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Publications

2007

Stream-based electricity load forecast

Authors
Gama, J; Rodrigues, PP;

Publication
Knowledge Discovery in Databases: PKDD 2007, Proceedings

Abstract
Sensors distributed all around electrical-power distribution networks produce strean is of data it high-speed. From a data mining perspective, this sensor network problem is characterized by a large number of variables (sensors), producing a continuous flow of data, in a dynamic non-stationary environment. Companies make decisions to buy or sell energy based on load profiles and forecast. We propose an architecture based on an online clustering algorithm where each cluster (group of sensors with high correlation) contains a neural-network based predictive model. The goal is to maintain in real-time a clustering model and a predictive model able to incorporate new information at the speed data arrives. detecting changes and adapting the decision models to the most recent information. We present results illustrating the advantages of the proposed architecture, on several temporal horizons, and its competitiveness with another predictive strategy.

2007

A tool for interactive subgroup discovery using distribution rules

Authors
Lucas, JP; Jorge, AM; Pereira, F; PernaS, AM; Machado, AA;

Publication
PROGRESS IN ARTIFICIAL INTELLIGENCE, PROCEEDINGS

Abstract
We describe an approach and a tool for the discovery of subgroups within the framework of distribution rule mining. Distribution rules are a kind of association rules particularly suited for the exploratory study of numerical variables of interest. Being an exploratory technique, the result of a distribution mining process is typically a very large number of patterns. Exploring such results is thus a complex task and limits the use of the technique. To overcome this shortcoming we developed a tool, written in Java, which supports subgroup discovery in a post-processing step. The tool engages the analyst in an interactive process of subgroup discovery by means of a graphical interface with well defined statistical grounds, where domain knowledge can be used during the identification of such subgroups amid the population. We show a case study to analyze the results of students in a large scale university admission examination.

2007

An MPEG-21 Web Peer for the consumption of Digital Items

Authors
Ciobanu, G; Andrade, MT; Carvalho, P; Carrapatoso, E;

Publication
NOVAS PERSPECTIVAS EM SISTEMAS E TECNOLOGIAS DE INFORMACAO, VOL II

Abstract
MPEG-21 enables content consumers to access and interoperate with a large variety of multimedia resources and their descriptions in a flexible manner. Considering the great heterogeneity that presently exists across the entire multimedia content chain and the growing importance of open standards to facilitate the interoperations across environments, applications and formats, an MPEG-21 Peer was developed to process and present complex multimedia content, represented as MPEG-21 Digital Items. The novelty of the work essentially relies on the adoption of a Web Services architecture, based on a single Digital Items processing core available for all types of terminal devices.

2007

Agent-based inter-organizational workflow management system

Authors
Leitao, P; Mendes, J;

Publication
HOLONIC AND MULTI-AGENT SYSTEMS FOR MANUFACTURING, PROCEEDINGS

Abstract
An Electronic Institution is a computational framework that provides a set of services supporting the lifecycle of Virtual Organizations. In a virtual organization, different business partners cooperate in order to achieve a common goal (the established contract), being the coordination of the corresponding inter-organizational workflow an important issue. This paper describes an inter-organizational workflow management architecture, based in multi-agent systems principles, aiming to orchestrate the contract execution and to obtain feedback from the shop floor level. Aiming to validate its correctness and applicability, a special focus is devoted to its implementation, using the JADE agent development framework, and its operation under different scenarios.

2007

Exploiting parallelism in configurable architectures through custom array mapping

Authors
Baradaran, N; Diniz, PC;

Publication
IET COMPUTERS AND DIGITAL TECHNIQUES

Abstract
Configurable architectures offer the unique opportunity of customising the storage allocation to meet specific applications' needs. A compiler approach to map the arrays of a loop-based computation to internal memories of a configurable architecture with the objective of minimising the overall execution time is described. An algorithm that considers the data access patterns of the arrays along the critical path of the computation as well as the available storage and memory bandwidth is presented. Experimental results are presented which demonstrate the application of this approach for a set of kernel codes when targeting a field-programmable gate-array. The results reveal that the proposed algorithm outperforms the naive and custom data layout techniques by an average of 33% and 15% in terms of execution time, while taking into account the available hardware resources.

2007

Social theatres: A web-based regulated social interaction environment

Authors
Paredes, H; Martins, FM;

Publication
Groupware: Design, Implementation, and Use, Proceedings

Abstract
The growth of the Internet and its associated technologies did open space for a new type of human interaction: virtual, social interaction environments. The introduction of regulated interaction in these virtual interaction spaces may be a solution towards their organization and inherent increased credibility. In this paper we propose a model for interaction regulation and control for virtual, social interaction spaces, called Social Theatres. A multi-layer software architecture was developed to support this web-based interaction model, allowing easy construction of such social interaction spaces and adaptation to users' devices. This paper discusses the advantages of regulated interaction, addresses the Social Theatre metaphor and presents the software architecture for the implementation of these regulated social interaction spaces.

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