891 resultados para saturation modal gain


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Since core-collapse supernova simulations still struggle to produce robust neutrino-driven explosions in 3D, it has been proposed that asphericities caused by convection in the progenitor might facilitate shock revival by boosting the activity of non-radial hydrodynamic instabilities in the post-shock region. We investigate this scenario in depth using 42 relativistic 2D simulations with multigroup neutrino transport to examine the effects of velocity and density perturbations in the progenitor for different perturbation geometries that obey fundamental physical constraints (like the anelastic condition). As a framework for analysing our results, we introduce semi-empirical scaling laws relating neutrino heating, average turbulent velocities in the gain region, and the shock deformation in the saturation limit of non-radial instabilities. The squared turbulent Mach number, 〈Ma2〉, reflects the violence of aspherical motions in the gain layer, and explosive runaway occurs for 〈Ma2〉 ≳ 0.3, corresponding to a reduction of the critical neutrino luminosity by ∼25∼25 per cent compared to 1D. In the light of this theory, progenitor asphericities aid shock revival mainly by creating anisotropic mass flux on to the shock: differential infall efficiently converts velocity perturbations in the progenitor into density perturbations δρ/ρ at the shock of the order of the initial convective Mach number Maprog. The anisotropic mass flux and ram pressure deform the shock and thereby amplify post-shock turbulence. Large-scale (ℓ = 2, ℓ = 1) modes prove most conducive to shock revival, whereas small-scale perturbations require unrealistically high convective Mach numbers. Initial density perturbations in the progenitor are only of the order of Ma2progMaprog2 and therefore play a subdominant role.

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The provision of physical and social infrastructure in the form of roads, green spaces and community facilities has traditionally been provided for by the state through the general taxation system. However, as the state has been transformed along more neoliberal lines, the private sector is increasingly relied upon to deliver public goods and services. Planning gain agreements have flourished within this context by offering another vehicle through which local facilities are privately funded. Whilst these agreements reflect the broader dynamics of neoliberalism, they are commonly viewed as a tool which can be employed to challenge these very dynamics by empowering local communities to secure more just planning outcomes. This paper counters such claims. Based on evidence gathered from 80 interviews with planners, councillors, developers and community groups in Ireland, the paper demonstrates how planning gain agreements have been strategically redeployed by the holders of political and economic power to serve their own ends. In seeking to understand why and how this has occurred, specific consideration is given to the changing power dynamics between the state and private capital under neoliberalism. The paper highlights how institutional arrangements have enabled developers to infiltrate the political sphere in more subtle and implicit ways than ever before. We conclude by arguing that planning gain must be understood as a mechanism which has been manipulated in ways which essentially work to preserve and enhance, rather than redress, existing power imbalances in the planning system by facilitating large scale transfers of wealth upwards in society.

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Impactive contact between a vibrating string and a barrier is a strongly nonlinear phenomenon that presents several challenges in the design of numerical models for simulation and sound synthesis of musical string instruments. These are addressed here by applying Hamiltonian methods to incorporate distributed contact forces into a modal framework for discrete-time simulation of the dynamics of a stiff, damped string. The resulting algorithms have spectral accuracy, are unconditionally stable, and require solving a multivariate nonlinear equation that is guaranteed to have a unique solution. Exemplifying results are presented and discussed in terms of accuracy, convergence, and spurious high-frequency oscillations.

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This study is a corpus-based comparison between student essays written in the subject areas of English linguistics and literature at undergraduate level. They are 200 Bachelor degree theses submitted at a variety of university departments (such as English, Language and Literature, Humanities, Social and Intercultural Studies) in Sweden. The comparison concerns frequencies of core modal verbs and how often they occur together with the I, we and it subject pronouns and in the structures this/the [essay, study, project, thesis] when students attempt to communicate their personal claims. Quantitative and qualitative analyses of the essays show few similarities in the ways that core modal verbs appear in both disciplines. The results indicate mainly distinct differences, especially in relation to clusters and variation of performative verbs. Specific patterns in the ways that students use core modal verbs as hedges have also been identified.

