References of "Denoël, Vincent"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailClosed form solution of the stochastic torsional flutter of an 1 aeroelastic oscillator under buffeting loads
Heremans, Julien ULiege; Denoël, Vincent ULiege; Mayou, Anass ULiege

in Journal of Wind Engineering and Industrial Aerodynamics (in press)

The complete flutter analysis of a structure requires the repeated analysis of the aeroelastic response of the structure for various wind velocities. In a spectral approach, each of these analyses is ... [more ▼]

The complete flutter analysis of a structure requires the repeated analysis of the aeroelastic response of the structure for various wind velocities. In a spectral approach, each of these analyses is based on the integration of the power spectral density of the aeroelastic response. Traditional integration methods struggle to efficiently estimate these integrals because of the marked eakedness of the function in the neighborhood of the poles of the system. In this paper, we have derived an extension of the Background/Resonant decomposition (which is commonly applied under the quasi-steady assumption), to aeroelastic analysis, where the stiffness and damping of the coupled system changes with frequency. Both the background and resonant components take a more general form than in the well known case. They remain simple, however, and offer therefore a straightforward understanding of the response. The proposed formulation is illustrated with several examples of torsional flutter, where the critical state corresponds either to torsional galloping either to divergence. The study is limited to single degree-of-freedom systems but constitute the cornerstone of an extension to multi degree-of-freedom systems, where such an approximation becomes very interesting in terms of computational efficiency. [less ▲]

Detailed reference viewed: 76 (4 ULiège)
Full Text
Peer Reviewed
See detailOn the axial force identification in Euler-Bernoulli beams with unknown boundary conditions
Foti, Francesco ULiege; Geuzaine, Margaux ULiege; Denoël, Vincent ULiege

in Proceedings of the XI International Conference on Structural Dynamics, EURODYN 2020 (2020, November 23)

Identification of the tensile force in slender axially-loaded structural elements, such as stay cables, metallic bars and tie-rods, is of paramount importance for health mon- itoring and safety assessment ... [more ▼]

Identification of the tensile force in slender axially-loaded structural elements, such as stay cables, metallic bars and tie-rods, is of paramount importance for health mon- itoring and safety assessment purposes. Dynamic testing techniques provide the ground for quick and cheap identification strategies, based on the knowledge of: (a) a set of iden- tified natural frequencies, and (b) a structural model that relates natural frequencies to the axial-force value. Within this framework, reliability of the identified axial force values depends, among other factors, on the predictive capabilities of the underlying structural model. Errors may arise, in particular, from the modeling of boundary conditions. The present paper analytically investigates the effect of boundary conditions on the modal prop- erties of axially loaded Euler-Bernoulli beam elements. Starting from theoretical results obtained on this archetypal structural model, a numerical procedure for the identification of the axial force in beam elements with unknown bending stiffness and boundary condi- tions is then presented. Parametric analyses are carried out to quantitatively assess the accuracy of the proposed identification algorithm in the case of frequencies contaminated by measurement errors. [less ▲]

Detailed reference viewed: 34 (1 ULiège)
Full Text
Peer Reviewed
See detailEfficient estimation of the skewness of the response of a wave-excited oscillator
Geuzaine, Margaux ULiege; Denoël, Vincent ULiege

in Proceedings of the XI International Conference on Structural Dynamics, EURODYN 2020 (2020, November)

The Multiple Timescale Spectral Analysis is a framework relying on the existence of well-separated timescales in the dynamic response of structures to generalize for higher-order statistics the famous ... [more ▼]

The Multiple Timescale Spectral Analysis is a framework relying on the existence of well-separated timescales in the dynamic response of structures to generalize for higher-order statistics the famous background/resonant decomposition, widely applied by the wind engineer- ing community to compute the variance of the response of SDOF structures or of each modal response of MDOF structures. This fast spectral analysis method mainly concerns the statistics of the response of onshore structures subjected to a buffeting wind loading whose characteristic frequency is typically lower than the natural frequencies of the structures concerned. By con- trast, when dealing with wave-loaded floating offshore structures, the roles of the slow and fast timescales are likely to be interchanged and the method is extended further in this paper to com- pute rapidly the variances and the skewnesses of modal responses of such structures responding in the inertial regime as well, since these statistics are necessary to consider the influence of the non-Gaussianity of the loading. [less ▲]

