Modelling and optimisation of hull erection process
Yongquan Zhang, Kelin Xu, Jinwei Yu · International Journal of Production Research · 2010
Due to the low efficiency of hull erection, this paper applies fuzzy-timed place Petri net (P-FTPN) to model the process of hull construction. Triangular Fuzzy Number (TFN) is utilised to denote the uncertain duration. A rule of setting dummy place and a reformative Minkowski subtraction are presented. According to the model, the low efficiency attributes to the time-consuming disequilibrium of each parallel branch and the complicated interrelations within tasks. Thus, we adjust the Orientation Block, eliminate the Hatch Coaming Blocks and combine them with corresponding Compartment Blocks, repartition the complicated Bow Blocks and reduce the construction difficulty. On this basis, modularisation building and preliminary group erection are applied for partial blocks. The parallel erection strategy is achieved on the whole from serial erection strategy. The result shows the efficiency has been enhanced greatly. Finally, whether a given construction state is in rational construction scheme(s) can be identified immediately from the Reasonable Marking Graph (RMG) of the model. Then, the dynamic supervisory control to the hull erection process can be realised.