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Resonantly enhanced second-and third-harmonic generation in dielectric nonlinear metasurfaces

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Opto-Electronic Advances 2024年第5期7卷 5-19页

作者： Ji Tong Wang Pavel Tonkaev Kirill Koshelev Fangxing Lai Sergey Kruk Qinghai Song Yuri Kivshar Nicolae C.Panoiu Department of Electronic and Electrical Engineering University College LondonLondon WC1E 7JEUnited Kingdom Nonlinear Physics Center Research School of PhysicsAustralian National UniversityCanberra ACT 2601Australia Ministry of Industry and Information Technology Key Lab of Micro-Nano Optoelectronic Information System Guangdong Provincial Key Laboratory of Semiconductor Optoelectronic Materials and Intelligent Photonic SystemsHarbin Institute of TechnologyShenzhen 518055China Wuzhen Laboratory EGO Wuzhen Digital Economy Industrial ParkNo.925 Daole RoadTongxiangChina

Nonlinear dielectric metasurfaces provide a promising approach to control and manipulate frequency conversion optical processes at the nanoscale,thus facilitating both advances in fundamental research and the development of new practical applications in photonics,lasing,and ***,we employ symmetry-broken metasurfaces made of centrosymmetric amorphous silicon for resonantly enhanced second-and third-order nonlinear optical *** the rich physics of optical quasi-bound states in the continuum and guided mode resonances,we comprehensively study through rigorous numerical calculations the relative contribution of surface and bulk effects to second-harmonic generation(SHG)and the bulk contribution to third-harmonic generation(THG) from the ***,we experimentally achieve optical resonances with high quality factors,which greatly boosts light-matter interaction,resulting in about 550 times SHG enhancement and nearly 5000-fold increase of THG.A good agreement between theoretical predictions and experimental measurements is *** gain deeper insights into the physics of the investigated nonlinear optical processes,we further numerically study the relation between nonlinear emission and the structural asymmetry of the metasurface and reveal that the generated harmonic signals arising from linear sharp resonances are highly dependent on the asymmetry of the *** work suggests a fruitful strategy to enhance the harmonic generation and effectively control different orders of harmonics in all-dielectric metasurfaces,enabling the development of efficient active photonic nanodevices.

关键词： second-harmonic generation third-harmonic generation bound state in the continuum guided mode resonance all-dielectric metasurfaces nonlinear optics

Optimal monitoring and attack detection of networks modeled by Bayesian attack graphs

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Cybersecurity 2024年第1期7卷 1-15页

作者： Armita Kazeminajafabadi Mahdi Imani Department of Electrical and Computer Engineering Northeastern UniversityBostonMAUSA

Early attack detection is essential to ensure the security of complex networks,especially those in critical *** is particularly crucial in networks with multi-stage attacks,where multiple nodes are connected to external sources,through which attacks could enter and quickly spread to other network *** attack graphs(BAGs)are powerful models for security risk assessment and mitigation in complex networks,which provide the probabilistic model of attackers’behavior and attack progression in the *** attack detection techniques developed for BAGs rely on the assumption that network compromises will be detected through routine monitoring,which is unrealistic given the ever-growing complexity of *** paper derives the optimal minimum mean square error(MMSE)attack detection and monitoring policy for the most general form of *** exploiting the structure of BAGs and their partial and imperfect monitoring capacity,the proposed detection policy achieves the MMSE optimality possible only for linear-Gaussian state space models using Kalman *** adaptive resource monitoring policy is also introduced for monitoring nodes if the expected predictive error exceeds a user-defined *** and efficient matrix-form computations of the proposed policies are provided,and their high performance is demonstrated in terms of the accuracy of attack detection and the most efficient use of available resources using synthetic Bayesian attack graphs with different topologies.

