查看更多>>摘要：The interplay between a dS black hole horizon and cosmological horizon in a dS spacetime introduces distinctive thermodynamic behaviors (for example the well-known upper bounds of mass and entropy (Dinsmore et al. in Class. Quant. Grav. 37(5), 2020)). Based on this point, we present the Hawking-Page (HP) phase transition of the four-dimensional dS spacetime with nonlinear charge correction when the effective pressure is fixed, and analyze the effects of different effective pressures and nonlinear charge corrections on HP phase transition. The evolution of this system undergoing the HP phase transition is also investigated. We find that the coexistent curve of HP phase transition is a closed one with two different branches. That indicates there exist the upper bounds of the HP temperature and HP pressure, which is completely distinguished with that in AdS spacetime. With decreasing the distance between two horizons, the dS spacetime at the coexistent curve of HP phase transition is going along with different branches. Furthermore, we also explore the influences of charge and nonlinear charge correction on the coexistent curve.
查看更多>>摘要：In order to grasp the inherent change law of laser to serve people effectively, setting up laser dynamical models is a very important aspect. In this work, we build a new fractional-order delayed single-model laser model. First of all, the existence and uniqueness of the solution to the involved fractional-order delayed single-model laser model is proved. Next, the stability and the generation of Hopf bifurcation are systematically explored. A delay-independent stability and bifurcation condition is obtained. Then, via designing an appropriate PD rho controller, we successfully control the time of onset of Hopf bifurcation for the considered fractional-order delayed single-model laser model. In the end, Matlab simulation results are presented to check the correctness of the derived key fruits. The obtained results in this work are completely novel and have momentous practical value in stabilizing system and control the balance of variables of single-model laser system.
查看更多>>摘要：Non-local and non-convex energies represent fundamental interacting effects regulating the complex behavior of many systems in biophysics and materials science. We study one-dimensional, prototypical schemes able to represent the behavior of several biomacromolecules and the phase transformation phenomena in solid mechanics. To elucidate the effects of thermal fluctuations on the non-convex non-local behavior of such systems, we consider three models of different complexity relying on thermodynamics and statistical mechanics: (i) an Ising-type scheme with an arbitrary temperature-dependent number of interfaces between different domains, (ii) a zipper model with a single interface between two evolving domains, and (iii) an approximation based on the stationary phase method. In all three cases, we study the system under both isometric condition (prescribed extension, matching with the Helmholtz ensemble of the statistical mechanics) and isotensional condition (applied force, matching with the Gibbs ensemble). Interestingly, in the Helmholtz ensemble the analysis shows the possibility of interpreting the experimentally observed thermal effects with the theoretical force-extension relation characterized by a temperature-dependent force plateau (Maxwell stress) and a force peak (nucleation stress). We obtain explicit relations for the configurational properties of the system as well (expected values of the phase fractions and number of interfaces). Moreover, we are able to prove the equivalence of the two thermodynamic ensembles in the thermodynamic limit. We finally discuss the comparison with data from the literature showing the efficiency of the proposed model in describing known experimental effects.
查看更多>>摘要：Spin nonclassicality is the discrete analogue of the continuous variable optical nonclassicality, and may be regarded as a resource related to coherence or quantumness of states with respect to an overcomplete basis consisting of spin coherent states. It plays a significant role in some quantum information processing tasks such as quantum computation and quantum metrology. Detecting and quantifying spin nonclassicality, which are of both theoretical and experimental relevance, have attracted much attention in quantum information theory. In this work, by virtue of the Wigner-Yanase skew information and the resolution of identity induced by spin coherent states, we provide an information-theoretic approach to spin nonclassicality, elucidate its basic properties and illustrate it through some important and widely used spin states. In particular, we derive a convenient criterion for detecting spin nonclassicality and use it to certify spin nonclassicality for some prototypical states.
查看更多>>摘要：Recent studies have shown that a small systematic redshift error (z(g)) of approximate to 10(-4) in the type Ia supernovae (SNe) measurements can affect the estimates of cosmological parameters. Here, we show that it could also lead to a reduction of approximate to 5% in the local value of the Hubble parameter H-0, when very low-z SNe are included in the fit of the magnitude-redshift data. The estimated value, H-0 = 69.60(-1.58)(+1.49) km s(-1) Mpc(-1), differs by approximate to 1.3 sigma from the latest CMB result from the Planck collaboration.
