synthetic images are then benchmarked against their predefined particle velocity. It will be shown that even smallest turbulent flow structures are adequately detected. [less ▲]

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See detailEarly eukaryotes: insights from microanalyses of proterozoic microfossils
Cornet, Yohan ULiege; Beghin, Jérémie ULiege; Kabamba Baludikay, Blaise ULiege et al

in Goldschmidt Abstracts, 2017 (2017, August)

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See detailNETPerfTrace – Predicting Internet Path Dynamics and Performance with Machine Learning
Wassermann, Sarah ULiege; Casas, Pedro; Cuvelier, Thibaut ULiege et al

in Proceedings of Big-DAMA ’17 (2017, August)

We study the problem of predicting Internet path changes and path performance using traceroute measurements and machine learning models. Path changes are frequently linked to path inflation and ... [more ▼]

We study the problem of predicting Internet path changes and path performance using traceroute measurements and machine learning models. Path changes are frequently linked to path inflation and performance degradation, therefore the relevance of the problem. We introduce NETPerfTrace, an Internet Path Tracking system to forecast path changes and path latency variations. By relying on decision trees and using empirical distribution-based input features, we show that NETPerfTrace can predict (i) the remaining life time of a path before it actually changes and (ii) the number of path changes in a certain time period with relatively high accuracy. Through extensive evaluation, we demonstrate that NETPerfTrace highly outperforms DTRACK, a previous system with the same prediction targets. NETPerfTrace also offers path performance forecasting capabilities. In particular, our tool can predict path latency metrics, providing a system which can not only predict path changes, but also forecast their impact in terms of performance variations. We release NETPerfTrace as open software to the networking community, as well as all evaluation datasets. [less ▲]

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See detailForeseeing New Control Challenges in Electricity Prosumer Communities
Olivier, Frédéric ULiege; Marulli, Daniele; Ernst, Damien ULiege et al

in Proc. of the 10th Bulk Power Systems Dynamics and Control Symposium – IREP’2017 (2017, August)

This paper is dedicated to electricity prosumer communities, which are groups of people producing, sharing and consuming electricity locally. This paper focuses on building a rigorous mathematical ... [more ▼]

This paper is dedicated to electricity prosumer communities, which are groups of people producing, sharing and consuming electricity locally. This paper focuses on building a rigorous mathematical framework in order to formalise sequen- tial decision making problems that may soon be encountered within electricity prosumer communities. After introducing our formalism, we propose a set of optimisation problems reflecting several types of theoretically optimal behaviours for energy exchanges between prosumers. We then discuss the advantages and disadvantages of centralised and decentralised schemes and provide illustrations of decision making strategies, allowing a prosumer community to generate more distributed electricity (compared to commonly applied strategies) by mitigating over- voltages over a low-voltage feeder. We finally investigate how to design distributed control schemes that may contribute reaching (at least partially) the objectives of the community, by resort in to machine learning techniques to extract, from centralised solution(s), decision making patterns to be applied locally. First empirical results show that, even after a post-processing phase so that it satisfies physical constraints, the learning approach still performs better than predetermined strategies targeting safety first, then cost minimisation. [less ▲]

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See detailEffects of High Solidification Rates on Segregations and Solid Phase Transformations in High Speed Steels
Tchuindjang, Jérôme Tchoufack ULiege; Sinnaeve, Mario; Lecomte-Beckers, Jacqueline ULiege

in MATSUBARA, Yasuhiro; SASAGURI, Nobuya; YAMAMOTO, Kaoru (Eds.) ABRASION 2017 - The 6th International COnference on Abrasion Wear Resistant Alloyed White Cast Iron for Rolling and Pulverizing Mills (2017, August)

High Speed Steels (HSS) represent high alloyed steels that belong to the complex Fe-Cr-C-X system whit X being a strong carbide forming element such as V, Nb, Mo or W. During the solidification of HSS ... [more ▼]

High Speed Steels (HSS) represent high alloyed steels that belong to the complex Fe-Cr-C-X system whit X being a strong carbide forming element such as V, Nb, Mo or W. During the solidification of HSS, segregations corresponding to preferential distribution of elements can occur. Segregations are influenced both by the initial chemical composition and by the casting route, which is the case with conventional spin casting process. But the same phenomenon should also exist with the expanding additive manufacturing techniques that involved higher thermal gradients and higher cooling rates compared to classical processes. The solid phase transformations are controlled by the local concentrations of elements, especially the supersaturation which may exist in certain regions. That is the reason why the segregations inherited from the solidification of the HSS alloys lead to unexpected solid state phase transformations during the ongoing cooling stage. These phase transformations may occur either in the moderate temperature range or subsequently in the lower temperature range which is close to the ambient temperature, as for the martensitic transformation. In the present work a general review of the literature dealing with the fundamentals of solidification is reviewed aiming at justifying the need to search for tools that will be more adapted to simulate or study the microstructures obtained by manufacturing processes such as laser cladding, which refer to conditions far away from equilibrium. The new approach to understanding non-equilibrium structures also requires consideration of related studies with materials that are different from the HSS alloys, such as stainless steels, in order to take advantage of relevant analyzes that have already been achieved in other areas. The study is open, because the scope of the analyses is large and it can be extend to the phase transformations and also to the properties. Some relevant results obtained on two HSS processed by laser cladding are discussed related to the solidification mode and the solidification sequence. [less ▲]

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See detailProbabilistic Reliability Management Approach and Criteria for Power System Short-term Operational Planning
Karangelos, Efthymios ULiege; Wehenkel, Louis ULiege

in Probabilistic Reliability Management Approach and Criteria for Power System Short-term Operational Planning (2017, August)

This paper develops a probabilistic decision making framework for reliability management in the short-term operational planning context. We build upon our recent work, which proposed a probabilistic ... [more ▼]

This paper develops a probabilistic decision making framework for reliability management in the short-term operational planning context. We build upon our recent work, which proposed a probabilistic reliability management approach and criterion (RMAC) for the latest decision making opportunity of real-time system operation. Here, we transpose the RMAC to the preceding problem instance of short-term operational planning, wherein i) risk is aggravated by the uncertainty on power injections and weather conditions, and, ii) the problem scope concerns choosing `strategic' actions (e.g., starting additional generating units, granting outage requests for maintenance, etc.) to facilitate decision making during the forthcoming real-time system operation. To anticipate on the latter, we formalize the notion of a real-time `proxy' as a simplified model of the real-time decision making context, adequately accurate for the purpose of operational planning decision making. Stating a first proposal for such a proxy, we mathematically formulate the RMAC for short-term operational planning as a multi-stage stochastic decision making problem and demonstrate its main features by case studies on a modified version of the single area IEEE RTS-96 system. [less ▲]

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See detailEffects of User IT Capabilities and Organized Big Data Analytics on Competitive Advantage
Kamioka, Taro; Hosoya, Ryuichi; Tapanainen, Tommi ULiege

in Proceedings of the Pacific-Asian Conference on Information Systems (PACIS) (2017, July 20)

In the age of big data, it becomes important to develop capabilities for utilizing information technology (IT) in order to take advantage of the potential of data for business objectives. While users have ... [more ▼]

