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Layered metastructure containing freely-designed local resonators for wave attenuation

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Defence Technology（防务技术） 2024年第2期32卷 23-31页

作者： Yu Li Huguang He jiang feng Hailong Chen fengnian Jin Hualin Fan State Key Laboratory for Disaster Prevention&Mitigation of Explosion&Impact Army Engineering University of PLANanjing 210007China Rocket Force University of Engineering Xi'an 710025China Henan International Joint Laboratory of Dynamics of Impact and Disaster of Engineering Structures Department of Civil EngineeringNanyang Institute of TechnologyNanyang 473004China Guangxi Key Laboratory of Disaster Prevention and Engineering Safety and Key Laboratory of Disaster Prevention and Structural Safety of Ministry of EducationCollege of Civil Engineering and ArchitectureGuangxi UniversityNanning 530004China Research Center of Lightweight Structures and Intelligent Manufacturing State Key Laboratory of Mechanics and Control of Mechanical StructuresNanjing University of Aeronautics and AstronauticsNanjing 210016China

Combining periodic layered structure with three-dimensional cylindrical local resonators,a hybrid metastructure with improved wave isolation ability was designed and investigated through theoretical and numerical *** metastructure is composed of periodic rubber layers and concrete layers embedded with three-dimensional resonators,which can be freely designed with multi local resonant frequencies to attenuate vibrations at required frequencies and widen the attenuation *** metastructure can also effectively attenuate seismic *** with layered rubber-based structures,the metastructure has more excellent wave attenuation effects with greater attenuation and wider bandgap.

关键词： Layered metastructure Local resonator Wave attenuation

Collaborative positioning for swarms:A brief survey of vision,LiDAR and wireless sensors based methods

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Defence Technology（防务技术） 2024年第3期33卷 475-493页

作者： Zeyu Li Changhui jiang Xiaobo Gu Ying Xu feng zhou Jianhui Cui College of Geodesy and Geomatics Shandong University of Science and TechnologyQingdao266590China Geoloc Laboratory Universite Gustave EiffelParis77454France School of Automation Guangdong University of TechnologyGuangzhou510006China

As positioning sensors,edge computation power,and communication technologies continue to develop,a moving agent can now sense its surroundings and communicate with other *** receiving spatial information from both its environment and other agents,an agent can use various methods and sensor types to localize *** its high flexibility and robustness,collaborative positioning has become a widely used method in both military and civilian *** paper introduces the basic fundamental concepts and applications of collaborative positioning,and reviews recent progress in the field based on camera,LiDAR(Light Detection and Ranging),wireless sensor,and their *** paper compares the current methods with respect to their sensor type,summarizes their main paradigms,and analyzes their evaluation ***,the paper discusses the main challenges and open issues that require further research.

关键词： Collaborative positioning Vision LiDAR Wireless sensors Sensor fusion

Effect of turbulent fluctuation on the ignition of millimeter particle:Experimental studies and numerical modelling with a new correlation of nusselt number Author links open overlay panel

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Particuology 2024年第8期91卷 168-175页

作者： Lele feng Jie Liu Haihui Xin Liangliang jiang Yuxin Wu Saeideh Babaee jiangsu Key Laboratory of Coal-based Greenhouse Gas Control and Utilization China University of Mining and TechnologyXuzhou221008China School of Safety Engineering China University of Mining and TechnologyXuzhou221116China Key Laboratory of Hubei Province for Coal Conversion and New Carbon Materials Wuhan University of Science and TechnologyWuhan430000China Department of Chemical and Petroleum Engineering University of CalgaryCalgaryAlbertaCanada Department of Energy and Power Engineering Tsinghua UniversityBeijing100084China Department of Chemical and Metallurgical Engineering University of the WitwatersrandJohannesburgSouth Africa

Understanding the influencing mechanism of turbulent fluctuation on the ignition characteristics of millimeter coal particles is *** this work,to study the effect of turbulent fluctuation on ignition time,millimeter coal particles are subjected to a specific flow field,generated in a furnace with symmetric fans.A one-dimensional model with the new proposed correlation and the Ranz-Marshall(R-M)correlation for Nu(Nusselt number)is established to simulate the coal ignition *** addition,the effects of fan speed,temperature,particle diameter,particle distance and coal type on the ignition time are *** is found that an increase in fan speed from 0 to 3000 rpm leads to a particle Reynolds number Re_(p)increase from 0 to 22.5,and a turbulent particle Reynolds number Re_(t)*increase from 0 to *** a consideration of the fluctuation effect,the new correlation of Nu gives a better prediction of ignition time compared to the R-M ***,the ignition time is revealed to decrease with an increasing fan speed and an elevating *** the ignition time shows merely an initial boost with enlarging particle distance,it exhibits a linearity with the term of particle diameter dp1.3-1.7 and Reynolds numbers(Nu*/Nu)-0.6(Nu*is turbulent Nusselt number).Based on this relationship,the difference of predicted ignition time is calculated at different Re_(p)and Re_(t)*.It is shown that at low Re_(p)or high Re_(t)*values,the new correlation should substitute for the R-M correlation.

