References of "Denoël, Vincent"
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See detailReliability of unipodal and bipodal counter movement jump landings in a recreational male population
Schwartz, Cédric ULg; Forthomme, Bénédicte ULg; Paulus, Julien ULg et al

in European Journal of Sport Science (in press)

Movement patterns during landing have been suggested to be related to injury risk. The purpose of this study was to determine the inter-session reliability of kinematic variables and ground reaction ... [more ▼]

Movement patterns during landing have been suggested to be related to injury risk. The purpose of this study was to determine the inter-session reliability of kinematic variables and ground reaction forces during landing in a population of male recreational athletes after a counter movement jump. Both unipodal and bipodal landings were evaluated. Furthermore, the possibility to improve landing reliability with a verbal instruction was also studied. Twenty- four male volunteers with no history of lower-extremity trauma were randomly assigned to two groups (with and without verbal landing instruction). An optoelectronic 3D system and force plates were used to measure the lower-limb joint angles and the ground reaction forces during landing. Intraclass correlation values show moderate to excellent inter-session reliability for the bipodal task (ICC average: 0.80, range: 0.46 to 0.97) and poor to excellent reliability for the unipodal task (ICC average: >0.75, range: 0.20 to 0.95). However, large standard errors of measurement values at the ankle joint at impact (27.6 ± 11.5°) and for the vertical ground reaction forces (394 ± 1091 N) show that some variables may not be usable in practice. The verbal instruction had a negative effect on the reliability of unipodal landing but improved the reliability of bipodal landing. These findings show that the reliability of a landing task is influenced by its motor complexity as well as the instruction given to the subject. [less ▲]

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See detailAverage first-passage time of a quasi-Hamiltonian Mathieu oscillator with parametric and forcing excitations
Vanvinckenroye, Hélène ULg; Denoël, Vincent ULg

in Journal of Sound and Vibration (in press)

A linear oscillator simultaneously subjected to stochastic forcing and parametric excitation is considered. The time required for this system to evolve from a low initial energy level until a higher ... [more ▼]

A linear oscillator simultaneously subjected to stochastic forcing and parametric excitation is considered. The time required for this system to evolve from a low initial energy level until a higher energy state for the first time is a random variable. Its expectation satisfies the Pontryagin equation of the problem, which is solved with the asymptotic expansion method developed by Khasminskii. This allowed deriving closed-form expressions for the expected first passage time. A comprehensive parameter analysis of these solutions is performed. Beside identifying the important dimensionless groups governing the problem, it also highlights three important regimes which are called incubation, multiplicative and additive because of their specific features. Those three regimes are discussed with the parameters of the problem. [less ▲]

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See detailA Novel Accelerometer-Based Method for Stride Length Estimation
Boutaayamou, Mohamed ULg; Schwartz, Cédric ULg; Denoël, Vincent ULg et al

Poster (2017, July 14)

We demonstrate the feasibility of accurately and precisely estimating the left/right average stride length from measured heel/toe accelerations in the gait of healthy, old adults. Our approach relies on ... [more ▼]

We demonstrate the feasibility of accurately and precisely estimating the left/right average stride length from measured heel/toe accelerations in the gait of healthy, old adults. Our approach relies on (1) a novel method that uses only accelerometer data without the need of additional data from, e.g., gyroscopes and/or magnetometers, and on (2) the validation of the results using reference 3D optoelectronic system data. [less ▲]

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See detailExperimental characterisation of tape spring nonlinear compliant mechanisms
Dewalque, Florence ULg; Schwartz, Cédric ULg; Denoël, Vincent ULg et al

Conference (2017, June 29)

Tape springs are compliant mechanisms used as alternative to kinematic joints, for example, in deployable space structures. To reach a detailed understanding of their highly nonlinear behaviour, involving ... [more ▼]

Tape springs are compliant mechanisms used as alternative to kinematic joints, for example, in deployable space structures. To reach a detailed understanding of their highly nonlinear behaviour, involving buckling, the formation of folds, nonlinear vibrations and hysteresis, an experimental set-up is designed. Dynamic and quasi-static tests are performed, as well as small amplitude vibration tests and large amplitude deployments in order to collect data in a broad variety of cases. The acquisition equipment consists of a 3D motion analysis system which triangulates the position of active markers and a force plate. The reproducibility of the acquisitions is assessed and the parameters affecting the measurements are identified. In the end, a finite element model is developed and correlated with the experimental results. [less ▲]

