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See detailStability and Consistency of the LISP Pull Routing Architecture
Li, Yue; Saucez, Damien; Iannone, Luigi et al

in Proc. IEEE Workshop on Network Measurements (WNM) (2016, November)

Future Internet has been a hot topic for the last decade. One of the approaches put forward in order to revise the Internet architecture is LISP~--~Locator/ID Separation Protocol, which leverages the ... [more ▼]

Future Internet has been a hot topic for the last decade. One of the approaches put forward in order to revise the Internet architecture is LISP~--~Locator/ID Separation Protocol, which leverages the separation of the identifier and the locator roles of IP addresses. Contrary to the classical push model used by the BGP-based routing architecture, LISP relies on a pull model. In particular, routing information is pulled from a new network element, the Mapping System, to provide the association between the identifier (i.e., the address used to identify a host inside a domain) and a list of locators (i.e., the addresses to locate an attachment point) upon an explicit query. In this paper, we evaluate a LISP Mapping System deployment in the public LISP Beta Network from two standpoints: Stability and Consistency. Our measurements show that the mapping information is stable over time and consistent between the different mapping entities and the vantage points. Our analysis shows that there are cases where the Mapping System is unstable and/or inconsistent, hence, beside proposing a taxonomy in order to classify them, we carry out an in-depth investigation of such cases so to provide hints on how to improve the performance of LISP. [less ▲]

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See detailOn the Analysis of Internet Paths with DisNETPerf, a Distributed Paths Performance Analyzer
Wassermann, Sarah ULg; Casas, Pedro; Donnet, Benoît ULg et al

in Proc. 10th IEEE Workshop on Network Measurements (WNM) (2016, November)

Traceroute is the most widely used Internet path analysis tool today to study the topology of the Internet and to diagnose routing failures as well as poor performance events. A major limitation of ... [more ▼]

Traceroute is the most widely used Internet path analysis tool today to study the topology of the Internet and to diagnose routing failures as well as poor performance events. A major limitation of traceroute when the destination is not controllable by the user is its inability to measure reverse paths, i.e., the path from any given destination back to the source. This is a major drawback for ISPs, who need to understand the performance of the Internet paths connecting popular services (e.g., YouTube and Facebook) to their customers. Even if public servers and distributed measurement platforms can provide partial reverse path visibility through ad-hoc measurements, there is still a need for a structured approach capable of analyzing the performance of Internet paths connecting any pair of nodes (servers, routers, hosts, etc.). While the problem of reverse traceroute has been addressed in the past, proposed techniques rely on IP address spoofing – which might lead to security concerns, and assume the availability of certain route-tracking options –, which might not be available. In this paper, we introduce and evaluate DisNETPerf, a new tool which provides exactly the same type of information as traceroute, but for paths connecting arbitrarily selected nodes. DisNETPerf works by firstly locating probes (i.e., measurement points) that are the closest to a given target node, using them to perform traceroute measurements from the target point-of-view to a given destination for path performance monitoring and troubleshooting purposes. We propose two techniques for probe location, and demonstrate that the reverse path (from server to users) can be measured with very high accuracy in certain scenarios. We also analyze relevant characteristics of Internet paths and distributed measurement platforms, which reinforce the applicability and relevance of DisNETPerf in current Internet. [less ▲]

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See detailThe construction of religion as a ‘public problem’. The emergence of Islam in the public space during Tunisia’s transition to democracy (2011--2014)
Nachi, Mohamed ULg

in Social Sciences Information = Information sur les Sciences Sociales (2016), 55(4),

La construction de l'islam en "problème public" au cours de la période de transition démocratique.

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See detailTransition to democracy in Tunisia. Learning about citizenship in a national and transnational context
Nachi, Mohamed ULg

in Social Sciences Information = Information sur les Sciences Sociales (2016), 55(4),

La transition en Tunisie a constitué un moment fort d'apprentissage de la démocratie.

