Advances of phononics in 2012—2022

Due to its great potential applications in thermal management, heat control, and quantum information, phononics has gained increasing attentions since the first publication in Rev. Mod. Phys. 84 1045 (2012). Many theoretical and experimental progresses have been achieved in the past decade. In this paper, we first give a critical review of the progress in thermal diodes and transistors, especially in classical regime. Then, we give a brief introduction to the new developing research directions such as topological phononics and quantum phononics. In the third part, we discuss the potential applications. Last but not least, we point out the outlook and challenges ahead.     

Power—Law in Depth—Dependence of Signal Speed in Vertical Granular Chain

The signal generated by an initial perturbation dispersively propagates in the vertical granular chain under gravity.For the power-law-type contact force,the signal speed follows power-law with the depth.When the perturbation is very weak,the exponent is 1/2(1-1/p).When the perturbation is very strong,the exponent approaches zero.The transition of the exponent from oscillatory regime with weak nonlinearity to quasi-solitary regime with strong nonlinearity is smooth.     

Theoretical Analysis of Ionic Autoionization Spectra of Lanthanum in the Energy Region of 90650—915—00cm^—1

Eigenquantum defects μα and transformation matrix Uiα of La are calculated from the first principles byrelativistic multichannel theory, and dipole matrix elements Dα are obtained by fitting the experimental spectra.With these parameters, ionic autoionization spectra of lanthanum via an intermediatestate (Xe)5d6d^-1 P1 of La . in the energy region of 90650-91500 cm^-1 are calculated within the framework of multichannel auantum defecttheory. Our calculated spectra are in general agreement with the experimental data.     

Behaviour of Internal Stress in Melt—Spun Ni—Mn—Ga Ribbons

We investigate the martensitic transition of melt-spun Ni-Mn-Ga ribbons ,during which an abrupt release of internal stress occurs.The release results in the appearance of two peaks on the curve of field-induced strains versus temperature.During and after the transformation,a large lag of field-induced strains was observed.indicating a competition between the stress energy and Zeemann energy.The lag leads to an unusual relation of the strains to the inducing field.     

Entropy of Neutrino Field in Kerr—Newman—de Sitter Space—time

By using the improved brick wall model,we regard the two null horizons in kerr-Newman-de Sitter space-time as two independent thermal equilibrium systems and we calculate the entropies of both horizons due to neutrino field.We propose that the so-called“superradiant”mode cannot be considered because fermion fields does not display supperradiance.In fact,the nonsuperradiant part does exactly show the expected area-law entropy.Moreover,our cut-offε,which does not require an angular cut-off,is independent of angle θ.     

Modelling of multi-bodies in close proximity under water waves——Fluid resonance in narrow gaps

Viscous fluid model and potential flow model with and without artificial damping force(f=-μV,μ the damping coefficient and V the local averaging flow velocity) are employed in this work to investigate the phenomenon of fluid resonance in narrow gaps between multi-bodies in close proximity under water waves.The numerical results are compared with experimental data available in the literature.The comparison demonstrates that both the viscous fluid model and the potential flow model are able to predict the res...     

Thermal properties of Lense—Thirring spacetime in tetrad theory of gravity

Using the divergence term appearing in the Lagrangian of the teleparallel equivalent of general relativity(TEGR),we calculate the thermodynamic quantities of four tetrads’ spacetime reproducing Lense-Thirring(LT) metric.We also investigate the first law of thermodynamics and the quantum statistical relation.     

Wavelength Dependence of Electro—Optic Coefficients in Chromophore—Incorporated Polymers

Wavelength dependence of electro-optic coefficients in chromophore-incorporated polymers is studied by using the attenuated-total-reflection technique.Experimental result shows that the electro-optic coefficient decreases with increasing light wavelength,which is in agreement well with the theoretical prediction.     

Centrality Dependence of Flow in High—Energy Nucleus—Nucleus Collisions

Directed flow and elliptic flow of final state particles in high-energy nucleus-nucleus collisions in the EMU01 experiment have been studied.The dependences of directed flow and elliptic flow on incident energy and impact centrality of outgoing particles are presented.The results exhibit strong dependence of flow on centrality and energy.We also suggest a more reliable way to determine the event plane resolution here.     

Theory of sound field in a room—re-examination

The theory of steady-state sound field in a room is re-examined. It is shown that the normal-mode solution of the wave equation is not the exact solution, and the derivation is incorrect... The exact solution of the wave equation in a reflective room should contain both the free space solution (direct sound field) and the standing wave solution (reverberant sound field), the latter is formed by all the reflected waves to a group of allowed wave types (the normal modes of vibration ).     

Transverse Flow of Kaons in Heavy—Ion Collisions

The transverse flow of positively charged kaons from heavy-ion collisions at intermediate energy is investigated within the framework of the quantum molecular dynamics model.The calculated results whow that the experimental data are only consistent with those including the kaon mean-field potential from the chiral Lagrangian.This indicates that the transverse flow pattern of kaons is a useful probe of the kaon potential in a nuclear medium.     

Refraction of active waves in reaction—diffusion media

The refraction of active waves is analyzed for a stable—metastable reaction—diffusion system consisting of two regions with different diffusion coefficients. The equations governing the evolution of wavefronts are derived by means of an asymptotic perturbation method for boundary layers. These equations describe non-stationary refraction near the steady state regime. It is shown that the dynamics of wavefronts separates into that in the region near the boundary and that far from the boundary.     

Formation and Distribution of Space—Charge in Cross—Linked Polyethylene

The formation and distribution of space-charge in a cross-linked polyethylene(XLPE) sample are investigated by means of pressure wave propagation,infrared spectroscopy and electrostatic force microscopy(EFM).The related mechanism of space-charge distribution and the structure of XLPE are discussed.The EFM images show that quite large quantitative space-charges locate at the surface of spherulites.     

Characteristics of Period—Doubling Bifurcation Cascades in Quasi—discontinuous Systems

Many systems can display a very short,rapid change stage(quasi-discontinuous region)inside a relatively very long and slow change process.A quantitative definition for the “quasi-discontinuity“ in these systems has been introduced.With the aid of a simplified model,some extraordinary Feigenbaum constants have been found inside the period-doubling cascades,the relationship between the values of the extraordinary Feigenbaum constants and the quasi-discontinuity of the system has also een reported.The phenomenon has been observed in Pikovsky circuit and Rose-Hindmash model.     

Generalized synchronization of chaos in erbium—doped dual—ring lasers

We investigate chaotic synchronization in the generalized sense in unidirectionally coupled erbium-doped fibre dual-ring lasers. Numerical simulation shows that no matter whether the two different erbium-doped fibre dual-ring lasers are chaotic or not before coupling, they show generalized synchronization with a suitable unidirectional coupling coefficient under which the maximum condition Lyapunov exponent is negative. We also use the auxiliary system approach to detect the generalized synchronization.     

Self—Organization of CdS Nanoparticles in Polystyrene Film

Self-organization of nano-CdS particles in polystyrene can be observed by encapsulating the particles with ndodecyl mercaptan owing to a strong electron transfer interaction between the modified CdS nanoparticles and aliphatic carbons in polystyrene.Consequently,ultraviolet/visible absorption edge of the treated nano CdS/polystyrene composites is further blueshifted in addition to the shift caused by the quantum size effect,and the fluorescence emission peak of the composite becomes redshifted and narrow.