关键词： Turbulent fluctuation Particle heat transfer Empirical correlation Coal ignition

Fabrication of AZ31/Mg3Y Composites with Excellent Strength and Plasticity via Accumulated Rolling Bonding and Diffusion Annealing

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Acta Metallurgica Sinica(English Letters) 2024年第2期37卷 339-352页

作者： Yang feng Wenhuan Chen Zheng Xu Weijun He Bin jiang Fusheng Pan College of Materials Science and Engineering Chongqing UniversityChongqing400044China International Joint Laboratory for Light Alloys(Ministry of Education) Chongqing UniversityChongqing400044China

AZ31/Mg3Y composites with a layer thickness of 100-200μm were fabricated by accumulated rolling bonding(ARB),which was followed by diffusion annealing at 300℃ for 0-32 *** interface layer,containing numerous Al-Y precipitates,is formed in the Mg3Y layer that is adjacent to the interface as a result of Al diffusing from the AZ31 layers into the Mg3Y *** thickness of the interface layer gets increased and more precipitates are formed in the interface layer with the extension of the annealing *** microhardness of the AZ31 and Mg3Y layer decreases firstly and then reaches a stable value,while the microhardness of the interface layer increases gradually with the extension of the annealing *** AZ31/Mg3Y composites exhibit equivalent strength but increased ductility after diffusion annealing,in comparison to the as-rolled AZ31/Mg3Y *** addition,the AZ31/Mg3Y composites after annealing always present higher strength and ductility than AZ31/AZ31 composite,which was fabricated by the same process as that for the AZ31/Mg3Y ***-deformation induced strengthening also plays an important role in the excellent strength and ductility of the annealed AZ31/Mg3Y *** study can provide a direction for improving the plasticity and strength of magnesium alloys synergistically.

关键词： AZ31/Mg3Y composite Accumulated rolling bonding Diffusion annealing Precipitates Strengthening

Recent advances in visible light-mediated chemical transformations of enaminones

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Chinese Chemical Letters 2024年第2期35卷 4-15页

作者： Yu Han Liyun Zhou Chengyu wang Shangti feng Rong Ma Jie-Ping wan College of Chemistry and Chemical Engineering Jiangxi Normal UniversityNanchang 330022China School of Chemistry and Chemical Engineering Linyi UniversityLinyi 276000China Linyi Sanfeng Chemical Co. Ltd.Linyi 276000China

Enaminones,which possesses both the nucleophilic enamine as well as electrophilic enone structures,are well known versatile building blocks in organic ***,visible light-mediated reactions have emerged as useful synthetic strategy with enhanced *** the last decade,various photochemical transformations of enaminones have been developed to construct cyclic or acyclic *** this review,we describe the recent advances in visible light-mediated chemical transformations of *** discussion on the reaction mechanism of the related reactions is given to provide guide to the ***,a summary on the existing challenges and the future outlook towards the development of practical photocatalytic reactions of enaminones is also presented.

关键词： Enaminone Visible light C-H functionalization C=C bond cleavage Cyclization Multicomponent reactions

Committed-programming reductions: formalizations,implications and relations

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Science China(Information Sciences) 2024年第10期67卷 151-171页

作者： jiang ZHANG Yu YU Dengguo feng Shuqin FAN Zhenfeng ZHANG State Key Laboratory of Cryptology Department of Computer Science and Engineering Shanghai Jiao Tong University Trusted Computing and Information Assurance Laboratory Institute of SoftwareChinese Academy of Sciences

In this work, we introduce a class of black-box(BB) reductions called committed-programming reduction(CPRed) in the random oracle model(ROM) and obtain the following interesting results:(1) we demonstrate that some well-known schemes, including the full-domain hash(FDH) signature(Eurocrypt1996) and the Boneh-Franklin identity-based encryption(IBE) scheme(Crypto 2001), are provably secure under CPReds;(2) we prove that a CPRed associated with an instance-extraction algorithm implies a reduction in the quantum ROM(QROM). This unifies several recent results, including the security of the Gentry-Peikert-Vaikuntanathan IBE scheme by Zhandry(Crypto 2012) and the key encapsulation mechanism(KEM) variants using the Fujisaki-Okamoto transform by jiang et al.(Crypto 2018) in the ***, we show that CPReds are incomparable to non-programming reductions(NPReds) and randomly-programming reductions(RPReds) formalized by Fischlin et al.(Asiacrypt 2010).

