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Robot trajectory planning for autonomous 3D reconstruction of cockpit in aircraft final assembly testing

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Chinese Journal of Aeronautics 2024年第3期37卷 332-350页

作者： Yanzhe WANG Zemin PAN Qian YANG Changxi DENG Yanding WEI The State key Laboratory of Fluid Power and Mechatronic Systems School of Mechanical EngineeringZhejiang UniversityHangzhou 310027China School of Information Science and Engineering NingboTech UniversityNingbo 315100China AVIC Xi’an Aircraft Industry(Group)Company Ltd. Xi’an 710089China key Laboratory of Advanced Manufacturing Technology of Zhejiang Province School of Mechanical EngineeringZhejiang UniversityHangzhou 310027China

The trend towards automation and intelligence in aircraft final assembly testing has led to a new demand for autonomous perception of unknown cockpit operation scenes in robotic collaborative airborne system *** address this demand,a robotic automated 3D reconstruction cell which enables to autonomously plan the robot end-camera’s trajectory is developed for image acquisition and 3D modeling of the cockpit operation scene.A continuous viewpoint path planning algorithm is proposed that incorporates both 3D reconstruction quality and robot path quality into optimization *** metrics for viewpoint position paths and orientation paths are introduced together for the first time in 3D *** ensure safe and effective movement,two spatial constraints,Domain of View Admissible Position(DVAP)and Domain of View Admissible Orientation(DVAO),are implemented to account for robot reachability and collision *** using diffeomorphism mapping,the orientation path is transformed into 3D,consistent with the position *** orientation and position paths can be optimized in a unified framework to maximize the gain of reconstruction quality and path smoothness within DVAP and *** reconstruction cell is capable of automatic data acquisition and fine scene modeling,using the generated robot C-space *** and physical scene experiments have confirmed the effectiveness of the proposed method to achieve highprecision 3D reconstruction while optimizing robot motion quality.

关键词： Aircraft assembly testing Aircraft cockpit 3D modeling Camera viewpoint Robot trajectory planning

Slicing of large-size single crystals by ultrafast laser with external stress assistance

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CHINESE OPTICS LETTERS 2024年第8期22卷 081601-081601页

作者： Wang, Lifeng Liu, Lili Wang, Yinan Li, Xun Li, Chenchen Li, Ming Chinese Acad Sci Xian Inst Opt & Precis Mech State Key Lab Transient Opt & Photon Xian 710119 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China

The existing single-crystal slicing techniques result in significant material wastage and elevate the production cost of premium-quality thin slices of crystals. Here we report (for the first time, to our knowledge) an approach for vertical slicing of large-size single-crystal gain materials by ultrafast laser. By employing aberration correction techniques, the optimization of the optical field distribution within the high-refractive-index crystal enables the achievement of a continuous laser-modified layer with a thickness of less than 10 mu m, oriented perpendicular to the direction of the laser direction. The compressed focal spot facilitates crack initiation, enabling propagation under external forces, ultimately achieving the successful slicing of a Phi 12 mm crystal. The surface roughness of the sliced Yb:YAG is less than 2.5 mu m. The results illustrate the potential of low-loss slicing strategy for single-crystal fabrication and pave the way for the future development of thin disk lasers.

关键词： single-crystal gain materials ultrafast laser slicing YAG aberration correction FEMTOSECOND LASER DEFORMATION MECHANISM YAG

Causal temporal graph attention network for fault diagnosis of chemical processes

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Chinese Journal of Chemical Engineering 2024年第6期70卷 20-32页

作者： Jiaojiao Luo Zhehao Jin Heping Jin Qian Li Xu Ji Yiyang Dai School of Chemical Engineering Sichuan UniversityChengdu 610065China china Three Gorges Corporation Beijing 100038China

Fault detection and diagnosis(FDD)plays a significant role in ensuring the safety and stability of chemical *** the development of artificial intelligence(AI)and big data technologies,data-driven approaches with excellent performance are widely used for FDD in chemical ***,improved predictive accuracy has often been achieved through increased model complexity,which turns models into black-box methods and causes uncertainty regarding their *** this study,a causal temporal graph attention network(CTGAN)is proposed for fault diagnosis of chemical processes.A chemical causal graph is built by causal inference to represent the propagation path of *** attention mechanism and chemical causal graph were combined to help us notice the key variables relating to fault *** in the Tennessee Eastman(TE)process and the green ammonia(GA)process showed that CTGAN achieved high performance and good explainability.

