Globular clusters are not simple stellar populations. Practically all globular clusters show multiple populations (MPs), where at the same metallicity [Fe/H], approximately half of their stars are enriched by the products of high-temperature hydrogen burning relative to the rest that show field-like abundances. The source of enrichment for forming the enriched population is an unresolved problem. Interacting massive binaries are an underexplored proposed source of enrichment. Many assessments of the theory are based on only one modelled binary. We simulate a suite of metal-intermediate, [Fe/H]=-1.44, interacting binaries with initial primary masses of 10 to 40 solar masses, with mass ratios ranging from 0.15 to 0.9, over periods ranging from about 2 to 700 days using MESA. Our simulations show that binaries at higher masses, higher mass ratios, and near our upper period limit tend to be the most enriching with ejecta showing HeNaCNOAlMg variations consistent with hot-H burning. Some binaries do not eject material, suggesting binary mass loss can contribute to the dilution of enrichment. As a realistic population, binaries within our parameter space eject about ten times as much mass as they would as single stars. Ejection occurs on timescales of about 11 Myr, consistent with observed and theoretical limits on the age spreads for MPs. Our systems are rare, making them more suited to explaining the stochastic nature of MPs but not the large fraction of enriched stars. Spreads in He, N, Na, C, and Al for our ejecta could reasonably explain the observed spreads in clusters. Reduced variation in O and Mg suggests more massive binaries should be investigated. A multi-scale approach to cluster formation with multiple types of enrichment sources is a necessary next step for validating MP formation scenarios. / Thesis / Master of Science (MSc) / The majority of stars form in star clusters. Globular clusters are the oldest and most massive type of star cluster. Formerly thought to be made of stars of the same age and chemical composition, nearly all observed globular clusters are now known to host multiple populations. About half of their stars form from similar material as isolated stars. The other half show signs of enrichment. How enriched stars get their enriching material is an open problem in cluster formation. Pairs of stars orbiting each other as binaries were proposed to eject the material needed to form these stars. We model 408 binaries to find that some systems eject large amounts of enrichment, especially when the stars are more massive. The rarity of these systems suggests binaries can explain the variations seen in multiple populations between clusters but cannot fully explain the large fraction of enriched stars seen.