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Excess deaths from cardiovascular disease are a major contributor to the significant reduction in life expectancy experienced by people with schizophrenia. Important risk factors in this are smoking, alcohol misuse, excessive weight gain and diabetes. Weight gain also reinforces service users’ negative views of themselves and is a factor in poor adherence with treatment. Monitoring of relevant physical health risk factors is frequently inadequate, as is provision of interventions to modify these. These guidelines review issues surrounding monitoring of physical health risk factors and make recommendations about an appropriate approach. Overweight and obesity, partly driven by antipsychotic drug treatment, are important factors contributing to the development of diabetes and cardiovascular disease in people with schizophrenia. There have been clinical trials of many interventions for people experiencing weight gain when taking antipsychotic medications but there is a lack of clear consensus regarding which may be appropriate in usual clinical practice. These guidelines review these trials and make recommendations regarding appropriate interventions. Interventions for smoking and alcohol misuse are reviewed, but more briefly as these are similar to those recommended for the general population. The management of impaired fasting glycaemia and impaired glucose tolerance (‘pre-diabetes’), diabetes and other cardiovascular risks, such as dyslipidaemia, are also reviewed with respect to other currently available guidelines. These guidelines were compiled following a consensus meeting of experts involved in various aspects of these problems. They reviewed key areas of evidence and their clinical implications. Wider issues relating to primary care/secondary care interfaces are discussed but cannot be resolved within guidelines such as these.

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Atualmente, a internacionalização é uma estratégia adotada por muitas empresas, independentemente da sua dimensão com o intuito de enfrentar o abrandamento económico no seu mercado doméstico e impulsionar o seu crescimento. No caso das PME, as principais razões que as levam a sair do seu mercado doméstico e a arriscar em mercados externos prendem-se com motivações reativas e muitas vezes exógenas, como sejam a saturação do mercado doméstico, as pressões da concorrência e as relações com os clientes. Assim, a crise financeira no país, aliada à crise no setor da construção civil, leva esta PME portuguesa, do ramo da carpintaria de limpo, a procurar novas oportunidades no exterior. No entanto, como tem consciência da falta de experiência e conhecimento nos mercados internacionais, começa por abordar os mercados numa lógica de procura de novas oportunidades, aproveitando as oportunidades que lhe são dirigidas e vendo nestas uma forma de aprofundar relacionamentos e ganhar experiência neste âmbito. Posteriormente, este conhecimento e experiência permitir-lhe-á enveredar por uma estratégia de internacionalização mais ativa, abandonando/diminuindo a lógica de oportunidade e apostando numa lógica mais estruturada e planeada. Este trabalho, ao tirar proveito de um único estudo de caso, pretende analisar a perspetiva evolutiva da empresa, e como uma estratégia empreendedora, a confiança e a incorporação em redes de relacionamentos facilitam o processo de abertura aos mercados externos.

