Articles

A case study of contributor behavior in Q&A site and tags: the importance of prominent profiles in community productivity

Question-and-answer (Q&A) sites have shown to be a valuable resource for helping people to solve their everyday problems. These sites currently enable a large number of contributors to exchange expertise by di...

Authors: Adabriand Furtado, Nigini Oliveira and Nazareno Andrade

PQR sort: using PQR trees for binary matrix reorganization

Reorganization of rows and columns of a matrix does not modify data but may ease or impair visual analysis of data similarities in this structure, according to Gestalt spatial proximity laws. However, there ar...

Authors: Celmar Guimarães da Silva, Marivaldo Felipe de Melo, Felipi de Paula e Silva and João Meidanis

Editorial

Authors: Maria Cristina Ferreira de Oliveira

Microalgae classification using semi-supervised and active learning based on Gaussian mixture models

Microalgae are unicellular organisms that have different shapes, sizes and structures. Classifying these microalgae manually can be an expensive task, because thousands of microalgae can be found in even a sma...

Authors: Paulo Drews- Jr., Rafael G. Colares, Pablo Machado, Matheus de Faria, Amália Detoni and Virgínia Tavano

Survey on automatic transcription of music

An automatic music transcriber is a device that detects, without human interference, the musical gestures required to play a particular piece. Many techniques have been proposed to solve the problem of automat...

Authors: Tiago Fernandes Tavares, Jayme Garcia Arnal Barbedo, Romis Attux and Amauri Lopes

Mechanized metatheory for a \(\lambda \)-calculus with trust types

As computer programs become increasingly complex, techniques for ensuring trustworthiness of information manipulated by them become critical. In this work, we use the Coq proof assistant to formalise a

Authors: Rodrigo Ribeiro, Lucília Figueiredo and Carlos Camarão

Editorial

Authors: Maria Cristina Ferreira de Oliveira

The evolution of agile software development in Brazil

Agile software development methods have been increasingly adopted worldwide and became one of the mainstream software development approaches. Agile methods have also had an impact on software engineering educa...

Authors: Claudia de O. Melo, Viviane Santos, Eduardo Katayama, Hugo Corbucci, Rafael Prikladnicki, Alfredo Goldman and Fabio Kon

A systematic review on keystroke dynamics

Computing and communication systems have improved our way of life, but have also contributed to an increased data exposure and, consequently, to identity theft. A possible way to overcome this issue is by the ...

Authors: Paulo Henrique Pisani and Ana Carolina Lorena

A review on Relation Extraction with an eye on Portuguese

The task of Relation Extraction is one of the main challenges in Natural Language Processing. We present a review of the state-of-the-art for Relation Extraction in free texts, addressing the progress and diff...

Authors: Sandra Collovini de Abreu, Tiago Luis Bonamigo and Renata Vieira

Syntenic global alignment and its application to the gene prediction problem

Given the increasing number of available genomic sequences, one now faces the task of identifying their protein coding regions. The gene prediction problem can be addressed in several ways, and one of the most...

Authors: Said S. Adi and Carlos E. Ferreira

CogTRA: a deployable mechanism for cognitive transmission rate adaptation in IEEE 802.11 networks

Wireless local area networks have become vastly popular, and IEEE 802.11 is the chosen standard for almost all wireless devices. This standard specifies several modulation and channel coding techniques that mu...

Authors: Luciano J. Chaves, Edmundo R. M. Madeira and Islene C. Garcia

BitTorrent traffic from a caching perspective

BitTorrent currently contributes a significant amount of inter-ISP traffic. This has motivated research and development to explore caching and locality-aware neighbor selection mechanisms for costly traffic re...

Authors: Lesandro Ponciano, Nazareno Andrade and Francisco Brasileiro

Incremental validation of NCL hypermedia documents

This paper proposes an incremental, structural and contextual validation method for Nested Context Language (NCL) documents. As part of the proposed method, we define a declarative metalanguage to ensure low c...

Authors: Rodrigo Costa Mesquita Santos, José Rios Cerqueira Neto, Carlos de Salles Soares Neto and Mário Meireles Teixeira

Editorial

Authors: Maria Cristina Ferreira de Oliveira

Link prediction using a probabilistic description logic

Due to the growing interest in social networks, link prediction has received significant attention. Link prediction is mostly based on graph-based features, with some recent approaches focusing on domain seman...

Authors: José Eduardo Ochoa Luna, Kate Revoredo and Fabio Gagliardi Cozman

A strategy for preparing software organizations for statistical process control

Software organizations have increased their interest in software process improvement (SPI). Nowadays, there are several frameworks that support SPI implementation. Some of them, such as CMMI (Capability Maturi...

Authors: Monalessa Perini Barcellos, Ricardo de Almeida Falbo and Ana Regina Rocha

Terminating constraint set satisfiability and simplification algorithms for context-dependent overloading

Algorithms for constraint set satisfiability and simplification of Haskell type class constraints are used during type inference in order to allow the inference of more accurate types and to detect ambiguity. ...

