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See detail"Giant Planets Aurorae" - Europlanet RI Science Case in the Working Packages
Rucker, M Scherf H O; Blanc, M.; André, N. et al

Conference (2010)

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See detailEnjeux fonciers et exploitation du bois-énergie en périphérie de Kinshasa, RDC
Vermeulen, Cédric ULg; Mutambwe, Shango; Dubiez, Emilien et al

Conference (2010)

L’identification des acteurs, des finages, des dynamiques sociales locales et du rapport à la terre et aux ressources naturelles constitue un préalable à toute intervention dans les zones péri-urbaines ... [more ▼]

L’identification des acteurs, des finages, des dynamiques sociales locales et du rapport à la terre et aux ressources naturelles constitue un préalable à toute intervention dans les zones péri-urbaines soumises à forte pression anthropique. En République Démocratique du Congo, la capitale Kinshasa, mégapole en pleine extension, engendre une pression considérable sur les ressources ligneuses dans les finages des villages situés dans sa grande périphérie. La présente communication décrit les rapports des acteurs aux espaces-ressources dans deux zones (Bas-Congo et plateau Bateke) situées en périphérie de cette ville, zones considérées comme des bassins d’approvisionnement en bois-énergie. Les deux sites différent en termes de pression foncière (très élevée dans le Bas-congo, centrée sur les forêts galerie sur les plateaux Bateke) mais présentent les mêmes faciès de surexploitation des ressources ligneuses. Dans les deux cas, la gestion locale, aux mains des chefs de villages ou des chefs de lignée, a failli. La volonté de reboisement est aussi grande au Bas-Congo qu’elle semble moins développée sur les plateaux. Dans les deux situations, la pratique du retour rapide sur la formation végétale (pour l’agriculture ou pour l’exploitation du charbon de bois) hypothèque la possibilité de régénération de la plupart des essences locales. [less ▲]

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See detailEffect of rosemary extract and related flavonoid carnosol on chondro-protection and on the bone-cartilage crosstalk
Horcajada, Marie-Noelle; Sanchez, Christelle ULg; Scalfo, Fanny et al

Conference (2010)

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See detailComment la confiance envers le supérieur hiérarchique influence la créativité et le voice des employés. Le rôle du sentiment de responsabilité.
De Zanet, Fabrice ULg

Conference (2010)

Les entreprises attendent de plus en plus de leurs employés qu’ils soient proactifs et prennent des initiatives. Or, un employé qui est proactif prend un risque, car son initiative peut être perçue ... [more ▼]

Les entreprises attendent de plus en plus de leurs employés qu’ils soient proactifs et prennent des initiatives. Or, un employé qui est proactif prend un risque, car son initiative peut être perçue négativement par la hiérarchie. Detert et Burris (2007) postulent ainsi que la décision d’être proactif résulte d’un calcul coûts-bénéfices. Par ailleurs, un employé est d’autant plus enclin à prendre des risques qu’il fait confiance à son supérieur hiérarchique (Mayer, Davis, & Schoorman, 1995). En conséquence, la confiance des employés envers leur supérieur hiérarchique est certainement un facteur clé dans l’adoption par les employés de comportements proactifs. Néanmoins, il reste encore à comprendre le mécanisme à travers lequel la confiance envers le supérieur hiérarchique influence la proactivité des employés. L’objectif de cet article est de montrer comment la confiance des employés envers le supérieur hiérarchique influence - via le sentiment de responsabilité des employés - l’adoption de deux comportements proactifs, à savoir la créativité, c'est-à-dire le fait de proposer des idées innovantes et utiles, et le voice, c'est-à-dire le fait de faire remonter des informations potentiellement critiques à propos du fonctionnement de l’organisation. Les analyses réalisées sur 111 paires employés-supérieurs montrent que la confiance envers le supérieur hiérarchique agit sur le niveau créativité et de voice des employés et que cette influence est médiée par le fait que ces derniers se sentent davantage responsables d’apporter des changements constructifs dans leur travail. [less ▲]

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See detailLa biopolitique et les nouveaux pouvoirs sur la vie
Caeymaex, Florence ULg

Conference (2010)

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See detailStrengthening local innovations in rice processing through video in Benin
Zossou, Espérance; Van Mele, P.; Vodouhe, D. S. et al

Conference (2010)

