Cluster dynamics (CD) is a fast method for simulating long-term defect evolution in materials under irradiation. However, CD models based on mean-field rate theory do not account for spatial correlations between defects/clusters in cascades. Object kinetic Monte Carlo (OKMC) models take intrinsically account of defect spatial correlations, but they are limited by time scale and irradiation dose. A CD model with spatial correlation effect, termed as CD-SC, is developed based on a simple constant-time annealing method to determine CD source term by coupling Monte Carlo (IM3D) and OKMC (MMonCa) models. It shows that, results by CD-SC match those by full OKMC well. It is helpful for accuracy improvement of sequential multi-scale models of long-term radiation damage under typical irradiation conditions.

Effect of biofilm structure on bioreaction as well as flow and mass transfer are investigated with lattice Boltzmann method (LBM) on meso-scale. Porous construction of biofilm is regenerated by Quartet Structure Generation Set (QSGS) method, and LB method is coupled with multi-block model to obtain detail information and save computational cost. It indicates that properly increasing porosity benefits mass transportation between main region and biofilm, and hence improve substrate consumption efficiency under condition of stable biofilm structure. At given porosity of biofilm, changing growth construction of biofilm can also promote mass transfer between inner and outer of biofilm, leading to higher substrate consumption efficiency.

Density functional theory on level of B3LYP at 6-311++G(d,p) was used to calculate CCl₃F geometrical parameters, dipole moments, charge distribution and total energies of ground state of CCl₃F molecule under external electric fields(F=-0.025~0.025 a.u.). It shows that with decreasing of C-Cl band distance, charge distribution of Cl increases. Molecular geometric parameter and total energy are strongly dependent on increasing field intensity. IR vibrationt spectrum of CCl₃F molecule shows observable blue shift as electric field increased to F=-0.02 a.u.

With given total toroidal current and central current density of plasma, temperature, density and magnetic field profiles of tokamak plasma with different elongation and triangularity are obtained numerically with Grad-Shafranov equation. Electron cyclotron wave ray trajectories and current drive in configurations are investigated with Fokker-Planck equation incorporated into a ray tracing code. It shows that as electron cyclotron wave of X-mode are launched from top, rays propagate toward low-field side with increasing elongation. As electron cyclotron wave are launched from mid-plane and low-field-side, high quotient power deposition is obtained with greater elongation, and driven current profile is close to central plasma with increase of triangularity. Current drive profile moves toward central plasma and peak current density increases with decreasing poloidal or toroidal injection angle.

We analyze non-physical solutions in laser ray tracing simulation.With a system of nonlinear equations,a new algorithm for intersection is presented.A special preconditioner is used to improve numerical stability.The algorithm is suitable for any intersectant condition.Numerical experiments show that the algorithm has better precision and adaptability.Simulation in LARED code shows good performance.

We introduce an ignition hohlraum 2D-simulation design method with 2D code.A design sequence,in which X-rays drive tempetature is tuned before P² asymmetry,is put forward.Details in designing laser power is studied.It indicates that control of P² asymmetry during trough pulse limits the maximum of filling gas density and expansion of capsule ablator can be restrained by longer drive pulse.An ignition hohlraum 2D-simulation design is given.

Geometries of Mg_xAl_yN (x,y=1-5) clusters are studied by using hybrid density functional theory (B3LYP) with 6-311+G^* basis sets. For lowest-energy structures of Mg_xAl_yN clusters, stabilities and electronic properties are investigated. It shows that planar structures are dominant structures of Mg_xAl_yN (x+y≤4) clusters. The lowest-lying Mg_xAl_yN clusters mostly derived from ground-state structures of Al_nN or Mg_x-1Al_y+1N clusters. Mg_xAl_yN clusters are stable with respect to fragmentation into atoms or smaller clusters. Compared with neighboring clusters, MgAl₃N and Mg₃Al₃N clusters own higher stability. For all Mg_xAl_yN clusters studied, we found co-existence of covalent, ionic, and metallic bonding characteristics. Furthermore, ionization potential and electron affinity exhibit weak oscillations as increasing cluster size. Ro general pattern is observed.

We give a convergence analysis on splitting iterative (SI) algorithm of multi-group radiation diffusion equations. Spectral radii of iterative matrix is shown. Numerical computation and analysis on spectral radii formulae reveal a relation between convergence rate and radiation coefficients. Numerical results confirm theoretical results, and give applicable conditions of the algorithm.

Heating of magnetized plasmas by low-frequency Alfvén waves propagating along background magnetic field is studied with test particle simulation.It shows that ions in perpendicular and parallel directions of the background magnetic field are heated significantly.In a stage of non-resonance heating,perpendicular heating is more significant than parallel heating,and anisotropic temperature comes into being.In a stage of stochastic heating,perpendicular and parallel temperatures of ions finally reach saturation and convergence.In heating process,the maximum kinetic temperature of ions is dependent on the ratio of magnetic field energy density and plasma density,which has no relevance with Alfvön-wave frequency and amplitude.Ions are significantly accelerated in parallel direction.and attained a bulk speed that is roughly equal to phase velocity of Alfvén waves.

