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See detailMeasurement of 3D Room Impulse Responses with a Spherical Microphone Array
Embrechts, Jean-Jacques ULg

in Proceedings of the Euronoise 2015 Congress (2015, June)

Directional room impulse responses (DRIRs) are composed of the sound contributions reaching a given location in the room from a well-defined direction in space. DRIRs can be useful in many applications ... [more ▼]

Directional room impulse responses (DRIRs) are composed of the sound contributions reaching a given location in the room from a well-defined direction in space. DRIRs can be useful in many applications, such as the evaluation of spatial room acoustics parameters, the detection of unwanted specular reflections or the 3D auralization of acoustic spaces. A spherical array containing 16 microphones has been realized to measure DRIRs. The logarithmic sinesweep technique is first applied to measure 16 impulse responses, one for each microphone. A spherical harmonics (SH) decomposition of the sound field is then obtained. Spatial aliasing, placement errors and the ‘white noise gain’ (WNG) have been analysed to define the useful bandwith of this measure, i.e. [250Hz – 4kHz]. The coefficients of the SH decomposition are then processed by some beamforming methods, in order to compute the DRIR in any direction around the spherical array. Time and 3D space representations can be generated. The results obtained in some rooms are illustrated in this paper: it is shown that the combination of the ‘delay-and-sum’ and ‘minimum-variance distorsionless response’ beamforming methods is particularly well suited for the analysis of DRIRs. [less ▲]

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See detailDescription of the research project CIMEDE for the industrial construction of evolutionary, sustainable and economic houses
Duthoit, Fabienne ULg; Embrechts, Jean-Jacques ULg

in Proceedings of the Euronoise 2015 Congress (2015, June)

CIMEDE is a research project supported by the Region of Wallonia (Belgium). It stands for CIMEDE “Construction Industrielle de Maisons Evolutives, Durables et Economiques – industrial construction of ... [more ▼]

CIMEDE is a research project supported by the Region of Wallonia (Belgium). It stands for CIMEDE “Construction Industrielle de Maisons Evolutives, Durables et Economiques – industrial construction of evolutionary, sustainable and economic houses”. Since the materials envisaged for this project are timber and gypsum fibre board, it was necessary to design a constructive principle of lightweight timber frame constructions which meets the industrial, sustainable, evolutionary and economic requirements and also the requirements of the Belgian acoustic standard NBN S01-400-1. First of all, an inventory of constructive elements that are currently used in this type of construction (floors, walls and facades) is presented with their acoustic performances. Then, the laboratory measurements of some samples of floors, facades, interior walls and partition walls are described and discussed. On the basis of the measurement results, several solutions that best meet all criteria were retained and a mock-up was built with these constructive elements. Measurement results on this mock-up are also presented. The final solution for the floor, the partition wall, the interior wall and the facade which meets the acoustic requirements is finally described [less ▲]

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See detailPrésentation de cas pratique - atelier n°2 « Outils et méthodes de formation : quels outils (EAD, MOOC, partage social, manuels...) et quelles méthodes (enseignement mixte, classe inversée, résolution de problèmes, travaux en groupe...) face à des groupes de tailles très variables ? Comment former avec peu de moyens (financiers, humains, matériels) ? »
Pasquet, Coralie ULg

Conference (2015, May 18)

Au cours du premier quadrimestre de l’année académique 2014 - 2015, une nouvelle activité a été proposée aux 280 étudiants inscrits en 3ième année du grade de Bachelier en Médecine à ... [more ▼]

Au cours du premier quadrimestre de l’année académique 2014 - 2015, une nouvelle activité a été proposée aux 280 étudiants inscrits en 3ième année du grade de Bachelier en Médecine à l’Université de Liège, ce dans le cadre du « Module Système Nerveux ». La réalisation progressive de cette activité s'est effectuée exclusivement en ligne. [less ▲]

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See detailValid inequalities for the single arc design problem with set-ups
Agra, Agostinho; Doostmohammadi, Mahdi; Louveaux, Quentin ULg

in Discrete Optimization (2015), 16

We consider a mixed integer set which generalizes two well-known sets: the single node fixed- charge network set and the single arc design set. Such set arises as a relaxation of feasible sets of general ... [more ▼]