In Africa, rice processing provides employment for many rural people. A survey on local rice processing methods in the north, central and south of Benin shows that local rice is often parboiled before ... [more ▼]

In Africa, rice processing provides employment for many rural people. A survey on local rice processing methods in the north, central and south of Benin shows that local rice is often parboiled before milling. Parboiling is a transformation process that enhances the quality of rice. This important income generating activity is exclusively done by women from rice producing communities. In Benin, the traditional parboiling method is still prevailing and does not lead to quality rice. To address this, an improved rice parboiling technology was developed. AfricaRice subsequently developed a video where rural women explain how to use this improved technology. Four NGOs in central Benin publicly screened the video in 80 villages. After women watched the video, they started using the improved parboiler equipment individually or collectively. Women who didn’t have the financial support to buy the improved equipment understood its principle and developed creative solutions based on the idea of pre-cooking paddy with steam. Video watching also made women pay attention to reducing the loss of steam and to use local resources innovatively to conserve energy. Women also improved the quality of their parboiled rice by removing dirt, properly washing rice and drying rice on tarpaulins. On the other hand, in the north and south of Benin where there were no public video screenings, the traditional rice parboiling method is still predominant. This study shows the potential of farmer-to-farmer video to improve farmers’ practices and their attitudes to work collectively in agro-processing and marketing. [less ▲]

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See detailMorphemes in the mind: Are there graded effects of semantic similarity on morphological processing in children?
Deacon, Hélène; Downing, Jennifer; Gonnerman, Laura et al

Conference (2010)

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See detailSozialrechtliche Aspekte der Staatenlosigkeit
Thevissen, Patrick ULg

Conference (2010)

Detailed reference viewed: 11 (0 ULg)
Peer Reviewed
See detailInterplay between non-death and death TNFR in inflammation.
Dejardin, Emmanuel ULg

Conference (2010)

Detailed reference viewed: 9 (4 ULg)
See detailEnsemble-based assimilation of high-frequency radar surface currents in regional ocean models
Barth, Alexander ULg; Alvera Azcarate, Aïda ULg; Beckers, Jean-Marie ULg et al

Conference (2010)

The results of coastal ocean models depend critically on the accuracy of boundary and initial conditions and atmospheric forcing. The precision of coastal ocean models is limited among others by ... [more ▼]

The results of coastal ocean models depend critically on the accuracy of boundary and initial conditions and atmospheric forcing. The precision of coastal ocean models is limited among others by uncertainty in those forcing fields. Since high-frequency (HF) radar installations provide measurements over a relatively large area, the assimilation of these data has a high potential to reduce the errors in ocean models and to provide a dynamically consistent estimation of the ocean circulation. The assimilation of HF radar data is not without its own challenges: the spatial variation of the surface currents uncertainty, the high temporal resolution of HF radar data, the simultaneous presence of a wide range of processes with distinct spatial and temporal scales (tides and other surface gravity waves, mesoscale and wind-driven circulation), and the generally strong sensitivity of regional models to errors in the boundary conditions and atmospheric forcings. These processess are important aspects to consider in the application of data assimilation methods to HF radar measurements. The results of two data assimilation experiments on the West Florida Shelf (WFS) and the German Bight are presented. HF radar currents are assimilated in a nested West Florida Shelf based on an ensemble of model realizations with different wind forcings. The model is sequentially updated and a filter is implemented to reduce spurious surface-gravity waves. Results of the WFS model assimilating surface currents show an improvement of the model currents not only at the surface but also at depth compared to independent ADCP observations. This West Florida Shelf assimilation experiment does not include tides. Tides are not generated within the domain, but are rather propagated inside the domain through the boundary conditions. The potential of using HF radar data to reduce errors in tidal boundary conditions is shown in a model setup of the German Bight. For improving the modeled tidal variability it is not sufficient to update the model state without updating the boundary conditions. An ensemble smoother to improve the tidal boundary values is presented and validated with independent HF radar measurements and tide-gage data. The ensemble-scheme is also applied to improve the wind forcing by assimilation of surface currents. The improvement of the analyzed wind forcing is assessed by using in-situ wind measurements. [less ▲]

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See detailPerceiving prosodic prominence in a second language
Rasier, Laurent ULg; Caspers, Johanneke; Van Heuven, Vincent

Conference (2010)

Detailed reference viewed: 17 (0 ULg)
See detailLes dispositifs en faveur de l’égalité hommes-femmes.
Cornet, Annie ULg