关键词： Multi-stage attacks Bayesian attack graph Attack detection Optimal monitoring

Dynamics of self-hybridized exciton–polaritons in 2D halide perovskites

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Light(Science & Applications) 2024年第1期13卷 13-22页

作者： Surendra B.Anantharaman Jason Lynch Christopher E.Stevens Christopher Munley Chentao Li Jin Hou Hao Zhang Andrew Torma Thomas Darlington Francis Coen Kevin Li Arka Majumdar PJames Schuck Aditya Mohite Hayk Harutyunyan Joshua R.Hendrickson Deep Jariwala Department of Electrical and Systems Engineering University of PennsylvaniaPhiladelphiaPA19104USA KBR Inc. BeavercreekOH45431USA Air Force research Laboratory Sensors DirectorateWright-Patterson Air Force BaseOH45433USA Department of Physics University of WashingtonSeattleWA98195USA Department of Physics Emory UniversityAtlantaGA30322USA Department of Chemical and Biomolecular Engineering Rice UniversityHoustonTX77005USA Department of Materials Science and Nanoengineering Rice UniversityHoustonTX77005USA Applied Physics Program Smalley‐Curl InstituteRice UniversityHoustonTX77005USA Department of Mechanical Engineering Columbia UniversityNew YorkNY10027USA Department of Electrical and Computer Engineering University of WashingtonSeattleWA98195USA

Excitons,bound electron–hole pairs,in two-dimensional hybrid organic inorganic perovskites(2D HOIPs)are capable of forming hybrid light-matter states known as exciton-polaritons(E–Ps)when the excitonic medium is confined in an optical *** the case of 2D HOIPs,they can self-hybridize into E–Ps at specific thicknesses of the HOIP crystals that form a resonant optical cavity with the ***,the fundamental properties of these self-hybridized E–Ps in 2D HOIPs,including their role in ultrafast energy and/or charge transfer at interfaces,remain ***,we demonstrate that>0.5µm thick 2D HOIP crystals on Au substrates are capable of supporting multiple-orders of self-hybridized E–P *** E–Ps have high Q factors(>100)and modulate the optical dispersion for the crystal to enhance sub-gap absorption and *** varying excitation energy and ultrafast measurements,we also confirm energy transfer from higher energy E–Ps to lower energy E–***,we also demonstrate that E–Ps are capable of charge transport and transfer at *** findings provide new insights into charge and energy transfer in E–Ps opening new opportunities towards their manipulation for polaritonic devices.

关键词： charge polar excitation

Spontaneous mutations and mutational responses to penicillin treatment in the bacterial pathogen Streptococcus pneumoniae D39

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Marine Life Science & Technology 2024年第2期6卷 198-211页

作者： Wanyue Jiang Tongtong Lin Jiao Pan Caitlyn ERivera Clayton Tincher Yaohai Wang Yu Zhang Xiang Gao Yan Wang Ho‑Ching T.Tsui Malcolm E.Winkler Michael Lynch Hongan Long Institute of Evolution and Marine Biodiversity KLMMEOcean University of ChinaQingdao 266003China Laboratory for Marine Biology and Biotechnology Laoshan LaboratoryQingdao 266237China Department of Biology Indiana UniversityBloomingtonIN 47405USA School of Mathematics Science Ocean University of ChinaQingdao 266000China State Key Laboratory of Microbial Technology Microbial Technology InstituteSchool of Life ScienceShandong UniversityQingdao 266237China Biodesign Center for Mechanisms of Evolution Arizona State UniversityTempeAZ 85281USA

Bacteria with functional DNA repair systems are expected to have low mutation rates due to strong natural selection for genomic ***,our study of the wild-type Streptococcus pneumoniae D39,a pathogen responsible for many common diseases,revealed a high spontaneous mutation rate of 0.02 per genome per cell division in mutation-accumulation(MA)*** rate is orders of magnitude higher than that of other non-mutator bacteria and is characterized by a high mutation bias in the A/T *** high mutation rate may have resulted from a reduction in the overall efficiency of selection,conferred by the tiny effective population size in *** line with this,*** D39 also exhibited the lowest DNA mismatch-repair(MMR)efficiency among *** with the antibiotic penicillin did not elevate the mutation rate,as penicillin did not induce DNA damage and *** lacks a stress response *** findings suggested that the MA results are applicable to within-host scenarios and provide insights into pathogen evolution.

