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See detailTree species and time since afforestation drive soil C and N mineralization on former cropland
Rahman, Md Masudur ULg; Bàrcena, Teresa G; Vesterdal, L

in Geoderma (2017), 305

Conversion from agriculture to forestry is considered a measure for mitigation of atmospheric CO2 but the impacts on soil C and N processes remain still unclear. We investigated heterotrophic respiration ... [more ▼]

Conversion from agriculture to forestry is considered a measure for mitigation of atmospheric CO2 but the impacts on soil C and N processes remain still unclear. We investigated heterotrophic respiration (RH), specific carbon mineralization (CMIN) and nitrogen mineralization (NMIN) in Norway spruce (Picea abies (Karst.) L.) and oak (Quercus robur L.) chronosequences on former cropland by laboratory incubation. The RH was estimated as the release of C per gram soil and CMIN as the release of C per gram of soil organic matter (SOM). Seven Norway spruce stands (16–44 years), eight oak stands (4–43 years), a cropland, a 35 years old permanent pasture and a 200-year-old oak-dominated forest were sampled (0–5 cm and 5–15 cm soil layers) in early spring. The SOM content gradually increased with stand age in 0–5 cm but remained the same in the 5–15 cm soil layer. The RH in the 0–5 cm layer gradually increased with time since afforestation in both tree species while there was no change in CMIN. In 5–15 cm, neither RH nor CMIN changed significantly after afforestation, but oak stands had significantly higher RH than Norway spruce. The NMIN and nitrification in 0–5 cm significantly increased with stand age and only nitrification was higher in oak. In 5–15 cm, only NMIN in oak increased with stand age, but both NMIN and nitrification were significantly higher in oak than spruce. Cropland RH, CMIN and NMIN rates were comparable to those found within the first decades of afforestation, whereas the 200-year-old forest and the pasture generally had RH and NMIN rates similar to the older chronosequence stands. We conclude that potential RH and soil N mineralization increased with time since afforestation and were tree species specific. Soil organic C stock gains observed in this area during the first 45 years after afforestation were not driven by decreased SOM decomposability, leaving increased litter C inputs as a more likely explanation. The lower CMIN in the 200-year-old forest suggests that future studies should include older forests to assess if the stability of C and the retention of N may increase in a longer term perspective. [less ▲]

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See detailPoésie et cosmologie
Delville, Michel ULg; Bertrand, Jean-Pierre ULg

Conference (2017, October 25)

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See detailIndexing grey multilingual literature in General Practice in the era of Semantic Web
Jamoulle, Marc ULg; Resnick, Melissa; Ittoo, Ashwin ULg et al

in The Grey Journal (2017, October 23)

voir abstract ci-dessous

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See detailSelf et perspective en première personne
Englebert, Jérôme ULg; Monville, François

Conference (2017, October 06)

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See detailBayesian Multi-Objective Optimisation of Neotissue Growth in a Perfusion Bioreactor Set-up
olofsson, Simon; Mehrian, Mohammad ULg; Geris, Liesbet ULg et al

Scientific conference (2017, October 01)

We consider optimising bone neotissue growth in a 3D scaffold during dynamic perfusion bioreactor culture. The goal is to choose design variables by optimising two conflicting objectives: (i) maximising ... [more ▼]

We consider optimising bone neotissue growth in a 3D scaffold during dynamic perfusion bioreactor culture. The goal is to choose design variables by optimising two conflicting objectives: (i) maximising neotissue growth and (ii) minimising operating cost. Our contribution is a novel extension of Bayesian multi-objective optimisation to the case of one black-box (neotissue growth) and one analytical (operating cost) objective function, that helps determine, within a reasonable amount of time, what design variables best manage the trade-off between neotissue growth and operating cost. Our method is tested against and outperforms the most common approach in literature, genetic algorithms, and shows its important real-world applicability to problems that combine black-box models with easy-to-quantify objectives like cost. [less ▲]

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See detailAby Warburg, Textes & Fragments (1926-1929) suivi de "Plasticité du visuel. Montages et usages critiques de l'image chez A. Warburg" (M. Hagelstein)
Hagelstein, Maud ULg; Letawe, Céline ULg

Book published by Presses Universitaires de Liège (2017)

Assorti d’une série de textes inédits, cet ouvrage monographique vise à faire connaître dans le milieu francophone les écrits d’Aby Warburg (1866-1929), en particulier ceux rédigés dans les dernières ... [more ▼]

