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This paper investigates a high electrical conductivity and high strength of alloys based on Cu-Ni-Si system It proclaimed the results of the effect of tin (Sn) component on the mechanical properties and microstructure of Cu-Ni-Sn alloy. The conditions for processing the Cu-Ni-Si alloy were presented, the analysis of microstructure and mechanical properties after heat treatment was examined by X-ray, SEM, EDS and specialized machines. The results showed that with 3% mass of Sn added into the Cu-Ni-Sn alloy along with heat treatment and deformation, the hardness value reached the range of 221-240HV, the tensile strength and elastic limit reached around 1060MPa and 903MPa respectively. However, after heat treatment and deformation for the Cu-Ni-Sn alloy based on 6% mass of Sn, the hardness value reached the range of 221-318HV, the tensile strength and elastic limit were respectively 222MPa and 263MPa higher than those of the Cu-Ni-Sn alloy with 3% mass of Sn. The result from X-ray analysis showed the deflection of peaks. Nonetheless, the new phases were not observed in SEM and EDS, contrariwise, generated modular structure was considered as the proof of the Spinodal cluster. This fact might be explained by two mechanisms: deformation mechanism and Spinodal decomposition.

Alternative fuel and renewable energy is becoming important issue due to unstable fuel supply and price. Recently, bio-fuels are much interested because of their beneficial effects on environment, agriculture and economic development. Raw vegetable oils -a kind of bio-fuels, even though it has many disadvantages, are potential renewable fuel replaced for ever-exhausted fossil fuel. In this work, vegetable oil available in the South of Vietnam such as raw coconut oil is used by heating up to aim at reducing its high viscosity, surface tension, density and meeting the fuel requirements. Experimental and comparative study is carried out on an 80 hp small marine diesel engine fueled with heated coconut oil (HCO) and fossil diesel fuel. The results of engine performance and emission characteristics are measured. The results show that, specific fuel consumption, CO, HC and smoke emissions are higher, but thermal efficiency and NOx emission are lower as using HCO in comparison with diesel fuel. Besides, this study also denotes that, heated raw coconut oil up to 100 o C is considered as the most proper fuel to achieve the engine performance and emission characteristics, which are equal to diesel fuel.

Modern merchant ships use marine propulsion systems equipped with an ultra-long-stroke diesel engine that directly drives a large slow-turning propeller. Such systems use fewer cylinders and generate greater power at slower shaft speeds, which affords improved propulsion performance as well as low repair and maintenance costs. However, this also results in higher torsional vibrations, which can lead to the fatigue of the shafting system. Tests performed on various marine propulsion systems with 5- to 7-cylinder engines have shown that engines with fewer cylinders exhibit a correspondingly wider barred speed range (BSR) and higher torsional vibration stresses. Thus, it is necessary to investigate the optimal engine operation patterns required to quickly pass the BSR with smaller torsional vibration. In this study, we carried out a series of BSR passage experiments during actual sea trials to evaluate the intermediate shaft performance under different engine operation patterns. The fractional damage accumulations due to transient torsional vibration stresses were calculated to estimate the fatigue lifetime of the shafting system. Our analysis results show that the torsional fatigue damage during BSR decelerations are small and negligible; however, the fractional damage during accelerations is a matter of concern. Our study determines the optimal main engine operation pattern for quick passage through the BSR with the smallest torsional vibration amplitudes and the least fractional damage accumulation, which can therefore extend the fatigue lifetime of the entire propulsion shafting system. Based on this analysis, we also suggest the optimum engine pattern for safe BSR passage.