Analyse des conditions de rupture des conduites d’adduction d’eau potable en polyéthylène, sous l’effet d’écoulement transitoire, en présence d’un défaut

The efficiency of potable water distribution systems has been recently the subject of much research. Leakages or a ruptures, occurring in pipes, are quite a frequent phenomenon in urban areas. In order to minimize long-term risks of leakage, about 60% of potable water networks are built or renewed with the third generation of polyethylene pipe, PE100. It is a material with various features, which makes it a widely used material in the water supply networks. However, under transient conditions and with a surficial defect in the pipe, a failure occurs. To investigate this issue, our study is divided into two main parts. The first part is studying the dynamic effect of the viscoelastic material under transient flow conditions using a developed mathematical model. We have demonstrated that the viscoelastic behavior of PE100 plays a primordial role in the damping of water hammer and resonance phenomenon. In case of presence of coupling junction, a study of the fluid structure interaction is mandatory to correctly define the natural frequencies of a piping system. In the second part, we have investigated the crack behavior of PE100 pipes with defects. Using the experimental tests and finite elements results, we have demonstrated that the concept of elastic-plastic fracture mechanics, the J-Integral, define with reasonable accuracy the behavior of cracked PE100-pipe. At the end, we sought to determine the J-Integral with a semi-empirical model in order to define a relationship between the crack initiation pressure, the dimension of semi-elliptical surface cracks and the geometry of the pipeLe problème du rendement de la distribution des eaux potables a récemment fait l’objet de nombreux travaux de recherche. En effet, les ruptures des canalisations et les fuites sont des phénomènes assez fréquents en milieu urbain. Afin de réduire au maximum les risques de fuite à long terme, près de 60 % des réseaux d’eau potable sont construits ou renouvelés avec des conduites en polyéthylène de troisième génération, PE100. De par ses caractéristiques, c’est un matériau de choix pour les réseaux d’adduction d’eau. Mais la présence d’un défaut superficiel peut générer la rupture de la conduite sous l’effet d’écoulement transitoire. Afin d’étudier ce problème, notre étude est décomposée en deux parties. La première est consacrée à l’étude de l’effet dynamique du comportement viscoélastique du matériau sur l’écoulement transitoire à l’aide d’un modèle mathématique que nous avons développé dans cette thèse. Nous avons démontré que le comportement viscoélastique du PE100 joue un rôle primordial dans l’amortissement du phénomène du coup de bélier et de résonance. En cas de présence de couplage de jonction, l’étude de l’interaction fluide-structure est nécessaire pour définir correctement les fréquences propres d’un système de conduites. Ensuite, dans la seconde partie, nous avons étudié le comportement à la fissuration des conduites en PE100 présentant un défaut. A l’aide d’essais expérimentaux et de modélisations par éléments finis, nous avons démontré que le concept de la mécanique élasto-plastique de rupture, l’intégrale J, peut définir avec une précision acceptable le comportement à la fissuration d’une conduite en PE100. Nous avons cherché à déterminer l’intégrale J à l’aide d’un modèle semi-empirique afin de définir une relation entre la pression d’amorçage de fissure, la taille de défaut (fissure semi-elliptique) et la géométrie de la conduit

Failure analysis of drinking water polyethylene pipe under the effect of transient flow in the presence of a defect

