Conselho Nacional de Desenvolvimento Científico e Tecnológico / This work analyzes a spin glass (SG) model with cluster in two versions: a classic version with Ising spins and in a fermionic version with spin operators. In this model, the basic entities are correlated clusters that interact each other disorderedly (intercluster interaction). It is also considered short-range interactions among spins belonging to the same cluster (intracluster interaction), which can be ferromagnetic (FE) or antiferro- magnetic (AF). Disordered intercluster interactions are analytically calculated by using the framework of Parisi one-step replica symmetry breaking. After this treatment, we get an effective single cluster model solved by exact diagonalization. The fermionic version of the model can introduce quantum fluctuations by means of a transverse magnetic field Γ. As a result, the linear susceptibility χ has a cusp at the transition temperature Tf and the specific heat Cv has a broad maximum at temperature T* about 20% above Tf . However, for Γ sufficiently high, this difference is greater. This behavior is observed by some authors for the compound LiHoxY1-xF4 at low concentration. Furthermore, the fermionic SG model with cluster in the grand canonical ensemble (where the chemical potential μ introduces charge fluctuations) is used to investigate the mechanisms responsible for the inverse freezing (IF). In this analysis, for a certain region of μ, a reentrance related to the inverse freezing arises. However, the increase of the FE intracluster interactions J0 can take the tricritical point to lower T, introducing a second-order IF transition. On the other hand, the Γ destroys gradually the inverse freezing. The necessary mechanisms for the emergence of inverse freezing transition are also studied using the cluster SG model in a classic version with Ising spins. This study is firstly conducted considering only firstneighbors intracluster interactions AF and in a second moment considering intracluster interactions among second neighbors, where it is possible to introduce intracluster geometrical frustration. The presence of antiferromagnetic intracluster interactions decreases the total magnetic moment of the clusters, leading to a PM phase with low entropy, favoring the appearance of inverse freezing. Moreover, the presence of geometrical frustration is contrary to the emergence of inverse freezing. / Este trabalho analisa um modelo de vidro de spin (VS) com clusters em duasversões: uma versão clássica com spins de Ising e uma versão fermiônica com operadores de spins. Neste modelo, as entidades básicas são clusters correlacionados que interagem entre si de modo desordenado (interação intercluster). Considera-se também interações de curto-alcance entre momentos magnéticos pertencentes ao mesmo cluster (interação intracluster), que podem ser ferromagnéticas (FE) ou antiferromagnéticas (AF). As interações desordenadas intercluster são calculadas analiticamente através do método das réplicas com aproximação de um passo de quebra de simetria de réplicas. Após o tratamento, chega-se a um modelo efetivo de um único cluster resolvido por diagonalização exata. A versão fermiônica do modelo pode introduzir flutuações quânticas por meio de um campo magnético transverso Γ. Como resultados, a curva da susceptibilidade magnéticaΓ em função da temperatura T apresenta um pico agudo na temperatura de transição Tf e a curva do calor específico Cv em função de T apresenta um máximo arredondado à temperatura T* cerca de 20% acima de Tf . Porém, para um Γ suficientemente alto, esta diferença é muito maior, comportamento que é observado por alguns autores para o composto LiHoxY1-xF4 a baixas concentrações. Além disso, o modelo VS fermiônico com clusters no ensemble grão-canônico (onde o potencial químico μ introduz flutuações de carga) é usado para investigar os mecanismos responsáveis pelo congelamento inverso. Nesta análise, para uma certa região de μ, uma reentrância relacionada ao congelamento inverso surge. Entretanto, o aumento das interações FE intracluster J0 pode levar o ponto tricrítico para valores de T mais baixos, fazendo com que uma transição reentrante de segunda-ordem apareça. Por outro lado, o efeito de Γ é destruir o congelamento inverso gradativamente. Os mecanismos necessários para o surgimento da transição congelamento inverso também são estudados através do modelo de VS com clusters em uma versão clássica utilizando spins de Ising. Este estudo é realizado primeiramente considerando somente primeiros vizinhos intracluster AF e em um segundo momento considerando interações intracluster entre primeiros e segundos vizinhos, onde é possível introduzir frustração geométrica intracluster. A presença de interações antiferromagnéticas intracluster diminui o momento magnético total dos clusters, levando a uma fase PM de baixa entropia, favorecendo o aparecimento de congelamento inverso. Por outro lado, a presença de frustração geométrica é contrária ao surgimento de congelamento inverso.

