999 resultados para Ship models


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Este relatório de estágio representa o trabalho desenvolvido na Autoritat Portuària de Barcelona (APB), mais precisamente no Centro de Documentação da Autoridade Portuária de Barcelona, num período de 150 horas, onde tive a oportunidade de passar pelos diferentes serviços de documentação e realizar as tarefas inerentes a uma Instituição com idêntica tipologia àquela onde presto idêntica atividade em Portugal. Descreve-se a empresa e o trabalho desenvolvido no Centro de Documentação (CENDOC), considerando todas as funções desenvolvidas ao nível da gestão documental, na biblioteca, no arquivo intermédio, histórico e no arquivo fotográfico. O serviço de Arquivo agiliza a gestão de um fundo documental com mais de 3.900 metros lineares de documentos textuais, 500 metros lineares de documentação gráfica e cartográfica e 75.000 fotografias. Também gere o Património Cultural Móvel da APB, tanto o fundo documental do Arquivo Histórico (textual e imagens), como as coleções de objetos artísticos de interesse histórico e cultural (pinturas, esculturas, artes decorativas, cartas náuticas, modelos de navios). Toda a documentação do Arquivo Intermédio foi devidamente tratada, higienizada e organizada num novo espaço de arquivo, com melhores condições de acondicionamento. Aproveitando este trabalho, foi desenvolvido um novo Plano de Classificação em maio de 2012, no mesmo período que desenvolvi o estágio, a fim de melhorar o serviço de Arquivo. O serviço da Biblioteca tem ao alcance dos seus utilizadores um fundo de 1276 publicações periódicas e mais de 2.300 monografias, catalogadas no programa informático CDS/ISIS. A sua classificação é feita com base na Classificação Decimal Universal (CDU), e a partir de um tesauro especifico elaborado pelos técnicos do CENDOC. Enquanto Técnica Superior no Centro de Documentação e Informação na Administração do Porto de Lisboa (APL), o desenvolvimento deste estágio trouxe um importante contributo para o serviço que desempenho no Centro de Documentação e Informação na Administração do Porto de Lisboa. Este Estágio possibilitou, sem dúvida, um melhor conhecimento teórico e prático no âmbito das tarefas inerentes ao mesmo, e a capacitação para o desenvolvimento de projetos relacionados com as funções que desempenho, no Centro de Documentação e Informação da Administração do Porto de Lisboa.

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This paper presents the application of a statistical method for model structure selection of lift-drag and viscous damping components in ship manoeuvring models. The damping model is posed as a family of linear stochastic models, which is postulated based on previous work in the literature. Then a nested test of hypothesis problem is considered. The testing reduces to a recursive comparison of two competing models, for which optimal tests in the Neyman sense exist. The method yields a preferred model structure and its initial parameter estimates. Alternatively, the method can give a reduced set of likely models. Using simulated data we study how the selection method performs when there is both uncorrelated and correlated noise in the measurements. The first case is related to instrumentation noise, whereas the second case is related to spurious wave-induced motion often present during sea trials. We then consider the model structure selection of a modern high-speed trimaran ferry from full scale trial data.

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We introduce two probabilistic, data-driven models that predict a ship's speed and the situations where a ship is probable to get stuck in ice based on the joint effect of ice features such as the thickness and concentration of level ice, ice ridges, rafted ice, moreover ice compression is considered. To develop the models to datasets were utilized. First, the data from the Automatic Identification System about the performance of a selected ship was used. Second, a numerical ice model HELMI, developed in the Finnish Meteorological Institute, provided information about the ice field. The relations between the ice conditions and ship movements were established using Bayesian learning algorithms. The case study presented in this paper considers a single and unassisted trip of an ice-strengthened bulk carrier between two Finnish ports in the presence of challenging ice conditions, which varied in time and space. The obtained results show good prediction power of the models. This means, on average 80% for predicting the ship's speed within specified bins, and above 90% for predicting cases where a ship may get stuck in ice. We expect this new approach to facilitate the safe and effective route selection problem for ice-covered waters where the ship performance is reflected in the objective function.

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The technical feasibility of roll motion control devices has been amply demonstrated for over 100 years. Performance, however, can still fall short of expectations because of difficulties associated with control system designs, which have proven to be far from trivial due to fundamental performance limitations and large variations of the spectral characteristics of wave-induced roll motion. This tutorial paper presents an account of the development of various ship roll motion control systems together with the challenges associated with their design. It discusses the assessment of performance and the applicability of different mathematical models, and it surveys the control methods that have been implemented and validated with full scale experiments. The paper also presents an outlook on what are believed to be potential areas of research within this topic.

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The motion of marine vessels has traditionally been studied using two different approaches: manoeuvring and seakeeping. These two approaches use different reference frames and coordinate systems to describe the motion. This paper derives the kinematic models that characterize the transformation of motion variables (position, velocity, accelerations) and forces between the different coordinate systems used in these theories. The derivations hereby presented are done in terms of the formalism adopted in robotics. The advantage of this formulation is the use of matrix notation and operations. As an application, the transformation of linear equations of motion used in seakeeping into body-fixed coordinates is considered for both zero and forward speed.

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The technical feasibility of roll motion control devices has been amply demonstrated for over 100 years. Performance, however, can still fall short of expectations because of deficiencies in control system designs, which have proven to be far from trivial due to fundamental performance limitations. This tutorial paper presents an account of the development of various ship roll motion control systems and the challenges associated with their design. The paper discusses how to assess performance, the applicability of different models, and control methods that have been applied in the past.