流体的塔阱状态方程及其对迁移性质的推算

流体的塔阱状态方程及其对迁移性质的推算曾向东，严家（哈尔滨工业大学能源科学与工程学院哈尔滨１５０００６）牛文科，韩立中（哈尔滨船舶锅炉涡轮机研究所哈尔滨）关键词势能模型，配分函数，状态方程，平衡性质，迁移性质１流体的塔阱状态方程Ｐｒｉｇｏｇｉｎｅ认为...     

渐进非对称陀螺分子16O3及同位素16O18O16O的配分函数研究

采用乘积近似法计算了臭氧分子16O3及其同位素16O18O16O在20-6000 K温度范围内的总配分函数。其中转动配分函数用Watson的刚性转子模型,振动配分函数用谐振子模型．总的温度范围被划分为五个温度段。计算的配分函数在这五个温度段分别被拟合到一个温度T的五阶多项式,从而在每个温度段均得到六个拟合系数。由这些拟合系数就可以快速、准确的获得分子在所研究温度范围内任意温度的总配分函数。研究结果为目标特性识别、气动物理的高超声速技术等领域的研究提供了重要的参考信息。     

地层油气的相平衡热力学研究

地层油气的相平衡热力学研究王利生（北京理工大学化工学院北京１０００８１）关键词混合规则，状态方程，油藏流体，相平衡１链状分子的普遍化范德华配分函数链状分子的转动和振动运动会受阻于其它分子的运动，因而其配分函数中的转动和振动贡献与温度、密度均有关，被分...     

20～6000 K温度范围内二氧化碳配分函数的计算

在20～6000 K温度范围内,通过乘积近似计算了二氧化碳及其同位素的总的配分函数.其中振动配分函数用谐振子近似,转动配分函数考虑了离心扭曲修正.20～6000 K温度范围被划分为五个小区间.在每一个小区间,计算的总的配分函数被拟合到一个温度T的四阶或五阶多项式,从而获得五个或六个拟合系数.通过这些拟合系数可以快速准确的获得分子在所研究温度范围内任意温度下的总配分函数.     

基于Lattice-Boltzmann方法的纳米流体流动与传热分析

纳米流体是由流体与纳米粒子组成的悬浮体。由于悬浮的纳米粒子会受到各种内力或外力的影响,这使得其运动规律和换热规律及其复杂。本文运用Lattice-Boltzmann(LB)方法建立纳米流体的传热模型,并对纳米流体和水的流动换热参数进行比较分析。     

烟道气体SO2同位素分子配分函数模拟计算

利用Gaussian03程序包,在B3P86/cc-PV5Z水平上对烟道气体SO₂同位素分子进行优化计算,得到平衡几何结构、谐振频率和转动常数等物理性质参数;采用乘积近似法构建两种分子的配分函数模型,其中,转动配分函数采用WATSON的刚性转子模型,振动配分函数采用谐振子近似.模拟计算两种分子70~6 000 K温度范围内的总配分函数,并将70~3 000 K的数据与数据库比较,发现两者符合的较好,且随着温度升高,相对偏差逐渐增大,但差值都小于4%;相对偏差与温度可以近似看成-条直线,通过对相对偏差进行线性拟合,进而修正高温区(3 000~6 000 K)的计算,用-个温度T的多项表达式对高温区修正了的配分函数进行拟合,获得五个拟合系数,可以快速地获得高温区任意温度的配分函数,从而给出在高温下较为准确的分子配分函数.     

