Sistema fotovoltaico monocristalino para bombeamento de água

Since ancient times, it has been a huge challenge to all people around the world to manage to get their fresh water, keeping it clean and providing it to every human being, so that it can be used for their daily needs. This is especially true for small properties in the countryside and in isolated areas with low demographic density. Pumping the water in those regions is a solution that rationalizes its use in domestic chores, in animal rearing and in the irrigation systems of cultivated areas. Making feasible local, renewable and non-polluted energetic alternatives is the aim for those areas that are usually far away from the public electric network. Using photovoltaic solar energy is the alternative now proposed. For this objective was built a system with two monocrystalline panels, one pump, two water tanks, two level sensors and a solenoid valve to pump water, using a pump powered an array of monocrystalline solar panels. The main goal was to compare their rate of water flow and their energy consumption. The use of one data acquisition equipment allowed collecting meteorological, electrical and hydraulic values, and also serving for the control and activation of the pumping system. During four months in a row as from April 2009, arrangements with one or two panels were tested. Mathematics correlations and adjustment lines were used to interpret the behavior of obtained dataset. During the analyzed period the system followed the linear equations with great accuracy. The daily average amount of water pumped by the several tested arrays stayed between 1,100 and 2,500 liters, and that is enough to supply a small rural property. The pumping system with two panels effectively showed the major amount of water, but a system with one panel can be an economical solution until 1,500 liters on day. It did not characterize a direct relationship between power or quantity of photovoltaic panels and daily outflow of water pumping.

Desempenho de discos de corte de semeadora-adubadora em diferentes quantidades de cobertura vegetal

The quality and efficiency in straw cutting are determinants in the sowing process, according to the occurrence of "tamp" and stops, the magnitude of the straw removal or even the known effects of the seed "envelopment" where the cutting mechanism can not cut the remaining straw. Thus, the objective of this study was to evaluate the performance of different mechanisms for straw cutting of a seeder individualized in different amounts of crop coverage artificially added in a clay soil. The experiment was conducted at Unesp – Sao Paulo State University in the Experimental Farm Lageado, belonging to the College of Agricultural Sciences - Unesp, Botucatu. The experimental design was split plot with four replications, with main plots consisting of five quantities of black oat straw, in area with no-tillage system and subplots of three opening furrows mechanisms, which are: plane disk (PD), corrugated disk (CD) and wavy disk (WD). The wavy disk provided greater rolling resistance, reducing the speed of the set (tractor and equipment). The plane cutting disk showed the highest values of mobilized soil area, deeper penetration into the soil, requiring lower values of vertical force and higher values of lateral force. Regarding the type of waste and doses used, they offered no resistance to cutting and there was no change in the horizontal force on straw.