关键词： Neutral evolution Mutation spectrum Antibiotics DNA mismatch repair Oxidative damage repair

基于模拟-建模研究化学与温度对难熔高熵合金力学行为和变形机制的影响

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Acta Mechanica Sinica 2024年第2期40卷 103-115页

作者：李甲任思危刘彬 Peter K.Liaw 方棋洪 State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle EngineeringHunan UniversityChangsha410082China State Key Laboratory of Powder Metallurgy Central South UniversityChangsha410083China Department of Materials Science and Engineering The University of TennesseeKnoxville37996USA

难熔高熵合金在高温下表现出优异的性能,突破了传统高温合金的工作温度上限.我们采用原子模拟研究了化学元素分布和温度对等原子比MoNbTaW难熔高熵合金变形机制的影响.根据微观结构演化,建立了基于微观结构的本构模型,定量评估多种强化... 详细信息

难熔高熵合金在高温下表现出优异的性能,突破了传统高温合金的工作温度上限.我们采用原子模拟研究了化学元素分布和温度对等原子比MoNbTaW难熔高熵合金变形机制的影响.根据微观结构演化,建立了基于微观结构的本构模型,定量评估多种强化机制的贡献.结果表明,应变硬化后,流动应力随应变呈锯齿状剧烈波动.由于退火结构的溶质浓度降低,温度升高降低了应变硬化率和流动应力波动幅度.变形孪晶在变形机制中起着关键作用,能够通过位错基塑性和晶粒中的非晶形核进一步调节局部变形.有序结构的存在强烈影响了应力和应变分配.固溶强化和晶界强化对流动应力的贡献很大,孪晶强化对流动压力的贡献很小.原子模拟和力学模型为深入理解难熔高熵合金变形行为及性能的精确预测提供依据.

关键词：流动应力固溶强化强化机制高温合金高熵合金变形机制晶界强化溶质浓度

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声波超材料中D类拓扑的观测

Science Bulletin 2024年第7期69卷 893-900页

作者：吴世巧程文婷刘啸宇吴柄权 Emil Prodan Camelia Prodan 蒋建华 School of Physical Science and Technology&Collaborative Innovation Center of Suzhou Nano Science and Technology Soochow UniversitySuzhou 215006China School of Physics and Optoelectronic Engineering Foshan UniversityFoshan 528000China Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology Foshan UniversityFoshan 528000China Department of Physics University of MichiganAnn Arbor MI 48109USA Department of Physics Yeshiva UniversityNew York NY 10033USA Department of Physics and Engineering Physics Fordham UniversityNew York NY 10023USA Suzhou Institute for Advanced research University of Science and Technology of ChinaSuzhou 215123China

Topological materials and metamaterials opened new paradigms to create and manipulate phases of matter with unconventional *** D-class phases(TDPs)are archetypes of the ten-fold classification of topological phases with particle-hole *** two dimensions,TDPs support propagating topological edge modes that simulate the elusive Majorana elementary ***,a piercing ofπ-flux Dirac-solenoids in TDPs stabilizes localized Majorana excitations that can be braided for the purpose of topological quantum *** two-dimensional(2D)TDPs have been a focus in the research frontier,but their experimental realizations are still under ***,with a novel design scheme,we realize 2D TDPs in an acoustic crystal by synthesizing both the particle-hole and fermion-like time reversal symmetries for a wide range of *** design scheme leverages an enriched unit cell structure with real-valued couplings that emulate the targeted Hamiltonian of TDPs with complex hoppings:A technique that could unlock the realization of all topological classes with passive *** our experiments,we realize a pair of TDPs with opposite Chern numbers in two independent sectors that are connected by an intrinsic fermion-like timereversal symmetry built in the *** measure the acoustic Majorana-like helical edge modes and visualize their robust topological transport,thus revealing the unprecedented D and DIII class topologies with direct *** study opens up a new pathway for the experimental realization of two fundamental classes of topological phases and may offer new insights in fundamental physics,materials science,and phononic information processing.

