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Modelling and Wavelet-Based Identification of 3-DOF Vehicle Suspension System

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Journal of Software Engineering and Applications 2011年第12期4卷 672-681页

作者： Khaled Nouri Hichem Loussifi naceur Benhadj Braiek 不详

In this paper, a three Degrees Of Freedom (DOF) model of a quarter vehicle suspension system is proposed including the seat driver mass. The modal parameters of this system, which indicate the comfort and the safety of the suspension, are identified using Wavelet analysis. Two applications of wavelet analysis are presented: signal denoising based on the Discrete Wavelet Transform (DWT) and modal identification based on the Continuous Wavelet Transform (CWT). It is shown that the CWT analysis of the system response, initially denoised using DWT, allows the estimation of the natural pulsations and the damping ratios. The usefulness of the DWT in denoising and the accuracy of the CWT in modal identification are tested and confirmed by applying them to the proposed model. The complete modeling and identification of a 3-DOF vehicle suspension system is developed and the simulation results verify these statements and are satisfactory.

关键词： Suspension System Discrete and Continuous Wavelet Transform Signal Denoising Modal Identification

Characterization of a human brain cortical surface mesh using discrete curvature classification and digital elevation model

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Journal of Biomedical Science and Engineering 2012年第3期5卷 133-140页

作者： Kamel Aloui Amine Nait-Ali Mohamed Saber naceur LiSSi EA LaboratoryUniversite Paris-Est Creteil(UPEC)CreteilFrance LTSIRS Laboratory National Engineering SchoolTunisTunisia

In this paper we present a novel approach for brain surfacec characterization based on convexity and concavity analysis of cortical surface mesh. Initially, volumetric Magnetic Resonance Images (MRI) data is processed to generate a discrete representation of cortical surface using low-level segmentation tools and Level-Sets method. Afterward, pipeline procedure for brain characterization/labeling is developed. The first characterization method is based on discrete curvature classification. This is consists on estimating curvature information at each vertex in the cortical surface mesh. The second method is based on transforming the brain surface mesh into Digital Elevation Model (DEM), where each vertex is designed by its space coordinates and geometric measures related to a reference surface. In other word, it consists on analyzing the cortical surface as a topological map or an elevation map where the ridge or crest lines represent cortical gyri and valley lines represents sulci. The experimental results have shown the importance of these characterization methods for the detection of significant details related to the cortical surface.

关键词： Brain Curvature DEN Level-Sets MRI Mapping Surface Mesh

Spontaneous and simultaneous complete bilateral rupture of the quadriceps tendon in a patient receiving hemodialysis: A case report and literature review

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World Journal of Orthopedics 2018年第9期9卷 180-184页

作者： Wassim Zribi Mohamed Zribi Ahmed Racem Guidara Mohamed Ben Jemaa Ameur Abid Nabil Krid Abdessalem naceur Hassib Keskes Department of Orthopaedic Surgery and Traumatology Habib Bourguiba University Hospital Department of Orthopaedic Surgery and Traumatology Marechal Leclerc Argentan Hospital

The spontaneous and simultaneous rupture of both quadriceps tendons is uncommon and has rarely been reported in the literature. The current case involves a 43-year-old man with end-stage renal disease requiring hemodialysis for the past 20 years. The patient experienced bilateral knee pain and swelling and was unable to bear weight. Physical examination revealed bilateral quadriceps tendon defect above the patella and loss of active extension. Although plain radiographs of both knees showed no fracture or widening of the joint space, an inferiorly positioned patella was observed. Ultrasonography of the knees revealed a quadriceps tendon defect at the upper edge of each patella, while MR imaging revealed a tear in each quadriceps tendon from the superior poles of the patella. The patient then underwent surgical correction wherein the tendons were repaired using sutures passed through drill holes in the patella. The knees were immobilized with splints for 4 wk before starting physiotherapy. The patient subsequently regained full functional activity within 1 year.

