We analyze k-α iteration method for α eigenvalue problems, and point out that parameter in k-α iteration method affects error estimation of alpha eigenvalues, while error estimation has no relationship with the parameter. If the parameter isn't given properly, the estimated error deviates the real error estimation. Estimated error given by MCNP4C may deviates from real error estimation due to improper parameter. A parameter selecting method called average neutron fission lifetime method is proposed to make estimated error and real error estimation equal strictly in mathematics. It was tested with numerical experiments.

Reduced-order model of proper orthogonal decomposition method (POD) was established to analyzed performance of fluid flow and heat transfer in flat tube bank fin heat exchanger. Numerical results of POD were compared with those of FVM. It indicates that average relative error between POD results and FVM results is no more than 5.7% while computational speed is improved 164.78-2021 times. Conclusion is of theoretical meaning for optimizing heat exchanger structure and running mode in engineering.

For problems that can be described by parameterized partial differential equations, reduced basis finite element constructs basis functions on top of typical high-fidelity solutions and thus greatly reduces number of unknowns. Principles of the method is introduced and favorable features are demonstrated through heat conduction problem and neutron diffusion problem. It shows speedup of three orders of magnitude during online stage.

In order to identify key nodes in network effectively, a comprehensive index of node importance recognition which considers local and global characteristics of network is proposed. Nodes in weighted standard test system IEEE39 and IEEE118 are sorted according to importance based on this index. Ranking results are compared with those based on betweenness centrality method and point weight method. Meanwhile these important methods of node recognition are compared using structure-based network efficiency analysis and dynamics-based loss-of-synchronization diffusion time and synchronization capability. It shows that ranking of node importance based on comprehensive index is more reasonable, which is superior to node recognition method based on betweenness centrality and point weight.

Dissipative particle dynamics (DPD) is modified by introducing attractive force. Attractive interaction of liquid and solid and micro-scale flow in nano throats is simulated to discuss mechanism of boundary layer. It is found that thermal motion affects velocity significantly in molecular scale while pressure gradient is leading function as greater than molecular scale. However, thermal motion cannot change integral moving direction. As throat radius becomes larger, parabola shape of velocity distribution becomes more and more obvious. Boundary layer thickness is affected by pressure gradient, throat radius and fluid viscosity. As pressure gradient increases and fluid viscosity decreases, boundary layer thickness decreases. As throat radius decreases, boundary layer thickness increases first and then decreases. Boundary layer is essential reason of nonlinear flow behavior and thickness of boundary layer increasing makes nonlinear flow behavior more obvious.

Band structures,density of states and optical properties of pure,N-doped,S-doped and N-S co-doped rutile TiO₂ are studied with plane-wave ultrasoft pseudopotential method based on first-principles density functional theory.It shows that the gap of N-doped TiO₂ reduces to 1.43 eV,and there is an impurity band on top of the valence band.S-doped TiO₂ results in Fermi level moves to the conduction band,and the gap decreases to 0.32 eV.N-S co-doped TiO₂ results in two impurity bands located in the band gap.One impurity band is apart from the bottom of conduction band by 0.35 eV,the other is apart from the top of valence band by 0.85 eV,which is mainly formed by N-atom 2p orbital and S-atom 3p orbital.It causes a red-shift in absorption wavelength,and gives rise to extremely great absorption coefficient in visible-light region,which shows a strong photocatalytic activity.

With influences of interconnect inductance,thermal-electric coupling effects and interconnect temperature distribution,a delay optimized method by repeater insertion is presented.A interconnect resistance model and a delay model are obtained respectively based on interconnect temperature distribution.The repeater insertion optimal delay is calculated considering electro-thermal coupling among power,delay and temperature.Optimized results are successfully obtained with Matlab software.Repeater insertion in 45 nm technology is simulated.It shows effectiveness of the method.In addition,it indicates that the optimal delay is overestimated without inductance effect.Optimal delay is underestimated without consideration of temperature distribution.As overestimated global interconnect width is 245nm,8.71% optimal delay can be underestimated without considering temperature distribution effect.

