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| Registros recuperados: 122 | |
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| Fialho,Filipe Ton; Villela,Severino Delmar Junqueira; Leonel,Fernando de Paula; Tamy,Wagner Pessanha; Araujo,Raphael Pavesi; Machado,Henrique Valentim Nunes. |
| The objective was to study the kinetics of transit and degradation of the fiber from guinea grass and the waste from soybean pre-cleaning (WSPC), ensiled with different proportions of mass (0, 100, 150, and 200 g WSPC/kg total mass). Four crossbred (Gyr × Holstein), fistulated cattle with an average body mass of 400±50 kg were organized in a 4 × 4 Latin square experimental design. The fiber utilized in the study of the transit kinetics was stained with chromium mordant, whereas the in situ technique was adopted for the degradation kinetics. The level of inclusion of WSPC only affected the true digestibility and the mean retention time. The addition of waste from soybean pre-cleaning to the silage of guinea grass is beneficial, in terms of kinetics of... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: By-product; Mathematical models; Mean retention time; True digestibility. |
| Ano: 2015 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-35982015000600201 |
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| Galeano-Vasco,Luis Fernando; Cerón-Muñoz,Mario Fernando; Narváez-Solarte,William. |
| In this study, the Von Bertalanffy, Richards, Gompertz, Brody, and Logistics non-linear mixed regression models were compared for their ability to estimate the growth curve in commercial laying hens. Data were obtained from 100 Lohmann LSL layers. The animals were identified and then weighed weekly from day 20 after hatch until they were 553 days of age. All the nonlinear models used were transformed into mixed models by the inclusion of random parameters. Accuracy of the models was determined by the Akaike and Bayesian information criteria (AIC and BIC, respectively), and the correlation values. According to AIC, BIC, and correlation values, the best fit for modeling the growth curve of the birds was obtained with Gompertz, followed by Richards, and then... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Chickens; Mathematical models; Poultry; Regression analysis; Weight gain. |
| Ano: 2014 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-35982014001100573 |
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| Siqueira,Valdiney Cambuy; Resende,Osvaldo; Chaves,Tarcísio Honório. |
| The jatropha has emerged on the world scene as a promising plant for the production of biodiesel. However, this crop still lacks the development of specific equipment for its processing, particularly post-harvest. Therefore, the aim of this work was to fit different mathematical models to experimental data obtained while drying jatropha fruits, and to recommend the one that best represents the facts. Jatropha fruit with a moisture content of 4.4 (kg moisture kg-1 dry matter) were subjected to drying in a greenhouse with forced air-ventilation at five temperature conditions: 45; 60; 75; 90 and 10 ºC and relative humidities of 14.5; 7.4; 3.8; 2.2 and 1.4%, respectively, until reaching a moisture content of 0.10 ± 0.005 (kg moisture kg-1 dry matter),with... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Biodiesel; Drying temperatures; Mathematical models. |
| Ano: 2013 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1806-66902013000200009 |
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| Levins,Richard; Miranda,Ileana. |
| In the present work, the models of dynamics ecological populations were described. The development of the models, in order to describe these populations was presented. They have evolved from an independent way to the models that represent the evaluation of epidemiology in humans. The differential equations that describe the relationships prey-predator, crop-pest and migration effect were shown. It was also described the possibility to represent these models by means of equations in difference and computerized simulation systems. The interconnection between a mathematical model and the ecosystem stability according to the biological parameters was showed. Ecological questions that can be answered analyzing the models were approached. |
| Tipo: Journal article |
Palavras-chave: Mathematical models; Prey; Predator; Migration; Ecosystem. |
| Ano: 2007 |
URL: http://scielo.sld.cu/scielo.php?script=sci_arttext&pid=S1010-27522007000100001 |
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| Siqueira, Valdiney Cambuy; Universidade Federal de Lavras; Resende, Osvaldo; Instituto Federal de Educação, Ciência e Tecnologia Goiano - Campus Rio Verde; Chaves, Tarcísio Honório; Instituto Federal de Educação, Ciência e Tecnologia Goiano - Campus Rio Verde. |
