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yes / This paper presents a structured approach for systems requirements analysis that integrates use case modelling with a coherent flows based approach for describing interface exchanges based on the Interface Analysis Template. The approach is discussed in the context of current frameworks for requirements elicitation from the engineering design and systems engineering domains, and it is illustrated with an automotive case study. This illustrates the strength of the framework to support structured multi-domain and multi-disciplinary analysis of requirements for complex systems.

Variações temporais na tensão de cisalhamento do vento, na Plataforma Continental Sudeste do Brasil (PCSE), perturbam o equilíbrio geostrófico gerando movimentos com frequências próximas à inercial local. Estas perturbações se propagam horizontalmente e verticalmente, interagindo com o fluxo médio e alterando as características hidrográficas e hidrodinâmicas. Foram analisados dados observacionais de corrente, registrados por correntógrafos fundeados às isóbatas de 50 m e 100 m, ao largo de Arraial do Cabo (RJ) e Ubatuba (SP), de vento registrados por bóias meteorológicas e de salinidade e temperatura perfilados em função da profundidade em estações hidrográficas, obtidos no âmbito do Projeto DEPROAS (Dinâmica do Ecossistema de Plataforma da Região Oeste do Atlântico Sul), entre 2001 e 2002. Os resultados das análises indicaram que a média de duração dos eventos de oscilações inerciais é 7,5 dias com desvio padrão de 3,8 dias, sendo 6,8 o número médio de oscilações em cada evento (desvio padrão de 3,3 oscilações). O período inercial efetivo médio foi calculado em 26,5 h com deslocamento médio da frequência inercial em 12,2%, devido ao desvio Doppler causado pelas interações com a vorticidade relativa do fluxo básico. As correntes inerciais horizontais, filtradas a partir das séries correntográficas, apresentaram valores entre 3 e 10 cm/s. Foi observada propagação vertical das oscilações inerciais e calculado o valor da velocidade de grupo vertical em -2,59 .10-2 cm.s-1. A partir desse resultado, foi obtido o valor de 28,3 m de profundidade para o valor máximo de velocidade vertical das partículas de água na onda interna inercial forçada pela oscilação das isotermas, em acordo com resultados observados de máxima corrente inercial logo abaixo da camada de mistura. O valor calculado para a amplitude da oscilação vertical das isotermas foi 17,2 m, próximo aos 19 m registrado com os resultados observacionais em períodos de mudança do campo de ventos. O modelo numérico hidrodinâmico ROMS (Regional Ocean Modelling System) comprovou resultados observacionais em relação à capacidade de mudanças na tensão de cisalhamento do vento, em períodos menores que o inercial local, gerarem oscilações inerciais. Os resultados numéricos com o ROMS permitiram analisar a interação das oscilações inerciais com o fluxo médio em diferentes regiões da PCSE, através de diferentes condições de estratificação da coluna de água e, a partir da trajetória de pseudoderivadores, estimar os raios das trajetórias com ordem 10 km. / Temporal variations in the wind stress, on the South Brazil Bight, disturb the geostrophic equilibrium and generate motion with near inertial frequencies. The disturbances propagate horizontally and vertically, interacting with the basic motions and altering the hydrodynamics and hydrographic characteristics. Observational data of currents, collected by currentmeters deployed in the 50 m and 100 m isobaths, offshore Arraial do Cabo (RJ) and Ubatuba (SP), of winds collected in meteorological buoys and of salinity and temperature vertically profiled in hydrographic stations, during the project DEPROAS (Dinâmica do Ecossistema de Plataforma da Região Oeste do Atlântico Sul), in the years of 2001 and 2002, have been analyzed. Results showed that the mean duration of the inertial oscillations events is 7.5 days, with standard deviation of 3.8 days, being 6.8 the mean number of oscillations in each event (standard deviation of 3.3 oscillations). The calculated mean effective inertial period is 26.5 h, with a mean difference of the local inertial frequency of 12.2% due to the Doppler shift caused by interactions with the relative vorticity of the basic flow. The horizontal inertial currents, filtered from the current time series, presented values between 3 and 10 cm/s. Vertical propagation of the inertial oscillations were observed and the calculated value for the vertical group velocity was -2.59 . 10-2 cm/s. From these results, the calculated value for the depth of maximum water vertical velocity was 28.3 m for the internal inertial wave forced by the isotherms oscillations, in accordance with results observed of maximum vertical velocities occurring below the mixing layer. The calculated value for the amplitude of vertical oscillations of isotherms was 17.2 m, approximately equal to the 19 m observed in the data set during periods of wind shift. The numerical hydrodynamical model ROMS (Regional Ocean Modeling System) confirmed the observational results that changes in the wind field with periods smaller than the local inertial period generate inertial oscillations. The numerical results with ROMS allowed to analyze the interaction between the inertial oscillations and the basic flow in different regions of the South Brazil Bight, due to vertical different stratification characteristics of the sea water, and from the trajectories of pseudo-drifters it was possible to estimate the radius of the trajectories as having order of magnitude of 10 km.

