“…Test dataset t i = {(x 1 ,y 1 ),...,(x j ,y j )} for i = 1,2,...,m for n = 1,2,...,N )} Figure 3: Operating principle of the stacking model. 3 Geofluids of different sizes of drill bits is divided into three grades: low ROP, medium ROP, and high ROP. The ROP classification makes the value of ROP independent of the size of the drill bit and transforms the modeling task from regression problem to classification problem, which is beneficial to improve the accuracy of model prediction.…”