Hugo A. D. Nascimento

Universidade Federal de Goiás | UFG · Instituto de Informática (INF)

Doenças neurodegenerativas (DNDs) causam, dentre outros sintomas, o comprometimento da marcha. Diversos estudos analisam a marcha para, com o auxílio da inteligência artificial, auxiliar no diagnóstico de DNDs. Devido à dificuldade de coleta de novos dados, a técnica de sobreamostragem através do janelamento de dados é frequentemente utilizada. No...

Search space visualizations have important applications in the optimization area, particularly for real-world optimization problems. When supported by interactive tools, they can enhance the cognitive processing of perceiving the complexity of such problems and help guide search algorithms toward good solutions. The present chapter provides an over...

The prediction of academic dropout, with the aim of preventing it, is one of the current challenges of higher education institutions. Machine learning techniques are a great ally in this task. However, attention is needed in the way that academic data are used by such methods, so that it reflects the reality of the prediction problem under study an...

The FWI is formulated as a nonlinear optimization problem that traditionally uses local (derivative-based) minimization to find the scalar field of properties that best represents the field seismic data. This problem has a high computational cost and accuracy limited to local minima, in addition to suffering from a slow convergence rate (Cycle Skip...

Este artigo apresenta um comparativo que, busca salientar os benefícios da utilização do Algoritmo Genético com Fertilização InVitro na resolução do problema de atraso total ponderado em máquina única. Para tanto, são apresentadas outras duas meta-heurísticas que foram utilizadas na resolução do problema. Além disso, buscou-se definir um conjunto d...

Parkinson’s Disease (PD) is a neurodegenerative disease affecting neurons, causing motor and physiological symptoms, such as involuntary movements, weakness, and gait problems. There is no cure for Parkinson’s Disease and diagnosing it, especially in early cases, is a complex task due to the lack of definitive tests. Here, we propose a multiclassif...

Neurodegenerative disease is a general term to describe various diseases that affect the neurons, causing motor and physiological symptoms, such as involuntary movements, weakness, and gait problems. Neurodegenerative diseases do not have a cure, and diagnosing them, especially in early cases, is a hard task due to the lack of definitive tests for...

The interaction challenges presented by touch-screen enabled devices for blind and visually impaired people has been addressed extensively in the literature. However, the emergence of wrist-worn devices with small screens, the so-called smartwatches, exacerbates such challenges. This paper presents an evaluation of text entry methods for smartwatch...

Hashtag segmentation, also known as hashtag decomposition, is a common step in preprocessing pipelines for social media datasets. It usually precedes tasks such as sentiment analysis and hate speech detection. For sentiment analysis in medium to low-resourced languages, previous research has demonstrated that a multilingual approach that resorts to...

The conception, and usage, of methods designed to evaluate information visualizations is a challenge that goes along with the development of these visualizations. In the scientific literature there is a myriad of proposals for such methods. However, none of them was able to pacify the field or establish itself as a de facto standard, due to difficu...

Nesse artigo, analisou-se um procedimento simples para construção de datasets de segmentação de hashtags a partir dos microtextos de dumps de tweets. Foram geradas segmentações automáticas por meio de um algoritmo heurístico, no qual verificamos estatisticamente que esse método consegue corrigir anomalias de modelos avançados de segmentação, podend...

This article introduces Doclass, a free and open-source software for the Web that aims to assist in labeling and classifying large sets of documents. The research involved a design science research methodology, guided by the real demands of a legal text processing company. The architecture, several design decisions and the current development stage...

The Brazilian Digital Library of Thesis and Dissertations (BDTD) provides essential data to support many social sciences investigations. Nevertheless, there is still a lack of computation tools tailored for helping extract and analyze the necessary information from the BDTD library. In this paper, we discuss the development of computational solutio...

Recommender Systems are expert systems that utilize the user’s interests in order to recommend different products. One of the main techniques employed in this type of system is the Collaborative Filtering which recommends products to users based on their interactions and on what items similar users have liked in the past. However, many traditional...

