To see the other types of publications on this topic, follow the link: Clusters.
Dissertations / Theses on the topic 'Clusters'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Clusters.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Jeltema, Tesla Erin. "Cosmology with clusters of galaxies : high-redshift clusters and the evolution of cluster substructure." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28372.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2004.Includes bibliographical references (p. 85).
Clusters of galaxies have become an important cosmological tool, yet we do not un-erstand many aspects of their formation and development. In this thesis, I pursue two projects aimed at using clusters to constrain cosmology and better understanding cluster evolution. First, I examine the Chandra observation of MS1054-0321. MS1054-0321 is the highest redshift cluster in the Einstein Medium Sensitivity Survey (EMSS), and it was one of the first high-redshift clusters observed with Chandra. I confirm that this cluster is hot and massive, although its temperature is slightly lower than inferred previously. I also detected an iron line in this cluster, one of the first detections of iron in a cluster at these redshifts, with an abundance consistent with early enrichment of the ICM. MS1054-0321 exhibits significant substructure, which I study in detail for the first time. In X-rays, it appears to be a nearly equal mass double cluster in the process of merging. Both the cluster galaxies and mass associated with the western subclump are offset from the X-ray peak, possibly indicating that the gas in the subclump is being stripped off as it falls into the cluster. Despite the lower temperature, I find that the detection of this cluster in the EMSS constrains Qm to be less than one.
(cont.) In the second project, I investigate the evolution of cluster substructure with redshift, quantifying for the first time cluster structure out to z [approx.] 1. My sample includes 40 X-ray selected, luminous clusters from the Chandra archive, and I quantify cluster morphology using the power ratio method (Buote & Tsai 1995). I find that, as expected qualitatively from hierarchical models of structure formation, high-redshift clusters have more substructure and are dynamically more active than low-redshift clusters. Specifically, the clusters with z > 0.5 have significantly higher average third and fourth order power ratios than the lower redshift clusters. This observation of structure evolution indicates that dynamical state may be an important systematic effect in cluster studies seeking to constrain cosmology, and when calibrated against numerical simulations, structure evolution will itself provide interesting bounds on cosmological models.
by Tesla Erin Jeltema.
Ph.D.
2
Junior, Paulo Vanderlei Cassanego. "Governança em clusters de negócios: um estudo em clusters do Rio Grande do Sul." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/12/12139/tde-06012015-120214/.
Full textAbstract:
Esta tese teve como objetivo apresentar quais os elementos que devem constar em um modelo descritivo para representar o que ocorre na realidade na governança em clusters. Para atingir este objetivo desenvolveu-se uma pesquisa para compreender que elementos eram considerados por pesquisadores ao escreveram sobre a governança de aglomerados produtivos. De posse destes dados, o material resultante foi classificado considerando sua natureza. Se descritivos ou normativos. Assim foram constituídos os Elementos da Governança em Cluster com sua conceituação a partir do que indica a literatura da área. Os Elementos da Governança, a saber: Estrutura da Governança, Funções da Governança, Mecanismos /Meios da Governança, Objetivos da Governança, Agentes da Governança e Requisitos da governança. Após, para atingir o objetivo da Tese, fez-se necessária a confrontação das informações teóricas com dados empíricos. Então se desenvolveu pesquisa em 5 Clusters no Estado Rio Grande do Sul. Foram estudados os seguintes casos: Cluster de Doces, na região de Pelotas-RS; Cluster Bovinocultura de Corte, na região da Campanha Gaúcha; Cluster Vitivinícola, na Região da Fronteira Oeste de Campanha; Cluster Moveleiro, na Região Central do Estado; e Cluster Metal-Mecânico. Na Serra Gaúcha. Os dados coletados constituíram-se em um modelo descritivo visando representar como estão apresentados os Elementos da Governança na realidade. A Estrutura da Governança foi definida como a forma como se organiza a governança em um cluster. De forma hierárquica ou heterárquica, apresentando firmas independentes que operam como uma entidade única. A Função da Governança foi definida como o ato de influenciar a tomada de decisão das empresas no aglomerado, indicando formas de interação entre as organizações. Os Mecanismos da Governança foram definidos como contratos formais e informais que organizam o relacionamento entre organizações em um cluster. O Objetivo da Governança foi definido como Garantir vitalidade do agrupamento compondo competitividade e maximização do valor para toda a cadeia de produção. Os Agentes da Governança foram definidos como empresas independentes, ligadas por vínculos de proximidade geográfica, relacionamento transacional, processos competitivos e/ou cooperativos, governo local, instituições científicas e de apoio. Como requisito para a existência de Governança foi definido que a confiança é o principal atributo.This thesis aims to show what elements should be included in a descriptive model to represent what actually occurs in governance in clusters. To achieve this goal developed a survey to understand what factors were considered by the researchers wrote about the governance of production clusters. Using these data, the resulting material was classified considering their nature. If descriptive or normative. Thus were formed the Elements of Governance Cluster with its concept from the literature would suggest the area. Elements of Governance, namely: Governance Structure, Functions Governance Mechanisms / Media Governance, Governance Goals, Agents and Governance Requirements governance. After, to achieve the objective of the thesis, it was necessary to confrontation of theoretical information with empirical data. Then developed in 5 research clusters in Rio Grande do Sul state the following cases were studied: Cluster Candy, in the region of Pelotas; Cluster Beef Cattle in the Campanha Gaucha region; Wine Cluster in the Border Campaign West Region; Cluster Furniture in the State Central Region; Cluster and Metal-mechanic. In the Serra Gaucha. The data collected consisted of a descriptive model, to represent how the elements are shown Governance in reality. The Structure of Governance was defined as how governance is organized in a cluster. Hierarchical or heterarchical form, with independent firms that operate as a single entity. The Role of Governance has been defined as the act of influencing the decision making of firms in the cluster, indicating ways of interaction between organizations. The Mechanisms of Governance were defined as formal and informal contracts that organize the relationship between organizations in a cluster. The Purpose of the Governance was set to ensure the vitality and competitiveness cluster composing maximizing value for the whole chain of production. Agents of the Governance were defined as independent companies linked by bonds of geographical proximity, transactional relationships, competitive and / or cooperative processes, local government, scientific institutions and support. As a requirement for the existence of Governance has been defined that trust is the main attribute.
3
Contini, Emanuele. "Galaxy populations in clusters and proto-clusters." Doctoral thesis, Università degli studi di Trieste, 2014. http://hdl.handle.net/10077/9964.
Full textAbstract:
2012/2013The aim of my Thesis is to explore the physical properties of the galaxy population in clusters and proto-clusters. A large number of physical processes plays an important role in the formation and evolution of galaxies: cooling, that allows the condensation of gas in the centre of dark matter haloes; star formation, that converts cold gas in stars; feedback from Active Galactic Nuclei (AGN), that prevents the gas in the central regions of haloes from "over-cooling"; feedback from Supernovae, which liberates energy in the surrounding, mixing the gas and enriching it with heavy metals. Galaxy clusters are special environments in which additional important processes take place, and play an important role in the evolution of the cluster galaxy population. Galaxy merging, harassments, tidal interactions, ram pressure stripping and strangulation are all processes acting in dense environments such as clusters of galaxies. I will take advantage of a {\it state of the art}-semi-analytic model of galaxy formation and of a set of 27 high-resolution dark matter only simulations: the semi-analytic model is based on physically motivated and observationally constrained prescriptions for the physical processes listed above and makes use of merger-trees extracted from the simulations to generate mock catalogues of galaxies. First, I make use of this set of simulations to carry out a statistical study of dark matter substructures. In the framework of modern theories of galaxy formation, dark matter substructures can be considered as the birth-sites of luminous galaxies. Therefore, the analysis of subhaloes, and in particular of their mass and spatial distributions, merger and mass accretion histories, provides important information about the expected properties of galaxies in the framework of hierarchical galaxy formation models. I have studied the amount and distribution of dark matter substructures within dark matter haloes, focusing mainly on the measured properties of subhaloes as a function of the mass and physical properties of their parent haloes, and redshift. I show that the fraction of halo mass in substructures increases with increasing mass, reaching $10 \%$ for haloes with mass of the order of $10^{15} \,M_{\odot} \hm$. The scatter in the relation is driven by halo concentration, with less concentrated haloes having larger fractions of mass in substructures. Most of this mass is locateted in the external regions of the parent haloes, in relatively few, but massive subhaloes, thus giving rise to a mass segregation which appears to be stronger at increasing redshift. Tidal stripping is found to be the process responsible for that. In fact, haloes that are more massive at the time of accretion, and that are supposed to host more luminous galaxies, are brought closer to the centre on shorter time-scales by dynamical friction, and therefore suffer of a more significant stripping. The results confirm that the main properties of galaxies, such as luminosity or stellar mass, are related to the mass of subhalos at infall, as found in previous studies.. The main results discussed in this part of the Thesis have been published in Contini et al. (2012), MNRAS.420.2978C. In a second part, I describe the implementation of physical processes responsible for the generation of the Intra-Cluster Light (ICL) in the available semi-analytic model, that, in its original form, does not account for them. The inclusion of these physical processes is, thus, an important improvement of the model. I take advantage of this upgrade of the model to investigate the origin of the ICL and to understand how the main properties of galaxies change with respect to a model that does not include these additional prescriptions. I find the fraction of ICL in groups and clusters predicted by the model to range between $10 \%$ and $40 \%$, with a large scatter and no halo mass dependence. Large part of the scatter on cluster scales is due to a range of dynamical histories, while on smaller scales it is mainly driven by individual accretion events and stripping of relatively massive satellites, with mass of the order of $10^{10.5} \, M_{\odot} \hm$, found to be the major contributors to the ICL. The ICL forms very late, below $ z \sim 1$ and a non negligible fraction (between $5 \%$ and $25 \%$) has been accreted during the hierarchical growth of haloes. Moreover, the ICL is made of stars which cover a relatively large range of metallicity, with the bulk of them being sub-solar, in agreement with recent observational data. The main results of this analysis have been submitted to MNRAS (Contini et al. 2013). In the last part of the thesis, the updated model is used to investigate the properties of the galaxy population in proto-cluster regions. The work is still in progress. I am testing the predictions of the semi-analytic model and comparing them with observations in terms of properties such as galaxy colours, star formation and stellar mass. A preliminary analysis of one very massive proto-cluster region shows that the galaxy population gets red and tend to cluster around the most massive galaxy as time goes by. There are, in literature, only a few attempts to probe such peculiar regions of the Universe from a theoretical point of view. The novelty of this work lies in the connection between massive clusters observed in the local Universe and the proto-cluster regions from which they have formed. I will try to define what a proto-cluster region is, and how it looks like, by studying the main properties of progenitors it contains. Specifically, I will investigate the spatial and velocity distributions of galaxies in simulated proto-clusters, looking at the red and blue galaxy distributions in these regions, as well as at BCG and satellite properties as a function of redshift. The main results of this work will be the subject of a paper in preparation.
