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See detailIdentifying and computing nonlinear normal modes
Cammarano, A.; Carrella, A.; Renson, Ludovic ULg et al

in Proceedings of the SEM IMAC XXX Conference (2012, February)

Non linear normal modes offer a rigorous framework, both mathematical and physical, for theoretical and experimental dynamical analysis. Albeit still in its infancy, the concept of non linear normal modes ... [more ▼]

Non linear normal modes offer a rigorous framework, both mathematical and physical, for theoretical and experimental dynamical analysis. Albeit still in its infancy, the concept of non linear normal modes has the potential of providing to both the academic and the industrial establishment a powerful tool for the analysis of non linear dynamical systems. However, in order to exploit the full potential of this theory (and its associated simulation capability), there is need to integrate it with other branches of non linear structural dynamics: namely, in order for the non linear normal modes of a real - physical - structure to be computed, there is need to identify and quantify its non linearity. In this paper, an identification method based on the measured Frequency Response Function (FRF) is employed to identify and quantify the system's non linearity before computing the system's non linear normal modes. [less ▲]

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See detailLa Foire du livre, terrain d'enquête
Barnabé, Fanny ULg; Bertrand, Charlotte ULg; Duchesne, Laurence

Article for general public (2012)

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See detailBeleidsaanbevelingen ter ondersteuning van ondernemers in moeilijkheden
Van Caillie, Didier ULg; Lambrecht, Johan

Book published by Koning Boudewijn Stichting - 1ère (2012)

This study proposes an extended discussion of 7 measures adapted for increasing the efficiency of administrative and legal measures taken in Belgium in order to sustain entrepreneurs confrontated to the ... [more ▼]

This study proposes an extended discussion of 7 measures adapted for increasing the efficiency of administrative and legal measures taken in Belgium in order to sustain entrepreneurs confrontated to the first steps of a business decline [less ▲]

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See detailOn the human pose recovery based on a single view
Pierard, Sébastien ULg; Van Droogenbroeck, Marc ULg

in International conference on pattern recognition applications and methods (ICPRAM) (2012, February)

Estimating the pose of the observed person is crucial for a large variety of applications including home entertainment, man-machine interaction, video surveillance, etc. Often, only a single side view is ... [more ▼]

Estimating the pose of the observed person is crucial for a large variety of applications including home entertainment, man-machine interaction, video surveillance, etc. Often, only a single side view is available, but authors claim that it is possible to derive the pose despite that humans evolve in a 3D environment. In addition, to decrease the sensitivity to color and texture, it is preferable to rely only on the silhouette to recover the pose. Under these conditions, we show that there is an intrinsic limitation: at least two poses correspond to the observed silhouette. We discuss this intrinsic limitation in details in this short paper. To our knowledge, this issue has been overlooked by authors in the past. We observe that this limitation has an impact on the way previous reported results should be interpreted, and it has clearly to be taken into account for designing new methods. [less ▲]

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See detailCoordinated primary frequency control among non-synchronous systems connected by a multi-terminal high-voltage direct current grid
Dai, Jing; Phulpin, Yannick; Sarlette, Alain et al

in IET Generation, Transmission & Distribution (2012), 6(2), 99-108

The authors consider a power system composed of several non-synchronous AC areas connected by a multiterminal high-voltage direct current (HVDC) grid. In this context, the authors propose a distributed ... [more ▼]

The authors consider a power system composed of several non-synchronous AC areas connected by a multiterminal high-voltage direct current (HVDC) grid. In this context, the authors propose a distributed control scheme that modifies the power injections from the different AC areas into the DC grid so as to make the system collectively react to load imbalances. This collective reaction allows each individual AC area to downscale its primary reserves. The scheme is inspired by algorithms for the consensus problem extensively studied by the control theory community. It modifies the power injections based on frequency deviations of the AC areas so as to make them stay close to each other. A stability analysis of the closed-loop system is reported as well as simulation results on a benchmark power system with five AC areas. These results show that with proper tuning, the control scheme makes the frequency deviations converge rapidly to a common value following a load imbalance in an area. [less ▲]

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See detailSuburban areas favoring energy efficiency (SAFE) : Rapport scientifique et technique final.
Marique, Anne-Françoise ULg; de Meester, Tatiana; De Herde, André et al

