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Sources of inaccuracy when estimating economically optimum N fertilizer rates
Confidence Interval Economic Optimum N Rate Trials
2013/2/28
Nitrogen rate trials are often performed to determine the economically optimum N application rate. For this purpose, the yield is modeled as a function of the N application. The regression analysis pr...
Evaluation of some empirical methods of estimating potential evapo-transpiration for determination of length of growing season in a tropical wet and dry climate
Potential evapo-transpiration length of growing season
2011/1/12
A comparison of 4 empirical methods of calculating potential evapo-transpiration (PE) using climatic data for the estimation of length of growing season from rainfall – potential evapo-transpiration m...
根系吸水模型参数的混合遗传算法估算方法（Inverse Method Estimating Root Water Uptake Model Parameters Using Hybrid Genetic Algorithms）
根系吸水模型 参数优化 混合遗传算法
2009/9/11
构建了遗传算法与Levenberg-Marquardt算法相结合的混合遗传算法，用于求解根系吸水模型参数。分别进行数值试验和棉花根系吸水试验对混合遗传算法求解精度进行验证。数值试验表明，采用混合遗传算法优化求解根系吸水模型参数的优化值具有较高的精度，含水率资料的时间步长和空间步长对根系吸水模型参数的优化精度有较大影响，在实际中时间步长可取值5～10d，空间步长取值5～10cm。对室内棉花根系吸水进...
Comparison of the Centroid Method and Four Standard Formulas for Estimating Log Volumes
Centroid Method Four Standard Formulas Estimating Log Volumes
2009/1/15
Centroid Samling was tested on 21 logs of Ash ( Fraxinus angustifolia subsp. oxycarpa), 38 logs of Spruce ( Picea orien-talis (L.) Link.), and 33 logs of Beech ( Fagus orientalis Lipsky.) all of which...
Estimating reference evapotranspiration and irrigation water requirements in the Gallikos river basin, Greece
evapotranspiration irrigation cropwater requirements
2008/11/19
Reference evapotranspiration was calculated using five various types of estimating methods. The Hargreaves and Thornthwaite methods produced close, strongly-correlated ETo values to those yielded by t...
Estimating trafficability of three Nigerian agricultural soils from shear strength-density-moisture relationsEstimating trafficability of three Nigerian agricultural soils from shear strength-density-moisture relations
compactive efforts trafficability moisture content shear strength dry density
2008/11/19
The dry density and shear strength of Iwo (Alfisols), Egbeda (Entisols) and Ondo (Ultisols) soil series in south-western Nigeria were measured at different compaction efforts and moisture contents. Re...
Artificial neural network as an alternative to multiple regression analysis for estimating the parameters of econometric models
artificial neural network econometric models grain yield
2010/1/13
In recent years, neural networks have been used for a wide variety of applications where statistical methods are traditionally employed. Neural nets offer the opportunity to create a model by using te...