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See detailMise en réseau des acteurs, des activités et des produits touristiques dans les chefferies de l’Ouest -Cameroun
Lekane Tsobgou, Dieudonné ULg; Schmitz, Serge ULg

in Bokwa, Anita (Ed.) Changes, Challenges, Responsability. IGU 2014 Book of Abstracts (2014, August)

Cette recherche propose comme défis a relever, d’élaborer des dispositifs, des outils et la méthodologie de mise en réseau dans le secteur du tourisme dans les Chefferies de l'Ouest du Cameroun. La ... [more ▼]

Cette recherche propose comme défis a relever, d’élaborer des dispositifs, des outils et la méthodologie de mise en réseau dans le secteur du tourisme dans les Chefferies de l'Ouest du Cameroun. La communication discute des logiques (construit processuel) de la mise en réseau d’acteurs, d’activités et de ressources territoriales dans un circuit touristique [less ▲]

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See detailWhich agritourism for which suburban countryside? A heuristic and comparative analysis in Wallonia and Grand-Duchy of Luxembourg (part 2)
Dubois, Charline ULg; Schmitz, Serge ULg

in Ianos, Ioan (Ed.) Rural life and rural systems between tradition and integrated urban-rural development (2014, August)

Mutations, transformations, transitions are keywords which open the door to many questions regarding the global European agriculture. The resources of the rural countryside in Europe are subject to many ... [more ▼]

Mutations, transformations, transitions are keywords which open the door to many questions regarding the global European agriculture. The resources of the rural countryside in Europe are subject to many pressures. Agricultural activities are decreasing and farmers are losing importance. In some northwestern European countryside, the declining agriculture compels to diversify activities in farms. Some farmers need to rethink their business goals in order to successfully sustain their operations in the economic space. In many areas, one of the solutions suggested is the development of agritourism. Agritourism in Wallonia and in the Grand-Duchy of Luxembourg is a tourist activity proposed by the farmer in his farm. While addressing the challenges and countering threats of their agriculture, both suburban areas present many advantages and opportunities for tourism development. Different tourist and leisure developments are conceived and proposed. The activity is reinforced by popular images of sustainability and ecology. Is agritourism a universal solution or is it a reflected contextualized solution? In the Tel-Aviv CSRS meeting, in 2010, we presented a communication on this issue. While the theoretical review and the aim of the first paper were well presented, the empirical results were not well documented because we were at the beginning of the PhD research. Today, we propose, in this paper, to improve information and to answer to the different comments from the members of the commission. Agritourism should be defined, localized, differentiated. Between 2010 and 2014, we conducted interviews of Walloon and Luxembourg tenants (n = 33), surveys among potential tourists (n = 1148) in seven tourist places, interviews of privileged witnesses (n = 31), and field observations. Working on two regions of Western Europe which had not been analyzed previously, the Walloon and Luxembourg suburban countryside, we want to understand the agritourism dynamics, the factors that influence the location and development, and the images of farm tourism. The purpose of this research is to understand the geographical relationship between agritourism, countryside, local resources, agriculture, and tourism specialization. This issue is underdeveloped in the literature and our PhD thesis contributes to fill this gap. We scrutinize the spatial distribution of agritourism in both regions, the logic of emergence of tourism in a farm, the links between these tourist functions and these agricultural functions. We analysed the tenants and visitors’ reasons and motivations in regards of the regional and local context. Finally, we build a typology of the countryside according to agritourism. We conclude that the farm diversification should pay attention to several local and regional factors to succeed in a win-win combination of tourism and agriculture. These factors are listed in a heuristic model, which is a user-friendly tool to think future development of agritourism in the European countryside. [less ▲]

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See detailThe quest for rurality in Wallonia in 2013 (Belgium)
Schmitz, Serge ULg

in Bokwa, Anita (Ed.) Changes, Challenges Responsability. IGU 2014 Book of Abstarcts. (2014, August)

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See detailCharacterization of the Solidification Path, the Solid State Transformations and the Mechanical Behavior of a High Chromium Cast Steel
Tchuindjang, Jérôme Tchoufack ULg; Neira Torres, Ingrid; Habraken, Anne ULg et al

in Proceedings of the 5th Abrasion Conference - 2014 (2014, August)

The mechanical behavior of the fully austenitic matrix of a High Chromium Cast Steel (HCCS) alloy has been determined under external compression stress applied at 300°C and 700°C. The solidification path ... [more ▼]

The mechanical behavior of the fully austenitic matrix of a High Chromium Cast Steel (HCCS) alloy has been determined under external compression stress applied at 300°C and 700°C. The solidification path and the microstructure have been studied, including the nature and the critical temperature ranges for carbides formation, while using Differential Thermal Analysis and both Optical and Scanning Electron Microscopes. The microstructure has been characterized towards both Optical and SEM analyses. Differential Thermal Analysis and Dilatometry were used to study the solid state phase transformations on the one hand, and precipitation and dissolution reactions on the other hand, especially during heating from room temperature up to austenitization, and subsequent cooling down to room temperature. Dilatometry also helps setting the parameters for the preliminary thermal treatments to perform prior to compression tests, in order to allow more or less transition carbides within the stressed microstructure, the other carbides remaining undissolved. Flow stress curves and related work hardening rates were determined for both temperatures. From the compression tests, various strengthening phenomena, such as precipitation hardening and stress induced bainite transformation, and one softening mechanism such as recovery, have been highlighted, while enhancing at the same time the influence of the temperature and the carbide type on the mechanical behavior of the HCCS material. Cracks observed on grain boundaries primary carbides allow establishing a rough damage model. The crack initiation within the HCCS alloy seems to be strongly dependent on the temperature, the external applied stress and the matrix toughness. [less ▲]

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See detailAdvanced optimization methods for power systems
Panciatici, Patrick; Campi, M.C.; Garatti, S. et al

in Proceedings of the 18th Power Systems Computation Conference (2014, August)

Power system planning and operation offers multitudinous opportunities for optimization methods. In practice, these problems are generally large-scale, non-linear, subject to uncertainties, and combine ... [more ▼]

Power system planning and operation offers multitudinous opportunities for optimization methods. In practice, these problems are generally large-scale, non-linear, subject to uncertainties, and combine both continuous and discrete variables. In the recent years, a number of complementary theoretical advances in addressing such problems have been obtained in the field of applied mathematics. The paper introduces a selection of these advances in the fields of non-convex optimization, in mixedinteger programming, and in optimization under uncertainty. The practical relevance of these developments for power systems planning and operation are discussed, and the opportunities for combining them, together with high-performance computing and big data infrastructures, as well as novel machine learning and randomized algorithms, are highlighted. [less ▲]

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See detailCreation of universal MIR calibration by standardization of milk spectra: example of fatty acids
Grelet, Clément; Fernandez Pierna, Juan; Soyeurt, Hélène ULg et al

in Book of abstracts of the 65th annual meeting of the European Federation of Animal Science (2014, August)

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See detailA quantitative analysis of the effect of flexible loads on reserve markets
Mathieu, Sébastien ULg; Louveaux, Quentin ULg; Ernst, Damien ULg et al

in Proceedings of the 18th Power Systems Computation Conference (PSCC) (2014, August)

We propose and analyze a day-ahead reserve market model that handles bids from flexible loads. This pool market model takes into account the fact that a load modulation in one direction must usually be ... [more ▼]

We propose and analyze a day-ahead reserve market model that handles bids from flexible loads. This pool market model takes into account the fact that a load modulation in one direction must usually be compensated later by a modulation of the same magnitude in the opposite direction. Our analysis takes into account the gaming possibilities of producers and retailers, controlling load flexibility, in the day-ahead energy and reserve markets, and in imbalance settlement. This analysis is carried out by an agent-based approach where, for every round, each actor uses linear programs to maximize its profit according to forecasts of the prices. The procurement of a reserve is assumed to be determined, for each period, as a fixed percentage of the total consumption cleared in the energy market for the same period. The results show that the provision of reserves by flexible loads has a negligible impact on the energy market prices but markedly decreases the cost of reserve procurement. However, as the rate of flexible loads increases, the system operator has to rely more and more on non-contracted reserves, which may cancel out the benefits made in the procurement of reserves. [less ▲]

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See detailNumerical Investigation of Cooling in the Continuous Fiber Glass Drawing Process
Chouffart, Quentin ULg; Simon, Philippe; Terrapon, Vincent ULg

in Proceedings of the 15th International Heat Transfer Conference (2014, August)

The manufacturing process of glass fibers used for the reinforcement of composite material consists in drawing a glass melt at high temperature through an array of thousands of small orifices (i.e., the ... [more ▼]

The manufacturing process of glass fibers used for the reinforcement of composite material consists in drawing a glass melt at high temperature through an array of thousands of small orifices (i.e., the bushing plate) into fibers using a winder. This process is sensitive to numerous disturbances that can cause a fiber to break during the drawing process. This paper analyzes how the stress in the fiber depends on the controlling parameters of the process. The approach relies on numerical simulations and sensitivity analysis. Both a semi-analytical one-dimensional model and a more complex two-dimensional axisymmetric model are used. It is first found that radial variations across the fiber are small compared to changes in the axial direction and that the one-dimensional approximation is accurate enough to describe the major trends in the process. Sensitivity analyses on some physical parameters controlling the heat transfers and on process parameters are then performed to identify strategies to reduce the axial stress. In particular, it is shown that, for a given fiber diameter, the stress is minimized if the glass melt temperature and the drawing velocity are increased. This approach is then applied to quantify the effect of inhomogeneous heat patterns on a bushing plate with a large number of fibers. [less ▲]

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See detailOperational experience with Dynamic Line Rating forecast-based solutions to increase usable network transfer capacity
Nguyen, Huu-Minh ULg; Lambin, Jean-Jacques; Vassort, Frédéric et al

in Proceedings of the 45th session of the Council on Large Electric Systems (CIGRE) (2014, August)

This proposed paper focuses on the criteria that need to be met to allow network operators to effectively use Dynamic Line Ratings in real-life operations. Different pilot projects in Europe and around ... [more ▼]

This proposed paper focuses on the criteria that need to be met to allow network operators to effectively use Dynamic Line Ratings in real-life operations. Different pilot projects in Europe and around the world have proven the DLR technology works in the field. The paper will highlight the experience the Belgian TSO, Elia, has had regarding those questions. The specific aspects detailed here is the usability of day-ahead forecasting of DLR. Indeed, most decisions regarding network operation and Electricity Market are taken many hours/days in advance; therefore if DLR is to influence these decisions, a reliable forecast of the dynamic rating values is required. Two-day ahead DLR forecast has shown an average capacity improvement of more than 10% over seasonal rating with 98% confidence, and potential impact on the European market regarding congestion issues is presented. The paper will further highlight 3 years of operation of two critical lines located near the North Sea and impacted by the connection of off-shore wind resources using intra-day and day-ahead forecasting of DLR. The conclusion of those experiences shows that innovative solutions emerge from two-day ahead ampacity forecast provided by DLR. [less ▲]

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See detailAn AC OPF-based Heuristic Algorithm for Optimal Transmission Switching
Capitanescu, Florin; Wehenkel, Louis ULg

in Proceedings of the 18th Power Systems Computation Conference (2014, August)

This paper focuses on reducing generators dispatch cost by means of transmission line switching. The problem is formulated as a mixed-integer nonlinear program (MINLP) optimal power flow (OPF). A scalable ... [more ▼]

This paper focuses on reducing generators dispatch cost by means of transmission line switching. The problem is formulated as a mixed-integer nonlinear program (MINLP) optimal power flow (OPF). A scalable heuristic algorithm is proposed to break-down the complexity of the problem due to the huge combinatorial space. The algorithm aims at providing the sequence of lines to be removed from service, one at the time, until no further decrease in the dispatch cost can be obtained. It identifies the line candidate for removal at each step by exploiting the (continuously relaxed values of) lines breaker statuses at the solution of a relaxed OPF problem. The algorithm thus relies on solving a sequence of OPF problems formulated as nonlinear programs (NLPs). The effectiveness of the approach is demonstrated on the IEEE118-bus system. Results show that the approach can provide good quality sub-optimal solutions with relatively small computational effort and by removing only few lines from service. [less ▲]

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See detailInnovative lactation stage specific prediction of CH4 from milk MIR spectra
Vanlierde, Amélie; Vanrobays, Marie-Laure ULg; Dehareng, Frédéric et al

in Book of abstracts of the 65th annual meeting of the European Federation of Animal Science (2014, August)

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See detailPrediction of Body Weight of Primiparous Dairy Cows Throughout Lactation
Vanrobays, Marie-Laure ULg; Vandenplas, Jérémie ULg; Hammami, Hedi ULg et al

in Proceedings of the 10th World Congress on Genetics Applied to Livestock Production (2014, August)

Body weight (BW) can be computed using linear conformation traits (CBW). However, these traits are recorded mostly once during a lactation. Therefore, predicted BW (PBW) is needed throughout the lactation ... [more ▼]

Body weight (BW) can be computed using linear conformation traits (CBW). However, these traits are recorded mostly once during a lactation. Therefore, predicted BW (PBW) is needed throughout the lactation (e.g., allowing feed intake prediction in milk recording systems). A two-step procedure was developed to obtain PBW using a random regression test-day model using CBW as observations. Added second step consisted in changing prior distribution for additive genetic random effects using results from first step to predict again PBW. This method was applied on 24,919 primiparous Holstein cows having 25,061 CBW to obtain PBW for 232,436 test-days. Results showed that applying both steps provided more accurate estimates than using only the first step. Furthermore, this procedure predicting PBW throughout lactation is also extremely flexible because actual BW can also be used together with CBW, the prediction model being able to accommodate different levels of accuracies. [less ▲]

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See detailStructural Identifiability Analysis of a Cardiovascular System Model
Pironet, Antoine ULg; Dauby, Pierre ULg; Chase, J. Geoffrey et al

in Preprints of the 19th World Congress (2014, August)

A simple experimentally validated cardiovascular system model has been shown to be able to track the evolution of various diseases. The model has previously been made patient-specific by adjustment of its ... [more ▼]

A simple experimentally validated cardiovascular system model has been shown to be able to track the evolution of various diseases. The model has previously been made patient-specific by adjustment of its parameters on the basis of a minimal set of hemodynamic measurements. However, this model has not yet been shown to be structurally identifiable, which means that the adjusted model parameters may not be unique. The model equations were manipulated to show that, from a theoretical point of view, all of their parameters can be exactly retrieved from a restricted set of model outputs. However, this set of model outputs is still too large for a clinical application, because it includes left and right ventricular pressures. Consequently, further hypotheses that determine some model parameter values have to be made for the model to be clinically applicable. [less ▲]

