Dimensional control is one of the most important challenges in shipbuilding industry. In order to predict assembly dimensional variation in block construction of shipbuilding, a variation stream model based on state space is presented in this paper, which can be further applied to accuracy control. Both locating error and welding deformation are taken into consideration in this model, and variation propagation mechanisms and accumulative rule in the assembly process are analyzed, then, a model is developed to describe the variation propagation throughout the assembly process, finally, an example of flat block construction is given to provide this method is effective and useful.

Methanol is an attractive alternative transportation fuel because it is a renewable resource and it is oxygenated, thereby providing the potential to reduce particulate emissions in gasoline engines. In this paper the key impacts to the properties of methanol blended with gasoline fuel are discussed. The property impacts including increased alcohol and oxygen content, stability, hygroscopicity, volatility and materials compatibility. The effect of the changed properties on engine performance, durability and emissions is also considered.