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See detailA large strain hyperelastic viscoelastic-viscoplastic-damage constitutive model based on a multi-mechanism non-local damage continuum for amorphous glassy polymers
Nguyen, Van Dung ULg; Lani, Frédéric; Pardoen, Thomas et al

in International Journal of Solids and Structures (2016), 96

A large strain hyperelastic phenomenological constitutive model is proposed to model the highly nonlinear, rate-dependent mechanical behavior of amorphous glassy polymers under isothermal conditions. A ... [more ▼]

A large strain hyperelastic phenomenological constitutive model is proposed to model the highly nonlinear, rate-dependent mechanical behavior of amorphous glassy polymers under isothermal conditions. A corotational formulation is used through the total Lagrange formalism. At small strains, the viscoelastic behavior is captured using the generalized Maxwell model. At large strains beyond a viscoelastic limit characterized by a pressure-sensitive yield function, which is extended from the Drucker-Prager one, a viscoplastic region follows. The viscoplastic flow is governed by a non-associated Perzyna-type flow rule incorporating this pressure-sensitive yield function and a quadratic flow potential in order to capture the volumetric deformation during the plastic process. The stress reduction phenomena arising from the post-peak plateau and during the failure stage are considered in the context of a continuum damage mechanics approach. The post-peak softening is modeled by an internal scalar, so-called softening variable, whose evolution is governed by a saturation law. When the softening variable is saturated, the rehardening stage is naturally obtained since the isotropic and kinematic hardening phenomena are still developing. Beyond the onset of failure characterized by a pressure-sensitive failure criterion, the damage process leading to the total failure is controlled by a second internal scalar, so-called failure variable. The final failure occurs when the failure variable reaches its critical value. To avoid the loss of solution uniqueness when dealing with the continuum damage mechanics formalism, a non-local implicit gradient formulation is used for both the softening and failure variables, leading to a multi-mechanism non-local damage continuum. The pressure sensitivity considered in both the yield and failure conditions allows for the distinction under compression and tension loading conditions. It is shown through experimental comparisons that the proposed constitutive model has the ability to capture the complex behavior of amorphous glassy polymers, including their failure. [less ▲]

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See detailOceanBrowser: on-line visualization of gridded ocean data and in situ observations
Barth, Alexander ULg; Watelet, Sylvain ULg; Troupin, Charles et al

Conference (2016, October)

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See detailA review of Silurian dispersed spore assemblages from the Arabian Plate: biostratigraphy and palaeogeography
Wellman, CH; Steemans, Philippe ULg; Breuer, P et al

Conference (2016, October)

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See detailIdentification de mécanismes moléculaires d’induction de la réponse immunitaire de type Th2 par les cellules dendritiques conventionnelles CD11b+ du poumon
Janss, Thibaut ULg

Doctoral thesis (2016)

Currently, the activation mechanisms of type 2 helper T cells (Th2) by dendritic cells are not yet fully understood. In recent years, more and more evidences show that there is a functional specialization ... [more ▼]

Currently, the activation mechanisms of type 2 helper T cells (Th2) by dendritic cells are not yet fully understood. In recent years, more and more evidences show that there is a functional specialization of the different dendritic cells populations. Therefore, in our laboratory, it was demonstrated that lung CD11b+ conventional dendritic cells (cDC) are the cells responsible for the allergic sensitization after an inhalation of house dust mite extracts in mice. Because this population is responsible for priming Th2 response, we decided to study them in an allergic context as a model in order to identify new mechanisms involve in Th2 induction. So far, few transcription factors required for the pro-Th2 activity of dendritic cells have been identified. Their discovery could considerably improve the understanding of Th2 activation by dendritic cells. Transcriptomic profiling of lung CD11b+ cDCs exposed to HDM in vivo revealed first that HDM triggered an antiviral defence-like response and second that the majority of HDM-induced transcriptional changes depended on the transcription factor Inresterferon Response Factor-3 (Irf3). Validating the functional relevance of these observations, Irf3-deficient CD11b+ cDCs displayed reduced pro-allergic activity. Indeed, Irf3-deficient CD11b+ cDCs induced less Th2, more regulatory T cell, and similar Th1 differentiation in naïve CD4+ T cells compared to their wild-type counterparts. The altered APC activity of Irf3 CD11b+ cDCs was associated with reduced expression of CD86 and was phenocopied by blocking CD86 activity in wild-type CD11b+ cDCs. Altogether, these results establish Irf3, mostly known for its role in antiviral responses, as a transcription factor involved in the induction of Th2 responses through the promotion of pro-Th2 costimulation in CD11b+ DCs. [less ▲]

