In the traditional pipeline magnetic flux leakage(MFL)detection technology,circumferential or axial excitation is mainly used to excite the magnetic field of defects.However,the domestic and foreign pipeline detection...In the traditional pipeline magnetic flux leakage(MFL)detection technology,circumferential or axial excitation is mainly used to excite the magnetic field of defects.However,the domestic and foreign pipeline detection devices currently in operation are mainly axial excitation MFL detection tools,in which circumferential cracks can be clearly identified,but the detection sensitivity of axial cracks is not high,thus forming a detection blind zone.Therefore,a composite excitation multi-extension direction defect MFL detection method is proposed,which can realize the simultaneous detection of axial and circumferential defects.On the basis of the electromagnetic theory Maxwell equation and Biot Savart law,a mathematical model of circumferential and axial magnetization is firstly established.Then finite element simulation software is used to establish a model of a new type of magnetic flux leakage detection device,and a simulation analysis of crack detection in multiple extension directions is carried out.Finally,under the conditions of the relationship model between the change rate of leakage magnetic field and external excitation intensity under unsaturated magnetization and the multi-stage coil magnetization model,the sample vehicle towing experiment is carried out.The paper aims to analyze the feasibility and effectiveness of the new magnetic flux leakage detection device for detecting defects in different extension directions.Based on the final experimental results,the new composite excitation multi extension direction leakage magnetic field detector has a good detection effect for defects in the axial and circumferential extension directions.展开更多
This paper presents a compact and high-performance piezoelectric micro-electro-mechanical system(MEMS)fast steering mirror(FSM)designed for use in laser inter-satellite links(ISLs).The FSM features a large optical ape...This paper presents a compact and high-performance piezoelectric micro-electro-mechanical system(MEMS)fast steering mirror(FSM)designed for use in laser inter-satellite links(ISLs).The FSM features a large optical aperture of 10 mm and is batch fabricated using an 8-inch wafer-level eutectic bonding process,packaged into a volume of 26×22×3 mm3.Notably,the piezoresistive(PZR)sensor is integrated on the spring of the FSM to facilitate precise beam control.Furthermore,an intermediate directional defect structure is novelly designed to create a Stress Concentration Region(SCR),effectively improving PZR sensitivity from 3.3 mV/(V∙mrad)to 5.4 mV/(V∙mrad).In this article,various performance metrics of the FSM are tested,including the mechanical characteristics,PZR sensor properties,and mirror optical quality,which all meet the requirements for laser ISLs.Results indicate that the FSM achieves a high resonant frequency(>1 kHz)and a low nonlinearity of 0.05%@±2.1 mrad.A remarkable minimum angular resolution of 0.3μrad and a repeated positioning accuracy of 1.11μrad ensure exceptional pointing precision.The open-loop control is driven by the double-step algorithm,resulting in a step response time of 0.41 ms and achieving a control bandwidth over 2 kHz.Additionally,the integrated angular sensor demonstrates a nonlinearity of 0.09%@±1.05 mrad,a sensitivity of 5.1 mV/(V∙mrad),and a minimum angular resolution of 0.3μrad.Under quasi-static driven conditions(500 Hz@±2 mrad),the maximum dynamic deformation of the mirror surface is merely 2 nm.展开更多
基金National Natural Science Foundation of China(No.51804267)State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum,Beijing(No.PRP/open-1610)。
文摘In the traditional pipeline magnetic flux leakage(MFL)detection technology,circumferential or axial excitation is mainly used to excite the magnetic field of defects.However,the domestic and foreign pipeline detection devices currently in operation are mainly axial excitation MFL detection tools,in which circumferential cracks can be clearly identified,but the detection sensitivity of axial cracks is not high,thus forming a detection blind zone.Therefore,a composite excitation multi-extension direction defect MFL detection method is proposed,which can realize the simultaneous detection of axial and circumferential defects.On the basis of the electromagnetic theory Maxwell equation and Biot Savart law,a mathematical model of circumferential and axial magnetization is firstly established.Then finite element simulation software is used to establish a model of a new type of magnetic flux leakage detection device,and a simulation analysis of crack detection in multiple extension directions is carried out.Finally,under the conditions of the relationship model between the change rate of leakage magnetic field and external excitation intensity under unsaturated magnetization and the multi-stage coil magnetization model,the sample vehicle towing experiment is carried out.The paper aims to analyze the feasibility and effectiveness of the new magnetic flux leakage detection device for detecting defects in different extension directions.Based on the final experimental results,the new composite excitation multi extension direction leakage magnetic field detector has a good detection effect for defects in the axial and circumferential extension directions.
基金the support from the National Key Research and Development Program of China(no.2023YFB3209900).
文摘This paper presents a compact and high-performance piezoelectric micro-electro-mechanical system(MEMS)fast steering mirror(FSM)designed for use in laser inter-satellite links(ISLs).The FSM features a large optical aperture of 10 mm and is batch fabricated using an 8-inch wafer-level eutectic bonding process,packaged into a volume of 26×22×3 mm3.Notably,the piezoresistive(PZR)sensor is integrated on the spring of the FSM to facilitate precise beam control.Furthermore,an intermediate directional defect structure is novelly designed to create a Stress Concentration Region(SCR),effectively improving PZR sensitivity from 3.3 mV/(V∙mrad)to 5.4 mV/(V∙mrad).In this article,various performance metrics of the FSM are tested,including the mechanical characteristics,PZR sensor properties,and mirror optical quality,which all meet the requirements for laser ISLs.Results indicate that the FSM achieves a high resonant frequency(>1 kHz)and a low nonlinearity of 0.05%@±2.1 mrad.A remarkable minimum angular resolution of 0.3μrad and a repeated positioning accuracy of 1.11μrad ensure exceptional pointing precision.The open-loop control is driven by the double-step algorithm,resulting in a step response time of 0.41 ms and achieving a control bandwidth over 2 kHz.Additionally,the integrated angular sensor demonstrates a nonlinearity of 0.09%@±1.05 mrad,a sensitivity of 5.1 mV/(V∙mrad),and a minimum angular resolution of 0.3μrad.Under quasi-static driven conditions(500 Hz@±2 mrad),the maximum dynamic deformation of the mirror surface is merely 2 nm.
