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Pronostic de la performance d’Efficacité Energétique pour la prise de décision en maintenance dans les systèmes industriels / Energy efficiency-based prognostics for optimizing the maintenance decision-making in industrial systemsHoang, Anh 10 July 2017 (has links)
Aujourd'hui, la maîtrise de l'énergie est la question prépondérante pour la croissance économique des entreprises industrielles. En effet, l’énergie est une ressource qui se raréfie et qui devient de plus en plus coûteuse. L’optimisation énergétique est donc un défi majeur que doit relever les entreprises et principalement celles manufacturières pour supporter les exigences du développement durable. Cette optimisation est à construire prioritairement par une amélioration de l’efficacité énergétique (EE), c'est-à-dire réduire la quantité d'énergie requise pour produire des produits et des services. En regard de ce défi énergétique, l’objectif de cette thèse est d’investiguer la considération de l’efficacité énergétique et de sa prévision comme un nouvel indicateur pertinent dans la prise de décision en maintenance. En ce sens, nous proposons tout d'abord un concept de l’efficacité énergétique, appelé EEI (EE indicator), applicable aux différents niveaux d’abstraction d’un système industriel. Nous définissons ensuite une formulation générique permettant d’évaluer l'EEI (et son évolution) en prenant en compte les facteurs d’influence statiques et dynamiques. Cela nous amène à fonder un concept de performance d’efficacité énergétique, appelé REEL (Remaining Energy-Efficient Lifetime), représentant la durée de vie énergétique résiduelle. Pour prédire l’évolution potentielle de l’EEI qui permettra de calculer la REEL, une approche générique basée sur des approches de pronostics existantes est également développée. Ensuite, nous investiguons l'utilisation d’EE dans la prise de décision en maintenance conditionnelle (Condition-Based Maintenance, CBM). Enfin, toutes ces contributions sont validées sur la plateforme laboratoire TELMA / Among sustainability consideration, energy is today the key for economic growth in industrial systems. Energy resources are however limited and becomes more and more expensive. The energy optimization of manufacturing systems must therefore be considered as a major challenge to be compliant with environmental impact and management of energy resources. This should be reflected primarily by using energy efficiency (EE) as main key lever to deploy sustainability to plants, i.e. reduce the amount of energy required to provide products and services. With regards to this EE context, the aim of this thesis is to investigate the problem of considering energy efficiency and its prediction as a new indicator in maintenance decision-making. In that way, we develop first a concept of energy efficiency, called EEI (energy efficiency indicator), applicable to the different levels of abstraction of an industrial system. Then, we propose a generic formulation to evaluate the EEI (and its evolution) taking into account static and dynamic factors of influence. The temporal evolution of this indicator with respect to the degradation of the system is addressed in a predictive maintenance objective. It leads to found an energy efficiency performance concept called REEL (remaining energy-efficient lifetime), representing the residual energy lifetime. To predict the potential evolution of the IEE to calculate REEL, a generic approach based on existing predictive approaches is also developed. Next, we investigate the use of EE in CBM maintenance decision-making. Finally, all these contributions are validated on the TELMA platform
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Multi-constrained QoS Routing and Energy Optimization for Wireless Sensor Networks / Routage avec QoS multi-contraintes et optimisation de l'énergie pour réseaux de capteurs sans filTsiontsiou, Evangelia 15 December 2017 (has links)
