We study heat transport in magnetic island in Tokamak. As electron cyclotron resonance heating (ECRH) has good locality it is used to simulate ECRH plasmas for local Gaussian heat source in magnetic island. In the case of simultaneous existence of background heat source and local Gaussian heat source, variation of radial electron temperature distribution and heat transport in local Gaussian heat source are studied. Analysis is made on influence of local Gaussian heat source on temperature perturbation and magnetic island constraint energy.

With pseudo-potential plane-wave based on density functional theory (DFT), effects of zinc vacancies on ZnO lattice parameters and electronic structure of Al-P co-doped were studied. Formation energy, density of states are analysed. It shows that Al_Zn-P_Zn has the lowest formation energy and presents n-type in the process of co-doping. Presence of zinc vacancies make cell volume decrease, and lattice constant c increase and decreases as concentration of zinc vacancies increase. According to formation energy of co-doping, formation of zinc vacancies system is more stable than Al_Zn-P_O. System with Al and P ratio of 1:2 co-doping can reduce formation energy and become more stable. With comparisons of band structure of V_Zn and 2V_Zn, it is found that band gap increased with zinc vacancies increasing, which makes p-type ZnO more obvious and enhances conductivity of Al_Zn-2P_Zn co-doping systems. However, for Al_Zn-2P_Zn co-doping of 2V_Zn, it shows great superiority of p-type. According to state density analysis, Al_Zn-2P_Zn of 2V_Zn makes the state density more diffuse, and go through the Fermi level, which leads to formation of obvious p-type. As a result, better p-type ZnO can be obtained by controlling Al/P in proportion of 1:2 co-doing with zinc vacancy to 2V_Zn.

With margins and their uncertainties, QMU (Quantification of Margin and Uncertainty) method can be used to make decisions on whether performances of a product reach demands or not. Recur to new methods of UQ (Uncertainty Quantification) for M&S (Modeling & Simulation), QMU is actualized with input information directly from M&S and its uncertainties. With reliability assessment for a stockpiled product, main ideas and executing details of QMU decision are demonstrated.

Inverse mode problem of a horizontal bar structure, a single branch structure of a rod-beam-rod system, is investigated. Sign-oscillatory properties of inherent vibration stiffness matrix of discrete horizontal bar structure are shown mathematically. In addition, qualitative properties of frequencies and modes are introduced. Physical parameters of horizontal bar structure are constructed from two sets of displacement or strain modes and corresponding circular frequencies. Several numerical examples are given. A particular inverse mode problem is discussed, where structure parameters of horizontal bar are symmetrical for geometrical symmetry axis. It shows that formulation of inverse problems is reasonable and solution method is validated.

Three-dimensional Navier-Stokes equations in high temperature real gas model and perfect gas model are solved for hypersonic entry process. Good agreement is achieved between numerical results, reference values and flight data of Viking, which validates physical-chemical models and numerical methods. Aerodynamic prediction of Mars Pathfinder proves that results of real gas model are close to LAURA. Perfect gas model with effective specific heat ratio is capable of computing lift and drag coefficients. At 2° angle of attack, MPF exhibits static instability along trajectory, which perfect gas model failed to catch on. It is considered that main reasons of static instability are sonic line shifting around shoulder in windward, subsonic area varying and subsonic bubble occurring in leeward. They result in different pressure change in shock layer and in transportation process from expansion zone to upstream.

Test particle Monte Carlo (TPMC) method is presented. Return flux on four geometric surfaces due to ambient scatter of outgassing molecules is simulated. Return flux ratio (RFR) obtained for flow past a sphere is in good agreement with DSMC results. RFR on outgassing and freestream conditions for flows past three geometric bodies, including a circle flat plate, a convex and concave hemisphere, is investigated. RFR for flows past a circle flat plate and a concave hemisphere is much greater than that for flows past a convex hemisphere. Outgassing molecules collide on outgassing surfaces directly forming direct flux contamination for flows past concave surfaces, which is much greater than RFR. Thus, using convex outgassing surfaces in spacecraft design can decrease return flux contamination effectively.

Inverse mixed problems of a discrete system for a rod are studied, i.e., stiffness and mass matrices of discrete system of a rod are reconstructed from some frequency data and part of mode data. Three inverse mixed problems are formulated. Solving methods for these problems are given. And conditions of existing solutions for these inverse problems are discussed. Numerical examples are also shown. Potential worth for this type of inverse problems is analysed.

