M. Macedo, Elliackin M. N. Figueiredo, Fabiana Soares, H. Siqueira, A. M. A. Maciel, A. Gokhale, C. Bastos-Filho
{"title":"Clustering students based on grammatical errors for on-line education","authors":"M. Macedo, Elliackin M. N. Figueiredo, Fabiana Soares, H. Siqueira, A. M. A. Maciel, A. Gokhale, C. Bastos-Filho","doi":"10.21528/lnlm-vol16-no1-art2","DOIUrl":"https://doi.org/10.21528/lnlm-vol16-no1-art2","url":null,"abstract":"Learning Management System (LMS) is an educational solution created for people who need flexibility regarding time and place. The problem of this kind of tool primarily concerns the difficulty in identifying which students have learned the content correctly. This paper aims to analyze the performance of a group of distance learning students regarding grammar errors in two different terms of an undergraduate course. Our hypothesis relies on the existence of different characteristics that emerge from subgroups of students with similar difficulties. This division can help tutors in educational platforms to develop specific recommendations tasks for each group of students. A previous work applied the well-known K-means algorithm to cluster the groups, but in that paper, we fixed the number of clusters. Therefore, we carried out a methodology to find the best number of clusters to be used in K-means for this problem. Moreover, we also applied the Fuzzy C-means to tackle the clustering problem and analyzed the results obtained by both algorithms using the well-known metrics in the literature (Gap Statistic and Davies-Bouldin) to assess the quality of the obtained groups. The experimental results showed that Fuzzy C-means approach outperforms the K-means algorithm. Moreover, the application of the Spearman Correlation on each group expose several differences, relations and similarities between groups and inside each one.","PeriodicalId":386768,"journal":{"name":"Learning and Nonlinear Models","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122805892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Caos em tempo discreto: introdução, exemplos e representação estatística","authors":"Marcio Eisencraft","doi":"10.21528/LNLM-VOL16-NO1-ART1","DOIUrl":"https://doi.org/10.21528/LNLM-VOL16-NO1-ART1","url":null,"abstract":"Resumo – No presente texto revisitam-se alguns aspectos de sinais caóticos gerados por sistemas de tempo discreto ou mapas. Em particular, destaca-se o emprego de técnicas comumente utilizadas para sinais aleatórios na sua caracterização. Para tanto, inicia-se com uma breve revisão das principais definições e propriedades dos sinais caóticos de tempo discreto, exemplificando-se também diversos mapas capazes de gerá-los. A seguir, as técnicas e conceitos apresentados são utilizados na dedução das caracterı́sticas temporais e espectrais de sinais gerados por alguns mapas lineares por partes. Por fim, sugerem-se temas de pesquisa futuros.","PeriodicalId":386768,"journal":{"name":"Learning and Nonlinear Models","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116801467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Álgebra multilinear aplicada ao reconhecimento facial","authors":"Emanuel D.R. Sena, André Almeida","doi":"10.21528/lnlm-vol16-no1-art3","DOIUrl":"https://doi.org/10.21528/lnlm-vol16-no1-art3","url":null,"abstract":"In this review, the face recognition problem is investigated from the standpoint of multilinear algebra, more specifically the tensor decomposition, and by making use of Gabor wavelets. The feature extraction occurs in two stages: first the Gabor wavelets are applied holistically in feature selection; Secondly facial images are modeled as a higher-order tensor according to the multimodal factors present. Then, the HOSVD is applied to separate the multimodal factors of the images. The proposed facial recognition approach exhibits higher average success rate and stability when there is variation in the various multimodal factors such as facial position, lighting condition and facial expression. We also propose a systematic way to perform cross-validation on tensor models to estimate the error rate in face recognition systems that explore the nature of the multimodal ensemble. Through the random partitioning of data organized as a tensor, the mode-n cross-validation provides folds as subtensors extracted of the desired mode, featuring a stratified method and susceptible to repetition of cross-validation with different partitioning.","PeriodicalId":386768,"journal":{"name":"Learning and Nonlinear Models","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125106068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The lower bound error as an auxiliary technique to select the integration