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Modelos para a previsão da produtividade da cana-de-açúcar (Saccharum spp.) através de parâmetros climáticos.; Productivity predicting models to sugarcane (Saccharum spp.) using through weather parameters.

Scarpari, Maximiliano Salles
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 13/09/2002 PT
Relevância na Pesquisa
46.29%
A cultura da cana-de-açúcar é submetida durante o seu desenvolvimento a diferentes condições ambientais, sendo o rendimento agrícola afetado diretamente por estas condições. Dessa variação ao longo do ciclo, surge a necessidade de se prever as respostas da cultura aos diferentes estímulos para fins de planejamento. Modelos de previsão de produtividade e qualidade da matéria-prima tornam-se ferramentas importantes na lavoura canavieira, objetivando suprir estimativas de rendimento ao longo da safra, visando à caracterização das alternativas de manejo, aumentando a eficácia das decisões gerenciais e estratégicas. O objetivo deste trabalho foi desenvolver modelos capazes de obter previsões de ATR - Açúcar Teórico Recuperável e TCH - toneladas de cana-de-açúcar por hectare, ao longo da safra, utilizando dados referentes aos fatores de produção como precipitação e temperatura. Os dados da Usina Açucareira Bortolo Carolo localizada no município de Pontal – SP das safras 1999/2000, 2000/2001 e 2001/2002 foram analisados em termos de produtividade (ATR e TCH), idade do canavial, solo, variedades e manejo, e com os dados testou-se modelos estatísticos de previsão de produtividade utilizando o programa computacional SAS "Statistical Analysis System". Os modelos de maturação (ATR) para cana de ano e cana de ano e meio foram os mais promissores obtendo um coeficiente de determinação R2 = 0...

Uso do melhor preditor linear não viesado (BLUP) em análises dialélicas e predição de híbridos.; Use of best linear unbiased prediction in diallel analysis and in prediction of single crosses.

Iemma, Mariana
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 14/03/2003 PT
Relevância na Pesquisa
26.18%
A obtenção de híbridos de milho está relacionada com o aumento de produtividade dessa cultura. Para isso, normalmente são realizados cruzamentos entre linhagens de diferentes grupos heteróticos, que são determinados pelos melhoristas de forma que seja maximizada a divergência entre eles. A escolha dos genitores a serem cruzados pode ser facilitada pelo uso de cruzamentos dialélicos. Os modelos usados para a análise dos dialélicos permitem a estimação de parâmetros úteis para a seleção dos genitores e o estabelecimento de grupos heteróticos, sendo que os efeitos genéticos normalmente podem ser considerados como aleatórios. A forma tradicional de análise inclui tais efeitos na matriz de incidência dos efeitos fixos e emprega o método dos mínimos quadrados ordinários, o que impossibilita a análise usando a metodologia dos modelos mistos. Os objetivos deste trabalho foram comparar os resultados das análises dialélicas obtidas considerando o modelo fixo e o modelo misto e avaliar a eficiência do melhor preditor linear não viesado (BLUP) para predição de cruzamentos não realizados entre linhagens de milho, utilizando informações de marcadores moleculares RFLP para a estimação da matriz de parentesco. Foram considerados dados de 80 híbridos interpopulacionais e 20 testemunhas comerciais...

Atributos ecofisiológicos do híbrido DKB-390 e modelo estocástico para previsão da produtividade de grãos; Ecophysiological attributes of hybrid DKB-390 and sthocastic model for predicting grain productivity

Detomini, Euro Roberto
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 02/04/2008 PT
Relevância na Pesquisa
26.12%
O milho é uma das culturas mais importantes do mundo, pois os produtos dele oriundos são largamente utilizados na indústria de amidos, na alimentação animal e humana, e também na produção de energia proveniente de biomassa. Por esse motivo, há sempre um grande interesse em conhecer a potencialidade de uso dos principais materiais genéticos disponíveis em relação aos ambientes em que serão inseridos. Este trabalho teve como objetivo central caracterizar, para o genótipo DKB-390 conduzido sob condição irrigada, atributos ecofisiológicos como área foliar, eficiência de uso da radiação, coeficiente de extinção, coeficientes de cultura, consumo hídrico e componentes de espiga; bem como conceitualizar modelos norteadores de manejo e de planejamento para cultura do milho, no intuito de obter a produtividade de grãos contemplada pelas incertezas climáticas diárias dos principais elementos do clima e suas correlações, para posteriormente se obter as correspondentes necessidades de água e de nitrogênio pela cultura. Para tanto, um experimento de campo foi conduzido, informações da literatura foram revisadas e levantadas, e modelos de previsão foram concebidos para a produtividade de grãos e para as demais variáveis de interesse. Como principais resultados...