Conference (2010)

Detailed reference viewed: 18 (2 ULg)
Peer Reviewed
See detailStudy of the degradation mechanisms of Prussian Blue in paint layers by X-ray absorption spectroscopy
Samain, Louise ULg; Silversmit, Geert; Vekemans, Bart et al

Conference (2010)

Detailed reference viewed: 63 (8 ULg)
See detailla gestion des âges
Cornet, Annie ULg

Conference (2010)

Detailed reference viewed: 48 (18 ULg)
Peer Reviewed
See detailProcess mineralogy and automated phase identification in mixed copper ores at Kansanshi (Zambia)
Kottgen; Bastin, David ULg; Dufrane, Florent et al

Conference (2010)

Detailed reference viewed: 16 (0 ULg)
Peer Reviewed
See detailSocial enterprise
Defourny, Jacques ULg

Conference (2010)

Detailed reference viewed: 19 (4 ULg)
See detailElectronic spectroscopy of nucleic acids in the gas phase
Gabelica, Valérie ULg; Rosu, Frédéric ULg; Joly, Laure ULg et al

Conference (2010)

DNA polyanions trapped in a mass spectrometer undergo electron detachment following UV irradiation. Photodetachment is a single-photon process. Its efficiency depends on the nature of the DNA bases, the ... [more ▼]

DNA polyanions trapped in a mass spectrometer undergo electron detachment following UV irradiation. Photodetachment is a single-photon process. Its efficiency depends on the nature of the DNA bases, the ion's charge, and the excitation wavelength. Photodetachment can therefore be used to perform ion spectroscopy experiments, which probe electronic excitation within the initial charge state of the nucleic acids. Ion spectroscopy experiments on trapped nucleic acid cations and anions were performed from 4 to 20 eV using an OPO laser or using synchrotron radiation. Photoelectron spectroscopy experiments were also performed on multiply charged anions to probe direct detachment cross sections and electronic excitations within the final charge. The electronic spectra obtained from photodetachment integral cross sections show several resonances, provided that the photon energy is larger than the electron binding energy. We will also discuss whether the electronic spectra obtained via photodetachment can be used to probe gas phase ion structure. [less ▲]

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See detailTool use and site function in the European Middle Palaeolithic
Rots, Veerle ULg

Conference (2010)

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See detailEnsemble smoother for optimizing tidal boundary conditions and wind forcing by assimilation of High-Frequency Radar surface currents measurements of the German Bight
Barth, Alexander ULg; Alvera Azcarate, Aïda ULg; Staneva, Joanna et al

Conference (2010)

An ensemble smoother scheme is presented to assimilate HF radar surface currents to improve tidal boundary conditions and wind forcings of a circulation model of the German Bight. To create an ensemble of ... [more ▼]

An ensemble smoother scheme is presented to assimilate HF radar surface currents to improve tidal boundary conditions and wind forcings of a circulation model of the German Bight. To create an ensemble of dynamically realistic tidal boundary conditions, a cost function is formulated which is directly related to the probability of each perturbation. This cost function ensures that the perturbations are spatially smooth and that the structure of the perturbations satisfies approximately the harmonic linearized shallow water equations. Based on those perturbations an ensemble simulation is carried out using the full three-dimensional General Estuarine Ocean Model (GETM). Optimized boundary values are obtained using all observations within the assimilation period using the covariances of the ensemble simulation. The approach acts like a smoother scheme since all observations are taken into account. Since the scheme aims to derive the optimal perturbation, it might be called Ensemble Perturbation Smoother. The final analysis is obtained by rerunning the model using the optimal perturbation to the boundary conditions. The analyzed model solution satisfies thus the model equations exactly and does not suffer from spurious adjustments often observed with sequential assimilation schemes. Model results are also compared to independent tide gage data. The assimilation did also reduce the model error compared to those sea level observations. The same scheme has also been used to correct surface winds. Surface winds are crucial for accurately modeling the marine circulation in coastal waters. The method is validated directly by comparing the analyzed wind speed to in situ measurements and indirectly by assessing the impact of the corrected winds on sea surface temperature (SST) relative to satellite SST. [less ▲]

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See detailIs left ventricular longitudinal function related to metabolic abnormalities and fat distribution?
Laret, V; Magne, Julien ULg; O'Connor, K et al