Le cluster d’étain [(BuSn)12O14OH6]AMPS2 a servi de nanobrique pour l’élaboration de matériaux auto-réparants et themoformables. Le matériau hybride synthétisé est un élastomère capable de récupérer l’ensemble de ses propriétés mécaniques après avoir subi un endommagement mécanique, allant de la fissure de quelques μm à un endommagement drastique. En plus d’être réparable le matériau est recyclable, ce qui est un comportement exceptionnel pour un élastomère. Les liaisons ioniques entre le cœur du cluster et ses ligands qui connectent entre elles les chaînes macromoléculaires sont à la fois suffisamment fortes pour permettre de réticuler les chaînes et d’atteindre les propriétés d’un élastomère et suffisamment labiles pour permettre au réseau d’être dynamique. Les propriétés mécaniques des matériaux ont été évaluées mettant en évidence la nature dynamique du réseau à l’échelle macroscopique. La RMN DOSY a permis de mettre en évidence la dynamique dans le réseau à l’échelle moléculaire confirmant le rôle du cluster. Afin d’obtenir des matériaux avec des modules mécaniques élevés, des copolymères constitués de blocs rigides de polystyrène et de blocs souples de poly(acrylate de n-butyle) au sein duquel le cluster fonctionnel a été incorporé assurant la réticulation dynamique du matériau ont été synthétisé par polymérisation RAFT . Ces systèmes possèdent des propriétés de réparation thermostimulée, de thermoformage et peuvent être recyclés, contrairement aux élastomères thermoplastiques conventionnels. Cette stratégie de synthèse permet d’augmenter le module élastique G’ de 0,1 MPa pour l’élastomère à 500 MPa pour les copolymères tout en conservant un caractère dynamique. / A butyltin oxo-cluster macrocation, [(BuSn)12O14(OH)6]AMPS2, has been chosen as the Nano Building Block to create self-healing and malleable materials. The functional ligands enable the cluster to ionically cross-link poly(n-butyl acrylate) chains. The resulting hybrid material is an elastomer possessing properties which enable it to recover from damages: from a few μm depth cut to a dramatic failure. In addition, this material is recyclable, which is an exceptional property for an elastomer. The origin of the dynamic behavior is the ionic interaction between the cluster core and its ligands which are connected by macromolecular chains. Such interactions are strong enough to cross-link the polymer and consequently exhibit rubber-like elasticity behavior as well as render it labile enough to allow dynamic bond recombination leading to a dynamic network. Mechanical properties of the material (DMTA, Tensile Tests, and Relaxation Tests) have been evaluated and verify the macroscopic dynamic nature of the network. DOSY NMR experiments demonstrate the molecular dynamic of the networks, attesting the key role of the cluster. Concentrating on the development of high mechanical modulus materials with dynamic network, copolymers using hard blocks made of polystyrene and soft blocks of poly(n-butyl acrylate) which are cross-linked by the cluster have been synthetized. Such materials have thermo-stimulated healing properties, can be recycled, and are malleable, which is not the case for conventional thermoplastics. This synthesis strategy enables to raise the elastic modulus of the elastomer from 0.1 MPa to 500 MPa while maintaining the co-polymers dynamic properties.

The IEEE Standard for Gigabit Networking was accepted in June 1998 and ratified as IEEE 802.3z. This standard uses considers an optical cable for signal transmission. One year later a new standard for Gigabit Ethernet over unshielded twisted pair of the 5th category was certified under the name 802.3ab. Nowadays, there are a couple of younger and older studies about Gigabit Ethernet technology and performance. This Meta Analysis is intended to put the main results altogether into one document suitable for a proper choice of gigabit networking equipment for cluster computers.