La thèse porte sur la conception de protocoles de routage pour les réseaux de capteurs. Les problèmes de recherche du routage de données dans un réseau multi-sauts sont d’une part l’optimisation de l’énergie et d’autre part le routage sous contraintes de la qualité de service (QoS) multicritères (e.g., énergie, fiabilité, délai, …). Cette thèse apporte deux contributions par rapport à l’état de l’art : une optimisation d'un protocole de routage probabiliste pour l'équilibre de l'usage d'énergie et un protocole de routage capable de prendre en compte simultanément des métriques de QoS multiples. En effet, pour équilibrer la consommation de l’énergie du routage lorsque des chemins multiples existent, les protocoles de routage probabiliste existants affectent une probabilité de choix à chaque chemin, soit de façon empirique, soit proportionnelle au niveau de l’énergie disponible du chemin. Nous ne savions pas quelles sont les probabilités optimales qui permettent d’avoir la durée de vie maximale du réseau. Cette thèse a permis d’établir ces probabilités optimales à l’aide de la modélisation sous forme d’un problème d’optimisation linéaire. Quant au problème du routage multicritères, bien que des métriques multiples soient définies par RPL (un standard d’IETF), les protocoles existants choisissent la route soit sur une métrique, soit sur une fonction de coût combinant plusieurs (qui introduit par conséquent un biais de pondération), mais jamais plusieurs simultanément. Dans cette thèse, nous avons d’abord évalué numériquement les performances de l’approche « operator calculus algebra » introduit par R. Schott et S. Staples qui définit un algorithme efficace permettant de trouver tous les chemins satisfaisant les contraintes multiples dans un graphe , puis dérivé une version distribuée sur laquelle nous avons conçu un protocole de routage multi-métriques. Ces deux contributions ont été implémentées dans l’environnement Contiki et émulées/simulées sous Cooja (un logiciel permettant de simuler des protocoles des réseaux de capteurs) / In this thesis, we focus on routing protocols for Wireless Sensor Networks (WSNs). The main research problems in the domain of routing data packets in a multi-hop network are the optimisation of the energy and the routing under multi-criteria QoS constraints (e.g., energy, reliability, delay, …). To address these problems, this dissertation proposes two contributions. Firstly, an optimal probabilistic routing protocol which balances the usage of energy and secondly, a routing protocol which is able to simultaneously take into account multiple QoS metrics. In fact, for balancing the energy consumption between the multiple existing links, the existing probabilistic routing protocols assign a probability to each link, either in an empirical way or depending on proportional energy level of the path. We did not know what are the optimal probabilities which lead to the optimal network lifetime. Our first contribution proposes optimal probabilities by modeling and solving a linear programming problem. As for the multi-constrainted QoS routing problem, multiple metrics are defined by RPL (a standard of IETF) but the existing protocols chose paths either according to only one metric or using a single aggregated function with multiple metrics, but never all the metrics simultaneously. In this dissertation, we first evaluate the performance of the operator calculus algebra introduced by R. Schott and S. Staples which defines an efficient algorithm allowing to find all the paths which satisfy the multiple constraints in a graph, and secondly we proposed a distributed version of this algorithm based on which a routing protocol has been designed. Both contributions are implemented in Contiki environment and simulated/emulated under Cooja (a software designed for simulating protocols of WSNs)
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Influence of ABCA1 and ABCA7 on the lipid microenvironment of the plasma membranePlazzo, Anna Pia 02 July 2009 (has links)
Der ABC-Transporter ABCA1 ist unmittelbar in die zelluläre Lipidhomeostasie einbezogen, in dem er die Freisetzung von Cholesterol an plasmatische Rezeptoren, wie ApoA-I, vermittelt. Trotz intensiver Untersuchungen ist dieser molekulare Mechanismus nicht verstanden. Verschiedene Studien deuten daraufhin, dass durch die Aktivität von ABCA1 bedingte Veränderungen in der Lipidphase der äußeren Hälfte der Plasmamembran (PM) wichtig für die Freisetzung des Cholesterols sind. In der vorliegenden Arbeit wird die Lipidumgebung von ABCA1 in der PM lebender Säugetierzellen unter Anwendung der Fluoreszenzlebenszeitmikroskopie von fluoreszierenden Lipidsonden untersucht. Es wurde eine breite Verteilung der Fluoreszenzlebenszeiten der Sonden gefunden, die sensitiv gegenüber Veränderungen der lateralen und transversalen Organisation der Lipide ist. Im Einklang mit Studien an riesengroßen unilamellaren Vesikeln und Plasmamembranvesikeln