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Neutral regular black hole solution in generalized Rastall gravity

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Chinese Physics C 2019年第8期43卷 81-85页

作者： Kai Lin Wei-Liang Qian Hubei Subsurface Multi-scale Imaging Key Laboratory Institute of Geophysics and GeomaticsChina University of GeosciencesWuhan 430074HubeiChina Escola de engenharia de Lorena Universidade de S?o Paulo12602-810LorenaSPBrazil faculdade de engenharia de guaratingueta Universidade Estadual Paulista12516-410GuaratinguetaSPBrazil Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou UniversityYangzhou 225009China

We investigate the static, spherically symmetric regular black hole solutions in the generalized Rastall gravity. In particular, the prescription of Rastall gravity implies that the present approach does not necessarily involve nonlinear electrodynamics. Subsequently, the resulting regular black hole solutions can be electrically and magnetically neutral. The general properties of the regular black hole solutions are explored. Moreover, specific solutions are derived and discussed, particularly regarding the parameter related to the degree of violation of the energy-momentum conservation in the Rastall theory.

关键词： regular black hole generalized Rastall gravity static spherically symmetrical spacetime

Shadows of magnetically charged rotating black holes surrounded by quintessence

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Chinese Physics C 2022年第6期46卷 246-256页

作者： Chengxiang Sun Yunqi Liu Wei-Liang Qian Ruihong Yue Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou UniversityYangzhou 225009China Escola de engenharia de Lorena Universidade de Sao Paulo12602-810LorenaSPBrazil School of Aeronautics and Astronautics Shanghai Jiao Tong UniversityShanghai 200240China faculdade de engenharia de guaratingueta Universidade Estadual Paulista12516-410GuaratingueiaSPBrazil

In this work,we study the optical properties of a class of magnetically charged rotating black hole *** black holes in question are assumed to be immersed in the quintessence field,and subsequently,the resulting black hole shadows are expected to be modified by the presence of dark *** investigate the photon region and the black hole shadow,especially their dependence on the relevant physical conditions,such as the quintessence state parameter,angular momentum,and magnetic charge *** photon regions depend sensitively on the horizon structure and possess intricate ***,from the viewpoint of a static observer,we explore a few observables,especially those associated with the distortion of the observed black hole shadows.

关键词： black hole shadow quintessence magnetically charged rotating black hole

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

Formation of TiO_(2) Nanotube Layer by Anodization of Titanium in Ethylene Glycol-H_(2)O Electrolyte

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Journal of Surface Engineered Materials and Advanced Technology 2014年第3期4卷 123-130页

作者： Alain Robin Michele Bernardes de Almeida Ribeiro Jorge Luiz Rosa Roberto Zenhei Nakazato Messias Borges Silva Escola de engenharia de Lorena Universidade de Sao PauloLorenaBrazil faculdade de engenharia de guaratingueta Universidade Estadual PaulistaGuaratinguetaBrazil

In orthopaedics and orthodontics, the growth of nanotubes of titanium oxide on titanium implants is a promising route for improving the osseointegration. Among the fabrication routes to produce nanotubes, anodization was generally preferred due to its simplicity and low cost. TiO2 nanotubes are formed by the simultaneous anodic reaction and chemical dissolution due to the fluoride species present in the anodization bath. In this work, the formation of TiO2 nanotubes was studied in stirred ethylene glycol-H2O electrolyte (90 - 10 v/v) containing NH4F at room temperature. In order to study the effect of NH4F concentration, voltage and anodization time, and to reduce the number of experiments, a design of experiments (DOE) based on a 2k factorial design with four replicates at the center point was used. The analysis of variance (ANOVA) was used to evaluate the effects of the factors of control and their interactions on the percentage of the titanium surface coated by nanotubes. The dimensions of nanotubes (length and diameter) were also evaluated using field emission gun scanning electron microscopy. The cristallinity and phase composition of the oxide layers was investigated by X-ray diffractometry. The electrochemical behavior of as-received and anodized titanium specimens was studied in Ringer’s solution. The statistical analysis showed that fluoride concentration is the most significant factor. The best condition according to the response surface analysis is the center point (1% NH4F, 20 V, 2 h). The nanotubular oxide layers presented an amorphous structure. Electrochemical tests showed that TiO2 nanotubes coated titanium is less corrosion resistant than as-received titanium.