Variações temporais na tensão de cisalhamento do vento, na Plataforma Continental Sudeste do Brasil (PCSE), perturbam o equilíbrio geostrófico gerando movimentos com frequências próximas à inercial local. Estas perturbações se propagam horizontalmente e verticalmente, interagindo com o fluxo médio e alterando as características hidrográficas e hidrodinâmicas. Foram analisados dados observacionais de corrente, registrados por correntógrafos fundeados às isóbatas de 50 m e 100 m, ao largo de Arraial do Cabo (RJ) e Ubatuba (SP), de vento registrados por bóias meteorológicas e de salinidade e temperatura perfilados em função da profundidade em estações hidrográficas, obtidos no âmbito do Projeto DEPROAS (Dinâmica do Ecossistema de Plataforma da Região Oeste do Atlântico Sul), entre 2001 e 2002. Os resultados das análises indicaram que a média de duração dos eventos de oscilações inerciais é 7,5 dias com desvio padrão de 3,8 dias, sendo 6,8 o número médio de oscilações em cada evento (desvio padrão de 3,3 oscilações). O período inercial efetivo médio foi calculado em 26,5 h com deslocamento médio da frequência inercial em 12,2%, devido ao desvio Doppler causado pelas interações com a vorticidade relativa do fluxo básico. As correntes inerciais horizontais, filtradas a partir das séries correntográficas, apresentaram valores entre 3 e 10 cm/s. Foi observada propagação vertical das oscilações inerciais e calculado o valor da velocidade de grupo vertical em -2,59 .10-2 cm.s-1. A partir desse resultado, foi obtido o valor de 28,3 m de profundidade para o valor máximo de velocidade vertical das partículas de água na onda interna inercial forçada pela oscilação das isotermas, em acordo com resultados observados de máxima corrente inercial logo abaixo da camada de mistura. O valor calculado para a amplitude da oscilação vertical das isotermas foi 17,2 m, próximo aos 19 m registrado com os resultados observacionais em períodos de mudança do campo de ventos. O modelo numérico hidrodinâmico ROMS (Regional Ocean Modelling System) comprovou resultados observacionais em relação à capacidade de mudanças na tensão de cisalhamento do vento, em períodos menores que o inercial local, gerarem oscilações inerciais. Os resultados numéricos com o ROMS permitiram analisar a interação das oscilações inerciais com o fluxo médio em diferentes regiões da PCSE, através de diferentes condições de estratificação da coluna de água e, a partir da trajetória de pseudoderivadores, estimar os raios das trajetórias com ordem 10 km. / Temporal variations in the wind stress, on the South Brazil Bight, disturb the geostrophic equilibrium and generate motion with near inertial frequencies. The disturbances propagate horizontally and vertically, interacting with the basic motions and altering the hydrodynamics and hydrographic characteristics. Observational data of currents, collected by currentmeters deployed in the 50 m and 100 m isobaths, offshore Arraial do Cabo (RJ) and Ubatuba (SP), of winds collected in meteorological buoys and of salinity and temperature vertically profiled in hydrographic stations, during the project DEPROAS (Dinâmica do Ecossistema de Plataforma da Região Oeste do Atlântico Sul), in the years of 2001 and 2002, have been analyzed. Results showed that the mean duration of the inertial oscillations events is 7.5 days, with standard deviation of 3.8 days, being 6.8 the mean number of oscillations in each event (standard deviation of 3.3 oscillations). The calculated mean effective inertial period is 26.5 h, with a mean difference of the local inertial frequency of 12.2% due to the Doppler shift caused by interactions with the relative vorticity of the basic flow. The horizontal inertial currents, filtered from the current time series, presented values between 3 and 10 cm/s. Vertical propagation of the inertial oscillations were observed and the calculated value for the vertical group velocity was -2.59 . 10-2 cm/s. From these results, the calculated value for the depth of maximum water vertical velocity was 28.3 m for the internal inertial wave forced by the isotherms oscillations, in accordance with results observed of maximum vertical velocities occurring below the mixing layer. The calculated value for the amplitude of vertical oscillations of isotherms was 17.2 m, approximately equal to the 19 m observed in the data set during periods of wind shift. The numerical hydrodynamical model ROMS (Regional Ocean Modeling System) confirmed the observational results that changes in the wind field with periods smaller than the local inertial period generate inertial oscillations. The numerical results with ROMS allowed to analyze the interaction between the inertial oscillations and the basic flow in different regions of the South Brazil Bight, due to vertical different stratification characteristics of the sea water, and from the trajectories of pseudo-drifters it was possible to estimate the radius of the trajectories as having order of magnitude of 10 km.

