Sensitivity analysis of a sound absorption model with correlated inputs

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Acoustic characterization of air saturated porous materials at audible frequencies

International audienceAn acoustic method based on sound transmission is proposed for measuring the viscous and thermal permeability, viscous and thermal tortuosity, and porosity of porous materials having a rigid frame at low frequencies. The proposed method is based on a temporal model of the direct and inverse scattering problems for the propagation of transient audible frequency waves in a homogeneous isotropic slab of porous material having a rigid frame. The acoustic parameters are determined from the solution of the inverse problem. The minimization between experiment and theory is made in the time domain. Tests are performed using industrial plastic foams

Reliability modeling and prediction of passive controlled structures through Random Forest

Reliability prediction plays a significant role in risk assessment of engineering structures. Mathematically, the prediction task can be seen as a classification (regression) procedure. In this aspect, machine learning methods have recently shown their superior performance over others in various research domains. Random forest (RF) is distinguished for its robustness and high accuracy in modeling and prediction work. However, its application in the area of structural reliability has not been widely explored. This study aims to explore the feasibility of RF as well as examine its performance in modeling and prediction of structure reliability in passive control mode. A numerical example is introduced in the simulation part to evaluate performance of the proposed method in different perspectives

ON THE STRUCTURAL CHARACTERIZATION THROUGH K-SPACE METHODS: ASSESSMENTS AND VALIDATIONS

International audienceThe physical characteristics of periodic structures are employed to analyze the vibro-acoustic response of several complex structures in the wavenumber domain. This work is fo-cused on the analysis of elastic periodic structures, designed in order to obtain a wave atten-uation in certain frequency bands, generating the so-called band-gaps (mainly related to the Bragg's effect), and on the identification of the material properties of complex structures. In this context, an inverse wavenumber correlation method is developed to obtain the dispersion characteristics and the damping information of complex periodic structures. The wavenumbers and the damping loss factor are identified exciting the structure by a unit harmonic force and using the complete vibrational field as primary input

Measuring static thermal permeability and inertial factor of rigid porous materials

International audienceAn acoustic method based on sound transmission is proposed for deducing the static thermal permeability and the inertial factor of porous materials having a rigid frame at low frequencies. The static thermal permeability of porous material is a geometrical parameter equal to the inverse trapping constant of the solid frame [Lafarge et al., J. Acoust. Soc. Am. 102, 1995 (1997)] and is an important characteristic of the porous material. The inertial factor [Norris., J. Wave Mat. Interact. 1, 22 365 (1986)] describes the fluid structure interactions in the low frequency range (1-3 kHz). The proposed method is based on a temporal model of the direct and inverse scattering problems for the propagation of transient audible frequency waves in a homogeneous isotropic slab of porous material having a rigid frame. The static thermal permeability and the inertial factor are determined from the solution of the inverse problem. The minimization between experiment and theory is made in the time domain. Tests are performed using industrial plastic foams. Experimental and theoretical data are in good agreement. Furthermore, the prospects are discussed. This method has the advantage of being simple, rapid, and efficient

Tailoring of carboxyl-decorated magnetic latex particles using seeded emulsion polymerization

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Reactive magnetic poly(divinylbenzene-co-glycidyl methacrylate) colloidal particles for specific antigen detection using microcontact printing technique

International audienceEpoxy-functionalized magnetic poly(divinylbenzene-co-glycidyl methacrylate) colloidal particles (mPDGs) were prepared by co-polymerization of 1,4-divinylbenzene and glycidyl methacrylate monomers. The reaction was conducted by batch emulsion polymerization in the presence of an oil in water magnetic emulsion as a seed. The chemical composition, morphology, iron oxide content, magnetic properties, particle size and colloidal stability of the prepared magnetic polymer particles were characterized using Fourier transform infrared spectroscopy, transmission electron microscopy, thermal gravimetric analysis, vibrating sample magnetometry, dynamic light scattering, and zeta potential determination, respectively. The prepared mPDGs were immobilized on a self-assembled monolayer of 3-aminopropyltriethoxysilane (APTES)/octadecyltrichlorosilane (OTS), which were patterned on glass using microcontact printing technique, forming mPDGs-APTES/OTS reactive surface. This construction (mPDGs-APTES/OTS) was used as a solid support for immunoassay. The immobilized magnetic particles were bioconjugated with monoclonal anti-human IL-10 antibody to provide specific and selective recognition sites for the recombinant human IL-10 protein (antigen). Fluorescence microscopic examination was carried out to follow this immunoassay using fluorescently labeled anti-human IL-10 antibody. The results obtained proved the successful use of mPDGs-APTES/OTS microcontact printed surfaces in an immunoassay, which can be exploited and integrated into microsystems in order to elaborate medical devices (e.g. biosensors) which could provide rapid analysis at high sensitivity with low volumes of analyte