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See detailStructure and Dynamics of Ge-Se Liquids and Glasses under Pressure
Yildirim, Can ULg

Doctoral thesis (2016)

Among network forming glasses, chalcogenide glasses are of great importance not only for their optoelectronic applications, but also for the network structure that displays enhanced structural variability ... [more ▼]

Among network forming glasses, chalcogenide glasses are of great importance not only for their optoelectronic applications, but also for the network structure that displays enhanced structural variability due to the covalent bonding network. In this project, we study the Ge-Se binary alloy as the target system in order to investigate the structure and dynamics of the liquid and glassy phases under pressure by using a combination of ab initio molecular dynamics (AIMD) simulations and X-ray scattering experiments. The wide glass forming range of the GexSe100􀀀x system allows one to tune the stiffness of the network structure by increasing the mean coordination number with the Ge content which affects the macroscopic material properties such as resistance to aging, hardness, conductivity, and fragility. In this respect, we study 10 different AIMD generated and 5 experimentally produced (i.e melt quenching) compositions spanning the flexible-to-rigid elastic phase transitions according to Maxwell’s isostatic stability criterion. As for the liquid state, after having validated the structural models by comparing the experimental findings available, we examine the dynamics of Ge-Se melts at ambient pressure. The investigations on the diffusion coefficients and viscosity at 1050 K showed clear anomalies, departing from the expectation that atomic mobility should decrease as the system becomes more and more rigid. Furthermore, the relaxation behavior at 1050 K also shows similar anomalies when intermediate scattering factors are examined at q vector corresponding to the principal peak position of the total structure factor. To elucidate this anomaly, we discuss the effect of the topological constraints on the dynamics in liquid state. The results show that the isostatic systems have slower dynamics as compared to flexible and stressed rigid phases. Moreover, we speculate that the reason of this anomaly may originate from the distribution of the topological bond bending constraints of the higher coordinated species (i.e. Ge) results. In particular, the flexible, and stressed rigid compositions showed a high variance in the Ge bond bending constraints whereas the isostatic composition forms a network in which the bond bending constraints are homogeneously distributed. We link this behavior with a global fragility concept for network forming liquids in such a way that fragility minima are obtained both by experimental findings and the calculated fragility values of the AIMD generated compositions (i.e. VFT or MYEGA fits) when scaled to the isostatic composition for a number of different systems. As for the glassy phase, the AIMD generated structural models show good agreement in both real and reciprocal space. The equation of state and normalized stress-strain curves are compared to the available experiments in order to verify the pressure behavior of the simulations. The results show a good agreement. In addition to the simulations under pressure, we show results of X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) experiments under pressure. Both simulations and the experiments show that there are no sign of crystallization during compression up to 42 GPa. One of the main important finding is the evolution of the Ge-Se bond length for the compositions studied. We observe a bond compression in the early stages of densification in the phase identified as low density amorphous (LDA), which is followed by an abrupt jump starting in pressures around 10-15 GPa, both in simulations and experiments. Furthermore, a semiconductor to metal transition is identified with the red shift in Ge K edge energy. The features of polyamorphism was also detected from the pressure evolution of the principal peak position of the structure factor which show two distinct slopes indicating different structural response to the applied pressure. In order to have a deeper understanding of the densification mechanisms, we apply neighbor analyses to our atomic trajectories and show that the tetrahedral to octahedral transformation (i.e LDA to HDA) starts to take place when the fifth and sixth neighbors effectively become the part of first shell neighbors, where the bond angles adapt themselves to 90 degrees. We furthermore speculate the effect of network rigidity of the glasses at ambient conditions onto the kinetics of the amorphous-amorphous transitions. It appears that the polyamorphic transitions are more sluggish as the network rigidity (i.e Ge content) increases. Finally we show that there is a universal threshold value in coordination change from LDA to HDA phases GexSe100􀀀x (where x 25) when scaled to reduced densities. [less ▲]

