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Nombre total de résultats : 1902
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Scale space Radon transform

Djemel Ziou, Nafaa Nacereddine, Aicha Baya Goumeidane  (2021)

An extension of Radon transform by using a measure function capturing the user need isproposed. The new transform, called scale space Radon transform, is devoted to the casewhere the embedded shape in the image is not ?liform. A case study is brought on a straightline and an ellipse where the SSRT behaviour in the scale space and in the presence of noiseis deeply analyzed. In order to show the effectiveness of the proposed transform, the exper-iments have been carried out, ?rst, on linear and elliptical structures generated syntheticallysubjected to strong altering conditions such blur and noise and then on structures imagesissued from real-world applications such as road traf?c, satellite imagery and weld X-rayimaging. Comparisons in terms of detection accuracy and computational time with well-known transforms and recent work dedicated to this purpose are conducted, where theproposed transform shows an outstanding performance in detecting the above-mentionedstructures and targeting accurately their spatial locations even in low-quality images. Voir les détails

Mots clés : radon transform, line, ellipse, scale space, noise

Segmentation of x-ray image for welding defects detection using an improved Chan-Vese model

Rabah ABDELKADER, Naim Ramou, Mohammed Khorchef, Nabil CHETIH, Yamina BOUTICHE  (2021)

The welding defects detection in industries is becoming an important area and is attracting the attention of many researchers. Radiography is one of the most widely used techniques for inspecting weld defects. X-ray images are generally characterized by low contrast, poor quality and uneven illumination, so the extraction of weld defects could become a difficult task. Among the techniques most used in this field, it is the active contour and the main problem of this technique is the initial contour selection. To solve this problem and obtain reliable and efficient detection of welding defects, we propose in this work a new approach for welding defects detection from x-ray image based on an improved Chan-Vese model. This improved model is based on three stages. The first stage is the detection the region of interest. In the second stage, we apply the Fuzzy C-Mean (FCM) algorithm to select one of the clusters as the initial contour. In the third stage, we use the Chan-Vese model and the selected initial contour to segment the acquired images and obtain the boundaries of the weld defects. Experiments are carried out on different x-ray welding images of the GDxray database in order to extract the characteristics of the welding defects. The results obtained show the effectiveness of the proposed approach compared to conventional techniques. Voir les détails

Mots clés : Chan-Vese model Fuzzy, C-means clustering, X-ray image, Welding defects

L'effet de l'incorporation de Zn sur les propriétés physiques des couchesminces CdS pour cellules solaires de type (Cd, Zn) S/Cu2SnZnS4

ZELLAGUI Rahima (2021)
Thèse de doctorat

Le but de ce travail est la réalisation des couches minces CdS par la technique Bain chimiquepour l’application photovoltaïque (cellule solaire). En effet, le cadmium est un élémenthautement cancérigène qui bien que présent en très faible quantité en tant que couche tamponet pouvant être recyclé en fin de vie des panneaux, Enfin, au niveau industriel, la synthèse dece composé s’effectue par CBD et entraine une rupture du vide sur la chaine de production,ainsi que des coûts occasionnés par le stockage de réactifs dangereux (cadmium, thiourée,ammoniaque) et le traitement des déchets toxiques pour cela on fait l'étude de l'effet del'incorporation de Zn sur les propriétés physiques des couche minces CdS pour cellules solairede type (Cd, Zn) S/ Cu(Sn, Zn)S2.Des couches minces de CdxZn1-xS ont été déposées sur des substrats en verre par uneméthode chimique simple et économique, c'est-à-dire le dépôt chimique en bain (CBD), pourleurs applications potentielles dans le photovoltaïque. Les propriétés structurales,morphologiques, chimiques et optiques des couches minces déposéesont été étudiées pardiffraction des rayons X, microscopie électronique à balayage, UV-VIS et spectrométrieRaman. Les propriétés structurelles ont révélé que les couches minces déposées présentent à lafois des structures cristallines hexagonale et cubique. Les films minces CdxZn1-xS avec unegranulométrie comprise entre 6 et 25 nm et présentent une transmittance de 50 à 80% dans larégion visible. L'énergie de bande interdite optique de la couche mince déposée se situaiententre 2,6 et 3,6 eV, illustrant leur viabilité potentielle pour dispositifs optoélectroniques etphotovoltaïques. Voir les détails

Mots clés : couche mince, Bain Chimique(CBD), CdZnS, morphologie, propriétés Optique

Tamanrasset’s Clay Characterization and Use as Low Cost, Ecofriendlyand Sustainable Material for Water Treatment: Progress and Challengein Copper Cu (II)

