Interest in wind energy use has increased in recent years, specifically in the study field of protected agriculture. To harness residual wind energy produced in an air exhaust system, a wind energy recovery system could be installed using a horizontal axis wind turbine, designed according to airflow conditions at the system outlet. For this reason, airstream in a greenhouse exhaust system was analyzed, wherefore a set of extractors with different number and blades wide, air attack angle, angular velocity and geometry exhaust duct were designed. Subsequently, some simulations were performed by Computational Fluid Dynamics based on different boundary conditions and according two pipeline geometric configurations: with simple and double conical diffuser. 3D model resolution was based on numerically solving the Navier-Stokes equations by means of a finite volume discretization method. With this information 36 2D images of velocity contours and another 36 in 3D of the output airflow streamlines were obtained, also speed and power curves were constructed with respect to geometric model and exhaust system. Moreover, air flow, torque, and power of exhaust system were determined. Finally, opening and flow angle values inside and outside the exhaust system airstream were estimated. By implementing a waste wind energy recovery system at a greenhouse extraction system outlet, will be possible to improve the use of generated airstream, which in most cases is expelled to the outside.

Para diseñar máquinas cortadoras y deshojadoras de mazorcas (Zea mays L.), es necesario conocer las propiedades geométricas del fruto que forman los datos de entrada para la evaluación de los modelos matemáticos del sistema fruto-máquina. Se determinaron tres características geométricas nuevas: diámetro de corte óptimo (do), longitud de la base al diámetro mayor (lbdm) y longitud de la base al diámetro de corte óptimo (lbco) de una muestra de 50 mazorcas de maíz blanco de la variedad Murano, del estado de Morelos, así como longitud total (lt) y diámetro mayor (dm). Del mismo modo para una muestra de 103 mazorcas variedad Arroz del estado de Veracruz se determinaron lbco, lbdm, dm y lt, además se realizó un registro fotográfico y se procesó con el software OpenCV con determinación de dos parámetros más-área (A) y longitud de la base al centroide (lbc). El análisis estadístico mostró que existe una correlación simple de 0.905 entre lbco-lbdm y dos coeficientes de correlación múltiple de 0.904 entre dm-lbdm-lbco, y de 0.917 entre lt-lbdm-lbco para la variedad Murano. La variedad Arroz mostro una correlación múltiple de 0.66 entre lbco-dm-lbdm-lt-A-lbc. Con los resultados se establecieron diferentes modelos matemáticos de relación entre los parámetros de la mazorca para su aplicación en el diseño de un prototipo mejorado de deshojadora.

In the present study, the kinematic and stress analysis of an aerator roller with blades was performed. The trajectories of the aerator roller blades were obtained, which included the rotational and translational movements on the ground. Longitudinal underground areas and volumes of the cracks were calculated for rectangular blades (Type A), symmetric triangular (Type 1) and asymmetric triangular (Type 2) blades. The results of the kinematic analysis reported that type A blades significantly modified soil with respect to the other two. Normal forces were calculated numerically and per finite element, obtaining for blade type 1 numerically calculated forces of 4.52 MPa in the upper zone of the element and -7.06 MPa in its lower zone. The normal stress calculated per finite element were found in the range from 3.66 to 6.52 MPa for the upper part of the element and -7.8 MPa for its lower part. For type 2 design, a normal stress was obtained numerically of 8.83 MPa. The normal stress calculated per finite element was found in the range from 3.95 to 12.86 MPa.

Objective. To develop a low-cost automated irrigation system controlled through Arduino UNO that delivers pulses and intervals according to crop requirements, aimed at tomato growers in low-tech greenhouses with limited resources. Design/ Methodology/ Approach. An Arduino UNO-based system was developed to activate and deactivate four 1/2 HP pumps connected to automate irrigation in a low-tech greenhouse growing Saladette tomatoes in the municipality Saltillo (Coahuila), Mexico. This system was compared to a standard irrigation system with pumps connected to timers. Four types of substrates were irrigated with both systems; mulched soil and polyethylene 12 L-containers filled with three mixtures of peat moss and perlite in ratios of 100:0, 66:33, and 50:50 (v/v). Fertilization with Steiner solution was applied during irrigation according to the growth stages of tomatoes. This treatment arrangement was used to evaluate the efficiency of the two irrigation systems. Results: The Arduino UNO successfully automated tomato irrigation in a low-tech greenhouse. The growing medium of peat moss and perlite (66:33, v/v), irrigated with the automated system, showed the best performance. This results in higher productivity compared to the other substrates, also irrigated by the Arduino UNO, and to all substrates irrigated by timers. It was determined that, in terms of production cost and nutrient solution efficiency, the automated system would benefit resource-limited farmers in the region by enabling them to implement affordable automation, thus increasing tomato yields. Limitations/ Implications of the study. The power supply voltage must be stable for the Arduino UNO board to function correctly. The software coded for the hardware should be simple and user-friendly, with introductory guidance and technical support for its use by the farmer. Findings/ Conclusions. Automated irrigation and fertilization control is more precise with the use of Arduino UNO. By combining irrigation efficiency with a 2:1 peat moss/ perlite mix (66:33, v/v) as substrate, tomato yield is higher and production costs are affordable, with less waste of nutrient solution.