A random four-parameter method is used to reconstruct pore structure of heterogeneous sandy conglomerate. Imbibition behavior of wetting fluid in porous media is studied with an improved SC-LBM (Shan-Chen lattice Boltzmann) model. It shows that interfacial dynamics at the initial stage is closely related to the arrangement of pore skeleton, and the imbibition interface is mainly formed by matrix. As fluid flows through the pore throat, the flow cross section shrinked instantly, leading to a rapid increase in pressure gradient and flow resistance. The presence of hole roar pressure leads to the flow cross section shrinked instantly, which increases the flow resistance, indicating that the change of pore radius has a great influence on imbibition rate. In the later stage, the wetting fluid forms a dominant imbibition channel, which reduces the swept area and greatly reduces the imbibition displacement rate. This study is helpful to understand the spontaneous imbibition of fluid in heterogeneous pores, and is of great significance to imbibition and oil displacement in fractured tight reservoirs.

A method of directly solving the heat conduction equation is used to numerically study a controllable thermal cloaking technology with adaptive heat source.We explore heat flow control method and cloaking effect,and deduce general solution of distribution of adaptive heat source in the thermal cloak region with two-dimensional arbitrary symmetrical section under uniform background. Simulation results show that for a cloak with arbitrary symmetrical section,the adaptive heat source makes disturbed temperature field turn to the background temperature field and achieves the purpose of thermal cloaking.

Analyzing advantages and disadvantages of three Riemann solvers of AC(Acoustic), MFCAV(Multi Fluid Channel on Averaged Volume) and HLLC for compressible multimaiterial fluid problems, we constructed an adaptive Riemann solver(ADRS) as a weighted average of three solvers. Rule for designing weights is discussed in detail. ADRS Riemann solver is applied to a compatible cell-centered Lagrangian method which resisting spurious mesh deformation by viewing MFCAV as a modification of AC solver. Numerical examples include Taylor Green vortex problem are given to show efficiency of the method.

Electronic structures, half-metallic and magnetoelectric properties of pure LiZnN, Mn-doped LiZnN and Mn-doped LiZnN with excess and deficient of Li are geometrically optimized and calculated by using first principle density functional theory based on full potential linearized augumented plane wave method. It reveals that doping of Mn leads to a spin polarized impurity band with a spin polarization of 100%. The system exhibits half-metallic ferromagnetism properties, and strong Mn-N covalent bonds are formed. In Li vacancy system, covalent bonds of Mn-N bonds are strongest. Their bond lengths become shorter, and half-metallic is obviously enhanced. Formation energy of the system decrease, which indicates that the structure is more stable. In Li excess system, half-metallic property of the system disappears and becomes metallic. Impurity band width increases and conductivity of the system increases, but interaction of Mn-N bond becomes weaker. It indicates that magnetic and electrical properties of Mn-doped LiZnN new diluted magnetic semiconductor can be regulated separately via Mn isovalent doping and off-stoichiometry. Ground state of Mn doped LiZnN system is ferromagnetic, and net magnetic moment of the system is mainly contributed by Mn atoms. It is found with Heisenberg model that Li vacancy system increases Curie temperature.

Thomas-Fermi approximation (TFA) and imaginary-time propagation method are used to study ground states of rotating Bose-Einstein condensates in an annular trap. Ground state density profiles of condensates experience a transition from vortex lattice phase to giant vortex phase with increase of angular frequency or with increase of width and center height of trap potential. Particularly, ground state density profiles change from a disc shape into an annulus shape with the increase of width and center height of trap potential, when angular frequency is zero. Finally, comparison between ground state density profiles, obtained by analytical method and numerical method is made. They coincide with each other.

Cryosorption of oxygen produced in chemical oxygen iodine laser(COIL) is considered. From the view point of mass conservation, a linear relation between gas pressure gradient and gas velocity is used with which gases flows through a zeolite porous bed is obtained. An adsorption balance equation, describing relation of components in gas flow and adsorped components,is established with adsorption dynamics equation. Henry relation is employed as isothermal equation. A set of cryosorption model equations is solved numerically. Oxygen concentration evolution,and long time character of concentrations are given.

A brief introduction to development history of computational electromagnetics(CEM) and numerical methods in CEM is provided. In addition, we discuss up-to-date progress of CEM in scientific researches, commercial softwares and proprietary softwares. Considering applications of electromagnetics environmental effects (E3), we present development of our numerical simulation platform of E3. Finally, future trends of development in E3 are shown.

We investigate relaxation absorption of ultrasound and speed of sound dependence on temperature and constituent concentration of gas mixture.Two three-dimensional models,one based on molecular relaxation model and the other on sound velocity, are established for a sample consisting of carbon monoxide, nitrogen and oxygen.An algorithm is developed to reconstruct simultaneously temperature field,concentration field and flow of the mixture in sensing domain.Numerical simulation shows that the algorithm is feasible and applicable to measurement of complicated multi-physics fields.Errors arising in simulation are discussed.It is possible to use the algorithm for other component mixtures.