Detailed reference viewed: 42 (4 ULiège)
Full Text
Peer Reviewed
See detailIdentification of the essential features of the transient amplification of mistuned systems
Carassale, Luigi; Denoël, Vincent ULiege; Martel, Carlos et al

in Proceedings of the ASME 2020 Turbo Expo Conference (2020, September)

The dynamic behavior of bladed disks in resonance crossing has been intensively investigated in the community of turbomachinery, addressing the attention to (1) the transienttype response that appear when ... [more ▼]

The dynamic behavior of bladed disks in resonance crossing has been intensively investigated in the community of turbomachinery, addressing the attention to (1) the transienttype response that appear when the resonance is crossed with a finite sweep rate and (2) the localization of the vibration in the disk due to the blade mistuning. In real conditions, the two mentioned effects coexist and can interact in a complex manner. This paper investigates the problem by means of analytic solutions obtained through asymptotic expansions, as well as numerical simulations. The mechanical system is assumed as simple as possible: a 2-dof linear system defined through the three parameters: damping ratio , frequency mistuning , rotor acceleration  . The analytic solutions are calculated through the multiple-scale method. [less ▲]

Detailed reference viewed: 20 (1 ULiège)
Full Text
Peer Reviewed
See detailVortex induced vibration of two tandem cylinders in subcritical regime
Rigo, François ULiege; Denoël, Vincent ULiege; Andrianne, Thomas ULiege

Conference (2020, May)

Vortex induced vibrations (VIV) have been widely studied for a singular cylinder. Many engineering applications also involve multiple body configurations and particularly cylinders in tandem, with a ... [more ▼]

Vortex induced vibrations (VIV) have been widely studied for a singular cylinder. Many engineering applications also involve multiple body configurations and particularly cylinders in tandem, with a strong interaction between cylinders through wake interference, depending on the spacing between them. The specific features of this interaction has been widely studied in terms of topology. Some studies also propose to extend the well-known wake oscillator model from one to two tandem cylinders. These models based on a Van der Pol oscillator require empirical coefficients, particularly for the coupling terms between cylinder wakes, which have to be experimentally identified. Different configurations are thus required compared to the simple cases already studied. We propose to carry out an extensive experimental campaign in the low-subsonic wind tunnel of University of Liège to feed a VIV model. The quality of measures extends the knowledge in several aspects: (i) measurement in air instead of water, (ii) extensive pressure measurement on both cylinders, in case of (iii) free vibration test (both cylinders in free response) and extended to (iv) forced vibration test. The parametric study consists in studying the geometric effects (spacing and angle of attack between cylinders) and, on a side basis, the influence of turbulence properties (intensity, integral length scales) is studied regarding their effect on the syncronization of both cylinders and their wakes. The proposed work consists in a novel and complete (i) flow characterization in static, free and forced motion of both cylinders, (ii) identification of experimental parameters used to supply an improved VIV model. [less ▲]

Detailed reference viewed: 48 (5 ULiège)
Full Text
Peer Reviewed
See detailStochastic analysis of vortex-induced vibrations by means of a randomized wake-oscillator model
Denoël, Vincent ULiege

in Proceedings of the Second International Symposium on Flutter and its Application (2020, May)

The influence of wind turbulence on the vortex-induced response of a single cylinder is not well understood yet. It also appears that there is no commonly accepted model to represent the influence of a ... [more ▼]

The influence of wind turbulence on the vortex-induced response of a single cylinder is not well understood yet. It also appears that there is no commonly accepted model to represent the influence of a turbulent flow. In this paper, a low-order phenomenological model, inspired by the smooth flow VIV model derived by Facchinetti et al., is described and analyzed. The main features of this model are presented. In particular, the topology of the limit cycle of the coupled wake-oscillator system is analyzed in the presence of noise. The extent of the so-called lock-in domain is interpreted, in the stochastic version of the problem, by means of the statistics of the phase between the two degrees-of-freedom. Based on the slow phase model of the problem, it is shown that both the turbulence intensity and the frequency content of the turbulence play a significant role in the statistical distributions of the magnitudes of fluid and structure oscillations. The derivation is proposed in a dimensionless version so that the major scalings driving the problem naturally come out of the analysis. [less ▲]

