|
|
|
| Registros recuperados: 47 | |
|
|
| Souza,Jéssica L. F.; Oliveira,Daniel E. C.; Plácido,Geovana R.; Egea,Mariana B.; Caliari,Márcio; Silva,Marco A. P. da. |
| ABSTRACT The objectives of this study were to fit mathematical models to the experimental data of the drying of the pequi mesocarp, determine the effective diffusion coefficient, and to obtain activation energy and thermodynamic and nutritional properties in different drying conditions. The mesocarp of pequi fruits, with an initial moisture content of 5.05 (decimal, dry basis), was dried in a forced ventilation oven at temperatures of 40, 50, 60 and 70 °C until the final moisture content of 0.15 ± 0.01 (decimal, dry basis). The mathematical models were adjusted by non-linear regression analysis using the Gauss-Newton method, considering the magnitude of the coefficient of determination (R2), the mean relative error (P) and the estimated mean error (SE).... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Mathematical modeling; Activation energy; Midilli model; By-product utilization. |
| Ano: 2019 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662019000900655 |
| |
|
|
| Zeymer,Juliana S.; Corrêa,Paulo C.; Oliveira,Gabriel H. H. de; Baptestini,Fernanda M.; Freitas,Rita C. P.. |
| ABSTRACT Lactuca sativa seeds are highly sensitive to climate conditions; thus, they should be stored securely to maintain their qualitative and quantitative characteristics. Studies on hygroscopicity aim to decrease possible changes in agricultural products under specific environmental conditions. Accordingly, this study aims to develop an appropriate mathematical model to represent the desorption isotherms of Lactuca sativa seeds. The hygroscopic equilibrium was achieved using a static-gravimetric method at temperatures of 10, 20, 30, 40 and 50 °C and water activity in the range 0.11-0.96. Six mathematical models were fitted to the experimental data of the equilibrium moisture content of Lactuca sativa seeds. The best model was chosen based on the... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Mathematical modeling; Hygroscopic equilibrium; Relative humidity; Temperature. |
| Ano: 2017 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662017000800568 |
| |
|
| |
|
|
| Botelho,Fernando M.; Boschiroli Neto,Nilso J.; Botelho,Silvia de C. C.; Oliveira,Gabriel H. H. de; Hauth,Michele R.. |
| ABSTRACT Knowledge of the water sorption phenomenon in Brazil nut seeds will allow proper handling of this product, especially with regard to adequate conditions for safe storage. Thus, the present study aimed to determine the sorption isotherms (desorption and adsorption) of Brazil nuts, fitting different mathematical models to the experimental data, as well as to examine the hysteresis effect. To obtain the sorption isotherms, the static method was employed at temperatures of 25, 35, 45 and 55 °C and air relative humidities varying from 10 to 80%. The psychrometric conditions of the air were acquired with the aid of acid solutions and specific saturated saline left inside desiccators with the samples. It was verified that for a given isotherm, the... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Bertholletia excelsa; Moisture content; Hysteresis; Mathematical modeling. |
| Ano: 2019 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662019001000776 |
| |
|
|
| Guimarães,Rafaiane M.; Oliveira,Daniel E. C. de; Resende,Osvaldo; Silva,Jhessika de S.; Rezende,Thaisa A. M. de; Egea,Mariana B.. |
| ABSTRACT ‘Okara’ is the insoluble part obtained after the aqueous extraction of soybeans, generated in large quantities as a by-product of the ‘tofu’ industry or soybean water-soluble extract. This work aimed to study ‘okara’ convective drying kinetics, determine the effective diffusion coefficient, and obtain activation energy and thermodynamic properties under different drying conditions. The by-product ‘okara’ was obtained from the processing of BRS 257 soybean water-soluble extract, homogenized and dried in a forced-air oven at temperatures of 40, 50, 60 and 70 °C until constant weight. Among the analysed models, Wang & Singh was selected to represent the drying phenomenon. Effective diffusion coefficient increased with the temperature rise, and... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Mathematical modeling; Activation energy; Diffusion coefficient. |
| Ano: 2018 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662018000600418 |
| |
|
|
| Goneli,André L. D.; Corrêa,Paulo C.; Oliveira,Gabriel H. H. de; Resende,Osvaldo; Mauad,Munir. |
