During the grinding train operation process,the grinding force between the grinding wheel and the rail is critical in ensuring the grinding quality and efficiency.The coupling vibration among the frame,the grinding wh...During the grinding train operation process,the grinding force between the grinding wheel and the rail is critical in ensuring the grinding quality and efficiency.The coupling vibration among the frame,the grinding wheels,and the wheelsets will seriously affect the stability of the grinding force.In this paper,the coupled mechanical model of the grinding wheel/rail is established based on the contact mechanics theory,which is embedded as a submodel into the dynamic model of the multi-rigid buggy.The interaction among the frame,the grinding wheels and the wheelsets is analysed by setting the convex irregularity on the rail.The grinding effect is evaluated in combination with the subway’s long wave corrugation grinding conditions.The results show that when the grinding buggy passes the convex irregularity,the vibration excited by the wheelset system has a significant impact on the dynamic behavior of the grinding wheels.The vibration of the grinding wheel is mainly transmitted between the grinding wheel and the frame,less affecting the wheelset.For the long wave corrugation of the subway,the grinding effect of the grinding wheel has a certain correlation with the phase angle of the wheelset through the corrugation.The research results provide an important reference for the setting of the grinding pattern.展开更多
Functional signal conversion devices are critical components of next-generation intelligent systems,driving an urgent demand for novel sensing materials and functionalities to enable advanced applications in intellige...Functional signal conversion devices are critical components of next-generation intelligent systems,driving an urgent demand for novel sensing materials and functionalities to enable advanced applications in intelligent robotics and human-machine interfaces.In this work,we present a quantum dot light-emitting diode(QLED)array based on a newly developed signal conversion functional material 20%Gd-doped CeO_(2-x)(CGO).Under pressure and electric field induction,the oxygen vacancy dynamics in CGO were modulated,resulting in macroscopic polarization charges,reflecting the mechanical force-electrical response effect.The QLED pixel emission intensity was controlled by external pressure,achieving a remarkable1000%enhancement at 1.8 GPa.Combined with resolution-tunable Si MWs array,mapping of 2D pressure distribution on external objects with optical signals was realized.This work extends the force-electrical-optical signal conversion mechanism to centrosymmetric cubic fluorite materials,overcoming the traditional limitations of piezo-phototronic devices that rely on specific crystal symmetries,and provides new avenues for the development of the next-generation smart sensing.展开更多
The teleoperation of a 6 degrees-of-freedom(DOF)manipulator is one of the basic methods to extend people’s capabilities in the wide variety of applications.The master interface based on the force/torque(FT)sensor cou...The teleoperation of a 6 degrees-of-freedom(DOF)manipulator is one of the basic methods to extend people’s capabilities in the wide variety of applications.The master interface based on the force/torque(FT)sensor could provide the full-dimension intuitive teleoperation of a 6-DOF robot since it has the ability to trigger 6-DOF command input.However,due to the force coupling,noise disturbance and unlimited input signals of the FT sensor,this force-sensed interface could not be widely used in practice.In this paper,we present an intuitive teleoperation method based on the FT sensor to overcome these challenges.In this method,the input signals from the force-sensed joystick were filtered and then processed to the force commands by force limit algorithm,with the merits of anti-interference,output limitation,and online velocity adjustment.Furthermore,based on the admittance control and position controller,the manipulator could be teleoperated by the force commands.Three experiments were conducted on our self-designed robotic system.The result of the first experiment shows that the interfered force from the force coupling could be effectively suppressed with the limitation of the input force through force limit algorithm.Then,a parameter was introduced in the other two experiments to adjust the velocity online practically with force limit algorithm.The proposed method could give a practical solution to the intuitive teleoperation based on the FT sensor.展开更多
In this study, free and forced vibration analysis of nano-composite rotating pressurized microbeam reinforced by carbon nanotubes （CNTs） under magnetic field based on modify couple stress theory （MCST） with temper...In this study, free and forced vibration analysis of nano-composite rotating pressurized microbeam reinforced by carbon nanotubes （CNTs） under magnetic field based on modify couple stress theory （MCST） with temperature-variable material propertiesis presented. Also, the boundary conditions at two ends of nano-composite rotating pressurized microbeam reinforced by CNTs are considered as simply supported. The governing equations are obtained based on the Hamilton＇s principle and then computed these equations by using Navier＇s solution. The magnetic field is inserted in the thickness direction of the nano-composite microbeam. The effects of various parameters such as angular velocity, temperature changes, and pressure between of the inside and outside, the magnetic field, material length scale parameter, and volume fraction of nanocomposite microbeam on the natural frequency and response systemare studied. The results show that with increasing volume fraction of nano-composite microbeam, thickness, material length scale parameter, and magnetic fields, the natural frequency increases. The results of this research can be used for optimization of micro-structures and manufacturing sensors, displacement fluid, and drug delivery.展开更多
This paper presents the structural design and dynamic analysis of the magnetic field of the collector of machining wastes. From the viewpoint of energy the magnetic coupled force exerted on machining wastes by the no...This paper presents the structural design and dynamic analysis of the magnetic field of the collector of machining wastes. From the viewpoint of energy the magnetic coupled force exerted on machining wastes by the nonuniform magnetic field of a permanent magnet has been discussed. The difficult problem that machining wastes attracted by a permanent magnet above the iron base platform has been solved.展开更多
This paper introduces a new stabilized finite element method for the coupled Stokes and Darcy problem based on the nonconforming Crouzeix-Raviart element. Optimal error estimates for the fluid velocity and pressure ar...This paper introduces a new stabilized finite element method for the coupled Stokes and Darcy problem based on the nonconforming Crouzeix-Raviart element. Optimal error estimates for the fluid velocity and pressure are derived. A numerical example is presented to verify the theoretical predictions.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.52475137)Sichuan Provincial Science and Technology Program(Grant No.2024YFHZ0280)Sichuan Provincial Nature and Science Foundation Innovation Research Group Project(Grant No.2023NSFSC1975).