Aicha Kourim1, Moulay Abderrahmane Malouki2, Aicha Ziouche3, Mouna Boulahbal4, d and Madjda Mokhtari5  (2021)

In this study, the adsorption of copper Cu (II) from aqueous solution, on Tamanrasset’sclay which is low cost adsorbent, was studied using batch experiments. The adsorption study includesboth equilibrium adsorption isotherms and kinetics. The characterization of the adsorbent necessitatedseveral methods such as X-Ray Diffraction, Scanning Electron Microscopy coupled with EnergyDispersive X-ray, BET for specific surface area determination, Fourier transform infraredspectroscopy and thermogravimetric analysis. Indeed, various parameters were investigated such ascontact time, initial metal ion concentration, mass of solid, pH of the solution and temperature. Theadsorption process as batch study was investigated under the previews experimental parameters. Theresults revealed that the adsorption capacity of Cu2+ is maximized at naturel pH of metal 5.5. Removalof copper by the clay of Tamanrasset (kaolinite) achieved equilibrium within 50 minutes; the resultsobtained were found to be fitted by the pseudo-second order kinetics model. The equilibrium processwas well described by the Langmuir model and the maximum adsorption capacity was found to be26.59 mg/g. Voir les détails

Mots clés : adsorption, Clay, copper, kinetic, Isotherms

First principal investigation of structural, morphological, optoelectronic and magnetic characteristics of sprayed Zn: Fe2O3 thin films

Rihab BenAyed, MejdaAjili, Jorge M.Garcia, AichaZiouche, Jose Luis CostaKramer, Najoua KamounTurki  (2020)

Undoped and Zn-doped Fe2O3 thin films were grown through spray pyrolysis. Zinc doping effect on the physical properties was investigated in detail. X-ray diffraction analysis confirms that all the Fe2O3 thin films showed a rhombohedral structure. The surface morphological study shows an interesting dendrite structure. The estimated band gaps energies were increased from 2.13 to 2.21 eV for indirect transition and from 1.80 to 1.85 eV for direct transition as function of doping ratio which was increased from 2 to 8 at. % Zn. The resistivity value (ρ) of un-doped Fe2O3 thin film is 6.06 × 104 Ω. cm and as adding Zn ions, ρ consequently decreased to 52 Ω. cm for 6 at. % Zn-doped Fe2O3 thin films. Vibrating sample magnetometer (VSM) measurements showed an increase of the saturation magnetization with the Zn2+ insertion. Further, a ferromagnetic behavior was observed. Voir les détails

Mots clés : Ferromagnetic, semiconductor, Fe2O3, Zinc doping, Low resistivity

Unraveling the effect of Bi2S3 on the optical, electrical and magnetic properties of γ-MnS-based composite thin films

Z.Amara, M.Khadraoui, R.Miloua, A.Boukhachem, A.ZIOUCHE  (2020)

(Bi2S3)x (γ-MnS)1-x composite thin films have been deposited onto glass substrates using spray pyrolysis method. The structural and compositional investigations confirmed the co-existence of Bi2S3 and γ-MnS binary compounds in the thin films. The surface morphology indicated that the increase in Bi2S3 concentration influences both the shape and the size of γ-MnS crystallites. The optical analysis via transmittance and reflectance measurements revealed that the band gap energy Eg decreased from 3.29 eV to 1.5 eV in terms of Bi2S3 content. The electrical parameters such as resistivity ρ, mobility μ, carrier concentrations and Hall coefficient have been obtained by Hall Effect measurements. It is found than incorporation of Bi2S3 enhances the conductivity, and p-type conduction of γ-MnS could be converted to n-type at x = 0.5. The vibrating sample magnetometer measurement has revealed that (Bi2S3)x (γ-MnS)1-x composite thin films have a ferromagnetic behavior at room temperature. Voir les détails

Mots clés : γ-MnS, Bi2S3, Spray pyrolysis, Magnetic Properties

Investigation of some physical properties of pure and Co-doped MoO3 synthesized on glass substrates by the spray pyrolysis method

N.Benameur, M.A.Chakhoum, A.Boukhachem, M.A.Dahamni, A.ZIOUCHE  (2019)