| ABSTRACT Sorption isotherms are of great importance in post-harvest procedures, especially for predicting drying and storage, which help to establish the final moisture content of the product under certain environmental condition. Hysteresis is a phenomenon that occurs due to the difference between adsorption and desorption curves, which aids the evaluation of chemical and microbiological deteriorations, indicating the stability of stored products. Moisture sorption isotherms of castor beans were determined and hysteresis was analyzed. Static gravimetric technique at different temperatures (25, 35, 45 and 55 ± 1 °C) was used. Saturated salt solutions in the range of 37-87% ± 2% were utilized to create the required controlled relative humidity environment.... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Ricinus communis L.; Equilibrium moisture content; Mathematical modeling. |
| Ano: 2016 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662016000800751 |
| |
|
|
| Freitas,Bheatriz S. M. de; Cavalcante,Maisa D.; Cagnin,Caroline; Silva,Richard M. da; Plácido,Geovana R.; Oliveira,Daniel E. C. de. |
| ABSTRACT The objective of this work was to perform foam-mat drying of yellow mombin pulp, verifying the kinetics and mathematical modeling of the process, and characterizing the obtained product with respect to physical and chemical characteristics, compared with the fresh pulp. Foam-mat drying was carried out with the aid of the foam agent Emustab®, at temperatures of 50, 60, 70 and 80 °C. The drying data were analyzed and fitted to four mathematical models (Wang & Singh, Verma, Page and Midilli). Effective diffusion coefficient and activation energy were determined. Titratable acidity, pH, soluble solids content and vitamin C content, as well as the solubility in water of yellow mombin powder and color variance (L*, a*, b*) were analyzed in both... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Drying kinetics; Diffusion; Mathematical modeling. |
| Ano: 2018 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662018000600430 |
| |
|
|
| Santos,Francislaine S. dos; Figueirêdo,Rossana M. F. de; Queiroz,Alexandre J. de M.; Santos,Dyego da C.. |
| ABSTRACT The objective of this work was to obtain the drying kinetic curves of white-fleshed ‘pitaya’ peels and characterize the obtained powder regarding physical and chemical parameters. Different mathematical models were fitted to the experimental data of drying kinetics, considering the coefficient of determination (R2), mean square deviation (MSD) and residual distribution as fit criteria. The peels had an initial moisture content of 93.38% (w.b.) and final moisture contents of 5.39% at temperature of 50 °C, 5.27% at 60 °C and 4.40% at 70 °C. After drying, the peels were disintegrated to obtain the powders and characterized for moisture content, reducing sugars, total titratable acidity, ascorbic acid, betacyanins, betaxanthins, water activity and... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Hylocereus undatus; Dehydration; Mathematical modeling; Betalains. |
| Ano: 2017 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662017001200872 |
| |
|
|
| Furuya,Valéria R.B.; Michelato,Mariana; Cruz,Thais P. da; Furuya,Wilson M.. |
| This study ascertains the length-weight relationship and predicts body composition equations in cultivated Astyanax aff. fasciatus. A total of 300 fish were distributed in five groups according to body weight: 1.19 ± 0.18, 3.7 ± 0.70, 7.55 ± 0.97, 12.28 ± 2.32 and 22.16 ± 2.64 g. The length-weight relationship was elaborated using linear (y i = b0 + b1x i) or second-order (y i = b0 + b1x i + b1x i²) regression analysis. The value of the b slope in the length-weight relationship was 3.6971 and the intercept was 0.0031. The prediction equations obtained for body moisture, crude protein, crude lipid and ash were, y = 71.680 - 0.404BW, y = 17.140 - 0.095BW, y = 8.432 +0.364BW and y = 3.720 - 0.032BW, respectively, where BW is the body weight of fish (g). The... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Aquaculture; Fish; Growth; Mathematical modeling; Regression analysis. |
| Ano: 2014 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1984-46702014000600001 |
| |
|
|
| Silva,Tarcila Souza de Castro; Santos,Lilian Dena dos; Silva,Lilian Carolina Rosa da; Michelato,Mariana; Furuya,Valéria Rossetto Barriviera; Furuya,Wilson Massamitu. |
| The objective of the present study was to develop models for predicting live weight from the length-weight relationship and body composition of Nile tilapia. A total of 3,000 juvenile fish (initial weight = 28.6±4.16 g and standard length = 13.8±0.16 cm) were distributed into three circular cages (12 m3 each). The fish were hand-fed extruded diets containing 332 g kg-1 of crude protein and 3,230 kcal kg-1 of digestible energy, until apparent satiety, twice daily, for 100 days. Twelve fish were collected from each cage every 20 days for measurements of body weight and length, and proximate composition analysis; statistical analysis was conducted using linear regression. The value of the slope b and the intercept for the length-weight relationship were... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Amino acids; Aquaculture; Fish; Mathematical modeling. |