The objective of this thesis is the evaluation of selected coefficients of the cluster analysis when determining the optimal number of clusters. The analytical evaluation is performed on 20 independent real datasets. The analysis is made in statistical SYSTAT 13.1 Software. The application of coefficients RMSSTD, CHF, PTS, DB and Dunn's index on real datasets is the main part of this thesis, because the issue of evaluating the results of clustering is not devoted sufficient attention in scientific publications. The main goal is whether the selected coefficients of clustering can be applied in the real situations. The second goal is to compare selected clustering methods and their corresponding metrics when determining the optimal number of clusters. In conclusion, it is found that the optimal number of clusters determined by the coefficients mentioned above cannot be considered to be correct since, after application to the real data, none of the selected coefficients overcome the success rate of 40%, hence, the use of these coefficients in practice is very limited. Based on the practical analysis, the best method in identifying the known number of clusters is the average linkage in connection with the Euclidean distance, while the worst is the Ward's method in connection with the Euclidean distance.

Les clustomésogènes sont une nouvelle classe de cristaux liquides hybrides multifonctionnels découverts dans l'équipe CSM de l'Institut des Sciences Chimiques de Rennes en 2008. Ils sont constitués d'un cœur inorganique - des clusters de métaux de transition - auquel sont associés, de manière covalente ou électrostatique, des ligands organiques pro-mésogéniques. Ces matériaux hybrides associent les propriétés d'auto-assemblage des cristaux liquides aux propriétés intrinsèques des clusters métalliques. Le présent travail s'articule autour de clustomésogènes contenant des clusters octaédriques de molybdène, phosphorescents dans le rouge-proche infra-rouge, et aux rendements quantiques compris entre 10% et 50%. Ils sont synthétisés par approche ionique en vue de leur intégration dans des dispositifs optiques. La démarche consiste à rationaliser les relations structures-propriétés afin de contrôler l'arrangement des clustomésogènes à l'échelle nanométrique. Nous créons ainsi des états nématiques sur de larges gammes de température. Le transfert de ces systèmes dans des cellules électro-optiques est renforcé par leur miscibilité dans un certain nombre de cristaux liquides commerciaux. La nature et la concentration de ces derniers permet l'ajustement des températures de fonctionnement et le contrôle de la viscosité de l'état cristal-liquide. Nous montrons qu'il est possible de faire commuter l'intensité de photoluminescence des clustomésogènes de 50% par l'application d'un champ alternatif à la manière des systèmes d'affichage. L'intégration au sein de diodes électroluminescentes constitue le dernier volet de ce travail. La maîtrise de leur structure permet d'envisager leur potentiel dans des dispositifs d'éclairage. L'ensemble de ces études ouvre la voie aux clustomésogènes de molybdène comme alternative réaliste aux émetteurs inorganiques rouges actuels. / Clustomesogens are a new class of hybrid liquid crystals developed since 2008 in our laboratory. They are a combination of an inorganic core, namely transition metal clusters, linked with promesogenic organic ligands through covalent or electrostatic interactions. These hybrid materials associate liquid crystals self-assembling abilities to the metallic clusters intrinsic properties. This work present octahedral molybdenum cluster based clustomesogens, emitting, through phosphorence mechanisms, in the deep red area and exhibiting 10% to 50% quantum efficiency. These materials are produced via an ionic approach by replacing the alkali cations of the ternary solid state compounds with tailored promesogenic organic ones. The ambition of this work is to rationalize the structures-properties relationship to control, at the nanometric scale, the clustomesogens organization. This approach allows us to observe nematic liquid crystalline phases over a wide range of temperatures. As these compounds are miscible with commercial nematic liquid crystals, we could envision their use as emissive species in the design of electroswitchable luminescent liquid crystal cells. By changing the type and concentration of commercial liquid crystals, we could adjust the operating temperature range as well as the viscosity of the mixture. We also establish that it is possible to modulate the clustomesogens' photoluminescence by 50% by applying an alternative electric field, as in display devices. In the last part of this work, we study the integration of clustomesogens as the emissive species into electroluminescent diodes. Being able to control their structure should allow their use in lighting devices. These works pave the way for using Molybdenum clustomesogens as an alternative to inorganic compounds presently used as red light emitters.