We consider a mixed integer set which generalizes two well-known sets: the single node fixed- charge network set and the single arc design set. Such set arises as a relaxation of feasible sets of general mixed integer problems such as lot-sizing and network design problems. We derive several families of valid inequalities that, in particular, generalize the arc resid- ual capacity inequalities and the flow cover inequalities. For the constant capacitated case we provide an extended compact formulation and give a partial description of the convex hull in the original space which is exact under a certain condition. By lifting some basic inequalities we provide some insight on the difficulty of obtaining such a full polyhedral description for the constant capacitated case. Preliminary computational results are presented. [less ▲]

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See detailA comparison of within-season yield prediction algorithms based on crop model behaviour analysis
Dumont, Benjamin ULg; Basso, Bruno; Leemans, Vincent ULg et al

in Agricultural and Forest Meteorology (2015), 204

The development of methodologies for predicting crop yield, in real-time and in response to different agro-climatic conditions, could help to improve the farm management decision process by providing an ... [more ▼]

The development of methodologies for predicting crop yield, in real-time and in response to different agro-climatic conditions, could help to improve the farm management decision process by providing an analysis of expected yields in relation to the costs of investment in particular practices. Based on the use of crop models, this paper compares the ability of two methodologies to predict wheat yield (Triticum aestivum L.), one based on stochastically generated climatic data and the other on mean climate data. It was shown that the numerical experimental yield distribution could be considered as a log-normal distribution. This function is representative of the overall model behaviour. The lack of statistical differences between the numerical realisations and the logistic curve showed in turn that the Generalised Central Limit Theorem (GCLT) was applicable to our case study. In addition, the predictions obtained using both climatic inputs were found to be similar at the inter and intra-annual time-steps, with the root mean square and normalised deviation values below an acceptable level of 10% in 90% of the climatic situations. The predictive observed lead-times were also similar for both approaches. Given (i) the mathematical formulation of crop models, (ii) the applicability of the CLT and GLTC to the climatic inputs and model outputs, respectively, and (iii) the equivalence of the predictive abilities, it could be concluded that the two methodologies were equally valid in terms of yield prediction. These observations indicated that the Convergence in Law Theorem was applicable in this case study. For purely predictive purposes, the findings favoured an algorithm based on a mean climate approach, which needed far less time (by 300-fold) to run and converge on same predictive lead time than the stochastic approach. [less ▲]

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See detailExperimental study and phenomenological modeling of the quasi-static mechanical behavior of Ti6Al4V at room temperature
Gilles, Gaëtan ULg

Doctoral thesis (2015)

The work aims to characterize the quasi-static mechanical behavior of the Ti6Al4V titanium alloy at room temperature and to describe it by a phenomenological model. The thesis is divided in four parts ... [more ▼]

The work aims to characterize the quasi-static mechanical behavior of the Ti6Al4V titanium alloy at room temperature and to describe it by a phenomenological model. The thesis is divided in four parts. The first one presents a literature review of the basic properties of titanium and its alloys (crystal structure, classification, deformation mechanisms), then it focuses on the specific mechanical features of Ti6Al4V. It also proposes a state of art in the field of the phenomenological constitutive laws used to model the mechanical behaviors of metals. The second part deals with the experimental campaign conducted on a 0.6 mm thick Ti6Al4V sheet. The devices and the tests are first described before giving the test results. The campaign includes experiments with monotonic and complex strain paths (tension, compression, simple shear, plane strain, Bauschinger tests, deep-drawing processes, layer compression tests). The experimental results show that the material displays anisotropy in yield stress, r-ratios and hardening, as well as a strength differential effect between tension and compression. The third part describes the implementation of the yield criteria CPB06exn in the non-linear finite element code LAGAMINE developed in MSM team. These criteria are selected to model the yield locus of Ti6Al4V since they are able to take into account both the anisotropy and the tension-compression asymmetry exhibited by the alloy. Several parameter identifications are performed using the classical simulated annealing algorithm. They determine that CPB06ex2 is required to represent the yield surface. The criterion is next associated to different hardening formulations: (1) Voce isotropic law; (2) mixed Voce isotropic – Armstrong-Frederick kinematic law; (3) model taking into account the evolution of the yield locus shape with the deformation. The identification of the hardening parameters is achieved from the monotonic and Bauschinger tests either by inverse method, or by the simulated annealing method. The last part of the thesis proposed a validation of the different modelings in the case of the layer compression tests and the deep-drawing processes. [less ▲]