文摘During the grinding train operation process,the grinding force between the grinding wheel and the rail is critical in ensuring the grinding quality and efficiency.The coupling vibration among the frame,the grinding wheels,and the wheelsets will seriously affect the stability of the grinding force.In this paper,the coupled mechanical model of the grinding wheel/rail is established based on the contact mechanics theory,which is embedded as a submodel into the dynamic model of the multi-rigid buggy.The interaction among the frame,the grinding wheels and the wheelsets is analysed by setting the convex irregularity on the rail.The grinding effect is evaluated in combination with the subway’s long wave corrugation grinding conditions.The results show that when the grinding buggy passes the convex irregularity,the vibration excited by the wheelset system has a significant impact on the dynamic behavior of the grinding wheels.The vibration of the grinding wheel is mainly transmitted between the grinding wheel and the frame,less affecting the wheelset.For the long wave corrugation of the subway,the grinding effect of the grinding wheel has a certain correlation with the phase angle of the wheelset through the corrugation.The research results provide an important reference for the setting of the grinding pattern.
基金financially supported by the National Natural Science Foundation of China(Nos.52192610,62422120,52371202,52125205,and 52250398)the Natural Science Foundation of Beijing Municipality(No.L223006)+1 种基金Shenzhen Science and Technology Program(No.KQTD20170810105439418)the Fundamental Research Funds for the Central Universities
文摘Functional signal conversion devices are critical components of next-generation intelligent systems,driving an urgent demand for novel sensing materials and functionalities to enable advanced applications in intelligent robotics and human-machine interfaces.In this work,we present a quantum dot light-emitting diode(QLED)array based on a newly developed signal conversion functional material 20%Gd-doped CeO_(2-x)(CGO).Under pressure and electric field induction,the oxygen vacancy dynamics in CGO were modulated,resulting in macroscopic polarization charges,reflecting the mechanical force-electrical response effect.The QLED pixel emission intensity was controlled by external pressure,achieving a remarkable1000%enhancement at 1.8 GPa.Combined with resolution-tunable Si MWs array,mapping of 2D pressure distribution on external objects with optical signals was realized.This work extends the force-electrical-optical signal conversion mechanism to centrosymmetric cubic fluorite materials,overcoming the traditional limitations of piezo-phototronic devices that rely on specific crystal symmetries,and provides new avenues for the development of the next-generation smart sensing.
基金National Key Research and Development Program of China(Grant No.2019YFB1309900)Shandong Provincial Key Research and Development Program of China(Grant No.2019JZZY010432)Institute for Guo Qiang,Tsinghua University,China(Grant No.2019GQG0007).
文摘The teleoperation of a 6 degrees-of-freedom(DOF)manipulator is one of the basic methods to extend people’s capabilities in the wide variety of applications.The master interface based on the force/torque(FT)sensor could provide the full-dimension intuitive teleoperation of a 6-DOF robot since it has the ability to trigger 6-DOF command input.However,due to the force coupling,noise disturbance and unlimited input signals of the FT sensor,this force-sensed interface could not be widely used in practice.In this paper,we present an intuitive teleoperation method based on the FT sensor to overcome these challenges.In this method,the input signals from the force-sensed joystick were filtered and then processed to the force commands by force limit algorithm,with the merits of anti-interference,output limitation,and online velocity adjustment.Furthermore,based on the admittance control and position controller,the manipulator could be teleoperated by the force commands.Three experiments were conducted on our self-designed robotic system.The result of the first experiment shows that the interfered force from the force coupling could be effectively suppressed with the limitation of the input force through force limit algorithm.Then,a parameter was introduced in the other two experiments to adjust the velocity online practically with force limit algorithm.The proposed method could give a practical solution to the intuitive teleoperation based on the FT sensor.
基金the Iranian Nanotechnology Development Committee for their financial supportthe University of Kashan (463855/7)
文摘In this study, free and forced vibration analysis of nano-composite rotating pressurized microbeam reinforced by carbon nanotubes （CNTs） under magnetic field based on modify couple stress theory （MCST） with temperature-variable material propertiesis presented. Also, the boundary conditions at two ends of nano-composite rotating pressurized microbeam reinforced by CNTs are considered as simply supported. The governing equations are obtained based on the Hamilton＇s principle and then computed these equations by using Navier＇s solution. The magnetic field is inserted in the thickness direction of the nano-composite microbeam. The effects of various parameters such as angular velocity, temperature changes, and pressure between of the inside and outside, the magnetic field, material length scale parameter, and volume fraction of nanocomposite microbeam on the natural frequency and response systemare studied. The results show that with increasing volume fraction of nano-composite microbeam, thickness, material length scale parameter, and magnetic fields, the natural frequency increases. The results of this research can be used for optimization of micro-structures and manufacturing sensors, displacement fluid, and drug delivery.
文摘This paper presents the structural design and dynamic analysis of the magnetic field of the collector of machining wastes. From the viewpoint of energy the magnetic coupled force exerted on machining wastes by the nonuniform magnetic field of a permanent magnet has been discussed. The difficult problem that machining wastes attracted by a permanent magnet above the iron base platform has been solved.
基金Project supported by the Science and Technology Foundation of Sichuan Province(No. 05GG006-006-2)
文摘This paper introduces a new stabilized finite element method for the coupled Stokes and Darcy problem based on the nonconforming Crouzeix-Raviart element. Optimal error estimates for the fluid velocity and pressure are derived. A numerical example is presented to verify the theoretical predictions.
