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Test particles and quasiperiodic oscillations around Kiselev black hole with cloud of strings

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Chinese Physics C 2024年第5期48卷 293-308页

作者： Javlon Rayimbaev Uktambek Eshimbetov Bushra Majeed Ahmadjon Abdujabbarov Alisher Abduvokhidov Bakhrom Abdulazizov Akram Xalmirzayev School of Mathematics and Natural sciences New Uzbekistan UniversityMovarounnahr Str.1Tashkent 100000Uzbekistan School of Engineering Central Asian UniversityTashkent 111221Uzbekistan university of tashkent for applied sciences Str.Gavhar 1Tashkent 100149Uzbekistan Institute of Fundamental and applied Research National Research University TIIAMEKori Niyoziy 39Tashkent 100000Uzbekistan National university of Uzbekistan Tashkent 100174Uzbekistan Ulugh Beg Astronomical Institute Astronomy Str.33Tashkent 100052Uzbekistan tashkent State Technical university Tashkent 100095Uzbekistan College of Electrical and Mechanical Engineering(CEME) National University of Sciences and TechnologyRawalpindiPakistan Andijan State university Universitet Str.129Andijan 170100Uzbekistan Namangan State university Boburshoh Str.161Namangan 160107Uzbekistan

In the present study,we investigate the dynamics of test particles around a Schwarzschild black hole surrounded by quintessence and immersed in a scalar string cloud *** start our study by defining the possible values of the quintessence and cloud of string parameters corresponding to the existence of the black hole horizon for fixed values of the parameters of the equation of state for dark *** also study the effects of the effective potential on the circular motion,energy,and angular momentum of the test particles together with the innermost stable circular orbits(ISCOs).We investigate the fundamental frequencies in the particle oscillations along stable circular *** relate the stability of the orbits to the Lyapunov exponent,and the chaotic behavior is studied ***,we apply the fundamental frequencies to describe quasiperiodic oscillations(QPOs)and find that,in the presence of both fields,low-frequency twin-peak QPOs are not *** addition,we obtain the constraint values for the string cloud parameter and mass of the black hole candidates located in the center of the microquasars GRO J1655-40 and GRS 1915+105 as well as the Milky Way galaxy.

关键词： quintessential field black holes string cloud quasiperiodic oscillations

Exploring the shadow of a rotating charged ModMax black hole

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Communications in Theoretical Physics 2024年第2期76卷 89-101页

作者： Khurshid Karshiboev Farruh Atamurotov Ahmadjon Abdujabbarov Ali Övgün Anvar Reyimberganov Institute of Theoretical Physics National University of UzbekistanTashkent 100174Uzbekistan New Uzbekistan university Movarounnahr Street 1Tashkent 100000Uzbekistan Central Asian university Milliy Bog'Street 264Tashkent 111221Uzbekistan university of tashkent for applied sciences Str.Gavhar 1Tashkent 100149Uzbekistan tashkent State Technical university Tashkent 100095Uzbekistan Ulugh Beg Astronomical Institute Astronomy Street 33Tashkent 100052Uzbekistan Institute of Fundamental and applied Research National Research University TIIAMEKori Niyoziy 39Tashkent 100000Uzbekistan Physics Department Eastern Mediterranean UniversityFamagusta99628 North Cyprusvia Mersin 10Turkey Urgench State university Urgench 220100Uzbekistan

The research presented in this paper discusses the impact that the parameters of charge(Q)and screening factor(γ)have on properties of the horizon and silhouette of rotating charged Mod Max black holes which were reviewed in[***.J.C(2022)82:1155]recently,building upon previous findings in the ***,the study explores the behavior of null geodesics,which can help us better understand the apparent shape of the black hole’s silhouette,as well as the distortion parameter and approximate radii of the silhouette that are influenced by the aforementioned parameters,and there are some values of parameter Q which corresponds to data from the Event Horizon Telescope(EHT).Notably,we explore the distortion parameter and approximate radii of the silhouette,revealing that while an increase inγleads to a growth in silhouette radius(Rs),it simultaneously reduces the distortion rate(δs).Conversely,heightened Q charge results in a reduction of Rsaccompanied by an increase inδ***,the paper analyzes the effects of the black hole’s parameters on the effective potential and energy emission:the peak value of the energy emission rate experiences a decrease as the screening factor(γ)increases,while it increases with higher values of the charge parameter(Q).