In the age of big data, it becomes important to develop capabilities for utilizing information technology (IT) in order to take advantage of the potential of data for business objectives. While users have received attention in many ways, we note that the capability literature has focused more on the IT supply side. We argue that user capabilities have moved to an integral position in firm competitive advantage, and call them “User IT Capabilities” (UIC). A survey was conducted to collect data from Japanese organizations, and a total valid sample of 1,170 respondents involved in big data use was extracted. The findings show the effect of UIC on the performance of big data analytics and firm competitiveness, mediated by the variable of organized big data analytics (OBDA). The direct effects are shown to be valid irrespective of company size, although the levels of UIC and OBDA are higher in larger firms. [less ▲]

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See detailEvaluating flexibility and adequacy in future EU power systems: model coupling and long-term forecasting
Quoilin, Sylvain ULiege; Nijs, Wouter; Zucker, Andreas

in Proceedings of the 2017 ECOS Conference (2017, July 09)

There is an increasing need for improving the representation of the power system in energy system models. Recent research has shown that the economic value of each MWh of Variable Renewable Energy (VRE ... [more ▼]

There is an increasing need for improving the representation of the power system in energy system models. Recent research has shown that the economic value of each MWh of Variable Renewable Energy (VRE) declines with growing deployment. There are two main reasons for this: (1) even with limited shares of VRE, there is a reduced utilisation of dispatchable power plants and (2) with high shares of VRE, there can be possible excess electricity that might have to be curtailed in case of insufficient storage capacity. These findings tend to be completely ignored by models with low temporal resolution and high shares of VRE. In this work, we aim at endogenizing the flexibility constraints into long-term planning models (such as the JRC-EU-TIMES model) by taking profit of Dispa-SET, a unit commitment and optimal dispatch model. The main idea is to derive generic functions from Dispa-SET that can be used by JRC-EU-TIMES and all other energy system models. In particular, we evaluate the impact of increased variable renewable power and different configurations of power systems (production, storage, EVs, demand and flexible demand) (1) on the operations of power plants and the different storage options, determining their economics such as operating hours, number of cycles and (2) on the amount of possible excess power (power that has to be curtailed, stored, or transformed. Simulations are run in Dispa-SET for a wide set of exploratory configurations of the power system in Dispa-SET. Then, a statistical analysis of the results is performed to derive generic flexibility functions. An example of the use of such flexiblity function is finally proposed for a long-term simulation in the JRC-EU-TIMES model at the European level, showing a non-negligible impact on the value of VRE, on the utilization of dispatchable generation, and on the required storage capacity. [less ▲]

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See detailConditions, apports et limites du e-tutorat dans un dispositif de formation hybride
Denis, Brigitte ULiege

in Rinaudo, Jean-Luc (Ed.) Symposium du REF - Téléprésence en éducation (2017, July 04)

Un des enjeux de la formation à distance en formation d’adultes est de mettre en place des dispositifs répondant aux besoins des apprenants, respectant des principes andragogiques et procurant un ... [more ▼]

Un des enjeux de la formation à distance en formation d’adultes est de mettre en place des dispositifs répondant aux besoins des apprenants, respectant des principes andragogiques et procurant un environnement de qualité pédagogique (activités, ressources...) et ergonomique. De plus, le tutorat est un facteur primordial dans la mise en œuvre de tels dispositifs. Procurant un sentiment de présence (Jacquinot, 2002), fournissant un soutien (socio-affectif, cognitif, organisationnel...) à l’apprenant, il influence sa persévérance et l’atteinte de ses objectifs. Cette étude traite de la médiation entre e-tuteurs et apprenants dans un dispositif de formation hybride (certificat d'université en gestion de dispositifs techno-pédagogiques innovants). La mise en place de ce dernier a impliqué d’une part un processus d’ingénierie pédagogique incluant une médiatisation des savoirs (ressources) et des activités à distance (consignes, outils de communication, de dépôt de travaux, etc.) et, d’autre part, un processus d’ingénierie tutorale (Rodet, 2010). Les e-tuteurs ont été formés (Denis, 2003) et se sont accordés sur leur profil d’interventions vis-à-vis des apprenants. En outre, des réunions de concertation ont été organisées à plusieurs reprises durant la formation afin de réguler, au besoin, les interventions tutorales. Le principe de ce dispositif est de s’ancrer dans le projet personnel du participant. Il prévoit au fil de la formation des interactions régulières entre un e-tuteur et son (ses) tutoré(s) sur base d’un carnet de route (Roadbook) hebdomadaire complété en ligne. Ces interactions ont généralement lieu par courriel ou via l’annotation de documents partagés. Par ailleurs, les tutorés reçoivent également de la part des formateurs des feedback écrits personnalisés au fur et à mesure de la rentrée de leurs travaux. Ces derniers, ainsi que leurs réflexions tout au long du processus de formation, sont compilés dans leur Roadbook. Les conditions, apports et limites du e-tutorat dans ce dispositif seront appréhendées à partir de l’analyse des Roadbooks des apprenants et d’interviews de l’un d’entre eux ainsi que des e-tuteurs. [less ▲]

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See detailBenchmarking the Environmental Impact of Green and Traditional Masonry Wall Constructions
Gauvreau-Lemelin, Corinne; Attia, Shady ULiege

in Brotas, Luisa; Roaf, Susan; Fergus, Nicol (Eds.) Passive low energy architecture design to thrive (2017, July 03)

In Belgium, the most common approach for nearly Zero Energy Buildings is to comply with the locally modified version of the German Passive House (PH) Standard that requires a very low conductivity of ... [more ▼]

In Belgium, the most common approach for nearly Zero Energy Buildings is to comply with the locally modified version of the German Passive House (PH) Standard that requires a very low conductivity of exterior walls. The conventional PH brick constructions are dominated by building materials with high environmental impact including concrete blocks, firebrick and petrochemical insulation materials that produce a great amount of greenhouse gases (GHG). Moreover, there are very few studies that assessed the holistic environmental impact of conventional wall compositions against ecological wall compositions. Therefore, this research compares a traditional Belgian representative wall against a hemp block wall, according to the PH standard. The environmental impact of each wall is quantified through a life cycle assessment. The final results indicate that the hemp wall reinforced with a wood skeleton has a much lower impact on the environment: up to 60% reduction on total primary energy, 72% on climate changes, 93% on eutrophication, 61 % on ozone layer depletion and 74% on acidification. Future work may refine the assessment process. The study provides novel and significant findings that can inform building owners, architects and contractors and encourage them to choose environmentally friendly masonry wall compositions. [less ▲]

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See detailEffects of void fraction and heat transfer correlations in a charge-sensitive ORC model – a comparison with experimental data
Dickes, Rémi ULiege

in Proceedings of ECOS 2017 (2017, July 02)

In order to properly evaluate the off-design performance of an ORC unit, it is important to use simulation tools that minimize the number of assumptions regarding the system state. To avoid imposing the ... [more ▼]

In order to properly evaluate the off-design performance of an ORC unit, it is important to use simulation tools that minimize the number of assumptions regarding the system state. To avoid imposing the condenser subcooling (or any other equivalent state variable), the ORC model should account for the mass repartition of working fluid through the unit in function of the operating conditions. Among the various components constituting ORC power systems, the proper modelling of the mass of working fluid enclosed in the heat exchangers is of primary importance. The goal of this work is to develop such a reliable charge-sensitive ORC model. To this end, a 2kWe recuperative ORC system is used as case study and experimental measurements are used as reference dataset. The ORC system features two brazed plate heat exchangers and one fin coil condenser. For these three heat exchangers, a large set of empirical correlations is investigated in order to evaluate both the fluids void fractions and their convective heat transfer coefficients. By comparing the models predictions with the experimental data, the study highlights the limitations of existing correlations and investigates three different correction methods to improve them. Ultimately, the analysis compares nine models of brazed plate heat exchangers, two models of condenser, three correction methods for improving the heat transfer correlations and four void fraction methods. Accounting for every combination possible, 288 different models of the ORC are compared for predicting both the heat exchangers thermal performance and the total mass enclosed in the ORC unit. Out of this study, the best modelling approach is identified and details of its charge inventory predictions are presented. [less ▲]

