We investigated spontaneous imbibition behavior in a basic bifurcated channel. The rupture and convergence of the two-phase interface in a bifurcated channel is strongly unsteady, which is hard to be described accurately with classical theories and conventional numerical calculation methods. An improved two-component pseudopotential lattice Boltzmann method was employed in simulating the unsteady spontaneous process. It shows that the width of inlet/outlet channel controls the competitive imbibition behavior in the bifurcated channel. Whereas the viscosity ratio between the wetting phase and the non-wetting phase controls the overall spontaneous imbibition behavior. The results provide a basis for quantitative characterization of spontaneous imbibition in complex pore structures.

Molecular dynamics simulations are used to study interfacial interaction and diffusion properties of CNT/polymer chains. It shows that —CH₃ decreases interfacial interaction energies of PE/CNT and PP/CNT systems. However, interfacial interaction energy of CNT/PEO modified with —CH₃ is increased. Compare interaction energies between pure CNT and PE, PP and PEO, we found that the interfacial interaction energy increased as CNT modified with —OH and —COOH. And the strength satisfies —COOH<—OH. Besides, total energies of PE/CNT, PP/CNT and PEO/CNT modified with —CH₃, —OH and —COOH are reduced. The decrease rate follows rule: —COOH < —OH < —CH₃. Coulomb energy plays the main role in the non-bond energies rather than vdW energy. Moreover, diffusion coefficient of functional CNT/PE, CNT/PP and CNT/PEO are obviously reduced by the impose of function groups, and the diffusion coefficient of the polymer chains satisfy —COOH<—OH<—CH₃.

Binding energy, electronic structure and optical properties of pure AlN and Ag, S codoping AlN were calculated with first-principles ultrasoft pseudopotential approach of plane wave based upon density functional theory.It shows that concentration of doping Ag atoms can be increased in AlN and acceptor level becomes shallower by introduction of S atoms. Acceptor Ag atoms play an important role in activating. So Ag, S codoping AlN is expected as an efficient means of p-type doping.Imaginary part of dielectric function and optical absorption spectrum of the doping system show a new peak in low energy region.And absorption edge extends to low energy. Doping system enhances low frequency electromagnetic wave absorption.

Stochastic neutron dynamics is important task in nuclear power plant design and nuclear reactor safety. In this paper, basic concepts and research methods for stochastic neutron kinetics are introduced and historical development and research status in the field are sketched out. Multiplicities of fission neutrons and photons are main sources of zero power reactor noise. Based on description equation of neutron fluctuation and its solution, stochastic theory of zero power and power reactor noise is evolved. Stochastic neutron dynamics are applied in important areas such as reactivity microscopic measurement, power reactor noise measurement and analysis, nuclear criticality excursion analysis, nuclear material detection and identification and so on. In the past half century, however, it lacks available method and tool to implement quantitative analysis of problems such as probability distribution of burst waiting time of neutron initiation in pulse reactor. In recent years, important progress is made in generalized semi-Markov process simulation method, which is applied to stochastic neutron kinetic process simulation. It reveals inherent law of neutron initiation experiments conducted in pulse reactor. At last, research topics to be solved in stochastic neutron dynamics are discussed.