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See detailRelevance of early stretching in overhead athletes
Schwartz, Cédric ULg; Tubez, François ULg; Croisier, Jean-Louis ULg et al

Conference (2017, June 16)

Overhead athletes often develop, over time, a tightness of the posterior structures of the shoulder, which may be associated with injuries. Ten symptomatic (with pain) and ten asymptomatic players with a ... [more ▼]

Overhead athletes often develop, over time, a tightness of the posterior structures of the shoulder, which may be associated with injuries. Ten symptomatic (with pain) and ten asymptomatic players with a tight shoulder were compared and the effect of a self-applied stretching program was evaluated. Before and after the stretching program, pain and stiffness of the shoulder were evaluated. Our results demonstrate that risk factors for shoulder pain such as glenohumeral internal rotation deficit and total range of motion deficit may only be limited in symptomatic athletes. The mobility of the shoulder was significantly improved after the stretching program for both groups. Pain was reduced when present. Because of the limited differences between the symptomatic and asymptomatic athletes, clinicians may find it advantageous to initiate early prevention or rehabilitation programs. [less ▲]

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See detailInfluence of the laboratory context and the size of the markers set on the tennis serve evaluation
Tubez, François ULg; Forthomme, Bénédicte ULg; Croisier, Jean-Louis ULg et al

Conference (2017, June 15)

The purpose of this study was to identify the influence on the tennis serve evaluation of 1/ the test environment and 2/ the number of the markers placed of the player. Two different studies were ... [more ▼]

The purpose of this study was to identify the influence on the tennis serve evaluation of 1/ the test environment and 2/ the number of the markers placed of the player. Two different studies were performed. The first compared a 4 vs. 28 marker set in a laboratory the same day. The second compared a 4 markers test in a laboratory with a 4 markers test on an official tennis court one week apart. We observed similar results between the different tests of both studies. [less ▲]

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See detailEccentric training for tendon healing after lesion: a rat model
Kaux, Jean-François ULg; Libertiaux, Vincent ULg; Leprince, Pierre ULg et al

in American Journal of Sports Medicine (2017), 45(6), 1440-1446

BACKGROUND:The tendon is a dynamic entity that remodels permanently. Platelet-rich plasma (PRP) injection has been shown to have a beneficial effect on tendon healing after lesion in rats. Furthermore ... [more ▼]

BACKGROUND:The tendon is a dynamic entity that remodels permanently. Platelet-rich plasma (PRP) injection has been shown to have a beneficial effect on tendon healing after lesion in rats. Furthermore, eccentric exercise seems to improve the mechanical quality of the tendon. HYPOTHESIS:A combination of PRP injection and eccentric training might be more effective than either treatment alone. STUDY DESIGN:Controlled laboratory study. METHODS:Adult male rats were anesthetized, an incision was performed in the middle of their left patellar tendon and an injection of physiological fluid (PF) or homologous PRP was randomly made at the lesion level. The rats were then divided into 2 groups: the eccentric group, undergoing eccentric training 3 times a week, and the untrained group, without any training. Thus, 4 groups were compared. After 5 weeks, the tendons were removed and their ultimate tensile strength and energy were measured. Tendons were frozen for proteomic analyses when all biomechanical tests were completed. Statistical analysis was performed with linear mixed effect models. RESULTS:No significant difference was found between the treatments using PF injection or PRP injection alone. However, the value of the ultimate tensile force at rupture was increased by 4.5 N (108% of control, P = .006) when eccentric training was performed. An intragroup analysis revealed that eccentric training significantly improved the ultimate force values for the PRP group. Proteomic analysis revealed that eccentric training led to an increase in abundance of several cytoskeletal proteins in the PF group, while a decrease in abundance of enzymes of the glycolytic pathway occurred in the PRP treated groups, indicating that this treatment might redirect the exercise-driven metabolic plasticity of the tendon. CONCLUSION: Eccentric training altered the metabolic plasticity of tendon and led to an improvement of injured tendon resistance regardless of the treatment injected (PF or PRP). CLINICAL RELEVANCE:This study demonstrates the necessity of eccentric rehabilitation and training in cases of tendon lesion regardless of the treatment carried out. [less ▲]

