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Vortex excites unidirectional water waves near ancient Luoyang Bridge

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Frontiers of physics 2024年第3期19卷 163-165页

作者： Yichen Li Xinhua Hu department of Materials Science and Key Laboratory of Micro-and Nano-Photonic structures(Ministry of Education) Fudan UniversityShanghai 200433China

Since the discovery of generalized Snell’s law in 2011[1],metasurfaces have opened up the mainstream of arbitrary wavefront manipulation in *** a gradient-index metasurface,the parallel wavenumber kx of reflected wave can be not equal to the incident one(kx=ξ+k0sinθi,where k0 andθi are the incident wavenumber and angle,andξis the phase gradient of metasurface in its supercell)[1].Whenξ>k0,the reflected wave becomes a surface wave bounded on the metasurface(where|kx|>k0,kz is imaginary,and z is normal to the metasurface)[2].However,as research of metasurfaces continually evolves,some articles have pointed out that such graded metasurfaces suffer from a series of problems[3-6].In particular,multiple metallic resonators are adopted in a subwavelength supercell,resulting in impedance mismatch,moderate conversion efficiency,wave absorption,and fabrication ***,although the approach of graded metasurfaces has been demonstrated in the microwave regime,it is hard to extend to infrared and optical ranges with shorter *** solve this problem,Ra’di et al.[7]devised metagratings with periodic arrays of bianisotropic scatterers and showed that they enable wave front engineering with unitary efficiency and significantly lower fabrication demands.

关键词： graded reflected imaginary

Comparison of engineering failures and seismic responses of 500 kV transformer-bushing systems in the 2022 Luding earthquake

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Earthquake Engineering and Engineering Vibration 2024年第4期23卷 1029-1041页

作者： Zhu, Wang Wu, Ming’er Xie, Qiang department of Structural Engineering Tongji University Shanghai China Key Laboratory of Performance Evolution and Control for Engineering structures (Tongji University) Shanghai China

Cemented and mechanically clamped types of end fittings (fitting-C and fitting-M) are commonly used in transformer bushings. During the Luding Ms 6.8 earthquake that occurred in China on September 5, 2022, all transformer bushings with the two types of end fittings in a 500 kV substation were damaged. Post-earthquake field investigations were conducted, and the failures of the two types of bushings were compared. Two elementary simulation models of the transformer-bushing systems were developed to simulate the engineering failures, and further compute their seismic responses for comparison. The results indicate that the hitch lugs of the connection flange are structurally harmful to seismic resistance. Fitting-M can decrease the bending stiffness of the bushing due to the flexible sealing rubber gasket. Since it provides a more flexible connection that dissipates energy, the peak accelerations and relative displacements at the top of the bushing are significantly lower than those of the bushing with fitting-C. Compared with fitting-C, fitting-M transfers the high-stress areas from the connection flange to the root of the porcelain, so the latter becomes the most vulnerable component. Fitting-M increases the failure risk of the low-strength porcelain, indicating the unsuitability of applying it in high-intensity fortification regions.

关键词： transformer bushing end fitting Luding earthquake,engineering failure seismic responses

Gravitational wave fluxes on generic orbits in near-extreme Kerr spacetime:Higher spin and large eccentricity

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Science China(Physics,Mechanics & Astronomy) 2024年第11期Mechanics & Astronomy) .卷 20-32页

作者： Changkai Chen Jiliang Jing department of Physics Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of EducationSynergetic Innovation Center for Quantum Effects and Applications Hunan Normal University

To accurately obtain the waveform template of gravitational waves, substantial computational resources and extremely high precision are often required. In a previous study, we employed the confluent Heun function to obtain an exact solution to the Teukolsky equation. This approach allowed us to efficiently and accurately calculate the gravitational wave flux for a particle in circular orbits around a Schwarzschild black hole. building on this method, we now extend its application to calculate the asymptotic gravitational wave fluxes from a particle in generic orbits around a near-extreme Kerr black hole. Our extended method proves particularly effective in handling computational challenges associated with large eccentricities(e = 0.9), higher spins(a = 0.999), higher harmonic modes, and strong-field regions. The results we obtained significantly outperform those derived from the numerical integration method based on the Mano-Suzuki-Takasugi method.