高温条件下一氧化氮红外辐射物性参数的计算

一氧化氮(NO)对高超声速飞行器本体和流场红外辐射传输有重要影响,而目前HITEMP数据库只能计算70K~3000K温度范围内的谱线参数,同时现有的高温条件下NO配分函数算法一般运算量大、且较少考虑电子基态双重分裂的影响,因此获取更为高效精准的NO辐射参数非常重要。根据乘积近似模型将NO配分函数分解成电子、振动、转动等配分函数,且在计算电子配分函数时考虑了NO电子基态中2个自旋分量的作用,以提高算法的准确性;对于3000K~8000K温度范围内,对振转配分函数乘积进行修正。实验结果表明,在70K~3000K温度范围内,本配分函数与HITEMP数据库的配分函数几乎完全相同,最大误差不超过0.3%,但该算法还可用于计算非平衡态下配分函数;在3000K~8000K温度范围内,该方法取得了与现有的基于求和运算的配分函数计算方法以及实验相近的结果。     

自由基SiH_2分子配分函数的计算

利用Gaussian03程序包,在B3P86/cc-PV5Z水平上对自由基SiH_2分子基态X~1A_1几何结构进行优化计算,得到其平衡几何结构、谐振频率和转动常数等性质参数;采用乘积近似法计算了自由基SiH_2分子基态X~1A_1从低温20 K到高温6000 K温度范围内的总配分函数.其中,转动配分函数采用WATSON的刚性转子模型,振动配分函数采用谐振子近似.然后我们把20～6000 K的温度范围划分为五个区间段,计算的总配分函数在这五个温度区间分别被拟合到一个温度T的四阶多项式,从而在每个区间均得到五个拟合系数.由这些拟合系数就可以快速、准确的获得该分子在所研究温度范围内任意温度的总的配分函数.     

二氧化硅分子配分函数的研究

在低温20K到高温6000K温度范围内,计算了¹⁶O²⁸Si¹⁶O分子稳定结构的的总配分函数.其中,转动配分函数考虑了离心扭曲修正,振动配分函数采用谐振子近似.把20—6000K的温度范围划分为五区间段,计算的总配分函数在这五个温度区间分别被拟合到一个温度T的四阶多项式,从而在每个区间均得到五个拟合系数.由这些拟合系数就可以快速、准确地获得分子在所研究温度范围内任意温度的总的配分函数. 关键词： 总配分函数 二氧化硅分子 转动配分函数 振动配分函数     

三维Ising模型的封闭近似解(Ⅲ)——用高阶超复数改进数值结果的可能性

在分析Ising模型二维严格解和三维Q近似的基础上,讨论统计配分函数解析表达式应当具备的各种性质。在此基础上探讨引用高阶超复数从数值上改进Q近似所得结果的可能性,为构造高低温之间的配分函数的内插公式作好准备。 关键词：     

概率假设密度滤波的物理空间意义

为了深入理解概率假设密度滤波,本文在Ozgur Erdinc对随机集的物理空间假设的基础上,采用Bayes公式和全概率公式对概率假设密度滤波的迭代过程进行了推导.为有效改善概率假设密度滤波的目标漏检问题提供了理论基础.     

带势估计的概率假设密度滤波的物理空间意义

为了便于人们深入理解带势估计的概率假设密度滤波,本文在Ozgur Erdin对随机集做的物理空间假设的基础上,采用Bayes公式和全概率公式对带势估计的概率假设密度滤波的迭代过程进行了推导.推导过程详细明了,推导结果与文献一致.这为带势估计的概率假设密度滤波在目标跟踪中的应用及性能改进提供了理论基础.     

Regulation Mechanisms in Spatial Stochastic Development Models

The aim of this paper is to analyze different regulation mechanisms in spatial continuous stochastic development models. We describe the density behavior for models with global mortality and local establishment rates. We prove that the local self-regulation via a competition mechanism (density dependent mortality) may suppress a unbounded growth of the averaged density if the competition kernel is superstable.     

Systematic treatment of the anderson localization on the basis of the projection operator formalism

A derivation within the projection operator technique is given for the density and current response functions of a system of independent particles moving in a random potential. The essential point is the derivation of kinetic equations for the current relaxation kernel instead of for the density propagator as in a previous treatment on the basis of the projection operator formalism. In these equations the divergent contributions from the 2k _F -scattering mechanism can be systematically separated from those of diffusional scattering. Especially, both the self-consistent current relaxation theory, developed by Götze and the self-consistent treatment of Vollhardt and Wölfle are rederived from simple approximations of the kinetic equations. The outlined method represents a systematic approach to the Anderson localization. It may be applicable also to more realistic models for the Anderson localization as well as extended to the evaluation of general transport coefficients on a level far beyond the usual perturbation theories.     