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Résumé : En raison de sa grande étendue, le Nord canadien présente plusieurs défis logistiques pour une exploitation rentable de ses ressources minérales. La TéléCartographie Prédictive (TCP) vise à faciliter la localisation de gisements en produisant des cartes du potentiel géologique. Des données altimétriques sont nécessaires pour générer ces cartes. Or, celles actuellement disponibles au nord du 60e parallèle ne sont pas optimales principalement parce qu’elles sont dérivés de courbes à équidistance variable et avec une valeur au mètre. Parallèlement, il est essentiel de connaître l'exactitude verticale des données altimétriques pour être en mesure de les utiliser adéquatement, en considérant les contraintes liées à son exactitude. Le projet présenté vise à aborder ces deux problématiques afin d'améliorer la qualité des données altimétriques et contribuer à raffiner la cartographie prédictive réalisée par TCP dans le Nord canadien, pour une zone d’étude située au Territoire du Nord-Ouest. Le premier objectif était de produire des points de contrôles permettant une évaluation précise de l'exactitude verticale des données altimétriques. Le second objectif était de produire un modèle altimétrique amélioré pour la zone d'étude. Le mémoire présente d'abord une méthode de filtrage pour des données Global Land and Surface Altimetry Data (GLA14) de la mission ICESat (Ice, Cloud and land Elevation SATellite). Le filtrage est basé sur l'application d'une série d'indicateurs calculés à partir d’informations disponibles dans les données GLA14 et des conditions du terrain. Ces indicateurs permettent d'éliminer les points d'élévation potentiellement contaminés. Les points sont donc filtrés en fonction de la qualité de l’attitude calculée, de la saturation du signal, du bruit d'équipement, des conditions atmosphériques, de la pente et du nombre d'échos. Ensuite, le document décrit une méthode de production de Modèles Numériques de Surfaces (MNS) améliorés, par stéréoradargrammétrie (SRG) avec Radarsat-2 (RS-2). La première partie de la méthodologie adoptée consiste à faire la stéréorestitution des MNS à partir de paires d'images RS-2, sans point de contrôle. L'exactitude des MNS préliminaires ainsi produits est calculée à partir des points de contrôles issus du filtrage des données GLA14 et analysée en fonction des combinaisons d’angles d'incidences utilisées pour la stéréorestitution. Ensuite, des sélections de MNS préliminaires sont assemblées afin de produire 5 MNS couvrant chacun la zone d'étude en totalité. Ces MNS sont analysés afin d'identifier la sélection optimale pour la zone d'intérêt. Les indicateurs sélectionnés pour la méthode de filtrage ont pu être validés comme performant et complémentaires, à l’exception de l’indicateur basé sur le ratio signal/bruit puisqu’il était redondant avec l’indicateur basé sur le gain. Autrement, chaque indicateur a permis de filtrer des points de manière exclusive. La méthode de filtrage a permis de réduire de 19% l'erreur quadratique moyenne sur l'élévation, lorsque que comparée aux Données d'Élévation Numérique du Canada (DNEC). Malgré un taux de rejet de 69% suite au filtrage, la densité initiale des données GLA14 a permis de conserver une distribution spatiale homogène. À partir des 136 MNS préliminaires analysés, aucune combinaison d’angles d’incidences des images RS-2 acquises n’a pu être identifiée comme étant idéale pour la SRG, en raison de la grande variabilité des exactitudes verticales. Par contre, l'analyse a indiqué que les images devraient idéalement être acquises à des températures en dessous de 0°C, pour minimiser les disparités radiométriques entre les scènes. Les résultats ont aussi confirmé que la pente est le principal facteur d’influence sur l’exactitude de MNS produits par SRG. La meilleure exactitude verticale, soit 4 m, a été atteinte par l’assemblage de configurations de même direction de visées. Par contre, les configurations de visées opposées, en plus de produire une exactitude du même ordre (5 m), ont permis de réduire le nombre d’images utilisées de 30%, par rapport au nombre d'images acquises initialement. Par conséquent, l'utilisation d'images de visées opposées pourrait permettre d’augmenter l’efficacité de réalisation de projets de SRG en diminuant la période d’acquisition. Les données altimétriques produites pourraient à leur tour contribuer à améliorer les résultats de la TCP, et augmenter la performance de l’industrie minière canadienne et finalement, améliorer la qualité de vie des citoyens du Nord du Canada.

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Thesis (Ph.D.)--University of Washington, 2016-07

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L’augmentation exponentielle de la demande de bande passante pour les communications laisse présager une saturation prochaine de la capacité des réseaux de télécommunications qui devrait se matérialiser au cours de la prochaine décennie. En effet, la théorie de l’information prédit que les effets non linéaires dans les fibres monomodes limite la capacité de transmission de celles-ci et peu de gain à ce niveau peut être espéré des techniques traditionnelles de multiplexage développées et utilisées jusqu’à présent dans les systèmes à haut débit. La dimension spatiale du canal optique est proposée comme un nouveau degré de liberté qui peut être utilisé pour augmenter le nombre de canaux de transmission et, par conséquent, résoudre cette menace de «crise de capacité». Ainsi, inspirée par les techniques micro-ondes, la technique émergente appelée multiplexage spatial (SDM) est une technologie prometteuse pour la création de réseaux optiques de prochaine génération. Pour réaliser le SDM dans les liens de fibres optiques, il faut réexaminer tous les dispositifs intégrés, les équipements et les sous-systèmes. Parmi ces éléments, l’amplificateur optique SDM est critique, en particulier pour les systèmes de transmission pour les longues distances. En raison des excellentes caractéristiques de l’amplificateur à fibre dopée à l’erbium (EDFA) utilisé dans les systèmes actuels de pointe, l’EDFA est à nouveau un candidat de choix pour la mise en œuvre des amplificateurs SDM pratiques. Toutefois, étant donné que le SDM introduit une variation spatiale du champ dans le plan transversal de la fibre, les amplificateurs à fibre dopée à l’erbium spatialement intégrés (SIEDFA) nécessitent une conception soignée. Dans cette thèse, nous examinons tout d’abord les progrès récents du SDM, en particulier les amplificateurs optiques SDM. Ensuite, nous identifions et discutons les principaux enjeux des SIEDFA qui exigent un examen scientifique. Suite à cela, la théorie des EDFA est brièvement présentée et une modélisation numérique pouvant être utilisée pour simuler les SIEDFA est proposée. Sur la base d’un outil de simulation fait maison, nous proposons une nouvelle conception des profils de dopage annulaire des fibres à quelques-modes dopées à l’erbium (ED-FMF) et nous évaluons numériquement la performance d’un amplificateur à un étage, avec fibre à dopage annulaire, à ainsi qu’un amplificateur à double étage pour les communications sur des fibres ne comportant que quelques modes. Par la suite, nous concevons des fibres dopées à l’erbium avec une gaine annulaire et multi-cœurs (ED-MCF). Nous avons évalué numériquement le recouvrement de la pompe avec les multiples cœurs de ces amplificateurs. En plus de la conception, nous fabriquons et caractérisons une fibre multi-cœurs à quelques modes dopées à l’erbium. Nous réalisons la première démonstration des amplificateurs à fibre optique spatialement intégrés incorporant de telles fibres dopées. Enfin, nous présentons les conclusions ainsi que les perspectives de cette recherche. La recherche et le développement des SIEDFA offriront d’énormes avantages non seulement pour les systèmes de transmission future SDM, mais aussi pour les systèmes de transmission monomode sur des fibres standards à un cœur car ils permettent de remplacer plusieurs amplificateurs par un amplificateur intégré.

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The work presented in this thesis is concerned with the dynamical behavior of a CBandola's acoustical box at low resonances -- Two models consisting of two and three coupled oscillators are proposed in order to analyse the response at the first two and three resonances, respectively -- These models describe the first resonances in a bandola as a combination of the lowest modes of vibration of enclosed air, top and back plates -- Physically, the coupling between these elements is caused by the fluid-structure interaction that gives rise to coupled modes of vibration for the assembled resonance box -- In this sense, the coupling in the models is expressed in terms of the ratio of effective areas and masses of the elements which is an useful parameter to control the coupling -- Numerical models are developed for the analysis of modal coupling which is performed using the Finite Element Method -- First, it is analysed the modal behavior of separate elements: enclosed air, top plate and back plate -- This step is important to identify participating modes in the coupling -- Then, a numerical model of the resonance box is used to compute the coupled modes -- The computation of normal modes of vibration was executed in the frequency range of 0-800Hz -- Although the introduced models of coupled oscillators only predict maximum the first three resonances, they also allow to study qualitatively the coupling between the rest of the computed modes in the range -- Considering that dynamic response of a structure can be described in terms of the modal parameters, this work represents, in a good approach, the basic behavior of a CBandola, although experimental measurements are suggested as further work to verify the obtained results and get more information about some characteristics of the coupled modes, for instance, the phase of vibration of the air mode and the radiation e ciency

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As a result of globalization, two thirds of the world’s business takes place nowadays in the service sector. In line, professional service firms are growing their share of the global service production. However, saturation of the professional service sector has forced professional service firms to search for more heuristic ways to conduct business in the international markets. By leveraging effectively the firm’s professionals, a professional service firm can lower its costs to clients and simultaneously generate additional value for the company and thus gain competitive advantage. Even though the academic field has shown growing interest towards services for decades, the fields of service productization and service internationalization are heavily understudied even today. Hence, the objective of this study was to contribute to the research on professional service internationalization and productization. The study concentrated on examining the impact that productization has on knowledge sharing and leveraging in professional service firms operating internationally. The research question focused on examining what implications productization has on knowledge transfer and leveraging during professional service internationalization by leaning on the existing research and on an empirical research. The empirical research was conducted as a single case study within a professional service firm operating in debt-related administrative service business. The case company is one of the leading operators in its field of business and therefore offered a fruitful environment to observe and analyze the topics in question. Additionally, the case company has a strong international presence and a large scale of operations in the selected markets, Finland, Norway and Sweden. Based on the previous literature and on the empirical research, this study found that for professional service firms to efficiently utilize individual, tacit knowledge, in its internationalization processes, it must be shared with the whole organization. By exploiting productization as a knowledge leveraging mechanism, a PSF can apply and transfer knowledge profoundly during its internationalization processes that would otherwise be difficult to tap into. Productization might not be sufficient alone, but by complementing it with a favorable organizational structure and culture, and by encouraging open communication, a PSF may take advantage of the whole potential that productization has to offer.

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A series of 3 experiments were conducted to evaluate the use of microalgae as supplements for ruminants consuming low-CP tropical grasses. In Exp. 1, the chemical composition and in vitro protein degradability of 9 algae species and 4 protein supplements were determined. In Exp. 2, rumen function and microbial protein (MCP) production were determined in Bos indicus steers fed speargrass hay alone or supplemented with Spirulina platensis, Chlorella pyrenoidosa, Dunaliella salina, or cottonseed meal (CSM). In Exp. 3, DMI and ADG were determined in B. indicus steers fed speargrass hay alone or supplemented with increasing amounts of NPN (urea combined with ammonia sulfate), CSM, or S. platensis. In Exp. 1, the CP content of S. platensis and C. pyrenoidosa (675 and 580 g/kg DM) was highest among the algae species and higher than the other protein supplements evaluated, and Schizochytrium sp. had the highest crude lipid (CL) content (198 g/kg DM). In Exp. 2, S. platensis supplementation increased speargrass hay intake, the efficiency of MCP production, the fractional outflow rate of digesta from the rumen, the concentration of NH3N, and the molar proportion of branched-chain fatty acids in the rumen fluid of steers above all other treatments. Dunaliella salina acceptance by steers was low and this resulted in no significant difference to unsupplemented steers for all parameters measured for this algae supplement. In Exp. 3, ADG linearly increased with increasing supplementary N intake from both S. platensis and NPN, with no difference between the 2 supplements. In contrast, ADG quadratically increased with increasing supplementary N intake from CSM. It was concluded that S. platensis and C. pyrenoidosa may potentially be used as protein sources for cattle grazing low-CP pastures.

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Colour words abound with figurative meanings, expressing much more than visual signals. Some of these figurative properties are well known; in English, for example, black is associated with EVIL and blue with DEPRESSION. Colours themselves are also described in metaphorical terms using lexis from other domains of experience, such as when we talk of deep blue, drawing on the domain of spatial position. Both metaphor and colour are of central concern to semantic theory; moreover, colour is recognised as a highly productive metaphoric field. Despite this, comparatively few works have dealt with these topics in unison, and even those few have tended to focus on Basic Colour Terms (BCTs) rather than including non-BCTs. This thesis addresses the need for an integrated study of both BCTs and non-BCTs, and provides an overview of metaphor and metonymy within the semantic area of colour. Conducted as part of the Mapping Metaphor project, this research uses the unique data source of the Historical Thesaurus of English (HT) to identify areas of meaning that share vocabulary with colour and thus point to figurative uses. The lexicographic evidence is then compared to current language use, found in the British National Corpus (BNC) and the Corpus of Contemporary American (COCA), to test for currency and further developments or changes in meaning. First, terms for saturation, tone and brightness are discussed. This lexis often functions as hue modifiers and is found to transfer into COLOUR from areas such as LIFE, EMOTION, TRUTH and MORALITY. The evidence for cross-modal links between COLOUR with SOUND, TOUCH and DIMENSION is then presented. Each BCT is discussed in turn, along with a selection of non-BCTs, where it is revealed how frequently hue terms engage in figurative meanings. This includes the secondary BCTs, with the only exception being orange, and a number of non-BCTs. All of the evidence discussed confirms that figurative uses of colour originate through a process of metonymy, although these are often extended into metaphor.