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See detailSurvey about diffusion and adoption of glycaemic controller in European intensive care units
Penning, Sophie ULg; Pironet, Antoine ULg; Chase, J. Geoffrey et al

in Proceedings of the 19th IFAC Conference (2014, August)

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See detailDetection of wheat root and straw in soil by use of NIR hyperspectral imaging spectroscopy and Partial Least Square discriminant analysis
Eylenbosch, Damien ULg; Fernández Pierna, Juan Antonio; Baeten, Vincent et al

in Szilvássy, Zoltán; Pepó, Péter; Csajbók, József (Eds.) Book of Abstracts, ESA XIIIth Congress : ESA, Debrecen 25-29 August 2014 (2014, August)

Monitoring of root systems development and crop residues decomposition is only possible if these constituents can be discriminated from soil and quantified. In this work, Near Infrared (NIR) combined with ... [more ▼]

Monitoring of root systems development and crop residues decomposition is only possible if these constituents can be discriminated from soil and quantified. In this work, Near Infrared (NIR) combined with Hyperspectral Imaging (HSI) and Partial Least Square Discriminant Analysis (PLS-DA) is proposed as a new rapid and reliable method to discriminate soil, roots and straws. NIR-HSI provides simultaneously spectral and spatial information and PLS-DA allows discrimination between classes based on spectra of each pixel linked to chemical nature of sample constituents on the image. [less ▲]

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See detailAssessment of pulmonary hypertension in dogs with chronic pulmonary diseases by thoracic ct-angiography.
Couvreur, T.; Roels, Elodie ULg; Merveille, Anne-Christine ULg et al

in Proceedings of the ECVDI Meeting, Utrecht - Netherlands - 27-30 August 2014 (2014, August)

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See detailUsing milk spectral data for large-scale phenotypes linked to mitigation and efficiency
Soyeurt, Hélène ULg; Vanlierde, Amélie; Vanrobays, Marie-Laure ULg et al

in Book of abstracts of the 65th annual meeting of the European Federation of Animal Science (2014, August)

Even if producing milk efficiently has always been a major concern for producers, the direct environmental impact of their cows is becoming a novel one. Traits linked to this issue were identified as ... [more ▼]

Even if producing milk efficiently has always been a major concern for producers, the direct environmental impact of their cows is becoming a novel one. Traits linked to this issue were identified as methane emission (CH4), dry matter intake (DMI) and feed efficiency (FE); however they are available on a small scale. Researches showed that CH4 could be predicted from milk mid-infrared (MIR) spectra, allowing large-scale recording at low cost. The main objective of this study was to show, using a modelling approach, that DMI and FE could be derived from milk MIR spectra. For that, knowledge of body weight (BW) is required; however it was unknown in this study. Derived procedure was based on milk yield and composition, MIR CH4, and modelled standard animal requirements, allowing the prediction of expected BW. An external validation was conducted based on 91 actual records. 95% confidence limit for the difference ranged between -0.66 and 18.84 kg for BW, from -0.02 to 0.26 kg/day for DMI, and from -0.02 to 0.002 kg of fat corrected milk/kg DM for FE. Root mean square errors were 39.66 kg, 0.56 kg/d, and 0.03 kg/DM for the 3 studied traits. P-value for the t-test was not significant for BW and DMI. This suggests the possibility to obtain expected BW and therefore DMI from MIR spectra. Single trait animal test-day models used 1,291,850 records to assess the variability of studied traits. Significant variations were observed for the lactation stage, parity, genetics, and age. These findings were in agreement with the literature except for early lactation. This suggests in conclusion that the MIR information gave similar results for DMI and CH4 for the major part of lactation. The use of this novel method to predict expected BW offers new possibilities interesting for the development of genomic and genetic tools. [less ▲]

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See detailCombining magnetic and seismic studies to constrain processes in massive stars
Neiner, C.; Degroote, P.; Coste, B. et al

in IAUS 302 - Magnetic Fields Throughout Stellar Evolution (2014, August)

The presence of pulsations influences the local parameters at the surface of massive stars and thus it modifies the Zeeman magnetic signatures. Therefore it makes the characterisation of a magnetic field ... [more ▼]

The presence of pulsations influences the local parameters at the surface of massive stars and thus it modifies the Zeeman magnetic signatures. Therefore it makes the characterisation of a magnetic field in pulsating stars more difficult and the characterisation of pulsations is thus required for the study of magnetic massive stars. Conversely, the presence of a magnetic field can inhibit differential rotation and mixing in massive stars and thus provides important constraints for seismic modelling based on pulsation studies. As a consequence, it is necessary to combine spectropolarimetric and seismic studies for all massive classical pulsators. Below we show examples of such combined studies and the interplay between physical processes. [less ▲]

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See detailA relaxation scheme to combine Phasor-Mode and Electromagnetic Transients Simulations
Plumier, Frédéric ULg; Aristidou, Petros ULg; Geuzaine, Christophe ULg et al

in Proceedings of the 18th Power System Computation Conference (2014, August)

This paper deals with a new scheme for coupling phasor-mode and electromagnetic transients simulations. In each simulation, an iteratively updated linear equivalent is used to represent the effect of the ... [more ▼]

This paper deals with a new scheme for coupling phasor-mode and electromagnetic transients simulations. In each simulation, an iteratively updated linear equivalent is used to represent the effect of the subsystem treated by the other simulation. Time interpolation and phasor extraction methods adapted to this scheme are presented and compared to existing methods. Finally, simulation results obtained with a 74-bus test system are reported. [less ▲]

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See detailInsulin Sensitivity Variability during Hypothermia
Sah Pri, Azurahisham; Chase, J. Geoffrey; Pretty, Christopher et al

in Proceedings of the 19th IFAC Conference (2014, August)

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See detailEnhancement of ray tracing method for radiative heat transfer: application to EUI space instrument
Jacques, Lionel ULg; Masset, Luc ULg; Kerschen, Gaëtan ULg

in Proceedings of the 15th International Heat Transfer Conference, IHTC-15 (2014, August)

The finite element method (FEM) is widely used in mechanical engineering, in particular for space structure design. However, FEM is not yet often used for thermal engineering of space structures where the ... [more ▼]

The finite element method (FEM) is widely used in mechanical engineering, in particular for space structure design. However, FEM is not yet often used for thermal engineering of space structures where the lumped parameter method is still dominant. Radiative exchange factors (REFs), used to calculate radiative thermal exchanges in space, are usually computed through Monte Carlo ray tracing. Due to the large number of elements composing a FE model, the computation of the REFs is prohibitively expensive. The isocell method aims at reducing the computational effort of the REFs with FEM, by decreasing the number of rays required to achieve a given accuracy. Based on Nusselt’s analogy, the ray direction sampling is carried out by sampling the unit disc to derive the ray directions. The isocell method is a special case of stratified sampling. It divides the unit disc into cells of almost same area and shape from which random points are generated. This enhances the uniformity of the ray directions and leads to faster convergence. This isocell method is associated with different surface sampling to derive the REFs. The method is benchmarked against ESARAD, the standard thermal analysis ray tracing engine used in the European aerospace industry. One entrance baffle of the Extreme Ultraviolet Imager (EUI) instrument developedat the Centre Spatial de Liège in Belgium is used as benchmarking case. Solar Orbiter is an European Space Agency mission to be launched in a Sun-centered 0.28 perihelion orbit. [less ▲]

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See detailImproving dairy cow fertility using milk-based indicator traits
Bastin, Catherine ULg; Vandenplas, Jérémie ULg; Gengler, Nicolas ULg

in Proceedings of the 10th World Congress on Genetics Applied to Livestock Production (2014, August)

Improvement of dairy cow fertility by means of genetic selection has become increasingly important over the last decades. Because fertility traits are difficult to measure and have low heritabilities ... [more ▼]

Improvement of dairy cow fertility by means of genetic selection has become increasingly important over the last decades. Because fertility traits are difficult to measure and have low heritabilities, indicator traits are of interest to supplement the prediction of genetic merit for female fertility. This paper examines milk-based traits that could be potential predictor of fertility: changes in protein and fat composition, fat to protein ratio, urea, lactose, ketone bodies, and mid-infrared prediction of body energy traits. The pattern of genetic correlations between these traits and fertility over days in milk is likely related to the cow’s energy balance state. Furthermore, changes in milk fatty acid profile were demonstrated as good potential predictors of fertility. Finally, additional research is warranted to investigate the association over the lactation between fertility and changes in milk biomarkers, potentially predicted by mid-infrared analysis of milk. [less ▲]

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See detailRelaxations for multi-period optimal power flow problems with discrete decision variables
Gemine, Quentin ULg; Ernst, Damien ULg; Louveaux, Quentin ULg et al

in Proceedings of the 18th Power Systems Computation Conference (PSCC'14) (2014, August)

We consider a class of optimal power flow (OPF) applications where some loads offer a modulation service in exchange for an activation fee. These applications can be modeled as multi-period formulations ... [more ▼]

We consider a class of optimal power flow (OPF) applications where some loads offer a modulation service in exchange for an activation fee. These applications can be modeled as multi-period formulations of the OPF with discrete variables that define mixed-integer non-convex mathematical programs. We propose two types of relaxations to tackle these problems. One is based on a Lagrangian relaxation and the other is based on a network flow relaxation. Both relaxations are tested on several benchmarks and, although they provide a comparable dual bound, it appears that the constraints in the solutions derived from the network flow relaxation are significantly less violated. [less ▲]

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See detailModel-Based Computation of Total Stressed Blood Volume from a Preload Reduction Experiment
Pironet, Antoine ULg; Desaive, Thomas ULg; Chase, J. Geofrrey et al

in Preprints of the 19th World Congress (2014, August)

Total stressed blood volume is an important parameter for both doctors and engineers. From a medical point of view, it has been associated with the success or failure of fluid resuscitation therapy, which ... [more ▼]

Total stressed blood volume is an important parameter for both doctors and engineers. From a medical point of view, it has been associated with the success or failure of fluid resuscitation therapy, which is a treatment for cardiac failure. From an engineering point of view, this parameter dictates the cardiovascular system’s dynamic behavior. Current methods to determine this parameter involve repeated phases of circulatory arrests followed by fluid administration. In this work, a method is developed to compute stressed blood volume from preload reduction experiments. A simple six-chamber cardiovascular system model is used and its parameters are adjusted to pig experimental data. The parameter adjustment process has three steps: (1) compute nominal values for all model parameters; (2) determine the most sensitive parameters; and (3) adjust only these sensitive parameters. Stressed blood volume was determined sensitive for all datasets, which emphasizes the importance of this parameter. The model was able to track experimental trends with a maximal mean squared error of 11.77 %. Stressed blood volume has been computed to range between 450 and 963 ml, or 15 to 28 ml/kg, which matches previous independent experiments on pigs, dogs and humans. Consequently, the method proposed in this work provides a simple way to compute total stressed blood volume from usual hemodynamic data. [less ▲]

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See detailImprovement of defect detection in shearography by using Principal Component Analysis
Vandenrijt, Jean-François ULg; Lièvre, Nicolas; Georges, Marc ULg

in Proceedings of Conference on Interferometry XVII: Techniques and Analysis (2014, August)

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See detailAlgorithmic and Computational Advances for Fast Power System Dynamic Simulations
Aristidou, Petros ULg; Van Cutsem, Thierry ULg

in Proceedings of the IEEE PES General Meeting (2014, July 30)

In this paper, some algorithmic and computational advances are presented for power system dynamic simulations. The heart is a Schur-complement-based solution algorithm, stemming from domain decomposition ... [more ▼]

In this paper, some algorithmic and computational advances are presented for power system dynamic simulations. The heart is a Schur-complement-based solution algorithm, stemming from domain decomposition methods, applied to the differential-algebraic equation model. This algorithm is then accelerated computationally, by employing parallel computing techniques, and numerically, by exploiting time-scale decomposition and localization. Models of a real medium-scale system and a realistic large-scale test system are used for the performance evaluation of the proposed methods. [less ▲]

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See detailUnveiling new stellar companions from the PIONIER exozodi survey
Marion, Lindsay ULg; Absil, Olivier ULg; Ertel, S. et al

in Rajagopal, Jayadev; Creech-Eakman; Malbet, Fabien (Eds.) Optical and Infrared Interferometry IV (2014, July 24)

The main goal of the EXOZODI survey is to detect and characterize circumstellar dust and to propose the first statistical study of exozodiacal disks in the near-infrared using telescopes in both ... [more ▼]

The main goal of the EXOZODI survey is to detect and characterize circumstellar dust and to propose the first statistical study of exozodiacal disks in the near-infrared using telescopes in both hemispheres (VLTI and CHARA). For this purpose, Ertel et al. have conducted in 2012 a survey of nearby main sequence stars with VLTI/PIONIER to search for the presence of circumstellar dust. This survey, carried out during 12 nights, comprises about 100 stars. For each star, we obtained typically three OBs and we searched for circumstellar emission based on the measurement of squared visibilities at short baselines. A drop in the measured visibilities with respect to the expected photospheric visibility indicates the presence of resolved emission around the target star. It is however generally not possible to conclude on the morphology of the detected emission based solely on the squared visibilities. Here, we focus on closure phases to search systematically for faint companions around the whole sample. Indeed, to derive robust statistics on the occurrence rate of bright exozodiacal disks, we need to discriminate between companions and disks. For this reason, the main goal of this paper is to discriminate between circumstellar disks (which show no closure phase provided that they are point-symmetric) and faint companions (point-like sources, creating non-zero closure phases). We also aim to reveal new companions that do not necessarily produce a significant signature in the squared visibilities, as the signature of the companion may show up more prominently in the closure phases. In this process, we reveal four new stellar companions with contrasts ranging from 2% to 95% (i.e., up to near-equal flux binaries). We also tentatively detect faint companions around one other target that will require follow-up observations to be confirmed or infirmed. We discuss the implications of these discoveries on the results of the exozodi survey. [less ▲]

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See detailRécits de vie d’adolescents. Humeur dépressive et figures parentales
Poudat, Céline; Boulard, Aurore ULg

in 4ème Congrès Mondial de Linguistique Française (2014, July 22)

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See detailThe VORTEX project: first results and perspectives
Absil, Olivier ULg; Mawet, Dimitri; Delacroix, Christian ULg et al

in Marchetti, Enrico; Close, Laird; Véran, Jean-Pierre (Eds.) Adaptive Optics Systems IV (2014, July 21)

Vortex coronagraphs are among the most promising solutions to perform high contrast imaging at small angular separations from bright stars. They feature a very small inner working angle (down to the ... [more ▼]

