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.

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.

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.

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 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.

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.

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.

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.

Treanor's and Gear's methods are applied to chemical reactions in the process of NO_x/SO₂ removal. The results are satisfactory. The systems of NO-NO₂-N₂,NO-NO₂-N₂-O₂ and NO-NO₂-N₂-O₂-H₂O are discussed. The removal of NO_x and SO₂ is also discussed as CO₂ and SO₂ are added.

In order to evaluate the migration of aerosols in porous media driven by gases, a dual porosity dual permeability mathematical model is proposed in symmetric cylinder coordinates.The processes of permeation, absorption, diffusion and heat exchange are considered. Calculated results show that aerosols could be contained in porous media well. Simulating experiments confirmed the prediction.

To explore the effect of discretization scheme on the simulation results,both the QUICK scheme and the hybrid scheme are applied to the numerical simulation of turbulent flow in a swirl combustor with coaxial jets. The computation adopts the k-εmodel for the closure of turbulence. It is seen that the gas axial and tangential velocities and the root mean square of gas axial fluctuating velocity calculated by utilizing the QUICK scheme agree well with the measured test data, while the calculated results by using the hybrid scheme show obvious deviations from the measurement.

A traveltime interpolation wavefront tracing method for numerical modeling of seismic wave in complex media is developed.It is based on an earth model consisting of uniform-velocity rectangular or polygonal cells with nodes placed at vertices and along cell edges.The wavefronts are propagated away from source throughout the entire model and sampled at the nodes,in which the first arrival time at a node is calculated by the interpolation of two previously computed traveltimes at all pair of adjacent nodes within a cell and minimization of traveltimes in the light of Fermat's principle. Once the wavefront traveltimes are sampled throughout the model, the minimal traveltime and raypaths from the source to receivers are easily obtained using the same technique as above.This method is regardless of model complexity,cell's shape and the positions of source and receivers.It can model all types of first arrival wave,such as direct waves,critical refractions and diffractions,and can trace entirely minimum traveltime paths.So it has a good flexibility and a high precision.At last,the method is applied to first arrival wave modeling of some typical near-surface models,the wavefront shapes and raypaths of which are shown explicitly.

Because the number of tetrahedral elements in three dimensional field division is too great and will need too much computer memory and run time,the control volume finite element method based on parallelepiped elements is presented. In this method,the number of elements is much smaller and the number of points is egual to that in using tetrahedral elements. The divergence theorem can be used to translate the volume integral into the surface integral corresponding to the same control volume of grid points so that the upwind interpolated scheme for convection variables can be used. Through three test problems,it is proved that this method is valid for numerical simulation of three dimensional fluid flow and heat transfer under the limit of computer memory and run speed.

For the purpose of developing swirl combustors with high combustion efficiency and low pollutant emission, a numerical simulation of swirling turbulent flows in a swirl combustor with coaxial jet interactions is performed. A new algebraic Reynolds stress model and the QUICK discretization scheme are utilized in the present calculations. The simulated results of swirling turbulent flows in the combustor for both cases of the coswirl jets and the counterswirl jets are in agreement with the experiment data in terms of the time-averaged gas axial velocity, tangential velocity and static pressure.

The stress produced by a series of chemical explosions were numerically simulated with one dimension spherical symmetric elastic-plastic flow model. The acceleration, velocity, stress and displacement of particle in rock were calculated and the approximate agreement was observed between calculated value and experimental data.

It outlines MCMGP3-A 3-D multigroup P₃ Monte Carlo neutron transport code, which is designed for computation of reactor critical safety. It is developed from the coupled neutron and photon transport Monte Carlo code MCNP with continual point cross sections and the continual point cross section module of MCNP code has been replaced by multigroup cross section module. MCMGP3 code is with the capablilities of MCNP geometry treatment, counting, deviation reducing techniques and plot. Either macroscopic or microscopic cross sections can be used.The neutron scattering angular distribution adopts P₃ approximation and generalized Gaussian quadrature scheme. The sample problem results prove the computational correctness of the code. MCMGP3 code can treat steady or unsteady porblems with exterior source and critical problems. It suits various cross section formats and the energy groups can be expanded easily from one group to multigroup. In addition, the MCMGP3 code has successfully realized the coupled with the reactor lattic code WIMS. It can be used to simulate the full reactor problems.

