Granma, Cuba
Granma, Cuba

The University of Granma is a university located in Bayamo, Cuba. Wikipedia.

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Frias-Blanco I.,University of Granma | Del Campo-Avila J.,University of Malaga | Ramos-Jimenez G.,University of Malaga | Morales-Bueno R.,University of Malaga | And 2 more authors.
IEEE Transactions on Knowledge and Data Engineering | Year: 2015

Incremental and online learning algorithms are more relevant in the data mining context because of the increasing necessity to process data streams. In this context, the target function may change over time, an inherent problem of online learning (known as concept drift). In order to handle concept drift regardless of the learning model, we propose new methods to monitor the performance metrics measured during the learning process, to trigger drift signals when a significant variation has been detected. To monitor this performance, we apply some probability inequalities that assume only independent, univariate and bounded random variables to obtain theoretical guarantees for the detection of such distributional changes. Some common restrictions for the online change detection as well as relevant types of change (abrupt and gradual) are considered. Two main approaches are proposed, the first one involves moving averages and is more suitable to detect abrupt changes. The second one follows a widespread intuitive idea to deal with gradual changes using weighted moving averages. The simplicity of the proposed methods, together with the computational efficiency make them very advantageous. We use a Naïve Bayes classifier and a Perceptron to evaluate the performance of the methods over synthetic and real data. © 1989-2012 IEEE.

Ghanbarian-Alavijeh B.,University of Tehran | Ghanbarian-Alavijeh B.,Wright State University | Millan H.,University of Granma | Huang G.,China Agricultural University
Canadian Journal of Soil Science | Year: 2011

The soil water retention curve is an important hydraulic parameter for characterizing water flow and contaminant transport in porous media. Therefore, many empirical, semi physical, and physical models of the soil water retention curve have been proposed. Among them, fractal models appear to be a useful approach for modeling soil as a heterogeneous porous medium and its hydraulic characteristics. Fractal models are mathematically based, and their parameters have physical meanings. In this study, we review published fractal, prefractal and pore-solid-fractal models for soil water retention curves including Tyler and Wheatcraft, Rieu and Sposito, Perrier et al., Perfect, Bird et al., Millán and González-Posada, and Cihan et al. models. In the pore-solid fractal (PSF) approach the pore phase and matrix phase have a finite volume even for an infinite number of iterations. The results of fitting the PSF model to measured soil water retention data indicate that this model works well, particularly at lower water contents.

Silva E.B.D.,Federal University of Goais | Silva B.D.D.S.,Federal University of Goais | Leon J.R.R.,University of Granma | Kipnis A.,Federal University of Goais | And 2 more authors.
Veterinary Journal | Year: 2011

This study evaluated the Mycobacterium tuberculosis protein antigen MPT-51, the trimeric antigen 85 (Ag85) complex, and Bacillus Calmette-Guérin (BCG) in an indirect ELISA to diagnose bovine tuberculosis (TB) from serum samples. Serum was collected from 208 intra-dermal tuberculin test (ITT)-positive and 54 ITT-negative animals from a region where bovine TB is endemic. Using the Ag85 and BCG antigens, the indirect ELISA was able to discriminate ITT-positive from ITT-negative animals. This level of discrimination was not achieved when using the MPT-51 antigen. The highest sensitivity (Se) and specificity (Sp) of the test was found when BCG was used (Se, 82%; Sp, 91%). Further work in different epidemiological settings and with larger numbers of animals will be required to validate these findings. © 2009 Elsevier Ltd.

Govea-Alcaide E.,University of Granma | Machado I.F.,University of Sao Paulo | Jardim R.F.,University of Sao Paulo
Journal of Applied Physics | Year: 2015

Pre-reacted powders of (Bi-Pb)2Sr2Ca2Cu3O10+ δ (Bi-2223) were consolidated by using the spark plasma sintering (SPS) technique under vacuum and at two different temperatures TD: 750 and 830 °C. The results indicate the occurrence of grains with core-shell morphology, where the shell is oxygen deficient. A post-annealing heat treatment (PAHT), performed in air, at 750 °C, and for a brief time interval, is responsible for a 10 to 25-fold increase in the transport superconducting current density at 77 K. The role of the oxygen-deficient shell, before and after the PAHT, was investigated by means of magnetic and transport measurements. We argue that the PAHT is two folds: (i) it is responsible for the decrease of the width of the oxygen-deficient shell, then increasing the oxygen content along the grain boundaries; (ii) it promotes the formation of conduction current paths along the grain boundaries of the SPS material. © 2015 AIP Publishing LLC.

