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Merger estimates for a disformal Kerr black hole in quadratic degenerate higher-order scalar-tensor theories

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Chinese Physics C 2024年第5期48卷 284-292页

作者：蒋洪鑫杜欣怡潘启沅陈松柏荆继良 Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of Education Synergetic Innovation Center for Quantum Effects and Applicationsand Department of PhysicsHunan Normal UniversityChangsha 410081China Institute of Interdisciplinary Studies Hunan Normal UniversityChangsha 410081China Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou UniversityYangzhou 225009China

We investigate the main features of a disformal Kerr black hole merger in quadratic degenerate higher-order scalar-tensor *** the ringdown stage of the black hole merger,for the prograde orbit,the real part of the quasinormal modes decreases with an increase in the disformal parameter,and the imaginary part also decreases,except in the Kerr case for a large spin ***,for the retrograde orbit,the real part increases with an increase in the disformal parameter,and the imaginary part always decreases with *** the approximate final spin,regardless of an equal spin,unequal spin,or generic spin configuration merger,the final black hole spin always increases with an increase in the disformal *** results show that the disformal parameter in the disformal Kerr solution and the MOG parameter in the Kerr-MOG case have obviously different effects on the black hole merger,which suggests the differences between these two spacetime structures.

关键词： black hole merger quasinormal modes final black hole spin disformal Kerr black hole quadratic degenerate higher-order scalar-tensor(DHOST)theory

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新形势下民办义务教育的功能定位与实践理路

教育发展研究 2024年第12期44卷 8-16页

作者：陈松柏王一涛吴华苏州大学教育学院苏州215123 吉林外国语大学民办高等教育研究院长春130117

公民办教育的比例是在各国特定的经济、文化和社会背景下逐渐形成的,目前,全球私立基础教育平均占比超过两成且呈现稳步上升的发展趋势。就我国来说,民办义务教育学校在发展进程中逐渐形成了补充型和选择型两大功能类型,分别发挥着补充... 详细信息

公民办教育的比例是在各国特定的经济、文化和社会背景下逐渐形成的,目前,全球私立基础教育平均占比超过两成且呈现稳步上升的发展趋势。就我国来说,民办义务教育学校在发展进程中逐渐形成了补充型和选择型两大功能类型,分别发挥着补充教育资源和丰富学生教育选择的作用。民办义务教育学校具备灵活性和高效率两大体制优势。随着政府不断提高基本公共教育服务投入水平,低端补充型民办学校将逐渐退出义务教育领域,高质量、有特色的选择型民办学校将成为我国义务教育阶段民办学校的主流,对于此类民办学校政府应大力支持和鼓励。为此,当前应疏解民办义务教育的负面情绪和发展压力,引导民办学校提高质量、形成特色,与公办学校错位发展,提供公办学校不具有的选择性功能,努力维护教育生态系统的多样性和灵活性,更好满足人民群众对多样化优质教育的需要。

关键词：民办义务教育国际比较功能价值实践理路

Effect of noncircularity on the dynamic behaviors of particles in a disformal rotating black-hole spacetime

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Science China(Physics,Mechanics & Astronomy) 2022年第5期65卷 34-42页

作者： Xuan Zhou songbai chen Jiliang Jing Department of Physics Synergetic Innovation Center for Quantum Effects and ApplicationsHunan Normal UniversityChangsha 410081China Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou UniversityYangzhou 225009China

A disformal rotating black-hole solution is a black-hole solution in quadratic degenerate higher-order scalar-tensor *** breaks the circular condition of spacetime different from the case of the usual Kerr *** study investigated the dynamic behaviors of the motion of timelike particles in such disformal black-hole spacetime with an extra deformation *** showed that the characteristics of the particle’s motion depend on the sign of the deformation *** the positive deformation parameter,the motion is regular and *** the negative one,as the deformation parameter changes,the motion of the particles undergoes a series of transitions between the chaotic motion and the regular motion and falls into the horizon or escapes to spatial *** means that the dynamic behavior of timelike particles in the disformal Kerr black-hole spacetime with noncircularity becomes richer than that in the usual Kerr black-hole case.