Three-dimensional Navier-Stokes equations in real gas models are solved with a parallel code to analyze aerodynamic characteristics of Mars Science Laboratory in hypersonic entry in Martian atmosphere. Good agreement between numerical results and flight data of Viking validates physical-chemical models and numerical methods. It shows that impacted by real gas effect,shock layer thickness is reduced; drag coefficient rises,lift coefficient is almost unchanged. Difference of trim angle between real gas and perfect gas is about 2.2°; As keeping altitude,greater Mach number results in greater drag and pitching moment coefficient. Difference of trim angle varies from 1.6° to 2.6°. Increasing Mach number enhances real gas effect. As keeping Mach number,increasing altitude weakens chemical reactions behind the shock,but it has weak influence on aerodynamic coefficient.

Conditions and method for constructing stiffness distribution function of various parameters symmetric simple supported beams with a symmetric or anti-symmetric mode and specified polynomial density distributing function are discussed. It is shown that the constructed stiffness distribution functions are positive functions in case with different density distributing. Two numeral examples are given. And two problems correlated are explained.

To enhance optimization ability of quantum potential well-based particle swarm optimization algorithm,a quantum particle swarm optimization algorithm based on Bloch spherical search is proposed by analyzing the design of quantum potential well-based particle swarm optimization algorithms.Firstly,particles are expressed with qubits,axis of rotation is established with Pauli matrix,the angle of rotation is obtained with a model of Delta potential well,and search is realized with rotation of qubits in Bloch sphere.Then,to avoid premature convergence,mutation of particles is achieved with Hadamard gates.Such rotation makes current qubit approximates target qubit along with the biggest circle on Bloch sphere,which accelerates optimization process.It shows that the proposed algorithm is superior to the original one in optimization ability.

Based on a microscope capillary model,a mathematical model for induced polarization of reservoir rock is obtained.Influences of concentration difference polarization and electric double-layer deformation on induced polarizability are studied numerically.It shows that induced polarization is governed by ion concentration difference polarization in capillary.Electric double-layer deformation has greater influence on total polarizability.Speed of charging and discharging in induced polarization depends mainly on cation exchange capacity and pore structure of rock.

With plane-wave pseudo-potential method of first-principles,effect of dopant Fe on dehydrogenation characteristics of LiAlH₄ and mechanism were studied.Dopant formation energy,electronic density of states and dissociation energy of H were investigated.Bonding state and structure-stability of the crystal were analyzed.It indicates that as Fe occupied an interstitial site,an Al site or an Li site,dehydrogenation properties of LiAlH₄ were improved.Fe tended to occupy the interstitial site.Analysis on electronic structure reveals that there exist strong interactions between a dopant Fe and its nearest neighbouring Al atoms as Fe occupied an interstitial site.Meanwhile,interaction between a dopant Fe and its nearest neighbouring H atoms is also considerably strong.Stability of the [AIH₄] ligand is distorted.Therefore,dehydrogenation properties of LiAlH₄ are improved.In general,dopant Fe improve dehydrogenation properties of LiAlH₄,which is consistent with experimental observations.

A one-dimensional fluid model for RF methane plasma is presented.Equations of particle balance with drift-diffusion approximation for fluxes,and electron energy balance are solved.Totally 20 species(neutrals,radicals,ions,and electrons) are included in the model,as well as 49 reactions(27 electron reactions,7 ion-neutral reactions,and 15 neutral-neutral reactions).It is found that high electron reaction-rate occurs at high electric-field region.Besides inlet gas CH₄,neutral gases H₂,C₂H₆,C₃H₈,C₂H₄,and C₂H₂ also show high densities in the plasma.The main radical in plasma is CH₃,with a density of about 10¹⁹m^-3.At low pressures(e.g.,18Pa) the most important ion is CH₅⁺.At high pressures(e.g.,67Pa) C₂H₅⁺ becomes the dominant ion.Radical and ion fluxes towards electrode(except C₂H₅⁺) increase slightly with power.

Electron energy distribution function(EEDF) in RF methane plasma is calculated with Boltzmann equation and Lorentz approximation. Instead of a self-consistent RF field satisfying Poisson's equation,a simple electric field distribution is used.6 neutrals are included,as well as 27 electron-neutral reactions.EEDF yields information about electron reaction rates in plasma,electron average energy,and transport coefficients.In the sheath region,EEDF is Maxwellian,and in the bulk region a Druyvesteyn EEDF is found.An electron average energy peak occurs in the sheath region,together with electron reaction rates.Differing from constant transport coefficients used in references,electron diffusion and mobility coefficients strongly depend on RF period and space.

