Using B3LYP calculations on the 6-311G ++ (d, p) group, the structural characteristics and dissociation properties of the chloroethane molecule are discussed from the perspective of molecular structure under an external electric field (0~10.28 V·nm^-1). The calculation results show that with the increase of external electric field, the total energy of the molecule increases, the bond length of the C—C single bond decreases, the bond length of the C—Cl bond increases, the dipole moment increases, the size of the energy gap bond increases and then decreases. At different frequencies, the infrared absorption peaks respectively have red shift and blue shift phenomena, and the intensity of the Raman peaks changes. In addition, with the increase of the external electric field, the dissociation energy gradually decreases, and it can be seen that the potential energy barrier almost no longer exists when the external electric field reaches 18.00 V·nm^-1, representing that the degradation of the chloroethane has been achieved.

Based on density functional theory (DFT), a B3LYP method at a level of 6-311G++ was used to study physical properties of CO molecules and ions under applied electric field. Total energy, bond length, charge distribution, energy level distribution and infrared spectrum are studied. Degradation of CO under applied electric field was studied according to its potential energy curve. With gradual increase of external electric field (- 0.015 a.u.~0.015 a.u.), the properties of CO change obviously. As the electric field increases from -0.015 a.u. to 0.145 a.u., the potential energy curve shows that the dissociation energy of CO molecules decreases. CO molecular degradation can be achieved as the electric field increases to a certain extent. Similarly, with the increase of external electric field, total energy of CO ions decreases gradually with the increase of electric field. The bond length becomes longer, the dipole moment becomes greater, and the molecular energy gap decreases gradually in the alpha track and increases in the beta track. The intensity of infrared spectrum increases accordingly. When the electric field increases from 0.0 to 0.150 a. u., the potential energy curve indicates that the dissociation energy of CO ions decreases. CO ion degradation can be achieved as the electric field increases to a certain extent.

Numerical simulation on optical cross section (OCS) of complex targets is shown.An adaptive Z buffer method is discussed.Optical hidden facets are processed precisely and subtracted from integral OCS.Optical scattering characteristics described by bidirectional reflectance distribution function (BRDF) are used in numerical simulation.For surface pleats of space targets with grass-like optical scattering characteristics, normal vector model of pleat and scattering model are analyzed.An analysis for OCS experimental evaluation is given.OCS for a downsizing space target with different azimuth and zenith angle attitudes are achieved.Simulation parameters for downsizing target are calibrated with experimental results.Simulation images and trendlines are coherent with experiment results roughly, which indicates that the method describes OCS at a certain extent.

Magnetic properties of transition metal Co doped Fe₃Si alloy are studied with first-principles pseudo-potential plane wave method based on density functional theory (DFT). It shows that magnetism of Fe_3-xCo_xSi mainly results from transition metal elements Fe and Co. Strong-magnetism of Fe_B atom is revealed compared with weak-magnetism of A- and C-site atom. Total magnetic of Fe_3-xCo_xSi decreases slowly in 0≤x≤0.75, but increases rapidly in 0.75≤x≤1.5. Fe_A,C moment shows similar trend. Magnetic moment of Co atoms increases slowly as Co content increases. Change of atomic magnetic moment is related to charge transfer of spin up and down direction.

Mimetic finite difference (MFD) method was applied to numerical simulation of non-Darcy flow in low permeability reservoirs. Principle of MFD method was described in details. And corresponding numerical formula of the non-Darcy flow model was developed. An IMPES scheme was used for solution of two-phase flow simulation. Several numerical examples are presented to demonstrate efficiency and applicability of the scheme.

Non-Newtonian fluid model is introduced into multiphase LBM to investigate non-Newtonian fluid displacement in porous media. To begin with,process of a Newtonian fluid displaced by pseudo-plastic fluid and Newtonian fluid in a simple pore with a small obstacle is studied. It shows that fluid displaced by pseudo-plastic fluid is faster than that by Newtonian fluid. Besides,interface tension effects on displacement process is investigated in detail. It indicates that interface tension plays a resistant role during displacement process. Lower interface tension enhances displacement. By using quartet structure generation set (QSGS) algorithm,we perform a series of modeling of displacement in porous media systems. Impacts of interface tension,wettability and pressure difference on final production are discussed.