关键词： Quadriceps tendon Tear Krackow sutures Renal failure Hyperparathyroidism

Robust Adaptive FTC against Sensor Fault

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Computer Technology and Application 2012年第1期3卷 56-68页

作者： Amina Challouf Christophe Aubrun Adel Tellili Mohamed naceur Abdelkrim Unite de Recherche. Modelisation Analyse et Commande de Systemes （MACS） Ecole Nationale d＇Ingenieurs de Gabes （ENIG） Facultes des Sciences et Techniques Centre de Recherche en Automatique de Nancy （CRAN） Nancy-University CNRS UMR 7039 France Institute Superieure des Etudes Technologiques de Djerba （ISET） Universite de Gabes Gabes 6029 Tunisia

This paper addresses the problem of robust Fault-Tolerant （FT） design for large-scale systems. This particular class constitutes complex system which can be decomposed into N-interconnected subsystems. Special attention is paid to two different design architectures of an Active Fault-Tolerant Control （AFTC）. An AFTCS is characterized by an online Fault Detection and Isolation （FDI） process and a control reconfiguration mechanism. As the AFTC system offers the possibility to choose different controllers, the controller may be the most appropriate choice for the faulty situation and obtaining better performance. The goal of each adaptive controller is to accommodate sensor anomalies. Continuous, Linear and Time Invariant （LTI） complex system with faulty sensors and external disturbances is proposed. This study focuses on two different internal structures of the system. In this paper the direct adaptive method based on feedback controller design is applied both centralized and decentralized architectures. The controller gain is updated online using an adaptive law which takes into account the estimation of the faults and the disturbances. Then from the both classes of systems structures the adaptation controller performances, in terms of stability and fault effect rejection capability, are studied and compared. The proposed techniques are finally evaluated in the light of a simulation for a centralized interconnected system that can be decomposed into N-subsystems with some strong interconnections.

关键词： Adaptive control centralized control complex system decentralized control fault-tolerant control (FTC),N-Interconnected subsystems robust control sensor failure.

Robust Control of Time Delay Systems

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Computer Technology and Application 2012年第1期3卷 69-75页

作者： Farhati Samia Bel Hadj All Naoui Saloua Abdelkrim Mohamed naceur Modeling Analysis and Control of Systems National Engineering School of Gabes Street lbn E1 Khatab Zrig 6029 Gabes Tunisia

This study presents the design of both H∞ Loop Shaping Control （HLSC） and Internal Model Control （IMC） strategies for linear time delay systems. For first order time delay system, a systematic approach for weight selection based on the sensitivity function was proposed, then compared to the internal model control strategy. For both methods, the synthesis was based on the Pade approximation. Two cases are considered for time delay： upper or lower than system time constant. Simulation results for the proposed approaches are acceptable ever in presence of disturbances and model mismatches.

关键词： H∞ loop shaping control internal model control sensitivity function constant delay Pade approximation model mismatches.

Predictive Factors of Multiple Hospitalizations for Acute Exacerbations of COPD

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Open Journal of Respiratory Diseases 2019年第3期9卷 61-74页

作者： Ahmed Ben Saad Nesrine Fahem Asma Migaou Saousen Cheikh Mhamed Samah Joobeur naceur Rouatbi Pulmonology Department Fattouma Bourguiba Teaching Hospital Monastir Tunisia