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See detailTesting the discrimination hypothesis for female self employment migrants in the UK
Constantinidis, Christina ULiege; Fletcher, Denise; Joxhe, Majlinda

in IAFFE (Ed.) Books of Abstracts (2017, July 01)

We propose a comparative analysis of migrants in both sectors (employment and self-employment) exploring the gender earning discrimination hypothesis. Using individual micro data from the British ... [more ▼]

We propose a comparative analysis of migrants in both sectors (employment and self-employment) exploring the gender earning discrimination hypothesis. Using individual micro data from the British Household Panel Survey (1991-2008), we estimate wage equations for employed and self-employed migrants and find that, contrary to our expectations, the average earnings gap in self-employment is almost double compared to the employment sector. This finding reveals that self-employment leads migrant women to an even more precarious and vulnerable position in terms of financial means and economic power. In addition, we explore the determinants of these gaps using the econometric procedure of the decomposition (the Blinder-Oaxaca) model. We find that the variables that explain the gender gap in the employment sector are mostly observable individual characteristics like education or migration duration, confirming the human capital theory, whereas in the self-employment sector, this gap is more due to unobservable individual characteristics. Through our work, we show that including the gender perspective into migration analysis has implications for policy makers enabling them to evaluate these processes from a more social (rather than individualistic) dimension. [less ▲]

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See detailAggregation of flexible domestic heat pumps for the provision of reserve in power systems
Georges, Emeline ULiege; Quoilin, Sylvain ULiege; Mathieu, Sébastien ULiege et al

in Proceedings of the 30th International Conference on Efficiency, Cost, Optimisation, Simulation and Environmental Impact of Energy Systems. (2017, July)

The integration of renewable energy sources in the electricity production mix has an important impact on the management of the electricity grid, due to their intermittency. In particular, there is a ... [more ▼]

The integration of renewable energy sources in the electricity production mix has an important impact on the management of the electricity grid, due to their intermittency. In particular, there is a rising need for flexibility, both on the supply and demand sides. This paper assesses the amount of flexibility that could be reserved from a set of flexible residential heat pumps in a given geographical area. It addresses the problem of a load aggregator controlling a set of heat pumps used to provide both space-heating and domestic hot water. The flexibility of the heat pumps is unlocked in order to reduce electricity procurement costs in the day-ahead electricity market, while ensuring the provision of a predefined amount of reserve for real-time grid management. The objective of the paper is two-fold. On the one hand, an aggregation method of large sets of heat pumps based on physics-based models and random sampling techniques is proposed. On the other hand, a combined optimization problem is formulated to determine both the optimal electricity demand profile to be bought on the day-ahead market and the cost associated to the reservation of a defined amount of power. The method is applied to a set of 40000 residential heat pumps in Belgian houses. Results show that these houses can provide up to 100MW of upward reserve for 50% of the current costs. The provision of downward reserve at competitive cost is hampered by significant overconsumption. [less ▲]

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See detailÉvaluation de la capacité du Modèle Atmosphérique Régional (MAR) à simuler la saison des pluies en Afrique Intertropicale
Doutreloup, Sébastien ULiege; Wyard, Coraline ULiege; Belleflamme, Alexandre ULiege et al

in Dahech, Salem; Charfi, Sami (Eds.) Actes du XXXe colloque de l'Association Internationale de Climatologie : CLIMAT, VILLE ET ENVIRONNEMENT (2017, July)

In Intertropical Africa, climate is essentially characterized by the amount of precipitation and its annual regime. These precipitations and their evolution during the period 1970-1999 are simulated ... [more ▼]

In Intertropical Africa, climate is essentially characterized by the amount of precipitation and its annual regime. These precipitations and their evolution during the period 1970-1999 are simulated thanks to the Regional Atmospheric Model (MAR), developed at the ULg, and forced by the NCEP1 reanalyses and by the outputs of three global models (GCM) of the CMIP5 database. These MAR simulations are compared to the gridded data of the Climate Research Unit (CRU). It is clear from our investigations that the simulation of the MAR model forced by the NCEP1 reanalyses is better reproducing the quantities as well as the annual rainfall regime in the semi-arid regions than in equatorial regions. On the other hand, simulations of the MAR forced by the outputs of the GCMs are globally unsatisfactory throughout the intertropical domain in terms of quantities as well as the seasonality of precipitation. [less ▲]

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See detailReinforcement Learning for Electric Power System Decision and Control: Past Considerations and Perspectives
Glavic, Mevludin ULiege; Fonteneau, Raphaël ULiege; Ernst, Damien ULiege

in The 20th World Congress of the International Federation of Automatic Control, Toulouse 9-14 July 2017 (2017, July)

In this paper, we review past (including very recent) research considerations in using reinforcement learning (RL) to solve electric power system decision and control problems. The RL considerations are ... [more ▼]

In this paper, we review past (including very recent) research considerations in using reinforcement learning (RL) to solve electric power system decision and control problems. The RL considerations are reviewed in terms of speci c electric power system problems, type of control and RL method used. We also provide observations about past considerations based on a comprehensive review of available publications. The review reveals the RL is considered as viable solutions to many decision and control problems across di erent time scales and electric power system states. Furthermore, we analyse the perspectives of RL approaches in light of the emergence of new-generation, communications, and instrumentation technologies currently in use, or available for future use, in power systems. The perspectives are also analysed in terms of recent breakthroughs in RL algorithms (Safe RL, Deep RL and path integral control for RL) and other, not previously considered, problems for RL considerations (most notably restorative, emergency controls together with so-called system integrity protection schemes, fusion with existing robust controls, and combining preventive and emergency control). [less ▲]

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See detailcopycat: Testing Differential Treatment of New Transport Protocols in the Wild
Edeline, Korian ULiege; Kühlewind, Mirja; Trammell, Brian et al

in Applied Networking Research Workshop (2017, July)

Recent years have seen the development of multiple transport solutions to address the ossification of TCP in the Internet, and to ease transport-layer extensibility and deployability. Recent approaches ... [more ▼]

Recent years have seen the development of multiple transport solutions to address the ossification of TCP in the Internet, and to ease transport-layer extensibility and deployability. Recent approaches, such as PLUS and Google's QUIC, introduce an upper transport layer atop UDP; their deployment therefore relies on UDP not being disadvantaged with respect to TCP by the Internet. This paper introduces copycat, a generic transport protocol testing tool that highlights differential treatment by the path in terms of connectivity and QoS between TCP and a non-TCP transport protocol. copycat generates TCP-shaped traffic with custom headers, and compares its performance in terms of loss and delay with TCP. We present a proof-of-concept case study (UDP vs. TCP) in order to answer questions about the deployability of current transport evolution approaches, and demonstrate the extent of copycat's capabilities and possible applications. While the vast majority of UDP impairments are found to be access-network linked, and subtle impairment is rare, middleboxes might adapt to new protocols that would then perform differently in the wild compared to early deployments or controlled environment testing. [less ▲]

