Crystal structure, elasticity, electronic properties, phonon spectra and thermodynamic properties of PuCoGa₅ and PuRhGa₅ were studied with first-principles PBEsol+U method. PBEsol+U method is used to account for strong on-site Coulomb repulsion among localized Pu 5f electrons. Our results shown that the ground state properties, including lattice parameters and atomic sites, are agree well with experimental data. Mechanical properties and phonon dispersion indicated that the ground state structures (at zero temperature and pressure conditions) of PuCoGa₅ and PuRhGa₅ are stable. In particular, 5f electrons of PuCoGa₅ and PuRhGa₅ have obvious localization near Fermi level, and the localization of 5f electrons of PuRhGa₅ is obviously stronger than that of PuCoGa₅, which may be the reason that the superconducting critical transition temperature T_c of PuCoGa₅ is higher than that of PuRhGa₅. In addition, thermodynamic properties of PuCoGa₅ and PuRhGa₅ include Helmholtz free energy, entropy, internal energy and isovolume molar heat capacity have similar dependence on temperature.

With first-principle calculations, we investigate elastic and magneto-optical properties of Al₁₄Mn₂P₁₆ under hydrostatic pressures (0~20 GPa). Our calculations show that the ground state is a ferromagnetic state. The system was proved stable according to the elastic stability criterion. The magnetic moment decreases with increasing hydrostatic pressure. Below 5 GPa, the system hosts Curie temperature (T_C) of 184 K combine with a slightly decrease with increasing hydrostatic pressure. Furthermore, intriguingly, as external pressure furthers improves, T_C drops sharply, even vanishes at 18 GPa. It was found that the absorption peak in visible optical range has obvious blue shift. As hydrostatic pressure reaches 20 GPa, absorption peak in visible optical range disappears.

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.

With powerful nonlinear mapping and fitting ability of neural network, a production predicting neural network model is constructed. In view of high error, easy to default and other characteristics of oil field production data or data fitting and prediction is not easy to converge, a method of extended training data set and improved mean square error loss function are presented to get remarkable results in oil production fitting.

Temperature pattern in circulation phase of SAGD process is studied. Two in-situ points, three-dimensional heat conduct and partial penetration of horizontal well into reservoirs, are considered. The model is processed by dimensionless treatment, Laplace transformation, separation of variables and Stehfest numerical inversion. The results are in accordance with simulations by CMG software which verifies accuracy of the model. It shows relationship between temperature and heating time and concludes that the smaller the radial distance, the less the time is needed. Calculation plate can be helpful to design heating time and amount of heat.

Scaled boundary finite element method (SBFEM) is used to analysis and calculate electromagnetic field problems. SBFEM equation and discrete format of irrotational magnetic fields are derived with weighted residual method. Solving method of inside common node on public edge of adjacent sub-domain is shown. A typical example that has analytical solution of electromagnetic field is used for comparative analysis, which verifies discrete format correctness and feasibility of the method. Foundation for method applications in electromagnetic field calculation is made.

Considering side group structures of poly(organosilanes),unified basic formula are derived with method of configurational-conformational statistics in rotational-isomeric-state model.Characteristic ratios of mean-square radius of gyration for atactic poly(silastyrene)(PSS),polysilapropylene(PSP),poly(methylphenylsiloxane)(PMPS),poly(dimethylsilmethylene)(PDMSM) and poly(dimethylsilylene)(PDMS) chains are obtained.They are 1.45,0.63,0.97,0.69 and 1.99,and ratios of mean-square dipole moment are 2.49,0.99 0.61,0.48 and 0.27,respectively.It is found that effect of temperature,conformational energy,polymerization degree and tacticity of chains on ratios of PSS and PMPS is quite obvious.However,dependences of basic quantity of PSP and PDMSM on side groups,conformational energy and temperature are inappreciable.Dipolar large side groups in analysis flexibility and polarity of poly(organosilanes) is significant.

Rcaction mechanism between Mg(NH₂)₂ and LiH are investigated with a B3LYP method of density functional theory. Geometries and harmonic vibration frequencies of reactants,intermediates,transition states and products are calculated at B3LYP/6-311G(d,P) level.Vibration analysis and intrinsic reaction coordinates(IRC) calculation at the same level are applied to validate connection of stationarv points. It indicates that the reaction has three stages.They are the first step of hydrogen substitution,the second step of hydrogen substitution and isomerization after removal of hydrogen.There are two pathways, in which a channel of the second step of alignment hydrogen suhstitution reaction is the main channel.The two hydrogen atoms in H₂ released are from Mg(NH₂)₂ and Lilt.

