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See detailRegime change in Mexico and the transformation of state-diaspora relations
Lafleur, Jean-Michel ULg

in Collyer, Michael (Ed.) Policies and Ideologies of Emigrant Engagement (2013)

Over the course of last two decades, Mexico’s policies towards its population abroad has moved from a situation characterized by a general lack of interest to being one of the most active state in this ... [more ▼]

Over the course of last two decades, Mexico’s policies towards its population abroad has moved from a situation characterized by a general lack of interest to being one of the most active state in this field. The recent development of dual national and external voting policies as well as the creation of a dedicated government agency and of a consultative body all epitomize the radical change through which Mexico has gone. In this chapter, I argue that the transformation of Mexico’s attitude towards its emigrants is strongly connected to the evolution of its political regime characterized by a transition towards democracy, a strong desire to take part actively in the global economy and the increasing interest of regional actors in migration issues. Focusing on the issue of external voting, the chapter concludes by discussing the evolution of the power relations between the emigrant community and the Mexican state. [less ▲]

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See detailEvaluating Portfolio Performance: Reconciling Asset Selection and Market Timing
Cavé, Arnaud; Hübner, Georges ULg; Lejeune, Thomas ULg

in Baker, H. Kent; Filbeck, Georges (Eds.) Portfolio Theory and Management (2013)

This chapter examines the performance measurement of mutual funds when both security selection and market timing management skills are considered. In an option replication approach, linear and quadratic ... [more ▼]

This chapter examines the performance measurement of mutual funds when both security selection and market timing management skills are considered. In an option replication approach, linear and quadratic coefficients of the Treynor and Mazuy regression are combined to assess performance in presence of market timing. This new correction has the potential to overcome the “artificial timing” bias and delivers particularly encouraging results on a sample of 1,413 U.S. mutual funds selected for an empirical analysis. Unlike alternative approaches proposed in the literature, most of positive market timers seem to be rewarded for the convexity they add to their portfolio, while negative market timers are penalized, and a correlation between abnormal performance and the convexity parameter is found. [less ▲]

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See detailFactors of knickpoint migration on the moderately uplifted Ardennes Plateau, Western Europe
Beckers, Arnaud ULg; Bovy, Benoît ULg; Demoulin, Alain ULg

Poster (2012, April 27)

In the last two decades, much research has been devoted to the development and refinement of numerical models of river incision. In settings of prevailing bedrock channel erosion, numerous studies used ... [more ▼]

In the last two decades, much research has been devoted to the development and refinement of numerical models of river incision. In settings of prevailing bedrock channel erosion, numerous studies used field data, notably knickpoint data, to calibrate the widely acknowledged stream power model of incision and to discuss the specific impact of various variables (e.g., sediment load, channel width) not appearing explicitly in the model’s simplest form. However, most of these studies were conducted in areas of very active tectonics and high relief, thus displaying an exacerbated geomorphic response to the tectonic signal. Here, we analyze the traces left in the drainage network 0.7 My after the NE Ardennes region (western Europe) underwent a moderate 100-150 m uplift. We identify a set of knickpoints that have travelled far upstream in the Ourthe catchment. Because time becomes a more sensitive variable than distance near the headwaters, we fit the stream power model to the data by minimizing time residuals (i.e., the differences between 0.7 My and the modelled times for the knickpoints to reach their actual location) rather than distance residuals. Our best fit of the stream power model parameters yields m/n = 0.75 and K = 4.63 10-8 m-0.5y-1. We suggest that the discrepancy with the m/n value of 0.5 obtained from field and long profile data of the currently graded downstream part of the catchment’s streams points to a narrowing of the bedrock channel at the passage of a knickpoint. Then, the time residuals of the model fit are regressed against quantitative expressions of bedrock resistance to erosion and junction crossing, showing that both variables significantly affect knickpoint migration. In particular, most of the small tributaries with highly delayed knickpoints display all features characteristic of hanging valleys. However, not all such small streams have developed hanging valleys, and further research is needed to unravel how other controls, e.g., amount and size of the tributary bed load, are determining for the creation of such valleys. [less ▲]