Reduction operations aggregate a finite set of numeric elements into a single value. They are extensively employed in many computational tasks and can be performed in parallel when multiple processing units are available. This work presents a GPU-based approach for parallel reduction, which employs techniques like loop unrolling, persistent threads...

In this systematic literature review (SLR) we summarize studies that address the word segmentation problem (WSP) for Latin-based languages. We adopted the protocol of Kitchenham et al. for the review. The search in academic repositories found 771 works, from which 89 were selected. After a quality assessment step, 69 papers were chosen for data ext...

Scheduling is a very important problem in many organizations, such as hospitals, transportation companies, sports confederations and educational institutions. Obtaining a good schedule results in the maximization of some desired benefit. In particular, in educational institutions (from elementary school to universities) this problem is periodically...

The Full Waveform Inversion (FWI) is an accurate approach for finding high resolution velocity models because it uses all information present in the wavefield. The FWI traditionally employs gradient-based algorithms. Most of these algorithms are of high computational cost and have precision limited to local minima. Derivative-Free Optimization (DFO...

Smartwatches are gaining popularity on market with a set of features comparable to smartphones in a wearable device. This novice technology brings new interaction paradigms and challenges for blind users, who have difficulties dealing with touchscreens. Among a variety of tasks that must be studied, text entry is analyzed, considering that current...

We investigated the characteristics of the subsurface seismic exploration using Full Waveform Inversion (FWI) formulated as a nonlinear optimization problem in one dimension (1D). The FWI technique originally used mathematical methods based on the calculation of derivatives to optimize the objective function that quantifies the misfit between the d...

In the present paper we explore the idea of combining computation power and the availability of ordinary art spectators in order to produce new interactive art works. This is investigated for a particular application, which consists of producing new behaviors for a programmable art apparatus named C3 Cubes. Given the nature of the problem and some...

As an emerging technology that combines mobile and wearable markets, smartwatches are finding their place on consumers' daily lives. They allow tasks that used to be performed only by smartphones and tracking devices. Despite the increasing interest on them, a task that is still not fully covered by these devices is text entry, mainly due to their...

This work proposes the development of a method for smartwatches that allows to control platform games using continuous recognition of gestures and conducts a case study as the game Super Mario World. Uses a set of gestures based on geometric shapes to send actions to the game. Gesture recognition is performed by the algorithm of continuous gesture...

This paper discusses three edge bundling optimization problems that aim to minimize the total number of bundles of a graph drawing, in conjunction with other aspects, as the main goal. A novel evolutionary algorithm for edge bundling for these problems is described. The algorithm was successfully tested by solving the related problems applied to re...

Reduction operations are extensively employed in many computational problems. A reduction consists of, given a finite set of numeric elements, combining into a single value all elements in that set, using for this a combiner function. A parallel reduction, in turn, is the reduction operation concurrently performed when multiple execution units are...

A Parallel Floyd-Warshall Algorithm on GPU

The well-known k-nearest neighbors problem (kNN) involves building a data structure that reports the k closest training points to each of a given set of query points, with all points being in a given metric space S. The problem discussed here is an important operation in rotation-invariant image processing. It consists of a nontrivial variant of kN...

Graph drawing, as a research field, is concerned with the visualization of information modeled in the form of graphs. The present paper is a literature review that identifies the state-of-the-art in applying machine learning techniques to problems in graph drawing. We focused on machine learning strategies that build up and represent knowledge abou...

This paper presents the history of development of Web content mana-ged systems at UFG. It goes from the first system that supported a small set of Web pages to the design and the implementation of a final flexible, robust and modern piece of software, which keeps now hundreds of Web sites of the ins-titution. This latter system, called Weby, was re...

The restriction (prohibition) of certain turns at intersections is a very common task employed by the managers of urban traffic networks. Surprisingly, this approach has received little attention in the research literature. The turning restriction design problem (TRDP) involves finding a set of turning restrictions at intersections to promote flow...

Previous studies have evaluated the work done by software developers using data extracted from version control systems (VCS). However, they have focused mostly on counting the amount of written lines of code and the number of commits, which are general information that can be obtained from these software repositories. In the present article, we inn...