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See detailGraded-commutative nonassociative algebras: higher octonions and Krichever-Novikov superalgebras; their structures, combinatorics and non-trivial cocycles.
Kreusch, Marie ULg

Doctoral thesis (2015)

This dissertation consists of two parts. The first one is the study of a series of real (resp. complex) noncommutative and nonassociative algebras $\bbO_{p,q}$ (resp. $\bbO_{n}$) generalizing the algebra ... [more ▼]

This dissertation consists of two parts. The first one is the study of a series of real (resp. complex) noncommutative and nonassociative algebras $\bbO_{p,q}$ (resp. $\bbO_{n}$) generalizing the algebra of octonion numbers $\bbO$. This generalization is similar to the one of the algebra of quaternion numbers in Clifford algebras. Introduced by Morier-Genoud and Ovsienko, these algebras have a natural $\bbZ_2^n$-grading ($p+q =n$), and they are characterized by a cubic form over the field $\bbZ_2.$ We establish all the possible isomorphisms between the algebras $\bbO_{p,q}$ preserving the structure of $\bbZ_2^n$-graded algebra. The classification table of $\bbO_{p,q}$ is quite similar to that of the real Clifford algebras $\cC l_{p,q}$, the main difference is that the algebras $\bbO_{n,0}$ and $\bbO_{0,n}$ are exceptional. We also provide a periodicity for the algebras $\bbO_n$ and $\bbO_{p,q}$ analogous to the periodicity for the Clifford algebras $\cC l_{n}$ and $\cC l_{p,q}$. In the second part we consider superalgebras of Krichever-Novikov (K-N) type. Krichever and Novikov introduced a family of Lie algebras with two marked points generalizing the Witt algebra and its central extension called the Virasoro algebra. The K-N Lie (super)algebras for more than two marked points were studied by Schlichenmaier. In particular, he extended the explicit formula of $2$-cocycles due to Krichever and Novikov to multiple-point situation. We give an explicit construction of central extensions of Lie superalgebras of K-N type and we establish a $1$-cocycle with values in its dual space. In the case of Jordan superalgebras related to superalgebras of K-N type, we calculate a 1-cocycle with coefficients in the dual space. [less ▲]

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See detailImpact of Aphasia on Consciousness Assessment: A Cross-Sectional Study.
Schnakers, C; Bessou, H; Rubi-Fessen, I et al

in Neurorehabilitation & Neural Repair (2015), 29

BACKGROUND: . Previous findings suggest that language disorders may occur in severely brain-injured patients and could interfere with behavioral assessments of consciousness. However, no study ... [more ▼]

BACKGROUND: . Previous findings suggest that language disorders may occur in severely brain-injured patients and could interfere with behavioral assessments of consciousness. However, no study investigated to what extent language impairment could affect patients' behavioral responses. OBJECTIVE: . To estimate the impact of receptive and/or productive language impairments on consciousness assessment. METHODS: . Twenty-four acute and subacute stroke patients with different types of aphasia (global, n = 11; Broca, n = 4; Wernicke, n = 3; anomic, n = 4; mixed, n = 2) were recruited in neurology and neurosurgery units as well as in rehabilitation centers. The Coma Recovery Scale-Revised (CRS-R) was administered. RESULTS: . We observed that 25% (6 out of 24) of stroke patients with a diagnosis of aphasia and 54% (6 out of 11) of patients with a diagnosis of global aphasia did not reach the maximal CRS-R total score of 23. An underestimation of the consciousness level was observed in 3 patients with global aphasia who could have been misdiagnosed as being in a minimally conscious state, even in the absence of any documented period of coma. More precisely, lower subscores were observed on the communication, motor, oromotor, and arousal subscales. CONCLUSION: . Consciousness assessment may be complicated by the co-occurrence of severe language deficits. This stresses the importance of developing new tools or identifying items in existing scales, which may allow the detection of language impairment in severely brain-injured patients. [less ▲]

