Sensor fault detection and isolation filter for polytopic LPV systems: A winding machine application

In this paper, a fault diagnosis method is developed for a particular class of nonlinear systems described by a polytopic linear parameter varying (LPV) formulation. The main contribution consists in the synthesis of an accurate fault detection and isolation (FDI) filter and also a sensor fault magnitude estimation with a quality factor. This quality factor of the filter underlines if the fault estimation can be used or not. Stability conditions of the polytopic LPV filter are studied by ensuring poly-quadratic stability with Linear Matrix Inequality (LMI) representation. The effectiveness of this global FDI scheme through LPV modelization, filter design and stability analysis, is illustrated on a real winding machine under multiple sensor faults.     

Influence of stirring conditions on hard anodising of aluminium A6061-T6 shapes

Hard anodising is used to produce relatively thick and adherent coatings in order to improve the hardness, abrasion and corrosion resistance of aluminium components. In typical industrial conditions, the local variation of anodic oxide film thickness is often significant and it affects the dimensional tolerances and reliability of coating thickness. Electrolyte stirring is a simple and effective way to improve the uniformity of the oxide layer thickness. However, very little practical information is available in the literature to guide industry in this regard. In this work, extruded A6061-T6 specimens were anodised in industrial conditions. To reduce the thickness variability of the coating, three methods of electrolyte stirring were studied and compared. Air bubble stirring showed the best coating thickness uniformity and improved control over anodising parameters. However it did not reduce the variability due to metal forming texture.

On utilise l’anodisation dure afin de produire un revêtement d’oxyde épais et adhérent à la surface de pièces en alliage d’aluminium. Ce revêtement accroît la dureté, la résistance à l’abrasion et la résistance à la corrosion des composantes. En milieu industriel, l’épaisseur de la couche d’oxyde a tendance à varier en fonction de la position dans la cellule et même d’un endroit à l’autre sur une pièce, ce qui réduit la précision dimensionnelle. L’agitation de l’électrolyte dans la cellule est un moyen simple et efficace d’améliorer l’uniformité de l’épaisseur du revêtement. Toutefois, très peu d’information est disponible dans la littérature pour guider les industriels et déterminer dans quelle mesure l’agitation permet de réduire cette variabilité. Dans ce travail, des composantes extrudées en alliage A6061-T6 ont été anodisées en milieu industriel. Afin de réduire la variabilité de l’épaisseur de la couche anodisée, trois types d’agitation d’électrolyte dans la cellule ont été étudiés et comparés. L’agitation par bulles d’air a permis d’obtenir la meilleure uniformité de l’épaisseur de la couche anodisée et le meilleur contrôle sur les paramètres d’anodisation. Toutefois, les résultats montrent aussi que l’agitation accentue la différence d’épaisseur de la couche anodisée occasionnée par la texture de laminage ou d’extrusion.     

A New PSO-based Algorithm for Two-Dimensional Non-Guillotine Non-Oriented Cutting Stock Problem

In this paper, a new algorithm is proposed for the two-dimensional non-guillotine non-oriented cutting stock problem. The considered problem consists of cutting small rectangular pieces of predetermined sizes from large but finite rectangular plates. The objective is to generate cutting patterns that minimize the unused area and fulfill customer orders. The proposed algorithm is a combination of a new particle swarm optimization approach with a heuristic criterion inspired from the literature. The algorithm is tested on twenty-two instances divided into two sets. Corresponding results show the algorithm efficiency in optimizing the trim loss that is comprised between 2.6% and 7.8% for all considered instances.     

Adaptive noise-reducing anisotropic diffusion filter

In image processing and computer vision, the denoising process is an important step before several processing tasks. This paper presents a new adaptive noise-reducing anisotropic diffusion (ANRAD) method to improve the image quality, which can be considered as a modified version of a speckle-reducing anisotropic diffusion (SRAD) filter. The SRAD works very well for monochrome images with speckle noise. However, in the case of images corrupted with other types of noise, it cannot provide optimal image quality due to the inaccurate noise model. The ANRAD method introduces an automatic RGB noise model estimator in a partial differential equation system similar to the SRAD diffusion, which estimates at each iteration an upper bound of the real noise level function by fitting a lower envelope to the standard deviations of pre-segment image variances. Compared to the conventional SRAD filter, the proposed filter has the advantage of being adapted to the color noise produced by today’s CCD digital camera. The simulation results show that the ANRAD filter can reduce the noise while preserving image edges and fine details very well. Also, it is favorably compared to the fast non-local means filter, showing an improvement in the quality of the restored image. A quantitative comparison measure is given by the parameters like the mean structural similarity index and the peak signal-to-noise ratio.     