With asymptotic assumption for physical field near notch tip, characteristic differential equations for electroelastic singularities of wedges that contain bounded piezo/piezo materials are built from three-dimensional equilibrium equations and Maxell equations. Mechanical and electric boundary conditions are expressed by combination of singularity orders and characteristic angle functions. Thus, evaluation of singularity orders is transformed into solving ordinary differential equations (ODEs) under designated boundary conditions. Interpolating matrix method is introduced to solve derivative ODEs. More electroelastic singularity orders and associated eigenfunctions in wedges that comprise two bounded transverse isotropic piezoelectrics materials are obtained. It shows that the method is efficient and has high accuracy compared with existent solutions.

A detached-eddy simulation (DES) model is proposed based on a fully hydrodynamic pressure model instead of hydrostatic model. The numerical scheme is based on finite volume method (FVM) on unstructured grids in the horizontal plane, and σ coordinate in vertical direction to fix free surface and uneven bottom. The in-house codes are paralleled using OpenMP. The proposed model is shown particularly effective in prediction of small-scale vortical structures.

Based on two annular pressure buildup mechanisms, coupling of wellbore heat transfer and formation heat transfer and coupling of gas temperature and gas pressure, we build a calculation model for critical rate in deep high temperature high pressure( HT/HP) gas wells. It takes account of influence of gas well profile, string assembly and fluid properties. The model is solved with programm based on iterative method. Finally, it is applied to a deep HT/HP gas well in Tarim oilfield. Critical rate under several operational modes are calculated and they provide basis for optimum allocation in deep HT/HP gas wells.

We focus on anisotropic reservoir with natural fractures,and simulate distribution of natural fracture with Monte Carlo. It characterizes natural fracture parameters from the perspective of statistics. Coupled natural and artificial fractures are considered as independent sources. A formula of steady production is derived according to potential superposition principle. It shows that Monte Carlo simulations of natural fractures reflect trends of productivity from a statistical point of view. It analyzes quickly steady productivity of fractured directional well.

To forecast gas leakage of a planned experiment,harmful gas leaking time from a scaled underground explosion cavity and ratio of leaked harmful gas to entire harmful gas are studied with theoretical analysis and numerical simulation.The leakage mechanisms are:(1) gas leaks through uniform porous media,(2) gas leaks through non-uniform porous media,(3) gas leaks through fractures.It shows that leakage time is proportional to two thirds power of explosive amount in scaled underground explosions.Percentages of leaked gas are approximately same for scaled explosions in same media.Theoretical results about leakage time is basically in line with scaled experimental results.

A model of electromagnetic force and temperature field in magnetic levitation induction heating is studied.Influence of electric current,anti-connected coils,metal sphere positions on heating and temperature distributing of metal spheres are analyzed,as well as electromagnetic force.Simulation results are confirmed with experiments.

Homoclinie intemections are soul.ce of chaos for a map.It is convenient to determine whether a given map iS chaotic or not by computing stable and unstable manifolds of its hyperbolic fixed point and observing if there are homoclinic intersections.A new algorithm is presented to compute one-dimensional stable and unstable manifolds of a map.Inspired by a unique property that derivative is transported along the orbit of one-dimensional manifold.position of new point is located quickly with a two-step "prediction and correction" scheme.Tangent component of the manifold is used as reference line to check if the uew point is acceptable.Performance of the algorithm is demonstrated with several typical chaotic maps.It shows that the algorithm is capable of computing both one- dimensional stable and unstable manifolds of maps.

A mathematical model is built for cavity temperature and pressure in underground detonation after the completion of cavity growth.It incorporates gas permeation in porous media,heat radiation between gas and cavity-wall and heat conduction between gas and ambient media.A corresponding one-dimensional code on the basis of spherical symmetry finite volume method is developed. Catty pressure and temperature of an underground nuclear test in alluvium at Nevada Test Site are computed.Measurment data of cavity pressure are analyzed in detail.

