ESTG - Escola Superior de Tecnologia e Gestão
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- Control of baker’s yeast fermentation: PID and fuzzy algorithmsPublication . Machado, Carlos; Gomes, Pedro; Soares, Rui; Pereira, Sílvia; Soares, Filomena BaptistaA MATLAB/SIMULINK-based simulator was employed for studies concerning the control of baker’s yeast fed-batch fermentation. Four control algorithms were implemented and compared: the classical PID control, two discrete versions- modified velocity and position algorithms, and a fuzzy law. The simulation package was seen to be an efficient tool for the simulation and tests of control strategies of the nonlinear process.
- Using attractor dynamics to generate decentralized motion control of two mobile robots transporting a long object in coordinationPublication . Soares, Rui; Bicho, EstelaDynamical systems theory is used here as a theoretical language and tool to design a distributed control architecture for a team of two mobile robots that must transport a long object and simultaneously avoid obstacles. In this approach the level of modeling is at the level of behaviors. A “dynamics” of behavior is defined over a state space of behavioral variables (heading direction and path velocity). The environment is also modeled in these terms by representing task constraints as attractors (i.e. asymptotically stable states) or reppelers (i.e. unstable states) of behavioral dynamics. For each robot attractors and repellers are combined into a vector field that governs the behavior. The resulting dynamical systems that generate the behavior of the robots may be nonlinear. By design the systems are tuned so that the behavioral variables are always very close to one attractor. Thus the behavior of each robot is controled by a time series of asymptotically stable states. Computer simulations support the validity of our dynamic model architectures.
- Aplicação do Método da Transformada de Laplace a uma Classe de Operadores Integrais de ConvoluçãoPublication . Correia, AldinaRESUMO------------------------------------------------------------------------------------------------------------------------ Neste trabalho apresentamos resultados do nosso estudo sobre operadores integrais de convolução, baseado no método das transformadas de Laplace e de Mellin. Apresentamos as definições e estabelecemos condições da sua existência, em vários espaços de Lebesgue. Além disso, provamos fórmulas de inversão de certos operadores integrais de convolução do tipo de Mellin. São discutidas algumas relações entre a transformada de Laplace e a transformada Mellin. Por fim, aplicamos estes métodos na investigação de operadores de convolução de Mellin, relacionados com núcleos associados a funções de Bessel, de Gauss e de Bessel modificadas.
- Agent based simulation for group formationPublication . Marreiros, Goreti; Santos, Ricardo; Ramos, Carlos; Neves, JoséGroup decision making plays an important role in today’s organisations. The impact of decision making is so high and complex, that rarely the decision making process is made just by one individual. The simulation of group decision making through a Multi-Agent System is a very interesting research topic. The purpose of this paper it to specify the actors involved in the simulation of a group decision, to present a model to the process of group formation and to describe the approach made to implement that model. In the group formation model it is considered the existence of incomplete and negative information, which was identified as crucial to make the simulation closer to the reality.
- Agent Based Simulation for Group FormationPublication . Marreiros, Goreti; Santos, Ricardo; Ramos, Carlos; Neves, JoséGroup decision making plays an important role in today’s organisations. The impact of decision making is so high and complex, that rarely the decision making process is made just by one individual. The simulation of group decision making through a Multi-Agent System is a very interesting research topic. The purpose of this paper it to specify the actors involved in the simulation of a group decision, to present a model to the process of group formation and to describe the approach made to implement that model. In the group formation model it is considered the existence of incomplete and negative information, which was identified as crucial to make the simulation closer to the reality.
- Coordinated transportation of a large object by a team of two robotsPublication . Soares, Rui; Bicho, EstelaIn this paper dynamical systems theory is used as a theoretical language and tool to design a distributed control architecture for a team of two robots that must transport a large object and simultaneously avoid collisions with obstacles (either static or dynamic). This work extends the previous work with two robots (see [1] and [5]). However here we demonstrate that it’s possible to simplify the architecture presented in [1] and [5] and reach an equally stable global behavior. The robots have no prior knowledge of the environment. The dynamics of behavior is defined over a state space of behavior variables, heading direction and path velocity. Task constrains are modeled as attractors (i.e. asymptotic stable states) of a behavioral dynamics. For each robot, these attractors are combined into a vector field that governs the behavior. By design the parameters are tuned so that the behavioral variables are always very close to the corresponding attractors. Thus the behavior of each robot is controlled by a time series of asymptotic stable states. Computer simulations support the validity of the dynamical model architecture.
- Coordinated transportation of a large object by a team of three robotsPublication . Soares, Rui; Bicho, EstelaDynamical systems theory in this work is used as a theoretical language and tool to design a distributed control architecture for a team of three robots that must transport a large object and simultaneously avoid collisions with either static or dynamic obstacles. The robots have no prior knowledge of the environment. The dynamics of behavior is defined over a state space of behavior variables, heading direction and path velocity. Task constraints are modeled as attractors (i.e. asymptotic stable states) of the behavioral dynamics. For each robot, these attractors are combined into a vector field that governs the behavior. By design the parameters are tuned so that the behavioral variables are always very close to the corresponding attractors. Thus the behavior of each robot is controlled by a time series of asymptotical stable states. Computer simulations support the validity of the dynamical model architecture.
- Using an integrative approach to assess brand identityPublication . Barros, Teresa; Martins, Francisco VitorinoThere is a wide agreement that identity is a multidisciplinary concept. The authors consider this an opportunity do develop a framework to assess identity. In a marketing context, literature reveals two approaches on identity: one focus on corporate identity and the other focus on branding. The aim of this paper is to integrate these two approaches to develop a synthesis framework to assess brand identity. Based on literature on identity the authors found nine components related to brand identity. Those components are described in this paper as well as the relation they have with brand identity. The authors hope that this synthesis approach contributes to a better understanding of the brand identity, and are very encouraging for refining this framework in the future.
- A type-level approach to component prototypingPublication . Barbosa, Luís; Cunha, Jácome; Visser, Joost
- Marketing social e gestão de voluntários em ONG'sPublication . Ferreira, Marisa R.; Proença, João F.; Proença, TeresaEste trabalho apresenta um projecto de investigação que relaciona a área do marketing social com a gestão do voluntariado em ONG’s. Trata-se de uma primeira reflexão que contextualiza a problemática da gestão de pessoas não remuneradas nessas organizações e introduz diversas questões sobre a gestão das ONG’s e do voluntariado. Nomeadamente, qual o papel do voluntariado nas ONG’s e quais as principais motivações associadas ao voluntariado? Como é que as ONG’s podem recrutar e seduzir de forma eficaz o voluntariado? Qual a particularidade do comportamento organizacional nestas organizações, como, por exemplo, que conflitos surgem entre os corpos profissionalizados e os voluntários nessas organizações?