关键词： D-class topology Chiral symmetry Time-reversal symmetry Particle-hole symmetry Gapless edge states

Nonlinear photonics with metasurfaces

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Photonics research 2023年第2期11卷 122-136页

作者： POLINA VABISHCHEVICH YURI KIVSHAR Physical Measurement Laboratory National Institute of Standards and TechnologyGaithersburgMaryland 20899USA Department of Chemistry and Biochemistry University of MarylandCollege ParkMaryland 20742USA Nonlinear Physics Center Research School of PhysicsAustralian National UniversityCanberra ACT 2601Australia

Nonlinear optics is a well-established field of research that traditionally relies on the interaction of light with macroscopic nonlinear media over distances significantly greater than the wavelength of light. However, the recently emerged field of optical metasurfaces provides a novel platform for studying nonlinear phenomena in planar geometries. Nonlinear optical metasurfaces introduce new functionalities to the field of nonlinear optics extending them beyond perturbative regimes of harmonic generation and parametric frequency conversion,being driven by mode-matching, resonances, and relaxed phase-matching conditions. Here we review the very recent advances in the rapidly developing field of nonlinear metasurface photonics, emphasizing multi-frequency and cascading effects, asymmetric and chiral frequency conversion, nonperturbative nonlinear regimes, and nonlinear quantum photonics, empowered by the physics of Mie resonances and optical bound states in the continuum.

关键词： Nonlinear nonlinear optics

State of health based battery reconfiguration for improved energy efficiency

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Control Theory and Technology 2022年第4期20卷 443-455页

作者： Le Yi Wang George Yin Yi Ding Caiping Zhang Department of Electrical and Computer Engineering Wayne State UniversityDetroitMI 48202USA Department of Mathematics University of ConnecticutStorrsCT 06269USA US army CCDC Ground Vehicle Systems Center in Warren WarrenMI 48397USA School of Electrical Engineering Beijing Jiaotong UniversityBeijing 100044China

This paper analyzes the system-level state of health(SOH)and its dependence on the SOHs of its component battery *** to stochastic natures of battery aging processes and their dependence on charge/discharge rate and depth,operating temperature,and environment conditions,capacities of battery modules decay unevenly and *** on estimated SOHs of battery modules during battery operation,we analyze how the SOH of the entire system deteriorates when battery modules age and become increasingly diverse in their capacities.A rigorous mathematical analysis of system-level capacity utilization is *** is shown that for large battery strings with uniformly distributed capacities,the average string capacity approaches the minimum,implying an asymptotically near worst-case capacity utility without *** is demonstrated that the overall battery usable capacities can be more efficiently utilized to achieve extended operational ranges by using battery *** optimal regrouping algorithm is *** methods,simulation examples,and a case study using real-world battery data are presented.

关键词： Battery system State of health Battery aging Capacity utilization Energy efficiency Battery regrouping

Phase classification of multi-principal element alloys via interpretable machine learning

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npj Computational Materials 2022年第1期8卷 206-217页

作者： Kyungtae Lee Mukil V.Ayyasamy Paige Delsa Timothy Q.Hartnett Prasanna V.Balachandran Department of Materials Science and Engineering University of VirginiaCharlottesvilleVA22904USA Department of Physics University of RichmondRichmondVA23173USA Department of Mechanical and Aerospace Engineering University of VirginiaCharlottesvilleVA22904USA

There is intense interest in uncovering design rules that govern the formation of various structural phases as a function of chemical composition in multi-principal element alloys (MPEAs).In this paper,we develop a machine learning (ML) approach built on the foundations of ensemble learning,post hoc model interpretability of black-box models,and clustering analysis to establish a quantitative relationship between the chemical composition and experimentally observed phases of *** originality of our work stems from performing instance-level (or local) variable attribution analysis of ML predictions based on the breakdown method,and then identifying similar instances based on k-means clustering analysis of the breakdown *** also complement the breakdown analysis with Ceteris Paribus profiles that showcase how the model response changes as a function of a single variable,when the values of all other variables are *** from local model interpretability analysis uncover key insights into variables that govern the formation of each *** developed approach is generic,model-agnostic,and valuable to explain the insights learned by the black-box *** interactive web application is developed to facilitate model sharing and accelerate the design of MPEAs with targeted properties.

关键词： alloys element instance