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See detailRECONSTRUCTION DE L'ÉVOLUTION DU RAYONNEMENT SOLAIRE REÇU EN SURFACE EN EUROPE OCCIDENTALE SUR LA PÉRIODE 1900-2014 À L'AIDE DU MODÈLE ATMOSPHÉRIQUE RÉGIONAL MAR
Wyard, Coraline ULiege; Fettweis, Xavier ULiege; Belleflamme, Alexandre ULiege et al

in Dahech, Salem; Charfi, Sami (Eds.) Actes du XXXe colloque de l'Association Internationale de Climatologie : Climat, ville et environnement (2017, July)

Many studies show that the surface solar radiation has underwent large variations over the second half of the 20th century as a result of variations in cloud cover and aerosol loading in the atmosphere ... [more ▼]

Many studies show that the surface solar radiation has underwent large variations over the second half of the 20th century as a result of variations in cloud cover and aerosol loading in the atmosphere. However, it is difficult to build strong conclusions before the 1950' because of the observations scarcity. The evolution of the surface solar radiation has been reconstructed over 1900-2014 using the regional model MAR (« Modèle Atmosphérique Régional ») in Belgium. Boundary conditions were provided by four reanalysis products : the ERA-interim (1979-2014) completed by the ERA40 (1958-1978), the NCEP/NCAR-v1 (1948-2014), the ERA-20C (1900-2010) and the 20CRV2C (1900-2010). Results show that the reanalyses can generate divergent trends while they assimilate observations and are supposed to represent the same climate. [less ▲]

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See detailDevelopment of an Ericsson Heat Engine for biomass Combined Heat and Power
Oudkerk, Jean-François ULiege; Lemort, Vincent ULiege

in Proceedings of the 30th International conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems (ECOS) (2017, July)

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See detailÉvolution de l'enneigement moyen dans les Alpes au cours du 20e siècle à l'aide du modèle atmosphérique régional MAR
Belleflamme, Alexandre ULiege; Wyard, Coraline ULiege; Doutreloup, Sébastien ULiege et al

in Dahech, Salem; Charfi, Sami (Eds.) Actes du XXXème colloque de l'Association Internationale de Climatologie - Climat, ville et environnement (2017, July)

The evolution of the snow height over the Alps can strongly impact tourism, but also the water availability of the region. In this study, we have reproduced the evolution of the climate in the Alps over ... [more ▼]

The evolution of the snow height over the Alps can strongly impact tourism, but also the water availability of the region. In this study, we have reproduced the evolution of the climate in the Alps over the 20th century with the help of the regional atmospheric model MAR forced by three reanalyses (ERA-20C, NCEP/NCAR, and ERA-Interim). MAR shows that the snow height has increased since the beginning of the 20th century, first only at higher altitudes, then also at lower levels, before knowing a strong and abrupt decrease between 1985 and 1990. This evolution, which is consistent with observations given in the literature, is directly linked with the trends of NAO and AO. In fact, the atmospheric circulation changes highlighted by NAO and AO induce temperature and precipitation changes that directly determine the snow height in the Alps. [less ▲]

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See detailImpact of Diesel generator limitations in the robust sizing of isolated hybrid Microgrids including PV and batteries
Balderrama Subieta, Sergio Luis ULiege; Canedo, Walter; Lemort, Vincent ULiege et al

in Proceedings of ECOS 2016 - the 30th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems (2017, July)

The recent developments in PV and Lion-ion batteries along with the maturity of gensets technology to provide energy to isolated systems has fostered the use of hybrid micro-grids for rural ... [more ▼]

The recent developments in PV and Lion-ion batteries along with the maturity of gensets technology to provide energy to isolated systems has fostered the use of hybrid micro-grids for rural electrification. In this context, the optimal coupling of different technologies and the minimization of the cost to the final consumer are the objects of a number of previous researches. However, the approach usually relies on deterministic linear programming optimizations (LP), which do not allow to model certain non-linearities and limitations of the components. This paper aims at filling this gap by proposing an optimization of such system, with a detailed representation of each component. The case study of an isolated village (Las Misiones, Bolivia) with a peak electricity consumption of 9.2 MW is analyzed. The considered system comprises a diesel generator; a PV array and Li-Ion batteries whose nominal capacities should be optimized. A robust optimization tool is first proposed with an LP formulation and the net present cost as objective function. The basic model is then modified to take into account more complex operating characteristics of a gen-set operating in part-load. To that aim, the LP problem is changed into a mixed integer linear programing formulation. Results indicate that the more detailed constraints influence the final design of the system and negatively impact the total cost. [less ▲]

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See detailHydro-mechanical modelling of a coalbed methane production well via a dual-porosity approach
Bertrand, François ULiege; Buzzi, Olivier; Collin, Frédéric ULiege

in Book of Abstracts: 6th International Conference on Coupled THMC Processes in Geosystems (2017, July)

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See detailPerformance of gridded and along-track altimetry products in eddy manifestation in the Western Mediterranean
Karimova, Svetlana ULiege

in Proc. IGARSS 2017 (2017, July)

In the present work, we assess the performance of different sea level anomaly (SLA) products in manifesting mesoscale eddies of the Western Mediterranean. As ‘ground truth’ in this study we use eddy ... [more ▼]

In the present work, we assess the performance of different sea level anomaly (SLA) products in manifesting mesoscale eddies of the Western Mediterranean. As ‘ground truth’ in this study we use eddy manifestations found in sea surface temperature (SST) fields of the region of interest. Co-location of eddies found in thermal imagery with closed contours of the fields of SLA showed that only anticyclonic eddies exceeding approx. 70 km in diameter can be more or less sustainably manifested in the fields of SLA and its derivatives. Detection of cyclonic eddies, presumably due to their small spatial and temporal scales and non-geostrophic nature, is problematic. A preliminary analysis of the along-track SLA data seemed to support the conclusions made for the gridded SLA products. Application of a vector geometry approach to eddy detection, in its turn, seems to lead to an excess of large cyclonic eddies and thus biasing resulting mesoscale eddy statistics. [less ▲]

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See detailAn approach to automated spiral eddy detection in SAR images
Karimova, Svetlana ULiege

in Proc. IGARSS 2017 (2017, July)

Satellite derived synthetic aperture radar (SAR) imagery frequently contains manifestations of coherent structures (eddies) of different spatial scale. However, due to strong dependence of SAR imaging on ... [more ▼]

Satellite derived synthetic aperture radar (SAR) imagery frequently contains manifestations of coherent structures (eddies) of different spatial scale. However, due to strong dependence of SAR imaging on the near-surface wind speed during the SAR acquisition, such eddy manifestations can be at great extent masked by the signatures of other, mostly atmospheric, phenomena. In the present paper, we propose a method for an automated detection of eddy manifestations visualized by surfactant films presenting on the water surface. The method proposed based on sequential application of image transformations aimed at masking atmospheric phenomena and highlighting the surfactant filaments manifesting eddies in SAR images. Thus extracted dark patches are being fitted by circles, and close co-location of several such circles would be considered an eddy manifestation. [less ▲]

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See detailPractical Trajectories of Parametric Tools in Small and Medium Architectural Firms
Stals, Adeline ULiege; Elsen, Catherine ULiege; Jancart, Sylvie ULiege

in Future trajectories for computation in design (2017, July)

