São João Evangelista, Brazil
São João Evangelista, Brazil

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Cabacinha C.D.,Federal University of Minas Gerais | Lafeta B.O.,Instituto Federal Of Minas Gerais
Ciencia Florestal | Year: 2017

This study aimed to evaluate the predictive efficiency of Shannon index (H’) and Pielou Equitability index (J) in forest fragments from the Brazilian Cerrado biome, from the vegetation indices and landscape metrics using artificial neural networks (ANN). Feedforward networks were used and they were trained through a back propagation error algorithm. The variables used as ANN input for simultaneous estimation of indices were: the categorical (H’ and J) and the numbers related to the mean and standard deviation of vegetation indices (NDVI, SAVI, EVI, and MVI5, MVI7) and landscape metrics (AREA, GYRATE, SHAPE, CONTIG, CORE and ENN). It was generated five models of ANN from the functional relationships between numerical variables inherent to vegetation indices in two seasons, a dry season (June) and a rainy season (February). The architecture of the networks was the Multilayer Perceptron (MLP), to estimate simultaneously the H’ and J: 500 using vegetation indices in the wet season (100 for each vegetation index) and 500 in dry (100 for each vegetation index). The precision, accuracy and realism of biological ANN were assessed. The nets built during the rainy season and dry season that used vegetation indices MVI5 (Moisture Vegetation Index) and SAVI (Soil Adjusted Vegetation Index), respectively, were more appropriate, accurate and biologically realistic to estimate both indices H’ and J. The ANN modeling demonstrated to be adequate to estimate the diversity index. © 2017, Universidade Federal de Santa Maria. All rights reserved.

Camargos A.F.P.,Instituto Federal Of Minas Gerais | Camargos A.F.P.,University of Sao Paulo | Silva V.C.,University of Sao Paulo | Guichon J.-M.,CNRS Grenoble Electrical Engineering Lab | Meunier G.,CNRS Grenoble Electrical Engineering Lab
International Journal of High Performance Computing Applications | Year: 2017

We present a performance analysis of a parallel implementation for both preconditioned conjugate gradient and preconditioned bi-conjugate gradient solvers running on graphic processing units (GPUs) with CUDA programming model. The solvers were mainly optimized for the solution of sparse systems of algebraic equations at complex entries, arising from the three-dimensional edge-finite element analysis of the electromagnetic phenomena involved in the open-bound earth diffusion of currents under time-harmonic excitation. We used a shifted incomplete Cholesky (IC) factorization as preconditioner. Results show a significant speedup by using either a single-GPU or a multi-GPU device, compared to a serial central processing unit (CPU) implementation, thereby allowing the simulations of large-scale problems in low-cost personal computers. Additional experiments of the optimized solvers show that its use can be extended successfully to other complex systems of equations arising in electrical engineering, such as those obtained in power-system analysis. © SAGE Publications.

da Silveira F.G.,Instituto Federal Of Minas Gerais | Silva F.F.E.,Federal University of Viçosa | Malhado P.L.S.C.,State University of Southwest Bahia
Revista Brasileira de Saude e Producao Animal | Year: 2012

The main objective of this work was to use the cluster analysis in order to classify nonlinear growth models in relation to different quality fit evaluators when data from the following lambs genetic groups were utilized: Dorper x Morada Nova, Dorper x Rabo Largo e Dorper x Santa Inês. After the choice of the best model, it was also aimed to apply the identity model test in order to identify the most efficient genetic group. The proposed methodology was applied to data of all animals from each group regarding twelve nonlinear models, whose fit quality was measured by determination coefficient, Akaike information criterion, Bayesian information criterion, mean quadratic error of prediction, predicted determination coefficient and convergence percentual. The cluster analysis indicated the von Bertalanffy as the best model for the three data sets. The model identity tests revealed that the Dorper x Santa Inês group presented higher adult weight, therefore this group is recommend for meat production.