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See detailFactors to be considered to perform a kinematic evaluation of the tennis serve
Tubez, François ULg; Forthomme, Bénédicte ULg; Croisier, Jean-Louis ULg et al

in Journal of Medecine and Science in Tennis (2017), 22

With the 2D video cameras and later the appearance of 3D measurement methods, the tennis serve has been increasingly studied. In order to improve the biomechanical evaluation of the tennis serve. Our goal ... [more ▼]

With the 2D video cameras and later the appearance of 3D measurement methods, the tennis serve has been increasingly studied. In order to improve the biomechanical evaluation of the tennis serve. Our goal is to provide a comprehensive view of the major factors of an evaluation protocol. [less ▲]

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See detailAssessment of extreme value overestimations with equivalent static wind loads
Blaise, Nicolas ULg; Andrianne, Thomas ULg; Denoël, Vincent ULg

in Journal of Wind Engineering & Industrial Aerodynamics (2017)

The wind-resistant design using equivalent static wind loads is convenient for structural engineers. This paper studies the reliability of such an approach in the case of non-Gaussianities in both ... [more ▼]

The wind-resistant design using equivalent static wind loads is convenient for structural engineers. This paper studies the reliability of such an approach in the case of non-Gaussianities in both aerodynamic pressures and responses. These non-Gaussianities are responsible for overestimations of envelope values and may result in uneconomical designs, if not appropriately understood, assessed and addressed. In this study, it is shown that the equivalent static wind loads defined with the Conditional Expected Load method, which extends the physical meaning of the Load-Response Correlation approach in a non-Gaussian framework, improves the issue of overestimations of envelope values. Several envelopes of structural responses are considered: the mean of extremes and the 86% quantiles of extremes, together with two reference periods (10 min and 1 h). Extensive wind tunnel measurements have been collected, which correspond to 371 h full scale. This study is undertaken for quasi-static analysis of structures and is illustrated with a low-rise building. [less ▲]

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See detailAlgorithm for Temporal Gait Analysis Using Wireless Foot-Mounted Accelerometers
Boutaayamou, Mohamed ULg; Denoël, Vincent ULg; Bruls, Olivier ULg et al

Book published by Springer (2017)

We present a new signal processing algorithm that extracts five gait events: heel strike, toe strike, heel-off, toe-off, and heel clearance from only two accelerometers attached on the heels of the ... [more ▼]

We present a new signal processing algorithm that extracts five gait events: heel strike, toe strike, heel-off, toe-off, and heel clearance from only two accelerometers attached on the heels of the subjects usual shoes. This algorithm first uses a continuous wavelet-based segmentation that parses the signal of consecutive strides into motionless periods defining relevant local acceleration signals. Then, the algorithm uses versatile techniques to accurately extract the five gait events from these local acceleration signals. We validated, on a stride-by-stride basis, the extraction of these gait events by comparing the results with reference data provided by a kinematic 3D analysis system and a video camera. The accuracy and precision achieved by the extraction algorithm for healthy subjects, the reduced number of accelerometer units required, and the validation results obtained, encourage us to further study this system in pathological conditions. [less ▲]

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See detailAnalyse des Structures II
Denoël, Vincent ULg

Learning material (2017)

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See detailFast In-Plane Dynamics of a Beam with Unilateral Constraints
Liakou, Anna; Denoël, Vincent ULg; Detournay, Emmanuel

in Journal of Engineering Mechanics (2017), 0(0), 04016116

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See detailResponse to the discussion on “Reconstruction of the envelope of non-Gaussian structural responses with principal static wind loads by N. Blaise, T. Canor and V. Denoël”
Blaise, Nicolas; Canor, Thomas; Denoël, Vincent ULg

in Journal of Wind Engineering & Industrial Aerodynamics (2017)

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See detailReproducibility of a tennis serve protocol
Tubez, François ULg; FORTHOMME, Bénédicte ULg; Croisier, Jean-Louis ULg et al

Conference (2016, July 08)

INTRODUCTION Serve in modern tennis game is a real offensive weapon for players. In kinematic analysis, it is the most studied stroke of this game because it is the only stroke played in a closed skill ... [more ▼]

