Réflexions sur les pouvoirs de la maternité. A partir des récits de vie de Maherzia Amira Bournaz

Le texte contient quelques points de repère sur le pouvoir de la mère dans le vécu tunisien, la condition féminine au début du XXe siècle et la démarche utilisée par certaines pour combattre cet état de fait

Collaborative robot control with hand gestures

Mestrado de dupla diplomação com a Université Libre de TunisThis thesis focuses on hand gesture recognition by proposing an architecture to control a collaborative robot in real-time vision based on hand detection, tracking, and gesture recognition for interaction with an application via hand gestures. The first stage of our system allows detecting and tracking a bar e hand in a cluttered background using skin detection and contour comparison. The second stage allows recognizing hand gestures using a Machine learning method algorithm. Finally an interface has been developed to control the robot over. Our hand gesture recognition system consists of two parts, in the first part for every frame captured from a camera we extract the keypoints for every training image using a machine learning algorithm, and we appoint the keypoints from every image into a keypoint map. This map is treated as an input for our processing algorithm which uses several methods to recognize the fingers in each hand. In the second part, we use a 3D camera with Infrared capabilities to get a 3D model of the hand to implement it in our system, after that we track the fingers in each hand and recognize them which made it possible to count the extended fingers and to distinguish each finger pattern. An interface to control the robot has been made that utilizes the previous steps that gives a real-time process and a dynamic 3D representation.Esta dissertação trata do reconhecimento de gestos realizados com a mão humana, propondo uma arquitetura para interagir com um robô colaborativo, baseado em visão computacional, rastreamento e reconhecimento de gestos. O primeiro estágio do sistema desenvolvido permite detectar e rastrear a presença de uma mão em um fundo desordenado usando detecção de pele e comparação de contornos. A segunda fase permite reconhecer os gestos das mãos usando um algoritmo do método de aprendizado de máquina. Finalmente, uma interface foi desenvolvida para interagir com robô. O sistema de reconhecimento de gestos manuais está dividido em duas partes. Na primeira parte, para cada quadro capturado de uma câmera, foi extraído os pontos-chave de cada imagem de treinamento usando um algoritmo de aprendizado de máquina e nomeamos os pontos-chave de cada imagem em um mapa de pontos-chave. Este mapa é tratado como uma entrada para o algoritmo de processamento que usa vários métodos para reconhecer os dedos em cada mão. Na segunda parte, foi utilizado uma câmera 3D com recursos de infravermelho para obter um modelo 3D da mão para implementá-lo em no sistema desenvolvido, e então, foi realizado os rastreio dos dedos de cada mão seguido pelo reconhecimento que possibilitou contabilizar os dedos estendidos e para distinguir cada padrão de dedo. Foi elaborado uma interface para interagir com o robô manipulador que utiliza as etapas anteriores que fornece um processo em tempo real e uma representação 3D dinâmica

[4-(2-Amino­ethyl)piperazin-1-ium]trichloridocopper(II) monohydrate

In the title compound, [CuCl3(C6H16N3)]·H2O, the copper(II) ion is five-coordinated by two N atoms from the bidentate 4-(2-amino­ethyl)piperazin-1-ium cation and three chloride ions in a distorted square-pyramidal environment. Inter­molecular N—H⋯Cl and O—H⋯Cl hydrogen bonds build up an intricate three-dimensional network

Numerical Investigation of PCM Melting in a Finned Tube Thermal Storage

Due to their high energy storage capacity, latent heat storage units using phase change materials (PCMs) have gained considerable attention over the past three decades. The heat exchange of a PCM with the surrounding medium is managed by the thermal energy equation (solidification/melting) with different complex boundary and initial conditions. In this study, we propose to solve numerically this equation applied to a PCM by the finite difference method. To understand the storage phenomenon of solar energy in the form of latent heat in PCM, initially found under cooling at 18°C, we studied the fusion in a specific configuration corresponding to a tubular exchanger with five circular horizontal fins. In this perspective, we propose in this work a numerical investigation based on an enthalpy formulation to study the melting of a PCM in a finned heat exchanger. This numerical approach gives simultaneously the temperature distributions in the PCM storage system and temporal propagation of the melting front during the melting of the PCM when it is exposed to a hot airflow. Also, we give in this study the transient evolution of the longitudinal air temperature profiles