weisen unsere Ergebnisse die Existenz einer größeren Vielfalt submikroskopischer Lipiddomänen auf. Die FLIM-Untersuchungen an ABCA1 exprimierenden HeLa-Zellen weisen eine die Lipidphase destabilisierende Funktion des Transportes aus. Dieses wurde unterstützt durch die Lipidanalyse von Fraktionen der PM. Auf der Basis unserer Untersuchungen und früheren Daten stellen wir die Hypothese auf, dass die Exponierung von Phosphatidylserin (PS) auf der Zelloberfläche ein zentrales Ereignis der ABCA1 bedingten Veränderungen ist. Allerdings zeigen vergleichende Studien an ABCA7 exprimierenden Zellen, dass dies nicht ausreicht, um die ABCA1 verursachten Veränderungen in der Lipidpackung der PM zu erklären. Unsere Ergebnisse beweisen, dass die Fähigkeit von ABCA1, den Cholesterolefflux zu vermitteln, auf durch den Transporter bedingte Veränderungen in der LP der PM zurückzuführen sind, die unabhängig von der Bindung von ApoA-1 sind und dieser vorausgehen. Diese Veränderungen sind notwendig für die Lipidierung von ApoA-1 und der Generierung von HDL-Partikeln. / The ABCA1 transporter organizes cellular lipid homeostasis by promoting the release of cholesterol to plasmatic acceptors such as ApoA-I. Despite intensive investigation, the molecular mechanism of such a process has not yet been clarified. In the present study we report on the analysis of the ABCA1 lipid microenvironment at the plasma membrane of living cells, by a novel approach based on fluorescence lifetime imaging microscopy (FLIM). In the plasma membrane of mammalian cells, a broad fluorescence lifetime distribution sensitive to treatments interfering with the membrane lateral and transbilayer organization was found. In agreement with investigations in giant unilamellar vesicles and giant plasma membrane vesicles, our results are consistent with the existence of a large variety of submicroscopic lipid domains. Based on that, FLIM in HeLa cells expressing ABCA1 revealed the destabilizing function of the transporter on the lipid arrangement at the membrane, indicating that lipid packing was a primary target of ABCA1 activity. This was corroborated by the analysis of plasma membrane fractions isolated by density fractionation. On the basis of our analysis and previous data, we speculate that the exposure of phosphatidylserine on the cell surface is a central event for ABCA1-dependent modifications. However, a comparative study of cells expressing ABCA7, the member of the ABCA subfamily with the highest homology to ABCA1, revealed that exposure of PS alone cannot account for the detected effects. Collectively, our data suggest that the ability of ABCA1 to promote cholesterol efflux is independent and precedes its actual binding to ApoA-I. Rather, ABCA1-induced plasma membrane modifications are necessary for the lipidation of ApoA-I and the generation of high density lipoprotein particles.
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Proposição de um modelo baseado em Customer Lifetime Value para a análise de melhorias no sistema produtivoCamargo, Luís Felipe Riehs 20 March 2009 (has links)
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Previous issue date: 20 / Nenhuma / Esta pesquisa propõe um método e um modelo matemático fundamentado na métrica Customer Lifetime Value para analisar conjuntamente as preferências e percepções dos
consumidores, a relação destas preferências com o sistema de produção e potenciais ações de melhorias no processo produtivo. O método de pesquisa empregado apresenta três fases, a primeira explora a literatura na busca de elementos relevantes ao objetivo proposto. A segunda fase propõe o modelo matemático e o método de avaliação de melhorias e a terceira fase aplica as propostas em um contexto real. Essa aplicação possibilita a avaliação da validade prática dos resultados para a empresa analisada e a análise de viabilidade de utilização do modelo e do método. Os três pilares de sustentação do modelo são os consumidores de um dado mercado com as suas necessidades e percepções em relação aos bens e serviços, as características atribuídas pela produção e as regras para análise do impacto da adoção de diferentes melhorias no sistema produtivo sobre o v / This research aims to propose a method and a mathematic model based on a metric Customer Lifetime Value to analyze jointly the consumer’s preferences and perceptions, the relation between preferences and productive system and potential improvements on productive process. The applied research method shows three stages: the first one explores the literature to find relevant elements for the proposed objective; the second one aims the mathematic model and the evaluation method of improvements and the last one applies all proposals in a real case. This case study allows to analyze practiced results generated by the model and the
