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Modelo para diagnose de falhas em regulador de velocidade de turbinas hidráulicas. / Model to faults diagnosis in speed-governor system of hydraulic turbine.Hidalgo, Erick Miguel Portugal 28 July 2010 (has links)
O regulador de velocidade tem a função principal de atuar no sentido de aumentar ou diminuir a potência gerada pela turbina quando a velocidade ou freqüência se afasta do valor de referência. Em função da demanda do sistema, o sistema regulador da turbina atua sobre a posição das pás do distribuidor controlando a abertura e conseqüentemente a vazão que chega ao rotor, gerando apenas a energia elétrica necessária para o consumo. O presente trabalho tem como objetivo desenvolver um método para diagnosticar falhas em reguladores de velocidade de turbinas hidráulicas. Baseando-se nas ferramentas de confiabilidade selecionou-se os componentes críticos do sistema para elaborar políticas de manutenção que visam obter maior disponibilidade do sistema. Este trabalho apresenta uma metodologia com as seqüências das atividades que permitem fazer uma análise detalhada e confiável, pois são utilizadas numa ordem lógica e organizada, de forma que o método seja desenvolvido corretamente. A metodologia proposta utiliza as ferramentas de análise de confiabilidade como: Análise de Modos e Efeitos de Falha (FMEA) e Análise de Árvore de Falhas (FTA). O FMEA parte da definição das funções dos sistemas e subsistemas analisados, verificando em seguida as falhas que afetam cada função e todos os modos de falha que levam a cada falha. O FTA é basicamente um método dedutivo que visa identificar as causas ou combinações de causas que possam levar ao evento topo definido. / The speed governing system has the primary function of acting to increase or decrease the power generated by the turbine when the speed or frequency deviation from reference value. According to the system demand, the speed governing system turbine operates on the position of the blades of the distributor controlling the opening and therefore the flow that reaches the rotor, generating only the power required for consumption. This work aims at to develop a method to diagnose faults in speed governing system of hydraulic turbines. The tools of reliability selected critical components of the system to develop policies aimed at keeping achieve greater system availability. This work presents a methodology with a sequence of activities allowing one to make a detailed and reliable analysis, because they are used in a logical order and organized so that the model is developed properly. The proposed methodology uses tools such as reliability analysis: Analysis of Failure Modes and Effects (FMEA) and Fault Tree Analysis (FTA). The FMEA part of the definition of the functions of systems and subsystems analyzed, then verifying that the flaws affect every function and all modes of failure that led to each failure. The FTA is basically a deductive method that aims at identifying the causes of combinations of causes that could lead to top event defined.
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Modelo para diagnose de falhas em regulador de velocidade de turbinas hidráulicas. / Model to faults diagnosis in speed-governor system of hydraulic turbine.Erick Miguel Portugal Hidalgo 28 July 2010 (has links)
O regulador de velocidade tem a função principal de atuar no sentido de aumentar ou diminuir a potência gerada pela turbina quando a velocidade ou freqüência se afasta do valor de referência. Em função da demanda do sistema, o sistema regulador da turbina atua sobre a posição das pás do distribuidor controlando a abertura e conseqüentemente a vazão que chega ao rotor, gerando apenas a energia elétrica necessária para o consumo. O presente trabalho tem como objetivo desenvolver um método para diagnosticar falhas em reguladores de velocidade de turbinas hidráulicas. Baseando-se nas ferramentas de confiabilidade selecionou-se os componentes críticos do sistema para elaborar políticas de manutenção que visam obter maior disponibilidade do sistema. Este trabalho apresenta uma metodologia com as seqüências das atividades que permitem fazer uma análise detalhada e confiável, pois são utilizadas numa ordem lógica e organizada, de forma que o método seja desenvolvido corretamente. A metodologia proposta utiliza as ferramentas de análise de confiabilidade como: Análise de Modos e Efeitos de Falha (FMEA) e Análise de Árvore de Falhas (FTA). O FMEA parte da definição das funções dos sistemas e subsistemas analisados, verificando em seguida as falhas que afetam cada função e todos os modos de falha que levam a cada falha. O FTA é basicamente um método dedutivo que visa identificar as causas ou combinações de causas que possam levar ao evento topo definido. / The speed governing system has the primary function of acting to increase or decrease the power generated by the turbine when the speed or frequency deviation from reference value. According to the system demand, the speed governing system turbine operates on the position of the blades of the distributor controlling the opening and therefore the flow that reaches the rotor, generating only the power required for consumption. This work aims at to develop a method to diagnose faults in speed governing system of hydraulic turbines. The tools of reliability selected critical components of the system to develop policies aimed at keeping achieve greater system availability. This work presents a methodology with a sequence of activities allowing one to make a detailed and reliable analysis, because they are used in a logical order and organized so that the model is developed properly. The proposed methodology uses tools such as reliability analysis: Analysis of Failure Modes and Effects (FMEA) and Fault Tree Analysis (FTA). The FMEA part of the definition of the functions of systems and subsystems analyzed, then verifying that the flaws affect every function and all modes of failure that led to each failure. The FTA is basically a deductive method that aims at identifying the causes of combinations of causes that could lead to top event defined.