关键词： disformal rotating black-hole noncircularity quadratic degenerate higher-order scalar-tensor theories chaos

Polarization distribution in the image of a synchrotron emitting ring around a regular black hole

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Science China(Physics,Mechanics & Astronomy) 2022年第12期65卷 97-108页

作者： Xueyao Liu songbai 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 ApplicationsHunan Normal UniversityChangsha410081China Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou UniversityYangzhou225009China

The polarized images of a synchrotron emitting ring are studied in the regular Hayward and Bardeen black hole *** regular black holes carry a magnetic field in terms of gravity coupled to nonlinear *** show that the main features of the polarization images of the emitting rings are similar in these two regular black hole *** the magnetic charge parameter increases,the polarization intensity and the electric vector position angle in the image plane increase in Hayward and Bardeen black hole ***,the polarization intensity and electric vector position angle in the image of the emitting ring in the Hayward black hole spacetime are closer to those in the Schwarzschild *** effects of the magnetic charge parameter on the Strokes Q-U loops are also slightly smaller in the Hayward black hole *** information stored in the polarization images around Hayward and Bardeen black holes could help understand regular black holes and the gravity coupled to nonlinear electrodynamics.

关键词： black hole image regular black hole polarization distribution synchrotron emitting ring

Determination of the spin parameter and the inclination angle from the primary and secondary images caused by gravitational lensing

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中国科学:物理学、力学、天文学英文版 2023年第11期66卷 106-118页

作者： Mingzhi Wang songbai chen Jiliang Jing School of Mathematics and Physics Qingdao University of Science and TechnologyQingdao266061China Institute of Physics and 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 UniversityChangsha410081China Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou UniversityYangzhou225009China

We study the primary images(PIs)and secondary images(SIs)caused by strong gravitational lensing around a Kerr black hole shadow,which carry some essential signatures related to the black hole *** define a new celestial coordinate,whose origin is the center of the black hole shadow,to locate the PIs and SIs of luminous celestial *** on the dragging effect caused by the rotating black hole and the inclination angle of the observer,the relative positions between the PIs and SIs are different for different values of the Kerr spin parameter a and the observer's inclination angle i;hence,it can be used to determine the values of a and *** propose a specific approach to measure a and i using the PIs and *** time delays between the PIs and SIs are different for different values of a and *** time delays,in conjunction with the relative positions between the PIs and SIs,can enable us to measure a and i more *** PIs and SIs around the black hole shadow act as unique fingerprints for the black hole space-time,using which we can further determine other parameters of different types of compact objects and verify various theories of *** results provide a new method to implement parameter estimation in the study of black hole physics and astrophysics.

关键词： black hole shadow gravitational lensing the primary images the secondary images

Thick accretion disk configurations around a compact object in the brane-world scenario

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Communications in Theoretical Physics 2023年第11期75卷 76-83页

作者： Yunzhu Wei songbai chen Jiliang Jing Department of Physics Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of EducationInstitute of Interdisciplinary StudiesSynergetic Innovation Center for Quantum Effects and ApplicationsHunan Normal UniversityChangshaHunan 410081China Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou UniversityYangzhou 225009China

We have studied the equipotential surfaces of a thick accretion disk around a Casadio-Fabbri-Mazzacurati compact object in the brane-world scenario,which possesses a mass parameter together with a parameterized post-Newtonian(PPN)*** the increase in the PPN parameter,the size of the thick accretion disk decreases,but the corresponding Roche lobe size ***,the larger PPN parameter yields the larger region of existing bound disk structures,where the fluid is not accreted into the central ***,with the increase in the PPN parameter,the position of the Roche lobe gradually moves away from the central compact object,and the thickness of the region enclosed by the Roche lobe decreases near the compact object but increases in the region far from the compact *** results also show that the pressure gradient in the disk decreases with the PPN *** effects of the PPN parameter on the thick accretion disk could help one to further understand compact objects in the brane-world scenario.