关键词： gravitational wave fluxes exact solution Teukolsky equation near-extreme Kerr black hole

Theoretical Analysis of the Buckling Behaviors of Inhomogeneous Shape Memory Polymer Composite Laminates Considering Prestrains

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Acta Mechanica Solida Sinica 2024年第2期37卷 271-284页

作者： Hanxing Zhao Pengyu Cao Fengfeng Li Xin Lan Liwu Liu Yanju Liu Jinsong Leng Centre of Composite Materials and structures Harbin Institute of Technology(HIT)Harbin150080China department of Astronautical Science and Mechanics Harbin Institute of Technology(HIT)Harbin150001China

The mismatch in thermal expansion coefficients between the fiber-rich and resin-rich regions of a shape memory polymer composite(SMPC)laminate,along with the residual strain during SMPC fabrication,results in buckling deformation of the inhomogeneous *** paper presents a macroscopic model for buckling of an inhomogeneous SMPC laminate under initial biaxial *** linear and nonlinear buckling analyses are carried out using the energy *** influences of prestrain biaxiality,temperature,and ply angle on the buckling wavelength,critical buckling prestrain,and buckling amplitude are *** results demonstrate that the critical buckling wavelength of the SMPC laminate is independent of the prestrain,while the amplitude is almost independent of *** addition,the optimal fiber stacking configuration with the maximum critical buckling prestrains of inhomogeneous SMPC laminates is determined by a genetic algorithm.

关键词： Shape memory polymer composite Buckling behavior Inhomogeneous laminate Biaxial prestrains

Isogeometric Analysis for the Arbitrary AFG Microbeam with Two-Phase Nonlocal Stress-Driven Model

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Acta Mechanica Solida Sinica 2024年第2期37卷 341-360页

作者： Pei-Liang Bian Zhaowei Liu Hai Qing Tiantang Yu department of Engineering Mechanics Hohai UniversityNanjing211100China State Key Laboratory of Mechanics and Control of Mechanical structures Nanjing University of Aeronautics and AstronauticsNanjing210016China

Scale effects play critical roles in the mechanical responses of *** isogeometric analysis was developed here to investigate the mechanical responses of an axially functionally graded *** Euler–Bernoulli beam model was utilized,and size effects in the structure were modeled with a stress-driven two-phase local/nonlocal integral *** governing equation of microstructures was given in an equivalent differential form with two additional constitutive boundary *** framework was verified and utilized to analyze the microbeam’s static and dynamic mechanical *** present work showed great potential for modeling various types of functionally graded microstructures.

关键词： Isogeometric analysis Size effect Functionally graded material Nonlocal theory Euler-Bernoulli beam

Lorentz violation induces isospectrality breaking in Einstein-bumblebee gravity theory

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Science China(Physics,Mechanics & Astronomy) 2024年第8期67卷 87-96页

作者： Wentao Liu Xiongjun Fang Jiliang Jing Jieci Wang department of Physics Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of EducationSynergetic Innovation Center for Quantum Effects and ApplicationsHunan Normal UniversityChangsha 410081China

In this study,we investigate the quasinormal modes(QNMs)of a Lorentz-violating spacetime,factoring in a cosmological constant,within the framework of Einstein-bumblebee *** findings reveal that the interaction of spacetime with an anisotropic bumblebee field imparts distinct contributions to the axial and polar sectors of the vector *** subsequently breaks the isospectrality typically observed in vector *** evidence strongly indicates isospectral breaking in the vector modes of Einstein-bumblebee black holes:a pronounced breakage in the real part of the frequencies,while the imaginary component seems less *** isospectral breaking indicates the existence of two different waveforms in the Ringdown phase of the black hole,which provides a potential signal of quantum gravity observable in current experiments.

关键词： Lorentz-violating isospectral breaking quasinormal modes

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Dynamic Sulfur-Rich Polymers from Elemental Sulfur and Epoxides

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Chinese Journal of Polymer Science 2024年第10期42卷 1479-1487页

作者： Ke-Xiang Chen Chen-Hui Cui Zhen Li Ting Xu Hao-Qing Teng Zhi-Yuan He Yin-Zhou Guo Xiao-Qing Ming Zhi-Shen Ge Yan-Feng Zhang Tie-Jun Wang School of Chemistry Engineering Research Center of Energy Storage Materials and Devices Ministry of Education Xi'an Jiaotong University State Key Lab for Strength and Vibration of Mechanical structures Department of Engineering Mechanics Xi'an Jiaotong University

