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See detailOn the Use of Principal Component Analysis for Parameter Identification and Damage Detection in Structures
Golinval, Jean-Claude ULg

Conference (2014, November 20)

Modal analysis is used extensively for understanding the dynamic behaviour of structures as well as for structural health monitoring or damage detection based on output-only measurements. In this ... [more ▼]

Modal analysis is used extensively for understanding the dynamic behaviour of structures as well as for structural health monitoring or damage detection based on output-only measurements. In this presentation, a different approach based on principal component analysis is considered. Principal component analysis (PCA), also called proper orthogonal decomposition (POD), is a multi-variate statistical method that aims at obtaining a compact representation of the data. In the present paper, PCA (POD) is used for three purposes, namely damage detection, structural health monitoring and identification of nonlinear parameters. The key idea of PCA is to reduce a large number of measured data to a much smaller number of uncorrelated variables while retaining as much as possible of the variation in the original data. To this purpose, an orthogonal transformation to the basis of the eigenvectors of the sample covariance matrix is performed, and the data are projected onto the subspace spanned by the eigenvectors corresponding to the largest eigenvalues. This transformation has the property to decorrelate the signal components and to maximize variance. The first problem to which PCA is applied here is the damage detection problem. When applied to vibration measurements, it can be shown that the basis of eigenvectors (called the proper orthogonal modes) span the same subspace as the mode-shape vectors of the monitored structure. Thus the damage detection problem may be solved using the concept of subspace angle between a reference subspace spanned by the eigenvectors of the initial (undamaged) structure and the subspace spanned by the eigenvectors of the current (possibly damaged) structure. The second problem concerns structural health monitoring of civil engineering structures when environmental effects (e.g. the influence of the variation of the ambient temperature) have to be removed from the structural changes. In this case, PCA may be applied on identified modal features (e.g. the natural frequencies) to separate the changes due to environmental variations from the changes due to damage sources. This procedure is illustrated on the example of a real bridge located in Luxembourg. The third problem is related to the estimation of nonlinear parameters using model updating techniques. In this case, the most interesting property of PCA is that it minimizes the average squared distance between the original signal and its reduced linear representation. When applied to nonlinear problems, PCA gives the optimal approximating linear manifold in the configuration space represented by the data. The linear nature of the method is appealing because the theory of linear operators is still available. However, it should be borne in mind that it also exhibits its major limitation when the data lie on a nonlinear manifold. [less ▲]

Detailed reference viewed: 29 (2 ULg)
See detailUne photographie peut-elle faire l’événement ? Document, histoire et mémoire.
Hamers, Jérémy ULg

Conference given outside the academic context (2014)

Detailed reference viewed: 10 (3 ULg)
See detailLa pensée et l'institution psychanalytiques à l'épreuve e la question de l'homosexualité
Naziri, Despina ULg

Scientific conference (2014, November 20)

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See detailTraitements conservateurs de la gonarthrose
Kaux, Jean-François ULg

Conference (2014, November 20)

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See detailA Debate on Responsible Research and Innovation
Van Oudheusden, Michiel ULg

Conference (2014, November 20)

In the space of just a few years the concept of Responsible Research and Innovation (RRI), or in Dutch Maatschappelijk verantwoord innoveren (MVI), has gained considerable ground: NWO has an MVI-program ... [more ▼]

In the space of just a few years the concept of Responsible Research and Innovation (RRI), or in Dutch Maatschappelijk verantwoord innoveren (MVI), has gained considerable ground: NWO has an MVI-program that has so far funded three rounds of research proposals; Horizon 2020 regularly refers to RRI; and there is now a new journal devoted to RRI. In this panel we focus on the following questions: • How could the concept become so popular in such a relatively short time? • What, if anything, is new in RRI, when we compare it to e.g. CTA, participatory TA, Public Engagement, etc? • If we want to make research and innovation more responsible and responsive to society’s needs, what are the opportunities and obstacles? • What are the conditions for successful mainstreaming of RRI? Panel members Frank Kupper (Athena Institute) Hub Zwart (Centre for Society and the Life Scences), Michiel van Oudheusden (author of a dissertation on Flemish RRI initiatives), and Tsjalling Swierstra (co-founder of the Journal for RI) share their thoughts with colleagues in the audience. [less ▲]

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See detailContraires, attention danger !
Steffens, Marie ULg

Conference given outside the academic context (2014)

Marie Steffens explores how two opposites used in the same sentence utilize our thought processes to influence the way we conceptualize the world. Opposites linked together in one sentence can express ... [more ▼]

Marie Steffens explores how two opposites used in the same sentence utilize our thought processes to influence the way we conceptualize the world. Opposites linked together in one sentence can express, inter alia, the totality of a category (rich and poor means “all people”). By studying the mechanisms underlying the expression of a totality, we try to understand how opposites can manipulate us. [less ▲]

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See detailSolar Wind Interaction with the Magnetosphere of Jupiter : Impact on the Magnetopause and the Aurorae
Bonfond, Bertrand ULg; Grodent, Denis ULg; Gérard, Jean-Claude ULg et al

Conference (2014, November 20)

The outcome of the interaction between the solar wind and the Jovian magnetic field bears many differences compared to the Earth's case. At Earth, the solar wind is the major particle and energy source in ... [more ▼]