In order to study statistical properties of surface fluctuation in a Wolf-Villain(WV) model。maximal-and minimal-heigIlt distributions(MAHD and MIHD) of saturated surfaces in a(1+1)-dimensional WV model are investigated with theory of extreme value statistics.It shows that both MAHD and MIHD csn be fitted well with universal functions of different system sizes.They are asymmetrical.MAHD takes on a generalized Fisher-Tippett-Gumbel(FTG) distribution,a typical extreme value distribution function.MIHD,however,displays a slightly different distribution,a modified FTG distribution.

Possible geometrical structures and relative stability of alkali metal nitride compound (K₃N)_n(n=1,…,5) clusters are studied with a hybrid density functional theory(B3LYP)with 6-311*-basis sets.Bond property,charge distribution,vibrational property and stabilities of the stablest isomers of (K₃N)_n(n=1,…,5)clusters are analyzed.It shows that the stablest isomers of (K₃N)_n(n=1,…,5) clusters are changing gradually from planar structure to three-dimensional structure.(K₃N)₄ and (K₃N)₅ are layered structure similar to crystal.Coordination rlnmhers of N atoms are usually 5 or 6.Natural charges of N atom and K atom are about-1.608e and+0.550e.respectively.A strong ionic bond exists between K atom and N atom.Dynamic stability of (K₃N)₄ cluster is higher than that of other clusters.

Roughness distributions of 1+1 dimensional noisy Kuramoto-Sivashinsky(KS) equation at steady states are obtained and compared with Kardar-Parisi-Zhang(KPZ) equation's with numerical simulation.It is shown that the scaling functions of roughness distributions of the noise KS equation in 1+1 dimensions show small finite-size effects.They are in good agreement with the Kardar-Parisi-Zhang(KPZ) equation's.

A complete analytical method for coefficient of charge on plane elements in SCM(surface charge method) is complicated under linear or high order charge density approximation.A kind of semi-analytical integration is proposed.It transforms the integral under local reference into a separable double integration under global reference.Since the inner layer integration is analytical,the original integration can be simplified to a one-dimensional problem which can be calculated by traditional numerical method.As for singular integral,eliminating singularity technique by adding auxiliary function is adopted.It indicates that high precision is achieved and the method is applicable.

Lattice Boltzmann method(LBM) and back and forth error compensation and correction(BFECC) skill are combined together for two-dimensional incompressible flows with quad-tree mesh.The scheme is equivalent to conventional LBM. Results for flows in two-dimensional cavity and around a cylinder demonstrate the scheme.

A muhi-component mathematical model characterizing polymer enhanced foam flooding filtration is established with mass conservation principle of foam components. Considering combination of foam generation, coalescence and migration phenomena, the model effectively reflects mechanism of oil phase foam coalescence and polymer foam stabilizing. Differential numerical solution is conducted with adaptive implicit method. Validity of the mathematical model is verified with experiment. Meanwhile, taken foam flooding pilot region of a oilfield, a numerical simulator is employed to study filtration characteristics of enhanced foam flooding. It is indicated that the foam system could exist stably in the formation and gradually advance to production wells to improve oil recovery.

Possible geometrical structures and relative stability of (MgB₂)_n(n=1~3) clusters are studied with a hybrid density functional theory(B3LYP) with 6-31G^* basis sets.For the stablest isomers of (MgB₂)_n(n=1~3) clusters,the electronic structure,vibrational property,bond,ionization potential,polarizability and hyperpolarizability are analyzed. Most of the optimized (MgB₂)_n(n=1~3) clusters are planar structures and the B-B and B-Mg bonds coexist,while the Mg-Mg bonds are infrequent.The bond lengths of B-B and Mg-B are 0.153~0.182 nm and 0.218~0.231 nm,respectively. Several negative B atoms form an electronegative center and other B and Mg atoms with positive charge are located at the apex of the cluster.The natural charges of Mg atom and B atom are +0.559e~+0.920e and -0.724e~+0.197e,respectively.

According to the characteristics of perfectly matched layers (PML), a convolutional PML (CPML) is chosen to truncate open boundaries used in the numerical simulation of low-altitude electromagnetic pulse. On the basis of the split-field PML and the plane-wave solution of electromagnetic field in a free space, an unsplit-field PML is constructed. With convolutional theorem in the Fourier transformation, discerete iterative equations of electromagnetic field components in the CPML media are presented in three-dimensional prolate-spheroidal coordinate system. The effectiveness of the method in numerical simulation of nuclear electromagnetic pulse is shown.

A 9-bits lattice gas model with temperature effect is applied into the simulation of thermoacoustic prime movers. The self-excited oscillation in a thermoacoustic resonant tube has been simulated. The distribution of two-dimensional temperature field and the evolution process of temperature are presented as well. The effects of the length of stack and of its position on acoustic pressure have also been investigated numerically. The simulation results are valuable to the optimum design of stack. The validity of the lattice gas model for a thermoacoustic engine has been verified by the comparison of the simulated and experimental results, which demonstrates that the lattice gas method is suitable for the thermoacoustic simulation.