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See detailDealing with storm impacts on the forest sector through integrated and systemic approaches at the regional level
Riguelle, Simon ULg

Doctoral thesis (2016)

Wind is one the most damaging natural hazard that forests are facing worldwide and in Europe. Destructive storms lead to severe forest damage and consequently cause disruptions in daily forest management ... [more ▼]

Wind is one the most damaging natural hazard that forests are facing worldwide and in Europe. Destructive storms lead to severe forest damage and consequently cause disruptions in daily forest management and timber supply chains. Major dysfunctions can happen at each step of forest-wood chains and at each level of management, leading to huge economic losses and long-lasting crises within public organisations and private companies. In this context, the first part of this work aims at handling those complex and multi-facetted storm-related issues with new approaches in order to mitigate economic, environmental and societal impacts of storms on the forest-based sector. In a first step, an overview of risk management practices in forestry is presented, as well as major determinants of storm damage risk management. SWOT analyses are also used for highlighting main issues and opportunities in current windthrow management process. In a second step, an integrated framework is proposed for tackling those strategic issues and seizing opportunities arising from the uncertain decision-making context. A systemic perspective is also presented for managing storm damage risk at regional, national or supranational level with a holistic perspective. In regards to those original approaches, the thesis also highlights some of the crucial challenges public authorities might address for enhancing their affectivity in this process. In the second part of the manuscript, three particular aspects of storm damage management are considered: contingency planning, the development of decision-supporting tools for the forest community, and timber storage planning at the regional level. Those topics are illustrated by case studies taking place in Wallonia, Belgium. In particular, the development of a model-based decision support system (DSS) illustrate how systemic analysis can help on the one hand designing balanced strategies for the regional forest-based sector in case of severe wind damage and on the other hand identifying bottlenecks that should be solved before the next huge storm to enhance systemic resilience and resistance. Regarding timber conservation, a GIS-based methodology for locating optimal areas for sprinkling storage at the regional scale is presented, together with an applied study on the influence of anaerobic storage process on the quality of spruce logs. From a wider perspective, this thesis reveals that taking decision under uncertainty will remain a key challenge to address in forestry, especially in the context of climatic change. However, original methodologies focusing on systemic and integrated risk management approaches can help in this effort. Finally, the work emphasises the urgent need of effective risk management policies at regional, national, and international levels to guide researchers, forest managers and industrials. [less ▲]

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See detailDevelopment and validation of analytical methods for quantifying isoflavones and equol in biological matrices
Daems, Frédéric ULg

Doctoral thesis (2016)

Isoflavones are natural plant substances that attract widespread interest because of their association with a large variety of beneficial effects on human health. When they are ingested by animals or ... [more ▼]

Isoflavones are natural plant substances that attract widespread interest because of their association with a large variety of beneficial effects on human health. When they are ingested by animals or humans, most of these compounds are metabolized by bacteria present in the digestive system. Among the isoflavone microbial metabolites, equol is probably the most widely studied because it seems to have numerous health benefits. In the human population, however, not everyone is able to produce equol. Equol enrichment of some food, such as cow's milk, could be an alternative strategy for making equol’s health benefits available to everyone. The main objective of the present thesis was to develop analytical tools for quantifying these compounds in several biological matrices, thus contributing to the feasibility study being conducted on producing milk naturally enriched with equol. For this purpose, four analytical procedures, using ultra performance liquid chromatography coupled with tandem mass spectrometry (UPLC®-MS/MS), were developed and fully validated. The analytical tools were then applied successfully in two original exploratory studies that sought to quantify equol concentrations in commercial cow's milk in Belgium and study the evolution of isoflavone concentration in red clover (Trifolium pratense L.) silage in laboratory-scale silos. This thesis describes new and reliable analytical tools that will help to improve current knowledge about the feasibility of producing cow's milk naturally enriched with equol and to study isoflavone metabolization in dairy cow. [less ▲]