The outcome of the interaction between the solar wind and the Jovian magnetic field bears many differences compared to the Earth's case. At Earth, the solar wind is the major particle and energy source in the magnetosphere. At Jupiter, the tremendous volcanism on the moon Io is the main plasma source and Jupiter's rapid rotation (relative to its size) is the main energy source for the particles populating its magnetosphere. Combined with a weaker solar wind pressure and a larger Alfvén Mach number as the distance from the Sun increases, all these parameters modify the relative importance of large scale Dungey reconnection and viscous interaction at the magnetopause. In order to study these differences, here we present a statistical analysis of magnetopause waves and flux tube event on the Jovian magnetopause, based on in-situ measurement from the spacecraft that flew-by or orbited around Jupiter. Moreover, variations of the solar wind have significant impact on the Jovian magnetospheric current systems and such changes reflect on the aurora. In this presentation, we will also review the recent findings concerning the aurora at Jupiter and their relationship with the solar wind. [less ▲]

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See detailENMG non classique
WANG, François-Charles ULg

Scientific conference (2014, November 20)

Detailed reference viewed: 11 (1 ULg)
See detailBoolean Functions for Classification: Logical Analysis of Data
Crama, Yves ULg

Conference (2014, November 20)

Detailed reference viewed: 13 (0 ULg)
See detailJoint care composition
Serisier, Samuel; Comblain, Fanny ULg; Henrotin, Yves ULg

Patent (2014)

The present invention relates to a composition comprising curcuminoid with green tea polyphenol or with a combination of glycine, proline and hydroxyproline for use in preventing or treating ... [more ▼]

The present invention relates to a composition comprising curcuminoid with green tea polyphenol or with a combination of glycine, proline and hydroxyproline for use in preventing or treating osteoarthritis. It also relates to a method of preventing or treating osteoarthritis in mammals, the method comprising administering to said mammal a composition which comprises curcuminoid with green tea polyphenol or with a combination of glycine, proline and hydroxyproline. [less ▲]

Detailed reference viewed: 11 (2 ULg)
Peer Reviewed
See detailSpatial Analysis of GNSS Measurements from an Equatorial Ionospheric Scintillation Monitoring Receiver (ISMR) Network
Lonchay, Matthieu ULg; Wautelet, Gilles ULg; Cornet, Yves ULg et al

Conference (2014, November 19)

The ionosphere has always been a major limitation for GNSS positioning applications. Free electrons in the ionosphere perturb the propagation of GNSS radio signals involving both refraction and ... [more ▼]

The ionosphere has always been a major limitation for GNSS positioning applications. Free electrons in the ionosphere perturb the propagation of GNSS radio signals involving both refraction and diffraction effects. In particular, small-scale ionospheric irregularities generated by different physical processes may cause scattering effects on GNSS signals, producing rapid fluctuations of the signal phase and amplitude as a result. Such scintillations of GNSS signals are responsible for critical consequences regarding applications, such as precise positioning, due to many resulting effects: cycle slips, signal power fading, receiver loss of lock and poor resulting satellite geometry. Ionospheric Scintillation Monitoring Receivers collect high-rate GNSS data. Specific scintillation parameters, such as the well-known S4 and Phi60 indices, are built on high-rate measurements performed on GNSS signals and provide additional information to characterize the intensity of such an event occurring at a specific geographic location at a given time. Spatial Statistics belong to the field of Spatial Analysis, Geography and GIS (Geographic Information System). This discipline allows to perform analyses of data which are localised in space. Ionospheric Scintillation observations achieved by ISMR stations can be characterized by a set of attributes (S4, Phi60, Rate of TEC, etc.) including also the geographic location of their respective Ionospheric Pierce Point (IPP). By combining the simultaneous Multi-GNSS ISMR measurements from a network of ISMR stations, we can obtain a spatially denser data set, able to support spatial statistics tests. The idea of our research is to provide a spatio-temporal analysis of ionospheric scintillation events over Equatorial regions by applying spatial statistics on ISMR Multi-GNSS measurements. In particular, by using spatial statistics, we aim to resolve specific issues regarding ionospheric scintillation data from an ISMR network established in Brazil. The research consists in spatially describing the data set, detecting and measuring potential spatial autocorrelation, determining the scale of the spatial dependency and finally producing an interpolated scintillation sky map at a given time. In terms of applicability of the methodology, our research project consists in exploiting the spatio-temporal analysis performed on ionospheric scintillation data in order to improve the performances and the reliability of Absolute GNSS Positioning algorithms under moderate ionospheric scintillation conditions. By assessing correlations existing between specific ISMR data and classic GNSS observations, the method could be extended to a more general usage which would be independent of ISMR measurements. [less ▲]

Detailed reference viewed: 51 (13 ULg)
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See detailEntrepreneuriat collectif : Quand entreprendre socialement se conjugue au pluriel
Dufays, Frédéric ULg

Conference given outside the academic context (2014)

Detailed reference viewed: 17 (2 ULg)
See detailBattista Guarino, ‘Sermone del cane e del cavallo’. Un testo inedito alla corte d’Este
Valenti, Gianluca ULg

Conference given outside the academic context (2014)

Detailed reference viewed: 6 (2 ULg)
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See detailThe physical education teacher as a physical activity promoter: Current developments
Cloes, Marc ULg

Conference (2014, November 19)

The physical education teacher is considered as a cornerstone of the physical activity promotion in the schools. This presentation proposes answers to three questions: (1) Why to promote physical activity ... [more ▼]

The physical education teacher is considered as a cornerstone of the physical activity promotion in the schools. This presentation proposes answers to three questions: (1) Why to promote physical activity at school? (2) Why the PE teacher should play a central role? (3) How the PE teacher could play such role? In conclusion, it is important to remember that (1) PE teachers should become the cornerstones of the PA promotion at school; (2) They have to be involved in PE as well as in the other dimension of PA at school; (3) They have to collaborate (they are not alone), and; (4) Pre service and inservice PETE has to be adapted to show the way and change the mentalities [less ▲]

Detailed reference viewed: 16 (1 ULg)