Navegando por Assunto "Linear regression"

Agora exibindo 1 - 5 de 5

Acesso aberto (Open Access)
Análise dos fatores relacionados ao desempenho das escolas no IDEB: estudo de caso no Estado do Pará
(Universidade Federal do Pará, 2022-02-11) GOMES, Vitor Hugo Macedo; SILVA, Marcelino Silva da
The complexity of identifying all the factors that are related to the performance of schools on the Basic Education Development Index (IDEB) is enormous. In this study, three databases were analyzed with the objective of identifying several factors that correlate with low performance in state schools in the state of Pará. Initially, it was observed through the analysis that 142 municipalities in the state were at risk of not meeting the goal regarding the reduction of school dropouts and, consequently, affecting the performance of schools. This study used educational data mining techniques to, first, select variables with structural characteristics in the teaching environment, comparing the schools with higher and lower performance in IDEB, identifying possible relationships with school dropouts. Then, the Randon Florest (RF) algorithm was used to select the most important variables that directly or indirectly impact the IDEB index. After the selection phase, the variables were submitted to the Linear Regression (LR) algorithm. The results reveal that in the group of schools below average in IDEB, 60.6% reside in families with incomes up to one minimum wage, while 37.5% have incomes above one minimum wage. In the group of schools above average in IDEB, 42.4% live in families with incomes up to one minimum wage, while 51.6% live in families with incomes above one minimum wage. Evidencing that family income is related to better IDEB scores and, consequently, better infrastructure conditions. The results also indicate that the income of students’ families is related to the average family income in the analyzed municipalities. Next, variables related to parents’ income were used to identify a possible relationship between parents’ schooling and students’ performance. Finally, the analysis ends with the analysis of the impact of the Municipal Human Development Index (HDI) on the variables related to the students’ grades, the teachers’ qualifications, and the teachers’ experience in the school environment. The results reveal that there is a correlation between the index and student learning in the classroom. On the other hand, better IDEB scores are directly related to the adequacy of the curriculum to the subject taught, in addition to good working conditions for teachers.
Acesso aberto (Open Access)
Análise não paramétrica para identificação de fontes de distorções harmônicas em sistemas de energia elétrica: um estudo aplicado no campus universitário do Guamá da Universidade Federal do Pará
(Universidade Federal do Pará, 2016-02-19) MATOS, Edson Ortiz de; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813
Nowadays, the use of non-linear loads and power electronics-based equipment in residential, commercial and industrial facilities are contributing to the significant increase of current harmonic distortion levels and, consequently voltage harmonic distortions, as noted in the Brazilian distribution systems. Increasing levels of harmonic distortion in electrical distribution networks is a concern to electric utilities and customers, because the presence of these harmonic sources causes, among others, loss of quality in the energy supply. With a focus on this problem, this thesis proposes the development of non-parametric regression models to identify and quantify what non-linear loads can be considered main sources of voltage harmonic distortion at a point of interest in the electric network. The proposed methodology is based on data correlation analysis, using non-parametric regression statistical models to establish the correlation among the non-linear loads harmonic currents and harmonic voltage at a point of interest. This model is built from harmonic voltage and currents measurements, obtained in measuring campaigns using power quality analyzers installed at the points of interest. In addition, it should be pointed out that these harmonic voltages and currents must be express in base units, rather than percent values in relation to the fundamental component, in order to prevent the influence in the creation of the regression model. An important aspect in this methodology is the use of techniques based on Kernel local polynomial regression, for the estimation of the regression model between harmonic voltage and current. To validate the models it is introduced the determination coefficient R2, which can be obtained from the Pearson correlation coefficient, to measure the accuracy degree of the developed models. The non-parametric regression procedure provides a great flexibility in the estimation of regression models, since it makes possible to carry out a more effective model fit to the data samples, and therefore it is able to characterize the influence of each harmonic source in more detail for the entire measurement period. This technique presented more reliable results and overcomes the shortcomings of the linear regression model, which requires the harmonic currents of other sources, called background, not to vary when analyzing a particular load current. The linear and non-parametric regression models were simulated using the program R, which is a language and environment for statistical calculations and graphs, and as test system it was used the Federal University of Pará electric distribution network, consisting of 84 (84) load busbars in 13.8 kV. The results so obtained are compared to those obtained with the linear regression models, and presented good performance, allowing its application for electric power distribution companies.
