References of "Denoël, Vincent"
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See detailNormalizing shoulder EMG: an optimal set of maximum isometric voluntary contraction tests considering reproducibility
Schwartz, Cédric ULg; Tubez, François ULg; WANG, François-Charles ULg et al

in Journal of Electromyography and Kinesiology (in press)

Normalization of the electromyography (EMG) signal is often performed relatively to maximal voluntary activations (MVA) obtained during maximum isometric voluntary contraction (MVIC). The first aim was to ... [more ▼]

Normalization of the electromyography (EMG) signal is often performed relatively to maximal voluntary activations (MVA) obtained during maximum isometric voluntary contraction (MVIC). The first aim was to provide an inter-session reproducible protocol to normalize the signal of eight shoulder muscles. The protocol should also lead to a level of activation >90% of MVA for >90% of the volunteers. The second aim was to evaluate the influence of the method used to extract the MVA from the EMG envelope on the normalized EMG signal. Thirteen volunteers performed 12 MVICs twice (one-week interval). Several time constants (100 ms to 2 s) were compared when extracting the MVA from the EMG envelope. The EMG activity was also acquired during an arm elevation. Our results show that a combination of nine MVIC tests was required to meet our requirements including reproducibility. Both the number of MVIC tests and the size of the time constant influence the normalized EMG signal during the dynamic activity (variations up to 15%). A time constant of 1 s was a good compromise to extract the MVA. These findings are valuable to improve the reproducibility of EMG signal normalization. [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 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 (2017), 17(9), 1143-1152

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 detailBeam-to-column joints, column bases and joint components under impact loading
Demonceau, Jean-François ULg; Vanvinckenroye, Hélène ULg; D'Antimo, Marina ULg et al

in Proceeding of Eurosteel 2017 conference (2017, September)

Recent events such as natural catastrophes or terrorist attacks have highlighted the necessity to ensure the structural integrity of buildings under exceptional events. For more than 10 years, the ... [more ▼]

Recent events such as natural catastrophes or terrorist attacks have highlighted the necessity to ensure the structural integrity of buildings under exceptional events. For more than 10 years, the University of Liege is strongly involved in researches on the response of structures further to such exceptional events through participations to national or European research projects. In particular, the University of Liege has contributed very recently to a European research project entitled ROBUSTIMPACT investigating the behaviour of steel or steel-concrete composite building structures subjected to impact loading and proposing simplified procedures to predict the response of such structures under the considered scenario. As a contribution to this research project, an experimental test campaign was realised in Liège; the objective was to study the behaviour of beam-to-column joints, of column bases and of most of their constitutive components under impact loading and, in particular, to highlight the influence of the strain rate effects on the response of the studied joints and components. The proposed paper first describes the conducted test campaign with all the required details about the tested specimens and the testing setup; then the analysis of the so-obtained experimental results is presented. Finally authors’ views on how to account for the strain rate effects in analytical approaches for joint design is briefly expressed. [less ▲]

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See detailExperimental and numerical investigation of the nonlinear dynamics of compliant mechanisms for deployable structures
Dewalque, Florence ULg; Schwartz, Cédric ULg; Denoël, Vincent ULg et al

in Mechanical Systems & Signal Processing (2017), 101

This paper studies the dynamics of tape springs which are characterised by a highly geometrical nonlinear behaviour including buckling, the formation of folds and hysteresis. An experimental set-up is ... [more ▼]

This paper studies the dynamics of tape springs which are characterised by a highly geometrical nonlinear behaviour including buckling, the formation of folds and hysteresis. An experimental set-up is designed to capture these complex nonlinear phenomena. The experimental data are acquired by the means of a 3D motion analysis system combined with a synchronised force plate. Deployment tests show that the motion can be divided into three phases characterised by different types of folds, frequencies of oscillation and damping behaviours. Furthermore, the reproducibility quality of the dynamic and quasi-static results is validated by performing a large number of tests. In parallel, a nonlinear finite element model is developed. The required model parameters are identified based on simple experimental tests such as static deformed configurations and small amplitude vibration tests. In the end, the model proves to be well correlated with the experimental results in opposite sense bending, while in equal sense, both the experimental set-up and the numerical model are particularly sensitive to the initial conditions. [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 detailAnalyse des Structures II
Denoël, Vincent ULg

Learning material (2017)

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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 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)

Detailed reference viewed: 50 (4 ULg)