The total energy and cohesive energy of typical binary compounds, namely, NiAl, SiC, GaAs, MgS and NaCl, are studied by using he linearized augmented plane-wave method. Special emphasis is put on the effects of the choice of muffin-tin radii of the two elements. Results show that, for closely packed alloy NiAl, the variation of MT radius yields little change to the total energy; and the atomic covalent radii could be used in setting the MT radii for covalent crystals such as SiC and GaAs; but the ionic radii are not appropriate for crystals with strong ionic bonds such as MgS and NaCl due to a large number of core electrons lost out of the mufin-tin spheres of cations. The calculated cohesive energies with proper choice of muffin-tin radii are in good agreement with experimental results.

The premixed turbulent reacting flow in an axisymmetric sudden-expansion combustor has been numerically simulated. The k-ε turbulent transport model and the EBU-Arrhenius turbulent reaction model are utilized for the closure of the time-averaged governing equations. The calculated results cover the time-averaged gas flow field, species mass fraction and temperature distributions for the premixed reacting flow in the sudden-expansion combustor. The EBU-Arrhenius model is discussed and evaluated based on the comparisons between the calculated results and the measured data.

The one-dimensional ideal elastic-plastic fluid hydrodynamical model with finite difference method is used to study the processes of formation and decay of the shock waves induced by laser irradiation to solid targets and effects of dynamic fracture.

By means of a hydrodynamic model in which electrons and ions have different temperature and same isothermal expanding velocity,it deals with interaction process of the intense pulse laser with the target,and gives scaling relationships between the plasma parameters and the laser or the target behaviour,in which include equilibrium absorption and radiation in the plasma.

A numerical method and an analytical method for study creation and decay of laser generated shock-wave in the target are presented on the basis of one-dimensional hydrodynamic model.The ablation presure is used as boundary condition.These methods permit the caculation of the three stages of shock-wave evolution.Three kinds of solid state material,such as Al,Cu and C/Ph are caculated.The maximum presure and shock-wave profile of each material are given out.

A mathematical model of pulverized coal combustion is formulated and developed based on a particle continuum-trajectory model.An overall iterative solution procedure for reactive two-phase flows is also proposed.The corresponding CCVC computer code has been developed for calculating two-dimensional, recirculating,reactive,two-phase turbulent flows.It is utilized to numerically simulate the pulverized coal combustion in a combustor of large velocity difference jets which at plesent is widely used in coal fired boilers.

A self-consistent Monte Carlo simulation method that includes charge exchange and elastic scattering is developed to calculate the energy and angle distributions of ions in cathode sheath of a DC argon gas discharge for the different pressures. Cross sections of the charge exchange and the momentum transfer that depend on the ion energy are taken into account precisely. It is found that, as the ions move towards the cathode, the high energy portions of ion energy distributions are enhanced gradually and the small-angle portions of the angle distributions increase. A strong field accelerates the ions to higher speed and ensures that more ions move along the lines of force. The self-consistent electric field spatial variation in the sheath is nonlinear.

This artical uses the non-stationary heat-transfer theory to carry out dynamic simulation for solar green house, establishes the mathematical model of solar green house, uses computer to design and calculate solar house system, analyses the influence to solar green house by various parameters, and taking the area of Henan Province as a example, makes out the optimum designing datum which possess extensive practical value.

The given digital sequence r₁,r₂,…,r_i,…,r_n in the interval (0, 1) on a computer, it is a important problem in the Monte Carlo computation to tost if that the digital sequence can be used as the uniformly distributed random numbers, The software system SUTEST in the statistical package SASD (a package for the Statistical Analysis of Stochastic Data) can be used to test statistical properties of the uniformly distributed random numbers in (0, 1) with 12 kinds,27 different testing methods and 61 statistics from homogeneity, randomnes,independence and simulative computing.SUTEST is developed with portable FORTRAN and can be used on a large, middle or small computer, and microcomputers too.