Resultados da pesquisa - "Ferreira, Nuno M."

Catálogo de Publicações - "Ferreira, Nuno M."

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  1. 1

    A new concept of ceramic consumable anode for iron pyroelectrolysis in magnesium aluminosilicate melts

    Publicação
    por Ferreira, Nuno M.
    Outros Autores: Kovalevsky, Andrei V.; Ferro, Marta C.; Costa, Florinda M.; Frade, Jorge R.
    Drivenbyenvironmentalchallengesandglobalmovementtocarbonleantechnologies,thepyroelec trolysisprocessforironextractionfromoxidemeltsisbeingproposedasaninterestingalternativetothe traditional steelmaking.Still,oneofthecriticalissuesimpactingtheprospectsofthistechnologyincludes the developmentofappropriateanodematerials,takingintoaccounttheextremelyaggressivenatureof oxidemeltsatveryhightemperatures.Hereweproposeauniqueconceptofconsumableanodefor pyroelectrolysisprocess,basedonmulticomponentferrospinelbasedceramics.Theelectrochemical studies andpostmortemXRD/SEM/EDSanalysisoftheelectrolysiscellshavedemonstratedthatceramic spinel anodescansustainsignificant currentdensitiesformakingtheprocessfeasible,whiletheir consumption byinteractionwithSicontainingspeciesfromthemoltenelectrolytewasfoundtobe moderate.
    2016 artigo Portugal acesso restrito
  2. 2

    Processing Effects on Properties of (Fe,Mg,Al)(3)O-4 Spinels as Potential Consumable Anodes for Pyroelectrolysis

    Publicação
    por Ferreira, Nuno M.
    Outros Autores: Kovalevsky, Andrei V.; Costa, Florinda M.; Frade, Jorge R.
    A promising concept of consumable anode materials for high-temperature pyroelectrolysis process, which is expected to overcome the environmental and economical impacts of classical extractive metallurgy, relies on substituted magnetite-based ferrospinels, presenting high electrical conductivity, appropriate refractoriness, and redox stability. The present work aims assessment of the processing effects on structural, redox, and electrical properties of Fe2.3Al0.2Mg0.5O4 spinel, prepared by conventional solid-state route (SSR) and laser floating zone (LFZ) method. The observed trends for high-temperature electrical conductivity behavior indicated that the electronic transport is only slightly affected by the preparation method, suggesting the minor effects from the grain boundaries. For scaled-up ferrospinel-based consumable anodes the impact of oxidation during thermal cycling on electrical properties and electrode integrity can be minimized even in air, by using relatively fast cooling/heating rates.
    2016 artigo Portugal acesso restrito
  3. 3

    A new concept of ceramic consumable anode for iron pyroelectrolysis in magnesium aluminosilicate melts

    Publicação
    por Ferreira, Nuno M.
    Outros Autores: Kovalevsky, Andrei V.; Ferro, Marta C.; Costa, Florinda M.; Frade, Jorge R.
    Driven by environmental challenges and global movement to carbon-lean technologies, the pyroelectrolysis process for iron extraction from oxide melts is being proposed as an interesting alternative to the traditional steelmaking. Still, one of the critical issues impacting the prospects of this technology includes the development of appropriate anode materials, taking into account the extremely aggressive nature of oxide melts at very high temperatures. Here we propose a unique concept of consumable anode for pyroelectrolysis process, based on multicomponent ferrospinel-based ceramics. The electrochemical studies and post-mortem XRD/SEM/EDS analysis of the electrolysis cells have demonstrated that ceramic spinel anodes can sustain significant current densities for making the process feasible, while their consumption by interaction with Si-containing species from the molten electrolyte was found to be moderate. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
    2016 artigo Portugal acesso restrito
  4. 4

    Interacção com um robô através de linguagem natural falada

    Publicação
    por Ferreira, Nuno M.
    Outros Autores: Ferreira, Nuno F.; Rodrigues, Mário; Teixeira, António; Vaz, Francisco; Lopes, Luís Seabra
    Developing a system capable of using spoken language for interaction with humans has been pursued by several studies. Such systems are interesting by allowing humans to communicate with machines in a simple and intuitive way. The spoken language interface with a robot (named Carl), in development as part of the CARL project, is presented in this paper. We present, mainly, existing technologies, available tools and connection of all interface subsystems: speech synthesis, speech recognition and natural language processing.
  5. 5

    Two cooperating manipulators with fractional controllers

    Publicação
    por Ferreira, Nuno M. F.
    Outros Autores: Machado, J. A. Tenreiro; Tar, József K.
    This paper analyzes the dynamic performance of two cooperative robot manipulators. It is studied the implementation of fractional-order algorithms in the position/force control of two cooperating robotic manipulators holding an object. The simulations reveal that fractional algorithms lead to performances superior to classical integer-order controllers.
    2010 capítulo de livro Portugal acesso aberto
  6. 6