Conference (2010)

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See detailOptimal design of a CO2 absorption unit and assessment of solvent degradation
Léonard, Grégoire ULg

Conference (2010)

Presentation of the main research fields of my PhD thesis at the University of Liège

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See detail"Hypermoderne" le mangeur belge ?
Duquesne, Brigitte ULg

Conference (2010)

Detailed reference viewed: 113 (22 ULg)
See detailSaturn's secondary auroral ring
Grodent, Denis ULg; Radioti, Aikaterini ULg; Bonfond, Bertrand ULg et al

Conference (2010)

Not Available

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See detailImproved Aid Effectiveness but Waiting for Results: What are the Missing Links?
Paul, Elisabeth ULg; Dujardin, Bruno; Ireland, Megan et al

Conference (2010)

Objectives: The objective is to analyze the content of the Paris Declaration (PD) on aid effectiveness and Accra Agenda for Action (AAA), and their practical implications for the health sector in aid ... [more ▼]

Objectives: The objective is to analyze the content of the Paris Declaration (PD) on aid effectiveness and Accra Agenda for Action (AAA), and their practical implications for the health sector in aid-recipient countries. Design/methods: The study draws on (i) a critical analysis of the two declarations, (ii) a review of the literature on their implementation and (iii) interviews of people in charge of implementing them – both donors and government representatives. Results: The PD and AAA both have a "missing link" between, on the one hand, international cooperation policies (five pillars of the PD) and national development (health) plans; and, on the other hand, the operational level that is supposed to deliver results. They presume that by changing aid management and respecting a few principles, development results will automatically improve as through a "black box". The influence of international and national policies over health systems, service providers’ behaviour and health impacts is not treated at all by the agenda for aid effectiveness, while it is crucial for its success. Moreover, that agenda is mostly dealt with at a too high level (international forums or at best national sector level), thus deepening the disconnexion from field realities. Conclusions/policy implications: This "missing link" entails the risk that, if the "black box" does not perform as expected – that is, if health systems and health service providers’ behaviour do not evolve in a positive way – and health impacts do not improve, the aid effectiveness agenda may be rejected at all, notwithstanding its (incomplete) added value. Hence the need to closely monitor the processes of national health plans implementation, so in order to better understand how these processes are translated on the field and what could be done to ensure that health service delivery and health results ultimately improve. [less ▲]

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See detailDisplacement Extrapolation Method : An alternative to J-integral for stress intensity factors computation using X-FEM
Minnebo, Hans; Majérus, Julien; Noels, Ludovic ULg

Conference (2010)

Stress intensity factors (SIFs) computation techniques based on J-integral methods [1] are widely used in finite element codes. However, the Displacement Extrapolation Method (DEM) [2] is an alternative ... [more ▼]

Stress intensity factors (SIFs) computation techniques based on J-integral methods [1] are widely used in finite element codes. However, the Displacement Extrapolation Method (DEM) [2] is an alternative way to compute them. The idea is to process an extrapolation based on the relative displacement of the crack face nodes. This method is generally less accurate than integral methods, but it requires much less computational resources. The method is well documented and is implemented in some finite element software. The X-FEM introduced in [3] is suited for crack problems. However, the literature on DEM in the X-FEM case seems to be non-existent in the present time. This paper tries to fill this lack in the literature by describing a new method using X-FEM. The approach followed here is only developed for Linear Elastic Fracture Mechanics. Note that the finite element software Code_Aster [4] already computes SIFs with DEM in X-FEM, but in a slightly different way. [less ▲]

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See detailUnlock sytemic locking? From conversion towards transition
Stassart, Pierre M ULg

Conference (2010)

The potential sectoral (food chain) transition approach suffers from a strong regimen’s irreversibility. In this paper we consider the question of cooperation regime transformation. Indeed in our case ... [more ▼]

The potential sectoral (food chain) transition approach suffers from a strong regimen’s irreversibility. In this paper we consider the question of cooperation regime transformation. Indeed in our case, the lock-in issue also proved to have a professional dimension linked to the cooperation regime. While the “filière” quality convention (Gomez 1994) could re-frame the traditional relationships between different members of the “filière,” this potential transformation was blocked by the strongest professional/sectoral convention. Professional conventions (Allaire 2004) are competency conventions that define and qualify “good” work within a set of rules. Professional conventions may be destabilized by transforming legitimacy systems through a territorial (rather than sectoral) approach and as a consequence start to overcome the socio-technical lock-in. Interactions between weak pressure at the landscape (macro) level (EU), niche (micro) level, and knowledge coming from the previous intervention research created space for regime destabilization (Geels & Schot 2007b). Local stakeholders (institutions) joined with local actors (consumers-citizens, and naturalists) to create room for a learning process and let the “Gaume Grassland Steer” niche experiment emerge. [less ▲]