Le problème du rendement de la distribution des eaux potables a récemment fait l’objet de nombreux travaux de recherche. En effet, les ruptures des canalisations et les fuites sont des phénomènes assez fréquents en milieu urbain. Afin de réduire au maximum les risques de fuite à long terme, près de 60 % des réseaux d’eau potable sont construits ou renouvelés avec des conduites en polyéthylène de troisième génération, PE100. De par ses caractéristiques, c’est un matériau de choix pour les réseaux d’adduction d’eau. Mais la présence d’un défaut superficiel peut générer la rupture de la conduite sous l’effet d’écoulement transitoire. Afin d’étudier ce problème, notre étude est décomposée en deux parties. La première est consacrée à l’étude de l’effet dynamique du comportement viscoélastique du matériau sur l’écoulement transitoire à l’aide d’un modèle mathématique que nous avons développé dans cette thèse. Nous avons démontré que le comportement viscoélastique du PE100 joue un rôle primordial dans l’amortissement du phénomène du coup de bélier et de résonance. En cas de présence de couplage de jonction, l’étude de l’interaction fluide-structure est nécessaire pour définir correctement les fréquences propres d’un système de conduites. Ensuite, dans la seconde partie, nous avons étudié le comportement à la fissuration des conduites en PE100 présentant un défaut. A l’aide d’essais expérimentaux et de modélisations par éléments finis, nous avons démontré que le concept de la mécanique élasto-plastique de rupture, l’intégrale J, peut définir avec une précision acceptable le comportement à la fissuration d’une conduite en PE100. Nous avons cherché à déterminer l’intégrale J à l’aide d’un modèle semi-empirique afin de définir une relation entre la pression d’amorçage de fissure, la taille de défaut (fissure semi-elliptique) et la géométrie de la conduiteThe efficiency of potable water distribution systems has been recently the subject of much research. Leakages or a ruptures, occurring in pipes, are quite a frequent phenomenon in urban areas. In order to minimize long-term risks of leakage, about 60% of potable water networks are built or renewed with the third generation of polyethylene pipe, PE100. It is a material with various features, which makes it a widely used material in the water supply networks. However, under transient conditions and with a surficial defect in the pipe, a failure occurs. To investigate this issue, our study is divided into two main parts. The first part is studying the dynamic effect of the viscoelastic material under transient flow conditions using a developed mathematical model. We have demonstrated that the viscoelastic behavior of PE100 plays a primordial role in the damping of water hammer and resonance phenomenon. In case of presence of coupling junction, a study of the fluid structure interaction is mandatory to correctly define the natural frequencies of a piping system. In the second part, we have investigated the crack behavior of PE100 pipes with defects. Using the experimental tests and finite elements results, we have demonstrated that the concept of elastic-plastic fracture mechanics, the J-Integral, define with reasonable accuracy the behavior of cracked PE100-pipe. At the end, we sought to determine the J-Integral with a semi-empirical model in order to define a relationship between the crack initiation pressure, the dimension of semi-elliptical surface cracks and the geometry of the pip

Tenue en service des joints soudés (influence des paramètres géométriques)

LILLE1-BU (590092102) / SudocSudocFranceF

An Efficient Service Selection Approach with Time-Dependent QoS

International audienceIn advanced service-oriented computing, complex applications are usually specified as abstract business processes. The execution of these applications requires the selection of a set of services to invoke abstract business tasks. With the growing number of alternative services of each business task that differ in their QoS, the selection of the best combination of services that satisfies business process constraints and end-to-end users' requirements becomes a complex decision problem. Current selection approaches consider only static QoS and ignore the fact that QoS values can depend on temporal properties. In this paper, we propose a novel service selection approach considering time-dependent QoS attributes. The proposed approach introduces two search space reduction mechanisms that combine QoS and temporal constraints. The application of these mechanisms improves the performance of the selection process which is demonstrated by experimental results

Modélisation et analyse expérimentale du procédé de soudage par friction

Cette étude contribue à la modélisation numérique du soudage par friction pour l'identification des paramètres de soudage. La modélisation repose sur le calcul de la quantité de chaleur générée par frottement et sur la répartition spatiale de la chaleur en tenant compte de la variation des propriétés thermiques et physiques du matériau. Des essais de soudage par friction nous ont permis d'étudier l'effet du temps de friction sur la propagation de la chaleur et sur la taille de la zone affectée thermiquement

Time-aware selection approach for service composition based on pruning and improvement techniques

International audienceIn service-oriented environments, abstract business processes can be implemented by concrete services to build complex applications. Given global user constraints, service selection allows to identify the best combination of services with respect to the business constraints. Generally, the selection problem is challenging, but it is particularly complex when dealing with QoS (quality of service) values, which can change during the time associated with temporal constraints. Indeed, these constraints make the selection problem heavily constrained, which can present a barrier for enabling effective service selection. Unlike static QoS values which have been deeply studied in the existing service selection approaches, time-dependent QoS associated with temporal constraints are insufficiently taken into consideration. Moreover, existing approaches cannot handle heavily constrained problems and usually do not provide strategies to detect the source of failure in order to enhance the selection problem in case there is no solution. In this paper, we introduce a new service selection approach, while considering time-dependent QoS values associated with temporal constraints. First, pruning techniques are proposed. The aim of the pruning process is twofold: (1) it allows for reducing the search space and thus, enhancing the efficiency of the selection process; (2) it allows for improving the selection problem by detecting at earlier stages the possible causes of failure, even before the selection process. Second, based on the pruning phase, improvement techniques are proposed to identify possible actions for finding a solution. Third, an exact and an approximate service selection algorithms under several constraints are given. Finally, we demonstrate the effectiveness of our approach through experimental results

