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Arc Extraction Analysis for Circularity Measurement of Small Cylindrical Parts by the Segmenting-stitching Method

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仪器仪表学报:英文版 2023年第3期10卷 1-11页

作者： ZHAO Jiali WU Dan ZHANG Liang shen bobo LI Qiaolin School of Mechanical and Electrical Engineering Lanzhou University of TechnologyLanzhou 730050China shenzhen International Graduate School Tsinghua UniversityShenzhen 518055China

To reduce the stitching error of circularity measurement of small cylindrical workpieces(Diameter less than 3 mm)by the segmenting-stitching method,arc contour extraction is analyzed in this *** coordinates of cross-sectional circle of a small cylindrical part are segmented into several equal arcs to be obtained by a two-dimensional coordinate measuring *** circularity contour of the small cylindrical part can be formed by stitching a series of arc contours which are calculated by the obtained arc coordinate *** to the different measuring pressure angles of different measuring positions,the accuracy of obtained arc coordinate points is *** bigger the pressure angle is,the accurate the obtained arc coordinate data *** experiments show that the accuracy of two ends of the arc data is not as good as the central ***,the two ends of the obtained arc data are appropriately to be cut off,namely,only the central part of the arc data are extracted to be used for the *** a result,the mean value of the matching coefficient is enhanced by 12%,the deviation between the overlap part of the neighbouring arc contour is reduced by 26%,and the average curvature of the arc contours is improved with the extraction ***,the accuracy of the stitched circularity contour can be improved by this extraction procedure in the segmenting-stitching method for the circularity measurement of the small cylindrical parts.

关键词： Circularity Measurement Arc Extraction Small Cylindrical Workpiece Segmenting-stitching Method

Improved Circularity Metrology of Small Cylindrical Workpieces by the Segmenting-stitching Technique

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Instrumentation 2023年第4期10卷 39-49页

作者： ZHAO Jiali ZHANG Liang WU Dan shen bobo LI Qiaolin School of Mechanical and Electrical Engineering Lanzhou University of TechnologyLanzhou 730050China shenzhen International Graduate School Tsinghua UniversityShenzhen 518055China

To address the alignment and measuring force problem in the segmenting-stitching technique for the circularity metrology of small cylindrical workpieces(diameter less than 1.5 mm and length less than 10 mm),a magnet combination jig method is proposed.A small round magnet is attached between the round magnetic jig and small cylinder,and the other end of the small cylindrical workpiece is attached to some cylindrical ***,the smaller cylinder can be put in the V-groove and measured successfully with the magnet *** verifying the advantage of the magnet combination jig,four measurement quality evaluations are proposed:the circumferential deviation of neighbor arc contours,radial deviation of neighbor arc contours,angle of inclination between the V-groove and small cylinder,and curvature of the obtained *** results show that the matching coefficient is enhanced by 98%,the Euclidean distance of overlap parts of neighbor arc contours is reduced by 68%,the position error is reduced 27%,and the average curvature of the arc contours is *** can be concluded that the measuring quality can be enhanced prominently by this magnet combination method for the segmenting-stitching method.

关键词： Circularity and Diameter Measurement Magnets Combination Jig Small Cylinder Segmenting-stitching Method

Transient Characteristics and Accommodative Current Limiting Strategy for Bidirectional Interlinking Converters in Hybrid AC/DC Microgrids

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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1575-1588页

作者： Xia shen Zhikang Shuai Wen Huang Chao shen Yang shen Z.John shen College of Electrical and Information Engineering Hunan UniversityChangsha 410082China Department of Electrical and Computer Engineering Illinois Institute of TechnologyChicagoIL 60616 USA

Bidirectional interlinking converter(BIC)is the core equipment in a hybrid AC/DC microgrid connected between AC and DC ***,the variety of control modes and flexible bidirectional power flow complicate the influence of AC faults on BIC itself and on DC sub-grid,which potentially threaten both converter safety and system *** study first investigates AC fault influence on the BIC and DC bus voltage under different BIC control modes and different pre-fault operation states,by developing a mathematical model and equivalent sequence ***,based on the analysis results,a general accommodative current limiting strategy is proposed for BIC without limitations to specific mode or operation *** amplitude is predicted and constrained according to the critical requirements to protect the BIC and relieving the AC fault influence on the DC bus *** with conventional methods,potential current limit failure and distortions under asymmetric faults can also be ***,experiments verify feasibility of the proposed method.