Foam microscopic seepage experiments show that foam present two seepage states: Flowing foam and trapped foam.Foam plugging experiment show that foam plugging ability has accumulating effect.Plugging pressure gradient near core inlet is less than that of downstream of the core when foam flooding reaches steady state.A multi-component mathematical model characterizing foam flooding is established based on bubble population balance theory and foam properties.The model is solved numerically with fully implicit method.Validity of the model is verified with foam plugging experiment.Meanwhile,foam microscopic seepage characteristic parameters such as foam texture,pressure and aqueous phase saturation in foam flooding are studied.

We consider a many-particle model which concludes interaction of molecular BEC,and gave a semi-analytical method to calculate conversion efficiency of Fermion atom pairs convert to Boson molecules.The method used mainly independent crossing approximation.With mean-field theory we get an equation for conversione efficiency.Calculating results are supported by numerical simulation and experiment of ⁶Li by Hulet group in 2003.

In this article,long range part of electrostatic interaction is accelerated using GPUs in NIVIDIA CUDA programming environment.Particle Mesh Ewald algorithm is adopted and split into 5 procedures:parameters designation,discretization of point charges into grids,Fourier transformation of grids,potential of electrostatic interaction,and force calculation of electrostatic interaction.The codes are tested by seven biomolecular systems with different sizes.Roughly 7-fold speedup over one core of mainstream CPUs is obtained.The codes can be integrated into molecular dynamic simulation software packages that already exst or used as part of GPU codes developed in the future to further speedup traditional MD simulations.

A series of exact solutions are constructed for two-dimensional radiative transfer and radiative diffusion problems with outer source.These solutions exhibt physical characteristics with simple expressions.Moreover,transport solutions degenerate directly into solutions of corresponding diffusion equations.Test results of the diffusion model with LARED-R are presented and analyzed.

Strong-coupled multigroup radiative transfer in optically thick regions are analyzed.A simple conner balance method in 2D is presented.A grey transport acceleration scheme is generalized to accelerate source iteration convergence of differenced multigroup transport equations.

We provide a radiant energy probing method based on single contour integration,including annulus probing and uniform probing.It probes the radiant field of an anisotropy light source and is used as an efficient visualization method.

Construction of difference schemes for parabolic equations on distorted meshes with large aspect ratio is discussed.The limitation of 9-point scheme is provided.An assistant mesh difference method is proposed for distorted meshes with large aspect ratio to improve precision and efficiency.Based on the conservation law,applying appropriate rezone methods for meshes we modify the 9-point method to reduce computation error due to poor regularity of the meshes and low precision due to the approximation to vertices values by an average of neighboring cell values.The nonlinear system obtained is a different system from the 9-point scheme.Its solution approximates to the solution with the original meshes.The designed scheme is implemented easily and adapts well to distorted meshes.Numerical experiments show good precision and stability.

A new concept of pulse tube refrigerator using gap regenerator as its regenerator is suggested.The physical model of this pulse tube refrigerator is established.The influences of frequency,gap width,opening of orifice and double inlet valves on the refrigerator performance have been analyzed by numerical calculation based on the finite difference method.It shows that in the pulse tube refrigerator with a gap regenerator, the optimum frequency,optimum openings of orifice and double inlet valves are less than those of the pulse tube refrigerator with screen-matrix regenerator.

Based on the MT(Multipole Theory),a new method is presented for calculating the electrical conductance of cables with complicated cross-section.By analyzing two examples, it is proven that the calculating accuracy of the MT is much better than that of the BEM(Boundary Element Method).

Based on the theoretical study of spatial coherence of laboratory x-ray lasers, a principle setup is proposed for x-ray laser holography, and corresponding theoretical simulation is performed for the recording and reconstruction of the lenseless Fourier transform hologram.

The Vlasov-Poisson equations are used to simulate the propagation processes of relativistic electron beam (REB) in one plate or two plates.The position of cumulative maximum space charge,the oscillating frequency,of current J,elrctron number density n and electric field E in different positions versus injecting electron number density n₀ and injecting electron velocity v₀ in one plate model,and the inject-ing current J₀ and the distance between the two plates in two plates model are investigated.Numerical results of virtual cathode position are closed to the results given by stable theory.Its oscillating frequency is in agreement with the empiric expresion (1~√2π)ω_peb.Numerical simulation result for injecting elec-tron beam density having Guass distribution for volecity,spread of energy ΔE_n/E_n < 10% appears to be in largely conformity with the conclusion of monoenergy case in one plate model.