Channel constrictions in which strong currents are mainly driven by tidal processes represent sites with high potential for harvesting renewable and predictable tidal stream energy. Tidal Current Turbines (TCTs) deployed in arrays appear to be the most promising solution to efficiently capturing this carbon neutral energy resource. However to ensure the sustainable character of such projects, the balance between power extraction maximization and environmental impact minimization must be found so that device layout optimization takes into account environmental considerations. This is particularly appropriate since both resource and impact assessments go intrinsically hand in hand. The present method proposes the use and adaptation of ocean circulation models as an assessment tool framework for tidal current turbine (TCT) array-layout optimization. By adapting both momentum and turbulence transport equations of an existing model, the present TCT representation method is proposed to extend the actuator disc concept to 3-D large scale ocean circulation models. Through the reproduction of physical experiments to reasonable accuracy, grid and time dependency tests and an up-scaling exercise, this method has shown its numerical validity as well as its ability to simulate accurately both momentum and turbulent turbine-induced perturbations in the wake. These capabilities are demonstrated for standalone devices and device arrays, and are achieved with a relatively short period of computation time. Consequently the present TCT representation method is a very promising basis for the development of a TCT array layout optimization tool. By applying this TCT representation method to realistic cases, its capability is demonstrated for power capture assessment and prediction of hydrodynamic interactions as would be required during the layout deployment optimization process. Tidal energy has seen considerable development over the last decade and the first commercial deployments are likely to take place within the next 5 years. It is hoped that this new tool and the numerical approaches described herein will contribute to the development of TCT array power plants around the world.

The plasma vertical position system on the COMPASS–D tokamak is studied in this thesis. An analogue P+D controller is used to regulate the plasma vertical position which is open loop unstable. Measurements from inside the vessel are used for the derivative component of the control signal and external measurements for the proportional component. Two main sources of disturbances are observed on COMPASS–D. One source is 600Hz noise from thyristor power supplies which cause large oscillations at the control amplifier output. Another source is impulse–like disturbances due to ELMs (Edge Localized Modes) and this can occasionally lead to loss of control when the control amplifier saturates. Models of the plasma open loop dynamics were obtained using the process of system identification. Experimental data is used to fit the coefficients of a mathematical model. The frequency response of the model is strongly dependent on the shape of the plasma. The effect of shielding by the vessel wall on external measurements when compared with internal measurements is also observed. The models were used to predict values of gain margins and phase crossover frequencies which were found to be in good agreement with measured values. The harsh reactor conditions on the proposed ITER tokamak preclude the use of internal measurements. On COMPASS–D the stability margins of the loop decrease when using only external flux loops. High order controllers were designed to stabilize the system using only external measurements and to reduce the effect of 600Hz noise on the control amplifier voltage. The controllers were tested on COMPASS–D and demonstrated the improved performance of high order controllers over the simple P+D controller. ELMs cause impulse–like disturbances on the plasma position. The optimal controller minimizing the peak of the impulse response can be calculated analytically for COMPASS–D. A multiobjective controller which combines a small peak impulse response with robust stability and noise attenuation can be obtained using a numerical search.