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See detailInitial Investigation of Chordwise Flexible Flat Aerofoil
Vio, Gareth A.; Worotynska, Jagoda; Berci, Marco et al

in Proceedings of the 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference (2012, April 25)

The size of small Unmanned Air Vehicles (UAVs) makes them susceptible to gusts, hence an evaluation of their aeroelastic performance is a necessary requirement. With advances in materials, new aircraft ... [more ▼]

The size of small Unmanned Air Vehicles (UAVs) makes them susceptible to gusts, hence an evaluation of their aeroelastic performance is a necessary requirement. With advances in materials, new aircraft are ever lighter and more flexible, both in the span-wise and chord-wise direction. An experiment is set up to evaluate the aeroelastic performance of a 2D chord-wise aerofoil structure under gust loading, where the wing of a small Unmanned Air Vehicle (UAV) is considered by coupling a Finite Element (FE) structural model with a Doublet-Lattice Method (DLM) aerodynamic model; a new semi-analytical modelling approach is also described. The flexible aerofoil structure is then optimised by means of a genetic algorithm (GA) framework for the minimum weight, subject to aeroelastic constraints of flutter, divergence and structural displacement. [less ▲]

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See detailExperiments on a pitch-plunge wing undergoing limit cycle oscillation
Norizham, Abdul Razak ULg; Rothkegel Ide, José Ignacio ULg; Dimitriadis, Grigorios ULg

in Proceedings of the 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference (2012, April 25)

The aeroelastic behaviour of a wing oscillating in the heave and pitch degrees of freedom is examined by means of wind tunnel experiment. The phenomena of interest are classical flutter and limit cycle ... [more ▼]

The aeroelastic behaviour of a wing oscillating in the heave and pitch degrees of freedom is examined by means of wind tunnel experiment. The phenomena of interest are classical flutter and limit cycle oscillation. Classical flutter is normally associated with the exponential growth of the response amplitude. Linear flutter theory only predicts the critical flutter speed. Any excitation or disturbance beyond the critical speed is assumed to cause exponential growth in the response amplitude. In contrast, any limited amplitude oscillations occurring post-fultter suggest the existence of nonlinear properties in the system. Such properties can originate from the aerodynamic forces in the form of flow separation and reattachment. On the structural side, damping and stiffness can also contribute nonlinear properties. Furthermore, these nonlinearities can manifest themselves even at pre-flutter conditions, depending on the values of some governing parameter. The focus of the present work is the transformation of classical flutter into stall flutter as the equilibrium angle of attack of heaving and pitching wing is increased. The interaction of stall-related nonlinearity with structural nonlinearities is also of interest. The measured aeroelastic responses are analyzed and the bifurcation behavior of the dynamic system is characterized. Structural responses as well as flow field visualization through Particle Image Velocimetry show the origin of nonlinearity does not solely come from the manifestation of separation and the shedding of vortices, but from the structural nonlinearity which limits the response amplitude. [less ▲]

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See detailComputational Considerations for the Prediction of Stall Flutter
Watrin, Damien ULg; Dimitriadis, Grigorios ULg; Perry, Tristan et al

in Proceedings of the 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference (2012, April 25)

A solver has been developed within the OpenFoam framework to compute large amplitude motion of two-dimensional rigid configurations. The results obtained with this code were successfully validated on ... [more ▼]

A solver has been developed within the OpenFoam framework to compute large amplitude motion of two-dimensional rigid configurations. The results obtained with this code were successfully validated on rigid airfoils at static and dynamic conditions, as well as correlated with experimental data and numerical solutions from similar unsteady solvers. The results demonstrated that while current computational methods are able to predict the self-sustained oscillations characterizing a pitch-dominated stall flutter, including energy transfer, improvements are needed. The influence of grid, temporal integration, turbulence modeling, and flow equations is examined for the stall flutter starting solution of dynamic stall. [less ▲]