A numerical method applicable to unstructured mesh is proposed to compute 3D hypersonic ionized and radiating flowfields in thermo-chemical nonequilibrium. The flowfield is described with multi-specy N-S equations. The chemical model includes 11 species(O₂, N₂, O,N, NO, NO⁺, N⁺, O+, N₂⁺, O₂⁺, e^-) and 20 reactions. For thermal nonequilibrium effect, a two temperature model is considered. Radiation transfer equation (RTE) is solved with finite volume method. Numerical result on MUSES-C is shown and compared with referenced data. Influence of radiation on flowfield is discussed.

Mass and heat transfer between fluid molecules and a carbon tube is studied via molecular dynamic simulation with Lennard-Jones potential and Bernner-Tersoff potential. A valve hole of area 17.3~116.9Å2 is formed by removing different numbers of molecules from the flank of a (5,5) armchair carbon tube. The results indicate that diffusion behavior can not describe the phenomena completely, since the hydrogen atoms penetration rate Vb can also be affected by hole size at the same temperature. The Maxwell-Bohzmann energy distribution equation is modified. Atom release rate and valve hole size are interdependent. Variation of potential energy barrier, work function and energy gap at different valve sizes and influences on the dynamic behavior, such as flow rate and velocity by molecule penetration, are studied. The characteristic is used for design of nano-valve, particle separator or chemical reactor.

A uniform method for unsteady flows at arbitrary Mach number is developed.The preconditioned dual-time compressible Navier-Stokes equations for unsteady flows are obtained by incorporating a pseudo-time derivative term and preconditioning.The inviscid flux vectors and the viscous flux vectors are differentiated by a Roe-scheme of three-order and a general central difference scheme,respectively.A pseudo-time subiteration with an implicit ADI-LU scheme is implemented based on state-vector flux linearization.A two-order precision for physical-time step is achieved.Taking low speed flows as examples,the flow over a circular cylinder and the dynamic stall of the NACA0015 airfoil with identical pitching rate are simulated.Computed results agree with published results.It shows that the method simulates unsteady flows at arbitrary Mach number well.

A spectral method with FFT transformation is introduced in the numerical solution of the Fokker-Planck-Landau equation in describing charged particle transport in plasma.The time evolution of the distribution function in the velocity-space is studied with a "space-homogeneous" condition.Numerical results show that conservations of mass,momentum and energy are held precisely.In addition,the computation cost is reduced considerably due to the adoption of FFT transformation.

A general Monte Carlo program has been developed to study the performance of the X-ray intensifying screens and imaging systems.The program contains three major parts, each of which describes one of the interaction steps occuring in the system:the absorption and scattering of X-rays, the diffusion of generated electrons, and the diffusion of light photons.Through comprehensive verification, it shows that the simulation methods for all physical processes are correct and the results obtained are credible.For a kind of Gd₂O₂S:Tb intensifying screen, several characteristic parameters such as the number of collected light photons, light collection efficiency and PSF depending on the incident X-ray energy are calculated.These basic physical quantities are useful for the prediction of the information transfer properties of a phosphor layer.

A new model is established to perform simulation for Single-Event Gate-Rupture of power MOSFETs in use of PSPICE circuit simulation software. The application results have a very good agreement with the corresponding data in published articles.

Calculated shock-wave compressed properties of metal platinum is presented based on i)the accurate calculations of 0-K total energies with the self-consistent,relativistic,full-potential,and spin-polarized,linearized augmented plane wave method within the local density approximation to exchenge-correlational functional;and ii)the classical mean-field statistics.The calculations of 0-K total energies span a wide fcc lattice constant range of from 6.1 a.u. to 9.9 a.u.Our approach does not invoke any empirical parameters.The experimental Hugoniot is reproduced excellently.

It develops an approach to calculating electron structure of atom cluster which has some symmetry by using the multigrid method,symmetry theory and famous Kohn-Sham equation in density-function theory and calculates the ground energy of H₂ molecule.The calculated result shows that the energy coincides well with result of other theory.