step-size in the simulation of chaotic systems","authors":"W. R. L. Júnior, S. Martins, E. Nepomuceno","doi":"10.21528/LNLM-VOL16-NO1-ART4","DOIUrl":"https://doi.org/10.21528/LNLM-VOL16-NO1-ART4","url":null,"abstract":"This work presents a method to choose the integration step-size h for discretization of nonlinear and chaotic dynamic systems, in order to obtain a simulation with numerical reliability. In this context, the Lower Bound Error is used as an auxiliary technique in the search for the optimal value of h, considering the Fourth Order Runge Kutta as the discretization method. The Lorenz equations, Rössler equations and Duffing-Ueda oscillator were used as case studies. This work, besides investigating the most adequate step-size h for each case, shows that the choice of very small values of h results in significantly inferior solutions, despite the consensus that the smaller the step-size, the higher the accuracy.","PeriodicalId":386768,"journal":{"name":"Learning and Nonlinear Models","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125780958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Máquinas de vetores-suporte: uma revisão","authors":"Ajalmar R. da Rocha Neto","doi":"10.21528/lnlm-vol15-no1-art2","DOIUrl":"https://doi.org/10.21528/lnlm-vol15-no1-art2","url":null,"abstract":"","PeriodicalId":386768,"journal":{"name":"Learning and Nonlinear Models","volume":"120 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127286838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jean Pierre Jarrier Conti, Tiago B. Nion da Silveira, H. S. Lopes
{"title":"Wi-Fi Device Identification in Crowd Counting Using Machine Learning Methods","authors":"Jean Pierre Jarrier Conti, Tiago B. Nion da Silveira, H. S. Lopes","doi":"10.21528/lnlm-vol15-no1-art4","DOIUrl":"https://doi.org/10.21528/lnlm-vol15-no1-art4","url":null,"abstract":"The increase in the availability of computational resources gave rise to new technologies to estimate the amount of people in a given area. In this context, algorithm-based solutions for crowd counting can be grouped into image-based and non-image based approaches, the latter considering any other feature that is not visual. Currently, due to the popularization of smartphones and mobile devices, several researchers have been using Wi-Fi request packets for crowd counting estimation. Assuming that, on average, each person in a given place carries a Wi-Fi device, the number of unique MAC addresses can be associated with the number of people. However, since the probe may capture all Wi-Fi traffic – which may include broadcast messages from other access points or packets from notebooks and desktop devices – some strategy must be applied in order to identify only personal mobile devices, thus improving the method accuracy. In this work, we trained classifiers to segment mobile from static devices through its Wi-Fi behavior pattern. Therefore, using data collected from different devices and in different environments, we evaluated the proposed methodology by using several machine learning algorithms. Best results were achieved with logistic regression and neural network (MLP). The results of this study suggest the feasibility of the proposed method for crowd counting in high-density Wi-Fi zones.","PeriodicalId":386768,"journal":{"name":"Learning and Nonlinear Models","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116449236","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Ferramentas para análise de sistemas caóticos de tempo discreto: um breve tutorial","authors":"J. M. Junior","doi":"10.21528/LNLM-VOL15-NO1-ART1","DOIUrl":"https://doi.org/10.21528/LNLM-VOL15-NO1-ART1","url":null,"abstract":"The main goal of the current paper is to present to the reader fundamental concepts on the analysis and characterization of dicrete-time dynamical systems, in particular those presenting chaotic features. The target task is the reconstruction of strange attractors based on Takens’ Theorem, with focus on the estimation of the embedding dimension and delay. Then, the characterization of chaotic systems is discussed from the point of view of elementary typical properties of that kind of dynamical system, such as boundedness, nonlinearity, predictability and sensitivity to initial conditions. The tutorial is rich in examples and discussion.","PeriodicalId":386768,"journal":{"name":"Learning and Nonlinear Models","volume":"1761 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127452321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Gutoski, L. T. Hattori, Nelson Marcelo Romero Aquino, H. C. Senefonte, Manassés Ribeiro, A. Lazzaretti, H. S. Lopes