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See detailVariogram-based inversion of time-lapse electrical resistivity data: development and application to a thermal tracing experiment
Hermans, Thomas ULg; Nguyen, Frédéric ULg

Poster (2015, April 15)

Electrical resistivity tomography (ERT) has become a popular imaging methodology in a broad range of applications given its large sensitivity to subsurface parameters and its relative simplicity to ... [more ▼]

Electrical resistivity tomography (ERT) has become a popular imaging methodology in a broad range of applications given its large sensitivity to subsurface parameters and its relative simplicity to implement. More particularly, time-lapse ERT is now increasingly used for monitoring purposes in many contexts such as water content, permafrost, landslide, seawater intrusion, solute transport or heat transport experiments. Specific inversion schemes have been developed for time-lapse data sets. However, in contrast with static inversions for which many techniques including geostatistical, minimum support or structural inversion are commonly applied, most of the methodologies for time-lapse inversion still rely on non-physically based spatial and/or temporal smoothing of the parameters or parameter changes. In this work, we propose a time-lapse ERT inversion scheme based on the difference inversion scheme. We replace the standard smoothness-constraint regularization operator by the parameter change covariance matrix. This operator takes into account the correlation between changes in resistivity at different locations through a variogram computed using independent data (e.g., electromagnetic logs). It may vary for subsequent time-steps if the correlation length is time-dependent. The methodology is first validated and compared to the standard smoothness-constraint inversion using a synthetic benchmark simulating the injection of a conductive tracer into a homogeneous aquifer inducing changes in resistivity values of known correlation length. We analyze the influence of the assumed correlation length on inversion results. Globally, the method yields better results than the traditional smoothness constraint inversion. Even if a wrong correlation length is assumed, the method performs as well as the smoothness constraint since the regularization operator balances the weight given to the model constraint functional in the objective function. Then the methodology is successfully applied to a heat injection and pumping experiment in an alluvial aquifer. The comparison with direct measurements in boreholes (temperature loggers and distributed temperature sensing optic fibres) shows that ERT-derived temperatures and breakthrough curves image reliably the heat plume through time (increasing part of the curve, maximum and tail are correctly retrieved) and space (lateral variations of temperature are observed) with less spatial smoothing than standard methods. The development of new regularization operators for time-lapse inversion of ERT data is necessary given the broad range of applications where ERT monitoring is used. In many studies, independent data are available to derive geostatistical parameters that can be subsequently used to regularize geophysical inversions. In the future, the integration of spatio-temporal variograms into existing 4D inversion schemes should further improve ERT time-lapse imaging. [less ▲]

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See detailRegularized focusing inversion of time-lapse electrical resistivity data: an approach to parametrize the minimum gradient support functional
Nguyen, Frédéric ULg; Hermans, Thomas ULg

Poster (2015, April 15)

Inversion of time-lapse resistivity data allows obtaining ‘snapshots’ of changes occurring in monitored systems for applications such as aquifer storage, geothermal heat exchange, site remediation or ... [more ▼]