Energy cost that bounce shock wave on its propagation through outer iron core must pay for dissociation of heavy nuclei is considered as an adjusted parameter. Based on this, the method of artificial prompt explosion model is proposed to research effects of iron core mass of SN Ⅱ on prompt explosion. Range of iron core mass of presuperonva models which can produce prompt explosion is estimatd. The preliminary investsgation shows that iron core mass of presupermova models of WW(1993) is too large to produce prompt explosion.

Gauss numerical integration is applied to compute the radial emission coefficients in Optically-Thick,Cylindrically-Symmetric Plasmas.Using the integration,the generalized Abel equation is separated into a system of linear algebraic equations and the coefficient matrix of the system is an upper triangular matrix,so the interpolation,which has second order of accuracy,is very simple to compute and less computation time is required.

The dynamic response of aluminium alloy and carbon phenolic composite plate impacted by an iron bullet has been studied by finite element method. Both the results of theoretical calculation and graphical analysis are given.

Some improving works have been done on the SCF-Xα-SW and LMTO Programs by vectorization and parallelization.The energy level of C₆₀ is researched.The 108 one electrom Rydberg excitation energies of benzene,such as 1e_1g,2e_2g,1a_2u→ka_1g(k=3-11),ke_2g(k=2-7),ke_1u(k=3-8),ke_1g(k=2-5),ke_2g(k=3-5),ke_2u(k=2-3),kb_2u(k=2-3),kb_1u(k=2-3),1b_1g,1b_2g are calculated.The electronic structure and bulk modulus of some U-Ni alloys are also analyzed.

Based on a static non-overlapped domain decomposition method,the problem is studied about the parallel implementation of a Harten-Yee implicit TVD difference algorithm on a MIMD multi-computers parallel system.The convergence and stability of the parallel processing techniques used here are manifested well through numerical simulation of the steady "super-supersonic" jet flow fields,and the parallel parameters obtained are promising.

In terms of the three basic forms and the eight-various cases of artifical viscosity for the same progenitor madel-"WW88", the numerical simulation has been performed for the whole processes of collapse and explosion of supernovae, and the artifical viscosity influences on compulation of supernovae explosion are investigated through analysis of numerical experimental results.

The inner-sphere reorganization energies (REs) of diatondc molecules in gaseous phase electron transfer (ET)process have been calculated in terms of Morse function scale model presented in this paper, the struCtural reorganization index (activated radius of the reduCed molecule) is given, the parameters involved can be determined via ah initio calculations at HFSCF levels (6-31G, 6-31G^*, DZ and DZP (d)), The inner-sphere RE values are calibrated by comparing molecular structural parameters (bond dissociation energies, force constants) with experimental data. Results indicate that ah initio calculation values are better agreement with experimental ones, and are found to be accurate to within + l.5kcal/mol or better. This method not only improves classical model but also gets around the difficulties in obtaining available experimental data and constitutes an accurate ah initio method in calculating inner-sphere REs of diatondc molecules in gaseous ET process.

Three-dimension, compressible, internal flow solution obtained using a modifiedBeam-Warming implicit factorization scheme is presented. Steady-state solution is obtained by solving numerically the full Navier-Stokes equations from given initial conditions until the time-dependent terms become negligible. The configuration considered is a rectangular cross-section, S-shaped centreline diffuser duct with an exit/inlet area ratio of 2.25. TheMach number at the duct entrance is 0.9 with a Raynolds number of 5.82×10⁵. Two regions of separated flow exist within the diffuser. The detail flow field especially the developement process of secondary velocity patterns in transverse plane are pressented. Comparing with the results ofRef.[1]. they have a good agreement. The secondary velocity patterns are more reasonable.

Some aerodynamic characteristics of an oscillating trail-edge flap were investigated by numerical simulation, such as the unsteady effect of flow field and flow field comparison between different frequences or amplitudes. The Euler equations were solved by LU-ADI algorithm, the grid is C type grid. The numerical results showed that: (1) with the oscillation of trail-edge flap, the shock strength and its location are nonlinear to the motion of the trail-edge flap, (2) the higher the reduced frequence, the less the influence to variable pressure jump, (3) with the increase of the amplitude, the variations of shock strength and its location become more seriously.

