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We show that the spherically symmetric black hole (BH) solution of a charged (linear case) field equation of Rastall gravitational theory is not affected by the Rastall parameter and this is consistent with the results presented in the literature. However, when we apply the field equation of Rastall’s theory to a special form of nonlinear electrodynamics (NED) source, we derive a novel spherically symmetric BH solution that involves the Rastall parameter. The main source of the appearance of this parameter is the trace part of the NED source, which has a non-vanishing value, unlike the linear charged field equation. We show that the new BH solution is Anti−de-Sitter Reissner−Nordström spacetime in which the Rastall parameter is absorbed into the cosmological constant. This solution coincides with Reissner−Nordström solution in the GR limit, i.e., when Rastall’s parameter is vanishing. To gain more insight into this BH, we study the stability using the deviation of geodesic equations to derive the stability condition. Moreover, we explain the thermodynamic properties of this BH and show that it is stable, unlike the linear charged case that has a second-order phase transition. Finally, we prove the validity of the first law of thermodynamics.

Underlying the classical thermodynamic principles are analogous microscopic laws, arising from the fundamental axioms of quantum mechanics. These define quantum thermodynamic variables such as quantum work and heat and characterize the possible transformations of open quantum systems. The foremost quantum thermodynamic law is a simple statement concerning the conservation of energy. Nevertheless, there exist ambiguity and disagreement regarding the precise partition of a quantum system’s energy change to work and heat. By treating quantum mechanics as a comprehensive theory, applicable to both the micro and macroscopic domains, and employing dynamical symmetries, we bridge the gaps between five popular thermodynamic approaches to the first law. These include both autonomous and semi-classical formulations, which define work in terms of an ensemble average, as well as the single shot paradigm, where work is defined as a deterministic quantity.

We compare definitions of the internal energy of an open quantum system and strategies to split the internal energy into work and heat contributions as given by four different approaches from the autonomous system framework. Our discussion focuses on methods that allow for arbitrary environments (not just heat baths) and driving by a quantum mechanical system. As a simple application we consider an atom as the system of interest and an oscillator field mode as the environment. Three different types of coupling are analyzed. We discuss ambiguities in the definitions and highlight differences that appear if one aims at constructing environments that act as pure heat or work reservoirs. Further, we identify different sources of work (e.g. coherence, correlations, or frequency offset), depending on the underlying framework. Finally, we give arguments to favour the approach based on minimal dissipation.

The current brake thermal efficiency of advanced internal combustion engines is limited to 50%, and how to further improve the efficiency is a challenge. In this study, a theoretical investigation on engine thermal efficiency was carried out using one-dimension simulations based on the first law of thermodynamics. The energy balance was evaluated by varying parameters such as compression ratio (CR); heat transfer coefficient; intake charge properties; and combustion phasing etc.—their influences on the efficiency limits were demonstrated. Results show that for a given heat transfer coefficient, an optimal CR exists to obtain the peak efficiency. The optimal CR decreases with the increase of heat transfer coefficient, and high CR with a low heat-transfer coefficient can achieve a significantly high efficiency. A higher density and specific heat ratio of intake charge, as well as a shorter combustion duration with a proper CA50 (crank angle at 50% of total heat release), can increase efficiency significantly. Methanol shows an excellent ability in decreasing the peak in-cylinder temperature; and the peak indicated efficiency is relatively higher than other tested fuels. The displacement has few effects on the indicated efficiency, while it shows a strong effect on the energy distribution between heat transfer and exhaust energy. All these strategies with high CR result in high in-cylinder pressure and temperature; which means a breakthrough of material is needed in the future.

Synthetic aperture radar (SAR) is prevalent in the remote sensing field but is difficult to interpret by human visual perception. Recently, SAR-to-optical (S2O) image conversion methods have provided a prospective solution. However, since there is a substantial domain difference between optical and SAR images, they suffer from low image quality and geometric distortion in the produced optical images. Motivated by the analogy between pixels during the S2O image translation and molecules in a heat field, a thermodynamics-inspired network for SAR-to-optical image translation (S2O-TDN) is proposed in this paper. Specifically, we design a third-order finite difference (TFD) residual structure in light of the TFD equation of thermodynamics, which allows us to efficiently extract inter-domain invariant features and facilitate the learning of nonlinear translation mapping. In addition, we exploit the first law of thermodynamics (FLT) to devise an FLT-guided branch that promotes the state transition of the feature values from an unstable diffusion state to a stable one, aiming to regularize the feature diffusion and preserve image structures during S2O image translation. S2O-TDN follows an explicit design principle derived from thermodynamic theory and enjoys the advantage of explainability. Experiments on the public SEN1-2 dataset show the advantages of the proposed S2O-TDN over the current methods with more delicate textures and higher quantitative results.