Inversion of time-lapse resistivity data allows obtaining ‘snapshots’ of changes occurring in monitored systems for applications such as aquifer storage, geothermal heat exchange, site remediation or tracer tests. Based on these snapshots, one can infer qualitative information on the location and morphology of changes occurring in the subsurface but also quantitative estimates on the degree of changes in certain property such as temperature or total dissolved solid content. Analysis of these changes can provide direct insight into flow and transport and associated processes and controlling parameters. However, the reliability of the analysis is dependent on survey geometry, measurement schemes, data error, and regularization. Survey design parameters may be optimized prior to the monitoring survey. Regularization, on the other hand, may be chosen depending on available information collected during the monitoring. Common approaches consider smoothing model changes both in space and time but it is often needed to obtain a sharp temporal anomaly, for example in fractured aquifers. We here propose to use the alternative regularization approach based on minimum gradient support (MGS) (Zhdanov, 2002) for time-lapse surveys which will focus the changes in tomograms snapshots. MGS will limit the occurrences of changes in electrical resistivity but will also restrict the variations of these changes inside the different zones. A common difficulty encountered by practitioners in this type of regularization is the choice of an additional parameter, the so-called , required to define the MGS functional. To the best of our knowledge, there is no commonly accepted or standard methodology to optimize the MGS parameter . The inversion algorithm used in this study is CRTomo (Kemna 2000). It uses a Gauss-Newton scheme to iteratively minimize an objective function which consists of a data misfit functional and a model constraint functional. A univariate line search is performed at each Gauss-Newton iteration step to find the optimum value of the regularization parameter  which minimizes the data misfit as a function of  while the data misfit is above the desired value and yields the desired target misfit (root-mean square value of error-weighted data misfit equal to 1) at the last iteration for a maximum value of . We propose here to optimize the  of the MGS functional by considering a univariate line search at the first iteration to find the  that minimizes the data misfit. The parameter is then kept constant during the Gauss-Newton iterative scheme. In this contribution, we validate our approach on a numerical benchmark and apply it successfully on a case study in the context of salt tracers in fractured aquifers. Zhdanov M.S. 2002. Geophysical Inverse Theory and Regularization Problems. Elsevier, Amsterdam, 628 p. Kemna A. 2000. Tomographic Inversion of Complex Resistivity - Theory and Application. PhD Thesis, Ruhr University Bochum. [less ▲]

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See detailTracking Middleboxes in the Mobile World with TraceboxAndroid
Thirion, Valentin; Edeline, Korian ULg; Donnet, Benoît ULg

in 7th International Workshop on Traffic Monitoring and Analysis (TMA) (2015, April)

Middleboxes are largely deployed over cellular networks. It is known that they might disrupt network performance, expose users to security issues, and harm protocols deployability. Further, hardly any ... [more ▼]

Middleboxes are largely deployed over cellular networks. It is known that they might disrupt network performance, expose users to security issues, and harm protocols deployability. Further, hardly any network measurements tools for smartphones are able to infer middlebox behaviors, specially if one cannot control both ends of a path. In this paper, we present TraceboxAndroid a proof-of-concept measurement application for Android mobile devices implementing the tracebox algorithm. It aims at diagnosing middlebox-impaired paths by detecting and locating rewriting middleboxes. We analyze a dataset sample to highlight the range of opportunities offered by TraceboxAndroid. We show that TraceboxAndroid can be useful for mobile users as well as for the research community. [less ▲]

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See detailThe words of prevention, part II: ten terms in the realm of quaternary prevention
Jamoulle, Marc ULg; Gavilan, Enrique; Cardoso, Raquel Val et al

in Revista Brasileira de Medicina de Família e Comunidade (2015)

ABSTRACT Objective: This part II article about the ‘words of prevention’ presents in a terminological way the content of ten current concepts used in the prevention domain which are closely linked to ... [more ▼]

ABSTRACT Objective: This part II article about the ‘words of prevention’ presents in a terminological way the content of ten current concepts used in the prevention domain which are closely linked to quaternary prevention: (1) overinformation, (2) overdiagnosis, (3) medically unexplained symptoms, (4) overmedicalisation, (5) incidentaloma, (6) overscreening, (7) overtreatment, (8) shared decision making, (9) deprescribing, and (10) disease mongering. Methods: with the support of the laboratory team of the University of Rouen, France, which is dedicated to medical terminology and semantic relationships, it was possible to utilize a graphic user interface (called DBGUI) allowing the construction of links for each of chosen terms, and making automatic links to MeSH, if any. Those concepts are analyzed in their environment in current literature, as well as in their MeSH counterparts, if any, and related semantic online terminologies. Results and Discussion: The rules in terminological development aspire to cover the whole field of a concept and in the meantime, it helps to avoid the noise due to proxy and not exactly related issues. This refers to exhaustivity and specificity in information retrieval. Our finds show that referring to MeSH only in information retrieval in General Practice/Family medicine can induce much noise and poor adequacy to the subject investigated. Conclusion: Gathering concepts in specially prepared terminologies for further development of ontologies is a necessity to enter in the semantic web area and the era of distributed data. [less ▲]

