Browsing by Issue Date, starting with "1995"
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- Navegação em robótica móvel baseada em referências naturaisPublication . Ramos, PatriciaNavegação em robótica móvel baseada em referências naturais
- O Direito à informação do administrado e a reserva da intimidadePublication . Meira, Deolinda Maria Moreira AparícioO Direito à informação do administrado e a reserva da intimidade
- As relações accionistas-gestores segundo os tipos de organizaçãoPublication . Coelho, Maria Hélder MartinsOs observadores da vida económica ficarão surpreendidos pela diversidade de formas jurídicas retidas, como quadro de funcionamento das diferentes organizações. Como se pode explicar a coexistência de empresas individuais, de sociedades, de mútuas, de cooperativas, de associações, etc.? E segundo os sectores de actividade onde estão inseridas, como se explica que certas formas surjam com maior frequência que outras ? Poder-se-á dizer que existem formas jurídicas mais ou menos eficazes ? Há economistas americanos que defendem que a prosperidade do mundo ocidental está ligada a dois elementos: o sistema que rege os direitos de propriedade e o tipo de sociedade.
- O Contrato de consórcio no âmbito dos contratos de cooperação entre empresasPublication . Vasconcelos, PauloO Contrato de consórcio no âmbito dos contratos de cooperação entre empresas
- Distributed Belief Revision and Environmental Decision SupportPublication . Malheiro, Benedita; Oliveira, EugénioThis article discusses the development of an Intelligent Distributed Environmental Decision Support System, built upon the association of a Multi-agent Belief Revision System with a Geographical Information System (GIS). The inherent multidisciplinary features of the involved expertises in the field of environmental management, the need to define clear policies that allow the synthesis of divergent perspectives, its systematic application, and the reduction of the costs and time that result from this integration, are the main reasons that motivate the proposal of this project. This paper is organised in two parts: in the first part we present and discuss the developed - Distributed Belief Revision Test-bed - DiBeRT; in the second part we analyse its application to the environmental decision support domain, with special emphasis on the interface with a GIS.
- Evaluation of manipulator direct dynamics using customized Rung-Kutta MethodsPublication . Machado, J. A. Tenreiro; Galhano, Alexandra M. S. F.This paper studies the efficiency of customized Runge-Kutta methods on the evaluation of the direct dynamics of robot manipulators. Customizing consists not only on the elimination of unnecessary and redundant calculation but also on the development of efficient integration methods. In this perspective, we investigate numerical algorithms with high order expansion and integration with adaptive step size based on the embedded estimated of the local truncation error.
- An Intelligent Distributed System for Environmental ManagementPublication . Malheiro, Benedita; Oliveira, EugénioEnvironmental management is a complex task. The amount and heterogeneity of the data needed for an environmental decision making tool is overwhelming without adequate database systems and innovative methodologies. As far as data management, data interaction and data processing is concerned we here propose the use of a Geographical Information System (GIS) whilst for the decision making we suggest a Multi-Agent System (MAS) architecture. With the adoption of a GIS we hope to provide a complementary coexistence between heterogeneous data sets, a correct data structure, a good storage capacity and a friendly user’s interface. By choosing a distributed architecture such as a Multi-Agent System, where each agent is a semi-autonomous Expert System with the necessary skills to cooperate with the others in order to solve a given task, we hope to ensure a dynamic problem decomposition and to achieve a better performance compared with standard monolithical architectures. Finally, and in view of the partial, imprecise, and ever changing character of information available for decision making, Belief Revision capabilities are added to the system. Our aim is to present and discuss an intelligent environmental management system capable of suggesting the more appropriate land-use actions based on the existing spatial and non-spatial constraints.
- Improving Assumption based Distributed Belief RevisionPublication . Malheiro, Benedita; Oliveira, EugénioBelief revision is a critical issue in real world DAI applications. A Multi-Agent System not only has to cope with the intrinsic incompleteness and the constant change of the available knowledge (as in the case of its stand alone counterparts), but also has to deal with possible conflicts between the agents’ perspectives. Each semi-autonomous agent, designed as a combination of a problem solver – assumption based truth maintenance system (ATMS), was enriched with improved capabilities: a distributed context management facility allowing the user to dynamically focus on the more pertinent contexts, and a distributed belief revision algorithm with two levels of consistency. This work contributions include: (i) a concise representation of the shared external facts; (ii) a simple and innovative methodology to achieve distributed context management; and (iii) a reduced inter-agent data exchange format. The different levels of consistency adopted were based on the relevance of the data under consideration: higher relevance data (detected inconsistencies) was granted global consistency while less relevant data (system facts) was assigned local consistency. These abilities are fully supported by the ATMS standard functionalities.
- WinRob: An educational program for roboticsPublication . Tenreiro Machado, J. A.; Galhano, AlexandraThe paper presents a program for robotics education that runs on standard IBM-PC's under Microsoft Windows environment. The WinRob package is designed for undergraduates students and emphasis the aspect of robot modelling and control. The software is self-explanatory and uses menus, dialog boxes with figures and context-dependent on-line help. In this perspective, students are motivated to investigate on the kinematics, dynamics, trajectory planning and control in order to get insight into robotics.
- Intelligent motion control using fractional integrals and derivativesPublication . Tenreiro Machado, J. A.The theory of fractional derivatives and integrals (FDI's) is still in a research stage but recent progresses in the area of chaos reveal promising aspects for future developments. In the field of automatic control systems some preliminary results are restricted to the frequency domain. In this paper a novel method for the FDI approximation is presented. The proposed algorithms adopt the time domain which makes them well suited for z-transform analysis and digital implementation. Based on the new concepts the paper shows that classical P, I and D actions are special cases of a more broad paradigm.