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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Investigations of the Tube Support Plate (TSP) clogging phenomenon in PWR steam generators - understanding and prioritization of its formation mechanisms / Etudes sur le phénomène de colmatage dans les générateurs de vapeur des réacteurs à eau pressurisée (REP) – compréhension et hiérarchisation de ces mécanismes de formation

Yang, Guangze 16 November 2017 (has links)
Le générateur de vapeur est un composant essentiel du réacteur à eau pressurisée. Après 15 à 20 ans de fonctionnement du GV, un phénomène de colmatage est observé, qui induit le bouchage du passage folié entre les tubes GV et la plaque entretoise. Ce phénomène peut avoir de graves conséquences pour le fonctionnement de la centrale nucléaire. L’objectif majeur de cette thèse est d’approfondir les connaissances des mécanismes responsables de la formation du colmatage en identifiant et hiérarchisant les processus prépondérants. L’installation COLENTEC est un outil expérimental conçu pour reproduire des dépôts dans des conditions représentatives d’un GV. La post-caractérisation microscopique a permis d’identifier la contribution du phénomène de précipitation et le rôle d’initiation de la passivation du matériau. Les formes spécifiques du colmatage, lipping à l’entrée et rides le long de la plaque entretoise, n’ont pas été observées dans les essais COLENTEC. Cela peut être provoqué par l’absence de particules dans la section d’essai ou une vitesse insuffisante du fluide. Le flashing et le phénomène électrocinétique ont été supposés contribuer à la formation du colmatage. Une collaboration avec l’Université de Manchester a été établie au cours de ce travail afin d’étudier expérimentalement le phénomène électrocinétique. Les travaux effectués ont permis de mieux comprendre ce phénomène et de suggérer son influence considérable dans la formation du colmatage. Des quantifications numériques de chaque phénomène ont été réalisées, prédisant un rôle prédominant du phénomène électrocinétique. / The steam generator is an essential component in PWR. After 15-20 years of functioning, an obstruction by deposits of flow holes between Tube Support Plate (TSP) and primary tubes is observed, called TSP clogging. This phenomenon may lead to dramatic consequences for nuclear power plant operation. The aim of this thesis is to deepen the understanding of the mechanisms responsible for TSP clogging by identifying and prioritizing the preponderant processes. COLENTEC is an experimental facility designed to reproduce TSP clogging deposits under representative conditions. Microscopic characterizations allowed revealing the deposit formation by precipitation and the initiation role of material passivation in deposit formation. Lipping and ripple forms, specifying TSP clogging, were not observed in COLENTEC tests. This is suggested to be caused by insufficient concentration of suitable particles at the test section. Particle deposition is supposed to be essential for the formation of lipping deposits. Electrokinetic and flashing phenomena are supposed to contribute to TSP clogging formation. An experimental collaboration with the University of Manchester was established to better understand the clogging formation by investigating the role of electrokinetic phenomenon. This study allowed reforming deposits with lipping and ripple forms as observed in EDF steam generators. Electrokinetic involvement, strongly affected by flow velocity, was considerably suggested in TSP clogging formation. Numerical quantification of deposit formation by each phenomenon was performed and compared to EDF feedbacks. Electrokinetic phenomenon was found to play a predominant role.
72

AplicaÃÃo da metaheurÃstica tabu search na otimizaÃÃo de rotas de manutenÃÃo preventiva em campo / Application of the metaheuristic Tabu Search to the on field preventive maintenance routes optmization