Vortex coronagraphs are among the most promising solutions to perform high contrast imaging at small angular separations from bright stars. They feature a very small inner working angle (down to the diffraction limit of the telescope), a clear 360 degree discovery space, have demonstrated very high contrast capabilities, are easy to implement on high-contrast imaging instruments, and have already been extensively tested on the sky. Since 2005, we have been designing, developing and testing an implementation of the charge-2 vector vortex phase mask based on concentric sub-wavelength gratings, referred to as the Annular Groove Phase Mask (AGPM). Science-grade mid-infrared AGPMs were produced in 2012 for the first time, using plasma etching on synthetic diamond substrates. They have been validated on a coronagraphic test bench, showing broadband peak rejection up to 500:1 in the L band, which translates into a raw contrast of about 6e-5 at 2λ/D. Three of them have now been installed on world-leading diffraction-limited infrared cameras, namely VLT/NACO, VLT/VISIR and LBT/LMIRCam. During the science verification observations with our L-band AGPM on NACO, we observed the beta Pictoris system and obtained unprecedented sensitivity limits to planetary companions down to the diffraction limit (0.1"). More recently, we obtained new images of the HR 8799 system at L band during the AGPM first light on LMIRCam. After reviewing these first results obtained with mid-infrared AGPMs, we will discuss the short- and mid-term goals of the on-going VORTEX project, which aims to improve the performance of our vortex phase masks for future applications on second-generation high-contrast imager and on future extremely large telescopes (ELTs). In particular, we will briefly describe our current efforts to improve the manufacturing of mid-infrared AGPMs, to push their operation to shorter wavelengths, and to provide deeper starlight extinction by creating new designs for higher topological charge vortices. Within the VORTEX project, we also plan to develop new image processing techniques tailored to coronagraphic images, and to study some pre- and post-coronagraphic concepts adapted to the vortex coronagraph in order to reduce scattered starlight in the final images. [less ▲]

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See detailThe VORTEX coronagraphic test bench
Jolivet, Aïssa ULg; Piron, Pierre ULg; Huby, Elsa ULg et al

in Navarro, Ramon; Cunningham, Colin; Barto, Allison (Eds.) Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation (2014, July 18)

In this paper, we present the infrared coronagraphic test bench of the University of Liège named VODCA (Vortex Optical Demonstrator for Coronagraphic Applications). The goal of the bench is to assess the ... [more ▼]

In this paper, we present the infrared coronagraphic test bench of the University of Liège named VODCA (Vortex Optical Demonstrator for Coronagraphic Applications). The goal of the bench is to assess the performances of the Annular Groove Phase Masks (AGPMs) at near- to mid-infrared wavelengths. The AGPM is a subwavelength grating vortex coronagraph of charge two (SGVC2) made out of diamond. The bench is designed to be completely achromatic and will be composed of a super continuum laser source emitting in the near to mid-infrared, several parabolas, diaphragms and an infrared camera. This way, we will be able to test the different AGPMs in the M, L, K and H bands. Eventually, the bench will also allow the computation of the incident wavefront aberrations on the coronagraph. A reflective Lyot stop will send most of the stellar light to a second camera to perform low-order wavefront sensing. This second system coupled with a deformable mirror will allow the correction of the wavefront aberrations. We also aim to test other pre- and/or post-coronagraphic concepts such as optimal apodization. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only. [less ▲]

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See detailApplication of multiple-point geostatistics on groundwater flow and transport in media with complex geological heterogeneity: lessons learnt and remaining challenges
Huysmans, Marijke; Dassargues, Alain ULg

in Proceedings (2014, July 09)

Multiple-point geostatistics has been increasingly applied on groundwater problems in the last ten years. Several case studies have been published indicating simulating realistic geological heterogeneity ... [more ▼]

Multiple-point geostatistics has been increasingly applied on groundwater problems in the last ten years. Several case studies have been published indicating simulating realistic geological heterogeneity using multiple-point geostatistics can significantly improve groundwater flow and solute transport predictions. There are however several remaining challenges when applying multiple-point geostatistics to groundwater problems often suffering from data scarcity. These challenges might be the reason why multiple-point has been used to a much lesser extent by practitioners than by researchers. This paper gives an overview of the current challenges and discusses new advancements to overcome them. The following questions will be discussed: How to obtain 3D training images? Can the representativity of the used training image be validated ? How sensitive are groundwater calculations to the selection of the training image? Is it worth incorporating fine scale geological heterogeneity in groundwater problems or are other features (boundary conditions, data uncertainty/quality, …) more important for improving predictions? How can multiple-point geostatistics be used without suffering from very long computation times for the numerical models? Is overparametrization of groundwater models an issue ? What are the practical obstacles to apply multiple-point geostatistics by groundwater practitioners? [less ▲]

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Peer Reviewed
See detailMicrobial communities associated to common bean seed - A mechanism of local adaptation of plants?
Klaedtke, Stephanie ULg; Barret, Mathieu; Chable, Véronique et al

in Chable, V; Goldringer, I; Howlett, SA (Eds.) et al Diversity strategies for organic and low input agricultures and their food systems .Book of abstracts of Solibam final congress, Nantes, 7-9 July 2014 (2014, July 08)

The effects of crop genotype and cultivation site on microbial communities associated to seed of Phaseolus vulgaris were assessed on 33 seed lots. These seed lots were obtained by multiplying 5 initial ... [more ▼]

The effects of crop genotype and cultivation site on microbial communities associated to seed of Phaseolus vulgaris were assessed on 33 seed lots. These seed lots were obtained by multiplying 5 initial seed lots of different cultivars in two contrasting environments for 2 years in 3 replicates. An additional commercial control lot was introduced the second year. The diversity of fungal and bacterial communities was analyzed by high-throughput sequencing of the bacterial 16S rRNA gene and the fungal ITS1 region, respectively. Results showed that the structure of the fungal and the bacterial communities is significantly affected by the cultivation site. [less ▲]

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See detailAspects of non-smooth dynamics in models of percussion
Depouhon, Alexandre; Detournay, Emmanuel; Denoël, Vincent ULg

in Proceedings of the 8th European Nonlinear Dynamics Conference (2014, July 08)

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See detailDevelopment of a subwavelength grating vortex coronagraph of topological charge 4 (SGVC4)
Delacroix, Christian ULg; Absil, Olivier ULg; Carlomagno, Brunella ULg et al

in Ramsay, Suzanne; McLean, Ian; Takami, Hideki (Eds.) Ground-based and Airborne Instrumentation for Astronomy V (2014, July 08)

One possible solution to achieve high contrast direct imaging at a small inner working angle (IWA) is to use a vector vortex coronagraph (VVC), which provides a continuous helical phase ramp in the focal ... [more ▼]

One possible solution to achieve high contrast direct imaging at a small inner working angle (IWA) is to use a vector vortex coronagraph (VVC), which provides a continuous helical phase ramp in the focal plane of the telescope with a phase singularity in its center. Such an optical vortex is characterized by its topological charge, i.e., the number of times the phase accumulates 2pi radians along a closed path surrounding the singularity. Over the past few years, we have been developing a charge-2 VVC induced by rotationally symmetric subwavelength gratings (SGVC2), also known as the Annular Groove Phase Mask (AGPM). Since 2013, several SGVC2s (or AGPMs) were manufactured using synthetic diamond substrate, then validated on dedicated optical benches, and installed on 10-m class telescopes. Increasing the topological charge seems however mandatory for cancelling the light of bright stars which will be partially resolved by future Extremely Large Telescopes in the near-infrared. In this paper, we first detail our motivations for developing an SGVC4 (charge 4) dedicated to the near-infrared domain. The challenge lies in the design of the pattern which is unrealistic in the theoretically perfect case, due to state-of-the-art manufacturing limitations. Hence, we propose a new realistic design of SGVC4 with minimized discontinuities and optimized phase ramp, showing conclusive improvements over previous works in this field. A preliminary validation of our concept is given based on RCWA simulations, while full 3D finite-difference time-domain simulations (and eventually laboratory tests) will be required for a final validation. [less ▲]

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See detailMid-IR AGPMs for ELT applications
Carlomagno, Brunella ULg; Delacroix, Christian ULg; Absil, Olivier ULg et al

in Ramsay, Suzanne; McLean, Ian; Takami, Hideki (Eds.) Ground-based and Airborne Instrumentation for Astronomy V (2014, July 08)

The mid-infrared region is well suited for exoplanet detection thanks to the reduced contrast between the planet and its host star with respect to the visible and near-infrared wavelength regimes. This ... [more ▼]

The mid-infrared region is well suited for exoplanet detection thanks to the reduced contrast between the planet and its host star with respect to the visible and near-infrared wavelength regimes. This contrast may be further improved with Vector Vortex Coronagraphs (VVCs), which allow us to cancel the starlight. One flavour of the VVC is the AGPM (Annular Groove Phase Mask), which adds the interesting properties of subwavelength gratings (achromaticity, robustness) to the already known properties of the VVC. In this paper, we present the optimized designs, as well as the expected performances of mid-IR AGPMs etched onto synthetic diamond substrates, which are considered for the E-ELT/METIS instrument. [less ▲]

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See detailComparaison entre le profil vertical de la vitesse du vent observé dans les basses couches de la troposphère et celui simulé par le modèle WRF en Belgique
Doutreloup, Sébastien ULg; Fettweis, Xavier ULg; Beaumet, Julien ULg et al

in Camberlin, Pierre; Richard, Yves (Eds.) Actes du XXVIIe Colloque de l'Association Internationale de Climatologie : CLIMAT : SYSTÈME & INTERACTIONS (2014, July 02)

In the framework of FLEXIPAC project funded by the "RELIABLE" program of Walloon Region (Belgium), the Laboratory of Climatology Topoclimatology (LCT) of the University of Liège (Belgium) aims to adjust ... [more ▼]

In the framework of FLEXIPAC project funded by the "RELIABLE" program of Walloon Region (Belgium), the Laboratory of Climatology Topoclimatology (LCT) of the University of Liège (Belgium) aims to adjust the WRF regional model (v.3.4.) forced by the ERA-Interim reanalysis for Belgium. Our analysis shows that wind speeds at 100m simulated by WRF are systematically overestimated compared to wind speeds extracted from wind productions of two wind farms. In order to solve this problem, four ways are considered in this contribution. The first way is to compare the WRF model with the reanalysis data. The second way is to test the influence of the spatial resolution by running WRF with a finer resolution. The third way is to smooth WRF outputs, where in order to analyze the variability created by the model. And finally, the fourth way is to compare the WRF model with the MAR (v3.3.) regional model. This last way seems to confirm that the MAR model better simulates wind speeds at 10m and at 100m than the WRF model. [less ▲]

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See detailMICROPHYSIQUE DES NUAGES ET RAYONNEMENT SOLAIRE : COMPARAISON DES MESURES IN SITU AU MONT RIGI EN HAUTE BELGIQUE ET DES DONNÉES CLOUD PHYSICAL PROPERTIES (CPP) OBTENUES À PARTIR DES IMAGES METEOSAT-9
Beaumet, Julien ULg; Clerbaux, Nicolas; Cornet, Yves ULg et al

in Camberlin, Pierre; Richard, Yves (Eds.) Actes du XXVIIe Colloque de l'Association Internationale de Climatologie : CLIMAT : SYSTÈME & INTERACTIONS (2014, July 02)

Le rayonnement solaire global mesuré au mont Rigi a été comparé à l'épaisseur optique des nuages (COT) estimée à l'aide des données SEVIRI. Une relation logarithmique avec un coefficient de détermination ... [more ▼]

Le rayonnement solaire global mesuré au mont Rigi a été comparé à l'épaisseur optique des nuages (COT) estimée à l'aide des données SEVIRI. Une relation logarithmique avec un coefficient de détermination d'environ 0,5 a été trouvée. Ce résultat plutôt faible peut en grande partie s'expliquer par un nombre limité de cas où subsistent des erreurs de positionnement ou par des interactions plus complexes entre nébulosité et rayonnement. De plus, l'incertitude sur l'estimation de l'épaisseur optique des nuages à l'aide des données SEVIRI pour les nuages optiquement plus épais n'est pas négligeable. [less ▲]

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See detailWater, hydrogen cyanide, and dust production from the distant comet 29P/Scwassmann-Wachmann 1
Bockelee-Morvan, D.; Biver, N.; Opitom, Cyrielle ULg et al

in Muinonen, Karri (Ed.) Asteroids, Comets, Meteors - Book of Abstracts (2014, July 01)

Comet 29P/Schwassmann-Wachmann is a periodic comet, also classified as a Centaur, orbiting on a nearly circular orbit at 6 au from the Sun. It is well known for its permanent activity driven by CO ... [more ▼]

Comet 29P/Schwassmann-Wachmann is a periodic comet, also classified as a Centaur, orbiting on a nearly circular orbit at 6 au from the Sun. It is well known for its permanent activity driven by CO outgassing, and its episodic outbursts. Comet 29P was observed in 2010--2011 with the Herschel space observatory. Observations of water and ammonia were performed with the Heterodyne Instrument for the Far-Infrared (HIFI). One set of measurements was obtained two days after a major outburst (16 Apr. 2010). Images of the dust coma at 70 and 160 μ m were obtained using the Photodetector Array Camera and Spectrometer (PACS). To support these observations, observations of CO and HCN were undertaken at the 30-m telescope of the Institut de radioastronomie millimétrique (IRAM). We present an overview of this set of observations. H_2O and CO are detected. We also obtain the first detection of HCN in this distant comet. Relative abundances are similar to those measured in the coma of comet C/1995 O1 (Hale-Bopp) when at r_h = 6 au from the Sun, but strongly differ from coma compositions at r_h = 1 au. The line profiles show evidence that both H_2O, HCN are released from long-lived icy grains. Detailed modeling of water production from icy-grain suggests continuous release of icy grains from the nucleus. The thermal emission from the nucleus is detected in the PACS 70 μ m images. The thermal emission from dust grains is analyzed with a thermal model of dust emission, which takes into account the dust size distribution. Both the size index and the dust production rate are measured. [less ▲]

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See detailTRAPPIST monitoring of comets C/2012 S1 (ISON) and C/2013 R1 (Lovejoy)
Opitom, Cyrielle ULg; Jehin, Emmanuel ULg; Manfroid, Jean ULg et al

in Muinonen, Karri (Ed.) Asteroids, Comets, Meteors - Book of Abstracts (2014, July 01)

We present the results of a dense photometric monitoring of comets C/2012 S1 (Ison) and C/2013 R1 (Lovejoy) using narrow-band cometary filters and the 60-cm TRAPPIST robotic telescope [1]. We were able to ... [more ▼]