关键词： Nanotubes Titanium Anodization Implants

On the Boundary Condition and Related Instability in the Smoothed Particle Hydrodynamics

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Communications in Theoretical Physics 2019年第11期71卷 1281-1292页

作者： Chong Ye Jin Li Kai Lin Wei-Liang Qian College of Physics Chongqing UniversityChongqing 401331China Centro Brasileiro de Pesquisas Fisicas 22290-180Rio de JaneiroRJBrazil Institute of Geophysics and Geoinforma tics China University of GeosciencesWuhan 430074China Escola de engenharia de Lorena Universidade de Sao Paulo12602-810LorenaSPBrazil faculdade de engenharia de Guaratinguetá Universidade Estadual Paulista12516-410GuaratinguetaSPBrazil School of Physical Science and Technology Yangzhou UniversityYangzhou 225002China

In this work, we explore various relevant aspects of the Smoothed Particle Hydrodynamics regarding Burger's equation. The stability, precision, and efficiency of the algorithm are investigated in terms of different *** particular, we argue that the boundary condition plays an essential role in the stability of numerical ***, the issue is shown to be closely associated with the initial particle distribution and the interpolation *** others, we introduce an interpolation scheme termed symmetrized finite particle method. The main advantage of the scheme is that its implementation does not involve any derivative of the kernel function. Concerning the equation of motion, the calculations are carried out using two distinct scenarios, where the particles are chosen to be either stationary or dynamically evolved. The obtained results are compared with those obtained by using the standard finite difference method for spatial derivatives. Our numerical results indicate subtle differences between different schemes regarding the choice of boundary condition. In particular, a novel type of instability is observed where the regular distribution is compromised as the particles start to traverse each other. Implications and further discussions of the present study are also addressed.

关键词： hydrodynamic model SPH algorithm pair instability

Hawking radiation received at infinity in higher dimensional Reissner-Nordstrom black hole spacetimes

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Chinese Physics C 2021年第8期45卷 182-189页

作者： Kai Lin Wei-Liang Qian Xilong Fan Bin Wang Elcio Abdalla Hubei Subsurface Multi-scale Imaging Key Laboratory Institute of Geophysics and GeomaticsChina University of GeosciencesWuhan 430074China Escola de engenharia de Lorena Universidade de Sao Paulo12602-810LorenaSPBrazil Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou UniversityYangzhou 225009China Faculadade de engenharia de guaratingueta Universidade Estadual PaulistaGuaratinguetaSPBrazil School of Physics and Technology Wuhan UniversityWuhan 430072China Instituto de Fisica Universidade de Sao PauloSao PauloBrazil

In this study,we investigate the Hawking radiation in higher dimensional Reissner-Nordstrom black holes as received by an observer located at *** frequency-dependent transmission rates,which deform the thermal radiation emitted in the vicinity of the black hole horizon,are evaluated *** addition to those in four-dimensional spacetime,the calculations are extended to higher dimensional Reissner-Nordstrom metrics,and the results are observed to be sensitive to the spacetime dimension to an ***,we observe that the transmission coefficient practically vanishes when the frequency of the emitted particle approaches *** increases with frequency and eventually saturates to a certain *** four-dimensional spacetime,the above result is demonstrated to be mostly independent of the metric's parameter and the orbital quantum number of the particle,when the location of the event horizon,rh,and the product of the charges of the black hole and the particle qQ are ***,for higher-dimensional scenarios,the convergence becomes more ***,the difference between states with different orbital quantum numbers is observed to be more *** the magnitude of the product of charges qQ becomes more significant,the transmission coefficient exceeds *** other words,the resultant spectral flux is amplified,which results in an accelerated process of black hole *** relationship of the calculated outgoing transmission coefficient with existing results on the greybody factor is discussed.