Rodrigo Frank de Souza Gomes 08 December 2011 (has links)
nÃo hà / O objetivo deste trabalho foi propor uma aplicaÃÃo baseada na metaheurÃstica Busca Tabu (TS) para ser utilizada em serviÃos de manutenÃÃo preventiva em campo (FPMS) a fim de obter maior eficiÃncia logÃstica, atravÃs do roteamento de setores de manutenÃÃo. Ao contrÃrio dos serviÃos realizados na indÃstria, onde todos os sistemas, mÃquinas e equipamentos estÃo localizados praticamente no mesmo local, serviÃos de manutenÃÃo em campo requerem um componente adicional diretamente relacionado ao custo, que se refere exatamente a diferenÃa entre a unidade de base e local de trabalho. ServiÃos em campo podem ser considerados uma variaÃÃo do Problema do Caixeiro Viajante (PCV) e suas diferentes abordagens, como o Problema DinÃmico do Reparador Viajante (DTRP - Dynamic Travelling Repairman Problem) proposto por Bertsimas e Van Ryzin. Em situaÃÃes prÃticas do dia-a-dia existe uma enorme demanda por serviÃos de manutenÃÃo a serem realizados em campo, demonstrando sua relevÃncia: elevadores, escadas rolantes, aparelhos seguranÃa eletrÃnica residencial, suporte de TI à hardwares, entre outros. O mÃtodo foi implementado e testado em problemas da biblioteca TSP-LIBRARY variando de 17 a 280 pontos. Boas soluÃÃes foram encontradas em um tempo de processamento aceitÃvel. O input do problema leva em consideraÃÃo duas formas: coordenadas geogrÃficas ou coordenadas cartesianas. Para uma aplicaÃÃo prÃtica do mundo real, foi considerada uma empresa de manutenÃÃo em elevadores e os resultados tambÃm foram eficientes, reduzindo bastante os custos de transporte e a logÃstica empregada na operaÃÃo. / The aim of this paper was to propose an application based on the Metaheuristic Tabu Search (TS) to be used on FIELD PREVENTIVE MAINTENANCE SERVICES (FPMS) in order to get more logistics efficiency by routing maintenance sectors. Unlike services performed in industry, where all systems, machines and equipment are located practically in the same location, maintenance services in the field require an additional component directly related to cost, which refers to exactly offset between the base unit and jobsite. Services in the field can be considered a variation of the Travelling Salesman Problem (TSP) and its different approaches, like the DTRP (Dynamic Travelling Repairman Problem) proposed by Bertsimas and Van Ryzin. There is a huge demand for maintenance in the field, demonstrating its relevance: elevators, escalators, electronic devices for home-security, IT hardware support and others. The method was designed, implemented and tested in problems of the TSP-LIBRARY ranging from 17 up to 280 points. Good solutions were found in a acceptable processing time. The input data can be made by geographical coordinates or 2D-coordinates. For a real-world application, it was considered an Elevator Company and the results were also efficient, greatly reducing transportation cost and logistics used in the operation.
73

Experiences from Simulating TSP Clusters in the Simics Full System Simulator / Erfarenheter från simulering av TSP-kluster i full-system simulatorn Simics

Eriksson, Olle, Erlandsson, Emil January 2004 (has links)
TSP (or Telecommunication Server Platform) is a scalable, high availability cluster operating system developed by Ericsson for use in the telecommunications industry. This thesis describes an attempt to simulate a TSP cluster in the full system simulator Simics, and talks about some of the possibilities offered by such a setup and full system simulation in general. This attempt to simulate TSP was unsuccessful in completely booting the cluster in Simics, but some of the experiences and problems encountered are described. A proposed development environment for working with TSP in Simics is also presented, along with scripts that were created during this thesis to alleviate the working process. / TSP (eller Telecommunication Server Platform) är en skalbar, högt tillgängligt kluster-operativsystem utvecklat av Ericsson för användning inom telekommunikationsindustrin. Den här rapporten beskriver ett försök att simulera TSP-kluster i full-system simulatorn Simics, och beskriver en del av de möjligheter med detta och full-system simulering i allmänhet. Det här försöket att simulera TSP lyckades inte att fullständigt boota klustret i Simics, men några av de erfarenheter och problem som stöttes på är beskrivna. En föreslagen utvecklingsmiljö presenteras också, tillsammans med script som skapades under det här arbetet för att underlätta arbetet. / Olle Eriksson, Contact info at www.olle-eriksson.com Emil Erlandsson, Contact info at www.buglix.org
74

Utveckling av en metod för att implementera IPv6 i en existerande nätverksmiljö / Development of a method to implement IPv6 in a existing network environment