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See detailWhat’s the difference? Results of a functional study of Aterian and Mousterian tools from the site of Ifri n’Ammar (Morocco)
Tomasso, Sonja ULg; Rots, Veerle ULg

Conference (2016, September 16)

Until today, the definition of the North African Mousterian has been based on a systematic comparison with the European Mousterian. Particularly the “Aterian” and its tanged tools have been widely ... [more ▼]

Until today, the definition of the North African Mousterian has been based on a systematic comparison with the European Mousterian. Particularly the “Aterian” and its tanged tools have been widely discussed. Researchers considered the tanged Aterian tools as early indications of the existence of hafting techniques [1]. It is currently not entirely understood how the Aterian relates to the Mousterian in North Africa, whether tanged tools can indeed be linked with hafting, and whether non-tanged tools were also hafted, which could indicate that a variety in hafting techniques existed. The site of Ifri n’Ammar presents an ideal chance to compare Aterian and Mousterian technocomplexes. The rock shelter is located in the eastern Moroccan Rif and has a rich and well preserved stratigraphy where Middle Paleolithic tools are abundantly represented [2]. At Ifri n’Ammar, the Aterian and Mousterian assemblages are inter-stratified, which means that the relationship of these industries cannot simply be explained in terms of chronological succession [2,3]. The density of retouched artefacts differs between the Aterian and the Mousterian levels and tanged tools are present in the denser Aterian levels only. These levels also show a higher overall tool frequency. We present the results of a functional study focusing on the artefacts from the upper levels (“Occupation supérieure”) of Ifri n’Ammar, dated between 83 ± 6 ka and 130 ± 8 ka [3]. The functional study was combined with a specific experimental program designed to address questions raised during the analysis of the archaeological material, with a specific focus on hafting. Diagnostic microscopic wear patterns confirm that the tanged tools were used while hafted. Tanged tools did not prove to be related to hunting activities only, but various tool uses could be identified. They all fit, however, within the context of hunting and animal processing activities. The reuse of hafted armatures for other activities is not evident in the present sample. [less ▲]

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See detailCoefficients binomiaux de mots
Rigo, Michel ULg

Scientific conference (2016, September 15)

Le coefficient binomial (u,v) de deux mots u et v est défini comme le nombre de fois que v apparaît comme sous-suite du mot u. Par exemple, (abbab,ab)=4. Il étend de manière naturelle le coefficient ... [more ▼]

Le coefficient binomial (u,v) de deux mots u et v est défini comme le nombre de fois que v apparaît comme sous-suite du mot u. Par exemple, (abbab,ab)=4. Il étend de manière naturelle le coefficient binomial de deux entiers. Ce concept a été largement étudié depuis plus d'une trentaine d'années (cf. par exemple, Simon et Sakarovitch). Dans cet exposé, je passerai tout d'abord en revue quelques résultats combinatoires classiques pour ensuite m'attarder sur l'équivalence k-binomiale. A l'instar de l'équivalence k-abélienne étudiée par Karhumäki et al., deux mots x et y sont k-binomialement équivalents si leurs coefficients binomiaux (x,v) et (y,v) coïncident pour les mots v de longueur au plus k. En fin d'exposé, j'évoquerai l'extension récente des triangles de Pascal et de Sierpinski à ces coefficients. [less ▲]