Initially used as an extension of hand-drawing tools, digital design tools and moreover parametric ones are nowadays deeply modifying the architectural design process. Big offices with star-architects ... [more ▼]

Initially used as an extension of hand-drawing tools, digital design tools and moreover parametric ones are nowadays deeply modifying the architectural design process. Big offices with star-architects were able to adopt these tools but most architects working in a small office are still trying to cope with these parametric design tools. Several questions arise in this regard: what digital tools do architects usually use? Do they express interest for new technologies and software such as parametric ones? What is their understanding of the term “parametric architecture”? Why is this kind of tools still not largely adopted? Going through the results of an online survey, this paper first discusses the meaning of parametric design for architects. The contribution then analyzes the Belgian case regrouping mostly small and medium offices. It reflects particularly on the way architects do or do not implement these new digital tools in their workflows, and it sheds light on the fact that parametric tools also have the potential to free the creativity of SME’s. [less ▲]

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See detailComparison of a dynamic model and experimental results of a residential heat pump with vapor injection and variable speed scroll compressor
Dechesne, Bertrand ULiege; Gendebien, Samuel ULiege; Lemort, Vincent ULiege et al

in PROCEEDINGS OF ECOS 2017 (2017, July)

The first part of this paper presents a Modelica-based dynamic model of the system. Finite-volume models are used for the heat exchangers and the evaporator model takes into account frost formation. A ... [more ▼]

The first part of this paper presents a Modelica-based dynamic model of the system. Finite-volume models are used for the heat exchangers and the evaporator model takes into account frost formation. A thermodynamic model of the vapor injection scroll compressor is developed using empirical correlations for the volumetric efficiency, isentropic efficiency and the ratio between the injection and suction mass flow rate. The second part presents experimental results of a vapor injection and variable speed scroll compressor air to water residential heat pump. The unit is a 10kW residential system working with R410a as working fluid and capable of providing floor heating and domestic hot water. It was tested in a controlled environment in order to achieve a wide range of outdoor, including frosting conditions, and indoor conditions. The model predictions and experimental results are compared in order to validate the component models in steady state. The experimental investigations showed that there is room for improvement on the control side of the system and the developed model can be used in order to develop model based control of the injection and outdoor electronic expansion valves. [less ▲]

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See detailPolynomial state-space model decoupling for the identification of hysteretic systems
Esfahani, Alireza; Dreesen, Philippe; Tiels, Koen et al

in Proceedings of the IFAC World Congress (2017, July)

Hysteresis is a nonlinear effect that shows up in a wide variety of engineering and scientific fields. The identification of hysteretic systems from input-output data is an important but challenging ... [more ▼]

Hysteresis is a nonlinear effect that shows up in a wide variety of engineering and scientific fields. The identification of hysteretic systems from input-output data is an important but challenging question, which has been studied by using both tailored parametric white-box identification methods as by using black-box identification methods. The white-box modeling approach is by far the most common in identifying hysteretic systems, and has the advantage of resulting into an interpretable model, but it requires to be adjusted to a specific hysteresis model. A black-box approach can be used more universally, but results in models containing many parameters that cannot easily be interpreted. In the current paper, we propose a two-step identification procedure that combines the best of the two approaches.We employ the Bouc-Wen hysteretic model to generate data that is used for identification. The system is identified using a black-box polynomial nonlinear state-space identification procedure. We reduce the number of parameters in this model by applying a polynomial decoupling method that results in a more parsimonious representation. We compare the full black-box model with the decoupled model and show that the proposed method results in a comparable performance, while significantly reducing the number of parameters. [less ▲]

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See detailDiversity and biogeography of microorganisms in microbial mats of Antarctic lakes
Wilmotte, Annick ULiege; Durieu, Benoit ULiege; Lara, Yannick ULiege et al

in Van de Putte, Anton (Ed.) Book of abstracts: XIIth SCAR Biology Symposium, Leuven, Belgium, 10-14 July 2017. (2017, July)

The BelSPO project CCAMBIO aims to study the biogeographical distribution of microorganisms (bacteria, cyanobacteria, microeukaryotes) in lacustrine microbial mats using a combination of techniques ... [more ▼]

The BelSPO project CCAMBIO aims to study the biogeographical distribution of microorganisms (bacteria, cyanobacteria, microeukaryotes) in lacustrine microbial mats using a combination of techniques including microscopic observations, strain isolation and genetic characterisation, and molecular diversity assessments using Next Generation Sequencing of environmental DNA. The samples were collected in different Antarctic and sub-Antarctic biogeographical regions. [less ▲]

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See detailAssessment of AquaCrop for winter wheat using satellite derived fCover data
Mohamed Sallah, Abdoul-Hamid ULiege; Wellens, Joost ULiege; Tychon, Bernard ULiege et al

in 9th International Workshop on the Analysis of Multitemporal Remote Sensing Images (2017, June 29)

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See detailA Discussion on the Advancement of Blade Tip Timing Data Processing
Kharyton, Vsevolod; Dimitriadis, Grigorios ULiege; Defise, Colin

in Proceedings of the Turbomachinery Technical Conference & Exposition, TURBO EXPO 2017 (2017, June 29)

The Blade Tip Timing method (BTT) is a well-known approach permitting individual blade vibration behavior characterization. The technique is becoming increasingly popular among turbomachinery vibration ... [more ▼]

The Blade Tip Timing method (BTT) is a well-known approach permitting individual blade vibration behavior characterization. The technique is becoming increasingly popular among turbomachinery vibration specialists. Its advantages include its non-intrusive nature and its capability of being used for long-term monitoring, both in on-line and off-line analysis. However, the main drawback of BTT is frequency aliasing. Frequency aliasing effects in tip timing can be reduced by means of the application of different methods from digital signal analysis that can exploit the non-uniform nature of the data sampled by BTT. This non-uniformity is due to the fact that an optimization of the circumferential distribution of BTT probes is usually required in order to improve the data quality for targeted modes of blade vibration and/or orders of excitation. The BTT data analysis methods considered in this study are the non-uniform Fourier transform, the minimum variance spectrum estimator approach, a multi-channel technique using in-between samples interpolation, the Lombe-Scargle periodogram and an iterative variable threshold procedure. These methods will be applied to measured data representing quite a large scope of events occurring during gas-turbine compressor operation, e.g. synchronous engine order resonance crossing, rotating stall, suspected limit-cycle oscillations. Finally, the frequency estimates obtained from all these methods will be summarized. [less ▲]

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See detailPotato monitoring in Belgium with "watchITgrow"
Piccard, Isabelle; Gobin, Anne; Wellens, Joost ULiege et al

in 19th International Workshop on the Analysis of Multitemporal Remote Sensing Images (2017, June 29)

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See detailDynamic stall onset variation with reduced frequency for three stall mechanisms
Boutet, Johan ULiege; Dimitriadis, Grigorios ULiege; Amandolese, Xavier

in Proceedings of the International Forum on Aeroelasticity and Structural Dynamics, IFASD 2017 (2017, June 27)

A set of unsteady aerodynamic load measurement is performed on three oscillating airfoils with distinct stall mechanisms: a flat plate, a NACA0012, and a NACA0018. The airfoils are forced to oscillate in ... [more ▼]

