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Joining of SiO2f/SiO2 composite to Nb using Ag-Cu-In-Ti brazing alloys

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Journal of Materials Science & Technology 2020年第15期47卷 13-20页

作者： Bo Chen wen-jiang zou wen-wen Li Shi-Biao Wu Hua-Ping Xiong Xin Wu Welding and Plastic Forming Division Beijing Institute of Aeronautical MaterialsBeijing100095China

Three compositions of Ag-Cu-In-Ti system brazing alloys were designed for joining SiO2 f/SiO2 ceramic composite to Nb *** wettability of the three alloys on the composite was studied with the sessile drop *** results showed that after heating at 1073 K for 30 min,they exhibited contact angles of 74°,83° and 86°,*** brazing alloys were fabricated into foils by rapid solidification *** the three brazing filler alloys the joints brazed with AgCu-10 In-5 Ti at 1073 K for 10 min presented the maximum average shear strength of 30.9 *** the brazing process the active element Ti diffused strongly from the filler alloy to the composite surface and a reaction layer with a thickness of 2-3 μm was *** metallurgical bonding was also achieved at the Nb *** interface structure of the joint brazed with the AgCu-10 In-5 Ti alloy can be described as the following sequence:SiO2 f/SiO2→SiO2+Cu3 Ti3 O→SiO2+TiO+Ti5 Si4→Ag(s,s)+(Cu-Ti)→***,for the filler alloy with 4.0 wt% Ti content the joint strength was only 15.8 MPa.

关键词： Joining Composites Strength SiO2

Copper foils with gradient structure in thickness direction and different roughnesses on two surfaces fabricated by double rolling

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International Journal of Minerals,Metallurgy and Materials 2013年第12期20卷 1170-1175页

作者： Xi-yong Wang Xue-feng Liu wen-jiang zou Jian-xin Xie School of Materials Science and Engineering University of Science and Technology Beijing Beijing Laboratory of Metallic Materials and Processing for Modern Transportation University of Science and Technology Beijing Key Laboratory for Advanced Materials Processing Ministry of Education) University of Science and Technology Beijing

Copper foils with gradient structure in thickness direction and different roughnesses on two surfaces were fabricated by double rolling. The two surface morphologies of double-rolled copper foils are quite different, and the surface roughness values are 61 and 1095 nm, respectively. The roughness value of matt surface can meet the requirement for bonding the resin matrix with copper foils used for flexible printed circuit boards, thus may omit traditional roughening treatment; the microstructure of double-rolled copper foils demonstrates an obviously asymmetric gradient feature. From bright surface to matt surface in thickness direction, the average grain size first increases from 2.3 to 7.4 μm and then decreases to 3.6 μm; compared with conventional rolled copper foils, the double-rolled copper foils exhibit a remarkably increased bending fatigue life, and the increased range is about 16.2%.

关键词： copper foils rolling surfaces gradient structure fatigue of materials

Process-driven susceptibility assessment of glacial lake outburst debris flow in the Himalayas under climate change

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Advances in Climate Change Research 2024年第3期15卷 500-514页

作者： Bin ZHOU Qiang zou Hu jiang Tao YANG wen-Tao ZHOU Si-Yu CHEN Hong-Kun YAO Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China University of Chinese Academy of Sciences Beijing 100049China School of Environment and Resource Southwest University of Science and TechnologyMianyang 621010China

Global warming is causing glaciers to retreat and glacial lakes to expand in the Himalayas,which amplifies the risk of glacial lake outburst debris flows(GLODFs)and poses a significant threat to downstream lives and ***,the complex interplay between GLODF occurrences and associated indicators,coupled with the lack of a comprehensive susceptibility indicator system that considers the entire GLODF process,presents a substantial challenge in assessing GLODF susceptibility in the *** study proposes a process-driven GLODF susceptibility assessment indicator system responding to climate change that considers the complete process of GLODF formation,incorporating relevant parameters about upstream,themselves,and downstream of glacial ***,to mitigate subjective factors associated with traditional evaluation methods,we developed three novel hybrid machine-learning models by integrating classic machine-learning algorithms with the whale optimization algorithm(WOA)to delineate the distribution of GLODF susceptibility in the *** the hybrid models effectively predicted the GLODFs occurrence,with the WOA-SVC model demonstrating the highest prediction *** 34%of the catchments exhibit high and very high susceptibility levels,primarily concentrated along the north and south sides of the Himalayan ridge,particularly in the eastern and central *** capturing the physical formation process of hazards,such as topographic potential(highest relative importance value of 40%),can precisely identify GLODF.A total of 128 catchments pose potential transboundary threats,with 24 classified as having a very high susceptibility level and 25 as having a high susceptibility ***,the border region between China and Nepal is a prominent hotspot for transboundary threats of *** findings can provide valuable clues for disaster prevention,mitigation,and cross-border coordination in the Himalayas.

