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See detailBias correction using data assimilation: Application on the Lorenz ’95 and NEMO-LIM models.
Canter, Martin ULg; Barth, Alexander ULg

Poster (2014, May 01)

Data assimilation has been used for decades in fields like engineering or signal processing to improve forecast models. Ensemble Kalman filters and other sequential data assimilation methods are examples ... [more ▼]

Data assimilation has been used for decades in fields like engineering or signal processing to improve forecast models. Ensemble Kalman filters and other sequential data assimilation methods are examples of developments which reduce the uncertainty of the model by taking observations into account. The widespread interest in addressing systematic forecast model errors only arose when the advances in modelling, data assimilation and computational power had reduced random errors to the point of commensurability with systematic errors, also known as bias. We present here a new method of bias correction using data assimilation. This method is based on the stochastic forcing of a model to correct bias. First, through a preliminary run, we estimate the bias of the model and its possible sources. Then, we establish a forcing term which is directly added inside the model’s equations. We create an ensemble of runs and consider the forcing term as a control variable during the assimilation of observations. We then use this analysed forcing term to correct the bias of the model. Since the forcing is added inside the model, it acts as a source term, unlike external forcings such as wind. This procedure has been developed and successfully tested with a twin experiment on a Lorenz 95 model. Indeed, we were able to estimate and recover an artificial bias that had been added into the model. This bias had a spatial structure and was constant through time. The mean and behaviour of the corrected model corresponded to those the reference model. It is currently being applied and tested on the sea ice ocean NEMO LIM model, which is used in the PredAntar project. NEMO LIM is a global and low resolution (2 degrees) coupled model (hydrodynamic model and sea ice model) with long time steps allowing simulations over several decades. Due to its low resolution, the model is subject to bias in area where strong currents are present. We aim at correcting this bias by using perturbed current fields from higher resolution models and randomly generated perturbations. [less ▲]

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See detailDetermination of the magnetic penetration depth in a superconducting Pb film
Brisbois, Jérémy ULg

Conference (2014, May 01)

By means of scanning Hall probe microscopy technique we accurately map the magnetic field pattern produced by Meissner screening currents in a thin superconducting Pb stripe. The obtained field profile ... [more ▼]

By means of scanning Hall probe microscopy technique we accurately map the magnetic field pattern produced by Meissner screening currents in a thin superconducting Pb stripe. The obtained field profile allows us to quantitatively estimate the Pearl length Λ without the need of pre-calibrating the Hall sensor. This fact contrasts with the information acquired through the spatial field dependence of an individual flux quantum where the scanning height and the magnetic penetration depth combine in a single inseparable parameter. The derived London penetration depth λL coincides with the values previously reported for bulk Pb once the kinetic suppression of the order parameter is properly taken into account. [less ▲]

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See detailOutplacement adequacy and benefits: The mediating role of retrospective justice
Marzucco, Laurence ULg; Hansez, Isabelle ULg

Poster (2014, May)

ABSTRACT We examined the relationships between perceived outplacement adequacy, retrospective justice and outplacement benefits for redundant employees using outplacement services. Based on an ... [more ▼]

ABSTRACT We examined the relationships between perceived outplacement adequacy, retrospective justice and outplacement benefits for redundant employees using outplacement services. Based on an outplacement experience perceived as adequate, victims formed retrospective justice perceptions about their former organization that in turn, impacted their negative emotions, well-being, future perspectives and job search. PRESS PARAGRAPH The increasing prevalence of organizational downsizing has been matched by growth in the provision of outplacement services over the last decade. Despite this rapid growth and ongoing need for outplacement services, little is yet known about the perceived adequacy and the benefits of these services for redundant employees using them. Our results indicated that an outplacement experience perceived as adequate for redundant employees retrospectively fosters their impressions of justice about the dismissing organization; this leads in turn to satisfactory benefits for them: reduction of negative emotions, enhancement of their perceived well-being, future perspectives, and job-seeking activities. [less ▲]

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See detailEvent justice and social entity justice: A cross-lagged analysis
Marzucco, Laurence ULg; Hansez, Isabelle ULg

Poster (2014, May)