Numerical parametric study of a cooling system for an LNG storage tank

International audienceThe study of the cooling system of a Liquefied Natural Gas (LNG) storage tank is vital for the safety of the installation. The objective of this paper is to develop cooling baffles capable of reducing the heat gain from the environment leading to a loss of LNG quantity, keeping the Boil-Off Gas (BOG) under control. For this purpose, a specific code based on the finite volume method was developed to improve our knowledge of the hydrodynamic and thermal behaviors of LNG in the cylindrical tank. In addition, the effect of the number, position and dimension of the baffles on the flow structure of LNG were determined. The obtained results indicated that the location of the baffles at the top of the tank nearby the vicinity of the wall would yield a better cooling of the LNG. Moreover, we emphasized that a number of six baffles would give rise to a better heat transfer. For a design purpose, the Nusselt numbers on the lateral surface and on the baffles have been correlated as functions of Rayleigh and baffle numbers

La lagune de Ghar El Melh : Diagnostic écologique et perspectives d'aménagement hydraulique

La lagune de Ghar El Melh, située au Nord de la Tunisie (dans le Golfe de Tunis), est caractérisée par une superficie de 28,5 km2, une faible profondeur et une faible communication avec la mer. Actuellement, sous l'effet des actions anthropiques (les rejets terrestres), elle connaît une dégradation progressive de la qualité de ses eaux et sédiments dont les conséquences sont la chute de la richesse biologique et la réduction des ressources halieutiques de la lagune.Dans ce travail, nous présentons les résultats de l'analyse des caractéristiques physico-chimiques et biologiques des eaux de la lagune. Ces analyses montent bien l'hyper-eutrophisation du milieu caractérisé par de fortes concentrations des eaux en azote total et en phosphore total. Les résultats de simulation du fonctionnement hydrodynamique, que nous avons réalisée à l'aide d'un modèle à 2 dimensions intégré sur la hauteur, montrent une stagnation des eaux dans environ 80% de surface de la lagune qui a fortement amplifié la dégradation de la qualité de l'écosystème. Parmi plusieurs scénarios d'aménagements simulés, nous proposons la création d'une nouvelle communication avec la mer dont la simulation hydrodynamique montre une nette augmentation des échanges d'eau mer-lagune. Nous présentons ensuite un modèle écologique homogène de la lagune de Ghar El Melh qui a été mis au point et calibré en s'appuyant sur les mesures de terrain. Les simulations, avec ce modèle, montrent que l'arrêt total des rejets terrestres et la création d'un nouveau grau réduisent considérablement l'eutrophisation du milieu ce qui conduiraient certainement à une nette amélioration de la production halieutique dans la lagune.The Ghar El Melh lagoon is a Mediterranean water body, situated in Northeastern Tunisia, on the Northwestern side of the Gulf of Tunis. The Ghar El Melh lagoon is a vestigial part of the Utique Sea, and this lagoon was largely open at the time of the Roman invasion. Due to a combination of the shape of the coastline and alluvium deposits from the Medjerda River, this small gulf has become progressively closed from the Utique Sea, causing the lagoon to become progressively shaped to its present morphology. The coastal barrier separating the lagoon from the Mediterranean Sea was interrupted, allowing a permanent