Optimized local basis set for Kohn–Sham density functional theory

We develop a technique for generating a set of optimized local basis functions to solve models in the Kohn–Sham density functional theory for both insulating and metallic systems. The optimized local basis functions are obtained by solving a minimization problem in an admissible set determined by a large number of primitive basis functions. Using the optimized local basis set, the electron energy and the atomic force can be calculated accurately with a small number of basis functions. The Pulay force is systematically controlled and is not required to be calculated, which makes the optimized local basis set an ideal tool for ab initio molecular dynamics and structure optimization. We also propose a preconditioned Newton–GMRES method to obtain the optimized local basis functions in practice. The optimized local basis set is able to achieve high accuracy with a small number of basis functions per atom when applied to a one dimensional model problem.     

Nonlocal pseudopotentials and magnetic fields

We show how to describe the coupling of electrons to nonuniform magnetic fields in the framework of the widely used norm-conserving pseudopotential approximation for electronic structure calculations. Our derivation applies to magnetic fields that are smooth on the scale of the core region. The method is validated by application to the calculation of the magnetic susceptibility of molecules within density functional theory (DFT) in the local density approximation. Our results are compared with high-quality all-electron DFT results obtained using Gaussian basis sets and another recently proposed pseudopotential formalism.     

Local deterministic model of singlet state correlations based on relaxing measurement independence

The derivation of Bell inequalities requires an assumption of measurement independence, related to the amount of free will experimenters have in choosing measurement settings. Violation of these inequalities by singlet state correlations brings this assumption into question. A simple measure of the degree of measurement independence is defined for correlation models, and it is shown that all spin correlations of a singlet state can be modeled via giving up just 14% of measurement independence. The underlying model is deterministic and no signaling. It may thus be favorably compared with other underlying models of the singlet state, which require maximum indeterminism or maximum signaling. A local deterministic model is also given that achieves the maximum possible violation of the well-known Bell-Clauser-Horne-Shimony-Holt inequality, at a cost of only 1/3 of measurement independence.     

Magnetoresistance relaxation and flux creep in high-Tc superconductors

The appearance of hysteretic voltages on ceramic high temperature superconductors during the measurement of the mixed state resistance is now well known., While these voltages can be attributed to a field dependence of the critical current density, the primary phonomenon is the V—H—i characteristic which is representative of a magnetic field induced, dissipative process in the granular material.

Two mechanisms may be responsible for these effects; one is the well known flux-flow or flux-creep phenomenon where the electrical energy is used in changing the vortex system while the other is a more conventional thermal loss as the intergranular contacts are driven normal by the applied field.

The observation of a corresponding time dependent residual voltage which is associated with flux trapped in the superconductor is examined in terms of the two models, both of which are found to predict the observed time decay and also justify the derivation of the flux-trapping energies from the decay law. The differences between the models appear in the prefactors to the logarithmic decay term.     

Kinetic equation for a weakly interacting classical electron gas

A kinetic equation is derived for the two-time phase space correlation function in a dilute classical electron gas in equilibrium. The derivation is based on a density expansion of the correlation function and the resummation of the most divergent terms in each order in the density. It is formally analogous to the ring summation used in the kinetic theory of neutral fluids. The kinetic equation obtained is consistent to first order in the plasma parameter and is the generalization of the linearized Balescu-Guersey-Lenard operator to describe spatially inhomogeneous equilibrium fluctuations. The importance of consistently treating static correlations when deriving a kinetic equation for an electron gas is stressed. A systematic derivation as described here is needed for a further generalization to a kinetic equation that includes mode-coupling effects. This will be presented in a future paper.