We present the results of a dense photometric monitoring of comets C/2012 S1 (Ison) and C/2013 R1 (Lovejoy) using narrow-band cometary filters and the 60-cm TRAPPIST robotic telescope [1]. We were able to isolate the emission of the OH, NH, CN, C_2, and C_3 radicals for both comets as well as the dust continuum in four bands. By applying a Haser model [2] and fitting the observed profiles, we derive gas production rates. From the continuum bands, we computed the dust Afρ parameters [3]. We were able to follow the evolution of the gas and dust activity of these comets for weeks, looking for changes with the heliocentric distance, study the coma morphology, and analyze their composition and dust coma properties. Comet C/2012 S1 (ISON) was observed about three times a week from October 12 (r=1.43 au) to November 23, 2013. It was then at a heliocentric distance of 0.33 au, only five days before perihelion, when it disintegrated. This dense monitoring allowed us to detect fast changes of the cometary activity. We observed a slowly rising activity in October and early November, and two major outbursts around November 13 and November 19 [4], the gas and dust production rates being multiplied by at least a factor of five during each outburst and then slowly decreasing in the following days. These outbursts were correlated with changes in gas-production-rate ratios. The coma morphology study revealed strong jets in both gas and dust filters. Since the comet was very active in November, we were even able to detect OH jets in our images. Comet C/2013 R1 (Lovejoy) was observed before perihelion from September 9 (r=1.94 au) to November 16 (r=1.12 au), 2013 when the comet was too far North. We recovered the comet post-perihelion on February 13 (r=1.24 au), 2014 and planned to observe it until May (r=2.5 au) with narrow-band filters. We compare the evolution of gas and dust activity as well as the evolution of gas production rates ratios on both sides of perihelion. The morphological study of both gas and dust coma we already performed on pre-perihelion images revealed structures in gas and dust filters. We compare the gas and dust features in all filters and study their evolution. [less ▲]

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See detailHigh-resolution spectra of comet C/2013 R1 (Lovejoy)
Rousselot, P.; Decock, A.; Jehin, Emmanuel ULg et al

in Muinonen, Karri (Ed.) Asteroids, Comets, Meteors - Book of Abstracts (2014, July 01)

Comet C/2013 R1 (Lovejoy) is a long-period comet discovered on 7 September 2013 by Terry Lovejoy with a 0.2-m telescope (Guido et al., 2013), it passed its perihelion (0.81 au) on 22 December 2013. It was ... [more ▼]

Comet C/2013 R1 (Lovejoy) is a long-period comet discovered on 7 September 2013 by Terry Lovejoy with a 0.2-m telescope (Guido et al., 2013), it passed its perihelion (0.81 au) on 22 December 2013. It was a bright comet visible to the naked eye. We obtained high-resolution spectra of this comet immediately after its perihelion passage during 4 nights in the period 23-26 December 2013. These spectra have been obtained with the 3.5-m Telescopio Nazionale Galileo (TNG) and the High Accuracy Radial velocity Planet Searcher in North hemisphere (HARPS-N) echelle spectrograph. HARPS-N is an echelle spectrograph covering the spectral range from 383 to 693 nm, with a spectral resolution of R=115000 (Cosentino et al., 2012). It is designed to measure stellar radial velocities in view of detecting extrasolar planets. Our observations are the first successful cometary observations performed with this instrument. They demonstrate that this spectrograph can also be efficient for getting cometary spectra, even if the sensitivity of this instrument is low in the blue part of its spectral coverage. We will present the results of our data analysis for these spectra. This analysis is focused on isotopic ratios, mainly ^{12}C/^{13}C with C_2 emission lines (with the method described in Rousselot et al. 2012) and ^{14}N/^{15}N with ^{14}NH_2 and ^{15}NH_2 emission lines (with the line wavelengths given in Rousselot et al. 2014), atomic oxygen emission lines at 557.7, 630.0 and 636.4 nm (intensity ratios and widths, see Decock et al. 2013) and relative production rates of the detected species. [less ▲]

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See detailThe TRAPPIST comet survey
Jehin, Emmanuel ULg; Opitom, Cyrielle ULg; Manfroid, Jean ULg et al

in Muinonen, Karri (Ed.) Asteroids, Comets, Meteors - Book of Abstracts (2014, July 01)

TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope) is a 60-cm robotic telescope that has been installed in June 2010 at the ESO La Silla Observatory [1]. Operated from Liège (Belgium) it is ... [more ▼]

TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope) is a 60-cm robotic telescope that has been installed in June 2010 at the ESO La Silla Observatory [1]. Operated from Liège (Belgium) it is devoted to the detection and characterisation of exoplanets and to the study of comets and other small bodies in the Solar System. We describe here the hardware and the goals of the project and give an overview of the comet production rates monitoring after three years of operations. The telescope and observatory --- TRAPPIST's optical tube unit is a Ritchey-Chretien 0.6 meter telescope with a focal length of 4.8 meter. It is associated with a German equatorial mount that is, thanks to its direct drive system, extremely fast (up to 50 deg/s), accurate (tracking accuracy without autoguider better than 2'' in 10 min), and free of periodic error. The instrument is a Peltier cooled commercial camera equipped with a Fairchild 3041 back-illuminated 2k×2k chip. The pixel scale is 0.64''/pixel. Three read-out modes are available, the shortest read-out time being 2s. The total field of view of the camera is 22'×22'. It is associated to a custom-made dual filter wheel. One of the filter wheel contains broad band filters (Johnson B, V, R, Cousins Ic, Sloan z, and a special I+z filter), while the other contains the narrow-band NASA HB cometary filters (OH, NH, CN, CO+, C3, and C2 gaseous species; UC, BC, GC and RC solar continuum windows and a NaI D filter) [2]. The telescope is protected by a 5 meter diameter dome that was totally refurbished and automatized. The observatory is fully robotic and equipped with a weather station, an UPS and webcams. The la Silla site is excellent with more than 300 clear nights per year and the telescope has proven to be very reliable with a small amount of technical downtime. Comet monitoring --- For relatively bright comets (V < 12) we measure several times a week the gaseous production rates (using a Haser model) and the spatial distribution of several species among which OH, NH, CN, C2 and C3 as well as ions like CO+. The dust production rates (Afrho) and color of the dust are determined through four dust continuum bands (UC, BC, GC, RC). Such regular measurements are rare because of the lack of observing time on larger telescopes. Yet they are very valuable as they show how the gas production rate of each species evolves with respect to the distance to the Sun. Those observations allow to determine the composition of the comets and the chemical class to which they belong (rich or poor in carbon for instance [3]), possibly revealing the origin of those classes but also if there are some changes of the abundance ratios along the orbit (evolutionary effects). Indeed with half a dozen of comets observed each year --- and as long as possible along their orbit --- this program will provide a good statistical sample after a few years. We will present the results of this monitoring after three years of operations. Thanks to the way the telescope is operated, follow-up of split comets and of special outburst events is possible right after an alert is given and can bring important information on the nature of comets. In addition to providing the productions rates of the different species through a proper photometric calibration, image analysis can reveal coma features (jets, fans, tails), that can lead to the detection of active regions and measure the rotation period of the nucleus. The monitoring is also useful to assess the gas and dust activity of a given comet in order to prepare more detailed observations with larger telescopes. Such data can be obtained at any time under request. Finally a dozen of faint comets (V < 20) are monitored once a week through B, V, Rc, Ic filters and magnitudes and positions are sent to the MPC. [less ▲]

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See detailThe activity cycle of 67P/Churyumov-Gerasimenko
Snodgrass, C.; Barrera, L.; Boehnhardt, H. et al

in Muinonen, Karri (Ed.) Asteroids, Comets, Meteors - Book of Abstracts (2014, July 01)

We present ground-based observations of comet 67P/Churyumov-Gerasimenko, target of the Rosetta mission, and an assessment on its activity levels. Based on imaging in the R-band, we measure the brightness ... [more ▼]

We present ground-based observations of comet 67P/Churyumov-Gerasimenko, target of the Rosetta mission, and an assessment on its activity levels. Based on imaging in the R-band, we measure the brightness of the coma within various apertures and use this to assess the amount of dust in the coma. We find that the comet begins to show detectable activity at a pre-perihelion distance from the Sun of 4.3 au, and then shows a smooth increase in production to a peak around one month after perihelion passage. The behaviour of the comet is consistent from one orbit to another, based on archival images taken over three apparitions, and we therefore use the heliocentric lightcurve to make predictions for the 2014/5 period while Rosetta is operating at the comet. We find that the Afρ parameter, measured within an aperture of radius 10,000 km at the comet, is proportional to r^{-3.2}, pre-perihelion [1]. We also attempt to make predictions on the gas production rate by fitting a model to the observed brightness values. This is done by assuming various parameters about the nucleus and dust, many of which are reasonably well constrained for 67P, and solving an energy balance equation that gives the sublimation rate of various ices as a function of solar illumination [2]. The model then links the gas production rate to the total amount of dust in the coma, and its brightness. We find that only a small fraction of the surface area (1.4 %) needs to be active for water sublimation, with an extra peak (up to 4 %) for a month either side of perihelion, while an even smaller area is producing CO_2 (0.04-0.09 %) [1]. The predictions can now be tested against new observations, and we will present the latest results from our 2014 monitoring of 67P. We are performing regular R-band imaging on the comet using the VLT, and early indications in March 2014 indicate that the comet does appear to have returned to activity as expected. By the time of the ACM meeting we will have around 4 months of imaging to make a clear assessment of the trend between 4.4 and 3.8 au, which will allow a comparison with our model and therefore predictions to be made of how well 67P appears to be following its previous activity pattern. By July, we will also have obtained the first of a series of VLT/FORS visible wavelength spectra, to make a direct search for gas emission lines. These will represent some of the most distant spectroscopic observations of a Jupiter family comet coma. Preliminary results will be shown from these spectra, which will also constrain the expected evolution of activity as Rosetta approaches the comet. [less ▲]

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See detailThe X-ray Integral Field Unit (X-IFU) for Athena
Ravera, Laurent; Barret, Didier; den Herder, Jan Willem et al

in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series (2014, July 01)

Athena is designed to implement the Hot and Energetic Universe science theme selected by the European Space Agency for the second large mission of its Cosmic Vision program. The Athena science payload ... [more ▼]

Athena is designed to implement the Hot and Energetic Universe science theme selected by the European Space Agency for the second large mission of its Cosmic Vision program. The Athena science payload consists of a large aperture high angular resolution X-ray optics (2 m2 at 1 keV) and twelve meters away, two interchangeable focal plane instruments: the X-ray Integral Field Unit (X-IFU) and the Wide Field Imager. The X-IFU is a cryogenic X-ray spectrometer, based on a large array of Transition Edge Sensors (TES), offering 2:5 eV spectral resolution, with ~5" pixels, over a field of view of 50 in diameter. In this paper, we present the X-IFU detector and readout electronics principles, some elements of the current design for the focal plane assembly and the cooling chain. We describe the current performance estimates, in terms of spectral resolution, effective area, particle background rejection and count rate capability. Finally, we emphasize on the technology developments necessary to meet the demanding requirements of the X-IFU, both for the sensor, readout electronics and cooling chain. [less ▲]

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See detailDistant activity of comet C/2006 W3 (Christensen) as observed with Herschel
de Val-Borro, M.; Bockelée-Morvan, D.; Jehin, Emmanuel ULg et al

in Muinonen, Karri (Ed.) Asteroids, Comets, Meteors - Book of Abstracts (2014, July 01)

We aimed to measure the H_2O and dust production rates in C/2006 W3 (Christensen) with the Herschel Space Observatory at a heliocentric distance of ˜ 5 au and compare these data with previous post ... [more ▼]

We aimed to measure the H_2O and dust production rates in C/2006 W3 (Christensen) with the Herschel Space Observatory at a heliocentric distance of ˜ 5 au and compare these data with previous post-perihelion Herschel and ground-based observations at ˜ 3.3 au from the Sun (Bockelée-Morvan et al. 2010b). We have searched for emission in the H_2O and NH_3 ground-state rotational transitions at 557 GHz and 572 GHz, simultaneously, toward comet C/2006 W3 (Christensen) with the Heterodyne Instrument for the Far Infrared (HIFI) onboard Herschel on UT 1.5 September 2010. Photometric observations of the dust coma in the 70 μ m to 160 μ m channels were acquired with the Photodetector Array Camera and Spectrometer (PACS) instrument on UT 26.5 August 2010. A tentative 4-σ H_2O line emission feature was found in the spectra obtained with the HIFI wide-band and high-resolution spectrometers, from which we derive a water production rate of 2.0(5)×10^{27} molec. s^{-1}. A 3-σ upper limit for the ammonia production rate of < 1.5×10^{27} molec. s^{-1} is obtained taking into account the contribution from all hyperfine components (Biver et al. 2012). The dust thermal emission was detected in the 70-μ m to 160-μ m filters, with a more extended emission in the blue channel. We fit the radial dependence of the surface brightness with radially symmetric profiles for the blue and red bands. The dust production rates, obtained for a dust size distribution index that explains the fluxes at the photocenters of the PACS images, lie in the range 70-110 kg s^{-1}. Scaling the CO production rate measured post-perihelion at 3.20-3.32 au, these values correspond to a dust-to-gas production rate ratio in the range 0.3-0.4. The blueshift of the water line detected by HIFI suggests preferential emission from the subsolar point. However, it is also possible that water sublimation occurs in small ice-bearing grains that are emitted from an active region on the nucleus surface at a speed of ˜ 0.2 km s^{-1}. The dust production rates derived in August 2010 are roughly one order of magnitude lower than in September 2009, suggesting that the dust-to-gas production rate ratio remained approximately constant during the period when the activity became increasingly dominated by CO outgassing. These data will complement available Herschel observations of the distant activity of other comets such as 29P/Schwassmann-Wachmann 1 (Bockelée-Morvan et al. 2010a) and main-belt comets 176P/LINEAR and P/2012 T1 (PANSTARRS) (de Val-Borro et al. 2012, O'Rourke et al. 2013). [less ▲]

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See detailEarly Prediction of Transient Voltage Sags caused by Rotor Swings
Weckesser, Tilman; Johannsson, Hjortur; Van Cutsem, Thierry ULg

in Proc. IEEE PES general meeting (2014, July)

The paper investigates various methods to predict voltage sags at load buses caused by large generator rotor swings and following a transient disturbance. Three different prediction methods are proposed ... [more ▼]

The paper investigates various methods to predict voltage sags at load buses caused by large generator rotor swings and following a transient disturbance. Three different prediction methods are proposed, which all use real-time measurements from PMUs. One of the methods uses a slightly extended version of the E-SIME method. The other two methods use measurements and process them by recursive least square estimation. It is shown that the prediction method employing E-SIME allows the earliest detection of a critical voltage sag with satisfactory accuracy. [less ▲]

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See detailOrder reduction in time integration caused by velocity projection
Arnold, Martin; Cardona, Alberto; Bruls, Olivier ULg

in Proceedings of the 3rd Joint International Conference on Multibody System Dynamics and the 7th Asian Conference on Multibody Dynamics (2014, July)

Holonomic constraints restrict the configuration of a multibody system to a subset of the configuration space. They imply so called hidden constraints at the level of velocity coordinates that may ... [more ▼]