| The objective of this study was to determine the geometric diameter of volumetric shrinkage in Jatropha seeds subjected to drying under six air conditions and to fit different mathematical models to the experimental values. Seeds with an approximate initial moisture content of 0.61 kgw kgdm-1 (kilogram of water per kilogram of dry matter) were dried in a convection oven at temperatures of 36, 45, 60, 75, 90, and 105°C until they reached a moisture content of 0.11 ± 0.006 kgw kgdm-1. The experimental data were fitted to five mathematical models used to represent volumetric shrinkage in agricultural products. The models were analyzed using the coefficient of determination, chi-square, mean relative error, mean estimated error, and residual distribution.... |
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Palavras-chave: Mathematical models; Moisture content; Polynomial model. |
| Ano: 2012 |
URL: http://periodicos.uem.br/ojs/index.php/ActaSciAgron/article/view/14402 |
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| Moretti de Souza, Jorge Luiz; de Oliveira, Cibelle Tamiris; Kreutz Rosa, Stefanie Lais; Yoiti Tsukahara, Rodrigo. |
| Crop growth models are abstract tools that represent a real system, being a simple and important technology to develop studies aiming to improve the yields of the most agricultural crops, like the maize in Brazil. The objective of this study was to analyze the sensitivity of the main AquaCrop model input parameters, as well as their responses in maize yield estimation, in Parana State, Southern Brazil. The analyses were performed with the genotype 30R50YH, 2014/15 harvest, planted on April 11, 2014. The parameters analyzed refer to crop, soil and soil management. The parameters were modified individually, maintaining the others fixed. With the results, the Sensitivity Index (SI) was calculated, which allowed the identification of the most sensitive... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Modeling; Mathematical models; Sensitivity analysis; Maize; Zea mays. |
| Ano: 2022 |
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/7541 |
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| Sheremeta, Roman; Kuzminskyj, Roman. |
| Dimensions of 100 randomly selected coffee beans of the Arabica and Robusta variety were determined by measuring their length (l), width (b) and thickness (h). The results of the measurements were processed by the methods of mathematical statistics. Parameters of distributions of separate sizes as random variables are determined. By the value of the coefficient of variation, the density function of normal distribution (Gaussian distribution) is taken as a model of separate sizes of beans. Models of two-dimensional distributions of beans sizes as independent random variables are presented. The coefficients of correlation between the geometric sizes of beans are calculated. The obtained values of the correlation coefficients indicate that the geometric sizes... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Coffee beans; Geometric parameters; Mathematical models; Distribution function. |
| Ano: 2019 |
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/5018 |
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| FERNANDES,FRANCISCO S.; GODOY,WESLEY A.C.; RAMALHO,FRANCISCO S.; GARCIA,ADRIANO G.; SANTOS,BÁRBARA D.B.; MALAQUIAS,JOSÉ B.. |
| ABSTRACT Population dynamics of aphids have been studied in sole and intercropping systems. These studies have required the use of more precise analytical tools in order to better understand patterns in quantitative data. Mathematical models are among the most important tools to explain the dynamics of insect populations. This study investigated the population dynamics of aphids Aphis gossypii and Aphis craccivora over time, using mathematical models composed of a set of differential equations as a helpful analytical tool to understand the population dynamics of aphids in arrangements of cotton and cowpea. The treatments were sole cotton, sole cowpea, and three arrangements of cotton intercropped with cowpea (t1, t2 and t3). The plants were infested with... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Aphids; Cotton; Cowpea; Dynamics; Mathematical models. |
| Ano: 2018 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652018000100311 |
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| CARVALHO,JULIANA O. DE; TOEBE,MARCOS; TARTAGLIA,FRANCIELI L.; BANDEIRA,CIRINEU T.; TAMBARA,ANDRÉ L.. |
| ABSTRACT The goal of this study was to estimate the leaf area of Crotalaria juncea according to the linear dimensions of leaves from different ages. Two experiments were conducted with C. juncea cultivar IAC-KR1, in the 2014/2015 sowing seasons. At 59, 82, 102, 129 days after sowing (DAS) of the first and 61, 80, 92, 104 DAS of the second experiment, 500 leaves were collected, totaling 4,000 leaves. In each leaf, the linear dimensions were measured (length, width, length/width ratio and length × width product) and the specific leaf area was determined through Digimizer and Sigma Scan Pro software, after scanning images. Then, 3,200 leaves were randomly separated to generate mathematical models of leaf area (Y) in function of linear dimension (x), and 800... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Non-destructive method; Image processing; Mathematical models; Model validation. |