Sulfur-containing dynamic polymers had attracted significant attention due to their unique chemical structures with high *** sulfur, an inexpensive industrial waste product, to synthesize dynamic polysulfide polymers through reverse vulcanization has been a notable approach. However, this method required high temperatures and resulted in the release of unpleasant oders. In this study, we presented a robust method for the preparation of sulfur-rich polymers with dynamic polysulfide bonds from elemental sulfur and inexpensive epoxide monomers via a one-pot strategy at the mild room temperature. Different types of polysulfide molecules and polymers were synthesized by reacting various epoxide compounds with sulfur, along with the investigation of their structures and dynamic behaviors. It was noteworthy that the obatined polymers prepared from m-(2,3-epoxypropoxy)-N,N-bis(2,3-epoxypropyl)aniline and elemental sulfur exhibit multiple dynamic behaviors, including polysulfide metathesis and polysulfide-thiol exchange, enabling their rapid stress relaxation, self-healing, reprocessing and degradable properties of the cross-linked polymer. More importantly, the hydroxyl groups at the side chains from epoxide ring opening exhibited potential transesterification. This work provided a facile strategy for designing dynamic sulfur-rich polymers via a mild synthesis route.

关键词： Dynamic covalent bond Dynamic polymer Elemental sulfur Sulfur-containing polymer

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A CAD-BEM geometry transformation method for face-based primary geometric input based on closed contour recognition

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building Simulation 2024年第2期17卷 335-354页

作者： Jun Xiao Hao Zhou Shiji Yang Deyin Zhang Borong Lin department of building Science School of ArchitectureTsinghua UniversityBeijing100084China Key Laboratory of Eco Planning&Green building Ministry of EducationTsinghua UniversityBeijing100084China Institute for Urban Governance and Sustainable Development Tsinghua UniversityBeijing100084China

Performance analysis during the early design stage can significantly reduce building energy ***,it is difficult to transform computer-aided design(CAD)models into building energy models(BEM)to optimize building *** model structures for CAD and BEM are *** this study,geometry transformation methods was implemented in BES tools for the early design stage,including auto space generation(ASG)method based on closed contour recognition(CCR)and space boundary topology calculation *** program is developed based on modeling tools SketchUp to support the CAD format(like*.stl,*.dwg,*.ifc,etc.).It transforms face-based geometric information into a zone-based tree structure model that meets the geometric requirements of a single-zone BES combined with the other thermal parameter inputs of the *** addition,this study provided a space topology calculation method based on a single-zone BEM *** program was developed based on the SketchUp modeling tool to support additional CAD formats(such as*.stl,*.dwg,*.ifc),which can then be imported and transformed into*.*** to current methods mostly focused on BIM-BEM transformation,this method can ensure more modeling *** method was integrated into a performance analysis tool termed MOOSAS and compared with the current version of the transformation *** were tested on a dataset comprising 36 conceptual models without partitions and six real cases with detailed *** ensures a transformation rate of two times in any bad model condition and costs only 1/5 of the time required to calculate each room compared to the previous version.

关键词： geometry transformation building energy model computer aid design closed contour recognition

A graph neural network approach to the inverse design for thermal transparency with periodic interparticle system

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Chinese Physics B 2024年第8期33卷 295-303页

作者：刘斌王译浠 department of Electronic Information and Artificial Intelligence LeShan Normal UniversityLeShan 614099China department of Physics State Key Laboratory of Surface Physicsand Key Laboratory of Micro and Nano Photonic Structures(MOE)Fudan UniversityShanghai 200438China

Recent years have witnessed significant advances in utilizing machine learning-based techniques for thermal metamaterial-based structures and devices to attain favorable thermal transport *** the various thermal transport behaviors,achieving thermal transparency stands out as particularly desirable and *** earlier work demonstrated the use of a thermal metamaterial-based periodic interparticle system as the underlying structure for manipulating thermal transport behavior and achieving thermal *** this paper,we introduce an approach based on graph neural network to address the complex inverse design problem of determining the design parameters for a thermal metamaterial-based periodic interparticle system with the desired thermal transport *** work demonstrates that combining graph neural network modeling and inference is an effective approach for solving inverse design problems associated with attaining desirable thermal transport behaviors using thermal metamaterials.

关键词： thermal metamaterial thermal transparency inverse design machine learning graph neural net-work

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