| Ano: 2015 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-35982015000400133 |
| |
|
|
| Nääs,Irenilza de Alencar; Romanini,Carlos Eduardo Bites; Salgado,Douglas D'Alessandro; Lima,Karla Andrea Oliveira; Vale,Marcos Martinez do; Labigalini,Marcelo Ricardo; Souza,Silvia Regina Lucas de; Menezes,Adriana Gomes; Moura,Daniella Jorge de. |
| Global warming is affecting agribusiness in its economic aspects. Therefore, the prediction of the evolution of Brazilian beef cattle production cost was made using the IPCC forecast scenario for global warming. The methodology consisted of two steps: (i) the development of a fuzzy model that estimated the grazing land capacity (RP) decrease risk as a function of the changes in the average total rain index, air temperature and increase in extension of the dry season; and (ii) the design of an algorithm for predicting the decrease in production as function of the RPfuzzy model, that results in the impact in beef cattle productivity, and consequent increase in production costs. Historical environmental data from important producing counties in the Cerrado... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Dry season; Environmental temperature; Fuzzy simulation; Mathematical modeling. |
| Ano: 2010 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162010000100001 |
| |
|
|
| Brondani, Gilvano Ebling; Escola Superior de Agricultura "Luiz de Queiroz" (ESALQ/USP); Wendling, Ivar; Empresa Brasileira de Pesquisa Agropecuária (Embrapa - Florestas); Brondani, André Ebling; Universidade Federal Fluminense; Araujo, Marla Alessandra; Universidade Federal de Lavras; Silva, André Luís Lopes da; Universidade Federal do Paraná; Gonçalves, Antonio Natal; Escola Superior de Agricultura “Luiz de Queiroz”, Universidade de São Paulo. |
| It is possible to determine the optimum time for permanence of vegetative propagules (mini-cuttings) inside a greenhouse for rooting, and this value can be used to optimize the structure of the nursery. The aim of this study was to determine the dynamics of adventitious rooting in mini-cuttings of three clones of Eucalyptus benthamii x Eucalyptus dunnii. Sprouts of H12, H19 and H20 clones were collected from mini-stumps that were planted in gutters containing sand and grown in a semi-hydroponic system. The basal region of the mini-cuttings was immersed in 2,000 mg L-1 indole-3-butyric acid (IBA) solution for 10 seconds. The rooting percentage of the mini-cuttings, the total length of the root system and the rooting rate per mini-cutting were also evaluated... |
| Tipo: Pesquisa |
Palavras-chave: 5.01.03.04-0 vegetative propagation; Clonal forestry; Organogenesis; Mathematical modeling; Rhizogenesis; Clonal mini-garden 5.01.03.04-0. |
| Ano: 2012 |
URL: http://periodicos.uem.br/ojs/index.php/ActaSciAgron/article/view/13059 |
| |
|
|
| Absalan, Ghafour; Kianmehr, Mohammad Hossein; Arabhosseini, Akbar. |
| Compost compression processes, such as pelleting, increase bulk density, improve storability, reduce transportation costs and make easier materials handling using existing equipment for handling and storage of grains. It is important to prevent quality deterioration of pellets in long time storage. Therefore, it is necessary to reduce the moisture content of the pellets to less than or less. In this research the drying kinetics of compost pellets were studied at air temperatures of 50, 60 and 70 , air velocities of 0.5, 1 and 1.5 , particle sizes of 1.18 and 2 mm and pellet diameters of 6 and 8 mm. The maximum effective moisture diffusivity (1.78× ) was obtained at air velocity of , air temperature of 70 , particle size of 1.18 mm and pellet diameter of 8... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Drying kinetics; Effective moisture diffusivity; Mathematical modeling; Pellet. |
| Ano: 2016 |
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/3656 |
| |
|
| |
|
| |
|
|
| Santos,Maria L.S.; Muniz,Kátia; Barros-Neto,Benício; Araujo,Moacyr. |
| The Amazon River estuary is notable at the Amazon Continental Shelf, where the presence of the large amount of water originating from the Amazon during the river's falling discharge period was made evident by the low salinity values and high nutrient levels. Even so, the presence of oceanic waters in the shelf area was significant. Dissolved organic nitrogen was the predominant species of the nitrogen cycle phases, followed by total particulate nitrogen, nitrate, ammonium and nitrite. The chlorophyll a data in the eutrophic area indicated that there is sufficient nitrogen in the area to withstand productivity, though dissolved inorganic nitrogen removal processes are faster than regeneration or mineralization. The anomalous amounts of inorganic dissolved... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Amazon Continental Shelf; Nitrogen; Phosphate; Mathematical modeling. |