A set of unsteady aerodynamic load measurement is performed on three oscillating airfoils with distinct stall mechanisms: a flat plate, a NACA0012, and a NACA0018. The airfoils are forced to oscillate in pitch around the stall angle of attack with prescribed frequency and amplitude. A criterion proposed by Sheng et al. is used to locate the onset of the flow separation process associated with dynamic stall, and quantify its variation with an equivalent reduced pitch rate. The validity of this criterion is tested for the three airfoils at low Reynolds number, Re = 2 × 10^4. Results are compared with the experimental data obtained by Sheng et al. at higher Reynolds number of Re = 1.5 × 10^6. [less ▲]

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See detailResearch on Fast Aeroelastic Modeling Methods for the Transonic Regime
Güner, Hüseyin ULiege; Dimitriadis, Grigorios ULiege; Terrapon, Vincent ULiege

in Proceedings of the International Forum on Aeroelasticity and Structural Dynamics, IFASD 2017 (2017, June 27)

Two methods for modeling unsteady transonic flows at low computational cost are presented as a first step towards a fast and accurate aeroelastic calculation methodology for the preliminary design stage ... [more ▼]

Two methods for modeling unsteady transonic flows at low computational cost are presented as a first step towards a fast and accurate aeroelastic calculation methodology for the preliminary design stage in the transonic flow regime. The first approach corresponds to a quasi-steady approximation based on few steady simulations that is improved through the use of an unsteady filter. The second approach is based on the interpolation of dynamic modes between solutions at different frequencies that are obtained either from Dynamic Mode Decomposition (DMD) of unsteady simulations or directly from Harmonic Balance (HB) simulations. The two methods are illustrated in the case of a pitching airfoil in the transonic regime. Results show that the first method is fast and provides a first approximation of the unsteady dynamics. The computational cost of the second approach is higher, but the method provides better results in predicting aerodynamic forces and shock motion for a large range of reduced frequencies. [less ▲]

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See detailLimit cycle oscillations of cantilever rectangular flat plates in a wind tunnel
Giannelis, Nicholas; Vio, Gareth A.; Dimitriadis, Grigorios ULiege

in Proceedings of the International Forum on Aeroelasticity and Structural Dynamics, IFASD 2017 (2017, June 27)

A closed form state-space model of the nonlinear aeroelastic response of thin cantilevered flat plates is derived using a combination of Von Karman thin plate theory and a linearized continuous time ... [more ▼]

A closed form state-space model of the nonlinear aeroelastic response of thin cantilevered flat plates is derived using a combination of Von Karman thin plate theory and a linearized continuous time vortex lattice aerodynamic model. The modal-based model is solved for the amplitude and period of the limit cycles of the flat plates using numerical continuation. The resulting predictions are compared to experimental data obtained from identical flat plates in the wind tunnel. It is shown that the aeroelastic model predicts the linear flutter conditions and nonlinear response of the plates with reasonable accuracy, although the predicted limit cycle amplitude variation with airspeed is different to the one measured experimentally due to unmodelled physics. [less ▲]

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See detailFreeplay-induced limit cycle oscillation mitigation using linear and nonlinear tuned vibration absorbers
Verstraelen, Edouard ULiege; Kerschen, Gaëtan ULiege; Dimitriadis, Grigorios ULiege

in Proceeding of the IFASD 2017 Conference (2017, June 27)

Structural nonlinearities such as freeplay in control surface bearings and actuators or in connections between wings and external payloads sometimes lead to aeroelastic limit cycle oscillations at ... [more ▼]

Structural nonlinearities such as freeplay in control surface bearings and actuators or in connections between wings and external payloads sometimes lead to aeroelastic limit cycle oscillations at airspeeds lower than the linear flutter speed of the aircraft. In parallel, numerous studies demonstrated the potential of linear and nonlinear tuned vibration absorbers to increase the flutter speed of linear and continuously hardening aeroelastic systems such as two-degree- of-freedom wings or long span bridges. In this work, the effect of linear and nonlinear tuned vibration absorbers is studied on a wing with pitch plunge and control surface deflection degrees of freedom and with freeplay in pitch. Depending on the tuning of the linear absorber, the linear flutter speed of the system can be increased by 10% or the onset of limit cycle oscillations due to the freeplay can be delayed by 7.7% and their amplitude can be significantly decreased. The addition of cubic hardening forces on the absorber can further decrease the limit cycle amplitude in a limited airspeed range at the cost of an increase in limit cycle amplitude in another airspeed range. Conversely, the addition of a freeplay hardening force on the absorber can decrease the limit cycle amplitude without any detrimental effect. [less ▲]

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See detailSystem Eigenvalue Identification Of Mistuned Bladed Disks Using Least-Squares Complex Frequency-Domain Method
Huang, Yuan; Kielb, Robert E.; Li, Jing et al

in Proceeding of the Turbomachinery Technical Conference & Exposition TURBO EXPO 2017 (2017, June 26)

This paper presents the results from a research effort on eigenvalue identification of mistuned bladed rotor systems using the Least-Squares Complex Frequency-Domain (LSCF) modal parameter estimator. The ... [more ▼]

This paper presents the results from a research effort on eigenvalue identification of mistuned bladed rotor systems using the Least-Squares Complex Frequency-Domain (LSCF) modal parameter estimator. The LSCF models the frequency response function (FRF) obtained from a vibration test using a matrix-fraction description and obtains the coefficients of the common denominator polynomial by minimizing the least squares error of the fit between the FRF and the model. System frequency and damping information is obtained from the roots of the denominator; a stabilization diagram is used to separate physical from mathematical poles. The LSCF estimator is known for its good performance when separating closely spaced modes, but few quantitative analyses have focused on the sensitivity of the identification with respect to mode concentration. In this study, the LSCF estimator is applied on both computational and experimental forced responses of an embedded compressor rotor in a three-stage axial research compressor. the LSCF estimator is first applied to computational FRF data obtained from a mistuned first-torsion (1T) forced response prediction using FMM (Fundamental Mistuning Model) and is shown to be able to identify the eigenvalues with high accuracy. Then the first chordwise bending (1CWB) computational FRF data is considered with varied mode concentration by varying the mistuning standard deviation. These cases are analyzed using LSCF and a sensitivity algorithm is developed to evaluate the influence of the mode spacing on eigenvalue identification. Finally, the experimental FRF data from this rotor blisk is analyzed using the LSCF estimator. For the dominant modes, the identified frequency and damping values compare well with the computational values. [less ▲]

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See detailFire resistance of concrete slabs acting in compressive membrane action
Molkens, Tom; Gernay, Thomas ULiege; Caspeele, Robby

in Nigro, Emidio; Bilotta, Antonio (Eds.) Proceedings of the 2nd International Fire Safety Symposium - IFireSS 2017 (2017, June 08)

In building renovation, the real behaviour of reinforced concrete slabs cannot always be explained by the bending theory according to classical structural mechanics. Indeed, the bearing capacity, as ... [more ▼]

In building renovation, the real behaviour of reinforced concrete slabs cannot always be explained by the bending theory according to classical structural mechanics. Indeed, the bearing capacity, as assessed for instance by a loading test, sometimes appears to be much higher than what would be expected. This phenomenon may be caused by the activation of an arch-effect or so-called compressive membrane action (CMA) which can develop even with small vertical deformations. For a slab which is completely restrained, the presence of reinforcement becomes of lesser importance when this phenomenon is activated (except for end fields). Hence, for fire resistance purposes, it can be discussed whether reinforcement and concrete cover has a smaller influence on the bearing capacity for slabs subjected to fire which exhibit a significant concrete compressive membrane behaviour. This paper presents a loading test performed on a real concrete building which highlighted the development of CMA as the load bearing mode. It then proposes a strategy to evaluate the behaviour resulting from the development of CMA in reinforced concrete slabs at ambient and at elevated temperature based on numerical modelling. The numerical analyses are performed with the finite element software SAFIR® using a strip of layered shell elements. A plastic-damage constitutive model with an explicit transient creep formulation is used to capture the concrete behaviour at elevated temperature. [less ▲]