A variable-scale lattice gas automata model for gas-solid two-phase flow is established based on lattice gas automata (LGA)in which macroscopic behavior is described with microscopic gas-solid interactions.A two-dimensional flow field is divided into two.deck hexagon laRiees with different scales,where solid particles and gas pseudo-particles are aligned in lattices for solid and gas respectively.In addition to basic LGA rules.collision and propagation rules ale specifically designed for gas-solid systems,as well as additional evolution rules.A statistical method of macroscopic properties and conversion between model parameters and hydrodynamic properties based on similarity principle aIe established. Simulations of dynamic behaviors of gas-solid two-phase flow in a bubbling fluidized bed with this model show good agreement with experiments as well as simulation results with a two-fluid model.It has less average deviation,which validates the proposed model.

In order to balance growth rate of manifold in all directions and construct global manifold structure of a dynamical system,a radial control factor is adopted to normalize the original dynamical system.Taking radius component of the tangent vector as a standard,this method controls manifold expanding at same speed in all directions.Theoretical analysis and example calculation demonstrate that manifolds before and after normalization have same orbit with the original one,which means their global manifold structures are consistent.Lorenz and Duffing systems are taken for examples to demonstrate effectiveness of the proposed approach.It indicates that the method not only get same effect as geodesic process but also present manifold in discrete flow way,which avoids many complicated boundary value problems.

With definition of DHT(distinguished hyperbolic trajectory) and existing measure function in phase space,a measure function in extended phase space is presented.Existing algorithms with constant accuracy parameters is laborious as high precision is required.In order to overcome this shortage,a variable-step convergence algorithm is proposed.The main idea is to estimate initial region with the help of ISP(instantaneous stagnation points) and adopt variable-step grids to increase efficiency.With theoretical analysis and numerical calculation,an optimal range of key parameter is given.Two-dimensional and three-dimensional Duffing systems are used to test the performance.It shows that convergence route gained by the developed measure function is smooth and stable.And the variable-step convergence algorithm is more efficient.

With embedding theorem proposed by Takens,we study methods for choosing proper delay time in phase space reconstruction of chaotic time series.A united method to incorporate advantages of average displacement and mutual information is put forward.In mutual information calculation we employ binary tree coding to divide and mark grids which makes it implemented easily.We determine layer numbers according to percentages of sparse grid.Numerical experiments of R ssler and Lorenz systems verifies accaracy of the method.

We propose a method for data-visualization of smoothed particle hydrodynamics(SPH).Data calculated with SPH on convex or non convex continuum domain are processed.Particle set is discretized into a set of triangular elements by Delaunay triangulation,and only those elements on which nodes interact with each other are kept.With kept elements and data on their nodes a finite element interpolation is employed to derive values on interior points of the elements.A free surface is easily extracted with the method.Feasibility of the method is tested.Methods dealing with walls,severe particle splashing or multi-materials are provided,respectively.They supply feasible ways for realizing a general post-processing software package for SPH and even for gridless methods.

Considering the fact that large deviatoric deformations are always localized in a small narrow region in hypervelocity impact problems,a method named subdomain computation for SPH(smoothed particle hydrodynamics) is developed.The entire computational domain is divided into several subdomains.In subdomains where large deformation is developed more particles are placed,and in subdomains where only small deformation is developed fewer particles are placed.Computational instability induced at interface of two subdomains is discussed and a method to handle the instability is proposed.Numerical simulations of a rod projectile penetrating into a thick target are carried out with the method and traditional SPH.It shows that computation accuracy as well as computation efficiency are improved.

Control and synchronization of chaotic systems are studied.They are transformed into numerical optimization problems.A novel hybridization of differential evolution(DE) and bacterial foraging algorithm(BFOA),called CDEM algorithm,is proposed.The algorithm incorporates an adaptive chemotactic step from the BFOA into DE,which improves convergence of the classical DE.It introduces mutation operation of genetic algorithm for enhancing population diversity.Finally,CDEM algorithm is used to chaotic system control and synchronization.Numerical simulations based on Hénon Map demonstrate effectiveness and stability of the algorithm.Effects of parameters are investigated as well.

