A carregar...
6 resultados
Resultados da pesquisa
A mostrar 1 - 6 de 6
- Process and execution planning for manufacturing systemsPublication . Moura, António Machado e; Rocha, João; Ramos, Carlos; Vale, ZitaThis paper deals with a system called TPMS (task planning for manufacturing systems). The main aim of this system is to automatically generate programs or sets of commands for robots, AGV's, numerical control machines, etc., without spending much time programming the flexible manufacturing system components. A description of how to automatically generate a high level plan for the task is presented as well as a methodology to automatically calculate the duration of each operation from the machine program. The main contributions include: to link symbolic and execution planning; the referred aims at working for complete manufacturing systems (not for controlling only one robot); different industrial operations (assembly, welding, drilling, etc.) can be considered at the same time.
- Process planning using a genetic algorithm approachPublication . Rocha, João; Ramos, Carlos; Vale, ZitaThis paper presents a system for computer aided process planning (CAPP), using a precedence graph representation of the operations and their restrictions. Description of machine and tool selection is described, as well as the operation sequencing. A genetic algorithm is used to generate the sequence of operations and to select the machine and tools that minimize some criteria (machining time).
- Proposal for the combination of ontology assemble and ontology mapping processesPublication . Silva, Nuno; Santos, Jorge; Rocha, João; Ramos, Carlos; Vale, ZitaOntology mapping is dependent on the matching algorithms, which in turn depends on the semantics of the ontologies. This proposal grounds on two distinct technologies: ontology mapping and ontology assemble. The ontology mapping system is a service-oriented system in which autonomous plug-able services capture and represent the ontology mapping domain’s expertise. Automatic ontology mapping systems perform poorly due to the lack of ontologies’ semantics to reason upon. The assemble process aims to integrate well-founded, proofed knowledge into the domain ontologies, providing extra semantics. Exploiting such semantics indistinct phases of the ontology mapping process, we envisage that such semantics would be very useful in the improvement of the automatic mapping results. Conversely, the ontology mapping experiences would provide feed-back to the assemble process, suggesting its improvement too. The cyclic improvement would run indefinitely. This paper suggests therefore the combination of efforts from both the assemble and mapping processes towards a better semantic relations and assembled ontologies.
- Service-oriented semi-automatic ontology bridgingPublication . Silva, Nuno; Rocha, João; Ramos, Carlos; Vale, ZitaWith the advent of Semantic Web, knowledge-based interoperability faces a new technological shift, in which ontologies and semantic web technologies play a major role. Exploiting the explicit semantic description of the domain of discourse allows reasoning and automatically acquiring semantic relations between two different domains of discourses. Such semantic relations would be further applied in converting data or documents between such domains. This process is named Ontology Mapping. This paper proposes a semi-automatic bridging process, based in the idea that while automatic matching algorithms do not provide enough information to overcome semantic heterogeneity, they represent valuable sources of similarities measurements between ontologies’ entities, which can be combined into an overall similarity measure according to each service specific requirements.
- Evaluation of potential tidal impoundment energy systems in Ria de Aveiro, PortugalPublication . Rocha, João; Abreu, Tiago; Felgueiras, CarlosThe shelving of the seabed and funneling of the water by the estuaries is favorable for tidal impoundment technologies. In this work, the estimation of the tidal potential energy for Ria de Aveiro lagoon was achieved through the application of a model developed in the Delft3D software. This software can reproduce the hydrodynamics of this complex system and simulations were run to identify hot spots to retrieve gravitational potential energy. For the selected places, both power and annual energy were calculated. It was concluded that the tidal energy that can be extracted from Ria de Aveiro is considerable, justifying further studies to consider the accommodation of some type of tidal exploitation, in the foreseeable future.
- Geração e representação de planos para o planeamento do processoPublication . Rocha, João; Ramos, Carlos; Vale, ZitaNeste artigo vamos descrever um sistema designado TPMS (Task Planning for Manufacturing Systems) que tem por finalidade efectuar a geração automática de planos simbólicos para tarefas de fabrico. Este sistema é especialmente útil como auxiliar do Planeamento do Processo, podendo ser também utilizado para estimar o plano óptimo, auxiliando desse modo a fase de Planeamento da Produção, embora não seja concebido para o planeamento operacional de tarefas industriais. O sistema TPMS é capaz de gerar todos os planos, mas só o faz quando o problema não conduz à explosão combinacional. Nestes casos é gerado apenas o melhor plano, atendendo ao critério de minimização do tempo de execução.