ABSTRACT This study aimed to examine the directionality of the relationship between event justice and social entity justice. Using two samples and a cross-lagged panel analysis with two measurement times ... [more ▼]

ABSTRACT This study aimed to examine the directionality of the relationship between event justice and social entity justice. Using two samples and a cross-lagged panel analysis with two measurement times, social entity justice was found to predict event justice (procedural, distributive, interpersonal and informational justice event), supporting the top-down process. PRESS PARAGRAPH The life of organizations is punctuated by a wide range of managerial decisions (e.g., hiring, performance appraisal or organizational change). Facing such events, employees evaluate the fairness of the situation experienced. However, little is known about how employees develop justice judgments. This study shows that employees’ fairness perceptions about their organization influence their interpretation of the fairness of subsequent events involving the organization. Building and fostering a climate of justice is therefore of primary importance for organizations, since global fairness perceptions about the organization may help employees to perceive a specific event, such as a managerial decision, as being fair. [less ▲]

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See detailAméliorer la formation clinique en logopédie par un stage socle au sein de l'université
Martinez Perez, Trecy ULg; Willems, Sylvie ULg; Maillart, Christelle ULg

Conference (2014, May)

La formation clinique des étudiants en logopédie (orthophonie) occupe une place importante dans leur cursus. Cette formation se dispense principalement via des stages réalisés dans des structures ... [more ▼]

La formation clinique des étudiants en logopédie (orthophonie) occupe une place importante dans leur cursus. Cette formation se dispense principalement via des stages réalisés dans des structures extérieures au centre de formation. Si cette ouverture permet aux étudiants de se confronter à la réalité du terrain, elle implique en contrepartie une hétérogénéité des lieux de stage et, par conséquent, une hétérogénéité de la formation avec certaines compétences qui sont peu ou pas travaillées dans certains lieux de stage. Face à cette problématique, un stage « socle », garant d’un base commune préalable, est désormais proposé à tous les étudiants du Master 1 Logopédie de l’Université de Liège au sein de la clinique universitaire. Ce dispositif poursuit un double objectif : (a) permettre à tous les étudiants en logopédie d’accéder aux apprentissages de base nécessaires pour une pratique future de qualité, (b) par son design, accompagner l’étudiant dans le développement réflexif et intégré de plusieurs compétences professionnelles du logopède. Plus précisément, ce stage de 60H se réalise en binôme. Chaque binôme participe à cinq séances de quatre heures sur la réalisation d’un bilan logopédique. Par ailleurs, un système de caméra permet aux étudiants d’observer activement le bilan réalisé par un second binôme et sert de support pour une séance de feedback. En 2012-2013, l’évaluation du dispositif indique notamment que : pour 84% des étudiants, ce dispositif leur a permis d’apprendre et/ou de pratiquer des notions qui ne sont pas abordé par ailleurs dans leur parcours de formation ; pour 82% des étudiants, ce dispositif les a aidé à relier la pratique aux notions abordées aux cours ; 100% des étudiants pensent pouvoir utiliser ce qu’ils ont développé lors du dispositif dans leur pratique professionnelle. [less ▲]

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See detailAnalyses croisées du monde du travail
Smette, Bernard ULg

in Cahiers du GRM (2014), 5

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See detailDark Atoms and Dark Radiation
Khlopov, Maxim; Belotsky, Konstantin; Cudell, Jean-René ULg et al

Book published by Hindawi Publishing Corporation (2014)

We have invited investigators to contribute original research and review articles that seek to define the possible physical nature of composite dark matter and its constituents, to stimulate the ... [more ▼]

We have invited investigators to contribute original research and review articles that seek to define the possible physical nature of composite dark matter and its constituents, to stimulate the experimental searches and to suggest astrophysical tests for their effects. The collected papers in this special issue represent only a first small step in the approach to the thorough investigation of the topic of dark atoms and dark radiation, demonstrating the wide but far from complete variety of possible aspects of this problem. [less ▲]

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See detailShewhart Control Charts for Monitoring Reliability with Weibull Lifetimes
Faraz, Alireza ULg; Saniga, Erwin; Heuchenne, Cédric ULg

in Quality and Reliability Engineering International (2014)