Predição da disponibilidade de nitrogênio e potencial de resposta à fertilização nitrogenada em plantações de Eucalipto; Prediction of nitrogen availability and response potential to nitrogen fertilization in eucalyptus plantations

Gomes, Simone da Silva
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 27/10/2009 PT
Relevância na Pesquisa
35.93%
Respostas à fertilização nitrogenada têm sido observadas apenas em condições de solo muito especiais, como nos Espodossolos e nos solos muito degradados. Contudo, considerando as altas taxas de exportação de N e o possível esgotamento das reservas de N orgânico potencialmente mineralizável, espera-se que as florestas manejadas intensivamente respondam à fertilização nitrogenada após vários ciclos de cultivo. Os objetivos desse estudo foram: a) caracterizar as taxas anuais e os padrões sazonais de mineralização de N em povoamento de eucalipto em solos representativos do Estado de São Paulo; b) determinar as relações entre as taxas de mineralização de N e atributos físicos e químicos do solo; c) avaliar a relação entre a disponibilidade de N e a resposta à fertilização nitrogenada; d) avaliar a eficiência de atributos específicos do solo e de características ambientais para estimar a taxa de mineralização de N. Onze experimentos de fertilização, incluindo taxas de aplicadas de até 240 kg ha-1 de N foram estabelecidos em plantações de E. grandis ou E. grandis x urophylla de diversos sítios, em diferentes estádios de crescimento, no estado de São Paulo, Brasil. Os sítios possuem precipitação média anual entre 1200 a 1500 mm por ano...

Utilização de modelo agrometeorologico na estimativa de produtividade da cultura da soja, nos estados de GO, MT, PR, RS e SP; Agrometeorological model for soybean productivity estimation in GO, MT, PR, RS and SP states, Brazil

Gustavo Coral
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 27/02/2004 PT
Relevância na Pesquisa
36.12%
A agricultura é a atividade econômica mais afetada pelo clima. Os fenômenos meteorológicos como a temperatura, precipitação, umidade relativa, velocidade do vento, influenciam tanto na produtividade e qualidade dos produtos agrícolas, quanto nos custos de produção. Uma das ferramentas mais utilizadas para quantificar os efeitos causados pelos fenômenos meteorológicos na produtividade agrícola são os modelos agrometeorológicos. No presente trabalho foi utilizado um modelo agrometeorológico multiplicativo, que se baseia na penalização da produtividade agrícola, em decorrência de fenômenos meteorológicos desfavoráveis ao desenvolvimento da cultura, para a estimativa de safra da soja. O estudo abrangeu um total de 66 municípios nos estados de Goiás, Mato Grosso, Paraná, Rio Grande do Sul e São Paulo. Foram relacionados os municípios que possuíam área plantada de soja superior à 2000 ha, com os municípios que possuíam estações pluviométricas operando entre os anos de 1994à 2000. Utilizou-se mapas pedológicos para diferenciação dos tipos de solos predominantes em cada município, com a finalidade de se obterem informações sobre a capacidade de água disponível no solo (CAD), bem como a média histórica da evapotranspiração potencial (ETP) para o cálculo do balanço hídrico decendial e da evapotranpiração real (ETR). As épocas de semeadura selecionadas foram baseadas no Zoneamento Agroclimático da cultura da soja...

Growth indices ans productivity in sugarcane

Simões,Maurício dos Santos; Rocha,Jansle Vieira; Lamparelli,Rubens Augusto Camargo
Fonte: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz" Publicador: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz"
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2005 EN
Relevância na Pesquisa
26.09%
A knowledge about the temporal development of agronomic variables in sugarcane is a very important aspect for the development of crop yield prediction models using remote sensing, and further studies are still needed. This paper describes the temporal evolution of sugarcane biophysical parameters, such as total biomass, leaf area index, number of plants per meter, and productivity. During two seasons, a commercial field in Araras/SP, planted with variety SP80-1842, on the 4th and 5th cuts, was monitored on eight different dates, and data were obtained for 2 m of sugarcane in three crop rows at 18 sampling points. Linear and multiple regression analyses were used to study growth analysis and to correlate agronomic variables (leaf area index and number of plants per meter) with biomass and productivity. Gompertz model, a sigmoidal curve, was the best adjustment curve for total biomass and yield in relation to days after cutting (r² = 0.8987 and r² = 0.9682, respectively); number of plants and leaf area index showed best fit with a cubic exponential model and a quadratic exponential model, respectively. Total biomass and cane productivity were well correlated with LAI in the first two stages of the sugarcane cycle using linear regression. At the end of the cycle...