The objective of this study is to develop a mathematical model for calculating the initiation and spresd of fire resulting from an attack on an urban area, and to apply the model for predicting the fire-depentdent fire damage to an assumed city. The numerical test is obtained valuable information by using the parameters of fire spread from Japanese Hiroshima.The model to be developed is included——to determine description for a simplified urban,to take account of fire spread by radiation and firebrands in terms of statistical data, and to develop a computer program to perform the numerical simulation.

As development of equation of state supernova core collapse will reach high density above nuclear density, the general relativitic effects are most important. The density of core collapse is higher in the general relativitic (GR) core than in the Newtonian (NR) case. The higher the density reached the deeper the shock wave digs into the gravitational well and hance the shock wave will be launched with a larger energy. The formation mass point for shock wave is further from core boundary in GR case than in NR case. The disintegration of iron on the way of shock wave to propagate out will be increased. Once the core centre density reaches it maximum, the imner parts of the cross mass point for two velocity distribution in GR case and in NR case (which slight greater than the sonic mass point in NR case). The velocity value in GR case is greater than one in NR case, but the outer parts of the velocity cross point the velocity value is smaller in GR case than one in NR case, when the shock wave reaches the outer parts where the density and velocity is lower in GR case than in NR, which makes it easier for the shock wave to propagate.

In this paper, we are concerned only with computer simulation of the fires of buildings ignited on urban areas produced by a nuclear burst. The numerical test is obtained sorne qualitative results for the simplest model by using the parameters of fire-spread from Japanese Hiroshima.

In this paper, LU-ADI scheme and Baldwin-Lomax turbulent model were applied to simulate turbulent transonic flow around twodimensional airfoils. By a series of numerical experiments, it is proven that the method used in this paper is successful and the numerical results are satisfactory.

There is a restriction to the solution of the epuation of θ (the ratio between the density of the nuclear matter and the density of the nuclear matter at saturation) in the J. Cooperstein's equ ation of state. Starting from the expression of nucleons pressure near the saturation density at zero temperature, a expression of nucleon internal energy is obtained by us. the re striction mentioned above in J. Cooperstein's equation of state has been removed by substituting the expression of nucleon internal energy obtained by us for the expression used by J.Cooperstein. Me present results of hydrodynamic cal culation of core collapse and subsequent shock wave formation and propagation using the equation of state of us and using the 15M_⊙ initial model of WZW.The relesse of gravitational binding energy of core can be increased by proper softening the equation of state above the sqturation density of nucl ear matter.

The analysis contrasting the feature of BBAL's equation of state (eos) with the feature of equation of state EOS(1) is presental. At range of low density of matter(ρ<10¹¹g cm^-3), the chemical potential of neutron and proton of BBAL's(eos) differs notablly from EOS(1).This results in that two equations of state mentioned above differ greatly in abundance of free neutron and free proton at low density.The difference between the balance expression for finite temperature correct (thermal effect) and for "zero temperature appoximation" has been investegated.The effect for finite temperature correct on the chemical potential of neutron and proton is small, but the effect on the mass number and charge number of the average heavy nucleus is marked.Having taken 15M_① model of weaver et al.as initial model,the collapse process of stellar core between the onset of collapse and core bounce has been calculated by using both the (eos) of BBAL and EOS(1).The results show that the difference betwean the calculational results of stellar collapse (at ρ_c~10¹⁴g cm^-3) with EOS (1) and with BBAL's (eos)is not so large, in spite of that BBAL's (eos) differ greatly from EOS(l) in abundance of free nucleon at low density. The difference between calculational result (at ρ_c~10¹⁴g cm^-3) of stellar collapse resulting from finite temperature correct and "zero temperature approximation" for both BBAL's (eos) and EOS(l) is more notable.