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Advanced reliability analysis of polymer electrolyte membrane fuel cells in automotive applicationsWhiteley, Michael January 2016 (has links)
Hydrogen fuel cells have the potential to dramatically reduce emissions from the energy sector, particularly when integrated into an automotive application. However, there are three main hurdles to the commercialisation of this promising technology; one of which is reliability. Cur- rent standards require an automotive fuel cell to last around 5000 h of operation (equivalent to around 150,000 miles), which has proven difficult to achieve to date. This hurdle can be overcome through in-depth reliability analysis including techniques such as Failure Mode and Effect Analysis (FMEA), Fault Tree Analysis (FTA) and Petri-net simulation. This research has found that the reliability field regarding hydrogen fuel cells is still in its infancy, and needs development, if the current standards are to be achieved. In this research, a detailed reliability study of a Polymer Electrolyte Membrane Fuel Cell (PEMFC) is undertaken. The results of which are a qualitative and quantitative analysis of a PEMFC. The FMEA and FTA are the most up to date assessments of failure in fuel cells developed using a comprehensive literature review and expert opinion. Advanced modelling of fuel cell degradation logic was developed using Petri-net modelling techniques. 20 failure modules were identfied that represented the interactions of all failure modes and operational parameters in a PEMFC. Petri-net simulation was used to overcome key pitfalls observed in FTA to provide a verfied degradation model of a PEMFC in an automotive application, undergoing a specific drive cycle, however any drive cycle can be input to this model. Overall results show that the modeled fuel cell's lifetime would reach 34 hours before falling below the industry standard degradation rate of more than 5%. The degradation model has the capability to simulate fuel cell degradation under any drive cycle and with any operating parameters. A fuel cell test rig was also developed that was used to verify the simulated degradation. The rig is capable of testing single cells or stacks from 0-470W power. The results from the verification experimentation agreed strongly with the degradation model, giving confidence in the accuracy of the developed Petri-net degradation model. This research contributes greatly to the field of reliability of PEMFCs through the most up-to-date and comprehensive FMEA and FTA presented. Additionally, a degradation model based upon Petri-nets is the first degradation model to encompass a 1D performance model to predict fuel cell life time under specific drive cycles.
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Riskanalys av självkörande fordon i hamnområden : En kvalitativ studie för interna transporter av containrarBylin, Jenniefer January 2019 (has links)
Today, companies face constant challenges, as the business must constantly be developed in order to compete. As new ports are being built in already existing ones, other opportunities are often made available to develop further and reduce costs and risks. Replacing some labour against automation is one of them. The study aims to ensure the risks of using selfdriving vehicles for the movement of containers in port areas. The work has been carried out at SCA in Tunadal for their new coming terminal. The aim of the study was to examine the risk associated with manpower versus self-driving vehicles exist. If, based on a safety aspect, it is profitable to go towards a more automated business. To carry out the study, documents have been collected describing the accidents in the port, two persons who are extra responsible for the accidents in the port have been interviewed and observations have been made to also see how the self-driving vehicle is to be applied to reality. When processing the data, THERP - Technique for human error rate prediction has been used for mapping the current situation. FMEA - failure mode and effects analysis and FTA - Fault tree analysis has been used to map the future situation with automation. The result shows that from a safety perspective, it is safest to use self-driving vehicles, as it is the human slips that represent the greatest risks in port areas. / Idag står företag för ständiga utmaningar då verksamheten hela tiden måste utvecklas för att kunna konkurrera. Då nya hamnar byggs i redan befintlig tas ofta andra möjligheter i förfogande för att utvecklas ytterligare och minska på kostnader och risker. Att byta ut viss arbetskraft mot automation är en av dem. Studien syftar till att se till riskerna med att använda självkörande fordon för förflyttning av containrar i hamnområden. Arbetet har genomförts hos SCA i Tunadal för deras nya kommande terminal. Målet med studien var att se till de risker som finns med att använda arbetskraft kontra självkörande fordon. Om det utifrån en säkerhetsaspekt är lönsamt att gå mot en mer automatiserad verksamhet. För att utföra studien har dokument samlats in som beskriver olyckorna i hamnen, två personer som är extra ansvariga för olyckorna i hamnen har intervjuats och observationer har gjorts för att också se till hur det självkörande fordonet ska appliceras på verkligheten. Vid bearbetning av data har THERP - Technique for human error rate prediction använts för kartläggning av nuläget. FMEA - failure mode and effects analysis och FTA - Fault tree analysis har använts för att kartlägga det framtida läget med automation. Resultatet visar att det ur ett säkerhetsperspektiv är säkrast att använda sig av självkörande fordon då det är de mänskliga snedstegen som står för de största riskerna i hamnområden.