Application of the Hybrid-Maize model for limits to maize productivity analysis in a semiarid environment

Liu,Yi; Yang,Shenjiao; Li,Shiqing; Chen,Fang
Fonte: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz" Publicador: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz"
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2012 EN
Relevância na Pesquisa
36.01%
Effects of meteorological variables on crop production can be evaluated using various models. We have evaluated the ability of the Hybrid-Maize model to simulate growth, development and grain yield of maize (Zea mays L.) cultivated on the Loess Plateau, China, and applied it to assess effects of meteorological variations on the performance of maize under rain-fed and irrigated conditions. The model was calibrated and evaluated with data obtained from field experiments performed in 2007 and 2008, then applied to yield determinants using daily weather data for 2005-2009, in simulations under both rain-fed and irrigated conditions. The model accurately simulated Leaf Area Index , biomass, and soil water data from the field experiments in both years, with normalized percentage root mean square errors < 25 %. Gr.Y and yield components were also accurately simulated, with prediction deviations ranging from -2.3 % to 22.0 % for both years. According to the simulations, the maize potential productivity averaged 9.7 t ha-1 under rain-fed conditions and 11.53 t ha-1 under irrigated conditions, and the average rain-fed yield was 1.83 t ha-1 less than the average potential yield with irrigation. Soil moisture status analysis demonstrated that substantial potential yield may have been lost due to water stress under rain-fed conditions.

Richness–productivity relationships between trophic levels in a detritus-based system: significance of abundance and trophic linkage

Yee, Donald A.; Yee, Susan Harrell; Kneitel, Jamie M.; Juliano, Steven A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
26.19%
Most theoretical and empirical studies of productivity–species richness relationships fail to consider linkages among trophic levels. We quantified productivity–richness relationships in detritus-based, water-filled tree-hole communities for two trophic levels: invertebrate consumers and the protozoans on which they feed. By analogy to theory for biomass partitioning among trophic levels, we predicted that consumer control would result in richness of protozoans in the lower trophic level being unaffected by increases in productivity, whereas richness of invertebrate consumers would increase with productivity. Our data were consistent with this prediction: consumer richness increased linearly, but protozoan richness was unrelated to changes in productivity. The productivity–richness relationships for all taxa combined were not necessarily consistent with relationships within each trophic level. We used path analysis to investigate the mechanisms that may produce the observed responses of trophic levels to changes in productivity. We tested the importance of the direct effect of productivity on richness and the indirect effect of productivity mediated by effects on total abundance. For protozoans, only direct effects of productivity on richness were important...

PreZon: Prediction by Zone and Its Application to Egg Productivity in Chickens

Lin, Yen-Jen; Liou, Ming Li; Lee, Wen Chuan; Tang, Chuan Yi
Fonte: The Scientific World Journal Publicador: The Scientific World Journal
Tipo: Artigo de Revista Científica
Publicado em 22/05/2012 EN
Relevância na Pesquisa
26.33%
Taiwan red-feathered country chickens (TRFCCs) are one of the main meat resources in Taiwan. Due to the lack of any systematic breeding programs to improve egg productivity, the egg production rate of this breed has gradually decreased. The prediction by zone (PreZone) program was developed to select the chickens with low egg productivity so as to improve the egg productivity of TRFCCs before they reach maturity. Three groups (A, B, and C) of chickens were used in this study. Two approaches were used to identify chickens with low egg productivity. The first approach used predictions based on a single dataset, and the second approach used predictions based on the union of two datasets. The levels of four serum proteins, including apolipoprotein A-I, vitellogenin, X protein (an IGF-I-like protein), and apo VLDL-II, were measured in chickens that were 8, 14, 22, or 24 weeks old. Total egg numbers were recorded for each individual bird during the egg production period. PreZone analysis was performed using the four serum protein levels as selection parameters, and the results were compared to those obtained using a first-order multiple linear regression method with the same parameters. The PreZone program provides another prediction method that can be used to validate datasets with a low correlation between response and predictors. It can be used to find low and improve egg productivity in TRFCCs by selecting the best chickens before they reach maturity.

