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Al-Mg and CuZn34 alloys were lap joined using friction stir welding while the aluminum alloy sheet was placed on the CuZn34. In addition, the mechanical properties of each sample were characterized using shear tests. Scanning electron microscopy (SEM) and X-ray diffraction analysis were used to probe chemical compositions. An artificial neural network model was developed to simulate the correlation between the Friction Stir Lap Welding (FSLW) parameters and mechanical properties. Subsequently, a sensitivity analysis was performed to investigate the effect of each input parameter on the output in terms of magnitude and direction. Four methods, namely, the “PaD” method, the “Weights” method, the “Profile” method, and the “backward stepwise” method, which can give the relative contribution and/or the contribution profile of the input factors, were compared. The PaD method, giving the most complete results, was found to be the most useful, followed by the Profile method that gave the contribution profile of the input variables.

In this study, the effects of extractives in wood flour on the physicomechanical properties of wood flour-polypropylene (PP) composites have been investigated. Three different solvents, hot-water (HW), 1% NaOH (AL), and dichloromethane (DM), were used to remove extractives in both poplar and eucalypt wood flour. The obtained results showed that mechanical properties of the composites were moderately enhanced on using extractive-free lignocellulosic materials in both the wood types. A large increase in the strength of eucalyptus flour-PP composites was observed upon the removal of extractives from eucalyptus flour. Unlike the mechanical properties, no improvement in the water absorption and thickness swelling was observed for any type of extracted-free samples. The thermal degradation behavior of the composites showed that in both cases, the degradation temperatures shifted to higher values after removing the extractives. In general, the removal of AL solubles was more effective in its improvement of the physicomechanical properties than the removal of HW and DM extractives.

Akbarnia A., Farhani F., 2014. Study of fuel consumption in three tillage methods. Res. Agr. Eng., 60: 142-147.Fuel consumption per hectare of tilled land for the conventional or maximum tillage, reduced tillage using a multi-task machine, and no-tillage using a direct drill planter has been studied and compared. Time taken and number of tractor trips needed for performing tillage operations were used for comparison. Yield of crop per hectare was also used for the study. Duncan's multiple range test was used to compare and analyse the data. Results of fuel consumption were 59.33, 29.67 and 14.33 l/ha for the max. tillage, reduced tillage, and no-tillage cases, respectively. The corresponding yield of crop for these methods were 8.07, 7.90, and 6.33 t/ha, respectively. Therefore, the reduced and no-tillage methods provide enough energy saving per ton of yield to justify their use as good replacements for the max. tillage method in Iran. Also, considering land conditions in Iran, use of direct drill planters is recommended for dry cultivated or traditionally irrigated farms, and multi-task machinery for all types of irrigation systems and land conditions. Keywords: maximum tillage; reduced tillage; no-tillage; multi multi-task machinery; direct drill planter Agriculture, which is the most important sector in the production of food in Iran, is also a big consumer of energy in this country (Farahmandpour et al. 2009). Factors such as time lost for replacement of implements and tools used in conventional (maximal) tillage operations, wear out of tractors, high fuel consumption due to the increased number of tractor trips, and high capital investment needed for purchase of various implements result in higher production costs in the traditional agriculture practice in Iran. In addition, movement of tractors and implements on the soil results in soil compactness, which forms hard pan that prevents the penetration of water and free movement of plant roots deep inside the soil.Mechanization of agricultural operations and use of modern machinery such as multi-task machines and direct drill planters can reduce energy consumption per ton of yield of crop, and results in lower cost of production. Moreover, application of modern tillage methods decreases soil agitation, helps in conservation of soil humus, and prevents soil erosion (Hargrave et al. 1982). Bonari et al. (1995) studied the effect of using multi-task machines, as reduced tillage method, on the yield of crop or soil physical properties. They also focused on the reduction of energy consumption by studying the energy consumption in various tillage methods under different conditions. They reported that reduced tillage resulted in 55% less fuel consumption than the max. tillage, without a significant difference in the yield of crop. Similarly, Craciun et al. (2004) reported that in comparison with the technology with two passes on land, the fuel consumption is reduced by up to 60%. Kosutic et al. (2005) studied the energy consumption in different tillage syst...