With the continuous development of science and technology and the growing severity of energy issues,load-sensitive drive systems have attracted significant attention in the electro–hydraulic servo field due to their ...With the continuous development of science and technology and the growing severity of energy issues,load-sensitive drive systems have attracted significant attention in the electro–hydraulic servo field due to their high energy efficiency.Currently,most research primarily focuses on introducing load-sensitive valves to achieve load-following through hydraulic-mechanical feedback.This approach has partially achieved the energy-saving goal,but issues such as reduced dynamic response speed and limited load-sensitive range due to mechanical structures remain.This paper proposes an active load-sensitive variable displacement drive system that no longer relies on mechanical structures for load-sensitive adjustment.And multiple energy efficiency mapping relationships are designed to complete the system's load-sensitive adjustment,thereby reducing throttling losses.Additionally,a dual-loop anti-disturbance control method based on energy efficiency mapping is proposed.An appropriate Lyapunov function is selected to prove that the control system ultimately tends to be bounded and stable,successfully solving the multiplicative nonlinear coupling control problem caused by the variable mechanism,and improving the system's position control accuracy.Experimental results show that under this control method,the active loadsensitive drive system can reduce flow by up to 60 % compared to the traditional fixed displacement hydraulic motor drive system.Compared to conventional PID control,the proposed method can improve control accuracy by up to 50 %,effectively reducing energy consumption while improving the position control accuracy of the active load-sensitive variable motor drive system.展开更多
Results of an experimental and modelling study of forming processes in the AA2099 Al–Cu–Li alloy, for a wide range of temperatures, strains and strain rates, are presented. The analyses are based on tensile testing ...Results of an experimental and modelling study of forming processes in the AA2099 Al–Cu–Li alloy, for a wide range of temperatures, strains and strain rates, are presented. The analyses are based on tensile testing at 20 °C at a strain rate of 0.02 s-1and uniaxial compression testing in the temperature range 400–550 °C at strain rates ranging from0.001 to 100 s-1, for constant values of true strain of 0.5 and 0.9. The stability of plastic deformation and its relationship with a sensitivity of stress to strain rate are considered. The power dissipation efficiency coefficient, g（%）, and the flow instability parameter, n B 0, were determined. The complex processing maps for hot working were determined and quantified, including process frames for basic forging processes： conventional forging and for near-superplastic and isothermal conditions. A significant aspect is the convergence of power dissipation when passing through the 500 °C peak.Deformation, temperature and strain-rate-dependent microstructures at 500 °C for strain rates of 0.1, 1, 10 and 100 s-1are described and analysed for the conventional die forging process frame, corresponding to 465–523 °C and strain rates of50–100 s-1.展开更多
The joint efficient ordering method is a fundamental method of ordering alternatives in group multi-objective programming problems. In this paper, the rational properties of the joint efficient mapping corresponding t...The joint efficient ordering method is a fundamental method of ordering alternatives in group multi-objective programming problems. In this paper, the rational properties of the joint efficient mapping corresponding to the joint efficient ordering method are studied, and some necessary conditions of this mapping are proven.展开更多
基金supported by the National Natural Science Foundation of China(No.52205045)the Natural Science Foundation of Hebei Province,China(No.E2024203244)the Aeronautical Science Foundation of China(No.2022Z029051001)。
文摘With the continuous development of science and technology and the growing severity of energy issues,load-sensitive drive systems have attracted significant attention in the electro–hydraulic servo field due to their high energy efficiency.Currently,most research primarily focuses on introducing load-sensitive valves to achieve load-following through hydraulic-mechanical feedback.This approach has partially achieved the energy-saving goal,but issues such as reduced dynamic response speed and limited load-sensitive range due to mechanical structures remain.This paper proposes an active load-sensitive variable displacement drive system that no longer relies on mechanical structures for load-sensitive adjustment.And multiple energy efficiency mapping relationships are designed to complete the system's load-sensitive adjustment,thereby reducing throttling losses.Additionally,a dual-loop anti-disturbance control method based on energy efficiency mapping is proposed.An appropriate Lyapunov function is selected to prove that the control system ultimately tends to be bounded and stable,successfully solving the multiplicative nonlinear coupling control problem caused by the variable mechanism,and improving the system's position control accuracy.Experimental results show that under this control method,the active loadsensitive drive system can reduce flow by up to 60 % compared to the traditional fixed displacement hydraulic motor drive system.Compared to conventional PID control,the proposed method can improve control accuracy by up to 50 %,effectively reducing energy consumption while improving the position control accuracy of the active load-sensitive variable motor drive system.
基金financed by the Ministry of Science and Higher Education (AGH-UST statutory research project No. 11.11.110.292)
文摘Results of an experimental and modelling study of forming processes in the AA2099 Al–Cu–Li alloy, for a wide range of temperatures, strains and strain rates, are presented. The analyses are based on tensile testing at 20 °C at a strain rate of 0.02 s-1and uniaxial compression testing in the temperature range 400–550 °C at strain rates ranging from0.001 to 100 s-1, for constant values of true strain of 0.5 and 0.9. The stability of plastic deformation and its relationship with a sensitivity of stress to strain rate are considered. The power dissipation efficiency coefficient, g（%）, and the flow instability parameter, n B 0, were determined. The complex processing maps for hot working were determined and quantified, including process frames for basic forging processes： conventional forging and for near-superplastic and isothermal conditions. A significant aspect is the convergence of power dissipation when passing through the 500 °C peak.Deformation, temperature and strain-rate-dependent microstructures at 500 °C for strain rates of 0.1, 1, 10 and 100 s-1are described and analysed for the conventional die forging process frame, corresponding to 465–523 °C and strain rates of50–100 s-1.
基金The research is supported by National Natural Science Foundation of China under Grant No. 70071026 Science Foundation of Wenzhou University and Science Foundation of School of Mathematics and Information Science, Wenzhou University and Zhejiang Province Education Department Scientific Research Item.
文摘The joint efficient ordering method is a fundamental method of ordering alternatives in group multi-objective programming problems. In this paper, the rational properties of the joint efficient mapping corresponding to the joint efficient ordering method are studied, and some necessary conditions of this mapping are proven.
