References of "Denoël, Vincent"
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See detailValidated Extraction of Gait Events from 3D Accelerometer Recordings
Boutaayamou, Mohamed ULg; Schwartz, Cédric ULg; Stamatakis, Julien et al

in IEEE International Conference on 3D Imaging (IC3D) (2012, December)

This work is part of a project that deals with the three-dimensional (3D) analysis of normal and pathological gaits based on a newly developed system for clinical applications, using low-cost wireless ... [more ▼]

This work is part of a project that deals with the three-dimensional (3D) analysis of normal and pathological gaits based on a newly developed system for clinical applications, using low-cost wireless accelerometers and a signal processing algorithm. This system automatically extracts relevant gait events such as the heel strikes (HS) and the toe-offs (TO), which characterize the stance and the swing phases of walking. The performances of the low-cost accelerometer hardware and related algorithm have been compared to those obtained by a kinematic 3D analysis system and a force plate, used as gold standard methods. The HS and TO times obtained from the gait data of 7 healthy volunteers (147 trials) have been found to be (mean ± standard deviation) 0.42±7.92 ms and 3.11±10.08 ms later than those determined by the force plate, respectively. The experimental results demonstrate that the new hardware and associated algorithm constitute an effective low-cost gait analysis system, which could thus be used for the assessment of mobility in routine clinical practice. [less ▲]

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See detailPrincipal Static Wind Loads on a large roof structure
Blaise, Nicolas ULg; Hamra, Lotfi ULg; Denoël, Vincent ULg

in Proceedings of the 12th ANIV conference of wind engineering In Vento (2012, October 07)

Usually, structural wind design is realized using static wind loads. Such loadings are expected, as a main property, to recover by static analyses, the envelope values that would be obtained by a formal ... [more ▼]

Usually, structural wind design is realized using static wind loads. Such loadings are expected, as a main property, to recover by static analyses, the envelope values that would be obtained by a formal buffeting analysis. For simple structures, equivalent static wind loads might be used but they are established in order to reproduce envelope values of specific structural responses and are thus not suitable to reconstruct efficiently the entire envelope. Recently, more general methods were derived to propose global static loadings that reconstruct the entire envelope but several drawbacks remained as their robust applicability for any structure and accuracy. This paper addresses a new type of static loadings, the principal static wind loads, derived in a strict mathematical way, the singular value decomposition, to make it optimum for the envelope reconstruction problem. The method is illustrated with a large roof and the reconstruction accuracy is analysed by studying the rate of envelope reconstruction, envelope previously obtained by a rigourous stochastic analysis. The way principal loadings are derived makes them suitable for combinations in order to increase the rate of the envelope reconstruction. As a major outcome, the method provides a finite number of design load cases that matches a desired level of accuracy in the envelope reconstruction. [less ▲]

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See detailIntroduction aux statistiques et probabilités
Denoël, Vincent ULg

Learning material (2012)

Le document annexé contient les slides du cours donné en 2012-2013 aux étudiants du 3eme Bac Ingénieur Architectes de l'Université de Liège. Le cours est donné en 30 heures.

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See detailNonlinear Dynamics Of A Drill Bit Under Percussive Activation
Depouhon, Alexandre ULg; Denoël, Vincent ULg; Detournay, Emmanuel

in Proceedings of ICTAM 2012, Beijing (2012, August)

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See detailLimit cycling behavior of a hybrid system: Application to percussive drilling
Depouhon, Alexandre ULg; Detournay, Emmanuel; Denoël, Vincent ULg

in Proceedings of the 2nd International Colloquium on Non-Linear Dynamics and Control of Deep Drilling Systems, Eindhoven, May 2012 (2012, May)

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See detailStructural Dynamics
Denoël, Vincent ULg

Learning material (2012)

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See detailExtensions of the Background/biResonant decomposition
Denoël, Vincent ULg

Poster (2012)

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See detailThe concept of numerical admittance
Denoël, Vincent ULg; Maquoi, René ULg

in Archive of Applied Mechanics (2012)

The reconstruction of a discretized random distributed loading, as the wind pressure from some measurement taps, is usually performed by simple or advanced interpolation between the nodes of the mesh ... [more ▼]

The reconstruction of a discretized random distributed loading, as the wind pressure from some measurement taps, is usually performed by simple or advanced interpolation between the nodes of the mesh. This results in an overestimation of the coherence of the loading, especially in the high frequency range where the loading typically shows less coherence. An expensive way to circumvent this issue is to make the mesh denser. This is however not always possible, in particular in experimental testing where there is usually a limited number of available measurement spots. The concept of numerical admittance is introduced in order to rectify this inaccurate estimation of the resulting loading in the high-frequency range. It is actually introduced as a legitimate way of reducing the loading in accordance with the looseness of the discretisation mesh. Another major advantage of the concept is the opportunity to determine adequately the mesh size independently from the correlation length scale. [less ▲]