In this study, collectors with two different designs as solar air heaters were examined. Both collectors have equal dimensions and panels with the same features are placed inside. A zigzag strip is placed within the cavities of the collec-tor I panel. The inside of the cavities of the collector II panel is left empty. The thermal efficiency of the panel was observed by providing air flow from the bottom of both collectors. A good design is essential for an efficient collector. As a result of the studies carried out, according to the second law of thermodynamics, the efficiency of collector I, which has a zigzag inside the panel, is between 20.2% and 38.8%, whereas the efficiency of collector II, which is hollow inside the panel, varies between 17% and 32.2%.

The expansion law proposed by Padmanabhan suggests that the evolution of the volume of the horizon is due to the difference between the degrees of freedom on the horizon and the degrees of freedom in the bulk enclosed by the horizon. In formulating this law, Padmanabhan used the temperature, T = H / 2 π for a dynamical expansion. In this work, we modified the expansion law using Kodama–Hayward temperature, the dynamical temperature, for the horizon, first in ( 3 + 1 ) Einstein’s gravity and extended it to high order gravity theories such as ( n + 1 ) Einstein gravity, Gauss–Bonnet gravity, and more general Lovelock gravity. Contrary to the conventional approach, we expressed degrees of freedom of the horizon in terms of the ‘surface energy’ of the horizon. Also, we have expressed modified expansion law in terms of cosmic components. It then turns out that, it is possible to express the modified expansion law in a form as if T = H / 2 π is the temperature of the dynamical horizon.

Аннотация. В статье предпринята попытка строгой аксиоматизации термодинамики, т. е. построения такого ее изложения, при котором все ее изложение вытекает из нескольких аксиом. При этом оказывается, что классическая точка зрения, состоящая в том, что все здание термодинамики может быть построено на пяти началах (так называемые минус первый, нулевой, первый, второй и третий законы термодинамики), не выдерживает критики - количество аксиом существенно больше. Попытка выявить логическую необходимость введения этих аксиом в основания термодинамики и выявление самой их физической сущности (формулировка) и предприняты в данной статье.

The f ( R ,  T ) gravity as a modified theory of gravity is considered to study the Friedmann–Robertson–Walker (FRW) universe. We consider the case f ( R , T ) = f 1 ( R ) + 2 f 2 ( T ) , where f 1 ( R ) is an arbitrary function of Ricci scalar and f 2 ( T ) is an arbitrary function of the trace of the energy-momentum tensor. Using the usual field equations, the conservation equation does not hold. However, we can redefine the field equations to satisfy the conservation equation. In this paper, we show that the FRW universe, as a closed system, may have a conserved 4-momentum if we assume an interaction between matter and the dark energy component coming from f 2 ( T ) . The rate of the energy transfer between the ordinary matter and the dark energy component induced by f 2 ( T ) is obtained. Then, we derive the first law of thermodynamics by using the field equations and the standard entropy-area law on the apparent horizon. It is shown that there is an equality between the Friedmann equation and the first law of thermodynamics. One can also find an equilibrium description of thermodynamics in f ( R ,  T ) gravity. In addition, we investigate the validity of the generalized second law of thermodynamics. It is shown that the generalized second law of thermodynamics is always satisfied in the FRW universe.

Recently discovered twisted and coiled polymer actuators (TCPAs) show huge potentials in the field of soft robots due to advantages of low cost, large deformation and force, high energy density, long life, compact size, and easy to drive. To realize practical applications of the TCPA in soft robots, the study on its dynamic modeling is necessary. However, the TCPA has an obvious hysteresis nonlinearity, bringing obstacles to its modeling. Although some hysteresis models for the TCPA have been established, the study on its rate-dependent hysteresis modeling is still insufficient. To address this issue, a compound model has been established, in which the thermomechanical model is developed by cascading the backlash-like model and a dynamic linear system to depict the relationship between the output force and temperature. In addition, a thermoelectric model has been developed based on the first law of thermodynamics, whose function is to depict the relationship between the temperature and excitation current. All fitness values in the model validation of the compound model are larger than 87.949%. Hence, the compound model has a good generalization performance.