Last 7 days
Bookmark and Share    
Full Text
Peer Reviewed
See detailLoadbearing capacity criteria in fire resistance testing
Dumont, Fabien ULg; Wellens, Eric ULg; Gernay, Thomas ULg et al

in Materials and Structures (2016), 49(11), 4565-4581

The European system for fire testing and classification of loadbearing building elements lacks consistency because the two standards that have to be applied prescribe different criteria for assessing the ... [more ▼]

The European system for fire testing and classification of loadbearing building elements lacks consistency because the two standards that have to be applied prescribe different criteria for assessing the loadbearing performance. This article analyzes the implications of the present conflict between the standard for testing and the standard for classification. The prescribed criteria for loadbearing performance are related to the exceedance of deflection and rate of deflection thresholds. A database of 46 fire resistance tests performed at the University of Liege is collected that contains the time at which these thresholds are reached in fire tests with different typologies of elements (walls, floors, columns and beams). Then, the loadbearing performance (and hence the fire resistance rating) can be derived according to the two standards. The evolutions of deflection and rate of deflection during the tests are also analyzed to gain a better understanding of the adequacy of the standards. The selection of one or the other standard affects the time at which “failure” is deemed to occur in fire tests. Statistically speaking, the difference in terms of failure time that results from using one or the other standard has a 25% probability to exceed 10%. In certain cases, this results in a difference in fire resistance rating; this was observed for 3 of the analyzed tests. The apparent contradiction in two codes in application has potential practical implications and therefore needs to be solved. The article suggests some guidelines for defining homogenized and consistent criteria. [less ▲]

Detailed reference viewed: 39 (15 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 18 (1 ULg)
Full Text
See detailPreoptic glutamate and estradiol release during male sexual behavior
de Bournonville, Catherine ULg; de Bournonville, Marie-Pierre ULg; Aourz, Najat et al

Poster (2016, November)

Beside its long-term control by steroids, male sexual behavior is also modulated by neuroestrogens in a dynamic way (within minutes) in a number of species ranging from fishes to mammals. Studies in male ... [more ▼]

Beside its long-term control by steroids, male sexual behavior is also modulated by neuroestrogens in a dynamic way (within minutes) in a number of species ranging from fishes to mammals. Studies in male Japanese quail have also identified following exposure to a receptive female a rapid decrease in the activity of brain aromatase (AA) the enzyme responsible for the conversion of androgens into estrogens. These effects occur mainly within the medial preoptic nucleus (POM), a sexually dimorphic structure of the preoptic area that plays a key role in the activation of male sexual behavior and contains the highest AA in the brain. In vitro studies demonstrated that AA can be rapidly inhibited by calcium-dependent phosphorylations of the enzyme triggered by the activation of AMPA and kainate receptors. We confirmed here this rapid effect of glutamate on AA by injecting kainate in the POM of anesthetized males and measuring AA in the tissue after brain collection. AA in POM was inhibited in the kainate-injected hemisphere compared to the control hemisphere injected with vehicle. In a second experiment, we showed by in vivo microdialysis that glutamate is released in POM during copulation. These results thus suggest that glutamate controls dynamic changes of AA that occur in the brain during sexual interactions. To confirm that the decrease in AA leads to an actual reduction of local estradiol concentration, we quantified via microdialysis and radioimmunoassay changes in estradiol concentration in the male POM during sexual interactions with a female. Surprisingly, a dramatic elevation of estradiol was observed during copulation. Estradiol has been shown to enhance acutely male sexual motivation, therefore the function of its increase in the POM could be to maintain motivation during the entire sexual encounter. The decrease of AA observed ex vivo after copulation would then reflect a compensatory mechanism to restore baseline pre-copulatory conditions. Importantly, these results highlight that although long-term changes in AA are often used as a proxy for local estradiol concentrations, these two measures can show major short-term discrepancies possibly reflecting variations in estrogen turnover. [less ▲]

Detailed reference viewed: 32 (1 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 32 (9 ULg)
See detailInstitut de droit International’s Crisis (1873-1890’)
Genin, Vincent ULg

Conference (2016, November)

Detailed reference viewed: 12 (1 ULg)
Full Text
See detailReverse Traceroute with DisNETPerf, a Distributed Internet Paths Performance Analyzer
Wassermann, Sarah ULg; Casas, Pedro

in Proc. Demonstrations of the 41th Annual IEEE Conference on Local Computer Networks (LCN-Demos 2016) (2016)

Traceroute is the most widely used Internet path diagnosis tool today. A major limitation of traceroute when the destination is not controllable by the user is its inability to measure reverse paths, i.e ... [more ▼]

Traceroute is the most widely used Internet path diagnosis tool today. 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 a destination back to the source. In this demo session, we showcase DisNETPerf, a new tool to perform reverse traceroute measurements. DisNETPerf is able to collect measurements from the server to the user for path performance monitoring and troubleshooting purposes, even when the server is not under the control of the experimenter. DisNETPerf uses RIPE Atlas, a largely distributed active measurements platform to perform traceroute measurements from any arbitrarily selected server in the Internet. [less ▲]

Detailed reference viewed: 13 (0 ULg)
Full Text
Peer Reviewed
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.