PREDICTION OF PEROMYSCUS MANICULATUS (DEER MOUSE) POPULATION DYNAMICS IN MONTANA, USA, USING SATELLITE-DRIVEN VEGETATION PRODUCTIVITY AND WEATHER DATA

Loehman, Rachel A.; Elias, Joran; Douglass, Richard J.; Kuenzi, Amy J.; Mills, James N.; Wagoner, Kent
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/2012 EN
Relevância na Pesquisa
26.14%
Deer mice (Peromyscus maniculatus) are the main reservoir host for Sin Nombre virus, the primary etiologic agent of hantavirus pulmonary syndrome in North America. Sequential changes in weather and plant productivity (trophic cascades) have been noted as likely catalysts of deer mouse population irruptions, and monitoring and modeling of these phenomena may allow for development of early-warning systems for disease risk. Relationships among weather variables, satellite-derived vegetation productivity, and deer mouse populations were examined for a grassland site east of the Continental Divide and a sage-steppe site west of the Continental Divide in Montana, USA. We acquired monthly deer mouse population data for mid-1994 through 2007 from long-term study sites maintained for monitoring changes in hantavirus reservoir populations, and we compared these with monthly bioclimatology data from the same period and gross primary productivity data from the Moderate Resolution Imaging Spectroradiometer sensor for 2000–06. We used the Random Forests statistical learning technique to fit a series of predictive models based on temperature, precipitation, and vegetation productivity variables. Although we attempted several iterations of models...

Using Molecular Markers to Characterize Productivity in Chinese Hamster Ovary Cell Lines

Edros, Raihana Z.; McDonnell, Susan; Al-Rubeai, Mohamed
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 17/10/2013 EN
Relevância na Pesquisa
26.12%
Selection of high producing cell lines to produce maximum product concentration is a challenging and time consuming task for the biopharmaceutical industry. The identification of early markers to predict high productivity will significantly reduce the time required for new cell line development. This study identifies candidate determinants of high productivity by profiling the molecular and morphological characteristics of a panel of six Chinese Hamster Ovary (CHO) stable cell lines with varying recombinant monoclonal antibody productivity levels ranging between 2 and 50 pg/cell/day. We examined the correlation between molecular parameters and specific productivity (qp) throughout the growth phase of batch cultures. Results were statistically analyzed using Pearson correlation coefficient. Our study revealed that, overall, heavy chain (HC) mRNA had the strongest association with qp followed by light chain (LC) mRNA, HC intracellular polypeptides, and intracellular antibodies. A significant correlation was also obtained between qp and the following molecular markers: growth rate, biomass, endoplasmic reticulum, and LC polypeptides. However, in these cases, the correlation was not observed at all-time points throughout the growth phase. The repeated sampling throughout culture duration had enabled more accurate predictions of productivity in comparison to performing a single-point measurement. Since the correlation varied from day to day during batch cultivation...

Managing Vulnerability and Boosting Productivity in Agriculture through Weather Risk Mapping

Arce, Carlos; Uribe, Edgar
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Relatório
EN_US
Relevância na Pesquisa
36.06%
Productivity in the agricultural sector is inherently dependent on weather, such as variations in rainfall and temperature. As a result, weather risk events can cause losses in yield and production that translate into economic losses for producers, as well as other sector stakeholders that depend on income from agricultural trade, transport, processing, or export. This document is a guide for development practitioners and strategically presents a variety of mapping techniques for agricultural risk management and illustrates the application of these techniques for informing public and private sector development strategies. The introduction places weather risk mapping within the broader context of agricultural risk, explaining how mapping can enable risk identification, assessment and management activities, and each chapter elaborates on one or more of the technical components. A basic definition of agro-meteorology is provided, along with a discussion of different mapping techniques. The guide presents the available remote (satellite) databases of agro-meteorological variables that can be used for the purpose of weather risk mapping...

Analysis and modelling of the flood pulse and vegetation productivity response in floodplain wetlands

Powell, Susan Jennifer
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Thesis (PhD); Doctor of Philosophy (PhD)
EN_AU
Relevância na Pesquisa
36.06%
This thesis aims to develop a conceptual understanding of the flooding patterns and vegetation response of large floodplain wetlands and to develop an inundation and vegetation response model for water management. Applicable to a range of floodplain wetland systems, the conceptual node-network approach was developed in relation to the Gwydir wetlands, NSW, Australia. The Gwydir floodplains and wetlands occur in a dryland setting and are reliant on flows from the upstream catchment that has substantial water resource development. The Gwydir wetlands include a range of ecological values and are listed under international agreements for the protection of wetlands and migratory waterbirds. The challenge of understanding flooding patterns in the Gwydir wetlands are common to other floodplain systems where shallow inundation, rapid vegetation growth and canopy cover may preclude the assessment of open water flooding from conventional remote sensing techniques. To characterise the flooding patterns a multi-temporal decision tree approach was developed. Based on classification of flooding as open water or from the subsequent high vigour vegetation response, the method uses remotely sensed vegetation indices to map a range of flood events. The results are summarised into homogenous patches with respect to flood frequency and connectivity. Using the patch analysis and assessment of connectivity between the patches and channels...