关键词： Glacial lake outburst debris flow Susceptibility assessment Climate change Himalayas

Energy-based Directional Pilot Protection for Distribution Networks with IBDGs Considering Unmeasured Load Switching

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 139-150页

作者： Chenghan Zhou Guibin zou Shuo Zhang Xuhui wen Key Laboratory of Power System Intelligent Dispatch and Control of Ministry of Education Shandong UniversityJinan 250061China

Inverter-based distributed generations(IBDGs)are the main approach to utilizing clean energy in distribution networks(DNs).Compared with synchronous source,fault response of IBDG is very *** a result,in DNs with high penetration of IBDGs,legacy protection schemes will no longer be *** this paper,an energy-based directional pilot protection scheme suitabie for DNs with IBDGs is *** scheme considers the large range of phase angle caused by IBDG integration and uses improved energy polarity criterion to determine fault *** addition,magnitude of energy is used to distinguish between faults and load switching to overcome maloperation of directional pilot protection caused by internal unmeasured load *** proposed scheme first uses local measured information to determine fault direction sign and then exchanges the direction sign with the remote *** scheme does not require high-bandwidth communication and strict data synchronization,so it can be implemented at a low ***,simulation studies verify effectiveness of the proposed scheme.

关键词： Distribution network energy polarity inverterbased distributed generation pilot protection unmeasured load

General formalism for dirty extreme-mass-ratio inspirals

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Science China(Physics,Mechanics & Astronomy) 2024年第7期67卷 22-29页

作者： Ye jiang wen-Biao Han Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou 310024China Shanghai Frontiers Science Center for Gravitational Wave Detection Shanghai 200240China

Detecting the environment around the supermassive black holes and tests of general relativity are important applications of extreme-mass-ratio inspirals(EMRIs).There is still a challenge to efficiently describe various“dirty”impacts on the inspirals,such as dark matter,gas,dipole radiation,and electromagnetic *** this study,we find the inherent linearity of the asymptotic solution of the inhomogeneous Teukolsky *** the basis of this property,we completely decouple the factors of the perturber and the background spacetime in the energy fluxes and *** the new decoupling form,the waveforms of EMRIs with non-geodesic motion in Kerr spacetime can be conveniently *** will help to resolve the environment(including gas,field,dark matter,electromagnetic interaction)around supermassive black holes and test general relativity.

关键词： gravitational wave Teukolsky equation extreme-mass-ratio inspirals

The radiative decay of scalar glueball from lattice QCD

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Science China(Physics,Mechanics & Astronomy) 2024年第11期67卷 63-74页

作者： Jintao zou Long-Cheng Gui Ying Chen wen Qin Jian Liang Xiangyu jiang Yibo Yang Department of Physics Hunan Normal University and Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of EducationChangsha 410081China Synergetic Innovation Center for Quantum Effects and Applications(SICQEA) Hunan Normal UniversityChangsha 410081China Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China Key Laboratory of Atomic and Subatomic Structure and Quantum Control(MOE) Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of MatterInstitute of Quantum MatterSouth China Normal UniversityGuangzhou 510006China Guangdong-Hong Kong Joint Laboratory of Quantum Matter Guangdong Provincial Key Laboratory of Nuclear ScienceSouthern Nuclear Science Computing CenterSouth China Normal UniversityGuangzhou 510006China CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China International Centre for Theoretical Physics Asia-Pacific Beijing 100190China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou 310024China

We perform the first lattice QCD study on the radiative decay of the scalar glueball to the vector mesonφin the quenched *** calculations are carried out on three gauge ensembles with different lattice spacings,which enable us to do the continuum *** first revisit the radiative J/ψdecay into the scalar glueball G and obtain the partial decay widthΓ(J/ψ→γG)=0.578(86)keV and the branching fraction Br(J/ψ→γG)=6.2(9)×10^(-3),which are in agreement with the previous lattice *** then extend the similar calculation to the process G→γφand get the partial decay widthΓ(G→γφ)=0.074(47)keV,which implies that the combined branching fraction of J/ψ→γG→γγφis as small as O(10^(-9))such that this process is hardly detected by the BESⅢexperiment even with the large J/ψsample of O(10^(10)).With the vector meson dominance model,the two-photon decay width of the scalar glueball is estimated to beΓ(G→γγ)=0.53(46)e V,which results in a large stickiness S(G)~O(10^(4))of the scalar glueball by assuming the stickiness of f_(2)(1270)to be one.