Report (2012)

Rapport de recherches final présentant les résultats du projet de recherches SAFE (2009-2012). Le projet de recherches SAFE portait sur l'évaluation énergétique des quartiers périurbains existants dans le ... [more ▼]

Rapport de recherches final présentant les résultats du projet de recherches SAFE (2009-2012). Le projet de recherches SAFE portait sur l'évaluation énergétique des quartiers périurbains existants dans le but d'en améliorer l'efficience énergétique par le développement de nouveaux modes de conception et de planification des tissus périurbains. L'objectif concret de ce projet de recherche est d'offrir un outil informatique interactif, accessible sur le web (www.safe-energie.be), qui permette d'évaluer l'efficience énergétique des lotissements wallons existants et de comparer différentes stratégies de renouvellement périurbain. Cet outil est destiné à l'ensemble des acteurs du processus de conception, réalisation et rénovation du milieu urbain. L'outil informatique développé estl'aboutissement d'une recherche de pointe basée sur la modélisation énergétique de quartiers périurbains à l'aide de simulations du microclimat urbain (logiciel de CFD, etc), de simulations dynamiques des consommations énergétiques des bâtiments pendant leur utilisation et de simulations énergétiques des fragments urbains sur l'ensemble de leur cycle de vie (intégrant l'évaluation énergétique des bâtiments, du transport et des réseaux d'énergie). [less ▲]

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See detailL'astronomie dans le monde
Manfroid, Jean ULg

Article for general public (2012)

Survivantes; Kepler-20 et KOI-961;Êta Carinae; Exo-Saturne ? ; GRAIL; Tranquillityite; H1743-322; Matière noire; ACT-CL J0102-4915; Nébuleuse Oméga

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See detailCours de géologie
Poty, Edouard ULg

Learning material (2012)

Notes du cours de géologie de 1 bac en géologie et de 2 bac en géographie

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See detailComparing vertical ground heat exchanger models
Bertagnolio, Stéphane ULg; Bernier, Michel; Kummert, Michaël

in Journal of Building Performance Simulation [=JBPS] (2012)

The main objective of this article is to establish a set of test cases for analytical verification and inter-model comparison of vertical ground heat exchanger (GHX) models used in building simulation ... [more ▼]

The main objective of this article is to establish a set of test cases for analytical verification and inter-model comparison of vertical ground heat exchanger (GHX) models used in building simulation programs. Several test cases are suggested. They range from steady-state heat rejection in a single borehole to varying hourly loads with relatively large yearly thermal imbalance in multiple borehole configurations. The usefulness of the proposed test cases is illustrated with different GHX models. This comparison exercise has shown that analytical one-dimensional (1D) models compare favourably well with three-dimensional (3D) models for relatively short-simulation periods, where axial effects are not significant. Cyclic heat rejection/collection tests proved to be useful to characterize the accuracy and the computational performance of different load aggregation algorithms. Finally, different spatial superposition methods have been compared for various bore field sizes and configurations and various loads. [less ▲]

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See detailJust Democracy. A Radical Assessment.
Jacquemain, Marc ULg

Scientific conference (2012, February)

This paper is a tentative assessment of the Rawls-Machiavelli program by Philippe Van Paris, who proposes that justice is the main goal of political action (in a Rawlsian perspective) and democracy is ... [more ▼]

This paper is a tentative assessment of the Rawls-Machiavelli program by Philippe Van Paris, who proposes that justice is the main goal of political action (in a Rawlsian perspective) and democracy is only instrumental (the Machiavellian part of the program). The paper adresses three questions to the proposal of Philippe Van Paris : 1) Can democracy be properly defined without a condition of public debate ? 2) Don't "realistic politics" underestimate the margin of possibility we have to change "what people are" and 3) If people overemphasize that part of their interests which is linked to their ethno-national belonging, is it not because alternative political offer is not differentiated enough ? [less ▲]