Analyzing and improving large urban traffic networks is a difficult process due to complex interrelationships between the many variables that impact vehicle traffic behavior. Information visualization techniques can facilitate the tasks of analyzing large amounts of data and of exploring potential solutions to practical traffic problems. Surprising...

Este artigo apresenta uma implementa ao paralela baseada em Graphics Processing Unit (GPU) para o problema da identifica ao dos caminhos mínimos entre todos os pares de vértices em um grafo. A implementa aó e baseada no algoritmo Floyd-Warshall e tira o máximo proveito da arquitetura multithreaded das GPUs atuais. Nossa solu ao reduz a comunica ao...

Este artigo apresenta uma implementa ao paralela baseada em Graphics Processing Unit (GPU) para o problema da identifica ao dos caminhos mínimos entre todos os pares de vértices em um grafo. A implementa aó e baseada no algoritmo Floyd-Warshall e tira o máximo proveito da arquitetura multithreaded das GPUs atuais. Nossa solu ao reduz a comunica ao...

An important issue in the management of urban traffic networks is the estimation of origin–destination (O–D) matrices whose entries represent the travel demands of network users. We discuss the challenges of O–D matrix estimation with incomplete, imprecise data. We propose a fuzzy set-based approach that utilises successive linear approximation. Th...

This paper proposes a method to aid blind persons in skill development to walk in unfamiliar environments. The method aims to use the human ability in construct of spatial cognitive maps. Thus, we developed a system that uses the Virtual Reality and Kinect®. Two-dimensional and three-dimensional virtual environments modeling are allowed. It is poss...

This papers reports the Internet attack on UFG's Web site server. It also describes the information visualization techniques, the computational tools and the networking managment solutions that were employed by the University IT team for analysing and miti-gating the problem. Such type of attack is very common and difficult to contain. Therefore, t...

Information Visualization is an emerging scientific field that studies ways of presenting abstract data visually, so that information about that data can be better understood or even discovered. This paper discusses several aspects regarding the visual presentation of data and introduces well known and effective techniques for information visualiza...

E difícil mostrar o crescimento de um software e o esforço desprendido pelos desenvolvedores para a construção do mesmo. Várias abordagens têm sido utilizadas para tentar medir esse esforço e demonstrar o tamanho do sistema como, por exemplo, o uso de métricas de software. Certas abordagens utilizam técnicas de visualização de informações para apre...

Resumo Apresentamos um método de estimação de matrizes origem–destino (OD) para redes viárias urbanas congestionadas. Assume-se que os dados disponíveis incluem estimações incompletas e imprecisas de: contagens de tráfego, entradas OD, partidas em origens e chegadas em destinos. O método consiste de uma sequência de programas lineares fuzzy e foi p...

O presente documento descreve uma iniciativa de melhorias de processos de desenvolvimento de software em um órgão de produção de uma Instituição Federal de Ensino Superior. Além disso, são apresentadas lições aprendidas durante a execução do projeto. Estas lições, bem como o resultado de uma pesquisa sobre o grau de institucionalização do processo,...

This paper presents a Web-based DSS-decision support system - architecture for modeling, simulating and visualizing urban traffic. The architecture innovates by presenting a modeling of the problem that can be distributed and remotely updated by several users, and for using a mathematical model suitable for the Brazilian traffic reality. Moreover,...

This paper describes the usage of a free project management software called Redmine, in order to support the software development process at CERCOMP-UFG. We present the criteria for choosing this application, its main resources and a usage methodology, as well the benefits obtained from his adoption.

Cartography is one of the oldest forms of visualization. It has applications not only in geography but in many other science fields. A significant visual problem in cartography is the map-labeling problem, which consists of assigning positions for the labels of graphical features of a map so that these elements can be uniquely identified. Although...

We investigate the new problem of antomatic metro map layout. In general, a metro map consists of a set of lines which have intersections or overlaps. We define a set of aesthetic criteria for good metro map layouts and present a method to produce such layouts automatically. Our method uses a variation of the spring algorithm with a suitable prepro...