hydraulic communication across a local opening. The lagoon has an elliptical shape of approximately 28.5 km2 and an average depth of 0.8 m. Due to human activities within the lagoon itself and in the surrounding area, the lagoon ecosystem has suffered a progressive deterioration. This deterioration has led to a reduction in biodiversity resulting mainly in a decrease in fish resources and production.In order to improve the water quality of the lagoon for ecological and economical purposes, a diagnostic survey was carried out to characterize the present site conditions and to provide data for calibration of hydrodynamic and ecological models. The main results of the annual survey of biotic and non-biotic parameters demonstrated the existence of zones within the lagoon, with some seasonal variation. Thus, a decreasing biotic and non-biotic gradient was measured from the area of the lagoon under marine influence towards the bottom of the lagoon, under the continental and anthropogenic influence of the west side. The lagoon could be considered hypereutrophic with an annual average concentration of total phosphorus of 350 mg/m3. In order to conceptualize and optimise hydraulic structures for water quality improvement in the lagoon, a numerical model of the velocity fields (depth averaged) and water depth was used. The hydrodynamic model used was bi-dimensional, adapted for use in shallow lagoons. After model calibration using in-situ measurements, simulations were carried out to analyse the present hydrodynamic condition of the lagoon. Several stagnation zones were detected, which contributed to the altered water quality that was observed. Several management practices were proposed and simulated, aiming to control and improve the internal circulation and water exchange between the lagoon and the Mediterranean Sea. The main goal of these simulations was to improve water mobility inside the lagoon, and thus improve the water quality. The proposed hydraulic development measures consisted mainly of the creation of a new hydraulic communication in the south-eastern area of the lagoon, by dredging the south part of the lake or by channel creation in front of the new communication, reaching the stagnation zones of the lagoon. The impact assessment of the proposed development was verified with simulations using the bi-dimensional hydrodynamic model.An ecological model based on nitrogen and phosphorus cycling, was also developed for Ghar El Melh lagoon. It took into account one ecological compartment, the macro algae, that included Cladophora sp., Ulva sp. and Enteromorpha sp. Algae (A), inorganic nitrogen (NA), inorganic phosphorus (PA), organic nitrogen (NEorg) and organic phosphorus (PEorg), were the main variables of this model. After calibration of the model, a 10-yr simulation showed that all variables demonstrated a steady behaviour and that the lagoon eutrophication level remained. Model sensitivity analysis allowed the choice of some restoration scenarios and the prediction of their impacts on the ecological behaviour of the ecosystem. The simulations showed that wastewater load deviation combined with an increase in the sea-lagoon water exchange, instead of a decrease of nutrient diffusion from the sediments, led to a substantial decrease in the eutrophication level of the lagoon. Indeed, the annual average nutrient concentrations decreased from 270 to 60 mg/m3 for total nitrogen and from 350 to 20 mg/m3 for total phosphorus in the Ghar El Melh lagoon