{"title":"Qualitative analysis of deep learning frameworks","authors":"M. Gutoski, L. T. Hattori, Nelson Marcelo Romero Aquino, H. C. Senefonte, Manassés Ribeiro, A. Lazzaretti, H. S. Lopes","doi":"10.21528/lnlm-vol15-no1-art3","DOIUrl":"https://doi.org/10.21528/lnlm-vol15-no1-art3","url":null,"abstract":"– Deep learning methods are becoming more popular for complex pattern recognition applications. As result, many frameworks have appeared aiming to facilitate the development of such applications. However, choosing a suitable framework may not be an easy task for new users. In this paper, a qualitative evaluation of four of the most popular Deep Learning frameworks is provided, including: Caffe, Torch, Lasagne and TensorFlow. A printed character recognition task was used as case study, and a Convolutional Neural Network was implemented for this purpose. The analysis focus on issues that are important for the development process and encompasses nine qualitative dimensions, showing the strengths and weaknesses of each framework. It is expected that this analysis can be useful for guiding new users in the area.","PeriodicalId":386768,"journal":{"name":"Learning and Nonlinear Models","volume":"84 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116659882","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Using Self-Organizing Maps as a Decision-Making Tool for Multiobjective Design in Engineering","authors":"F. Campelo, F. Guimarães, J. A. Ramírez","doi":"10.21528/LNLM-VOL7-NO2-ART3","DOIUrl":"https://doi.org/10.21528/LNLM-VOL7-NO2-ART3","url":null,"abstract":"This paper discusses the use of self-organizing maps (SOM) for decision-making in multiobjec- tive design problems. Estimates of the Pareto-optimal solutions for a given problem are mapped onto a two- dimensional grid, where the distance between solutions is a measure of their similarity in the parameter space. By comparing the clustered points and the color grade of those points in the maps, the designer is able to visualize the similarity of the solutions in both the parameter and objective spaces, hence identifying redundant points. With the use of this technique, one is able to work with clusters of solutions instead of individual points, which can simplify the decision-making step. Resumo| Este trabalho discute o uso de mapas auto-organizativos (MAO) como ferramenta de aux lio para tomada de decis~ oes em problemas de projeto multiobjetivo. Estimativas das solu c~ oes Pareto- otimas para um determinado problema s~ ao mapeadas sobre uma malha bidimensional, no qual a dist^ ancia entre as solu c~ oes representa uma medida da similaridade das mesmas. Atrav es de compara c~ oes entre as posi c~ oes e cores dadas a cada ponto neste mapa e poss v el obter uma visualiza c~ ao da semelhan ca destas solu c~ oes, tanto em termos de par^ ametros de projeto quanto de performance nos diversos objetivos do problema, o que possibilita a detec c~ ao de pontos redundantes e o tratamento de conjuntos de solu c~ oes ao inv es de pontos individuais, simplicando assim a etapa de tomada de decis~ oes em um determinado projeto. Palavras-chave| Mapas auto-organizativos, otimiza c~ ao multiobjetivo, tomada de decis~ oes.","PeriodicalId":386768,"journal":{"name":"Learning and Nonlinear Models","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132281811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Método Dialético de Otimização Usando o Princípio da Máxima Entropia","authors":"W. P. D. Santos, F. M. Assis","doi":"10.21528/LNLM-vol7-no2-art2","DOIUrl":"https://doi.org/10.21528/LNLM-vol7-no2-art2","url":null,"abstract":"Resumo A Biologia, a Psicologia e as Ciências Sociais estão intrinsecamente ligadas aos fundamentos do desenvolvimento de métodos e algoritmos em computação evolucionária, como fica evidente em abordagens como algoritmos genéticos, programação evolucionária e otimização por enxame de partículas. Contudo, a Filosofia ainda é vista como algo enigmático, apesar da natureza sistemática de métodos investigativos como a dialética. Neste trabalho é proposto um novo método de otimização baseado na dialética como definida pelos trabalhos de Hegel e pela Filosofia da Práxis, utilizando funções de pertinência obtidas da aplicação do princípio da máxima entropia adaptado a entropia fuzzy, para modelar as interações entre os pólos, as unidades básicas que compõem sistemas dialéticos. Para validar a proposta foram feitas diversas simulações usando funções de teste conhecidas. Este trabalho provou que o algoritmo dialético proposto pode atingir bons resultados em problemas de otimização local e global.","PeriodicalId":386768,"journal":{"name":"Learning and Nonlinear Models","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131149288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}