Detailed reference viewed: 145 (6 ULiège)
Full Text
Peer Reviewed
See detailActivation Profile of Scapular Stabilizing Muscles in Asymptomatic People. Does Scapular Dyskinesis Have an Impact on Its?
Tooth, Camille ULiege; Schwartz, Cédric ULiege; Croisier, Jean-Louis ULiege et al

in American Journal of Physical Medicine and Rehabilitation (2020)

Detailed reference viewed: 24 (6 ULiège)
Full Text
Peer Reviewed
See detailKinesiotaping for scapular dyskinesis: The influence on scapular kinematics and on the activity of scapular stabilizing muscles
Tooth, Camille ULiege; Schwartz, Cédric ULiege; Colman, David ULiege et al

in Journal of Electromyography and Kinesiology (2020), 51

Scapular dyskinesis is observed in 61% of overhead athletes (Burn et al., 2016). For most of them, it remains asymptomatic. However, scapular dyskinesis is considered a risk factor for shoulder injury by ... [more ▼]

Scapular dyskinesis is observed in 61% of overhead athletes (Burn et al., 2016). For most of them, it remains asymptomatic. However, scapular dyskinesis is considered a risk factor for shoulder injury by some authors (Clarsen et al., 2014). The aim of this study is to explore the effectiveness of kinesiotaping in modifying scapular kinematics and peri-scapular muscle activity in dyskinetic athletes. The 3-dimensional position and orientation of the scapula as well as the activation of upper trapezius, lower trapezius and serratus anterior were recorded in twenty asymptomatic athletes during shoulder movements (flexion and abduction), in loaded and unloaded conditions and in three circumstances (standard, kinesiotaping 1, kinesiotaping 2). A significant decrease between 9 and 12% in upper trapezius activity was observed with kinesiotaping 1 and 2. Lower trapezius activity was slightly increased with kinesiotaping 1 while it was significantly decreased about 15–20% with kinesiotaping 2. No change was observed in serratus anterior activity, for either kinesiotaping 1 or 2. Considering scapular kinematics, both kinesiotaping 1 and 2 significantly increased posterior tilt and upward rotation. External rotation was decreased with kinesiotaping 2, in comparison to standard condition. Kinesiotaping, and especially taping 1, seems to be an effective method for changing periscapular muscle activity and scapular kinematics. [less ▲]

Detailed reference viewed: 60 (8 ULiège)
Full Text
Peer Reviewed
See detailA foot/ground contact model for biomechanical inverse dynamics analysis
Van Hulle, Romain ULiege; Schwartz, Cédric ULiege; Denoël, Vincent ULiege et al

in Journal of Biomechanics (2020), 100

Detailed reference viewed: 67 (7 ULiège)
Full Text
Peer Reviewed
See detailPlatelet-rich plasma (PRP) and tendon healing: comparison between fresh and frozen-thawed PRP
KAUX, Jean-François ULiege; Libertiaux, Vincent; Dupont, Laura ULiege et al

in Platelets (2020), 31(2), 221-225

Platelet-rich plasma (PRP) is increasingly used in the treatment of musculoskeletal diseases. Its preservation by freezing it for the realization of multiple injections in clinical use has never been ... [more ▼]

Platelet-rich plasma (PRP) is increasingly used in the treatment of musculoskeletal diseases. Its preservation by freezing it for the realization of multiple injections in clinical use has never been discussed. Calcaneal tendons of rats were surgically sectioned. Platelet concentration of the PRP was 2.5 x 106/μl with autologous plasma of rats. Frozen-thawed PRP was prepared by performing two cycles of freezing and thawing on PRP aliquots. Both platelet preparations were injected in the lesion. Biomechanical and histological evaluations were carried out after 7, 20 or 40 days post surgery. After 7 and 40 days, no significant difference was observed between the PRP and the frozen-thawed PRP group. There is however a difference 20 days after surgery: the ultimate tensile strength (UTS) was greater in the fresh PRP group. No obvious difference with histological aspect was observed between the two groups. In conclusion, fresh PRP and frozen-thawed PRP injections can lead to similar results in the healing process of section calcaneal tendons of rats. Improvements with fresh PRP are slight. PRP could thus be frozen to be preserved if multiple injections are needed (e.g. osteoarthritis). [less ▲]