XXV Ciclo
1982
4
Kozovska, Kornelia <1981>. "Business Clusters in Eastern Europe: Policy Analysis and Cluster Performance." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/1611/2/Tesi_Kornelia_Kozovska.pdf.
Full textAbstract:
Clusters have increasingly become an essential part of policy discourses at all levels, EU, national, regional, dealing with regional development, competitiveness, innovation, entrepreneurship, SMEs. These impressive efforts in promoting the concept of clusters on the policy-making arena have been accompanied by much less academic and scientific research work investigating the actual economic performance of firms in clusters, the design and execution of cluster policies and going beyond singular case studies to a more methodologically integrated and comparative approach to the study of clusters and their real-world impact. The theoretical background is far from being consolidated and there is a variety of methodologies and approaches for studying and interpreting this phenomenon while at the same time little comparability among studies on actual cluster performances. The conceptual framework of clustering suggests that they affect performance but theory makes little prediction as to the ultimate distribution of the value being created by clusters. This thesis takes the case of Eastern European countries for two reasons. One is that clusters, as coopetitive environments, are a new phenomenon as the previous centrally-based system did not allow for such types of firm organizations. The other is that, as new EU member states, they have been subject to the increased popularization of the cluster policy approach by the European Commission, especially in the framework of the National Reform Programmes related to the Lisbon objectives. The originality of the work lays in the fact that starting from an overview of theoretical contributions on clustering, it offers a comparative empirical study of clusters in transition countries. There have been very few examples in the literature that attempt to examine cluster performance in a comparative cross-country perspective. It adds to this an analysis of cluster policies and their implementation or lack of such as a way to analyse the way the cluster concept has been introduced to transition economies.
Our findings show that the implementation of cluster policies does vary across countries with some countries which have embraced it more than others. The specific modes of implementation, however, are very similar, based mostly on soft measures such as funding for cluster initiatives, usually directed towards the creation of cluster management structures or cluster facilitators. They are essentially founded on a common assumption that the added values of clusters is in the creation of linkages among firms, human capital, skills and knowledge at the local level, most often perceived as the regional level. Often times geographical proximity is not a necessary element in the application process and cluster application are very similar to network membership. Cluster mapping is rarely a factor in the selection of cluster initiatives for funding and the relative question about critical mass and expected outcomes is not considered. In fact, monitoring and evaluation are not elements of the cluster policy cycle which have received a lot of attention. Bulgaria and the Czech Republic are the countries which have implemented cluster policies most decisively, Hungary and Poland have made significant efforts, while Slovakia and Romania have only sporadically and not systematically used cluster initiatives.
When examining whether, in fact, firms located within regional clusters perform better and are more efficient than similar firms outside clusters, we do find positive results across countries and across sectors. The only country with negative impact from being located in a cluster is the Czech Republic.
5
Kozovska, Kornelia <1981>. "Business Clusters in Eastern Europe: Policy Analysis and Cluster Performance." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/1611/.
Full textAbstract:
Clusters have increasingly become an essential part of policy discourses at all levels, EU, national, regional, dealing with regional development, competitiveness, innovation, entrepreneurship, SMEs. These impressive efforts in promoting the concept of clusters on the policy-making arena have been accompanied by much less academic and scientific research work investigating the actual economic performance of firms in clusters, the design and execution of cluster policies and going beyond singular case studies to a more methodologically integrated and comparative approach to the study of clusters and their real-world impact. The theoretical background is far from being consolidated and there is a variety of methodologies and approaches for studying and interpreting this phenomenon while at the same time little comparability among studies on actual cluster performances. The conceptual framework of clustering suggests that they affect performance but theory makes little prediction as to the ultimate distribution of the value being created by clusters. This thesis takes the case of Eastern European countries for two reasons. One is that clusters, as coopetitive environments, are a new phenomenon as the previous centrally-based system did not allow for such types of firm organizations. The other is that, as new EU member states, they have been subject to the increased popularization of the cluster policy approach by the European Commission, especially in the framework of the National Reform Programmes related to the Lisbon objectives. The originality of the work lays in the fact that starting from an overview of theoretical contributions on clustering, it offers a comparative empirical study of clusters in transition countries. There have been very few examples in the literature that attempt to examine cluster performance in a comparative cross-country perspective. It adds to this an analysis of cluster policies and their implementation or lack of such as a way to analyse the way the cluster concept has been introduced to transition economies.
Our findings show that the implementation of cluster policies does vary across countries with some countries which have embraced it more than others. The specific modes of implementation, however, are very similar, based mostly on soft measures such as funding for cluster initiatives, usually directed towards the creation of cluster management structures or cluster facilitators. They are essentially founded on a common assumption that the added values of clusters is in the creation of linkages among firms, human capital, skills and knowledge at the local level, most often perceived as the regional level. Often times geographical proximity is not a necessary element in the application process and cluster application are very similar to network membership. Cluster mapping is rarely a factor in the selection of cluster initiatives for funding and the relative question about critical mass and expected outcomes is not considered. In fact, monitoring and evaluation are not elements of the cluster policy cycle which have received a lot of attention. Bulgaria and the Czech Republic are the countries which have implemented cluster policies most decisively, Hungary and Poland have made significant efforts, while Slovakia and Romania have only sporadically and not systematically used cluster initiatives.
When examining whether, in fact, firms located within regional clusters perform better and are more efficient than similar firms outside clusters, we do find positive results across countries and across sectors. The only country with negative impact from being located in a cluster is the Czech Republic.
6
Cruz, Sara Cristina Santos. "Surveying Industrial Clusters: A comprehensive Bibliometric Account." Master's thesis, Faculdade de Economia da Universidade do Porto, 2007. http://hdl.handle.net/10216/7563.
Full textAbstract:
EconomiaMaster in Economics
Num mundo onde o paradigma da globalização se tornou uma realidade inquestionável, a dimensão `local tem ganho particular interesse como objecto de análise. Isto decorre do facto de os principais factores de competitividade global se encontrarem profundamente enraizados a um nível local. Neste contexto, os clusters, como entidades geográficas e sócio-relacionais, com um percurso evolutivo específico, uma identidade institucional e dinâmicas locais de conhecimento, tornaram-se elementos cruciais no desenvolvimento das regiões, assumindo um papel significativo nas políticas públicas. Apesar da sua importância crescente, o conceito de cluster tem sido alvo de uma aplicação discricionária, em termos do seu sentido e definição. Tendo em conta a evolução histórica deste conceito, tornou-se, então, necessário encontrar uma forma de organizar a literatura existente, numa tentativa de harmonizar esta multiplicidade de interpretações e significados. Esta dissertação tem por objectivo sistematizar o actual corpo de abordagens teóricas e estudos empíricos sobre clusters através de uma revisão aprofundada da literatura, complementada com um estudo bibliométrico, realizado com base em artigos publicados em jornais indexados nas bases de dados bibliográficas Econlit e EBSCO, no período de 1962 a 2007. Os principais resultados deste trabalho de investigação indicam que, para além da sua importância académica, o papel dos clusters tem também sido amplamente reconhecido no domínio político. Por outro lado, o interesse crescente na dimensão `local tem sido acompanhado por um emergente corpo de literatura sobre `globalização, redes globais e clusters . Além disso, por detrás do recente boom na literatura sobre clusters, está a importância de temas como as `abordagens sociais e baseadas nas `networks de contactos ou redes locais dos clusters, bem como as teorias baseadas no conhecimento. Estudos sobre sistemas regionais e nacionais de inovação e abordagens institucionais (relativas a culturas, governação e costumes locais das regiões) alcançaram particular importância a partir da década de 1990. Isto reflecte claramente as mais recentes tendências da literatura sobre clusters, que têm dado especial enfoque a factores sistémicos e institucionais . Finalmente, não obstante a correlação positiva entre a qualidade das publicações e a investigação formal e experimental, a evolução da literatura sobre clusters continua a ser maioritariamente apreciativa e descritiva.