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Método de aquisição de conhecimento para sistemas especialistas destinados à diagnose de falhas: aplicação de técnicas de análise de confiabilidade e de risco. / Knowledge acquisition method for expert system to fault diagnosis: application of technical of reliability analysis and risk.Hidalgo, Erick Miguel Portugal 24 November 2014 (has links)
O processo de aquisição do conhecimento é uma das principais etapas de desenvolvimento de um sistema especialista e é considerado como um dos estágios mais difíceis. Essa dificuldade se dá em virtude da inexistência de uma metodologia eficiente, confiável e padrão para extração e organização do conhecimento das várias fontes. O método apresentado neste trabalho é uma alternativa que pode ser empregada para adquirir o conhecimento para desenvolver sistemas especialistas para diagnóstico de falhas em diferentes áreas da indústria. Este trabalho apresenta um método que integra as técnicas de confiabilidade e risco, tais como, Análise de Modos e Efeitos de Falha (FMEA), Análise de Árvore de falhas (FTA) e Estudo de Perigo e Operabilidade (HAZOP) para aquisição do conhecimento para o diagnóstico de falhas. O método também permite estimar a periocidade da manutenção preventiva aplicando os conceitos de manutenção imperfeita e teoria de decisão multicritério. O método utilizada técnicas empregadas em análise de confiabilidade e risco para determinar a relação entre efeito da falha em um sistema e as suas causas raiz com o objetivo de estabelecer um procedimento estruturado para aquisição do conhecimento associado à relação causa-efeito em um sistema. O método foi validado com a comparação do histórico de falhas de um sistema hidráulico de uma usina hidrelétrica e, considerando-se que os eventos definidos como causa raiz registrados no histórico de falhas foram encontrados como resultados da análise pelo sistema especialista, tem-se a validação. O método para determinar a periocidade da manutenção preventiva foi validado com os resultados de artigos e com os planos de manutenção da usina. / The process of knowledge acquisition is a major step in developing an expert system and is considered as one of the most difficult stages. This difficulty is due to the lack of an efficient, reliable and standard methodology for extraction and organization of knowledge from various sources. The method presented in this thesis is an alternative that can be used to acquire the knowledge to develop expert systems for fault diagnosis in different areas of industry. This thesis presents a method that integrates risk and reliability analysis techniques such as Failure Modes and Effects Analysis (FMEA), Fault Tree Analysis (FTA) and Hazard and Operability Study (HAZOP) for the acquisition of knowledge to fault diagnosis. The method also allows estimating the optimal intervention times of preventive maintenance by applying the imperfect maintenance and multicriteria concepts. The method uses techniques that are employed in reliability and risk analysis to determine the relationship between fault effect in the system and its root causes in order to establish a structured acquisition of knowledge associated with the causeeffect relationship in a system procedure. The method was validated by comparing the failure database related to a hydropower plant hydraulic system and, considering that the events defined as root causes recorded in the failure database were found by expert system, the method was validated. The method for determining the optimal intervention time for preventive maintenance has been validated with the results of articles and maintenance plans of the plant.
