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Bearings, considered crucial components in rotating machinery, are widely used in the industry. Bearing status monitoring has become an essential step in the deployment of preventive maintenance policy. This work is part of the diagnosis and classification of bearing defects by vibration analysis of signals from defective bearings using time domain and frequency analysis and wavelet packet transformations (Wavelet Packet Transform WPT) with Artificial Neural Networks (ANN). WPT is used for extracting defect indicators to train the neural classifier. The main goal is the determination of the wavelet generating the most representative indicators of the state of the bearings for better detection and classification of defects. Using the WPT-based neural classifier, the obtained simulation results showed that the db6 wavelet with level 3 decomposition is best suited for diagnosing and classifying bearing defects.

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This work presents an experimental study on a composite material obtained from vegetable and industrial wastes. The date palm leaflets waste was used as reinforcement in the form of short fibers, and the expanded polystyrene waste was recycled and used as a matrix for the preparation of the leaflets polystyrene composite material (LPC). The LPC material without lignin was prepared using a mass proportion of 70/30 % between the reinforcement and the matrix. In order to evaluate the effect of the presence of lignin on the mechanical properties of the LPC material, three combinations between reinforcement, matrix and lignin are considered. The three mass proportions between the reinforcement, matrix and lignin are respectively (70/28.5/1.5 %), (70/27/3 %) and (27/26.5/4.5 %). Threepoint bending tests were carried out to obtain the mechanical properties both flexural modulus and maximum stress. A comparative study between the mechanical properties of the LPC material without lignin (Fibers/Matrix) and the composite material with the presence of the lignin (Fiber/Matrix/lignin) is carried out. Results have shown that the presence of lignin in the LPC material reduces the bending mechanical properties of the material.