As the global paradigm became an accepted reality, the local dimension has gained particular interest as an object of analysis. This is because key factors of global competitiveness have become deeply rooted at a local level. In this context, clusters, as geographical and socio-relational entities with a specific evolutionary path, institutional embeddedness and local knowledge dynamics, have become crucial elements in regional development, assuming a significant role in public policies. Despite its growing importance, the concept of cluster has been subject to a rather discretionary use in terms of interpretation and meaning. Since the multiplicity of definitions has flourished with the historical evolution of the cluster concept, it became necessary to find a way to organize the existing literature, in an attempt to overcome this multitude of notions and meanings. This dissertation aims to systematize the existing corpus of theoretical approaches and empirical studies on clusters by carrying out a thorough, qualitative survey of the cluster literature, complemented with a comprehensive bibliometric account, based on articles published in journals indexed in the Econlit and EBSCO bibliographic databases, from 1962 to 2007. The main outcomes of this research show that besides their importance in academic fields, the role of clusters has also been widely acknowledged in political spheres. Along with an increasing interest in the `local dimension, an emergent corpus of literature on global networks and clusters has also arisen. Moreover, behind the recent boom in the cluster literature is the influence of the prominent themes `local networks and social approaches and `knowledge-based theories . Studies on `regional and national innovation systems and `institutional approaches (mostly concerned with enrooted local cultures, governance and customs) have been achieving a particular importance since the 1990s. This clearly reflects the most recent trends in the cluster literature, which focus particularly on `systemic and `institutional factors. Finally, despite the positive correlation between the `quality of journals and related formal research, the evolution of the literature on clusters continues to be mostly appreciative-led.
7
Cruz, Sara Cristina Santos. "Surveying Industrial Clusters: A comprehensive Bibliometric Account." Dissertação, Faculdade de Economia da Universidade do Porto, 2007. http://hdl.handle.net/10216/7563.
Full textAbstract:
EconomiaMaster in Economics
Num mundo onde o paradigma da globalização se tornou uma realidade inquestionável, a dimensão `local tem ganho particular interesse como objecto de análise. Isto decorre do facto de os principais factores de competitividade global se encontrarem profundamente enraizados a um nível local. Neste contexto, os clusters, como entidades geográficas e sócio-relacionais, com um percurso evolutivo específico, uma identidade institucional e dinâmicas locais de conhecimento, tornaram-se elementos cruciais no desenvolvimento das regiões, assumindo um papel significativo nas políticas públicas. Apesar da sua importância crescente, o conceito de cluster tem sido alvo de uma aplicação discricionária, em termos do seu sentido e definição. Tendo em conta a evolução histórica deste conceito, tornou-se, então, necessário encontrar uma forma de organizar a literatura existente, numa tentativa de harmonizar esta multiplicidade de interpretações e significados. Esta dissertação tem por objectivo sistematizar o actual corpo de abordagens teóricas e estudos empíricos sobre clusters através de uma revisão aprofundada da literatura, complementada com um estudo bibliométrico, realizado com base em artigos publicados em jornais indexados nas bases de dados bibliográficas Econlit e EBSCO, no período de 1962 a 2007. Os principais resultados deste trabalho de investigação indicam que, para além da sua importância académica, o papel dos clusters tem também sido amplamente reconhecido no domínio político. Por outro lado, o interesse crescente na dimensão `local tem sido acompanhado por um emergente corpo de literatura sobre `globalização, redes globais e clusters . Além disso, por detrás do recente boom na literatura sobre clusters, está a importância de temas como as `abordagens sociais e baseadas nas `networks de contactos ou redes locais dos clusters, bem como as teorias baseadas no conhecimento. Estudos sobre sistemas regionais e nacionais de inovação e abordagens institucionais (relativas a culturas, governação e costumes locais das regiões) alcançaram particular importância a partir da década de 1990. Isto reflecte claramente as mais recentes tendências da literatura sobre clusters, que têm dado especial enfoque a factores sistémicos e institucionais . Finalmente, não obstante a correlação positiva entre a qualidade das publicações e a investigação formal e experimental, a evolução da literatura sobre clusters continua a ser maioritariamente apreciativa e descritiva.
As the global paradigm became an accepted reality, the local dimension has gained particular interest as an object of analysis. This is because key factors of global competitiveness have become deeply rooted at a local level. In this context, clusters, as geographical and socio-relational entities with a specific evolutionary path, institutional embeddedness and local knowledge dynamics, have become crucial elements in regional development, assuming a significant role in public policies. Despite its growing importance, the concept of cluster has been subject to a rather discretionary use in terms of interpretation and meaning. Since the multiplicity of definitions has flourished with the historical evolution of the cluster concept, it became necessary to find a way to organize the existing literature, in an attempt to overcome this multitude of notions and meanings. This dissertation aims to systematize the existing corpus of theoretical approaches and empirical studies on clusters by carrying out a thorough, qualitative survey of the cluster literature, complemented with a comprehensive bibliometric account, based on articles published in journals indexed in the Econlit and EBSCO bibliographic databases, from 1962 to 2007. The main outcomes of this research show that besides their importance in academic fields, the role of clusters has also been widely acknowledged in political spheres. Along with an increasing interest in the `local dimension, an emergent corpus of literature on global networks and clusters has also arisen. Moreover, behind the recent boom in the cluster literature is the influence of the prominent themes `local networks and social approaches and `knowledge-based theories . Studies on `regional and national innovation systems and `institutional approaches (mostly concerned with enrooted local cultures, governance and customs) have been achieving a particular importance since the 1990s. This clearly reflects the most recent trends in the cluster literature, which focus particularly on `systemic and `institutional factors. Finally, despite the positive correlation between the `quality of journals and related formal research, the evolution of the literature on clusters continues to be mostly appreciative-led.
8
Hess, Cassiano Ricardo. "MDX-cc: ambiente de programação paralela aplicado a cluster de clusters." Pontifícia Universidade Católica do Rio Grande do Sul, 2003. http://hdl.handle.net/10923/1655.
Full textAbstract:
Made available in DSpace on 2013-08-07T18:43:26Z (GMT). No. of bitstreams: 1
000429227-Texto+Completo-0.pdf: 1053601 bytes, checksum: ac385028f1ef5808c2649d92f982cc04 (MD5)
Previous issue date: 2003Due to the appearance of fast communication networks, such as Myrinet and SCI, it becames possible the construction of new architectures based on commodity, off-the-shelf machines (PCs and workstations) connected by this kind of network - which are been called clusters. Such architectures are becoming an alternative execution platform for complex parallel applications, mainly due to the cost/benefit relation they present. The diversity of fast networks leads to the interconnection of clusters, building an architecture called cluster of clusters. One of the main problems in the use of clusters of clusters is the programming software used for parallel application development, since this kind of architecture has some characteristics that must be addressed by the programming language or environment in order to provide high performance. This work describes the development of a message passing parallel programming environment for cluster of clusters, the MDX-cc. This environment was projected based on the MDX system [PRE98][HES01] and a first version has been implemented supporting communication over Fast-Ethernet, SCI and Myrinet networks. The main goal of MDX-cc is to provide communication and synchronization of processes that run on interconnected clusters. Thanks to its modular architecture and the use of specific communication protocols dedicated to each network interface, MDX-cc provides a simple programming interface, with a small set of primitives, and also provides a transparent communication among processes running on different network-based clusters.
Em razão do surgimento de redes de comunicação de alta velocidade, tais como Myrinet e SCI, a construção de arquiteturas baseadas em máquinas comuns (PCs e estações de trabalho) conectadas por esse tipo de rede - o que se denomina agregado (ou cluster) - tornou-se viável. Tais arquiteturas vêm se consolidando como plataformas alternativas para a execução de aplicações paralelas complexas, principalmente devido à relação custo/benefício que oferecem. Esse avanço das tecnologias de redes possibilita também a agregação de clusters, formando uma estrutura de cluster de clusters, como uma única máquina paralela. Um dos principais problemas no uso de cluster de clusters é o software utilizado para o desenvolvimento de aplicações paralelas, visto que cada agregado envolvido na estrutura possui certas características que precisam ser tratadas pela linguagem ou ambiente de programação, visando o alcance de alto desempenho. Esta dissertação tem como objetivo apresentar uma ferramenta de programação paralela por troca de mensagens que executa sobre uma estrutura de cluster de clusters: o MDX-cc. A ferramenta foi concebida tendo como base o sistema MDX [PRE98][HES01] e uma primeira versão foi implementada oferecendo suporte à comunicação em agregados com redes SCI, Myrinet e Fast-Ethernet. O principal objetivo do MDX-cc é oferecer recursos de comunicação e sincronização de processos que rodam em agregados interligados. Por sua arquitetura modular e abstração do uso de protocolos de comunicação dedicados a cada tecnologia de rede, o MDX-cc oferece uma interface de programação simples, com um conjunto reduzido de primitivas, e provê transparência total na comunicação entre processos que executam em nós de clusters com tecnologias de rede distintas.
9
Ballestrin, Silvia <1989>. "Industrial Clusters in BRIC countries. An analysis of the economic geography of industrial clusters in BRIC countries and the cluster development policies." Master's Degree Thesis, Università Ca' Foscari Venezia, 2013. http://hdl.handle.net/10579/3656.
Full textAbstract:
La tesi si propone di analizzare la geografia economica dei cluster industriali nei BRIC. Essa è costituita da una prima parte in cui vengono riassunte le principali teorie economiche sviluppatesi attorno al concetto di cluster e si definiscono i principali tratti economici, demografici e sociali dei paesi presi in considerazione, i BRIC (Brasile, Russia, India, Cina). La seconda parte è invece dedicata all'analisi della geografia economica dei cluster industriali nei suddetti paesi, utilizzando una comune chiave di lettura. Lo scopo principale è quello di analizzare come questo modello di organizzazione industriale possa farsi promotore di sviluppo, agendo sul grado di competitività sostenibile delle economie emergenti in oggetto.
10
Bowlan, John. "Electric dipole moments, cluster metallicity, and the magnetism of rare earth clusters." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34751.
Full textAbstract:
One of the fundamental properties of bulk metals is the cancellation of electric
fields. The free charges inside of a metal will move until they find an arrangement where
the internal electric field is zero. This implies that the electric dipole moment of a metal
particle should be exactly zero, because an electric dipole moment requires a net separation
of charge and thus a nonzero internal electric field.