关键词： Bidirectional interlinking converter current limiting fault characteristic hybrid AC/DC microgrid variation/oscillation of DC bus voltage

Rational Solutions of First Order Algebraic Ordinary Differential Equations

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Journal of Systems Science & Complexity 2024年第2期37卷 567-580页

作者： FENG Shuang shen Liyong School of Physical and Mathematical Sciences Nanjing Tech UniversityNanjing 211816China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049China

Let f(t,y,y')=∑ _(i=0)^(n )a_(i)(t,y)y'^(i)=0 be an irreducible first order ordinary differential equation with polynomial *** in 1998 proved that there exists a constant C such that every rational solution of f(t,y,y')=0 is of degree not greater than *** show that this degree bound C depends not only on the degrees of f in t,y,y' but also on the coefficients of f viewed as the polynomial in t,y,y'.In this paper,the authors show that if f satisfies deg(f,y)0,then the degree bound C only depends on the degrees of f in t,y,y',and furthermore we present an explicit expression for C in terms of the degrees of f in t,y,y'.

关键词： Degree bound first order AODE height rational solution

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基于线结构光的空调四通换向阀高度测量

中国测试 2018年第3期44卷 33-37,43页

作者：沈波波许嘉璐孔明中国计量大学计量测试工程学院浙江杭州310018

为提高空调四通换向阀高度测量的精确度以及加工焊接的效率,提出一种基于线结构光的四通换向阀高度测量方法。通过计算机视觉技术搭配线型结构光获取四通阀的表面形貌特征,基于结构光三维测量原理得到被测工件表面各点的实际位置坐标,... 详细信息

为提高空调四通换向阀高度测量的精确度以及加工焊接的效率,提出一种基于线结构光的四通换向阀高度测量方法。通过计算机视觉技术搭配线型结构光获取四通阀的表面形貌特征,基于结构光三维测量原理得到被测工件表面各点的实际位置坐标,从而实现四通换向阀的高度测量。实验研究表明,线结构光法测量结果稳定,并能得到较高的精确度,所得高度的误差小于0.5 mm,满足零件的加工要求。该方法可完成物体表面轮廓的三维重建,克服单目视觉测量过程中丢失被测件深度信息的缺点;并能实现四通换向阀生产线上工件的自动化检测加工,因而避免传统人工测量引起的低效、易疲劳等问题。

关键词：计算机视觉四通阀线结构光三维测量

Large reversible magnetocaloric effect in antiferromagnetic Er_(3)Si_(2)C_(2) compound

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Journal of Rare Earths 2024年第8期42卷 1555-1559,I0005页

作者： Hao Sun Lu Tian Xinqiang Gao Zhaojun Mo Jun shen Baogen shen School of Rare Earths University of Science and Technology of ChinaHefei230026China Ganjiang Innovation Academy Chinese Academy of SciencesGanzhou341000China Department of Energy and Power Engineering School of Mechanical EngineeringBeijing Institute of TechnologyBeijing100081China

The magnetic properties,magnetic phase transition and magnetocaloric effects(MCE) of Er_(3)Si_(2)C_(2) compound were investigated based on theoretical calculations and experimental *** on the first principles calculations,the antiferromagnetic(AFM) ground state type in Er_(3)Si_(2)C_(2) compound was predicted and its electronic structure was *** experimental results show that Ei_(3)Si_(2)C_(2) compound is an AFM compound with the Neel temperature(T_(N) of 7 K and undergoes a field-induced firstorder magnetic phase transition from AFM to ferromagnetic(FM) under magnetic fields exceeding 0.6 T at 2 *** magnetic transition process of Er_(3)Si_(2)C_(2) compound was investigated and *** values of the maximum magnetic entropy change(-ΔS_(M)^(max)) and the refrigeration capacity(RC) are 17 J/(kg·K)and 193 J/kg under changing magnetic fields of 0-5 T,*** a potential cryogenic magnetic refrigerant,the Er_(3)Si_(2)C_(2) compound also provides an interesting research medium to study the magnetic phase transition process.