Detailed reference viewed: 241 (41 ULiège)
Full Text
Peer Reviewed
See detailDerivation of a slow phase model of vortex-induced vibrations for smooth and turbulent oncoming flows
Denoël, Vincent ULiege

in Journal of Fluids and Structures (2020), 99

This paper analyzes the influence of turbulence on a wake-oscillator model. Turbulence is introduced by randomizing the model proposed by Facchinetti et al. under the quasi-steady assumption. A multiple ... [more ▼]

This paper analyzes the influence of turbulence on a wake-oscillator model. Turbulence is introduced by randomizing the model proposed by Facchinetti et al. under the quasi-steady assumption. A multiple scale analysis of the deterministic model shows that the response is governed by a dimensionless group D, expressed as a function of the amplitudes of the forcing terms in the two governing equations, the total (aerodynamic plus structural) damping and the parameter ε of the fluid Van der Pol oscillator. The influence of turbulence is interpreted as a stochastic noise of small intensity and with a slower timescale than the (fast) oscillations, which is typical of wind engineering applications. A slow phase model of the problem is then derived by assuming that the small turbulence drives the system only slightly away from its limit cycle in smooth flow conditions. Standard modeling techniques borrowed from other fields of physics, in particular the observation of phase shifts and their accumulation, are used to highlight conditions under which the turbulence of the oncoming flow might reduce the amplitudes of vibrations of the body. The slow phase model is derived in smooth flow conditions, then extended to turbulent flow. It recalls that the phase plays a central role in synchronization problems, and that the response amplitude should only be considered as a sub-product of the slow phase. The slow phase model is expressed by means of a first order nonlinear differential equation for the phase and a memoryless transformation for the response amplitudes. Its solution is explicit and simple in some limiting cases. In particular, for small turbulence intensity, the response is shown to be insensitive to turbulence when its frequency content is not low enough. This major dependence upon the frequency content of the turbulence explains that the reduction of VIV due to turbulence cannot be explained by the turbulence intensity only, as usually considered today. The required relative smallnesses of the turbulence and its frequency content naturally appear in the derivation, which is led in a dimensionless manner. Finally, the present study constitutes an analysis of a phenomenological model which could be used in a much wider concept than of the elastically-mounted circular cylinder. [less ▲]

Detailed reference viewed: 38 (2 ULiège)
Full Text
Peer Reviewed
See detailA stochastic and continuous model of aeolian vibrations of conductors equipped with stockbridge dampers
Foti, Francesco; Denoël, Vincent ULiege; Martinelli, Luca et al

in Proceedings of the EURODYUN 2020 Conference (2020)

Suspended conductors and guard wires of overhead electrical transmission lines (OHL) are prone to aeolian vibrations, resulting from the alternate shedding of vortices in the wake of the cable. These ... [more ▼]

Suspended conductors and guard wires of overhead electrical transmission lines (OHL) are prone to aeolian vibrations, resulting from the alternate shedding of vortices in the wake of the cable. These vibrations can occur under light to moderate wind and, whenever not properly controlled, can induce wear damage and fatigue failures of the cables. Nonlinear passive control devices such as Stockbridge dampers, hence, are often installed along the line spans to reduce the vibration severity. The technical approach to the assessment of aeolian vibrations is based on the Energy Balance Method (EBM) and relies on the simplifying assumption of mono-modal oscillations. Typical aeolian vibration records, however, clearly show that several modes can be simultaneously excited due to wind variations in time and along the span. Aiming at overcoming the mono-modal vibration assumption of the EBM, in the present paper wind forces are modeled as a narrow band stochastic process, centered around the Strouhal frequency of the conductor and with arbitrary cross-correlation in space. A new approach, based on the well-known smooth endochronic Bouc-Wen model, is developed to describe the hysteretic dynamic response of Stockbridge dampers. An iterative solution strategy based on a stochastically equivalent linear damper model is then developed to investigate aeolian vibrations of a suspended cable with a Stockbridge damper attached along its length. [less ▲]

