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- A multi-agent environment in roboticsPublication . Oliveira, Eugénio; Camacho, R.; Ramos, CarlosThe use of Multi-Agent Systems as a Distributed AI paradigm for Robotics is the principal aim of our present work. In this paper we consider the needed concepts and a suitable architecture for a set of Agents in order to make it possible for them to cooperate in solving non-trivial tasks. Agents are sets of different software modules, each one implementing a function required for cooperation. A Monitor, an Acquaintance and Self-knowledge Modules, an Agenda and an Input queue, on the top of each Intelligent System, are fundamental modules that guarantee the process of cooperation, while the overall aim is devoted to the community of cooperative Agents. These Agents, which our testbed concerns, include Vision, Planner, World Model and the Robot itself.
- Addressing the facilities layout design problem through constraint logic programmingPublication . Tavares, José; Ramos, Carlos; Neves, JoséOne of the most difficult problems that face researchers experimenting with complex systems in real world applications is the Facility Layout Design Problem. It relies with the design and location of production lines, machinery and equipment, inventory storage and shipping facilities. In this work it is intended to address this problem through the use of Constraint Logic Programming (CLP) technology. The use of Genetic Algorithms (GA) as optimisation technique in CLP environment is also an issue addressed. The approach aims the implementation of genetic algorithm operators following the CLP paradigm.
- MASCEM: A Multiagent System That Simulates Competitive Electricity MarketsPublication . Praça, Isabel; Ramos, Carlos; Vale, Zita; Cordeiro, ManuelAround the world, the electricity industry, which has long been dominated by vertically integrated utilities, is experiencing major changes in the structure of its markets and regulations. Owing to new regulations, it's evolving into a distributed industry in which market forces drive electricity's price. The industry is becoming competitive; a market environment is replacing the traditional centralized-operation approach. This transformation is often called the deregulation of the electricity market. MASCEM, a multiagent simulator system, is a valuable framework for evaluating new rules, new behavior, and new participants in the numerous electricity markets that are moving toward liberalization and competition.
- Reducing job throughout time: using horizontal scheduling and simultaneous manufacturingPublication . Almeida, Ana; Ramos, Carlos; Silva, Sílvio do Carmo; Kendall, Graham; Burke, Edmund; Petrovic, SanjaThis paper is concerned with reducing job throughput time in job-shop like manufacturing systems using a Horizontal Scheduling approach. We follow this approach because we aim at compressing job throughout time to a minimum. To further enhance this objective we apply Simultaneous Manufacturing through the widespread use of batch overlapping. For this we use a mechanism called Job Scheduling Pattern, which in addition to be particularly effective in reducing job throughout time, maintains operating simplicity and calls for reduced manufacturing coordination.
- An agent-based approach to support decisions on electronic marketplacesPublication . Viamonte, Maria João; Ramos, Carlos; Rodrigues, Maria de Fátima Coutinho; Cardoso, José; Ramos, Carlos; Vale, ZitaWith the increasing importance of Electronic Commerce across the Internet the need for software agents to support both customers and suppliers in buying and selling goods/services is growing rapidly. It is becoming increasingly evident that in a few years the Internet will host a large number of interacting software agents. Most of them will be economically motivated, and will negotiate a variety of goods and services. It is therefore important to consider the economic incentives and behaviours of economic software agents, and to use all available means to anticipate their collective interactions. This paper addresses this concern by presenting a Market Simulator designed for analysing agent market strategies based on a complete understanding of buyer and seller behaviours, preference models and pricing algorithms. The system includes agents that are capable of increasing their performance with their own experience, by adapting to the market conditions. The results of the negotiations between agents will be analysed by Data mining tools in order to extract rules that will give the agents feedback to improve their strategies. We will describe the characteristics and technologies involved in the architecture we are specifying and developing.
- Fabricare: an agent-based system for manufacturingPublication . Sousa, Paulo; Neves, José; Ramos, Carlos; Ramos, Carlos; Vale, ZitaDue to current and future trends in manufacturing, computer-supported manufacturing systems are now more distributed than the traditional CIM approach. This paper presents a prototype system for the problem of scheduling of manufacturing orders, focusing on the internal implementation of each type of agent in the system.
- Hybrid methods for the maintenance scheduling of generating units problemPublication . Gomes, Nuno; Cordeiro, Manuel; Vale, Zita; Ramos, Carlos; Ramos, Carlos; Vale, ZitaReal world search and optimization problems are usually characterized by having large search spaces, being difficult to model and being constantly changing. Constraint Logic Programming (CLP) has proved to be a good tool to model and solve this type of problems despite some efficiency problems. It seams that the problem is related to some lack of a “global perspective” of the constraints in the search process, One way of overcoming this problem is to hybridize Constraint Logic Programming with Linear Programming (LP) in order to enhance the solving process by finding feasible solutions early in the search by “global reasoning”. In this work we propose 4 hybrid methods for solving a Maintenance Scheduling of Generating Units problem. The main idea is to take the advantages of both CLP and LP avoiding their problems. Some initial tests show that for some conditions all the hybrid methods can perform better than CLP alone.
- 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.
- Decision support for power system control centers – a model based reasoning componentPublication . Malheiro, Nuno; Vale, Zita; Ramos, Carlos; Cordeiro, Manuel; Marques, Albino; Couto, Vieira; Ramos, Carlos; Vale, ZitaThe increasing demand on Power System Control Centers (PSCC) for optimization of the use of the Electrical Network implies, as one of its key focuses, the fastest possible restoration of service. Human PSCC operators (PSCCO) control the Electrical Network aided by a distributed system of sensors and actuators, which produce temporal information about the networks’ state. These distributed systems are known as Supervisory Control and Data acquisition or SCADA systems. In incident situations, in which SCADA systems can produce huge amounts of information, PSCCOs can become very stressed and loose the necessary focus to perform an accurate diagnosis and hence proper power restoration. Several approaches have been made to develop systems which can cope with the particularly hard features of this problem in real-time. This paper presents a model based teasoning component which is integrated in a multicomponent system with the task of Electrical Network diagnosis and restoration. This particular component adds adaptability to the system ensuring correct behaviour on any topological variation of the part of the electrical network in service or its protection schemes. The whole system is fully functional and operating in the Portuguese Electrical Network Dispatch Center.
- An architecture to integrate discovered knowledge in a rule based systemPublication . Oliveira, Paulo; Rodrigues, Maria de Fátima Coutinho; Ramos, Carlos; Vale, ZitaThe techniques and tools of Knowledge Discovery in Databases seek to transform data into knowledge in an “intelligent” and semi-automatic way. One of the possible uses to this discovered knowledge consists in its integration or fusion with the knowledge that is in the knowledge base of an Expert System. It thus complements the knowledge . initially given by the expert, which is not always complete, or the most up-to-date. Using an alternative source it is possible to discover knowledge that is implicit in data, and then proceed with its fusion with the one already in the knowledge base. However, this process can result in errors appearing (for example, inconsistencies) in the knowledge base resulting from the fusion. Thus, one of the requirements to fulfil is the consistency and correction of this new knowledge base. A generic and domain independent architecture that allows a rule based knowledge fusion, in the context above described is presented. Consistency and correction are guaranteed through the detection of errors, and by the adoption of an approach based in maximal consistent subsets of rules.