Svensson, Jonas, Bergman, Joel January 2011 (has links)
Den här rapporten tog sin början i det faktum att många företag och organisationer idag inte är insatta i vad IPv6 innebär och hur de ska gå tillväga för att implementera IPv6. Det fanns vid tillfället ingen komplett metod för hur en analys av ett nätverk gick till, vad som var viktigt att tänka på, vilka tekniker som fanns tillgängliga och hur dessa implementerades. För att underlätta framtida övergångar till IPv6 bestämde vi oss för att utveckla en generell metod som användaren kan följa och läsa sig till vad de behöver tänka på vid varje steg. Metoden ger också exempel på hur användaren kan göra analyser och undersökningar som leder fram till en lösning som kan fungera för deras behov. Metoden besvarade frågeställningen ”Vad behöver ett företag göra för att kunna implementera IPv6 i en existerande nätverksmiljö?” Övergången till IPv6 är igång och många tekniker är inte färdigutvecklade. För att ta fram lösningar som fungerar för olika scenarier gjordes efterforskningar på både IP version fyra och version sex samt vilka övergångs-tekniker som är att rekommendera. Ett antal övergångs-tekniker valdes ut och sattes upp i ett testlabb där IPv6-funktionaliteten verifierades. För att ta fram en metod som täckte upp de vanligaste scenarierna diskuterades frågan med Empir AB, ett företag som arbetar med IT-lösningar och som tillhandahåller egna tjänster. Deras nätverk analyserades och det arbetet låg till grund för utformningen av metoden. Eftersom alla tekniker i metoden testades i laborations-nätverket fastställdes IPv6-funktionalitet genom att testa olika tjänster över nätverket. Testerna visade att det var fullt möjligt att implementera IPv6 efter en steg för steg-modell. Resultatet av arbetet kan användas för att initiera och fullfölja en övergång till IPv6 då användaren har en metod att följa, rekommendationer på vad som behöver göras och föreslagna lösningar som kan implementeras enligt anvisningar. / This report began with the fact that many companies and organizations today do not have any or little knowledge about IPv6 and what it means, nor do they know how to implement it. At the time of writing there were no complete method for how an analysis of a network were done, what was important to think on and which techniques were available. To ease future transitions to IPv6, we decided to develop a general method that a user could follow step by step, with instructions for what to think on at each step. The method also gives examples on how the user could do an analysis and examinations, and it eventually leads to a solution based on their needs. The method answers the question "what does a company need to do to be able to implement IPv6 in an already existing network?" The transition to IPv6 is happening and many techniques is still in development. To be able to present solutions that work with different needs, research in IP version four, version six and in transfer techniques were done as well. A set of transfer techniques was chosen and set up in a lab network where IPv6 functionality was verified. To develop a method that covered most of the common scenarios, the question were discussed with Empir AB, a company that works with IT solutions that hosts their own services. Their network was analyzed and the result was the foundation for the method. Since all techniques in the method were tested in the lab network, the IPv6 functionality was verified by testing different services over the network. The tests showed that it was possible to implement IPv6 after a step by step model. The result of this work can be used to initiate and follow through with a transition to IPv6 since the user have a method to follow, recommendations to what needs to be done and proposed solutions that can be implemented after instructions.
75

K-ELITISTISK SELEKTION FÖR DISTRIBUERADE GENETISKA ALGORITMER / K-ELITISTIC SELECTION IN DISTRIBUTED GENETIC ALGORITHMS

Jonasson, Simon January 2015 (has links)
Genetiska algoritmer(GA)är en sökalgoritm som framlades av Holland (1975). GA efterliknar evolution; en mängd lösningar kombineras och muterar under loppet av flera generationer för att skapa en så bra lösning som möjligt. En vidareutveckling av GA är distribuerade genetiska algoritmer (DGA); en samling GA exekverar isolerat från varandra och med jämna mellanrum delar lösningarmed varandra. Detta arbete har undersökt hur DGA påverkas av k-elitism; att de k bästa lösningarna kopieras till nästa generation utan att förändras. En DGA har implementerats som löser handelsresandeproblem från problembiblioteket TSPLIB. Experimenten visade att k-elitism påverkar hur bra lösningar som produceras samt hur många generationer som krävs innan algoritmen slutar göra framsteg. Vissa värden på k gav i regel bättre resultat, och andra värden på k gav i regel sämre resultat. Det föreslås att mer forskning görs på området. Resultaten bör verifieras för andra variabeluppsättningar och migrationsfrekvensens betydelse bör undersökas djupare.
76

Effet du valproate sur l'expression du génome viral dans les cellules infectées par HTLV-1 / Effect of valproate on viral expression in HTLV-1 infected cells