Response of free-living Nematodes to the quality of water and sediment at Bou Chrara Lagoon (Tunisia) during winter 2000

The Bou Ghrara lagoon, a stretch of water in southeastern Tunisia, has shown an alarming reduction of its fishery resources since 1993. In order to study the response of free-living nematodes to the water and sediment quality of this area, thirteen stations have been sampled. According to this study, the heavy metal, organic carbon and hydrocarbon content of sediments are key factors negatively influencing the density, biomass and diversity of the nematofauna

Analyse de sensibilité du système oasien et mesures de sauvegarde de l’oasis de Métouia (Tunisie)

L’oasis de Métouia, située au sud‑est de la Tunisie, est caractérisée par un climat aride où les précipitations sont rares et irrégulières. L’oasis doit donc son existence aux eaux souterraines qui, autrefois, provenaient de sources artésiennes actuellement taries suite à une surexploitation de la nappe profonde. La pédogenèse actuelle est dominée par l’évolution des processus de salinisation et d’hydromorphie affectant en totalité ou en partie le profil pédologique. Cette salinisation est la résultante des effets cumulés de la salinité des eaux d’irrigation et celle de la nappe phréatique proche de la surface dont la remontée capillaire génère des efflorescences salines. Ce facteur est accentué par l’absence de lessivage des sols et le dysfonctionnement du réseau de drainage. Le suivi des paramètres abiotiques de l’oasis durant quatre années successives (2001 – 2004), a révélé une interdépendance étroite entre la qualité des eaux précédemment décrite et les processus géochimiques qui en résultent, d’une part, et la dégradation de la zone non saturée, siège des accumulations gypseuses, d’autre part. Par ailleurs, aux facteurs précédemment signalés, viennent s’ajouter la mauvaise exploitation des parcelles et l’absence de règles de gestion du système oasien dans sa globalité. Afin de contrecarrer ces phénomènes qui affectent profondément la sensibilité du système oasien, on a élaboré des recommandations visant l’optimisation des besoins dynamiques en eau, du mode de distribution, ainsi que du réseau de drainage freinant la remontée de la nappe et améliorant l’aération et le lessivage de la zone non saturée.The Métouia oasis is situated in south-eastern Tunisia near the coast of Gabès City. The climate is arid with rare and irregular precipitation events. The oasis originated from a confined subsurface that was hydraulically connected to surface springs that had already been exhausted by human activities. The soil features are presently dominated by the evolution of salinization and water-saturation processes either partially or totally affecting the soil profile. The visible salt deposits and soil salinization processes are generated by the salinity of irrigation water and the shallow water table as well as the rising capillarity head. These processes are strongly influenced by the weak soil leaching mechanisms, on the one hand, and the poor drainage schemes, on the other hand. The four-year monitoring programme (2001 – 2004) focussed on important abiotic water and soil parameters and showed a close relationship between water quality and the generated geochemical processes parallel to the degradation of the non-saturated zone, in which gypsum accumulation processes are taking place. In addition to the above mentioned factors, the poor land exploitation system and the lack of integrated management of the oasis system are also important. Due to the high sensitivity of the oasis and in order to overcome the problems, several recommendations were proposed concerning the optimization of the irrigation scheme, the water supply network and drainage schemes. The recommended hydraulic infrastructure, combined with the proposed management rules for the oasis, would lead to better control of ground-water fluctuations and improvement of leaching and aeration processes in the unsaturated zone

Development, Implementation, and Validation of an Acoustic Emission-based Structural Health Monitoring System