method and to evaluate application viability analyses. The model is sustained by three fundamental elements: consumers, with their necessities and perceptions about the products and services desired; characteristics of the productive system; and rules to analyze the impact of adoption of different improvements on the productive on the Customer Lifetime Value. The method focuses on interf
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Étude de la fiabilité et du vieillissement d’un système de stockage par supercondensateurs pour l’alimentation partielle et ponctuelle d’un trolleybus grâce à la récupération de l'énergie de freinage : approche du composant au système de stockage / Study of reliability and aging of supercapacitor storage system for partial and punctual supplying of a trolley through the recovery of braking energy : component to the storage system approachKreczanik, Paul 13 April 2011 (has links)
Le premier objectif du projet HYBUS est d’intégrer un système de stockage par supercondensateurs dans un trolleybus permettant la récupération de son énergie de freinage afin d’assurer la continuité de l’alimentation des systèmes électriques embarqués. A terme un système de stockage plus conséquent est prévu pour permettre au trolleybus une autonomie de quelques mètres. Notre travail étudie la durée de vie de ce système. Plusieurs tests de vieillissement accéléré sur les supercondensateurs ont été mis en place au laboratoire AMPERE. Ces essais ont mis en évidence que le cyclage engendrait une forte accélération de la diminution de la capacité et de l’augmentation de la résistance série. Cependant, ces variations sont partiellement réversibles lors des phases de repos où une régénération s’opère. Une méthode se basant sur les dégradations observées en cours d’utilisation et les dégradations demeurant après régénération, a permis une mise en équation de l’évolution des paramètres internes des supercondensateurs. Un test d’endurance de systèmes complets de stockage a aussi été réalisé au laboratoire. Les résultats expérimentaux montrent une hétérogénéité du vieillissement due à l’existence d’importants gradients de température entre les composants. De ce fait, une nouvelle méthodologie d’équilibrage visant à égaliser les durées de vie de chacun des supercondensateurs a été mise au point. L’étude a donc contribué à une meilleure compréhension et évaluation du vieillissement des supercondensateurs dans le but d’améliorer la durée de vie de système de stockage de ce type. Une méthode est proposée pour estimer les dégradations en fonction des facteurs majeurs du vieillissement. / The first objective of the HYBUS project is to integrate a supercapacitor storage system in a trolleybus in order to ensure the continuity of onboard electrical systems supply. The aim is to integrate an energy storage system, composed by a huge number of supercapacitors, for the recovery of the braking energy of trolleybus and allow autonomy for several meters. Our work concerns the study of the lifetime of the storage system. Several accelerated aging tests on supercapacitors were developed in the AMPERE aboratory. These tests have shown that as far as ageing are concerned; the cycling is the major responsible. However, these changes are partially reversible during the rest time when regeneration phenomena are observed. A method based on the observed damage during cycling and the damage after regeneration, leads to a formal equation for the evolution of internal parameters of supercapacitors. An endurance test of complete storage systems was also performed in the laboratory. Experimental results show the heterogeneity of aging due to the existence of significant temperature gradients between components. As a result, a new balancing strategy to equalize the lifetime of each supercapacitors has been developed. In conclusion, our study has contributed to a better comprehension and evaluation of supercapacitors aging in order to improve the lifetime of this type of energy storage system. A method for the estimation of the supercapacitor lifetime has been also proposed.
