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Atomistic study on the microscopic mechanism of grain boundary embrittlement induced by small dense helium bubbles in iron

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Nuclear Science and Techniques 2024年第3期35卷 84-95页

作者： Lei Peng Yong-Jie Sun Jing-Yi Shi Yi-Fei Liu Shang-Ming Chen Liu-Liu Li State Key Laboratory of Particle Detection and Electronics University of Science and Technology of ChinaHefei 230026China School of Nuclear Science and Technology University of Science and Technology of ChinaHefei 230027China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of ChinaChengdu 610213China

The helium bubbles induced by 14 MeV neutron irradiation can cause intergranular fractures in reduced activation ferritic martensitic steel,which is a candidate structural material for fusion *** order to elucidate the susceptibility of different grain boundaries(GBs)to helium-induced embrittlement,the tensile fracture processes of 10 types of GBs with and without helium bubbles in body-centered cubic(bcc)iron at the relevant service temperature of 600 K were investigated via molecular dynamics *** results indicate that in the absence of helium bubbles,the GBs studied here can be classified into two distinct categories:brittle GBs and ductile *** atomic scale analysis shows that the plastic deformation of ductile GB at high temperatures originates from complex plastic deformation mechanisms,including the Bain/Burgers path phase transition and deformation twinning,in which the Bain path phase transition is the most dominant plastic deformation ***,the presence of helium bubbles severely inhibits the plastic deformation channels of the GBs,resulting in a significant decrease in elongation at *** bubble-decorated GBs,the ultimate tensile strength increases with the increase in the misorientation ***,the coherent twin boundary∑3{112}was found to maintain relatively high fracture strength and maximum failure strain under the influence of helium bubbles.

关键词： Helium bubble Grain boundary Embrittlement Reduced activation ferritic martensitic steel Molecular dynamics Bain path

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Will the fibers of the future be considered fibers?

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National Science Review 2024年第10期11卷 15-17页

作者： Dewen Xu Ya Liu Hailiang Wang Wei Yan Changjun Jiang Meifang Zhu State Key Laboratory for Modification of Chemical Fibers and Polymer Materials College of Materials Science and Engineering Donghua University Key Laboratory of Embedded System and Service Computing Ministry of Education Tongji University Department of Computer Science and Technology Tongji University

Fiber materials are key materials that have changed human history and promoted the progress of human civilization. In ancient times, humans used feathers and animal skins for clothing, and later they widely employed natural fibers such as cotton, hemp, silk and wool to make fabrics(Fig. 1a). Chinese ancestors had mastered the art of natural fiber weaving as early as the Neolithic *** thousand years ago, people were already familiar with and adept at techniques for spinning natural fibers [1].

关键词： future will considered fibers

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Reinforcement Learning Navigation for Robots Based on Hippocampus Episode Cognition

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Journal of Bionic Engineering 2024年第1期21卷 288-302页

作者： Jinsheng Yuan Wei Guo Zhiyuan Hou Fusheng Zha Mantian Li Pengfei Wang Lining Sun State Key Laboratory of Robotics and System Harbin Institute of Technology(HIT)Harbin 150001China Shenzhen Academy of Aerospace Technology Shenzhen 518057China School of Mechanical and Electrical Engineering Lanzhou University of TechnologyLanzhou 730050China

Artificial intelligence is currently achieving impressive success in all ***,autonomous navigation remains a major challenge for *** learning is used for target navigation to simulate the interaction between the brain and the environment at the behavioral level,but the Artificial Neural Network trained by reinforcement learning cannot match the autonomous mobility of humans and *** hippocampus–striatum circuits are considered as key circuits for target navigation planning and *** paper aims to construct a bionic navigation model of reinforcement learning corresponding to the nervous system to improve the autonomous navigation performance of the *** ventral striatum is considered to be the behavioral evaluation region,and the hippocampal–striatum circuit constitutes the position–reward *** this paper,a set of episode cognition and reinforcement learning system simulating the mechanism of hippocampus and ventral striatum is constructed,which is used to provide target guidance for the robot to perform autonomous *** with traditional methods,this system reflects the high efficiency of learning and better Environmental *** research is an exploration of the intersection and fusion of artificial intelligence and neuroscience,which is conducive to the development of artificial intelligence and the understanding of the nervous system.