Silva C.D.,Federal University of Viçosa | Cerqueira M.S.,Federal University of Viçosa | Moreira D.G.,Instituto Federal Of Minas Gerais | Marins J.C.B.,Federal University of Viçosa
Revista Andaluza de Medicina del Deporte | Year: 2013

Objective. To verify the reliability of maximal heart rate obtained (MHRobt) in official soccer games and to compare it with calculated by equations (MHRpre). Method. The study included 18 soccer players (14 ± 0.6 years, 174 ± 6 cm, 62 ± 6 kg) participant of a Brazilian state championship in U-15 category. The equations were selected [MHR = age-220]; Tanaka et al. [MHR = 208 - (0.7*age)] and Nes et al. [MHR=211 - (0.64*age)] for comparison with MHR obt in competition. Results. Bland-Altman analyze showed good agreement of MHRobt and the CV (1 %) and ICC (0.95 [0.86 - 0.98]) show good reliability of the inter matches. The MHRobt (202 ± 8 bpm) was lower than 220 - age equation (205 ± 1 bpm; P < 0.05) and higher than Tanaka et al. (198 ± 0.4; P < 0.05), with no difference to the Nes et al. equation (202 ± 0.5 bpm) (P > 0.05). Conclusion. MHRobt there is good reliability between soccer matches in competition and it is recommended to use the Nes et al. [MHR = 211 - (0.64 * age)] equation to MHRpre in young soccer players. © 2013 Revista Andaluza de Medicina del Deporte.

Pinho D.S.,Instituto Brasileiro Of Meio Ambiente E Recursos Naturais Renovaveis | de Lima e Borges E.E.,Federal University of Viçosa | Pontes C.A.,Instituto Federal Of Minas Gerais
Revista Arvore | Year: 2010

The aim of this experiment was to evaluate the effect of the accelerated aging in the vigor and viability of Anadenanthera peregrina seeds. For the accelerated aging test, the seeds were conditioned in "gerbox" boxes with an aluminum screen separating the seeds from the bottom of the box. Distilled water was added into the bottom and, after that, the boxes were conditioned in aging chambers under temperatures of 40, 50 and 60°C, during periods of 24, 48, 72 and 96 hours. Seeds not submitted to the aging process were used as the control. After each period the seeds were submitted to the following tests: standard germination test, germination speed index, electric conductivity, tetrazolium test, osmopriming and seedling evaluation. Under 40°C, the percentage of germination, the IVG and the percentage of viable seeds for the tetrazolium test decreased significantly. A significant increase in the electric conductivity curve was noticed, as the period in the aging chamber increased. The seeds lost all their viability when submitted to the aging chamber from periods longer than 96 hours, as well as those submitted to temperatures of 50° and 60°C. In the seedling evaluation, all the parameters analyzed decreased as the seeds stayed in the aging chamber for longer periods, except the percentage of abnormal seedlings and the cool weight of the root, which both increased.

Camargos A.F.P.,Instituto Federal Of Minas Gerais | Camargos A.F.P.,University of Sao Paulo | Silva V.C.,University of Sao Paulo | Guichon J.-M.,CNRS Grenoble Electrical Engineering Lab | Meunier G.,CNRS Grenoble Electrical Engineering Lab
Proceedings - 2014 22nd Euromicro International Conference on Parallel, Distributed, and Network-Based Processing, PDP 2014 | Year: 2014

We present a performance analysis of a parallel implementation to both preconditioned Conjugate Gradient and preconditioned Bi-conjugate Gradient solvers using graphic processing units with CUDA programming model. The solvers were optimized for the solution of sparse systems of equations arising from Finite Element Analysis of electromagnetic phenomena involved in the diffusion of underground currents under time-harmonic current excitation. We used a shifted Incomplete Cholesky factorization as preconditioner. Results show a significant speedup by using the GPU compared to a serial CPU implementation. © 2014 IEEE.

Rodrigues Filho F.A.,Federal University of Minas Gerais | Moreira T.A.A.,Instituto Federal Of Minas Gerais | Valle R.M.,Federal University of Minas Gerais | Baeta J.G.C.,Federal University of Minas Gerais | And 2 more authors.
Energy Conversion and Management | Year: 2016