关键词： black hole brane world wormhole

Black hole images:A review

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Science China(Physics,Mechanics & Astronomy) 2023年第6期66卷 101-117页

作者： songbai chen Jiliang Jing Wei-Liang Qian Bin Wang Department of Physics Synergetic Innovation Centerfor Quantum Effects and ApplicationsHunan Normal UniversityChangsha 40081China Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou UniversityYangzhou 225009China Escola de Engenharia de Lorena Universidade de Sao PauloSao Paulo 12602-810Brazil Faculdade de Engenharia de Guaratingueta Universidade Estadual PaulistaSao Paulo 12516-410Brazil School of Aeronautics and Astronautics Shanghai Jiao Tong UniversityShanghai 200240China

In recent years,unprecedented progress has been achieved regarding black holes’observation through the electromagnetic *** images of the supermassive black holes M87*and Sgr A*released by the Event Horizon Telescope(EHT)Collaboration provided direct visual evidence for their existence,which has stimulated further studies on various aspects of the compact celestial ***,the information stored in these images provides a new way to understand the pertinent physical processes that occurred near the black holes,to test alternative theories of gravity,and to furnish insight into fundamental *** this review,we briefiy summarize the recent developments on the *** particular,we elaborate on the features and formation mechanism of black hole shadows,the properties of black hole images illuminated by the surrounding thin accretion disk,and the corresponding polarization *** potential applications of the relevant studies are also addressed.

关键词： black hole shadow accretion disk polarization image

Experimental and Numerical Investigation of Non-synchronous Blade Vibration Excitation in a Transonic Axial Compressor

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Journal of Thermal Science 2024年第2期33卷 602-610页

作者： WANG songbai WU Yadong chen Yong CAO Zhipeng School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai200240China AECC Sichuan Gas Turbine Establishment Chengdu610500China

The complex flow phenomenon of rotating instability(RI) and its induced non-synchronous vibration(NSV) have become a significant challenge as they continuously increase aerodynamic *** study aims to provide an understanding of the non-synchronous blade vibration phenomenon caused by the rotating instability of a transonic axial compressor *** this case,blade vibrations and non-synchronous excitation are captured by strain gauges and unsteady wall pressure transducer *** numerical simulations for a full-annulus configuration are used to obtain the non-synchronous flow *** results show that the first-stage rotor blade exhibits an NSV close to the first bending mode;NSV is accompanied by a sharp increase in pressure pulsation;amplitude can reach 20%,and unsteady aerodynamic frequency will lock in a structural mode frequency when the blade vibrates in a large-amplitude *** predicted NSV frequency aligns well with the experimental *** dominant mode of circumferential instability flow structure is approximately 47% of the number blades,and the cell size occupies 2-3 pitches in the circumferential *** full-annulus unsteady simulations demonstrate that the streamwise oscillation of the shedding and reattachment vortex structure is the main cause of NSV owing to the strong interaction between the tip leakage and separation vortices near the suction surface.

关键词： non-synchronous vibration transonic axial compressor rotor blade rotating instabilities unsteady flow

Fatigue Crack Propagation Law of Corroded Steel Box Girders in Long Span Bridges

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Computer Modeling in Engineering & Sciences 2024年第7期140卷 201-227页

作者： Ying Wang Longxiao Chao Jun chen songbai Jiang Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education School of Civil EngineeringSoutheast UniversityNanjing211189China Jiangsu Provincial Engineering Construction Standard Station Nanjing210036China

In order to investigate the fatigue performance of orthotropic anisotropic steel bridge decks,this study realizes the simulation of the welding process through elastic-plastic finite element theory,thermal-structural sequential coupling,and the birth-death element *** simulated welding residual stresses are introduced into the multiscale finite element model of the bridge as the initial ***,the study explores the impact of residual stress on crack propagation in the fatigue-vulnerable components of the corroded steel box *** results indicate that fatigue cracks at the weld toe of the top deck,the weld root of the top deck,and the opening of the transverse diaphragm will not propagate under the action of a standard vehicle ***,the inclusion of residual stress leads to the propagation of these *** considering residual stress,the fatigue crack propagation paths at the weld toe of the transverse diaphragm and the U-rib weld toe align with those observed in actual *** the absence of residual stress,the cracks at the toe of the transverse diaphragm with a 15%mass loss rate are categorized as type I ***,when residual stress is considered,these cracks become I-II composite *** stress significantly alters the cumulative energy release rate of the three ***,incorporating the influence of residual stress is essential when assessing the fatigue performance of corroded steel box girders in long-span bridges.

关键词： Residual stress crack propagation corroded steel box girder cumulative energy release rate