关键词： Episode cognition Reinforcement learning Hippocampus Robot navigation

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A Novel FBG Shape Sensor Based on Mechanical Model for Continuum Manipulator 10

A Novel FBG Shape Sensor Based on Mechanical Model for Conti...

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10th International Conference on Automation, robotics, and Applications, ICARA 2024

作者： Zhang, Yuxin Dong, Wei Yan, Zhiyuan Gao, Yongzhuo Harbin Institute of Technology State Key Laboratory of Robotics and System Harbin China

ISBN: (纸本)9798350394245

Fiber Bragg Gratings (FBG) are used widely for that it is small and sensitive. It is suitable to insert a sensor based on FBGs to some narrow cavities. At the same time, a slender continuum structure requires tiny sensors inside it. A multi-node differential curvature measurement sensor of FBG fiber is designed in this paper to realize temperature compensation. Considering the friction among FBG, driving wires, and niti tube and external forces applied on the end, a mechanical model about the FBG sensor and the continuum manipulator is proposed. At last, a linear interpolation method is used in the curvature estimation. Under the condition that there is no end resistance and only the bending moment and friction along the outer surface of the continuum generated by the steel wire driven by the motor the absolute measurement error of the position of the end of the continuum is 1.9mm. © 2024 IEEE.

关键词： Fiber Bragg gratings

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An efficient stiffness analysis model based on shear deformation theory for flexible skin shear variable-sweep wing

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Chinese Journal of Aeronautics 2024年第10期37卷 445-458页

作者： Yue BAI Guang YANG Hong XIAO Hongwei GUO Rongqiang LIU Bei LIU State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001China China Aerodynamics Research and Development Center Institute of High-Speed AerodynamicsMianyang 621000China

Fixed-wing aircraft cannot maintain optimal aerodynamic performance at different flight speeds. As a type of morphing aircraft, the shear variable-sweep wing(SVSW) can dramatically improve its aerodynamic performance by altering its shape to adapt to various flight *** order to achieve smooth continuous shear deformation, SVSW's skin adopts a flexible composite skin design instead of traditional aluminum alloy materials. However, this also brings about the non-linear difficulty in stiffness modeling and calculation. In this research, a new SVSW design and efficient stiffness modeling method are proposed. Based on shear deformation theory, the flexible composite skin is equivalently modeled as diagonally arranged nonlinear springs, simulating the elastic force interaction between the skin and the mechanism. By shear loading tests of flexible composite skin, the accuracy of this flexible composite skin modeling method is verified. The SVSW stiffness model was established, and its accuracy was verified through static loading tests. The effects of root connection, sweep angles, and flexible composite skin on the SVSW stiffness are analyzed. Finally, considering three typical flight conditions of SVSW: low-speed flow(Ma = 0.3,Re = 5.82 × 10^(6)), transonic flow(Ma = 0.9, Re = 3.44 × 10^(6)), and supersonic flow(Ma = 3,Re = 7.51 × 10^(6)), the stiffness characteristics of SVSW under flight conditions were *** calculated results guide the application of SVSW.

关键词： Shear variable-sweep wing(SVSW) Flexible composite skin Morphing mechanism Stiffness analysis Loading tests Structure

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Lunar Rover's Path Tracking Control Strategy Using Zero-Order Optimization Method

Lunar Rover's Path Tracking Control Strategy Using Zero-Orde...