Govea-Alcaide E.,University of Granma | MacHado I.F.,University of Sao Paulo | Torikachvili M.S.,San Diego State University | Dilley N.R.,Quantum Engineering Design, Inc. | Jardim R.F.,University of Sao Paulo
Journal of Physics: Conference Series | Year: 2014

Pre-reacted powders of (Bi-Pb)2Sr2Ca 2Cu3O10+δ (Bi-2223) were consolidated by using the spark plasma sintering (SPS) technique under vacuum and at different consolidated temperatures TD. We have found that the transport properties of SPS samples depend on their oxygen content because the SPS process is performed under vacuum. From these results we have inferred that SPS samples are oxygen deficient and that a post-annealing treatment, performed in air for a brief time interval, is needed to restore such a deficiency. Measurements of temperature dependence of the thermal conductivity, κ(T), were performed in all SPS samples including a reference sample sintered at 845 °C in air. The results indicate that the electronic contribution to the thermal conductivity in all samples is very low. Values of κ were found to be higher in SPS samples mostly because of their high volume density of ∼ 5.7 g/cm3. We have also performed measurements of the critical current density as a function of the applied magnetic field, Jc(B a). All samples display a clear Josephson-like behavior and low values of the superconducting critical current density at zero applied magnetic field. The experimental results indicate that the oxygen deficiency in SPS samples is marked near the grain boundaries. This suggests the occurrence of grains with core-shell morphology, where the width of the shell is consolidation temperature dependent. © Published under licence by IOP Publishing Ltd.

Millan H.,University of Granma | Ghanbarian-Alavijeh B.,University of Tehran | Garcia-Fornaris I.,University of Granma
Atmospheric Research | Year: 2010

Chaos theory and its applications are at the cutting edge of investigations in environmental sciences (e.g. Environmental Physics, Biometeorology and Atmospheric Sciences among many others). However, we still need to take advantage of some recent computational efforts for nonlinear investigations of empirical meteorological variables. The objectives of this work were (i) to quantify the nonlinear variability of observed time series of mean daily temperature and dewpoint records collected at Babolsar, Iran and (ii) to stimulate the use of recent computational tools for investigating environmental data. Positive Lyapunov exponents were found for both time series (λmax=0.0174 and λmax=0.0169 for mean daily air temperature and dewpoint temperature, respectively). In addition, determinism tests showed that both time series masked strong determinist components (|→k|=0.721 and |→k|=0.693 for mean daily temperature and dewpoint, respectively). That nonlinear test could be of use in future research for making decisions in applying deterministic, stochastic or combinations of both models with climate data. There were found interesting evidences on the existence of empirical attractors in univariate climate time series as expressed by reconstructing both phase spaces. © 2010 Elsevier B.V.

Ghanbarian-Alavijeh B.,University of Tehran | Ghanbarian-Alavijeh B.,Wright State University | Millan H.,University of Granma
International Agrophysics | Year: 2010

Soil water retention curve (SWRC) is one of the most important soil hydraulic properties, whose estimation is still under consideration. In this study, we used 315 soil samples from the UNSODA database to develop three models of point pedotransfer functions (PTFs) and to verify them. We also used an independent database, GRIZZLY, with 59 samples, to verify the developed point PTFs and to compare them with the Rosetta model. Multiple linear regression and stepwise methods were used to derive pedotransfer functions. In the first model, soil texture data ie sand, silt, and clay content, geometric mean particle-size diameter and geometric standard deviation as well as bulk density were used to develop point PTFs at 10 matric potentials. In the second model, water content at field capacity, and in the third model water content at field capacity and permanent wilting point were also used for developing PTFs at 9 and 8 matric potentials, respectively. To evaluate the accuracy and reliability of the point PTFs, we used crossvalidation eg repeated random splitting of the data set into subsets for development and validation. The calculated RMSE values showed that all three developed point PTFs estimated soil water retention curve better than the Rosetta model. © 2010 Institute of Agrophysics, Polish Academy of Sciences.