In this Thesis experimental studies of nano-clusters using synchrotron radiation based photoelectron (UPS and XPS) and Auger Electron Spectroscopy (AES) are presented. The investigations may be divided into two parts where the first reports on the structure of heterogeneous two component clusters, and the second concerns electronic decay processes. Using photoelectron spectroscopies as investigative tools the radial composition of heteroclusters of argon mixed with xenon, krypton or neon has been determined. Two methods of heterogeneous cluster production were employed: co-expansion and doping/pick-up. By analyzing the line shapes, energy positions, and widths of the spectral cluster features the radial composition of the clusters produced by co-expansion were found to form close-to-equilibrium structures, placing the component with larger cohesive energy in the cluster core while the second component was to varying degree segregated toward the surface. By instead using the doping/pick-up technique the opposite radial structures, i.e. far-from-equilibrium structures, may be formed. In the case of argon/krypton clusters a similar surface structure is formed regardless of production technique. The second part of the Thesis concerns post-ionization decay processes. Experimental evidence for the Interatomic Coulombic Decay process, a theoretically predicted decay channel, is presented in a study of homogeneous neon clusters. The time scale of the decay was determined to 6±1 fs for bulk atoms and >30 fs for surface atoms in the neon cluster, showing the connection between local geometry and dynamics of the decay. Another channel for electronic relaxation is Auger decay. This Thesis presents a method of disentangling the spectral surface and bulk responses from clusters in Auger spectra. Studies of argon clusters show that the AES technique is more surface sensitive than XPS, even at the same electron kinetic energy. Furthermore, the effect scattering of the photoelectron has on the Auger spectra was investigated. Special effort was put into explaining an experimentally observed photon energy dependent intensity appearing on the high-kinetic energy side on the Auger signal. We propose that this intensity is due to a solid state-specific photoelectron recapture process we name Pre-Auger Recapture (PAR), which affects the kinetic energy of the Auger electrons.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Tourism comprises a set of equipment and services offered that together form the tourism product. Due to complementarity, interdependence and geographic concentration it is possible to understand destinations as clusters, since territorial grouping that characterizes the tourism product. Considering the tourists clusters fragmented composition emerges the actors need to establish collaboration relations and partnerships in interorganizational networks. It should be highlighted that to obtain competitive advantages through networks, the existence of a governance structure capable to organize the relationships between local actors is required, in order to ensure the guarantee of actors collective interests. This study aims to propose a model of analysis of governance in tourism clusters. The specific goals are: (a) test the model proposed it in the coordination structure and mechanisms involved in the Associação dos Produtores de Vinhos Finos do Vale dos Vinhedos - Association of Fine Wine Producers of the Vineyards Valley - (APROVALE) formation; (b) identify the actors which comprise APROVALE s tourist governance structure; (c) describe and analyse APROVALE structure; (d) identify, describe and analyse coordination mechanisms involved in APROVALE governance structure formation; and, (e) identify and analyse institutional arrangement formed from Vineyards Valley tourist governance structure. In order to do so, an exploratory and qualitative case study was suggested. The data was collected from primary and secondary sources. The secondary sources comprised documental/ bibliographic research. The primary sources comprised the non-participant observation and twelve semi-structured interviews with local actors, whereas four are public actors and eight private ones. The data set were analysed through content analyses. From these data, we draw on a research framework from which governance model of analyses in tourist destinations was proposed. The model is structured in the following categories: (1) local context; (2) destination governance structure; (3) destination governance development; (4) destination governance coordination; (5) destination governance results; and (6) institutional arrangement pattern. The results analyses were carried out from the previously established model, through which governance analysis was conducted. The results show that APROVALE is a private association that adopts an administrative structure composed of (a) General Assembly; (b) High Council; (c) Executive Board; (d) Audit Council; and (e) Geographic Indication Technical and Research Indicator Council. The organization has 68 members. The organization has shortage of attractive, entertainment activities, formalized interaction with the government and involvement with society. It should be highlighted that the Association Statute is the instrument which formalize and regulates the organization and members behaviors. Members share resources as wine grapes and wine productions methods. The results indicated: power equality between partners, the existence of high level trust, low incidence of conflict situations and the prioritization of collective interests. APROVALE adopt accountability and transparency mechanisms and provides a set of compensations to its members, such as (a) consolidation of Vineyards Valley as a destination; (b) increasing tourist demand; (c) media (investment) return, and (d) offer qualification. After all, was identified that APROVALE institutional arrangement pattern is enterprise and Network Administrative Organization (NAO). The proposed model presents a number of factors can influence the success of networks and governances to seek qualify a tourism cluster. / O turismo é composto pelo conjunto de equipamentos e serviços ofertados que juntos formam o produto turístico. Em decorrência a complementaridade existente, interdependência e concentração geográfica de atores, surge a possibilidade de se compreender os destinos como clusters, tendo em vista o agrupamento territorial que caracteriza o produto turístico. Considerando a composição fragmentada dos clusters turísticos, emerge-se a necessidade dos atores estabelecerem relações de colaboração e parcerias em redes interorganizacionais. Salientando-se que para obter vantagens competitivas compartilhadas por meio de rede se fazem necessária a existência uma governança capaz de organizar as relações entre os atores locais, assegurando que esses tenham seus interesses coletivos garantidos. O presente estudo tem como objetivo propor um modelo para análise da governança de uma rede de atores locais em clusters turísticos. Como objetivos específicos, tem-se: (a) testar o modelo proposto na estrutura e nos mecanismos de coordenação envolvidos na formação da APROVALE; (b) identificar os atores que integram a estrutura de governança da APROVALE; (c) descrever e analisar a estrutura da APROVALE; (d) identificar, descrever e analisar os mecanismos de coordenação envolvidos na formação da governança turística da APROVALE; e (e) identificar e analisar o arranjo institucional formado a partir da estrutura de governança turística do Vale dos Vinhedos/RS. Nos métodos, propõe-se a realização de um estudo de caso, exploratório e qualitativo. Procura-se trabalhar fontes secundárias, a partir de uma pesquisa documental/bibliográfica e dados primários coletados através de observação não-participante e realização de 12 entrevistas semi-estruturadas junto aos atores locais. A interpretação dos dados é proferida da análise de conteúdo. Obtém-se um framework de pesquisa, a partir do qual se propôs um modelo para análise da governança em destinos turísticos, dividido nas seguintes categorias: (1) contexto local; (2) estrutura da governança de destino; (3) desenvolvimento da governança de destino; (4) coordenação da governança de destino, (5) resultados da governança de destino e (6) padrão de arranjo institucional. A partir do modelo se procederam as análises da governança. Como resultados, tem-se que a APROVALE constitui uma associação privada, que possui uma estrutura administrativa composta por: (a) Assembleia Geral, (b) Conselho Superior, (c) Diretoria Executiva, (d) Conselho Fiscal e (e) Conselho Indicador de Indicação Geográfica, Técnico e de Pesquisa. A entidade possui 68 associados, apresentando uma carência por atrativos, atividades de entretenimento, interação formalizada com o poder público e envolvimento com a sociedade. Destaca-se o Estatuto como o instrumento que formaliza e regula o comportamento da entidade e seus associados. Os associados compartilham recursos como a uva e as técnicas de produção de vinho. Aponta-se para uma isonomia de poder entre os parceiros, a existência de um elevado grau de confiança, a baixa incidência de situações conflituosas e a priorização dos interesses coletivos. A APROVALE adota mecanismos de prestação de contas e transparência junto aos seus associados e proporciona compensações como: (a) consolidação do destino Vale dos Vinhedos, (b) crescente demanda de turistas, (c) retorno de mídia e (d) qualificação da oferta. Por fim, identificou-se o padrão de arranjo institucional formado pela APROVALE como empresarial e Organização Administrativa da Rede (OAR). Considera-se que o modelo proposto apresenta um conjunto de elementos capaz de influenciar no sucesso de redes de cooperação e de governanças voltadas para a qualificação de um cluster turístico.

