Germanistik in der Benelux: Kasus Belgien

Scientific conference (2012, December 07)

Using Proper Orthogonal Decomposition Methods for Comparing CFD Results to Experimental Measurements

Scientific conference (2012, December 07)

This work presents a method for quantitative comparison of numerical results to experimental measurements. It is based on the concept of Proper Orthogonal Decomposition. This technique is selected in ... [more ▼]

This work presents a method for quantitative comparison of numerical results to experimental measurements. It is based on the concept of Proper Orthogonal Decomposition. This technique is selected in order to compare the unsteady aerodynamic flows around static and oscillating bodies obtained from wind tunnel testing and numerical simulations. Two dimensional Time-resolved Particle Image Velocimetry measurements are carried out on the upper surface a 4:1 rectangular cylinder. Simulations are performed using unsteady Reynolds-Averaged Navier-Stokes and an unsteady Discrete Vortex Method. It is demonstrated that the proposed technique is a good preliminary step for comparing the main characteristics of unsteady aerodynamic data. [less ▲]

Horizon Partitioning of soil CO2 sources and their Isotopic Composition (13C) in a Pinus Sylvestris

Poster (2012, December 07)

The overall aim of this study is to contribute to a better understanding of mechanisms behind soil CO2 efflux using carbon stable isotopes. Given (i) the interest of conducting in situ studies with soil ... [more ▼]

The overall aim of this study is to contribute to a better understanding of mechanisms behind soil CO2 efflux using carbon stable isotopes. Given (i) the interest of conducting in situ studies with soil multilayer analysis and (ii) the benefits of isotopic tool to improve mechanistic understanding, these two approaches are combined. Quantifying the origin and the determinism of 13CO2 and 12CO2 production processes in the different soil layers using the gradient-efflux approach is the main goal of this work. To meet this one, the work includes an experimental setup and a modeling approach. The experimental set up (see also communication of Parent et al., session B008) comprised a combination of different systems, which were installed in a Scot Pine temperate forest at the Hartheim site (Southwestern Germany). Measurements include (i) half hourly vertical profiles of soil CO2 concentration (using soil CO2 probes), soil water content and temperature; (ii) half hourly soil surface CO2 effluxes (automatic chambers); (iii) half hourly isotopic composition of surface CO2 efflux and soil CO2 concentration profile and (iv) estimation of soil diffusivity through laboratory measurements conducted on soil samples taken at several depths. Using the data collected in the experimental part, we developed and used a diffusive transport model to simulate CO2 (13CO2 and 12CO2) flows inside and out of the soil based on Fick’s law. Given the horizontal homogeneity of soil physical parameters in Hartheim, we treated the soil as a structure consisting of distinctive layers of 5 cm thick and expressed the fick’s first law in a discrete formalism. The diffusion coefficient used in each layer was derived from (i) horizon specific relationships, obtained from laboratory measurements, between soil relative diffusivity and its water content and (ii) the soil water content values measured in situ. The concentration profile was obtained from in situ measurements. So, the main model inputs are the profiles of (i) CO2 (13CO2 and 12CO2) concentration, (ii) soil diffusion coefficient and (iii) soil water content. Once the diffusive fluxes deduced at each layer interface, the CO2 (13CO2 and 12CO2) production profile was calculated using the (discretized) mass balance equation in each layer. The results of the Hartheim measurement campaign will be presented. The CO2 source vertical profile and its link with the root and the Carbon organic content distribution will be showed. The dynamic of CO2 sources and their isotopic signature will be linked to climatic variables such soil temperature and soil water content. For example, we will show that the dynamics of CO2 sources was mainly related to temperature while changing of isotopic signature was more correlated to soil moisture. [less ▲]

Geometrical Validity of High-Order Triangular Finite Elements

in Engineering with Computers (2012)

This paper presents a method to compute accurate bounds on Jacobian determinants of high-order (curvilinear) triangular nite elements. This method can be used to guarantee that a curvilinear triangle is ... [more ▼]

This paper presents a method to compute accurate bounds on Jacobian determinants of high-order (curvilinear) triangular nite elements. This method can be used to guarantee that a curvilinear triangle is geometrically valid, i.e., that its Jacobian determinant is strictly positive everywhere in its reference domain. It also provides an e cient way to measure the quality the triangles. The key feature of the method is to expand the Jacobian determinant using a polynomial basis, built using B ezier functions, that has both properties of boundedness and positivity. Numerical results show the sharpness of our estimates. [less ▲]

Efficient ALE mesh management for 3D quasi-Eulerian problems

in International Journal for Numerical Methods in Engineering (2012), 92(10), 857-890

In computational solid mechanics, the ALE formalism can be very useful to reduce the size of finite element models of continuous forming operations such as roll forming. The mesh of these ALE models is ... [more ▼]