| Ano: 2008 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652008000400011 |
| |
|
|
| Grégio,Juliana M.; Caetano,Marco A.L.; Yoneyama,Takashi. |
| Optimal control theory provides a very interesting quantitative method that can be used to assist the decision making process in several areas of application, such as engineering, biology, economics and sociology. The main idea is to determine the values of the manipulated variables, such as drug doses, so that some cost function is minimized, subject to physical constraints. In this work, the cost function reflects the number of CD4+T cells, viral particles and the drug doses. It is worth noticing that high drug doses are related to more intense side-effects, apart from the impact on the actual cost of the treatment. In a previous paper by the authors, the LQR - Linear Quadratic Regulator approach was proposed for the computation of long period... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: AIDS; Filtering; Drugs; Mathematical modeling; Optimization. |
| Ano: 2009 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652009000100002 |
| |
|
|
| Longhi,Daniel Angelo; Tremarin,Andréia; Carciofi,Bruno Augusto Mattar; Laurindo,João Borges; Aragão,Gláucia Maria Falcão de. |
| The aim of this study was to establish primary and secondary models to describe the growth kinetics of Byssochlamys fulva on solidified apple juice at different temperatures. B. fulva was inoculated on solidified apple juice at 10, 15, 20, 25 and 30 °C. Linear-with-breakpoint, Baranyi and Roberts, and Huang primary models (without upper asymptote) were fitted to the data, and they showed good ability to describe the growth kinetics. B. fulva showed longer adaptation time on apple juice than on culture medium, but growth rates were similar as reported in the literature. The dependence of µmax and λ parameters on temperature was described with Square Root and Arrhenius-Davey secondary models, respectively. These models were important to establish... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Mould growth; Mathematical modeling; Food microbiology; Predictive mycology. |
| Ano: 2014 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132014000600971 |
| |
|
|
| Teixeira,Sirlei Dias; Fiorio,Jhonatan Luiz; Galvan,Diego; Sefstrom,Carolina; Cogo,Priscila Morgana; Sales Junior,Valber; Rodrigues,Márcio Barreto; Hendges,Ana Paula Palaro Klein; Maia,Beatriz Helena L. de Noronha Sales; Benghi,Thalita Gilda Santos. |
| ABSTRACT: The extraction of essential oils obtained by the hydrodistillation of needles/twigs waste of Pinus taeda L. was optimized by applying response surface methodology (RSM), with 24 full factorial design, in order to improve oil essential production, and aggregate value to the production chain of pine wood. Through the model it was possible to ascertain the influence of the variables in the average amount of essential oil (0.1032 mL), being the variables analyzed: biomass - Bm (x1), extraction time - ET (x2), Bm:ET (x1x2) and sample size - SS: drying times - DT (x3x4). Only linear terms (biomass and extraction time) and your interaction demonstrated significant positive values (0.0344, 0.0206 and 0.0131). The major components of the essential oil... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Pinus; Byproduct; Essential oil; Response surface methodology (RSM); Mathematical modeling. |
| Ano: 2016 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132016000100603 |
| |
|
|
| Andreola,Ricardo; Jorge,Regina Maria Matos; Santos,Onélia Aparecida Andreo dos; Jorge,Luiz Mario de Matos. |
| An industrial system for the production of white liquor of a pulp and paper industry, Klabin Paraná Papéis, formed by ten reactors was modeled, simulated, and analyzed. The developed model considered possible water losses by the evaporation and reaction, in addition to variations in the volumetric flow of lime mud across the reactors due to the composition variations. The model predictions agreed well with the process measurements at the plant and the results showed that the slaking reaction was nearly complete at the third causticizing reactor, while causticizing ends by the seventh reactor. Water loss due to slaking reaction and evaporation occurred more pronouncedly in the slaker reactor than in the final causticizing reactors; nevertheless, the lime... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Slaker reactor; Causticizing reactor; White liquor; Mathematical modeling; Simulation. |
| Ano: 2011 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132011000100024 |
| |
| Registros recuperados: 47 | |
|
|
|