Holonomic constraints restrict the configuration of a multibody system to a subset of the configuration space. They imply so called hidden constraints at the level of velocity coordinates that may formally be obtained from time derivatives of the original holonomic constraints. A numerical solution that satisfies hidden constraints as well as the original constraint equations may be obtained considering both types of constraints simultaneously in each time step (stabilized index-2 formulation) or using projection techniques. Both approaches are well established in the time integration of differential-algebraic equations. Recently, we have introduced a generalized- alpha Lie group time integration method for the stabilized index-2 formulation that achieves second order convergence for all solution components. In the present paper, we show that a separate velocity projection would be less favourable since it may result in an order reduction and in large transient errors after each projection step. This undesired numerical behaviour is analysed by a one-step error recursion that considers the coupled error propagation in differential and algebraic solution components. This one-step error recursion has been used before to prove second order convergence for the application of generalized-alpha methods to constrained systems. As a technical detail, we discuss the extension of these results from symmetric, positive definite mass matrices to the rank deficient case. [less ▲]

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See detailSmart Grid Energy Flexible Buildings through the use of Heat Pumps in the Belgian context
Georges, Emeline ULg; Masy, Gabrielle; Verhelst, Clara et al

in 3rd International High Performance Buildings Conference at Purdue (2014, July)

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See detailFatigue index reproducibility in isokinetic testing
Paulus, Julien ULg; Croisier, Jean-Louis ULg; Bosquet, Laurent et al

in De Haan, Arnold; De Ruiter, Jo; Tsolakidis, Elias (Eds.) Book of abstracts (2014, July)

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See detailAdvanced Aeroservoelastic Modeling for Horizontal axis Wind Turbines
Prasad, Chandra Shekhar ULg; Chen, Qiong-zhong; Dimitriadis, Grigorios ULg et al

in Cunha, A.; Caetano, E.; Riberio, P. (Eds.) et al Proceedings of the 9th International Conference on Structural Dynamics, EURODYN 2014 (2014, July)

This paper describes the development of a complete methodology for the unsteady aeroelastic and aeroservoelastic modeling of horizontal axis wind turbines at the design stage. The methodology is based on ... [more ▼]

This paper describes the development of a complete methodology for the unsteady aeroelastic and aeroservoelastic modeling of horizontal axis wind turbines at the design stage. The methodology is based on the implementation of unsteady aerodynamic modeling, advanced control strategies and nonlinear finite element calculations in the S4WT wind turbine design package. The aerodynamic modeling is carried out by means of the unsteady Vortex Lattice Method, including a free wake model. The complete model also includes a description of a doubly fed induction generator and its control system for variable speed operation and enhanced power output. The S4WT software features a non-linear finite element solver with multi-body dynamics capability. The complete methodology is used to perform complete aeroservoelastic simulations of a 2MW wind turbine prototype model. The interaction between the three components of the approach is carefully analyzed and presented here. [less ▲]

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See detailMovements of endemic and exotic fish in a large river ecosystem (Rhône, France)
Capra, Hervé; Pella, Hervé; Ovidio, Michaël ULg

in Proceedings of the 10th International Conference on Ecohydraulics (2014, July)

The aim of this study is to characterise the mobility templates of two patrimonial species of rheophilic cyprinids (Barbus barbus and Squalius cephalus) and of a species of exotic fish, the catfish ... [more ▼]

The aim of this study is to characterise the mobility templates of two patrimonial species of rheophilic cyprinids (Barbus barbus and Squalius cephalus) and of a species of exotic fish, the catfish (Silurus glanis), in an area of the upper Rhône River characterised by significant disruptions of flow and thermal regimes (caused by hydroelectric and nuclear power plants). Results reveal contrasted mobility patterns, habitat uses and home-range sizes between endemic and exogenous fish species, but with a high interindividual variability. [less ▲]

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See detailExcavation damaged zone modelling including hydraulic permeability evolution in unsaturated argilaceous rock
Pardoen, Benoît ULg; Levasseur, Séverine ULg; Collin, Frédéric ULg

in Khalili, Nasser; Russell, Adrian R.; Khoshghalb, Arman (Eds.) Unsaturated Soils: Research & Applications (2014, July)

The drilling of galleries induces damage propagation in the surrounding medium and creates the Excavation Damaged Zone (EDZ) in which the material properties are modified. The prediction of the fracture ... [more ▼]

The drilling of galleries induces damage propagation in the surrounding medium and creates the Excavation Damaged Zone (EDZ) in which the material properties are modified. The prediction of the fracture structure and flow properties evolution within this zone are major issues especially in the context of underground nuclear waste storage. Since experimental results indicate that shear strain localisation appears prior to fractures, we model the EDZ with strain localisation in shear band mode using the coupled local second gradient model. The evolution of the intrinsic hydraulic permeability inside the fractures is taken into consideration as well as the influence of gallery ventilation on the rock desaturation. The numerical results provide information about the damaged zone extension, structure and behaviour with good correspondence to in situ measurements and observations. [less ▲]

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See detailTassili n’Ajjer (Sahara Oriental Algérien) – Résultats préliminaires sur le Silurien-Dévonien
Djouder, Hocine ULg; Boulvain, Frédéric ULg; Da Silva, Anne-Christine ULg et al

in Journée Thématique de l’Association des Sédimentologistes Français (ASF) « Diagenèse : avancées récentes et perspectives » (2014, July)

Les gisements atypiques non-conventionnels, à roches sédimentaires faiblement perméables, ainsi que les « sources rocks » constituent une source pétrolière majeure, attirant de plus en plus l’industrie ... [more ▼]

Les gisements atypiques non-conventionnels, à roches sédimentaires faiblement perméables, ainsi que les « sources rocks » constituent une source pétrolière majeure, attirant de plus en plus l’industrie pétrolière, d’où un regain d’intérêt potentiel au sein du Bassin de Berkine. En effet, rien que les argiles radioactives (‘hot’) shales du Silurien sont à l’origine de 80 à 90% des hydrocarbures de la plaque Nord-africaine, et les argiles radioactives du Frasnien (source secondaire) avec des valeurs de TOC allant jusqu’à 14% (Lüning et al., 2000). L'objectif de la thèse s’agira dans un premier temps de l’analyse des diagraphies de forages (Berkine ‘subsurface’) conditionnée aux données de terrain (Tassili n’Ajjer sur affleurements) et de sismique réflexion. Ceci afin de réaliser la modélisation 2D et 3-D des corps réservoirs et de la roche mère, à l’aide du logiciel Petrel©. Et au final, la cartographie des unités de la série Silurien-Dévonien dans le but de définir les « Plays » potentielles aux futures plans d’exploration. Au second volet, la mise au point d’une méthodologie rigoureuse, permettant l’étude minéralogique et l’évolution diagénétique des faciès, sous différents aspect ; la quantification de la porosité, la définition des relations entre porosité et minéralogie. Ensuite caractériser les argiles radioactives du Llandoverien-Frasnien respectivement Silurien, Dévonien et minéraux associés (Lüning et al., 2004). Plus précisément les processus et mécanismes qui contrôlent les transformations des minéraux argileux (minéralogies et cristallochimies) en composante latérale mais aussi en fonction de la profondeur. Dans ce contexte, des missions de terrains seront entreprises dans les massifs du Fadnoun (Tassili Central), Oued Taïni, Oued Khabkhab ainsi que dans l’Oued Amassine (Tassili Occidental) qui nous permettront de décrire en surface les formations du Siluro-Dévonien (profondément étudiées par : Asses, A., 1987 - Massa, D., 1988 - Bekkouche, D., 1992 – IFP, Sonatrach, Beicip., 1999) qui renferment les argiles radioactives (‘hot’) shales et les niveaux réservoirs, situées à quelques centaines de kilomètres au Nord (Bassin de Berkine), sous 2500 à 3000 m de sédiments. Une première mission de terrain est déjà réalisée, ayant reçu un support financier de la R&D (Séjour de Recherche à l’étranger), ainsi que des facilitées administratives et logistiques respectivement du Ministère de la Culture et de l’office national du parc culturel du Tassili n’Ajjer (patrimoine mondial de l’UNESCO depuis 1982). D’autres missions ultérieures seront à organiser en fonction du planning du déroulement de la thèse. La première mission géologique de terrain a duré un mois sur le Plateau de Fadnoun (Tassili n’Ajjer central). Ceci dans différentes coupes géologique-type des affleurements du Silurien-Dévonien : l’Oued Imihrou, l’Oued Farzal, Gara Tihouririne (sur la route Illizi-Fort Tarat) et Isoutar (Djouder et al., 2014). Durant cette mission terrain nous avons pu assurer la concordance entre les thématiques et objectifs de départ et les réalisés sur terrain, entre autre : 1) la meilleure compréhension de la géométrie des corps sédimentaires, au sein du Plateau de Fadnoun et donc par extension dans le bassin ; 2) la description et l’analyse des faciès, grâce aux affleurements peu connus dans les oueds. Ils permettront une analyse, notamment en termes d’environnements sédimentaires, des formations du Silurien-Dévonien ; 3) application première dans son genre de la susceptibilité magnétique comme nouvel proxy, pour les corrélations lithostratigraphiques des unités du Silurien-Dévonien aux Tassilis. 4) réalisation d’un échantillonnage serré à différents niveaux pour couvrir tout l’intervalle de la dépression intra-Tassilienne et des Grès du Tassili Externe, et puis l’expédition du matériel, nécessaire aux analyses de laboratoires notamment à Liège, et collaborateurs. La confection de lames-minces (en cours) permettra l’étude de la minéralogie et de la pétrographie, et donc une meilleure compréhension des faciès et microfaciès, c’est à dire de leurs propriétés intrinsèques (systèmes hétérogènes et complexes). Les lames palynologiques permettront des datations précises de chaque niveau. Enfin, différentes analyses sur roche (minéraux argileux dans un Laboratoire partenaire de l’Université de Poitiers en France, susceptibilité magnétique, cathodoluminescence, analyses géochimiques des majeurs et des traces à l’ULg) permettront d’affiner les paramètres du paléoenvironnement (Da Silva et al., 2013). [less ▲]

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See detailUpdate on investigation in IPF - Clinical presentation and epidemiology in domestic animals
Clercx, Cécile ULg

in Proceedings of the Fibrosis Across Species Consortium - Louisville - EU - 27th – 29th April 2014 (2014, July)

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See detailExperimental analysis of 2:1 modal interactions with noncommensurate linear frequencies in an aerospace structure
Noël, Jean-Philippe ULg; Renson, Ludovic ULg; Kerschen, Gaëtan ULg

in Proceedings of the 8th European Nonlinear Dynamics Conference (ENOC) (2014, July)

Nonlinear interactions between modes with noncommensurate linear frequencies are studied. It is experimentally evidenced that a strongly nonlinear, full-scale aerospace structure may exhibit such 2:1 ... [more ▼]

Nonlinear interactions between modes with noncommensurate linear frequencies are studied. It is experimentally evidenced that a strongly nonlinear, full-scale aerospace structure may exhibit such 2:1 interactions in typical testing conditions. The experimental observations are compared with numerical predictions. [less ▲]

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See detail3D analysis and determination of stride parameters for different type of foot strike in running
Bury, Thierry ULg

in Abstract book of the 19th Annual Congress of the ECSS Amsterdam (2014, July)

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See detailEnhancement of ray tracing method for radiative heat transfer with new isocell quasi-monte carlo technique and application to EUI space instrument
Jacques, Lionel ULg; Masset, Luc ULg; Kerschen, Gaëtan ULg

in Proceedings of the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, HEFAT2014 (2014, July)

Monte Carlo ray tracing method for thermal analysis. The rationale for this research is the speed-up of radiative heat transfer computation with the Finite Element Method, widely used in mechanical ... [more ▼]

Monte Carlo ray tracing method for thermal analysis. The rationale for this research is the speed-up of radiative heat transfer computation with the Finite Element Method, widely used in mechanical engineering especially for space structure design but not yet often for thermal analysis of these structures. Based on Nusselt’s analogy, the ray direction sampling is done by sampling the unit disc to derive the ray directions. Stratified sampling is applied to the unit disc that is divided into cells or strata into which random points are generated. The isocell method relies on cells that have the particularity of presenting almost the same area and shape. This enhances the uniformity of the generated quasi-random sequence of ray directions and leads to faster convergence. The isocell method is associated with different surface sampling to derive REFs. The method is benchmarked against ESARAD, the standard ray tracing engine of the thermal analysis software used in the European aerospace industry. Various geometries are used. In particular, one entrance baffle of the Extreme Ultraviolet Imager (EUI) instrument developed at the Centre Spatial de Liège in Belgium is presented. The EUI instrument of the Solar Orbiter European Space Agency mission and will be launched in a 0.28 perihelion orbit around the Sun in 2018. [less ▲]

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See detailOn the convergence of relaxation schemes to couple phasor-mode and electromagnetic transients simulations
Plumier, Frédéric ULg; Geuzaine, Christophe ULg; Van Cutsem, Thierry ULg

in Proceedings of the IEEE PES General Meeting (2014, July)

Hybrid simulations combining phasor-mode and electromagnetic transients models aim at taking advantage of computational speed of the former and accuracy of the latter. For simulation accuracy, a ... [more ▼]

Hybrid simulations combining phasor-mode and electromagnetic transients models aim at taking advantage of computational speed of the former and accuracy of the latter. For simulation accuracy, a relaxation process is used, which consists of iterating between both models. The convergence properties of this relaxation process are investigated. The speed of convergence is assessed when the variables exchanged at the interface between both models are respectively pure voltage/current sources, Norton/Thévenin equivalents, or a combination of them. Iteratively updated Norton/Thévenin equivalents are shown to drastically reduce the number of relaxation iterations. [less ▲]

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See detailComputation of damped nonlinear normal modes with internal resonances: a boundary value approach
Renson, Ludovic ULg; Touzé, Cyril; Kerschen, Gaëtan ULg

in Proceedings of the 8th European Nonlinear Dynamics Conference (ENOC 2014) (2014, July)

This paper considers the computation of nonlinear normal modes (NNMs) defined as two-dimensional manifolds in phase space. Because existing methods use explicit manifold parameterization, NNM computation ... [more ▼]

This paper considers the computation of nonlinear normal modes (NNMs) defined as two-dimensional manifolds in phase space. Because existing methods use explicit manifold parameterization, NNM computation in the presence of internal resonances requires multiple pairs of constraint coordinates. This paper investigates an alternative method for which the manifold is computed using successive boundary value problems. [less ▲]

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See detailSoil compaction resulting from different soil tillage systems
Destain, Marie-France ULg; Roisin, Christian; Mercatoris, Benoît ULg

in ASABE - CSBE/ASABE Joint Meeting Presentation (2014, July)