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The Optimization of Solar Energy Harvesting in WSNLi, Zhitan January 2018 (has links)
In recent year, wireless sensor networks have gradually become an indispensable part of people's daily lives. Energy consumption and energy harvesting play an important role in these systems. In outdoor, there is no doubt that solar energy is more suitable to powering the wireless sensor nodes. Although the energy consumption of these systems has been greatly reduced and the lifetime of sensor nodes also be improved through the larger capacity of supercapacitor or larger size of solar panel. But it will generate another kind of squander, how to choose a suitable solar panel and supercapacitor is appearance in our view. In this paper, I optimized the solar energy harvesting system from two aspects of capacity of supercapacitor and size of solar panel. The objective of this thesis has shown that as small solar panel and supercapacitor as possible for a given load of these systems under low consumption condition. Here, I establish the simulation in Simulink of Matlab, and build a low-power consumption; high-security solar energy harvesting hardware system for monitoring environment in Sundsvall, Sweden. Through the comparison between the simulation and real monitor to verify the feasibility
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Durabilité des miroirs pour l'énergie solaire à concentration : étude des modes de vieillissement / Durability of mirrors for concentrating solar power : study of aging modesAvenel, Coralie 16 October 2018 (has links)
La durabilité des miroirs solaires est un point clé pour le développement des centrales solaires à concentration, du fait de l’investissement important, des 30 ans d’opération visés et des zones d’implantations aux climats agressifs. Ces travaux de recherche portent ainsi sur l’étude des modes de dégradation et de la durabilité de miroirs solaires en verre monolithiques ou laminés. Cette thèse a permis d’appliquer avec succès au CSP une méthodologie de prédiction de la durée de vie développée dans des domaines plus matures. Les corrélations entre les vieillissements accélérés et les expositions extérieures réalisées sur trois sites ont mis en avant le rôle prédominant de l’eau et de l’irradiance dans la dégradation des peintures de protection des miroirs monolithiques. Les essais en chaleur humide ont quant à eux été jugés trop agressifs pour les miroirs, considérant de plus les conditions climatiques des sites d’application potentiels. Les résultats expérimentaux des essais de vieillissements accélérés ont conduit à la détermination des paramètres cinétiques des miroirs inclus dans les relations mathématiques modélisant les principaux facteurs de stress identifiés précédemment. Les facteurs d’accélération ont ainsi été calculés pour des essais standards par rapport à des sites comportant des centrales CSP opérationnelles. Ce travail a permis au final d’estimer des durées de vie des miroirs sur les sites choisis, en considérant que seuls les facteurs de stress étudiés intervenaient dans la dégradation. / Durability of solar mirrors is a key point for the development of concentrating solar power plants, because of the large investment, the goal of 30 years lifetime and of the implantations areas with hostile climates. This research work concerns the study of degradation modes and of monolithic or laminated glass solar mirrors durability. This thesis allows to successfully apply to CSP a lifetime prediction method already developed in more mature fields. Correlations between accelerated ageing tests and natural outdoor exposures performed on three sites evidence the predominant role of water and irradiance in protection paints of monolithic mirrors degradation. Damp heat tests were evaluated too aggressive for mirrors, considering thus the climatic conditions of potential application sites. Experimental results of accelerated ageing tests lead to the determination of kinetic parameters included in mathematical relationships modelling the main stress factors previously identified. Acceleration factors were then calculated for standard tests compared to sites with operational CSP plants. This work finally allows to estimate lifetimes of mirrors on specific sites, assuming that only the studied stress factors take part in degradation.
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Konstrukce a realizace zařízení pro testování kluzných ložisek / Design and implementation of journal bearing test rigKučera, Petr January 2016 (has links)
This diploma thesis is dedicated to mechnical desing, fabrication and assembly of experimental bearing testing rig. First part of the document contains research of current knowlege in the field of bearing testing and desings of currently used machines. In second part is conception of the testing rig described. Third part contains description of design variations that were designed. In Discussion is comented choices of final variants. Last part is dedicated to functional verification of the whole testing rig by first series of the tests.