关键词： lattice QCD scalar glueball radiative decay

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Distributed dynamic task allocation for unmanned aerial vehicle swarm systems:A networked evolutionary game-theoretic approach

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Chinese Journal of Aeronautics 2024年第6期37卷 182-204页

作者： Zhe ZHANG Ju jiang Haiyan XU wen-An ZHANG College of Automation Engineering Nanjing University of Aeronautics and AstronauticsNanjing 211106China College of Economics and Management Nanjing University of Aeronautics and AstronauticsNanjing 211106China College of Information Engineering Zhejiang University of TechnologyHangzhou 310023China

Task allocation is a key aspect of Unmanned Aerial Vehicle(UAV)swarm collaborative *** an continuous increase of UAVs’scale and the complexity and uncertainty of tasks,existing methods have poor performance in computing efficiency,robustness,and realtime allocation,and there is a lack of theoretical analysis on the convergence and optimality of the *** paper presents a novel intelligent framework for distributed decision-making based on the evolutionary game theory to address task allocation for a UAV swarm system in uncertain scenarios.A task allocation model is designed with the local utility of an individual and the global utility of the ***,the paper analytically derives a potential function in the networked evolutionary potential game and proves that the optimal solution of the task allocation problem is a pure strategy Nash equilibrium of a finite strategy ***,a PayOff-based Time-Variant Log-linear Learning Algorithm(POTVLLA)is proposed,which includes a novel learning strategy based on payoffs for an individual and a time-dependent Boltzmann *** former aims to reduce the system’s computational burden and enhance the individual’s effectiveness,while the latter can ensure that the POTVLLA converges to the optimal Nash equilibrium with a probability of *** simulation results show that the approach is optimal,robust,scalable,and fast adaptable to environmental changes,even in some realistic situations where some UAVs or tasks are likely to be lost and increased,further validating the effectiveness and superiority of the proposed framework and algorithm.

关键词： Task allocation Unmanned Aerial Vehicles(UAV) Game theory Log-linear learning Distributed optimization algorithm

Study on a conical bearing for acceleration-sensitive equipment

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Earthquake Engineering and Engineering Vibration 2024年第1期23卷 103-128页

作者： Pang Hui Xu wen Dai Junwu jiang Tao Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering MechanicsChina Earthquake AdministrationHarbin 150080China Key Laboratory of Earthquake Disaster Mitigation Ministry of Emergency ManagementHarbin 150080China School of Civil Engineering and Transportation Beihua UniversityJilin 132013China

Seismic isolation effectively reduces seismic demands on building structures by isolating the superstructure from ground vibrations during ***,isolation strategies give less attention to acceleration-sensitive systems or ***,as the isolation layer’s displacement grows,the stiffness and frequency of traditional rolling and sliding isolation bearings increases,potentially causing self-centering and resonance *** a result,a new conical pendulum bearing has been selected for acceleration-sensitive equipment to increase self-centering capacity,and additional viscous dampers are incorporated to enhance system ***,the theoretical formula for conical pendulum bearings is supplied to analyze the device’s dynamic parameters,and shake table experiments are used to determine the proposed device’s isolation efficiency under various *** to the test results,the newly proposed devices have remarkable isolation performance in terms of minimizing both acceleration and displacement ***,a numerical model of the isolation system is provided for further research,and the accuracy is demonstrated by the aforementioned experiments.

关键词： seismic isolation acceleration-sensitive equipment the conical pendulum bearing shake table tests isolation performance,numerical model

Disentangling distinct Cu surface sites for electrocatalytic CO_(2)-to-CO and CO-to-C_(2+)conversion

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Science China Chemistry 2024年第4期67卷 1047-1048页

作者： Kun jiang wen-Bin Cai Interdisciplinary Science Research Centre School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Collaborative Innovation Center of Chemistry for Energy MaterialsDepartment of ChemistryFudan UniversityShanghai 200438China

Electrochemical CO_(2)reduction reaction(CO_(2)RR)is a promising strategy to curb anthropogenic carbon emissions,for which intermittent renewable electricity could be stored as chemical energy within carbon-based fuel... 详细信息

关键词： carbon Electrochemical surface