The effects of long-term use (8 years) of two different tillage systems were assessed on a Luvisol, under temperate climate (Belgium). The tillage treatments were (i) conventional tillage (CT) with ... [more ▼]

The effects of long-term use (8 years) of two different tillage systems were assessed on a Luvisol, under temperate climate (Belgium). The tillage treatments were (i) conventional tillage (CT) with moldboard ploughing to 27 cm depth and (ii) reduced tillage (RT) with a spring tine cultivator to 10 cm depth. The measurements included bulk density (BD) and precompression stress (Pc) chosen as indicators of mechanical strength, and the pore size distribution (PSD) measured by mercury intrusion porosimetry (MIP). The tillage systems, the depth and their interaction had a significant effect on BD, Pc and PSD. In CT, in the topsoil, the soil strength was low and the total porosity n was about 50 %. In the subsoil, n decreased to 43 %. The PSD of CT was uni-modal in topsoil and subsoil in the MIP measurement range. The mean value of the mode rmax diminished from the topsoil toward the subsoil (from 2.5 microns to 1.9 microns). In RT, in the topsoil, the soil strength was higher than CT. BD did not vary much according to the depth. The total porosity n of RT was comprised between 40-45 % in the soil profile. The PSD was uni-modal and rmax increased from topsoil (around 2 microns) to subsoil (> 3 microns). This suggested the agglomeration of fine particles under the long-term action of mechanical loads, climatic agents, biological organisms or clay minerals acting as cementing agents. These phenomena could be at the origin of the increase of Pc with the depth without significant modification of BD. Such high values of Pc could be responsible of negative effects on root-growth leading to a more superficial root lateral development. [less ▲]

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See detailModeling the hygrothermal response of a prefabricated straw bale panel and assessing its impact on indoor climate
Dubois, Samuel ULg; Evrard, Arnaud; Lebeau, Frédéric ULg

in 2014 ASABE and CSBE/SCGAB Annual International Meeting (2014, July)

Crop-based materials show many qualities in the quest for construction products with low environmental impact in the construction sector. Their ability to exchange moisture with indoor air offers new ... [more ▼]

Crop-based materials show many qualities in the quest for construction products with low environmental impact in the construction sector. Their ability to exchange moisture with indoor air offers new opportunities for improving interior user comfort and eventually buildings energy performance. Modeling their hygrothermal behavior has thus focused much attention, one of the main objectives being to assess more objectively the resulting performance at building scale. The first natural step in this modeling process is to understand the specific dynamics of heat and mass transfer within such materials. The Building Element Heat Air and Moisture (BEHAM) numerical models were designed to accurately predict internal conditions encountered in materials with partial balance equations. This envelope-based approach, however, requires the knowing of the interior and exterior climate conditions prior to the study. Therefore, it forbids any assessment of mutual exchange between the envelope to the indoor air and prevents any serious validation of the overall performance of materials. In response to this problem, the importance of developing whole building hygrothermal model has recently been raised. General scientific computational tools like MATLAB seem particularly adapted to perform this scaling-up, given their high flexibility and tools integration potentialities. In this communication we study a prefabricated straw bale panel subjected to two distinct and simple solicitations in a climatic chamber. A whole building hygrothermal model developed in MATLAB is then validated with the experimental datasets. The evolution of indoor conditions under the different tests is analyzed in details with an assessment of straw bales performance. [less ▲]

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See detailOptimization Of A Heat Pump For Satellite Cooling
Bell, Ian ULg; Lemort, Vincent

in 15 th International Refrigeration and Air Conditioning Conference at Purdue (2014, July)

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See detailAuf dem Weg zu einer neuen institutionellen Technologiefolgenabschätzung. TA in der Wallonie
Delvenne, Pierre ULg; Rosskamp, Benedikt ULg

in Decker, Michael; Bellucci, Sergio; Bröchler, Stephan (Eds.) et al Technilfolgenabschätzung im politischen System (2014, July)

Seit den offensiven Flämischen Technologie-Förderprogrammen in den achtziger Jahren, hat sich der technologische Graben zwischen dem Norden Belgiens und der von Deindustrialisierung stark betroffenen ... [more ▼]

Seit den offensiven Flämischen Technologie-Förderprogrammen in den achtziger Jahren, hat sich der technologische Graben zwischen dem Norden Belgiens und der von Deindustrialisierung stark betroffenen Wallonie weiter entwickelt. Hinzu kommt, dass Flandern im Jahre 2000 eine para-parlamentarische TA Institution eingeführt hat. Ein solches Unterfangen befand sich bis vor kurzem nicht auf der politischen Agenda der Wallonischen Entscheidungsträger. Zwischen 1994 und 2002 missglückte ein erstes TA Experiment, das sich sehr stark an das Baden-Württembergische Regional-TA Modell anlehnte. Zu diesem Zeitpunkt waren die Wallonischen Institutionen noch sehr jung und vor allem mit der Staatsreform befasst. Außerdem war das Interesse der traditionellen Sozialpartner (sprich Arbeitgeber- und Arbeitnehmerverbände) für TA nur bedingt vorhanden und der Bezug zur parlamentarischen Arbeit sehr begrenzt. Wir werden historisch nachverfolgen, wie es zu einer gemeinsamen Regierungserklärung des sozialistischen Ministers für Wirtschaft, Kleinunternehmen, Außenhandel und Neue Technologien sowie Hochschulwesen Jean-Claude Marcourt und des Grünen-Ministers für nachhaltige Entwicklung, öffentliche Ämter, Energie, Wohnungswesen und Forschung Jean-Marc Nollet kam, welche die Gründung eines Instituts für TA vorsieht. Diese ist teilweise zurückzuführen auf eine prospektive Aktionsforschung an der Universität Lüttich aus dem Jahr 2008 die ein weites Spektrum von Innovationsakteuren zu ihrer Haltung gegenüber institutionalisierter TA in der Wallonie befragt hat. Bei der Vorstellung dieser Studie, haben sich eine Reihe von Regionalabgeordneten für die Schaffung eines Instituts für TA ausgesprochen und wenig später eine parlamentarische Resolution verabschiedet. Wir werden auf die organisatorischen und programmatischen Aspekte, wie sie in den Regierungsplänen vorgesehen sind, eingehen. Die Originalität des Wallonischen Projekts ist u.a. der besondere Fokus auf wirtschaftliche Missionen. Mit dem ökonomischen Sektor als Adressaten soll u.a. die Wallonische Wirtschaft in strategischen Technologiebereichen unterstützt werden. Dabei wird viel Hoffnung in das Management von sozial-technologischen Kontroversen und in Wissenschaftskommunikation gesteckt. Neu ist auch der Ansatz, die Tradition der belgischen Sozialkonsultation auf gewisse Stakeholder-Gruppen auszuweiten und die Ambition partizipatorische Methoden zu nutzen, die im Wallonischen Kontext noch wenig verbreitet sind. Das aktuelle Projekt ist jedoch nicht frei von gegenwärtigen politischen Spannungen. Diese hängen sehr stark von parteipolitischen Ansichten sowie unterschiedlichen Positionen der zuständigen Ministerkabinette zur Staatsreform ab. Ferner gilt es auf die Eigenheiten eines solchen Instituts einzugehen und dessen formelle und informelle Adressaten sowie die Verbindung zu weiteren wissenschaftlichen, politischen und administrativen sowie zivilgesellschaftlichen Akteuren zu erläutern. Zuletzt werden wir auf die Besonderheiten der belgischen politischen Institutionen eingehen um besondere Risiken und Herausforderungen einer jungen TA Institution zu skizzieren. [less ▲]

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See detailAt the Crossroads of Greek and Roman Medicine: the Contribution of Latin Papyri. I. Medical Texts
Marganne, Marie-Hélène ULg

in Maire, Brigitte (Ed.) 'Greek' and 'Roman' in Latin Medical Texts. Studies in Cultural Change and Exchange in Ancient Medicine (2014, July)

Far fewer Latin medical papyri, whether paraliterary, documentary or magical, have survived compared to Greek medical papyri, but they nonetheless provide interesting information about medical practices ... [more ▼]

Far fewer Latin medical papyri, whether paraliterary, documentary or magical, have survived compared to Greek medical papyri, but they nonetheless provide interesting information about medical practices in the Graeco-Roman world, the relationship between Greek and Latin medical languages, and the choices made to use one rather than the other, a subject that has never been exhaustively studied. As part of the update undertaken by CEDOPAL since 2008 of the Corpus Papyrorum Latinarum, published fifty years ago by the late Robert Cavenaile, we have inventoried Latin papyri containing medical references, classifying them by type or nature of content, provenance, form, layout and writing. We finally analyse their content and what it reveals about the reception of Greek medicine by Latin or Latin-speeking writers. [less ▲]

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See detailRisk assessment of soil compaction in Walloon Region
D'Or, Dimitri; Destain, Marie-France ULg

in Proceedings of geoENV2014 (2014, July)

It is well established that soil compaction affects the growth and functioning of roots and disrupts the activity of microfauna and soil microorganisms, resulting in a loss of yields. Agriculture and ... [more ▼]

It is well established that soil compaction affects the growth and functioning of roots and disrupts the activity of microfauna and soil microorganisms, resulting in a loss of yields. Agriculture and forestry using increasingly heavy machines, the risk of soil compaction is increasing accordingly. Chosen as indicator of the susceptibility of soils to compaction, the precompression stress (Pc) is calculated using the pedotransfer functions (PTFs) proposed by Horn and Fleige (2003). These PTFs involve eight parameters linked to the hydraulic and mechanical behaviour of soils: organic matter content, bulk density, air capacity, available and non-plant available water capacity, saturated hydraulic conductivity, cohesion and angle of internal friction. The challenge consists in producing Pc maps at the regional scale for Wallonia. Those maps should also be accompanied by estimation uncertainty map. Finally, the results should be exploited to produce compaction risk maps according to various frequent scenarios. In this paper, a methodology is proposed, combining geostatistics and Monte Carlo simulations, to achieve these goals. [less ▲]

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See detailOrthanc - Logiciel libre pour l'imagerie médicale en milieu hospitalier
JODOGNE, Sébastien ULg; LENAERTS, Eric ULg; COUCKE, Philippe ULg et al

in Communications de la Conférence Francophone en Gestion et Ingénierie des Systèmes Hospitaliers (GISEH 2014) (2014, July)

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See detailVibration analysis by speckle interferometry with CO2 lasers and microbolometers arrays
Vandenrijt, Jean-François ULg; Thizy, Cédric ULg; Georges, Marc ULg

in Imaging and Applied Optics 2014, OSA Technical Digest (online) (2014, July)

Speckle interferometry in the time-average mode in long wave infrared is shown for observing the mode shapes of vibrating objects. The long wavelength allows observing larger vibration displacements than ... [more ▼]

Speckle interferometry in the time-average mode in long wave infrared is shown for observing the mode shapes of vibrating objects. The long wavelength allows observing larger vibration displacements than what is achieved with visible wavelengths. [less ▲]

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See detailA wavelet leaders-based climate classification of European surface air temperature signals
Deliège, Adrien ULg; Nicolay, Samuel ULg

in Ruiz Garcia, Gonzalo; Rojas Ruiz, Ignacio (Eds.) Proceedings of the International work-conference on Time Series: Volume 1, Granada 25-27 June 2014 (2014, June 25)

We explain the wavelet leaders method, a tool to study the pointwise regularity of signals, which is closely related to some functional spaces. We use the associated multifractal formalism to show that ... [more ▼]

We explain the wavelet leaders method, a tool to study the pointwise regularity of signals, which is closely related to some functional spaces. We use the associated multifractal formalism to show that surface air temperature signals are monofractal, i.e. these climate time series are regularly irregular. Then we use this result to establish a climate classification of weather stations in Europe which matches the Köppen-Geiger climate classification. This result could give rise to new criteria to determine the efficiency of current climatic models. [less ▲]

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See detailAntioxidant capacity and phenolic composition of red wines from various grape varieties : specificity of pinot noir.
degives, Julien; Kevers, Claire ULg; DEFRAIGNE, Jean ULg et al

in Giuseppe Viali (Ed.) 3rd international conference on cellular environmental stressors in biology and medicine : focus on redox reactions (2014, June 25)

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See detailCalculation of third order joint acceptance function for line-like structures
Blaise, Nicolas ULg; Canor, Thomas ULg; Denoël, Vincent ULg

in Proceedings of the XIII Conference of the Italian Association for Wind Engineering (2014, June 24)

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See detailSPATIODATA, un modèle de bâtiment non-constructif, collaboratif et multi-usage
Delfosse, Vincent ULg; Boulanger, Christelle ULg; Jeunejean, Aurélie ULg et al

in Actes du 6ème Séminaire de Conception Architecturale Numérique (2014, June 19)

There is an increasing number of mobile applications supporting specific activities related to the indoor building environment. SpatioData is a research project aiming at the development of a ... [more ▼]

There is an increasing number of mobile applications supporting specific activities related to the indoor building environment. SpatioData is a research project aiming at the development of a collaborative platform for the effective sharing of building-related data and supporting a wide range of different activities. This paper discusses the specific data model at the heart of the project. A comparison with the traditional BIM models is given in order to motivate the choices made in this project. [less ▲]

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See detailExperimental tests and numerical modelling on eight slender steel columns under increasing temperatures
Franssen, Jean-Marc ULg; Zhao, Bin; Gernay, Thomas ULg

in Li, G.Q.; Jiang, S.C.; Chen, Suwen (Eds.) et al Progress on Safety of Structures in Fire (2014, June 11)

In order to fill the lack of knowledge about slender elements behavior at elevated temperatures, a European research project called FIDESC4 has been funded by the RFCS. This project involves experimental ... [more ▼]

In order to fill the lack of knowledge about slender elements behavior at elevated temperatures, a European research project called FIDESC4 has been funded by the RFCS. This project involves experimental testing, parametric numerical analyses and development of simple design rules. The present paper reports the characteristics and the results of the FIDESC4 experimental test campaign performed at the University of Liege on slender steel columns at elevated temperatures. A total of eight columns have been tested, all of them with I shape section. Six columns were made of welded sections (some prismatic and some tapered members) and two columns were with hot rolled sections. The nominal length of the columns was 3 meters with the whole length being heated. The strength of the material (webs and flanges) was measured on sample before the tests. The order of magnitude of the initial geometrical imperfections was recorded. The columns were not restrained against longitudinal thermal elongation. The supports at the ends were cylindrical thus inducing a restrain against rotation in one plane while allowing rotation in the other plane. The allowed direction of rotation was chosen in each test to induce buckling around the strong or the weak axis. The load was applied at ambient temperature and maintained for a period of 15 minutes after which the temperature was increased under constant load. The load was applied concentrically on some tests and with an eccentricity in other tests. The load eccentricity was either applied at both ends, leading to constant bending moment distribution along the length, or at one end only, leading to a triangular bending moment distribution. Heating was applied by electrical resistances enclosed in ceramic pads. The columns and the ceramic pads were wrapped in ceramic wool insulating material. This technique was preferred to gas heating in a standard test furnace because it allows applying a slower and better controlled heating rate and thus obtaining a more uniform temperature distribution in the member. It is also easier to measured lateral displacements of the column. Preliminary blank tests were performed on unloaded specimen in order to determine the heating range to be used later on the loaded columns. The paper will also report on a modification of the heating technique that was applied and improved significantly the uniformity in the temperature distribution. Numerical simulations were performed before the tests using shell elements of the software SAFIR and assumed values of the material properties in order to predict the failure modes. It was essentially crucial to determine whether lateral supports at intermediate levels should be provided in order to ensure failure in the desired direction. Experience showed that the failure modes developed as predicted by the numerical simulations. Besides a thorough description of the experiments, the paper will also present the obtained results in terms of failure mode, ultimate temperature and evolution of longitudinal and transverse displacement. Some information will also be given about the level of detail that has to be used in the numerical model in order to get accurate results at a reasonable price. [less ▲]