关键词： black hole ModMax gravity rotating black hole black hole shadow

A regular MOG black hole's impact on shadows and gravitational weak lensing in the presence of a quintessence field

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Communications in Theoretical Physics 2024年第8期76卷 91-102页

作者： Ahmad Al-Badawi Sanjar Shaymatov Mirzabek Alloqulov Anzhong Wang Department of Physics Al-Hussein Bin Talal UniversityPO Box:2071111Ma’anJordan Institute for Theoretical Physics and Cosmology Zhejiang University of TechnologyHangzhou 310023China tashkent State Technical university Tashkent 100095Uzbekistan university of tashkent for applied sciences Str.Gavhar 1Tashkent 100149Uzbekistan New Uzbekistan university Movarounnahr Street 1Tashkent 100000Uzbekistan Institute of Fundamental and applied Research National Research University TIIAMEKori Niyoziy 39Tashkent 100000Uzbekistan GCAP-CASPER Physics DepartmentBaylor UniversityWacoTX 76798-7316United States of America

We investigate the impact of the modified gravity(MOG)field and the quintessence scalar field on horizon evolution,black hole(BH)shadow and the weak gravitational lensing around a static spherically symmetric *** first begin to write the BH metric associated with the MOG parameter and quintessence scalar *** then determine the BH shadow and obtain numerical solutions for the photon sphere and shadow *** show that the MOG(α)and the quintessence(c)parameters have a significant impact on the BH shadow and photon *** on the analysis,we further show that the combined effects of the MOG parameter and quintessence field can increase the values of BH shadow and photon sphere *** also obtain constraints on the BH parameters by applying the observational data of Sgr A^(★)and M87^(★).Finally,we consider the weak deflection angle of BH within the context of the Gauss-Bonnet theorem(GBT)and show that the combined effects of the MOG and quintessence parameters do make the value of the deflection angle increase,and find this remarkable property is in good agreement with the physical meaning of both parameters that can maintain the strong gravitational field in the surrounding environment of a BH.

关键词： modified gravity shadows gravitational weak lensing quintessence field

Shadows and weak gravitational lensing for black holes within Einstein-Maxwell-scalar theory

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Chinese Physics C 2024年第09期48卷 238-247页

作者： Ahmad Al-Badawi Mirzabek Alloqulov Sanjar Shaymatov Bobomurat Ahmedov Department of Physics Al-Hussein Bin Talal University Institute of Fundamental and applied Research National Research University TIIAME university of tashkent for applied sciences Institute for Theoretical Physics and Cosmology Zhejiang University of Technology Western Caspian university

In this study,we investigated the optical properties of charged black holes within the Einstein-Maxwellscalar(EMS) *** evaluated the shadow cast by these black holes and obtained analytical solutions for both the radius of the photon sphere and that of the *** observed that black hole parameters γ and β both influence the shadow of black *** also found that the photon sphere and shadow radius increase as a consequence of the presence of the parameter γ.Interestingly,the shadow radius decreases first and then remains unchanged owing to the impact of the parameter β.Finally,we analyzed the weak gravitational lensing and total magnification of lensed images around black *** found that the charge of the black holes and the parameter β both have a significant impact,reducing the deflection ***,the same behavior for the total magnification was observed,also as a result of the effect of the charge of the black holes and the parameter β.

关键词： Einstein Maxwell gravity gravitational weak lensing shadow

Neutrino oscillations in the Non-Kerr black hole with quantum phenomenon

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Chinese Physics C 2024年第07期 59-70页

作者： Husan Alibekov Farruh Atamurotov Ahmadjon Abdujabbarov Vokhid Khamidov Ulugh Beg Astronomical Institute university of tashkent for applied sciences New Uzbekistan university tashkent State Technical university Institute of Theoretical Physics National University of Uzbekistan Institute of Fundamental and applied Research National Research University TIIAME tashkent university of Information Technologies named after Muhammad al Khwarizmi

In this study, we have investigated the mathematical components of the Dirac equation in curved spacetime and how they can be applied to the analysis of neutrino oscillations. More specifically, we have developed a method for calculating the phase shift in flavor neutrino oscillations by utilizing a Taylor series expansion of the action that takes into account ?m4orders. In addition, we have used this method to assess how the phase difference in neutrino mass eigenstates changes according to the gravitational field described by the Johannsen spacetime.