    Marketing familiar: o marketing aplicado à gestão familiar

    Publicação
    por Ferreira, Nuno M F
    Este projeto descreve a discussão conceptual da filosofia de marketing aplicada à gestão familiar. Pretendeu-se com isto mostrar como o marketing pode ser aplicado como filosofia de gestão à família, conduzindo à concretização dos objetivos educacionais de uma forma mais pragmática e na linha da perspetiva mais atual de marketing que defende a definição de valores e ética como a condição para a sustentabilidade duma organização que na nossa perspetiva pode ser a familiar. Nesse sentido procedeu-se à aplicação do planeamento estratégico de marketing, ferramenta fundamental na operacionalização nesta filosofia de gestão, onde foram definidas as estratégias de marketing passíveis de serem seguidas pelas famílias, nomeadamente a religiosa, a tribal, a da natureza e a cívica, e à definição do marketing operacional assente nos “4 E”, que são “Experience” (Experiência), “Exchange” (Troca), “Everyplace” (Em todo lugar) e “Evangelism” (Evangelizar.
    2014 dissertação de mestrado Portugal acesso aberto
  7. 7

    Modeling and control of a dragonfly-like robot

    Publicação
    por Couceiro, Micael S.
    Outros Autores: Ferreira, Nuno M. F.; Machado, J. A. Tenreiro
    Dragonflies demonstrate unique and superior flight performances than most of the other insect species and birds. They are equipped with two pairs of independently controlled wings granting an unmatchable flying performance and robustness. In this paper, the dynamics of a dragonfly-inspired robot is studied. The system performance is analyzed in terms of time response and robustness. The development of computational simulation based on the dynamics of the robotic dragonfly allows the test of different control algorithms. We study different movements, the dynamics, and the level of dexterity in wing motion of the dragonfly. The results are positive for the construction of flying platforms that effectively mimic the kinematics and dynamics of dragonflies and potentially exhibit superior flight performance than existing flying platforms.
    2010 artigo Portugal acesso aberto
  8. 8

    Application of fractional algorithms in the control of a robotic bird

    Publicação
    por Couceiro, Miguel S.
    Outros Autores: Ferreira, Nuno M. F.; Machado, J. A. Tenreiro
    In this paper, it is studied the dynamics of the robotic bird in terms of time response and robustness. It is analyzed the wing angle of attack and the velocity of the bird, the tail influence, the gliding flight and the flapping flight. The results are positive for the construction of flying robots. The development of computational simulation based on the dynamic of the robotic bird should allow testing strategies and different algorithms of control such as integer and fractional controllers.
    2010 artigo Portugal acesso aberto
  9. 9

    Hybrid adaptive control of a dragonfly model

    Publicação
    por Couceiro, Micael S.
    Outros Autores: Ferreira, Nuno M. F.; Machado, J. A. Tenreiro
    Dragonflies show unique and superior flight performances than most of other insect species and birds. They are equipped with two pairs of independently controlled wings granting an unmatchable flying performance and robustness. In this paper, it is presented an adaptive scheme controlling a nonlinear model inspired in a dragonfly-like robot. It is proposed a hybrid adaptive (HA) law for adjusting the parameters analyzing the tracking error. At the current stage of the project it is considered essential the development of computational simulation models based in the dynamics to test whether strategies or algorithms of control, parts of the system (such as different wing configurations, tail) as well as the complete system. The performance analysis proves the superiority of the HA law over the direct adaptive (DA) method in terms of faster and improved tracking and parameter convergence.
    2012 artigo Portugal acesso aberto
  10. 10

    Benchmark of swarm robotics distributed techniques in a search task

    Publicação
    por Couceiro, Micael S.
    Outros Autores: Vargas, Patricia A.; Rocha, Rui P.; Ferreira, Nuno M. F.
    This paper presents a survey on multi-robot search inspired by swarm intelligence by further classifying and discussing the theoretical advantages and disadvantages of the existing studies. Subsequently, the most attractive techniques are evaluated and compared by highlighting their most relevant features. This is motivated by the gradual growth of swarm robotics solutions in situations where conventional search cannot find a satisfactory solution. For instance, exhaustive multi-robot search techniques, such as sweeping the environment, allow for a better avoidance of local solutions but require too much time to find the optimal one. Moreover, such techniques tend to fail in finding targets within dynamic and unstructured environments. This paper presents experiments conducted to benchmark five state-of-the-art algorithms for cooperative exploration tasks. The simulated experimental results show the superiority of the previously presented Robotic Darwinian Particle Swarm Optimization (RDPSO), evidencing that sociobiological inspiration is useful to meet the challenges of robotic applications that can be described as optimization problems (e.g., search and rescue). Moreover, the RDPSO is further compared with the best performing algorithms within a population of 14 e-pucks. It is observed that the RDPSO algorithm converges to the optimal solution faster and more accurately than the other approaches without significantly increasing the computational demand, memory and communication complexity.
    2014 artigo Portugal acesso aberto