Research in Agricultural Engineering, 2011 (vol. 57), issue 3
Analysis of force effects measured in the tractor three-point linkage
J. Čupera, F. Bauer, L. Severa, M. Tatíček
Res. Agr. Eng., 2011, 57(3):79-87 | DOI: 10.17221/26/2010-RAE 
The work is focused on description of tractor individual axels and wheels loading during ploughing. A combination of tractor inclination with force and momentum effects need not always result in marked differences in the load of driving wheels. This paper documents the relationship existing between forces working in the upper drawbar Fh of the three-point linkage and the momentum MTx. It was also demonstrated that with the increasing value of MTx the difference between loads of both rear wheels reduces. The described algorithm enables to evaluate output parameters of ploughing aggregates for...
An analysis of energy use, input costs and relation between energy inputs and yield of apple orchard
R. Fadavi, A. Keyhani, S.S. Mohtasebi
Res. Agr. Eng., 2011, 57(3):88-96 | DOI: 10.17221/0/2010-RAE
This study examines the energy balance between the input and the output per hectare for an apple orchard in the West Azarbaijan province in Iran (2008-2009). Data were collected by using random sampling method for 80 "face to face" questioners. Results showed that the highest share of energy consumption belongs to packaging (57%) and irrigation (16%). The highest share of expenses was found to be 34% and 30% for labor and packaging, respectively. The total energy input for apple production, energy productivity, net energy and output-input energy value were estimated as 101,505 MJ/ha, 0.23 kg/MJ, -56,320 MJ/ha and 0.44, respectively. Results indicated...
Ambient temperature kinetic assessment of biogas production from co-digestion of horse and cow dung
M.O.L. Yusuf, A. Debora, D.E. Ogheneruona
Res. Agr. Eng., 2011, 57(3):97-104 | DOI: 10.17221/25/2010-RAE
Biogas production from 5 batch digesters containing varying ratio of mix of horse and cow dung was studied for a period of 30 days at ambient temperature. It was observed that biogas production was optimized when horse and cow dung were mixed in a ratio of 3:1. The modified Gompertz equation was used to adequately describe the cumulative biogas production from these digesters. In addition, a modified first order model was developed to assess the kinetics of the biodegradation process. It was observed that the rates of substrate biodegradability and of removal of the biodegradable fractions of the substrate could be obtained by plotting 1/t...
Change of mechanical properties in substrate during rewelding deposit
R. Chotěborský, P. Hrabě, A. Kabutey
Res. Agr. Eng., 2011, 57(3):105-109 | DOI: 10.17221/36/2010-RAE
A study was carried out to examine the influence of rewelding deposit of structural low carbon steel and also the changes which occur in heat-affected zone and subcritical zone during rewelding. Optical metallography, microhardness Vickers method and Charpy impact test were employed to analyze these differences. The results show that rewelding deposit increased the heat-affected zone and fine coarse grain heat-affected zone and also has influence on impact toughness of substrate and their microhardness. Again, it was found that rewelding increased the fine coarse grain heat-affected zone. This effect resulted in increasing impact toughness in the heat-affected...
A mathematical model for predicting the cracking efficiency of vertical-shaft centrifugal palm nut cracker
M.C. Ndukwu, S.N. Asoegwu
Res. Agr. Eng., 2011, 57(3):110-115 | DOI: 10.17221/38/2010-RAE
A mathematical model for predicting the cracking efficiency of vertical-shaft palm nut cracker was presented using dimensional analysis based on the Buckingham's π theorem. A high coefficient of determination of 94.3% between the predicted and measured values showed that the method is good. The model was validated with data from existing palm nut cracker and there was no significant difference between the experimental cracking efficiency with the predicted values at 5% level of significance.