Template-Type: ReDIF-Article 1.0 Author-Name: J. Čupera Author-Workplace-Name: Faculty of Agronomy, Mendel University in Brno, Brno, Czech Republic Author-Name: F. Bauer Author-Workplace-Name: Faculty of Agronomy, Mendel University in Brno, Brno, Czech Republic Author-Name: L. Severa Author-Workplace-Name: Faculty of Agronomy, Mendel University in Brno, Brno, Czech Republic Author-Name: M. Tatíček Author-Workplace-Name: Faculty of Agronomy, Mendel University in Brno, Brno, Czech Republic Title: Analysis of force effects measured in the tractor three-point linkage Abstract: 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 different variants of forces changing in the tractor three-point linkage due to various ways of suspension and adjustment of individual plough types. When using data recorded in the course of ploughing operations it is possible to demonstrate the effect of plough adjustment/attachment on the efficiency of the whole ploughing aggregate. Keywords: three-point linkage, wheel load, load cell Journal: Research in Agricultural Engineering Pages: 79-87 Volume: 57 Issue: 3 Year: 2011 DOI: 10.17221/26/2010-RAE File-URL: http://rae.agriculturejournals.cz/doi/10.17221/26/2010-RAE.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/rae-201103-0001.txt Handle: RePEc:caa:jnlrae:v:57:y:2011:i:3:id:26-2010-RAE Template-Type: ReDIF-Article 1.0 Author-Name: R. Fadavi Author-Workplace-Name: Department of Agricultural Machinery Engineering, Faculty of Agricultural Engineering and Technology, University of Tehran, Karaj, Iran Author-Name: A. Keyhani Author-Workplace-Name: Department of Agricultural Machinery Engineering, Faculty of Agricultural Engineering and Technology, University of Tehran, Karaj, Iran Author-Name: S.S. Mohtasebi Author-Workplace-Name: Department of Agricultural Machinery Engineering, Faculty of Agricultural Engineering and Technology, University of Tehran, Karaj, Iran Title: An analysis of energy use, input costs and relation between energy inputs and yield of apple orchard Abstract: 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 that 71% and 96.7% of total energy input were in indirect and non-renewable form, respectively. The benefit-cost ratio was estimated as 1.77. The regression results revealed that all exogenous variables (for machinery, fertilizers, farmyard manure and packaging energies) were found statistically significant. The packaging had the highest impact (3.23). According to the benefit-cost ratio, large farms were more successful in economic performance. Keywords: energy, economic productivity, apple, packaging Journal: Research in Agricultural Engineering Pages: 88-96 Volume: 57 Issue: 3 Year: 2011 DOI: 10.17221/0/2010-RAE File-URL: http://rae.agriculturejournals.cz/doi/10.17221/0/2010-RAE.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/rae-201103-0002.txt Handle: RePEc:caa:jnlrae:v:57:y:2011:i:3:id:0-2010-RAE Template-Type: ReDIF-Article 1.0 Author-Name: M.O.L. Yusuf Author-Workplace-Name: Department of Civil and Environmental Engineering, University of Port Harcourt, Port Harcourt, Rivers State, Nigeria Author-Name: A. Debora Author-Workplace-Name: Department of Civil and Environmental Engineering, University of Port Harcourt, Port Harcourt, Rivers State, Nigeria Author-Name: D.E. Ogheneruona Author-Workplace-Name: Department of Mechanical Engineering, University of Port Harcourt, Port Harcourt, Rivers State, Nigeria Title: Ambient temperature kinetic assessment of biogas production from co-digestion of horse and cow dung Abstract: 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 (ln(dyt/dt)) against the inverse of time of digestion. This modified first order model also showed that the digester containing horse dung and cow dung in the ratio of 3:1 had the highest short term anaerobic biodegradability index (STABI) of 3.96 at room temperature. Keywords: cow dung, horse dung, anaerobic, modified Gomperzt, biodegradability, kinetics Journal: Research in Agricultural Engineering Pages: 97-104 Volume: 57 Issue: 3 Year: 2011 DOI: 10.17221/25/2010-RAE File-URL: http://rae.agriculturejournals.cz/doi/10.17221/25/2010-RAE.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/rae-201103-0003.txt Handle: RePEc:caa:jnlrae:v:57:y:2011:i:3:id:25-2010-RAE Template-Type: ReDIF-Article 1.0 Author-Name: R. Chotěborský Author-Workplace-Name: Faculty of Engineering, Czech University of Life Sciences Prague, Prague, Czech Republic Author-Name: P. Hrabě Author-Workplace-Name: Faculty of Engineering, Czech University of Life Sciences Prague, Prague, Czech Republic Author-Name: A. Kabutey Author-Workplace-Name: Faculty of Engineering, Czech University of Life Sciences Prague, Prague, Czech Republic Title: Change of mechanical properties in substrate during rewelding deposit Abstract: 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 zone. However, submicroscopic change in substrate ferrite showed decreasing impact toughness. Keywords: gas metal arc welding (GMAW), heat-affected zone, microhardness, impact toughness Journal: Research in Agricultural Engineering Pages: 105-109 Volume: 57 Issue: 3 Year: 2011 DOI: 10.17221/36/2010-RAE File-URL: http://rae.agriculturejournals.cz/doi/10.17221/36/2010-RAE.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/rae-201103-0004.txt Handle: RePEc:caa:jnlrae:v:57:y:2011:i:3:id:36-2010-RAE Template-Type: ReDIF-Article 1.0 Author-Name: M.C. Ndukwu Author-Workplace-Name: Department of Agricultural Engineering, Michael Okpara University of Agriculture, Umuahia, Nigeria Author-Name: S.N. Asoegwu Author-Workplace-Name: Department of Agricultural Engineering, Federal University of Technology, Owerri, Nigeria Title: A mathematical model for predicting the cracking efficiency of vertical-shaft centrifugal palm nut cracker Abstract: 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. Keywords: cracking efficiency, prediction equation, feed rate, throughput capacity, shaft speed, dimensional analysis Journal: Research in Agricultural Engineering Pages: 110-115 Volume: 57 Issue: 3 Year: 2011 DOI: 10.17221/38/2010-RAE File-URL: http://rae.agriculturejournals.cz/doi/10.17221/38/2010-RAE.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/rae-201103-0005.txt Handle: RePEc:caa:jnlrae:v:57:y:2011:i:3:id:38-2010-RAE