This thesis is an experimental study to see if this property continues to hold for tiny sub-
nanometer metal particles called clusters (2 - 200 atom, R < 1 nm). We have measured the
electric dipole moments of metal clusters made from 15 pure elements using a molecular
beam electric deflection technique. We find that the observed dipole moments vary a great
deal across the periodic table. Alkali metals have zero dipole moments, while transition
metals and lanthanides all have dipole moments which are highly size dependent. In most
cases, the measured dipole moments are independent of temperature (T = 20 - 50 K), and
when there is a strong temperature dependence this suggests that there is a new state of
matter present. Our interpretation of these results are that those clusters which have a non-
zero dipole moment are non-metallic, in the sense that their electrons must be localized
and prevented from moving to screen the internal field associated with a permanent dipole
moment.
This interpretation gives insight to several related phenomena and applications. We
briefly discuss an example cluster system RhN where the measured electric dipole moments
appear to be correlated with a the N2O reactivity.
Finally, we discuss a series of magnetic deflection experiments on lanthanide clusters
(Pr, Ho, Tb, and Tm). The magnetic response of these clusters is very complex and highly
sensitive to size and temperature. We find that PrN (which is non-magnetic in the bulk) becomes magnetic in clusters and TmN clusters have magnetic moments lower than the atomic value as well as the bulk saturation value implying that the magnetic order in the cluster involves non-collinear or antiferromagnetic order. HoN and TbN show very similar size dependent trends suggesting that these clusters have similar structures.
11
Jefferson, Bea A. "Clusters and cluster policy : advanced manufacturing and metals industries in South Yorkshire." Thesis, University of Sheffield, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412792.
Full text
12
Hess, Cassiano Ricardo. "MDX-cc : ambiente de programa??o paralela aplicado a cluster de clusters." Pontif?cia Universidade Cat?lica do Rio Grande do Sul, 2003. http://tede2.pucrs.br/tede2/handle/tede/5121.
Full textAbstract:
Made available in DSpace on 2015-04-14T14:49:29Z (GMT). No. of bitstreams: 1
429227.pdf: 1053601 bytes, checksum: ac385028f1ef5808c2649d92f982cc04 (MD5)
Previous issue date: 2003-03-28Em raz?o do surgimento de redes de comunica??o de alta velocidade, tais como Myrinet e SCI, a constru??o de arquiteturas baseadas em m?quinas comuns (PCs e esta??es de trabalho) conectadas por esse tipo de rede - o que se denomina agregado (ou cluster) - tornou-se vi?vel. Tais arquiteturas v?m se consolidando como plataformas alternativas para a execu??o de aplica??es paralelas complexas, principalmente devido ? rela??o custo/benef?cio que oferecem. Esse avan?o das tecnologias de redes possibilita tamb?m a agrega??o de clusters, formando uma estrutura de cluster de clusters, como uma ?nica m?quina paralela. Um dos principais problemas no uso de cluster de clusters ? o software utilizado para o desenvolvimento de aplica??es paralelas, visto que cada agregado envolvido na estrutura possui certas caracter?sticas que precisam ser tratadas pela linguagem ou ambiente de programa??o, visando o alcance de alto desempenho. Esta disserta??o tem como objetivo apresentar uma ferramenta de programa??o paralela por troca de mensagens que executa sobre uma estrutura de cluster de clusters: o MDX-cc. A ferramenta foi concebida tendo como base o sistema MDX [PRE98][HES01] e uma primeira vers?o foi implementada oferecendo suporte ? comunica??o em agregados com redes SCI, Myrinet e Fast-Ethernet. O principal objetivo do MDX-cc ? oferecer recursos de comunica??o e sincroniza??o de processos que rodam em agregados interligados. Por sua arquitetura modular e abstra??o do uso de protocolos de comunica??o dedicados a cada tecnologia de rede, o MDX-cc oferece uma interface de programa??o simples, com um conjunto reduzido de primitivas, e prov? transpar?ncia total na comunica??o entre processos que executam em n?s de clusters com tecnologias de rede distintas.
13
Silva, Júnior José Leite da 1967. "Análise de Clusters na avaliação de bancos." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/261158.
Full textAbstract:
Orientador: Takaaki OhishiTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
Made available in DSpace on 2018-08-25T14:58:19Z (GMT). No. of bitstreams: 1 SilvaJunior_JoseLeiteda_D.pdf: 2387475 bytes, checksum: 4204df22b013ff0857e5e9c02d7bec29 (MD5) Previous issue date: 2013
Resumo: A principal contribuição dessa tese é o desenvolvimento de uma metodologia de avaliação de instituições financeiras de implementação simples e que se mostrou precisa na avaliação de bancos americanos. A metodologia busca a produzir um índice de solidez que indique a relativa saúde das instituições sob estudo e está baseada na utilização da técnica estatística multivariada conhecida como análise de clusters, na utilização de variáveis financeiras publicamente disponíveis e na avaliação periódica de quais variáveis financeiras são significativas na avaliação das instituições bancárias. A metodologia foi aplicada ao mercado financeiro americano e apresentou bons resultados na identificação de instituições financeiras fragilizadas, o que permitiria ao supervisor bancário tomar mais precocemente ações com vistas a minimizar o impacto da atuação dessas instituições no mercado bancário como um todo
Abstract: The main contribution of this thesis is the development of a methodology evaluation of financial institutions to implement simple and that proved accurate evaluation of American banks. The methodology seeks to produce an index sound indicating the relative health of the institutions under study and is based on the use multivariate statistical technique known as analysis of clusters in use of publicly available financial variables and evaluation Periodical of which financial variables are significant in the evaluation of banking institutions. The methodology was applied to the U.S. financial market and showed good results in the identification of financial institutions weakened, allowing banking supervisor to take earlier actions aimed at minimizing the impact the role of these institutions in the banking market as a whole
Doutorado
Engenharia de Computação
Doutor em Engenharia Elétrica
14
Kuan, Fong Sheen, and mikewood@deakin edu au. "Organotin-Oxo Clusters." Deakin University. School of biological and chemical sciences, 2002. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20051125.084244.
Full textAbstract:
This thesis reports on the development and expansion of reliable synthetic di-and multi-tin precursors for the assembly of oligomeric organotin-oxo compounds in which the shape, dimension and tin nuclearity can be controlled.
The reaction of polymeric diorganotin oxides, (R2SnO)m (R = Me, Et, n-Bu, n-Oct, c-Hex, i-Pr, Ph), with saturated aqueous NH4X solutions (X = F, Cl, Br, I, OAc) in refluxing 1,4-dioxane afforded in high yields dimeric tetraorganodistannoxanes, [R2(X)SnOSn(X)R2]2, and in a few cases diorganotin dihalides or diacetates, R2SnX2. This method appears to be particularly good for the synthesis of halogenated tetraorganodistannoxanes but a less suitable method for the preparation of dicarboxylato tetraorganodistannoxanes. Identification of [R2(OH)SnOSn(X)R2]2 (R = n-Bu; X = Cl, Br) and [R2(OH)SnOSn(X)R2][R2(X)SnOSn(X)R2] suggest a serial substitution mechanism starting from [R2(OH)SnOSn(OH)R2]2.
A series of α, ω -bis(triphenylstannyl)alkanes, [Ph3Sn]2(CH2)n (n = 3-8, 10, 12) and some of their derivatives were synthesised and characterised. These α, ω-bis(triphenylstannyl)alkanes, [Ph3Sn]2(CH2)n were converted to the corresponding halides [R(Cl)2Sn]2(CH2)n (R = CH2SiMe3) and subsequently to the polymeric oxides {[R(0)Sn]2(CH2)n}m. Reaction of {[R(O)Sn]2(CH2)n}m with [R(Cl)2Sn]2(CH2)n. (n = 3, n' = 4 and n = 4, n' = 3) in toluene at 100°C results in a mixture of symmetric and asymmetric double ladders, where different spacer chain lengths (n and n') provide the source of asymmetry. The coexistence at high temperature of separate 119Sn NMR signals belonging to symmetric and asymmetric double ladders suggests an equilibrium that is slow on the 119Sn NMR time scale and the position of which is temperature dependent. However, 119Sn NMR spectroscopic experiments of {[R(0)Sn]2(CH2)3}m with [R(Cl)2Sn]2(CH2)n for longer spacers (n - 5, 6, 8, 10, 12) reveal that molecular self-assembly of symmetric spacer-bridged di-tin precursors of equal chain length is preferred over asymmetric species.
An ether-bridged di-tin tetrachloride [R(Cl)2Sn(CH2)3]2O (R = CH2SiMe3) and its corresponding polymeric oxide {[R(O)Sn(CH2)3]2O}m were synthesised and characterised. Reaction of [R(Cl)2Sn(CH2)3]2O with {[R(O)Sn(CH2)3]2O}m results in a unique functionalised double ladder {{[RSn(Cl)](CH2)3O(CH2)3[RSn(Cl)]}O}4 whose structure in the solid state was determined by X-ray analysis. Identification of tetrameric functionalised double ladder as well as dimeric and monomeric species suggest the existence of an equilibrium in solution. The feasibility of the functionalised double ladder to form host-guest complexes with a variety of metal cations is investigated using electrospray mass spectrometry (ESMS). Evidence for such complexes is found only for sodium cations.
The reaction between {[R(O)Sn]2(CH2)n}m (n = 3, 4, 8, 10) and triflic acid is described. The initial formed products [RSn(CH2)nSnR](OTf)4 are easily hydrolysed. For n = 3, self-assembly leads to a discrete double ladder type structure, {{[RSn(OH)](CH2)3[RSn(H2O)]}O}44OTf, which is the first example of a cationic double ladder. For n ≥ 3, hydrolysis gives polymeric products, as demonstrated by the crystal structure of {[(H2O)(OH)RSn]2(CH2)4-2OTf2H2O}m.
