Research Progress of Heat Resistant Magnesium Alloys

Magnesium alloy has extremely excellent properties and is known as “21st Century Green Engineering Material”. This article mainly introduces the influence of the heat resistance and comprehensive performance of the three series of Mg-Al, Mg-Zn and Mg-RE heat-resistant magnesium alloys after adding rare earth elements, alkali metal elements and other elements. Three development directions of improving the heat resistance of magnesium alloys are prospected. These are: 1. Using cheap alloy elements (such as Ca, Si, etc.) to replace rare earth elements of the heat-resistant magnesium alloy, 2. Titanium element is added to improve heat-resistant magnesium alloy’s mechanical properties and its strength, 3. The new casting process and processing technology are used to improve the heat-resistant magnesium alloy’s properties. This article aims to provide technical reference for the development of my country’s magnesium alloy industry.

A Hybrid Novel Fuzzy MCDM Method for Comprehensive Performance Evaluation of Pumped Storage Power Station in China

Considering the goals of carbon peaking and carbon neutrality, along with their related policies, pumped storage power stations are set to develop quickly in China. The comprehensive performance of pumped storage power stations must urgently be evaluated, which can help investors in decision making and provide a reference for policymakers. In this paper, a hybrid novel fuzzy multicriteria decision-making (MCDM) method combining the fuzzy best worst method (BWM) and fuzzy TOPSIS was proposed for the comprehensive performance evaluation of pumped storage power stations in China. The fuzzy BWM was utilized to determine the criteria weights describing the comprehensive performance of pumped storage power stations, while the fuzzy TOPSIS was used to rank the comprehensive performance of pumped storage power stations. The index system for the comprehensive performance evaluation of pumped storage power stations in China incorporated economic, social, and environmental aspects. The comprehensive performance of four pumped storage power stations in China was empirically evaluated using the proposed hybrid novel fuzzy MCDM method, and the results indicate that pumped storage power station PSPS2 exhibited the best comprehensive performance, followed by pumped storage power stations PSPS1 and PSPS4, whereas pumped storage power station PSPS3 had the worst comprehensive performance. A sensitivity analysis and comparative analysis were also conducted. The results indicate that the proposed hybrid novel fuzzy MCDM method, combining the fuzzy BWM and fuzzy TOPSIS for comprehensive performance evaluation of pumped storage power stations, is robust and effective.

Improving the comprehensive performance of miniature MR rotary actuators using a lamellar excitation structure

Miniaturization has increasingly become a crucial prerequisite in various magnetorheological (MR) drive application scenarios. Owing to their high controllability and low response time, MR rotary actuators are developed for numerous feasible actuation solutions. However, the incident low degradation efficiency in the miniaturization limits the application of MR rotary actuators. In addition to torque capacity, structural simplification and easy machinability are also essential for miniaturization. In this study, a novel lamellar excitation structure (LES), which is interleaved with induction coils and ring-shaped iron cores, is proposed to improve the comprehensive performance of a miniature MR rotary actuator. The optimisation of the magnetic field distribution is realised by adopting an equivalent magnetic modelling method. The miniature MR actuator is incorporated into a turbine generator to evaluate the torque capability of the proposed LES-incorporated MR actuator via a kinematic model of the rotating shaft. The LES-incorporated MR rotary actuator demonstrates more favourable deceleration efficiency and torque capacity than conventional MR rotary actuators. The speed reduction per unit power Δn/P can be increased by 500% at most. The torque enhancement ratio-to-volume ratio (TEVR) value of LES is approximately 80 times higher than that of other optimised structures. We believe that this study is significant in improving the comprehensive performance of miniature MR rotary actuators, expanding the applications of MR actuators in miniaturised scenarios.