An improved LB pseudo-potential multi-relaxation multiphase model is used to study flow characteristics of single/dual droplets impacting liquid film. Development of liquid film impacted by a single droplet under different gas-liquid density ratio was investigated. It was found that with decrease of density ratio, top of coronal crown started bending inward, and bottom radius is significantly reduced. Then, double droplets impinging on liquid film was studied with large density ratio. It shows that a central jet was generated as double droplets impacting on liquid film. Increase of horizontal spacing between droplets delaied the appearance of central jet and reduced height of the initial central jet. With the increase of Re, height of the central jet increased obviously.

As an important multi-scale coupling method, lattice Green function (LGF) bridges gap between density functional theory (DFT) calculations on atomic scale and large-scale continuum medium elasticity theory, especially for material containing dislocation-doping complex. With LGF equilibrium dislocation core structure can be obtained. It provides basis for DFT calculations of interaction between dislocation and doping atoms. Based on lattice dynamics and force-constant matrix, LGF of perfect nickle lattice is obtained with special k-points sampling and Fourier transform, which can be applied in multi-scales calculation of nickle-base superalloy.

With pseudo-potential plane-wave based on density functional theory (DFT), effects of zinc vacancies on ZnO lattice parameters and electronic structure of Al-P co-doped were studied. Formation energy, density of states are analysed. It shows that Al_Zn-P_Zn has the lowest formation energy and presents n-type in the process of co-doping. Presence of zinc vacancies make cell volume decrease, and lattice constant c increase and decreases as concentration of zinc vacancies increase. According to formation energy of co-doping, formation of zinc vacancies system is more stable than Al_Zn-P_O. System with Al and P ratio of 1:2 co-doping can reduce formation energy and become more stable. With comparisons of band structure of V_Zn and 2V_Zn, it is found that band gap increased with zinc vacancies increasing, which makes p-type ZnO more obvious and enhances conductivity of Al_Zn-2P_Zn co-doping systems. However, for Al_Zn-2P_Zn co-doping of 2V_Zn, it shows great superiority of p-type. According to state density analysis, Al_Zn-2P_Zn of 2V_Zn makes the state density more diffuse, and go through the Fermi level, which leads to formation of obvious p-type. As a result, better p-type ZnO can be obtained by controlling Al/P in proportion of 1:2 co-doing with zinc vacancy to 2V_Zn.

Natural convection heat transfer in a porous medium with partially thermally active walls is studied with lattice Boltzmann method. Convective flow heat transfer with different heating and cooling zones, porosity, Darcy number and Rayleigh number is investigated. It reveals that at Da=10^-4 a circulating flow pattern at the middle of the cavity is found, and porosity have great influence on heat transfer at large Rayleigh numbers; As Darcy number is increased to 10^-2, streamlines exhibit a flow pattern with two vortices, and porosity have great influence on heat transfer at low Rayleigh numbers. Location of partially thermally active walls has significant influence on flow pattern and heat transfer in cavity. Bottom-top with bottom heating and top cooling provides a greater heat transfer rate compared with other partial heating. It is better than fully heated wall of cavity.

We study numerical methods for coupled radiative transfer and electron energy equations. In highly opaque materials, strong coupling between them results in stiff source terms, making design of efficient and stable algorithms a challenging task. In this paper, we develop an efficient algorithm for multi-group radiative transfer equations coupled with electron energy equations. It is an integration method based on an ansatz of electron temperature. It poses no constraint on time step, and gives physically relevent solutions under reasonable assumptions. Numerical results show that the method is highly efficient and accurate.

In large eddy simulations (LES), a flat ground model and rough wedge ground models with different wedge heights were adopted to investigate near-surface wind field characteristics under condition of time-varying upstream inflows. In both flat ground model and rough wedge ground models, simulated results show that there is downdraft in peak period of gusty wind and updraft in valley period, respectively. Intensity of downdraft/updraft flows are related to ground roughness in upwind areas and amplitude of inflows. It follows that wind velocity and direction in atmospheric boundary layer always change over time in time-varying upstream inflows, which enhances transportation of mass and energy in actual atmospheric boundary layer.

A mathematical model for numerical simulation of 2D water-oil phase reservoir concerning start-up pressure gradient is solved with full implicit finite difference scheme. A reduced-order model is established by projecting original model in low dimension space formed by basis functions, which is produced from collected snapshots; CVT-Lloyd algorithm is employed in cluster analysis to tackle with flaws from collecting snapshots of same time interval. Computational results show that reduced-order model established based on POD is able to approximate the original model effectively. With cluster analysis, data reduction is eliminated, which could create uniform snapshots in space resulting in enhanced accuracy of reduce-order model. On the other hand, extremely limited clustering groups may lead to loss of information and thus impairing accuracy of reduced-order model.