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2024 IEEE International Conference on Control Science and systems Engineering, ICCSSE 2024

作者： Cao, Jianfei Wang, Yaobing Yu, Jiyang Beijing Institute of Spacecraft System Engineering Beijing Key Laboratory of Intelligent Space Robotic Systems Technology and Applications Beijing China Beijing Institute of Spacecraft System Engineering Beijing China

ISBN: (纸本)9798331517199

The development of lunar rovers is critical for human exploration of the lunar surface. These rovers will need to travel longer distances at higher speeds, and the efficient control of their paths is essential for mission success. Model Predictive Control (MPC) is a path tracking method with foresight and robustness, capable of predicting vehicle movement and solving optimization problems to minimize cost functions. However, the complexity of lunar environments necessitates simplified models, such as kinematic models, to reduce computational cost. The study proposes a special MPC method that uses zeroth-order gradient optimization to directly solve the nonlinear model and generate precise control commands, significantly reducing computational burden and meeting the computational cost requirements of lunar rover control. © 2024 IEEE.

关键词： Cost functions

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A Novel PLL Structure for Dynamic Stability Improvement of DFIG-based Wind Energy Generation systems During Asymmetric LVRT

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Journal of Modern Power systems and Clean Energy 2023年第4期11卷 1149-1164页

作者： Lei Guan Jun Yao State Key Laboratory of Power Transmission Equipment&System Security and New Technology School of Electrical EngineeringChongqing UniversityChongqing 400044China

The dynamic coupling effect,which is introduced by the dual-sequence phase-locked loops(PLLs)used in doublyfed induction generator(DFIG)based wind energy generation systems(WEGSs)during asymmetric low voltage ride-through(LVRT)in weak grid,needs *** order to study this new dynamic coupling effect,an equivalent two-degree-of-freedom(2-DOF)spring damper particle model is used in this paper to develop a small-signal model for the dual-sequence *** dynamic interaction between the positive-sequence(PS)and negative-sequence(NS)PLLs is ***,the impact of the dynamic coupling between the dual-sequence PLLs on the dynamic stability during the steady-state stage of an asymmetric fault is *** analysis results show that the dynamic coupling between the dual-sequence PLLs will cause drift in the frequency and damping for the PS and NS PLL *** will change the instability modal of the system and introduce the risk of dynamic ***,the effectiveness of existing control strategies for enhancing the dynamic stability will be ***,a novel PLL structure is designed to improve the dynamic stability of the system during the steady-state stage of an asymmetric *** effectiveness of the proposed strategy is verified by simulations and experiments.

关键词： Doubly-fed induction generator(DFIG) phaselocked loop(PLL) dynamic stability dynamic coupling weak grid asymmetric low-voltage ride through(LVRT)

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Review and prospects on the low-voltage Na_(2)Ti_(3)O_(7) anode materials for sodium-ion batteries

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Journal of Energy Chemistry 2024年第1期88卷 446-460,I0011页

作者： Jun Dong Yalong Jiang Ruxing Wang Qiulong Wei Qinyou An Xiaoxing Zhang Hubei Key Laboratory for High-efficiency Utilization of Solar Energy and Operation Control of Energy Storage System Hubei University of TechnologyWuhan 430068HubeiChina State Key Laboratory of New Textile Materials and Advanced Processing Technologies Wuhan Textile UniversityWuhan 430200HubeiChina Xiamen Key Laboratory of High-Performance Metals and Materials College of MaterialsXiamen UniversityXiamen 361005FujianChina State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070HubeiChina