This thesis builds around the idea of a biofuel production process that is comprised of biomass production, biomass gasification, gas cleaning, and fuel production. In this work, we specifically looked into H2S removal as a part of cleaning the producer gas and flocculation of microalgae which is involved in the harvesting of microalgae after biomass production. One of the impurities to remove from the producer gas is hydrogen sulfide which can be removed by using a packed bed of zinc oxide. Despite the regular use, it was only recently shown that during reaction with H2S, nano-size particles of ZnO exhibit void formation and outward growth. In this work, a micro-scale model was introduced to describe the void formation and outward growth. On the macro-scale, the simulations captured pore clogging of pellets due to the outward growth. The pore clogging prevents the full conversion of pellets and consequently leads to shorter breakthrough times of beds. The second problem investigated here deals with the flocculation of microalgae. Microalgae is produced in relatively low concentrations in the incubator liquid medium and during the harvesting, the concentration is increased to an acceptable level. The harvesting process includes a flocculation followed by a filtration or centrifuge unit. During flocculation, microalgae are stimulated to aggregate and form clusters. The experiments showed that the mean size of clusters formed during flocculation increases with time to a maximum and then starts decreasing, resulting in an overshoot in the mean size profile. The size of clusters influence the efficiency of the afterward filtration or centrifuge, thus it is of interest to carefully track the size evolution of clusters, making the studying of overshoot a crucial research topic. In this work, the possible mechanisms behind this overshoot were investigated. / <p>QC 20170330</p>

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / There is an increasing desire in many organizations, including NASA and the DoD, to use constellations or fleets of autonomous spacecraft working together to accomplish complex mission objectives. At the Air Force Research Laboratory’s (AFRL) Space Vehicles Directorate we are investigating and developing architectures for commanding and controlling a cluster of cooperating satellites. For many space missions, large monolithic satellites are required to meet mission requirements. In many cases this results in costly satellites which are more complex, more susceptible to failure, and which have performance characteristics that are less than optimal due to realistic physical size limitations. Recently various organizations have begun to explore how distributed clusters of cooperating satellites can replace their larger monolithic counterparts resulting in an overall cost reduction, enhanced mission performance, and increased system fault tolerance. Large clusters of satellites flying in formation are required to have some level of on-board autonomy in order to: fly within specified tolerance levels; perform collision avoidance; address fault detection, isolation, and resolution (FDIR); share knowledge; and plan and schedule activities. In addition, from an operations standpoint, commanding and controlling a large cluster of satellites can be very burdensome for ground operators. At AFRL we are addressing these issues by development of an on-board Cluster Management system which will, in essence, provide the capability to treat a cluster of satellites as a single virtual satellite. A systems level approach is being taken, therefore from a ground perspective the ground control station must also be able to treat the cluster as a virtual satellite. [1] This paper will describe our Cluster Management system, which is the intelligent entity that is responsible for making cluster level decisions and which enables the satellite cluster to function as a virtual satellite. The cluster manager functionality can be broken down into the following five areas: • Command and control • Cluster data management • Formation flying • Fault management • On-board Planning This paper will contain a detailed description of the Cluster Manager architecture along with its various modules.