Entwicklung, Implementierung und Validierung eines schallemissionsbasierten Strukturüberwachungssystems Die Strukturüberwachung eng. Structural Health Monitoring (SHM) ist ein grundlegender Prozess für die Kontrolle der Betriebssicherheit und Zuverlässigkeit von Strukturen und Bauteilen während des Betriebs. Ein Überwachungssystem soll die Strukturdegradation in einer frühen Phase erkennen und quantifizieren, um den Totalausfall zu verhindern und somit menschliche und finanzielle Verluste zu vermeiden. Mit der wachsenden Nachfrage nach kosteneffizienten und robusten Produkten ist SHM mit besonders hohen Anforderungen konfrontiert. Diese Arbeit befasst sich mit der Entwicklung, Implementierung und experimenteller Validierung eines innovativen SHM-Systems, das auf umfassende Weise Schädigungsmechanismen von unterschiedlichen Materialen erkennt, identifiziert und klassifiziert. Für in-situ-Strukturüberwachung können verschiedene Methoden angewendet werden. Hier wird die Schallemissionsanalyse eng. Acoustic Emission Technik (AET) eingesetzt. Acoustic Emission ist eine passive zerstörungsfreie Prüfund Überwachungsmethode. Sie basiert auf der Analyse elastischer Wellen, die durch freigesetzte Energie während mikrostrukturelle Änderungen wie z. B. Risse, Brüche, und Verschleiß entstehen. Unter Verwendung geeigneter Hardware und fortgeschrittener Signalverarbeitungsverfahren können diese Wellen kontinuierlich und in Echtzeit erfasst und analysiert werden. Die Leistungsfähigkeit und Zuverlässigkeit einer AE-basierten Schadensdiagnose sind stark abhängig von Material/Werkstoff, Konstruktion und möglichen Schadensszenarien. Der Fokus dieser Arbeit liegt daher auf der Entwicklung einer hocheffizienten und leicht anpassbaren Field Programmable Gate Array (FPGA)–basierten Messkette zum Abtasten und Erfassen der erzeugten AE-Signale. Neben der Verwendung von sehr leistungsfähiger Hardware ist eine zuverlässige Interpretation der AE Signale von zentraler Bedeutung. Deswegen erfordern die Entwicklung und Umsetzung von Multi-Level-Signalverarbeitungsansätzen und Mustererkennungsverfahren eine besondere Beachtung. Die experimentelle Validierung des entwickelten Systems erfolgt durch die Untersuchungen von drei verschiedenen Materialien/Strukturen: Verschleißfeste Metallbleche, Faserverbundwerkstoff Platten und elektrochemische Zelle. Aufgrund der Diversität der untersuchten Strukturen werden drei Verarbeitungsprozesse entwickelt. Die implementierten Algorithmen können AE-Signale erkennen, quantifizieren und qualifizieren, so dass AE-basierte Eigenschaften identifiziert und mit den entsprechenden AE-Quellen korreliert sind. Die Diagnose konzentriert sich hauptsächlich auf die Schadenserkennung (Merkmalsextraktion), Schadensabschätzung (Merkmalsauswahl) und Schadensklassifizierung unter Anwendung von Zeit-Frequenz-Analyse, statistischen Ansätzen und überwachten Klassifikationsverfahren. Die gewonnenen Ergebnisse zeigen eine bemerkbare Verbesserung der Identifizierung und Klassifizierung von Schadensmechanismen und beweisen die Effizienz des angewandten Multi-Level-Verarbeitungsansätze. Die vorgestellte Methodik ermöglicht eine automatisierte Zustandsüberwachung und stellt daher einen wichtigen Schritt in der Entwicklung von sicheren und zuverlässigen Strukturen dar.In engineering, Structural Health Monitoring (SHM) is an important field of study representing a fundamental process to control the longevity and reliability of structures during service. The objective of an SHM is to detect and quantify the structure degradation at an earlier stage. The acquisition of such information can contribute to prevention of total failure and hence avoiding human and financial losses becomes more possible. With the growing demands for cost-efficient and robust products, SHM is facing particularly high requirements. This thesis focuses on the development, implementation, and experimental validation of an innovative SHM system able to detect, identify, and classify in an extensive way damage mechanisms occurring in different materials. Several techniques can be applied for in situ health monitoring. In this work, Acoustic Emission Technique (AET) is used. Acoustic Emission is a passive nondestructive evaluation technique referring to the elastic waves generated by energy release during microstructural changes in the material. Those changes arise as a result of mechanical and environmental stresses. Monitoring of such a conversion can be continuously done in real-time using suitable hardware and advanced signal processing methods. The performance and reliability of an AE-based damage diagnosis approach are highly dependent on material, structure design and the damage scenarios. Therefore, a Field Programmable Gate Array (FPGA)-based measurement chains developed for sensing and acquiring the generated AE signals. This chain is easily adaptable to different structures and materials. It was therefore kept so far constant as possible throughout all tests conducted. Additionally to the use of highly efficient hardware that enhance the sensing quality and the data acquisition speed, the implementation of advanced filtering techniques with high processing accuracy is of central importance. The main objective of this thesis is to prove the function of the system developed to analyze AE waves under different damage scenarios. For this purpose, three different materials namely wear resistant plates, laminated composite plates, and electrochemical cells are investigated. Owing to the diversity of the studied materials, special attention is paid to the development and implementation of multilevel signal processing approach and pattern recognition methods. The processing chains are capable to detect, quantify and qualify the AE data, whereby AE-based characteristics are identified and correlated with the corresponding AE sources. The designed diagnosis methodology concentrates/focuses on damage detection (feature extraction), damage estimation (feature selection), and damage classification by using time-frequency analysis, multilevel statistical approaches, and supervised classification methods. The results obtained show a noticeable/remarkable enhancement of the identification and classification of damage mechanisms. The efficiency of applying multilevel processing approach is/(could be) thus proved. The methodology presented here, allows an automated structural health monitoring. Hereby, an important step forward in future development of safe and reliable structures is represented