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See detailA Cross-Validation Approach to Approximate Basis Function Selection of the Stall Flutter Response of a Rectangular Wing in a Wind Tunnel
Kukreja, Sunil L.; Vio, Gareth A.; Andrianne, Thomas ULg et al

in Proceedings of the 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference (2012, April 25)

The stall flutter response of a rectangular wing in a low speed wind tunnel is modelled using a nonlinear difference equation description. Static and dynamic tests are used to select a suitable model ... [more ▼]

The stall flutter response of a rectangular wing in a low speed wind tunnel is modelled using a nonlinear difference equation description. Static and dynamic tests are used to select a suitable model structure and basis function. Bifurcation criteria such as the Hopf condition and vibration amplitude variation with airspeed were used to ensure the model was representative of experimentally measured stall flutter phenomena. Dynamic test data were used to estimate model parameters and estimate an approximate basis function. [less ▲]

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See detailQuelques mesures de prévention de l’IRC et de traitement
Krzesinski, Jean-Marie ULg

Conference (2012, April 24)

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See detailDiscrete Vortex Simulations of the torsional flutter oscillations of a 4:1 rectangular cylinder
Andrianne, Thomas ULg; Dimitriadis, Grigorios ULg

in Proceedings of the 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference (2012, April 24)

This work presents aeroelastic simulations of a 2D bluff-body around its pitching degree of freedom. The numerical tool consists in an aerodynamic solver based on the Discrete Vortex Method (DVM), coupled ... [more ▼]

This work presents aeroelastic simulations of a 2D bluff-body around its pitching degree of freedom. The numerical tool consists in an aerodynamic solver based on the Discrete Vortex Method (DVM), coupled with a linear structural model. The shape of the bluff-body is a sharp edged rectangular cylinder with a side ratio equal to 4. The numerical results are compared to the experimental measurements recently obtained by the authors.8 The validation is carried out in three steps: first the frequency content of the flow-field in the wake of the static body is investigated. Then the simulated unsteady flow-field around the imposed pitching motion of the body is compared to experimental flow visualizations. This comparison is performed using Proper Orthogonal Decomposition (POD). Finally, the simulation of the global aeroelastic behaviour, based on the coupling of the DVM code to the structural model of the pitching degree of freedom is carried out and the results are compared to measured aeroelastic responses.. Very good agreements are found between numerical and experimental results, demonstrating the capabilities of the numerical tool to simulate complex unsteady aerodynamics around an oscillating bluff-body. [less ▲]

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See detailComputational Identification of Non-Linear Damping in an Aeroelastic System
Vio, Gareth A.; Dimitriadis, Grigorios ULg

in Proceedings of the 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference (2012, April 23)

An energy-based method is proposed to identify damping parameters from time histories of responses to sets of single-frequency harmonic excitation. The method is intended to be practically applicable to ... [more ▼]

An energy-based method is proposed to identify damping parameters from time histories of responses to sets of single-frequency harmonic excitation. The method is intended to be practically applicable to real structures and is able to identify the value of viscous damping, Coulomb friction and eventually other forms of non-linear damping models in aeroelastic systems. The inputs required are simply the accelerometer signals and the forces applied. It will be shown that if the system is undergoing Limit Cycle Oscillations, no external force is required for the identification process. [less ▲]

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See detailVariability of shelf sea pH and surface water CO2 in response to North Atlantic Oscillation forcing
Salt, L.; Thomas, H.; Prowe, A.E.F. et al

Conference (2012, April 22)

Detailed reference viewed: 7 (0 ULg)
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See detailEstimating pCO2 from remote sensing in the Belgian Coastal Zone
Borges, Alberto ULg; Ruddick, Kevin; Harlay, Jérôme ULg

Poster (2012, April 22)

Detailed reference viewed: 18 (2 ULg)
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See detailHistorical changes in carbon dioxide (CO2) and dimethyl sulphide (DMS) emissions in the eutrophied Southern North Sea
Gypens, N.; Borges, Alberto ULg; Lancelot, C.