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Adoção da métrica do valor do cliente: fatores limitadores do processo no contexto empresarialRorato, Bruna 31 March 2016 (has links)
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Previous issue date: 2016-03-31 / UNISINOS - Universidade do Vale do Rio dos Sinos / Saber conduzir a base de clientes de maneira a tornar eficiente o investimento em marketing é um fator importante no processo estratégico das empresas hoje em dia. As empresas podem obter diversos ganhos ao adotar um modelo de gestão baseado na métrica do valor do cliente, tanto em fatores econômicos quanto em fatores que abordam o retorno do investimento em marketing. O objetivo geral deste estudo é identificar nas empresas pesquisadas os principais fatores que limitam a utilização da métrica valor do cliente nos processos estratégicos. O estudo buscou avaliar por meio da revisão bibliográfica e empresas pesquisadas como a métrica do valor do cliente está inserida no dia a dia das companhias analisadas, quais são os indicadores presentes nos processos e como os setores financeiro e marketing se relacionam quando o assunto em questão é “cliente”. Os temas valor do cliente (CE) e valor do cliente ao longo da vida (CLV) ainda apresentam diversas lacunas como a relação das estratégias de marketing interligadas com o retorno para a empresa, a interpretação dos investidores com referência as métricas de marketing e a real eficiência das estratégias de marketing. A análise sobre os fatores limitadores da utilização da métrica do valor cliente, bem como os indicadores utilizados pelas organizações, foi embasada através da coleta de dados qualitativa por meio de entrevistas, realizadas em três empresas pré selecionadas, com a alta gerência comercial, financeira e de marketing de cada, totalizando nove entrevistas e uma entrevista de apoio com um consultor financeiro especializado em valor de empresas. Como principais resultados da pesquisa aponta-se: falta de foco no valor do cliente na empresa, orientação estratégica somente no incremento de receita por meio de novos clientes, cliente visto como ativo intangível no processo estratégico e falta de conhecimento das métricas de marketing. Dentre estes aspectos, destacam-se os fatores limitadores decorrentes destas causas: o fator tecnológico, o fator cultural e o fator comunicação eficiente entre as áreas. / Knowing how to conduct customer base in order to make efficient marketing investment is an important factor in the strategic process of the companies today. Thecompanies can get many gains by adopting a management model based on metrics of customer equity, both on economic factors as factors that address the return on marketing investment. The aim of this study is to identify the companies surveyed the main factors that limit the use of measuring customers equity in strategic processes. The study evaluated through literature review and companies surveyed as the metric of customer equity is included on the day-to-day of the analyzed companies, which are the indicators present in the process and how the financial sectors and marketing relate when the subject matter is "customer". The Customer Equity issues (CE) and Customer Lifetime Value (CLV) still have several shortcomings such as relationship marketing strategies linked with the return to the company, the interpretation of investors with reference marketing metrics and the actual efficiency of strategies marketing. The analysis of the limiting factors of the use of customer equity metrics and indicators used by organizations, was based by qualitative data collection through interviews conducted in three pre selected companies with high commercial, financial and marketing management, totaling nine interviews and a supporting interview with an expert financial advisor in value companies. The main results on this research is pointed out: lack of focus on customer equity in the company, strategic guidance only on revenue growth through new customers, customer viewed as an intangible asset in the strategic process and lack of knowledge of marketing metrics. Among these aspects, it highlights the technological and cultural factor and efficient communication between the areas.
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Stochastic process customer lifetime value models with time-varying covariatesHarman, David M. 01 December 2016 (has links)
Customer lifetime value (CLV) is a forecasted expectation of the future value of a customer to the firm. There are two customer behavioral components of CLV that represent a particular modeling challenge: 1) how many transactions we expect from a customer in the future, and 2) how likely it is the customer remains active. Existing CLV models like the Pareto/NBD are valuable managerial tools because they are able to provide forward-looking estimates of transaction patterns and customer churn when the event of a customer leaving is unobservable, which is typical for most noncontractual goods and services.
The CLV model literature has for the most part maintained its original assumption that the number of customer transactions follows a stable transaction process. Yet there are many categories of noncontractual goods and services where the stable transaction rate assumption is violated, particularly seasonal purchase patterns. CLV model estimates are further biased when there is an excess of customers with no repeat transactions.
To address these modeling challenges, within this thesis I develop a generalized CLV modeling framework that combines three elements necessary to reduce bias in model estimates: 1) the incorporation of time-varying covariates to model data with transaction rates that change over time, 2) a zero-inflated model specification for customers with no repeat transactions, and 3) generalizes to different transaction process distributions to better fit diverse customer transaction patterns. This CLV modeling framework provides firms better estimates of the future activity of their customers, a critical CRM application.
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