Signatures of magnetospheric injections in Saturn's aurora

in Journal of Geophysical Research. Space Physics (2013)

Axisymmetric transient modelling of a wind turbine foundation in cohesionless soil using the Prevost’s model

in Computational Methods in Marine Engineering (2013)

Suction caissons are more and more used for offshore foundations. This paper deals with the cyclic modelling of suction caissons using the Prevost's model. The case study is a 8m large diameter embedded ... [more ▼]

Suction caissons are more and more used for offshore foundations. This paper deals with the cyclic modelling of suction caissons using the Prevost's model. The case study is a 8m large diameter embedded in dense No. 0 Lund sand. Parameters for the model are calibrated using drained triaxial tests. A parametric study concerning the influence of the constitutive law, the skirt length and permeability is carried out. [less ▲]

Development of a generalized steady-state simulation framework for positive displacement compressors and expanders

in Proceedings of the International Conference on Compressors and their Systems 2013 (2013)

In this paper, a generalized framework is presented that can be used to simulate the steady-state performance of a wide range of positive displacement compressors and expanders (scroll, piston, screw ... [more ▼]

In this paper, a generalized framework is presented that can be used to simulate the steady-state performance of a wide range of positive displacement compressors and expanders (scroll, piston, screw, rotary, spool, etc.). The complete simulation algorithm is described, and an emphasis is placed on the numerical methods required to obtain robust behavior of the simulation. This formulation has been implemented into an open-source software package entitled PDSim written in the Python language. PDSim is the first open-source generalized compressor and expander simulation package. The source code can be freely obtained from http://pdsim.sf.net [less ▲]

Retour au travail après une absence de longue durée : Comment dynamiser le dispositif légal existant ?

in DAVAGLE, MICHEL (Ed.) Le maintien au travail de travailleurs devenus partiellement inaptes (2013)

Possibilities and limitations of the Prevost model for the modelling of cohesionless soil cyclic behaviour

in Proceedings of the 18th International Conference on Soil Mechanics and Geotechnical Engineering (2013)

The Prevost’s model is currently used to model cyclic behaviour of soils especially in earthquake engineering. The original model is able to capture the main features of cyclic behaviour: pore pressure ... [more ▼]

The Prevost’s model is currently used to model cyclic behaviour of soils especially in earthquake engineering. The original model is able to capture the main features of cyclic behaviour: pore pressure build up and plastic deformation accumulation. But accurate modelling of laboratory tests requires improvements. Enhanced models exist but require a lot of parameters that make them cumbersome for practical purpose. A suction caisson, part of a tripod offshore foundation for wind turbines is modelled. Possibilities of the Prevost’s model are highlighted compared with a classical Drucker-prager model. [less ▲]

Downscaling transient climate change with a stochastic weather generator for the Geer catchment, Belgium

in Climate Research (2013)

The coarse resolution of climate models creates the need for future scenarios which are downscaled to an appropriate spatial scale. Considerable effort has been devoted to the development of downscaling ... [more ▼]

The coarse resolution of climate models creates the need for future scenarios which are downscaled to an appropriate spatial scale. Considerable effort has been devoted to the development of downscaling methods but a number of important issues remain in the development of robust, usable climate scenarios. These include the incorporation of various sources of uncertainty into future scenarios and the production of scenarios at timescales relevant to planners. This paper describes a new procedure which addresses these issues by producing a multi-model ensemble of transient climate change scenarios. This method couples an existing stochastic rainfall model to a new, transient implementation of a weather generator, using changes projected by an ensemble of regional climate model (RCM) experiments. The methodology is demonstrated by the generation of transient scenarios of daily rainfall, temperature and potential evapotranspiration (PET) for the Geer catchment in Belgium for the period 2010 to 2085. The utility of these scenarios is demonstrated by assessing the changes projected by the simulated time series of several temperature indices. The Geer is projected to experience a decrease in the occurrence of frost days with a corresponding shortening of the frost season and lengthening of the growing season. By examining a large ensemble of transient scenarios the range of uncertainty in these projections is assessed, but further, it is suggested that additional information on the projected timing of specified threshold events or system responses may be provided which could aid planners in assessing the likely timescales of required interventions and adaptation responses. [less ▲]

Dietro, il paesaggio: Misura e ritmo di una strada tra le colline e il Piave.

in Architettura del Mondo. Ricerche e progetti dal mondo universitario (2013)

The Alta Marca Trevigiana (Colli del Piave), between Valdobbiadene and Conegliano, doesn't have a definite recognized identity, despite its strong visual character. However, for the visitor driving along ... [more ▼]

