Liste des communications
Surface Flaw Classification Based on Dual Cross Pattern
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
The importance of using dual-channel heterostructure in strained P-MOSFETs
We present in this work a dual-channel heterostructure strained structure, introduce the high carrier mobility Awaited in heterostructure devices while using several models which are: CVT, SHIRAHATA, and WATT, we present a two-dimensional simulation of dual strained channel heterostructure P-MOSFETs. This study is accomplished usingSILVACO-TCAD simulation software, the comparison of the effect of using strain technique on P-MOSFET transistors will demonstrate the importance of using strain technique especially in dual channel heterostructure MOSFET. The simulation of fabrication steps and the extraction of the electronic proprieties in terms of transfer and output characteristics, transconductance, and the quasi-static capacitance allow understanding and interpreting these enhancements Voir les détails
Mots clés : Strained Silicon, SiGe layer, MOSFET; Heterostructure, simulation, Silvaco
Optimization of the number of layers for a fixed thickness of a composite material subjected to compression loading
In this paper, the effect of varying the number of layers for a fixed total thickness is investigated. In order to conserve the integrity and the safety of a multilayers composite structure, the search of the optimal number of layers in the cross section, induced the low stress-strain field intensity, is strongly recommended. Meanwhile, this study aims to show how the mechanical response of a multilayers composite plate loaded on a compression in the axial direction, changes when the number of layers increases from for a fixed total thickness. Voir les détails
Mots clés : security factor, stress-strain field, Composite material, Compression loading
Electronic Properties of Carbon Nanotubes
Theoretical calculations predicted that carbon nanotubes were to present a metal behavior or semiconductor following their diameter and their chirality, these properties of conduction have inherited the structure of a particular band of graphite. Consequently, a limited number of wave vectors are allowed in this direction, It depends on the diameter and the winding of the graphene sheet on itself. If the edge conditions include the corners of the Brillouin zone, the behavior of the nanotube is metallic, this is the case for all “chair” type nanotubes and a third of “chiral” and “zig-zag” nanotubes. In other cases, the band structure has a bandgap, as a first approximation, inversely proportional at the radius of the nanotube. In addition, STM makes it possible to image the atomic structure of nanotubes and therefore to determine their chirality and their diameter. The transport properties can thus be correlated with the structure of the nanotube, the nanotube would be thus a quantum prototype of wire to a dimension. The various measurements carried out by AFM and STM on nanotubes monofeuillets showed that they behave indeed like such. The possible applications of these properties come within the province of nanoelectronic, not only the use of the nanotube like a molecular discussion thread but also like an active electronic element. Voir les détails
Mots clés : Carbon Nanotubes;STM;AFM
Investigation of Properties of ZnO Nanostructures by First- Principals Calculations
Structural and microstructural properties were investigated by first-principals computing. The ZnO powder as Transparent Ceramics exhibited a hexagonal crystal structure with space group p63mc of ZnO. We applied the present first-principals approach to the electronic structure of the ZnO structures. Band structure and density of states of the phase of crystal ZnO computed using first principal methods, confirmed that pure ZnO is a direct band gap semiconductor when obtained in the B4 type structure phase. Voir les détails
Mots clés : ZnO;DFT; FP-LAPW
Electronic Properties of Graphene
Winding a graphene sheet around itself creates periodic boundary conditions, perpendicular to the nanotube axis. Therefore a limited number of wave vectors are allowed in this direction. It depends on the diameter and the winding of the graphene sheet on itself [1]. If the edge conditions include the corners of the Brillouin zone, the behavior of the nanotube is metallic. This is the case for all “chair” type nanotubes and a third of “chiral” [2] and “zig-zag” nanotubes. In other cases, the band structure has a band gap, as a first approximation, inversely proportional. at the radius of the nanotube. These properties have been confirmed experimentally by measuring the tunnel current between the tip of an STM (Tunnel Effect Microscope) and a nanotube, which provides a direct estimate of electron density. In addition, STM makes it possible to image the atomic structure of nanotubes and therefore to determine their chirality and their diameter. The transport properties can thus be correlated with the structure of the nanotube. Metal nanotubes have only two one-dimensional conduction bands that cross the Fermi level: all current flows through these two bands and the theory predicts the conductance G0 = 2e2 / h, equal to twice the unit of fundamental conductance. Voir les détails
Mots clés : Graphene, STM, Nanotube
Comparative study of the corrosion behavior of the high strength steel after thermal and thermomechanical treatments
The corrosion behaviour of X80 steel samples rolled and other quench-tempered in 3.5% NaCl have been studied. Optical microscopy, scanning electron microscopy, potentiodynamic polarization tests and electrochemical impedance measurements are the techniques used to characterize the samples. The results show that the tempered steel has a low corrosion current density compared to the rolled steel. The impedance measurements show the presence of a single capacitive loop attributed to the load transfer phenomenon. Voir les détails
Mots clés : HSLA grade steel X80, corrosion, structure, thermomechanical treatment.
The Importance of Applying Artificial Intelligence on Unmanned Aerial Vehicle
Unmanned Aerial Vehicles (UAVs) are used in several applications and they are growing in popularity. Recent progress in unmanned aerial vehicles and artificial intelligence constitutes a new chance for an autonomous operation and flight. Nowadays, artificial intelligence and deep learning are driving the evolution of UAVs and fueling their autonomous future. Computer vision achieved very important progress in image classification and segmentation, and object detection, which make it very attractive research field when it is applied on unmanned aerial vehicle. Artificial intelligence is not only important and benefic, but can be rather, dangerous and serious matter since the UAVs learns through algorithms, and use that for future decision making. This work is a survey, where we present works, challenges and dangerous part of using artificial intelligence on UAVs. Voir les détails
Mots clés : UAV, machine learning, Artificial intelligence, System, Drone
Effect of the c-axis tilting angle in piezoelectric ZnO crystal on the performances of electroacoustic SAW sensors
This paper aims to study the effect of c-axis tilting angle of piezoelectric ZnO/Si on the performances of electroacoustic SAW sensors, the dispersion curves of phase velocity, the electromechanical coupling factor K² and sensitivity to mass loading of Rayleigh and Sezawa modes are studied for different hZnO/λ and for different c-tilting angles (0, θ, 90°). The effect of the tilting angle θ on the performances of electroacoustic devices, is studied by finite element analysis. Based on the obtained results, SAW device is fabricated onto a ZnO/SiO2/Si multilayered structure. The obtained results show best performances and high sensitivity to gas and will contribute in enhancing the sensitivity and performances of SAW electroacoustic devices. Voir les détails
Mots clés : surface acoustic waves, electroacoustic devices, Finite Element Analysis, Piezoelectric materials, c-tilted ZnO
Analytical Modeling of the Behavior of Composite Structure Subjected to Combined Tensile and Moment Loading
The present work is a contribution in assessment of the security factor of the structures made from composites materials in order to work within safe conditions. In the first step, a Matlab code is developed in order to develop a mechanical model able to predict the mechanical behavior of the high performance composite material without necessity to the expensive experimental test. In the second step, an analytical modeling is performed for the composite structure subjected to a tensile load in the longitudinal direction and a moment in the transversal direction in order to assess the strain and the stress fields in all layers of the composite material and evaluate the security factor in all plies. Meanwhile, the new mechanical model can be used as a tool decision in design and maintenance in order to check the integrity of the composite structure. Voir les détails
Mots clés : composite, laminate, integrity, security factor, moment loading