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See detailFire risk assessment of multi-story buildings based on fragility analysis
Gernay, Thomas ULiege; Elhami Khorasani, Negar; Garlock, Maria

in Nigro, Emidio; Bilotta, Antonio (Eds.) Proceedings of the 2nd International Fire Safety Symposium - IFireSS 2017 (2017, June 07)

Recent efforts aim at assessing the fire performance of structures in a probabilistic framework. But there is still no well-established method to quantify the reliability of entire buildings. Previous ... [more ▼]

Recent efforts aim at assessing the fire performance of structures in a probabilistic framework. But there is still no well-established method to quantify the reliability of entire buildings. Previous works focused on isolated structural members, therefore not allowing for a determination of the global safety level of buildings. Here, a new methodology is developed to quantify the reliability of buildings in fire. The methodology uses Monte Carlo simulations for constructing fragility functions associated with different fire breakout locations in a building, then combines the functions to characterize the overall building conditional probability of failure, and finally incorporates the probabilistic models for intensity measure and fire occurrence likelihood. The methodology is applied to multi-story steel buildings. This work addresses fire reliability at the building scale, and therefore is useful for standardizing safety level as well as for evaluating community resilience. [less ▲]

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See detailImparting Knowledge in Humanities. About Some Practices of Scientific Blogging on Hypothèses
Mayeur, Ingrid ULiege

in Chan, Leslie; Loizides, Fernando (Eds.) Expanding Perspectives on Open Science: Communities, Cultures and Diversity in Concepts and Practices (2017, June 06)

My contribution aims to explain how a platform of electronic publishing such as OpenEdition might reach a larger public outside the academic sphere, and contribute to the revealing of research in the ... [more ▼]

My contribution aims to explain how a platform of electronic publishing such as OpenEdition might reach a larger public outside the academic sphere, and contribute to the revealing of research in the Humanities to civil society. Practices of academic blogging have expanded since the 2000's. Its potential as a vulgarization tool was acknowledged early. However, most initiatives in scientific blogging are concerned with the field of STM (Science, Technology, and Medicine). A quick overview of the classical literature about vulgarization shows that a great deal of attention is being paid to STM. As such, I propose to examine what the practices of communication are towards civil society in Humanities through Hypothèses, the blogging platform of OpenEdition. [less ▲]

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See detailContributions to handle maximum size constraints in density-based topology optimization
Fernandez Sanchez, Eduardo Felipe ULiege; Collet, Maxime ULiege; Bauduin, Simon ULiege et al

in Fiebig, Sierk; Bletzinger, Kai-Uwe; Maute, Kurt (Eds.) et al Advances in Structural and Multidisciplinary Optimization (2017, June 05)

The maximum size formulation in topology optimization restricts the amount of material within a test region in each point in the design domain, leading to a highly constrained problem. In this work the ... [more ▼]

The maximum size formulation in topology optimization restricts the amount of material within a test region in each point in the design domain, leading to a highly constrained problem. In this work the local constraints are aggregated into a single one by p-mean and p-norm functions, classically used for stress constraints. Moreover, a new test region is investigated which is a ring instead of the classical circle around the element. These developments were implemented for compliance minimization with the MBB beam test case. Results indicate that p-mean performs better in the maximum size field than p-norm, because it underestimates the most violated constraint. This gives some relaxation to the problem that allows stiffer connections. Similar effect has been observed for the ring-shaped region which reduces the amount of holes that are introduced in the structure, specially in the connection of solid members. In addition, it is shown that the maximum size formulation allows the definition of the minimum gap between solid members which gives designers more control over the geometry. The developments have been illustrated and validated with compliance minimization tests of 2D-domains. [less ▲]

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See detailConstraints on Landslide-Climate Research Imposed by the Reality of Fieldwork in Central Africa
Monsieurs, Elise ULiege; Kirschbaum, Dalia B.; Thiery, Wim et al

in Association of Environmental and Engineering Geologists (CC BY-NC 4.0) (2017, June 05)

Climate change is reported to be ‘very likely’ associated with an increasing trend in extreme rainfall intensity over the tropics. Its impact on the timing of landslide initiation however remains poorly ... [more ▼]

Climate change is reported to be ‘very likely’ associated with an increasing trend in extreme rainfall intensity over the tropics. Its impact on the timing of landslide initiation however remains poorly understood. Central Africa, located in the tropics, has repeatedly been highlighted as lacking landslide catalogs and landslide-climate studies. We present a research approach, adapted to the data-poor context of Central Africa, to study regional rainfall controls on landslides conditioned by climate change. Preliminary results are presented, including a description of the current rain gauge network installed, an inventory of 83 landslide events with known date and location, and a case study of a landslide occurrence. We show that the underrepresentation of Central Africa in current landslide-climate research is related to the dearth of adequate rainfall ground monitoring networks and spatiotemporal data on landslide occurrence, rather than to the lack of landslide occurrence. Research constraints imposed by the context of Central Africa are highlighted. In presenting this challenging research setting, our aim is not to discourage research in the region, but to identify lessons learned from previous field work and emphasize the abundant opportunities inviting natural hazard studies in Central Africa. [less ▲]

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See detailEfficient management of a connected microgrid in Belgium
Cornélusse, Bertrand ULiege; Ernst, Damien ULiege; Warichet, Luc et al

in Proceedings of the 24th International Conference on Electricity Distribution, Glasgow, 12-15 June 2017 (2017, June)

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See detailDecoding the disciplines – A pilot study at the University of Liège (Belgium)
Verpoorten, Dominique ULiege; Devyver, Julie ULiege; Duchâteau, Dominique ULiege et al

in Andersson, Roy; Martensson, Katarina; Roxa, Torgny (Eds.) Proceedings of the 2nd EuroSoTL Conference - Transforming patterns through the scholarship of teaching and learning (2017, June)

This paper reports on a first attempt to apply the two first stages of the “Decoding the disciplines” framework (Pace, 2017) at the University of Liège (Belgium). In this context, 7 professors volunteered ... [more ▼]

This paper reports on a first attempt to apply the two first stages of the “Decoding the disciplines” framework (Pace, 2017) at the University of Liège (Belgium). In this context, 7 professors volunteered to reflect, through a structured process, upon “bottlenecks” in their courses, with the help of IFRES’ (Institute for Training and Research in Higher Education) pedagogical advisers. This pilot delivered contrasted observations: while participants granted value to their exposure to this approach, especially in terms of enhanced awareness of possible discrepancies between what experts and newcomers in the field might consider as obvious, none of them activated the possibility offered to tackle the identified bottlenecks, according to the systematic approach (stages 3-7) suggested by the framework. The paper presents the pedagogical setting, analyses the interviews of participants and the outcomes of the project, outlines explanations for its results, and shares some lessons learnt. [less ▲]