Detailed reference viewed: 8 (1 ULg)
Full Text
Peer Reviewed
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.

Detailed reference viewed: 9 (1 ULg)
See detailDas Ende der Phantomschmerzen. Die Bundesrepublik und "Eupen-Malmedy"
Brüll, Christoph ULg

Scientific conference (2016, October 28)

Detailed reference viewed: 7 (0 ULg)
Full Text
See detailBounding surface plasticity model for natural clays
Ahayan, Sanae ULg; Yin, Zhen-Yu; Kotronis, Panagiotis et al

Conference (2016, October 26)

Natural soft clay exhibits a considerable degree of anisotropy as a result of its past sedimentation and consolidation history. It also tends to have significant inter-particle bonding, which affects its ... [more ▼]

Natural soft clay exhibits a considerable degree of anisotropy as a result of its past sedimentation and consolidation history. It also tends to have significant inter-particle bonding, which affects its mechanical behavior. The natural structure of in-situ soils makes their behavior different from that of a reconstituted material. In fact, most clays lose a proportion of their strength when remoulded. Various authors proposed anisotropic elastoplastic soil models allowing the yield surface to rotate with the stress history. These models have a “rotational hardening law" which relates the change of the inclination of the yield surface to the current soil state and to the increments of the plastic volumetric and/or shear strain, [Sekiguchi and Otha (1977)], [Hashiguchi and Chen (1998)], [Wheeller et al (2003)]… Other authors combine the plastic anisotropy with destructuration effects observed in soft sensitive soils by assuming that the size and /or the position of the center of the yield surface depends on the amount of the structural soil degradation. These models use an additional isotropic hardening law that relates the size and/or the position of the yield surface of the intact sample to that of the reconstituted one [Nova et al (2003)]. The previous models provide little or no flexibility when it comes to describe the change of the plastic modulus with the loading direction as they are unable to produce a smooth degradation of the stiffness, being single yield surface models. A way to improve this behavior is to introduce the “bounding surface plasticity” theory, initially developed by Dafalias [Dafalias and Herrmann 1986]. Unlike a single yield surface model, the bounding surface theory allows a smooth transition of stresses within and on the bounding surface. The mean feature of this concept is that the actual stress is mapped to the imaginary stress on the bounding surface. The distance between the real and imaginary stress, which is called the “ function distance ”, is used to specify the plastic modulus. This work presents a bounding surface plasticity model for natural and structured clays based on the critical state theory. A novel rotational hardening rule for clays is presented, and a hardening function distance is introduced to describe the evolution of the bounding surface. Validation of the model is provided by drained and undrained tests of Scottish and Finnish intact and reconstituted clays [Kastunnen 2008]. Finally, finite element simulations of a foundation considering the formulated constitutive law are presented. [less ▲]

Detailed reference viewed: 11 (1 ULg)
See detailLe droit international : un fleuron de la Belgique
Genin, Vincent ULg

Conference given outside the academic context (2016)

Detailed reference viewed: 18 (2 ULg)
Full Text
Peer Reviewed
See detailSU(3) Clebsch-Gordan coefficients at large $N_c$
Stancu, Floarea ULg

in Nuclear Physics A (2016), 945

It is argued that several papers where SU(3) Clebsch-Gordan coefficients were calculated in order to describe properties of hadronic systems are, up to a phase convention, particular cases of analytic ... [more ▼]

It is argued that several papers where SU(3) Clebsch-Gordan coefficients were calculated in order to describe properties of hadronic systems are, up to a phase convention, particular cases of analytic formulae derived by Hecht in 1965 in the context of nuclear physics. This is valid for irreducible representations with multiplicity one in the corresponding Clebsch-Gordan series. For multiplicity two, Hecht has proposed an alternative which can provide correct $1/N_c$ sub-leading orders in large $N_c$ studies. [less ▲]

Detailed reference viewed: 27 (4 ULg)
See detailMathias Enard, traducteur nomade
Bada, Valérie ULg

Speech/Talk (2016)

A travers 4 traductions de Mathias Enard (deux poèmes issus de la tradiction littéraire obscène persane et arabe du 19e s, ainsi qu'un récit autobiographique traduit de l'arabe du Liban et un recueil de ... [more ▼]