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See detailLe sort des travailleurs d’une entreprise en réorganisation judiciaire
Kéfer, Fabienne ULg; Gailliet, Guillaume ULg

in Clesse, Jacques (Ed.) Questions choisies de droit social. Hommage à Michel Dumont (2014, June 06)

Le droit de l’entreprise en difficulté entretient avec le droit du travail des liens tendus. La préservation du potentiel économique de l’entreprise s’affronte aux dispositions visant à éviter la ... [more ▼]

Le droit de l’entreprise en difficulté entretient avec le droit du travail des liens tendus. La préservation du potentiel économique de l’entreprise s’affronte aux dispositions visant à éviter la dégradation de la situation des travailleurs. Le complexe normatif étudié reflète le point actuel du rapport de force entre le monde économique et les syndicats. Les salariés sont, en définitive, amenés à faire une grande partie du sacrifice nécessaire pour atteindre l’objectif économique recherché. Ce constat est perceptible dans l’hypothèse d’une réorganisation par accord collectif et dans celle du transfert sous autorité de justice, qui témoignent des rapports complexes entre les intérêts économiques et sociaux. La conciliation de ces intérêts divergents s’effectue sous la surveillance du juge. [less ▲]

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See detailOn-the-fly domain adaptation of binary classifiers
Pierard, Sébastien ULg; Marcos Alvarez, Alejandro ULg; Lejeune, Antoine ULg et al

in 23rd Belgian-Dutch Conference on Machine Learning (BENELEARN) (2014, June 06)

This work considers the on-the-fly domain adaptation of supervised binary classifiers, learned off-line, in order to adapt them to a target context. The probability density functions associated to ... [more ▼]

This work considers the on-the-fly domain adaptation of supervised binary classifiers, learned off-line, in order to adapt them to a target context. The probability density functions associated to negative and positive classes are supposed to be mixtures of the source distributions. Moreover, the mixture weights and the priors are only available at runtime. We present a theoretical solution to this problem, and demonstrate the effectiveness of the proposed approach on a real computer vision application. Our theoretical solution is applicable to any classifier approximating Bayes' classifier. [less ▲]

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See detailLa psychopathologie à la lumière des histoires de vie : Etude de la fonction narrative d’adolescents obèses et dépressifs.
Jadin, Aurore ULg; Gauthier, Jean-Marie ULg; Boulard, Aurore ULg

in Née, Emilie; Daube, Jean-Michel; Valette, Mathieu (Eds.) et al Proceedings-Actes des 12èmes journées internationales d'analyse statistique de données textuelles (2014, June 05)

Obesity in adolescence is a complex chronic illness with havy consequences in short, medium and long terms, both in terms of physical health and mental health, disturbing the body and identity of these ... [more ▼]

Obesity in adolescence is a complex chronic illness with havy consequences in short, medium and long terms, both in terms of physical health and mental health, disturbing the body and identity of these youngs (High Authority of Health, 2011; Nietsen and Bruwier, 2007). The literature mentions depression as a pathology associated with obesity. Some researchers consider obesity as a cause of depressive symptoms while others researchers see depression like a risk factor for excessive weight gain (Blaine, 2008). Depression in adolescence has been the subject of epidemiological studies for some years. In adolescents, the prevalence rates vary from 5 to 7 % for major depressive episode (MDE) with a prevalence of 2 girls for one boy (Alvin and Marcelli, 2005). The specific symptoms of depressed mood are present in 30-40 % of schooled adolescents (Boulard et al., 2012). During adolescence, the individual acquires the ability to link the various elements of one’s life and build a coherent life story. The adolescent will write one’s story in a personal context. According to Habermas et al. (2008), both the form and the content of life stories show how the individual integrates the lived experiences in a coherent whole. Based on the statistical analysis of textual data, we compared the life stories of 28 obese adolescents, depressed schooled adolescents, depressed hospitalized adolescents and control ones. The first results show specific structures and particular contents depending on these groups. The use of pronouns, temporal markers and the reported events differ by groups. Beyond clinical results, this research also highlights the interest of statistical analysis of textual data (ADT) to improve the understanding of adolescent’s psychopathology. [less ▲]

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See detailApproche lexicométrique des controverses climatiques
Scotto d'Apollonia, Lionel; Luxardo, Giancarlo; Piet, Grégory ULg

in Les actes des JADT 2014 (2014, June 05)

D’un point de vue historique, les controverses climatiques prennent racine à la fin du XIXe siècle et se sont déployées tout au long du XXe siècle. Elles prennent toutefois une tournure plus politique, en ... [more ▼]

D’un point de vue historique, les controverses climatiques prennent racine à la fin du XIXe siècle et se sont déployées tout au long du XXe siècle. Elles prennent toutefois une tournure plus politique, en ce début de XXIe siècle, en ce sens que le débat climatique « se priorise » dans les agendas politiques des Etats européens, de manière générale. Si les études sur les controverses climatiques tendent, certes, à se développer de plus en plus actuellement, l’approche linguistique demeure peu investie par rapport au potentiel analytique qu’elle pourrait apporter à la recherche sur le sujet. L’une des rares études lexicométriques concernant le climat est celle réalisée par Lamria Chetouani dont le corpus de textes s’étend de 1989 à 1990. Il faut aussi prendre en compte les travaux de Francis Chateauraynaud, qui a entrepris une démarche destinée au traitement des controverses s'appuyant sur un ensemble de techniques : la socio-informatique. Inscrit dans un cadre d’analyse socioépistémique des controverses socioscientifiques et en se basant sur un corpus de textes choisis autour de la période 2009 - 2010, notre article propose donc d'associer une analyse socio-informatique des controverses climatiques avec une utilisation d'outils lexicométriques. En nous concentrant sur le traitement discursif de quelques notions-clés, notamment l'incertitude et le risque, nous cherchons à croiser les résultats fournis par la lexicométrie (logiciel Lexico) avec ceux fournis par la socio-informatique (logiciel Prospero). En conclusion, nous ouvrons un espace de discussion sur les modes opératoires permettant d'articuler les deux approches. [less ▲]

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See detailExploration du récit de vie d’adolescents
Poudat, Céline; Boulard, Aurore ULg

in Née, Emilie; Daube, Jean-Michel; Valette, Mathieu (Eds.) et al Proceedings-actes des 12èmes journées d'analyse statistique de données textuelles (2014, June 05)

The present paper follows on from the research we presented in previous JADT (Boulard, Poudat, Gauthier 2012). We still focus on the development of narrative competence (Habermas et Bluck 2000) in ... [more ▼]

The present paper follows on from the research we presented in previous JADT (Boulard, Poudat, Gauthier 2012). We still focus on the development of narrative competence (Habermas et Bluck 2000) in children and adolescents. Although children develop narrative skills, life narratives only emerge in adolescence. On the basis of a corpus made of spontaneous oral speech, we had empirically demonstrated that pre-adolescents aged of 12 had developed stabilized narrative skills enabling them to produce life narratives. Here, we propose a first exploration of the overall structure of adolescent life stories, thanks to a corpus of 268 oral self narratives completed with a questionnaire. [less ▲]

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See detailSIMPLIFIED SEISMIC ANALYSIS OF LOCK GATES
Buldgen, Loïc ULg; Degée, Hervé ULg; Lesourne, Hervé et al

in PIANC 2014 Conference (2014, June 02)

The paper deals with the seismic design of lock gates. When such structures are submitted to an earthquake, the water contained in the chamber is responsible for an additional hydrodynamic pressure acting ... [more ▼]

The paper deals with the seismic design of lock gates. When such structures are submitted to an earthquake, the water contained in the chamber is responsible for an additional hydrodynamic pressure acting on the gate. This one is the sum of three different parts, respectively called the convective, rigid and flexible contributions. The two first ones have already been extensively studied in the literature, but the flexible part is more difficult to assess as it is largely influenced by the coupling occurring between the fluid and the gate. To overcome this difficulty, it is of course possible to use finite elements software, but doing so is not always convenient. This is why some research have been undertaken to provide a rapid way for approximating the flexible pressure on lock gates. This is achieved by applying the analytical approach that is shortly presented in this paper. As a matter of validation, the results obtained through this simplified procedure are compared to numerical solutions. The agreement between both of them is found to be satisfactory. [less ▲]

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See detailRay tracing enhancement for space thermal analysis: isocell method
Jacques, Lionel ULg; Masset, Luc ULg; Kerschen, Gaëtan ULg

in Sarler, Bozidar; Massaroti, Nicola; Nithiarasu, Perumal (Eds.) Third International Conference on Computational Methods for Thermal Problems (2014, June 02)

The finite element method (FEM) is widely used in mechanical engineering, especially for space structure design. However, FEM is not yet often used for thermal engineering of space structures where the ... [more ▼]

The finite element method (FEM) is widely used in mechanical engineering, especially for space structure design. However, FEM is not yet often used for thermal engineering of space structures where the lumped parameter method is still dominant. Radiative exchange factors (REFs) are usually computed through Monte Carlo ray-tracing. Due to the large number of elements composing a FE model, the computation of the REFs is prohibitively expensive. The developments of the new Isocell quasi-Monte Carlo ray tracing method are presented. The Isocell method enhances the uniformity of the generated quasi-random sequence of ray directions and leads to faster convergence. It is associated with different surface sampling to derive the REFs. The method is benchmarked against ESARAD, the standard ray-tracing engine for thermal analysis used in the European aerospace industry. Various geometries are used. In particular, one entrance baffle of the Extreme Ultraviolet Imager (EUI) instrument developed at the Centre Spatial de Liège in Belgium is used. The EUI instrument of the Solar Orbiter European Space Agency mission and will be launched in a Sun-centered 0.28 perihelion orbit in 2018. [less ▲]

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See detailDe la matière à l'espace: une voie d'intégration numérique et matérielle
Delvaux, Frederic ULg; Bianchi, Romuald ULg; Jancart, Sylvie ULg

in Kubicki, Sylvain; Halin, Gilles; Bignon, Jean-CLaude (Eds.) Scan 14 séminaire de conception architecturale numérique : Interaction(s) des maquettes numériques (2014, June 01)

From a collaboration of formal and architectural research between architect and artist, we present the summary of an experimental approach that illustrates the creation and construction of a functional ... [more ▼]

From a collaboration of formal and architectural research between architect and artist, we present the summary of an experimental approach that illustrates the creation and construction of a functional space, located at the borders of the sculpture and the architecture. We present a look at the method, according to a revised approach to digital modeling / re-design. This has been an exploratory approach through the study of three generic models of the form. We present the experimental method, the selection of relevant parameters in form finding coupled with the integration of material and physical data specific to the object. We also expose the benefits of this approach, its limitations and the possibilities it offers as a generic point of view. [less ▲]

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See detailAn Investigation into the Influence of External Walls Reflectivity on the Indoor Daylight Availability in Desert Climates
Hegazy, Mohamed Amer; Attia, Shady ULg

in Conference Proceedings: Building Simulation and Optimization 2014 (2014, June)

Hot arid climates are characterized by clear sunny sky most of the year time. Such climates affects the urban morphology, which requires sometimes dense urban fabric. Narrow streets have significant ... [more ▼]

Hot arid climates are characterized by clear sunny sky most of the year time. Such climates affects the urban morphology, which requires sometimes dense urban fabric. Narrow streets have significant effect on the amount of daylight permeating indoor residential zones, which may have a negative or positive effect on the overall visual performance. This paper studies the quantitative effect of using different Façade reflectivity ratios, under different street widths, on the indoor daylight autonomy. The researcher performed a parametric analysis using DIVA for Rhino simulation tool on a hypothetical residential building unit with various window ratios facing neighbouring buildings. Four main orientations were examined under different urban contexts and wall reflectivity. This paper aims to measure daylight autonomy and address possible strategies and solutions to achieve better daylighting that can be used by architects at early design stages of housing developments in the desert climates. [less ▲]

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See detailDelivering Bad New in Service Encounters: a Customer Perspective
Delcourt, Cécile ULg; Gremler, Dwayne; van Riel, Allard et al

in SERVSIG (2014, June)

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See detailOn the ultimate compressive strength of transversely cracked plates
Bayatfar, Abbas ULg; Pire, Timothée ULg; Rigo, Philippe ULg

in Proceedings of the ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering (2014, June)

This paper aims to numerically analyse the ultimate strength of transversely cracked steel plates under longitudinal compressive loading, considering the effect of initial distortion as well. The main ... [more ▼]

This paper aims to numerically analyse the ultimate strength of transversely cracked steel plates under longitudinal compressive loading, considering the effect of initial distortion as well. The main objective of this study is to investigate the ultimate compressive strength characteristics of an unstiffened steel plate due to transverse cracking damages located in the middle (i.e. centre cracks and edge cracks). To achieve that, a series of non-linear finite element (FE) analyses are carried out using ANSYS commercial finite element code. The obtained FE results are discussed to indicate the amount of crack influence, in terms of its length and location, on the ultimate compressive strength of a steel plate element with different thicknesses. [less ▲]

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See detailPrediction of macroscopic mechanical properties of a polycrystalline microbeam subjected to material uncertainties
Lucas, Vincent ULg; Wu, Ling ULg; Arnst, Maarten ULg et al

in Cunha, Álvaro; Caetano, Elsa; Ribeiro, Pedro (Eds.) et al Proceedings of the 9th International Conference on Structural Dynamics, EURODYN 2014 (2014, June)

The first resonance frequency is a key performance characteristic of MEMS vibrometers. In batch fabrication, this first resonance frequency can exhibit scatter owing to various sources of manufacturing ... [more ▼]

