With empirical electronic theory of solids and molecules (EET), actual model for unit cell of cementite was built. A statistical method was applied to compute valence electron structure (VES) of cementite of θ-Fe₃C with specified number of Fe atoms substituted by alloyed atom of M(Cr, V, W, Mo, Mn). By definition stability factor, stability of alloyed cementite with different type, number and site of Fe atoms substituted were calculated and analysized. It shows that density of lattice electron, symmetry of bonds and bond energy have great influence on stability of alloyed cementite. It is more stable as M substitutes for Fe² than Fe¹. Alloyed cementite is the most stable as Cr, Mo, W and V substitutes for 2 atoms of Fe² at sites of No.2 and 3 or No.6 and 7. Stability of alloyed cementite decreases in order of W, Cr, V, Mo and Mn.

Two-dimensional axi-symmetric gas-solid two-fluid model was established. Under three conditions of source: E0/10,E0/100,E0/1 000 (initial energy per mass of gas),diminishing of gas energy and gas pressure caused by packing particles was studied. It shows that: With higher initial energy per mass of source kinetic and internal energy of gas is diminished by packing particles more quickly,gas fluid is close to stillness more quickly,gas pressure is decreased more quickly.

Influence of surface potential barrier on escape probability of gradient-doping negative electron affinity (NEA) GaN photocathode was studied. Electron energy distribution and escape probability are calculated and compared with those of uniform-doping GaN photocathode. It shows that gradient-doping NEA GaN photocathode can obtain higher electron escape probability. And barrier I has an evident influence on escape probability while barrier Ⅱ has limited influence. Photocurrents of two GaN photocathodes are measured with a multi-information-test system. Experimental results show that gradient-doping GaN photocathode has higher escape probability. Obvious effect on escape probability can be found by barrier I from Cs-activation while barrier Ⅱ from Cs/O-joint-activation has little impact.

A Monte Carlo model is established to simulate transmission of 1.06 μm laser pulse in graphite smoke screen.Relation between transmittance and graphite particle size,smoke concentration,smoke thickness are analyzed.A convolution method is put forward to calculate waveform of pulse laser through smoke.For δ pulse laser and rectangular pulse laser with different width,time broadening is calculated.It shows that there is an optimal radius(0.16 μm) for graphite smoke particles,at which interference effect is the best for 1.06μm laser pulse.For rectangular pulse laser,the smaller pulse width is,the more remarkable change in pulse shape and temporal broadening are.For microseconds width laser pulse,pulse shape changes and temporal broadening are not obvious.

To improve resolution of a low-light image intensifier,simulation of electronic transport in a micro-channel plate(MCP) is made.Field distribution is obtained by calculating electron optics with numerical method.Distribution of photoelectron on fluorescent screen is determined by tracing electron trajectory in MCP.Influence of MCP tilt angle,channel diameter,voltage on electronic transport and resolution of image intensifier are studied.It shows that MCP has good electronic transport characteristics,image intensifier has good modulation transfer function(MTF) and high resolution at a title angle of 14°,channel diameter of 5.0 μm,a voltage of 900 V.

A transfer matrix method is discussed,and precision of the method is controlled.It is shown that the transfer matrix method and the intergral iterative method show same results for a general confocal resonator.Convergence problem of the intergral iterative method can be solved and laser resonators can be analyzed by the transfer matrix mothod with reasonable control of calculation precision.

An uncoupled method based on an implicit dual time-step approach for nonequilibrium flows is developed.Flow and reaction are separated by using operator-splitting method.Flow equations are solved by a dual time-step approach and source equations are solved by 2nd order trapezoidal formulas.A source-eliminating method is designed to remove error imposed to the solution by chemical source,which is very effective to assure time precision of flow-solving.Analysis and computations suggest that the method maintains efficiency of dual time-step approach as well as precision of unsteady computational results.

We carry out three-dimensional(3-D) modeling of frequency electromagnetic sounding in layered anisotropic earth using integral equation method. A integral equation formulation is derived based on modified Green's operator with norm less or equal to one. The integral equation is convergent for any conductivity distribution and frequency if iterative solvers are used. An optimal choice method on initial guess for iterative solvers is introduced. It improves computational efficiency of 3-D modeling of frequency electromagnetic sounding significantly. Apparent resistivity responses of 3-D axial frequency electromagnetic sounding are considered in multilayered anisotropic earth.

A model of one-dimensional photonic crystal laser with four-energy-level gain media is presented.The model consists of Maxwell-Bloch equations coupled with rate equations of electronic population in a photonic crystal laser system.The discretization of coupled equations is accomplished with finite different time domain(FDTD).Spectra,lasing mode,lasing threshold and dynamics of the photonic crystal laser are obtained.The simulation shows good agreement with theoretical predictions.

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.

A hypothesis on electrical field distribution is presented for the physical model of a scanning probe tip with a conical body ending in a spherical apex. Based on the hypothesis, we deduced an analytical model to calculate the electrostatic force acting on the tip and analyzed variation of the electrostatic force with structural parameters of the tip. The simulation results are consistent with those given by numerical methods of equivalent charge distribution (ECD) and by experiments. The hypothesis is proved reasonable according to the work.

With a variational method and a modified arrangmement channel quantum mechanics(MACQM) method, the energies of a equilateral triangle H₃ and a tetrahedron H₄ system are calculated. The result shows that as α=1.03 and R=1.74a₀, the H₃ system has a minimal energy of -1.58161 a.u.; as α=1.07 and R=1.60 a₀, the H₄ system has a minimal energy of -2.28097 a.u.. It shows that both structures could exist.

The transmitters of induction well logging tools can be simplified as a series of magnetic dipoles, whose fields formed in dipping boreholes can be decomposed as the sum of transversal electrical and transversal magnetic waves (TE and TM waves), and solved completely from the two scalar partial differential equations. A new process is first given to decompose the electromagnetic field into TE and TM waves through the tensor expression of Maxwell equations in the cylinder system, and then recurrence formula for amplitudes of the field in each bed and generalized reflection and transmission coefficients on each boundary are given. On the bases, the analytic solution of the field in each bed is obtained. Finally, using numerical results, the influence of dipping angles of boreholes, bed thickness and thinly laminated sand/shale on the response of the deep induction well logging tools is investigated.

With the mesoscale model being used as the dynamical frame, and coupled with the cloud model of explicit scheme, a numerical simulation is conducted on the macro parameters of cloud fields, water vapour of cloud and size-distribution of the spectrum of cloud particles, based on which the application of cloud model in aviation is also investigated.

The explicit finite difference method is used to the quenching of CrNi steel, the relationship between surface heat transfer coefficients and temperature is determinated by means of solving the inverse problem of heat conduct equation.

By using Linearization method in little time interval, from the heat conduition equation with the 1st-order phasetransformations, the foundation equations of Finite Elememts in solidifications of Metals is established in the paper. The numerical analog on symetric problem in solidification of a grayiron in sandform is obtained by means of triangular element, and the results tallies the corresponding test well.

In this paper, Norsette Method is used to solve the non-steady heat conduction problem. This method prevents the "oscillation" of numerical solution effectively.

We Propose here both first and second order explicit conservative difference schemes to solve1-D unsteady full Euler equations.As comPared with early schemes like MacCormack^[1] etc., these proposed schemes can prevent the occurence of nonphysical expansion shock and oscillation while the computing time is increased only a little bit.A series of numerical tests shows satisfactory qualities of these schemes.