关键词： Hawking radiation Reissner-Nordstrom black hole superradiation

Holographic p-wave superfluid with Weyl corrections

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Science China(Physics,Mechanics & Astronomy) 2020年第3期63卷 33-43页

作者： YongHao Huang QiYuan Pan Wei-Liang Qian JiLiang Jing ShiLiang Wang 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 Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou UniversityYangzhou 225009China Escola de engenharia de Lorena Universidade de Sao PauloLorena 12602-810Brazil faculdade de engenharia de Guaratinguetá Universidade Estadual PaulistaGuaratingueta 12516-410Brazil School of Physics and Electronics Central South UniversityChangsha 410083China

In this work,we study the effects of the Weyl corrections on the p-wave superfluid phase transition in terms of an EinsteinMaxwell theory coupled to a complex vector *** the probe limit,it is observed that the phase structure is significantly modified owing to the presence of the higher order Weyl *** latter,in general,facilitates the emergence of the superfluid phase as the condensate increases with the Weyl coupling measured byγ.Moreover,several features about the phase structure of the holographic superfluid are carefully *** a specific region,the phase transition from the normal phase to the superfluid phase is identified to be the first order,instead of being the second order,as in the cases for many holographic *** carrying out a numerical scan of model parameters,the boundary dividing these two types of transitions is located and shown to be rather sensitive to the strength of Weyl ***,a feature known as"Cave of Winds",associated with the emergence of a second superfluid phase,is observed for specific choices of model ***,it becomes less prominent and eventually disappears asγ***,for temperature in the vicinity of the critical one for vanishing superfluid velocity,denoted by T0,the supercurrent is found to be independent of the Weyl *** calculated ratio,of the condensate with vanishing superfluid velocity to that with maximal superfluid velocity,is in good agreement with that predicted by Ginzburg-Landau *** compared with the impact on the phase structure owing to the higher curvature corrections,the findings in our present study demonstrate entirely different *** implications are discussed.

关键词： AdS/CFT correspondence Weyl corrections holographic superfluid

Tail wavelets in merger of binary compact objects

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Chinese Physics C 2020年第7期44卷 1-7页

作者： Kai Lin Wei-Liang Qian Xilong Fan Hongsheng Zhang Institute of Geophysics and Geoinformatics China University of GeosciencesWuhan 430074China Escola de engenharia de Lorena Universidade de Sao Paulo12602-810LorenaSPBrazil faculdade de engenharia de guaratingueta Universidade Estadual Paulista12516-410GuaratinguetaSPBrazil School of Physical Science and Technology Yangzhou UniversityYangzhou 225002China School of Physics and Technology Wuhan UniversityWuhan 430072China School of Physics and Technology University of Jinan336 West Road of Nan XinzhuangJinan 250022China State Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China

We present a model for tail wavelets,a phenomenon known as"echo"in the *** tail wavelet may appear in signal reconnaissances in the merger of binary compact objects,including black holes and neutron *** show that the dark matter surrounding the compact objects lead to a speculated tail wavelet following the main gravitational wave(GW).We demonstrate that the radiation pressure of the main wave is fully capable of pushing away the surrounding matter to some altitude,and splashing down of the matter excites the tail wavelet after ringing down of the main *** illustrate this concept in a simplified model,where numerical estimations are conducted on the specific distribution of dark matter outside the black hole horizon and the threshold values in accordance with *** study the full back reaction of the surrounding dark matter to the metric and find that the effect on to the tail wavelets is *** reveal the fine difference between the tail wavelets of a dressed and a bare black *** demonstrate that the tail wavelet can appear as a natural phenomenon in the frame of general relativity,without invoking modified gravities or quantum effects.

关键词： gravitational wave dark matter tail wavelet

The matrix method for black hole quasinormal modes

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Chinese Physics C 2019年第3期43卷 117-125页

作者： Kai Lin Wei-Liang Qian Hubei Subsurface Multi-scale Imaging Key Lab. Institute of Geophysics and GeomaticsChina University of GeosciencesHubei 430074China Escola de engenharia de Lorena Universidade de S?o Paulo12602-810LorenaSPBrazil faculdade de engenharia de Guaratinguetá Universidade Estadual Paulista12516-410GuaratinguetáSPBrazil School of Physical Science and Technology Yangzhou UniversityJiangsu 225002China

We provide a comprehensive survey of possible applications of the matrix method for black hole quasinormal modes. The proposed algorithm can generally be applied to various background metrics, and in particular, it accommodates both analytic and numerical forms of the tortoise coordinates, as well as black hole spacetimes. We give a detailed account of different types of black hole metrics, master equations, and the corresponding boundary conditions. Besides, we argue that the method can readily be applied to cases where the master equation is a system of coupled equations. By adjusting the number of interpolation points, the present method provides a desirable degree of precision, in reasonable balance with its efficiency. The method is flexible and can easily be adopted to various distinct physical scenarios.

关键词： quasinormal modes black hole spacetime matrix method quasinormal frequency