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Khaldi K.,National Engineering School of Tunis | Boudraa A.-O.,Ecole Navale
IEEE Transactions on Audio, Speech and Language Processing | Year: 2013

In this paper a new adaptive audio watermarking algorithm based on Empirical Mode Decomposition (EMD) is introduced. The audio signal is divided into frames and each one is decomposed adaptively, by EMD, into intrinsic oscillatory components called Intrinsic Mode Functions (IMFs). The watermark and the synchronization codes are embedded into the extrema of the last IMF, a low frequency mode stable under different attacks and preserving audio perceptual quality of the host signal. The data embedding rate of the proposed algorithm is 46.9-50.3 b/s. Relying on exhaustive simulations, we show the robustness of the hidden watermark for additive noise, MP3 compression, re-quantization, filtering, cropping and resampling. The comparison analysis shows that our method has better performance than watermarking schemes reported recently. © 2006-2012 IEEE. Source

Today, the reverse osmosis (RO) becomes a process of first importance for fresh water production worldwide. For this reason, downtimes due to repairing operations (following breakdowns, blockage of membrane, pressure losses, etc.) or preventive maintenance (cleaning of membranes, changes in components, etc.) have to be minimized in duration and frequency to ensure maximum availability. Indeed, improving the availability (or the reliability) of the RO plant as a whole system, objectively leads to a substantial reduction in operating costs and maintenance. In this paper we consider two methods for availability and effectiveness assessment of an RO unit, where the main objective is economic optimization. The two methods are Reliability Block Diagram Method (RBD) and Fault Tree Analysis Method (FTA). For the validation of both methods, we used data related to an RO unit operating in Kuwait and corresponding to four years operation. A comparison between both methods was performed in order to highlight the efficiency and the limitation of each one.It was shown that all the subsystems (pretreatment, dosing, etc.) have a good availability. Slightly lower availability was determined for the high pressure pump. A sensitivity study was conducted to determine the critical components for the availability of the RO plant. The obtained results show a high influence of the availability of the high pressure pump on the total availability of the system. Hence, particular attention should be taken on the selection and the maintenance of the high pressure pump.The comparison between the two methods RBD and FTA shows that the first method is more appropriate for the availability assessment because it allows accurate modeling of different complex configurations. © 2012 Elsevier B.V. Source

Hammami S.,National Engineering School of Tunis
ISA Transactions | Year: 2015

This paper deals with a new state feedback-based synchronization problem for coupled hyperchaotic systems. In the beginning, complete synchronization conditions of coupled chaotic systems, are provided. The active control law developed is based on the use of both aggregation techniques for error dynamics stability study and the arrow form matrix for systems description. After that, the proposed feedback-based synchronization between two identical hyperchaotic systems is successfully applied for transmitting an encoded image. To finish, numerical simulations are carried out to assess the performance and the efficiency of the proposed contributions in the important field of secure image encryption. © 2014 ISA. Source

Hamdi M.A.,National Engineering School of Tunis
International Journal of Imaging and Robotics | Year: 2012

This paper proposes a new technique's segmentation that combines multiresolution contourlet transform with the watershed transform. The contourlet transform is one kind of new multi-scale transform that is based on discrete curvelet transform, whose structural elements include the parameters of location and dimension, and orientation parameter more, which let contourlet transform has good orientation characteristic. Therefore, contourlet transform is superior to curvelet in the expression of image edge, and denoising such as geometry characteristic of discrete curve and beeline, which has already obtained very good research results in image denoising. The flooding watershed transform is then applied, and the segmented image is projected up to higher resolutions using contourlet transform. Typically, if a low resolution is chosen for the initial segmentation so large relevant objects will be captured (noise); therefore, a higher initial resolution will lead to smaller and more detailed segmented objects. This paper puts forward an improved method based on contourlet and watershed transform because certain regions of the image have the ringing and radial stripe after contourlet transform. © 2012 by IJIR (CESER Publications). Source

Bouzid M.B.K.,National Engineering School of Tunis | Bouzid M.B.K.,Ecole de Technologie Superieure of Montreal | Champenois G.,University of Poitiers
IEEE Transactions on Industrial Electronics | Year: 2013

This paper proposes new expressions of symmetrical components (SCs) of the stator currents of the induction motor (IM) in steady state and under different stator faults, useful to ensure an efficient fault diagnosis. In this paper, the considered stator faults are interturns short circuit, phase-to-phase, and single-phase-to-ground faults. An analytical study of the behavior of these expressions shows that, under balanced supply voltage, the phase angle and the magnitude of the negative-and zero-sequence currents can be considered as reliable indicators of stator faults of the IM. The behavior of the developed expressions of the SCs is also verified experimentally on a 1.1-kW IM under different fault conditions, different frequencies, and different load conditions. The good agreement between the analytical and experimental values leads to consider the negative-and zero-sequence currents as powerful and effective indicators of stator faults. © 1982-2012 IEEE. Source

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