Two spacer-bridged terra-tin octachlorides [R(Cl)2Sn(CH2)3Sn(Cl)2]2(CH2)n (R = CH2SiMes; n = 1, 8) and their corresponding polymeric oxides {[R(O)Sn(CH2)3Sn(O)]2(CH2)n}m were successfully synthesised and characterised. Attempts were made to synthesise quadruple ladders from these precursors. Reactions of [R(Cl)2Sn(CH2)3Sn(Cl)2]2CH2 with {[R(O)Sn(CH2)3Sn(O)]2CH2}m or (Y-Bu2SnO)3 result in, mostly insoluble, amorphous solids. Reactions of [R(Cl)2Sn(CH2)3Sn(Cl)2]2(CH2)8 with {[R(O)Sn(CH2)3Sn(O)]2(CH2)8}m or (t-Bu2SnO)s result in new tin-containing species which are presumably oligomeric.
The synthesis of a series of alkyl-bridged di-tin hexacarboxylates [(RCO2)3Sn]2(CH2)n (n = 3, 4; R = Ph, c-C6H11, CH3, C1CH2) is also reported. The hydrolysis of these compounds is facile and complex. There appears to be no correlation between spacer chain length and hydrolysis product. However, the conjugate acid strength of the carboxylate does appear to be important. In general only insoluble amorphous polymeric organotin-oxo compounds were obtained.
15
Millington, S. J. C. "Clusters of galaxies." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382461.
Full text
16
Dutton, Tom. "Ruthenium carbido clusters." Thesis, University of Cambridge, 1989. https://www.repository.cam.ac.uk/handle/1810/290027.
Full text
17
Galsworthy, Jane R. "Heterometallic boride clusters." Thesis, University of Cambridge, 1994. https://www.repository.cam.ac.uk/handle/1810/272676.
Full text
18
Edwards, Andrew John. "Tetraruthenium carbido clusters." Thesis, University of Cambridge, 1991. https://www.repository.cam.ac.uk/handle/1810/272445.
Full text
19
Behera, Swayamprabha. "CLUSTERS BRIDGING DISCIPLINES." VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/3571.
Full textAbstract:
Clusters constitute an intermediate state of matter between molecules and solids whose properties are size dependent and can be tailored. In recent years, cluster science has become one of the most exciting areas of research since their study can not only bridge our understanding between atoms and their bulk but also between various disciplines. In addition, clusters can serve as a source of new materials with uncommon properties. This dissertation deals with an in-depth study of clusters as a bridge across physics, chemistry, and materials science and provides a fundamental understanding of the structure-property relationships by focusing on three different topics. The first topic deals with superatoms which are clusters that mimic the chemistry of atoms. I show that superhalogens and superalkalis can be designed to mimic the chemistry of halogen and alkali atoms, respectively. An entirely new class of salts can then be synthesized by using these superatoms as the building blocks. I have also explored the possibility of designing highly electronegative species called hyperhalogens by using superhalogens as ligands or superalkalis as core and a combination of both. Another aspect of my work on superatom is to examine if traditional catalysts (namely Pd) can be replaced by clusters composed of earthabundant elements (namely Zr and O). This is accomplished by comparing the electronic structure and reactivity of Pd clusters with isoelectronic ZrO clusters. The second topic deals with a study of the electronic structure of coinage metal (Cu and Ag) clusters and see if they remain unchanged when a metal atom is replaced by an isoelectronic hydrogen atom as is the case with Au-H clusters. The third topic deals with clusters as model of polymeric materials to understand their gas storage and sequestration properties. This is accomplished by studying the trapping of H2, CO2, CH4 and SO2 molecules in borazine-linked polymers (BLPs) and benzimidazole-linked polymers (BILPs). The first two topics provide a bridge between physics and chemistry, while the third topic provides a bridge to materials science.
20
Bonamigo, Mario. "Triaxial galaxy clusters." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4717/document.
Full textAbstract:
Il est bien établit théoriquement et observationnellement que les amas de galaxies ne sont pas des objets sphèriques, et qu'ils sont beaucoup mieux décrits par la géométrie triaxiale. Malgré cela, les travaux sur la forme tri-dimensionnelle des amas de galaxies sont encore trés rares. L'objet de cette thèse est de contribuer à cette problématique naissante. L'originalité de ce travail est d'aborder ce sujet théoriquement et observationnellement. J'ai mesuré la forme d'amas de galaxies simulés, proposant des prédictions sur la forme des haloes de matière noire. J'ai ensuite développé un algorithme qui se propose de combiner des données en lentilles gravitationnelles et en rayons X afin de contraindre un modèle de haloe triaxial. L'algorithme est testé sur des données simulées. Finalement, je présente l'analyse en rayons X de Abell 1703, qui, combinée avec l'analyse en lentilles gravitationnelles, permettra de déterminer la forme de Abell 1703It is well established both theoretically and observationally that galaxy clusters are not spherical objects and that they are much better approximated as triaxial objects. This thesis focusses on the three dimencional shape of galaxy clusters. The originality of my approach is to tackle the problem both theoretically and observationally. First, I have measured the shape of dark matter haloes in the Millenium XXL and Sbarbine simulations, providing predictions for dark matter halo shape over 5 order in magnitude in mass. Then, I have developed an algorithm aimed at fitting simultaneously lensing and X-ray data in order to constrain a triaxial mass distribution. The algorithm is tested and characterized on mock data sets. It is found to be able to recover the input parameters. Finally, I present the X-ray analysis of galaxy cluster Abell 1703, which will be combined with the existing lensing analysis in order to investigate its shape
21
Lindqvist, Göran. "Disentangling clusters : agglomeration and proximity effects." Doctoral thesis, Handelshögskolan i Stockholm, Institute of International Business (IIB), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hhs:diva-426.
Full textAbstract:
Clusters are spatial agglomerations of firms in related industries. Although industry clusters have existed for centuries, the cluster concept has only recently been formulated in economic terms and has begun to attract considerable interest from scholars and policymakers over the last 20 years. A vast literature has examined all kinds of clusters and how clustering relates to innovation, growth, and other forms of economic performance of firms and regions. The cluster concept has provided a framework for thousands of national, regional, and local initiatives around the world. Yet, both research and policy efforts have yielded varying and sometimes contradictory results. This dissertation revisits some of the most basic questions about clusters. Using an approach that treats agglomeration and proximity effects as separate but related phenomena, it examines three fundamental aspects of clusters. First, it proposes a way to measure agglomeration more accurately and presents more detailed data on clusters in Europe than have previously been available. Second, it analyses the benefits of clusters for new firms and for regions. Third, it examines how clusters are “organised” through cluster initiatives. The results presented here carry implications for the study of clusters in economic geography, strategic management, and cluster policy research. They also contribute to our knowledge of cluster organisations and are of interest to both policymakers and cluster practitioners. Göran Lindqvist is a researcher at the Center for Strategy and Competitiveness at the Stockholm School of Economics. He has published books and articles about clusters and cluster policy, and he has conducted numerous cluster-related projects for international and national public agencies in Europe and the USA. www.sse.edu/cscDiss. Stockholm : Handelshögskolan, 2009 Sammanfattning jämte 7 uppsatser
22
Vilela, Júnior Dalton Chaves. "A criação de conhecimento em clusters industriais." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2010. http://hdl.handle.net/10183/18804.
Full textAbstract:
Esta tese propõe um quadro referencial abrangente para analisar os elementos envolvidos na criação de conhecimento em clusters (CCC), tema não completamente abordado pela literatura. A CCC é um processo que visa ampliar a base de conhecimento, compreendendo o cluster, a governança do cluster e/ou a coletividade dos membros. O quadro proposto contempla os diferentes atores que operam em clusters (empresas, instituições de ensino e pesquisa, governo, instituições de cooperação e instituições para financiamento), os níveis onde o conhecimento é criado (nas organizações, na governança e no cluster) e as diferentes dimensões do conhecimento (tecnológica, gerencial, relacional e estratégica). A estratégia da pesquisa previu a realização de quatro estudos de caso: no cluster de desenvolvimento de software em Manaus – AM – Brasil (Amazonsoft), no cluster de ciências da vida com foco em biotecnologia na região de Marseille – França (Bioméditerranée), no cluster de móveis na região de Bento Gonçalves – RS – Brasil (Pólo Moveleiro da Serra Gaúcha) e no cluster têxtil na região de Caxias do Sul – RS – Brasil (Pólo de Moda da Serra Gaúcha). Os principais resultados apontam para: a) a importância do conhecimento criado no nível do cluster para o desenvolvimento coletivo; b) a importância do conhecimento criado pelos membros decorrente de sua participação no cluster; c) a influência do setor industrial; do estágio de desenvolvimento e da composição do cluster na CCC; d) o papel da governança na potencialização da CCC; e) a relevância dos spillovers como um dos impulsionadores do conhecimento no cluster; f) a ligação entre a capacidade absortiva dos membros e a CCC; g) a necessidade de envolvimento dos membros na expansão do conhecimento no cluster; h) a consideração das diferentes dimensões do conhecimento para o desenvolvimento e a sustentabilidade dos clusters. Estes resultados podem orientar o desenvolvimento de novas pesquisas sobre a CCC e podem auxiliar a tomada de decisão de gestores de clusters, de membros de clusters e de agências governamentais para impulsionarem a CCC nos clusters, os quais estão envolvidos.This dissertation proposes a comprehensive theoretical framework to analyze the factors involved in the Clusters Knowledge Creation (CKC), a subject that still is not totally covered by the literature. CKC is a process designed to increase the knowledge base, comprising the cluster, the cluster governance and/or its member‘s community. The proposed framework contemplates the different parties that operate in clusters (companies, educational and research institutions, government, cooperation agencies, and financial institutions), the levels where knowledge creation takes place (in the organizations, in the governance structure and in the cluster) and the different knowledge dimensions (technological, managerial, strategic, and relational). The research strategy relied on the performance of four case studies: the software development cluster in Manaus - AM - Brazil (AmazonSoft), the life sciences cluster focused on biotechnology in the region of Marseille - France (Bioméditerranée), the furniture cluster in the region of Bento Gonçalves - RS - Brazil (Pólo Moveleiro da Serra Gaúcha), and the textile cluster in the region of Caxias do Sul - RS - Brazil (Pólo de Moda da Serra Gaúcha). The main results highlight: a) the importance of the knowledge created at the cluster level for the collective development; b) the importance of the knowledge created by members due to their participation in the cluster; c) the influence of industrial sector, development stage and cluster composition in the CKC; d) the governance role to increase the CKC; e) the spillovers relevance as one of the drivers of the cluster knowledge; f) the link between members absorptive capacity and CKC; g) the need of members‘ embeddedness for the expansion of cluster‘s knowledge; and h) the consideration of different knowledge dimensions for the cluster‘s development and sustainability. These results can guide the development of new researches about CKC. Moreover, it may assist the decision-making process of clusters‘ managers, cluster members and government entities to propel the CKC in the clusters to which they are associated.