The Alta Marca Trevigiana (Colli del Piave), between Valdobbiadene and Conegliano, doesn't have a definite recognized identity, despite its strong visual character. However, for the visitor driving along the “Sinistra Piave”, the landscape is seen as a rhythmical composition of invitation to movement at different scales and at various intensity, that can be compared to a musical composition. The question then is how to transform the road from a simple through-way into an occasion to engage with the Colli del Piave, to transform a “landscape scenery” into an “experienced landscape”. [less ▲]

Voyage au Centre de la Terre

Book published by Académie royale de Belgique (2013)

L’intérieur de notre planète a toujours été une source d’effroi ou de fascination. Ceci d’autant plus que l’observation directe ne permet d’accéder qu’à moins de 1/500 de son rayon ! Notre connaissance de ... [more ▼]

L’intérieur de notre planète a toujours été une source d’effroi ou de fascination. Ceci d’autant plus que l’observation directe ne permet d’accéder qu’à moins de 1/500 de son rayon ! Notre connaissance de l’intérieur de la Terre provient donc soit de mesures géophysiques effectuées lors des séismes, soit d’expériences de cristallisation de minéraux sous des pressions et températures contrôlées, soit encore de l’observation de certaines météorites, censées représenter des fragments de l’intérieur d’une planète semblable à la nôtre. Après avoir abordé, via la tectonique des plaques, la composition et le fonctionnement de la croûte superficielle de notre planète, sa structure interne (manteau, noyau) est envisagée. Enfin, quelques informations quant au magnétisme terrestre permettent de comprendre son origine et son utilisation en tant que marqueur de la mobilité continentale. [less ▲]

Modeling Species Distributions from Heterogeneous Data for the Biogeographic Regionalization of the European Bryophyte Flora

in PLoS ONE (2013), 8(2),

The definition of biogeographic regions provides a fundamental framework for a range of basic and applied questions in biogeography, evolutionary biology, systematics and conservation. Previous research ... [more ▼]

The definition of biogeographic regions provides a fundamental framework for a range of basic and applied questions in biogeography, evolutionary biology, systematics and conservation. Previous research suggested that environmental forcing results in highly congruent regionalization patterns across taxa, but that the size and number of regions depends on the dispersal ability of the taxa considered. We produced a biogeographic regionalization of European bryophytes and hypothesized that (1) regions defined for bryophytes would differ from those defined for other taxa due to the highly specific eco-physiology of the group and (2) their high dispersal ability would result in the resolution of few, large regions. Species distributions were recorded using 10,000 km2 MGRS pixels. Because of the lack of data across large portions of the area, species distribution models employing macroclimatic variables as predictors were used to determine the potential composition of empty pixels. K-means clustering analyses of the pixels based on their potential species composition were employed to define biogeographic regions. The optimal number of regions was determined by v-fold cross-validation and Moran's I statistic. The spatial congruence of the regions identified from their potential bryophyte assemblages with large-scale vegetation patterns is at odds with our primary hypothesis. This reinforces the notion that post-glacial migration patterns might have been much more similar in bryophytes and vascular plants than previously thought. The substantially lower optimal number of clusters and the absence of nested patterns within the main biogeographic regions, as compared to identical analyses in vascular plants, support our second hypothesis. The modelling approach implemented here is, however, based on many assumptions that are discussed but can only be tested when additional data on species distributions become available, highlighting the substantial importance of developing integrated mapping projects for all taxa in key biogeographically areas of Europe, and the Mediterranean peninsulas in particular. © 2013 Mateo et al. [less ▲]

On the asymptotic standard error of a class of robust estimators of ability in dichotomous item response models

Report (2013)

In item response theory, the classical estimators of ability are highly sensitive to response disturbances and can return strongly biased estimates of the true underlying ability level. Robust methods ... [more ▼]

In item response theory, the classical estimators of ability are highly sensitive to response disturbances and can return strongly biased estimates of the true underlying ability level. Robust methods were introduced to lessen the impact of such aberrant responses onto the estimation process. The computation of asymptotic (i.e., large sample) standard errors (ASE) for these robust estimators, however, has not been fully considered yet. This paper focuses on a broad class of robust ability estimators, defined by an appropriate selection of the weight function and the residual measure, for which the ASE is derived from the theory of estimating equations. The maximum likelihood (ML) and the robust estimators, together with their estimated ASE, are then compared through a simulation study. It is concluded that both the estimators and their ASE perform similarly in absence of response disturbances, while the robust estimator and its estimated ASE are less biased and outperform their ML counterparts in presence of response disturbances with large impact on the item response process. [less ▲]