The addition of nanoparticles to lubricant is effective for the reduction of wear and friction in the mechanical system. In this research, the effects of additions of copper oxide nanoparticle nanoparticles on lubrication behavior of biodiesel-diesel fuel blends were investigated by using a four-ball tester. Three fuel blends with the addition of 0, 25, 50 and 75 ppm nanoparticle were tested in steady-state conditions at four different rotational speed of 600, 1200 and 1500 rev/min. the results showed that the friction coefficient decreases with the increase in nanoparticles up to 50 ppm because of filling the friction surface with the nanoparticles and replacement of sliding friction with the rolling effect in the contact zone. On the other hand, the FC was enhanced significantly with 75 ppm nanoparticle addition in fuel blends B10 and B20. However, the results showed that the lubrication of fuel blend B50 with the 75 ppm nanoparticle is better than that of other fuel blends in the same situation. Moreover, it was found that with an increase in biodiesel concentration the friction coefficient was reduced due to free fatty acids, monoglycerides, and diglycerides as the components of biodiesel. پرونده مقاله

Due to the massive loss of leaves in parks and green spaces and big cities such as Isfahan and the lack of domestic production of leaf vacuum shredder machine for use in large green spaces of parks, the design and construction of the collecting and recycling by the system is need so the design of the vaccum section which is one of the main parts and includes entrance, channels and ducts and exhaust air passage, a centrifugal fan were diseigned according to the working conditions of the device and and based on the fluid mechanics. Also vaccum air flow rate test was done in this research. پرونده مقاله

Normal lubricants such as petroleum, coals or natural gases are limited and will keep depleting due to high fuel consumption all over the world; so nano-lubricants can be considered as the alternatives. In the present study, copper oxide nanoparticles were mixed with biodiesel-diesel blends to evaluate the wear properties of the mixture by 4-ball wear tribo-tester. CuO nanoparticles (25, 50 and 75 ppm) were dispersed in B10, B20, and B50 blends. The results showed that with increasing the CuO nanoparticle fraction up to 50 ppm in the fuel blend, the wear scar diameter (WSD) decreased. Also, the results indicated that using copper oxide nanoparticles with a dosage of 75 ppm in the fuel blend causes a higher WSD compared with 50 ppm dosage. Based on the results, the scratches and roughness on the surface also decreased with an increase of biodiesel concentration and addition of nanoparticles up to 50 ppm in the fuel mixture. پرونده مقاله

In this paper, to simulate mechanical stress on the cutter bar of the harvesting combine during cutting of wheat stems, first, shearing strength of the stems was measured for various moisture content levels and cutting heights. After that the cutter bar of combine was simulated by Abaqus with the specified conditions. The results of the simulation showed that with increase in moisture content of stem, shear stress on the blade is increased up to 18% due to the viscous damping effect of the moisture of stem. On the other hand, with increase in cutting height, shear stress on the blade is decreased up to 12% because of the accumulation of less mature fibers at the lower levels of stems. پرونده مقاله