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Out-of-time-order correlators in the one-dimensional XY model

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Communications in Theoretical Physics 2020年第8期72卷 69-78页

作者： Jia-Hui Bao cheng-yong zhang Department of Physics and Siyuan Laboratory Jinan UniversityGuangzhou 510632China School of Physics and Astronomy Sun Yat-sen University2 Daxue Rd.Zhuhai 519082China

We study the behavior of information spreading in the XY model, using out-of-time-order correlators(OTOCs). The effects of anisotropic parameter γ and external magnetic field λon OTOCs are studied in detail within thermodynamical limits. The universal form which characterizes the wavefront of information spreading still holds in the XY model. The butterfly speed vBdepends on(γ, λ). At a fixed location, the early-time evolution behavior of OTOCs agrees with the results of the Hausdorff–Baker–Campbell expansion. For long-time evolution,OTOCs with local operators decay as for power law t^-1, but those with nonlocal operators show different and nontrivial power law behaviors. We also observe temperature dependence for OTOCs when(γ=0, λ=1). At low temperature, the OTOCs with nonlocal operators show divergence over time.

关键词： out-of-time-order correlators information spreading integrable model

Linear instability of charged massless scalar perturbation in regularized 4D charged Einstein-Gauss-Bonnet anti de-Sitter black holes

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Chinese Physics C 2021年第2期45卷 631-640页

作者： Peng Liu Chao Niu cheng-yong zhang Department of Physics and Siyuan Laboratory Jinan UniversityGuangzhou 510632China

We study the linear instability of the charged massless scalar perturbation in regularized 4D charged Einstein-Gauss-Bonnet-AdS black holes by exploring their quasinormal *** find that the linear instability is triggered by *** charged massless scalar perturbation becomes more unstable with increasing Gauss-Bonnet coupling constant or black hole *** the AdS radius,on the other hand,will make the charged massless scalar perturbation more *** stable region in parameter space(α,Q,Λ)is ***,we find that the charged massless scalar perturbation is more unstable for larger scalar *** modes of multipoles are more stable than that of the monopole.

关键词： black hole quasinormal mode Einstein-Gauss-Bonnet

Porous Alumina Ceramics Fabricated by Spark Plasma Sintering

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Chinese Journal of Aeronautics 2006年第B12期19卷 257-260页

作者： WANG Kun FU Zheng-yi PENG yong WANG Yu-cheng zhang Jin-yong zhang Qing-jie State Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

Porous alumina of regular spherical particles was fabricated with the spark plasma sintering （SPS） and then compared to those obtained through conventional hot pressing （HP）. The effects of the parameters of the heating process on porosity were also investigated, Microstructural studies suggest that porous ingots including regular pores be made out of regular spherical alumina particles due to the close sphere packages. A comparative study on the relative necks of the specimens produced by SPS and HP indicates an enhancement of neck growth with SPS. Contrasting the theoretical values to the experimental results over the relative necks indicates that a proper relationship between the relative necks and the porosity can be established by a sintering model.

关键词： spark plasma sintering (SPS) porous alumina ceramics sintering neck

Instability of regularized 4D charged Einstein-Gauss-Bonnet de-Sitter black holes

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Chinese Physics C 2021年第2期45卷 568-577页

作者： Peng Liu Chao Niu cheng-yong zhang Department of Physics and Siyuan Laboratory Jinan UniversityGuangzhou 510632China

We studied the instability of regularized 4D charged Einstein-Gauss-Bonnet de-Sitter black holes under charged scalar *** unstable modes satisfy the superradiant condition,but not all of the modes satisfying the superradiant condition are *** instability occurs when the cosmological constant is small and the black hole charge is not too *** Gauss-Bonnet coupling constant further destabilizes black holes when both the black hole charge and the cosmological constant are small and further stabilizes black holes when the black hole charge is large.

关键词： black hole Einstein-Gauss-Bonnet instability

Critical scalarization and descalarization of black holes in a generalized scalar-tensor theory

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Science China(Physics,Mechanics & Astronomy) 2023年第10期66卷 44-52页

作者： Yunqi Liu cheng-yong zhang Qian Chen Zhoujian Cao Yu Tian Bin Wang Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou UniversityYangzhou 225009China Department of Physics and Siyuan Laboratory Jinan UniversityGuangzhou 510632China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Department of Astronomy Beijing Normal UniversityBeijing 100875China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou 310024China Institute of Theoretical Physics Chinese Academy of SciencesBeijing 100190China Shanghai Frontier Science Center for Gravitational Wave Detection Shanghai Jiao Tong UniversityShanghai 200240China

We study the critical dynamics in scalarization and descalarization in the fully nonlinear dynamical evolution in the class of theories with a scalar field coupling with both Gauss-Bonnet(GB) invariant and Ricci scalar. We explore the manner in which the GB term triggers black hole(BH) scalarization. A typical type Ⅰ critical phenomenon is observed, in which an unstable critical solution emerges at the threshold and acts as an attractor in the dynamical scalarization. For the descalarization, we reveal that a marginally stable attractor exists at the threshold of the first-order phase transition in shedding off BH hair. This is a new type Ⅰ critical phenomenon in the BH phase transition. Implications of these findings are discussed from the perspective of thermodynamic properties and perturbations for static solutions. We examine the effect of scalar-Ricci coupling on the hyperbolicity in the fully nonlinear evolution and observe that such coupling can suppress the elliptic region and enlarge parameter space in computations.

