2012
Autores
Macedo, Nuno; Cunha, Alcino;
Publicação
CoRR
Abstract
1999
Autores
Belo, O; Cunha, A;
Publicação
Proceedings of the IEEE International Conference on Systems, Man and Cybernetics
Abstract
In the last few years, information outsourcing has been a current activity on large companies. Information as become a regular trading commodity. It is a well known fact that direct mailing companies acquire databases, or other kind of information sources, from other companies with names and addresses of potential clients. Also, enterprise managers are frequently concerned with the current status and welfare of their clients and suppliers. Commonly, they use to appeal to specialized external information providers which may, under certain conditions, provide them specific profiles about such potential commercial partners. On companies with effective means of information processing, it is very probable that such needs of information may be directly satisfied with data stored and managed in the companies' data warehouses. In this paper we propose a protocol based on economic principles that enables the automatic negotiation of information transference between data warehouse systems of different companies. The protocol was designed to be used by a community of intelligent agents responsible to ensure and support all the operational tasks related to information outsourcing among companies.
1998
Autores
Ribeiro, A; Cunha, A; Belo, O;
Publicação
ESS'98 - SIMULATION TECHNOLOGY: SCIENCE AND ART
Abstract
Today's dynamic industrial process simulation problems require systematically new methodologies and sophisticated computational tools. Such processes involve frequently discontinuities, environment structures changes and entities with high functional levels. Furthermore, there are cases where we must integrate intelligent techniques and negotiation protocols. These characteristics are crucial in distributed problems that require resource balance, low cost distribution plans, and stock optimization. In order to analyse the application of a distributed object-oriented simulation system we selected, as a case study, a gas distribution network in which we find all the referred characteristics. This paper presents a brief description of the simulation scenario, the overall system's structure, the intelligent negotiation protocol used by system's objects and the concurrent programming techniques to implement it.
1997
Autores
Cunha, A; Santos, LP; Belo, O;
Publicação
SIMULATION IN INDUSTRY: 9TH EUROPEAN SIMULATION SYMPOSIUM 1997
Abstract
Load distribution is a well known critical problem in every distributed system. From operating systems to agent oriented applications it is not difficult to find cases where processing nodes are overloaded when, at the same time, other peers present low levels of activity. In agent oriented applications, where the appeal to cooperation is almost a constant event, these unbalanced situations may generate serious cases of contention, deadlock or simply large idle times. The implementation of load distribution strategies in a distributed system may help significantly to improve its overall performance and reduce effectively such undesirable situations. In order to study the effects of different load distribution policies in agent based applications a generic load distribution simulation system was design and implemented. The system allows the specification of multiorganisational distributed systems with dynamic load patterns. Its main characteristics and functionalities are presented in this paper.
1997
Autores
Cunha, A; Biscaia, C; Torres, M; Sobral, L; Belo, O;
Publicação
APPLICATIONS OF HIGH PERFORMANCE COMPUTING IN ENGINEERING V
Abstract
This paper presents and discusses the design and the development of a pattern recognition agent based on neural networks. This agent is part of an intelligent navigation system, providing it with the necessary vision abilities so that it can be placed on a strange environment in order to explore and recognise its structures and specificities. Although similar, the properties of the recognised objects change through time and according to each specific environment. The flexibility required by such recognition process was implemented by several pattern recognition agents. Each agent is based on a neural network and can be trained on-line by a parallel training algorithm to allow an effective real time utilisation.
2023
Autores
Barros, M; Ramos, M; Gomes, A; Cunha, A; Pereira, J; Almeida, PS;
Publicação
FORMAL TECHNIQUES FOR DISTRIBUTED OBJECTS, COMPONENTS, AND SYSTEMS, FORTE 2023
Abstract
Automatic grading based on unit tests is a key feature of massive open online courses (MOOC) on programming, as it allows instant feedback to students and enables courses to scale up. This technique works well for sequential programs, by checking outputs against a sample of inputs, but unfortunately it is not adequate for detecting races and deadlocks, which precludes its use for concurrent programming, a key subject in parallel and distributed computing courses. In this paper we provide a hands-on evaluation of verification and testing tools for concurrent programs, collecting a precise set of requirements, and describing to what extent they can or can not be used for this purpose. Our conclusion is that automatic grading of concurrent programming exercises remains an open challenge.
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