A model of sheath formation on a planar electrode in strongly electronegative plasmas is presented.The plasma sheath is studied by using a set of hydrodynamic equations.Spatial potential,net space charge distributions and sheath width as functions of distance are obtained.It shows that in a strongly electronegative sheath a presheath between bulk plasma and sheath hardly exist,and electrons,negative and positive ions in the sheath form a pure positive ion sheath near boundary of electrode.Density of net space charge has a sharp peak near the sheath edge.Compared with an electropositive sheath,it is found that the width of strongly electronegative sheath is much narrower,and the spatial potential within the sheath falls much faster.

Lattice Boltzmann method is employed to study nonlinear heat conduction problems.A kind of lattice Boltzmann model is derived in details and multi-scale algorithm and macroscopic quantity are selected.It is proposed to solve transient responses of nonlinear heat conduction problems.The relation between heat conductivity and temperature meets the multi-polynomial function.Different parameters are considered to verify feasibility of the proposed method.Simulation results are illustrated with comparison in linear case.

Monte Carlo method is used to simulate ions in a double-layer target of Ti film on Al substrate.As high-intensity pulsed ion beam (HIPIB) irradiates on target,deposited energy results in rapid increase of surface temperature.Meanwhile high energy ions make cross mixing among atoms at film and substrate interface.Shooting ions and energy deposition influence melting or vaporization of target materials.It changes adhesion between film and substrate.It shows that cascade collision mixing is not a main process in mixing of a double-layer target by HIPIB irradiation.The most preferable ion current densities lie in a range of 100 A·cm^-2~150A·cm^-2.

Local structure,optical absorption spectra and electron paramagnetic resonance (EPR) spectra of CdCl₂:Ni²⁺ crystal are calculated in a semi-SCF d-orbit wave functions model for free Ni²⁺ ions and a point-charge-dipole model.A complete diagonalization procedure (CDP) and high-order perturbation formulas are used.Results of two methods are compared.

A new algorithm-particle swarm optimization (PSO), based on swarm intelligence, is applied to data processing of film parameters by ellipsometry. For a monolayer absorption film, reflective index, extinction coefficient and film thickness are obtained simultaneously by PSO. Even if the range of parameters is unknown, optimal solution can be obtained rapidly with search in a wide range. Compared with ellipsometry processing and genetic algorithm, the method exhibits high computational precision and high convergence speed.

A multi-dimensional particle-in-cell code KLAP is introduced. Field ionization, impact ionization and two body collision are considered in a one-dimensional code. Moving window technology is used in a three-dimensional code to study laser wakefield acceleration in GeV region. Terahertz radiation, laser propagation in neutral gas medium, surface electron acceleration as well as GeV electron generation in laser wakefield acceleration are studied.

A mathematical model for multiple scattering of light conducted in polymers is presented.Based on the Mie scattering theory,Monte Carlo method is employed and a program is developed.By simulating scattering of a photon,we simulate problem with light source as laser or CCFL.Distribution of light out of source in polymers is obtained by statistic calculation.The results show that a plane light in polymer can be obtained with body scattering principle and intensity distribution of light escaping from polymer can be well controlled.

Power coupled equations for a multi-wavelength broadband Raman amplifier (MBRA) are reasonably simplified.A multi-step average power method is used to compute composite Raman gain of multi-signal in a dense wavelength division multiplexed system (DWDM).A conventional simulated annealing algorithm is applied for optimization of MBRA.A simple object function is proposed considering the gain bandwidth,on-off gain,gain flatness and other characteristic parameters.Influences of the number of pump,input power and wavelength distribution on Raman gain are studied.Relations among gain bandwidth,on-off gain,gain flatness and the number of pump of MBRA are revealed.Simulation shows that the optimal signal bandwidth Δλ becomes boarder with the increasing of the number of pump and narrower with the increasing of Raman gain and the improvement of flatness.

Numerical simulation of dynamic behaviour of internal transport with a barrier trigger in Tokamak plasmas in splitting domain and its parallel computation are shown.The parallel efficiency increases with the computing scale.Numerical results agree well with theoretical analysis.The code adapts to the simulation of nonlinear tearing mode (specially mutiple mode) as well.