Missing(ness) in Action : Selectivity Bias in GPS-Based Land Area Measurements

Kilic, Talip; Zezza, Alberto; Carletto, Calogero; Savastano, Sara
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Publications & Research :: Policy Research Working Paper; Publications & Research
ENGLISH; EN_US
Relevância na Pesquisa
26.12%
Land area is a fundamental component of agricultural statistics, and of analyses undertaken by agricultural economists. While household surveys in developing countries have traditionally relied on farmers' own, potentially error-prone, land area assessments, the availability of affordable and reliable Global Positioning System (GPS) units has made GPS-based area measurement a practical alternative. Nonetheless, in an attempt to reduce costs, keep interview durations within reasonable limits, and avoid the difficulty of asking respondents to accompany interviewers to distant plots, survey implementing agencies typically require interviewers to record GPS-based area measurements only for plots within a given radius of dwelling locations. It is, therefore, common for as much as a third of the sample plots not to be measured, and research has not shed light on the possible selection bias in analyses relying on partial data due to gaps in GPS-based area measures. This paper explores the patterns of missingness in GPS-based plot areas...

Why Liquidity Matters to the Export Decision of the Firm

Chan, Rosanna
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Publications & Research :: Policy Research Working Paper; Publications & Research
ENGLISH; EN_US
Relevância na Pesquisa
26.15%
Under financial constraints, exporting may have less to do with productivity and more to do with financial resources. The established relationship between exporting and productivity would differ when examined through the lens of the working capital needs of the firm. The hypothesis that working capital matters in the firm's exporting decision is explored in two ways: first, by articulating a dynamic working capital model of the firm that incorporates the firm's export decision. Secondly, by testing the hypothesis empirically using a unique firm level dataset from Bangladesh, where issues of financial constraints are particularly acute. The model shows that productivity determines export status of the firm as long as it is not under financial constraints. However, under financial constraints, export status is less dependent on productivity and more dependent on the availability of working capital. Empirical results support the model's prediction. The relationship between exporting time and the need for greater liquidity is also borne out empirically as shown by a positive and significant correlation between the amount of working capital and the distance of export destination. An important policy implication from the analysis is that short term liquidity is critical in allowing productive firms to export and that access to finance may prevent the benefits of trade liberalization within a country to be fully realized.

Site index prediction for Pinus radiata D. Don at local scale on the southern tablelands of New South Wales using a national forest productivity model

Ford, Andrew; Brack, Cristopher; James, Ryde
Fonte: Institute of Foresters of Australia Publicador: Institute of Foresters of Australia
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.27%
Productivity indices, developed by the Australian Greenhouse Office as part of the National Carbon Accounting System (NCAS) to aid spatial estimation of native forest productivity across Australia, were tested to estimate site quality for Pinus radiata D.

Prediction of Solar Flares from a Statistical Analysis of Events during Solar Cycle 23

Qu, Z. Q.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 14/11/2008
Relevância na Pesquisa
26.2%
Ways to give medium- and short-term predictions of solar flares are proposed according to the statistical analysis of events during solar cycle 23. On one hand, the time distribution of both C and M class flares shows two main periods of 13.2 and 26.4 months in this cycle by wavelet analysis. On the other hand, active regions of specific magnetic configurations and their evolutions give high productivity of C class flares but relatively low productivity of energetic (M and X class) flares. Furthermore, by considering the measurable kinetic features of active regions, i.e., the rotation of the sunspots, some active regions of specified types are observed to have high energetic flare productivity, above 66%. The periodicity of the activity revealed can be used for medium-term C and M class flare forecasting and the high productivity of active regions forms the basis for short-term prediction of individual energetic flares.; Comment: 11 pages, 5 figures. submitted to ApJ Letters

Validação de modelo fenológico de produtividade de cafeeiro no sul do estado de Minas Gerais; Phenological model validation of coffee productivity in the southern state of Minas Gerais

