2,636 research outputs found
Rate of the phase transition for a charged anti-de Sitter black hole
Phase transition is a core content of black hole thermodynamics. This study
adopted the Kramer's escape rate method for describing the Brownian motion of
particles in an external field to investigate the intensity of the phase
transition between small and large black hole states. Some existing studies
mostly focused on the formal analysis of the thermodynamic phase transition of
black holes, but they neglected the detailed description of the phase
transition process. Our results show that the phase transition between small
and large black holes for charged anti-de Sitter (AdS) black holes presents
serious asymmetric features, and the overall process is dominated by the
transition from a small black hole to a large black hole. This study filled a
research gap of a stochastic process analysis on the issue of the first-order
phase transition rate in the AdS black hole.Comment: 8 pages, 3 figures, to appear in SCIENCE CHINA Physics, Mechanics &
Astronomy (http://engine.scichina.com/doi/10.1007/s11433-022-2022-6
Diagnosis inspired by the thermodynamic geometry for different thermodynamic schemes of the charged BTZ black hole
Due to the asymptotic structure of the black hole solution, there are two
different thermodynamic schemes for the charged Banados-Teitelboim-Zanelli
(BTZ) black hole. In one scheme, the charged BTZ black hole is super-entropic,
while in the other, it is not (the reverse isoperimetric inequality is
saturated). In this paper, we investigate the thermodynamic curvature of the
charged BTZ black hole in different coordinate spaces. We find that in both
schemes, the thermodynamic curvature is always positive, which may be related
to the information of repulsive interaction between black hole molecules for
the charged BTZ black hole if we accept an empirical relationship between the
thermodynamic curvature and interaction of a system. More importantly, we
provide a diagnosis for the discrimination of the two schemes from the point of
view of the thermodynamics geometry. For the charged BTZ black hole, when the
reverse isoperimetric inequality is saturated, the thermodynamic curvature of
an extreme black hole tends to be infinity, while when the reverse
isoperimetric inequality is violated, the thermodynamic curvature of the
extreme black hole goes to a finite value.Comment: v1: 12 pages; v2: title changed and some comments added; v3:add some
comments;v4: final version to appear in The European Physical Journal
Computation Offloading for Edge Computing in RIS-Assisted Symbiotic Radio Systems
In the paper, we investigate the coordination process of sensing and
computation offloading in a reconfigurable intelligent surface (RIS)-aided base
station (BS)-centric symbiotic radio (SR) systems. Specifically, the
Internet-of-Things (IoT) devices first sense data from environment and then
tackle the data locally or offload the data to BS for remote computing, while
RISs are leveraged to enhance the quality of blocked channels and also act as
IoT devices to transmit its sensed data. To explore the mechanism of
cooperative sensing and computation offloading in this system, we aim at
maximizing the total completed sensed bits of all users and RISs by jointly
optimizing the time allocation parameter, the passive beamforming at each RIS,
the transmit beamforming at BS, and the energy partition parameters for all
users subject to the size of sensed data, energy supply and given time cycle.
The formulated nonconvex problem is tightly coupled by the time allocation
parameter and involves the mathematical expectations, which cannot be solved
straightly. We use Monte Carlo and fractional programming methods to transform
the nonconvex objective function and then propose an alternating
optimization-based algorithm to find an approximate solution with guaranteed
convergence. Numerical results show that the RIS-aided SR system outperforms
other benchmarks in sensing. Furthermore, with the aid of RIS, the channel and
system performance can be significantly improved.Comment: 13 pages, 7 figure
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