In this paper, we present Shewhart type Z ̅ and S2 control charts for monitoring individual or joint shifts in the scale and shape parameters of a Weibull distributed process. The advantage of this method ... [more ▼]

In this paper, we present Shewhart type Z ̅ and S2 control charts for monitoring individual or joint shifts in the scale and shape parameters of a Weibull distributed process. The advantage of this method is its ease of use and flexibility for the case where the process distribution is Weibull, although the method can be applied to any distribution. We illustrate the performance of our method through simulation and the application through the use of an actual data set. Our results indicate that Z ̅ and S2 control charts perform well in detecting shifts in the scale and shape parameters. We also provide a guide that would enable a user to interpret out-of-control signals. [less ▲]

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See detailDes performances de production laitière et de reproduction élevées sont compatibles. Le management en est la clé.
Chapaux, Philippe; Glorieux, Géry; Hanzen, Christian ULg

in Veterinaria (Bruxelles) : Bulletin d’Information de l’Union Syndicale Vétérinaire Belge (2014)

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See detailExpression of peroxisome-proliferator activated receptor alpha in pituitary tumours
Rotondi, S; Modarelli, A; Rostomyan, L et al

in Endocrine Abstracts (2014, May)

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See detailThe Robust Economic Statistical Design of the Hotelling’s T^2 Chart
Faraz, Alireza ULg; Chalaki, Kamyar; Saniga, Erwin et al

in Journal of Statistical Computation & Simulation (2014)

Economic statistical designs aim at minimizing the cost of process monitoring when a specific scenario or a set of estimated process and cost parameters is given. However, in practical situations the ... [more ▼]

Economic statistical designs aim at minimizing the cost of process monitoring when a specific scenario or a set of estimated process and cost parameters is given. However, in practical situations the process may be affected by more than one scenario which may lead to severe cost penalties for upsetting the true scenario. This paper presents the robust economic statistical design (RESD) of the T^2 chart to reduce the monetary losses when there are multiple distinct scenarios. The genetic algorithm optimization method is employed here to minimize the total expected monitoring cost across all distinct scenarios. Through two numerical examples the proposed method is illustrated. Simulation studies indicate that the robust economic statistical designs should be encouraged in practice. [less ▲]

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See detailLa mineuse de la tomate et ses risques agriculturaux
De Backer, Lara ULg; Verheggen, François ULg

Conference (2014, May)

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See detailLe "déplacement" comme problème: les transferts artistiques à l'époque gothique
Van den Bossche, Benoît ULg; Dubois, Jacques; Guillouët, Jean-Marie

in Van den Bossche, Benoît; Dubois, Jacques; Guillouët, Jean-Marie (Eds.) Les transferts artistiques dans l'Europe gothique (2014)

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See detailProcessing of alloy Ti-6Al-4V and of stainless steel 316L by Laser Beam Melting
Mertens, Anne ULg; Paydas, Hakan ULg; Reginster, Sylvie ULg et al

Conference (2014, May)

Additive manufacturing processes such as Selective Laser Melting (SLM) appear very promising in view of the economic production of near-net-shape, complex and (almost) fully dense parts from metallic ... [more ▼]

Additive manufacturing processes such as Selective Laser Melting (SLM) appear very promising in view of the economic production of near-net-shape, complex and (almost) fully dense parts from metallic materials such as Ti alloys and stainless steels. Practically, in SLM, a metallic powder is deposited layer-by-layer in a powder bed and then molten locally according to the desired shape. An important feature of this process is that the structure undergoes an ultra-fast cooling once the beam leaves the working zone, thus giving rise to strongly out-of-equilibrium microstructures. In the case of Ti alloy Ti-6Al-4V, in particular, the microstructural anisotropy resulting from the epitaxial growth of the newly deposited layer on the material previously solidified has been shown to exert a very strong influence on the mechanical properties [1] In the present work, the thermophysical behaviour of Ti-alloy Ti-6Al-4V and of stainless steel 316L has been characterised in details, in order to reach a better understanding of the phenomena controlling the microstructures and mechanical properties of parts. In particular, the thermal conductivity of Ti-alloy Ti-6Al-4V and of stainless steel 316L at high temperature has been determined by combining dilatometry, Differential Scanning Calorimetry (DSC) and laser flash diffusivimetry based on Laplace’s equation. Since Ti-alloy Ti-6Al-4V and stainless steel 316L exhibit quite different physical behaviours, their careful comparison is shown to shed more light into the role of phenomena such as epitaxial growth, out-of-equilibrium phase transformations and/or internal stresses in the additive manufacturing of metallic materials. [less ▲]