Geometric structure of W_mB_n(m+n≤7) clusters are optimized by using density functional theory at B3LYP/LANL2DZ level. For ground state configurations, average binding energies, second order differential energies, energy gaps and WIB bond orders are analyzed. It shows that ground state structures of WB_n clusters are flat structures; as m≥2 and m+n≥4, all clusters are cube structure except W₃B cluster. Stability of clusters is getting better and better as W atoms increase. The bonding strength of W-W is significantly higher than those of W-B and B-B key. W atom plays a leading role in stability of clusters. Stability of W₂B₂ and W₃B cluster is the best.

Possible equilibrium geometries of W_mC_n clusters are optimized by using density functional theory at B3LYP/LANL2DZ level.For ground-state structures,average binding energy,second difference in energy,HOMO-LOMO gaps and the Wiberg bond index are analyzed.With increasing tungsten atoms,structures of clusters transform from linear into planar,and then become three-dimensional structures.All spin multiplicity is not more than 5.Hybridization of carbon atoms enhanced stability of the clusters,but reduced chemical activity.And Wiberg of W-C is much stronger than that of W-W and C-C,so it is easier to form W-C bond in W_mC_n clusters.

First-principles investigation on inelastic electron tunneling spectra of 1,6-hexanedithiol and 1,4-benzenedithiol molecular junctions with metal electrodes are performed.It shows that vibrational peaks in inelastic electron tunneling spectra are sensitive to electrode material and distance between sulfur atoms and electrodes.It hence provides unambiguous evidence that electrode material and metal-molecule bond length are crucial for inelastic electron transport through molecular junctions.The peak heights are mainly attributed to coupling energies between electrode and molecule.

With plane-wave pseudo-potential method of first-principles,effect of dopant Fe on dehydrogenation characteristics of LiAlH₄ and mechanism were studied.Dopant formation energy,electronic density of states and dissociation energy of H were investigated.Bonding state and structure-stability of the crystal were analyzed.It indicates that as Fe occupied an interstitial site,an Al site or an Li site,dehydrogenation properties of LiAlH₄ were improved.Fe tended to occupy the interstitial site.Analysis on electronic structure reveals that there exist strong interactions between a dopant Fe and its nearest neighbouring Al atoms as Fe occupied an interstitial site.Meanwhile,interaction between a dopant Fe and its nearest neighbouring H atoms is also considerably strong.Stability of the [AIH₄] ligand is distorted.Therefore,dehydrogenation properties of LiAlH₄ are improved.In general,dopant Fe improve dehydrogenation properties of LiAlH₄,which is consistent with experimental observations.

Lattice Boltzmann thermal models with second-order accuracy are obtained with an extra parameter term.They are employed to Rayleigh-Benard convection heat transfer and are compared with original models.In order to reduce error of Nu number at large Ra number and thermal diffusivity,we analyze truncation error of corresponding heat-transfer equation and introduce an adjusting parameter in the equilibrium distribution function.Applicability of LBM heat-transfer models is extended.

An idiographic method for calculating periodic solutions is proposed as stiff phenomena occur.Program ODE15s for stiff initial value problems is adopted.The Gear's method with variable step length is used and corresponding formula is derived.Numerical example shows good efficiency.

Möbius inverse formula is an old theorem in number theory. Professor Chen Nanxian extended it to ordinary function and presented a new method for solving many inversion problems in physics. This paper introduces Chen's theorem with a more comprehensible way and shows its vast range of application prospects by some concrete problems.

Some potential problems are studied by applying boundary element method.The starting equation in the form of discretization is obtained by weighting residual.The computer software for numerical simulation has been provided.Numerical results conform to physics law and are satisfactory.

A Practical Monte Carlo Sampling Library is described. The library provides pesudorandom number generators using the best algorithms, excellent random variable generators of many important probability distributions such as spatial position, energy and motion direction distributions often used in particle transport problems. In addition a special test system for sampling library is designed and applied. The library runs on PC/386 (486). Its installation and usage are very easy. It can be applied in various fields and easy portable.

A conversion lormula of the count rate in the measuring interval for the radioactive decay and an iterative program for fitting multi-component decay curves wity count rate correction are reported, the proposed program gas been used successfully to analyse artificial decay curves and experimetal decay curves. The comparison with conventional medhod shows that the present medhod gives satisfactory results.

This paper introduees the finite analytic method, then gives a few results of the finite analytic method for unsteady one-dimensional convective transport equations. An example showing effictiveness of FAM is given.