Three-dimensional algorithms solving laminar Navier-Stokes equations coupled with chemical reaction and transportation equations are developed.Detailed flow field and distribution of yield,dissociation and pumping rates and small signal gain are obtained which cannot easily be got in experiments.The reason that experimental results are not as good as that in theories is analyzed.Furthermore,a better way to operate the system is suggested.It is shown that the mixing and chemical process in a nozzle of limited length is not complete due to the high speed in supersonic mixing zone and low mixing efficiency.Higher iodine concentration for speeding up chemical reaction causes insufficient of singlet oxygen,so as an unreasonable gain.A primary flow without buffer gas is claimed necessary and essential to reduce flow velocity and assure mixing process and chemical reaction accomplished before arriving the cavity.With an appropriate flow rate ratio,a small signal gain can reach 1.3% cm^-1.

Mode inverse problem for a beam with overhangs is discussed.Flexural rigidity and density of beam with overhangs are solved with two groups of displacement modes or two groups of strain modes and corresponding frequency.Necessary and sufficient conditions for unique existence of solution of the problem are discussed.An algorithm is proposed and numerical calculations are carried out.Two examples show that better results can be attained if strain modes instead of displacement mode are employed.

A integrated method solving fluid and solid simultaneously is used to deal with complicated flow and solid temperature field coupling problems.A simple but effective approach is proposed to overcome stiffness in two-equation turbulence models.Related theory is provided.With this method,efficiency in multigrids and LUSGS implicit temporal stepping method is increased remarkably.

A Cartesian mesh algorithm is developed for numerical solution of supersonic flows with arbitrarily complex and moving solid boundaries.The method defines and tracks fluid-solid interfaces with a level set function. Fluid-solid boundary condition is dealed with a ghost cell technique and is calculated separately in normal and tangential directions.The method proposed is simple,robust,and can work with high-order finite difference schemes.To validate the scheme,one-and two-dimensional numerical examples involving static or moving boundaries are included.

Three dimensional unsteady natural convective heat transfer in an inclined cubic enclosure with porous medium is studied numerically. The right side wall (X=1) of the enclosure is kept at a constant temperature of T_o, Temperature of the opposite vertical wall (X=0) varies by sine law with a mean value of T_o. Other walls are kept adiabatic. A Brinkman-extended Darcy model is used to describe flow through porous medium in the enclosure and the equations are solved with SIMPLE algorithm. Inclination angle α1 rotating around Y coordinate varies between 0å and 90°. Inclination angle α2 rotating around X coordinate varies between 0° and 45°. Dimensionless temperature oscillation frequency f ranges from 5° to 90π. Effects of inclination angles and temperature oscillation frequency on heat transfer are studied in detail. It shows that the maximal heat transfer is achieved at an inclined angles α1=46°, α2=45° and a temperature oscillating frequency f=45π.

Shock/turbulent boundary layer interaction(STBLI) in a M_∞=3.0 supersonic compression ramp flow are studied using a spatial large eddy simulation method. At upstream, flat plate transition and developed turbulent boundary layer are simulated in which Shock/turbulent boundary layer interaction shows at the ramp. Analysis on mechanism of turbulent boundary layer/shock interaction indicates that linear unstable disturbance leads transition rapidly. In the process of STBLI, average separation range of the ramp is smaller than that in the laminar flow. However, extent of the separation shows different characteristics in different span-wise positions due to high velocity strip and low velocity strip.

We study heat transfer and fluid flow in a complex enclosure fiLled with porous media, with SIMPLEC (Semi-Implicit Method for Pressure Linked Equations Consistent) algorithm in curvilinear coordinates. The upper and lower walls of the enclosure are horizontal and adiabatic. The vertical wall forms cosine curve and is kept at a constant temperature. Governing equations are discretized with a finite-volume method on body-fitted coLlocated grids. Brinkman-extended-Darey model and local thermal non-equilibrium model are used to solve momentum and energy equations. Effects of parameters, such as Rayleigh numbers, Darey numbers and porosity, on heat transfer and fluid flow are studied. It is shown that Rayleigh numbers and Darey numbers have significant effect while porosity is negligible. There exists an optimal aspect ratio to make the heat transfer rate maximum.

Unsteady natural convection heat transfer of incompressible fluid in an inclined cavity filled with saturated porous medium is studied numerically.The temperature of the cold sidewall maintains constant and the temperature of the opposite sidewall varies sinusoidally with time.The Brinkman-extended Darcy model and SIMPLER algorithm are adopted.Comprehensive numerical solutions are acquired at a fixed Prandtl number Pr=1 and a Rayleigh number Ra=10⁶.The inclination angle of the enclosure α varies from 0° to 90°.The effects of α and dimensionless oscillation frequency f on the natural convection are analyzed.The maximum heat transfer is reached at f=60π and α=43°.