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See detailHybrid MicroPET Imaging for Dosimetric Applications in Mice: Improvement of Activity Quantification in Dynamic MicroPET Imaging for Accelerated Dosimetry Applied to 6-[ 18 F] Fluoro- L -DOPA and 2-[ 18 F]Fluoro- L -Tyrosine
Bretin, Florian ULg; Mauxion, T; Warnock, G et al

in Molecular Imaging and Biology (2014), 16(3), 383-394

Purpose: Dynamic microPET imaging has advantages over traditional organ harvesting, but is pronetoquantificationerrorsinsmallvolumes.Hybridimaging,wheremicroPETactivitiesarecross- calibrated using post ... [more ▼]

Purpose: Dynamic microPET imaging has advantages over traditional organ harvesting, but is pronetoquantificationerrorsinsmallvolumes.Hybridimaging,wheremicroPETactivitiesarecross- calibrated using post scan harvested organs, can improve quantification. Organ harvesting, dynamic imaging and hybrid imaging were applied to determine the human and mouse radiation dosimetry of 6-[18 F]fluoro-L-DOPA and 2-[18 F]fluoro-L-tyrosine and compared. Procedures: Two-hour dynamic microPET imaging was performed with both tracers in four separate mice for 18 F-FDOPA and three mice for 18 F-FTYR. Organ harvesting was performed at 2, 5, 10, 30, 60 and 120 min post tracer injection with n=5 at each time point for 18 F-FDOPA and n=3 at each time point for 18 F-FTYR. Human radiation dosimetry projected from animal data was calculated for the three different approaches for each tracer using OLINDA/EXM. S- factors for the MOBY phantom were used to calculate the animal dosimetry. Results: Correlations between dose estimates based on organ harvesting and imaging was improved from r=0.997 to r=0.999 for 18 F-FDOPA and from r=0.985 to r=0.996 (p<0.0001 for all) for 18 F-FTYR by using hybrid imaging. Conclusion: Hybrid imaging yields comparable results to traditional organ harvesting while partially overcoming the limitations of pure imaging. It is an advantageous technique in terms of number of animals needed and labour involved. [less ▲]

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See detailA Brief Review of Ultraviolet Auroral Emissions on Giant Planets
Grodent, Denis ULg

in Space Science Reviews (2014)

The morphologies of the ultraviolet auroral emissions on the giant gas planets, Jupiter and Saturn, have conveniently been described with combinations of a restricted number of basic components. Although ... [more ▼]

The morphologies of the ultraviolet auroral emissions on the giant gas planets, Jupiter and Saturn, have conveniently been described with combinations of a restricted number of basic components. Although this simplified view is very handy for a gross depiction of the giant planets’ aurorae, it fails to scrutinize the diversity and the dynamics of the actual features that are regularly observed with the available ultraviolet imagers and spectrographs. In the present review, the typical morphologies of Jupiter and Saturn’s aurorae are represented with an updated and more accurate set of components. The use of sketches, rather than images, makes it possible to compile all these components in a single view and to put aside ultraviolet imaging technical issues that are blurring the emission sources, thus preventing one from disentangling the different auroral signatures. The ionospheric and magnetospheric processes to which these auroral features allude can then be more easily accounted. In addition, the use of components of the same kind for both planets may help to put forward similarities and differences between Jupiter and Saturn. The case of the ice giants Uranus and Neptune is much less compelling since their weak auroral emissions are very poorly documented and one can only speculate about their origin. This review presents a current perspective that will inevitably evolve in the future, especially with upcoming observing campaigns and forthcoming missions like Juno. [less ▲]

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