23
Zeni, Elton. "Sistema de avaliação das vantagens potenciais de Clusters industriais." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/97233.
Full textAbstract:
Este trabalho tem como objetivo principal desenvolver um sistema de avaliação de desempenho de clusters, capaz de analisar as vantagens potenciais que um cluster pode oferecer e concluir a respeito do aproveitamento dessas vantagens e dos aspectos que podem ser aprimorados. Para isso, o trabalho se propõe a: (i) identificar os constructos e variáveis que devem ser utilizados para representar as vantagens potenciais que um cluster industrial pode oferecer; (ii) desenvolver um sistema de avaliação do aproveitamento das vantagens potenciais de um cluster, baseado nos constructos e variáveis identificados; (iii) testar o sistema, avaliando o nível de desenvolvimento, no que tange ao aproveitamento de vantagens potenciais em que se encontra o cluster moveleiro do Oeste de Santa Catarina; e (iv) estabelecer um plano para aprimoramento das operações e consolidação do referido cluster. Esta tese está baseada numa abordagem quantitativa e qualitativa, utilizando questionário aplicado em 112 empresas, grupo focado e entrevistas. Uma das principais contribuições desta tese é a proposição de um modelo capaz de avaliar o aproveitamento das vantagens potenciais de um cluster, auxiliando na tomada de decisão dos envolvidos (poder público, instituições de classe, empresas) e melhoria da competitividade das empresas do cluster em relação às empresas externas. Outra contribuição deste trabalho é a proposição de ações que possam aumentar o aproveitamento das vantagens oferecidas às empresas pertencentes ao cluster moveleiro do oeste de Santa Catarina e à sua competitividade.The main objective of this work is to develop a performance evaluation system of clusters, able of analyzing the potential advantages that a cluster can offer to its member companies and conclude about the use of these advantages and about the aspects which could be improved. Considering this general objective, this work intends: (i) identify the constructs and variables that should be utilized for represent the potential advantages that an industrial cluster can offer; (ii) develop an evaluation system for access the use of the potential advantages of a cluster, based on the constructs and identified variables; (iii) test the system, evaluating the development level of the west of Santa Catarina furniture cluster, regarding the use of the potential advantages, (iv) establish a plan for the improvement of operations and consolidation of the mentioned cluster. This dissertation is based on a qualitative and quantitative approach, comprising a survey involving 112 companies, focus group and interviews. One of the main contributions of this dissertation is the proposal of a model capable of evaluate the use of the potential advantages of a cluster, assisting on the decision making of the stakeholders (government, class association and companies) and competitiveness improvement of the cluster member companies compared to outside companies. Other contribution of this work is the proposal of a plan of actions that could increase the use of the advantages offered to the member companies of the west of Santa Catarina furniture cluster and their respective competitiveness.
24
Steiner, Roland. "Innovative Cluster Konzept zur Lancierung eines innovativen Clusters, mit starkem Fokus auf KMU /." St. Gallen, 2005. http://www.biblio.unisg.ch/org/biblio/edoc.nsf/wwwDisplayIdentifier/02602191001/$FILE/02602191001.pdf.
Full text
25
Huang, Hung-Jin, Rachel Mandelbaum, Peter E. Freeman, Yen-Chi Chen, Eduardo Rozo, and Eli Rykoff. "Intrinsic alignment in redMaPPer clusters – II. Radial alignment of satellites towards cluster centres." OXFORD UNIV PRESS, 2018. http://hdl.handle.net/10150/627131.
Full textAbstract:
We study the orientations of satellite galaxies in redMaPPer clusters constructed from the Sloan Digital Sky Survey at 0.1 < z < 0.35 to determine whether there is any preferential tendency for satellites to point radially towards cluster centres. We analyse the satellite alignment (SA) signal based on three shape measurement methods (re-Gaussianization, de Vaucouleurs, and isophotal shapes), which trace galaxy light profiles at different radii. The measured SA signal depends on these shape measurement methods. We detect the strongest SA signal in isophotal shapes, followed by de Vaucouleurs shapes. While no net SA signal is detected using re-Gaussianization shapes across the entire sample, the observed SA signal reaches a statistically significant level when limiting to a subsample of higher luminosity satellites. We further investigate the impact of noise, systematics, and real physical isophotal twisting effects in the comparison between the SA signal detected via different shape measurement methods. Unlike previous studies, which only consider the dependence of SA on a few parameters, here we explore a total of 17 galaxy and cluster properties, using a statistical model averaging technique to naturally account for parameter correlations and identify significant SA predictors. We find that the measured SA signal is strongest for satellites with the following characteristics: higher luminosity, smaller distance to the cluster centre, rounder in shape, higher bulge fraction, and distributed preferentially along the major axis directions of their centrals. Finally, we provide physical explanations for the identified dependences and discuss the connection to theories of SA.
26
He, Shaowei. "Structural embeddedness, clusters, and cluster policy : a case study of the West Midlands." Thesis, University of Birmingham, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440930.
Full text
27
Marquezan, Clarissa Cassales. "Integrated Cluster Environment (ICE) : plataforma de gerenciamento e de acesso a múltiplos clusters." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2006. http://hdl.handle.net/10183/10270.
Full textAbstract:
Facilitar o gerenciamento e o acesso a sistemas de alto desempenho vem sendo uma área de pesquisa explorada nos últimos anos. Isto acontece uma vez que se verifica o aumento do número de usuários, muitos pertencentes a outras áreas, como por exemplo, biologia, geologia, hidrologia, etc e, desta forma, é preciso facilitar os meios de interação destes usuários com tais sistemas, assim como melhorar as técnicas de gerenciamento dos mesmos. Além do aumento do número e da multidisciplinaridade desses usuários, existe também o fato de que grande parte deles tem acesso a diferentes tipos de sistemas de alto desempenho. Em geral, estes sistemas possuem ferramentas não padronizadas, sendo que cada uma apresenta uma interface e um conjunto de ações e comandos a serem realizados para que possam dispor de suas funcionalidades. Este trabalho propõe a definição de uma arquitetura de gerenciamento e acesso a múltiplos clusters, que seja capaz de ser facilmente extensível, transparente, interoperável e de fácil utilização configuração e manutenção. Como resultado da arquitetura proposta, foi desenvolvido um protótipo, denominado ICE - Integrated Cluster Environment. Os principais objetivos da arquitetura e do ambiente ICE são: (i) capacidade de uniformização do modo como as ferramentas de clusters são utilizadas e, também, uniformização na maneira como os clusters são acessados; (ii) transparência na forma de acesso e uso dos clusters; e (iii) capacidade de extensibilidade em dois níveis: o primeiro refere-se á extensibilidade do número de funcionalidades (serviços) providos pelo sistema e o segundo está relacionado á capacidade do sistema lidar com o uso de diferentes ferramentas que possuem a mesma funcionalidade. Além da descrição da arquitetura e do protótipo, neste trabalho, também é realizada uma avaliação do ambiente ICE. Essa avaliação foi dividida em dois momentos. O primeiro traz a comparação das características do ambiente proposto com algumas ferramentas relacionadas. No segundo momento são apresentados alguns experimentos que visam identificar o overhead inserido pelo ambiente ICE na execução das operaçõess do módulo de gerenciamento de aplicações, desenvolvido e descrito neste trabalho.Some researches have been done over the last years in order to improve the management and access of high performance systems. One of the motivations of these researches is the continuously increase in the number of users who, not rarely, belong to other areas, such as biology, geology, hydrology, etc; so it is necessary to provide some access and also management facilities in these kinds of systems. Furthermore, the users also have access to different kinds of high performance systems, and they have to deal with distinct tools of their underlying, which are not standardize. Therefore, the users need to learn the specificities of each tool in each high performace system that they have permission to access. Aiming to solve this problem, this work proposes an architecture to provide access and management of multiple clusters with extensibility, transparance, interoperability, user-friendly, manageability and maintainability. As a result of the proposed architecture, a prototype called ICE - Integrated Cluster Environment - was developed. The main goals of the architecture and the ICE environment are: (i) the capability of uniforming the manner the cluster tools are used and accessed; (ii) cluster access and transparence use; and (iii) two extensibility levels: the first one refers to capability of extending the number of functionalities/services provided by the environment and the second one concerns to the capability of extending the number of tools, with the same functionality, the system is able to manage. Beyond the architecture and prototype description, this research presents the evaluation of ICE environment, which is divided in two parts. The first one brings the comparison of the features between ICE and some related work. The second part shows some experiments that intend to verify the overhead inserted by ICE environment when performing the tasks of the job management module, also developed and explained in this work.