Vehicular emissions significantly increase atmospheric air pollution and the greenhouse effect. This fact associated with the fast growth of the global motor vehicle fleet demands technological solutions from the scientific community in order to achieve a decrease in fuel consumption and CO2 emission, especially of fossil fuels to comply with future legislation. To meet this goal, a prototype stratified torch ignition engine was designed from a commercial baseline engine. In this system, the combustion starts in a pre-combustion chamber where the pressure increase pushes the combustion jet flames through a calibrated nozzle to be precisely targeted into the main chamber. These combustion jet flames are endowed with high thermal and kinetic energy being able to promote a stable lean combustion process. The high kinetic and thermal energy of the combustion jet flame results from the load stratification. This is carried out through direct fuel injection in the pre-combustion chamber by means of a prototype gasoline direct injector (GDI) developed for low fuel flow rate. During the compression stroke, lean mixture coming from the main chamber is forced into the pre-combustion chamber and, a few degrees before the spark timing, fuel is injected into the pre-combustion chamber aiming at forming a slightly rich mixture cloud around the spark plug which is suitable for the ignition and kernel development. The performance of the torch ignition engine running with E25 is presented for different mixture stratification levels, engine speed and load. The performance data such as combustion phasing, specific fuel consumption, thermal efficiency and the specific emissions of CO2 are carefully analyzed and discussed in this paper. The results obtained in this work show a significant increase in the torch ignition engine's performance in comparison with the baseline engine which was used as a workhorse for the prototype engine construction. © 2016 Elsevier Ltd. All rights reserved.

Filho R.M.,Instituto Federal Of Minas Gerais | Filho R.M.,Federal University of Minas Gerais | Almeida J.M.,Federal University of Minas Gerais | Pappa G.L.,Federal University of Minas Gerais
Proceedings of the 2015 IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining, ASONAM 2015 | Year: 2015

In the past years a lot of effort has been spent analyzing online social network data to understand how the world reality is reflected in the "virtual" world. Twitter is by far the network most used in these studies, given its policy of public data availability. However, a big discussion is still on on whether the data available is enough to make user characterization or event outcomes prediction, and what are the pitfalls people do not usually account for. In this direction, we propose a new methodology for drawing representative samples from Twitter data, which is divided into four phases: (i) user filtering, (ii) user demographic characterization, (iii) user sampling, and (iv) event prediction. The methodology is tested into a common scenario in Twitter event outcome prediction: elections. The methodology was tested with municipality elections from six different Brazilian cities, and compared to official election results. Results show it is worth further investigating the topic, but that a very hight number of messages is required to match real data distributions. © 2015 ACM.

Vaz C.T.,Federal University of Minas Gerais | Bracarense A.Q.,Federal University of Minas Gerais | Felizardo I.,ELBRAS Inc. | Pereira Pessoa E.C.,Instituto Federal Of Minas Gerais
Journal of Materials Research and Technology | Year: 2012

This paper evaluates the weld metal microstructure and properties of low hydrogen covered electrodes where the usual binders (potassium and sodium silicates) were replaced by polymers. The impermeable covered electrode was produced using the commercial E7018 formula. Preliminary tests with different polymers and formulation changes were realized to meet the satisfactory weld ability. The best covered electrode at the first stage was evaluated at the second stage. Weld metal diffusible hydrogen, microstructure and mechanical properties were evaluated and compared with traditional low hydrogen covered electrodes. In addition, it were made tests to evaluate the slag and fumes generated during the welding. The impermeable covered electrode diffusible hydrogen content was less than 4 mL/100 g of weld metal. This is very low if compared to conventional low hydrogen covered electrodes. Additional hydrogen tests were made after covered electrode moisture exposure under several conditions and confirm the coating resistance. The impermeable covered electrode weld metal showed the same morphology and typical microstructure of weld metal produced by the E7018 low hydrogen covered electrode. However, the acicular ferrite volume was significantly higher when compared with E7018 covered electrode. Weld metal tensile and yield strength, elongation and toughness (Charpy V-notch test) overcome the E7018 low hydrogen covered electrodes properties. The slag analysis showed the strongly polymer influence. © 2012 Elsevier Editora Ltda. and Brazilian Metallurgical, Materials and Mining Association.

Freitas A.M.S.,Federal University of Ouro Preto | Souza F.T.,Instituto Federal Of Minas Gerais | Freitas M.S.R.,Federal University of Ouro Preto
Thin-Walled Structures | Year: 2010

This work presents a general analysis of drive-in racks, evaluating the influence of each of their components on global stability. In this study, a full-scale test of a drive-in system was carried out. Finite element models were also developed to evaluate global structural stability and component influence on system behavior. The experimental and numerical results show that the connections and base plates have the most significant influence on the system's behavior. This influence is analyzed, an equation that predicts base plate resistance is then proposed, and its results are compared with experimental and numerical results. © 2009 Elsevier Ltd. All rights reserved.

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