关键词： Chemical processes Safety Fault diagnosis Causal discovery Attention mechanism Explainability

Size-Dependent Analysis of Piezoelectric–Elastic Bilayer Microbeams Based on General Strain Gradient Theory

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Acta Mechanica Solida Sinica 2024年第4期37卷 622-633页

作者： Kanghui Wu Shenjie Zhou Zhenjie Zhang Juanjuan Li School of Mechanical Engineering Shandong UniversityJinan250061China key Laboratory of High Efficiency and Clean Mechanical Manufacture Ministry of EducationShandong UniversityJinan250061China

The classical piezoelectric theory fails to capture the size-dependent electromechanical coupling behaviors of piezoelectric microstructures due to the lack of material length-scale *** study presents the constitutive relations of a piezoelectric material in terms of irreducible transversely isotropic tensors that include material length-scale *** these relations and the general strain gradient theory,a size-dependent bending model is proposed for a bilayer cantilever microbeam consisting of a transversely isotropic piezoelectric layer and an isotropic elastic *** solutions are provided for bilayer cantilever microbeams subjected to force load and voltage *** proposed model can be simplified to the model incorporating only partial strain gradient *** study examines the effect of strain gradient by comparing the normalized electric potentials and deflections of different *** results show that the proposed model effectively captures size effects in piezoelectric microbeams,whereas simplified models underestimate size effects due to ignoring partial strain gradient effects.

关键词： Size dependency Piezoelectric microbeam Size effect Strain gradient effect

Multi-performance evaluation of high-throughput accelerated corrosion test for high-strength low-alloy 921A steel

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Journal of Iron and Steel research International 2024年第5期31卷 1260-1278页

作者： Cong-cong Du Ming-hua Qin Zhan-fang Wu Dong-ling Li Lei Zhao Xiang-yang Li Hai-zhou Wang Beijing Advanced Innovation Center for Materials Genome Engineering National Center for Materials Service SafetyUniversity of Science and Technology BeijingBeijing100083China china Iron and Steel research Institute Group Co. Ltd.Beijing100081China Beijing Advanced Innovation Center for Materials Genome Engineering Central Iron and Steel Research InstituteBeijing100081China

The corrosion behavior of high-strength low-alloy 921A steel in a simulated marine atmospheric environment was studied using a high-throughput experimental *** corrosion behavior,corrosion morphology,and corrosion products of 921A steels were analyzed using various techniques,including corrosion mass loss method,polarization curve,white-light interferometry,scanning electron microscopy,energy-dispersive spectrometry,microbeam X-ray fluorescence spectrometry,X-ray diffraction technique,and X-ray photoelectron *** test results indicated that 921A steel exhibits better corrosion resistance than Q450NQR1 steel in simulated harsh atmospheric environments,as evidenced by a lower corrosion mass loss rate throughout the corrosion *** corrosion products of both steels consisted ofα-FeOOH,Fe_(3)O_(4),andγ-FeOOH,withα-FeOOH being more prevalent in the rust layer of 921A steel than in Q450NQR1 *** inner rust layer of 921A steel also exhibited an appositional enrichment region of Cr,Ni,Mo,and V,leading to its superior corrosion resistance compared to that of Q450NQR1 *** efficacy of high-throughput accelerated corrosion experimental methods was highlighted for evaluating the corrosion resistance of steel materials in harsh environmental *** findings suggest that 921A steel exhibits better corrosion resistance compared to Q450NQR1 steel and has the potential to be more suitable in harsh marine atmospheric *** characterization of the rust layer structures and composition reveals the parallel enrichment of certain elements in the inner rust layer of 921A steel,which enhances its corrosion resistance.

关键词： Atmospheric corrosion High-throughput experimental method High-strength low-alloy steel Corrosion characteristics Rust layer Element enrichment

Cyber-Syndrome:Concept,Theoretical Characterization,and Control Mechanism

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Tsinghua Science and Technology 2024年第3期29卷 721-735页

作者： Feifei Shi Huansheng Ning Liming Chen Sahraoui Dhelim School of Computer and Communication Engineering University of Science and Technology BeijingBeijing 100083China Faculty of Computing Ulster UniversityNewtownabbeyBT370QBUK School of Computer Science University College DublinDublinD04 V1W8Ireland

The prevalence of social media and mobile computing has led to intensive user engagement in the emergent Cyber-Physical-Social-Thinking(CPST)***,the easy access,the lack of governance,and excessive use has generated a raft of new behaviors within CPST,which affects users’physical,social,and mental *** this paper,we conceive the Cyber-Syndrome concept to denote the collection of cyber disorders due to excessive or problematic Cyberspace interactions based on CPST *** we characterize the Cyber-Syndrome concept in terms of Maslow’s theory of Needs,from which we establish an in-depth theoretical understanding of Cyber-Syndrome from its etiology,formation,symptoms,and ***,we propose an entropy-based Cyber-Syndrome control mechanism for its computation and *** goal of this study is to give new insights into this rising phenomenon and offer guidance for further research and development.