Belrose, Gilda 07 January 2011 (has links)
L’HTLV-1 est l’agent étiologique de la TSP/HAM et de l’ATL. La TSP/HAM est une méningomyélite chronique d’évolution lente et progressive. La charge provirale HTLV-1 est corrélée à l’évolutivité de la maladie. La protéine virale Tax module la synthèse et la fonction de multiples protéines de la prolifération et de la survie des lymphocytes T infectés. L’expression virale n’est pas toujours détectable in vivo. Une modulation épigénétique par inhibiteurs d’HDAC a été proposée. Des travaux dans le modèle du BLV et in vitro dans l’infection à HTLV-1 ont conforté ce concept et conduit à un essai thérapeutique évaluant le VPA dans le traitement de la TSP/HAM, qui n’a pas montré d’impact sur la charge provirale. Nous nous sommes intéressés à l’effet du VPA sur les lymphocytes T CD4+ en culture, cibles du virus HTLV-1. L’expression du génome viral, surtout la balance entre les protéines Tax et HBZ a été étudiée avec ou sans VPA. Son expression serait corrélée à la charge provirale et à l’évolution de la TSP/HAM. Nous montrons qu’un tiers des cellules CD4+ infectées expriment Tax. Cette proportion augmente sous VPA. La détection de la protéine p19 est augmentée sous VPA. La stimulation par le VPA de la transcription sens du génome viral a été confirmée par quantification des messagers Tax et Gag alors que l’expression d’HBZ se trouve réprimée sous VPA. Les données cinétiques d’expression spontanée d’HBZ montrent l’existence d’un rétrocontrôle négatif exercé par HBZ sur l’expression de Tax et des gènes structuraux. Influer sur l’expression d’HBZ ouvre une voie nouvelle pour le traitement des maladies associées à HTLV-1. / HTLV-1 is the etiological agent of HAM/TSP and ATL. TSP/HAM is a chronic meningomyelitis with a course being slow and progressive. HTLV-1 proviral load correlates with disease progression. Tax protein modulates the synthesis and function of proteins involved in the regulation of infected T-lymphocytes proliferation and survival. Viral expression is not always detectable in vivo. An epigenetic modulation by the use of HDAC inhibitors has been proposed. A study in the BLV model and an in vitro study in a HTLV-1 infection have lead to a therapeutic assay in order to assess VPA in the treatment of HAM/TSP. This assay did not show any impact on the proviral load. We evaluated the impact of VPA treatment on viral genome expression in cultured lymphocytes, especially the balance between Tax and HBZ. A third of provirus-positive CD4+ T cells spontaneously became Tax-positive. The estimation rose up to two-thirds of Tax-positive infected cells when VPA was added. VPA enhanced Gag p19 protein release. VPA treatment enhanced and prolonged Tax mRNA expression, while it blocked HBZ expression. Our data are consistent with the hypothesis of a feed-back loop coordinating Tax and HBZ expression. Modulation of HBZ expression may impact the net outcome of VPA treatment on HTLV-1-infected cell proliferation and survival.
77

Rôle de la Thrombospondine-1 et du récepteur CD47 dans le développement de la fibrose rénale / Role of Thrombospondin-1 and CD47 receptor in renal fibrosis