Background: Multiple hospitalizations for acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are associated with considerable morbidity and mortality. Objectives: To identify predictive factors of multiples hospitalizations for AECOPD. Methods: This is a retrospective single center study of consecutive patients with COPD hospitalized at the Department of Respiratory Medicine between January 1990 and December 2015. We calculated for each patient the mean number of hospitalizations for AECOPD/year (H/y). We distinguished 2 groups (G) of patients. G1: <2 H/y and G2: ≥2 H/y. Predictors of multiple admissions identified by univariate analysis were included in the multivariate analysis. Results: The study included 1167 COPD patients (mean age 67 ± 10 years, 97% males). Three hundred six (26%) COPD patients had a mean number of hospitalizations per year ≥ 2. Multivariate logistic regression analysis demonstrated that an mMRC ≥ 2 (Odd ratio [OR] 1.8, 95% confidence interval [CI] 1.08 - 2.99, p = 0.022), a low PaO2 (PaO2 OR 0.97, 95% CI 0.95 - 0.99, p = 0.007) and frequent exacerbations (OR 2.95, 95% CI 2.56 - 3.39, p < 0.001) are independent factors associated with multiple admissions for AECOPD. Conclusions: An mMRC ≥ 2, a low PaO2 and frequent exacerbations are independently associated with multiple hospitalizations for AECOPD. The identification of these high risk COPD patients will be helpful in the decision of intervention strategies.

关键词： COPD Hospitalization COPD Exacerbation Risk Factors Hospital Readmission

Ambient Intelligence: Awareness Context Application in Industrial Storage

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Wireless Sensor Network 2011年第4期3卷 135-146页

作者： Ahmed Zouinkhi Eddy Bajic Eric Rondeau Mohamed Ben Gayed Mohamed naceur Abdelkrim UMR Research Center for Automatic Control CRAN CNRS / Henri Poincare University Research Unit MACS National Engineering School of Gabes

WSNs are designed to efficiently collect data and monitor environments, among other applications. This article describes the concept and realization of an Active Security System for security management of warehousing of chemical substances using WSNs. We present an approach to modeling and simulating cooperation between intelligent products that are equipped with a platform of sensor networks and ambient communication capabilities to increase their security, in a context of ambient intelligence of a deposit for chemical substances. Behavior evolution of every intelligent product is modeled by hierarchical Petri Nets. The simulation of the model is implemented in the Castalia-OMNET++ Tools language.

关键词： Ambient Intelligence Intelligent Product Cooperation Security WSN Petri Nets Castalia

Does Making Method of Alginate Hydrogel Influence the Chondrogenic Differentiation of Human Mesenchymal Stem Cells?

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Engineering（科研） 2012年第10期4卷 110-113页

作者： Jessica Schiavi naceur Charif Natalia de Isla Daniele Bensoussan Jean-Francois Stoltz Nadia Benkirane-Jessel Celine Huselstein INSERM-UMR Faculty of medicineStrasbourg UniversityStrasbourgFrance Universitede Lorraine CNRS-UMR–Campus Sante–BiopoleFaculty of medicineLorraine UniversityVandouvre-les-NancyFrance

To overcome cartilage injury, strategies have been developed in the last few years based on tissue engineering to rebuild the defects. Cartilage engineering is principally based on three main biological factors: cells (native cells (chondrocytes) or a more primitive ones as mesenchymal stem cells), scaffolds and functionalization factors (growth factors, mechanical stimulation and/or hypoxia). Cartilage tissue engineering strategies generally result in homogeneous tissue structures with little resemblance to native zonal organization of articular cartilage. The main objective of our work concerns the buildup of complex biomaterials aimed at reconstructing biological tissue with three dimensional cells construction for mimicking cartilage architecture. Our strategy is based on structures formation by simple and progressive spraying of mixed alginate hydrogel and human mesenchymal stem cells (hMSC). In this work, the comportment of cells and more precisely their chondrogenic differentiation potential is compared to a traditional making process: the mold. We report here that spraying method allowed to product a scaffold with hMSC that confer a favorable environment for neocartilage construction.

关键词： Component: Cartilage Tissue Engineering Sodium Alginate Sprayed method Molded Method

DIFFERENT NANOFIBRILLATED CELLULOSE AND INNOVATIVE STRATEGIES DEVELOPED FOR THEIR USES IN COATING OR EXTRUSION

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DIFFERENT NANOFIBRILLATED CELLULOSE AND INNOVATIVE STRATEGIE...