Although magnetorheological finishing (MRF) is a deterministic finishing technology, the machining results always fall short of simulation precision in the actual process, and it cannot meet the precision requirements just through a single treatment but after several iterations. We investigate the reasons for this problem through simulations and experiments. Through controlling and compensating the chief errors in the manufacturing procedure, such as removal function calculation error, positioning error of the removal function, and dynamic performance limitation of the CNC machine, the residual error convergence ratio (ratio of figure error before and after processing) in a single process is obviously increased, and higher figure precision is achieved. Finally, an improved technical process is presented based on these researches, and the verification experiment is accomplished on the experimental device we developed. The part is a circular plane mirror of fused silica material, and the surface figure error is improved from the initial $\lambda /5$ [peak-to-valley (PV) $\lambda =632.8\mathrm{nm}$], $\lambda /30$ [root-mean-square (rms)] to the final $\lambda /40$ (PV), $\lambda /330$ (rms) just through one iteration in $4.4\min$. Results show that a higher convergence ratio and processing precision can be obtained by adopting error control and compensation techniques in MRF.

Ion beam figuring (IBF) is an optical fabrication technique that provides highly deterministic process to correct surface figure error of previously polished surfaces by using a directed, inert and neutralized ion beam to physically sputter material from the optic surface. Recently, an ion beam figuring system KDIFS-500 has been designed and built in National University of Defense Technology (NUDT) of the P.R. China. KDIFS-500 is capable of processing workpiece up to Φ500mm. Line scanning process was discussed in detail for estimating the parameters of the beam removal function (BRF) in process. Experiments were conducted to demonstrate that the BRF increases gradually in process and by employing a stability control, the BRF can be kept stable in process. Finally, a Φ95 mm plano optical sample of CVD coated SiC substrate has been figured in two process iterations for demonstrating the correction capability of the KDIFS-500. Their figure convergence ratios reached 5.8 and 2.1 respectively. The actual figure residual errors were basically consistent with the predicted error. These consistencies indicated that the IBF processes on KDIFS-500 are predictable deterministic processes.

Steering acid fracturing is a technique that improves the conductivity of carbonate reservoir. It is widely used in a carbonate reservoir. However, due to the lack of comparative experiments, the application of steering acid to improve the fracturing results is still unknown. Therefore, a series of true triaxial acid fracturing experiments were conducted to study steering acid fracturing in carbonate reservoir. The carbonate specimens used in the experiment were from the Qixia group and Dengsi Member in Sichuan, China. In this study, slick water, cross-linked gel, and self-generating acid were used as ahead fluid to cooperate with steering acid. Experimental results show that (1) the low-viscosity ahead fluid with steering acid can result in more complex fractures; (2) the complexity of fractures is influenced by natural fracture and the viscosity of the ahead fluid; and (3) based on the 3D scanning results of the fracture surface, different ahead fluids will lead to different corrosion results. This study provides useful suggestions on steering acid fracturing design and physical simulation experiments.