We choose a confined point-contact geometry as research model. Steady-state oscillations of magnetic vortex driven by a spin-polarized current are calculated with analytical calculations based on Thiele's equation. It indicates that magnetic vortex can maintain steady oscillations in a specific current range. Current density range depends on nanocontact dimensions and dot aspect ratios. Both orbital radius and frequency of steady oscillations increases with current density. Adjustable range of oscillation frequency decreases dramatically with increasing nanoeontaet size.

A full wave numerical method is developed for fast wave current drive in tokamak plasmas,in which finite Larmor radius effects and parallel dispersion are taken into account.A physical model with full wave are developed.Electric field distribution in radial is obtained.It shows that fast wave can propagate to central plasma;Mode conversion happened near central plasmas;Fast wave can drive current in centre to improve balance current profile;Parallel electric is weaker than that in vertical direction.The current is droven by Landau damping and transit-time magnetic pumping.

Global linear stability of compressible,three-dimensional flow around a sphere is investigated with a quasi-linearization method on Navier-Stokes equations.An implicit restarted Arnoldi approach is adopted to solve the eigenvalue problem.The global stability problem of three-dimensional compressible basic flows around a sphere is investigated at subcritical parameters of Reynolds number Re=200,Mach number M=0.2,and supercritical parameters of Re=300,M=0.6.It shows that the increasing of Mach number(up to 0.6) has no qualitative influence on transition of flow patterns.

A convolution type semi-analytical approach is proposed for structural dynamic response.With convolution original governing equation is transformed into a complete initial-value problem with initial conditions.The equation is mathematically equivalent to Gutrin's variational principle while it involves no functional and complicated calculation in variational principle.The new governing equation is solved by differential quadrature method in space domain and analytical series in time domain to obtain dynamic response.Dynamic response of a beam is studied.It is shown that the proposed method is accurate and efficient.

Metropolis-Monte Carlo simulation is made to investigate autocorrelation of conformation energy and tangent vectors of minicircles(less than 500 base pairs) with flexible hinges.Direct conformation information and topology of minicircle containing flexible hinges are demonstrated.It provides powerful support for the existence of flexible hinge.

A parallel smoothed molecular dynamies (SMD) method is proposed. Parallel programs with SMD and SMD-MD coupling are developed for loading problems of a plate with a crack and a nano single crystal copper beam subjected to remote tensile. With traditional molecular dynamics, smoothed molecular dynamics method introduces fixed background mesh and solves motion equations. Critical time step in SMD is controlled by background grid size and could be enlarged to save simulation time. Results are in agreement with those of traditional molecular dynamics. Compared with traditional MD simulation, SMD and SMD-MD coupling methods save computing time.

A unified method is proposed to treat 3D moving boundaries at arbitrary velocity as an extension of kinetic format and bounce-back format. Velocities at inlet and on solid wall are special cases of the model. A simplified expression is given in a three dimensional 15-velocity model. Numerical simulation for a diagonally lid-driven three-dimensional cavity flow is performed to verify this scheme. Compared with finite difference method (FDM), the proposed method proves reasonable.

A Godunov-type ALE (Arbitrary Lagrangian-Eulerian) method based on finite volume technique is developed to simulate compressible multimaterial flows with large deformation.The method adapts well to Lagrangian,ALE or Eulerian formulations due to its arbitrary moving speed of meshes.Numerical features are studied in the formulations.Numerical traits of several Godunov-type schemes are studied.Resolutions of scheme for shock and contact are compared.

Techniques to treat interaction of tracked discontinuities,such as "stack",in a one-dimensional front-tracking method based on conservation (conservative front-tracking method) are developed and described in details.A numerical example is presented to illustrate the efficiency of the techniques.

We present temporal segmentation and retrieval of stored memories or patterns with neural networks of a widely used model, the Fitzhugh-Nagumo neurons. For a superposition of several stored input patterns, it is shown that the proposed neuronal network is capable of segmenting out each pattern one after another in the time domain as synchronous firings of a subgroup of neurons. And as a corrupted input pattern is presented, the network is shown to be able to retrieve the perfect one. That is to say it has the function of associative memory. By adjusting parameters as coupling strength and intensity of the noise it is shown that the temporal segmentation attains its optimal performance at intermediate noise intensity, which is reminiscent of the stochastic resonance observed in the coupled spiking neuronal networks.

A conservative front-tracking method^[8,9] has been developed. The main feature of the method is that it uses the conservation property of the solution rather than the Hugoniot conditions to track discontinuities. The goal of this paper is to realize the method for the Euler system in an almost second order fashion. Euler system has three different kinds of characteristics, and waves propagate along the characteristics. Thus, to do the front-tracking, in the vicinity of the tracked discontinuities, it is necessary to spearate the waves in other characteristic fields from the tracked discontinuities and then distribute them to the solution on the two sides. An almost second order accurate wave separation procedure be designed, which can separate waves and then distribute them. Numerical examples show the effciency of the method.