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The density of states of long-range Blume—Emery—Griffiths (BEG) and short-range Ising models are obtained by using Wang—Landau sampling with adaptive windows in energy and magnetization space. With accurate density of states, we are able to calculate the microcanonical specific heat of fixed magnetization introduced by Kastner et al. in the regions of positive and negative temperature. The microcanonical phase diagram of the Ising model shows a continuous phase transition at a negative temperature in energy and magnetization plane. However the phase diagram of the long-range model constructed by peaks of the microcanonical specific heat looks obviously different from the Ising chart.

We investigate the segregation effect of binary granular mixtures with the same size but different densities under vibration at different air pressures. Our experiments show that the segregation state is seriously dependent on the air pressure and there is a new type of partially segregated state at high air pressure, which has the characteristic that the lighter grains tend to stay at the bottom and form a pure layer, while heavier grains and remained lighter ones tend to rise and to form a mixed layer on the top of the system. We redefine the order parameter to study the variation of the segregation effect with the air pressure and vibration parameter in detail. Finally, the mechanism of the air-driven segregation is illustrated by the faster acceleration due to the airflow through the granular bed for lighter particles.

In this paper, a fuzzy inference method based on the notion of fuzzy concept lattice is studied. We first propose a new form of fuzzy concept lattice, and then based on three kinds of known fuzzy concept lattices and our new fuzzy concept lattice, two coherent fuzzy inference methods, the lower approximate fuzzy inference and the upper approximate fuzzy inference, are proposed, and the combined use of the two methods will make the fuzzy inference more precise.

Segregation in vertically vibrated binary granular mixtures with same size is studied experimentally. A new partial segregated state is found in this system. This state exists between the completely mixed state and the pure segregated state, and has the characteristic that the lighter particles tend to rise and form a pure layer on the top of the system while the heavier particles and some of the lighter ones stay at the bottom and form a mixed layer. The ratio of the thickness of the pure top layer and that of the whole system varies continuously with the vibration frequency or amplitude. It is suggested to consider the ratio as an order parameter for describing the degree of the segregation quantitatively. By use of the order parameter, a detailed phase diagram is obtained in Γ versus f space. Finally, the formation of the observed partial segregated state is illustrated by the competition between the impact of momentum of the heavier particles and the stiffness of the layer composed of the mixed particles.

The frequency dependence of the in-plane angular change of the antiferromagnetic resonance (AFMR) field of KCuF3 is systematically measured at frequencies ranging from 3.8 to 10.6 GHz at 4.2 K. The effect of inequivalent g-tensors is found to gradually diminish with decreasing the frequency, and completely vanish when the frequency is decreased to the lower-frequency branch of C-band, while the effect of the effective anisotropy field is significantly enhanced with decreasing the frequency. The calculated AFMR field Hres based on the eight-sublattice model proposed by Yamada and Kato [J. Phys. Soc. Jpn. 63 (1994) 289] is in good agreement with the experimental data.

We consider the relaxation processes of parametric excitation of magnons in a microwave resonator. Using the approach of unitary transformation, we calculate the effective amplitude of three-boson terms of Hamiltonian, especially for photon–magnon interaction which is expected to contribute to the resonance linewidth of ferromagnets.

We consider the process of parametric resonance of magnons in magneto-ordered crystals in a microwave resonator. The nonlinear interaction of the resonator photons with the parametric magnon pairs is analysed theoretically and the result expressed by the deviation frequencies relative to the pump frequency further demonstrates that the dynamics of resonator modes plays an important role once the pump power exceeds the threshold of parallel pumping.

Granular flow is usually divided into three kinds of flow pattern, namely quasi static flow, slow flow, and rapid flow. The core issue of the research is the constitutive relation. A series of constitutive relations of application value have been received up to now, however, the study on principal theory is insufficient. Granular flow has an emergent mesoscopic structure, such as force chain network and vortex, involving complex irreversible processes. This paper studies its mesoscopic structure and principal characters, introduces the concept of two granular temperatures Tconf and Tkin of the granular flow to characterize the degree of chaotic motion and disordered configuration evolution, sets them as the non-equilibrium variables to constitute the thermodynamic state variables set for granular flow with the classical irreversible thermodynamic (CIT) variables, also determines the granular flow law of energy conversion and the entropy production rate, etc., and develops the two granular temperatures (TGT) model. Taking the simple shear quasi-static granular flow in a constant volume as example, and combining it with the discrete element method (DEM), this work confirms the material parameters needed for the TGT model, and analyzes the law of developing period and the effective coefficient of friction of steady period of granular flow.

