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Publicações

2008

Partial data reuse for nested loop computations: design space exploration for FPGA implementations

Autores
Park, J; Diniz, PC;

Publicação
INTERNATIONAL JOURNAL OF ELECTRONICS

Abstract
Automated compiler analyses and transformation techniques aim at improving design productivity of the mapping process of applications expressed in high-level programming languages to FPGAs. These transformations allow a compiler tool to reduce the number of design cycles and eliminate tedious and error-prone low-level transformations required in this mapping process, while still leading to good designs. Scalar replacement, also known as register promotion, is a very important data-oriented transformation that leads to designs that reduce the number of external memory accesses, and thus reduce execution time, at the expense of storage resource's. In this article we present a combination of loop transformation techniques, namely loop unrolling, loop splitting, and loop interchange with scalar replacement to enable partial data reuse on computations expressed by tightly nested loops pervasive in image processing algorithms. We describe a performance modelling in the presence of partial data reuse. Our experimental results reveal that our model accurately captures the non-trivial execution effects of pipelined implementations in the presence of partial data reuse due to the need to fill-up data buffers. The model thus allows a compiler to explore a large design space with high accuracy, ultimately allowing quickly it to find better designs than designs with limited manual search or brute-force approaches.

2008

Funchal 500 years: Learning Through Role Play Games

Autores
Baptista, R; de Cardalho, CV;

Publicação
2ND EUROPEAN CONFERENCE ON GAMES BASED LEARNING

Abstract
It is commonly accepted that the educational environment has been undergoing considerable change due to the use of the Information and Communication tools. But learning depends upon actions such as experimenting, comprehending, visualizing, abstracting and demonstrating, by means of which the learner succeeds in constructing his own knowledge. It is not always easy to achieve these actions through current distance learning approaches. Since we live in a society that demands creativity, globalization, responsibility, autonomy and the ability to deal with virtuality and new technologies, Role Playing Games (RPG) may well develop such capacities. The creation of an interactive computer game with RPG characteristics, about the 500th anniversary of the city of Funchal, the capital of Madeira Island, is invested with compelling educational/pedagogical implications, aiming clearly at teaching history and social relations through playing. By incorporating the concept "games to teach", players will interpret different characters in different settings/scenarios, experiencing adventures, meeting challenges and reaching multiple and simultaneous goals in the areas of education, entertainment and social integration along the first 150 years of the history of Funchal. Through this process they will live and understand all the social and historical factors of that age.

2008

Secure biometric authentication with improved accuracy

Autores
Barbosa, M; Brouard, T; Cauchie, S; de Sousa, SM;

Publicação
INFORMATION SECURITY AND PRIVACY

Abstract
We propose a new hybrid protocol for cryptographically secure biometric authentication. The main advantages of the proposed protocol over previous solutions can be summarised as follows: (1) potential for much better accuracy using different types of biometric signals, including behavioural ones; and (2) improved user privacy, since user identities are not transmitted at any point in the protocol execution. The new protocol takes advantage of state-of-the-art identification classifiers, which provide not only better accuracy, but also the possibility to perform authentication without knowing who the user claims to be. Cryptographic security is based on the Paillier public key encryption scheme.

2008

Automatic Extraction of Process Control Flow from I/O Operations

Autores
Diniz, PC; Ferreira, DR;

Publicação
BUSINESS PROCESS MANAGEMENT

Abstract
Many end users will expect the output of process mining to be a model they can easily understand. On the other hand, knowing which objects were accessed in each operation can be a valuable input for process discovery. From these two trends it is possible to establish an analogy between process mining and the discovery of program structure. In this paper we present an approach for extracting process control-flow from a trace of read and write operations over a set of objects. The approach is divided in two independent phases. In the first phase, Fourier analysis is used to identify periodic behavior that can be represented with loop constructs. In the second phase, a match-and-merge technique is used to produce a control-flow graph capable of generating the input trace and thus representing the process that generated it. The combination of these techniques provides a structured and compact representation of the unknown process, with very good results in terms of conformance metrics.

2008

Work in Progress - Learning Through Role Play Games

Autores
Batista, R; de Carvalho, CV;

Publicação
FIE: 2008 IEEE FRONTIERS IN EDUCATION CONFERENCE, VOLS 1-3

Abstract
It is commonly accepted that the educational environment has been undergoing considerable change due to the use of the Information and Communication tools. But learning depends upon actions such as experimenting, visualizing and demonstrating through which the learner succeeds in constructing his own knowledge. Although it is not easy. to achieve these actions through current ICT supported learning approaches, Role Playing Games (RPG) may well develop such capacities. The creation of an interactive computer game with RPG characteristics, about the 500th anniversary of the city of Funchal, the capital of Madeira Island, is invested with compelling educational/pedagogical implications, aiming clearly at teaching history and social relations through playing. Players interpret different characters in different settings/scenarios, experiencing adventures, meeting challenges and trying to reach multiple and simultaneous goals in the areas of education, entertainment and social integration along the first 150 years of the history of Funchal. Through this process they will live and understand all the social and historical factors of that epoch.

2008

The Economic Advantage of Being the "Voice of the Majority"

Autores
Resende, J;

Publicação
JOURNAL OF MEDIA ECONOMICS

Abstract
This article analyzes price competition in it duopolistic newspaper industry. where politically differentiated newspapers compete in 2 distinct markets: circulation and advertising. Assuming that 1 of the newspapers represents the "voice of the majority," the theory of the circulation spiral is investigated and whether the interdependence between newspapers' demands in the circulation and advertising markets favors the majority's newspaper to the detriment of the minority's newspaper is investigated.

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