A travers 4 traductions de Mathias Enard (deux poèmes issus de la tradiction littéraire obscène persane et arabe du 19e s, ainsi qu'un récit autobiographique traduit de l'arabe du Liban et un recueil de nouvelles traduites du castillan), le rapport à la langue de traduction et à sa langue de création littéraire est évoqué ainsi que l'intervention créative dans le texte traduit. Est évoquée également la visibilité du traducteur à travers la préface et la postface de ses traductions. [less ▲]

Detailed reference viewed: 35 (0 ULg)
See detailPsychiatrie et liberté : approche phénoménologique
Englebert, Jérôme ULg; Cormann, Grégory ULg

Conference (2016, October 22)

Detailed reference viewed: 32 (6 ULg)
See detailLe clergé à Eupen-Malmedy durant l'entre-deux-guerres
Brüll, Christoph ULg

Conference given outside the academic context (2016)

Detailed reference viewed: 11 (0 ULg)
Peer Reviewed
See detailThe Middle Ages: A New Age for the Reception of the Gods of Egypt
Veymiers, Richard ULg

Conference (2016, October 20)

Detailed reference viewed: 19 (0 ULg)
See detailPrison : face à l'enfermement des corps
Englebert, Jérôme ULg

Conference given outside the academic context (2016)

Detailed reference viewed: 17 (2 ULg)
See detailXérogels de carbone comme matériaux modèles pour l'étude du comportement électrochimique en tant qu'anodes de batteries Li-ion
Piedboeuf, Marie-Laure ULg

Doctoral thesis (2016)

The main goal of this thesis aims at shedding some light on how the textural and surface chemistry properties of porous carbons influence their electrochemical behavior when used as anodes for Li-ion ... [more ▼]

The main goal of this thesis aims at shedding some light on how the textural and surface chemistry properties of porous carbons influence their electrochemical behavior when used as anodes for Li-ion batteries. In this respect, carbon xerogels (XC) have been used as model materials, since their tunable pore texture and surface chemistry have made it possible to perform a systematic study, where each variable could be modified independently. The first target consisted in obtaining a series of carbon xerogels with controlled meso- or macropore textures. These materials are made of interconnected nearly spherical microporous nodules, delimiting meso- or macroporous voids. Several series of carbon xerogels with controlled pore textures have been prepared. As a result, materials with a wide range of meso- or macropore sizes have been obtained and the influence of the aqueous formaldehyde precursor solution on the final textural characteristics could be highlighted. Additional post-synthesis treatments have been performed in order to tune the microporosity as well as the surface chemistry of selected materials. The second aim was to control and set several variables other than the pore texture and the surface chemistry of XC, that could influence their behavior as active materials for Li-ion batteries, such as the particle sizes or the electrode characteristics. In this respect, an in-depth study of the ball-milling process of carbon xerogels has allowed to determine the conditions leading to materials with a well-defined particle size distribution centered on 10 µm. The specific surface area, as well as the meso- or macroporosity remain identical from the monolithic form to the final powder. This work has also shown the possibility of using mercury intrusion porosimetry as a tool to assess the mean particle sizes of a XC powder. Several methods for the coating of active materials on current collectors (bar-coating and spray) have been investigated for different ink formulations (organic- or water-based). This study has shown that XC-binder composites resulting from aqueous-based inks preserve the porosity of the starting materials, whereas the microporosity is strongly reduced in the case of the organic pathway. As a result, the method of spraying a water-based ink, with xanthan gum as a binder, seems to be the most appropriate in terms of precision, ease of processing and safety in this case. The third goal consisted in performing detailed electrochemical characterizations of the electrodes produced with carbon xerogels displaying various defined pore textures and surface chemistries. In the case of electrodes obtained upon using an organic ink, a linear relationship is observed between the relative irreversible losses and i) the external surface area of the nodules as well as ii) the specific surface area of the XC-binder composites. In the case of the aqueous electrode processing method and upon using carbon xerogels with tuned microporosity, a linear relationship could be established between the total specific surface area of the starting materials (including micropores) and the irreversible as well as reversible capacities at the first charge-discharge cycle, if the maximum potential is set at 3 V vs. Li+/Li. Finally, after modulation, the surface chemistry has shown to have a significant effect on the accessibility of the surface by the electrolyte as well as on the SEI formation at the first charge-discharge cycle. [less ▲]

Detailed reference viewed: 12 (3 ULg)
See detailAnorexie et régulation émotionnelle
Englebert, Jérôme ULg

Conference (2016, October 08)

Detailed reference viewed: 32 (4 ULg)