The aim of this thesis is to examine the cluster analysis ability segment the data set by selected methods. The data sets are consisting of quantitative variables. The basic criterion for the data sets is that the number of classes has to be known and the next criterion is that the membership of all object to each class has to be known too. Execution of the cluster analysis was based on knowledge about the number of classes. Classified objects to individual clusters were compared with its original classes. The output was the relative success of classification by selected methods. Cluster analysis methods are not able to determine an optimal number of clusters. Estimates of the optimal number of clusters were the second step in analysis for each data set. The ability of selected criteria identify the original number of classes was analyzed by comparing numbers of original classes and numbers of optimal clusters. The main contribution of this thesis is the validation of the ability of selected cluster analysis methods to identify similar objects and verify the ability of selected criteria to estimate the number of clusters corresponding to the real file distribution. Moreover, this work provides a structured overview of the basic cluster analysis methods and indicators for estimating the optimal number of clusters.

Atualmente, o paradigma multicore é uma tendência fortemente estabelecida também na área de sistemas embarcados. O grau de paralelismo provido por tal arquitetura tem sido a principal causa de avanços de performance na área além de economia de energia e potência. Entretanto, para obter paralelismo eficiente desta arquitetura não é uma tarefa simples. Assim, desenvolvedores propuseram diversos modelos de ambientes de programação tentando prover o máximo de transparência possível. No nível do hardware, este crescente aumento no número de componentes dentro chip cria um problema de gerenciamento a ser tratado. No contexto deste cenário complexo, esta tese propõe o uso de abordagens de gerenciamento de recursos para aumentar a eficiência, levando em consideração tanto performance quanto consumo de energia, de ambientes MPSoC em diferentes níveis. Além disso, estas abordagens tem em comum a noção de clusterização, a qual tenta agregar recursos logicamente de acordo com as demandas da aplicação. Primeiramente no nível do processador/aplicação, é proposto um hardware dinamicamente adaptável para suportar modelos de programação paralelos distintos sem nenhum sobrecusto computacional uma vez que todo o processo é completamente transparente para o programador. Ainda neste ambiente, onde aplicações distintas podem ser executadas, é proposto um mecanismo de escalonamento visando gerenciamento de recursos para aumentar a performance chamado Processor Clustering. São propostas quatro diferentes políticas de mapeamento de recursos que tiram vantagem de aspectos distintos da natureza paralela das aplicações e das restrições arquiteturais do sistema. Entretanto, algumas aplicações tem demandas de memória mais altas do que demandas computacionais. Logo, uma abordagem similar pode ser utilizada no nível da hierarquia de memória. Neste caso, o objetivo é redistribuir recursos de memória de acordo com as demandas da aplicação. Redistribuição de memória é explorada tanto em tempo de projeto quanto em tempo de execução. Um mecanismo de mapeamento de distribuição é proposto baseado na quantidade de requisições de acesso à memória externa. Finalmente, é proposto um mecanismo de tolerância à falhas baseado em gerenciamento de recursos para memórias distribuídas dentro do chip em NoCs. É introduzido um modelo de Reliability Clustering que tira proveito da infraestrutura da NoC. Neste caso, os roteadores tem conhecimento dos blocos com falhas e blocos redundantes. Baseado neste conhecimento, o mecanismo é capaz evitar altas latências de acesso à memória. / The multicore paradigm is a solid trend nowadays, also in the field of embedded systems. The degree of parallelism provided by such architecture has been the foundation of performance advancements in the field as well as for power and energy savings. However, to obtain efficient parallelism of such architecture is not an easy task. Therefore, developers come up with several proposals of programming environments trying to provide as much transparency as possible. On the hardware side, this increasing number of on-chip components creates a management issue to be handled. In the context of this complex scenario this thesis proposes the use of resource management approaches to improve the efficiency, regarding both performance and energy consumption, of MPSoC environments at different levels. Also, these approaches have in common the notion of clustering, which tries to logically aggregate resources according to application demands. First, at the processor/application level, we propose a dynamically adaptable hardware to support distinct parallel programming models at no computational overhead, since the entire process is completely transparent to the programmer. Also, in this environment, where distinct applications can be executed, we propose a resource-aware scheduling mechanism to improve performance named Processor Clustering. We propose four different resource mapping policies that leverage on distinct aspects of the parallel nature of the applications and on architecture constraints. However, some applications have higher memory demands than computational demands. Therefore, a similar approach can be used at the memory level. In this case, we aim at redistributing memory resources according to application demands. We explore memory redistribution at both design time and runtime and propose a distribution mapping mechanism based on the amount of off-chip memory requests. Finally, we propose a resource-aware fault-tolerance mechanism for distributed on-chip memories in NoCs. We introduce a Reliability Clustering model that leverages on the NoC infrastructure. In this case, the routers have knowledge of faulty blocks and redundancy blocks and, based on that, they are able to avoid higher memory access latency.