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See detailA survey of honey bee colony losses in Belgium, fall 2008 to spring 2009
Nguyen, Bach Kim ULg; Mignon, Jacques ULg; Laget, D. et al

Conference (2010)

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See detailDeveloping the HRH Policy and Plan in Mali
Paul, Elisabeth ULg; Samaké, Salif

Conference (2010)

Context: Deficient HRH management – especially insufficient training and motivation, and adverse distribution of qualified staff countrywide, at the expense of poor and remote areas – has been identified ... [more ▼]

Context: Deficient HRH management – especially insufficient training and motivation, and adverse distribution of qualified staff countrywide, at the expense of poor and remote areas – has been identified for over a decade as one major constraint for the implementation of Mali's national health policy. Main objective: The HRH policy aims to define a coherent framework for the ministry of health (MoH) and its partners in order to ensure the harmonious development, distribution, management and motivation of health staff so as to ultimately improve health results. The policy is translated into an operational plan dealing specifically with training, recruitment, motivation, and career management. Methodology: The HRH policy and plan were developed by a core team under the leadership of the Planning Department of the MoH, with the involvement from other departments of the MoH, the ministries in charge of finance (MoF) and civil service (MoCS), and donors. After analyzing existing studies and data, the diagnosis over the major problems to be tackled was done. This allowed identifying the main orientations of the policy, which were then translated into strategies and interventions, and then costed. Once the policy and plan have been drafted by the core team, they have been circulated to all departments and partners and discussed in several meetings with different stakeholders at central level. After integrating comments from these meetings, the MoH organized a validation workshop with very broad participation (including the operational level, private sector, and civil society) so as to ensure ownership. Final amendments were negotiated with the MoF and MoCS in order to be adopted as a national policy by the Counsel of Ministers by the end of 2009. Results: The HRH policy and plan now benefit from wide political support by major stakeholders. Yet, implementation still has been delayed because of the management modalities at operational level still need to be definitively agreed upon. Conclusion: The inclusive development process has been necessary to move on with the complex and highly sensitive issue of HRH management, and to get the support from MoF, MoSC and donors who are supposed to contribute to its financing. [less ▲]

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See detailDynamique spatiale de rejet des déchets au sein des fourmilières Myrmica rubra
Diez, Lise; Lejeune, Philippe ULg; Detrain, Claire

Conference (2010)

La vie en société de milliers d’individus apparentés dans un milieu confiné augmente le risque de transmission des pathogènes. Par le biais de comportements hygiéniques collectifs tels quel le rejet des ... [more ▼]

La vie en société de milliers d’individus apparentés dans un milieu confiné augmente le risque de transmission des pathogènes. Par le biais de comportements hygiéniques collectifs tels quel le rejet des déchets, les insectes sociaux ont développé des défenses spécifiques contre les pathogènes. Nous avons comparé la dynamique de rejet de différents types de déchets (cadavres, proies et morceaux de vermiculite) introduits dans des nids de Myrmica rubra. L’analyse vidéo, réalisée grâce à un programme original de suivi du déchet et de digitalisation des zones de couvain, a permis un suivi précis du déplacement de ces déchets au sein du nid. La vermiculite a été rapidement rejetée après 12 ± 4 minutes, les cadavres ont été éliminés après 139 ± 28 min et les proies ont été consommées puis rejetées après 17,3 ± 0,3 heures. L’analyse spatiale des déchets a montré un déplacement rapide des cadavres loin du couvain alors que les proies étaient fréquemment apportées près des larves pour la consommation. L’efficacité de la gestion des déchets a été testée par ailleurs en comparant la survie de colonies de fourmis ayant ou non la possibilité de rejeter leurs cadavres. La mortalité des adultes et des larves vivant dans des nids contraints de garder leurs cadavres est significativement supérieure à celle observée dans les colonies contrôles, confirmant l’importance de ce rejet pour la survie et le bon état sanitaire de la fourmilière. [less ▲]