Detailed reference viewed: 27 (1 ULiège)
Full Text
Peer Reviewed
See detailTight shoulders: a clinical, kinematic and strength comparison of symptomatic and asymptomatic male overhead athletes before and after stretching
Schwartz, Cédric ULiege; Croisier, Jean-Louis ULiege; Bruls, Olivier ULiege et al

in European Journal of Sport Science (2020)

A tightness of the posterior structures of the throwing shoulder has been hypothesized to be associated with injuries and pain because of alterations of the scapular kinematics and muscular imbalances ... [more ▼]

A tightness of the posterior structures of the throwing shoulder has been hypothesized to be associated with injuries and pain because of alterations of the scapular kinematics and muscular imbalances. The aims of this study were to identify the clinical and biomechanical profile of symptomatic and asymptomatic overhead athletes with a tight shoulder and to evaluate the efficiency of a self-applied stretching program. Twenty male overhead athletes were recruited. Half of them reported a painful shoulder at the beginning of the study. For four weeks, the volunteers performed daily stretching exercises. Before and after the stretching program, gleno-humeral mobility, scapular kinematics, rotator muscles strength and pain were evaluated. Before stretching, the main difference between the groups was more impingement syndrome and rotator cuff tendon lesion positive tests in the symptomatic group (p<0.027, effect size = 0.51). After the program, pain reported by the symptomatic volunteers was reduced by approximately 40% and the gleno-humeral internal rotation bilateral difference was significantly reduced by 77.6% (p<0.009, effect size = 0.84). In the symptomatic group, the scapula at rest was significantly more posteriorly tilted (p=0.027, effect size = 0.69) after the stretching; a position that has been shown to limit the risk of impingement. The absence of significant differences of the profiles of the symptomatic and asymptomatic overhead athletes before stretching may indicate that the initiation of early prevention programs, including self-applied stretching, should not rely solely on biomechanical and clinical parameters and might be recommended to all players with a tight shoulder. [less ▲]

Detailed reference viewed: 40 (7 ULiège)
Full Text
Peer Reviewed
See detailAlgorithm for extracting initial and terminal contact timings during treadmill running using inertial sensors
Prijot, Laura ULiege; Schwartz, Cédric ULiege; Watrin, Julien et al

Conference (2020)

Inertial measurement units (IMUs) are now considered as an economical solution for long term assessment in real conditions. However, their use in running gait analysis is relatively new and limited ... [more ▼]

Inertial measurement units (IMUs) are now considered as an economical solution for long term assessment in real conditions. However, their use in running gait analysis is relatively new and limited. Detecting the timing at which the foot strikes the ground (initial contact, IC) and the timing at which the foot leaves the ground (terminal contact, TC) gives access to many relevant temporal parameters such as stance, swing or stride durations. In this paper, we present an original algorithm to extract IC and TC timings and associated parameters from running data. These data have been measured using a newly developed IMU-based hardware system in ten asymptotic participants who ran at three speeds (slow, normal, and fast) with different running patterns (natural, rearfoot strike, mid-foot strike, and forefoot strike). This algorithm has been validated against a 200 Hz video camera based on 7056 IC and TC timings and 6861 temporal parameters. This algorithm extracted ICs and TCs with an accuracy and precision of (median [1st quartile; 3rd quartile]) 5 ms [-5 ms, 15 ms] and 0 ms [-5 ms, 5 ms], respectively. The relative errors in the extraction of stride and stance durations are -1.56 ± 3.00% and 0.00 ± 1.32%, respectively. [less ▲]

Detailed reference viewed: 47 (9 ULiège)
Full Text
Peer Reviewed
See detailOn the identification of axial force in stay cables anchored to flexible supports
Foti, Francesco ULiege; Geuzaine, Margaux ULiege; Denoël, Vincent ULiege