Conference (2012, April 22)

Detailed reference viewed: 8 (0 ULg)
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See detailSeasonal dynamics of organic carbon in the Tana River Basin, Kenya
Tamooh, F.; Meysman, F.; Marwick, T.R. et al

Conference (2012, April 22)

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See detailRisk factor of fetal chromosomal aberrations in the south of Vietnam
To, Hong ULg

in European Federation of Societies for Ultrasound in Medicine and Biology (2012, April 22)

Objectives: The aim of this study is to find the risk factors of fetal chromosomal aberrations in order to classify a high risk pregnancy in our prenatal care unit. Material and methods: A prospective ... [more ▼]

Objectives: The aim of this study is to find the risk factors of fetal chromosomal aberrations in order to classify a high risk pregnancy in our prenatal care unit. Material and methods: A prospective study was carried out during one year in our clinic. 523 cases of amniocentesis was followed up and evaluated the relation with abnormal result (fetal aneuploidies) and the risk factors such as advanced maternal age (≥ 35 years old), parity, habitation, positive triple test (≥ 1/250), fetal malformation history and abnormal signs in the first and second trimester scanning. Results: The incidence of fetal aneuploidy was 3.4% (18/523 [95%CI: 2.1-5.4%]) and the trisomy 21 showed the most common in these chromosomal aberrations (67%). The younger women (< 35 years old), nulliparous, positive triple test and abnormal ultrasonographic findings (included increased nuchal translucency [≥ 2.4mm], absent nasal bone in the first trimester scanning and/or echogenic nodule in ventricular) was identified as the risk factors of fetal aneuploidies (OR was 2.3 [95%CI: 0.8-6.7], 4.0 [95%CI: 1.4-13.2], 3.3 [95%CI: 0.3-33.5] and 9.4 [95%CI: 1.1-79.2], respectively). The abnormal ultrasonographic findings found a relation significantly with abnormal chromosomes (p=0.04). Conclusion: Abnormal ultrasonographic findings in the first and second trimester were the important markers for predicting fetal aneuploidy, especially trisomy 21. [less ▲]

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See detailFeasibility of scanning fetal anatomy in the first trimester of gestation
To, Hong ULg

in European Federation of Societies for Ultrasound in Medicine and Biology (2012, April 22)

Objectives: This study aims to evaluate the feasibility of performing an anatomy scanned for fetal abnormalities at the time of nuchal translucency (NT) measurement in Vietnamese population Material and ... [more ▼]

Objectives: This study aims to evaluate the feasibility of performing an anatomy scanned for fetal abnormalities at the time of nuchal translucency (NT) measurement in Vietnamese population Material and methods: In a prospective study, 2500 singleton pregnancies measured fetal NT and scanned structural anatomy in the first trimester; then checked fetal morphology systematically at 18-24 weeks and followed up to their delivery. According to ultrasonographic abnormalities and amniocentesis, we evaluated the detection rate of ultrasound for aneuploidy in the first and second trimester of gestation. Results: The sensitivity and specificity of ultrasound for aneuploidy was 17.2% and 99.7%, respectively. All 13 cases of fetal ultrasonographic anomalies related significantly with an increased NT (≥ 2.4mm) (p < 0.001). 30.8% of these abnormalities that included cystic hygroma, omphalocele and holoprosencephaly were detected at 11-13.6 weeks’ gestation. In the second trimester scanning, 69.2% of major structural anomalies found and the detection rate of central nervous system malformation, abnormal heart, abdominal wall defect, face anomaly and skeletal deformities were 85.7%, 100%, 66.7%, 50% and 75%, alternatively. Conclusion: Scanning of fetal anatomy at the time of NT measuring is useful to detect fetal abnormalities, especially aneuploidy in Vietnamese pregnancies. [less ▲]

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See detailAnémies et insuffisance rénale : quoi de neuf?
Krzesinski, Jean-Marie ULg

Conference (2012, April 17)

Detailed reference viewed: 11 (0 ULg)
See detailDroits de succession et de mutation par décès
Bourgeois, Marc ULg; Douny, Raphaël ULg; Gustin, Manuel ULg et al

in Chroniques notariales (2012)

Detailed reference viewed: 41 (9 ULg)