Esta dissertação de mestrado propõe uma nova política de distibuição de requisições em cluster de web services, denominada Política Performance. Essa política provê uma distribuição transparente, flexível e dinâmica das requisições na plataforma em que é executada. Um estudo sistemático também é realizado para analisar a qualidade dos índices de carga empregados no contexto de web services e propõe um novo índice capaz de representar fielmente o desempenho dos web services e encapsular a complexidade estrutural da plataforma. Também é proposto em Módulo Gerenciador de Energia capaz de prover sustentabilidade à plataforma, reduzindo o consumo de energia elétrica sem prejudicar a alta confiabilidade na distribuição das requisições e com baixo impacto no tempo médio de resposta. Os estudos experimentais realizados neste trabalho mostraram que a Política Performance permitiu um melhor desempenho no atendimento das requisições realizadas à plataforma. EStes resultados referem-se a um desempenho superior a 70% no tempo médio de resposta, quando comparado ao desempenho demosntrado pela política padrão do Mod_cluster. O Módulo Gerenciador de Energia proporcionou uma redução de aproximadamente 30% no consumo de energia da plataforma mantendo a alta confiabilidade na distribuição das requisições / The Master\'s dissertation proposes a new for distribution of requests in cluster of web services, named policy Performance. This policy provides a transparent flexible and dynamic distribution of requests on the plataform. A systematic study is also conducted to example the quality of load indices used in the context of web services., and proposes a new index that accurately represent the performance of web services and encapsulate the complexity structural of the plataform. Also proposed is an Energy Manager Module capable of providing sustainability to the plataform, reducing power consumption without sacrificing high reliability in the distribution of request and low impact on the average response time. Our main results show that policy Performance has a better performance in handling requests sent to the plataform. Our results show a gain of performance higher than 70% in average responswetime when compared to the perormance demonstrated by the defaut policy Mod_cluster. The Power Manager Module reduced byapproximately 30% the energy consumption of the plataform even keeping the high reliability in the distribution of requests

[EN] Literature on clusters has evolved over time, together with different approaches where they have been used. However, there was not a quantitative analysis of the current state of that evolution. In this research project, a methodology based on bibliometric analysis has been used; this methodology is called "bibliographic coupling", and is based on the identification and quantification of common references mentioned in the documents under study. This has allowed us to identify and explain the most relevant approaches in which the concepts of cluster and industrial district were used in 2013. One of the most common demands shown in this literature, or in the approaches analyzed, such as Evolutionary Economic Geography, is the need for more cases of evolutionary (or dynamic) analysis of the study of clusters or industrial districts. Since present literature lacks an evolutionary analysis of Spanish cluster through its patents, in this research project the cluster toy-plastic of "Foia de Castalla" is analysed. This analysis is based on knowledge of the cluster environment, the development of those companies which it is made of and the evolution of skills and capabilities for the analysis of its patents; their patterns and processes of innovation will be better known, providing, thus, literature with a new analysis on the evolution of clusters. Therefore, this doctoral thesis contributes to the literature on clusters evolution with two elements; firstly a case of evolutionary analysis based on patents and secondly a quantitative procedure, "bibliographic coupling", applied to this literature; the main approaches or lines of research in this area being, thus, identified. / [ES] La literatura sobre los clusters ha ido evolucionando a lo largo del tiempo y de distintos enfoques que los han ido utilizando, sin embargo no existía un análisis cuantitativo de la situación actual de dicha