关键词： Magnetic materials Magnetocaloric Metamagnetic transitions Magnetic phase transition Rare earths

Identifying the enhancement mechanism of Al/MoO_(3) reactive multilayered films on the ignition ability of semiconductor bridge using a one-dimensional gas-solid two-phase flow model

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Defence Technology（防务技术） 2024年第3期33卷 168-179页

作者： Jianbing Xu Yuxuan Zhou Yun shen Yueting Wang Yinghua Ye Ruiqi shen School of Chemistry and Chemical Engineering Nanjing University of Science and TechnologyNanjing 210094China Micro-Nano Energetic Devices Key Laboratory of MIIT Nanjing 210094China Institute of Space Propulsion Nanjing University of Science and TechnologyNanjing 210094China

Energetic Semiconductor bridge(ESCB)based on reactive multilayered films(RMFs)has a promising application in the miniature and intelligence of initiator and pyrotechnics *** the ignition enhancement mechanism of RMFs on semiconductor bridge(SCB)during the ignition process is crucial for the engineering and practical application of advanced initiator and pyrotechnics *** this study,a one-dimensional(1D)gas-solid two-phase flow ignition model was established to study the ignition process of ESCB to charge particles based on the reactivity of Al/MoO_(3) *** order to fully consider the coupled exothermic between the RMFs and the SCB plasma during the ignition process,the heat release of chemical reaction in RMFs was used as an internal heat source in this *** is found that the exothermal reaction in RMFs improved the ignition performance of *** the process of plasma rapid condensation with heat release,the product of RMFs enhanced the heat transfer process between the gas phase and the solid charge particle,which accelerated the expansion of hot plasma,and heated the solid charge particle as well as gas phase region with low *** addition,it made up for pressure loss in the gas *** the plasma dissipation process,the exothermal chemical reaction in RMFs acted as the main heating source to heat the charge particle,making the surface temperature of the charge particle,gas pressure,and gas temperature rise *** result may yield significant advantages in providing a universal ignition model for miniaturized ignition devices.

关键词： Ignition enhancement mechanism 1D gas-solid two-phase flow Al/MoO_(3)reactive multilayered films Semiconductor bridge Miniaturized ignition device

Model-free method for LQ mean-field social control problems with one-dimensional state space

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Control Theory and Technology 2024年第3期22卷 479-486页

作者： Zhenhui Xu Tielong shen School of Engineering Tokyo Institute of TechnologyTokyo 152-8550Japan Department of Engineering and Applied Sciences Sophia UniversityTokyo 102-8554Japan

This paper presents a novel model-free method to solve linear quadratic(LQ)mean-field control problems with one-dimensional state space and multiplicative *** focus is on the infinite horizon LQ setting,where the conditions for solution either stabilization or optimization can be formulated as two algebraic Riccati equations(AREs).The proposed approach leverages the integral reinforcement learning technique to iteratively solve the drift-coefficient-dependent stochastic ARE(SARE)and other indefinite ARE,without requiring knowledge of the system dynamics.A numerical example is given to demonstrate the effectiveness of the proposed algorithm.

关键词： Mean-field control Social optima Infinite horizon Reinforcement learning

On the half-quantized Hall conductance of massive surface electrons in magnetic topological insulator films

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Science China(Physics,Mechanics & Astronomy) 2024年第6期67卷 127-136页

作者： Rui Chen Shun-Qing shen Department of Physics The University of Hong KongHong Kong 999077China Department of Physics Hubei UniversityWuhan 430062China

In topological insulators,massive surface states resulting from local symmetry breaking were thought to exhibit a half-quantized Hall conductance,obtained from the low-energy effective model in an infinite Brillouin *** a lattice model,the surface band is composed of a combination of surface states and bulk *** massive surface states alone may not be enough to support an exact one-half quantized surface Hall conductance in a finite Brillouin zone and the whole surface band always gives an integer quantized Hall conductance as enforced by the TKNN *** explore this,we investigate the band structures of a lattice model describing the magnetic topological insulator film that supports the axion insulator,Chern insulator,and semi-magnetic topological insulator *** reveal that the gapped and gapless surface bands in the three phases are characterized by an integer-quantized Hall conductance and a half-quantized Hall conductance,*** propose an effective model to describe the three phases and show that the low-energy dispersion of the surface bands inherits from the surface Dirac *** gapped surface band manifests a nearly half-quantized Hall conductance at low energy near the center of Brillouin zone,but is compensated by another nearly half-quantized Hall conductance at high energy near the boundary of Brillouin zone because a single band can only have an integer-quantized Hall *** gapless band hosts a zero Hall conductance at low energy but is compensated by another half-quantized Hall conductance at high energy,and thus the half-quantized Hall conductance can only originate from the gapless ***,we calculate the layer-resolved Hall conductance of the *** conclusion suggests that the individual gapped surface band alone does not support the half-quantized surface Hall effect in a lattice model.

关键词： magnetic topological insulator Dirac equation half-quantized Hall conductance