The world shipping freight market for the transportation of bulk cargo - liquid and dry - is characterised by the somewhat erratic and extreme fluctuations exhibited by many of the measures that can be used to describe the "state" of the market. Such 'measures' include the spot freight rates - the cost to the shipper of chartering a unit of shipping capacity 'on the spot' (that is, not reserving the vessel in advance), - the proportion of chartered tonnage at any time taken on a period (time) basis as opposed to a voyage (single) basis, and the rate at which orders for new vessels reach the shipyards. These factors are extremely variable, and have exhibited a similar form of behaviour for a large number of years. This present thesis describes an attempt to investigate the behaviour of the freight market (bulk cargo); the aim of the investigation being to identify the structure of the market system and to construct a System Dynamics model which describes the complex relationships in the market and which can be used to explore questions relating to present or future market behaviour. The construction of such a model is described, together with an exhaustive chapter on the analysis of the model, covering loop-analysis, the behaviour of the model under various test inputs, and the senstivity of the model to significant changes in parameter values. The final chapter considers the use of the model, and, in particular, describes its use in an investigation of the feasibility or desirability of introducing tonnagestabilization schemes into the market. Such schemes aim to prevent the freight rates from falling to unacceptably low values, by implementing a scheme whereby tonnage is withdrawn from operation and laid-up: the decrease in the supply of tonnage then has a positive influence on the freight rates. It is concluded that the problems involved in designing such schemes preclude the schemes from implementation. The appendices cover the various data used in the determination of market relationships, as well as the computer listing, in Fortran, of the market model. Also included in an appendix is a description of the application of System Dynamics to a hypothetical company. The tcompany model' allows for the examination of chartering policies and lay-up policies under a variety of conditions of market demand.

In this study, a semiotic point of view of selected literature written by ‘coloured’ writers is examined, using some of the semiotic theories of Jurij M. Lotman, one of the leading Soviet semioticians of the school of Tartu. Selected theories of Lotman are applied to ‘coloured’ literature. These include an examination of poetic language (based on Lotman’s theory of a primary and secondary modelling system), the iconicity of the text, the aesthetics of identity and opposition, the distinction between text and extra-text, and the relationship that exists between the extra-text, culture and code. The literary texts chosen for analysis are works by three contemporary ‘coloured’ writers, namely Adam Small, Peter Snyders and Robert Pearce, who have all contributed poetry, prose and drama to Afrikaans literature in general, and original Afrikaans literature in particular. The selected dramas are Joanie Galant-hulle (Small 1978), Political Joke (Snyders 1983) and Die Laaste Supper in Marabastad (Pearce 1988b)*. These writers’ works span approximately three consecutive decades and their work can be examined for commonality and differences. The three chosen dramas were written five years apart respectively; yet they reveal thematic similarities. The dramas also feature a common ‘deviant’ language code used by ‘coloured’ people and discussed in this study as original Afrikaans. This code, which is juxtaposed with standard Afrikaans, is one of the basic areas of interest that motivated the choice of subject for this study. The primary objective of this study is to examine the differentiation that Lotman makes between the various sign systems that operate in natural language (the primary modelling system) and poetic language (a secondary modelling system), and to determine whether these sign systems can be detected and are functional in ‘coloured’ literature. In addition, an investigation is made of the iconicity that operates in poetic language (which, according to Lotman, is the basis for differentiation), and to ascertain whether iconicity occurs in these examples of ‘coloured’ literature and to what extent it influences meaning. In the process, intratextual relations within the poetic text were scrutinised to establish whether the manipulation of language, devices and codes raises any particular expectation in the poetic text, and also to detect whether oppositionally constituted code-systems which set up their own patterns of expectation within the syntactic and lexical levels of the poetic text clash with and contradict prior expectations. In addition, an analysis has been made to determine whether a new understanding of the texts can be reached, based on Lotman’s aesthetics of identity and opposition, and to what extent the reader is forced to collaborate in the modelling process of the texts when the reader’s expectations are undermined by an aesthetics of opposition. The study has successfully corroborated and substantiated all the selected aspects of Lotman’s theory. The differentiation that Lotman makes between the primary and secondary language model is demonstrated especially by the iconicity that operates in poetic language. Examples are abundant in the selected literature and are conspicuous, especially through the manipulation of the language, devices and codes employed by the authors to defamiliarise objects so that they transcend their familiar characteristics and perceptions, and sometimes signify a totally new concept. In this way, readers’ expectations are subverted and they are invited to collaborate in the modelling process of the texts. These techniques are also an integral part of both the text and the extra-text, and their presence justifies Lotman’s claims that the meaning of a literary text cannot be understood outside its cultural or historical context. In retrospect, it can be argued that this research has opened up some additional avenues for an analysis of meaning in ‘coloured’ literature. / Dissertation (MA (English))--University of Pretoria, 2004. / English / unrestricted

