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Non-exotic static spherically symmetric thin-shell wormhole solution in f(Q,T)gravity

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Chinese physics C 2023年第7期47卷 173-189页

作者： Moreshwar Tayde Sayantan Ghosh p.k.sahoo Department of Mathematics Birla Institute of Technology and Science-PilaniHyderabad CampusHyderabad-500078India

In this study,we conduct an analysis of traversable wormhole solutions within the framework of linear f(Q,T)=αQ+βT gravity,ensuring that all energy conditions hold for the entire *** solutions presented in this paper are derived through a comprehensive analytical examination of the parameter space associated with the wormhole *** involves considering the exponents governing the redshift and shape functions,as well as the radius of the wormhole throat(r_(0)),the redshift function value at the throat(∅_(0)),and the model parameters(αandβ).Moreover,we establish bounds on these free parameters,which guarantee the satisfaction of the energy conditions throughout spacetime and also provide two ***,we use the Israel junction condition to observe the stability of a thin-shell around the ***,we calculate the null energy condition criteria as well as the potential for the thin-shell and how it varies with the chosen shape function.

关键词： wormhole energy conditions f(Q,T)gravity junction condition thin-shell

Thin-shell gravastar model in f(Q,T)gravity

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Chinese physics C 2023年第9期47卷 162-173页

作者： Sneha pradhan Debasmita Mohanty p.k.sahoo Department of Mathematics Birla Institute of Technology and Science-PilaniHyderabad CampusHyderabad-500078India Faculty of Mathematics&Computer Science Transilvania University of BrasovEroilor 29BrasovRomania

In the last few decades,gravastars have been proposed as an alternative to black *** stability of a gravastar has been examined in many modified theories of gravity along with Einstein's *** f(Q,T)gravity,a successfully modified theory of gravity for describing the current accelerated expansion of the universe,has been used in this study to examine gravastar in different *** to Mazur and Mottola[***.101,9545(2004);Gravitational condensate stars:An alternative to black holes,I12-011,(2002)],a gravastar has three regions with three different equations of *** this study,we examined the interior of a gravastar by consid-ering p=-ρ EoS to describe the dark sector for the interior *** next region is a thin shell of ultrarelativistic stiff fluid,in which we investigated several physical properties,including proper length,energy,entropy,and surface energy ***,we examined the surface redshift and speed of sound to check the potential stability of our proposed thin-shell gravastar ***,we used the entropy maximization technique to verify the stability of the gravastar model.A gravastar's outer region is a complete vacuum described by exterior Schwarzschild ***,we presented a stable gravastar model,which is singularity-free and devoid of any incom-pleteness in classical black hole theory.

关键词： gravastar stability f(Q,T)gravity

Dynamical system analysis of Dirac-Born-Infeld scalar field cosmology in coincident f(Q)gravity

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Chinese physics C 2024年第9期48卷 199-209页

作者： Sayantan Ghosh Raja Solanki p.k.sahoo Department of Mathematics Birla Institute of Technology and Science-PilaniHyderabad CampusHyderabad-500078India

In this article,we present a dynamical system analysis of a Dirac-Born-Infeld scalar field in a modified f(Q)gravity *** considered a polynomial form of modified gravity,used two different types of scalar potential,polynomial and exponential,and found a closed autonomous dynamical system of *** analyzed the fixed points of such a system and evaluated the conditions under which deceleration to late-time acceleration occurs in this *** note the similarity of the two models and show that our result is consistent with a previous study on Einstein s *** also investigated the phenomenological implications of our models by plotting EoS(ω),energy density(Ω),and deceleration parameter(q)*** e-fold time and comparing to the present *** conclude the paper by observing how the dynamical system analysis differs in the modified f(Q)gravity,and present the future scope of our research.

关键词： Dirac-Born-Infeld field f(Q)gravity dark energy dynamical system analysis

Slow-roll inflation in f(T,T)modified gravity

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Chinese physics C 2023年第12期47卷 162-168页

作者： Aaqid Bhat Sanjay Mandal p.k.sahoo Department of Mathematics Birla Institute of Technology and Science-PilaniHyderabad CampusHyderabad-500078India Faculty of Mathematics and Computer Science Transilvania UniversityIuliu Maniu Str.50500091 BrasovRomania

In this study, we explore the concept of cosmological inflation within the framework of the f(T, T)theory of gravity, where f is a general function of the torsion scalar T and the trace T of the energy-momentum *** is assumed that the conditions of slow-roll inflation are applicable in f(T, T) gravity. To determine different observables related to inflation, such as the tensor-to-scalar ratio r, scalar spectral index ns, spectral index αs, and tensor spectral index nt, the Hubble slow-roll parameters are utilized for a particular model of f(T, T). Lastly, an assessment is carried out to determine the feasibility of the models by conducting a numerical analysis of the parameters. The findings indicate that it is feasible to achieve compatibility with the observational measurements of slow-roll parameters by utilizing different values of the free parameters.

