A material-invariant (frame indifferent) version of the Maxwell–Cattaneo law is proposed in which the relaxation rate of the heat flux is given by Oldroyd’s upper-convected derivative. It is shown ...that the new formulation allows for the elimination of the heat flux, thus yielding a single equation for the temperature field. This feature is to be expected from a truly frame indifferent description.
In this article, wave propagation characteristics of a size-dependent laminated composite nanostructure coupled with a piezoelectric actuator (PA) is investigated. In order to consider the effects of ...small scale, the governing equations of the laminated composite nanostructure coupled with PA are derived using Hamilton's principle based on the nonlocal strain gradient theory (NSGT). The differential equations of motion are solved with the assistance of the analytical method. Afterward, a parametric study is carried out to investigate the effects of the PA thickness, wave number, angular velocity and the ply angle on the value of phase velocity. The results show that the ply angle plays an important role on phase velocity changes of the laminated composite nanostructure by increasing wave number. It is also observed that by assuming a constant field of phase velocity, increase in the thickness of PA leads to increase in the critical value of external voltage which is associated with increase in the stability of the laminated composite nanostructure coupled with PA.
In this paper, we study the deflection of light by a class of phantom black hole and wormhole solutions in the weak limit approximation. More specifically, in the first part of this work we study the ...deflection of light by Garfinkle–Horowitz–Ströminger black hole and Einstein–Maxwell anti-dilaton black hole using the optical geometry and the Gauss–Bonnet theorem. Our calculation shows that gravitational lensing is affected by the phantom scalar field (phantom dilaton). In the second part of this work, we explore the deflection of light by a class of asymptotically flat phantom wormholes. In particular we have used three types of wormholes: wormhole with a bounded/unbounded mass function, and a wormhole with a vanishing redshift function. We show that the particular choice of the shape function and mass function plays a crucial role in the final expression for the deflection angle of light. In the third part of the paper we verify our findings with the help of standard geodesics equations. Finally, in the fourth part of this paper we consider the problem for the observational relevance of our results studying the creation of the weak field Einstein rings.
The number of molecules used in a typical Molecular Dynamics (MD) simulations is orders of magnitude lower than in the thermodynamic limit. It is therefore essential to correct diffusivities computed ...from Molecular Dynamics simulations for finite-size effects. We present a comprehensive review on finite-size effects of diffusion coefficients by considering self-, Maxwell-Stefan, and Fick diffusion coefficients in pure liquids, as well as binary, ternary, and quaternary mixtures. All finite-size corrections, both analytical and empirical, are discussed in detail. The finite-size effects of rotational and confined diffusion are also briefly discussed.
The low energy interactions between axions and electromagnetic fields that arise in models with heavy dyons charged under a spontaneously broken global axial U(1) symmetry are derived using the path ...integral approach. Hence, generic axion‐Maxwell equations relevant for experimental searches are obtained. It is found that the structure of the axion Maxwell equations can be significantly different compared to what is normally assumed in the literature, as the derived equations feature new axion‐dependent terms including CP‐violating ones. The new terms can reconcile the Peccei–Quinn solution to the strong CP problem with astrophysical axion hints, as well as give unique signatures in light‐shining‐through‐wall and haloscope experiments. Moreover, via the latter signatures, these experiments can indirectly probe the existence of heavy dyons.
It is possible that the interactions between axions and electromagnetic field are mediated by heavy dyons. In this article, the corresponding axion Maxwell equations are derived using the path integral approach. These equations feature novel axion‐dependent terms which can lead to unique signatures in light‐shining‐through‐wall and haloscope experiments.
We derive in the present work topological photonic states purely based on conventional dielectric material by deforming a honeycomb lattice of cylinders into a triangular lattice of cylinder ...hexagons. The photonic topology is associated with a pseudo-time-reversal (TR) symmetry constituted by the TR symmetry supported in general by Maxwell equations and the C_{6} crystal symmetry upon design, which renders the Kramers doubling in the present photonic system. It is shown explicitly for the transverse magnetic mode that the role of pseudospin is played by the angular momentum of the wave function of the out-of-plane electric field. We solve Maxwell equations and demonstrate the new photonic topology by revealing pseudospin-resolved Berry curvatures of photonic bands and helical edge states characterized by Poynting vectors.
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Microgels can deform and interpenetrate and display colloid/polymer duality. The effective interaction of microgels in the collapsed state is governed by the interplay of ...polymer–solvent interfacial tension and bulk elasticity. A connecting neck is shown to mediate microgel interaction, but its temporal evolution has not been addressed. We hypothesize that the necking dynamics of attractive microgels exhibits liquid-like or solid-like behavior over different time and length scales.
We simulate the merging and pinching of attractive microgels with different crosslinking densities in explicit solvent using dissipative particle dynamics. The temporal coalescence dynamics of microgels is investigated and compared with simple liquid and polymeric droplets. We model the neck growth on long time scales using Maxwell model of polymer relaxation and compare the theoretical prediction with simulation data. The mechanical strength of the neck is characterized systematically via simulated pinch-off of microgels by steered molecular dynamics.
We evidence a crossover in the coalescence dynamics reflecting the viscoelastic signature of microgels. In contrast to the common knowledge that viscoelastic materials respond elastically on short time scales, the early expansion of the microgel neck exhibits a linear behavior, similar to the viscous coalescence of liquid droplets. However, the late regime with arrested dynamics resembles sintering of solid particles. Through an analytical model relating microgel dynamics to neck growth, we show that the long-term behavior is governed by stress relaxation of the polymers in the neck region and predict an exponential decay in the rate of growth, which agrees favorably with the simulation. Different from coalescence, the thread thinning in microgel breakup primarily highlights its polymeric characteristics.
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