Made available in DSpace on 2014-06-12T17:40:46Z (GMT). No. of bitstreams: 2 arquivo723_1.pdf: 2509449 bytes, checksum: aee89d3fd6cd28c43ba22ccfaced1689 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2009 / Companhia Hidro Elétrica do São Francisco / Esta dissertação enfoca a questão do erro humano nas atividades relacionadas com a manutenção dos equipamentos de proteção e automação numa grande empresa de transmissão de energia elétrica. A ênfase é no erro humano que tenha provocado o desligamento acidental de alguma função de transmissão. A justificativa do estudo cita ações preventivas aos erros humanos na manutenção, apresenta dados básicos de desligamentos, resume os cenários antes e depois da resolução normativa que alterou a remuneração do setor de transmissão, ressalta os impactos econômicos com a nova regulamentação e aborda aspectos da cultura organizacional. A pesquisa sobre as causas de acidentes no trabalho resume teorias com ênfase no homem (da fadiga; da propensão para acidentes, do puro acaso) e teorias com visão sistêmica (modelos Skill-Rule-Knowledge e Generic Error-Modelling System). Aborda ainda aplicações das teorias de análise e classificação de erros humanos que resultaram no modelo Human Factors Analysis and Classification System. Conclui destacando a dificuldade e a necessidade das empresas abandonarem as análises de acidentes com foco nos erros dos homens para considerarem os fatores organizacionais, apresenta fatores psicológicos que levam a buscar culpados e propostas para alcançar excelentes níveis de segurança. O método proposto para a análise e classificação de erros humanos, composto de nove fases, estabelece análise ampla e participativa, apresenta fluxogramas e diagramas de apoio e um processo de validação das recomendações de modo a obter o comprometimento dos responsáveis pela implantação. Apresenta a visão da análise de acidentes no mundo, alerta para o perigo da tendência em supervalorizar o organizacional , insiste que as organizações não podem perder de vista os atos inseguros. Na aplicação é descrita a avaliação da influência da mudança na tecnologia dos equipamentos de proteção e automação em relação aos erros humanos sendo constatado forte efeito sobre a atividade de cálculo e emissão de ajustes dos equipamentos digitais. A conclusão ressalta as bases teóricas do método proposto, destaca os aplausos às empresas que conseguem evitar análises de acidentes com foco excessivo no humano e sugere estudos envolvendo psicologia, engenharia, psiquiatria, estatística, administração e pedagogia

Submitted by Maike Costa (maiksebas@gmail.com) on 2016-06-27T11:48:41Z No. of bitstreams: 1 arquivo total.pdf: 1475107 bytes, checksum: 81ce6a6da2e948a869020b9eb4f94b0c (MD5) / Made available in DSpace on 2016-06-27T11:48:42Z (GMT). No. of bitstreams: 1 arquivo total.pdf: 1475107 bytes, checksum: 81ce6a6da2e948a869020b9eb4f94b0c (MD5) Previous issue date: 2015-02-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This research focalizes the way the theatrical signs are structured and organized in the dramatic spectacle Vau da Sarapalha, performed by the Piollin Company during two decades. The main objective of this academic work is the understanding of how the theatrical code operates the catalyzing process of different semiotic languages that interact dialogically to generate the meaning of the dramatic perform. The methodology employed includes the examination of different signs that are responsible for the meaning of the performance, such as: the gestures produced by the actors, the scenery’s objects, the music, the lighting, the costumes and the linguistic signs, among others. Scholars who follow the approach of the Semiotic Study of Cultures, as for instance, Lotman, Machado, Schnaiderman, Bakhtin and Jakobson, will support the analysis. The contributions of Pavis, Fischer-Lichtie, Ubersfeld and Guinsburg, theorists who studied the theatre as a semiotic system, were also essential to the development of this analysis. In this way, this research intends to contribute to the understanding of Vau da Sarapalha as a semiotic text. / Esta pesquisa analisa a maneira como os signos encontram-se estruturados e organizados no espetáculo Vau da Sarapalha, montado pelo Grupo Piollin de Teatro e apresentado durante mais de duas décadas. O objetivo principal do estudo é entender o funcionamento e a interação das diferentes linguagens que formam o espetáculo, bem como a semiose produzida a partir desses encontros dialógicos. A metodologia adotada inclui o exame de vários signos que compõem o espetáculo, tais como: os gestos produzidos pelos atores, os objetos do cenário, a música, a iluminação, o figurino e os signos linguísticos, entre outros. Estudiosos da Semiótica Russa como, por exemplo, Lotman, Machado, Schnaiderman, Bakhtin e Jakobson, fornecerão o suporte teórico à análise. As considerações de Pavis, Fischer-Lichte, Ubersfeld e Guinsburg, teóricos que estudaram o teatro enquanto um sistema semiótico, também foram essenciais para o desenvolvimento dessa análise. Dessa forma, essa pesquisa pretende contribuir para o entendimento do espetáculo teatral Vau da Sarapalha enquanto texto semiótico