Due to its low cost and natural abundance of sodium,Na-ion batteries(NIBs)are promising candidates for large-scale energy storage *** development of ultralow voltage anode materials is of great significance in improving the energy density of ***-voltage anode materials,however,are severely lacking in *** all the reported insertion oxides anodes,the Na_(2)Ti_(3)O_(7) has the lowest operating voltage(an average potential of 0.3 V ***^(+)/Na)and is less likely to deposit sodium,which has excellent potential for achieving NIBs with high energy densities and high *** significant progress has been made,achieving Na_(2)Ti_(3)O_(7) electrodes with excellent performance remains a severe *** paper systematically summarizes and discusses the physicochemical properties and synthesis methods of Na_(2)Ti_(3)O_(7).Then,the sodium storage mechanisms,key issues and challenges,and the optimization strategies for the electrochemical performance of Na_(2)Ti_(3)O_(7) are classified and further ***,remaining challenges and future research directions on the Na_(2)Ti_(3)O_(7) anode are *** review offers insights into the design of high-energy and high-safety NIBs.

关键词： Sodium-ion batteries Low-voltage anode materials Na_(2)Ti_(3)O_(7) Electrochemical performances Electrochemical mechanism

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Research progress of space non-pyrotechnic low-shock connection and separation technology(SNLT):A review

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Chinese Journal of Aeronautics 2022年第11期35卷 113-154页

作者： Honghao YUE Yifei YANG Yifan LU Fei YANG Jun WU Qi RUAN Zongquan DENG State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 15000lChina

Space missions have become diversified in recent years, where connection and separation devices play a crucial role as key components of various spacecraft. Traditional pyrotechnic devices have the advantages of large carrying capacity, rapid motion and functional reliability. However,their shortcomings such as great release shock, poor safety, unrepeatability and other prominent defects make them unsuitable for new generation spacecraft such as microsatellites to separate at low shock or lock repeatedly, etc. Therefore, it is necessary to develop space non-pyrotechnic low-shock connection and separation devices(SNLD) which are required for advanced aerospace missions. In this paper, the progress of the research on space non-pyrotechnic low-shock connection and separation technology(SNLT) is summarized and reviewed. Proceed from the principle of reducing shock for non-pyrotechnic devices, present studies are classified from the perspective of actuating technology and systematic designing methods. For non-pyrotechnic actuating techniques,according to different driving sources, the separation devices are classified into several main categories: electric, magnetic, gas and thermal actuating devices. The actuation principle and application prospect of separation techniques are introduced and the working process, dimension and mechanical properties of typical devices are compared and evaluated. For the systematic designing method, the common mechanism types of SNLDs are summarized according to the designing concept of reducing shock. Then connection configurations are classified according to the structural forms of connection devices, of which the principles, bearing capacities and general applications are discussed. This paper systematically summarizes the key problems, puts forward the future development trend of SNLT, and points out the breakthrough direction for related scholars.

关键词： Connection Low-shock Non-pyrotechnic Separation Space

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Improved calibration and 3D reconstruction for micro fringe projection profilometry

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Optics Express 2025年第6期33卷 13455-13471页

作者： Zhang, Chenfan Zhu, Dongchen Shi, Wenjun Wang, Lei Li, Jiamao Bionic Vision System Laboratory State Key Laboratory of Transducer Technology Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai200050 China University of Chinese Academy of Sciences Beijing100049 China

Micro fringe projection profilometry (MFPP) is a crucial three-dimensional measurement technology widely used in industrial inspection. As the system measurement accuracy is limited by calibration and reconstruction errors, this paper proposes a joint calibration of telecentric camera and projector, and develops noise-robust 3D reconstruction, ultimately forming a high-precision MFPP for microscopic object measurement. Specifically, the optimal parameters for the telecentric camera model are determined by constructing a virtual 3D calibration target, which circumvents the limitations that plane-based calibration methods often produce local optimal solutions. In response to the presence of phase errors, a method employing global homography is proposed to refine the projector pixel coordinates of feature points, thus enhancing the calibration accuracy of the projector. Furthermore, we integrate epipolar constraints into the reconstruction process, which helps eliminate noise points and optimizes the reconstruction results by constructing epipolar deviation. Extensive experiments demonstrate that our MFPP system can achieve micron-level measurement accuracy. © 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.

关键词： Profilometry

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