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See detailAcoustic indices provide information on the status of coral reefs: an example from Moorea Island in the South Pacific
Bertucci, Frédéric; Parmentier, Eric ULg; Lecellier, Gaël et al

in Scientific Reports (2016), 6(33326), 1-9

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See detailPerformance de l'indicateur Azote Potentiellement Lessivable pour l'évaluation de la gestion du nitrate en agriculture et du risque pour la qualité de l’eau
Vandenberghe, Christophe ULg

Doctoral thesis (2016)

Since the end of last century, the nitrate concentration in groundwater has steadily increased in Wallonia as in other parts of Europe, particularly in regions where agriculture is intensively practised ... [more ▼]

Since the end of last century, the nitrate concentration in groundwater has steadily increased in Wallonia as in other parts of Europe, particularly in regions where agriculture is intensively practised. In response to this, Europe developed a ' Nitrates ' directive in 1991 that each member state had to transcribe in its legislation. In the Walloon region, the transcription took the form of a Sustainable Nitrogen Management Program (PGDA). This program provides among others control of farms through the analysis of nitrate nitrogen soil residue, in autumn, the beginning of the leaching period of nitrate. This measure is commonly referred to as APL for ‘Potentially Leachable Nitrogen’. The results are assessed by comparison to references established annually based on observations in plots where PGDA is applied and where fertilization recommendations are based on nitrogen balance. In case of non -compliance, the farmer has to follow an observation program, or even to pay a fine. The aim of the thesis is to evaluate the performance of the APL as agronomic (nitrogen management) and environmental indicator (risk to groundwater quality). On the agronomic side, through experimentations or treatment of field APL controls, it has been demonstrated that the indicator was well correlated with fertilization practices and intercrop management. The performance of the indicator has been validated. Some uncertainty factors (intra-plot variability, temporal variability, bulk density, stone content) were quantified. Finally, the influence of soil physicochemical properties on the APL was studied and discussed. The performance of the APL control was also discussed and improvements to regulation have been proposed. On the environmental side, through observations made during a decade in plots equipped with a lysimiter or in a small watershed, the dependence of the nitrate concentration in water (at the base of the root zone or in aquifer) to the APL has been demonstrated. It therefore appears that the APL can be used to firstly assess the reality of the sustainable nitrogen management in controlled farms and also to validate or, if necessary, complete the PGDA to make it more efficient for water quality preservation / restoration. [less ▲]

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See detailOmbres de réalité
Choffray, Jean-Marie ULg

Book published by Amazon, Kindle Edition (2016)

« Ombres de réalité » a pour objectif de partager avec vous nombre d’erreurs personnelles – factuelles et d’appréciation –, à la lumière de ce que d’autres ont eu l’élégance de nous transmettre. Le socle ... [more ▼]

« Ombres de réalité » a pour objectif de partager avec vous nombre d’erreurs personnelles – factuelles et d’appréciation –, à la lumière de ce que d’autres ont eu l’élégance de nous transmettre. Le socle de la réalité, lieu de convergence de ses ombres, et que décrit à merveille la comédie humaine, ne peut jamais être approché qu’au travers d’une recherche sincère et permanente. Apprendre à désapprendre résolument, apprendre à reconstruire patiemment, et apprendre à transmettre modestement, constituent le but ultime de la vie. Personnellement, je n’en vois pas d’autre aujourd’hui. Après une brève introduction, ou « Sortie de l’ombre », de courts chapitres couvrent un thème particulier, généralement à la lumière d’observations, d’expériences personnelles, ou de lectures qui m’ont touché. La sélection et l’ordre des sujets ne traduit aucun souci particulier, même si je ne crois plus beaucoup au hasard. Tous deux pourraient évoluer au fil des révisions que connaîtra ce texte dans les années à venir. Le choix actuel va de « Chacun pour soi » au « Secret du silence », en passant par « L’aventure à deux », « La foire aux illusions », « La tyrannie des marchés », « L’intérêt général », « Non ! merci », et « Une chance d’être ». Chaque thème peut être exploré isolément. A vous, donc, de constituer votre menu en fonction de votre curiosité et de votre appétit. [less ▲]

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