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Método de aquisição de conhecimento para sistemas especialistas destinados à diagnose de falhas: aplicação de técnicas de análise de confiabilidade e de risco. / Knowledge acquisition method for expert system to fault diagnosis: application of technical of reliability analysis and risk.Erick Miguel Portugal Hidalgo 24 November 2014 (has links)
O processo de aquisição do conhecimento é uma das principais etapas de desenvolvimento de um sistema especialista e é considerado como um dos estágios mais difíceis. Essa dificuldade se dá em virtude da inexistência de uma metodologia eficiente, confiável e padrão para extração e organização do conhecimento das várias fontes. O método apresentado neste trabalho é uma alternativa que pode ser empregada para adquirir o conhecimento para desenvolver sistemas especialistas para diagnóstico de falhas em diferentes áreas da indústria. Este trabalho apresenta um método que integra as técnicas de confiabilidade e risco, tais como, Análise de Modos e Efeitos de Falha (FMEA), Análise de Árvore de falhas (FTA) e Estudo de Perigo e Operabilidade (HAZOP) para aquisição do conhecimento para o diagnóstico de falhas. O método também permite estimar a periocidade da manutenção preventiva aplicando os conceitos de manutenção imperfeita e teoria de decisão multicritério. O método utilizada técnicas empregadas em análise de confiabilidade e risco para determinar a relação entre efeito da falha em um sistema e as suas causas raiz com o objetivo de estabelecer um procedimento estruturado para aquisição do conhecimento associado à relação causa-efeito em um sistema. O método foi validado com a comparação do histórico de falhas de um sistema hidráulico de uma usina hidrelétrica e, considerando-se que os eventos definidos como causa raiz registrados no histórico de falhas foram encontrados como resultados da análise pelo sistema especialista, tem-se a validação. O método para determinar a periocidade da manutenção preventiva foi validado com os resultados de artigos e com os planos de manutenção da usina. / The process of knowledge acquisition is a major step in developing an expert system and is considered as one of the most difficult stages. This difficulty is due to the lack of an efficient, reliable and standard methodology for extraction and organization of knowledge from various sources. The method presented in this thesis is an alternative that can be used to acquire the knowledge to develop expert systems for fault diagnosis in different areas of industry. This thesis presents a method that integrates risk and reliability analysis techniques such as Failure Modes and Effects Analysis (FMEA), Fault Tree Analysis (FTA) and Hazard and Operability Study (HAZOP) for the acquisition of knowledge to fault diagnosis. The method also allows estimating the optimal intervention times of preventive maintenance by applying the imperfect maintenance and multicriteria concepts. The method uses techniques that are employed in reliability and risk analysis to determine the relationship between fault effect in the system and its root causes in order to establish a structured acquisition of knowledge associated with the causeeffect relationship in a system procedure. The method was validated by comparing the failure database related to a hydropower plant hydraulic system and, considering that the events defined as root causes recorded in the failure database were found by expert system, the method was validated. The method for determining the optimal intervention time for preventive maintenance has been validated with the results of articles and maintenance plans of the plant.
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霸權的維繫與挑戰:以美國小布希政府之美新與美澳自由貿易協定為例 / The maintenance and challenge of hegemony:The U.S.-Singapore FTA and U.S.-Australia FTA of George W.Bush's administration蔡宜珊, Tsai, Yi Shan Unknown Date (has links)
本文主要以霸權穩定論作為研究基礎,解釋美國為維持在亞太地區的主導權,透過簽訂FTA作為一種手段並檢視其效益,意即美國與亞太國家簽訂雙邊FTA是否為一有效維繫其在亞太地區主導權的手段。研究重心為美國在亞太地區的FTA政策運用和FTA性質的變化,並以美新FTA與美澳FTA兩個案作為研究標的,分析美國選取簽署國的政經與策略,並評估美國在亞太地區簽訂雙邊FTA對於其霸權維繫的之成效與FTA政策運用是否成功。根據本研究發現,相較於亞太地區因區域整合而引領的FTA洽簽風潮,美國於2001年小布希上台後才對FTA重視程度大幅提升,但與亞太國家的談判速度與簽署數量上仍然進度緩慢且成效不彰,美國對亞太整體的FTA政策運用已從過去傳統的經濟策略轉變為政治與安全上的手段。從美澳FTA與美新FTA兩個已簽署並生效的FTA個案檢視,簽署的關鍵因素皆傾向以911後反恐戰略上的考量與對美政策支持的回饋來解釋,而在洽簽考量上主要是政治與安全因素大於經濟效益的考量。最後,美國並未在與新加坡和澳洲簽訂FTA後引發其他亞太國家積極與美洽簽的效果,因此美國對亞太地區的FTA政策並未達到美國預期之輪軸網絡化目標。
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Preferential trade agreements: building blocks or stumbling blocks - case study of the US importsBothra, Aditi January 1900 (has links)
Master of Arts / Department of Economics / Peri da Silva / Preferential Trade Agreements (PTAs) are known to facilitate liberalization with respect to only a few trading partners and thus they have been a topic of debate for the past two decades especially because their effect on most favored nation (MFN) tariffs is known to be ambiguous. We provide insights for analyzing whether the PTAs indeed hamper or support multilateral liberalization. Using product level official and actual tariffs we provide evidence from the United States (US) import data that the stumbling block effect on the US MFN bound tariffs is present only for goods that receive full preference in books or in actual. However, my dataset does not statistically support the stumbling block hypothesis in the case of Applied tariffs.
