Papers by Author: Cheng Gang Yang

Abstract: LY12 aluminum alloy was welded with vacuum electron beam welding, the effect of welding speed and electron beam current on the weld microstructure and mechanical properties of welding joints were studied, the results were shown that with the increasing of welding speed or decreasing of electron beam current, the grains in weld metal were refined, so the joint strength were increased. When the electron beam current was 18mA, the welding speed was 1000mm/min, the grains of weld metal were the finest, and the tensile strength was 373.2MPa. In addition, the micro-hardness of weld metal was much lower than base metal and heat affected zone, and the heat affected zone had certain softening phenomenon. With the increasing of welding speed or decreasing of electron beam current, the micro-hardness of weld metal was increased respectively.

Abstract: The rising international oil prices will cause the loss of national GDP and the establishment of strategic petroleum reserves (SPR) could avoid this loss as much as possible. The oil price-GDP elasticity coefficient is an important parameter in calculating strategic petroleum reserve, but since it is difficult to obtain, it is also hard to calculate. This paper provides the fitting formula of oil price-GDP elasticity coefficient based on the regression analyzing of literature data. China’s oil price-GDP elasticity coefficient in recent years has been analyzed and predictions for future trends in different situations have been made. Finally, the predicted oil price-GDP elasticity coefficient is used to calculate the size of China's strategic petroleum reserve and its earnings.