| Ano: 2017 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652017000401851 |
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| Gerrard,Andrew Mark; Havranek,Josef; Novak,Vratislav; Halecky,Martin; Jones,Kim; Soccol,Carlos Ricardo; Paca,Jan. |
| The aim of this work was the study a trickling biofilter, where water was circulated throughout the bed. In the first steady state experiment, the packing materials used were 25mm Pall rings. The airflow rate was increased gradually and the concentration of styrene in the air stream was held constant. In the second experiment, 15mm Pall rings were used. In this case, the feed contained both styrene and a small amount of acetone. The concentration of acetone and the air flow rate were kept constant, but the styrene inlet concentration was increased. The concentrations were measured at the input, and also at an intermediate and the outlet position in the biotrickling filter to determine the concentration profile along the reactor. Using the values of... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Biotrickling filter; Steady state; Unsteady state; Mathematical models; Styrene; Acetone. |
| Ano: 2010 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132010000500028 |
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| Lazzaretti,Bruno Pedro; Silva,Leandro Souza da; Drescher,Gerson Laerson; Dotto,André Carnieletto; Britzke,Darines; Nörnberg,José Laerte. |
| ABSTRACT: Among the soil constituents, special attention is given to soil organic matter (SOM) and clay contents, since, among other aspects, they are key factors to nutrient retention and soil aggregates formation, which directly affect the crop production potential. The methods commonly used for the quantification of these constituents have some disadvantages, such as the use of chemical reactants and waste generation. An alternative to these methods is the near-infrared spectroscopy (NIRS) technique. The aim of this research is to evaluate models for SOM and clay quantification in soil samples using spectral data by NIRS. A set (n = 400) of soil samples previously analyzed by traditional methods were used to generate a NIRS calibration curve. The clay... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Calibration; Validation; Mathematical models; Spectral pretreatment.. |
| Ano: 2020 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-84782020000100251 |
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| Toebe,Marcos; Souza,Rafael Rodrigues de; Mello,Anderson Chuquel; Melo,Patrícia Jesus de; Segatto,Alexandre; Castanha,Ana Carla. |
| ABSTRACT: The objectives of this work were estimate the leaf area of squash ‘Brasileirinha’ by linear dimensions of the leaves and check models available in the literature. An experiment was conducted in the 2015/16 sowing season. Were collected 500 leaves and in each one, were measured the length (L), width (W) and length×width product (LW) and determined the real leaf area (LA). Then, 400 leaves were separated to generate models of the leaf area (LA) as a function of linear dimension (L, W or LW) of squash. The remaining 100 leaves were used for the validation of models. A second experiment was conducted in the 2016/17 sowing season. Were collected 250 leaves, used only for the validation of the models of the first experiment. There is collinearity... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Cucurbita moschata; Image processing; Non-destructive method; Mathematical models. |
| Ano: 2019 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-84782019000400203 |
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| Lima,Máida Cynthia Duca de; Barreto-Garcia,Patrícia Anjos Bittencourt; Sanquetta,Carlos Roberto; Novaes,Adalberto Brito de; Melo,Lara Clímaco de. |
| ABSTRACT: There is a large number of studies evaluating methods to quantify biomass for the genus Pinus in different regions of Brazil. However, knowledge about this subject in the Northeast region of Brazil is still incipient. The objective of the present study was to assess the biomass and carbon stocks and select mathematical models to estimate these variables in Pinus caribaea var. hondurensis , which is established in homogenous stands in the Southwest region of the state of Bahia (Brazil). The biomass was quantified using the destructive method. Samples of needles, bole, bark, and branches were analyzed to determine their carbon contents. Ten models were tested, and the best of them were chosen based on the following statistical indicators: adjusted... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Exotic forest species; Mathematical models; Biomass. |
| Ano: 2016 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-84782016000600957 |
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| Registros recuperados: 122 | |
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