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See detail3D Analysis of Normal and Pathological Gait Based on Low-Cost Wireless Accelerometers
Boutaayamou, Mohamed ULg; Schwartz, Cédric ULg; Bruls, Olivier ULg et al

in URSI Benelux Forum 2012 “Antennas: multiple designs, multiple applications” (2012)

We describe the principle and use of a new low-cost, wireless, 3-axis accelerometer-based device that records acceleration signals and automatically analyses them to characterize normal and pathological ... [more ▼]

We describe the principle and use of a new low-cost, wireless, 3-axis accelerometer-based device that records acceleration signals and automatically analyses them to characterize normal and pathological gait. [less ▲]

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See detailEfficient uncoupled stochastic analysis with non-proportional damping
Canor, Thomas ULg; Blaise, Nicolas ULg; Denoël, Vincent ULg

in Journal of Sound & Vibration (2012), 331(2012), 52835291

The use of normal modes of vibration in the analysis of structures with nonproportional damping reduces the size of the resulting set of governing equations, but does not decouple them. A common practice ... [more ▼]

The use of normal modes of vibration in the analysis of structures with nonproportional damping reduces the size of the resulting set of governing equations, but does not decouple them. A common practice consists in decoupling the equations by disregarding the o -diagonal elements in the modal damping matrix. Recently, an approximation based on an asymptotic expansion of the modal transfer matrix has been proposed in a deterministic framework to partially account for o -diagonal terms, but still with a set of uncoupled equations. This paper aims at extending this method in a stochastic context. First the mathematical background is introduced and the method is illustrated with a simple example. Then its relevance is demonstrated within the context of the structural analysis of a large and realistic structure. [less ▲]

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See detailApplication of deterministic and stochastic analysis to calculate a stadium with pressure measurements in wind tunnel
Blaise, Nicolas ULg; Denoël, Vincent ULg; De Ville De Goyet, Vincent ULg et al

in Proceedings of the 8th International Conference on Structural Dynamics EURODYN 2011 (2011, July)

This paper aims at comparing different analysis methods in the design of a roof subjected to buffeting wind forces. The specificity of this study is that pressures acting on the stadium roof are measured ... [more ▼]

This paper aims at comparing different analysis methods in the design of a roof subjected to buffeting wind forces. The specificity of this study is that pressures acting on the stadium roof are measured in a wind tunnel. The key idea is to fit a probabilistic model onto the measured data and to perform the stochastic analysis as a usual buffeting analysis. [less ▲]

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See detailReproducibility and repeatability of upper limb landmarks palpation for junior operators
Schwartz, Cédric ULg; Fedrigo, Tatiana ULg; Bruls, Olivier ULg et al

Poster (2011, July)

In human motion analysis, bone motions are usually expressed relatively to anatomical reference frames. The anatomical reference frames are constructed thanks to the localization of bony landmarks during ... [more ▼]

In human motion analysis, bone motions are usually expressed relatively to anatomical reference frames. The anatomical reference frames are constructed thanks to the localization of bony landmarks during a static phase prior to the acquisitions. These landmarks are identified by means of palpation. Accurate comparison between subjects and studies implies good reproducibility and repeatability of the palpation process. However, all investigators don’t have a long experience in palpation. In this paper, the reproducibility and repeatability of palpation for junior investigators were measured. Results show worse reproducibility and repeatability than what is usually expected. These errors have particularly an influence on the definition of the reference frames of the arm. This study therefore emphasizes on the need of a specific training of operators working in a motion lab. [less ▲]

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See detailImproving 3D measurements accuracy with camera information redundancy
Schwartz, Cédric ULg; Fringuellini, Anthony ULg; Bruls, Olivier ULg et al

Conference (2011, July)

The accuracy of the Codamotion system for 3D measurement depends mainly on the signal level of the sensors and the resolution of the system at the marker localization. When using several units to cover a ... [more ▼]

The accuracy of the Codamotion system for 3D measurement depends mainly on the signal level of the sensors and the resolution of the system at the marker localization. When using several units to cover a large field of view, the estimated position of the different units might differ. We propose a method taking both resolution and signal level in to account, instead of only the signal level as in the built-in weighting process. This new method offers improved accuracy. [less ▲]

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See detailEvaluation of the use of VEGF111 for the treatment of tendon lesions.
Janssen, Lauriane ULg; Kaux, Jean-François ULg; Drion, Pierre ULg et al

Poster (2011, May 20)

Alterations of tendons are common pathologies resulting from repetitive or abnormal mechanical sollicitations. Very frequently lesions become chronic and may even lead to rupture. As there is no current ... [more ▼]

