Nebojsa Dedovic

Surface Area and Volume Modeling of the Williams Pear (Pyrus Communis)

Two methods for estimation of the surface area and volume of a Williams pear quarter provides the focus of this study. The heat energy needed for the drying process depends, in part, on the surface area. The first method involved multiplying the number of pears by the average surface area or volume. The second method involved calculating the surface area and volume of each pear quarter based on the pear length only, as described in the proposed algorithm. It was based on significant correlation between pear length and points on the upper bounder of the pear as well as on integral calculus.

The effects of working parameters and tillage quality on rotary tiller specific work requirement

Accepted 31 October, 2011 The aim of this paper was to analyze the influence of rotary tiller rotor rotation direction on specific work requirement (SWPTO). The SWPTO was calculated by measuring the power take-off (PTO) torque, PTO speed, working speed and depth, as well as the working width. The tillage quality was determined by the bulk density and soil structure. Reverse rotor rotation direction concept is characterized by more efficient tillage which provides significantly higher amount of macro-structure aggregates (0.25 to 10 mm) and their better distribution in the soil. Significantly lower SWPTO was observed with the reverse rotor rotation direction. It was within the range of -2.15-27.74% (14.35% on average) depending on the work speed which was 0.29 to 1.08 m s -1 . Multiple linear regression provided new equations for the calculation of SWPTO depending not only on the working parameters, but on the intensity of soil breaking and soil conditions as well. The obtained equations had high values of Coefficients of determination R 2 (0.92 to 0.99 for conventional and 0.84 to 0.93 for reverse rotor rotation direction). Reverse rotor rotation direction had lower SWPTO values which were 20.3 and 15.5% for the working speeds of 0.5 and 1.0 m s -1 , respectively, and were obtained for equal values of tillage intensity parameters.

Application of an original soil tillage resistance sensor in spatial prediction of selected soil properties

Implementation of novel three-point-hitch measuring system.Investigation of potential of new measuring system for better soil observation.Utilization of geostatistics for maps generation of soil physical properties.Study of interactions between soil tillage resistance and standard soil properties. Horizontal and vertical variability of soil properties, temporal dynamics, and the complexity of monitoring and prediction processes are the limiting factors for full implementation of all the postulates of site specific crop management. The aim of this research was to prove the possibilities for utilization of original soil tillage resistance measuring device in spatial assessment of some physical properties of soil.The tillage resistance measurement and soil evaluation were performed in 2012 on a field of 0.78ha, with calcic chernozem type of soil. The year before, the field was divided into three equal plots where three types of tillage were applied (moldboard plowing, disc harrowing and chisel plowing) in order to increase spatial soil differences and to ensure more reliable testing. Soil physical properties were observed at 30 points that were arranged on the nodes of a rectangular grid all over the field along with their geopositioning. Soil tillage resistance was measured in real time and space, during 30 passes that were made on the entire field by a standard tractor and plow.The tillage management applied in 2011 resulted in the differences of some soil parameters. Significant differences between the field plots arose with respect to cone index, moisture content and soil tillage resistance. However, no differences arose regarding the texture (sand, silt+clay content) and bulk density. The correlation analysis showed a high positive correlation between soil resistance and cone index (R=0.82) and a negative correlation between soil resistance and moisture content (R=-0.41). Fitting of variograms in the modeling of spatial correlation gave the highest prediction error for cone index (13.9%), then for tillage resistance (9.32%), sand content (3.95%), moisture content (3.34%), bulk density (2.4%), and finally clay+silt content (2.2%). The generated maps showed that the soil compaction, moisture and tillage resistance had certain orientations with respect to the field plots.

Corn seeding process fault cause analysis based on a theoretical and experimental approach

Abstract Contemporary trends have set the need for high precision systems in agricultural operations, but it is the seeding technology in the first place that must satisfy the toughest demands to achieve the highest possible profit. The improvement of seeding precision is impossible without knowledge of the working principles of all parts of a singulation mechanism and all factors which influence the seeding errors. The evolution of a seeder depended crucially on the improvement of the testing methodology and techniques. This paper presents a photo-electronic device which monitors the seed flow at free fall after leaving the seeding mechanism. An air blowing seeding mechanism was used to simulate the seeding. Its performances were tested with seven varieties of corn seed, two seeding plates, two different air flow rates, and four different speeds of revolution of the seeding plate. A full factorial design was used to determine the significance of influence of four input factors and interactions of two of them. Data validation was done by comparing the values calculated according to visual analysis of high-speed camera recordings and photo-electronic system data where a strong relationship was achieved (R2 > 0.99). It was determined that the speed of revolution of the seeding plate had the greatest influence on the varying distance between the consecutive seeds, while the seed variety exerted the least influence. The pressure of air flow and the variety of the seeds had the most significant influence on the variation of quality of feed index, although, the type and speed of revolution of the seeding plate were also statistically significant parameters. The occurrence of miss and multiple seed were caused by air flow pressure, variety of the seeds, type of the seeding plate, i.e., speed of revolution of the seeding plate. The applied optimization method can be a useful tool for finding the best possible combination of input parameters observed in the test in order to fulfill the criteria which vary depending on the user’s needs.