Pristine and Cobalt (Co)-doped MoO3 nanofilms were synthesized on glass substrates using the spray pyrolysis method. The nanometric pristine MoO3 films were prepared from the 10−2 M.L-1 solution of ammonium molybdate tetrahydrate [(NH4)6Mo7O24,4H2O] in distilled water. Co-doping at 0.5, 0.75 and 1% was achieved by adding cobalt (II) chloride hexahydrate (Cl2CoH12O6) in the pristine solution. The structure and the morphology of the films were investigated by means of X-ray diffraction and atomic force microscopy: two pronounced (020) and (040) peaks corresponding to the orthorhombic structure phase of α-MoO3 were detected. The AFM observations revealed the formation of micro-plates, parallel to the surface plane, with a roughness ranging from 33?nm to 54?nm. Optical properties were investigated through reflectance, transmittance and photoluminescence measurements. The optical band gap, the Urbach energy and the refractive index were deduced from these measurements. The presence of oxygen vacancies was revealed from the interband transitions in the blue and green domains. Co-doped MoO3 nanofilms showed ferromagnetic behavior. The photocatalytic degradation of an aqueous solution of methylene blue (MB) under UV irradiation, in the presence of Co-MoO3 nanomfilms, has been carried out using UV–vis spectrometery: the intensity of the absorption peak recorded at 660?nm decreased with the increase of the UV-illumination time while the color of the initial MB solution was drastically waned. Voir les détails

Mots clés : Spray pyrolysis method, MoO3 nanofilms, optical properties, Magnetic Properties

Tool combination for the description of steel surface image and defect classification

Zoheir MENTOURI, Hakim DOGHMANE, Kaddour Gherfi, Rachid Zaghdoudi, Hocine Bourouba  (2021)
Article de conférence

In industry, the automatic recognition of surface defects of flat steel products still represents a real challenge. Indeed, in addition to constraints such as the image noise or blur, there is neither an agreed standard of these defects nor a standard method that can ensure the defect identification, whatever are their size, shape, orientation and location. Thus, the complexity of the algorithm that deals with this matter always depends on specific needs of the application. In this paper, we give details on an approach that combines Gabor wavelets (GW) and the local phase quantization technique (LPQ), to describe the steel surface images, and uses the histogram to extract their characteristics. The defect classification is carried out by means of two classifiers, namely the nearest neighbors and the support vector machine. The method assessment is based on testing different parameter values of the used tools. The approach shows a good performance in terms of recognition rates and feature vector length, which impacts the computing time. Also, the study reveals its suitability for an online steel surface defect recognition application. Voir les détails

Mots clés : Quality control, Computer vision, metal surface imaging, Filter bank application, pattern analysis and recognition

Surface Flaw Classification Based on Dual Cross Pattern

Zoheir MENTOURI, Hakim DOGHMANE, Abdelkrim Moussaoui, Djalil BOUDJEHEM  (2020)
Article de conférence

The evaluation of flat steel surface quality is mainly concerned with detecting and identifying product surface defects. Although the variety of the implemented techniques, this type of control still presents a challenge. In this paper, we assess the Dual Cross Pattern technique, as a feature descriptor, that should be quite discriminative, to ease the steel surface defect classification. The histograms extracted from the captured DCP features are concatenated to represent the global image feature vector. The procedure parameters, as the DCP circle radius, the number of the training images and their choice, are considered to show their impact on the results. The experiment conducted on the NEU published defect database shows that, compared to the other used techniques, the proposed approach reveals not only interesting recognition rates but presents advantages in time coast too. Voir les détails

Mots clés : Image description, pattern recognition, Product quality, steel surface defects, hot rolling process

Steel Strip Surface Defect Identi?cation using MultiresolutionBinarized Image Features

Zoheir MENTOURI, Abdelkrim Moussaou, Djalil BOUDJEHEM, Hakim DOGHMANE  (2020)

The shaped steel strip, in the hot rolling process,may exhibit some surface ?aws. Their origin could bethe internal discontinuities in the input product or thethermomechanical transformation of the material, duringthe shaping process. Such defects are of a random occurrenceand may lead to costly rework operations or to adowngrading of the ?nal product. So, they should bedetected and identi?ed as soon as possible, to allow atimely decision-making. For such a quality monitoring, theused vision systems are mainly based on an imagedescription and a reliable classi?cation. In this paper, weexplore pre-de?ned image ?lters and work on a procedureto extract a discriminant image feature, while realizing thebest trade-off between the improved recognition rate of thesurface defects and the computing time. The proposedmethod is a multiresolution approach, based on theBinarized Statistical Image Features method, employed todate in biometrics. The ?lters, pre-learnt from naturalimages, are applied to steel defect images as a new surfacestructure indicator. They provide a quite discriminating image description. A relevant data reduction is used togetherwith a classi?er to allow an ef?cient recognition rate ofthe defective hot rolled products. Voir les détails

Mots clés : Computer vision, statistical features, Classi?cation, strip surface defects, hot rolling process