Alterations of tendons are common pathologies resulting from repetitive or abnormal mechanical sollicitations. Very frequently lesions become chronic and may even lead to rupture. As there is no current efficient treatment for curing this type of diseases, new therapeutic approaches are being tested and developed. Injection of platelet-rich plasma (PRP) seems to be a promising treatment by local release of growth factors. Among these factors, VEGF-A is known to induce positive effects on vascular functions and angiogenesis, and could be implicated in the healing process of tendons. Several isoforms of VEGF-A have been described in literature, including VEGF165 and 121. VEGF111 is encoded by exons 1-4 and 8a. The lack of exon 5 enables VEGF111 to resist to proteolytic degradation and the absence of exons 6 and 7 reduces its affinity for several macromolecules present on the cell surface and in the extracellular matrix. In vivo, it has been shown to be highly proangiogenic and diffusible. A 5mm defect was surgically performed in the Achilles tendon of 60 rats. Two hours after closure of the fascia and the skin, an injection within the wound was performed with PBS alone (n=30) or with PBS containing 100 ng of VEGF111 (n=30). 10 rats of each group were sacrificed at days 5, 15 and 30. The operated tendon was then carefully removed and collected for either immunohistochemical analyses or mechanical testing. At each time point, the section and the overall appearance of the repairing tendons were similar for PBS and VEGF111-injected tendon. As compared to controls, injection of VEGF111 seemed to promote a faster angiogenesis, although the number of samples was at this stage too low for performing reliable statistical analysis. Mechanical resistance to rupture of the repairing tendons was also measured. No difference between the two groups was observed after 5 or 15 days. By contrast, increased tensile strength was clearly evidenced in the VEGF-treated group after 30 days. These preliminary data seem to indicate a positive effect of a single VEGF111 injection for restoring the mechanical properties of tendons after their section. Additional experiments are planned for confirmation purposes and for further characterizing the model. It includes a “dose- response” analysis, the use of VEGF165 as an additional control and a study evaluating the effect of several injections. [less ▲]

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See detailSensitivity of Structural Response to Wind Turbulence Characteristics
Denoël, Vincent ULg

in Marcuso, Russell J. (Ed.) Turbulence: Theory, Types and Simulation - Series: Physics Research and Technology (2011)

Civil engineering structures that are built in the atmospheric boundary layer have to be designed according to the gusty winds they are likely to withstand during their lifetime. Traditionally statistical ... [more ▼]

Civil engineering structures that are built in the atmospheric boundary layer have to be designed according to the gusty winds they are likely to withstand during their lifetime. Traditionally statistical characteristics of the wind turbulence -as standard deviation of and correlation between turbulence components, frequency content, etc. - are provided to structural engineers by meteorologists. The first dialogue between these two communities dates back to 1960's when they agreed on a list of necessary statistical characteristics of turbulence that need to be observed and measured to feed the structural models available at that time. In the framework of advanced wind loading models developed recently, it turns out that this basic list of statistical characteristics of turbulence is no longer sufficient. In this chapter, we point out some quantities that would need to be measured and others that are already measured but require a more precise estimation. This need is justified by analyzing the sensitivity, to these quantities, of the structural response to an advanced Wind loading model. After having introduced the need for advanced modeling of the wind loading, and eventually thus of the wind turbulence, a nonlinear non-Gaussian quasi-steady loading model is presented. Then the model is rigorously analyzed with cumbersome mathematics and statistics, with the permanent background aim at estimation of the influence of the turbulence properties. Final results are however presented in a concise way in order to pave the way for the future dialogue between engineers and meteorologists, and so build up the advanced design procedures that will presumably be used during the coming decades. [less ▲]

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See detailOptimal processing of wind tunnel measurements in view of stochastic structural design of large flexible structures
Blaise, Nicolas ULg; Denoël, Vincent ULg

in Lerner, J. C.; Boldes, U. (Eds.) Wind Tunnels and Experimental Fluid Dynamics Research (2011)

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See detailTransient Fokker-Planck Equation solved with SPH
Canor, Thomas ULg; Denoël, Vincent ULg

in Proceedings of the 5th International Conference on Advanced Computational Methods in Engineering (2011)

In many engineering matters, systems are submitted to random excitations. Probabilistic theories aim at describing the properties of a system by means of statistical properties such as probability density ... [more ▼]

In many engineering matters, systems are submitted to random excitations. Probabilistic theories aim at describing the properties of a system by means of statistical properties such as probability density function (pdf). For a deterministic system randomly excited, the evolution of its pdf is commonly described with Fokker-Planck-Kolmogorov equation (FPK). The FPK equation is a conservation equation of a hypothetical fluid, which represents physically the transport of probability. To solve this equation, Smoothed Particle Hydrodynamics (SPH) are used: the system is modelled with a conservation equation for the system and a transport equation for each particle. Numerical implementation shows the superiority of this method over many other mesh-based methods: (i) the conservation of total probability in the state space is explicitly written, (ii) no specific boundary conditions must be imposed if an adaptive smoothing length is chosen and if particles are initially regularly spread out, (iii) the positivity of the pdf is ensured. Furthermore, thanks to the moving particles, this method is adapted for a large kind of initial conditions (quasi-deterministic or even discontinuous). The FPK equation can be solved without any a priori knowledge of the stationary distribution; just a precise representation of the initial distribution is required. [less ▲]

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See detailEulerian Formulation of a Drillstring Constrained inside a Curved Borehole
Denoël, Vincent ULg; Detournay, Emmanuel

Conference (2011)

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