Application of ARMAV models to identification and damage detection of mechanical and civil engineering structures

peer reviewedIn this paper, the application of auto-regressive moving average vector models to system identification and damage detection is investigated. These parametric models have already been applied for the analysis of multiple input-output systems under ambient excitation. Their main advantage consists in the capability of extracting modal parameters from the recorded time signals, without the requirement of excitation measurement. The excitation is supposed to be a stationary Gaussian white noise. The method also allows the estimation of modal parameter uncertainties. On the basis of these uncertainties, a statistically based damage detection scheme is performed and it becomes possible to assess whether changes of modal parameters are caused by, e.g. some damage or simply by estimation inaccuracies. The paper reports first an example of identification and damage detection applied to a simulated system under random excitation. The `Steel-Quake' benchmark proposed in the framework of COST Action F3 `Structural Dynamics' is also analysed. This structure was defined by the Joint Research Centre in Ispra (Italy) to test steel building performance during earthquakes. The proposed method gives an excellent identification of frequencies and mode shapes, while damping ratios are estimated with less accuracy

Immuno-Electron Microscopical Investigations with a New Tracer: Peroxidase-Labeled Protein A: Application for Detection of Pemphigus and Bullous Pemphigoid Antibodies

Peroxidase-labeled Protein A, a stable immunoenzyme tracer of high reactivity and comparatively low molecular weight, has been applied in immuno-electron microscopy for detection of bound IgG-type pemphigus and bullous pemphigoid antibodies. Comparing Protein A-peroxidase with peroxidase-labeled immunoglobulins, we obtained similar morphological results in corresponding incubation techniques, but lower nonspecific adsorption of Protein A-peroxidase complexes in tissues, The Protein A-peroxidase molecules showed good tissue penetration abilities. Our rapid one-step incubation procedure led to enhanced preservation of tissue fine structures, without the need of prior tissue fixation, It seems that Protein A-peroxidase is able to replace peroxidase-labeled anti-IgG for immuno-electron microscopical purposes

H. Eckert. Avoir vingt ans à l’usine

On pouvait parler, jusque dans les années 70-80, d’une « classe ouvrière », de par ses conditions sociales d’existence, ses pratiques culturelles, ses opinions, croyances, valeurs. Sans avoir recours aux sociologues, la « classe ouvrière » était bel et bien visible sur la place publique : cité ouvrière autour des usines, associations, parti politique représentatif, syndicat, luttes collectives ayant aboutit à de nombreux acquis en droit du travail... Qu’en est-il de nos jours ? La « classe ou..

La collaboration en traduction : objectifs et mode d’emploi

Si nombre de traducteurs travaillent seuls, un tel isolement n’est pas forcément propice à leur épanouissement professionnel. La mise en place d’un partenariat commercial entre traducteurs peut receler de multiples avantages, dont l’amélioration de la qualité des travaux, la possibilité d’approcher des clients à la recherche de traductions immédiatement publiables et une satisfaction professionnelle accrue. La collaboration régulière peut également accroître la productivité en facilitant l’ac..

Particle swarm optimization with sequential niche technique for dynamic finite element model updating

Peer reviewedPostprin

A gas-templating strategy to synthesize CZTS nanocrystals for environment-friendly solar inks

A high-temperature gas-templating strategy is proposed to synthesize Cu2ZnSnS4 (CZTS) nanocrystals for all-aqueous solar inks. Our gas templating process route involves the in-situ generation and stabilization of nanosized gas bubbles into a molten KSCN-based reaction mixture at 400 °C. Chemical insights of the templating gas process are provided such as the simultaneous formation of gas bubbles and CZTS nuclei highlighting the crucial role of the nucleation stage on the sponge and resulting nanocrystals properties. The high porosity displayed by the resulting CZTS nanocrystals facilitates their further post-fragmentation, yielding individualized nanocrystals. The advantages of our high temperature gas templating route are illustrated by the following: (i) the low defect concentration displayed by the highly crystalline nanocrystals, (ii) the synthesis of CZTS nanocrystals displaying S2− polar surfaces after ligand exchange. The good photoluminescence properties recorded on the pure CZTS nanocrystals reveal potential for exploration of new complex chalcogenide nanocrystals useful for various applications including photovoltaics and water splitting. Here we demonstrate that using these building blocks, a CZTS solar cell can be successfully fabricated from an environment-friendly all-aqueous ink

Modal Identification of the "Steel-Quake" Structure Using the Data-Driven Stochastic Subspace and ARMAV Methods

In this paper, two techniques used for modal identification of output-only systems are presented and compared. The first technique is based on an ARMAV model. The method is known as the prediction error method (PEM) and requires a non-linear iterative optimisation procedure. The second technique is a stochastic subspace method that estimates the system matrices of a stochastic state space model by a data-driven algorithm and by using numerical techniques such as singular value and QR decompositions. The comparison between both techniques is performed over the “Steel-Quake” benchmark proposed in the framework of COST Action F3 “Structural Dynamics”. The results show that the investigated techniques give good results in term of estimated modal parameters. Especially, it is found that the stochastic subspace technique is much faster than the PEM