Assorti d’une série de textes inédits, cet ouvrage monographique vise à faire connaître dans le milieu francophone les écrits d’Aby Warburg (1866-1929), en particulier ceux rédigés dans les dernières années de sa vie. Peu connus, ces textes datent de la période d’élaboration de l’Atlas d’images Mnemosyne – Atlas dont le succès grandissant auprès des artistes et des théoriciens de l’art n’est plus à démontrer . Mais si Mnemosyne attire de plus en plus les spécialistes des images de tous horizons, on accorde encore peu d’intérêt aux textes et aux notes rédigées par son auteur dans les années 1926-1929. Ces textes auraient du accompagner les planches de l’Atlas si le projet avait abouti. Or, les manuscrits inédits conservés au Warburg Institute (Londres) montrent la portée philosophique des recherches tardives d’Aby Warburg. Il y développe une théorie culturelle de l’image pour le moins originale et qui a profondément influencé certaines démarches plus contemporaines (dans les domaines de l’histoire de l’art, de l’anthropologie du visuel, de la Bildwissenschaft allemande ou des Visual Studies anglo-saxonnes). À l’occasion d’un débat avec les pensées de Nietzsche et de Burckhardt, Warburg élabore une conception nouvelle de la Kultur. [less ▲]

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See detailA mathematical model of respiration under protective ventilation and extracorporeal CO2 removal therapy
Habran, Simon ULg; Desaive, Thomas ULg; MORIMONT, Philippe ULg et al

Conference (2017, September 27)

The aim of the present study is to build a mathematical model of the respiratory system connected to an extracorporeal CO2 removal device (ECCO2RD) to optimize the gas exchanges efficiency. The model must ... [more ▼]

The aim of the present study is to build a mathematical model of the respiratory system connected to an extracorporeal CO2 removal device (ECCO2RD) to optimize the gas exchanges efficiency. The model must be simple enough to provide rapid solutions and to estimate specific parameters from available clinical data. But it also must be complex enough to be able to simulate the respiratory system when protective ventilation is used and when this system is assisted by an ECCO2RD. [less ▲]

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See detailConférence d'ouverture : Sartre, la Conférence de Rome, 1964
Cormann, Grégory ULg; Bourgault, Jean

Conference (2017, September 22)

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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 ULg

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 detailUsing IPCAPS to identify fine-scale population structure
Chaichoompu, Kridsadakorn ULg; Fentaw Abegaz, Yazew ULg; Tongsima, Sissades et al

Poster (2017, September 09)

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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, C.; Gernay, Thomas ULg

in Proceedings of the ASFE '17 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 detailA method for hybrid fire testing: Development, implementation and numerical application
Sauca, Ana ULg; Mergny, Elke ULg; Gernay, Thomas ULg et al

in Proceedings of ASFE'17 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 detailEffect of upgrading concrete strength class on fire performance of reinforced concrete columns
Gernay, Thomas ULg; Peric, Vlado; Mihaylov, Boyan ULg et al

in Proceedings of ASFE'17 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 detailSensitivity of elevated temperature load carrying capacity of thin-walled steel members to local imperfections
Maraveas, Chrysantos ULg; Gernay, Thomas ULg; Franssen, Jean-Marc ULg

in Proceedings of ASFE'17 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 detailMethis (7): Agir dans la ville.
Hamers, Jérémy ULg; Darcis, Damien ULg

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

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See detailAnalysis of definitions of General Practice/Family Medicine and Primary Health Care
Jamoulle, Marc ULg; Resnick, Melissa; Ittoo, Ashwin ULg et al

in British Journal of General Practice (2017)

Abstract Background There are numerous definitions of General Practice and Family Medicine (GP/FM) and Primary Health Care (PHC), but the distinction between the two concepts is unclear. Aim To conduct a ... [more ▼]

Abstract Background There are numerous definitions of General Practice and Family Medicine (GP/FM) and Primary Health Care (PHC), but the distinction between the two concepts is unclear. Aim To conduct a terminological analysis of a set of definitions of GP/FM and of PHC, to clarify what binds and what distinguishes these two concepts. Design The terms of 20 definitions were collected in two bags of words (one for GP/FM and one for PHC terms). A terminological analysis of these two bags of words was performed to prioritize the terms and analyze their world of reference. Methods The two collected bags of words were extracted with Vocabgrabber®, configured in two term butts using Wordle®, and further explored for similarities using Tropes®. The prioritized terms were analyzed using the Aristotelian approach to categorization of things. Results Although continuity of care (with person-centered approach and shared decision making) is the central issue of the two sets, the two sets of definitions differ greatly in content. The prioritized terms specific to GP/FM (community, medicine, responsibility, individual, problem, needs, ...) are different from prioritized terms specific to PHC (home, team, promotion, collaborator, engagement, neighborhood, medical center…). Conclusion Terminological analysis of the definitions for GP/FM and PHC shows two entities which are overlapping but distinct, necessitating a different taxonomic approach and different bibliographic search strategies. [less ▲]

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

in Etudes Philosophiques (2017)

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See detailCompte-rendu de l'ouvrage de Gilbert Gagné : The Trade and Culture Debate Evidence from US Trade Agreements
Vlassis, Antonios ULg

in Revue Québecoise de Droit International (2017)

Detailed reference viewed: 28 (0 ULg)