28
Cluver, Michelle E. "Probing distant clusters : a pre-SALT photometric study of intermediate redshift galaxy cluster." Master's thesis, University of Cape Town, 2005. http://hdl.handle.net/11427/4415.
Full text
29
Popescu, Bogdan. "MASSCLEAN - MASSive CLuster Evolution and ANalysis Package - A New Tool for Stellar Clusters." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1276526207.
Full text
30
Cuciti, Virginia <1989>. "Cluster-scale radio emission: analysis of a mass-selected sample of galaxy clusters." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amsdottorato.unibo.it/8540/1/Tesi_PhD.pdf.
Full textAbstract:
Radio halos are Mpc scale diffuse sources located at the center of a fraction of galaxy clusters. In the current theoretical picture, they form via the re-acceleration of electrons in the ICM by means of turbulence, injected during cluster mergers. This scenario allows basic predictions on the formation history of radio halos that can only be tested by analysing large samples of galaxy clusters with adequate radio and X-ray data.
The main goal of this Thesis is to study the first complete large sample of mass-selected galaxy clusters to obtain solid statistical constraints on the connection between radio halos and the dynamics and mass of the host clusters.
We used the Planck SZ catalogue to select a sample of 75 massive galaxy clusters (M500>6x10^{14}Msun) at redshift z=0.08-0.33 and we collected information on the presence or absence of diffuse emission from the literature and from the large observational (GMRT and JVLA) campaign carried out during this PhD project.
We analysed X-ray Chandra and XMM-Newton data to investigate the dynamical properties of clusters.
We updated the radio power-mass scaling relation for radio halos and we found clear evidence for a bimodal behaviour of clusters in both the radio power-mass plane and, for the first time, in the radio emissivity-mass diagram, with radio halos and non-radio halo clusters following two distinct distributions. Similarly to previous studies, we found that this bimodality is clearly connected to the cluster dynamics. For the very first time, we found an increase of the radio halo fraction with the cluster mass, which is remarkably in agreement with theoretical models.
In addition to the statistics of radio halos, the amount of data available in this Thesis led to the discovery of new radio relics, mini halos and head tail radio galaxies in our clusters.
31
Greab, Maria Corina <1990>. "Inter-Cluster Networks in Europe: Relationships between Biomedical Clusters in Italy and Germany." Master's Degree Thesis, Università Ca' Foscari Venezia, 2016. http://hdl.handle.net/10579/7685.
Full textAbstract:
The thesis investigates the relationships between Italian and German cluster and RIS actors in the biomedical industry. Both countries are main actors in the red biotechnology field, counting on two highly specialized clusters (Mirandola in Italy and Tuttlingen in Germany). Also, other innovative life sciences clusters have developed in the last decades and are at the heart of dynamic regional innovation systems. Literature on the matter is not very extensive yet, so the work attempts to give an overview of the extent of such relations. The aim is to understand what are the relationships between biomedical clusters of Italy and Germany. Based on interviews with RIS and cluster actors and experts in the field, along with publicly available data, the outcome of the research is that relationships between the cluster and RIS actors of the two countries in the biomedical field are still to be developed. Market relations and collaborations research networks exist, but knowledge transfer relations and milieu informal networks are still weak. Such outcome is due to different factors, e.g. differences in public funding for research in the field, or the costly research of partners in the other country. Such causes need further investigation, through a more structured approach and involving more cluster and RIS actors between the two countries, along with a thorough empirical research on the causes that could favor stronger research collaborations between the two countries.
32
Pedersen, David B. "The reactivity of gas-phase neutral transition-metal clusters, reactions of W clusters with cyclopropane and Ta clusters with alkanes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0007/NQ38324.pdf.
Full text
33
Cui, Lifeng. "Photoelectron spectroscopy studies on group IV semiconductor clusters and novel binary clusters." Online access for everyone, 2007. http://www.dissertations.wsu.edu/Dissertations/Spring2007/l_cui_050107.pdf.
Full text
34
Schooler, Paul. "Linked arene clusters : the interaction of transition metal clusters with the cyclophanes." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624962.
Full text
35
Sun, Haojun. "Determining the number of clusters and distinguishing overlapping clusters in data analysis." Thèse, Université de Sherbrooke, 2004. http://savoirs.usherbrooke.ca/handle/11143/5055.
Full textAbstract:
Le processus de Clustering permet de construire une collection d’objets (clusters) similaires au sein d’un même groupe, et dissimilaires quand ils appartiennent à des groupes différents. Dans cette thèse, on s’intéresse a deux problèmes majeurs d’analyse de données: 1) la détermination automatique du nombre de clusters dans un ensemble de données dont on a aucune information sur les structures qui le composent; 2) le phénomène de recouvrement entre les clusters. La plupart des algorithmes de clustering souffrent du problème de la détermination du nombre de clusters qui est souvent laisse à l’utilisateur. L’approche classique pour déterminer le nombre de clusters est basée sur un processus itératif qui minimise une fonction objectif appelé indice de validité. Notre but est de: 1) développer un nouvel indice de validité pour mesurer la qualité d’une partition, qui est le résultat d’un algorithme de clustering; 2) proposer un nouvel algorithme de clustering flou pour déterminer automatiquement le nombre de clusters. Une application de notre nouvel algorithme est présentée. Elle consiste à la sélection des caractéristiques dans une base de données. Le phénomène de recouvrement entre les clusters est un des problèmes difficile dans la reconnaissance de formes statistiques. La plupart des algorithmes de clustering ont des difficultés à distinguer les clusters qui se chevauchent. Dans cette thèse, on a développé une théorie qui caractérise le phénomène de recouvrement entre les clusters dans un modèle de mélange Gaussien d’une manière formelle. À partir de cette théorie, on a développé un nouvel algorithme qui calcule le degré de recouvrement entre les clusters dans le cas multidimensionnel. Dans ce cadre précis, on a étudié les facteurs qui affectent la valeur théorique du degré de recouvrement. On a démontré comment cette théorie peut être utilisée pour la génération des données de test valides et concrètes pour une évaluation objective des indices de validité pax rapport à leurs capacités à distinguer les clusters qui se chevauchent. Finalement, notre théorie est utilisable dans une application de segmentation des images couleur en utilisant un algorithme de clustering hiérarchique.
36
Feyel, Sandra. "Gaseous vanadium, vanadium oxide and hydroxide clusters from clusters to model catalysts." Berlin Logos-Verl, 2008. http://d-nb.info/990757048/04.
Full text
37
Ayakwah, Anthony. "Internationalisation of business clusters : the case of fruit processing clusters in Ghana." Thesis, Middlesex University, 2016. http://eprints.mdx.ac.uk/21276/.
Full textAbstract:
Since Alfred Marshall propounded industrial clusters, the study of spatial organisation over the years has revealed numerous benefits of agglomeration to businesses, countries and regions. Until recently, discussions on the gains associated with internationalising clusters have mainly been situated within the developed economy setting. The key drivers of exporting clusters have mostly been related to cases within more functioning institutional environments. However, factors responsible for driving exporting activities in clusters within developing economies’ setting are a current phenomenon in academic enquiry that has received minimal attention. Thus, the study aims to fill the knowledge gap by investigating the emergence of and dynamism within clusters, thereby understanding the key drivers of exporting fruit processing cluster activities in developing economies like Ghana. The study focuses on spatial and internationalisation theories to draw out key concepts on networking and knowledge. The research adopts a mixed methods approach, using 99 surveys and 24 interviews, to empirically study actors in two fruit processing and exporting clusters. The findings show that, comparatively, palm processing businesses have a more socially embedded network structure that drives exporting activities in the cluster as opposed to the more formal business-like relationship in the pineapple cluster. As a result, parallel social institutions have emerged among the palm processing businesses which are enhancing their exporting capabilities. The findings also reveal how pineapple processors, due to their more outward-looking nature, have been able to externally acquire and transmit ‘tacit’ knowledge on MD2 pineapples through an entrepreneur ‘gatekeeper’. Further evidence shows that processing businesses in the pineapple cluster are mostly set up to internationalise from the onset due to the presence of external investors and the exposure of entrepreneurs to international markets. The results provide a compelling case of born global businesses within a developing economy setting. The research contributes to extant theoretical development and understanding of the key drivers of exports within clustered businesses. Particularly, it emphasises the role spatial organisation plays in exporting clusters within the developing economy setting.
38
Nielson, Curtis R. "A Descriptive Performance Model of Small, Low Cost, Diskless Beowulf Clusters." Diss., CLICK HERE for online access, 2003. http://contentdm.lib.byu.edu/ETD/image/etd280.pdf.
Full text
39
Lugo, Preciado Jesus Gustavo. "Dynamics of ligands on gold surfaces to obtain Janus nanoclusters : a theoretical and experimental investigation." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066570/document.