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See detailDiarrhea and vomitting in a yorkshire terrier
Ramery, Eve ULg; Papakonstantinou, Stratos; Pinilla, Manuel et al

Conference (2010)

Detailed reference viewed: 25 (1 ULg)
See detailEvolution of anatomical complexity, including an early type of cambium, in Psilophyton-grade plants.
Strullu-Derrien, Marie-Christine; Gensel, Patricia G.; Gerrienne, Philippe ULg

Conference (2010)

Detailed reference viewed: 23 (1 ULg)
See detailSémiochimiques et danger - Les phéromones d'alarme
Verheggen, François ULg

Conference (2010)

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See detailLand conversion to industrialization and its impacts on household food security in Red River Delta, Vietnam
Nguyen Thi, Dien; Lebailly, Philippe ULg; Vu Dinh, Ton

Conference (2010)

Since 1990s Vietnam is undergoing rapid industrialization with the national goal of becoming an industrial country. As a result, large tracts of agricultural land were conversed to industrial zones and ... [more ▼]

Since 1990s Vietnam is undergoing rapid industrialization with the national goal of becoming an industrial country. As a result, large tracts of agricultural land were conversed to industrial zones and clusters. This paper analyzes the complex impacts caused by industrialization on household food security. Both qualitative and quantitative methods were applied to investigate how land conversion process to industrial companies affected food security of different groups of peasant households in Hung Yen province, the most rapid industrialization province in Red River Delta of Vietnam. The study showed that industrialization and neo-liberalism affected household food security in three aspects: the lost of large agricultural land area which did not ensure stable jobs for peasants; the decline of living quality as a result of environmental pollution and high living costs; and the lost of household self reliance on food, with 77 percent of surveyed households not producing enough food for their own consumption. Industrialization had created a new class structure in the Vietnamese countryside with the rise of landless peasants who survived by selling their labor and who are net food buyers. The study contributes to the research that link the analysis of household food security with livelihood systems in the processes interacting across scales, from the very local to the global. [less ▲]

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See detailL'erreur totale pour le transfert de méthodes
Rozet, Eric ULg

Conference (2010)

Detailed reference viewed: 36 (3 ULg)
See detailSubspace-based Methods for Machinery Analysis and Monitoring
Nguyen, Viet Ha ULg; Rutten, Christophe ULg; Golinval, Jean-Claude ULg

Conference (2010)

The objective of this presentation is to address the problem of structural damage detection or fault diagnosis in mechanical systems using subspace-based methods. Different methods are reviewed starting ... [more ▼]

The objective of this presentation is to address the problem of structural damage detection or fault diagnosis in mechanical systems using subspace-based methods. Different methods are reviewed starting from Principal Component Analysis (PCA) also known as Proper Orthogonal Decomposition (POD) of time responses. PCA is known as an efficient method for extracting modal features of linear structures from output-only measurements. Those features define a subspace which characterizes the dynamical behavior of the structure. It becomes than possible to detect structural damage by comparing a reference subspace (obtained from the healthy structure) with current subspaces on the basis of the concept of angles between subspaces. Other damage indexes based on statistics may also be used. One of the drawbacks of PCA is the need of several sensors. If the number of sensors is too small, modal identification and/or damage detection may not be performed in good conditions using PCA. An alternative PCA-based method named Null Subspace Analysis (NSA) may then be used. The NSA method generates data by means of block Hankel matrices and is proven to be efficient when the number of available sensors is small or even reduced to one sensor only. However, when damage activates nonlinearity, the detection problem may necessitate methods which are more sensitive to nonlinear behaviors. To this purpose, Kernel Principal Component Analysis (KPCA) is a nonlinear extension of PCA built to authorize features with nonlinear dependence between variables. The method is “flexible” in the sense that different kernel functions may be used to better fit the testing data. Industrial applications are presented to illustrate the proposed methods. [less ▲]

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See detailEuropean Union-Africa Partnership on cotton
Berti, Fabio ULg

Conference (2010)

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See detailCOMMUNITY FORESTS IN CENTRAL AFRICA: PRESENT HURDLES AND PROSPECTIVE EVOLUTIONS
Karsenty, Alain; Lescuyer, Guillaume; Ezzine de Blas, Driss et al

Conference (2010)