In computational solid mechanics, the ALE formalism can be very useful to reduce the size of finite element models of continuous forming operations such as roll forming. The mesh of these ALE models is said to be quasi-Eulerian because the nodes remain almost fixed—or almost Eulerian—in the main process direction, although they are required to move in the orthogonal plane in order to follow the lateral displacements of the solid. This paper extensively presents a complete node relocation procedure dedicated to such ALE models. The discussion focusses on quadrangular and hexahedral meshes with local refinements. The main concern of this work is the preservation of the geometrical features and the shape of the free boundaries of the mesh. With this aim in view, each type of nodes (corner, edge, surface and volume) is treated sequentially with dedicated algorithms. A special care is given to highly curved 3D surfaces for which a CPU-efficient smoothing technique is proposed. This new method relies on a spline surface reconstruction, on a very fast weighted Laplacian smoother with original weights and on a robust reprojection algorithm. The overall consistency of this mesh management procedure is finally demonstrated in two numerical applications. The first one is a 2D ALE simulation of a drawbead, which provides similar results to an equivalent Lagrangian model yet is much faster. The second application is a 3D industrial ALE model of a 16-stand roll forming line. In this case, all attempts to perform the same simulation by using the Lagrangian formalism have been unsuccessful. [less ▲]

Biorthogonalization Techniques for Least Squares Temporal Difference Learning

Poster (2012, December 07)

We consider Markov reward processes and study OLS-LSTD, a framework for selecting basis functions from a set of candidates to obtain a sparse representation of the value function in the context of least ... [more ▼]

We consider Markov reward processes and study OLS-LSTD, a framework for selecting basis functions from a set of candidates to obtain a sparse representation of the value function in the context of least squares temporal difference learning. To support efficient both updating and downdating operations, OLS-LSTD uses a biorthogonal representation for the selected basis vectors. Empirical comparisons with the recently proposed MP and LARS frameworks for LSTD are made. [less ▲]

Direct parameter identification in a model of the cardiovascular system

in 11th Belgian Day on Biomedical Engineering (2012, December 07)

Calitatea lucernei sub influenţa fertilizării în condiţiile din silvostepa Moldovei

in Ţenu, Ioan; Vîntu, Vasile; Jităreanu, Gerard (Eds.) Durable Agriculture and Food Security – Priority objectives in research activity of the Ph.D. students from the UASVM Iasi (2012, December 07)

The research conducted during 2011-2012, on the Ezăreni farm, has sought influence of fertilization on the leaves/stems ratio, crude protein content (CP), neutral detergent fiber content (NDF), acid ... [more ▼]

The research conducted during 2011-2012, on the Ezăreni farm, has sought influence of fertilization on the leaves/stems ratio, crude protein content (CP), neutral detergent fiber content (NDF), acid detergent fiber content (ADF) and relative feed value (RFV), of alfalfa (Medicago sativa L.) in the second and third year of vegetation, at the first cut. The studied experimental plots were v1- unfertilized (control plot), v2-N50P50, v3-N75P50 and v4-30 t/ha manure). The results showed that the fertilization negatively affected crude protein content of plants. Although the protein content of leaves was higher and that of strains was less affected, the leaves/stems ratio decided this indicator for plant production. Organic fertilization showed a highly significant positive effect on the content of plant leaves and stems in NDF and ADF. [less ▲]

La littérature scientifique dans la formation des bioingénieurs à Gembloux. Vingt années d'évolution du concept d'Information Literacy

Doctoral thesis (2012)

In the education of bioengineers at Gembloux, the concept of information literacy was chosen as a guide for information literacy education. This concept describes a set of skills that allow individuals to ... [more ▼]

In the education of bioengineers at Gembloux, the concept of information literacy was chosen as a guide for information literacy education. This concept describes a set of skills that allow individuals to recognize an information need and enable them to locate, evaluate and use information needed. The concept of information literacy has evolved over the last two decades. This essay traces, through five articles and a review of the literature on the subject, the evolution of the concept. It also presents ways to implement information literacy education with a methodological approach, starting by the identification of the need of information to solve a problem to the production of a scientific communication (a homework, a conference, a scholarly paper...). This work addresses also the question of the relative invisibility of the concept of information literacy outside information specialists such as librarians. The major objective is to demonstrate that information literacy education is going well beyond the library. The skills involved are also intellectual, social and cultural skills. They include media and new information technologies and are not limited to technical or technological skills. Information literacy has become an autonomous discipline, with specific content, evolving, to talk about a didactic. Information literacy courses held in Gembloux should be considered as tools to improve the training of bioengineers and particularly the quality of their scientific publications. [less ▲]

Excess Return Forecast Using a Dynamic Asset Class Factor Model

E-print/Working paper (2012)

We propose a Dynamic Hierarchical Factor Model using Asset classes to predict mutual funds excess returns. We use different forecast combination schemes of bivariate model considering each asset class ... [more ▼]

We propose a Dynamic Hierarchical Factor Model using Asset classes to predict mutual funds excess returns. We use different forecast combination schemes of bivariate model considering each asset class factor in isolation. Primary analysis highlights the importance to account for asset class specific variations together with between classes or common variations. Further refinements of the a priori repartition are however in order. Forecasting performance of the model outperforms the historical mean benchmark both in terms of MSPE and utility based criteria. A forecasting exercise matching more closely real-time conditions must be undertaken to validate these initial results. [less ▲]