关键词： Cyber-Syndrome cyber-physical systems Cyber-Physical-Social-Thinking(CPST)space Maslow’sHierarchy of Needs entropy

Exploring the Core-shell Structure of BaTiO3-based Dielectric Ceramics Using Machine Learning Models and Interpretability Analysis

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Journal of Wuhan University of Technology(Materials Science) 2024年第3期39卷 561-569页

作者：孙家乐 XIONG Peifeng 郝华 LIU Hanxing State key Laboratory of Advanced Technology for Materials Synthesis and Processing School of Material Science and EngineeringInternational School of Material Science and EngineeringWuhan University of TechnologyWuhan 430070China Sanya Science and Education Innovation Park Wuhan University of TechnologySanya 572000China Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory Xianhu Hydrogen ValleyFoshan 528200China

A machine learning(ML)-based random forest(RF)classification model algorithm was employed to investigate the main factors affecting the formation of the core-shell structure of BaTiO_(3)-based ceramics and their interpretability was analyzed by using Shapley additive explanations(SHAP).An F1-score changed from 0.8795 to 0.9310,accuracy from 0.8450 to 0.9070,precision from 0.8714 to 0.9000,recall from 0.8929 to 0.9643,and ROC/AUC value of 0.97±0.03 was achieved by the RF classification with the optimal set of features containing only 5 features,demonstrating the high accuracy of our model and its high *** the interpretability analysis of the model,it was found that the electronegativity,melting point,and sintering temperature of the dopant contribute highly to the formation of the core-shell structure,and based on these characteristics,specific ranges were delineated and twelve elements were finally obtained that met all the requirements,namely Si,Sc,Mn,Fe,Co,Ni,Pd,Er,Tm,Lu,Pa,and *** the process of exploring the structure of the core-shell,the doping elements can be effectively localized to be selected by choosing the range of features.

关键词： machine learning BaTiO_(3) core-shell structure random forest classifier

Distributed Cooperative Secondary Voltage Control in an Unbalanced Microgrid

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 222-234页

作者： Xiangzhen Yang Haixi Zhao Mengke Duan Yan Du Haining Wang Jian Zhang School of Electrical Engineering and Automation Hefei University of TechnologyHefei 23009China

The negative-sequence reactive power-conductance(Q^(−)-G) droop control strategy is a conventional method to compensate for the output unbalanced voltages in an islanded ***, the conflict between unbalanced voltage compensation and negative-sequence reactive power sharing, caused bythe impedance mismatching of distribution lines and distributedgenerators, has not been solved only by Q^(−)-G droop *** this paper, a distributed cooperative secondary unbalancedvoltage control strategy is proposed to decrease the outputvoltage unbalance factor (VUF) of each droop-controlled DG,as well as to further enhance the negative-sequence reactivepower sharing effectiveness among DGs by properly shiftingup and down the Q^(−)-G droop characteristics of each *** algorithm for adaptive VUF weight coefficient is proposedto better suppress VUF under severe imbalance ***, a negative-sequence small-signal model of an MGunder an unbalanced condition, considering the communicationdelay time of the proposed SUVC, is established to analyze thesystem’s stability and transient performance under the influenceof some critical parameters. Finally, the effectiveness of theproposed strategy is validated by the simulation results froma real-time emulator of StarSim HIL.

关键词： Distributed cooperative control MG negativesequence reactive power starsim real-time platform time delay voltage unbalance compensation

Simulation of gas-solid flow characteristics of the circulating fluidized bed boiler under pure-oxygen combustion conditions

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Chinese Journal of Chemical Engineering 2024年第6期70卷 9-19页

作者： Kaixuan Gao Xiwei Ke Bingjun Du Zhenchuan Wang Yan Jin Zhong Huang Yanhong Li Xuemin Liu key Laboratory of Special Equipment Safety and Energy-Saving for State Market Regulation China Special Equipment Inspection&Research InstituteBeijing 100029China Department of Energy and Power Engineering Tsinghua UniversityBeijing 100084China School of Electrical and Power Engineering Taiyuan University of TechnologyTaiyuan 030024China

Under the pressure of carbon neutrality,many carbon capture,utilization and storage technologies have witnessed rapid development in the recent years,including oxy-fuel combustion(OFC)***,the conventional OFC technology usually depends on the flue gas recirculation system,which faces significant investment,high energy consumption,and potential low-temperature corrosion *** these deficiencies,the direct utilization of pure oxygen to achieve particle fluidization and fuel combustion may reduce the overall energy consumption and CO_(2)-capture *** this paper,the fundamental structure of a self-designed 130 t·h^(-1) pure-oxygen combustion circulating fluidized bed(CFB)boiler was provided,and the computational particle fluid dynamics method was used to analyze the gas-solid flow characteristics of this new-concept boiler under different working *** results indicate that through the careful selection of design or operational parameters,such as average bed-material size and fluidization velocity,the pure-oxygen combustion CFB system can maintain the ideal fluidization state,namely significant internal and external particle ***,the contraction section of the boiler leads to the particle backflow in the lower furnace,resulting in the particle suspension concentration near the wall region being higher than that in the center ***,the upper furnace still retains the classic core-annulus flow *** addition to increasing solid circulation rate by reducing the average bed-material size,altering primary gas ratio and bed inventory can also exert varying degrees of influence on the gas-solid flow characteristics of the pure-oxygen combustion CFB boiler.

关键词： Circulating fluidized bed Pure-oxygen combustion Gas-solid flow characteristics Simulation CO_(2)capture