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See detailReally TVD advection schemes for shelf seas
Mercier, Christophe ULg; Delhez, Eric ULg

Conference (2010)

During the last decade large efforts have been devoted to the development of high-resolution schemes to solve advection problems. High-resolution conservative numerical schemes satisfying conservative ... [more ▼]

During the last decade large efforts have been devoted to the development of high-resolution schemes to solve advection problems. High-resolution conservative numerical schemes satisfying conservative, monotonicity preserving and shock-capturing properties are nowadays widely used in ocean modeling. Among these, TVD schemes, based on the concept of Total Variation Diminishing (TVD), were progressively adopted because of their good behavior that guarantees a solution free from numerical artifacts (no overshooting, no spurious oscillation, small diffusion) that can spoil the physical significance of the results. Most of the TVD schemes and associated limiters have been originally developed in idealized one-dimensional flows described by a linear advection. In finite volume marine models, one has however often to deal with the depth integrated advection equation. This formulation is usually preferred because of its conservative form that is particularly suited to numerical treatment using a finite volume approach. Conservative numerical schemes can be easily formulated to ensure that the total mass of the advected quantity is conserved. This property is very valuable in the context of environmental studies for which a strict equilibrium of the mass budget of pollutants is often more relevant that the raw accuracy of the integration scheme. In the same context, the numerical scheme should also produce neither new local extremum nor negative concentrations, i.e. it should be monotonicity preserving which is implied by the TVD property. The development of TVD schemes for the resolution of advection equations written in the conservative form is however not trivial. Numerical experiments show that the blind application to the depth-integrated equation of the usual TVD schemes and associated flux limiters introduced in the context of linear advection can lead to non-TVD solutions in presence of complex geometries. Spatial and/or temporal variations of the local bathymetry can indeed break the TVD property of the usual schemes. Really TVD schemes can be recovered by taking into account the local depth and its variations in the formulation of the flux limiters. Using this approach, a generalized superbee limiter is introduced and validated. [less ▲]

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See detailEstimation of tidal boundary conditions and surface winds by assimilation of high-frequency radar surface currents in the German Bight
Barth, Alexander ULg; Alvera Azcarate, Aïda ULg; Gurgel, Klaus-Werner et al

Conference (2010)

Numerical ocean models are affected by errors of various origins: errors in the initial conditions, boundary conditions and atmospheric forcings, uncertainties in the turbulence parametrization and ... [more ▼]

Numerical ocean models are affected by errors of various origins: errors in the initial conditions, boundary conditions and atmospheric forcings, uncertainties in the turbulence parametrization and discretization errors. In data assimilation, observations are used to reduce the uncertainty in the model solution. Ensemble-based assimilation schemes are often implemented such that the expected error of the model solution is minimized. It is shown that the observations can also be used to obtain improved estimates of the, in general, poorly known boundary conditions and atmospheric forcings. An ensemble smoother scheme is presented to assimilate high-frequency (HF) radar surface currents to improve tidal boundary conditions and wind forcings of a circulation model of the German Bight. To create an ensemble of dynamically realistic tidal boundary conditions, a cost function is formulated which is directly related to the probability of each perturbation. This cost function ensures that the perturbations are spatially smooth and that the structure of the perturbations satisfies approximately the harmonic linearized shallow water equations. Based on those perturbations an ensemble simulation is carried out using the full three-dimensional General Estuarine Ocean Model (GETM). Optimized boundary values are obtained using all observations within the assimilation period using the covariances of the ensemble simulation. The approach acts like a smoother scheme since past and future observations are taken into account. The final analysis is obtained by rerunning the model using the optimal perturbation of the boundary conditions. The analyzed model solution satisfies thus the model equations exactly and does not suffer from spurious adjustments often observed with sequential assimilation schemes. Model results are also compared to independent tide gauge data. The assimilation also reduces the model error compared to those sea level observations. The same scheme is also used to correct surface winds. Surface winds are crucial for accurately modeling the marine circulation in coastal waters. The method is validated directly by comparing the analyzed wind speed to in situ measurements and indirectly by assessing the impact of the corrected winds on sea surface temperature (SST) relative to satellite SST. [less ▲]

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See detailTotal Error Concept in Validation of Viral Activity in Cell Cultures
Gibein, N.; Rozet, Eric ULg

Conference (2010)

