18 research outputs found

    B-spline curve interpolation model by using intuitionistic fuzzy approach

    Get PDF
    In this paper, B-spline curve interpolation model by using intuitionistic fuzzy set approach is introduced. Firstly, intuitionistic fuzzy control point relation is defined based on the intuitionistic fuzzy concept. Later, the intuitionistic fuzzy control point relation is blended with B-spline basis function. Through interpolation method, intuitionistic fuzzy B-spline curve model is visualized. Finally, some numerical examples and an algorithm to generate the desired curve is shown

    B-spline curve interpolation model by using intuitionistic fuzzy approach

    Get PDF
    In this paper, B-spline curve interpolation model by using intuitionistic fuzzy set approach is introduced. Firstly, intuitionistic fuzzy control point relation is defined based on the intuitionistic fuzzy concept. Later, the intuitionistic fuzzy control point relation is blended with B-spline basis function. Through interpolation method, intuitionistic fuzzy B-spline curve model is visualized. Finally, some numerical examples and an algorithm to generate the desired curve is shown

    Compensação de atrito no controle de sistemas mecânicos: uma abordagem utilizando estratégias inteligentes

    Get PDF
    Friction can be found in almost all mechanical systems. In many cases, however, it is undesirable and has to be minimized and/or compensated. Besides of speeding up the wear of its components, friction is strongly associated with the nonlinear behavior of a mechanical system. It should also be noted that when the system has to be controlled, friction hampers the achievement of an efficient control law, due to its nonlinear feature and the issues related to the development of a mathematical model that accurately describes it. In this context, based on an adaptive sliding mode control approach, this work presents the development of a friction identification/control strategy. In addition to the ability to compensate for friction, the proposed control scheme an also cope with other unmodeled dynamics. The proposed strategy is able to identify the dynamics of the plant as well as its variation due to changes in friction characteristics. Moreover, the proposed scheme can also indicate the precise moment that friction’s variation occurs. The following contributions should be highlighted: (i) the introduction of a unifying approach, capable of combining different algorithms of computational intelligence; (ii) the development of a new adaptation scheme that reduces the computational complexity of the adjustment method; (iii) an index related to friction variation, which is based on the real-time evaluation of the approximate model of the system; (iv) an intelligent sliding mode controller that does not require prior knowledge of the dynamics of the plant and can retain its performance even when there are significant changes in operating conditions. The stability of the proposed intelligent controller is demonstrated by means of a Lyapunov-like analysis. The efficacy of the designed control scheme is evaluated by means of both numerical and experimental studies with electro-hydraulic actuated system.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)O atrito está presente em praticamente todos os tipos de sistemas mecânicos. Em muitos casos, porém, ele é indesejável e precisa ser minimizado e/ou compensado. Além de acelerar o desgaste de seus componentes, o atrito está fortemente associado ao comportamento não-linear de um sistema mecânico. Deve-se ainda ressaltar que, quando o sistema precisa ser controlado, o atrito dificulta a obtenção de um controlador eficiente, em virtude de sua característica não-linear e da dificuldade de se obter um modelo matemático que o descreva com exatidão. Neste contexto, este trabalho apresenta o desenvolvimento de uma estratégia de controle e identificação do atrito, bem como demais dinâmicas não modeladas, baseada na técnica de controle por modo deslizante adaptativo. A estratégia proposta identifica a dinâmica do sistema, bem como sua variação quando ocorrem modificações das características do atrito. O método apresentado também possibilita indicar o momento que ocorreu a variação deste atrito. Destaca-se como contribuições principais: (i) a apresentação de uma abordagem unificadora, capaz de combinar diferentes algoritmos provenientes da área de inteligência computacional; (ii) a apresentação de uma nova estratégia para redução da complexidade do método de ajuste; (iii) um indicador da variação do atrito, baseado na análise em tempo real do modelo aproximado do sistema; (iv) um controlador inteligente por modo deslizante que não requer conhecimento prévio da dinâmica do sistema a ser controlado, e que mantém a sua performance mesmo quando há a alterações significativas do sistema em tempo real. A dedução da estabilidade do controlador é demonstrada através da teoria de estabilidade de Lyapunov. Sua viabilidade é demonstrada através de resultados numéricos e experimentais obtidos utilizando como exemplo de estudo um atuador eletro-hidráulico

    Políticas de Copyright de Publicações Científicas em Repositórios Institucionais: O Caso do INESC TEC

