Welding and Research Center
Welding and Research Center
Boucherma D.,Welding and Research Center |
Charef A.,University of Mentouri Constantine |
Nezzari H.,Welding and Research Center
International Journal of Dynamics and Control | Year: 2017
In a previous work, we have derived the general solution of the state space linear fractional system of commensurate order for real simple and multiple eigenvalues of the state space matrix. The obtained solutions of the homogeneous and non-homogeneous cases have been expressed as a linear combination of introduced fundamental functions. In this paper, the above work has been extended to solve the state space linear fractional system of commensurate order for complex eigenvalues of the state space matrix. First, suitable fundamental functions corresponding to the different types of complex eigenvalues of the state space matrix are introduced. Then, the derived formulations of the resolution approach are presented for the homogeneous and the non-homogeneous cases. The solutions are expressed in terms of a linear combination of the proposed fundamental functions which are in the form of exponentials, sine, cosine, damped sine and damped cosine functions depending on the commensurate fractional order. The results are validated by solving an illustrative example to demonstrate the effectiveness of the proposed analytical tool for the solution of the state space linear fractional system of commensurate order. © 2015, Springer-Verlag Berlin Heidelberg.
Tala-Ighil N.,Welding and Research Center |
Fillon M.,University of Poitiers
Tribology International | Year: 2015
Journal bearing characteristics modellization has been investigated in this paper for both cases of texture presence or absence onto the bearing surface. The thermal effect has been studied. The used numerical approach in this analysis is finite difference method. The textured bearing performance enhancement passes essentially by a minimum film thickness and a friction torque improvement through an appropriate surface texture geometry and right texture distribution on the bearing surface. It is found that the simulations results are in good concordance with those issued from the literature. The obtained results by considering the temperature effect are more realistic. © 2015 Elsevier Ltd. All rights reserved.
Benammar A.,Welding and Research Center |
Benammar A.,Blida University |
Drai R.,Welding and Research Center |
Guessoum A.,Blida University
Ultrasonics | Year: 2014
Interference noising originating from the ultrasonic testing defect signal seriously influences the accuracy of the signal extraction and defect location. Time-frequency analysis methods are mainly used to improve the defects detection resolution. In fact, the S-transform, a hybrid of the Short time Fourier transform (STFT) and wavelet transform (WT), has a time frequency resolution which is far from ideal. In this paper, a new modified S-transform based on thresholding technique, which offers a better time frequency resolution compared to the original S-transform is proposed. The improvement is achieved by the introduction of a new scaling rule for the Gaussian window used in S-transform. Simulation results are presented and show correct time frequency information of multiple Gaussian echoes under low signalto- noise ratio (SNR) environment. In addition, experimental results demonstrate better and reliable detection of close echoes drowned in the noise. © 2013 Elsevier B.V. All rights reserved.
Mekhalfa F.,Welding and Research Center |
Nacereddine N.,Welding and Research Center
Proceedings - 10th International Conference on Signal-Image Technology and Internet-Based Systems, SITIS 2014 | Year: 2014
In this paper, we present through the experimental study the use of support vector machines (SVMs) in the automatic classification of weld defects in radiographic images. SVM is a machine learning tool used for classification and regression and it is well known for binary classification, but there are many approaches for multiclass classification, the most popular are one versus all and one versus one. The performance of the proposed classification system is evaluated using hundreds of radiographic images representing four types of defects. The experimental results show that the SVM classifier is an efficient automatic weld defect classification algorithm and can achieve high accuracy percent and is faster than multilayer perceptron artificial neural network (MLP-ANN). © 2014 IEEE.
Chetih N.,Welding and Research Center |
Messali Z.,University of Bordj Bou Arréridj
3rd International Conference on Control, Engineering and Information Technology, CEIT 2015 | Year: 2015
This paper presents comparative study and experimentation of Algebraic Reconstruction Technique (ART) and Filter Back Projection (FBP). The ART and FBP methods are used to reconstruct the object from the X-ray projection. The process of creating back the object image from the Radon Transform of the object is known as Image Reconstruction. Image reconstruction is a famous and interesting field which comes under computed tomography. Computed Tomography is used for identifying the hidden or inner defects of objects. In this paper Algebraic Reconstruction technique and Filter Back Projection methods are implemented and the experimented results are compared using performance parameters for various test cases. Projections for the image reconstruction are calculated analytically by defining two phantoms: Shepp-Logan phantom head model and the standard medical image of abdomen. The original images are grayscale images of size 128 × 128, 256 × 256, respectively. © 2015 IEEE.