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Le désaccord et la critique entre amis : stratégies d'adoucissement dans le discours pré-conflictuelRiou, Lucie January 2013 (has links)
The objective of this study, based on the theories of Facework (Goffman 1967) and Politeness (Brown & Levinson 1978, 1987), is to observe and establish a classification of mitigating strategies used by two groups of friends to express and deal with disagreement and criticism in French. After a critical review of the development of sociopragmatics and of essential notions for the analysis of interactions, the concept of mitigation is presented, including mitigation used in the context of disagreement and criticism. The fieldwork and the transcription process and new conventions are then presented and discussed. For the analysis, three episodes from recordings of naturally-occurring conversations between friends were selected and transcribed. The data were analysed and classified in context with a view to defining both the pragmatic functions of the various mitigators and how they tend to be used by the speakers. The results of the analysis have allowed us to establish a classification of micro-mitigating-strategies within macro-strategies, and to show that speakers were able to mitigate disagreement and criticism, in order of descending frequency, by converging towards the interlocutor, by using modalised forms, by using a didactic, clarificatory speech style, but also by realising a "décrochage énonciatif" (enunciation disconnection) and trying to avoid or minimise the Face Threatening Acts. These observations contribute to the study of mitigating disagreement and criticism among friends, provide initial evidence of a considerable variation in the use of mitigating strategies in conversational French and call for further analysis of this type of conversation in order to determine to what extent these uses of mitigators result from a social behaviour specific to this type of interactional situation or speech acts.
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Mainland China Implements Customs-Free to the Influence of Taiwanese Fruit IndustrySu, Fang-yi 17 July 2009 (has links)
Mainland China and Taiwan successfully joined WTO to be active members in December 2001 and January 2002. They relax economic and trade restrictions from both sides and make the relevant regulations and mechanisms more transparent year by year. Since May 2005, Mainland China implemented preferential policies, such as zero tariff, clearing customs and opening ' the fast roadway ' to many kinds of Taiwan¡¦s fruits, etc.That makes the proportion of Taiwan¡¦s fruits sold in Mainland China improve year by year, and the marketing stronghold expand constantly, too.
According to the past documents and experiences, Taiwan fruit is relatively suitable for taking the gift box and up-market route, and aims at the demand of the high consumption group. Because most people in Mainland China consume the goods for freshness or the demands of giving a present, they would not purchase it in usual time. Therefore, we should avoid depending too much on some agricultural products and overly concentrate on the specific country. What we need to do is carrying on the global market survey, opening up the new service stronghold actively in order to improve the competitiveness of agricultural products in our country. In addition, the consumption habits between the South and North of Mainland China are different. We should make variable marketing strategies for different consumption ethnicities and match their demands and preferences.
We set up an empirical model by using Time Series Analysis and actual data. The research includes the weight and amount sold to Mainland China, policy of zero tariff, old farmers¡¦ subsidies, areas of fruit trees, transportation and storage, Taiwan¡¦s inflation rate and processed goods of farm production. The main conclusion shows that the effect of zero tariff policy is not good enough to Taiwan¡¦s export sales. The possible reason may be that the cross-strait system is not sound. Finally, we compare the changes in production of Taiwan fruits between Years 2004-2008, and choose three levels of Taiwan fruits. The First one is new stars, like betel nuts, mango, orange, grapefruits and shakya. The second one is keeping it¡¦s level, like jujube, pineapple, guava, papaya, starfruit and wax apple. The third one is lack of competition, like coconut, peach, banana, orange, lemon, plum, persimmon, loquat, etc. The possible reason may be come from outside pressure or not suitable to plant in Taiwan.
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