The first resonance frequency is a key performance characteristic of MEMS vibrometers. In batch fabrication, this first resonance frequency can exhibit scatter owing to various sources of manufacturing variability involved in the fabrication process. The aim of this work is to develop a stochastic multiscale model for predicting the first resonance frequency of MEMS microbeams constituted of polycrystals while accounting for the uncertainties in the microstructure due to the grain orientations. At the finest scale, we model the microstructure of polycrystaline materials using a random Voronoï tessellation, each grain being assigned a random orientation. Then, we apply a computational homogenization procedure on statistical volume elements to obtain a stochastic characterization of the elasticity tensor at the second scale of interest, the meso-scale. In the future, using a stochastic finite element method, we will propagate these meso-scale uncertainties to the first resonance frequency at the coarser scale. [less ▲]

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See detailUsing intensive multiyear fish-pass monitoring to analyse seasonal upstream movement patterns of patrimonial holobiotic potomadromous fish species in a medium size river
Benitez, Jean-Philippe ULg; Nzau Matondo, Billy ULg; Dierckx, Arnaud ULg et al

in Proceedings of the 10th International Conference on Ecohydraulics (2014, June)

Belgian rivers are fragmented by numerous obstacles which considerably limit the free access of fish to functional habitats. Fish-passes are major tools used to increase stream continuity and improve ... [more ▼]

Belgian rivers are fragmented by numerous obstacles which considerably limit the free access of fish to functional habitats. Fish-passes are major tools used to increase stream continuity and improve connectivity in the upstream direction. Using two modern multispecies fish-passes, this study aims to investigate multiyear abundance of holobiotic potamodromous fish and their seasonal movement patterns in relation with environmental factors. The fish passes were monitored continuously during 5 and 7 years and are located in two Belgian streams: the (19.3m³.s-1) and the Berwinne (1.9m³.s-1). Results revealed the presence of 20 different fish species, 14 species in the Berwinne and 19 species in the occurrence, salmonids and cyprinids species were predominant. A great interspecific and intraspecific variability in capture periodicity and in terms of stimulation by combination of factor environmental was observed. This study highlights the complexity and the omnipresence of holobiotic potamodromous fish movements at different life stages, in medium size river and brings new information on fish passes efficiency and use by these poorly known species. [less ▲]

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See detailThe grassland model intercomparison of the MACSUR (Modelling European Agriculture with Climate Change for Food Security) European knowledge hub
Ma, Shaoxiu; Acutis, Marco; Barcza, Zoltan et al

in Proceedings of the 7th International Congress on Environmental Modelling and Software (iEMSs) June 15-19, 2014, San Diego, California, USA (2014, June)

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See detailDistributed Model-free Control of Photovoltaic Units for Mitigating Overvoltages in Low-Voltage Networks
Aristidou, Petros ULg; Olivier, Frédéric ULg; Hervas, Maria Emilia et al

in Proc. of CIRED 2014 workshop (2014, June)

In this paper, a distributed model-free control scheme to mitigate overvoltage problems caused by high photovoltaic generation in low-voltage feeders is proposed. The distributed controllers are ... [more ▼]

In this paper, a distributed model-free control scheme to mitigate overvoltage problems caused by high photovoltaic generation in low-voltage feeders is proposed. The distributed controllers are implemented on the photovoltaic inverters and modulate the active and reactive power injected into the network. In particular, they direct photovoltaic units first to consume reactive power and, if necessary, curtail active power generation to reduce high voltages in the feeder. [less ▲]

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See detailSimple connectome inference from partial correlation statistics in calcium imaging
Sutera, Antonio ULg; Joly, Arnaud ULg; François-Lavet, Vincent ULg et al

in Proceedings of Connectomics 2014 (ECML 2014) (2014, June)

In this work, we propose a simple yet effective solution to the problem of connectome inference in calcium imaging data. The proposed algorithm consists of two steps. First, processing the raw signals to ... [more ▼]

In this work, we propose a simple yet effective solution to the problem of connectome inference in calcium imaging data. The proposed algorithm consists of two steps. First, processing the raw signals to detect neural peak activities. Second, inferring the degree of association between neurons from partial correlation statistics. This paper summarises the methodology that led us to win the Connectomics Challenge, proposes a simplified version of our method, and finally compares our results with respect to other inference methods. [less ▲]

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See detailMODEL PREDICTIVE CONTROL OF CONGESTION AND VOLTAGE PROBLEMS IN ACTIVE DISTRIBUTION NETWORKS
Soleimani Bidgoli, Hamid ULg; Glavic, Mevludin ULg; Van Cutsem, Thierry ULg

in Proc. of CIRED Workshop 2014 (2014, June)

This paper presents a centralized control scheme, inspired of Model Predictive Control (MPC), to manage thermal overloads and correct abnormal voltages in real-time. The control scheme is able to smoothly ... [more ▼]

This paper presents a centralized control scheme, inspired of Model Predictive Control (MPC), to manage thermal overloads and correct abnormal voltages in real-time. The control scheme is able to smoothly bring the system within the desired limits, taking into account its near-future evolution. The control method effectiveness is illustrated on a 20-kV, 32-bus network hosting four distributed generation units. [less ▲]

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See detailLe B.I.M et la maquette virtuelle comme moyen pédagogique permettant le rapprochement entre les cours d'informatique et l'enseignement du projet d'architecture
Boutemadja, Abdelkader ULg; Driesmans, Carine ULg; Jancart, Sylvie ULg

in Kubicki, Sylvain; Halin, Gilles; Bignon, Jean-Claude (Eds.) Scan 14 sémainaire de conception architecturale numérique : Interaction(s) des maquettes numériques (2014, June)

In the context of this paper, we pose the question of the conditions of possible link between computer courses and design projet. The integration of schools of architecture at universities is an ... [more ▼]

In the context of this paper, we pose the question of the conditions of possible link between computer courses and design projet. The integration of schools of architecture at universities is an opportunity to focus in the experiments made in this direction and to propose to implement the terms of this rapprochement. For us, it is important that this approach lies in the Bachelor years in a common core for all students. [less ▲]

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See detailGeometric parameters influence on Piano Key Weir hydraulic performances
Erpicum, Sébastien ULg; Archambeau, Pierre ULg; Pirotton, Michel ULg et al

in Chanson, Hubert; Toombes, Luke (Eds.) Hydraulic Structures and Society – Engineering Challenges (2014, June)

The Piano Key Weir is a recent evolution of the traditional labyrinth weir. Thanks to a reduced foot print, this nonlinear weir can be placed on the top of gravity dams. The Piano Key Weir geometry ... [more ▼]

The Piano Key Weir is a recent evolution of the traditional labyrinth weir. Thanks to a reduced foot print, this nonlinear weir can be placed on the top of gravity dams. The Piano Key Weir geometry involves a large number of geometric parameters. Several experimental studies have been carried out to investigate the main geometric parameters influencing the weir hydraulic efficiency and to define their optimal value. In this paper, the experimental data gathered at the University of Liege are re-examined to show how the weir height, the keys widths and the overhangs positions influence, for a given crest length magnification ratio, the weir discharge capacity. The theoretical rating curve of a standard linear weir is considered for comparison. The analysis highlights that the keys widths and overhangs lengths ratios influence significantly the Piano Key Weir efficiency, but less than the weir height. Considering the above mentioned results, a cost efficient design proposed in the literature is also proved to be close to the hydraulic optimum. [less ▲]

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See detailDouble Sweep Preconditioners for propagation problems solved by Optimized Schwarz Methods
Vion, Alexandre ULg; Geuzaine, Christophe ULg

in Proceedings of the 6th International Conference on Advanced COmputational Methods in ENgineering, ACOMEN 2014 (2014, June)

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See detailOn the Quality of BGP Route Collectors for iBGP Policy Inference
Cittadini, Luca; Vissicchio, Stefano; Donnet, Benoît ULg

in IFIP Networking (2014, June)

A significant portion of what is known about Internet routing stems out from public BGP datasets. For this reason, numerous research efforts were devoted to (i) assessing the (in)completeness of the ... [more ▼]

A significant portion of what is known about Internet routing stems out from public BGP datasets. For this reason, numerous research efforts were devoted to (i) assessing the (in)completeness of the datasets, (ii) identifying biases in the dataset, and (iii) augmenting data quality by optimally placing new collectors. However, those studies focused on techniques to extract information about the AS-level Internet topology. In this paper, we show that considering different metrics influences the conclusions about biases and collector placement. Namely, we compare AS-level topology discovery with \iac inference. We find that the same datasets exhibit significantly diverse biases for these two metrics. For example, the sensitivity to the number and position of collectors is noticeably different. Moreover, for both metrics, the marginal utility of adding a new collector is strongly localized with respect to the proximity of the collector. Our results suggest that the ``optimal'' position for new collectors can only be defined with respect to a specific metric, hence posing a fundamental trade-off for maximizing the utility of extensions to the BGP data collection infrastructure. [less ▲]

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See detailCHARACTERIZATION OF PROTEINURIA IN DOGUE DE BORDEAUX DOGS USING ELECTROPHORESIS AND URINARY BIOMARKERS
Lavoué, Rachel; Smets, P.; Trumel, Cathy et al

in Proceedings of the 2014 ACVIM Forum (2014, June)

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See detailOn the Performance of the LISP Beta Network
Coras, Florin; Saucez, Damien; Iannone, Luigi et al

in IFIP Networking (2014, June)

The future Internet has been a hot topic during the past decade and many approaches towards this future Internet, ranging from incremental evolution to complete clean slate ones, have been proposed. One ... [more ▼]

The future Internet has been a hot topic during the past decade and many approaches towards this future Internet, ranging from incremental evolution to complete clean slate ones, have been proposed. One of the proposition, LISP, advocates for the separation of the identifier and the locator roles of IP addresses to reduce BGP churn and BGP table size. Up to now, however, most studies concerning LISP have been theoretical and, in fact, little is known about the actual LISP deployment performance. In this paper, we fill this gap through measurement campaigns carried out on the LISP Beta Network. More precisely, we evaluate the performance of the two key components of the infrastructure: the control plane (i.e., the mapping system) and the interworking mechanism (i.e., communication between LISP and non-LISP sites). Our measurements highlight that performance offered by the LISP interworking infrastructure is strongly dependent on BGP routing policies. If we exclude misconfigured nodes, the mapping system typically provides reliable performance and relatively low median mapping resolution delays. Although the bias is not very important, control plane performance favors USA sites as a result of its larger LISP user base but also because European infrastructure appears to be less reliable. [less ▲]

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See detailBayes Adaptive Reinforcement Learning versus Off-line Prior-based Policy Search: an Empirical Comparison
Castronovo, Michaël ULg; Ernst, Damien ULg; Fonteneau, Raphaël ULg

in Proceedings of the 23rd annual machine learning conference of Belgium and the Netherlands (BENELEARN 2014) (2014, June)

This paper addresses the problem of decision making in unknown finite Markov decision processes (MDPs). The uncertainty about the MDPs is modeled using a prior distribution over a set of candidate MDPs ... [more ▼]

This paper addresses the problem of decision making in unknown finite Markov decision processes (MDPs). The uncertainty about the MDPs is modeled using a prior distribution over a set of candidate MDPs. The performance criterion is the expected sum of discounted rewards collected over an infinite length trajectory. Time constraints are defined as follows: (i) an off-line phase with a given time budget can be used to exploit the prior distribution and (ii) at every time step of the on-line phase, decisions have to be computed within a given time budget. In this setting, we compare two decision-making strategies: OPPS, a recently proposed meta-learning scheme which mainly exploits the off-line phase to perform policy search and BAMCP, a state-of-the-art model-based Bayesian reinforcement learning algorithm, which mainly exploits the on-line time budget. We empirically compare these approaches in a real Bayesian setting by computing their performances over a large set of problems. To the best of our knowledge, it is the first time that this is done in the reinforcement learning literature. Several settings are considered by varying the prior distribution and the distribution from which test problems are drawn. The main finding of these experiments is that there may be a significant benefit of having an off-line prior-based optimization phase in the case of informative and accurate priors, especially when on-line time constraints are tight. [less ▲]

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See detailThe Call for project proposals « Let’s live my village »: between free interpretations and compulsory readings regarding innovation and convivial village ambiance in Wallonia.
Schmitz, Serge ULg

in Les campagnes: espaces d'innovation dans un monde urbain (2014, June)

The paper scrutinizes 186 rural development projects selected on the short list of the first and second “Lets’ live my village!” calls. It examines trends concerning rural community life and the identity ... [more ▼]

The paper scrutinizes 186 rural development projects selected on the short list of the first and second “Lets’ live my village!” calls. It examines trends concerning rural community life and the identity of the leaders/brokers. It pays attention to the way that associations define rurality. Question 14 of the application form « Does your association act in rural areas? Explain” is the main source of information for content analysis and contingency tables [less ▲]

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See detailÉtude des changements de circulation au-dessus de l'océan Austral en été
Belleflamme, Alexandre ULg; Fettweis, Xavier ULg; Erpicum, Michel ULg

in Camberlin, Pierre; Richard, Yves (Eds.) Actes du XXVIIème colloque de l'Association de Climatologie - Climat : système & interactions (2014, June)

Over the five last decades, the reanalyses (ERA and NCEP/NCAR) show a strengthening of the pressure gradient between the southern hemisphere subtropical anticyclone belt and the southern circumpolar lows ... [more ▼]

Over the five last decades, the reanalyses (ERA and NCEP/NCAR) show a strengthening of the pressure gradient between the southern hemisphere subtropical anticyclone belt and the southern circumpolar lows during summer. With the help of an automatic circulation type classification, we show that the strengthening of the pressure gradient is generalised to all circulation types and, paradoxically, it does not cause circulation changes. It is probably implied by the strengthening of the temperature gradient between the tropics and the South Pole, without consequences on the general circulation. Our classification also allows a successful comparison between the two reanalyses in a region where the observation data are rare. [less ▲]

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See detailDecoding memory processing from electro-corticography in human posteromedial cortex
Schrouff, Jessica ULg; Foster, Brett L.; Rangarajan, Vinitha et al

in International Workshop on Pattern Recognition in Neuroimaging (2014, June)

Recently machine learning models have been applied to neuroimaging data, which allow predictions about a variable of interest based on the pattern of activation or anatomy over a set of voxels. These ... [more ▼]

Recently machine learning models have been applied to neuroimaging data, which allow predictions about a variable of interest based on the pattern of activation or anatomy over a set of voxels. These pattern recognition based methods present clear benefits over classical (univariate) techniques, by providing predictions for unseen data, as well as the weights of each feature in the model. Machine learning methods have been applied to a range of data, from MRI to EEG. However, these multivariate techniques have scarcely been applied to electrocorticography (ECoG) data to investigate cognitive neuroscience questions. In this work, we used previously published ECoG data from 8 subjects to show that machine learning techniques can complement univariate techniques and be more sensitive to certain effects. [less ▲]

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