Authors: Rodrigo Ribeiro, Carlos Camarão and Lucília Figueiredo

Characterizing the communication in the Amazon rainforest: towards a realistic simulation

Many literature papers evaluate solutions in wireless sensor networks by simulation experiments. However, little attention is given to the adequacy of the simulator propagation models to the environment in whi...

Authors: Afonso D. Ribas, Antonio R. Carvalho Jr., Carlos M. S. Figueiredo and Eduardo F. Nakamura

On the analysis of the collaboration network of the Brazilian symposium on computer networks and distributed systems

The Brazilian symposium on computer networks and distributed systems (SBRC) reached its 30th edition as the paramount scientific event in the area of computer networks and distributed systems in Brazil. Faced ...

Authors: Guilherme Maia, Pedro O. S. Vaz de Melo, Daniel L. Guidoni, Fernanda S.H. Souza, Thiago H. Silva, Jussara M. Almeida and Antonio A. F. Loureiro

A survey on automatic techniques for enhancement and analysis of digital photography

The fast growth in the consumer digital photography industry during the past decade has led to the acquisition and storage of large personal and public digital collections containing photos with different qual...

Authors: Claudio S. V. C. Cavalcanti, Herman Martins Gomes and José Eustáquio Rangel De Queiroz

Functional test data generation for Simulink-like models

Embedded systems are increasingly present in many electronic devices and is often related to critical applications. Therefore, the need for a well planned and executed testing procedure is even higher. We inte...

Authors: Rodrigo Fraxino Araujo, Marcio Eduardo Delamaro and Jose Carlos Maldonado

Ambiguity and context-dependent overloading

This paper discusses ambiguity in the context of languages that support context-dependent overloading, such as Haskell. A type system for a Haskell-like programming language that supports context-dependent ove...

Authors: Rodrigo Ribeiro and Carlos Camarão

A conceptual-driven survey on future internet requirements, technologies, and challenges

Nowadays, research initiatives to redesign the Internet are popping up around the world. Each of these projects has a particular focus and its own set of design requirements and key technologies. The panorama ...

Authors: Antonio Marcos Alberti

Challenges for mesoscale climatology execution on experimental grid computing systems

This paper discusses the challenges of executing a long-term application on a computational grid, which generates the climatology of the atmospheric numerical model BRAMS (Brazilian development on Regional Atmosp...

Authors: Eugenio Sper de Almeida, Haroldo Fraga de Campos Velho and Airam Jonatas Preto

Editorial

Authors: Maria Cristina Ferreira de Oliveira

A Hajós-like theorem for weighted coloring

The Hajós’ Theorem (Wiss Z Martin Luther Univ Math-Natur Reihe, 10, pp 116–117, 1961) shows a necessary and sufficient condition for the chromatic number of a given graph ...

Authors: J. Araujo and C. Linhares Sales

Scrum adoption and architectural extensions in developing new service applications of large financial IT systems

The use of modern agile software development methods in large organisations requires tailoring agile development to the organisations’ needs. This study concentrated on studying integrating software product li...

Authors: Tuomas Ihme

Marching cubes technique for volumetric visualization accelerated with graphics processing units

Volume visualization has numerous applications that benefit different knowledge domains, such as biology, medicine, meteorology, oceanography, geology, among others. With the continuous advances of technology,...

Authors: Marcos Vinicius Mussel Cirne and Hélio Pedrini

Portuguese text generation using factored language models

As in many other natural language processing (NLP) fields, the use of statistical methods is now part of mainstream natural language generation (NLG). In the development of systems of this kind, however, there...

Authors: Eder Miranda de Novais and Ivandré Paraboni

A semantic approach for QoS specification of communication services using QoE parameters

Various operations related to Quality of Service (QoS) management in communication networks require the clients/users to specify the quality level of the network service. The current QoS proposals adopt a fixe...

Authors: José Cé Júnior, Achilles C. Prudêncio, Roberto Willrich and Madalena P. da Silva

A method to convert floating to fixed-point EKF-SLAM for embedded robotics

The Extended Kalman Filter (EKF) is one of the most efficient algorithms to address the problem of Simultaneous Localization And Mapping (SLAM) in the area of autonomous mobile robots. The EKF simultaneously e...

Authors: Leandro de Souza Rosa and Vanderlei Bonato

A set of novel modifications to improve algorithms from the A* family applied in mobile robotics

This paper presents a set of novel modifications that can be applied to any grid-based path planning algorithm from the A* family used in mobile robotics. Five modifications are presented regarding the way the...

Authors: Tiago Pereira do Nascimento, Pedro Costa, Paulo G. Costa, António Paulo Moreira and André Gustavo Scolari Conceição

Feasible path planning for fixed-wing UAVs using seventh order Bézier curves

This study presents a novel methodology for generating smooth feasible paths for autonomous aerial vehicles in the three-dimensional space based on a variation of the Spatial Quintic Pythagorean Hodographs cur...