INTRODUCTION Serve in modern tennis game is a real offensive weapon for players. In kinematic analysis, it is the most studied stroke of this game because it is the only stroke played in a closed skill. Players have a maximum of control on this stroke. It is unclear whether 3D kinematic tests are reproducible for the same player under identical conditions and if a familiarization session is necessary. In practice, with professional players, who have little time available to perform tests, familiarization sessions are difficult. The aim of our study is to measure the reproducibility of a 3D serve protocol test. METHODS Nine tennis players (righties, regional level, 20 ± 2 years) were asked to hit first flat serves in a 1 m² area placed on the "T" zone of deuce diagonal of the tennis court. Two identical tests are performed one week apart. For each test, we selected the three best serves of the 25 trials (with the highest speed and the highest accuracy). Kinetics measurements were performed using a 3D analysis system (Codamotion), a force platform (Kistler) and a radar gun. 28 markers were placed on the players’ bodies to measure kinematics of the movements: ankles, knees, hips, trunk, shoulder, elbow and wrist dominant side. We measured ball speed, leg drive, linear velocity of the racket and joints, joints range of motion and maximum angular velocities at different positions (armed, maximum external rotation and impact) (1). RESULTS All analyzed parameters (linear speeds of racket and joints, leg drive force, joint angles and angular velocities) are reproducible with exception of a small part of them. Our study shows that 5,7% (7 of 122 measurements) joint position parameters and 8,3% (4 of 48 measures) angular velocity parameters are not reproducible from a session to another. DISCUSSION Various errors sources encountered in 3D analysis can justify the presence of non-reproducible parameters (2-3). However, after this work, we can state that the established protocol provides reproducible results when analyzing the tennis serve. [less ▲]

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See detailApplications of the multiple timescale spectral analysis in wind engineering
Denoël, Vincent ULg

in Zingoni, Alphose (Ed.) Proceedings of the Sixth International Conference on Structural Engineering, Mechanics and Computation (2016, July)

The random response of civil engineering structures to the buffeting action of wind loads is typically composed of several components, usually referred to as the background component, in the low fre ... [more ▼]

The random response of civil engineering structures to the buffeting action of wind loads is typically composed of several components, usually referred to as the background component, in the low fre- quency zone and the resonant component(s) in the neighborhood of modal natural frequencies. It has become customary to study separately and add the contributions of these components to the total response, at least as far as the second order response (variance of structural responses) is concerned. Such a decomposition exists but is less usual for the computation of covariances of modal coordinates or of structural displacements, which are in turn necessary for the determination of internal stresses. The question of such a decomposition also holds for nonlinear systems, or even for the higher statistical moments of a linear structural system, should the response be non Gaussian. With very wide ranges of applicability, the Multiple Timescale Spectral Analysis summarizes under a unified framework recent works aiming at the development of such decompositions. This paper briefly pictures this particular theory based on perturbation methods, and provides illustrations of its applicability to the problems cited above. [less ▲]

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See detailEulerian Formulation of Elastic Rods
Huynen, Alexandre ULg; Detournay, Emmanuel; Denoël, Vincent ULg

in Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences (2016), 472(2190),

In numerous biological, medical and engineering applications, elastic rods are constrained to deform inside or around tube-like surfaces. To solve efficiently this class of problems, the equations ... [more ▼]

In numerous biological, medical and engineering applications, elastic rods are constrained to deform inside or around tube-like surfaces. To solve efficiently this class of problems, the equations governing the deflection of elastic rods are reformulated within the Eulerian framework of this generic tubular constraint defined as a perfectly stiff canal surface. This reformulation hinges on describing the rod deformed configuration by means of its relative position with respect to a reference curve, defined as the axis or spine curve of the constraint, and on restating the rod local equilibrium in terms of the curvilinear coordinate parameterizing this curve. Associated with a segmentation strategy, which partitions the global problem into a sequence of rod segments either in continuous contact with the constraint or free of contact (except for their extremities), this approach not only trivializes the detection of new contacts but also suppresses the isoperimetric constraints resulting from the self-feeding feature of these elementary problems and the imposition of the rod position at the extremities of each rod segments. [less ▲]

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