Compact and Highly Sensitive Bended Microwave Liquid Sensor Based on a Metamaterial Complementary Split-Ring Resonator

YesIn this paper, we present the design of a compact and highly sensitive microwave sensor based on a metamaterial complementary split-ring resonator (CSRR), for liquid characterization at microwave frequencies. The design consists of a two-port microstrip-fed rectangular patch resonating structure printed on a 20 × 28 mm2 Roger RO3035 substrate with a thickness of 0.75 mm, a relative permittivity of 3.5, and a loss tangent of 0.0015. A CSRR is etched on the ground plane for the purpose of sensor miniaturization. The investigated liquid sample is put in a capillary glass tube lying parallel to the surface of the sensor. The parallel placement of the liquid test tube makes the design twice as efficient as a normal one in terms of sensitivity and Q factor. By bending the proposed structure, further enhancements of the sensor design can be obtained. These changes result in a shift in the resonant frequency and Q factor of the sensor. Hence, we could improve the sensitivity 10-fold compared to the flat structure. Subsequently, two configurations of sensors were designed and tested using CST simulation software, validated using HFSS simulation software, and compared to structures available in the literature, obtaining good agreement. A prototype of the flat configuration was fabricated and experimentally tested. Simulation results were found to be in good agreement with the experiments. The proposed devices exhibit the advantage of exploring multiple rapid and easy measurements using different test tubes, making the measurement faster, easier, and more cost-effective; therefore, the proposed high-sensitivity sensors are ideal candidates for various sensing applications.This work was supported by the Moore4Medical project, funded within ECSEL JU in collaboration with the EU H2020 Framework Programme (H2020/2014–2020) under grant agreement H2020-ECSEL-2019-IA-876190, and the Fundação para a Ciência e Tecnologia (ECSEL/0006/2019). This project received funding in part from the DGRSDT (Direction Générale de la Recherche Scientifique et du Développement Technologique), MESRS (Ministry of Higher Education and Scientific Research), Algeria. This work was also supported by the General Directorate of Scientific Research and Technological Development (DGRSDT)–Ministry of Higher Education and Scientific Research (MESRS), Algeria, and funded by the FCT/MEC through national funds and, when applicable, co-financed by the ERDF, under the PT2020 Partnership Agreement under the UID/EEA/50008/2020 project

Experimental investigation of the flow over single and successive hills on smooth and rough walls

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Optimisation des paramètres du vecteur formé : application au diagnostic vibratoire automatise des défauts d'une boite de vitesse d'un hélicoptère

Les processus de détérioration des machines tournantes, qu'ils soient accidentels (rupture fragile d'un composant) ou résultant de l'usure normale des éléments mécaniques, sont en général très complexes. Toutefois, l'apparition d'une détérioration se traduit par une modification du comportement de la machine et en particulier une évolution des niveaux vibratoires. De ce fait, il existe plusieurs procédures de diagnostic de défauts. Le choix d'une approche est lié à la connaissance que l'on souhaite acquérir sur le système, mais aussi à la complexité de ce système. Les techniques de surveillance par reconnaissance de formes sont plus élaborées que les simples tests statistiques et sont capables de détecter et de diagnostiquer les défaillances d'une manière automatisée. Pour cela, il suffit d'extraire un vecteur de paramètres, appelé vecteur forme (VF), sur chacune des mesures effectuées sur la machine. La règle de décision utilisée permet de classer les observations décrites par le vecteur forme par rapport aux différents modes de fonctionnement connus avec ou sans défaut. Les travaux présentés dans cet article portent sur la sélection d'un nombre réduit de paramètres pertinents pour représenter les signatures vibratoires des défauts d'une boîte de vitesse CH-46 d'un hélicoptère de la marine américaine. Nous avons pu montrer que les performances des méthodes de reconnaissance de formes (RdF) sont étroitement liées à la pertinence des indicateurs de défauts

A new method for automatic defects detection and diagnosis in rolling element bearings using Wald test

To detect and to diagnose, the localized defect in rolling bearings, a statistical model based on the sequential Wald test is established to generate a “hypothetical” signal which takes the state zero in absence of the defect, and the state one if a peak of resonance caused by the defect in the bearing is present. The autocorrelation of this signal allows one to reveal the periodicity of the defect and, consequently, one can establish the diagnosis by comparing the frequency of the defect with the characteristic frequencies of the bearing. The originality of this work is the use of the Wald test in the signal processing domain. Secondly, this method permits the detection without considering the level of noise and the number of observations, it can be used as a support for the Fast Fourier Transform. Finally, the simulated and experimental signals are used to show the efficiency of this method based on the Wald test

Contribution of Angular Measurements in the Diagnosis of Gear Faults by Artificial Neural Networks

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Formulation of off-axis single reference beam and two angle views for digital holography

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Transport éolien hors équilibre

International audienceWe investigate the relaxation process toward the equilibrium regime of saltation transport in the context of nonuniform conditions. Relaxation phenomena can be described in terms of a characteristic length scale that measures the distance for the particle flux to adapt to a spatial change in flow or boundary conditions. We conducted wind tunnel experiments to document the influence of the upwind mass flux on the relaxation process. For zero upwind mass flux conditions, the relaxation process is monotone and the relaxation length is independent of the wind strength. In contrast, for nonzero upwind flux conditions (obtained by releasing particles in the flow from a finite height), the relaxation process is nonmonotone and is well captured by damped harmonic oscillations. Importantly, the relaxation length increases with increasing air flow velocity but is almost insensitive to the magnitude of the upwind flux. Our experimental outcomes clearly indicate that the relaxation of far from equilibrium transport regimes strongly deviates from a simple exponential behavior