Full textAbstract:
Une étude théorique couplée à une partie expérimentale a été entreprise sur la dynamique de l'échange de ligand sur des surfaces de nanoclusters (GNC) dans le but de montrer qu'il était possible de contrôler les propriétés structurales et optiques de GNC à travers la composition de la couronne de ligand. Nos études de calcul ont été effectuées par la théorie fonctionnelle de la densité en chimie quantique (approche Kohn - Sham). Nous avons analysé les principales caractéristiques UV - Visible des spectres calculés par TD - DFT / niveau de CAMB3LYP pour les clusters métalliques Au13, Au25 et Au28 protégées par des ligands thiolate, chlorure, et phosphine. Nos résultats montrent qu'il est possible de régler l'énergie de la bande d'absorption la plus basse des clusters d'or par une répartition spécifique des ligands qui contrôle de fait la répartition des charges entre la couronne de ligand et le noyau métallique.En parallèle, nous avons synthétisé une série de clusters de composition Au25 (ATP)x (TP) 18 - x avec 4ATP (4 - aminothiophénol) et TP (thiophénol) par synthèse directe et par échange de ligands. Les mesures de spectroscopie de masse ESI - MS montrent que la nucléarité Au25 est préservée pour tous ces différents clusters. En revanche, l'échange de ligands TP par le DDT (1 - dodécanethiol) dans le mélange conduit à la formation de nanoparticules. Les mesures de spectroscopies IR confirment la présence de deux ligands différents sur la surface de l'or et les analyses SAXS montrent que nous avons une bonne corrélation entre la distance entre deux cœurs métalliques et la longueur du ligand de surfaceWe performed a joint computational – experimental investigation of the dynamics of ligand exchange on gold nanoclusters (GNC) surface with the aim to understand how to control the structural and optical properties of GNC through the design of their ligand shell. Our computational studies were carried out in the framework of the Kohn – Sham implementation of density functional theory in quantum chemistry. We analyzed the main features of UV – Vis spectra computed at the TD – DFT / CAMB3LYP level for the Au13, Au25, and Au28 metallic cores protected by thiolate, chloride, and phosphine ligands. Our results show that it is possible to tune the energy of the lowest absorption band of gold clusters by ligand shell engineering in order to control the charge redistribution between ligand shell and metallic core.In parallel we synthesized a set of Au25(ATP)x(TP)18 – x clusters with different ATP/TP ratios using an adapted Demessence protocol by combining 4ATP (4 – aminothiophenol) and TP (thiophenol) ligands. ESI – MS measurements evidence that for these mixed ligand shells the Au25 nuclearity is preserved. However, the addition of the DDT (1 – dodecanethiol) ligand in the mixture leads to nanoparticle formation. FT – IR spectroscopy confirms the absorption of two different ligands on the gold surface and SAXS shows that we have a good correlation between the distance between two clusters and the length of the ligand protecting them.Finally, we carried out a comparison of the mode of binding and the structural and optical properties of the fully ligated PH3 and NHC GNC with metallic cores of different nuclearities
40
Brustenga, Moncusi Laura. "Parametrising clusters of sections." Doctoral thesis, Universitat Autònoma de Barcelona, 2020. http://hdl.handle.net/10803/669497.
Full textAbstract:
En aquest treball generalitzem clústers de punts d'un esquema al cas relatiu, és a dir,
clústers de seccions d'una família d'esquemes.
Quan la família és llisa, som capaços de veure que existeix un esquema parametritzant els seus clústers de seccions.
el qual és una generalització dels blow ups iterats de Kleiman.En este trabajo generalizamos los clústeres de puntos de un esquema al caso relativo, esto es, clústeres de secciones de una familia de esquemas. Cuando la familia es lisa, somos capaces de demostrar que existe un esquema parametrizando sus clústeres de secciones, el cual es una generalización de los blow up iterados de Kleiman.
In this work we generalise clusters of points of a scheme to the relative setting, that is, we introduce clusters of sections of a family. When the family is smooth, we are able to show that there is a scheme parametrising its clusters of sections of length r, which is a generalisation of Kleiman's iterated blow ups (which parametrise clusters of points).
41
Breukelen, Caroline van. "The most distant clusters." Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491751.
Full textAbstract:
The aim of this Thesis is to develop a new algorithm to detect high-redshift clusters of galaxies, to be used specifically with photometric redshifts derived from the latest near-infrared deep and wide-field imaging surveys. In Chapter 2 I describe the algorithm in detail, whose two main characteristics are: (i) the use of the complete photometric redshift probability distributions for all galaxies and (ii) the combination oftwo techniquesto select clusters, in order to minimise the detection of spurious sources. In Chapter 3 I present the first high-redshift optically/infrared selected cluster catalogue in the Subaru XMM-Newton Deep Field. The catalogue contains 13 clusters at 0.6 < z < 1.4 over 0.5 deg2 , which is in line with theoretical expectations. Chapter 4 describes the follow-up multi-object spectroscopy on six of the highest-redshift clusters. The clusters' reality is confirmed, and the previously derived photometric redshifts are compared with the spectroscopic redshifts. Our highest-redshift cluster candidate, CVB13 at z = 1.4, is discussed in detail in Chapter 5. The spectroscopic data reveal that instead of one massive cluster, the system comprises three lower-mass systems within b.z = 0.08, the most robust of which lying at z = 1.45. A cluster of similar mass is found at z = 1.28. I conclude that it is extremely difficult to obtain photometric redshifts accurate enough to distinguish between massive clusters and superimposed groups. Therefore it remains challenging to determine the cluster mass function at high redshift without spectroscopic follow-up. In Chapter 6 I investigate the X-ray and radio properties of four high-redshift clusters. I find that the two virialised clusters show diffuse X-ray emission but contain few, if any, X-ray point sources or radio galaxies. In contrast, the other two pre-virialisation clusters have a large X-ray and radio AGN population. It is likely that as the cluster virialises, AGN activity is extinguished, leaving the clusters quiescent.
42
Abernethy, Colin D. "Inorganometallic clusters containing vanadium." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0026/NQ29462.pdf.
Full text
43
Mao, Qian. "Clusters Identification: Asymmetrical Case." Thesis, Uppsala universitet, Informationssystem, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-208328.
Full textAbstract:
Cluster analysis is one of the typical tasks in Data Mining, and it groups data objects based only on information found in the data that describes the objects and their relationships. The purpose of this thesis is to verify a modified K-means algorithm in asymmetrical cases, which can be regarded as an extension to the research of Vladislav Valkovsky and Mikael Karlsson in Department of Informatics and Media. In this thesis an experiment is designed and implemented to identify clusters with the modified algorithm in asymmetrical cases. In the experiment the developed Java application is based on knowledge established from previous research. The development procedures are also described and input parameters are mentioned along with the analysis. This experiment consists of several test suites, each of which simulates the situation existing in real world, and test results are displayed graphically. The findings mainly emphasize the limitations of the algorithm, and future work for digging more essences of the algorithm is also suggested.
44
Abernethy, C. D. "Inorganometallic clusters containing vanadium." Thesis, University of New Brunswick, 1997. http://hdl.handle.net/1882/920.
Full text
45
Eke, Vincent R. "Cosmology with galaxy clusters." Thesis, Durham University, 1996. http://etheses.dur.ac.uk/5195/.
Full textAbstract:
A number of different ways of using galaxy clusters to provide information concerning fundamental cosmological parameters are considered. Using the observed local cluster X-ray temperature function in conjunction with the Press-Schechter formalism, the normalisation of a CDM power spectrum is found to be σ(_8) = (0.52 ± 0.04)Ω(_o)(^-0.46+0.10Ωo) if Ʌ(_o) = 0 or σ(_8) = (0.52 ± 0.04)Ω(_o)(^-0.52+0.13Ωo) if Ʌ(_o) = 1 — Ω(_0). This result is employed to provide detailed predictions for the abundance of clusters at high redshift, and the differences between predictions for various cosmologies are emphasised. New tests using available high-redshift cluster data are presented. For the adopted power spectrum normalisation, it is found that an Ω(_o) = 0.3, Ʌ(_o) = 0 cosmology vastly overpredicts the number of clusters that were actually found with 0.4 < z < 0.6 in the Extended Medium Sensitivity Survey. The rapid variation in the expected abundance with both σ(_8) and the assumed scatter in the L(_x) – T_x) relation limits the significance of this result, but this model is still ruled out at the ~ 95% confidence level. Order statistics are utilised to calculate the probability of finding extremely massive clusters at high redshifts. With presently available observations, no interesting upper limit can yet be placed on Ω(_o). Systematic variations in the cluster-cluster correlation length calculated using numerical simulations and resulting from the definition of clusters, the chosen σ(_8), the mean intercluster separation and whether or not redshift space distortions are included, are found to exceed the statistical errors on the measurements. Although the uncertainty in ε(_cc) derived from an ensemble of 10 Standard CDM simulations is not sufficient at large separations to remove the discrepancy between this model and results from the APM Cluster Survey, this does suggest that the level at which such a scenario has previously been rejected using ε(_cc) should be significantly reduced. Details and a few tests of a procedure for improving mass and spatial resolution in cosmological simulations are presented. After showing that a coarse-sampling technique can be used to represent the large-scale forces sufficiently accurately, the method is then used to perform ten simulations of clusters forming in an Ω(_o) = 0.3, Ʌ(_o) = 0.7 CDM cosmology. To incorporate non-radiative gas, an SPH code adapted to work on a GRAPEsupercomputer is used. The resulting clusters are found to have virial radii in good agreement with the predictions of the spherical collapse model, dark matter density profiles well described by the 'NFW formula and isothermal central gas components, with temperatures dropping by a factor of ~ 2 near the virial radius. The evolution of these properties is studied as well as that of the bulk quantities describing the clusters, with particular reference to the β parameters relating cluster gas temperatures with virial mass or velocity dispersion. Slightly greater evolution in the luminosity is seen than in previous Ω(_o) = 1 simulations, suggesting that the improved resolution is important. The β parameter relevant to the normalisation of the mass fluctuation spectrum is found to be 0.98 ± 0.07.
46
Temple, John. "Supported high nuclearity clusters." Thesis, University of Liverpool, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333573.
Full text
47
Sabounchei, S. J. S. Z. "Carbide and nitride clusters." Thesis, University of Liverpool, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.291737.
Full text
48
Bott, Adrian William. "Clusters : synthesis and topology." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316027.
Full text
49
Jackson, Patricia A. "Mixed-metal organometallic clusters." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304280.
Full text
50
Shongwe, Musa Sipho. "Metal-rich metallaborane clusters." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315214.
Full text