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See detailA Single Ancient Origin for Prototypical Serine/Arginine-Rich Splicing Factors1[W][OA]
Califice, Sophie; Baurain, Denis ULg; Hanikenne, Marc ULg et al

in Plant Physiology (2012), 158(2), 546-560

Eukaryotic pre-mRNA splicing is a process involving a very complex RNA-protein edifice. Serine/arginine-rich (SR) proteins play essential roles in pre-mRNA constitutive and alternative splicing, and have ... [more ▼]

Eukaryotic pre-mRNA splicing is a process involving a very complex RNA-protein edifice. Serine/arginine-rich (SR) proteins play essential roles in pre-mRNA constitutive and alternative splicing, and have been suggested to be crucial in plant-specific forms of developmental regulation and environmental adaptation. Despite their functional importance, little is known about their origin and evolutionary history. SR splicing factors have a modular organization featuring at least one RRM domain and a C-terminal region enriched in Ser/Arg dipeptides. To investigate the evolution of SR proteins, we infer phylogenies for >12,000 RRM domains representing >200 broadly sampled organisms. Our analyses reveal that the RRM domain is not restricted to eukaryotes and that all prototypical SR proteins share a single ancient origin, including the plant-specific SR45 protein. Based on these findings, we propose a scenario for their diversification into four natural families, each corresponding to a main SR architecture, and a dozen subfamilies, of which we profile both sequence conservation and composition. Finally, using operational criteria for computational discovery and classification, we catalogue SR proteins in 20 model organisms, with a focus on green algae and land plants. Altogether, our study confirms the homogeneity and antiquity of SR splicing factors, while establishing robust phylogenetic relationships between animal and plant proteins, which should enable functional analyses of lesser characterized SR family members, especially in green plants. [less ▲]

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See detailBénéfices démontrés et potentiels de l'administration intraveineuse périopératoire de lidocaïne
Giudice, Véronica; LAUWICK, Séverine ULg; KABA, Abdourahmane ULg et al

in Revue Médicale de Liège (2012), 67(2), 81-84

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See detailInvestigations sur les protéines placentaires extraites des cotylédons fœtaux du Cervus elaphus
Fondja, E.; Okuyama, M.; Petrova, A. et al

Poster (2012, February)

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See detailThe Taoussa project (Mali): an example of effective composite modeling
Erpicum, Sébastien ULg; Dewals, Benjamin ULg; Vuillot, Jean Marie et al

in 4th IAHR International Symposium on Hydraulic Structures (2012, February)

Physical modeling and numerical modeling are two efficient analysis approaches in hydraulic engineering. The interactive application of both methods is obviously the more effective response to most flow ... [more ▼]

Physical modeling and numerical modeling are two efficient analysis approaches in hydraulic engineering. The interactive application of both methods is obviously the more effective response to most flow problems analyses. This paper presents the results of a successful application of such a composite numerical – physical study carried out by the Research Group Hydraulics in Environmental and Civil Engineering (former HACH) of the University of Liège on behalf of Coyne et Bellier (Tractebel Engineering). It concerned, at the stage of detailed draft, the hydraulic study of the Taoussa Project on the Niger River in Mali. The studies, performed in less than 6 months, focused on the flow characteristics at the scale of the reservoir and the river, using the numerical approach, as well as on hydrodynamic details in the spillway using a large scale factor physical model with boundary conditions defined on the basis of numerical modeling. [less ▲]

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See detailA non-linear homogeneous model for bone-like materials under compressive load.
Mengoni, Marlène ULg; Voide, Romain; de Bien, Charlotte ULg et al

in International Journal for Numerical Methods in Biomedical Engineering (2012), 28(2), 334-348

Finite element (FE) models accurately compute the mechanical response of bone and bone-like materials when the models include their detailed microstructure. In order to simulate non-linear behavior, which ... [more ▼]

Finite element (FE) models accurately compute the mechanical response of bone and bone-like materials when the models include their detailed microstructure. In order to simulate non-linear behavior, which currently is only feasible at the expense of extremely high computational costs, coarser models can be used if the local morphology has been linked to the apparent mechanical behavior. The aim of this paper is to implement and validate such a constitutive law. This law is able to capture the non-linear structural behavior of bone-like materials through the use of fabric tensors. It also allows for irreversible strains using an elastoplastic material model incorporating hardening. These features are expressed in a constitutive law based on the anisotropic continuum damage theory coupled with isotropic elastoplasticity in a finite strains framework. This material model was implemented into Metafor, a non-linear FE software. The implementation was validated against experimental data of cylindrical samples subjected to compression. Three materials with bone-like microstructure were tested : aluminum foams of variable density (ERG, Oakland, CA), PLA (polylactic acid) foam (CERM, University of Liège) and cancellous bone tissue of a deer antler (Faculty of Veterinary Medicine, University of Liège). [less ▲]