Effect of Sn2O3 doping on structural,optical and dielectric properties of ZnO ceramics

The synthesis of the undoped ZnO and ZnO–Sn₂O₃ composites prepared by conventional solid-state reaction method has been reported. Besides, the effect of increasing Sn₂O₃ content from 5 to 15 wt% on structural, optical, dielectric and electrical properties of the ZnO–Sn₂O₃ composites has also been investigated. In fact, the X-ray diffraction analysis indicates that the as-prepared ZnO–Sn₂O₃ composites may contain some combined phases such as SnO and Zn₂SnO₄. The atomic force microscopy shows that the surfaces of the composites are rough. The band gap energy seems to depend on the amount of Sn₂O₃ addition, with the maximum obtained at 15 wt% Sn₂O₃. Concerning the optical band gap, it has been found to be in the range of 3.18–3.93 eV. The dielectric loss was found to decrease with the increase in frequency. The results obtained from the ac-conductivity revealed that the values of σ(ω) increases with the Sn₂O₃ adding content. The dc-conductivity of all the composites increases with the increase in temperature. The electrical conductivity was analyzed with the power law, and agrees with the correlation barrier hopping model.     

Hybrid hexahedral element for solids,plates, shells and beams by selective scaling

A robust two-field hexahedral element capable of handling plate/shell, beam and nearly incompressible material analyses without locking are presented. Starting with the assumed stress element of Pian and Tong,⁷ parasitic strain components leading to locking in plate, shell and beam analyses are first identified. Locking can be alleviated by scaling down selectively the parasitic strain components in the leverage matrix. Unfortunately, the element then fails the patch test. However, patch test correction and reduction in computation can be achieved by the recently proposed admissible matrix formulation. The resulting element is lock-free and very efficient. All matrices involved in constructing the stiffness matrix can be derived explicitly. The accuracy of the element is tested by popular bench-mark problems.     

Deep and Handcrafted Feature Fusion for Automatic Defect Detection in Quadratic Frequency Modulated Thermal Wave Imaging

Russian Journal of Nondestructive Testing - Recent advancements of nondestructive testing and evaluation (NDT&E) with machine learning, artificial intelligence, and the internet of things...     

The behaviour of iron electrode in CO2− saturated neutral electrolyte—I. Electrochemical study

The properties of iron electrode in CO₂-saturated sodium chloride supporting electrolyte were investigated by cyclic voltammetry of static and rde-Ferrovac electrode in the potential region from ?1.1 to ?0.3 V (nhe). In addition to the reduction of H₃O⁺ ions formed due to the protolysis of carbonic acid, the direct (activated) reduction of both H₂CO₃ molecules and HCO^?₃ ions was observed. It is proposed that catalytic, E_rC′_i mechanism accounts for the occurrence of the latter processes.     

Electrodissolution de la galène en présence d'une induction magnétique inhomogéne

Résumé La polarisation anodique des sulfure de plomb en présence et en l'absence d'un champ magnétique a été étudiée en milieu d'acide chlorhydrique 1 mol dm^–3 à la temperature ambiante. Le courant anodique est sensible à la présence d'un champ magnétique inhomogène. Les études potentiocinétique et potentiostatique concernant l'influence de l'induction magnétique sur le courant montrent un comportement différent suivant la magnitude du champ. En choisissant certaines conditions expérimentales, le courant stationnaire à potentiel imposé peut être multiplié par un facteur de 1.5–1.8.

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The anodic polarisation of lead sulphide with and without a magnetic field has been studied in hydrochloric acid medium, 1 mol dm^–3, at ambient temperature. The anodic current is sensitive to the presence of a heterogeneous magnetic field. The potentiodynamic and potentiostatic studies concerning the influence of the magnetic induction on the current show a different behaviour for different magnitudes of the field. In choosing certain experimental conditions, the stationary current at an imposed potential can be multiplied by a factor of 1.5–1.8.

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On leave from Laboratoire d'Electrochimie, Université de Reims, BP 347-51062 Reims Cédex, France. Visiting Professor at l'Université Laval in 1981.