Millan H.,University of Granma | Tarquis A.M.,Technical University of Madrid | Perez L.D.,University of Granma | Mato J.,University of Granma | Gonzalez-Posada M.,University of Granma
Soil and Tillage Research | Year: 2012

Spatial variability of Vertisol properties is relevant for identifying those zones with physical degradation. In this sense, one has to face the problem of identifying the origin and distribution of spatial variability patterns. The objectives of the present work were (i) to quantify the spatial structure of different physical properties collected from a Vertisol, (ii) to search for potential correlations between different spatial patterns and (iii) to identify relevant components through multivariate spatial analysis. The study was conducted on a Vertisol (Typic Hapludert) dedicated to sugarcane (Saccharum officinarum L.) production during the last sixty years. We used six soil properties collected from a squared grid (225 points) (penetrometer resistance (PR), total porosity, fragmentation dimension (D f), vertical electrical conductivity (ECv), horizontal electrical conductivity (ECh) and soil water content (WC)). All the original data sets were z-transformed before geostatistical analysis. Three different types of semivariogram models were necessary for fitting individual experimental semivariograms. This suggests the different natures of spatial variability patterns. Soil water content rendered the largest nugget effect (C 0=0.933) while soil total porosity showed the largest range of spatial correlation (A=43.92m). The bivariate geostatistical analysis also rendered significant cross-semivariance between different paired soil properties. However, four different semivariogram models were required in that case. This indicates an underlying co-regionalization between different soil properties, which is of interest for delineating management zones within sugarcane fields. Cross-semivariograms showed larger correlation ranges than individual, univariate, semivariograms (A≥29m). All the findings were supported by multivariate spatial analysis, which showed the influence of soil tillage operations, harvesting machinery and irrigation water distribution on the status of the investigated area. © 2011 Elsevier B.V..

An interpretive methodological approach and elements of the research-action method were used in this research that shows the results of a study made with a group of families from Bayamo city which have a five years old or younger child with Down Syndrome (DS), with the objective of characterizing the significance of their birth. A purposeful and intensive, typical case sampling was chosen; 14 fathers and mothers were interviewed, 10 of them participated in the sessions of a Formative Group, guided by one coordinator and two observers, supervised by an expert in the planning, implementation and analysis of the intervention. The emergent topics detected aimed to the significance that has in the family the birth of a Down syndrome child; in the Formative Group some of these aspects and the difficulties in the functioning of the family were approached; the group reflection facilitated the incorporation of new analysis, cognitive and affective elements for the initiation of change processes in these families. Diagnostic Indicators of population, which according to their diagnostic and predictive importance, can be used in the design of other similar programs for community intervention linked to the Primary Health Care, Education, Community Extension among other, were identified, which is one of the most important value of this research.

Perez L.D.,University of Granma | Millan H.,University of Granma | Gonzalez-Posada M.,University of Granma
Soil and Tillage Research | Year: 2010

Sugarcane is one important crop for many Third World countries. Soils dedicated to sugarcane are usually compacted during the harvesting process. The main objective of the present work was to search for prefractal scaling patterns of soil compaction before and after sugarcane harvest. We used descriptive statistics and prefractal analysis with experimental semivariograms for characterizing the spatial patterns of soil penetrometer resistance distributions. The soil is a Vertisol (Typic Hapludert) dedicated to sugarcane production during the last 60 years. Approximately 50% of soil resistance values were over 2.5 MPa after sugarcane harvest. This could restrict sugarcane shoot emergence. A power-law (prefractal) model fitted experimental semivariograms fairly well except for those distributions corresponding to 2.5-5.0 cm soil depth. Those particular distributions could be fitted by any standard geostatistical model. The main findings were (i) scaling exponents larger than 1.5 which indicate anti-persistence and (ii) change of anisotropic directions after sugarcane harvest. The range of prefractal behaviour was approximately 105m before harvest and 93. m after crop harvest. The spatial structure of some soil physical or mechanical properties connected to soil compaction can resemble those patterns. The combination of Geostatistics and prefractal analysis can assist the mechanized agriculture and scientists through a previous identification of degraded zones within the field and the physical processes involved in the formation of those local areas. © 2010 Elsevier B.V.

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