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See detailThe words of prevention, part I: changing the model
Jamoulle, Marc ULg; Gavilan, Enrique; Cardoso, Raquel Val et al

in Revista Brasileira de Medicina de Família e Comunidade (2015)

ABSTRACT Objective: This part I article explores the different meanings of relevant keywords for General Practice/Family Medicine (GP/FM) in the prevention domain. The aim is to contribute to information ... [more ▼]

ABSTRACT Objective: This part I article explores the different meanings of relevant keywords for General Practice/Family Medicine (GP/FM) in the prevention domain. The aim is to contribute to information process in GP/FM by keeping in line with the main terms used in health care organization. Methods: Important keywords for GP/FM in the prevention domain were selected. Then, a search was carried out on the main sources in GP/FM databases, as well as in Medical Subject Heading and major terminological databases available online. Results and Discussion: There is discrepancy between the conceptual contents of major prevention models amongst the usual bibliographic sources of knowledge in GP/FM in particular and medicine in general. Conclusion: For GP/FM, distribution of preventive activities is now firmly established on a new constructivist model, privileging the doctor-patient relationships and introducing a cybernetic thinking on the health care activities with a special commitment to ethics and the positive duty of beneficence. [less ▲]

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See detailPrevenção quaternária: primeiro não causar dano - Editorial
Jamoulle, Marc ULg

in Revista Brasileira de Medicina de Família e Comunidade (2015)

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See detailQuaternary prevention: first, do not harm - Editorial
Jamoulle, Marc ULg

in Revista Brasileira de Medicina de Família e Comunidade (2015)

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See detailManuels de langues et risques d'inégalités
Simons, Germain ULg; Delbrassine, Daniel ULg; Van Hoof, Florence ULg

in Didactiques en pratique (2015), (1),

Dans cet article synthétique, les auteurs relèvent quelques caractéristiques de certains manuels de langues contemporains et démontrent en quoi celles-ci présentent des risques d'inégalités pour les ... [more ▼]

Dans cet article synthétique, les auteurs relèvent quelques caractéristiques de certains manuels de langues contemporains et démontrent en quoi celles-ci présentent des risques d'inégalités pour les apprenants [less ▲]

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See detailEditorial du n°1 de la revue "Didactiques en pratique"
Simons, Germain ULg; Beckers, Jacqueline ULg; Poffé, Corentin ULg

in Didactiques en pratique (2015)

Ce premier éditorial de la nouvelle revue du Cifen :"Didactique en pratique" présente le contenu de ce numéro et propose une mise en perspective théorique de la problématique abordée lors de l'Université ... [more ▼]

Ce premier éditorial de la nouvelle revue du Cifen :"Didactique en pratique" présente le contenu de ce numéro et propose une mise en perspective théorique de la problématique abordée lors de l'Université d'été 2014 : "Outils didactiques et (in)égalités". Ce premier numéro est principalement consacré à la publication des Actes de l'Université d'été 2014, mais il évoque aussi la première journée de rencontre officielle entre le Cifen et les maitres de stages. [less ▲]

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See detailMise en perspective de l'après-midi de rencontre avec les maîtres de stages du Cifen
Simons, Germain ULg

in Didactiques en pratique (2015), 1

Ce texte est le discours du Président du Cifen qui a été prononcé à l'occasion de la première journée officielle de rencontre entre le Centre et les maitres de stages (5 novembre 2014). Ce discours ... [more ▼]

Ce texte est le discours du Président du Cifen qui a été prononcé à l'occasion de la première journée officielle de rencontre entre le Centre et les maitres de stages (5 novembre 2014). Ce discours succinct reprend la question qui a servi de fil rouge à cette journée : "Comment collaborer efficacement pour accompagner au mieux nos stagiaires ?" et en détaille chaque composante. [less ▲]

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