Authors: Armando Alves Neto, Douglas G. Macharet and Mario F. M. Campos

Parallel transitive closure algorithm

Authors: C. E. R. Alves, E. N. Cáceres, A. A. de Castro Jr., S. W. Song and J. L. Szwarcfiter

Editorial

Authors: Maria Cristina Ferreira de Oliveira

Evaluation of parameters for combining multiple textual sources of evidence for Web image retrieval using genetic programming

Web image retrieval is a research area that is receiving a lot of attention in the last few years due to the growing availability of images on the Web. Since content-based image retrieval is still considered v...

Authors: Patrícia Correia Saraiva, João M. B. Cavalcanti, Marcos A. Gonçalves, Katia C. Lage dos Santos, Edleno S. de Moura and Ricardo da S. Torres

Generating a pronunciation dictionary for European Portuguese using a joint-sequence model with embedded stress assignment

This paper addresses the problem of grapheme to phoneme conversion to create a pronunciation dictionary from a vocabulary of the most frequent words in European Portuguese. A system based on a mixed approach f...

Authors: Arlindo Veiga, Sara Candeias and Fernando Perdigão

Automatic generation of Brazilian sign language windows for digital TV systems

Deaf people have serious difficulties accessing information. The support for sign language (their primary means of communication) is rarely addressed in information and communication technologies. Furthermore,...

Authors: Tiago Maritan Ugulino de Araújo, Felipe Lacet Silva Ferreira, Danilo Assis Nobre dos Santos Silva, Felipe Hermínio Lemos, Gutenberg Pessoa Neto, Derzu Omaia, Guido Lemos de Souza Filho and Tatiana Aires Tavares

On-the-fly extraction of hierarchical object graphs

Reverse engineering techniques are usually applied to extract concrete architecture models. However, these techniques usually extract models that just reveal static architectures, such as class diagrams. On th...

Authors: Hugo de Brito, Humberto Torres Marques-Neto, Ricardo Terra, Henrique Rocha and Marco Tulio Valente

Reducing the impact of location errors for target tracking in wireless sensor networks

In wireless sensor networks (WSNs), target tracking algorithms usually depend on geographical information provided by localization algorithms. However, errors introduced by such algorithms affect the performan...

Authors: Éfren L. Souza, Eduardo F. Nakamura, Horácio A. B. F. de Oliveira and Carlos M. S. Figueiredo

A semi-automated method for acquisition of common-sense and inferentialist knowledge

This paper presents a semi-automated method for the acquisition of common-sense and inferentialist concepts in Portuguese. Its innovative feature is a module of reasoning over the pre-existing knowledge that a...

Authors: Vladia Pinheiro, Vasco Furtado, Tarcísio Pequeno and Wellington Franco

Automatic student modeling in adaptive educational systems through probabilistic learning style combinations: a qualitative comparison between two innovative stochastic approaches

Considering learning and how to improve students’ performances, adaptive educational systems must know the way in which an individual student learns best. In this context, this work presents a comparison betwe...

Authors: Fabiano A. Dorça, Luciano V. Lima, Márcia A. Fernandes and Carlos R. Lopes

A model for inference of emotional state based on facial expressions

Non-verbal communication is of paramount importance in person-to-person interaction, as emotions are an integral part of human beings. A sociable robot should therefore display similar abilities as a way to in...

Authors: Rafael A. M. Gonçalves, Diego R. Cueva, Marcos R. Pereira-Barretto and Fabio G. Cozman

A coherence analysis module for SciPo: providing suggestions for scientific abstracts written in Portuguese

SciPo is a writing tool whose ultimate goal is to assist novice writers in producing scientific writing in Portuguese, focusing primarily on abstracts and introductions from computer science. In this paper, we...

Authors: Vinícius Mourão Alves de Souza and Valéria Delisandra Feltrim

Evaluation of desktop operating systems under thrashing conditions

Virtual memory mechanisms allow offering more RAM memory space to processes than the amount of memory physically available in the system, using disk space as a memory extension. When there is not enough RAM me...

Authors: Carlos Maziero, Douglas dos Santos and Altair Santin

Forgetting mechanisms for scalable collaborative filtering

Collaborative filtering (CF) has been an important subject of research in the past few years. Many achievements have been made in this field, however, many challenges still need to be faced, mainly related to ...

Authors: João Vinagre and Alípio Mário Jorge

Space D*

This paper describes a new method of path-planning for multiple robots in unknown environments. The method, called Space D*, is based on two algorithms: the D*, which is an incremental graph search algorithm, ...

Authors: Luan Silveira, Renan Q. Maffei, Silvia S. C. Botelho, Paulo L. Drews Jr., Alessandro de L. Bicho and Nelson L. Duarte Filho

D-Confidence: an active learning strategy to reduce label disclosure complexity in the presence of imbalanced class distributions

In some classification tasks, such as those related to the automatic building and maintenance of text corpora, it is expensive to obtain labeled instances to train a classifier. In such circumstances it is com...

Authors: Nuno Filipe Escudeiro and Alípio Mário Jorge

b-Coloring graphs with large girth

A b-coloring of a graph is a coloring of its vertices such that every color class contains a vertex that has a neighbor in all other classes. The b-chromatic number of a graph is the largest integer k such that t...

Authors: Victor Campos, Victor A. E. de Farias and Ana Silva