An elastic coordinate variational method is given for calculating ground-state energy and wave function of two-electron atom. The program in terms of Matlab language has leen achieved. It provides numerical results of ground state energy of helium atom and helium-like ions.

Effects of SEU and SEB are simulated with 0.4μm diameter microbeam. SEU for drain region of MOSFET and CMOS SRAM are calculated. Collective charge depending on LET for specific device structure is calculated for different ions. LET and critical charge are provided. SEB for VDMOS is simulated and electric field, potential line, current, rate of impact ionization are given at different times along ion tracks. It is very important for heavy microbeam test physics models which have been set up.

The MEDICI software of two dimensional simulation of semiconductor device is briefly introduced.Its characteristics and use are described.With the help of MEDICI,effects of total dose for MOSFET and dose rate for pn junction are simulated.Their physical models are set up.A theory approach is provided for the research of ionization radiation effects.

The capability of hydrogen storage in zigzag single-walled carbon nanotubes is investigated.Relations of diameter and length with the hydrogen reserves and the distribution of hydrogen storage in single-walled carbon nanotubes are obtained.A new expression of hydrogen storage capability is presented.

By using explicit saturation and implicit concentration methods,numerical solution is presented to the polymer drive model characterizing dispersion and adsorption of polymer solution flowing through a porous medium.Saturation equation is solved by using an explicit total variation diminishing(TVD)method.To ensure the stability of concentration equation calculation,Crank-Nicolson difference format is used in spatial discretization,and variable is quasi-linear disposed in temporal discretization.The validity of the method presented is verified by comparison with analytic solutions.The calculated example indicates that dispersion causes dilution and dissipation of polymer solutions,and adsorption results in a loss,thus leading to lagging of concentration propagation.Also,the important polymer flooding mechanism- "oil block" is illustrated in the results of calculation.Under the condition of slug injection,the breakthrough time of oil enrichment zone lies between the breakthrough time of polymer concentration front and polymer concentration peak.

Finite difference method is used to simulate the physical process numerically during which the electromagnetic signal is generated by the interaction of nuclear-explosion-induced currents with the geomagnetic field. The EMP waveforms above burst point are researched. The earth-based coordinates and the local spherical coordinates are introduced to illustrate propagating properties of the nuclear electromagnetic pulse along the orbit direction of satellites with various explosion height and yield. Taking into account the attenuation and dispersion of the ionospheric plasma, the FFT method is used to extrapolate the strength of the DEMP. With cosmic noise considered, the peak electric field strength with the yield over 1 kt could be detected at a distance of 10⁴km.

The finite difference and PIC method are used to simulate the behavior of secondary electrons stimulated by primary X-ray photoelectrons. The results are given for the air pressure below 1 Pa and the plasma effects of low energy secondary electrons to the irradiated conductor are discussed as well.

It develops a two-dimensional,fully electromagnetic,relativistic FDTD computer code combined with the PIC method.The physical process of the vircator that electrons are emitted from cathode is simulated.The effects of applied voltage and reflected electrons from the vircator to the diode region are studied preliminarily.

A general approach based on evolutionary algorithms to inverse parameter identification problems of PDEs is introduced. The evolutionary algorithms is used for solving the inverse problem as an optimization problem. This approach can evolve the optimal coefficient estimation by genetic algorithms (GA) in the giving function space of unknown parameter from observation data objectively and automatically. The approach has also been applied to parameter identification problem of linear and quasi linear parabolic equations. The numerical results demonstrated the effectiveness of this method.

A 9_Bit square lattice gas model with temperature was introduced. We fulfilled an acoustic driver using Monte Carlo Method. Using this driver to generate plane waves, a standing sound wave was established in a two-dimensional pipe. This model can display the formation and change of the standing wave in real time and combined with its ability to simulate temperature variations, other phenomena, such as thermoacoustic, can be further analized on the microscopic level.

The System generated electromagnetic pulse (SGEMP) generated by X rays in various ranges of fluence have been numerically studied.Certain trends about the electric and magnetic field and their distribution as a function of fluence are abtained and discussed.

A new free surface scheme for 1-D and 2-D numerical calculation of elastic-plastic flow is proposed to study e-beam or X-ray radiation,high velocity impact and blast.Some numerical examples given here show that the pressent free surface scheme is more suitable than Richtmyer's for solving thermal-mechanical effects of material subjected to e-beam or X-ray pulse radiation.It is proved that this scheme should give a third-order accuracy.

According to the conductor's skin effect in low frequency electromagnetic field and the characteristic of comparatively small excitement coil in the benchmark model for eddy current testing, a perturbation model is proposed by combining the axisymmetric field and the 3-dimensional field, in which the disturbed field due to crack in the conductor allows being solved.