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See detailResults of kidney transplantation from controlled donors after cardio-circulatory death: a single center experience.
Ledinh, H.; WEEKERS, Laurent ULg; BONVOISIN, Catherine ULg et al

in Transplant International (2012), 25

The aim of this study was to determine results of kidney transplantation (KT) from controlled donation after cardio-circulatory death (DCD). Primary end-points were graft and patient survival, and post ... [more ▼]

The aim of this study was to determine results of kidney transplantation (KT) from controlled donation after cardio-circulatory death (DCD). Primary end-points were graft and patient survival, and post-transplant complications. The influence of delayed graft function (DGF) on graft survival and DGF risk factors were analyzed as secondary end-points. This is a retrospective mono-center review of a consecutive series of 59 DCD-KT performed between 2005 and 2010. Overall graft survival was 96.6%, 94.6%, and 90.7% at 3 months, 1 and 3 years, respectively. Main cause of graft loss was patient's death with a functioning graft. No primary nonfunction grafts. Renal graft function was suboptimal at hospital discharge, but nearly normalized at 3 months. DGF was observed in 45.6% of all DCD-KT. DGF significantly increased postoperative length of hospitalization, but had no deleterious impact on graft function or survival. Donor body mass index >/=30 was the only donor factor that was found to significantly increase the risk of DGF (P < 0.05). Despite a higher rate of DGF, controlled DCD-KT offers a valuable contribution to the pool of deceased donor kidney grafts, with comparable mid-term results to those procured after brain death. [less ▲]

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See detailDéveloppements analytiques appliqués à une thématique d'écologie chimique
Heuskin, Stéphanie ULg

Scientific conference (2012, February)

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See detailPOST-COMBUSTION CO2 CAPTURE: Global Process Simulation and Solvent Degradation
Léonard, Grégoire ULg; Lepaumier, Hélène; Blandina, Fabrice et al

Poster (2012, February)

One of the biggest upcoming challenges concerning both environmental and energy systems engineering is the control and limitation of greenhouse gas emissions due to human activity. Fossil fuels-fired ... [more ▼]

One of the biggest upcoming challenges concerning both environmental and energy systems engineering is the control and limitation of greenhouse gas emissions due to human activity. Fossil fuels-fired power plants are in this context one of the main contributors due to the large amounts of CO2 emitted. Different technologies have been developed for capturing CO2 from such power plants. This work focuses on post-combustion CO2 capture by reactive absorption into amine solvents like monoethanolamine (MEA). The main drawback of this technology is actually the high energy requirement of the process, especially for solvent regeneration. It is then highly interesting to model the capture process so that optimal operating conditions could be approached by simulation thus reducing the number of expensive experimental tests. Thanks to the simulation, it has been possible to identify the most influent process variables and to optimize their value. It was also possible to study the impact of process modifications on the global capture efficiency. The improvements studied allowed for a reduction by up to 14% of the process exergy consumption. Another major drawback of the post-combustion CO2 capture is solvent degradation, which can be due to thermal as well as oxidative mechanisms. Degradation affects the CO2 capture process since it may cause corrosion, foaming and fouling, possibly inducing a decrease of the solvent efficiency and high additional operating costs due to solvent replacement. In order to study degradation of conventional amine solvents as well as degradation of novel solvents, a degradation test rig has been built at the University of Liège in collaboration with the company Laborelec, member of the GDF SUEZ group. First results show that degradation obtained on this lab installation can be compared to degradation results observed on CO2 capture pilot installation. The final objective of this thesis is to make a link between degradation and simulation. Experimental data obtained on the degradation test rig will be implemented into the existing simulation model so that optimal operating conditions considering both process energy efficiency and solvent degradation can be determined. [less ▲]

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