关键词： f(T,T)gravity early-time cosmology dark energy equation of state slow-roll inflation

Compact stars admitting Finch-Skea symmetry in the presence of various matter fields

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Chinese physics C 2023年第1期47卷 234-251页

作者： Oleksii Sokoliuk Alexander Baransky p.k.sahoo Main Astronomical Observatory of the NAS of Ukraine(MAO NASU) Kyiv03143Ukraine Astronomical Observatory Taras Shevchenko National University of Kyiv3 Observatorna St.04053 KyivUkraine Department of Mathematics Birla Institute of Technology and Science-PilaniHyderabad CampusHyderabad-500078India

In the present study,we investigate the anisotropic stellar solutions admitting Finch-Skea symmetry(viable and non-singular metric potentials)in the presence of some exotic matter fields,such as Bose-Einstein Condensate(BEC)dark matter,the kalb-Ramond fully anisotropic rank-2 tensor field from the low-energy string theory effective action,and the gauge field imposing U(1)*** spacetime is matched with both Schwarzchild and Reissner-N?rdstrom vacuum spacetimes for BEC,kB,and gauge *** addition,we study the energy conditions,Equation of State(EoS),radial derivatives of energy density and anisotropic pressures,Tolman-OppenheimerVolkoff equilibrium condition,relativistic adiabatic index,sound speed,and surface *** of the aforementioned conditions are ***,the solutions derived in the current study lie in the physically acceptable regime.

关键词： compact stars Finch-Skea symmetry energy conditions Tolman-Oppenheimer-Volkoff equilibrium condition sound speed

Gravastar in the framework of symmetric teleparallel gravity

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Chinese physics C 2023年第5期47卷 221-231页

作者： Sneha pradhan Sanjay Mandal p.k.sahoo Department of Mathematics Birla Institute of Technology and Science-PilaniHyderabad CampusHyderabad 500078India

We present a novel gravastar model based on the Mazur-Mottola(2004)method with an isotropic matter distribution in f(Q)*** gravastar,which is a hypothesized substitute for a black hole,is built using the Mazur-Mottola *** approach allows us to define the gravastar as having three *** first one is an inner region with negative pressure;the next region is a thin shell that is made up of ultrarelativistic stiff fluid,and we studied the proper length,energy,entropy,and surface energy density for this ***,we demonstrated the possible stability of our suggested thin shell gravastar model through the graphical study of the surface *** exterior Schwarzschild geometry describes the outer region of the *** the context of f(Q)gravity,we discovered analytical solutions for the interior of gravastars that are free of any type of singularity and the event horizon.

关键词： gravastar modified gravity non-metricity kuchowicz metric potential

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Static spherically symmetric wormholes in f(Q,T)gravity

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Chinese physics C 2022年第11期46卷 275-290页

作者： Moreshwar Tayde Zinnat Hassan p.k.sahoo Sashideep Gutti Department of Mathematics Birla Institute of Technology and Science-PilaniHyderabad CampusHyderabad-500078India Department of physics Birla Institute of Technology and Science-PilaniHyderabad CampusHyderabad-500078India

In this study,we obtain wormhole solutions in the recently proposed extension of symmetric teleparallel gravity,known as f(Q,T)***,the gravitational Lagrangian L is defined by an arbitrary function f of Q and T,where Q is a non-metricity scalar,and T is the trace of the energy-momentum *** this study,we obtain field equations for a static spherically symmetric wormhole metric in the context of general f(Q,T)*** study the wormhole solutions using(ⅰ)a linear equation of state and(ⅱ)an anisotropy *** adopt two different forms of f(Q,T),(a)linear f(Q,T)=αQ+βT and(b)non-linear f(Q,T)=Q+λQ^(2)+ηT,to investigate these *** investigate various energy conditions to search for preservation and violation among the obtained solutions and find that the null energy condition is violated in both cases of our assumed forms of f(Q,T).Finally,we perform a stability analysis using the Tolman-Oppenheimer-Volkov equation.

关键词： wormhole EoS energy conditions stability analysis f(Q,T)gravity

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采用析因设计法优化低品位锰矿石的硫化焙烧

中国锰业 1989年第6期7卷 41-43页

作者： p.k.sahoo k.SRINIVASARAO 贾宽贵

印度奥里萨邦凯翁贾尔地区的贫锰矿与硫化剂混合后,在适当的温度下进行焙烧,焙烧产品冷却后,用水浸出可溶的锰。试验变量,即硫化剂用量、焙烧时间和焙烧温度用析因设计法进行了优化。

关键词：析因设计法低品位锰矿石硫化焙烧

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铁置换法从多金属硫化物浸渣中回收铅

有色矿冶 1993年第3期9卷 28-31页

作者： p.k.sahoo p.C.RATH 王凤英

研究了从氨压浸出多金属铜铅锌精矿浸渣中铅的回收。以硫酸盐、碱式硫酸盐和黄钾铁矾混合物形态存在的铅,采用先硫酸浸出再盐浸的早已标准化了的方法,将其转入溶液中。从所得到的氯化铝溶液中以金属铁置换出金属铅,铁置换的条件是用化... 详细信息

研究了从氨压浸出多金属铜铅锌精矿浸渣中铅的回收。以硫酸盐、碱式硫酸盐和黄钾铁矾混合物形态存在的铅,采用先硫酸浸出再盐浸的早已标准化了的方法,将其转入溶液中。从所得到的氯化铝溶液中以金属铁置换出金属铅,铁置换的条件是用化学纯氯化铅试验确定的,发现金属铅被铁置换的速度为活化能分别是40和60kJ/mol的二个过程所控制。最终铅产物的回收率和纯度皆非常好。根据研究结果建议了从该物料中回收铅的流程。

关键词：多金属硫化物浸渣铅铁置换法