evolución. En el presente trabajo de investigación se ha utilizado una metodología mediante el análisis bibliométrico denominado "apareo bibliográfico", basada en la identificación y cuantificación de las referencias bibliográficas comunes citadas por los documentos objeto de estudio, que nos ha permitido señalar y explicar los enfoques más relevantes que utilizan los conceptos de cluster y distrito industrial en el año 2013. Una de las demandas más extendida, dentro de esta literatura o por ejemplo de los enfoques detectados como es el caso de la Geografía Económica Evolutiva, es la necesidad de más casos de análisis evolutivos (o dinámicos) para el estudio de los clusters o distritos industriales. Dado que no existen en la literatura actual ningún caso de cluster español analizado evolutivamente a través de sus patentes, en el presente trabajo de investigación se ha analizado desde dicha perspectiva el cluster del juguete-plástico de la Foia de Castalla, dicho análisis está basado en el conocimiento del entorno del cluster, el desarrollo de las empresas que lo forman y la evolución de sus habilidades y capacidades por el análisis de sus patentes, para conocer mejor sus patrones y procesos de innovación. Aportando así un nuevo caso de análisis a la literatura sobre la evolución de los clusters. Por tanto, la presente tesis doctoral aporta a la literatura sobre la evolución de los clusters dos elementos, por un lado un caso de análisis evolutivo basado en las patentes y por otro un procedimiento cuantitativo "el apareo bibliográfico" aplicado a dicha literatura lo que permite detectar los principales enfoques o líneas de investigación en esta área. / [CAT] La literatura sobre els clústers ha anat evolucionant al llarg del temps i de diferents enfocaments que els han anat utilitzant, no obstant açò no existia una anàlisi quantitativa de la situació actual d'aquesta evolució. En el present treball de recerca s'ha utilitzat una metodologia basada en l'anàlisi bibliomètric denominat "apariat bibliogràfic", basada en la identificació i quantificació de les referències bibliogràfiques comunes citades pels documents objecte d'estudi, que ens ha permès assenyalar i explicar els enfocaments més rellevants que utilitzen els conceptes de clúster i districte industrial l'any 2013. Una de les demandes més estesa, dins d'aquesta literatura o per exemple dels enfocaments detectats com és el cas de la Geografia Econòmica Evolutiva, és la necessitat de més casos d'anàlisis evolutives (o dinàmiques) per a l'estudi dels clústers o districtes industrials. Atès que no existeixen en la literatura actual cap cas de clúster espanyol analitzat evolutivament a través de les seues patents, en el present treball de recerca s'ha analitzat des de la perspectiva el clúster del joguet-plàstic de la Foia de Castalla. Aquesta anàlisi està basada en el coneixement de l'entorn del clúster, el desenvolupament de les empreses que el formen i l'evolució de les seues habilitats i capacitats per l'anàlisi de les seues patents, per a conèixer millor els seus patrons i processos d'innovació. Així s'aporta un nou cas d'anàlisi a la literatura sobre l'evolució dels clústers. Per tant, la present tesi doctoral aporta a la literatura sobre l'evolució dels clústers dos elements: d'una banda, un cas d'anàlisi evolutiva basada en les patents, i d'altra banda, un procediment quantitatiu, "l'apariat bibliogràfic", aplicat a aquesta literatura la qual cosa permet detectar els principals enfocaments o línies de recerca en aquesta àrea. / Caja Meri, P. (2015). La evolución del cluster y su análisis: Estudio bibliométrico del concepto y aplicación de metodologías evolutivas en casos aplicados [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/52245 / TESIS

The scope of this thesis is to design and implement a system for deploying, managing and monitoring a Raspberry Pi cluster using Nix technologies. The thesis describes the benefits of the functional approach of Nix and the subsystems that are based on it. The thesis also results in a supporting web application, providing an intuitive environment for working with cluster configuration deployments and clearly displaying information about the utilization of individual nodes using dashboards. The final part of the thesis is devoted to testing cluster performance using sample distributed computing jobs.