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See detailDocumenting the parameters of effective SoTL counselling
Jérôme, Françoise ULiege; Verpoorten, Dominique ULiege; Detroz, Pascal ULiege

in Andersson, Roy; Martensson, Katarina; Roxa, Torgny (Eds.) Proceedings of the 2nd EuroSoTL Conference (2017, June)

The Specialized Master in Higher Education Pedagogy (Formasup) organized at the University of Liège (Belgium) aims at the professional development of teachers involved in Higher Education. The training ... [more ▼]

The Specialized Master in Higher Education Pedagogy (Formasup) organized at the University of Liège (Belgium) aims at the professional development of teachers involved in Higher Education. The training programme gives participants the opportunity to make a full-scale SoTL study (from the implementation of a well-circumscribed course regulation to the assessment of its pedagogical effectiveness by means of the analysis of collected data) of one prominent aspect of their teaching practice. The process of trying out some new pedagogical approach and of discussing its effects on student learning has also to be reported in the form of a scientific paper (including a short review of the relevant pedagogical literature) and presented to a small audience of teacher colleagues. In order to meet the many requirements of such a complex task, each participant benefits from individualized pedagogical counselling. Besides a brief description of the Formasup context, the present contribution proposes brief case studies of three SoTL projects carried out in 2016. The case studies focus mainly on the dynamics of the interaction between teacher and pedagogical counsellor at each constitutive step of the SoTL project with the intention of making out the specificities of counselling applied to first time SoTL experience (time dedicated to and types of counselling activities in relation to the particularities of individual projects). The case studies are then integrated into a bigger picture drawing upon a larger number of counselling experiences over the last four years (from 2013 to 2016). On the basis of the main characteristics of 21 counselling experiences we propose a typology of teacher profiles according to their strategic approach to SoTL and the corresponding input of counselling. [less ▲]

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See detailChallenges of Trace Mineral Diagnosis
Guyot, Hugues ULiege

in ACVIM Forum Proceedings (2017, June)

Trace elements deficiencies are commonly seen in cattle herds in Europe and in some parts of the USA. Many reasons are involved: economics of the cattle industry, nutrients formulation and legislation ... [more ▼]

Trace elements deficiencies are commonly seen in cattle herds in Europe and in some parts of the USA. Many reasons are involved: economics of the cattle industry, nutrients formulation and legislation, depletion of soil and roughages quality. The clinical signs of the deficiencies are rarely pathognomonic but loss of production, impaired reproduction performances or increased morbidity/mortality rates are mostly observed. In a European critical economic context, especially for milk production, it is not easy to convince the farmer to invest in diagnosis and/or trace mineral supplementation. Nevertheless, it is important to investigate the nutritional status of the herd to improve global herd health. This presentation aims to present the interest of the diagnosis of trace mineral deficiencies as well as the different manners to investigate this nutrition trouble at a herd level. Trace mineral supplementation solutions will be briefly discussed. [less ▲]

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See detailSmart City concepts: from perception to acceptability
Schelings, Clémentine ULiege; Elsen, Catherine ULiege

in Proceedings of the 21th Conference of the Environmental and Sustainability Management Accounting Network (EMAN) (2017, June)

This paper studies the sustainability of the Smart City from the acceptability perspective. Assuming that there is a possibility for end-users to reject some of the Smart City principles and, consequently ... [more ▼]

This paper studies the sustainability of the Smart City from the acceptability perspective. Assuming that there is a possibility for end-users to reject some of the Smart City principles and, consequently, to jeopardize its perenniality, we argue that studying how citizens perceive some of the Smart City concepts is a prerequisite for the assessment of the Smart City sustainability scheme. In this paper, we test the acceptability of the Smart City by confronting the theoretical concepts generally mobilized in the literature with the people’s actual perceptions. To this end, a short survey was distributed on the occasion of three Smart City events. This article analyses the obtained results in regard of three demographic factors (age, gender and professional background). It thus repositions chore concepts of the Smart City in regard of acceptability, and particularly in relation to the associated risks for its sustainability. [less ▲]

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See detailThe Use of Inflammatory Markers in Field Cattle Medicine
Guyot, Hugues ULiege

in ACVIM Forum Proceedings (2017, June)

Numerous cow-side diagnostic tests are available for bovine practitioners. Many of these tests serve etiologic purposes such as quick test for diarrhea or measures of metabolites directly linked to ... [more ▼]

Numerous cow-side diagnostic tests are available for bovine practitioners. Many of these tests serve etiologic purposes such as quick test for diarrhea or measures of metabolites directly linked to pathologies (BOH or ions Ca++, Na+, K+, etc.). Beside these interesting elements, inflammation, which is either a cause or a consequence of a specific disease, is often forgotten. This presentation will refresh the practitioner’s knowledge on the assessment of inflammation in cattle by using inflammatory markers assayed with laboratory and cow-side tests. The interpretation of these markers can be sometimes delicate (bias) and might not necessarily lead to a prognosis. Depending on the age of the animal, some inflammatory markers can also serve as diagnosis for other purposes such as the evaluation of passive immunity transfer in calves. [less ▲]

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See detailHic Sunt NATs: Uncovering Address Translation with a Smart Traceroute
Zullo, Raffaele; Pescapé, Antonio; Edeline, Korian ULiege et al

in IEEE/IFIP Workshop on Mobile Network Measurement (MNM) (2017, June)

Middleboxes are pervasive in today's Internet as they are deployed for an increasing number of reasons. An example is the network address translation (NAT), one of the first task to be performed to cope ... [more ▼]

Middleboxes are pervasive in today's Internet as they are deployed for an increasing number of reasons. An example is the network address translation (NAT), one of the first task to be performed to cope with the lack of IPv4 addresses. Recently the landscape for NATs has become even more crowded, especially in mobile networks, mainly due to the impossibility of IPv6 to be a large-scale solution to addressing issues. In this paper, we present a novel methodology for detecting NATs embodied in Mobile Tracebox, a measurement tool for Android smart devices that detects a wide range of middleboxes. It analyzes ICMP time-exceeded messages received during \traceroute and points at IP and transport checksum inconsistencies in the embedded packets to uncover address translation along a path. We deployed Mobile Tracebox through a crowdsourcing approach and used the collected dataset to validate our methodology. Results showed that, in absence of middleboxes breaking \traceroute, it can help to detect and locate NATs in the majority of the cases. [less ▲]

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See detailDevelopment of a unified model for flow-material interaction applied to porous charring ablators
Coheur, Joffrey ULiege; Schrooyen, Pierre; Turchi, Alessandro et al

in 47th AIAA Thermophysics Conference : AIAA Aviation Forum, 5-9 June, Denver, CO (2017, June)

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See detailAutomatic phase identification of smart meter measurement data
Olivier, Frédéric ULiege; Ernst, Damien ULiege; Fonteneau, Raphaël ULiege

in Proc. of CIRED 2017 (2017, June)

This paper highlights the importance of the knowledge of the phase identification for the different measurement points inside a low-voltage distribution network. Besides considering existing solutions, we ... [more ▼]

This paper highlights the importance of the knowledge of the phase identification for the different measurement points inside a low-voltage distribution network. Besides considering existing solutions, we propose a novel method for identifying the phases of the measurement devices, based exclusively on voltage measurement correlation. It relies on graph theory and the notion of maximum spanning tree. It has been tested on a real Belgian LV network, first with simulated unbalanced voltage for which it managed to correctly identify the phases of all measurement points, second, on preliminary data from a real measurement campaign for which it shows encouraging results. [less ▲]

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