In this note, relationships among the components, structure distribution and easy magnetization direction, structure of magnetic domain of nano-magnetic material in the major mature lateral radula teeth of chiton A. r...In this note, relationships among the components, structure distribution and easy magnetization direction, structure of magnetic domain of nano-magnetic material in the major mature lateral radula teeth of chiton A. rubrolinestus Lischke are probed by using the high resolution transmission electron microscope (HRTEM), the scanning electron microscope (SEM), the magnetic force microscope (MFM) and the super-conducting quantum interference device (SQUID) magnetometer from the point of view of magnetism to provide a basis for comprehending biologic function of the magnetic radula.展开更多
Motor-pump assembly is the core component of the Aerospace Electro-hydrostatic Actuator(EHA).Thus,the design of the motor pump can be very challenging under conditions of high speed and wide pressure range,especially ...Motor-pump assembly is the core component of the Aerospace Electro-hydrostatic Actuator(EHA).Thus,the design of the motor pump can be very challenging under conditions of high speed and wide pressure range,especially in particular working mediums.Our ultimate goal is to pursue better flow characteristics under a wide range of working conditions.In this paper,we built a sub-model of the main friction interfaces and a model of single-shaft coaxial motor-pump assembly adopting the method of hierarchical modeling.The experimental investigation of the output characteristics was mainly carried out in a phosphate ester medium environment.Then,the flow characteristics were compared and analyzed with the simulation results.Results indicated that the flow characteristics of the motor-pump assembly could be accurately simulated by the model and quite severe in a low speed and high-pressure environment.展开更多
With the development of power-by-wire technology for more electric aircraft,the electromechanical actuator(EMA)has the advantages to replace the conventional hydraulic servo actuator in some aerospace flight controls....With the development of power-by-wire technology for more electric aircraft,the electromechanical actuator(EMA)has the advantages to replace the conventional hydraulic servo actuator in some aerospace flight controls.Conventional hydraulically powered trimmable horizontal stabilizer actuation(THSA)system is nowadays developed to be electrically supplied.Given their safety-criticality,no-back mechanism and redundant load paths are utilized to meet the flight control requirements.However,rare literatures have introduced these functions and addressed the virtual prototyping activities from system-level point of view.This paper proposed such a model of a THSA system with dual electric power sources and fault-tolerant mechanical load paths.The nonlinear effects of components are considered with realism,and system-level simulation test is conducted to support the model-based system engineering(MBSE)approach.The models are developed with a power view instead of a pure signal view.Focusing on the friction effect and compliance effect with backlash or preload,some improved and novel approaches are adopted for these crucial components and validated via experimental results.Meanwhile,the implemented systemlevel model enables injection of crucial faults.Finally,the simulation of the proposed model shows that it is an efficient resource to investigate the actuator’s dynamic performance,to virtually prove that the actuator meets the fail/safe constraint,and to demonstrate the soundness of the fault monitoring functions.展开更多
基金This work was supported by the National Natural Science Foundation of China (Grant No. 19874078).
文摘In this note, relationships among the components, structure distribution and easy magnetization direction, structure of magnetic domain of nano-magnetic material in the major mature lateral radula teeth of chiton A. rubrolinestus Lischke are probed by using the high resolution transmission electron microscope (HRTEM), the scanning electron microscope (SEM), the magnetic force microscope (MFM) and the super-conducting quantum interference device (SQUID) magnetometer from the point of view of magnetism to provide a basis for comprehending biologic function of the magnetic radula.
基金This study was co-supported by the Chinese Civil Aircraft Project(No.MJ-2017-S49)China Postdoctoral Science Foundation(No.2021M700331).
文摘Motor-pump assembly is the core component of the Aerospace Electro-hydrostatic Actuator(EHA).Thus,the design of the motor pump can be very challenging under conditions of high speed and wide pressure range,especially in particular working mediums.Our ultimate goal is to pursue better flow characteristics under a wide range of working conditions.In this paper,we built a sub-model of the main friction interfaces and a model of single-shaft coaxial motor-pump assembly adopting the method of hierarchical modeling.The experimental investigation of the output characteristics was mainly carried out in a phosphate ester medium environment.Then,the flow characteristics were compared and analyzed with the simulation results.Results indicated that the flow characteristics of the motor-pump assembly could be accurately simulated by the model and quite severe in a low speed and high-pressure environment.
基金supported by the National Natural Science Foundation of China(No.52275062)the Fundamental Research Funds for the Central Universities of Beihang University(YWF-22-L-912).
文摘With the development of power-by-wire technology for more electric aircraft,the electromechanical actuator(EMA)has the advantages to replace the conventional hydraulic servo actuator in some aerospace flight controls.Conventional hydraulically powered trimmable horizontal stabilizer actuation(THSA)system is nowadays developed to be electrically supplied.Given their safety-criticality,no-back mechanism and redundant load paths are utilized to meet the flight control requirements.However,rare literatures have introduced these functions and addressed the virtual prototyping activities from system-level point of view.This paper proposed such a model of a THSA system with dual electric power sources and fault-tolerant mechanical load paths.The nonlinear effects of components are considered with realism,and system-level simulation test is conducted to support the model-based system engineering(MBSE)approach.The models are developed with a power view instead of a pure signal view.Focusing on the friction effect and compliance effect with backlash or preload,some improved and novel approaches are adopted for these crucial components and validated via experimental results.Meanwhile,the implemented systemlevel model enables injection of crucial faults.Finally,the simulation of the proposed model shows that it is an efficient resource to investigate the actuator’s dynamic performance,to virtually prove that the actuator meets the fail/safe constraint,and to demonstrate the soundness of the fault monitoring functions.