China has now become the largest producer and exporter of textile and clothing products in the world. The objective of this research is to explore the relationship between the complicated interactive process of institutional change and the development of industrial clusters in China. It focuses on the distinctive institutional factors that have allowed the textile and clothing clusters in China to benefit from globalisation while those in other transitional economies have not done so. The research also aims to make a thorough investigation into how the dynamic change of the public-private interface has influenced the development and upgrading of the textile and clothing clusters in contemporary China-in-transition, with all the political and social implications that the process entails. The research mainly uses the New Institutional Economics Approach (NIE) and gives weight to institutional change through multiple case studies of textile and clothing clusters in Zhejiang province, East China. The micro case studies are effective in illustrating the interaction between institutional change and industrial development. The research argues that the unique institutional factors leading to the rapid development of textile and clothing clusters in China include hybrid ownership, public entrepreneurship and the specialised wholesale market. The research has also shown that the theory of local state corporatism alone fails to explain the great success of textile and clothing clusters in China. The development and upgrading of textile and clothing clusters in China has witnessed extraordinary institutional change through co-evolution between the public sector and the private sector, which can be reflected through the interaction among social networks, entrepreneurship and performance of local government. The flexibility in the public-private interface is one unique endogenous institutional arrangement embedded in the economic system in China. It is a dynamic process of institutional embeddedness, deembeddedness and reembeddedness with a diversity of economic regimes coexisting at different hierarchies of government

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Radio frequency power margins in well planned line-of-sight (LOS) air-to-ground digital data transmission systems usually produce signal to noise ratios (SNR) that can deliver error free service. Sometimes field performance falls short of design and customer expectations. Recent flight tests conducted by the tri-service Advanced Range Telemetry (ARTM) project confirm that the dominant source of bit errors and short term link failures are “clusters” of severe error burst activity produced by flat fading, dispersive fading and poor antenna patterns on airborne vehicles. This paper introduces the techniques used by ARTM to measure bit error performance of aeronautical telemetry links.

This research addresses two puzzles: Why do similar regions within countries pursue different commitment strategies towards growing their bioscience industries? Why do some change in response to a global financial shock and others do not? I argue that the presence and strength of a knowledge-oriented strategy team (KOST) helps to explain different levels of and changes in bioscience commitment strategies. The study weaves in additional explanations including natural resources, rival industries, national institutions and path dependence. The most significant finding of this research is that those Canadian provinces that established a strong KOST prior to the 2008 global financial crisis "puzzled and powered through" to maintain high level commitments to their bioscience industries afterwards. Their KOSTs engaged in disruptive social learning and coordinative bargaining processes.

We present a detailed study of the colours of late-type galaxy discs for ten of the EDisCS galaxy clusters with 0.5 less than or similar to z less than or similar to 0.8. Our cluster sample contains 172 spiral galaxies, and our control sample is composed of 96 field disc galaxies. We deconvolved their ground-based V and I images obtained with FORS2 at the VLT with initial spatial resolutions between 0.4 and 0.8 arcsec to achieve a final resolution of 0.1 arcsec with 0.05 arcsec pixels, which is close to the resolution of the ACS at the HST. After removing the central region of each galaxy to avoid pollution by the bulges, we measured the V - I colours of the discs. We find that 50% of cluster spiral galaxies have disc V - I colours redder by more than 1 sigma of the mean colours of their field counterparts. This is well above the 16% expected for a normal distribution centred on the field disc properties. The prominence of galaxies with red discs depends neither on the mass of their parent cluster nor on the distance of the galaxies to the cluster cores. Passive spiral galaxies constitute 20% of our sample. These systems are not abnormally dusty. They are are made of old stars and are located on the cluster red sequences. Another 24% of our sample is composed of galaxies that are still active and star forming, but less so than galaxies with similar morphologies in the field. These galaxies are naturally located in the blue sequence of their parent cluster colour-magnitude diagrams. The reddest of the discs in clusters must have stopped forming stars more than similar to 5 Gyr ago. Some of them are found among infalling galaxies, suggesting preprocessing. Our results confirm that galaxies are able to continue forming stars for some significant period of time after being accreted into clusters, and suggest that star formation can decline on seemingly long (1 to 5 Gyr) timescales.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy