967 resultados para Bifurcation diagram


Relevância:

10.00% 10.00%

Publicador:

Resumo:

We present a time-variability study of young stellar objects (YSOs) in the cluster IRAS 20050+2720, performed at 3.6 and 4.5 μm with the Spitzer Space Telescope; this study is part of the Young Stellar Object VARiability (YSOVAR) project. We have collected light curves for 181 cluster members over 60 days. We find a high variability fraction among embedded cluster members of ca. 70%, whereas young stars without a detectable disk display variability less often (in ca. 50% of the cases) and with lower amplitudes. We detect periodic variability for 33 sources with periods primarily in the range of 2–6 days. Practically all embedded periodic sources display additional variability on top of their periodicity. Furthermore, we analyze the slopes of the tracks that our sources span in the color–magnitude diagram (CMD). We find that sources with long variability time scales tend to display CMD slopes that are at least partially influenced by accretion processes, while sources with short variability timescales tend to display extinction-dominated slopes. We find a tentative trend of X-ray detected cluster members to vary on longer timescales than the X-ray undetected members.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Tal como o título indica, esta tese estuda problemas de cobertura com alcance limitado. Dado um conjunto de antenas (ou qualquer outro dispositivo sem fios capaz de receber ou transmitir sinais), o objectivo deste trabalho é calcular o alcance mínimo das antenas de modo a que estas cubram completamente um caminho entre dois pontos numa região. Um caminho que apresente estas características é um itinerário seguro. A definição de cobertura é variável e depende da aplicação a que se destina. No caso de situações críticas como o controlo de fogos ou cenários militares, a definição de cobertura recorre à utilização de mais do que uma antena para aumentar a eficácia deste tipo de vigilância. No entanto, o alcance das antenas deverá ser minimizado de modo a manter a vigilância activa o maior tempo possível. Consequentemente, esta tese está centrada na resolução deste problema de optimização e na obtenção de uma solução particular para cada caso. Embora este problema de optimização tenha sido investigado como um problema de cobertura, é possível estabelecer um paralelismo entre problemas de cobertura e problemas de iluminação e vigilância, que são habitualmente designados como problemas da Galeria de Arte. Para converter um problema de cobertura num de iluminação basta considerar um conjunto de luzes em vez de um conjunto de antenas e submetê-lo a restrições idênticas. O principal tema do conjunto de problemas da Galeria de Arte abordado nesta tese é a 1-boa iluminação. Diz-se que um objecto está 1-bem iluminado por um conjunto de luzes se o invólucro convexo destas contém o objecto, tornando assim este conceito num tipo de iluminação de qualidade. O objectivo desta parte do trabalho é então minimizar o alcance das luzes de modo a manter uma iluminação de qualidade. São também apresentadas duas variantes da 1-boa iluminação: a iluminação ortogonal e a boa !-iluminação. Esta última tem aplicações em problemas de profundidade e visualização de dados, temas que são frequentemente abordados em estatística. A resolução destes problemas usando o diagrama de Voronoi Envolvente (uma variante do diagrama de Voronoi adaptada a problemas de boa iluminação) é também proposta nesta tese.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

No trabalho apresentado realiza-se uma primeira descrição de voz e emoção para o Português Europeu. Estudamos, utilizando como base estudos realizados em diversas línguas (finlandês; inglês; alemão), os parâmetros relacionados com voz e que variam consoante a emoção que expressamos. Analisamos assim os parâmetros relacionados com a frequência Fundamental (F0) com a perturbação (jitter) com a amplitude (shimmer) e com aspectos relacionados com o ruído (HNR). Trata-se de um estudo abrangente que estudando voz e a sua relação/variação de acordo com a emoção o faz em três vertentes: patologia de voz de origem psicogénica (carácter emocional); emoção produzida por actores e a análise de emoção espontânea. Conseguindo, como trabalho pioneiro nesta área, valores para todos estes tipos de produção. Salientamos o facto de no nosso trabalho apenas existir a análise de voz sem recurso a expressão facial ou à postura dos indivíduos. Para que pudéssemos realizar estudos comparativos com os dados que íamos recolhendo em cada corpus (patologia; emoção por actor e emoção espontânea), procurámos utilizar sempre os mesmos métodos de análise (Praat; SFS; SPSS, Hoarseness Diagram – para a análise de voz com patologia - e o sistema Feeltrace - para as emoções espontâneas). Os estudos e análises relativos à emoção produzida por actores são complementados por testes de percepção aplicados a falantes nativos de Inglês Americano e a falantes de Português Europeu. Este teste, juntamente com a análise da emoção espontânea, permitiu-nos retirar dados particulares relativos à língua portuguesa. Apesar de haver tanto na expressão como na percepção de emoções muitas características consideradas universais, em Português percebe-se algo de peculiar. Os valores para a expressão neutra; tristeza e alegria são todos muito próximos, ao contrário do que acontece noutras línguas. Além disso estas três emoções (de famílias distintas) são as que mais dificuldades causam (aos dois grupos de informantes) em termos de distinção no teste de percepção. Poderá ser esta a particularidade da expressão da emoção no Português Europeu, podendo estar ligada a factores culturais. Percebe-se ainda, com este trabalho, que a emoção expressa pelo actor se aproxima da emoção espontânea. No entanto, alguns parâmetros apresentam valores diferentes, isto porque o actor tem a tendência de exagerar a emoção. Com este trabalho foram criados corpora originais que serão um recurso importante a disponibilizar para futuras análises numa área que é ainda deficitária, em termos de investigação científica, em Portugal. Tanto os corpora, como respectivos resultados obtidos poderão vir a ser úteis em áreas como as Ciências da Fala; Robótica e Docência.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

An evaluation of the global atmospheric energetics is presented in the framework of the basic decomposition into the zonal mean and eddy components, the zonal wavenumber decomposition, and the three-dimensional normal mode decomposition. An extension to the normal mode energetics formulation is also presented in the study, which enables the explicit evaluation of the conversion rate between available potential energy and kinetic energy along with their generation and dissipation rates, in both the zonal wavenumber and vertical mode domains. In addition, it has been proposed an extended energy cycle diagram describing the flow of energy among the zonal mean and eddy components, and also among the barotropic and baroclinic components. The energetics is first assessed for three reanalysis datasets and five state-ofthe- art climate models simulations representing the present climate conditions. It is performed a comparative analysis between the observationally based energetics and that based on the climate models' simulations. In order to appraise possible changes in the atmospheric energetics of a future climate scenario relative to that of the present climate conditions, the analysis is extended using the datasets simulated by the same five climate models for a future climate scenario experiment, as defined in the Special Report on Emissions Scenarios (SRES) of the Intergovernmental Panel on Climate Change (IPCC).

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Dissertação de Mestrado, Engenharia Eléctrica e Electrónica, Ramo de Tecnologias de Informação e Telecomunicações, Instituto Superior de Engenharia, Universidade do Algarve, 2009

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A gas turbine is made up of three basic components: a compressor, a combustion chamber and a turbine. Air is drawn into the engine by the compressor, which compresses it and delivers it to the combustion chamber. There, the air is mixed with the fuel and the mixture ignited, producing a rise of temperature and therefore an expansion of the gases. These are expelled through the engine nozzle, but first pass through the turbine, designed to extract energy to keep the compressor rotating [1]. The work described here uses data recorded from a Rolls Royce Spey MK 202 turbine, whose simplified diagram can be seen in Fig. 1. Both the compressor and the turbine are split into low pressure (LP) and high pressure (HP) stages. The HP turbine drives the HP compressor and the LP turbine drives the LP compressor. They are connected by concentric shafts that rotate at different speeds, denoted as NH and NL.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This is a diagram broken down by circuits of the percentage of family courts meeting the benchmark of 80% of disposing of cases within a year.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Relatório da Prática de Ensino Supervisionada, Mestrado em Ensino de Informática, Universidade de Lisboa, 2015

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Summary form only given, as follows. In Vol. 12, no. 3 (Summer 2007), page 9, bottom of the left column, in 'Computer Architecture and Amdahl??s Law' by Gene Amdahl, the claim about invalidating Amdahl??s Law in 1988 came from a team at Sandia National Laboratories, and not Los Alamos. The correct text should read: "Several years later I was informed of a proof that Amdahl's Law was invalidated by someone at Sandia National Laboratories, where a number of computers interconnected as an Ncube by communication lines, but with each computer also connected to I/O devices for loading the operating system, initial data, and results." On page 20 of the same issue, in the second sentence of the diagram explanation note by Justin Rattner, the percentage figures for the sequential and the system coordination parts of the workload were interchanged. The correct version of this sentence should read: "assuming a fixed sized problem, Amdahl speculated that most programs would require at least 10% of the computation to be sequential (only one instruction executing at a time), with overhead due to interprocessor coordination averaging 25%."

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In proposing theories of how we should design and specify networks of processes it is necessary to show that the semantics of any language we use to write down the intended behaviours of a system has several qualities. First in that the meaning of what is written on the page reflects the intention of the designer; second that there are no unexpected behaviours that might arise in a specified system that are hidden from the unsuspecting specifier; and third that the intention for the design of the behaviour of a network of processes can be communicated clearly and intuitively to others. In order to achieve this we have developed a variant of CSP, called CSPt, designed to solve the problems of termination of parallel processes present in the original formulation of CSP. In CSPt we introduced three parallel operators, each with a different kind of termination semantics, which we call synchronous, asynchronous and race. These operators provide specifiers with an expressive and flexible tool kit to define the intended behaviour of a system in such a way that unexpected or unwanted behaviours are guaranteed not to take place. In this paper we extend out analysis of CSPt and introduce the notion of an alphabet diagram that illustrates the different categories of events that can arise in the parallel composition of processes. These alphabet diagrams are then used to analyse networks of three processes in parallel with the aim of identifying sufficient constraints to ensure associativity of their parallel composition. Having achieved this we then proceed to prove associativity laws for the three parallel operators of CSPt. Next, we illustrate how to design and construct a network of three processes that satisfy the associativity law, using the associativity theorem and alphabet diagrams. Finally, we outline how this could be achieved for more general networks of processes.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In proposing theories of how we should design and specify networks of processes it is necessary to show that the semantics of any language we use to write down the intended behaviours of a system has several qualities. First in that the meaning of what is written on the page reflects the intention of the designer; second that there are no unexpected behaviours that might arise in a specified system that are hidden from the unsuspecting specifier; and third that the intention for the design of the behaviour of a network of processes can be communicated clearly and intuitively to others. In order to achieve this we have developed a variant of CSP, called CSPt, designed to solve the problems of termination of parallel processes present in the original formulation of CSP. In CSPt we introduced three parallel operators, each with a different kind of termination semantics, which we call synchronous, asynchronous and race. These operators provide specifiers with an expressive and flexible tool kit to define the intended behaviour of a system in such a way that unexpected or unwanted behaviours are guaranteed not to take place. In this paper we extend out analysis of CSPt and introduce the notion of an alphabet diagram that illustrates the different categories of events that can arise in the parallel composition of processes. These alphabet diagrams are then used to analyse networks of three processes in parallel with the aim of identifying sufficient constraints to ensure associativity of their parallel composition. Having achieved this we then proceed to prove associativity laws for the three parallel operators of CSPt. Next, we illustrate how to design and construct a network of three processes that satisfy the associativity law, using the associativity theorem and alphabet diagrams. Finally, we outline how this could be achieved for more general networks of processes.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Since creation of the European Communities the number of Member States has gradually increased from the original six to current twenty-eight. Enlargement has become an EU’s flagship external policy, demonstrating the EU’s ability to shape its neighbourhood and to serve as a catalyst of deep and multilayered reforms. The consecutive seven enlargement rounds went in parallel with widespread internal developments, culminating with the creation of the European Union and, most recently, entry into force of the Treaty of Lisbon. As this volume demonstrates, EU criminal law has evolved considerably from its early days under the legal framework laid down by the Treaty of Maastricht to its current post-Lisbon shape. On 1 December 2014, that is with expiry of a five year transitional regime for the jurisdiction of the Court of Justice, Police and Judicial Co-operation in Criminal Matters became a fully fledged EU policy, governed largely by the same modus operandi as other areas of EU competence and with compulsory jurisdiction of the Court of Justice. As EU criminal law developed internally, so did its external dimension, including the role it plays in the enlargement policy. In case of the latter the expiry of the same transitional period has brought to an end a rather anomalous situation whereby the European Union had more enforcement tools before and after accession vis-à-vis its future/new Member States than it could employ against the old ones. This bifurcation, quite rightly, triggered a lot of discussions about double standards used by the European Union in its pre-accession policy. This is exacerbated by the fact that some of those standards are neither defined in EU law, nor pursued vis-à-vis the existing EU’s Member States. The aim of this chapter is to demonstrate that evolution with particular emphasis on the role of EU Criminal Law in the policy currently employed by the European Union vis-à-vis candidate and potential candidate countries of the Western Balkans and to Turkey. Arguably, together with political conditionality, it has become one of the pillars of the enlargement process and, as the examples of accession negotiations with Montenegro and Serbia prove, its role is likely to increase as rapprochement of other candidates and potential candidates progresses to the next stages.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Existing Workflow Management Systems (WFMSs) follow a pragmatic approach. They often use a proprietary modelling language with an intuitive graphical layout. However the underlying semantics lack a formal foundation. As a consequence, analysis issues, such as proving correctness i.e. soundness and completeness, and reliable execution are not supported at design level. This project will be using an applied ontology approach by formally defining key terms such as process, sub-process, action/task based on formal temporal theory. Current business process modelling (BPM) standards such as Business Process Modelling Notation (BPMN) and Unified Modelling Language (UML) Activity Diagram (AD) model their constructs with no logical basis. This investigation will contribute to the research and industry by providing a framework that will provide grounding for BPM to reason and represent a correct business process (BP). This is missing in the current BPM domain, and may result in reduction of the design costs and avert the burden of redundant terms used by the current standards. A graphical tool will be introduced which will implement the formal ontology defined in the framework. This new tool can be used both as a modelling tool and at the same time will serve the purpose of validating the model. This research will also fill the existing gap by providing a unified graphical representation to represent a BP in a logically consistent manner for the mainstream modelling standards in the fields of business and IT. A case study will be conducted to analyse a catalogue of existing ‘patient pathways’ i.e. processes, of King’s College Hospital NHS Trust including current performance statistics. Following the application of the framework, a mapping will be conducted, and new performance statistics will be collected. A cost/benefits analysis report will be produced comparing the results of the two approaches.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Existing Workflow Management Systems (WFMSs) follow a pragmatic approach. They often use a proprietary modelling language with an intuitive graphical layout. However the underlying semantics lack a formal foundation. As a consequence, analysis issues, such as proving correctness i.e. soundness and completeness, and reliable execution are not supported at design level. This project will be using an applied ontology approach by formally defining key terms such as process, sub-process, action/task based on formal temporal theory. Current business process modelling (BPM) standards such as Business Process Modelling Notation (BPMN) and Unified Modelling Language (UML) Activity Diagram (AD) model their constructs with no logical basis. This investigation will contribute to the research and industry by providing a framework that will provide grounding for BPM to reason and represent a correct business process (BP). This is missing in the current BPM domain, and may result in reduction of the design costs and avert the burden of redundant terms used by the current standards. A graphical tool will be introduced which will implement the formal ontology defined in the framework. This new tool can be used both as a modelling tool and at the same time will serve the purpose of validating the model. This research will also fill the existing gap by providing a unified graphical representation to represent a BP in a logically consistent manner for the mainstream modelling standards in the fields of business and IT. A case study will be conducted to analyse a catalogue of existing ‘patient pathways’ i.e. processes, of King’s College Hospital NHS Trust including current performance statistics. Following the application of the framework, a mapping will be conducted, and new performance statistics will be collected. A cost/benefits analysis report will be produced comparing the results of the two approaches.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This paper studies the DNA code of eleven mammals from the perspective of fractional dynamics. The application of Fourier transform and power law trendlines leads to a categorical representation of species and chromosomes. The DNA information reveals long range memory characteristics.