    Get PDF
    A progressiva transformação das práticas científicas, impulsionada pelo desenvolvimento das novas Tecnologias de Informação e Comunicação (TIC), têm possibilitado aumentar o acesso à informação, caminhando gradualmente para uma abertura do ciclo de pesquisa. Isto permitirá resolver a longo prazo uma adversidade que se tem colocado aos investigadores, que passa pela existência de barreiras que limitam as condições de acesso, sejam estas geográficas ou financeiras. Apesar da produção científica ser dominada, maioritariamente, por grandes editoras comerciais, estando sujeita às regras por estas impostas, o Movimento do Acesso Aberto cuja primeira declaração pública, a Declaração de Budapeste (BOAI), é de 2002, vem propor alterações significativas que beneficiam os autores e os leitores. Este Movimento vem a ganhar importância em Portugal desde 2003, com a constituição do primeiro repositório institucional a nível nacional. Os repositórios institucionais surgiram como uma ferramenta de divulgação da produção científica de uma instituição, com o intuito de permitir abrir aos resultados da investigação, quer antes da publicação e do próprio processo de arbitragem (preprint), quer depois (postprint), e, consequentemente, aumentar a visibilidade do trabalho desenvolvido por um investigador e a respetiva instituição. O estudo apresentado, que passou por uma análise das políticas de copyright das publicações científicas mais relevantes do INESC TEC, permitiu não só perceber que as editoras adotam cada vez mais políticas que possibilitam o auto-arquivo das publicações em repositórios institucionais, como também que existe todo um trabalho de sensibilização a percorrer, não só para os investigadores, como para a instituição e toda a sociedade. A produção de um conjunto de recomendações, que passam pela implementação de uma política institucional que incentive o auto-arquivo das publicações desenvolvidas no âmbito institucional no repositório, serve como mote para uma maior valorização da produção científica do INESC TEC.The progressive transformation of scientific practices, driven by the development of new Information and Communication Technologies (ICT), which made it possible to increase access to information, gradually moving towards an opening of the research cycle. This opening makes it possible to resolve, in the long term, the adversity that has been placed on researchers, which involves the existence of barriers that limit access conditions, whether geographical or financial. Although large commercial publishers predominantly dominate scientific production and subject it to the rules imposed by them, the Open Access movement whose first public declaration, the Budapest Declaration (BOAI), was in 2002, proposes significant changes that benefit the authors and the readers. This Movement has gained importance in Portugal since 2003, with the constitution of the first institutional repository at the national level. Institutional repositories have emerged as a tool for disseminating the scientific production of an institution to open the results of the research, both before publication and the preprint process and postprint, increase the visibility of work done by an investigator and his or her institution. The present study, which underwent an analysis of the copyright policies of INESC TEC most relevant scientific publications, allowed not only to realize that publishers are increasingly adopting policies that make it possible to self-archive publications in institutional repositories, all the work of raising awareness, not only for researchers but also for the institution and the whole society. The production of a set of recommendations, which go through the implementation of an institutional policy that encourages the self-archiving of the publications developed in the institutional scope in the repository, serves as a motto for a greater appreciation of the scientific production of INESC TEC

    Fuelling the zero-emissions road freight of the future: routing of mobile fuellers

    Get PDF
    The future of zero-emissions road freight is closely tied to the sufficient availability of new and clean fuel options such as electricity and Hydrogen. In goods distribution using Electric Commercial Vehicles (ECVs) and Hydrogen Fuel Cell Vehicles (HFCVs) a major challenge in the transition period would pertain to their limited autonomy and scarce and unevenly distributed refuelling stations. One viable solution to facilitate and speed up the adoption of ECVs/HFCVs by logistics, however, is to get the fuel to the point where it is needed (instead of diverting the route of delivery vehicles to refuelling stations) using "Mobile Fuellers (MFs)". These are mobile battery swapping/recharging vans or mobile Hydrogen fuellers that can travel to a running ECV/HFCV to provide the fuel they require to complete their delivery routes at a rendezvous time and space. In this presentation, new vehicle routing models will be presented for a third party company that provides MF services. In the proposed problem variant, the MF provider company receives routing plans of multiple customer companies and has to design routes for a fleet of capacitated MFs that have to synchronise their routes with the running vehicles to deliver the required amount of fuel on-the-fly. This presentation will discuss and compare several mathematical models based on different business models and collaborative logistics scenarios

    XVIII International Coal Preparation Congress

    Get PDF
    Changes in economic and market conditions of mineral raw materials in recent years have greatly increased demands on the ef fi ciency of mining production. This is certainly true of the coal industry. World coal consumption is growing faster than other types of fuel and in the past year it exceeded 7.6 billion tons. Coal extraction and processing technology are continuously evolving, becoming more economical and environmentally friendly. “ Clean coal ” technology is becoming increasingly popular. Coal chemistry, production of new materials and pharmacology are now added to the traditional use areas — power industry and metallurgy. The leading role in the development of new areas of coal use belongs to preparation technology and advanced coal processing. Hi-tech modern technology and the increasing interna- tional demand for its effectiveness and ef fi ciency put completely new goals for the University. Our main task is to develop a new generation of workforce capacity and research in line with global trends in the development of science and technology to address critical industry issues. Today Russia, like the rest of the world faces rapid and profound changes affecting all spheres of life. The de fi ning feature of modern era has been a rapid development of high technology, intellectual capital being its main asset and resource. The dynamics of scienti fi c and technological development requires acti- vation of University research activities. The University must be a generator of ideas to meet the needs of the economy and national development. Due to the high intellectual potential, University expert mission becomes more and more called for and is capable of providing professional assessment and building science-based predictions in various fi elds. Coal industry, as well as the whole fuel and energy sector of the global economy is growing fast. Global multinational energy companies are less likely to be under state in fl uence and will soon become the main mechanism for the rapid spread of technologies based on new knowledge. Mineral resources will have an even greater impact on the stability of the economies of many countries. Current progress in the technology of coal-based gas synthesis is not just a change in the traditional energy markets, but the emergence of new products of direct consumption, obtained from coal, such as synthetic fuels, chemicals and agrochemical products. All this requires a revision of the value of coal in the modern world economy
    corecore