查看更多>>摘要：We study cosmological dynamics of the energy-momentum squared gravity. By adding the squared of the matter field's energy-momentum tensor (zeta T-2) to the Einstein-Hilbert action, we obtain the Einstein's field equations and study the conservation law. We show that, the presence of zeta T-2 term, breaks the conservation of the energy-momentum tensor of the matter fields. However, an effective energy-momentum tensor in this model is conserved in time. By considering the FRW metric as the background, we find the Friedmann equations and by which we explore the cosmological inflation in zeta T-2 model. We perform a numerical analysis on the perturbation parameters and compare the results with Planck2018 different data sets at 68% and 95% CL, to obtain some constraints on the coupling parameter zeta. We show that, for 0 < zeta( )<= 2.1 x 10(-5), the zeta T-2 gravity is an observationally viable model of inflation.
Burgos, C.Cortes, J-CLopez-Navarro, E.Pinto, C. M. A....
12页
查看更多>>摘要：A number of relevant models in Classical Mechanics are formulated by means of the differential equation y ''(t) + At-beta y(t) = 0. In this paper, we improve the results recently established for a randomized reformulation of this model that includes a generalized derivative. The stochastic analysis permits solving that generalized model by computing reliable approximations of the probability density function of the solution, which is a stochastic process. The approach avoids constructing these approximations from limited statistical punctual information and the Principle of Maximum Entropy by directly constructing a sequence of approximations using the Probabilistic Transformation Method. We prove that these approximations converge to the exact density under mild conditions on the data. Finally, several numerical examples illustrate our theoretical findings.
查看更多>>摘要：In the present study, lime-based mortars were analysed to restore an ancient temple situated near the town of Tiruvannamalai in Tamil Nadu, India. Samples were taken from four different locations at the temple. Various techniques such as acid loss analysis, particle size distribution, XRD, XRF, SEM, FTIR, and TGA were employed to characterise ancient mortars and plasters. The binder-to-aggregate ratio was found to be in the range of 1:2.9 to 1:3.2 by acid loss analysis. The presence of organic additives (carbohydrates, proteins, and fats) identified in the analysis of organics was confirmed by FTIR analysis and TGA. Organic additives were added to strengthen the mortar against environmental degradation. The objectives of this study are to investigate the characteristics of traditional materials and techniques employed in the construction of the ancient temple for effective simulation of the conservation process and protection of the temple. The composition of mortars employed in the construction of the temple and the chemical and mineral composition of the binding ingredients used as organic additives were analysed in this study. The optimum binder-to-aggregate ratio for construction was determined to be 1:3. Restoration lime mortar samples matching the ancient mortars were prepared and the chemical and mineralogical properties of fresh and hardened samples, and their durability properties were also studied. It can be concluded that restoration of the temple can be accomplished by preparing suitable lime mortars but with different organic additives.
查看更多>>摘要：Antiferromagnetic spin-1 XYZ model is examined by using a mean-field approach with the introduction of spin operators on the simple cubic lattice. The model includes the crystal field interaction (D-z) along the z-axis, the Dzyaloshinskii-Moriya interaction (Delta(m)) and an external magnetic field with the components of H-x = H-y = H-z = H. The bilinear exchange interaction parameter (J(z)) is taken as a scaling parameter chosen to be negative to simulate the antiferromagnetic interactions between the nearest-neighbor spins. Thermal variations of the total magnetization and its components are investigated in detail to obtain the phase diagrams on the (H /vertical bar J(z)vertical bar, T/vertical bar J(z)vertical bar), (Dz/vertical bar J(z)vertical bar, T/vertical bar J(z)vertical bar) and (Delta(m)/vertical bar J(z)vertical bar, T/vertical bar J(z)vertical bar) planes. The model exhibits antiferromagnetic, paramagnetic and random phase regions. Very interesting various phase lines and critical points are observed including the tricritical points, bicritical points, critical end points and two more. The reentrant behavior is also observed for appropriate values of the system parameters.
Njitacke, Zeric TabekouengFeudjio, CyrilleSigning, Vitrice FolifackKoumetio, Bernard Nzoko...
18页
查看更多>>摘要：In this contribution, an image encryption technique jointly based on the contribution of chaotic behavior resulting from an extreme multistable system and DNA coding is proposed. The chaotic system used is based on a memristive model with quadratic memductance. This memductance is used to build the nonlinear term of a Jerk system. The investigation of the obtained system reveals that it is dissipative and deals with a line of equilibria. Using nonlinear analysis tools, including the two-parameter Lyapunov exponent, the graph of the Lyapunov spectrum, the bifurcation diagram, and phase portraits, to study the considered model, the results show that the considered system is able to exhibit the coexistence of an infinite number of stable states. Besides, the results of this work have been supported by using theoretical, numerical, and experimental approaches. Furthermore, the generated chaotic sequence by the proposed memristive Jerk system is used in the confusion and diffusion steps combined with DNA coding, thus enhancing the efficiency of the cryptosystem. The experimental results and the analyses (statistic, differential, and noise and data loss attacks) sufficiently show that the proposed cryptosystem is robust by the quality of the obtained results.
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Springer Nature