关键词： black hole(de)scalarization dynamical critical behavior marginally attractor

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Dynamical spontaneous scalarization in Einstein-Maxwell-scalar theory

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Chinese Physics C 2022年第9期46卷 268-275页

作者： Wei Xiong Peng Liu Chao Niu cheng-yong zhang Bin Wang Department of Physics and Siyuan Laboratory Jinan UniversityGuangzhou 510632China Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou UniversityYangzhou 225009China School of Aeronautics and Astronautics Shanghai Jiao Tong UniversityShanghai 200240China

We study the linear instability and nonlinear dynamical evolution of the Reissner-Nordstrom(RN)black hole in the Einstein-Maxwell-scalar theory in asymptotic flat *** focus on the coupling function f(φ)=e^(-bφ^(2)),which facilitates both scalar-free RN and scalarized black hole *** first present the evolution of system parameters during dynamic *** parameter regions in which spontaneous scalarization occurs,we observe that the evolution of the scalar field at the horizon is dominated by the fundamental unstable mode from linear analysis at early *** late times,the nonlinear evolution can be considered to be the perturbation of scalarized black holes.

关键词： black hole quasinormal modes scalarization

Successful Ablation of Cavo-tricuspid Isthmus Dependent Atrial Flutter in a Patient with Senning Operation

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Chinese Medical Journal 2015年第16期128卷 2267-2268页

作者： Jin-Lin zhang cheng Tang yong-Hua zhang Xi Su Department of Cardiology Wuhan Asian Heart Hospital Wuhan Hubei 430022 China

To the Editor：Intraatrial reentry tachycardia （IART） has been reported to occur in 2% to 10% of Mustard and Senning patients at 10 years＇ *** reported a case in which the cavo-tricuspid isthmus （CTI） in both the systemic venous atrium （SVA） and pulmonary venous atrium （PVA） was necessarily targeted in a patient following Senning operation.

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Onset of chaotic gravitational lensing in non-Kerr rotating black holes with quadrupole mass moment

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Chinese Physics C 2023年第8期47卷 122-135页

作者：吴文浩张承勇邵成刚钱卫良 MOE Key Laboratory of Fundamental Physical Quantities Measurement Hubei Key Laboratory of Gravitation and Quantum PhysicsPGMFand School of PhysicsHuazhong University of Science and TechnologyWuhan 430074China Department of Physics and Siyuan Laboratory Jinan UniversityGuangzhou 510632China Escola de Engenharia de Lorena Universidade de São Paulo12602-810LorenaSPBrazil Faculdade de Engenharia de Guaratinguetá Universidade Estadual Paulista12516-410GuaratinguetáSPBrazil Center for Gravitation and Cosmology School of Physical Science and TechnologyYangzhou UniversityYangzhou 225002China

In the electromagnetic channel,chaotic gravitational lensing is a peculiar phenomenon in strong gravita-tional *** this study,we analyze the properties and emergence of chaotic gravitational lensing in the Manko-Novikov black hole *** to better understand the underlying physics,we elaborate on the boundaries of the accessible region through analyses of the contours of the effective *** latter is associated with the two roots of a quadratic *** particular,we explore its interplay with an ergoregion,which leads to specific features of the effective potentials,such as the emergence of a cuspy edge and the formation of a pocket,which serve as static constraints on the ***,we investigate the properties of the radial and angular accelerations at the turning points in photon *** accelerations are further examined and may provide kinematic constraints on the geodesics,as argued *** is concluded that the onset of the chaotic lensing is significantly related to both con-straints;as a result,an arbitrary slight deviation in the incident photon is significantly amplified during evolution through an extensive period,demonstrating the complexity in the highly nonlinear deterministic gravitational system.

关键词： black hole shadow chaos black hole image

Control of Corner Separation for a Linear Compressor Cascade via Bionic Slanting Riblets at the Endwall

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Journal of Thermal Science 2025年第1期34卷 129-144页

作者： zhang Peng LI yonghong cheng Rixin Key Laboratory of Civil Aircraft Airworthiness Technology Civil Aviation University of China College of Aeronautical Engineering Civil Aviation University of China

A new passive control approach,utilizing bionic slanting riblets,is employed to mitigate the flow close to the blade endwall in a linear cascade,and its effectiveness and mechanism in controlling corner separation are investigated through numerical *** slanting riblets are positioned at the endwall upstream of the cascade channel,and the influence of riblet height,yaw angle and relative position on the control of corner separation is *** findings indicate that the application of slanting riblets can efficiently counteract corner separation across the stable operational ***,the introduction of riblets with a height of merely 0.1 times the boundary layer thickness results in a significant reduction in total pressure loss by up to 14.53%,while simultaneously enhancing the static pressure coefficient by 21.74%.Flow analysis reveals that minute vortices produced within the riblet channels tend to coalesce,forming a potent large-scale vortex near the boundary layer's base *** phenomenon results in reduced additional losses compared to conventional vortex ***,the induced vortex promotes enhanced mixing between the mainstream flow and boundary layer,inhibiting the lateral displacement of low-energy fluids within the endwall boundary ***,this delays the onset of separation vortex formation and eliminates vortex rings in the corner region,ultimately enhancing the aerodynamic efficiency of the cascade.

关键词： additional losses compressor cascade corner separation slanting riblets vortex generator