Bigé, Naïke 25 September 2014 (has links)
La Thrombospondine-1 (TSP-1) représente l'un des principaux activateurs endogènes du TGF-?1 et possède des propriétés anti-angiogéniques et immunomodulatrices. L'un de ses récepteurs, le CD47, joue un rôle critique dans son effet anti-angiogénique et module l'inflammation. Après obstruction urétérale unilatérale (UUO), l'expression de la TSP-1 augmente, est corrélée à celle du TGF-?1 et du collagène III et décroît avec la réparation tissulaire qui accompagne la désobstruction urétérale. L'utilisation de souris knock-out pour la TSP-1 a permis de montrer qu'elle participe au développement des lésions tubulaires rénales en favorisant les altérations vasculaires et le recrutement des cellules inflammatoires. Cet effet pro-inflammatoire dépend, au moins en partie, du facteur chimiotactique MCP-1, de l'augmentation du rolling leucocytaire et de l'activation de la voie Th17. Les souris knock-out pour CD47 bénéficient également d'une protection tubulaire et vasculaire. Cependant, elles présentent une fibrose interstitielle accrue associée à une augmentation de l'expression de la TSP-1 et du TGF-?1 qui pourrait compromettre une éventuelle récupération rénale. L'étude préliminaire de modèles de néphroangiosclérose chez le rat et la souris révèle que la TSP-1 est surexprimée dans le parenchyme rénal au cours de l'hypertension artérielle. L'intensité de son expression est corrélée à la sévérité des lésions histologiques, suggérant son rôle physiopathologique. Ces résultats montrent que la TSP-1 et le récepteur CD47 participent au développement de la fibrose rénale et représentent donc des cibles thérapeutiques potentielles au cours des maladies rénales chroniques. / Thrombospondin-1 (TSP-1) is a major endogenous activator of TGF-β1 and has anti-angiogenic and immunomodulatory properties. One of its partners, receptor CD47, plays a critical role in its anti-angiogenic activity and also regulates inflammation. After unilateral ureteral obstruction (UUO), TSP-1 expression increases, correlates to TGF-β1 and collagen III expression and decreases with renal repair after desobstruction. Use of TSP-1 knock-out mice allowed us to demonstrate that TSP-1 favours renal injury by increasing vascular lesions and inflammatory cells recruitment. This pro-inflammatory effect depends, at least in part, on chemotactic factor MCP-1, increasing in leukocyte rolling and engagement of T cells in Th17 pathway. CD47 knock-out mice also benefit from tubular and vascular protection after UUO. However, they exhibit increased interstitial fibrosis associated with higher expression of TSP-1 and TGF-β1, which could compromise renal repair. Preliminary study of nephroangiosclerosis models in rats and mice revealed that TSP-1 expression is induced in renal tissue by arterial hypertension and is correlated to the severity of histological lesions, suggesting its physiopathological role. These results show that TSP-1 and CD47 are involved in renal fibrosis and that they represent potential therapeutic target in the management of chronic kidney disease.
78

Modely a metody pro svozové problému v logistice / Models and methods for routing problems in logistics

Muna, Izza Hasanul January 2019 (has links)
The thesis focuses on how to optimize vehicle routes for distributing logistics. This vehicle route optimization is known as a vehicle routing problem (VRP). The VRP has been extended in numerous directions for instance by some variations that can be combined. One of the extension forms of VRP is a capacitated VRP with stochastics demands (CVRPSD), where the vehicle capacity limit has a non-zero probability of being violated on any route. So, a failure to satisfy the amount of demand can appear. A strategy is required for updating the routes in case of such an event. This strategy is called as recourse action in the thesis. The main objective of the research is how to design the model of CVRPSD and find the optimal solution. The EEV (Expected Effective Value) and FCM (Fuzzy C-Means) – TSP (Travelling Salesman Problem) approaches are described and used to solve CVRPSD. Results have confirmed that the EEV approach has given a better performance than FCM-TSP for solving CVRPSD in small instances. But EEV has disadvantage, that the EEV is not capable to solve big instances in an acceptable running time because of complexity of the problem. In the real situation, the FCM –TSP approach is more suitable for implementations than the EEV because the FCM – TSP can find the solution in a shorter time. The disadvantage of this algorithm is that the computational time depends on the number of customers in a cluster.
79

Optimalizace expedice zboží z regálového systému logistického skladu / Optimization of dispatch of goods from rack system of logistics warehouse.

Chlup, Jiří January 2009 (has links)
The diploma thesis submitted solves problems of optimization of goods expedition from rack system of a logistic store. It concerns solution of a practical task which optimizes a passage route through the rack system and evaluates individual orders for creation of optimal expedition dispatching batch. The existing dispatching system, use of sources and creation of time schedule is being described at the beginning. Description of general practical solutions of seeking the shortest way through the graph through appointed nodes follows. Chosen solution and its practical implementation are introduced afterwards. Comparative tests with existing system and their evaluations are mentioned at the end of the thesis.
80

Využití umělé inteligence v podnikatelství / The Use of Artificial Intelligence in Business

Matus, Gabriel January 2016 (has links)
This work deals with traveling salesman problem (TSP) and examines it’s possibilities to use in business. It is about the optimization of the travel cost, saving time and unnecessary mileage. Part of the work is a program with a GUI written in program MATLAB. Program uses neural networks to calculate the most effective path between places, where the trader has to reach. It’s possible to use the algorithm for many purposes, e.g. distribution of goods, store management, planning of PCBs or rescue services. Program communicates with the Google Maps API server, which provides the actual information of the path.

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