关键词： provable security random oracle model quantum random oracle model black-box reduction/separation programmability

Robust cooperative multi-agent reinforcement learning via multi-view message certification

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Science China(Information Sciences) 2024年第4期67卷 131-145页

作者： Lei YUAN Tao jiang Lihe LI feng CHEN Zongzhang ZHANG Yang YU National Key Laboratory for Novel Software Technology Nanjing University Polixir Technologies

Many multi-agent scenarios require message sharing among agents to promote coordination,hastening the robustness of multi-agent communication when policies are deployed in a message perturbation environment. Major relevant studies tackle this issue under specific assumptions, like a limited number of message channels would sustain perturbations, limiting the efficiency in complex scenarios. In this paper,we take a further step in addressing this issue by learning a robust cooperative multi-agent reinforcement learning via multi-view message certification, dubbed CroMAC. Agents trained under CroMAC can obtain guaranteed lower bounds on state-action values to identify and choose the optimal action under a worst-case deviation when the received messages are perturbed. Concretely, we first model multi-agent communication as a multi-view problem, where every message stands for a view of the state. Then we extract a certificated joint message representation by a multi-view variational autoencoder(MVAE) that uses a product-of-experts inference network. For the optimization phase, we do perturbations in the latent space of the state for a certificate guarantee. Then the learned joint message representation is used to approximate the certificated state representation during training. Extensive experiments in several cooperative multi-agent benchmarks validate the effectiveness of the proposed CroMAC.

关键词： multi-agent reinforcement learning robust communication adversarial training multi-view learning message certification

A novel reprocessable chloroprene rubber based on dynamic disulfide metathesis

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International Journal of Smart and Nano Materials 2024年第1期15卷 42-61页

作者： Jianliang jiang Junxue Zhai Yanqing Chen Dongqi Zhao Yakai feng School of Chemical Engineering and Technology Collaborative Innovation Center of Chemical Science and Chemical Engineering(Tianjin)Tianjin UniversityTianjinChina R&D Department of China(Yangzhou) Material Handling Tech-Engineering LtdYangzhouChina Key Laboratory of Rubber Plastics of Ministry of Education/Shandong Province (QUsT)School of Polymer Science&EngineeringQingdao University of Science&TechnologyQingdaoChina R&D Department of Tianjin Joaboa Technology Co.Ltd TianjinP.R.China Frontiers Science Center for Synthetic Biology Tianjin UniversityTianjinChina Key Laboratory of Systems Bioengineering(Ministry of Education) Tianjin UniversityTianjinChina

For sustainable application of chloroprene rubber(CR),a new technology is developed by the vulcanization of CR using 2,2'-dithiodipyridine(DPD)as a cross-linking agent with the repro-cessing performance owing to disulfde *** DPD was incorporated into CR vulcanization,the Menschutkin reac-tion between allyl chloride group and pyridine group occurred with a maximum exothermic peak at 184°*** number of effective cross-linking bond at o.5 phr DPD vulcanizate was higher than that at high DPD *** vulcanizate showed high tensile strength(11.12 MPa)and elongation at break(1253±120%)owing to the exchangeable disulfide bond in the *** the catalysis of triphenylphosphine,the metathesis of disulfide compound was improved obviously,which endowed CR/DPD vulcanizates with good recyclability *** cross-linkage maintains its stability at low temperature,thus ensuring the mechanical stability of CR/DPD vulcanizate under the ambient *** and reprocessing of CR/DPD vulcanizate can be conducted with common industrial rubber processing *** reprocessable chloroprene rubber could have potential appli-cation in CR industry,also serve to significantly improve envir-onmental sustainability.

关键词： Chloroprene rubber reprocessable Menschutkin reaction disulfide

Tunable topological polaritons by dispersion tailoring of an active metasurface

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Advanced Photonics 2024年第4期6卷 59-69页

作者： Shaojie wang Ke Chen Shufang Dong Tian jiang Junming Zhao Yijun feng Nanjing University School of Electronic Science and EngineeringNanjingChina

Hyperbolic polaritons are known to exist in materials with extreme anisotropy,exhibiting exotic optical properties that enable a plethora of unusual phenomena in the fields of polaritonics and ***,achieving simultaneous low-dimensionality,high-speed controllability,and on-demand reconfigurability of the polaritons remains unexplored despite their excellent potential in light-matter interactions,photonic integrated circuits,and optoelectronic ***,we propose a metasurface approach to integrating artificially engineered electromagnetic anisotropy with fast-controllable electronic elements,offering a new route to realize active topological *** showcase the proposed reconfigurable metasurface can support real-time transitions of designer polaritons from elliptical to flat,and then to hyperbolic and circular isofrequency ***,the in-plane surface wavefront undergoes the transitions from convex to collimating,concave,and eventually back to *** exploiting the topological variations in polariton dispersions,we observe intriguing phenomena of controllable field canalization and tunable planar ***,we report the concept of a planar reconfigurable integrated polariton circuit by spatially tailoring the distributions of polariton isofrequency contours,unveiling rich dispersion engineering possibilities and active control *** may provide an inspiring platform for developing planar active plasmonic devices with potential applications in subdiffraction-resolution imaging,sensing,and information processing.

关键词： topological transitions hyperbolic metasurface anisotropic polaritons active tuning dispersion engineering