In this study, industrial trial production of the microstructure evolutions and resultant mechanical properties and finite element model of the temperature variation in the cryogenic temperature rebar subjected to the TempCore processes were presented. The microstructure of tested steel rebar is composed of ferrite, pearlite and bainite when the cooling rate is less than or equal to 5 ℃/s. The pearlite disappears when the cooling rate is 10 ℃/s, and the microstructure is composed of granular bainite and a small amount of ferrite. The microstructure consists of martensite and bainite at cooling rate of 20 ℃/s. Compared with the tested steel rebar with water flow rate of 450 m3/h, the tested steel rebar with water flow rate of 100 m3/h has an optimum mechanical strength and a higher uniform elongation at room temperature, and has a higher NSR(notch sensitivity ratio) at - 165 ℃. The uniform elongation is 7.3% at room temperature and NSR is 1.14 at -165 ℃. The ductile-brittle transition temperature of the tested steel rebar with water flow of 100 m3/h is about - 30 ℃, while which of 450 m3/h is 0 ℃. The impact energy of the tested steel bar with water flow of 100 m3/h is 2~3 times that of 450 m3/h at or below 0 ℃, which is mainly due to its ultrafine acicular ferrite and bainite containing high dislocation density and sub-grains.

This paper introduces a novel control strategy into the insulation space for liquid natural gas carriers. The control strategy proposed can improve the effects of control for differential pressure and reduce the energy consumption of nitrogen. The method combines a nonlinear feedback technique with a closed-loop gain shaping algorithm (CGSA). It is designed for the pressure control system which is vital for liquid natural gas carriers (LNGCs) in marine transportation. The control error is modulated using nonlinear function. The deviation signal is replaced with a nonlinear feedback signal. Comparison experiments are conducted under different conditions to prove the effectiveness of this strategy. This paper compares three control strategies: a control strategy with nonlinear feedback based on CGSA, a control strategy without nonlinear feedback based on CGSA, and a two-degree-of-freedom (DOF) control strategy. The simulation results show that this control strategy with nonlinear feedback performs better than the other two. The average reduction of control input is about 38.8%. The effect of pressure control is satisfactory.

The pressure control for a liquid nature gas (LNG) ship is vital for the cargo handling system which is a nonlinear, unstable, and controllable complex system accompanied by the dynamics of time delay. To improve the control effect, this article proposed a robust controller based on closed‐loop gain shaping algorithm by mirror‐mapping approach. In addition, the complete mechanism models for the system are established to predict the changes of temperature, pressure, and liquid inventory in the cargo tank. The heat exchanges and evaporation of liquid are also considered. By collecting the data from the LNG ship “Dapeng,” the system models are validated. At the same time, the comparative experiment is introduced to verify the reliability and effectiveness. The scheme has been compared with the 2‐DOF structure control law of modified Smith predictor. The comparative experimental results show that the scheme proposed in this note has a strong disturbance rejection ability and steady‐state performance. The controller designed in this note has advantages of simplified construction method, satisfactory control effect and robustness.