Abstract In the present paper, we introduce a multi-user interactive framework for solving complex optimization problems. The framework, called Co-UserHints, provides a visual computational environment for interaction and visualization. We demonstrate its functionality by presenting a multi-user system for interactive graph drawing. Keywords: inter...

Innovative improvements in the area of human–computer interaction and user interfaces have enabled intuitive and effective applications for a variety of problems. On the other hand, there has also been the realization that several real-world optimization problems still cannot be totally automated. Very often, user interaction is necessary for refin...

A Finite Automaton is a mathematical model of a finite-state machine that reads symbols from a tape and accepts or rejects its input. The Theory of Finite Automata is important for modeling real machines with a finite set of states, for compacting dictionaries, and for several others applications. This paper describes a tool for helping students an...

We initiate a new problem of automatic metro map layout. In general, a metro map consists of a set of lines which have intersections or overlaps. We define a set of aesthetic criteria for good metro map layouts and present a method to produce such layouts automatically. Our method uses a variation of the spring algorithm with a suitable preprocessi...

The Map Labelling Problem appears in several applications, mainly in Cartography. Although much research on this problem has been done, it is interesting to note that map-labelling processes in commercial fields are very often executed manually or with little support of automatic tools. In general, practical map-labelling problems involve human sub...

This paper describes some studies in Human-Computer Interaction for Directed Graph Drawing. We have developed a system where users can help some standard graph drawing algorithms to produce nice drawings of a graph according to a set of aesthetic criteria. The system follows a general framework for interaction with optimisation processes that can b...

This paper presents a system for graph clustering where users can visualize the clustering and give "hints" that help a computing method to find better solutions. Hints include a variety of constraints, as well as direct manipulation of the previously computed clustering. The framework is flexible: it can accommodate several kinds of hints, cluster...

This paper presents a user-driven genetic algorithm for directed graph drawing. An interactive framework is considered where users can focus the algorithm on regions of the drawing that need major improvement, or include domain knowledge as layout constraints. The paper describes how focus and user constraints are managed by the genetic algorithm....

This paper investigates an interactive approach where users can help a system to produce nice drawings of directed graphs by giving hints to graph drawing algorithms. Hints can be three kinds of operations: focus on a specific part of the drawing that needs improvement, insertion of layout constraints, and manual changes of the drawing. These hints...

This paper describes some studies in Human-Computer Interaction for Directed Graph Drawing. We have developed a system where users can help some standard graph drawing algorithms to produce nice drawings of a graph according to a set of aesthetic criteria. The system follows a general framework for interaction with optimisation processes that can b...

This paper presents a system for graph clustering where users can visualize the clustering and give "hints" that help a computing method to find better solutions. Hints include a variety of constraints, as well as direct manipulation of the previously computed clustering. The framework is flexible: it can accommodate several kinds of hints, cluster...

We describe here a collection of heuristics for producing "nice" drawings of directed graphs, and a simple dual-mode software tool for testing and evaluating them. In playing mode, the heuristics are applied in random sequence over a set of drawings, in the manner of an asynchronous team (A-team). As new drawings are added to the set, others are de...

this paper, we investigate new methods which combine existing algorithms. By combining algorithms, we can obtain drawings which satisfy a combination of aesthetic criteria.

Resumo. O presente documento descreve uma iniciativa de melhorias de processos de desenvolvimento de software em um órgão de produção de uma Instituição Federal de Ensino Superior. Além disso, são apresentadas lições aprendidas durante a execução do projeto. Estas lições, bem como o resultado de uma pesquisa sobre o grau de institucionalização do p...

Information Visualization is an emerging scientific area that studies ways of presenting data visually, so that information about the data can be better understood or even dis-covered. This course discusses several aspects regarding the visual presentation of data and introduces well known and effective techniques for information visualization. The...

This paper describes how an initiative to improve software development processes has been led in a software engineering sector of a Federal Institute of Higher Education. Moreover, it presents the lessons learned during this work. Such lessons, as well as the results of a survey on the degree of implementation of the current project, are serving as...