Abbas A.,Welding and Research Center
Journal of Physics: Conference Series | Year: 2014
The aim of this work is to develop analytical models for the thermodynamic equilibrium at the interfaces (gas mixture / Quarz Micro Balance sensor arrays based on conducting polymers). Differential equations, which describe the change in the partial sensitivities of the sensor array elements depending on the gas mixture components concentrations, and the sensor array parameters, have been developed. Moreover, the responses of the sensor array as a function of the concentrations of the gas mixture components have been modeled. © Published under licence by IOP Publishing Ltd.
Salah B.,Welding and Research Center |
Slimane Z.,Welding and Research Center |
Zoheir M.,Welding and Research Center |
Jurgen B.,TU Bergakademie Freiberg
Measurement: Journal of the International Measurement Confederation | Year: 2015
This paper is concerned with a method for uncertainty evaluation of mechanical properties in metal testing. This method uses a combined approach based on Monte Carlo simulation and Markov Chain (MCMC) as a computing procedure of different uncertainties of mechanical and metallurgical parameters such as stress, and elongation. The MCMC is a stochastic method that computes the statistical properties of the considered states such as the probability distribution function (PDF) according to the initial state and the target distribution using Metropolis-Hasting (MH) algorithm. Conventional approach is based on the Guide of Uncertainty Measurement (GUM), the uncertainty budget is established for the stress and elongation parameters respectively. A comparative study between the conventional procedure and the proposed method is given. This kind of approaches is applied for constructing an accurate computing procedure of uncertainty measurement of mechanical and metallurgical parameters. © 2014 Elsevier Ltd. All rights reserved.
Attoui I.,Welding and Research Center |
Omeiri A.,Annaba University
Energy Conversion and Management | Year: 2014
In this paper, a contribution to modeling and fault diagnosis of rotor and stator faults of a Self-Excited Induction Generator (SEIG) in an Isolated Wind Energy Conversion System (IWECS) is proposed. In order to control the speed of the wind turbine, while basing on the linear model of wind turbine system about a specified operating point, a new Fractional-Order Controller (FOC) with a simple and practical design method is proposed. The FOC ensures the stability of the nonlinear system in both healthy and faulty conditions. Furthermore, in order to detect the stator and rotor faults in the squirrel-cage self-excited induction generator, an on-line fault diagnostic technique based on the spectral analysis of stator currents of the squirrel-cage SEIG by a Fast Fourier Transform (FFT) algorithm is used. Additionally, a generalized model of the squirrel-cage SEIG is developed to simulate both the rotor and stator faults taking iron loss, main flux and cross flux saturation into account. The efficiencies of generalized model, control strategy and diagnostic procedure are illustrated with simulation results. © 2014 Elsevier Ltd. All rights reserved.
Bouhouche S.,Welding and Research Center
Intelligent Systems Reference Library | Year: 2015
Quality management and control is a basic and important activity needed along the production process. From raw material to the final product, quality control and testing need an online measurement, control, evaluation and management. Generally, the management system is based on continuous measurements and improvement which is affected by several factors such as environmental perturbations and physical constraints. Methods and techniques of modeling and identification based on the first principle, black and gray box models are widely used. Because the systems are complex such as the mechanical testing where complex effects and interactions take place, it is strongly recommended to use a data driven empirical model. Such a model is based on the analysis of interactions between variables, data exploration, and modeling. The quality management of engineering process is a complex system defined by multivariate interactions between products and processes, where several factors such as the structure and others parameters must be processed to obtain a reliable model for online prediction of the quality behavior of the considered elements. In this work, new methods and techniques will be considered, essentially based on the intelligent approach such as the monitoring of the quality indexes—based model. These approaches are applied to quality monitoring and management of iron and steel products and processes. To give an optimal and a certified or accredited system, intelligent methods and techniques are strongly recommended. The objective of this chapter is to give the main principles of the management of engineering system—based intelligent methods. © Springer International Publishing Switzerland 2015.
Abdessalem B.,Welding and Research Center |
Redouane D.,Welding and Research Center |
Ahmed K.,Welding and Research Center |
Lyamine D.,Welding and Research Center |
Farid C.,Welding and Research Center
Physics Procedia | Year: 2015
In this paper, we apply a new technique for the ultrasonic phased array signal enhancement. It is based on the threshold modified S-transform (TMST). The signal processing algorithms generally give very satisfactory results on synthetic signals verifying the implicit or explicit hypotheses on which they are constructed. The obtained performances on the real signals can be however different radically. Time-frequency analysis methods are mainly used to improve the defects detection resolution. Significant performance enhancement is confirmed when the proposed approach is tested with the simulation of the B-scan signals contain a closer delamination to the front face. The experimental results show that the TMST Algorithm can enhance the quality of image provided by composite materials contained delamination defect. © 2015 The Authors.