Acesso aberto (Open Access)
Estimação de crosstalk em redes c-ran com fronthaul de cobre
(Universidade Federal do Pará, 2019-02-26) MONTEIRO, Waldeir de Brito; BORGES, Gilvan Soares; http://lattes.cnpq.br/7696860178450119; COSTA, João Crisóstomo Weyl Albuquerque; http://lattes.cnpq.br/9622051867672434
The implementation of the 5G standard will make the current mobile network architectures evolve towards C-RAN configurations, which are characterized by concentrating processing on a base station, from where the signal is distributed to remote antennas. To maintain uniform coverage, these systems rely on a dense network of low-power antennas scattered throughout buildings. This approach increases the complexity of the network’s Multi Input Multi Output (MIMO) system, which may hamper certain measurements involving equipment at both ends of the link. This work presents a method for the estimation of Far End Crosstalk (FEXT) and Insetion Loss (IL) using only one end of the link in order to bavoid synchronization problems present in complex MIMO systems. Compared to other methods with similar proposals, the presented technique combines a simpler approach to a lesser degree of dependence on dual loop measurements, besides complementing techniques that can accomplish these measurements, but in a restricted range of frequencies
Acesso aberto (Open Access)
LABSQL: laboratório de ensino de SQL
(Universidade Federal do Pará, 2007-12-19) LINO, Adriano Del Pino; FAVERO, Eloi Luiz; http://lattes.cnpq.br/1497269209026542
This work presents a new approach for automatic evaluation of SQL queries. This approach proposes a solution for a challenge to stimulate the student to improve his/her solution: searching, besides an answer that returns a correct result, a query with a complexity next to the optimum solution. This proposal can be used in e-learning environments or in presential education in laboratory activities, including the evaluations. The proposed solution has as advantages: (1) the student receives an instantaneous feedback during a practice programming activity, which allows the student to refactorize his/her solution in direction to a optimum solution; (2) complete integration between the programming concepts teaching with examples of fragments of on-line executable programs; (3) monitoring of students activities (how many examples were executed; in each exercise how many execution attempts were done, etc). This work is the first pass in direction to the construction of an environment, totally attended (for example with automatic evaluation) for teaching of SQL programming language, where the instructor is free of the hard work to correct SQL commands, being able to do more relevant pedagogic tasks. The method, based on statistics and Software Engineering metrics, can be adapted for other languages, such as Java and Pascal. In addition, the LabSQL serves as a laboratory for experimentation of two news techniques, one of evaluation and other of accompaniments that are being searched in several works at the same time: (a) automatic evaluation of discursive conceptual questions, besides to allow the traditional objective questions, (b) method of accompaniment through a montage of evaluation rubrics.
Acesso aberto (Open Access)
Sistema inteligente de suporte a análise da qualidade da energia elétrica em regime permanente
(Universidade Federal do Pará, 2017-02-21) ROCHA, Gabriel Vianna Soares; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148
This work presents the development of software that provides a computational environment so that the user can carry out analyzes of Quality of Eletrical Energy (QEE) following the rules stipulated by the National Eletrical Power Agency (ANEEL) through the Distribution Procedures (PRODIST). Also it is possible to do analysis of contribution of impacts caused by the injection of harmonics in the electric network, pointing out the possible percentage shares of contribution of each Consumer Unit (UC), through modules that perform a sensitivity study through Computational Intelligence (CI) techniques as Artificial Neural Network (ANN) Regression Trees (RT) and Simple Linear Regression (LR). For the construction of the models are used time series data of current and voltage harmonics that were obtained through measurement campaigns.