Conference (2020)

Identification of the axial force in stay cables is of paramount importance for health moni- toring and safety assessment purposes. Vibration based testing techniques provide the ground for quick and ... [more ▼]

Identification of the axial force in stay cables is of paramount importance for health moni- toring and safety assessment purposes. Vibration based testing techniques provide the ground for quick and cheap identification strategies, based on the knowledge of (a) a set of identified natural frequencies, and (b) a structural model that relates natural frequencies to the axial force value. Reliability of results, hence, is inherently related to the predictive capabilities of the underlying structural model. Errors may arise, in particular, from the modeling of boundary conditions. Ideal boundary conditions are often introduced, in the form of either perfectly hinged or perfectly clamped cable end sections, to simplify the analytical treatment of the problem. As a first step towards a quantitative assessment of the effect of unknown boundary conditions on the modal properties of stay cables, the present paper focuses on a taut cable with small bending stiffness anchored to flexible supports. Asymptotically accurate closed form equations for the natural frequencies of the cable are firstly obtained, generalizing a well-known result of the literature valid in the particular case of perfectly clamped end sections (Morse and Ingard, 1968; Caetano, 2007). Starting from the theoretical results obtained on this archetypal structural model, a simple but effective procedure to simultaneously identify the axial force,the bending stiffness and a support flexibility parameter of the stay cable is presented and validated through numerical testing. Parametric analyses are then carried out to assess the effects of uncertainties in the definition of the degree-of-fixity of the cable restraints on the accuracy of the identified axial force in the case of frequencies contaminated by measurement errors. [less ▲]

Detailed reference viewed: 27 (2 ULiège)
Full Text
Peer Reviewed
See detailDevelopment of a general monitoring program for bridge stays and hangers in Wallonia
Geuzaine, Margaux ULiege; Foti, Francesco ULiege; Rutten, Christophe et al

Conference (2020)

Recently, dramatic accidents drew attention to the monitoring of bridges. In this context and as Walloon bridges are aging, the Wallonia Public Service department has decided to launch a research project ... [more ▼]

Recently, dramatic accidents drew attention to the monitoring of bridges. In this context and as Walloon bridges are aging, the Wallonia Public Service department has decided to launch a research project which aims at remotely keeping track of the time evolution of tension in cables. The present paper reports on the design, implementation and preliminary testing of an accurate and non-intrusive axial force monitoring system. Wireless sensors are used to measure accelerations at selected points along the cables. Vibration measurements are acquired on a daily basis and processed to get estimates of the natural frequencies of vibration of the cable that feed up a numerical algorithm for the axial force identification. All cables studied in this project are highly tensioned, but their flexural rigidities are not always negligible, although small. Preliminary tests have also revealed that the flexibility of end conditions is actually far from the ideal cases of perfectly hinged or clamped. Based on these observations, the cables are deemed to be accurately described as pre- stressed Euler-Bernoulli beam anchored to flexible supports. A computationally efficient semi-analytical approach has been derived to calculate the natural frequencies of the struc- tural model. A custom implementation of the well-known Differential Evolution optimization algorithm (Storn and Price, 1995) is then adopted to adjust the model parameters in order to minimize the difference between calculated and measured natural frequencies. Special atten- tion is devoted, within this framework, to the definitions of conditions leading to an accurate identification of the parameters representing the flexibility of the anchorages whenever in pres- ence of noisy experimental frequencies. The delivered talk will cover the mathematical details of the model as well as the practical challenges of its deployment to the whole stock of bridges in Wallonia. [less ▲]

Detailed reference viewed: 41 (2 ULiège)
Full Text
Peer Reviewed
See detailEfficient estimation of the skewness of the response of a linear oscillator under non-Gaussian loading
Geuzaine, Margaux ULiege; Esposito Marzino, Michele ULiege; Denoël, Vincent ULiege

Conference (2020)

In the frequency domain, the third moment of the response of a linear oscillator subjected to a random loading is the result of the double integration of the bispectrum of the response, which corresponds ... [more ▼]

