Juan Manzano

Assessment of a 4-input artificial neural network for ETo estimation through data set scanning procedures

Evapotranspiration is a complex and non-linear phenomenon that depends on the interaction of several climatic parameters. As an alternative to traditional techniques, artificial neural networks (ANNs) are highly appropriate for the modeling of non-linear processes. In general, in the most common ANN applications, the available climatic series are usually split up into 3 data sets: one for training, one for cross-validating, and one for testing. Up to now, the studies regarding ANN-models for reference evapotranspiration estimation and forecasting consider usually only a single chronological assignment of data for the definition of these 3 data sets. In these cases, the ANN performance can only be referred to this specific data set assignment. This paper analyzes the performance of a simple ANN model, a temperature-based 4-input ANN, taking into consideration a complete scan of the possible training, cross-validation, and test set configurations using ‘leave one out’ procedures. The results of a comparative analysis between both methodologies show that the performance results achieved with the traditional methodology can be misleading when evaluating the real ability of a model, as they are referred to the single specific data set assignment assumed.

Generalization of ETo ANN Models through Data Supplanting

This paper describes the application of artificial neural networks (ANNs) for estimating reference evapotranspiration ( ETo ) as a function of local maximum and minimum air temperatures as well as exogenous relative humidity and reference evapotranspiration in different continental contexts of the autonomous Valencia region, on the Spanish Mediterranean coast. The development of new and more precise models for ETo prediction from minimum climatic data is required, since the application of existing methods that provide acceptable results is limited to those places where large amounts of reliable climatic data are available. The Penman-Monteith model for ETo prediction, proposed by the FAO as the sole standard method for ETo estimation, was used to provide the ANN targets for the training and testing processes. Concerning models which demand scant climatic inputs, the proposed model provides performances with lower associated errors than the currently existing temperature-based models, which only consider l...

Characterization and selection method of Venturi injectors for pressurized irrigation

Venturi-type chemigation injectors are widely used due to their advantages: they do not require electric power and are cheap to operate. However, they also generate considerable energy losses which affect the pressure in the system. The correct characterization of these systems requires pressures to be correctly set at the inlet, injector and outlet points in relation to main and injected solution flows. These analytical relationships, as described in the International Organization for Standardization’s standard ISO 15873:2002, can be obtained theoretically, although it is recommended that the manufacturer should determine the real behavior of the injector by operational tests. These relationships should also be provided graphically in the form of nomograms in order to facilitate the association of the variables involved and the subsequent selection of a specific model or class and type of assembly. In order to make the right choice, it is also necessary to have precise information on the irrigation sub-units that it feeds and the grower’s fertilization program.

Assessment Of Urban Landscapes Management

The paper is focused on making an integrated evaluation of hydraulic and energetic management in urban landscapes with the intention of detecting consumptions which are far from those recommended as best. The method is based on indentifying hydrozones inside plots and calculating their water needs. Additionally, an assessment methodology based on catch-can testing and quality irrigation indicators are proposed to appraise irrigation efficiency and uniformity. Finally, some energetic performance indicators for evaluating irrigation supply systems are defined. The protocol has been conducted in the gardens of the Universitat Politecnica de Valencia (Spain) and a potential saving of 43% in water consumption could be achieved. Quality irrigation and energy performance was assessed and showed that the system is not operated under the optimum conditions.

Formas de aplicação e doses de inseticidas sobre Aphis gossypii (Glover) (Hemiptera: Aphididae) em melão amarelo

Para aperfeicoar o manejo fitossanitario de pragas na cultura do melao (Cucumis melo L.), objetivou-se avaliar os efeitos de formas de aplicacao e doses de inseticidas sobre a eficiencia de controle quimico do pulgao A. gossypii. O experimento foi realizado em 2010, na cidade de Fortaleza, Ceara, com melao amarelo cultivado em condicoes de campo. O delineamento experimental foi em blocos ao acaso, arranjo fatorial 2 x 4, com quatro repeticoes e parcelas de seis plantas. Os tratamentos foram duas formas de aplicacao (pulverizacao costal manual e insetigacao por gotejamento) e quatro doses de inseticida (0; 50; 100; 200% da dose recomendada pelo fabricante). Os inseticidas acefato e tiametoxam, testados separadamente, foram aplicados em manejo de rotacao de grupos quimicos. A eficiencia de controle foi avaliada sete dias apos o uso de cada inseticida. O acefato nao apresentou diferenca significativa entre as formas de aplicacao, atingindo eficiencias de controle de 88,95 e 84,09% com 100 e 200% da dose recomendada, respectivamente. O tiametoxam nao diferiu significativamente quanto as formas de aplicacao e doses testadas, apresentando eficiencia de 100% em todos os tratamentos. Atualmente, no Brasil, a utilizacao de acefato no melao esta limitada a aplicacao mecanizada devido ao risco de contaminacao. Diante dessa limitacao, o controle do pulgao em meloeiro amarelo pode ser realizado via insetigacao por gotejo ou pulverizacao costal manual, devendo-se empregar, preferencialmente, 100% da dose recomendada de tiametoxam.