The velocity of sound in soap foams at high gas volume fractions is experimentally studied by using the time difference method. It is found that the sound velocities increase with increasing bubble diameter, and asymptotically approach to the value in air when the diameter is larger than 12.5 mm. We propose a simple theoretical model for the sound propagation in a disordered foam. In this model, the attenuation of a sound wave due to the scattering of the bubble wall is equivalently described as the effect of an additional length. This simplicity reasonably reproduces the sound velocity in foams and the predicted results are in good agreement with the experiments. Further measurements indicate that the increase of frequency markedly slows down the sound velocity, whereas the latter does not display a strong dependence on the solution concentration.

The apparent mass at the bottom of a granular pile confined in a vertical tube decreases for denser granular packing. We report that the denser granular packing comprising two different diameters of granules augments the apparent mass instead. This anomalous behavior occurs when small granules are stacked on the large ones. In the case of anomalous increase, a percolation effect is found and correlated with the augment of apparent mass at the bottom of the granular column. Finally, the results are qualitatively explained by using the Janssen model.

A systematic study about the cyclic segregation observed experimentally in a vertically vibrated quasi two-dimensional binary granular mixture is reported. The frequency-amplitude phase diagram was obtained, in which the region of cyclic segregation was found. We also measured the period of the cyclic segregation and showed the relationship between the period and total volume of granular mixture. Finally, the competition mechanism of percolation and condensation from Hong’s theory is used to explain the cyclic segregation and volume effect qualitatively.

Static packing structures of two-dimensional granular chains are investigated experimentally. It is shown that the packing density approximates the saturation with the exponential law as the length of chain increases. The packing structures are globally disordered, while the local square crystallization is found by using the radial distribution function. This characteristic phase of chain packing is similar to a liquid crystal state, and has properties between a conventional liquid and solid crystal.

A hybrid method of solving the electromagnetic inverse scattering problem in a lossy medium is proposed. The gradient search method is first used to determine the spatial distribution of the target, then the Monte Carlo method is selected to calculate the conductivity and permittivity of the scatterer. The results of numerical experiments verify that the hybrid method of combining the two ways is high-precision, efficient, and suited to global optimization.

We investigate the deflection and the fluctuation of stresses due to different sizes of granular material in a cylindrical column. It is experimentally observed that the saturation mass systemically increases with granule diameter. The results indicate the shielding of vertical stress in silo is varying. We show that the ratio between the horizontal and the vertical stresses, K, decreases with the increase in grainule diameter d. In addition, it has also been found that the presence of larger granules leads to stronger stress fluctuation on the bottom plate of silo.

Two inversion methods for electromagnetic scattering, the deterministic gradient search method and the Monte Carlo random search method， are proposed in this paper. Firstly, the fundamental principles of the two methods are introduced. Inversion properties including the positioning capability of the scattering body, inversion accuracy and inversion time of the two methods are analyzed and compared. Simulation results demonstrates that the deterministic gradient search method can be used for scattering body positioning and the results using Monte Carlo random search method have high-precision at the same time have high speed. Successive applications of both methods fully realize the advantages of the two methods and improve the inversion result.

A new phenomenon of granular segregation is observed, in which the binary granular mixture submitted to the vertically vibration behaves in cyclic segregation patterns which switches between the Brazil nut, reverse Brazil nut and sandwich patterns with a frequency that accelerates with time. The rule of cycing is investigated, and the phase diagram is depicted. The new phenomenon is qualitatively explained in terms of the collision, friction and air dissipation, and it was experimentally verified that the cycling of segregation patterns has close relation with the presence of air.

In this paper we briefly review the latest progress on the propagation of stress in granular bed and the resistant force of an object moving in granular media, and report our studies on the grain-size effect, which revals the discrete properties of granular media. We found that the sinking depth of a sphere on a granular bed driven by its own weight decreases monotonically with increasing grain-size. The supporting force of the granular bed experienced by the intruder sphere, during sinking, is measured. It is found that except for about 1 mm depth near the surface, the supporting force and the sinking depth of the sphere is related by a power-law with exponents between 1.5—1.0. The exponent decreases with increasing grain-size. This-size dependence of the power-law relation can be a macroscopic manifest of the reorganization of the stress chains in the granular system during the sinking process of the intruder sphere.

The criticality of the dilute-to-dense transition in an inclined two-dimensional(2D) granular channel flow is investigated. The waiting time t before the transition occurs and after the flow is initiated is recorded. It is found that the probability function C(t) for the flow remaining dilute at time t decays exponentially with a characteristic time α-1(d). The characteristic time is found to be fitted well by a power law a(dc-d)-γ, where dc is the critical opening size: as for d>dc, the transition will never happen. The existence of a critical opening size at the exit confirms that the dilute-to-dense transition in 2D granular flow is a critical transition.