In the frequency domain, the third moment of the response of a linear oscillator subjected to a random loading is the result of the double integration of the bispectrum of the response, which corresponds to the product of the bispectrum of the loading and a second-order kernel function [1]. Both the bispectrum of the loading and the kernel are in principle complex functions. The Multiple Timescale Spectral Analysis (MTSA) hinges on the existence of well-separated timescales in the response of the oscillator to derive simple analytical approximations of the main contributions to the integral of the bispectrum, which reduce the order of integration by one, at least [1]. The MTSA is therefore able to provide a rapid and accurate estimation of the third moment of the response. Until now, the MTSA has been applied to establish the expressions of the background and the biresonant components of the third moment of the response of a linear oscillator subjected to a buffeting wind loading, which is characterized by a low frequency content. Moreover, since the non-Gaussian buffeting loads on bridge decks are typically defined by a polynomial function of a Gaussian process, their bispectrum is actually real [2]. More generally, the real part of the bispectrum of the response is composed of the product of the real parts of the bispectrum of the loading and the second-order kernel as well as the product of the imaginary parts of these two functions. Consequently, when the bispectrum of the loading contains an imaginary part, the third moment of the response is modified by an additional biresonant component whose expression is presented and applied in this paper in the light of a statistical treatment of wind pressure data on a high rise building [3]. When the natural frequency of the system decreases, it appears that the biresonant component coming from the product of the imaginary parts becomes comparable to or even greater than the biresonant component coming from the product of the real parts. [less ▲]

Detailed reference viewed: 34 (6 ULiège)
Full Text
Peer Reviewed
See detailNormalizing gastrocnemius muscle EMG signal: an optimal set of maximum voluntary isometric contraction tests for young adults considering reproducibility
Schwartz, Cédric ULiege; WANG, François-Charles ULiege; Forthomme, Bénédicte ULiege et al

in Gait and Posture (2020), 82(October), 196-202

Background Even though most studies normalize the surface EMG signal of the gastrocnemius muscle using a single position of maximum voluntary isometric contraction (MVIC), several studies tend to indicate ... [more ▼]

Background Even though most studies normalize the surface EMG signal of the gastrocnemius muscle using a single position of maximum voluntary isometric contraction (MVIC), several studies tend to indicate that several positions are in fact needed to obtain a maximal voluntary activation (MVA) for most of the subjects. However, no combination of positions has already been described. Research question A combination of MVIC positions to normalize the EMG signal of the gastrocnemius muscle is investigated. the influence of using several positions on the reproducibility of the normalization process is evaluated. Methods Twenty healthy volunteers (45% female – 55 % male, 25.4 years (SD 4.3), 72.6 kg (SD 13.9), 1.78 m (SD 0.12)) were recruited. Six positions for MVIC were compared and the effect of several normalization combinations on a functional task (gait) was evaluated. Results Several positions are needed to obtain at least 90% of the MVA for 90% of the volunteers even though the use of a single well-chosen position (unipodal standing position with knee fully extended and ankle fully plantar-flexed) will lead to no statistically significant differences of the gait evaluation during stance phase. For each position, five repetitions of the MVIC are recommended to obtain a valid MVA. Significance This study confirms that using several MVIC positions is recommended when possible to normalize the gastrocnemius muscle EMG signal. However, in the situation of a patient where limited MVIC attempts are possible, using a single well-chosen position should not significantly influence the amplitude and the reproducibility of the measures. [less ▲]

Detailed reference viewed: 35 (2 ULiège)
Full Text
Peer Reviewed
See detailQuality assessment of synthetic wind turbulence
Heremans, Julien ULiege; Denoël, Vincent ULiege

in Belgian-Dutch IABSE Young Engineers Colloquium (YEC2020) (2020)

Detailed reference viewed: 19 (1 ULiège)
Full Text
See detailIntroduction à l'analyse spectrale à plusieurs échelles temporelles de ponts flottants
Geuzaine, Margaux ULiege; Denoël, Vincent ULiege

Scientific conference (2019, November 25)

Présentation vulgarisée de mes recherches pour un public principalement composé d'ingénieur civils des constructions.

Detailed reference viewed: 31 (4 ULiège)