Due to the high variability inherent of experimental recipients, validating biological methods is often a complex exercise, and following ICH Q2R1 recommendations is not always feasible and/or meaningful ... [more ▼]

Due to the high variability inherent of experimental recipients, validating biological methods is often a complex exercise, and following ICH Q2R1 recommendations is not always feasible and/or meaningful. Linking systematic error and random error to obtain a unique criterion, as defined in ISO guideline, could be of interest to capture the total variability in biological assays. In this paper, the use of Total Error concept in the validation of biological assays was for the first time investigated and compared to a conventional interpretation of the ICH guideline. Both decision methodologies concluded that the assaywas valid from 2.13 to 5.83 log10(CCID50/ml). However, only the Total Error approach using accuracy profile as decision tool allowed to guarantee that accurate and reliable results will be obtained during the future routine application of the assay. In addition, the risk to obtain out of acceptance limits results was estimated using this approach and was found out to be at the most 3.1% irrespective of the concentration level, thus demonstrating the reliability of the biological assay. [less ▲]

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See detailDevelopment of a new genetic evaluation model for carcass quality based on crossbred performances of Piétrain boars in the Walloon Region of Belgium
Dufrasne, Marie ULg; Hammami, Hedi ULg; Jaspart, Véronique et al

Conference (2010)

In context of the development of the genetic evaluation system of Piétrain boars for crossbred performances, a genetic evaluation model was developed for the estimation of genetic merit of boars for ... [more ▼]

In context of the development of the genetic evaluation system of Piétrain boars for crossbred performances, a genetic evaluation model was developed for the estimation of genetic merit of boars for backfat thickness (BF) and meat percentage (%meat). The model developed was a random regression model using linear splines on age which knots at 175, 200 and 250 days. Variance components were estimated by restricted maximum likelihood and Gibbs sampling. Estimated heritability from 150 to 300 days increased from 0.56 to 0.75 for BF and from 0.55 to 0.69 for %meat. Genetic correlation between BF and %meat varied between -0.90 and -0.93 from 150 to 300 days. According to the study of residuals, the developed model was considered to fit well the data especially between 175 and 250 days of age. [less ▲]

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See detailAssimilation of high-frequency radar surface currents measurements to optimize tidal boundary conditions and wind forcing
Barth, Alexander ULg; Alvera Azcarate, Aïda ULg; Gurgel, Klaus-Werner et al

Conference (2010)

An ensemble smoother scheme is presented to assimilate high-frequency (HF) radar surface currents to improve tidal boundary conditions and wind forcings of a circulation model of the German Bight. To ... [more ▼]

An ensemble smoother scheme is presented to assimilate high-frequency (HF) radar surface currents to improve tidal boundary conditions and wind forcings of a circulation model of the German Bight. To create an ensemble of dynamically realistic tidal boundary conditions, a cost function is formulated which is directly related to the probability of each perturbation. This cost function ensures that the perturbations are spatially smooth and that the structure of the perturbations satisfies approximately the harmonic linearized shallow water equations. Based on those perturbations an ensemble simulation is carried out using the full three-dimensional General Estuarine Ocean Model (GETM). Optimized boundary values are obtained using all observations within the assimilation period using the covariances of the ensemble simulation. The approach acts like a smoother scheme since past and future observations are taken into account. The final analysis is obtained by rerunning the model using the optimal perturbation of the boundary conditions. The analyzed model solution satisfies thus the model equations exactly and does not suffer from spurious adjustments often observed with sequential assimilation schemes. Model results are also compared to independent tide gage data. The assimilation also reduces the model error compared to those sea level observations. The same scheme is also used to correct surface winds. Surface winds are crucial for accurately modeling the marine circulation in coastal waters. The method is validated directly by comparing the analyzed wind speed to in situ measurements and indirectly by assessing the impact of the corrected winds on sea surface temperature (SST) relative to satellite SST. [less ▲]

Detailed reference viewed: 14 (2 ULg)
See detailVanadium oxide-based mesoporous films as positive electrode material in Li-ion batteries
Krins, Natacha ULg; Caes, Sébastien ULg; Arrebola, José-Carlos et al

Conference (2010)

Detailed reference viewed: 10 (3 ULg)
See detailRem Koolhaas, Le Corbusier et la ville-événement
Steinmetz, Rudy ULg

Conference (2010)

Detailed reference viewed: 91 (16 ULg)