Miranda, Wezer Lismar
Fonte: Universidade Federal de Lavras; Programa de Pós-Graduação em Recursos Hídricos em Sistemas Agrícolas; UFLA; brasil; Departamento de Engenharia Publicador: Universidade Federal de Lavras; Programa de Pós-Graduação em Recursos Hídricos em Sistemas Agrícolas; UFLA; brasil; Departamento de Engenharia
Tipo: Tese de Doutorado
Publicado em 22/12/2015 POR
Relevância na Pesquisa
46.36%
Coffee production is influenced by the variations of the climatic elements, by the occurrence of adverse conditions (frost, dry spells, etc.) and by plant physiology (bieniannial). The prediction for coffee productivity is very complex due to the intricate physiological mechanisms, cultivar diversity and management conditions. Considering the importance of predicting the productivity for market regulation, with the present study we aimed at validating a model for estimating coffee productivity, based on the use of phenological indexes, submitted to the edaphoclimatic conditions of the southern region of Minas Gerais, Brazil. For this, we used 10 sample plots, distributed in the municipalities of Lavras, Varginha, Carmo de Minas, Ijaci and Santo Antonio do Amparo. The criteria for choosing the plots was based on the existence of a history of productivity superior to 40 sc ha-1 . The necessary meteorological information were collected from the Main Climatological Station belonging to INMET and installed at the campus of the Universidade Federal de Lavras (UFLA, considering as representative of the region. We conducted a hydric balance for the period in which the study was conducted, encompassing the harvests of 2012/2013 and 2013/2014. The collection of phenological data was conducted during the months of September/October...

Application of the Hybrid-Maize model for limits to maize productivity analysis in a semiarid environment

Liu, Yi; Yang, Shenjiao; Li, Shiqing; Chen, Fang
Fonte: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz Publicador: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; Formato: application/pdf
Publicado em 01/10/2012 ENG
Relevância na Pesquisa
36.01%
Effects of meteorological variables on crop production can be evaluated using various models. We have evaluated the ability of the Hybrid-Maize model to simulate growth, development and grain yield of maize (Zea mays L.) cultivated on the Loess Plateau, China, and applied it to assess effects of meteorological variations on the performance of maize under rain-fed and irrigated conditions. The model was calibrated and evaluated with data obtained from field experiments performed in 2007 and 2008, then applied to yield determinants using daily weather data for 2005-2009, in simulations under both rain-fed and irrigated conditions. The model accurately simulated Leaf Area Index , biomass, and soil water data from the field experiments in both years, with normalized percentage root mean square errors < 25 %. Gr.Y and yield components were also accurately simulated, with prediction deviations ranging from -2.3 % to 22.0 % for both years. According to the simulations, the maize potential productivity averaged 9.7 t ha-1 under rain-fed conditions and 11.53 t ha-1 under irrigated conditions, and the average rain-fed yield was 1.83 t ha-1 less than the average potential yield with irrigation. Soil moisture status analysis demonstrated that substantial potential yield may have been lost due to water stress under rain-fed conditions.

Unplanned dilution and ore loss prediction in longhole stoping mines via multiple regression and artificial neural network analyses

Jang,H.; Topal,E.; Kawamura,Y.
Fonte: Journal of the Southern African Institute of Mining and Metallurgy Publicador: Journal of the Southern African Institute of Mining and Metallurgy
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/05/2015 EN
Relevância na Pesquisa
26.13%
Unplanned dilution and ore loss directly influence not only the productivity of underground stopes, but also the profitability of the entire mining process. Stope dilution is a result of complex interactions between a number of factors, and cannot be predicted prior to mining. In this study, unplanned dilution and ore loss prediction models were established using multiple linear and nonlinear regression analysis (MLRA and MNRA), as well as an artificial neural network (ANN) method based on 1067 datasets with ten causative factors from three underground longhole stoping mines in Western Australia. Models were established for individual mines, as well as a general model that includes all of the mine data-sets. The correlation coefficient (R) was used to evaluate the methods, and the values for MLRA, MNRA, and ANN compared with the general model were 0.419, 0.438, and 0.719, respectively. Considering that the current unplanned dilution and ore loss prediction for the mines investigated yielded an R of 0.088, the ANN model results are noteworthy. The proposed ANN model can be used directly as a practical tool to predict unplanned dilution and ore loss in mines, which will not only enhance productivity, but will also be beneficial for stope planning and design.