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Phase structures and critical behavior of rational non-linear electrodynamics Anti de Sitter black holes in Rastall gravity

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Communications in Theoretical Physics 2024年第4期76卷 134-152页

作者： Yassine Sekhmani Dhruba Jyoti Gogoi Ratbay Myrzakulov Javlon Rayimbaev Ratbay Myrzakulov Eurasian International Centre for Theoretical Physics Astana 010009Kazakhstan L.N.Gumilyov Eurasian National university Astana 010008Kazakhstan Department of Physics Moran CollegeMoranhatCharaideo 785670AssamIndia Theoretical Physics Division Centre for Atmospheric StudiesDibrugarh UniversityDibrugarh 786004AssamIndia New Uzbekistan university Movarounnahr Str.1Tashkent 100000Uzbekistan university of tashkent for applied sciences Gavhar Str.1Tashkent 100149Uzbekistan National university of Uzbekistan Tashkent 100174Uzbekistan

This research paper presents a black hole solution with a rational nonlinear electrodynamics source within the Rastall gravity *** paper analyzes the thermodynamic properties of the solution in normal phase space and explores its critical *** phase structure is examined using the extended first law of thermodynamics,with the cosmological constantΛserving as pressure *** isotherms exhibit van der Waals behavior at small values of horizon r_(+).The paper also investigates the Gibbs free energy behavior and finds two critical points with two pressures where the re-entrant phase transition occurs and *** also explore the prevalent microstructure of black holes in Ruppeiner geometry,uncovering significant deviations in the nature of particle interactions from conventional ***,the thermodynamic geometry is analyzed using the Ruppeiner formalism,with the normalized Ricci scalar indicating possible point-phase transitions of the heat capacity,and the normalized extrinsic curvature having the same sign as the normalized Ricci *** three-phase transitions of the heat capacity are those that we find for the normalized Ruppeiner ***,there is an absolute correspondence.

关键词： Rastall gravity biack hole Phase structures

Point defects in 2-D liquid crystals with a singular potential:Profiles and stability

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Science China Mathematics 2024年第11期67卷 2515-2540页

作者： Zhiyuan Geng Wei Wang Basque Center for applied Mathematics School of Mathematical sciences Zhejiang University

We study radial symmetric point defects with degree k/2 in the 2-D disk or R2in the Q-tensor framework with a singular bulk energy,which is defined by Bingham ***,we obtain the existence of solutions for the profiles of radial symmetric point defects with degree k/2 in the 2-D disk or ***,we prove that the solution is stable for |k| = 1 and unstable for |k| > *** identities are derived and utilized throughout the proof of existence and stability/instability.

关键词： radial symmetric point defects singular bulk potential Bingham closure stability

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Performance of Text-Independent Automatic Speaker Recognition on a Multicore System

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Tsinghua Science and Technology 2024年第2期29卷 447-456页

作者： Rand Kouatly Talha Ali Khan Faculty of Tech and Software Engineering University of Europe for Applied SciencesPotsdam 14469Germany

This paper studies a high-speed text-independent Automatic Speaker Recognition(ASR)algorithm based on a multicore system's Gaussian Mixture Model(GMM).The high speech is achieved using parallel implementation of the feature's extraction and aggregation methods during training and testing *** memory parallel programming techniques using both OpenMP and PThreads libraries are developed to accelerate the code and improve the performance of the ASR *** experimental results show speed-up improvements of around 3.2 on a personal laptop with Intel i5-6300HQ(2.3 GHz,four cores without hyper-threading,and 8 GB of RAM).In addition,a remarkable 100%speaker recognition accuracy is achieved.

关键词： Automatic Speaker Recognition(ASR) Gaussian Mixture Model(GMM) shared memory parallel programming PThreads OpenMP

Smart beam via electrically addressing the dye-doped and polymer-stabilized cholesteric liquid crystals

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Chinese Optics Letters 2024年第5期22卷 111-116页

作者：彭程徐春庭胡伟 College of Engineering and applied sciences Nanjing UniversityNanjing 210023China

Smart beams play a vital role in modern intelligent vehicles and have recently attracted significant attention.A spatial light modulator with high optical efficiency,low cost,and compact size is crucial for designing smart ***,we mix cholesteric liquid crystals with dichroic black dye and a *** UV polymerization,the sample exhibits a low driving voltage of 26 V,a high transmittance of over 70%,and an On-off ratio over 280,thanks to the joint contribution of both the absorption and the scattering effect.A smart beam device is demonstrated by electrically addressing the dye-doped and polymer-stabilized cholesteric liquid crystal with pixelated *** patterns with arbitrary designs are projected *** switching time reaches several tens of *** strategy brings new designs to intelligent vehicles and may also inspire applications in public information displays,advertising,and even AR/VR displays.

关键词： cholesteric liquid crystal spatial light modulation smart beam dye guest-host effect

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