A comprehensive survey on intra and inter organizational agreements

International audienceWith the continued growth of Service Oriented Architectures (SOA), cross-organizational enterprise collaboration is needed to satisfy complex client needs. To define dependencies between collaborative enterprises and guarantee the required Quality of Service (QoS) at different layers of the SOA, agreements present an effective solution. In fact, using agreements at different layers of SOA gives a clear specification and control of the agreed service levels between different stakeholders involved in the composition. In this context, aggregation functions that allow the management of composite agreements from the atomic ones at the same layer and translation techniques to detect dependencies between agreements at multiple layers are needed. In this paper, we give a survey on intra and inter organizational agreements for enterprise collaborations. We start by presenting the motivation of this paper and give an overview of agreements lifecycle and categories. Then, we give a state of the art of agreements composition approaches. After that, we highlight the techniques used to manage dependencies between agreements composition and we finish this paper by giving a synthetic view of existing works

Time-aware selection approach for service composition based on pruning and improvement techniques

International audienceIn service-oriented environments, abstract business processes can be implemented by concrete services to build complex applications. Given global user constraints, service selection allows to identify the best combination of services with respect to the business constraints. Generally, the selection problem is challenging, but it is particularly complex when dealing with QoS (quality of service) values, which can change during the time associated with temporal constraints. Indeed, these constraints make the selection problem heavily constrained, which can present a barrier for enabling effective service selection. Unlike static QoS values which have been deeply studied in the existing service selection approaches, time-dependent QoS associated with temporal constraints are insufficiently taken into consideration. Moreover, existing approaches cannot handle heavily constrained problems and usually do not provide strategies to detect the source of failure in order to enhance the selection problem in case there is no solution. In this paper, we introduce a new service selection approach, while considering time-dependent QoS values associated with temporal constraints. First, pruning techniques are proposed. The aim of the pruning process is twofold: (1) it allows for reducing the search space and thus, enhancing the efficiency of the selection process; (2) it allows for improving the selection problem by detecting at earlier stages the possible causes of failure, even before the selection process. Second, based on the pruning phase, improvement techniques are proposed to identify possible actions for finding a solution. Third, an exact and an approximate service selection algorithms under several constraints are given. Finally, we demonstrate the effectiveness of our approach through experimental results

Heuristic Based Time-Aware Service Selection Approach

International audienceQoS-based service selection is one of the importantrequirements in Service Oriented Computing (SOC). A challengingtask towards this purpose is the selection of the bestcombination of services that fulfils user’s requirements whilemeeting quality of service (QoS) constraints. This challengebecomes more complex when dealing with time-dependent QoSvalues and temporal properties. Indeed, during the selection,mutual dependencies between the different temporal constraintsmay arise so that the selection of each service may influenceor be influenced by the selection of other services. On otherside, to find the best solution, all potential combinations mustbe compared. However, the number of these combinations maybe very high, which can present a barrier for enabling effectiveservice selection. In this paper, we present a heuristic based timeawareservice selection approach to efficiently select a close-tooptimalcombination of services. First, pruning techniques areadopted to reduce the search space. Second, a novel heuristicapproach is proposed based on service clustering, constraintsdecomposition and local selection while considering both QoSand temporal constraints. Finally, experiments which confirm thefeasibility and effectiveness of the proposed approach in termsof its timeliness and optimality, are conducted

Pruning based Service Selection Approach under QoS and Temporal Constraints

International audienceDynamic selection of the best services to execute abstract tasks of business processes is very important. Indeed, it enables to cope with complex user's requirements that require the collaboration of several more elementary services. However, with the increasing amount of candidate services of each business task that offer different QoS (Quality of Service) parameters, the selection of the optimal combination of services becomes a very hard task. This problem is more complex when dealing with temporal properties of business processes associated with time-dependent QoS parameters that can change according to temporal properties such as the execution time. Unlike static QoS which have been deeply studied in the existing service selection approaches, time-dependent QoS are insufficiently taken into consideration. In this paper, we are interested in the problem of service selection to satisfy a given business process while considering temporal properties associated to time-dependent QoS