Periodically fully developed convective heat transfer characteristics in a two-dimensional wavy channel are investigated numerically with a constant wall temperature.The calculations are performed with Pr=0.7,Re=20~500 on non-orthogonal non-staggered grids generated by an elliptic equation system.A semi-implicit method for pressure linked equations revised (SIMPLER) algorithm in curvilinear body-fitted coordinates is employed.Effects of Reynolds number and geometric parameters,such as aspect ratio φ and shape ratio γ,on heat transfer and friction factor are studied.It shows that no recirculation region occurs through the whole channel at low Reynolds numbers,small aspect ratio or small shape ratio.With the increase of Reynolds number,aspect ratio or shape ratio,heat transfer is enhanced due to flow recirculation.Corresponding friction factor increases simultaneously.

A fully developed convective heat transfer inside a two-dimensional periodically wavy channel is investigated numerically with pulsating flows under a constant wall temperature. It is based on the SIMPLER(Semi-Implicit Method for Pressure Linked Equations Revised) algorithm in curvilinear body-fitted coordinates.Calculations are performed with Pr=0.7,Re=5~500 on a non-orthogonal non-staggered grid generated by elliptic equations. The effects of pulsatile parameters,such as pulsatile amplitude and frequency on heat transfer and flow friction,are studied.It shows that the vortice sweeping,diminishing and growing up due to pulsating flows enhance fluid pulsating and mixing,and lead to the enhancement of heat transfer.The intensity of heat transfer increases with the increase of Reynolds numbers and amplitudes and is independent of pulsating frequencies.The instantaneous flow resistance and Nusselts numbers present periodical cosine and sine variations, respectively.

A model of the beam centroid motion in a linear induction accelerator(LIA) was developed. It calculates the track of the beam centroid under the condition of cell magnet misalignment. The 3D magnetic field distribution is calculated with a coordinate transform. The track of the beam centroid is given by a coupled solution of the beam centroid and envelope equations. Quantitative relation between the transverse displacement of beam centroid and the misalignment of magnets is useful in the installation of magnets and the adjustment of steering coils.

The periodically fully developed laminar heat transfer and fluid flow in a two-dimensional wavy channel in a compact heat exchanger are investigated numerically. Calculations are performed at Pr=0.7, in the range of Re=100~1100 with non-orthogonal non-staggered grids. The Semi-Implicit Method for Pressure Linked Equations Revised (SIMPLER) algorithm in the curvilinear body-fitted coordinates is used. The effect of the wavy height and distance on momentum and heat transfer is studied. Performance of model parameters is evaluated. It is shown that the overall Nusseh numbers and friction factors increase with the increase of Reynolds numbers. The friction factors and overall Nusseh numbers increase as increasing the wavy height or decreasing the wavy distance. The overall Nusseh numbers increase significantly with the wavy height, especially at high Reynolds numbers. The best wavy height and distance are 1.15 mm and 13 mm, respectively.

The mesoscopic transport through a quantum dot and a toroidal carbon nanotube (TCN) coupled system is investigated with the nonequilibrium Green's function technique.The coherent tunneling is strongly related to the energy structures of the TCN and the quantum dot.The Aharonov-Bohm effect causes energy levels of the TCN to change periodically,and the tunneling current oscillates with the magnetic flux.The detailed nanostructure of TCN exhibits metal-semiconductor transition,and this behavior is reflected in the output current.The matching-mismatching of quantum levels of the sub-systems plays important role in the mesoscopic transport.

A reduced chemical kinetics model for typical combustion reaction systems is derived by means of the Computational Singular Perturbation (CSP) method.The combustion reaction governing equations are employed to construct ideal basis vectors,with them the coupling between the fast mode and the slow mode is decoupled properly.Several significant parameters are defined,such as the participation index,the radical pointer,and the importance index.Then the state equations of the fast modes and the reduced chemical kinetics model are obtained.A typical mixed combustion reaction system of CO-CH₄-Air is calculated,and the results show that the reduced combustion reaction system obtained by CSP method approximates the original system well.

A calculation model of accelerator beam envelope has been developed. It can predict beam envelope in linear induction accelerator from the injector to the final focus region. Its code can easily calculate the effect of various electric and magnetic element parameters on the beam. As calculating examples, the envelopes of 3 kA-beam current under the condition of 40 m long magnetic profiles are given.

An expert system is developed for the automatic determination of zoom lens layout. Its features include the calculation of Gaussian parameters for different zoom mechanisms, and the selection and optimization of each lens group in a zoom system.